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Monday, 27 December 2010

Merry Medical Christmas! 2010

 Today:

  1. Human enzyme breaks down potentially toxic nanomaterials
  2. Printed cells to treat burn victims
  3. Arsenic used to treat leukemia
  4. First evidence that chitosan could repair spinal damage
  5. Building organs block by block: Tissue engineers create a new way to assemble artificial tissues
  6. Scientists discover new method for regenerating heart muscle by direct reprogramming
  7. Eliminating tooth decay: Breakthrough in dental plaque research
Today's news are simply WOW :) Many great news on the medical front. I hope that they won't be only short-lived sensation, but also very real medical options in the near future. Happy holidays, everyone!

Human enzyme breaks down potentially toxic nanomaterials

April 7, 2010
An international study based at the University of Pittsburgh provides the first identification of a human enzyme that can biodegrade carbon nanotubes—the superstrong materials found in products from electronics to plastics—and in laboratory tests offset the potentially damaging health effects of being exposed to the tiny components, according to findings published online in Nature Nanotechnology.
The results could open the door to the use of carbon nanotubes as a safe drug-delivery tool and also could lead to the development of a natural treatment for people exposed to nanotubes, either in the environment or the workplace, the team reported. The researchers found that carbon nanotubes degraded with the human enzyme myeloperoxidase (hMPO) did not produce the lung inflammation that intact nanotubes have been shown to cause. Furthermore, neutrophils, the that contain and emit hMPO to kill invading microorganisms, can be directed to attack carbon nanotubes specifically.
For the current study, the researchers focused on human MPO because it works via the release of strong acids and oxidants—similar to the chemicals used to break down carbon nanotubes. They first incubated short, single-walled nanotubes in an hMPO and hydrogen peroxide solution—the hydrogen peroxide sparks and sustains hMPO activity—for 24 hours, after which the structure and bulk of the tube had completely degenerated. The nanotubes degenerated even faster when sodium chloride was added to the solution to produce hypochlorite, a strong oxidizing compound known to break down nanotubes.After establishing the effectiveness of hMPO in degrading carbon nanotubes, the team developed a technique to prompt to attack nanotubes by capturing them and exposing them to the enzyme. They implanted a sample of nanotubes with antibodies known as immunoglobulin G (IgG), which made them specific neutrophil targets. After 12 hours, 100 percent of IgG nanotubes were degraded versus 30 percent of those without IgG.
In subsequent laboratory tests, lung tissue exposed to the degraded nanotubes for seven days exhibited negligible change when compared to unexposed tissue. On the other hand, tissue exposed to untreated nanotubes developed severe inflammation. source
My comment: That's actually very interesting article for more than one reason. First, the disposal of nanoparticles is very important for obvious reason - nano materails are used in so many product on the market, their accumulation is obviously dangerous. So understanding the way the body handles nanoparticles and reinforcing it is obviously essential. Another thing I find very curious is the use of hydrogen peroxide. Why I find it odd is because hydrogen peroxide is famous for its use as some kind of cure. Some people say it works. The question for me is why. And here we see one explanation. The hydrogen peroxide strengthen the work of hMPO which kills microorganisms. Interesting.

Printed cells to treat burn victims

April 12, 2010 by Lin Edwards

(PhysOrg.com) -- A medical device that works rather like an inkjet printer is being developed in the US to heal burns and other wounds by "printing" skin cells directly onto the wound. The device, called a bioprinter, may reduce the need for skin grafts. It would be mounted on a wheeled frame and positioned over the bed of the patient.
A laser inside the bioprinter, which was developed at Wake Forest University School of Medicine in Winston-Salem, North Carolina, first measures the size and shape of the wound and then applies specific precisely where they are needed. The skin cell spray is produced by dissolving from pieces of skin and then separating cell types such as keratinocytes and fibroblasts. The purified cells are then incubated in a nutrient solution where they multiply. They are then placed into sterilized cartridges and sprayed onto the wound by a similar process to a multi-color , with the fibroblasts sprayed on first followed by a layer of keratinocytes. The sprayed-on cells form a protective shield for the wound.
The device has so far only been tested on mice, but the initial results show wounds heal quickly and safely, with wounds healing three weeks faster than those that were untreated. Professor of regenerative medicine at the University, George Christ, said the group would next test the device on pigs, who have skin resembling human skin. They will eventually apply for approval from the US to allow them to carry out human trials. source
My comment: Wow! That's pretty cool if you ask me. Especially for people with severe burns. 3 weeks difference is extremely serious. If I remember correctly, my burn wounds needed more than a month to heal properly. I spent like a week or two in hospital for treatment. So 3 weeks makes a lot of difference! I wish them quick and safe journey to human trials.

Arsenic used to treat leukemia

April 12, 2010 by Lin Edwards

(PhysOrg.com) -- Arsenic, known in the West mainly as a poison, has been used in traditional Chinese medicine for around two thousand years for the treatment of conditions such as syphilis and psoriasis. It has also been shown to have a substantial anti-cancer effect for a type of leukemia, but until now no one has known the mechanism for this effect. Now scientists in China have discovered arsenic targets proteins that contribute to the growth of cancer cells.
The group found that arsenic trioxide (As2O3) acts by promoting the degradation of a protein that encourages the growth of acute promyelocytic leukemia (APL) cells, although a detailed mechanism of how it works has yet to be established.
It was already known that a fusion protein called PML-RARalpha is produced as a result of a genetic mutation in APL, and this protein is essential to the growth and survival of the . When arsenic trioxide is present, a known as SUMO tags the fusion protein, which is then destroyed. When the protein is destroyed, the cancer cell can no longer survive. What the new research demonstrated was that As2O3 binds to a part of the protein called a zinc finger, which is rich in cysteine residues. As a result several protein molecules join together to form an insoluble protein, and the aggregate is then bound by SUMO, which destroys it.
APL affects the blood and bone marrow, and causes a drop in production of normal and platelets. Now, as a result of treating APL with arsenic in China, over 90 per cent of patients survive at least five years with no signs of the disease.
Arsenic treatment has an advantage over chemotherapy because there is a lower incidence of side effects such as hair loss and suppression of the immune system. Many other countries now use arsenic in the treatment of APL, but some doctors refuse to recommend it, and some patients refuse to accept it because of its reputation as a poison. source
My comment:Wow! 90% of the people survived without a sign of the disease Because if something works like this, it's obviously good. and people hesitate before taking such treatment?! Are they crazy? Or are they greedy! I mean health insurance companies, of course, not patients. Because for me, the only reason why a patient won't try a treatment promising so much is if s/he is advised so by a doctor. And why a doctor will advice so is a mystery for me!

First evidence that chitosan could repair spinal damage

April 16, 2010
Spinal injuries are some of the most debilitating that anyone can suffer. However, Richard Borgens and his team from the Center for Paralysis Research at the Purdue School of Veterinary Medicine can now offer spinal cord damage sufferers some hope. They publish their discovery in the Journal of Experimental Biology that chitosan, a sugar, can target and repair damaged spinal cord nerve membranes and restore nerve function.
(..)Another therapy that is currently undergoing testing is the use of polyethylene glycol (PEG) to seal and repair damaged spinal cord nerve cells. By repairing the damaged membranes of nerve cells, Borgens and his team can restore the spinal cord's ability to transmit signals to the brain. However, there is one possible clinical drawback: PEG's breakdown products are potentially toxic.
Borgens teamed up with physiologist Riyi Shi and chemist Youngnam Cho, who pointed out that some sugars are capable of targeting damaged membranes. Could they find a sugar that restored spinal cord activity as effectively as PEG? Borgens and his team publish their discovery that chitosan can repair damaged nerve cell membranes in The on 16 April 2010.
Next Cho tested whether a dose of chitosan could prevent large molecules from leaking from damaged spinal cord cells. Testing for the presence of the colossal enzyme lactate dehydrogenase (LDH), Borgens admits he was amazed to see that levels of LDH leakage from chitosan treated spinal cord were lower than from undamaged spinal cords. Not only had the sugar repaired membranes at the compression site but also at other sites where the cell membranes were broken due to handling. And when the duo tested for the presence of harmful reactive oxygen species (ROS), released when ATP generating mitochondria are damaged, they found that ROS levels also fell after applying chitosan to the damaged tissue: chitosan probably repairs mitochondrial membranes as well as the nerve cell membranes.
Measuring the brain's response to nerve signals generated in a guinea pig's hind leg, the duo saw that the signals were unable to reach the brain through a damaged spinal cord. However, 30·min after injecting chitosan into the rodents, the signals miraculously returned to the animals' brains. Chitosan was able to repair the damaged spinal cord so that it could carry signals from the animal's body to its brain. source
My comment: Another wow! Simply no comment.

Building organs block by block: Tissue engineers create a new way to assemble artificial tissues

May 13, 2010 by Anne Trafton
(PhysOrg.com) -- Researchers at the MIT-Harvard Division of Health Sciences and Technology (HST) have come up with a new way to overcome that challenge, by encapsulating living cells in cubes and arranging them into 3-D structures, just as a child would construct buildings out of blocks.
The new technique, dubbed "micromasonry," employs a gel-like material that acts like concrete, binding the cell "bricks" together as it hardens.
To obtain single cells for , researchers have to first break tissue apart, using enzymes that digest the extracellular material that normally holds cells together. However, once the cells are free, it's difficult to assemble them into structures that mimic natural tissue microarchitecture.The HST researchers built their "biological Legos" by encapsulating cells within a polymer called polyethylene glycol (PEG), which has many medical uses. Their version of the polymer is a liquid that becomes a gel when illuminated, so when the PEG-coated cells are exposed to light, the polymer hardens and encases the cells in cubes with side lengths ranging from 100 to 500 millionths of a meter.
Once the are in cube form, they can be arranged in specific shapes using templates made of PDMS, a silicon-based polymer used in many . Both template and cell cubes are coated again with the PEG polymer, which acts as a glue that holds the cubes together as they pack themselves tightly onto the scaffold surface.
After the cubes are arranged properly, they are illuminated again, and the liquid holding the cubes together solidifies. When the template is removed, the cubes hold their new structure.
Gomez Fernandez and Khademhosseini used this method to build tubes that could function as capillaries, potentially helping to overcome one of the most persistent problems with engineered organs — lack of an immediate blood supply.
Other researchers have developed a technique called organ printing to create complex 3-D tissues, but that process requires a robotic machine that is not in widespread use. The new technique does not require any special equipment. source
My comment: I'm not sure what the advantage of this technique over scaffolding is but let's say it's progress. I only wonder isn't PEG toxic to the cells as described in the previous article. Because if it is, it must be removed from the organ before it starts functioning.

Scientists discover new method for regenerating heart muscle by direct reprogramming


August 5, 2010 Scientists at the Gladstone Institute of Cardiovascular Disease (GICD) have found a new way to make beating heart cells from the body's own cells that could help regenerate damaged hearts.
In research published in the current issue of Cell, scientists in the laboratory of GICD director Deepak Srivastava, MD, directly reprogrammed structural cells called fibroblasts in the heart to become beating heart cells called cardiomyocytes. In doing so, they also found the first evidence that unrelated adult cells can be reprogrammed from one cell type to another without having to go all the way back to a stem cell state.
The researchers, led by Masaki Ieda, MD, PhD, started off with 14 important for formation of the heart and found that together they could reprogram fibroblasts into cardiomyocyte-like cells. Remarkably, a combination of just three of the factors (Gata4, Mef2c, and Tbx5) was enough to efficiently convert fibroblasts into cells that could beat like cardiomyocytes and turned on most of the same expressed in cardiomyocytes. When transplanted into mouse hearts 1 day after the three factors were introduced, fibroblasts turned into cardiomyocyte-like cells within the beating heart.
"Half of the cells in the heart are fibroblasts, so the ability to call upon this reservoir of cells already in the organ to become beating has tremendous promise for cardiac regeneration." The study results imply that cells in multiple organs within an individual might be directed into necessary cell types to repair defects within the body. source
My comment: Ok, but doesn't the heart need those fibroblasts? I guess this therapy is good only for certain class of heart failures, not for all of them. But hey, it's another progress. Awesome!

Eliminating tooth decay: Breakthrough in dental plaque research

December 7, 2010

Dutch professors Bauke Dijkstra and Lubbert Dijkhuizen have deciphered the structure and functional mechanism of the glucansucrase enzyme that is responsible for dental plaque sticking to teeth. This knowledge will stimulate the identification of substances that inhibit the enzyme. Just add that substance to toothpaste, or even sweets, and caries will be a thing of the past.  
The University of Groningen researchers analysed glucansucrase from the lactic acid bacterium Lactobacillus reuteri, which is present in the human mouth and digestive tract. The bacteria use the glucansucrase enzyme to convert sugar from food into long, sticky sugar chains. They use this glue to attach themselves to . The main cause of , the bacterium Streptococcus mutans, also uses this enzyme. Once attached to tooth enamel, these bacteria ferment sugars releasing acids that dissolve the calcium in teeth. This is how caries develops. source
My comment: I think that any hope for getting rid of caries is pretty far fetched for the moment, but as a person who spends a great deal of time with the dentist, I sincerely wish them luck. I wonder if there isn't some natural way to break this enzymes. Because as we all know, some people eat whatever they like, don't clean their teeth seriously and they still have healthy teeth! There must be a reason for that and I think this is a great way to fight caries. But then, what the poor dentist would do? Oh, don't worry, it's Christmas, so there is a miracle for them too. Purely and simply, not all the dental problem come from caries, so even if we eliminate it, they'll have a way to earn their living. So everybody is happy, now can we forget the word caries?! It's about time, I say! ;)

 

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