Graduate student Vanessa Ridaura and colleagues at the Center for Genome Sciences and Systems Biology, University of Washington School of Medicine reported in the September 6 issue of Science that mice lacking bacterial colonies of their own that received gut bacteria from obese humans put on more weight and accumulated more fat than mice that were given bacteria from the guts of lean humans.
To directly test the influence of the human gut microbiome on obesity, the investigators sampled microbes living in the guts of human fraternal and identical twins, one of whom was lean while the other, obese. They introduced these microbes into germ-free mice fed low-fat mouse chow, as well as diets representing different levels of saturated fat and fruit and vegetable consumption typical of the U.S. diet. Increased total body and fat mass, as well as obesity-associated metabolic phenotypes, were transmissible with uncultured fecal communities and with their corresponding fecal bacterial culture collections.
Anxiety disorders, which include posttraumatic stress disorder, social phobias and obsessive-compulsive disorder, affect 40 million American adults in a given year. Currently available treatments, such as antianxiety drugs, are not always effective and have unwanted side effects.
To develop better treatments, a more specific understanding of the brain circuits that produce anxiety is necessary, says Kay Tye, an assistant professor of brain and cognitive sciences and member of MIT’s Picower Institute for Learning and Memory.
The tips of long neuronal extensions from the amygdala (green) contact neurons of the hippocampus (blue). This communication pathway helps to modulate anxiety.
IMAGE: ADA FELIX-ORTIZ
Scientists have grown miniature human brains in test tubes, creating a “tool” that will allow them to watch how the organs develop in the womb and, they hope, increase their understanding of neurological and mental problems.
Just a few millimetres across, the “cerebral organoids” are built up of layers of brain cells with defined regions that resemble those seen in immature, embryonic brains.
The scientists say the organoids will be useful for biologists who want to analyse how conditions such as schizophrenia or autism occur in the brain. Though these are usually diagnosed in older people some of the underlying defects occur during the brain’s early development.
The organoids are also expected to be useful in the development and testing of drugs. At present this is done using laboratory animals or isolated human cells; the new organoids could allow pharmacologists to test drugs in more human-like settings.
Stem cell scientists at Edinburgh and the Institute of Molecular Biotechnology in Vienna grew this organoid, or tiny ‘brain’, which measures just 4mm across. Photograph: Madeline A Lancaster/PA
Posted August 25, 2013on:
For most of the past 40 years, cancers have been treated by surgery, radiotherapy or chemotherapy. This last technique involves the use of cytotoxic drugs which can kill cells that they encounter. By carefully adjusting doses of these drugs, doctors have been able to kill off cancer cells while leaving normal cells unaffected – in many cases. But the considerable toxicity of chemotherapy drugs means they can only be administered for a few weeks, which limits their tumour-killing potential.