STRESS IMPACT
Studies say it interferes with memory and may trigger an asthma attack
Stress impacts memory, other brain functions...
WASHINGTON
Stress activates an enzyme in the brain that interferes with short-term memory and other functions of the prefrontal cortex, located just above the eyes, in rats and monkeys, according to a study published in Science.
Known as "protein kinase C" (PKC), the enzyme is also implicated in bipolar disorder and schizophrenia, said Amy Arnsten of Yale Medical School in New Haven, Connecticut, WHO led the study. She said the first sign of psychological problems becomes evident during major, stressful changes in lifestyle, such as when a young person leaves home for university.
By acting on the prefrontal cortex, PKC could be a factor in distractibility, impaired judgment, impulsivity, and thought disorder, all of which have been tied to this brain region.
Arnsten said it gives scientists "some rational understanding of what is causing these irrational disorders." "I think it's an important breakthrough in understanding the causes of some kinds of mental illnesses," since it could lead to new PKC-inhibiting drugs, she added.
Arnsten also said other recent research has also found high PKC activity among people with mental disorders. She said her team used chemical substances to provoke stress in laboratory rats and monkeys in a controlled environment. Similar stress levels are found in humans when confronted with a loud noise or before an exam, she added.
...quadruples risk of asthma attack
PARIS
A stressful event can more than quadruple the likelihood of an asthma attack within two days and nearly double the risk of an attack up to seven weeks after the event, a study said.
British doctors asked 60 children diagnosed with chronic asthma to write a daily diary of any symptoms and measure their peak flow, a term for their respiratory strength, each day. Over the next 18 months, the youngsters were interviewed about their asthma and asked about events in their life.
A severely stressful event, such as a death, a birth, parental divorce, and moving home, increased the risk of an asthma attack within the first two days by a factor of 4.69. In the period three to 10 days after the event, there was no increased risk of an attack. However, there was also a delayed effect that endured for weeks. The asthma-tics were 1.8 times likelier to have an attack five to seven weeks after the event compared with calmer times.
The research led by Seija Sandberg of the University College London appeared in Thorax, a journal of the British Medical Association.
Asthma affects around 150 million people worldwide and kills 130,000 each year.
WHO okays first global standard for genetic test
GENEVA
The World Health Organization (WHO) has approved the first international standard for a human genetic test, ensuring that testing for a genetic predisposition to thrombosis is accurate worldwide.
"Establishment of the first international standard for a genetic test is an important milestone," said David Wood, quality and safety coordinator at WHO. "Genetic testing procedures are playing a vital and growing part in clinical medicine. This new standard will help to ensure that the tests are giving accurate results worldwide," he added.
The test covered by the new common standard for all countries relates to a genetic mutation present in 20 to 40 percent of cases of thrombosis, WHO said.
Heavy computer use linked to glaucoma
PARIS
Heavy users of computers, especially those WHO are shortsighted, may be at risk for glaucoma, according to a study in the Journal of Epidemiology and Community Health.
Japanese doctors assessed the sight of more than 10,200 Japanese workers, measuring them for visual acuity and signs of glaucoma. The volunteers were also asked to fill in questionnaires about their computer use at home or in the office and any history of eye disease. A total of 165 workers (1.6 percent) turned out to have suspected glaucoma. Those who were heavy computer users--defined as working onscreen more than eight hours a day--were twice as likely to have glaucoma than light or medium users. Of the 165 with glaucoma, 136 also had myopia.
Glaucoma is a slow, gradual disease of the optic nerve that often goes undetected. The authors speculate that the optic nerve in shortsighted people may be more vulnerable to computer stress than in normal-sighted people. If so, that would be dramatic news, given that so many hundreds of millions of people around the world now work at computer terminals at offices and at home.
Drug-dispensing contact lens
SINGAPORE
Scientists in Singapore have invented a contact lens capable of releasing precise amounts of medication to treat glaucoma and other eye diseases, doing away with eye drops. The government-backed Institute of Bioengineering and Nanotechnology (IBN) is now looking for partners to commercialize the product, which also minimizes the harmful seepage of drugs to other body organs.
"Glaucoma accounts for 20 percent of blindness in Singapore and is rapidly becoming the second major cause of blindness in Asia after cataracts," the IBN said. "Contact-lens wearers with dry eyes may also benefit from this invention as the material can be modified to produce self-lubricating contact lenses," it added.
According to industry studies, the eye care market is undergoing exponential expansion due to population growth, ageing, widening of licensing for prescription of ophthalmic drugs and novel technologies. The market for ophthalmic drugs worldwide is estimated at about US$4 billion per year, growing at 10 to 15 percent annually.
Most ophthalmic medications are now delivered through eye drops but the drugs usually mix with tears and reach other organs through the bloodstream, potentially causing serious side effects.
IBN developed a simple method of making entirely new polymeric lens materials whereby drugs are added directly into the solution that eventually becomes the lens, a spokesman said. The drugs sit in the structure of the lens material and are released into tiny channels from which they slowly leak onto the surface of the eye.
IBN scientist Edwin Chow, a coinventor of the new contact lens, said the delivery system can be tailored to different drugs and remain effective for extended periods. "Drugs may also be encapsulated in polymeric nanoparticles which are then dispersed through the lens material," he said. "By altering the size, concentration, and structure of these polymeric nanoparticles, we can further control the drug delivery rates, while retaining the appropriate lens clarity."
Uncooled vaccines could revolutionize public health
LONDON
A new science technique inspired by natural processes millions of years old could revolutionize public health care by allowing vaccines to be stored for years without refrigeration, British scientists said.
The technology, modeled on a desert plant's ability to survive drought, would spell radical improvements in medical access to child-ren in developing countries who were previously too far from the so-called "cold chain" now needed for vaccines.
Bruce Roser, chief scientist at Cambridge Biostability, said his company had created the technology called "stable liquid" based on anhydrobiosis, the process that allows cells to be preserved in a dried-out state. "If it works out as we hope, it will increase access to vaccines across the developing world and stop children dying," Roser said. He said the technique was modeled on the natural process seen in organisms like the resurrection plant, which dries up completely in drought conditions only to burst into life when rain falls.
The resurrection plant has an "unusual but simple sugar, which has the property of turning into a thick syrup when it dries out rather than crystallizing," he said. "We have taken this technology and made it work on the lab bench. We have put these vaccines in a solution of this syrup. We dry it and it turns into a syrup which becomes more and more viscous as we remove more and more water until imperceptibly it solidifies as a glass. It is very similar to fossilized insects trapped in amber, which are preserved for millions of years."
Cambridge Biostability's first goal is to develop a fridge-free five-in-one vaccine to immunize against diphtheria, tetanus, whooping cough, hemophilus influenza type B, and hepatitis B.
Gene shield against mad-cow disease
WASHINGTON
A gene may protect some people from Creutzfeldt-Jakob disease. Transgenic experiments on mice show that substitution of an amino acid in the prion proteins will produce symptoms different from variant Creutzfeldt-Jakob disease (vCJD), said a study published in Science.
So far, vCJD has only been found in persons WHOse genetic code has been programmed to allow a specific spot in the prions to contain methionine amino acid. Transmission from cow to human is limited by a barrier that usually disappears when the disease is passed from one animal to another of the same species, the study said.
The experiments found that the barrier persists in mice expressing a human valine amino acid in the place of the methionine. The valine hindered vCJD, as well as mad cow, or bovine spongiform encephalopathy (BSE). The researchers, led by Jonathan D. F. Wadsworth at University College London, concluded that some persons will be more resistant to vCJD, and that those persons WHO do get it, will have different symptoms.
High doses of vitamin E can be dangerous
WASHINGTON
Dietary supplements of vitamin E, recommended by some doctors to reduce the risk of heart disease, can be dangerous in high doses, according to a study published by the American Heart Association.
"Increasing doses of vitamin E were linked to an increase in death," said lead author Edgar Miller, associate professor of medicine at Johns Hopkins University in Baltimore.
The study found no increased risk of death with a dose of 200 international units per day or less, and there may even be some benefit. "However, an increased risk was found at amounts above 200 IU per day and significant risk of death was found starting at 400 IU a day," said the report.
"Those who take greater than 400 IU of vitamin E a day are about 10-percent more likely to die than those who do not," it said. "Many people who take vitamin E supplements take between 400 and 800 IU in a single capsule," said Miller.
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