Tuesday, February 23, 2010

Crease on earlobe? Then take care of your eyesight

Syed Akbar
Hyderabad, Feb 23: Diagonal crease on earlobe has long been associated with coronary heart disease and latest research by a group of Indian scientists link the presence of earlobe crease to sight-threatening diabetes retinopathy.

People with crease on their earlobes are relatively more prone to diabetes retinopathy (damage to retina, which ultimately causes blindness) than those without crease on their earlobes.

A team of researchers from Sankara Nethralaya, comprising Dr Tarun Sharma, Dr Rajiv Raman, Dr PK Rani and Dr V Kulothungan, has noticed that earlobe crease is present in nearly 60 per cent of urban south Indian population with diabetes, aged above 40 years. The presence of earlobe crease is somewhat related to sight-threatening diabetic retinopathy.

"The study is representative of a large population and results could be extrapolated to the whole of urban India," says Dr Tarun Sharma.

According to the researchers, in predicting any diabetic retinopathy, the presence of earlobe crease had sensitivity of 60.4 per cent, and specificity, 40.5 per cent. The earlobe crease was observed in nearly 60 per cent of the urban south Indian population.

The study revealed that the subjects in the earlobe crease group were older, had longer duration of diabetes and had poor glycemic (blood sugar) control. They had a higher socio-economic status as compared to the group without earlobe crease. "This could be an indirect measure of the population that is at a greater risk for coronary artery disease," the study pointed out.

The team also noticed that people with earlobe crease had almost twice the risk of developing sight-threatening diabetic retinopathy. The researchers explain that people with earlobe crease had loss of elastin (a protein that gives skin its shape). This loss of elastin in retinal blood vessels leads to increased leakage and dilatation, and gradual blindness.

"We also speculate the presence of ischemia (shortage of blood supply to particular part or parts of the body) in people with earlobe crease. The focal ischemia of the dermal fat might cause ear lobe crease, and ischemia in retina causes sight- threatening changes," the scientists pointed out.

Saturday, February 13, 2010

Novel human influenza A virus may evolve into a supervirus with unique genetic makeup

Syed Akbar
Hyderabad, Feb 13: The novel human influenza A virus, which is currently creating problems in north India particularly Delhi, may evolve into a "supervirus" with unique genetic make-up, infecting and replicating in multiple hosts.

This supervirus may develop resistance to all know anti-viral drugs, warn city biologists, adding that "future preparedness is mandatory".

A team of scientists from the city-based Centre for Cellular and Molecular Biology, Vellore Institute of Technology and Florida International University, Miami, USA, found that the novel influenza virus A/H1N1/2009 attaches to the same glycosylation receptor sites as its predecessor influenza A/H1N1/2008 virus.

"But it is antigenically different and may have the potential for initiating a significant pandemic". The study may facilitate the development of better therapeutics and preventive strategies, as well as impart clues for novel H1N1 diagnostic and vaccine development.

The researchers' team comprising Dr Shailendra K Saxena, Dr Niraj Mishra, Dr Rakhi Saxena, Dr ML Arvinda Swamy and Dr Shrish Tiwari noted that the evolution of H1N1 2009 by triple reassortment (from three different hosts and co-infections with other influenza A viral strains) is an alarming concern "because it suggests that the virus is not only assorting in multiple hosts, but also getting more chances to reassort in humans".

Along with antigenic shift and antigenic drift, H1N1 may evolve into a novel influenza A supervirus, which may be antigenenically unique, the study pointed out adding that it may transmit as well as infect and replicate in multiple hosts. "It may have resistance to known antivirals. Therefore, future preparedness is mandatory. Long-term preventive measures should be considered along with short-term prevention".

According to the scientists, the antigenic analysis showed H1N1 strains of 2009 and 2008 have large differences in antigenicity. This finding might be correlated with the large penetrance of H1N1/2009 because this strain has novel antigenicity. Therefore, the human population lacks herd immunity.

Co-infections during bouts of influenza might play a crucial role in the evolution of H1N1 and may cause the development of resistance to known antivirals. "This virus, therefore, can be used to study the involvement of new determinants, which may help us to develop effective vaccines against lethal H1N1 strains," the scientists observed.

The team members emphasised the need for studies on the evolution of H1N1 immunity, as for the first time, they provided evidence that H1N1/2009 uses the same glycosylation sites as its predecessor H1N1/2008 and may have a potential to initiate a more seriously mortal pandemic, owing to its antigenic difference with H1N1/2008.

"Our study may facilitate the development of better therapeutics and preventive strategies," they said.

Wednesday, February 10, 2010

CCMB develops system to identify sub-types of HIV

Syed Akbar
Hyderabad, Feb 8: The city-based Centre for Cellular and Molecular Biology has developed a system to identify various sub-types of HIV, which will ultimately help in the development of drug to fight human immunodeficiency virus and AIDS.
HIV-1, which causes Acquired Immune Deficiency Syndrome, exhibits very high genetic diversity with different variants or subtypes prevalent in different parts of the world.
According to CCMB senior scientist Dr Somdatta Sinha and senior research fellow Aridaman Pandit, the existing methods to classify HIV-1 sequence subtypes was based on the focus on specific genes/regions and they lack the capability to analyse whole genome variations.
To overcome the problem, the CCMB team adopted a new approach to identify the distinctive genomic signature in different HIV-1 subtypes. The team applied the approach to cluster the five unclassified HIV-1 sequences from Africa and Europe, and predicted their possible subtypes.
"HIV hijacks the human cellular machinery to make its own proteins and is completely dependent upon human cells for its survival and growth. There exist two types of HIV, of which type-1 (HIV-1) virus is more infectious, and has higher mortality rate," Aridaman Pandit told this correspondent.
High genetic diversity for HIV-1 exists that is a result of high rates of mutation and multiple cross-species transfers from chimpanzees to human. Because of high mutation rate, variants continuously emerge that have subtle genetic differences.
As a response to HIV-1, the immune system of human engages its cells to eliminate the pathogen. Human immune system is highly variable and has evolved to flight against a large number of pathogens. However, the variability of immune system leads to differences in response of every infected individual.
"Thus, HIV continuously evolves due to both its high mutation rate and the necessity to evade human immune system leading to emergence of new variants. Inability of human immune system to control HIV-1 spread and lack of cure both add to the success story of HIV-1 as a pathogen," they said.
Some of the variants adapt towards the human sub-population in a geographical region and are called subtypes of HIV. These subtypes represent antigenically distinct types of strains. Subtle genetic differences that exist in HIV subtypes lead to difference in their infectivity, disease progression, mode of transmission, and development of resistance towards drugs.
Thus, proper recognition of HIV subtype is important for monitoring the ongoing epidemics. As different subtypes also have different rates to develop the drug resistance, it can also play a role in monitoring the drug therapy.
"Our methodology of detecting the genomic signatures can be used to detect emergence of new subtypes, and can also curate HIV-1 sequences that the earlier methods could not classify properly," the CCMB scientists added.