Indian-origin researcher unveils biodegradable scaffold to fix damaged knees

A research team at Hospital for Special Surgery, including an Indian-origin scientist, have developed a biodegradable scaffold that can be used to treat patients with damaged knee cartilage.
Dr Asheesh Bedi, a fellow in sports medicine and shoulder surgery at Hospital for Special Surgery, has revealed that his team's invention is a Trufit plug that has mechanical properties similar to cartilage and bone.
"The data has been encouraging to support further evaluation of this synthetic scaffold as a cartilage repair technique," he said.
Damage to so-called articular cartilage can occur in various ways, ranging from direct trauma in a motor vehicle accident to a noncontact, pivoting event on the soccer field.
The Trufit plug has two layers. The top layer has properties similar to cartilage and the lower layer has properties similar to bone.
The bilayered structure has mechanical properties that approximately match the adjacent cartilage and bone.
During the study, surgeons inserted the plug in the knees of 26 patients with donor lesions from OATS procedures and followed up with imaging studies (with MRI and T2-mapping) at various intervals for a period of 39 months.
"Quantitative MRI, when combined with morphologic assessment, allows us to understand the natural history of these repair techniques and define those patients who are most likely to benefit from the surgery," said Hollis Potter, M.D., chief of the Division of Magnetic Resonance Imaging, director of Research in the Department of Radiology and Imaging at Hospital for Special Surgery and lead author of the study.
"We gain knowledge about the biology of integration with the host tissue, as well as the repair tissue biochemistry, all by a noninvasive imaging technique," he added.
"What we found was that the plug demonstrated a predictable process of maturation on imaging studies that paralleled the biology of their incorporation," Bedi said.
The findings were presented at annual meeting of the American Orthopedic Society for Sports Medicine.

How TB bacteria remain latent in body for decades

Scientists from Memorial Sloan-Kettering Cancer Centre have identified a protein that helps TB bacteria resist immune response, and remain latent in the body for decades.
They hope that the new discovery may lead to new drugs to eliminate those strains of mycobacterium tuberculosis that have grown resistant to therapies currently available.
"Tuberculosis can resist the host immune system and remain latent for decades," said Michael Glickman, of the Memorial Sloan-Kettering Cancer Centre.
"To do so, the mycobacterium responsible must resist an arsenal of DNA-damaging mutagens produced within the macrophage, the immune cell in which it lives.
"It's incompletely understood how it can do that. We've identified one such mechanism," he added.
According to the researchers, secret to TB's success is a protein called CarD.
"The mycobacterium tailors its translational machinery in response to stress within the host and we have identified CarD as a critical mediator of this response" said Glickman.
The study showed that loss of CarD is fatal to M. tuberculosis living in cell culture.
CarD depletion leaves the pathogen sensitive to killing by oxidative stress, starvation, and DNA damage as it fails to cut its transcription of rRNA.
Glickman said that they were able to show in infected mice that the mycobacterium depends on CarD not just when it is in its early, most active phase of growth, but also later in the course of infection.
He added that drugs that target CarD's interaction with RNA polymerase could, therefore, lead to sorely needed, new TB drugs.
The study has been published in the journal Cell, a Cell Press publication.

Scientists develop faster, more cost-effective DNA test for crime scenes

Scientists in Japan are reporting development of a faster, less expensive version of the fabled polymerase chain reaction (PCR), which is a DNA test widely used in criminal investigations, disease diagnosis, biological research and other applications.

According to the researchers, the new method could lead to expanded use of PCR in medicine, the criminal justice system and elsewhere.

In the new study, scientist Naohiro Noda and his team note that PCR works by "amplifying" previously undetectable traces of DNA almost like photocopiers produce multiple copies of documents.

With PCR, crime scene investigators can change traces of DNA into amounts that can be identified and linked to a suspect.

Biologists can produce multiple copies of individual genes to study gene function, evolution, and other topics.

Doctors can amplify the DNA from microbes in a patient's blood to diagnose an infection.

Current PCR methods, however, are too expensive and cumbersome for wide use.

The scientists describe development and testing of a new PCR method, called the universal QProbe system, which overcomes these problems.

Existing PCR processes require several "fluorescent probes" to seek out DNA.

QProbe substitutes a single "fluorescent probe" that can detect virtually any target, saving time and cutting costs.

The new method also is more specific, accurately detecting DNA even in the presence of unfavorable PCR products in the samples that may interfere with quantification results.

Most cognitive tests fail to predict Alzheimer's, vascular dementia

Most of the cognitive tests fail to predict whether someone has Alzheimer's disease or vascular dementia, say researchers.

Both Alzheimer's disease and vascular dementia affect learning and memory, behaviour and day-to-day function.

The researchers suggest when older people are confused and forgetful, doctors should base their diagnoses on many different types of information, including medical history and brain imaging.

Dr Jane Mathias and Jennifer Burke, M.Psych.(Clinical), both from the University of Adelaide, analysed 81 previously published studies that compared the cognitive testing of people diagnosed with dementia of the Alzheimer's and vascular type .

Of the 118 different tests that were used only two were able to adequately differentiate between Alzheimer's and vascular dementia.

The Emotional Recognition Task (the ability to identify facial expressions in photographs and match emotional expressions to situations, at which people with Alzheimer's were better) and Delayed Story Recall (at which people with vascular dementia were better), were the only tests that appeared to reliably tell the two groups apart.

Many commonly used tests-such as Digit Span (repeating a set of numbers forward, backward), verbal fluency (generating words by first letter or category, such as animals), drawing tasks and more - were unable to distinguish between dementia types. While these tests may assist in diagnosing dementia, they do not adequately discriminate between Alzheimer's disease and vascular dementia," wrote the authors.

They suggest that all cognitive tests should be used cautiously and only in conjunction with other information (imaging, medical history) when diagnosing patients.

The study appears in the journal Neuropsychology.