XML Feed for RxPG News   Add RxPG News Headlines to My Yahoo!   Javascript Syndication for RxPG News

Research Health World General
 
  Home
 
 Latest Research
 Cancer
 Psychiatry
 Genetics
 Surgery
 Aging
  Parkinson's
  Dementia
   Alzheimer's
 Ophthalmology
 Gynaecology
 Neurosciences
 Pharmacology
 Cardiology
 Obstetrics
 Infectious Diseases
 Respiratory Medicine
 Pathology
 Endocrinology
 Immunology
 Nephrology
 Gastroenterology
 Biotechnology
 Radiology
 Dermatology
 Microbiology
 Haematology
 Dental
 ENT
 Environment
 Embryology
 Orthopedics
 Metabolism
 Anaethesia
 Paediatrics
 Public Health
 Urology
 Musculoskeletal
 Clinical Trials
 Physiology
 Biochemistry
 Cytology
 Traumatology
 Rheumatology
 
 Medical News
 Health
 Opinion
 Healthcare
 Professionals
 Launch
 Awards & Prizes
 
 Careers
 Medical
 Nursing
 Dental
 
 Special Topics
 Euthanasia
 Ethics
 Evolution
 Odd Medical News
 Feature
 
 World News
 Tsunami
 Epidemics
 Climate
 Business
Search

Last Updated: Aug 19th, 2006 - 22:18:38

Dementia Channel
subscribe to Dementia newsletter

Latest Research : Aging : Dementia

   DISCUSS   |   EMAIL   |   PRINT
HIV mutation is clue to why only some people develop AIDS dementia
Jul 26, 2006, 13:12, Reviewed by: Dr. Ankush Vidyarthi

"If we identify the quintessential neurotoxic variant of HIV, could we use that as a predictor of HIV dementia?"

 
The study of 18 HIV-positive subjects shows that HIV in the brain and central nervous system is genetically different from HIV that lives in the blood and peripheral tissues.

Moreover, serious cognitive impairment among the study subjects was correlated with the presence of a particular mutation in the HIV envelope gene.

The study appears in the July 2006 issue of Brain. It was led by Satish K. Pillai, PhD, a staff research associate at SFVAMC and a postdoctoral fellow at the University of California, San Francisco.

Pillai and his associates generated 456 nucleotide sequences of HIV from the blood and cerebrospinal fluid of the study participants. They chose to focus on the viral envelope gene, which interacts with receptors on the surfaces of host cells. "That's the gene that's most likely to vary between tissues, because it evolves rapidly and allows the virus to dock with different cell types," Pillai says.

According to Pillai, an analysis of the sequence data suggests that HIV is "genetically compartmentalized" between the central nervous system (CNS) and the blood, "which means that the virus is replicating in relative isolation in these tissues, with very little exchange of genetic information between the two populations."

The researchers also analyzed the sequences in search of a "genetic signature" common to the CNS-specific viruses in all 18 individuals, recounts Pillai. They found such a pattern, consisting of four amino acids, within a subregion of the viral envelope gene known as the V3 loop. "The identification of these signature mutations presents convincing evidence that HIV adapts to the local environment within the central nervous system and, moreover, that commonalities in this environment exist across individuals," he asserts.

Another mutation in the V3 loop appeared consistently in virus from study subjects who demonstrated the most severe cognitive impairment. This mutation was absent in sequences from subjects with little or no cognitive deficit. "In other words," says Pillai, "there appears to be a particular HIV mutation that is associated with dementia." He cautions that this result is "suggestive, not conclusive," because of the study's small sample size.

This information "may be clinically relevant in terms of treatment," Pillai explains. "If we identify the quintessential neurotoxic variant of HIV, could we use that as a predictor of HIV dementia?" He says that such knowledge could also help care providers make "guided therapeutic decisions – for example, the detection of particular viral genotypes may lead physicians to select for antiretroviral regimens that cross the blood-brain barrier into the CNS most efficiently." Or, he speculates, "we might actually try to design a drug to target these genetic variants that are responsible for the neurological damage."

Pillai notes that the issue of HIV dementia is particularly important in regions outside North America and Europe where state-of-the-art antiretroviral medications are not widely available and HIV infection frequently leads to dementia.

SFVAMC staff physician Joseph K. Wong, MD, associate professor of medicine at UCSF and senior author of the study, adds, "In addition to the implications of this new knowledge for the 40 million people infected with HIV, this study may also contribute to our general understanding of viral encephalitis," or brain inflammation caused by other viruses. "These results suggest that specific features of viral components themselves, and not just the immune response to viral infection, may be responsible for direct damage to the nervous system."

Pillai says that even though the study included almost 500 gene sequences, it is still exploratory: "We are now in the process of expanding this to a survey of 100 to 150 individuals."
 

- The study appears in the July 2006 issue of Brain.
 

www.ucsf.edu

 
Subscribe to Dementia Newsletter
E-mail Address:

 

The study's co-authors were Sergei L. Kosakovsky Pond, PhD, of UC San Diego; Yang Liu, PhD, of Monogram Biosciences, South San Francisco; Benjamin M. Good, MS, of UCSD and VA San Diego Healthcare System; Matthew C. Strain, MD, PhD, of UCSD; Ronald J. Ellis, MD, PhD, and Scott Letendre, MD, of UCSD and the HIV Neurobiological Research Center, San Diego; Davey M. Smith, MD, of UCSD and VASDHS; Huldrych F. Gunthard, MD, of University Hospital Zurich, Switzerland; Igor Grant, MD, Thomas D. Marcotte, PhD, and J. Allen McCutchan, MD, of UCSD and HNRSC; and Douglas D. Richman, MD, of UCSD and VASDHS.

The study was supported by funds from the National Institutes of Health that were administered in part by the Northern California Institute for Research and Education and by the Department of Veterans Affairs.

NCIRE is the largest research institute associated with a VA medical center. Its mission is to improve the health and well-being of veterans and the general public by supporting a world-class biomedical research program conducted by the UCSF faculty at SFVAMC.

SFVAMC has the largest medical research program in the national VA system, with more than 200 research scientists, all of whom are faculty members at UCSF.

UCSF is a leading university that consistently defines health care worldwide by conducting advanced biomedical research, educating graduate students in the life sciences, and providing complex patient care.


Related Dementia News

Occupational therapy improves quality of life for dementia patients
Hope remains for Alzheimer's sufferers
Cognitive Decline is Often Undetected - Study
CATIE Study: Antipsychotics in Alzheimer's No Better Than Placebo
Mediterranean diet associated with a lower risk for Alzheimer’s disease
Omega-3 fatty acid supplements may slow cognitive decline
Microscopic brain damage detected in early Alzheimer's disease
Novel technique can identify early cellular damage in Alzheimer's disease
Cathepsin B - Part of protective mechanism against Alzheimer's
Boosting ubiquitin C-terminal hydrolase L1 (Uch-L1) restores lost memory


For any corrections of factual information, to contact the editors or to send any medical news or health news press releases, use feedback form

Top of Page

 

© Copyright 2004 onwards by RxPG Medical Solutions Private Limited
Contact Us