Researchers have developed a promising new material that can be used to repair severed nerves by combining chitosan, a compound found in the shells of crabs and shrimp, and polycaprolactone, a strong, flexible, biodegradable polyester commonly used in sutures. The hybrid fiber combines the biologically favorable qualities of the natural material with the mechanical strength of the synthetic polymer.

Researchers combined the fibers at the nanometer scale by first using a technique called electrospinning to draw the materials into nanometer-scale fibers, and then weaving the fibers together. The resulting material has a texture similar to that of the nanosized fibers of the connective tissue that surrrounds human cells.

The two materials are different and are difficult to blend, but proper mixing is crucial because imperfectly blended fibers have weak points.

[snip] Of the three materials, the chitosan-polyester weave showed the most consistent performance for strength, flexibility and resistance to compression under both dry and wet conditions. Under wet conditions, which the researchers say best mimics those in the body, the chitosan-polyester blend required twice as much force to push the tube halfway shut as the other biomaterial, and eight times as much force as the collagen tube.

The new material showed promise for nerve guides but would also work well for wound dressings, heart grafts, tendons, ligament, cartilage, muscle repair and other biomedical applications, Zhang said.

The details of the study is available online in the journal Advanced Materials.

Image: The left panel shows a closeup of chitosan and polyester fibers woven at the nanometer scale. The middle panel shows a nerve cell growing on the resulting mesh, which has a texture similar to the body's fibrous connective tissue. The right panel shows a cross-section of the synthetic nerve guide. Arrows point to nerve cells that have attached to the inner and outer surfaces of the tube. Credit: University of Washington

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Researchers have successfully sequence the genome of Azotobacter vinelandii, a nitrogen fixing bacterium found in soil. The data gathered will help advance research on nitrogen fixation and other biochemical processes, using A. vinelandii as model organism.

A. vinelandii has one of the highest respiratory rates of any known bacterium and has the capacity to maintain low levels of cytoplasmic oxygen through a process called respiratory protection. The sequence of the bacteria's genome allowed the team of researchers to identify the genes involved in respiration, including those responsible for respiratory protection. Genome analysis helped pinpoint the chromosomal location of the three known oxygen-sensitive nitrogenases, as well as the genes that code for other oxygen-sensitive enzymes such as carbon-monoxide dehydrogenase and a formate dehydrogenase. The sequence also provided important information on the genes that code for alginate, a polymer that further protects the organism from excess oxygen by forming a physical barrier around the bacterium.

The research will appear n the cover of the second July 2009 issue of the Journal of Bacteriology but has been published ahead of print, doi:10.1128/JB.00504-09.

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Previously, researchers haveidentified a key protein, called p16INK4a, that increase in mammalian organs as as cells and tissues age. Recently, they have found out that the protein is also present in human blood and is strongly correlated both with chronological age and with certain behaviors such as tobacco use and physical inactivity, which are known to accelerate the aging process. Based on these findings, they have developed a simple blood test to detect p16p16INK4a expression, which is present in cells called T-lymphocytes, also known as T-cells.

They found that expression of the biomarker was strongly correlated with the donor's chronological age and, in fact, increased exponentially with age. In addition, increased levels were independently associated with tobacco use and physical inactivity as well as with biomarkers of human frailty.

Sharpless said that the researchers were surprised by some of their findings, "We found a very weak correlation between the biomarker and obesity - as measured by body mass index (BMI) - despite other data suggesting that caloric restriction slows aging. The data suggest the possibility that reduced exercise may actually be worse with regard to molecular age than a higher BMI."

"Although we don't know whether this test is a good reflection of cellular age in all types of human tissues, we believe it is a first step toward a better understanding of issues like the suitability of organs for transplantation, how well patients are likely to recover after surgery or the future toxicity of chemotherapy for cancer patients," he added.

The study has been published online ahead of print in the journal Aging Cell.

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US agricultural company Becker Underwood, in collaboration with Plant Bioscience Limited, now holds worldwide exclusive licence on the use of jasmonic acid as a natural seed treatment to help cut down on pesticide use on some commercially-important agricultural crops.

Researchers at Lancaster University's Environment Centre and Stockbridge Technology Centre found that plants grown from seeds dipped in jasmonic acid are considerably more resistant to pests. The chemical seems to prime some plants' natural protective responses.

Early trials at Lancaster University saw promising results when researchers treated the seeds of tomato plants, sweet pepper and maize. Red spider mite attack on tomato plants was down by 80 per cent, aphid attack on sweet peppers cut by 70 per cent and caterpillar damage to maize was reduced by 38 per cent.
Applying jasmonic acid to seeds protects many crops for at least ten weeks after germination of the seeds. Treated seeds can also be stored and sown at a later stage.

'We think treating seeds with jasmonic acid acts rather like immunisation, protecting plants for an extended period after treatment,' says Dr Jason Moore, a member of the Lancaster team.

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Researchers are developing a diagnostic test for prostate cancer wherein gold nanoparticles screen for the same cancer-related protein marker that is screened for by the FDA-approved Prostate-Specific Antigen (PSA) test.

Huo and her team at the UCF lab developed the new technique involving gold nanoparticles, which she first mixes in a solution. The nanoparticles are engineered to attach themselves to cancer-producing proteins related to the type of cancer she is targeting. When she places a drop of blood in the solution, the gold nanoparticles seek out the protein. If the protein is present, the gold nanoparticles cluster around it. Using a dynamic light-scattering instrument, she looks for the clusters. If there are no clusters, there is no cancer-causing protein.

During a test, if cancer-producing proteins are detected at a significant level, the consumer would be directed to see a doctor.

Extensive cOlinical trials will have to be performed, but the researchers say that in three to five years an over-the-counter test kit for prostate cancer (and other cancers) is likely.

Farmers, consumers and civil society organizations in Australia, Canada and the U.S. released a joint statement confirming their collective commitment to stop commercialization of genetically engineered (GE) wheat.
Here's the summary statement:

In light of our existing experience with genetic engineering, and recognizing the global consumer rejection of genetically engineered wheat, we restate our definitive opposition to GE wheat and our commitment to stopping the commercialization of GE traits in our wheat crops.

You can download a pdf copy of the full statement here. Individual and organizations are invited to join the action. Find out how you can pitch in!

A group of researchers have identified eight genes that help predict a melanoma patient's response to treatment.

Dr. Tawbi and his colleagues examined the tumor tissues of 21 patients with metastatic melanoma, some of whom responded to chemotherapy and some who did not. Once the cases were divided, the researchers used a mathematical tool called Neural Network Analysis to survey over 25,000 genes and the regulators that turn the genes on and off to see if they could identify ones that could distinguish responders from nonresponders.

"Cancer cells contain massive amounts of information that, if analyzed appropriately, may inform us how to kill them," said Dr. Tawbi. "They contain thousands of genes, and every gene has a switch that turns it on or off. Neural Network Analysis, which utilizes pattern recognition algorithms, helped us identify a signature of eight genes and their switches that predict a patient's likelihood of responding to treatment for metastatic melanoma."

These eight genes are being validated in a larger sample of 80 patients.

Using an animal model, researchers have shown that injecting adult bone marrow stem cells into skeletal muscle can repair cardiac tissue and thus reverse damages due to heart failure by doubling myocytes, or heart cells, and reducing cardiac tissue injury by 60 percent.

"Injecting MSCs or factors released by MSCs improved ventricular function, promoted myocardial regeneration, lessened apoptosis (cell death) and fibrotic remodeling, recruited bone marrow progenitor cells and induced myocardial expression of multiple growth factor genes," Lee said.

"These findings highlight the critical 'cross-talks' between the injected MSCs and host tissues, culminating in effective cardiac repair for the failing heart."

This study has been published in the American Journal of Physiology- Heart Circulation Physiology.

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Scientists have developed a new anti-HIV drug as well as a possible means of producing the drug in large quantities using transgenic plants.

In the research paper, Ma and colleagues describe how they combined two protein microbicides (b12 monoclonal antibody and cyanovirin-N) into a single "fusion" molecule and showed that this molecule is more active against HIV than either of its individual components. They designed synthetic DNA for producing this molecule and introduced this DNA into plant cells. After regenerating transgenic plants that produce the fusion molecule, they prepared the microbicide from a plant extract made by grinding the leaves.

The study has been published in the latest issue of FASEB.

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Using a tool called P[acman], group of researchers has established a library of clones covering most of the genome of Drosophila melanogaster (fruit fly), an organism widely used in genetics research.

P[acman]- developed by Dr. Koen Venken (http://flypush.imgen.bcm.tmc.edu/lab/koenv/index.html) in Bellen's laboratory- allows scientists to study large chunks of DNA in living flies. The vector - officially P/phiC31 artificial chromosome for manipulation - combines different technologies: a specially designed bacterial artificial chromosome (BAC) that allows maintenance of large pieces of DNA in bacteria, recombineering that allows the manipulation of large pieces of DNA in bacteria, and the ability to insert the genomic DNA into the genome of the fly at a specific site using phiC31-mediated transgenesis.

Venken adapted the P[acman] vector to create genomic libraries, so that a researcher can choose a gene and find the corresponding clones in the library that cover that gene. Their collaborators at Lawrence Berkeley National Laboratory, Drs. Roger Hoskins and Joseph Carlson, played a key role in the design, construction, and annotation of the libraries.

"You can insert a single copy of a gene and rescue a mutation, or do a structure/function analysis of the gene," Bellen said. "If you don't know where the gene is expressed, you can tag it, put it back and locate where it is expressed."

The new libraries are described in detail in a paper recently published in Nature Methods. The library is available at http://pacmanfly.org/.