Useful Health Tips: August 2012

Saturday, August 4, 2012

DNA Clue Discovered For Why Women Outlive Men

Featured Article
Academic Journal
Main Category: Seniors / Aging
Also Included In: Men's Health; Biology / Biochemistry; Genetics
Article Date: 04 Aug 2012 - 1:00 PDT

A new study of mitochondrial DNA in fruit flies offers a number of clues that might explain why females tend to outlive males across much of the animal kingdom, including humans.

Researchers from Monash University in Australia and Lancaster University in the UK, write about their work in the 2 August online issue of Current Biology.

They found male fruit flies appear to have mutations in their mitochondrial DNA that affect how fast they age and how long they live.

Scientists use fruit flies as models for studies in genes and aging because their biological processes are remarkably similar to that of other animals, such as humans, and with a lifespan of about a month, it doesn't take too long to investigate generational effects.

Senior author Damian Dowling, a research fellow in the Monash School of Biological Sciences, told the press:

"All animals possess mitochondria, and the tendency for females to outlive males is common to many different species. Our results therefore suggest that the mitochondrial mutations we have uncovered will generally cause faster male aging across the animal kingdom."

"Intriguingly, these same mutations have no effects on patterns of aging in females. They only affect males," he added.

Mitochondria are special subunits of cells, about the same size as bacteria, that provide the energy for life. They combine sugar and oxygen into adenosine triphosphate or ATP, molecular packets of energy that are usable by cells.

Mitochondria have their own DNA that is quite separate from the cellular DNA in the nucleus of the cell.

And, unlike cellular DNA, which is inherited from the sperm and egg that fuse to make the new individual, mitochondrial DNA comes only from the egg.

Thus, as mitochondrial DNA is passed down from generation to generation, the process of natural selection has no opportunity to "screen out" mutations in mitochondrial DNA that might be harmful to males. The researchers refer to this as a "sex-specific selective sieve".

For their study, Dowling and colleagues looked at differences in longevity and biological aging in male and female fruit flies whose mitochondria came from different origins.

They found genetic variations in both male and female mitochondrial DNA, but only the male ones could be linked to life expectancy. There weren't just a few mutations in one place, there were several, spread all over the mitochondrial genome:

"... our results indicate that the mitochondrial mutation loads affecting male aging generally comprise numerous mutations over multiple sites," they write.

The researchers suggest the mutations are entirely due to the way mitochondrial DNA is passed down through the female line.

"If a mitochondrial mutation occurs that harms fathers, but has no effect on mothers, this mutation will slip through the gaze of natural selection, unnoticed. Over thousands of generations, many such mutations have accumulated that harm only males, while leaving females unscathed," Dowling explained.

In an earlier study that looked at the effect of mitochondria being passed down the female line, the team had also discovered a link with male infertility.

Dowling said combining this latest study with their earlier work suggests mitochondria are "hotspots" for mutations that influece male health.

"What we seek to do now is investigate the genetic mechanisms that males might arm themselves with to nullify the effects of these harmful mutations and remain healthy," said Dowling.

Written by Catharine Paddock PhD
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today

Additional
References
Citations

Please use one of the following formats to cite this article in your essay, paper or report:

MLA

APA

Please note: If no author information is provided, the source is cited instead.

Visitor Opinions (latest shown first)

Epic Fail!

posted by Kitfox on 3 Aug 2012 at 6:56 am

Is this research screening all flies or just the married ones? The data could be flawed. What we need to look into is the nagging genes of the females of the species and turn it off. Once that has been achieved the males will no longer mutate their genes ON PURPOSE in order to shorten the suffering period. :)

| post followup | alert a moderator |

Add Your Opinion On This Article

'DNA Clue Discovered For Why Women Outlive Men'

Please note that we publish your name, but we do not publish your email address. It is only used to let you know when your message is published. We do not use it for any other purpose. Please see our privacy policy for more information.

If you write about specific medications or operations, please do not name health care professionals by name.

All opinions are moderated before being included (to stop spam)

Contact Our News Editors

For any corrections of factual information, or to contact the editors please use our feedback form.

Please send any medical news or health news press releases to:

Note: Any medical information published on this website is not intended as a substitute for informed medical advice and you should not take any action before consulting with a health care professional. For more information, please read our terms and conditions.

Allergy Sufferers Have Lower Risk Of Brain Tumors

Editor's Choice
Main Category: Neurology / Neuroscience
Also Included In: Allergy
Article Date: 04 Aug 2012 - 1:00 PDT

A new study has added to the growing body of evidence implying that there's a link between allergies and reduced risk of a serious type of cancer that starts in the brain.

According to this particular study, published in the Journal of the National Cancer Institute, the reduced risk seems to be stronger among women than men, however men have a lower tumor risk with certain allergies.

Scientists have believed having allergies or similar factors reduces the risk for this cancer, and this study has strengthened that theory. Experts have never known whether allergies lower the risk of cancer or if, before diagnosis, these tumors (glioma) interfere with the hypersensitive immune response to allergens, because they have the potential to suppress the immune system in order to grow.

Stored blood samples that were taken from patients decades before they were diagnosed with glioma were analyzed by the researchers. The researchers found that there was a 50% reduced risk of developing glioma 20 years later for men and women who had blood samples containing allergy-related antibodies, compared to people without signs of allergies.

Judith Schwartzbaum, associate professor of epidemiology at Ohio State University, investigator in the University's Comprehensive Cancer Center, and leading author of the study, said:

"This is our most important finding. The longer before glioma diagnosis that the effect of allergies is present, the less likely it is that the tumor is suppressing allergies. Seeing this association so long before tumor diagnosis suggests that antibodies or some aspect of allergy is reducing tumor risk.
It could be that in allergic people, higher levels of circulating antibodies may stimulate the immune system, and that could lower the risk of glioma. Absence of allergy is the strongest risk factor identified so far for this brain tumor, and there is still more to understand about how this association works."

Studies, until now, have not been able to analyze blood samples collected longer than 20 years before tumor diagnosis. Previous studies examining the relationship between allergies and brain tumor risk have used self-report questionnaires on patients' histories with glioma.

The study also showed that women had at least a 50% lower risk for the most severe and common type of these tumors, known as glioblastoma, if their blood samples tested positive for specific allergy antibodies. These results were not seen in men. On the other hand, men had a 20% reduced risk of this tumor if they tested positive for both specific antibodies and antibodies of unknown function than men who tested negative.

In the United States, glioblastomas constitute about 60% of adult tumors that start in the brain, which affects 3 in 100,000 people. Patients may seek treatments such as radiation, surgery, and chemotherapy. On average, these patients survive for about one year, with fewer than 25% surviving up to 2 years and just 10% surviving up to 5 years.

The Janus Serum Bank in Norway granted the research team access to specimens. This bank contains samples collected over the last 40 years from people during their annual medical checkups or from volunteer blood donors. Since 1953, Norway has registered all recent cancer cases in the country, and personal identification numbers allows cross-referencing those cases with blood samples that have been previously collected.

The experts were able to analyze stored samples from 594 citizens who were diagnosed with glioma, including 374 that were diagnosed with glioblastoma, between 1974 and 2007. These samples were matched for age, sex, and date of blood collection with 1,777 samples from people who did not have glioma in order to compare.

The team was looking for levels of two types of proteins, IgE, or immunoglobulin E, while they were measuring the blood samples. This is a class of antibodies that are made from white blood cells that mediate immune responses to allergens. Two classes of IgE take part in the allergic response:

allergen-specific IgE- identifies specific components of an allergen
total IgE- identifies these components but also includes antibodies with unknown functions

The researchers observed each sample and determined whether the serum had elevated levels of IgE specific to the most common allergens in Norway as well as IgE. Specific Respiratory allergens were:

tree pollen and plants
dog and horse dander
dust mites
mold

A statistical analysis was then conducted in order to approximate the association between the risk of developing glioma and elevated concentrations of allergen-specific IgE and total IgE.

A 54% reduced risk of glioblastoma was associated with the women who tested positive for elevated levels of allergen-specific IgE compared to the women who tested negative. This association was not seen in men.

The relation between total IgE levels and risk of glioma was the same for both sexes. For men and women combined, a 25% reduced risk of glioma was associated with testing positive for elevated total IgE.

The analysis for effects on glioblastoma risk alone showed a similar decreased risk for both men and women combined whose blood samples tested positive for elevated levels of IgE. However, this finding was considered borderline in terms of statistical significance because it was not a significant enough number, meaning there is still the possibility that the association could be caused by chance.

"There is definitely a difference in the effect of allergen-specific IgE between men and women. And even results for total IgE suggest there still may be a difference between the sexes. The reason for this difference is unknown," explained Schwartzbaum.

This research has shown evidence for the likelihood that the immune system of people with respiratory allergies could help fight against this type of cancer. The author explained that being able to examine this association over 4 decades between blood sampling and tumor diagnosis gave him and his team better insight.

For example, a 46% reduced risk for developing glioma 20 years later was associated with a positive test for elevated concentrations of total IgE compared to samples that tested negative. That reduced risk was only about 25% in samples that tested positive for high levels of total IgE taken between 2 and 15 years before diagnosis.

Schwartzbaum explained:

"There may be a trend- the closer the samples get to the time of diagnosis, the less help the IgE is in decreasing the risk of glioma. However, if the tumor were suppressing allergy, we would expect to see a bigger difference in risk near the time of diagnosis."

He hopes to further his research and analyze the serum samples for concentration of cytokines (chemical passengers that promote or suppress inflammation as part of the immune response) in order to see if these proteins play a part in the relationship between elevated IgE levels and reduced tumor risk.

Written by Sarah Glynn
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today

Additional
References
Citations

Please use one of the following formats to cite this article in your essay, paper or report:

MLA

APA

Please note: If no author information is provided, the source is cited instead.

Add Your Opinion On This Article

'Allergy Sufferers Have Lower Risk Of Brain Tumors'

If you write about specific medications or operations, please do not name health care professionals by name.

All opinions are moderated before being included (to stop spam)

Contact Our News Editors

For any corrections of factual information, or to contact the editors please use our feedback form.

Please send any medical news or health news press releases to:

Researchers Develop First Potential Medicine For Patients With Most Severe Form Of Congenital Hyperinsulinism

Main Category: Diabetes
Also Included In: Pediatrics / Children's Health; Genetics
Article Date: 04 Aug 2012 - 0:00 PDT

A pilot study in adolescents and adults has found that an investigational drug shows promise as the first potential medical treatment for children with the severest type of congenital hyperinsulinism, a rare but potentially devastating disease in which gene mutations cause insulin levels to become dangerously high.

"There is currently no effective medicine for children with the most common and most severe form of hyperinsulinism," said study leader Diva D. De Leon, M.D., a pediatric endocrinologist at The Children's Hospital of Philadelphia. "Our new research shows that this investigational drug, a peptide called exendin-(9-39), controls blood sugar levels in people, a very promising result."

The study appears online ahead of print in the journal Diabetes.

In congenital hyperinsulinism (HI), mutations disrupt the insulin-secreting beta cells in the pancreas. Uncontrolled, excessive insulin levels thus sharply reduce blood glucose levels, a condition called hypoglycemia. If untreated, hypoglycemia may cause irreversible brain damage or death in children. Congenital HI occurs in an estimated one in 50,000 U.S. children, with a higher incidence among Ashkenazic Jews and certain other groups.

The standard treatment for some forms of congenital HI is diazoxide, a drug that controls insulin secretion by opening potassium channels in beta cells. However, this drug does not work in the most common types of HI, in which mutations prevent these potassium channels from forming.

When abnormal beta cells occur only in a discrete portion of the pancreas, precise surgery on the tiny organ can remove the lesion and cure HI. The Congenital Hyperinsulinism Center at The Children's Hospital of Philadelphia is a world leader in diagnosing such lesions and performing the curative surgery on newborns.

However, in roughly half of congenital HI cases, abnormal cells are diffused through the pancreas, and surgeons must remove nearly the entire pancreas. This leaves the majority of patients at high risk of developing diabetes.

The current study, which builds on previous research by De Leon and colleagues in animals, uses exendin-(9-39), which blocks the action of a hormone receptor, glucagon-like peptide-1 (GLP-1), in beta cells. The GLP-1 receptor is currently the target of drugs that treat diabetes, using the opposite effect from that investigated in this HI study.

The current pilot study included nine subjects, aged 15 to 47 years old, who had hyperinsulinism caused by mutations in potassium channels. None were being treated for HI at the time of the study, but all were at risk of hypoglycemia during periods of fasting.

In all nine subjects, the drug controlled blood glucose levels during fasting. Exendin also controlled insulin secretion in cell studies of beta cells taken from newborns with HI. The current research did not focus on the biological mechanisms that occurred, but De Leon said the results are encouraging enough to progress to a clinical study in children with HI over the next year.

Additional
References
Citations

Financial support for this study came from the National Institutes of Health (grant 1R03DK07835), the Lester and Liesel Baker Foundation, and the Clifford and Katherine Goldsmith Foundation. De Leon's co-authors, all from Children's Hospital, were Charles A. Stanley, M.D., Andrew C. Calabria, M.D., Changhong Li, M.D., and Paul R. Gallagher In addition to their positions at Children's Hospital, De Leon, Stanley and Li also are in the Perelman School of Medicine at the University of Pennsylvania.
"The GLP-1 Receptor Antagonist Exendin-(9-39) Elevates Blood Fasting Glucose Levels in Congenital Hyperinsulinism due to Inactivating Mutations in the ATP-sensitive Potassium Channel," Diabetes, published online Aug.1, 2012, to appear in print, October 2012. doi: 10.2337/db12-0166.
Children's Hospital of Philadelphia Please use one of the following formats to cite this article in your essay, paper or report:

MLA

APA

Please note: If no author information is provided, the source is cited instead.

Add Your Opinion On This Article

'Researchers Develop First Potential Medicine For Patients With Most Severe Form Of Congenital Hyperinsulinism'

If you write about specific medications or operations, please do not name health care professionals by name.

All opinions are moderated before being included (to stop spam)

Contact Our News Editors

For any corrections of factual information, or to contact the editors please use our feedback form.

Please send any medical news or health news press releases to: