Medical and Health News: Alzheimers

Showing posts with label Alzheimers. Show all posts

Saturday, March 26, 2011

New Brain Drug Delivery System Will Help Alzheimer's Patients

Editor's Choice
Main Category: Alzheimer's / Dementia
Also Included In: Neurology / Neuroscience
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One of the medical challenges with diseases of the brain is getting any treatment to cross the blood-brain barrier, however tests on the brains of mice with Alzheimer's traits, has shown it is possible to use the body's own natural delivery system to get manufactured treatments absorbed by the brain.

Dr. Matthew Wood stated in the research:

"These are dramatic and exciting results. This is the first time this natural system has been exploited for drug delivery. We are working on sending exosomes to muscle, but you can envisage targeting any tissue. It can also be made specific by changing the drug used."

Currently, less than 5% of drugs (made up of very small molecules) are able to cross the barrier; one example is temozolomide, which is the only chemotherapy available for treating brain tumours such as glioblastoma multiforme and progressive anaplastic astrocytoma. These tumours have a poor prognosis and continue to grow, even after treatment with temozolomide. Therefore, new therapies for these hard-to-treat brain tumours are needed urgently alongside brain malfunctions such as Alzheimer's, Parkinson's and more.

This natural barrier exists to protect the brain, preventing bacteria from crossing over from the blood, while letting oxygen through. However, this has also produced problems for medicine, as drugs can also be blocked. Researchers used the body's own transporters, exosomes, to deliver drugs and proved to be quite successful.

The team at Oxford harvested exosomes from mouse dentritic cells, part of the immune system, which naturally produce large numbers of exosomes. They then fused the exosomes with targeting proteins from the rabies virus, which binds to acetylcholine receptors in brain cells, so the exosome would target the brain.

They filled the exosomes with a piece of genetic code, siRNA, and injected them back into the mice. The siRNA was delivered to the brain cells and turned off a gene, BACE1, which is involved in Alzheimer's disease.

The authors reported a 60% reduction in the gene's activity.

This could be a groundbreaking advancement in the treatment of debilitating Alzheimer's disease and thought leaders on the subject are excited by these new studies. Dr. Susanne Sorensen, head of research at the Alzheimer's Society, said:

"In this exciting study, researchers may have overcome a major barrier to the delivery of potential new drugs for many neurological diseases including Alzheimer's. The blood-brain barrier had been an enormous issue as many potential drugs have not been properly tested because you couldn't get enough of them into the brain. If this delivery method proves safe in humans, then we may see more effective drugs being made available for people with Alzheimer's in the future."

Dr Simon Ridley, head of research at Alzheimer's Research UK, adds: "This is innovative research, but at such an early stage it's still a long way from becoming a treatment for patients. Designing drugs that cross the blood brain barrier is a key goal of research that holds the promise of improving the effectiveness of Alzheimer's treatments in the future."

Source: Nature Biotechnology

Written by Sy Kraft, B.A.
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today

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Friday, March 25, 2011

New Method Developed For Delivering Drugs To The Brain - Alzheimer's Society Comment

Main Category: Alzheimer's / Dementia
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Scientists have developed a new way of administering drugs to the brain to treat Alzheimer's disease, according to a study published last Sunday in 'Nature Biotechnology'.

Researchers at Oxford University injected exosomes - tiny particles naturally released by cells - into the blood of mice. They found that for the first time, using this 'natural' system they were able to transfer potential new drugs across the normally impermeable blood-brain barrier and into the brain.

This new technology was also found to reduce the production of the enzyme BACE1, which helps produce the plaques in the brain in Alzheimer's disease.

Alzheimer's Society comment:

'In this exciting study, researchers may have overcome a major barrier to the delivery of potential new drugs for many neurological diseases including Alzheimer's. The blood-brain barrier protects the brain from harmful chemicals, but also makes it difficult for drugs to reach the target cells. If this delivery method proves safe in humans, then we may see more effective drugs being made available for people with Alzheimer's in the future.'

'More research is now needed to see if this method would be effective for people with Alzheimer's. Dementia research is desperately underfunded. To make the breakthroughs we need, we must invest now.'

Dr Susanne Sorensen
Head of Research
Alzheimer's Society

Research reference: Alvarez-Erviti, Seow, Yin et al, 'Delivery of siRNA to the mouse brain by systemic injection of targeted exosomes', Nature Biotechnology, 20 March 2011.

Source:
Alzheimer's Society

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Monday, March 21, 2011

Neuroscience Discovery May Have A Bearing On Alzheimer's Disease, Autism And Mental Retardation

Main Category: Alzheimer's / Dementia
Also Included In: Autism; Neurology / Neuroscience
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You may remember the color of your loved one's eyes for years. But how?

Scientists believe that long-term potentiation (LTP) - the long-lasting increase of signals across a connection between brain cells - underlies our ability to remember over time and to learn, but how that happens is a central question in neuroscience.

Researchers at Duke University Medical Center have found a cascade of signaling molecules that allows a usually very brief signal to last for tens of minutes, providing the brain framework for stronger connections (synapses) that can summon a memory for a period of months or even years.

Their findings about how the synapses change the strength of connections could have a bearing on Alzheimer's disease, autism and mental retardation, said Ryohei Yasuda, Ph.D., assistant professor of neurobiology and senior author.

"We found that a biochemical process that lasts a long time is what causes memory storage," said Yasuda, who is a Howard Hughes Medical Institute Early Career Scientist.

This work was published in the March 20 issue of Nature.

The researchers were investigating the signaling molecules that regulate the actin cytoskeleton, which serves as the structural framework of synapses.

"The signaling molecules could help to rearrange the framework, and give more volume and strength to the synapses," Yasuda said. "We reasoned that a long-lasting memory could possibly come from changes in the building block assemblies."

The Duke researchers knew that long-term potentiation, a long-lasting set of electrical impulses in nerve cells, is triggered by a transient increase of calcium (Ca2+) ions in a synapse. They devised experiments to learn exactly how the short Ca2+ signal, which lasts only for ~0.1s, is translated into long-lasting (more than an hour) change in synaptic transmission.

The team used a 2-photon microscopy technique to visualize molecular signaling within single synapses undergoing LTP, a method developed in the Yasuda lab. This microscopy method allowed the team to monitor molecular activity in single synapses while measuring the synapses for increase in their volume and strength of the connections.

They found that signaling molecules Rho and Cdc42, regulators of the actin cytoskeleton, are activated by CaMKII, and relay a CaMKII signal into signals lasting many minutes. These long-lasting signals are important for maintaining long-lasting plasticity of synapses, the ability of the brain to change during learning or memorization.

Many mental diseases such as mental retardation and Alzheimer's disease are associated with abnormal Rho and Cdc42 signals, Yasuda said. "Thus, our finding will provide many insights into these diseases."

Notes:

Other authors include lead author Hideji Murakoshi and Hong Wang of the Duke Department of Neurobiology.

This study was funded by Howard Hughes Medical Institute, National Institute of Mental Health, National Institute of Neurological Disorders and Stroke, National Institute of Drug Abuse, the Alzheimer's Association and the Japan Society for the Promotion of Science.

Source:
Mary Jane Gore
Duke University Medical Center

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