Production of key Alzheimer's protein monitored for first time in humans .
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Researchers from Washington University have developed the first safe and sensitive way to monitor the production and clearance rates of amyloid beta peptide (Abeta) in the human central nervous system, opening a valuable window into the genesis of Alzheimer's disease.
The scientists report on Sunday on the online issue of journal Nature Medicine that via an intravenous drip, they give test subjects a form of the amino acid leucine that has been very slightly altered to label it. And they can monitor the production and clearance rate of Abeta through the labeled leucine.
High levels of Abeta in the brain are a hallmark of Alzheimer's disease and believed to be a pivotal cause of the condition. Tests that measure Abeta levels in the cerebrospinal fluid have been available for some time. However, those fixed assessments of Abeta gave no indication of whether the flood of Abeta in patient's brains came from an increase in the mechanisms that make the protein or a reduction in the processes that regularly clear it from the brain.
Because Alzheimer's symptoms take many years to develop, some researchers had assumed that the creation and clearance rates for Abeta were very slow. But the initial test of the new technique, applied to six healthy volunteers, suggests the opposite.
"Abeta has the second-fastest production rate of any protein whose production rate has been measured so far," says lead author Randall Bateman, assistant professor of neurology.
Ideally, the production and clearance rates stay balanced, causing the overall amount of Abeta in the central nervous system to remain constant. Researchers are now applying the technique to individuals with Alzheimer's disease.
Researchers are developing Alzheimer's drugs that either decrease Abeta production or increase its clearance, Bateman notes, and the new test could be very important in determining which approach is most effective.
The test also may be useful in diagnosis of Alzheimer's prior to the onset of clinical symptoms, which occurs after Alzheimer's has inflicted widespread and largely irreversible damage to the brain.
The scientists report on Sunday on the online issue of journal Nature Medicine that via an intravenous drip, they give test subjects a form of the amino acid leucine that has been very slightly altered to label it. And they can monitor the production and clearance rate of Abeta through the labeled leucine.
High levels of Abeta in the brain are a hallmark of Alzheimer's disease and believed to be a pivotal cause of the condition. Tests that measure Abeta levels in the cerebrospinal fluid have been available for some time. However, those fixed assessments of Abeta gave no indication of whether the flood of Abeta in patient's brains came from an increase in the mechanisms that make the protein or a reduction in the processes that regularly clear it from the brain.
Because Alzheimer's symptoms take many years to develop, some researchers had assumed that the creation and clearance rates for Abeta were very slow. But the initial test of the new technique, applied to six healthy volunteers, suggests the opposite.
"Abeta has the second-fastest production rate of any protein whose production rate has been measured so far," says lead author Randall Bateman, assistant professor of neurology.
Ideally, the production and clearance rates stay balanced, causing the overall amount of Abeta in the central nervous system to remain constant. Researchers are now applying the technique to individuals with Alzheimer's disease.
Researchers are developing Alzheimer's drugs that either decrease Abeta production or increase its clearance, Bateman notes, and the new test could be very important in determining which approach is most effective.
The test also may be useful in diagnosis of Alzheimer's prior to the onset of clinical symptoms, which occurs after Alzheimer's has inflicted widespread and largely irreversible damage to the brain.
Researchers in the University of Toronto's Department of Nutritional Sciences have some reassurance for diabetics and carb-counters. The glycemic index (GI), the table that lists the quality of carbohydrates in more than 750 common foods, works just as predictably whether subjects consume a single portion of one item, or a normal meal. Click link to read more.
http://www.medicalnewstoday.com/medicalnews.php?newsid=45862&nfid=al
posted by Valery Yermalitsky at
6:30 AM
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