July 20, 2008, 5:04 PM CT

How HIV conquers immune system

New research into the earliest events occurring immediately upon infection with HIV-I shows that the virus deals a stunning blow to the immune system earlier than was previously understood. As per researchers at Duke University Medical Center, this suggests the window of opportunity for successful intervention may be only a matter of days not weeks after transmission, as scientists had previously believed.

Appearing in the recent issue of the Journal of Virology, the finding may make the challenge of designing an effective HIV/AIDS vaccine appear daunting. But scientists say the study has also yielded a blueprint for what a successful vaccine should look like, and moreover, when such a vaccine would need to work.

Until now, researchers believed that the window of opportunity to intervene in the process of HIV-1 infection lay in the three to four weeks between transmission and the development of an established pool of infected CD4 T cells. HIV-1 cripples the immune system by invading and killing CD4 T cells, key infection-fighters in the body.

"But this new study shows that HIV-I does a lot of damage to the immune system very early in that time frame, and now we feel that the opportunity to intervene most effectively may range from about five to seven days after infection," said Barton Haynes, M.D., the senior author of the study and director of the Center for HIV/AIDS Vaccine Immunology (CHAVI) at Duke University Medical Center......... Posted by: Emily      Read more         Source

Sun, 20 Jul 2008 22:17:40 GMT

How Infants Start the Journey to Their First Word

have shown that adults cannot successfully distinguish as wider a range of phonemes as infants.

This is because until about 11 months of age infants are masters of discriminating phonemes used in all different types of languages. But after 11 months infants settle down with one set of phonemes for their first language, and lose the ability to discriminate the phonemes from other languages. Infants are beginning to specialise in their own language.

The specialisation at 11 months in one set of around 40 phonemes, along with other linguistic processes, is clearly crucial as it quickly brings a magical moment: the first word.

» Read other top 10 child psychology studies on the emergence of infant memory, self-concept, self-concept, attachment, self-concept, theory of mind and self-concept.

[Image credit: self-concept]

Reference

Eimas, P. D., Siqueland, E. R., Jusczyk, P., & Vigorito, J. (1971). self-concept. Science, 171(3968), 303-306.Labels: Child Psychology Posted by: Jerry      Read more     Source

July 20, 2008, 2:57 PM CT

Standards in stem cell research

Standards in stem cell research help both researchers and regulators to manage uncertainty and the unknown, as per new research funded by the Economic and Social Research Council. Efforts to standardise practices across different labs is, however, a balancing act where the autonomy of researchers and fragility of living material need to be weighed against the need for comparable data.

The ambition in a number of quarters to scale up the production of human embryonic stem cells and move towards clinical trials requires that different laboratories are able to produce to a standard quality of cells. Developing common standards in stem cell production is not straightforward as so much is still unknown in this new science.

Professor Andrew Webster and Dr Lena Eriksson of York University interviewed and observed a range of researchers and technicians working in stem cell laboratories in the UK, USA and Sweden.

Accurately describing human embryonic stem cell lines is one way to begin setting standards. A stem cell line is a family of constantly-dividing cells, the product of a single parent group of stem cells. Embryonic stem cells are unique in that they have yet to 'decide' which developmental path to choose: they have the ability to turn into almost all human cell types. However each human embryonic stem cell holds the genetic signature of the donor which differs between donors just as people themselves differ. Further the state of a stem cell is by its very nature temporary as it is defined by its ability to develop into a number of different cell types......... Posted by: Emily      Read more         Source

July 20, 2008, 2:13 PM CT

Stem cell chicken and egg debate

Logic says it has to be the niche. As air and water preceded life, so the niche, that hospitable environment that shelters adult stem cells in a number of tissues and provides factors necessary to keep them young and vital, must have emerged before its stem cell dependents.

A team of researchers at the Salk Institute for Biological Studies led by Leanne Jones, Ph.D., assistant professor in the Laboratory of Genetics, now suggests that this is not always the case. They report in the July 20 advance online edition of the journal Nature that the cells that comprise a specialized niche in the testis of fruit flies actually emerge from adult stem cells, a finding with implications for regenerative medicine, aging research, and cancer therapeutics.

Previously, researchers thought that a fruit fly's allotment of testis niche cells was handed out at birth and meant to last a lifetime. "What this paper demonstrates is that once a fly becomes an adult, some stem cells that function in spermatogenesis start making the very cells that support them," said Jones. "Once a fly develops into an adult, some of these niche cells can be replaced".

Using microscopy and fluorescent markers enabling them to image specific cell types over time, Jones' group, led by first author Justin Voog, actually caught a testis stem cell population in the act of turning into their own niche, known in the fly testis as the hub......... Posted by: Emily      Read more         Source

July 19, 2008, 10:24 AM CT

Give antibiotics within hour before first incision

Giving children preventive antibiotics within one hour before they undergo spinal surgery greatly reduces the risk for serious infections after the surgery, suggests a Johns Hopkins study would be reported in the recent issue of Pediatric Infectious Disease Journal (also available online ahead of print). Children who received antibiotics outside of the golden one-hour window were three and half times more likely to develop serious infections at the surgery site, scientists report, pointing out that something as simple as ensuring that a child gets timely prophylaxis can prevent serious complications and reduce the length of hospital stay.

"When it comes to preventing infections, when a child gets antibiotics appears to be one of the most critical yet most easily modifiable risk factors, and may matter just as much as the type and dosage of the medicine ,"says lead researcher Aaron Milstone, M.D., infectious disease specialist at the Johns Hopkins Children's Center. "The moral of this is that an ounce of timely prevention is indeed worth a pound of therapy".

Nearly 780,000 postsurgical infections occur in the United States each year, as per estimates from the Institute for Healthcare Improvement. An infection after surgery nearly doubles a patient's risk of death, doubles a patient's hospital stay and adds up to $50,000 to therapy costs per patient, scientists say......... Posted by: Emily      Read more         Source

July 16, 2008, 8:56 PM CT

Genetic variation increases HIV risk in Africans

A genetic variation which evolved to protect people of African descent against malaria has now been shown to increase their susceptibility to HIV infection by up to 40 per cent, as per new research. On the other hand, the same variation also appears to prolong survival of those infected with HIV by approximately two years.

The discovery marks the first genetic risk factor for HIV found only in people of African descent, and sheds light on the differences in genetic makeup that play a crucial role in susceptibility to HIV and AIDS.

The research, published recently in Cell Host & Microbe, was co-authored by Professor Robin Weiss, UCL Infection and Immunity, who worked with colleagues in the US to analyse data from a 25-year study of thousands of Americans of different ethnic backgrounds.

The gene that the research focused on encodes a binding protein found on the surface of cells, called Duffy Antigen Receptor for Chemokines (DARC). The variation of this gene, which is common in people of African descent, means that they do not express DARC on red blood cells. DARC influences the levels of inflammatory and anti-HIV blood factors called chemokines.

Discussing the findings, Professor Weiss said: "The big message here is that something that protected against malaria in the past is now leaving the host more susceptible to HIV......... Posted by: Emily      Read more         Source

July 16, 2008, 8:06 PM CT

Psychological and social issues associated with tooth loss

Are feelings of depression overwhelming you? Is your self-esteem an issue? Having problems advancing in life or your career? Maybe you feel nervous or self conscious in social settings? Do you avoid social settings all together? Check your smile; tooth loss could be the culprit and you're not alone. Nearly 20 million teeth are extracted each year leaving scores of people to deal with the psychological affects of a less than perfect smile. However, during the Academy of General Dentistry's (AGD) 56th Annual Meeting & Exhibits in Orlando, Fla., July 16-20, H. Asuman Kiyak, PhD, will address the psychological issues affecting people who must deal with the loss of a tooth, as well as explain how this loss can affect the quality of life.

In Dr. Kiyak's course, "Enhancing the Oral Health and Quality of Life for Partially Edentulous or Fully Edentulous Patients: The Importance of Communication," she will reveal the post traumatic effects a patient endures after the loss of a tooth and will also pinpoint ways a doctor can communicate with a patient to help them cope with and understand their options for restoring their smile.

"The major impact of tooth loss is on the appearance and social relations component of quality of life because people cannot change their appearance with missing teeth," says Dr. Kiyak......... Posted by: Emily      Read more         Source

July 15, 2008, 10:08 PM CT

Genetic contribution to autism

Some parents of children with autism evaluate facial expressions differently than the rest of us--and in a way that is strikingly similar to autistic patients themselves, as per new research by neuroscientist Ralph Adolphs of the California Institute of Technology and psychiatry expert Joe Piven at the University of North Carolina at Chapel Hill.

Adolphs, Bren Professor of Psychology and Neuroscience and professor of biology, and his colleague Michael Spezio (now at Scripps College in Claremont, California) collaborated with Piven and autism experts at the University of North Carolina to study 42 parents of children with autism, a complex developmental disability that affects an individual's ability to interact socially and communicate with others. Based on psychological testing, 15 of the parents were classified as being socially aloof.

"This manifests as a tendency not to prefer interactions with others, not to enjoy 'small talk' for the sake of the social experience, and to have few close friendships involving sharing and mutual support. This characteristic is really a variation of the normal range of social behavior and not linked to any functional impairment," says Piven, director of the Carolina Institute for Developmental Disabilities.

The parents participated in an experiment that measured how they make use of the face to judge emotions. The subjects were shown images depicting facial expressions of emotion that were digitally filtered so that only certain regions of the face were discernible--the left eye, for example, or the mouth. The subjects were then asked to decide as quickly as possible if the emotion depicted was "happy" or "fear." The part of the face shown, and the size of the revealed area, randomly varied from trial to trial......... Posted by: Emily      Read more         Source

July 10, 2008, 9:41 PM CT

Middle Eastern families yield intriguing clues to autism

Research involving large Middle Eastern families, sophisticated genetic analysis and groundbreaking neuroscience has implicated a half-dozen new genes in autism. More importantly, it strongly supports the emerging idea that autism stems from disruptions in the brain's ability to form new connections in response to experience consistent with autism's onset during the first year of life, when a number of of these connections are normally made.

Interestingly, not all the affected genes were actually deleted, but only prevented from turning on offering hope that therapies could be developed to reactivate the genes. The study, led by scientists at Children's Hospital Boston and members of the Boston-based Autism Consortium, is the cover article in the July 11 issue of Science

Autism genes have been difficult to identify because the disorder is complex, with a variety of causes stemming from a number of possible genes or combinations of genes. In addition, since people with autism tend not to have children, most of the genes identified thus far aren't inherited from a parent, but instead are mutated during embryonic development, making them hard to track through traditional linkage studies in families.

Christopher Walsh, MD, PhD, chief of genetics at Children's Hospital Boston, approached the problem by studying Middle Eastern families. In traditional Arab societies, it is common for cousins to marry, increasing the likelihood that offspring will inherit rare mutations. Middle Eastern families also tend to have a number of children, making them ideal for mapping genes......... Posted by: Emily      Read more         Source

July 9, 2008, 9:05 PM CT

Frequent dialysis may benefit but at what cost?

More frequent hemodialysis sessions might improve the health of patients with end-stage renal disease (ESRD), but under reasonable assumptions of expected benefit, the overall costs are likely to increase, as per a research studyappearing in the September 2008 issue of the Journal of the American Society Nephrology (JASN). The findings indicate that strategies are needed to reduce the costs of delivering hemodialysis if patients receive hemodialysis more than three times a week.

Despite ongoing treatment with current in-center hemodialysis procedures, which involve three sessions a week for three to four hours at a clinic per session, patients with ESRD experience relatively poor health and high mortality rates. Published studies suggest that more frequent hemodialysis for patients may improve their quality and length of life and cut down on hospitalizations and other costs. In recent years, several hemodialysis centers around the world have explored this strategy, and two ongoing clinical trials in the United States are currently comparing frequent and conventional hemodialysis.

To assess the potential effects of hemodialysis frequency on life expectancy and costs, Dr. Glenn Chertow of the Stanford University School of Medicine in Stanford, CA, and colleagues from Stanford's Graduate School of Business and the Wharton School at the University of Pennsylvania examined data from a national registry that is representative of the US hemodialysis population. Using a sophisticated simulation model, they set out to determine if more frequent hemodialysis strategies could enhance longevity at a reasonable cost......... Posted by: Emily      Read more         Source