News 11 march 2009
Turning Sunlight into Liquid Fuels
For millions of years, green plants have
employed photosynthesis to capture energy from sunlight and convert it into
electrochemical energy. A goal of scientists has been to develop an artificial version of
photosynthesis that can be used to produce liquid fuels from carbon dioxide and water.
Researchers with the U.S. Department of Energy’s Lawrence Berkeley National
Laboratory (Berkeley Lab) have now taken a critical step towards this goal with the
discovery that nano-sized crystals of cobalt oxide can effectively carry out the critical
photosynthetic reaction of splitting water molecules. In this video, an aqueous solution
contains silica particles that have been embedded with photooxidizing cobalt oxide
nanocrystals plus a sensitizer to allow the water-splitting reaction to be driven by
visible light. When laser light hits the solution it turns from gold to blue as the
sensitizer absorbs light. Bubbles soon begin to form as oxygen gas is released from the
spilt water molecules. “Photooxidation of water molecules into oxygen, electrons and
protons (hydrogen ions) is one of the two essential half reactions of an artifical
photosynthesis system - it provides the electrons needed to reduce carbon dioxide to a
fuel,” said Heinz Frei, a chemist with Berkeley Lab’s Physical Biosciences
Division, who conducted this research with his postdoctoral fellow Feng Jiao.
“Effective photooxidation requires a catalyst that is both efficient in its use of
solar photons and fast enough to keep up with solar flux in order to avoid wasting those
photons. Clusters of cobalt oxide nanocrystals are sufficiently efficient and fast, and
are also robust (last a long time) and abundant. They perfectly fit the bill.”
Nanotech coating could lead to
better brain implants to treat diseases
Biomedical and materials engineers at the
University of Michigan have developed a nanotech coating for brain implants that helps the
devices operate longer and could improve treatment for deafness, paralysis, blindness,
epilepsy and Parkinson's disease. Currently, brain implants can treat Parkinson's disease,
depression and epilepsy. These and the next generation of the devices operate in one of
two ways. Either they stimulate neurons with electrical impulses to override the brain's
own signals, or they record what working neurons are transmitting to non-working parts of
the brain and reroute that signal. On-scalp and brain-surface electrodes are giving way to
brain-penetrating microelectrodes that can communicate with individual neurons, offering
hope for more precise control of signals.
UI study suggests salt might be
'nature's antidepressant'
Most people consume far too much salt, and
a University of Iowa researcher has discovered one potential reason we crave it - it might
put us in a better mood. UI psychologist Kim Johnson and colleagues found in their
research that when rats are deficient in sodium chloride, common table salt, they shy away
from activities they normally enjoy, like drinking a sugary substance or pressing a bar
that stimulates a pleasant sensation in their brains. "Things that normally would be
pleasurable for rats didn't elicit the same degree of relish, which leads us to believe
that a salt deficit and the craving associated with it can induce one of the key symptoms
associated with depression," Johnson said. The UI researchers can't say it is
full-blown depression because several criteria factor into such a diagnosis, but a loss of
pleasure in normally pleasing activities is one of the most important features of
psychological depression. And, the idea that salt is a natural mood-elevating substance
could help explain why we're so tempted to over-ingest it, even though it's known to
contribute to high blood pressure, heart disease and other health problems. Past research
has shown that the worldwide average for salt intake per individual is about 10 grams per
day, which is greater than the U.S. Food and Drug Administration recommended intake by
about 4 grams, and may exceed what the body actually needs by more than 8 grams.
An end to fear
A team of Dutch researchers under the
leadership of Vici-winner Merel Kindt has successfully reduced the fear response. They
weakened fear memories in human volunteers by administering the beta-blocker propranolol.
Interestingly, the fear response does not return over the course of time. Top journal
Nature Neuroscience published the findings on 15 February 2009. Until recently, it was
assumed that the fear memory could not be deleted. However, Klindt's team has demonstrated
that changes can indeed be effected in the emotional memory of human beings. Before fear
memories are stored in the long-term memory, there is a temporary labile phase. During
this phase, protein synthesis takes place that ‘records’ the memories. The
traditional idea was that the memory is established after this phase and can, therefore,
no longer be altered. However, this protein synthesis also occurs when memories are
retrieved from the memory and so there is once again a labile phase at that moment. The
researchers managed to successfully intervene in this phase. During their experiments the
researchers showed images of two different spiders to the human volunteers. One of the
spider images was accompanied by a pain stimulus and the other was not. Eventually the
human volunteers exhibited a startle response (fear) upon seeing the first spider without
the pain stimulus being administered. The anxiety for this spider had therefore been
acquired.
New study identifies risk factors
in severity of 'flat head syndrome' in babies
A new study by physician researchers from
Hasbro Children's Hospital and Children's Hospital Boston identifies risk factors for the
severity of asymmetrical head shapes, known as deformational plagiocephaly (DP), or more
commonly as flat head syndrome. The study was published in the March 2009 edition of the
Journal of Craniofacial Surgery. Since the 1992 campaign by the American Academy of
Pediatrics, many parents have been placing babies on their backs to sleep, as it is
believed to reduce the risk of sudden infant death syndrome (SIDS). As a result, there has
been a 40% reduction in the incidence of SIDS. At the same time, there has been a noted
increase in the incidence of DP, affecting as many as one in six infants, which may be
connected with the change to the supine sleeping position in children. DP, however, can
also occur with prone positioning as well. Many researchers have published reports of risk
factors for the development of DP, which include supine positioning, firstborn infants,
prematurity, developmental delay and others. While these variables seem to be associated
to some extent with the development of DP, the influence of each of those variables on the
degree of asymmetry in DP has not been determined to date. With this in mind, physician
researchers from Hasbro Children's Hospital and Children's Hospital Boston developed a
study to determine the relationship between predisposing factors for DP and the severity
of the flattening. The researchers looked at a number of factors in the infants as well as
maternal variables associated with pregnancy. Of particular note in their findings is the
severity of flattening was not associated with infant sleep position.
Study suggests blood test for
Alzheimer’s possible
Researchers have revealed a direct
relationship between two specific antibodies and the severity of Alzheimer’s disease
symptoms, raising hopes that a diagnostic blood test for the devastating disorder is
within reach.Researchers from the University of Georgia, the Charlie Norwood VA Medical
Center in Augusta and the Medical College of Georgia compared antibody levels in blood
samples from 118 older adults with the participant’s level of dementia. The team,
whose results appear in the current edition of Journal of Gerontology: Medical Sciences,
found that the concentration of two specific proteins that are involved in the immune
response increases as the severity of dementia increases."We found a strong and
consistent relationship between two particular antibodies and the level of
impairment,” said study co-author L. Stephen Miller, professor and director of
clinical psychology training in the UGA Franklin College of Arts and Sciences. “The
finding brings us closer to our ultimate goal of developing a blood test that can diagnose
Alzheimer’s disease or potentially identify if someone is at higher risk for the
disease.”
Search reveals molecules that block
Stat 3
Finding molecules that block the activity
of the oncogene Stat3 (signal transducer and activator of transcription) required
screening literally millions of compounds, using computers that compared the structure of
the cancer-causing gene to those of the small molecules, said a Baylor College of Medicine
researcher in a report that appears in the current online issue of the journal PLoS One
(Public Library of Science ONE).
It was worth the effort, said Dr. David J. Tweardy, professor of medicine and molecular
and cellular biology and chief of the division of infectious diseases at BCM, because it
could point the way to better treatment of breast and other cancers, as well as chronic
viral infections, asthma, and inflammatory bowel disease. He is also on the faculty of the
NCI-designated Dan L. Duncan Cancer Center at BCM.
Scripps research team identifies
key molecules that inhibit viral production
The research, led by Professor Donny
Strosberg of Scripps Florida, was published on March 4, 2009, in the Journal of General
Virology's advance, online edition, Papers in Press. In the new study, Strosberg and his
colleagues describe peptides (molecules of two or more amino acids) derived from the core
protein of hepatitis C. The team found that these peptides inhibit not only dimerization
of the core protein (the joining of two identical subunits), but also production of the
actual virus itself. "We went for the simplest solution, taking a peptide from core
to see if we could block the interaction," Strosberg said, "and it did."
Researchers discover a new pathway
that regulates inflammation
Inflammation, the body’s earliest
response to damage or infection, can aid the healing process and trigger an immune
response against invading pathogens. But inflammation gone awry can also undermine health,
as in diseases such as rheumatoid arthritis or asthma. Researchers at the University of
Illinois have identified a novel pathway that controls the activity of a key protein
involved in inflammation. Their findings could have important implications for the
treatment of diseases or conditions linked to chronic inflammation. At the heart of the
cell’s inflammatory response is a protein complex called NF-kappa B. In the new
study,biochemistry professor Lin-Feng Chen and his colleagues deciphered a molecular code
that controls its function. Their results appear in the European Molecular Biology
Organization (EMBO) Journal. The NF-kappa B protein complex consists of two subunits that
can bind to DNA and regulate the expression of particular genes. The complex acts like a
molecular switch that can be turned on when the cell is under attack and then off when the
attack has been cleared. Upon activation, it rapidly moves into the nucleus and sets in
motion an army of proteins that cause inflammation. Often referred to as the master
regulator of the immune system, NF-kappa B belongs to a large family of proteins called
transcription factors that control which genes are turned on or off.
Shining light on diabetes-related
blindness
A group of scientists in California is
trying to develop a cheaper, less invasive way to spot the early stages of retinal damage
from diabetic retinopathy, the leading cause of blindness in American adults, before it
leads to blindness. As described in the special Interactive Science Publishing (ISP) issue
of Optics Express, the Optical Society's (OSA) open-access journal, the scientists are
using beams of light to measure blood flow in the back of the eye. "The more severe
the retinopathy, the lower the blood flow to the retina," says David Huang of the
Keck School of Medicine at the University of Southern California in Los Angeles. This
observation may lead to better ways to diagnose the condition early. Diabetic retinopathy
is caused by damage to blood vessels in the eye's retina. According to the U.S. Centers
for Disease Control and Prevention, 5.5 million people over the age of 40 suffered from
this condition in 2005, and this number is expected to triple by 2050 as the number of
people with diabetes continues to increase. But there's hope; vision loss is preventable
if retinal damage is detected early enough. Affecting everyone who has type 1 diabetes and
most people with type 2, diabetic retinopathy progresses in two stages. It begins when the
small vessels that carry blood to and from the eye swell and leak, which can lead to slow
vision loss as the health of the retina degenerates. In 20 percent of patients, the
disease then progresses to advanced "proliferative" retinopathy. The
oxygen-starved retina calls out to the circulatory system for help, which responds by
forming new, abnormal blood vessels. These fragile vessels have thin walls that tend to
scar and hemorrhage, causing sudden vision loss.
1 in 7 U.S. Teens Is Vitamin D
Deficient
One in seven American adolescents is
vitamin D deficient, according to a new study by researchers in the Department of Public
Health at Weill Cornell Medical College. The findings are published in the March issue of
the journal Pediatrics and were presented at the Pediatric Academic Societies' Annual
Meeting in May 2008. In children, vitamin D deficiency can interfere with bone
mineralization, leading to rickets. In adults, it is linked to cardiovascular disease,
cancer, diabetes, immune dysfunction and hypertension. The study employs a new definition
of vitamin D deficiency recommended by a group of scientists attending the 13th Workshop
Consensus for Vitamin D Nutritional Guidelines in 2007. These experts collectively
proposed that the minimum acceptable serum vitamin D level be raised from 11 nanograms per
milliliter (ng/mL) to at least 20 ng/mL. Using the newer criteria, the study finds more
than half of African-American teens are vitamin D deficient. Girls had more than twice the
risk of deficiency compared with boys. And overweight teens had nearly double the risk of
their normal-weight counterparts.
Obesity linked to dangerous sleep
apnea in truck drivers
Truck crashes are a significant public
health hazard causing thousands of deaths and injuries each year, with driver fatigue and
sleepiness being major causes. A new study has confirmed previous findings that
obesity-driven testing strategies identify commercial truck drivers with a high likelihood
of obstructive sleep apnea (OSA) and suggests that mandating OSA screenings could reduce
the risk of truck crashes. OSA is a syndrome characterized by sleep-disordered breathing,
resulting in excessive daytime sleepiness, sleep attacks, psychomotor deficits, and
disrupted nighttime sleep. It increases the risk of motor vehicle accidents, and is common
among truck drivers. Approximately 2.4 to 3.9 million licensed commercial drivers in the
U.S. are expected to have OSA. In addition to being unrecognized or unreported by drivers,
OSA often remains undiagnosed by many primary care clinicians despite the fact that OSA
increases the risks of hypertension, diabetes mellitus, and heart disease. Philip Parks,
MD, MPH, medical director of Lifespan's employee health and occupational services, is the
study's lead author. He worked with researchers at the Cambridge Health Alliance on the
study published in the March 2009 edition of the Journal of Occupational and Environmental
Medicine. Parks says, "It is well-known that obesity, a leading risk factor for
obstructive sleep apnea, is on the rise in the United States. Truck drivers with sleep
apnea have up to a 7-fold increased risk of being involved in a motor vehicle crash."
Iron induces death in tumor cells
Rapid growth of cancer cells and their
frequent divisions have their price: Cancer cells need considerably more energy than
healthy cells. Their metabolism runs at full speed and requires large amounts of
micronutrients, particularly iron. However, high levels of iron in the cell lead to the
production of extremely harmful free radicals. To protect itself from these, the cell
inactivates free iron by binding it to what are called iron storage proteins.
Collaborating with physicians of the Dermatology Department of Mannheim University
Hospitals, Dr. Karsten Gülow and Professor Dr. Peter Krammer, head of the Division of
Immunogenetics at DKFZ, investigated Sézary's disease (also called Sézary syndrome), an
extremely aggressive type of cutaneous T cell lymphoma. The majority of currently
available treatments are not really effective against this fatal type of cancer. Using a
molecular-biological trick, Gülow and colleagues succeeded in blocking the production of
one of the iron storage proteins in lymphoma cells. This leads to a rise in the level of
free, non-bound iron in these cells. The iron boosts the production of free oxygen
radicals which cause oxidative stress and, thus, cause damage to the cancer cells and
induce their death. Healthy cells with their low iron level, however, survive the
treatment unharmed.
Research supports toxoplasmosis
link to schizophrenia
Scientists have discovered how the
toxoplasmosis parasite may trigger the development of schizophrenia and other bipolar
disorders. The team from the University of Leeds' Faculty of Biological Sciences (UK) has
shown that the parasite may play a role in the development of these disorders by affecting
the production of dopamine - the chemical that relays messages in the brain controlling
aspects of movement, cognition and behaviour. Toxoplasmosis, which is transmitted via cat
faeces (found on unwashed vegetables) and raw or undercooked infected meat, is relatively
common, with 10-20% of the UK population and 22% of the US population estimated to carry
the parasite as cysts. Most people with the parasite are healthy, but for those who are
immune-suppressed - and particularly for pregnant women - there are significant health
risks that can occasionally be fatal. Dr Glenn McConkey, lead researcher on the project,
says: "Toxoplasmosis changes some of the chemical messages in the brain, and these
changes can have an enormous effect on behaviour. Studies have shown there is a direct
statistical link between incidences of schizophrenia and toxoplasmosis infection and our
study is the first step in discovering why there is this link."
Caltech neuroscientists map
intelligence in the brain
Neuroscientists at the California Institute
of Technology (Caltech) have conducted the most comprehensive brain mapping to date of the
cognitive abilities measured by the Wechsler Adult Intelligence Scale (WAIS), the most
widely used intelligence test in the world. The results offer new insight into how the
various factors that comprise an "intelligence quotient" (IQ) score depend on
particular regions of the brain. Neuroscientist Ralph Adolphs, Bren Professor of
Psychology and Neuroscience and professor of biology at Caltech, Caltech postdoctoral
scholar Jan Gläscher, and their colleagues compiled the maps using detailed magnetic
resonance imaging (MRI) and computerized tomography (CT) brain scans of 241 neurological
patients recruited from the University of Iowa's extensive brain-lesion registry. All of
the patients had some degree of cognitive impairment from events such as strokes, tumor
resection, and traumatic brain injury, as assessed by testing using the WAIS. The WAIS
test is composed of four indices of intelligence, each consisting of several subtests,
which together produce a full-scale IQ score. The four indices are the verbal
comprehension index, which represents the ability to understand and to produce speech and
use language; the perceptual organization index, which involves visual and spatial
processing, such as the ability to perceive complex figures; the working memory index,
which represents the ability to hold information temporarily in mind (similar to
short-term memory); and the processing speed index. The researchers first transferred the
brain scans of all 241 patients to a common reference frame, an approach pioneered by
neuroscientist Hanna Damasio of the University of Southern California, a coauthor of the
study. Using a technique called voxel-based symptom-lesion mapping (a voxel is the
three-dimensional analog of a pixel, and represents a volume of about 1 cubic millimeter),
Adolphs and his colleagues then correlated the location of brain injuries with scores on
each of the four WAIS indices.
Brain damage found in cognitively
normal people with Alzheimer's marker
Researchers at Washington University School
of Medicine in St. Louis have linked a potential indicator of Alzheimer's disease to brain
damage in humans with no signs of mental impairment. Although their cognitive and
neurological assessments were normal, study participants with lower levels of a substance
known as amyloid beta 42 (A-beta 42) in their cerebrospinal fluid (CSF) had reduced whole
brain volumes, suggesting that Alzheimer's changes might already be damaging their brains.
Scientists previously showed that low CSF levels of A-beta 42 mark the presence of amyloid
deposition in the brain, a key diagnostic marker of the amyloid plaques that characterize
Alzheimer's disease. Evidence is mounting that Alzheimer's harms the brain for many years
before physicians and family members can detect symptoms, and this has led many to
conclude that successful Alzheimer's treatments may only be possible if scientists find
ways to identify pre-symptomatic sufferers. The results are an encouraging sign that this
search for new indicators, known as antecedent biomarkers, may be succeeding, according to
senior author David M. Holtzman, M.D., the Andrew and Gretchen Jones Professor and chair
of the Department of Neurology at the School of Medicine and neurologist-in-chief at
Barnes-Jewish Hospital. "We still need to confirm with long-term follow-up studies
that subjects with this biomarker and brain damage go on to develop the cognitive changes
characteristic of Alzheimer's," says Holtzman. "For now, the evidence we've
uncovered further proves that identification and treatment prior to the start of the
symptoms of Alzheimer's disease are likely going to be essential to preventing
irreversible brain injury."
Brain network functions differently
in people with depression, researchers find
Neuroscientists at Washington University
School of Medicine in St. Louis have identified a key difference in the way the brain
functions in people who are depressed compared to those who are not. The study
demonstrates that brain regions, collectively known as the default mode network, behave
differently in depressed people. The default network typically is active when the mind
wanders. It shuts down when an individual focuses on the job at hand. But the researchers
found the network stays active in people who are depressed, even when they are
concentrating on specific tasks. The new work suggests individuals with depression may not
be able to "lose themselves" in work, music, exercise or other activities that
enable most healthy people to get "outside" of themselves.
Perinatal environment influences
aggression in children
It's a well-documented fact that children
from zero to two can be spontaneously aggressive and that boys can be among the worse
culprits. Even after being socialized, seven percent of boys will continue to be
hyper-aggressive until the age of nine. According to a new study, this small sub-group of
aggressive children has a different makeup than non-aggressive children. "We know
that when the mother faces adverse conditions such as poverty, stress, malnutrition,
family conflicts or tobacco use during pregnancy, it will directly influence the size and
weight of the fetus," says Sylvana Côté, a professor at the Université de
Montréal Department of Social and Preventive Medicine and the lead researcher of this
study. "These conditions are also correlated to heart disease, diabetes and child
obesity." "The education practices of the parents, as well as the transmission
of a genetic profile predisposing aggressive behavior are also contributors to atypical
violent development," adds Côté, who cautions the impact of the perinatal
environment on DNA methylation also has an impact.
Tiny samples could yield big
predictive markers for pancreatic cancer
A handful of proteins, detected in
incredibly tiny amounts, may one day help doctors distinguish between a harmless lesion in
the pancreas and a potentially deadly one, say researchers at Fox Chase Cancer Center. The
researchers believe that these protein biomarkers, if confirmed in subsequent studies,
could represent reliable indicators of pancreatic cancer or precancerous pancreatic
lesions, which would allow for earlier, perhaps more successful, treatment. Their findings
appear in the March issue of the journal Pancreas, available online now. "New
technologies have become very good at identifying pancreatic cysts when they appear, but
we know very little about how to categorize these cysts," says the study's senior
author Anthony Yeung, Ph.D., molecular biologist and member of Fox Chase's faculty.
"We can detect, in as little as 40 microliters of cyst fluids a group of proteins
that might collectively be used as indicators of a potentially cancerous cyst." The
difficulty of detecting pancreatic cancer early is one of the reasons that the disease
remains one of the deadliest forms of cancer. In some cases, pancreatic cancer develops
within small pancreatic cysts that are originally benign, but become cancerous over time.
As high-resolution imaging techniques, such as magnetic resonance imaging (MRI), are used
more often in clinical medicine, doctors are finding many more small, fluid-filled cystic
lesions of the pancreas. "Many of these cysts are completely benign and have little
or no risk of becoming cancerous. However, a subset of pancreatic cysts carry a real risk
of becoming malignant over time," says co-author Jeffrey Tokar, M.D., Fox Chase
gastroenterologist. "Many patients with pancreatic cysts are referred to us for
endoscopic needle aspiration of fluid within the cyst, which is then sent to the
laboratory and a variety of tests are commonly performed. However, while these tests can
be useful, it often remains impossible to tell a patient their absolute risk of
progression to cancer."
