July 10--DOWN SYNDROME
Asthma drug boosts mice's cognition
Stanford researchers have discovered that a drug approved for asthma helped improve cognitive function in mice with Down syndrome, a finding they hope could lead to additional treatments for people with this genetic disorder.
The drug, called formoterol, strengthened nerve connections in the hippocampus, the component of the brain used for spatial navigation, attention and the formation of new memories, the study found.
In addition to the improved function, the drug also appeared to help with contextual learning, the type of learning in which the brain integrates spatial and sensory information. Both hippocampal function and contextual learning are impaired in people with Down syndrome, which is caused by an extra copy of chromosome 21.
Boosting levels of a neurotransmitter in the brain may reverse some of the cognitive abnormalities. The drug activates certain receptors in the brain that make the neurons more complex and improve brain function.
Down syndrome affects about 400,000 people in the United States and 6 million worldwide.
The study was published online last week in the journal Biological Psychiatry.
- Victoria Colliver
Hyper-connectivity found in parts of children's brains
In children with autism, certain regions of the brain are much more strongly connected than they are in children without autism, and the hyper-connectivity of one region in particular may help explain some of the most prominent symptoms found in many patients, according to Stanford researchers.
The scientists performed brain scans on 20 autistic children and 20 typically developing children. In the children with autism, five regions of the brain were hyper-connected, meaning there was stronger than normal signaling across neural pathways. Other parts of the brain, however, were under-connected.
One region with hyper-connectivity that scientists found especially interesting was the salience network. That part of the brain is known to process external stimuli and prioritize incoming information. The strong connectivity there may have something to do with the intense, narrow focus many autistic children show toward particular objects or interests.
In addition to adding to scientists' understanding of brain functioning and autism, the brain imaging study also could be used in developing diagnostic tools, researchers said.
The new research was published June 26 in the journal JAMA Psychiatry.
- Erin Allday
Genes that lead to birth defects may also lead to mental illness
Gene mutations that are involved in birth defects may also be implicated in psychiatric disorders such as schizophrenia, autism and bipolar disorder, according to a new UCSF study.
Previous research has shown that mice with mutations in a gene called Dact1 are born with a range of severe birth defects. In the new study, which also involved mice, scientists selectively deleted the Dact1 protein in a group of brain cells that regulates cognitive and sensory processes and other activity in the cerebral cortex.
When the team examined these genetically altered cells, they found they had significantly fewer synapses, the sites where communication with neighboring neurons occurs.
While the cells looked otherwise normal, the researchers noted that the subtle changes were similar to the changes that have been identified in psychiatric illnesses in humans.
The study appeared online June 24 in Plos One.
- Stephanie M. Lee
Vitamin C helps control gene activity in mice
Vitamin C helps control gene activity in mouse stem cells and may play a role in guiding normal development in mice and humans, new research from UCSF suggests.
Vitamin C, the scientists found, helps enzymes that play a role in releasing the brakes that keep some genes from becoming activated in the embryo soon after fertilization.
The brakes are molecules called methyl groups. These are added to DNA at specific points along the genome to keep specific genes from activating. According to the study, vitamin C boosts a class of enzymes that removes those molecules. The result, in cultured stem cells, is stimulated gene activity that mirrors what occurs at early stages of embryo development in mice.
Eventually, vitamin C might be used to improve the results of in vitro fertilization, which involves the growth of early embryos, and to treat cancer, in which tumor cells abnormally stop or release these brakes on gene activation. For now, researchers said, vitamin C may start being used more often in the lab to grow healthy, useful stem cells.
The study appeared June 30 in the journal Nature.
- Stephanie M. Lee
New mouse model clarifies mystery
Children with Duchenne muscular dystrophy, an inherited disorder that involves muscle weakness, often die from heart and breathing complications. But scientists have long been confused that lab mice with the same genetic mutation behind the disease in humans show only mild symptoms.
Researchers at Stanford University School of Medicine have developed a mouse model that for the first time sheds light on a molecular basis for the cardiac defect that is the primary killer of people with the disease.
Humans suffer more serious symptoms, the scientists found, because the telomeres on the ends of their chromosomes are relatively short. Mice have telomeres about 40 kilobases in length, while human telomeres are 5 to 15 kilobases long. (A kilobase is the unit used in designating the length of a nucleic acid sequence and is 1,000 nucleotides.)
Shortened telomeres make the heart unable to contract well, the scientists said. This became apparent when the researchers gave the mice a mutation that reduced their telomere length, and the animals began to show muscle weakness, enlarged hearts, shortened life spans and other typical symptoms of the disease.
The study appeared in Nature Cell Biology last week.
- Stephanie M. Lee
Absence of gene leads to a more severe case
A team of UCSF-led scientists say they have identified, in an animal study, the likely genetic mechanism that causes some patients with multiple sclerosis to quickly enter a severe stage of the disease, and others to progress more slowly.
Multiple sclerosis is a potentially debilitating disease in which the immune system eats away at the protective sheath, known as myelin, that covers the nerves. It may result in the irreversible deterioration of the nerves themselves.
In the study, the scientists found that the absence of the gene Tob1 in a type of immune cell called CD4+ T-cells was the key to early onset of a more serious disease in a mouse model of multiple sclerosis.
When mice genetically engineered to be deficient in Tob1 had a multiple sclerosis-like disease induced in them, they developed an aggressive form of the disease significantly earlier than a control group. The presence or absence of this gene, scientists said, could eventually help doctors predict the onset and severity of the disease in patients.
The study was published June 24 in the Journal of Experimental Medicine.
- Stephanie M. Lee
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