Tibetans’ ability to survive at high altitude without getting sick has been linked to genes for the first time in a study published in Science.

Tibetans live in one of the highest regions of the world yet do not experience the symptoms associated with low levels of oxygen found in these high altitudes.

Scientists have found 10 genes that could explain why Tibetans living on Mountaintops don’t get sick

By comparing the genes of 31 Tibetans with a group of 90 Japanese and Chinese lowland people, scientists discovered 10 genes linked to a resistance to altitude sickness. Two of these genes have been linked to haemoglobin, the component in blood, which carries oxygen around the body.

Scientists have long known that Tibetans produce a low number of red blood cells but it is not understood how the body survives on such decreased levels of oxygen. By doing so, doctors predict it will help to understand and treat altitude sickness in mountaineers and other illnesses.

“What’s unique about Tibetans is they don’t develop high red blood cells counts,” said Professor Josef T. Prchal, a senior author on the study. “If we can understand this, we can develop therapies for human disease.”

The study was a joint collaboration between researchers at the University of Utah and Qinghai University Medical School.

Smallpox vaccine helped to curb AIDS?

Ending the worldwide smallpox vaccination may have lead to the explosive spread of HIV, scientists in a new study have suggested.

Smallpox immunisation gradually stopped between 1950s and 1970s, and since then, the rates of HIV have increased around the world.

The researchers from the study analysed white blood cells taken from people recently immunised against smallpox. They found that HIV replicated at lower levels from the vaccinated group compared with those from a control group who had not been immunised against smallpox.

According to the research, the smallpox vaccine cut HIV replication five-fold.

“There have been several proposed explanations for the rapid spread of HIV in Africa, including wars, the reuse of unsterilised needles and the contamination of early batches of polio vaccine. However, all of these have been either disproved or do not sufficiently explain the behaviour of the HIV pandemic,” said Dr Raymond Weinstein the lead researcher of the study, from the George Mason University in Virginia.

Mobile phones – no risk of brain tumours, scientists say

The largest study of mobile phone usage has found no link to suggest it increases the risk of brain tumours although the results are inconclusive, scientists report.

The study, carried out between 2000 and 2004, involved interviewing thousands of people from 13 countries about mobile phone usage and health.

The researchers compared the results from a group of patients suffering from either glioma or meningioma (types of tumour) with a similar number of health adults acting as a control group. No children took part in the study.
“Overall, this research has not shown evidence of an increased risk of developing a giloma or meningioma brain tumour as a result of using a mobile phone,” said Patricia McKinney an epidemiologist at the University of Leeds and one of the leaders of the study.

“The balance of evidence from this study, and in the previously existing scientific literature, does not suggest a causal link between mobile phone use and risk of brain tumours,” said Anthony Swerdlow, an epidemiologist at the Institute of Cancer Research and one of the leaders of the study.

Along with the other authors of the study, he warns that this does not provide assurances that there are no health risks associated with mobile phone usage: “The duration of phone use for which we yet have evidence is currently limited, however, and we have virtually no information for use of mobile phones for longer than 15 years.”

Sleep study – too much or too little

Sleeping fewer than six hours each night leads to a higher chance of dying prematurely, a new study has found. But consistently getting too much sleep may increase the risk of developing fatal illnesses the researchers found after analysing 1.3 million participants over 25 years.

“While short sleep may represent a cause of ill-health, long sleep is believed to represent more an indicator of ill-health,” said Francesco Cappuccio, leader of the Sleep, Health and Society Programme at the University of Warwick.

“Modern society has seen a gradual reduction in the average amount of sleep people take, and this pattern is more common amongst full-time workers, suggesting that it may be due to societal pressures for longer working hours and more shift-work,” added Cappuccio.

The study, a collaboration between the University if Warwick and the Federico II University Medical school in Naples, is published in the Sleep journal.

Vitamin D kick-starts the immune system

Vitamin D plays a crucial role in the body’s immune system, scientists at the University of Copenhagen have found. The vitamin is required to trigger a vital signaling enzyme which activates T-cells to seek out and destroy invading microbes.

“If the T-cells can’t find enough Vitamin D in the blood, they won’t even begin to mobilise,” said Professor Carsten Geisler of the University of Copenhagen, who led the research published in Nature. The findings “could help us to combat infectious diseases and global epidemics,” he added.

Gene interaction linked to Parkinson’s disease

Two genes that work together to remove damaged mitochondria from cells have been discovered, paving the way for potential treatments of Parkinson’s disease. Scientists studied the interaction of the genes, called parkin and PINK1, in fruit flies, and hope to develop ways to keep cells healthy.

“From this, we may be able to slow down or even stop Parkinson’s from progressing,” said Kieran Breen, director of research and development at the Parkinson’s Disease Society. The study is published in the Proceedings of the National Academy of Sciences.

Bacteria make us hungry

Intestinal bacteria can increase appetite and insulin resistance, calling into question whether it’s just lack of exercise and bad food that make people overweight, according to research published in Science magazine. By transferring certain kinds of intestinal bacteria into mice, the team of scientists was able to induce an increased appetite, obesity, elevated blood sugar levels, and insulin resistance in the rodents.

“Our results suggest that excess caloric consumption is not only a result of undisciplined eating, but that intestinal bacteria contribute to changes in appetite and metabolism,” said Andrew Gewirtz, professor of Pathology at Emory University School of Medicine.

HIV hides in bone marrow

The HIV virus returns after treatment because it lays dormant in bone marrow, a new study published in Nature Medicine has found. When the bone marrow produces blood cells, the HIV virus is reactivated. The aim is to find a way to reach the virus in hiding so patients don’t need to be on drugs for life. “One way is to find a way to push the cells from latency to go into an active infection while patients are still on their drugs,” said Kathleen Collins of the University of Michigan, one of the authors of the study.

Polio to be eradicated in Africa

More than 85 million children in 19 countries across West and Central Africa will be vaccinated against polio as part of a mass campaign to end a year-long epidemic.

Over 40,000 volunteers and health workers will go from door to door giving the oral polio vaccine to all children under the age of five.

Africa has made progress in the fight against polio but the virus has not been entirely eradicated, with outbreaks being reported in nine countries over the last six months.

The campaign, a joint collaboration between the Red Cross and the United Nations (UN), is being funded by Rotary International, a volunteer humanitarian organisation.

TB and leprosy: genetic variant found

A genetic variant has been found to improve protection against Tuberculosis (TB) and leprosy. Researchers discovered that a genetic variant of LTA4H improves resistance by studying patients with TB in Vietnam and leprosy in patients from Nepal. “This is an interesting finding and opens up a potential new target for drugs against these diseases,” said Dr Sarah Dunstan from the Oxford University Clinical Research Unit, part of the Wellcome Trust’s South-East Asia programme.

The study, published in Cell, was a collaboration between researchers at the University of Washington and the Oxford University Clinical Research Unit in Vietnam.