Sleep helps brain stay fit by clearing waste
Washington:
Like a janitor sweeping the halls after the lights go out, major changes occur
in the brain during sleep to flush out waste and ward off disease, researchers
said Thursday.
The
research in the journal Science offers new answers to explain why people spend
a third of their lives asleep and may help in treating dementia and other
neurological disorders.
In
lab experiments on mice, researchers observed how cellular waste was flushed
out via the brain's blood vessels into the body's circulatory system and
eventually the liver.
These
waste products included amyloid beta, a protein that when accumulated is a
driver of Alzheimer's disease.
In
order to help remove the waste, cerebral spinal fluid is pumped through brain
tissue.
The
process is sped along during sleep because the brain's cells shrink by about 60
percent, allowing the fluid to move faster and more freely through the brain.
The
whole operation takes place in what researchers call the glymphatic system,
which appears to be nearly 10 times more active during sleep than while awake.
"The
brain only has limited energy at its disposal," said lead author Maiken
Nedergaard of the University of Rochester Medical Center.
"You
can think of it like having a house party. You can either entertain the guests
or clean up the house, but you can't really do both at the same time."
Co-authors
of the study, which was funded by the US National Institutes of Health, came
from Oregon Health and Science University and New York University.
18.10.2013
New blood test can diagnose lung, prostate cancer
Washington:
Scientists have developed a simple new blood test that can detect early-stage
lung and prostate cancers as well as their recurrence.
Serum-free
fatty acids and their metabolites in the blood can be used as screening
biomarkers to help diagnose early stages of cancer and identify the probability
of recovery and recurrence after tumour removal, researchers found.
"While
cancer is the second-leading cause of death worldwide, diagnosis at the early
stages of cancer remains challenging," said Jinbo Liu, researcher at
Cleveland Clinic, and lead study author.
"In
this study, we identified compounds that appear to be new screening biomarkers
in cancer diagnosis and prognosis," Liu added.
The
study looked at blood samples from 55 patients with lung cancer and 40 patients
with prostate cancer and compared them to blood samples of people without
cancer.
In
a second phase of the study, blood was examined preoperatively from 24 patients
scheduled for curative lung cancer surgery and again at six and 24 hours after
the surgery.
The
cancer patients had one- to six-times greater concentrations of serum-free fatty
acids and their metabolites (the biomarker) in their blood than patients
without cancer.
In
the second phase, the serum-free fatty acid concentrations decreased by three
to 10 times within 24 hours after tumour removal surgery.
While
there is a blood test for prostate cancer, the prostate-specific antigen test,
or PSA, has a high false-positive rate that results in many unnecessary
biopsies and complications, according to Liu.
The
test developed in this study could be a helpful additional blood test for
prostate cancer.
"This
is an exciting first step to having an uncomplicated way to detect early stages
of lung, prostate and perhaps other cancers," said Daniel I Sessler, chair
of the Outcomes Research Department at Cleveland Clinic.
"It
could also be used to measure the success of tumour resection surgery,
immediately after surgery and long-term for recurrence screening," Sessler
added.
The
study was presented at a meeting of the American Society of Anesthesiologists
(ASA) in San Francisco.
18.10.2013
Nobody can go
back and start a new beginning, but anyone can start today and make a new
ending
Maria
Robinson
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