Japan experts find way to block allergic reactions

HONG KONG (Reuters) ¿ Scientists in Japan may have found a way to stop reactions such as wheezing, itching and swelling after identifying a key molecule which is crucial for the body to mount an allergic response.

They discovered the STIM1 molecule and found that when it was gone the body was no longer susceptible to allergens, the latest issue of Nature Immunology reported.

"If we can block STIM1 function, then we can block allergic reactions because STIM1 is very important for inducing allergies," Tomohiro Kurosaki, group director of the Laboratory for Lymphocyte Differentiation at the RIKEN Research Center for Allergy and Immunology said in a telephone interview.

Some people are allergic to common allergens such as dust and pollen, although sensitivities vary from person to person and it is possible to be allergic to just about anything.

Prior studies have established that allergens cause a build-up of calcium in what are called mast cells, located near the skin — kick-starting the process which leads to rashes, sneezing, itching and swelling.

What Kurosaki's team found was that the concentration of calcium was dependent on the presence of STIM1.

Using specially bred mice that lacked STIM1, the researchers found that they were resistant to stimuli normally capable of provoking severe allergic reactions.

Looking ahead, Kurosaki said the finding would help in the search for therapies to stop allergies. "If we can block calcium increase then ... subsequent allergic reactions can be blocked," Kurosaki said.

Improvements seen with replacement hips

NEW YORK (Reuters Health) — The substantial benefits of hip replacement for osteoarthritis are sustained in the long-term, British investigators report.

The short-term effectiveness of hip replacement surgery has been well documented, Dr. Cyrus Cooper and his associates note in the medical journal Arthritis Care and Research, but there's not much information about the durability of the benefits.

In 1998, Cooper, at the University of Southampton, and his team reported the results of a study involving 643 osteoarthritis patients who underwent hip replacement in the early 1990s, and 643 matched "controls." Their current report involves follow-up for an average of another 8.3 years for 282 of the original patients and 295 controls.

According to responses to a standard questionnaire, physical function scores improved from 20 initially to 30 at follow-up in the hip replacement group, and declined from 85 to 65 in the controls.

Exercise may boost brain's antidepressant

NEW YORK (Reuters Health) — Exercise seems to increase the production of naturally occurring brain chemical with antidepressant effects in mice, researchers reported Sunday.

The findings, published in the journal Nature Medicine, point to potential new ways to treat depression in people.

Studies have found that exercise can help ease depression symptoms, but the reasons for the benefit have not been clear. For the new study, scientists used a tool called a microarray to examine how exercise changed gene activity in the brains of mice.

They focused on a brain region known as the hippocampus, which has been implicated in mood regulation and in the brain's response to antidepressant medication. The researchers found that mice that had a week's worth of workouts on a running wheel showed altered activity in a total of 33 genes, the majority of which had never been identified before.

In particular, exercise enhanced activity in the gene for a nerve growth factor known as VGF. Nerve growth factors are small proteins important in the development and maintenance of nerve cells.

Moreover, when the researchers infused a synthetic version of VGF into the brains of the mice, it produced a "robust antidepressant effect" in standardised tests of animals placed in stressful situations.

"The major finding is that we have identified a key factor that underlies the antidepressant effects of exercise — information that could be used for the development of novel therapeutic agents," said senior researcher Dr. Ronald S. Duman of Yale University in New Haven, Connecticut.

Exercise "clearly has effects on the brain," he told Reuters Health, and they are both direct and indirect. It's possible, he explained, that the current findings reflect a direct effect of exercise on nerve cells in the hippocampus, or more general changes in the brain, like better blood flow or increased hormonal activity.

Corn syrup may not boost food intake

NEW YORK (Reuters Health) — Though some have blamed the US obesity problem on the corn syrup ubiquitous in processed foods, a new study casts some doubt on this idea.

Researchers found that high-fructose corn syrup did not differ from regular table sugar in its effects on people's appetite and food intake later in the day. They say the findings counter the argument that high-fructose corn syrup is contributing to the rise of obesity and Type 2 diabetes.

Over the past 35 years, food manufacturers have been steadily replacing sucrose (sugar) with high-fructose corn syrup as their sweetener of choice.

Some experts have argued that high-fructose corn syrup encourages overeating because of its short-term effects in the body. Glucose triggers an increase in the hormone insulin, which helps the body know that it's full; fructose, however, has a weaker effect on insulin.

Studies also suggest that fructose has a weaker effect on "appetite hormones" that help control food intake.

To further study the question, Tina Akhavan and G. Harvey Anderson from the University of Toronto in Canada conducted two tests with 31 young healthy men.

In each, the men were given various sugar solutions to drink — containing either table sugar, high-fructose corn syrup or other combinations of glucose and fructose. All of the solutions had the same number of calories.

An hour-and-a-half later, the men were allowed to eat all the pizza they wanted.

In general, the researchers found, there was no difference in the men's reported hunger levels or food intake whether they had high-fructose corn syrup or table sugar earlier in the day.

In addition, although sugar solutions with a higher ratio of glucose to fructose raised insulin levels to a greater degree, all of the solutions suppressed the appetite-stimulating hormone ghrelin to a similar extent.

3-D mammography cuts false-positives

CHICAGO (Reuters Health) — Stereoscopic digital mammography, which gives a 3-dimensional view of the inner structures of the breast, cuts the number of falsely diagnosed tumours in half, compared with conventional mammography, researchers reported here this week.

Preliminary results with stereoscopic digital mammography were described at the meeting of the Radiological Society of North America by one of its developers, Dr. David J. Getty of BBN Technologies of Cambridge, Massachusetts.

The technique involves capturing two images six to ten degrees apart that are cross-polarized and then superimposed, in much the same way as two images are used to create 3-D movies.

"Two-dimensional imaging masks subtle lesions," Getty explained. "With 3-D mammography, this is greatly reduced. Lesions can be seen as lying at different depths."

In the study, 1,093 women referred for evaluation of suspected breast cancer were each examined with conventional mammography and the stereoscopic digital technique.