http://www.guardian.co.uk/science/2008/aug/06/genetics.korea
Future applications can be used for this field
Tuesday, August 5, 2008
Friday, August 1, 2008
German doctors have carried out a complete double arm transplant.
The patient was a 54-year-old farmer who lost his limbs in an accident six years ago.
The donor is believed to be a teenager who had died shortly before the surgery. Neither man's name has been released by the Munich clinic.
The 15-hour operation took place last week, and the patient is recovering well, though it could be two years before he can move his new hands.
Arm transplants have been carried out before - the first occurred in Austria in 2003 when a man received transplanted forearms and hands.
In this procedure, limbs were reattached just below the shoulder.
Reiner Gradinger, medical director at the Munich University Clinic where the operation involving 40 doctors, nurses and assistants took place over 15 hours last week, said: "The reattachment appears up to now to have proceeded optimally."
Surgeon Edgar Biemer said the greatest challenge was establishing blood flow between the farmer's body and muscles in the new arms because the muscles have a limited lifespan.
And he said: "We discussed with the patient that he would have to deal with the fact that his hands were from somebody else.
"But this was discussed before the first heart transplant, and in reality nobody really cared about that."
Doctors are monitoring the patient closely to make sure his body does not reject the new limbs.
Long wait
The patient cannot move his new arms but doctors hope his network of nerves will expand at a pace of around one millimetre (0.04 inches) per day.
Even if that happens, it could still be two years before the patient can manipulate his new hands.
Hans-Guenther Machens, director of hand and plastic surgery at the clinic, said: "The regeneration process will take a long time."
UK transplant expert Nadey Hakim, head of the transplant unit at London's Hammersmith Hospital, said the higher up an amputation on the arms, the easier it was to connect new limbs, as there were fewer nerves and only one bone to connect.
But he added: "It is going to be quite difficult to get any sensation. The higher it is, the harder it is.
"Flexing and bending the arm is also going to be hard."
"He is going to require intensive physiotherapy every day for many months."
The donor is believed to be a teenager who had died shortly before the surgery. Neither man's name has been released by the Munich clinic.
The 15-hour operation took place last week, and the patient is recovering well, though it could be two years before he can move his new hands.
Arm transplants have been carried out before - the first occurred in Austria in 2003 when a man received transplanted forearms and hands.
In this procedure, limbs were reattached just below the shoulder.
Reiner Gradinger, medical director at the Munich University Clinic where the operation involving 40 doctors, nurses and assistants took place over 15 hours last week, said: "The reattachment appears up to now to have proceeded optimally."
Surgeon Edgar Biemer said the greatest challenge was establishing blood flow between the farmer's body and muscles in the new arms because the muscles have a limited lifespan.
And he said: "We discussed with the patient that he would have to deal with the fact that his hands were from somebody else.
"But this was discussed before the first heart transplant, and in reality nobody really cared about that."
Doctors are monitoring the patient closely to make sure his body does not reject the new limbs.
Long wait
The patient cannot move his new arms but doctors hope his network of nerves will expand at a pace of around one millimetre (0.04 inches) per day.
Even if that happens, it could still be two years before the patient can manipulate his new hands.
Hans-Guenther Machens, director of hand and plastic surgery at the clinic, said: "The regeneration process will take a long time."
UK transplant expert Nadey Hakim, head of the transplant unit at London's Hammersmith Hospital, said the higher up an amputation on the arms, the easier it was to connect new limbs, as there were fewer nerves and only one bone to connect.
But he added: "It is going to be quite difficult to get any sensation. The higher it is, the harder it is.
"Flexing and bending the arm is also going to be hard."
"He is going to require intensive physiotherapy every day for many months."
Thursday, July 31, 2008
Exercise in a Pill
July 31, 2008 -- It may be possible to make a pill that captures the endurance-boosting effects of exercise, scientists report in Cell.
So far, they've tested two compounds in lab tests in mice. One of those compounds, called GW1516, boosted endurance in mice that exercised, but not in sedentary mice. The other compound, called AICAR, improved endurance in mice that didn't exercise at all.
Those compounds haven't yet been tested in people, and they're not on the market. But the researchers are already working on a drug test to screen for traces of GW1516 and AICAR in athletes' blood and urine.
Here's a quick look at the two compounds.
Back in 2004, the researchers -- who included professor Ronald M. Evans, PhD, of the Salk Institute for Biological Studies and the Howard Hughes Medical Institute in La Jolla, Calif. -- reported that they boosted endurance in mice by tweaking a mouse gene to boost the activity of a protein called PPAR-delta.
Evans' team then worked on getting the same result without genetic engineering. They squirted GW1516, which boosts PPAR-delta, into mice's mouths every day for a month.
At the end of the month, the mice ran 68% longer and 70% farther than when the experiment began -- but only if they had been running on exercise wheels daily while taking the drug. GW1516 didn't do anything for mice that weren't exercising.
Next, the scientists focused on another protein called AMPK. They gave sedentary mice a daily injection of AICAR, which boosts AMPK, for a month.
At the end of the month, those mice ran 23% longer and 44% farther than before starting AICAR treatment. That is, their endurance had improved without working out.
The results show that AMPK and PPAR-delta "can be targeted by orally active drugs to enhance training or even to increase endurance without exercise," write the researchers.
The mouse tests were all about skeletal muscles and endurance, not about the drugs' safety or ability to mimic the many other benefits of exercise, such as improving cardiovascular health and making some types of cancer less likely.
So far, they've tested two compounds in lab tests in mice. One of those compounds, called GW1516, boosted endurance in mice that exercised, but not in sedentary mice. The other compound, called AICAR, improved endurance in mice that didn't exercise at all.
Those compounds haven't yet been tested in people, and they're not on the market. But the researchers are already working on a drug test to screen for traces of GW1516 and AICAR in athletes' blood and urine.
Here's a quick look at the two compounds.
Back in 2004, the researchers -- who included professor Ronald M. Evans, PhD, of the Salk Institute for Biological Studies and the Howard Hughes Medical Institute in La Jolla, Calif. -- reported that they boosted endurance in mice by tweaking a mouse gene to boost the activity of a protein called PPAR-delta.
Evans' team then worked on getting the same result without genetic engineering. They squirted GW1516, which boosts PPAR-delta, into mice's mouths every day for a month.
At the end of the month, the mice ran 68% longer and 70% farther than when the experiment began -- but only if they had been running on exercise wheels daily while taking the drug. GW1516 didn't do anything for mice that weren't exercising.
Next, the scientists focused on another protein called AMPK. They gave sedentary mice a daily injection of AICAR, which boosts AMPK, for a month.
At the end of the month, those mice ran 23% longer and 44% farther than before starting AICAR treatment. That is, their endurance had improved without working out.
The results show that AMPK and PPAR-delta "can be targeted by orally active drugs to enhance training or even to increase endurance without exercise," write the researchers.
The mouse tests were all about skeletal muscles and endurance, not about the drugs' safety or ability to mimic the many other benefits of exercise, such as improving cardiovascular health and making some types of cancer less likely.
Bone Tissue Engineering
Bone tissue engineering is a rapidly developing area. This form of therapy differs from standard drug therapy or permanent implants in that the engineered bone becomes integrated within the patient, affording a potentially permanent and specific cure of the disease state. The problem with putting man-made materials in the body is that they are subject to fatigue, fracture, toxicity, and wear, and do not remodel with time. In tissue engineering for the bones, you make the cells in a culture and then place them into the patient. Cells in the body are constantly receiving mechanical, electrical, structural and chemical cues to what they should be doing. So it is important to place the cell in back into the body so that can get the cures so go in the shape and form that they are needed to be in. Bone tissue engineering can possibly for a substitute in the bone instead of using man made materials.
Bioengineered external heart
Earlier this year tissue engineers at the University of Minnesota have created the first externally engineered heart. They stripped a rat’s heart of its own cells using a kind of bleach solution. Afterwards they infused the adult rat heart cells with that of a newborn rat. This takes quite a bit of time and skill but many of the scientists argee that this is a landmark in the field of tissue engineering. Being able to engineer organs could one day result in the making of biocompatible transplant organs for patients. We are nowhere near this point right now but it is still a field of research that deserves much attention.
There are many challenges in created a working heart for humans in an external environment. First of all the heart muscle is very thick and tissue engineers have not found a way yet to ensure that enough oxygen gets to the inner layers of the heart muscle. That and creating the necessary scaffolding for a three dimensional structure is on the top of the list of major problems. The easiest part about the project is that for heart cells you don’t have to tell them to beat in synchrony because they already know to do that.
Many of the researchers at the University of Minnesota are very optimistic and hope to have a working human heart and hopefully other organs such kidneys, livers, and lungs. They wish to have at least a working one of these within 15 years. These are very optimistic propositions but nonetheless it has been a great achievement in the biomedical industry.
http://www.startribune.com/lifestyle/health/13751901.html
Sources and Cool Article
Here's my sources:
http://www.cbte.group.shef.ac.uk/research/te5.html
http://www.innovations-report.com/html/reports/medicine_health/report-42576.html
http://www.jhu.edu/JLAB/Projects/Cornea.html
And here's a cool article about sweat glands functioning as antennaes:
http://physicsworld.com/cws/article/news/33704
(The link may not work unless you make an account on their site)
http://www.cbte.group.shef.ac.uk/research/te5.html
http://www.innovations-report.com/html/reports/medicine_health/report-42576.html
http://www.jhu.edu/JLAB/Projects/Cornea.html
And here's a cool article about sweat glands functioning as antennaes:
http://physicsworld.com/cws/article/news/33704
(The link may not work unless you make an account on their site)
Corneal Tissue Engineering
Due to the fragility of the eye, a 5-30% rejection rate for donor eyes, and the complexity of creating a transducer to send image data to the brain, corneal tissue engineering is a more friendly approach to a persistent problem; how to return site to those who have lost it due to disease or damage to the eye, or in this particular case, the cornea. Currently, corneal epithelial cells from other, healthy donors can be succesfully cultured and prepared for placement on the cornea. However, these donor epithelial cells are often rejected, and a patient wanting to undergo this treatment must take immunosuppressants (though in the distant future, healthy epithelial cells might be able to be genetically engineered from the patients own epithelial cells, preventing acceptance problems). There are also significant problems with attaching these epithelial cells to the damaged cornea. Currently this area is undergoing the most thorough investigation, resulting in a variety of different methods. The most common method is to use a human amniotic membrane as a hub to which all the epithelial cells can attach, and then to suture this onto the cornea. But this method requires an amniotic membrane donor, making supply and issue two major issues. There is also a proposed method of engineering a contact lense capable of transfering the epithelial cells to the damaged sections of the cornea, which requires an acrylic acid coating on the contact lense. However, engineering a suitable contact lense requires extensive knowlege of both organ culture and surface chemical engineering, making the construction a very complex process.
Tissue Engineered Bladder
For patients with bladder disease, one of the only treatment options was the replacement of bladder tissue with intestinal tissue. Side effects of that procedure include colon cancer and infection, because the intestinal tissue is designed to absorb water rather than release water. Another option is to tissue-engineer a new bladder from cells. At Wake Forest University, doctors took a biopsy of the bladder and seeded the cells into a scaffold made of synthetic polymer. The synthetic polymer scaffold is designed to fit the patient and mimic the collagen that exists in the natural bladder. After seven weeks in an incubator, the cells colonized and the bladder was implanted about the existing bladder, where it would continue to grow and improve existing bladder function. While the procedure is still experimental and cannot repair nerve damage, it tremendously improves the lives of bladder disease patients.
Sources:
http://www.washingtonpost.com/wp-dyn/content/article/2006/04/03/AR2006040301387.html
http://news.healingwell.com/index.php?p=news1&id=531931
Sources:
http://www.washingtonpost.com/wp-dyn/content/article/2006/04/03/AR2006040301387.html
http://news.healingwell.com/index.php?p=news1&id=531931
Artificial Blood
Eric Shine
Engineering Biomedical Systems
July 31, 2008
Artificial Blood
Tissue engineering is a broad field of engineering that deals with a combination of cells, and engineering methods that are used to improve of replace biological functions. An application of tissue that could help improves or replaces biological functioning would be the creation of artificial blood. Blood is a very complicated tissue. Blood contains two main components plasma and the formed elements. To add further complexity the formed elements are made up of RBCs (red blood cells), WBCs (white blood cells), and platelets. Along with blood being the transportation system of the body, blood comes in four different types: A, B, AB, and O. Since blood Artificial blood would help traumatic brain injuries, which is a leading cause in accidental death. Even though blood is very complex engineers and scientist have made a type of artificial blood called Oxycyte. Oxycyte is a revolutionary artificial blood because it can carry 50 times more oxygen than human blood. This synthetic blood is step in making blood transfusions and other types of blood related problems a thing of the past.
http://www.popsci.com/scitech/article/2006-11/better-blood
http://health.howstuffworks.com/artificial-blood1.htm
http://en.wikipedia.org/wiki/Tissue_engineering#Examples_of_tissue_engineering_technologies
Engineering Biomedical Systems
July 31, 2008
Artificial Blood
Tissue engineering is a broad field of engineering that deals with a combination of cells, and engineering methods that are used to improve of replace biological functions. An application of tissue that could help improves or replaces biological functioning would be the creation of artificial blood. Blood is a very complicated tissue. Blood contains two main components plasma and the formed elements. To add further complexity the formed elements are made up of RBCs (red blood cells), WBCs (white blood cells), and platelets. Along with blood being the transportation system of the body, blood comes in four different types: A, B, AB, and O. Since blood Artificial blood would help traumatic brain injuries, which is a leading cause in accidental death. Even though blood is very complex engineers and scientist have made a type of artificial blood called Oxycyte. Oxycyte is a revolutionary artificial blood because it can carry 50 times more oxygen than human blood. This synthetic blood is step in making blood transfusions and other types of blood related problems a thing of the past.
http://www.popsci.com/scitech/article/2006-11/better-blood
http://health.howstuffworks.com/artificial-blood1.htm
http://en.wikipedia.org/wiki/Tissue_engineering#Examples_of_tissue_engineering_technologies
An Artificial Pancreas
Diabetes is a physically as well as mentally and emotionally devastating disease. The inability of the pancreas to efficiently produce insulin lies at the root of the diabetic problem. There are machines and pumps available today for sufferers of diabetes to track their blood glucose levels and to regulate their insulin, but the process creates constant discomfort and worry for the patient.
Tissue engineers, in their efforts, are trying to create the perfect combination of comfort and insulin production through the invention of an artificial pancreas. This artificial pancreas would be able to automatically adjust the insulin levels for a diabetic patient. It would also restore normal endocrine functionality.
The complete development and use of an artificial pancreas would improve the insulin therapy to the point at which physiological complications cease. Variations of this artificial pancreas idea have arisen among the sciences. Among them are the biomedical device ideas to implant an insulin pump that would assume the role of the pancreas, a bioartificial pancreas made of a biocompatible sheet of "encapsulated beta cells" (Wikipedia), and the use of gene therapy to convert digestive cells into insulin producing cells.
All of these projects have the common goal of creating a normal pancreas function, artificial or not, in the body. One of the benefits of tissue engineering is its more natural approach to the replacement of diseased tissues in the body.
Tissue engineers, in their efforts, are trying to create the perfect combination of comfort and insulin production through the invention of an artificial pancreas. This artificial pancreas would be able to automatically adjust the insulin levels for a diabetic patient. It would also restore normal endocrine functionality.
The complete development and use of an artificial pancreas would improve the insulin therapy to the point at which physiological complications cease. Variations of this artificial pancreas idea have arisen among the sciences. Among them are the biomedical device ideas to implant an insulin pump that would assume the role of the pancreas, a bioartificial pancreas made of a biocompatible sheet of "encapsulated beta cells" (Wikipedia), and the use of gene therapy to convert digestive cells into insulin producing cells.
All of these projects have the common goal of creating a normal pancreas function, artificial or not, in the body. One of the benefits of tissue engineering is its more natural approach to the replacement of diseased tissues in the body.
Testing Drugs with Stem Cells
Stem cells have many applications now, and there are many more that are still being developed. However, one such use of stem cells that has already been established is the use of stem cells in testing the toxicity of pharmaceutical drugs.
Previously, drugs were tested in rats before they were administered to humans. This process is somewhat flawed in that drugs have been known to act differently in humans that in the lab animals that they were previously tested on. So, a woman named Gabriella Cezar came up with a way of using embryonic stem cells to test drug toxicity. She exposed these stem cells to the drug that was being tested and then let them react. These stem cells react with drugs like a human would, eliminating the chance of poisoning a human by accident. These stem cells produce a molecule that help metabolism. Cezar hypothesized that if the drug were toxic, then there would be different amounts of that metabolic compound in the stem cells than normally.
Cezar ran another test with valproate, a drug supposed to help and epileptic patient, which has been linked with causing autism. Cezar gave different dosages to different samples of stem cells while keeping some control groups to compare to. She found that the stem cell environments with the most valproate produced the most glutamate and kynurenin; both are used in brain development.
Even though this method of using stem cells is not an exact science yet, it is up and coming application of stem cells.
Heart in a Jar
Tissue engineering's whole purpose is to replace biological functions with new cell material products. Mostly, tissue engineers try to repair portions of organs that have been damaged. However, earlier this year, Doris Taylor made medical history by creating an entirely new rat heart in a lab. This beating heart was made by leaving only nonliving matrix of the rat's heart and redesigning it with new heart cells. To first remove all the cells to get to the matrix, detergents were pumped throughout the organ to wash away the debris in the network of blood vessels. This left the extracellular matrix or ECM as a matrix of protein fibers that create the connective tissue in the heart. This ECM was basically a skeleton of the organ's 3-D structure that was then formed into a heart with new cells. These cells were a mix of stem and progenitor cells from newborn rats that were injected into the left ventricle of the ECM. After pumping nutrients and oxygen throughout the heart and its blood vessels, four days later the heart starting contracting. The heart was then stimulated by electrodes to synchronize the beats. Taylor is continuing her study with experimenting with pig hearts and their own ECM. The hope is that one day new hearts will be creating for the 5 million people living with heart failure. This new advancement in tissue engineering could someday make organ transplants obsolete.
http://en.wikipedia.org/wiki/Doris_Taylor
http://www1.umn.edu/umnnews/Feature_Stories/Researchers_create_a_new_heart_in_the_lab.html
http://en.wikipedia.org/wiki/Doris_Taylor
http://www1.umn.edu/umnnews/Feature_Stories/Researchers_create_a_new_heart_in_the_lab.html
Gene Therapy
Gene therapy is a form of treatment that doctors and scientists hope to use against genetic diseases. Instead of battling a foreign body, which is not the source of problems in genetic diseases, the goal in gene therapy is to replace faulty genes causing illness in patients with correct ones. What one uses to replace the old gene with the new one is called a vector. There are many different vectors for placement of new genes, such as using viruses, naked-DNA injection, dendrimers, and others.
The first approved gene therapy procedure was performed in 1990. It was meant to treat severe combined immunodeficiency, or SCID, a genetic disease in which certain receptors on white blood cells are not correctly coded for in the corresponding gene, rendering white blood cells useless. Doctors removed white blood cells from the patient, a four year old girl, let the cells develop in cultures, then inserted the correct gene into the cells and put the cells back into the patient. Even though the procedure only lasted a couple months, it boosted the patient's immune system so much that she could now attend school, which she previously couldn't do due to her extremely high risk of fatal infections from what are considered mundane conditions, such as colds. This case shows promise for gene therapy, even if results aren't permanent.
http://en.wikipedia.org/wiki/Gene_therapy
http://en.wikipedia.org/wiki/Severe_combined_immunodeficiency
The first approved gene therapy procedure was performed in 1990. It was meant to treat severe combined immunodeficiency, or SCID, a genetic disease in which certain receptors on white blood cells are not correctly coded for in the corresponding gene, rendering white blood cells useless. Doctors removed white blood cells from the patient, a four year old girl, let the cells develop in cultures, then inserted the correct gene into the cells and put the cells back into the patient. Even though the procedure only lasted a couple months, it boosted the patient's immune system so much that she could now attend school, which she previously couldn't do due to her extremely high risk of fatal infections from what are considered mundane conditions, such as colds. This case shows promise for gene therapy, even if results aren't permanent.
http://en.wikipedia.org/wiki/Gene_therapy
http://en.wikipedia.org/wiki/Severe_combined_immunodeficiency
Wednesday, July 30, 2008
Bioartificial Liver Devices
One tissue engineering device is the Bioartificial Liver Device (BAL). There are two BAL's currently in clinical trials, they are the HepatAssist 2000 and the ELAD. The aim of both of these devices is either as a bridge to transplant, or as a means of letting the liver regenerate on it's own. Both perform these tasks rather well, but both differ in the method used to do this.
The HepatAssist 2000 is an extracorporeal device with hollow tubes and pig liver tissue samples that filters the plasma. This is good as plasma has a better flow rate, there is a greater molecular transfer rate, and there is decreased intracranial pressure. The down side is that pig cells create pig proteins which may cause immune responses, the plasma separation process can also cause problems.
The ELAD uses filtration cartridges much like kidney dialysis. These tubes contained hollow fibers with cloned human cells that are cultured in them. The ELAD is good as it mimics many of the natural liver functions like metabolizing amino acids and producing proteins and clotting factors. The down side of this product could be the fact that it doesn't have the better flow rates that the HepatAssist 2000 has.
http://www.medscape.com/viewarticle/420583
The HepatAssist 2000 is an extracorporeal device with hollow tubes and pig liver tissue samples that filters the plasma. This is good as plasma has a better flow rate, there is a greater molecular transfer rate, and there is decreased intracranial pressure. The down side is that pig cells create pig proteins which may cause immune responses, the plasma separation process can also cause problems.
The ELAD uses filtration cartridges much like kidney dialysis. These tubes contained hollow fibers with cloned human cells that are cultured in them. The ELAD is good as it mimics many of the natural liver functions like metabolizing amino acids and producing proteins and clotting factors. The down side of this product could be the fact that it doesn't have the better flow rates that the HepatAssist 2000 has.
http://www.medscape.com/viewarticle/420583
Gene Therapy
Genes, which are carried on chromosomes, are the basic physical and functional units of heredity. Genes are specific sequences of bases that encode instructions on how to make proteins. Although genes get a lot of attention, it’s the proteins that perform most life functions and even make up the majority of cellular structures. When genes are altered so that the encoded proteins are unable to carry out their normal functions, genetic disorders can result. Gene therapy is a technique for correcting defective genes responsible for disease development. Researchers use several approaches for correcting faulty genes including:
· inserting a normal gene into a nonspecific location within the genome to replace a nonfunctional gene
· swapping an abnormal gene for a normal gene through homologous recombination
· repairing the abnormal gene through selective reverse mutation
In most gene therapy studies, a "normal" gene is inserted into the genome to replace an "abnormal," disease-causing gene. A carrier molecule called a vector must be used to deliver the therapeutic gene to the patient's target cells. Currently, the most common vector is a virus that has been genetically altered to carry normal human DNA. Viruses have evolved a way of encapsulating and delivering their genes to human cells in a pathogenic manner. Scientists have tried to take advantage of this capability and manipulate the virus genome to remove disease-causing genes and insert therapeutic genes.
· inserting a normal gene into a nonspecific location within the genome to replace a nonfunctional gene
· swapping an abnormal gene for a normal gene through homologous recombination
· repairing the abnormal gene through selective reverse mutation
In most gene therapy studies, a "normal" gene is inserted into the genome to replace an "abnormal," disease-causing gene. A carrier molecule called a vector must be used to deliver the therapeutic gene to the patient's target cells. Currently, the most common vector is a virus that has been genetically altered to carry normal human DNA. Viruses have evolved a way of encapsulating and delivering their genes to human cells in a pathogenic manner. Scientists have tried to take advantage of this capability and manipulate the virus genome to remove disease-causing genes and insert therapeutic genes.
Stem Cells to Cure Parkinson's
Scientists have been working with stem cells since the 1980s, continuously searching to find functional benefits of the relatively new technology. In 2007 and article, “Stem Cells Make Neurons, and Tumors, in Rate Model of Parkinson’s Disease,” was released stating that “human embryonic stem cells led to dramatic functional improvement” although it was also shown to cause brain tumors. Research was done to determine whether stem cells could help cure Parkinson’s disease (PD). PD causes muscles to stiffen and a person’s movement to slow. It is believed that stem cells could help PD because it is a disease that damages few neurons which produce dopamine.
An experiment performed by Steven Goldman, M.D., Ph.D., at the University of Rochester Medical Center described how the stem cells were induced to become dopamine producing neurons. The cells were placed in rats with a condition similar to PD and the rats recovered their mobile functions. Along with the recovery, however, a tiny amount of the implanted cells had formed tumors. Stem cells had been produced in the past that showed therapeutic effects for PD, but the study was the first to show that cells derived from humans are able to produce positive effects as well as those cells derived from animals.
The study was continued with the use of a toxin that destroyed dopamine producing neurons being implanted into rats before any problems with movement existed. The rats were treated with the stem cells and showed to perform as well as rats that had not received the toxin within a few months. Dr. Goldman believes that all the team needs to do it find a way “‘to purify the neurons and separated them from the undifferentiated cells.’” The results from Dr. Goldman’s experiment are promising despite the fact that some tumors had formed on a few cells. The field of stem cell therapeutics is rapidly growing.
http://www.ninds.nih.gov/news_and_events/news_articles/stem_cells_improve_PD.htm
An experiment performed by Steven Goldman, M.D., Ph.D., at the University of Rochester Medical Center described how the stem cells were induced to become dopamine producing neurons. The cells were placed in rats with a condition similar to PD and the rats recovered their mobile functions. Along with the recovery, however, a tiny amount of the implanted cells had formed tumors. Stem cells had been produced in the past that showed therapeutic effects for PD, but the study was the first to show that cells derived from humans are able to produce positive effects as well as those cells derived from animals.
The study was continued with the use of a toxin that destroyed dopamine producing neurons being implanted into rats before any problems with movement existed. The rats were treated with the stem cells and showed to perform as well as rats that had not received the toxin within a few months. Dr. Goldman believes that all the team needs to do it find a way “‘to purify the neurons and separated them from the undifferentiated cells.’” The results from Dr. Goldman’s experiment are promising despite the fact that some tumors had formed on a few cells. The field of stem cell therapeutics is rapidly growing.
http://www.ninds.nih.gov/news_and_events/news_articles/stem_cells_improve_PD.htm
Artificial Blood Vessels
Artificial blood vessels were first introduced during WWI when Alexis Carrel discovered a way to sew blood vessels together. Today, methods from the 1940s and 1950s are still used. Surgeons originally used transplants for arteries or veins. However, this method resulted in failure. The recipient’s body either rejected the vessels or arteriosclerosis (artery hardening) formed. To transplant vessels from the same body required two complicated surgeries and most patients with circulatory problems did not have vessels for transplantation.
Researchers began to develop artificial vessels to overcome this problem. Tubing materials included polyethylene (soft and waxy plastic) and siliconized rubber. Further research proved that vessels made from Teflon and Dacron were not rejected by the body. While the larger Dacron vessels worked well, the smaller ones formulated blood clots. Smoother interior walls would help prevent clots from forming.
In the 1980s, Donald Lyman synthesized a polymer that reduced clot formation. The elastic polymer also reduced the strain where the natural and artificial valves met. Human testing began in 1988. In 1990, the bio-research company Organogenesis implanted a hybrid vessel in animals made of natural and artificial materials. This artificial vessel features a smooth inner layer grown in the laboratory from human cadaver (dead body) artery cells and tubules strengthened with Dacron mesh. Stuart Williams at Jefferson Medical College, Philadelphia, Pennsylvania, uses cells from the patient's own inner blood vessel lining to grow a lining on the inside of Dacron synthetic vessels.
Researchers have already managed to make wider blood vessels from scratch, but the formation of the tiny diameter capillaries needed to create a blood supply within other tissues and organs is more challenging. However, through the “nanoscale” template, US scientists claim to have made progress using stem cells using endothelial progenitor. These cells detect the grooves and align themselves in the direction of the vessel. When a gel is added, the cells grow outward consequently forming tiny tubes. Even though these tubes are not ready to be placed inside the body, researchers cannot contain their enthusiasm for the potential results of this process.
http://www.discoveriesinmedicine.com/Apg-Ban/Artificial-Blood-Vessels.html
http://news.bbc.co.uk/2/hi/health/7152405.stm
Researchers began to develop artificial vessels to overcome this problem. Tubing materials included polyethylene (soft and waxy plastic) and siliconized rubber. Further research proved that vessels made from Teflon and Dacron were not rejected by the body. While the larger Dacron vessels worked well, the smaller ones formulated blood clots. Smoother interior walls would help prevent clots from forming.
In the 1980s, Donald Lyman synthesized a polymer that reduced clot formation. The elastic polymer also reduced the strain where the natural and artificial valves met. Human testing began in 1988. In 1990, the bio-research company Organogenesis implanted a hybrid vessel in animals made of natural and artificial materials. This artificial vessel features a smooth inner layer grown in the laboratory from human cadaver (dead body) artery cells and tubules strengthened with Dacron mesh. Stuart Williams at Jefferson Medical College, Philadelphia, Pennsylvania, uses cells from the patient's own inner blood vessel lining to grow a lining on the inside of Dacron synthetic vessels.
Researchers have already managed to make wider blood vessels from scratch, but the formation of the tiny diameter capillaries needed to create a blood supply within other tissues and organs is more challenging. However, through the “nanoscale” template, US scientists claim to have made progress using stem cells using endothelial progenitor. These cells detect the grooves and align themselves in the direction of the vessel. When a gel is added, the cells grow outward consequently forming tiny tubes. Even though these tubes are not ready to be placed inside the body, researchers cannot contain their enthusiasm for the potential results of this process.
http://www.discoveriesinmedicine.com/Apg-Ban/Artificial-Blood-Vessels.html
http://news.bbc.co.uk/2/hi/health/7152405.stm
Use of Gene Therapy for Dwarfism
Alexis Gorin
Farah Laiwalla
Engineering Biomedical Systems (BI920-3B)
Wednesday, July 30, 2008
To treat dwarfism, the condition of abnormally-caused small stature, doctors use gene therapy as an option to help people affected, using growth hormone and any other hormone the person may be missing. The amount of each type of hormone given constantly changes though due to (metabolic) changes within the child (1).
Different drug deliveries systems are used to get the growth hormone in the body systems. One way, used by doctors like Jeffery M. Leiden, is to remove muscle cells and place the gene that makes HGH inside the cells, only to be placed back inside the body (2). This method has become very effective since new research came out, proving that muscle cells can secrete proteins. The study shows that after three months, the mice the manipulated muscle cells were put in were still making HGH.
Another way to deliver the needed hormones, although can be used for other purposes, is to put the hormone-creating gene into "replication-deficient retrovirus" (3). The virus then can attach to muscle cells and has its host cell copy the hormone-creating genetic material, have the material build up, and then spread to other cells. This was created by Vandenburgh as a way to deal without constant injections of proteins.
(1) "Dwarfism." Free Health Encyclopedia. 2007. NetIndustries, LLC. . 30 Jul 2008 http://www.faqs.org/health/topics/99/Dwarfism.html.
(2) Angier, Natalie. "With Direct Injections, Gene Therapy Takes A Step Into a New Age ." The New York Times 14 April 1992 30 Jul 2008 http://query.nytimes.com/gst/fullpage.html?res=9E0CE6DB1E3BF937A25757C0A964958260&sec=&spon=&pagewanted=all.
(3) "Gene Therapy - Putting Muscle Into the Research." NASA. 06 June 2002. NASA. 30 Jul 2008 http://www.nasa.gov/vision/earth/livingthings/gene_therapy_prt.htm.
Farah Laiwalla
Engineering Biomedical Systems (BI920-3B)
Wednesday, July 30, 2008
To treat dwarfism, the condition of abnormally-caused small stature, doctors use gene therapy as an option to help people affected, using growth hormone and any other hormone the person may be missing. The amount of each type of hormone given constantly changes though due to (metabolic) changes within the child (1).
Different drug deliveries systems are used to get the growth hormone in the body systems. One way, used by doctors like Jeffery M. Leiden, is to remove muscle cells and place the gene that makes HGH inside the cells, only to be placed back inside the body (2). This method has become very effective since new research came out, proving that muscle cells can secrete proteins. The study shows that after three months, the mice the manipulated muscle cells were put in were still making HGH.
Another way to deliver the needed hormones, although can be used for other purposes, is to put the hormone-creating gene into "replication-deficient retrovirus" (3). The virus then can attach to muscle cells and has its host cell copy the hormone-creating genetic material, have the material build up, and then spread to other cells. This was created by Vandenburgh as a way to deal without constant injections of proteins.
(1) "Dwarfism." Free Health Encyclopedia. 2007. NetIndustries, LLC. . 30 Jul 2008 http://www.faqs.org/health/topics/99/Dwarfism.html.
(2) Angier, Natalie. "With Direct Injections, Gene Therapy Takes A Step Into a New Age ." The New York Times 14 April 1992 30 Jul 2008 http://query.nytimes.com/gst/fullpage.html?res=9E0CE6DB1E3BF937A25757C0A964958260&sec=&spon=&pagewanted=all.
(3) "Gene Therapy - Putting Muscle Into the Research." NASA. 06 June 2002. NASA. 30 Jul 2008 http://www.nasa.gov/vision/earth/livingthings/gene_therapy_prt.htm.
Bone Scaffolds
Marissa Reitsma
7/30/08
Bone Scaffolds
http://www.acfnewsource.org/science/bone_scaffold.html
http://www.rsc.org/Publishing/Journals/cb/Volume/2007/1/Bone-buildingscaffold.asp
Stem Cell application
A stem cell is a kind of cell produced in a four-five day old fetus, called a blastocyst, which hasn't been assigned a specific purpose in the body yet. This "unassigned" cell allows researchers to implant stem cells into dying patients to improve impaired body parts and organs. Stem cell applications, whether embryonic, adult or pluripotent, is a huge breakthrough in modern-day scientific research. For scientists, stem cells are very vital to understanding how the body works and how to improve certain body tissues and cells. As of now, the goverment is not funding adequate amounts of money to pave the way for uses for stem cells, due to ethical problems. Yet, researchers have found that stem cells can help with numerous diseases and illnesses, ranging from cancer to a "broken heart" to glaucoma.
Stem cells can be transplanted into a patient, therefore completely eliminating the problem of a non-working body organ. Stem cells can also fix chromosomal abnormalities at birth.
Stem cells can be transplanted into a patient, therefore completely eliminating the problem of a non-working body organ. Stem cells can also fix chromosomal abnormalities at birth.
Monday, July 28, 2008
interesting article about artificial joints
http://www.nytimes.com/2008/07/29/business/29hip.html?_r=1&hp&oref=slogin
Thursday, July 24, 2008
Retinal Prosthesis
There are two major categories of retinal prosthesis’ known as subretinal and epiretinal prosthesis, and they differ in the location of their light receptors. As their names imply, subretinal means the artificial photoreceptors are located underneath the retina, and epiretinal means they are on top of the retina. Based on these characteristics alone, the subretinal would seem to be the wisest choice for a patient wanting to restore their vision; having eyes outside of your head is unnatural and makes them more prone to damage. Neither can you move them like you can your eyes. However, there are differences in their safety and ultimate effectiveness that go beyond the simple location of the light receptors.
Namely, these differences have to do with the way in which the device is connected to the brain. The major ways in which you can connect prosthesis with the brain are: 1 Implanting a MEMS (Micro Electrical Mechanical System) in the retina 2 Implanting a MEMS in the optic nerve 3 Implanting a MEMS into the skull 4 Implanting a hybrid retinal device. Out of all these methods, the most sophisticated and promising seems to be the hybrid retinal device for the following reasons.
Normal retinal and optic nerve implants cannot work if ganglion cells and the optic nerve are damaged, and would not be able to assist a majority of patients who suffer blindness. However, the solution for this problem, placing a MEMS in the skull, is a complex and dangerous procedure due mainly for increased chance of cell proliferation, whereas retinal and optic nerve implants can be installed/fixed with common and relatively safe procedures. Though there are others problems with all these implants, including power supply, difficulty in signal transmission, blurred images, and wear of artificial material, a hybrid retinal device succeeds where the other three do not; it is a relatively safe procedure and it does not require the optic nerve and/or retina to be intact. Like a cortical implant, it is epiretinal (a small put down, but in comparison to its advantages, insignificant), but unlike a cortical implant it uses neural grafts to build a connection through the damaged retina. The surgery required to implant it would be similar to retinal and optic nerve MEMS’, making it safer, and, when compared to other methods of connecting visual prosthesis, the obvious choice for the job.
Namely, these differences have to do with the way in which the device is connected to the brain. The major ways in which you can connect prosthesis with the brain are: 1 Implanting a MEMS (Micro Electrical Mechanical System) in the retina 2 Implanting a MEMS in the optic nerve 3 Implanting a MEMS into the skull 4 Implanting a hybrid retinal device. Out of all these methods, the most sophisticated and promising seems to be the hybrid retinal device for the following reasons.
Normal retinal and optic nerve implants cannot work if ganglion cells and the optic nerve are damaged, and would not be able to assist a majority of patients who suffer blindness. However, the solution for this problem, placing a MEMS in the skull, is a complex and dangerous procedure due mainly for increased chance of cell proliferation, whereas retinal and optic nerve implants can be installed/fixed with common and relatively safe procedures. Though there are others problems with all these implants, including power supply, difficulty in signal transmission, blurred images, and wear of artificial material, a hybrid retinal device succeeds where the other three do not; it is a relatively safe procedure and it does not require the optic nerve and/or retina to be intact. Like a cortical implant, it is epiretinal (a small put down, but in comparison to its advantages, insignificant), but unlike a cortical implant it uses neural grafts to build a connection through the damaged retina. The surgery required to implant it would be similar to retinal and optic nerve MEMS’, making it safer, and, when compared to other methods of connecting visual prosthesis, the obvious choice for the job.
Epiretinal and Subretinal implants
I believe that the epiretinal implant will work the best in patients. It does not require any intact optics, which would prove more useful in patients who have little to no vision at all. The ganglia are directly stimulated with an epiretinal implant, while the subretinal implant uses the remaining neurons of the old retinal network. The epiretinal implant is much harder to fix in place, but it provides better “connections” to the brain. It is simply a readout chip that receives signals from an external camera, which is simpler than the subretinal device which actually contains light sensors. Both devices have shown the ability to be biocompatible with cats, proving that one day they might be suitable for human use.
Sources
"Retinal implant." Wikipedia, The Free Encyclopedia. 25 Feb 2008, 21:29 UTC. Wikimedia Foundation, Inc. 24 Jul 2008.
Will Retinal Implants Restore Vision?
Eberhart Zrenner (8 February 2002)
Science 295 (5557), 1022. [DOI: 10.1126/science.1067996]
Sources
"Retinal implant." Wikipedia, The Free Encyclopedia. 25 Feb 2008, 21:29 UTC. Wikimedia Foundation, Inc. 24 Jul 2008
Will Retinal Implants Restore Vision?
Eberhart Zrenner (8 February 2002)
Science 295 (5557), 1022. [DOI: 10.1126/science.1067996]
Epiretinal Implant
I think that epiretinal implants will work the best in the future. Epiretinal prosthesis chronically implanted in blind patients allows them to perceive discrete phosphenes and perform visual spatial tasks. According to a presentation at the Cannes Retina Festival 24th Annual Meeting of the American Society of Retina Specialists (ASRS) & 6th Annual Meeting of the European Vitreoretinal Society (EVRS), held in Cannes, France, five patients implanted with the device (Second Sight Medical Products, Sylmar, Calif) continue to use it daily. “These patients are using the prosthesis to perform tasks such as finding doorways, following the action in sporting events, navigating, following individuals, locating objects across the room and eating,” said Robert J. Greenberg, MD, PhD, president and CEO of Second Sight..
Epiretinal Prosthesis Shows Promise for Blind Patients
BY CONNI BERGMANN KOURY, EDITOR-IN-CHIEF
Epiretinal Prosthesis Shows Promise for Blind Patients
BY CONNI BERGMANN KOURY, EDITOR-IN-CHIEF
Subretinal Implants
After examining the various types of retinal implants, the subretinal implant appears to be the best choice. Unlike the epiretinal and hybrid implants, the subretinal does not have any external devices. The majority of patients tend to feel more comfortable about having operations if they will appear the same afterwards; it feels more normal for patients to have only internal devices. The subretinal implant appears more normal and functions closer to how a healthy retina actually functions.
In a subretinal implant light is taken from the environment directly, similar to how a healthy retina does. The light received is then converted into electrical signals which stimulate the cell layers that are still capable. Unlike the subretinal, the epiretinal implant uses a sensor to encode information as electrical impulses; thus making the epiretinal implant more complex than is necessary. Not only is the epiretinal implant more complex in its information processing, but it is much more difficult to fix. Although the hybrid retinal implant appears to be an idea that could function well as it combines some of the better aspects of other retinal implants, there is not sufficient experimental data for me to support the implant. The implant that is most similar to an actual retina is the subretinal implant; therefore it is more likely to have better results because it uses the biological functions available.
References:
http://www.opticsreport.com/content/article.php?article_id=1007
http://www.sciencemag.org/cgi/content/full/295/5557/1022
http://ieeexplore.ieee.org/iel5/6569/17543/00812432.pdf?arnumber=812432
In a subretinal implant light is taken from the environment directly, similar to how a healthy retina does. The light received is then converted into electrical signals which stimulate the cell layers that are still capable. Unlike the subretinal, the epiretinal implant uses a sensor to encode information as electrical impulses; thus making the epiretinal implant more complex than is necessary. Not only is the epiretinal implant more complex in its information processing, but it is much more difficult to fix. Although the hybrid retinal implant appears to be an idea that could function well as it combines some of the better aspects of other retinal implants, there is not sufficient experimental data for me to support the implant. The implant that is most similar to an actual retina is the subretinal implant; therefore it is more likely to have better results because it uses the biological functions available.
References:
http://www.opticsreport.com/content/article.php?article_id=1007
http://www.sciencemag.org/cgi/content/full/295/5557/1022
http://ieeexplore.ieee.org/iel5/6569/17543/00812432.pdf?arnumber=812432
Subretinal Implants
Subretinal implants is a device which is implanted between the pigment epithelial layer and the outer layer of the retina. Many microelectrodes are placed onto a very thin plate which is then inserted under the retina. Light which falls on the retina activates a current resulting in a stimulation of sensory neurons from the retina. The information is sent directly then to the optic nerve exactly like a normal eye. This subretinal implant directly mimics the natural function of the retina, thus making this procedure better than the epiretinal implant. With the subretinal implant, the eye can function normally without any wires hanging around.
Subretinal implants have a promising future because they can fix the problem with the most efficency and ease.
http://www.opticsreport.com/content/article.php?article_id=1007
Subretinal implants have a promising future because they can fix the problem with the most efficency and ease.
http://www.opticsreport.com/content/article.php?article_id=1007
Subretinal Implants
Eric Shine
Engineering Biomedical Systems
July 24, 2008
Subretinal Implants
The subretinal implant strategy will likely work the best in the future. Subretinal devices contain hundreds to thousands of light sensitive microphotodiodes that get stimulated by light. The stimulation passes from the photodiodes to microelectrodes that send the electrical signal to the optic nerve; from the there the signal goes to the visual cortex of the brain. Subretinal prostheses have a number of advantages over epiretinal devices. One is that the microphotodiodes placed directly over the damaged photoreceptor cells. Also since these devices do not rely on wireless interfacing with an external camera the signals between the devices the chances of a disturbance is less likely to happen. Another advantage with subretinal prosthesis is because the person with the device can still focus on objects with there eyes.Also there are aesthetic advantages has well, people do not have to where glasses with camera which could be unpleasing, as well, people who have epiretinal implants have to maintain, and keep up with the camera / glasses. One major downside to having either subretinal / epiretinal impants, the networking between the retina and the brain via the optic nerve must not be damaged.
Currently subretinal devices under testing that use the light received through the eye as a power source, like a solar panel; even though it is not the most powerful devices on the market, compared to an epiretinal and subretinal devices that have an external powersource, this type of device shows the most promise. This type of subretinal device would only have to consist of one chip that would contain a power source, mircoelectrodes and microphotodiodes. Since this type of device would only require one chip methods for implanting this device could be improved to make surgery less complicated and less time consuming. I believe this type of retinal device is the better of the two because it is less noticeable, it has a simple design, and the imaging capability is comparable to an epiretinal device.
References:
www.sciencemag.org/cgi/content/full/295/5557/1022
ieeexplore.ieee.org/iel5/2220/35447/01683653.pdf
Engineering Biomedical Systems
July 24, 2008
Subretinal Implants
The subretinal implant strategy will likely work the best in the future. Subretinal devices contain hundreds to thousands of light sensitive microphotodiodes that get stimulated by light. The stimulation passes from the photodiodes to microelectrodes that send the electrical signal to the optic nerve; from the there the signal goes to the visual cortex of the brain. Subretinal prostheses have a number of advantages over epiretinal devices. One is that the microphotodiodes placed directly over the damaged photoreceptor cells. Also since these devices do not rely on wireless interfacing with an external camera the signals between the devices the chances of a disturbance is less likely to happen. Another advantage with subretinal prosthesis is because the person with the device can still focus on objects with there eyes.Also there are aesthetic advantages has well, people do not have to where glasses with camera which could be unpleasing, as well, people who have epiretinal implants have to maintain, and keep up with the camera / glasses. One major downside to having either subretinal / epiretinal impants, the networking between the retina and the brain via the optic nerve must not be damaged.
Currently subretinal devices under testing that use the light received through the eye as a power source, like a solar panel; even though it is not the most powerful devices on the market, compared to an epiretinal and subretinal devices that have an external powersource, this type of device shows the most promise. This type of subretinal device would only have to consist of one chip that would contain a power source, mircoelectrodes and microphotodiodes. Since this type of device would only require one chip methods for implanting this device could be improved to make surgery less complicated and less time consuming. I believe this type of retinal device is the better of the two because it is less noticeable, it has a simple design, and the imaging capability is comparable to an epiretinal device.
References:
www.sciencemag.org/cgi/content/full/295/5557/1022
ieeexplore.ieee.org/iel5/2220/35447/01683653.pdf
The Best kinds of Retinal Implants
The most prevalent forms of retinal implants in this day of increasing research in the area are the epiretinal and subretinal implants. In reality, neither is perfect, and both have their positives and negatives, just as you would expect from a growing field of research. But in my opinion, the aspects of one clearly outweigh the other. I believe that overall positive aspects of the epiretinal implant make it the retinal implant of choice in these situations of medical blindness.
The epiretinal implant is one that is placed in the inner retinal membrane. It requires no photoreceptors and relies upon an external camera of sorts to send it information that it can later relay to the ganglions in the eye by way of electrodes. The obvious limitations to this lie in its reliance on external sources of infomation, rather than the neurons of the optic nerve itself, as does the subretinal implant, which is placed between the pigment epithelial layer and the outer layer of the retina. But I also believe that therein lies the appeal to the epiretinal implant. The fact that it wouldn't need to rely on possibly diseased or dying cells makes it at least seem more efficient.
Among the detractors to the epiretinal implants is the fact that because they rely on an external source, the device itself must do the extraordinarily difficult task of interpreting the visual information into electrical signals and commands. Despite this enormous task, the epiretinal seems to me to be the better option considering that it mustn't rely on damaged cells. The use of external cameras and their images (if interpreted properly) also "optimizes the signal received by the implants" (Optics Report).
Of course, assumptions should be made lightly concerning these implants, especially during their experimental phases. The best information and determination will come later from human testing (when approved), seeing as the implants have seen most of their testing in blind and healthy rats, cats, and dogs.\
The epiretinal implant is one that is placed in the inner retinal membrane. It requires no photoreceptors and relies upon an external camera of sorts to send it information that it can later relay to the ganglions in the eye by way of electrodes. The obvious limitations to this lie in its reliance on external sources of infomation, rather than the neurons of the optic nerve itself, as does the subretinal implant, which is placed between the pigment epithelial layer and the outer layer of the retina. But I also believe that therein lies the appeal to the epiretinal implant. The fact that it wouldn't need to rely on possibly diseased or dying cells makes it at least seem more efficient.
Among the detractors to the epiretinal implants is the fact that because they rely on an external source, the device itself must do the extraordinarily difficult task of interpreting the visual information into electrical signals and commands. Despite this enormous task, the epiretinal seems to me to be the better option considering that it mustn't rely on damaged cells. The use of external cameras and their images (if interpreted properly) also "optimizes the signal received by the implants" (Optics Report).
Of course, assumptions should be made lightly concerning these implants, especially during their experimental phases. The best information and determination will come later from human testing (when approved), seeing as the implants have seen most of their testing in blind and healthy rats, cats, and dogs.\
- "Will retinal implants restore vision?". Zrenner, Eberhart. Science 2002.
. - "Optoelectronic implants to treat visual diseases." Optics report. June 14, 2003.
Subretinal VS Epiretinal
Subretinal
-All replacements are made within the eye, no external device needed
-Replaces the rods and cones with silicon plate containing light sensitive microphotodiodes attached to an electrode
-light stimulates the microphotodiodes which then sends a message from the electrode to the remaining neural cells
Epiretinal
-Uses an external camera to receive electrical signals
-Electrodes from the implant then stimulate directly stimulate the axons that form on the optic nerve
I think that Epiretinal Implants would work the best, but Subretinal Implants are ideal. I believe Epiretinal implants would work better simply for the reason that less can go wrong and it is easier to repair if something does in fact go wrong. If a subretinal implant malfunctions, to repair it a doctor must go into the eye every time, unlike if a Epiretinal Implant malfunctions. However, for the patient, Subretinal Implants would be the best option, simply on account of appearance and convenience. Personally, I would not wan't to walk around with a camera on my head and wires running from the camera to my eye. So, at the moment, I feel that Epiretinal implant are more plausible, but in the future Subretinal Implants will be most desired.
-All replacements are made within the eye, no external device needed
-Replaces the rods and cones with silicon plate containing light sensitive microphotodiodes attached to an electrode
-light stimulates the microphotodiodes which then sends a message from the electrode to the remaining neural cells
Epiretinal
-Uses an external camera to receive electrical signals
-Electrodes from the implant then stimulate directly stimulate the axons that form on the optic nerve
I think that Epiretinal Implants would work the best, but Subretinal Implants are ideal. I believe Epiretinal implants would work better simply for the reason that less can go wrong and it is easier to repair if something does in fact go wrong. If a subretinal implant malfunctions, to repair it a doctor must go into the eye every time, unlike if a Epiretinal Implant malfunctions. However, for the patient, Subretinal Implants would be the best option, simply on account of appearance and convenience. Personally, I would not wan't to walk around with a camera on my head and wires running from the camera to my eye. So, at the moment, I feel that Epiretinal implant are more plausible, but in the future Subretinal Implants will be most desired.
Retinal Implants
Retinal Implants
Over the course of time the subretinal devices will surpass the effectiveness of epiretnal and cortical ones. A rule of biomedical engineering is to try and make the device as simple as possible. This way less things can possibly go wrong because the more things you try to mimic the more room there is for error. The cortical implants replace more organs than the subretinal and epiretnal ones. The optic nerve is used to convert collected light into electrical signals. In cortical devices the programmers have to do this on their own. There is a much better chance that the already present optic nerve would create a better mental image than a programmer trying to understand the body’s encoding system. Also in epiretnal devices a similar process goes on in which a “smart” computer chip has to convert stimuli from an external camera into electrical impulses that the brain can understand. Another problem with the other two devices is that they are not utilizing something very complicated and effective that is already there, the other part of the retina that is not damaged. Using the actual retina instead of an external camera would help the patient have a better sense of real eyesight. With cameras on glasses the patient would only get a forward view and would not get the advantages of peripheral vision. Subretinal devices would allow the person to “look around” by actually moving their eyes without having to move their head. It is this advantage of utilizing the already present organs and reducing the complexity of the device that will make the subretinal devices superior to the others.
Over the course of time the subretinal devices will surpass the effectiveness of epiretnal and cortical ones. A rule of biomedical engineering is to try and make the device as simple as possible. This way less things can possibly go wrong because the more things you try to mimic the more room there is for error. The cortical implants replace more organs than the subretinal and epiretnal ones. The optic nerve is used to convert collected light into electrical signals. In cortical devices the programmers have to do this on their own. There is a much better chance that the already present optic nerve would create a better mental image than a programmer trying to understand the body’s encoding system. Also in epiretnal devices a similar process goes on in which a “smart” computer chip has to convert stimuli from an external camera into electrical impulses that the brain can understand. Another problem with the other two devices is that they are not utilizing something very complicated and effective that is already there, the other part of the retina that is not damaged. Using the actual retina instead of an external camera would help the patient have a better sense of real eyesight. With cameras on glasses the patient would only get a forward view and would not get the advantages of peripheral vision. Subretinal devices would allow the person to “look around” by actually moving their eyes without having to move their head. It is this advantage of utilizing the already present organs and reducing the complexity of the device that will make the subretinal devices superior to the others.
Retinal Impants
Retinal implants are a new technological advance that is used to help patients see that lost their sight due to degenerative eye conditions. People with degenerative eye conditions loose there site due to the retinal cells losing their ability to sense light. The retinal implants help take over for the job of sensing the light. The next generation of retinal implants that has just received approval from the FDA, is a tiny chip with tiny hair-like electrodes. When the chip is implanted in the retina, it sends messages to the neural cells in the brain that send the information to the brain.
The result of the new generation of retinal implants seems very promising. The new generation of retinal implants almost quadrupled the number of electrodes from 16 to 60. Having a device with 60 electrodes is does not give the patient very clear vision better than having nothing. I believe the retinal implants have a very promising future. It may take many years to have an advancement that would let people see very clearly, but I think with the retinal implants it can be possible.
http://www.technologyreview.com/Biotech/18193/page2/
http://en.wikipedia.org/wiki/Retinal_implant
Subretinal Implants
Subretinal Implants
Dennis Xuan
Subretinal Implants are placed behind the retina and act as closely as possible to normal, healthy retinas. The subretinal implants mimic a normal retina’s ability to take in light and converts the information into electrical signals that are sent to the rest of the eye for processing. After that the information is sent down the optic nerve and acts in exactly the same way as a normal eye from then on.
The subretinal approach is also more preferable than Epiretinal since it has more direct approach to the problem physically. Instead of stimulating the nerve cells dealing with vision the subretinal approach just mimics the function of a damaged retina. Structurally it is also preferable since it is fully implanted and there are no dangly wires around.
So since the Subretinal approach is the most simple structurally and fixes the problem in the simplest way I believe that it will probably be the most promising eye implant for the future.
Optic Nerve Implant
The optic nerve implant is an entirely different and new approach from the subretinal or epiretinal implants. Instead of working with the retina, a spiral cuff nerve electrode is implanted and attached to the optic nerve. This cuff is implanted intercranially with a cable passing through the skull and skin to the outer surface. Then it also passes through the neck and comes out below the clavicle. Fortunately there are no acute or chronic symptoms for this electrode. The implantation of the cuff has been proven to be a very safe and reliable medical procedure. The equipment used is biocompatible and efficient for electrical stimulation.
The cuff works by stimulating the nerve fibers electronically. This produces phosphene sensitivity over a large portion of the visual field. This image is then captured by a camera and then transferred to the electrode array which stimulates the optic nerve. Over a certain period of time, patients with optic nerve implants will be able to recognize patterns in color, motion, and spatial localization.
Optic nerve implant research has been positively received since it does not require large processing equipment or power such as the other implants. I believe that as the future approaches, more and more research will follow the optic nerve since it seems to be more cost efficient and the equipment has been proven to be safe and reliable.
http://www.escrs.org/eurotimes/September2003/3.asp
http://www.pages.drexel.edu/~dh329/bmes212/opticnerve.html
(I realize my memo was supposed to be on retinal implants but I thought it would be interesting to see the other forms of implants)
The cuff works by stimulating the nerve fibers electronically. This produces phosphene sensitivity over a large portion of the visual field. This image is then captured by a camera and then transferred to the electrode array which stimulates the optic nerve. Over a certain period of time, patients with optic nerve implants will be able to recognize patterns in color, motion, and spatial localization.
Optic nerve implant research has been positively received since it does not require large processing equipment or power such as the other implants. I believe that as the future approaches, more and more research will follow the optic nerve since it seems to be more cost efficient and the equipment has been proven to be safe and reliable.
http://www.escrs.org/eurotimes/September2003/3.asp
http://www.pages.drexel.edu/~dh329/bmes212/opticnerve.html
(I realize my memo was supposed to be on retinal implants but I thought it would be interesting to see the other forms of implants)
What retinal implant should you be eyeing?
In the realm of retinal implants, there exists three types, epiretinal, subretinal, and cortical. All three show promise to restoring vision in some manner, though each have their associated benefits and risks.
Epiretinal implants, are applied to the outermost layer of the retina, this receieves signals from a peripheral camera and then transmits these electrical impulses of the image to the intact retina and optic nerve. The benefits of an epiretinal implant is that the camera could and conversion process could be tuned and more honed while implanted, and makes replacement/upgrading of the camera an easier process should it be neccessary. Negatives about this system are obviously the fact that it's asthetics aren't the most pleasing, epiretinal implants also can't be used on damaged retinas. The next form of implants, subretinal implants, is put on the photoreceptor level of the retina. This chip does all the ligth detection and conversion work there, without a camera. This system is good because it can be used in persons who have suffered from retinal degeneration. The negatives to this procedure is that it's slightly more invasive, and that the image could be worse than that of epiretinal. The final form of retinal implants involves a cortical implant. This implant is used in patients who have deteriorated optical nerves. This method involves direct interaction with the brain via the visual cortex. The visual cortex is hooked up to a camera setup which converts the images into electrical impulses that travel to the brain. The problem with this system is: cost, dangers of direct brain implantation ie. menengitis and scar tissue formation, not that great of a resolution, and asthetic problems. The good about it is that it works for patients who have optical nerve degeneration.
The best of these systems is subretinal implants, this is because they are less noticeable, require less maitenence, is pretty safe, and does pretty much just as well image wise as epiretinal implants.
http://www.seeingwithsound.com/etumble.htm
http://www.opticsreport.com/content/article.php?article_id=1007
Epiretinal implants, are applied to the outermost layer of the retina, this receieves signals from a peripheral camera and then transmits these electrical impulses of the image to the intact retina and optic nerve. The benefits of an epiretinal implant is that the camera could and conversion process could be tuned and more honed while implanted, and makes replacement/upgrading of the camera an easier process should it be neccessary. Negatives about this system are obviously the fact that it's asthetics aren't the most pleasing, epiretinal implants also can't be used on damaged retinas. The next form of implants, subretinal implants, is put on the photoreceptor level of the retina. This chip does all the ligth detection and conversion work there, without a camera. This system is good because it can be used in persons who have suffered from retinal degeneration. The negatives to this procedure is that it's slightly more invasive, and that the image could be worse than that of epiretinal. The final form of retinal implants involves a cortical implant. This implant is used in patients who have deteriorated optical nerves. This method involves direct interaction with the brain via the visual cortex. The visual cortex is hooked up to a camera setup which converts the images into electrical impulses that travel to the brain. The problem with this system is: cost, dangers of direct brain implantation ie. menengitis and scar tissue formation, not that great of a resolution, and asthetic problems. The good about it is that it works for patients who have optical nerve degeneration.
The best of these systems is subretinal implants, this is because they are less noticeable, require less maitenence, is pretty safe, and does pretty much just as well image wise as epiretinal implants.
http://www.seeingwithsound.com/etumble.htm
http://www.opticsreport.com/content/article.php?article_id=1007
Visual Prosthetics: Cortical and Sub-retinal
Ultimately, I believe that Cortical will eventually be the most effective type of vision-replacement. Once the technology goes wireless, the images from the camera source will go directly to the brain; the subject's natural eye-system could deteriorate completely, but the patient could still see. That technology, however, is far from being safe and efficient enough to be used mainstream right now. In my opinion, the next step down is a sub-retinal implant. While a more complicated surgery is required and a few more complication are possible, I believe "pound-for-pound", so to speak, it offers more results than implants on the retina do. It still uses the retina, making it so the patient does not have any external gear with the possibility of being lost or damaged by everyday activities.
Subretinal Implants
The subretinal implant strategy will likely work the best in the future. The subretinal implant avoids any form of wireless data complications, such as interference from other wireless devices and signals, or hacking, which has seemed to be a concern in class lately, because it does not use an external camera. Instead, it directly detect images and stimulates the photoreceptors in the retina so the images can be sent to the brain. Also, because all of the parts are within the body, there would be less parts of it to potentially lose (unlike the presumably expensive camera-containing glasses of the eprietinal device).
There are currently subretinal devices under testing that use the light received through the eye as a power source; though this currently is not the most powerful device by far compared to the exernally-powered epiretinal and subretinal devices, this particular subretinal device shows a lot of promise in that it would need to consist of one chip only, making for a simpler implanaion procedure and for an altogether less invasive device. Once technology improves enough, I believe that this subretinal implant will come out on top.
There are currently subretinal devices under testing that use the light received through the eye as a power source; though this currently is not the most powerful device by far compared to the exernally-powered epiretinal and subretinal devices, this particular subretinal device shows a lot of promise in that it would need to consist of one chip only, making for a simpler implanaion procedure and for an altogether less invasive device. Once technology improves enough, I believe that this subretinal implant will come out on top.
Wednesday, July 23, 2008
Retinal Implants
Within the past few decades, procedures to replace and repair damaged or destroyed retinas have become more and more common, including several different options. Epiretinal Implants sit on top of the retina, directly stimulating ganglia using signals sent from the external camera and power sent from an external transmitter. Being as there are several different options it would only be expected for one to be recommended over another. That being said, I would recommend epiretinal implants, which sit on top of the retina, over subretinal implants, which sit under the retina.
While both types are showing promise in clinical trials I do find some faults with subretinal implants. For example, with some types of subretinal implant they are not able to have strong enough external power sources. Epiretinal implants sit on top of the retina and are therefore more easily accessible from power sources. However, since there are both still in the clinical trial stage it is possible that subretinal implants can be later seen as the more sensible choice.
Artificial Silicon Retina
Marissa Reitsma
The Artificial Silicon Retina (ASR) is a new retinal implant designed to help people with end stage retinitis pigmentosa improve their vision. The new retinal prosthesis, manufactured by Optobionics, is only 2mm. in diameter and only 25 microns (1/1000 inch) in thickness. After surgery, the ASR requires no externally worn devices. In addition, the implant does not require any wires or batteries. Instead, the ASR is powered solely by incident light. The ASR chip uses about 5,000 microscopic solar cells that work to convert light into electrical impulses. Since the ASR makes use of the natural optic nerve, brain surgery and wiring is not required to restore vision. On the other hand, the retinal prosthesis can only be used if the optic nerve is still fully functional.
The ASR implant is still in clinical trial phase, and it has seen variable success. Most of the patients who recieved the implant reported improvement in color vision, the ability to read letters, and an expansion of their visual field. Also, many patients experienced a positive affect on their walking abilities since they were not constantly bumping into unseen objects. The advantages of the ASR are that it requires no external visual device, no brain surgery, and no battery.
Random new study: Spinach protein may be able to serve as an artificial retina in a similar way to the ASR. The protein gives off a small electrical voltage after capturing incoming photons.
http://medgadget.com/archives/2005/02/optobionics_art.html
http://www.sciencedaily.com/releases/2005/04/050429100652.htm
http://www.rachnaindia.com/fzone/fz/asr.htm
Cortical Implants
Cortical Implants
Cortical implants are a great form of visual prosthesis. The way they work is that they collect images through an external camera, which then relays these images to the brain where they are processed. However, cortical implants are different from other types of visual aids in that they do not require any sort of implant in one’s brain; such is the case with the sub retinal implants. Sub retinal implants carry a certain risk of infection or rejection as there is a foreign object being inserted into the eye of the patient. The main idea behind cortical implants is that they bypass the eye all together since the signals are sent from the camera device (worn on the head) to an electrode array which is connected to the visual cortex ( a part of the brain). The main hope for cortical implants is that they may one day become wireless. In this case, the user would have fewer “things” to carry with them seeing as they have to carry a battery pack on their waste at all times as well as super cool head gear which allows them to see. Wireless CI units would allow the user to look more “normal” since the only thing about them that would be different is the fact that they would be wearing sunglasses all the time. The chip that would relay signals and images to the brain would be implanted inside the tissue of the brain itself; this implant is known as a penetrating implant. At this point, scientists have yet to refine this process of penetrating implants, but this discovery is just on the horizon now. And when they have perfected the system of penetrating implants and sending signals to the visual cortex, cortical implants will become a much more popular form of visual prosthesis.
http://www.jwen.com/rp/articles/cortical.html
http://science.jrank.org/pages/543/Artificial-Vision-Cortical-implants.html
Just an Implant
Alexis Gorin
Farah Laiwalla
Engineering Biomedical Systems (BI920-3B)
Wednesday, July 23, 2008
Unless most of the eye is damaged, a subretinal implant, compared to a cortial or epiretinal implant, is the most minimal implant to work with. Unlike the cortial implant, there is not a machinery to worry about, and there are no wires hooked up to the brain. Unlike the epiretinal implant, there are no external pieces and it uses the person's own eye movements, allowing a more natural look to the user and easier use of the technology. The main part of a subretinal implant is simply a stimulation chip, allowing easy use without all the extra macrotechnology used by both of the other types of retinal implants.
A subretinal implant also allows working neurons in the eye to continue processing electrical signals, since they are still intact. Considering that the implant is placed closer to the inner retinal neurons as well, it can also stimulate the eye effectively with a decreased number of currents (Javaheri et al). In the subretinal space, it is also easier to position and fix the implant using non-mechanical devices, leading to less trauma on the eye due to the implantation of the subretinal implant.
Javaheri et al, Michael. "Retinal Prostheses for the Blind." Annals Academy of Medicine Vol. 35 No. 3Mar 2006 141-143. 23 Jul 2008 http://www.annals.edu.sg/pdf/35VolNo3200604/V35N3p137.pdf.
"Optoelectronic implants to treat visual diseases." OpticsReport. 12 June 2007. Optics Report. 23 Jul 2008 http://www.opticsreport.com/content/article.php?article_id=1007.
Zrenner , Eberhart . "Will Retinal Implants Restore Vision? ." Science Vol. 295. no. 55578 Feb 2002 1022 - 1025. 23 Jul 2008 http://www.sciencemag.org/cgi/content/full/295/5557/1022.
Subretinal Implants
Research that led to the subretinal implant began in 1995. The device has now reached the stage of clinical testing after 10 years of research. Measuring 3 x 3 x 0.1 mm, the chip contains 1,500 photodiodes, amplifiers and electrodes. The external energy supply is a power line implanted subdermally. The implant depends on the light reaching the retina. This becomes a stimulus to the photodiodes of the implant. Because the implant is placed directly on the retina, it can communicate through the electrodes to the nerves in the eye.
Eberhart Zrenner, MD, presented the results of the first trials. After 30 days, the seven patients with implants did not experience any complications during or after the procedure. Some visual perception was restored in six out of the seven patients. Despite the lengthy implantation process (5 hours), improvements were recorded. Recognition of vertical and horizontal orientation pixels showed improvement along with differentiation of angles and movement. A wide range of brightness was perceived. The brightness and size of the dots viewed correlated with the voltage of the stimulation.
Even though results differed among the patients, all the patients were happy with the outcome. Just to see light again was a great experience. The next trials will include the effects of a long term implantation of 3 – 6 months. For now, the researchers are working on ways to improve the spatial resolution and the energy supply with the stimulation. The first trial producing positive feedback is encouraging. However, the subretinal implant is far from perfect but shows signs of potential vision for the blind.
OSN SuperSite:
http://www.osnsupersite.com/view.asp?rID=25565
Eberhart Zrenner, MD, presented the results of the first trials. After 30 days, the seven patients with implants did not experience any complications during or after the procedure. Some visual perception was restored in six out of the seven patients. Despite the lengthy implantation process (5 hours), improvements were recorded. Recognition of vertical and horizontal orientation pixels showed improvement along with differentiation of angles and movement. A wide range of brightness was perceived. The brightness and size of the dots viewed correlated with the voltage of the stimulation.
Even though results differed among the patients, all the patients were happy with the outcome. Just to see light again was a great experience. The next trials will include the effects of a long term implantation of 3 – 6 months. For now, the researchers are working on ways to improve the spatial resolution and the energy supply with the stimulation. The first trial producing positive feedback is encouraging. However, the subretinal implant is far from perfect but shows signs of potential vision for the blind.
OSN SuperSite:
http://www.osnsupersite.com/view.asp?rID=25565
New Tattoo Ink Erases Any Regrets
Since we've talked about polymer microspheres, I thought you guys might be interested in this new "biomedical" application of that technology. This product was developed in my lab. -Dan
PROVIDENCE — Having someone's name permanently etched into your flesh is considered by some to be the ultimate testament to a relationship. But wouldn't it be great to make that commitment without really making it ... forever?
A new dye due to hit tattoo parlors this fall will provide an exit strategy of sorts for people who have thought about getting a tattoo, then wondered if they might someday have regrets.
The permanent but removable ink is made by storing dye in microscopic capsules that will stay in the skin for good. But if that butterfly tattoo on the small of your back starts looking lame, it can be zapped away with a single laser treatment that is simpler and less painful than the barrage of treatments now needed.
While the idea might intrigue some — for example, the 36% of Americans ages 18 to 29 who get tattoos, according to a 2006 study by the Journal of American Academy of Dermatology— some enthusiasts say getting inked without the lifetime commitment wouldn't be appealing. Those in the industry are also skeptical, especially since the company making the dye says it will cost considerably more than a regular tattoo.
"I don't know anyone who would pay more for a tattoo where their thought is, 'Maybe one day I'm going to remove this,'" said Jerry Lorito, vice president of the tattoo removal company Tat2BeGone in Costa Mesa, Calif.
The idea was developed in the late 1990s by Rox Anderson, a dermatology professor at Harvard University who founded the New York-based company Freedom-2 in 1999 to bring the product to market.
In 2004, Anderson approached Edith Mathiowitz, a professor of medical science and engineering at Brown University. Mathiowitz specializes in microcapsulating medicines, DNA, hormones and insulin in plastic polymers, which control the time and rate of the drug's release in the body. Some molecules are designed to break open when exposed to heat, ultraviolet light or ultrasound.
Using the same technology, Mathiowitz trapped dye pigments in microscopic beads coated with a safe, biodegradable plastic.
It's possible to remove regular tattoos with lasers, but it can cost thousands of dollars and usually requires between seven to 15 treatments.
With each conventional laser treatment, the dye is broken down into fragments until they are small enough to be carried away by the bloodstream, usually into the lymph nodes. But the Freedom-2 ink particles held in the tiny beads are already small enough. In just one laser treatment, the polymers combust, and the fragments are released and naturally expelled from the body, Mathiowitz said.
She hopes to eventually design molecules that will dissolve over time for a long-term temporary tattoo that would not require any laser treatment.
Mathiowitz doesn't have a tattoo and said that as a scientist, she never thought she'd be working with them. But she said she is happy to help improve an ancient art form.
"This will make tattoos so much safer. None of the toxins from the ink will be able to leak out" and linger in the dermis, as occurs with conventional tattoos, Mathiowitz said.
Freedom-2 boasts it could save a painful and costly removal process for those who have their heart broken or make a spring break mistake.
"Regret is a strong word, but there are people who are parents or are in a job where they do not want their tattoo to show," said Martin Schmieg, president of Freedom-2. "There are times that your life circle changes things, and the form of self-expression you were proud of in your past just doesn't match now."
Schmieg is the only person to use the ink so far. He tattooed his bicep with the company's red logo, then removed it four months later. Photos show the color has disappeared and only a shadow of it looms. Schmieg said it has since faded.
For Elke O'Connor, 39, of Los Angeles, having a decade-old tribal print removed from her throat is costing her at least $1,000, about a dozen laser treatments and pain she described as "excruciating." "It's the worst pain I've ever had in my life," said O'Connor, who had her first treatment last week. "It's like razor blades cutting you."
Despite the pain, she said she still would have declined if she had the option for removable ink back then. "When someone's going into something like getting a tattoo, it's usually something they want forever," she said.
Lorito said the biggest obstacle the company faces is marketing the product to tattoo salons, where he said temporary tattoos, made from henna or vegetable dye that last weeks and sometimes months, are frowned upon.
"When an artist tattoos somebody, in their mind, they want their work on that body for the rest of that person's life," he said.
At Bambu Tattoo Art Studio in Providence, tattoo artist George Dietz said he's skeptical about whether the ink will last, and said he probably won't use it when it's available this fall.
"If people don't want something permanent," he said, "they shouldn't get a tattoo."
PROVIDENCE — Having someone's name permanently etched into your flesh is considered by some to be the ultimate testament to a relationship. But wouldn't it be great to make that commitment without really making it ... forever?
A new dye due to hit tattoo parlors this fall will provide an exit strategy of sorts for people who have thought about getting a tattoo, then wondered if they might someday have regrets.
The permanent but removable ink is made by storing dye in microscopic capsules that will stay in the skin for good. But if that butterfly tattoo on the small of your back starts looking lame, it can be zapped away with a single laser treatment that is simpler and less painful than the barrage of treatments now needed.
While the idea might intrigue some — for example, the 36% of Americans ages 18 to 29 who get tattoos, according to a 2006 study by the Journal of American Academy of Dermatology— some enthusiasts say getting inked without the lifetime commitment wouldn't be appealing. Those in the industry are also skeptical, especially since the company making the dye says it will cost considerably more than a regular tattoo.
"I don't know anyone who would pay more for a tattoo where their thought is, 'Maybe one day I'm going to remove this,'" said Jerry Lorito, vice president of the tattoo removal company Tat2BeGone in Costa Mesa, Calif.
The idea was developed in the late 1990s by Rox Anderson, a dermatology professor at Harvard University who founded the New York-based company Freedom-2 in 1999 to bring the product to market.
In 2004, Anderson approached Edith Mathiowitz, a professor of medical science and engineering at Brown University. Mathiowitz specializes in microcapsulating medicines, DNA, hormones and insulin in plastic polymers, which control the time and rate of the drug's release in the body. Some molecules are designed to break open when exposed to heat, ultraviolet light or ultrasound.
Using the same technology, Mathiowitz trapped dye pigments in microscopic beads coated with a safe, biodegradable plastic.
It's possible to remove regular tattoos with lasers, but it can cost thousands of dollars and usually requires between seven to 15 treatments.
With each conventional laser treatment, the dye is broken down into fragments until they are small enough to be carried away by the bloodstream, usually into the lymph nodes. But the Freedom-2 ink particles held in the tiny beads are already small enough. In just one laser treatment, the polymers combust, and the fragments are released and naturally expelled from the body, Mathiowitz said.
She hopes to eventually design molecules that will dissolve over time for a long-term temporary tattoo that would not require any laser treatment.
Mathiowitz doesn't have a tattoo and said that as a scientist, she never thought she'd be working with them. But she said she is happy to help improve an ancient art form.
"This will make tattoos so much safer. None of the toxins from the ink will be able to leak out" and linger in the dermis, as occurs with conventional tattoos, Mathiowitz said.
Freedom-2 boasts it could save a painful and costly removal process for those who have their heart broken or make a spring break mistake.
"Regret is a strong word, but there are people who are parents or are in a job where they do not want their tattoo to show," said Martin Schmieg, president of Freedom-2. "There are times that your life circle changes things, and the form of self-expression you were proud of in your past just doesn't match now."
Schmieg is the only person to use the ink so far. He tattooed his bicep with the company's red logo, then removed it four months later. Photos show the color has disappeared and only a shadow of it looms. Schmieg said it has since faded.
For Elke O'Connor, 39, of Los Angeles, having a decade-old tribal print removed from her throat is costing her at least $1,000, about a dozen laser treatments and pain she described as "excruciating." "It's the worst pain I've ever had in my life," said O'Connor, who had her first treatment last week. "It's like razor blades cutting you."
Despite the pain, she said she still would have declined if she had the option for removable ink back then. "When someone's going into something like getting a tattoo, it's usually something they want forever," she said.
Lorito said the biggest obstacle the company faces is marketing the product to tattoo salons, where he said temporary tattoos, made from henna or vegetable dye that last weeks and sometimes months, are frowned upon.
"When an artist tattoos somebody, in their mind, they want their work on that body for the rest of that person's life," he said.
At Bambu Tattoo Art Studio in Providence, tattoo artist George Dietz said he's skeptical about whether the ink will last, and said he probably won't use it when it's available this fall.
"If people don't want something permanent," he said, "they shouldn't get a tattoo."
Problems with the Medtronic Fidelis Defibrillator Leads
Most implantable defibrillator units contain two leads, thus the preferred type of lead is the small diameter high-voltage lead, which is easier to insert and possibly remove. However, HV lead model, the Medtronic Sprint Fidelis has been pulled due off the market since the leads could fracture. For patients with the device, which is implanted near the shoulder and connected to the body with leads, according to Medtronic, removing the leads can cause more complications than the fracture itself would cause. Medtronic believes that out of 1000 patients with the affected leads, 9 of them will have leads fracture, with half of them given more than two days’ notice and the other half less than two days notice or no notice at all. A study at the Minneapolis heart institute had six of 583 patients experience lead failure. The fractures would cause unnecessary shocks or cause the unit not to function at all. Two options, plus removal, are available to patients. One option is to monitor the device for signs of fracture. Medtronic is developing new software for the pacemakers that would give three days notice before the unit fails. Another option is to surgically implant a replacement lead while capping the Fidelis lead. However, according to a study, monitoring did not detect nor prevent the failure of the device in 2/3 of the patients. In Minneapolis, none of the patients had complications from neither lead extrication nor removal.
Sources:
Linda M. Kallinen, Robert G. Hauser, Ken W. Lee, Adrian K. Almquist, William T. Katsiyiannis, Chuen Y. Tang, Daniel P. Melby, Charles C. Gornick, Failure of impedance monitoring to prevent adverse clinical events caused by fracture of a recalled high-voltage implantable cardioverter-defibrillator lead, Heart RhythmVolume 5, Issue 6, , June 2008, Pages 775-779.
(http://www.sciencedirect.com/science/article/B7GW9-4S01WMP-D/1/6a9881ae45ab62e7574e77bc9ed83b22)
Keywords: Implantable cardioverter-defibrillator; Lead; Complications; Follow-up
Robert G. Hauser, Linda M. Kallinen, Adrian K. Almquist, Charles C. Gornick, William T. Katsiyiannis, Early failure of a small-diameter high-voltage implantable cardioverter-defibrillator lead, Heart RhythmVolume 4, Issue 7, , July 2007, Pages 892-896.
(http://www.sciencedirect.com/science/article/B7GW9-4NFXDKJ-3/1/a5783e4201e37af697bd3654c5626c86)
Keywords: Implantable cardioverter-defibrillator; Lead; Complications; Failure
http://www.fda.gov/consumer/updates/medtronic101507.html
http://wwwp.medtronic.com/Newsroom/NewsReleaseDetails.do?itemId=1192213397218?=en_US
http://www.medtronic.com/fidelis/physician-letter-may-2008.html
Sources:
Linda M. Kallinen, Robert G. Hauser, Ken W. Lee, Adrian K. Almquist, William T. Katsiyiannis, Chuen Y. Tang, Daniel P. Melby, Charles C. Gornick, Failure of impedance monitoring to prevent adverse clinical events caused by fracture of a recalled high-voltage implantable cardioverter-defibrillator lead, Heart RhythmVolume 5, Issue 6, , June 2008, Pages 775-779.
(http://www.sciencedirect.com/science/article/B7GW9-4S01WMP-D/1/6a9881ae45ab62e7574e77bc9ed83b22)
Keywords: Implantable cardioverter-defibrillator; Lead; Complications; Follow-up
Robert G. Hauser, Linda M. Kallinen, Adrian K. Almquist, Charles C. Gornick, William T. Katsiyiannis, Early failure of a small-diameter high-voltage implantable cardioverter-defibrillator lead, Heart RhythmVolume 4, Issue 7, , July 2007, Pages 892-896.
(http://www.sciencedirect.com/science/article/B7GW9-4NFXDKJ-3/1/a5783e4201e37af697bd3654c5626c86)
Keywords: Implantable cardioverter-defibrillator; Lead; Complications; Failure
http://www.fda.gov/consumer/updates/medtronic101507.html
http://wwwp.medtronic.com/Newsroom/NewsReleaseDetails.do?itemId=1192213397218?=en_US
http://www.medtronic.com/fidelis/physician-letter-may-2008.html
Dalkon Shield
The Dalkon Shield is a "contraceptive intrauterine device" or IUD that lead to numerous injuries in women as well as a number of expensive lawsuits. This device was claimed to prevent pregnancy as well as infections. It was coined as a "technological breakthrough" and had as many as 2.8 million women using it at one time in the US. However none of these women were informed of the risks of this faulty device.
The most important thing the inventors and investors at the Dalkon Corporation failed to do was to test their product sufficiently. Only one insignificant study was put out but later was found to be false because of the investigator's conflict of interest. It was later proven that he had invested in the company and was given a percentage of the profits. This investigator failed to report to the users that the device could carry bacteria to the sterile environment of the uterus. The longer the device stayed in the body, the more bacteria was introduced. Another problem involved the tailstring of the device that underwent hydrolysis in the body. This lead to the disintegration of the outer shealth and even more passage ways for bacteria to enter. And finally, another part of the design became embedded in a layer of the uterus speeding up the process of infectious diseases since this tissue is extremely susceptible to infections. Because of the faulty design, bacteria caused thousands of women numerous infections and diseases ranging from pelvic inflammatory disease (PID) to infertility.
Over 300,000 lawsuits were filed against the Dalkon Corporation and eventually lead to FDA's requirement of testing medical devices through the Medical Device Amendments.
http://en.wikipedia.org/wiki/Dalkon_Shield
The most important thing the inventors and investors at the Dalkon Corporation failed to do was to test their product sufficiently. Only one insignificant study was put out but later was found to be false because of the investigator's conflict of interest. It was later proven that he had invested in the company and was given a percentage of the profits. This investigator failed to report to the users that the device could carry bacteria to the sterile environment of the uterus. The longer the device stayed in the body, the more bacteria was introduced. Another problem involved the tailstring of the device that underwent hydrolysis in the body. This lead to the disintegration of the outer shealth and even more passage ways for bacteria to enter. And finally, another part of the design became embedded in a layer of the uterus speeding up the process of infectious diseases since this tissue is extremely susceptible to infections. Because of the faulty design, bacteria caused thousands of women numerous infections and diseases ranging from pelvic inflammatory disease (PID) to infertility.
Over 300,000 lawsuits were filed against the Dalkon Corporation and eventually lead to FDA's requirement of testing medical devices through the Medical Device Amendments.
http://en.wikipedia.org/wiki/Dalkon_Shield
Medtronic Fidelis Pacemaker
Medtronic Fidelis Pacemakers
In October of 2007 Medtronic a leading manufacturer of biomedical devices was forced to recall one of their products. Recently the company decided to switch leads on their pacemaker. The Quattro lead is much thicker and more difficult to thread through into the heart. The new Fidelis lead is much thinner and were thought to help out surgeons during the procedure. The fidelis leads were later discovered to fracture, though. This could either cause the signal to not get to the heart or it would corrupt data that the lead collects. Corrupted data would cause the pacemaker to make erratic beats. If misfires of this sort happened to rapidly it would induce heart attacks. This problem had already attributed to five deaths by December of that year only 2 months later. The company itself came out that the failure rate was 2.3% of patients who have already had the pacemaker for three months. This would, on a bigger scale, affect 5,000 out of the total 235,000 who have received these implants.
The company did assume responsibility for this problem and began to immediately recall them. They promised to pay for some of the cost of the lead replacement surgery. This compensation was fairly insufficient, for they only contributed $800 out of the total $12,500 cost of the surgery. Besides that the people who actually needed the surgery didn’t know they needed until it was too late. No one knew who was in that 5,000. So often times, against their physician’s recommendation, wanted to receive the replacement surgery just to be sure they would be okay.
Afterwards, the FDA met with some other regulatory organizations to try and come up with a better system for making sure that the new biomedical devices that were being put on the market were tested. This could surly be considered one of the largest biomedical device disasters, solely due to the large numbers of potential subjects and the large number of uncertainty.
Gibb, Gordan. “Medtronic fidelis lead: a nightmare for patients.” Lawyers and Settlements.com. 2007. Online Legal Marketing Ltd. 22 July 2008.
Drug Eluting Stents
When drug eluting stents were first invented, they were so well recieved that they "doubled the world market for stents to $5 Billion annually" (angioplasty.org). Designed with a drug coating to prevent renstenosis, or the closing of the arteries, they were thought to be the perfect solution for patient following angioplastey; Not only did the metal structure prevent most cases of renostenosis directly following angioplasty, but the drug prevented most cases of renostenosis following the implantation of a normal metal stent.
However, recent patterns in patients who use drug eluting stents has suggested they might be linked to problematic conditions. But because they were developed in the 90s, they are a fairly recent invention and have not been on the market long enough to be conclusively linked to any fatal event. Despite this, there is some evidence that they might be linked to an increased chance of thrombosis (clotting which causes blockage of a blood vessel), particularly "Late Stent Thrombosis," which, as its name implies, is thrombosis that occurs a year or two after the stent is implanted.
There are also other problems. Allergic inflamatory reactions, which increase the chance of thrombosis, are worried to be linked to use of Drug eluding stents. Though there is very little evidence to support this according to angioplasty.org, there are a large number of people who feel it could be related to the polymer used in creating the stent. One proposal to confront this problem is an allergy test in which polymers are tested on a patient before putting the stent in the body. Anti-platelet medication must also be taken to prevent platelets from forming on the stent, but due to the drugs which slow down cell growth on the stent, anit-platelet medication must be taken for a longer period of time than with regular metal stents and deal with all the risks that come from use of such medication (most notable of which is hemoraging).
http://www.ptca.org/des.html
http://www.aetna.com/cpb/medical/data/600_699/0621.html
http://heartdisease.about.com/od/angioplastystents/a/DESproblems.htm
http://www.ashcraftandgerel.com/stent_lawsuit.html
However, recent patterns in patients who use drug eluting stents has suggested they might be linked to problematic conditions. But because they were developed in the 90s, they are a fairly recent invention and have not been on the market long enough to be conclusively linked to any fatal event. Despite this, there is some evidence that they might be linked to an increased chance of thrombosis (clotting which causes blockage of a blood vessel), particularly "Late Stent Thrombosis," which, as its name implies, is thrombosis that occurs a year or two after the stent is implanted.
There are also other problems. Allergic inflamatory reactions, which increase the chance of thrombosis, are worried to be linked to use of Drug eluding stents. Though there is very little evidence to support this according to angioplasty.org, there are a large number of people who feel it could be related to the polymer used in creating the stent. One proposal to confront this problem is an allergy test in which polymers are tested on a patient before putting the stent in the body. Anti-platelet medication must also be taken to prevent platelets from forming on the stent, but due to the drugs which slow down cell growth on the stent, anit-platelet medication must be taken for a longer period of time than with regular metal stents and deal with all the risks that come from use of such medication (most notable of which is hemoraging).
http://www.ptca.org/des.html
http://www.aetna.com/cpb/medical/data/600_699/0621.html
http://heartdisease.about.com/od/angioplastystents/a/DESproblems.htm
http://www.ashcraftandgerel.com/stent_lawsuit.html
The Dalkon Shield: The Great Scam
The Intrauterine Device (IUD) is the most widely used contraceptive for woman in the world. The story is not quite the same in the United States. The IUD in this country has a sort of stigma around it, and it comes from the catastrophic results of popular IUD known as the Dalkon Shield sold in the U.S. beginning in 1971. The results of this faulty medical device were taken up in a 2.5 billion dollar class-action lawsuit.
The doctors and businessman involved with the production and sale of this device all knew that the severe risks associated with their product, but decided that the profit gained from the 2.8 million women who at one point in time were using the IUD had a greater weight in their decisions. Years later it was discovered that only one small study was held for the IUD, and that it was held to the ends of preventing pregnancy, not the possible complications of pelvis infection that could have followed. Also, further investigation revealed that the researchers involved in this experiment "cheated" their way to positive results by telling the women who volunteered to use spermicide along with the IUD.
The complications that later rose from the use of the IUDs came from the original design of the Shield. The wicking properties of the IUD and its place in the female anatomy. The wet cavity of the vagina leaves room for bacteria, whereas the uterus must be kept sterile the entire time. The properties of the Shield provided a sort of gateway for bacteria to enter the uterus. In this usually sterile environment, this condition, called sepsis, leads to pelvic inflammatory disease and could become fatal.
While the company greatly promoted and supported the product, the results experienced by most women could not be ignored, nor could the litigation that soon followed. The story of this IUD is tragic, as it forever cast a dark shadow on the contraceptive technology that followed, and it revealed what some people were greedy enough to do at any costs.
1. "Dalkon Shield." Wikipedia..
The doctors and businessman involved with the production and sale of this device all knew that the severe risks associated with their product, but decided that the profit gained from the 2.8 million women who at one point in time were using the IUD had a greater weight in their decisions. Years later it was discovered that only one small study was held for the IUD, and that it was held to the ends of preventing pregnancy, not the possible complications of pelvis infection that could have followed. Also, further investigation revealed that the researchers involved in this experiment "cheated" their way to positive results by telling the women who volunteered to use spermicide along with the IUD.
The complications that later rose from the use of the IUDs came from the original design of the Shield. The wicking properties of the IUD and its place in the female anatomy. The wet cavity of the vagina leaves room for bacteria, whereas the uterus must be kept sterile the entire time. The properties of the Shield provided a sort of gateway for bacteria to enter the uterus. In this usually sterile environment, this condition, called sepsis, leads to pelvic inflammatory disease and could become fatal.
While the company greatly promoted and supported the product, the results experienced by most women could not be ignored, nor could the litigation that soon followed. The story of this IUD is tragic, as it forever cast a dark shadow on the contraceptive technology that followed, and it revealed what some people were greedy enough to do at any costs.
1. "Dalkon Shield." Wikipedia.
Hey, we only use 10% of our Brain
The statement that suggests we only use 10% of our brains is completely false. There are a few possible reasons about how this saying came about, one being my own and the other being more factual, but either way it is false. I'll begin with my own explanation for its origins; someone was so aggravated at not being able to solve a problem that they needed an explanation for why they were so dumb. Unfortunately, while I was investigating this myth no other published article seemed to agree with my reasoning. One article suggested that it may have been on account of misunderstanding great scientist, such as Albert Einstein, who all suggested that we were not using all of our possible intellect as human beings. Unfortunately, the people who do only use 10% of their brain took these quotes far too literally and managed to drag the rest of us down with them : ). There is one more explanation which, besides my own, I find the most likely. It suggests that people may justify the 10% theory because only 1 out of every 10 nerve cells in the brain are essential at any one point in time. This still however does not justify the 10% theory, so before anyone goes to use this saying for motivation or for an explanation for getting a "D" on a test, make sure the person your talking to still believes that it's true.
Kyle
Kyle
The Medtronic Fidelis Pacemaker
The Fidelis lead was originally introduced as an improvement to the Quattro lead, which is thicker. Thinner leads are easier to thread for the surgeon, and were thought to be an improvement all around.However, it was found that the advantage to the Fidelis lead—its thin design—was contributing to hairline fractures that would impede the electrical impulses being delivered to the heart. The problem also proved to be a double-edged sword, given the dual role of the lead as a conduit for sending vital information from the heart to the Medtronic device. A fracture in the lead would garble the data, potentially causing the pacemaker or defibrillator to behave in an erratic fashion.Just as a pacemaker or defibrillation device fails in the delivery of life-saving shocks to the heart when needed, a device that delivers unnecessary shocks can pose an equal risk to the heart. At least one of the five deaths blamed on the fractured Fidelis lead occurred after a Medtronic device misfired so rapidly, it caused a heart attack.This has become an issue for thousands of Fidelis lead patients. In announcing the recall October 15th, Medtronic reported a failure rate of 2.3 per cent within 30 months of implantation. That translates to 5,000 patients out of the 235,000 who have received the Fidelis lead since they were first introduced.That's 5,000 individuals who might expect, statistically, that a fracture is on the horizon.But what of the other 230,000 patients? Statistically they should be fine. However, that's cold comfort. There are no lots drawn, or names pulled out of a hat, or patients rostered into either this group, or that. It leaves 230,000 patients wondering, constantly, if they will be one of the unlucky 5,000.
http://www.personalinjurylawcal.com/medtronic-sprint-pacemaker.html
http://www.personalinjurylawcal.com/medtronic-sprint-pacemaker.html
Eric Shine
Engineering Biomedical Systems
July 23, 2008
The brain doesn't grow new cells
There is a common belief in our society that our brains do not regenerate neurons. It has always been thought that we are born with all of the brain cells we re ever going to have (all 100 billion or so). Also that a human brain cannot regenerate brain cells in adulthood and that memory works by the growth of axon and dendrite connections. This idea of neurogenisis has been supported by years of research by neuroscientist. According to a study done by Princeton neuroscientists they used chemical tracers in an adult macaque monkey brain to track brain activity. The researchers found a rim-like layer of stem cells that covered over the ventricles of the brain. Theses stem cells produced as steady stream of neurons, which floated to the cortex of the brain, specifically the frontal lobe and parietal lobe. As an extension to this research, these neuroscientists want to be able to control the placement of these neurons to help treat diseases like Alzheimer’s and Parkinson’s. But, to be able to do this research, neurogenisis needs to be confirmed in humans.
More and more research is being done in this evolving field of neurogenisis. Some scientist even believe that neurogenisis occurs more efficiently under certain environmental conditions, more nutrients for cell growth. Even though the full effects of neurogenisis has not been understood, scientist are making ground breaking discoveries to understand more about the brain.
References:
http://en.wikipedia.org/wiki/Neurogenesis
http://www.sciencedaily.com/releases/2006/12/061223092924.htm
http://www.brainlightning.com/regen.html
Engineering Biomedical Systems
July 23, 2008
The brain doesn't grow new cells
There is a common belief in our society that our brains do not regenerate neurons. It has always been thought that we are born with all of the brain cells we re ever going to have (all 100 billion or so). Also that a human brain cannot regenerate brain cells in adulthood and that memory works by the growth of axon and dendrite connections. This idea of neurogenisis has been supported by years of research by neuroscientist. According to a study done by Princeton neuroscientists they used chemical tracers in an adult macaque monkey brain to track brain activity. The researchers found a rim-like layer of stem cells that covered over the ventricles of the brain. Theses stem cells produced as steady stream of neurons, which floated to the cortex of the brain, specifically the frontal lobe and parietal lobe. As an extension to this research, these neuroscientists want to be able to control the placement of these neurons to help treat diseases like Alzheimer’s and Parkinson’s. But, to be able to do this research, neurogenisis needs to be confirmed in humans.
More and more research is being done in this evolving field of neurogenisis. Some scientist even believe that neurogenisis occurs more efficiently under certain environmental conditions, more nutrients for cell growth. Even though the full effects of neurogenisis has not been understood, scientist are making ground breaking discoveries to understand more about the brain.
References:
http://en.wikipedia.org/wiki/Neurogenesis
http://www.sciencedaily.com/releases/2006/12/061223092924.htm
http://www.brainlightning.com/regen.html
The Brain DOES grow new Cells
Myth Heard About Brain
The Brain does not grow new Cells
Dennis Xuan
There was once a myth that your Brain just didn’t make new cells during its lifetime. The theory was that although almost all human tissues could repair themselves with stem cells the brain could only compensate for damage by making new connections between surviving neurons. The theory that the Brain does not spawn new cells has been debunked by scientists studying the hippocampus. They found that the hippocampus, which is an important part of the brain pertaining to memory and learning, can actually produce new nerve cells. The relative number produced is low compared to the total number of cells in the brain but this discovery does offer a chance to help patients with neurological disorders.
The findings that the brain can produce more cells can help patients with diseases such as Parkinson’s and Alzheimer’s. If doctors and medical professionals can stimulate growth of new cells in the brain some of these neurological disorders can be somewhat alleviated if not totally fixed. So the myth that the brain doesn’t grow new cells has been totally thrown out the window.
http://www.dsrf.co.uk/Reading_material/New_braincells/newbrain1.htm
Brain Myth: Logic and Creativity
Jason Sedlak
Brain Myths: Logic and Creativity
http://www.rense.com/general2/rb.htm
A common myth about the human brain is that the left side of brain completely deals with all things logical
and mathematical while the left brain dabbles and controls the more creative side of man. In a brain-scanning study conducted by London's Institute of Neurology, a subject looked at a large letter made of smaller, different letters: a large S made of small F’s, for example. The results showed the left side of the brain fired when the subject was focusing on details (the F’s), and the right fired when the subject was thinking about the bigger picture (the S). In another study with patients whom had their brain separated into the two hemispheres as an epilepsy treatment, the subject was shown a cake on a plate. The left part of the brain would connect the image to a fork and knife while the right saw the cake in spatial terms, and associated it with a broad-brimmed hat. The conclusion made by Hellige (One of he lead researchers) was that the distinction between the brain sides was not what they processed, but how they processed information. “A smart brain became one that simultaneously grasped both the foreground and the background of the moment.”
Hm. So whats the story behind Silicone Breast implants?
Silicone breast implants has been the most controversial procedure in the history of implants. The first breast implants were available on the market in 1895. Many women that had the breast implants started getting connective tissue disorders after receiving the implants. Starting in the late 1980’s and the 1990’s there was a large recall of silicone breast implants. Many women had to go to get them removed. The problem with this was that many health insurance companies didn’t cover the cost of the removal even though the cost of getting implants was covered by the health insurance companies.
The main cause of the recall of silicone breast implants was because of connective tissue disorders. Later studies showed that connective tissue disorders had nothing to do with the implant. In a study of 87,000 participants between 1979 and 1990 there was not a link between silicone breast implants and connective tissues disorder. Another possible reason for this problem was that in the 1970’s surgeons started making the lining of the breast implant thinner to give it a more realistic feel. The thinner lining made it easier for the implants to rupture.
In November of 2006 the FDA approved silicone breast implants to be used again after a 14 year ban. Today’s silicone breast implants are made differently than they were made in the 1960’s and 70’s. There are still many risks with getting implants like there are in other surgeries.
http://www.aboardcertifiedplasticsurgeonresource.com/breast_augmentation/augmentation_studies.
http://en.wikipedia.org/wiki/Breast_implant#Silicone_gel_implants
http://www.justbreastimplants.com/implants/silicone.htm
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