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Wednesday, June 20, 2012

Researchers develop new drug that blocks traumatic memories

Understanding memory is still one of the greatest challenges in science. In recent years, no one doubted the role that neurons played in the formation of cerebral networks. A few years ago however, the scientific world turned to the study of astrocytes with more attention.

A collaborative research project led by experts from the Universidad Andrés Bello in Chile, Ghent University and Catholic University of Leuven in Belgium, recently proved that astrocyte cells play a crucial role in the formation of memories.

The finding gives doctors a new target for medication to combat neurological diseases, such as Alzheimer’s disease or post-traumatic stress disorder. Their work was recently published in FASEB Journal.

Astrocyte cells account for 85 percent of cells in the brain and until recently, they were considered to be the "assistants" to neurons, since they were in charge of collecting the waste produced by the sinapsis used to speed up the neuron's reuse.

But scientists have now discovered that these "assistants" play a more important role than was previously thought.

Despite the fact that astrocytes are abundant, studying them was always complicated by the lack of tools used to isolate their function in the neurological connections as well the fragile nature of the cells themselves.

Jimmy Stehberg, leader of the Neurobiological Lab in the Universidad Andrés Bello explains that in conjunction with other investigators, they were able to create a compound that blocks a specific astrocyte connecting channel, one that the experts assumed was involved in the process of the formation of memory.

In order to prove their theory they injected the compound into the brain of a group of mice which were previously subjected to a traumatic experience

The mice that had the compound injected into them did not show any physical or cerebral reactions, while the ones who hadn't received the injection showed signs of stress.

With this, scientists demonstrated that blocking this channel in the astrocyte also blocks the process of the consolidation of memory. This proves that memory does not only depend upon neurons, but that it also needs the astrocytes, to be able to consolidate short-term memories.

The discovery could position the astrocyte as a focal point of investigation for neurological and psychiatric science. In their paper, the authors said that astroctytes are “a novel pharmacological target for the treatment of psychiatric disorders, particularly for memory-related disorders like post-traumatic stress disorder”.

More information: Release of gliotransmitters through astroglial connexin 43 hemichannels is necessary for fear memory consolidation in the basolateral amygdala, http://www.fasebj. … 416.abstract

Provided by Andres Bello University

"Researchers develop new drug that blocks traumatic memories." June 19th, 2012. http://medicalxpress.com/news/2012-06-drug-blocks-traumatic-memories.html

Comment:You take it for 'nam flashbacks and find that you forget your wedding day?

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Robert Karl Stonjek

New implant method to help diabetics

THE GARVAN INSTITUTE OF MEDICAL RESEARCH

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The 'islet' transplants are only given to patients who are suffering greatly from Type 1 diabetes, but many islet cells die within 2-5 years. The research suggests a better way to ensure the transplant is more effective.

Image: firebrandphotography/iStockphoto

A transplant procedure given only to those with Type 1 diabetes who pass out repeatedly from low blood sugar levels, or ‘hypos’, is likely to become much more effective as a result of a discovery made by a group of Australian researchers.

‘Islet transplants’ (the transplant of islets from the pancreas, which contain insulin-producing cells) are not given lightly because recipients must take immunosuppressive drugs for the rest of their lives. As a result, transplant recipients are generally people who cannot regulate their blood sugar levels, and who lapse into comas, often without warning.

However, many islets die within a week of transplantation, and most patients have to go back on at least some insulin within 2-5 years.

Associate Professor Jenny Gunton, from Sydney’s Garvan Institute of Medical Research and Westmead Hospital, together with the Westmead Islet Transplant Program, has discovered that treating islets prior to transplantation with a drug that boosts production of the HIF-1 alpha protein (a master regulator of cell survival) significantly improves the survival of human islets in mouse recipients. Her findings are published in Cell Transplantation.

“I work with the islet transplant team at Westmead Hospital, and we’ve been trying to figure out a way of improving outcomes for people who receive islet transplants,” she said.

“Isolating islets from a donor pancreas exposes them to lack of oxygen, and islets suffer a lot of damage even from temporary low amounts of oxygen. HIF-1 alpha helps cells respond to low oxygen levels, and so we predicted that boosting it would improve islet survival.”

“When we tested the effect of treating islets prior to transplantation with the drug deferoxamine, DFO for short, which boosts HIF-1 alpha, the results supported our prediction.

“Because we had to test the effect before using it in people, we transplanted human islets into mice – with some islets having been treated with DFO, and some not treated. In a ‘minimal mass’ model, which approximates the human situation, we went from a 0% cure rate at a month to a 50% cure rate in a month.”

“In an ‘adequate mass’ model, where you give the mice many more islets, mice were cured by non-DFO-treated islets. However, it took over 3 times the number of non-DFO-treated islets to cure the mice.”

“We also conducted an experiment which demonstrated the importance of HIF-1 alpha – by engineering mice not to produce any HIF-1 alpha in their insulin-producing cells. When these non-HIFF-1 alpha islets were transplanted into diabetic mice, the recipients did very badly.”

“The good thing about deferoxamine is that it is already approved for human use, has been in use for well over a decade, and in our studies, we used it the normal human treatment dose.”

“At Westmead, we’ve already started using DFO to treat islets before transplantation. While it’s still too early to draw any conclusions, recipients are doing well. To actually test the effect in people properly, you’d need to do a big randomised, placebo-controlled trial, and to get the number of people needed you’d have to enrol patients from many centres world-wide – clearly not an easy option.”

“We hope that finding a way of improving islet survival in recipients will extend the usefulness of donor pancreases – meaning you could give more transplants because one pancreas might be enough for one recipient, instead of two to three pancreases for each recipient.”

“At the moment islet transplants are good for those people that have regular severe hypos. Even if the transplanted islets don’t get the person ‘off’ insulin, they stop experiencing hypos. This increases quality of life immeasurably because prior to transplantation repeat hypo sufferers are not allowed to drive and generally can’t hold down a job.”

“We hope our finding will give these people a longer window without insulin use.”

Editor's Note: Original news release can be found here.

Sai Mantra Chanting: 1 Hour

Tuesday, June 19, 2012

Evolutionary benefits of sex explained

THE UNIVERSITY OF AUCKLAND

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The experiments found that when organisms adapted to different environments reproduced sexually, the species more rapidly adapted to both environments. The findings contradicted an evolutionary biology theory but mirrored what occurs in the real world.

Image: usas/iStockphoto

University of Auckland scientists have provided the first experimental explanation of how sexual reproduction helps species adapt in challenging real-world environments, solving a classic conundrum in evolutionary biology.

“According to classic evolutionary theory, sexual reproduction should actually retard species’ ability to adapt to complex environments and in the long run prevent the evolution of new species,” explains lead researcher Dr Mat Goddard.

“But in the real world, sex is a highly successful strategy that doesn’t prevent new species from evolving, so what we see in nature doesn’t tally with the theory. Our experimental work provides the first explanation for this and supports an alternate evolutionary theory.”

As organisms adapt to environmental challenges they accumulate genetic changes that help them survive. Since sexual reproduction produces offspring with a mix of genes from both parents, in theory, sex between organisms adapting to different environments should be detrimental. It would produce offspring poorly adapted to either environment because helpful genes are diluted and, according to classic theory, genes that are beneficial in one situation are detrimental in another.

To test the theory the researchers developed special yeast that could be switched from asexual to sexual forms. Two groups of yeast grown in different environments were allowed to sexually reproduce, to see whether this slowed the species’ simultaneous adaptation to both environments as predicted by the theory.

In fact, sexual reproduction proved advantageous, allowing more rapid adaptation to both environments even when there was interbreeding between the two groups. The results were consistent with a little-known alternate theory, which states that genes that confer a benefit in one environment are not necessarily detrimental in another and would therefore not disadvantage the offspring of mixed parents.

“If the classic theory were true, then any breeding between groups of organisms adapting to different environments would dramatically slow their evolution. So to explain how new species evolve, classical theorists have had to come up with all sorts of convoluted scenarios, like the emergence of ‘magic genes’ for mate choice to prevent sexual reproduction between populations,” says Dr Goddard.

“Our work is much more consistent with what we see in the real world. It supports an alternate theory, in which organisms adapting to different environmental niches can live alongside one another and interbreed occasionally but this doesn’t compromise their evolution or the eventual development of new species, in fact sex enhances this process.”

The research was funded by a Marsden grant and a University of Auckland PhD scholarship to Jeremy Gray, and has been published online in the journal Ecology Letters.

Editor's Note: Original news release can be found here.