7th May 2014, 03:49 PM #1081
Re: Health Bulletin
Faulty DNA-copying may lead to cancer
Scientists have found that 'fragile sites' that can be a breeding ground for human cancers appear in specific areas of the genome where the DNA-copying machinery is slowed or stalled.
Each time a human cell divides, it must first make a copy of its 46 chromosomes to serve as an instruction manual for the new cell. Normally, this process goes off without a hitch.
But from time to time, the information isn't copied and collated properly, leaving gaps or breaks that the cell has to carefully combine back together.
Researchers have long recognised that some regions of the chromosome, called 'fragile sites', are more prone to breakage and can be a breeding ground for human cancers. But they have struggled to understand why these weak spots in the genetic code occur in the first place.
A comprehensive mapping of the fragile sites in yeast by a team of researchers from Duke University showed that fragile sites appear in specific areas of the genome where the DNA-copying machinery is slowed or stalled, either by certain sequences of DNA or by structural elements.
The study, which appears in Proceedings of the National Academy of Sciences, could give insight into the origins of many of the genetic abnormalities seen in solid tumours.
"Other studies have been limited to looking at fragile sites on specific genes or chromosomes," said Thomas D Petes, the Minnie Geller professor of molecular genetics and microbiology at Duke University School of Medicine.
"Ours is the first to examine thousands of these sites across the entire genome and ask what they might have in common," Petes said.
The term 'fragile sites' was first coined in the 1980s to describe the chromosome breaks that appeared whenever a molecule called DNA polymerase - responsible for copying DNA - was blocked in mammalian cells.
Since that discovery, research in the yeast Saccharomyces cerevisiae has shown that certain DNA sequences can make the polymerase slow down or pause as it makes copies. However, none of them have shown how those delays result in fragile sites.
In this study, Petes wanted to find the link between the copier malfunction and its genetic consequences on a genome-wide scale.
First, he knocked down the levels of DNA polymerase in yeast cells to ten-fold lower than normal. Then he used microarray or "gene chip" technology to map where segments of DNA had been rearranged, indicating that a fragile site had once been there.
Researchers found that the fragile sites were associated with sequences or structures that stalled DNA replication, esoteric entities such as inverted repeats, replication termination signals, and transfer RNA genes.
In addition, Petes found that these fragile sites created a surprisingly unstable genome, resulting in a chaotic milieu of rearrangements, duplications and deletions of pieces of DNA or even the gain or loss of entire chromosomes.
7th May 2014, 03:50 PM #1082
Re: Health Bulletin
Avian flu virus found among penguins in Antarctica
An international team of researchers have for the first time identified a new avian influenza virus in a group of Adelie penguins from Antarctica.
The virus is unlike any other circulating avian flu viruses.
While other research groups have taken blood samples from penguins before and detected influenza antibodies, no one had detected actual live influenza virus in penguins or other birds in Antarctica previously, said senior research scientist Aeron Hurt at the WHO Collaborating Centre for Reference and Research on Influenza in Melbourne, Australia.
The virus did not cause illness in the penguins but the study shows that avian influenza viruses can get down to Antarctica and be maintained in penguin populations, he said. "It raises a lot of unanswered questions," Hurt added. They include how often Avian Influenza Virus (AIVs) are being introduced into Antarctica, whether it is possible for highly pathogenic AIVs to be transferred there, what animals or ecosystems are maintaining the virus and whether the viruses are being cryo-preserved during the winters.
For the study, Hurt collected swabs from the windpipes and posterior openings of 301 Adelie penguins and blood from 270 penguins from two locations on the Antarctic Peninsula: Admiralty Bay and Rada Covadonga. The samples were collected during January and February 2013.
Using a laboratory technique called real-time reverse transcription-PCR, the researchers found AIV genetic material in eight (2.7%) samples, six from adult penguins and two from chicks. Seven of the samples were from Rada Covadonga. The researchers were able to culture four of these viruses demonstrating that live infectious virus was present.
8th May 2014, 12:06 AM #1083
Re: Health Bulletin
Chinese scientists claim breakthrough in H7N9 treatment
Chinese scientists have claimed a breakthrough in the treatment of H7N9 bird flu which affected over 200 people in the country since last year.
According to their study, a human blood protein has been found to be associated with the H7N9 fatality rate.
The study, published in Nature Communications on Tuesday, showed that blood plasma levels of angiotensin II are higher in H7N9 patients and could be used to predict their physical deterioration.
Angiotensin II is a human protein contained in plasma, the vascular wall, heart and kidney to regulate blood pressure. It is closely linked to acute lung injury.
H7N9 patients with higher levels of angiotensin II carry more viral load, said Li Lanjuan, researcher at the Chinese Academy of Engineering and a specialist in H7N9 prevention.
"It is particularly obvious in the second week of human infection. The angiotensin II level of patients in critical condition keeps going up, while that of mild cases tends to drop," Li was quoted as saying by the state-run Xinhua news agency on Tuesday.
Li added the new finding could help in clinical practice. Medical personnel could adopt more effective and reliable treatment measures for patients suffering different conditions.
"This study will provide a new perspective to H7N9 pathology and potential treatment for future cases," said Ed Gerstner, executive editor of Nature Communications.
The study was led by researchers of the First Affiliated Hospital of Zhejiang University, Chinese Academy of Medical Sciences and Chinese Centre for Disease Control and Prevention.
They collected plasma from 47 H7N9 patients in cities of Hangzhou, Shanghai and Nanjing and analyzed the correlation between angiotensin II and viral load.
H7N9 was first reported in China in March 2013. The virus causes severe disease in humans, including acute and often lethal respiratory failure.
The country has reported more than 200 human H7N9 cases.
8th May 2014, 12:06 AM #1084
Re: Health Bulletin
Scientists add new letters to alphabet of life
: Scientists, in a world first, announced on Wednesday they had added two letters to the genetic code that forms the chemical blueprint for life.
They said they had modified a bacterium so that it incorporated and replicated two DNA ingredients that are not found in nature.
The experiment, they said, was designed to show that the alphabet for DNA, which has existed for hundreds of millions of years, can be expanded through human intervention.
This is the first step on a longer road that could lead to revolutionary drugs and innovations in nanotechnology, they said.
DNA — deoxyribonucleic acid — is the set of hereditary instructions for making and sustaining life.
A long molecule in the heart of a cell, it comprises a double-stranded helix in the form of a twisted zipper. Its "teeth" are millions of so-called base pairs of letters, meaning chemicals that match up with each other. Adenine teams up with thymine to creating the A-T base pair, while cytosine links up with guanine to make the C-G base pair.
The new work, reported in the scientific journal Nature, adds a third, man-made pair to the helix. However, the inclusions only survive with external help and are removed from the genome once this support is removed.
"Life on Earth in all its diversity is encoded by only two pairs of DNA bases, A-T and C-G," said Floyd Romesberg at Scripps Research Institute at La Jolla, California.
"What we've made is an organism that stably contains those two plus a third, unnatural pair of bases."
Researchers have worked for nearly two decades on finding new molecules to serve as new DNA bases, the goal being to create proteins that have never existed before.
But the search faces many challenges. The new base pair would have to fit snugly alongside natural bases in the DNA code and not disrupt replication or transcription, the first step in creating a protein.
During these processes, the DNA "zipper" is opened, segments of it are copied to provide a template, and the zipper then closes up again.
Another problem is to make sure that the inserted base pairs are not attacked and removed by the cell's DNA repair mechanism.
In the new study, the researchers made a circular piece of DNA called a plasmid that contained the natural A-T and C-G combinations, as well as an unnatural base pair, called d5SICs and dNaM. The plasmid was then inserted into a common bacterium, Escherichia coli.
But then another problem surfaced: as the base pair does not exist in nature, the molecular building blocks to replicate them in the cell are also absent.
The researchers found the answer by adding these building blocks to the solution in which the E coli was suspended.
They also genetically engineered the E. coli so that it exuded an algae protein that, like a beast of burden, hauled these blocks across the cell membrane.
The new-fangled plasmid replicated smoothly and with very few flaws — something that is essential for maintaining healthy DNA — and the unnatural base pairs were not weeded out of the code. Researcher Denis Malyshev stressed that the process was controlled by two mechanisms, the building blocks in the fluid and the protein transporter.
Without them, the new base pairs left the DNA code, leaving the bacterium to function happily on its A-T C-G combination — in other words, there could be no runaway replication of unnatural code. The next step will be to get the new letters into RNA (ribonucleic acid), a slimmed-down derivative of DNA that helps to crank out proteins.
In a commentary also carried by Nature, biologists Ross Thyer and Jared Ellefson at the University of Texas at Austin warned that scientists had to address public fears about tampering with DNA or creating artificial organisms. "Attempts to expand the genetic alphabet bravely question the idea of the universal nature of DNA, and potentially draw criticism about the wisdom of tinkering with it," they said.
8th May 2014, 01:43 PM #1085
Re: Health Bulletin
'Super pill' to prevent heart attacks
A daily 'super pill' could save millions of lives by preventing heart attacks and strokes, suggests a new study which used data from several countries including India. The largest ever analysis on the use of a polypill in cardiovascular disease shows potential for improvements in patient care, researchers said.
Almost 1 in 4 patients adhered better to treatment; significant improvements in blood pressure and cholesterol, they said.
New data presented for the first time at the World Heart Federation's World Congress of Cardiology 2014 shows a significant improvement in both patient adherence and risk factor control when patients at high risk of heart attack or stroke receive a polypill, compared to usual care.
A polypill is a fixed dose combination of commonly used blood pressure and cholesterol lowering medications, along with aspirin, which helps prevent cardiovascular disease (CVD).
The Single Pill to Avert Cardiovascular Events project, led by researchers from The George Institute for Global Health, analysed data from 3,140 patients with established CVD or at high risk of CVD in Europe, India and Australasia. The results showed a 43% increase in patient adherence to medication at 12 months with the polypill, in addition to corresponding improvements in systolic blood pressure and LDL-cholesterol that were highly statistically significant. The largest benefits were seen among patients not receiving all recommended medications at baseline, which corresponds to most cardiovascular disease patients globally.
"These results are an important step forward in the polypill journey and management of cardiovascular disease," said Ruth Webster of the George Institute for Global Health. "An important finding from our analyses is that the greatest benefits from a polypill were for currently untreated individuals," said Webster.
CVD is the number one cause of death globally, killing 17.3 million people each year and it is expected to remain the world's leading cause of death in the near future, researchers said. "These results emphasize the importance of the polypill as a foundation for a global strategy on cardiovascular disease prevention," professor Salim Yusuf, President-elect of the World Heart Federation said. "It will improve patient access to essential medications at an affordable cost and wide use of the polypill can avoid several millions of premature CVD events," he said.
8th May 2014, 01:47 PM #1086
Re: Health Bulletin
We yawn to cool our brains: Study
Yawning cools the brain to improve arousal and mental efficiency, according to a new study.
Researchers led by psychologist Andrew Gallup of State University of New York at Oneonta, US found that yawning is linked with thermoregulation, and in particular, brain cooling.
Sleep cycles, cortical arousal and stress are all associated with fluctuations in brain temperature, yawning subsequently functions to keep the brain temperature balanced and in optimal homeostasis.
According to this theory, yawning should also be easily manipulated by ambient temperature variation, since exchange with cool ambient air temperature may facilitate lowering brain temperature.
Specifically, the researchers hypothesised that yawning should only occur within an optimal range of temperatures, ie, a thermal window.
To test this, Jorg Massen and Kim Dusch of the University of Vienna measured contagious yawning frequencies of pedestrians outdoors in Vienna, Austria, during both the winter and summer months, and then compared these results to an identical study conducted earlier in arid climate of Arizona, US.
Pedestrians were asked to view a series of images of people yawning, and then they self-reported on their own yawning behaviour.
Results showed that in Vienna people yawned more in summer than in winter, whereas in Arizona people yawned more in winter than in summer.
It turned out that it was not the seasons themselves, nor the amount of daylight hours experienced, but that contagious yawning was constrained to an optimal thermal zone or range of ambient temperatures around 20 degrees Celsius.
In contrast, contagious yawning diminished when temperatures were relatively high at around 37 degrees Celsius in the summer of Arizona or low and around freezing in the winter of Vienna.
Lead author Massen explained that where yawning functions to cool the brain, yawning is not functional when ambient temperatures are as hot as the body, and may not be necessary or may even have harmful consequences when it is freezing outside.
While most research on contagious yawning emphasises the influence of interpersonal and emotional-cognitive variables on its expression, this report adds to accumulating research suggesting that the underlying mechanism for yawning, both spontaneous and contagious forms, is involved in regulating brain temperature, researchers said.
In turn, the cooling of the brain functions to improve arousal and mental efficiency, they said.
The spreading of this behaviour via contagious yawning could therefore function to enhance overall group vigilance, they added.
8th May 2014, 06:03 PM #1087
Re: Health Bulletin
Teen depression kills love life later
Negative emotions suffered when one was young can have a lasting grip on love relationships well into middle-age, new research says.
"The fact that depression and anger experienced during the teenage years clung on to people, even through major life events such as child-rearing, marriages and careers, was surprising," said Matthew Johnson, a researcher at University of Alberta in Canada.
The researchers took on to crack the code to happiness by exploring the long reach of depression and anger over more than two decades.
"We assume that high school experiences fade away. Symptoms of depression and expressions of anger can endure over many large events in life. How you grow and change over those early years becomes crucial to future happiness," said Johnson, an assistant professor of human ecology.
The researchers surveyed 178 women and 163 men through their transition to adulthood from age 18 to 25, at age 32 and on the quality of their intimate relationships at age 43.
As individuals, people can help themselves by "recognising the fact that where they are in their couple relationship now is likely shaped by earlier chapters in their lives", Johnson said in a paper published in the Journal of Family Psychology.
9th May 2014, 12:21 PM #1088
Re: Health Bulletin
Soon, cheap portable chip for instant blood tests
Scientists are developing a portable, credit-card-sized chip that can be used to run instant blood tests to detect anything from HIV to diabetes.
These labs-on-a-chip would not only be quick —results are available in minutes - but also inexpensive and portable, researchers said. They could be used miles from the nearest medical clinic to test HIV, diabetes etc. they said. But as powerful as they may be, they could be far better, said Shiyan Hu, an associate professor of electrical and computer engineering at Michigan Technological University.
Generally, a lab-on-a-chip (LOC) can run no more than a test or two because the chips are designed manually, said Hu. If the LOC were made using computer-aided design, you could run dozens of tests with a single drop of blood.
"In a short time, you could test many conditions. This really would be an entire lab on a chip," he said.
9th May 2014, 12:21 PM #1089
Re: Health Bulletin
Brain prepares mothers for baby-bonding
Pregnant women show increased activity in the area of the brain related to emotional skills as they prepare to bond with their babies, according to a new study.
Scientists at Royal Holloway, University of London, found that pregnant women use the right side of their brain more than new mothers do when they look at faces with emotive expressions.
"Our findings give us a significant insight into the 'baby brain' phenomenon that makes a woman more sensitive during the child bearing process," said Dr Victoria Bourne, from the Department of Psychology at Royal Holloway.
"The results suggest that during pregnancy, there are changes in how the brain processes facial emotions that ensure that mothers are neurologically prepared to bond with their babies at birth," Bourne said.
Researchers examined the neuropsychological activity of 39 pregnant women and new mothers as they looked at images of adult and baby faces with either positive or negative expressions.
The results showed that pregnant women used the right side of their brain more than new mothers, particularly when processing positive emotions.
The study used the chimeric faces test, which uses images made of one half of a neutral face combined with one half of an emotive face to see which side of the participants' brain is used to process positive and negative emotions.
"We know from previous research that pregnant women and new mothers are more sensitive to emotional expressions, particularly when looking at babies' faces," Bourne said.
"We also know that new mothers who demonstrate symptoms of post-natal depression sometimes interpret their baby's emotional expressions as more negative than they really are," Bourne added.
"Discovering the neuropsychological processes that may underpin these changes is a key step towards understanding how they might influence a mother's bonding with her baby," Bourne said.
10th May 2014, 12:19 PM #1090
Re: Health Bulletin
Frequent arguments can drive you to early grave
Frequent arguments with partners, relatives or neighbours triples risk of death from any cause in middle age. Men and those not in work seemed to be the most vulnerable, scientists have found.
Evidence suggests supportive social networks and strong relationships are good for general health and well-being. But scientists were curious on whether stressors inherent in family relationships and friendships had any impact on the risk of death from any cause.
They therefore quizzed almost 10,000 men and women aged 36 to 52 about their everyday social relationships. All the participants were already taking part in the Danish Longitudinal Study on Work, Unemployment and Health.
The researchers focused particularly on who, among partners, children, other relatives, friends and neighbours, made excess demands, prompted worries, or was a source of conflict, and how often these arose. They also considered whether having a job made any difference.
The health of the study participants was tracked from 2000 to the end of 2011, using data from the Danish Cause of Death Registry.
Between 2000 and 2011, 196 women (4%) and 226 men (6%) died. Almost half the deaths were from cancer, while heart disease/stroke, liver disease, and accidents and suicide made up the rest.
Around one in 10 study participants said that their partner or children were a frequent or constant source of excess demands and worries; around one in 20 (6%) and a further 2% claimed this for relatives and friends, respectively.
Similarly, 6% had frequent arguments with their partner or children, 2% with other relatives, and 1% with friends or neighbours.
After taking account of a range of influential factors, including gender, marital status, long term conditions, depressive symptoms, available emotional support, and social class, as defined by job title, the analysis indicated that frequent worries or demands generated by partners and/or children were linked to a 50%-100% increased risk of death from all causes.
But constant arguing seemed to be the most harmful for health. Frequent arguments/conflicts with anyone in the social circle - ranging from partners and relatives to friends and neighbours — were associated with a doubling to tripling in the risk of death from any cause compared with participants who said these incidents were rare.
Being out of work seemed to amplify the negative impact of social relationship stressors. Those who were unemployed were at significantly greater risk of death from any cause than those who were exposed to similar stressors but had a job.
And men seemed to be particularly vulnerable to the worries and demands generated by their female partners, with a higher risk of death than that normally associated with being a man or with this particular relationship stressor.
The authors accept that personality may have a role in how people perceive, generate, and respond to stress, and so may influence an individual's risk of an early death.
But they conclude that skills in conflict management may help to curb premature deaths associated with social relationship stressors.