Dying leaves its mark in the brain Genetic analyses should take into account cause of death. 2 February 2003 HELEN PEARSON Researchers have opened a window into the state of the human brain at the moment a person dies. The findings call into question previous reports based on brain autopsy tissue. Richard Myers of Stanford University in California and his colleagues found that a coma patient fires up a different set of genes in the brain than one who dies quickly from a heart attack. The group stumbled on the discovery when studying preserved human brain tissue. Using a chip carrying thousands of genes, the researchers analysed which ones are active in the brains of 40 people with depression, bipolar disorder, schizophrenia or none of these. They were searching for genes that were activated abnormally and therefore might underlie the disorders Instead, they noticed that the patterns of active genes fell into two distinct groups - depending on how the patients had died. "The statistics were screaming at us," Myers says. "It was pretty remarkable." Those who suffered prolonged deaths over hours or days, such as by multi-organ failure or coma, showed one type of genetic profile. Those who died suddenly from a heart attack, accident or suicide showed another1. Myers thinks his group has inadvertently taken a snapshot of dying brain tissue. During a prolonged illness, the brain might be starved of oxygen and sugars, triggering it to switch on a whole suite of genes that help cells survive. The dying brain also seems to dampen down genes involved in energy metabolism, perhaps because the cells are deprived of essential nutrients. Patients who suffered a prolonged death also seem to have more acidic brain tissue. This might be because cells deprived of oxygen churn out acidic by-products, such as lactic acid, as they make energy. "Brain death probably occurs when the pH threshold is crossed," suggests team member Jun Li. Read the rest at Nature http://www.nature.com/nsu/040126/040126-20.html Probiotic bacteria health boon Gut-friendly bugs don't have to be alive to boost immune system. 03 February 2004 MICHAEL HOPKIN Television advertisements are filled with advice about the benefit of foods containing 'friendly' bacteria, such as probiotic yoghurt. But a US-led research team now says that you don't need live bacteria to boost your digestive system - just their DNA. If true, that should allow the health effects of these bacteria to be incorporated into a range of different types of foods, or even pills and injections. Live bacteria are generally restricted to products such as dairy foods, because cooking or heating the cultures kills them. The average human gut contains about 100 different species of bacteria, including 'good' bacteria, such as Lactobacillus and Bifidobacterium, which aid digestion, bolster the immune system and battle for space with 'bad' bacteria, such as those that cause food poisoning. Some of these beneficial bacteria are added to products such as live-culture yoghurt. Probiotic foods and supplements are big business - the worldwide market is worth around US$6 billion a year. http://www.nature.com/nsu/040202/040202-1.html Plants to uncover landmines Genetically engineered plants turn red when growing over a mine. 29 January 2004 LAURA NELSON A genetically engineered plant that detects landmines in soil by changing colour could prevent thousands of deaths and injuries by signalling where explosives are concealed. The plant, a modified version of thale cress (Arabidopsis thaliana), is sensitive to nitrogen dioxide gas, which is released by underground landmines. The leaves of the plant change from green to red after three to five weeks of growth in the presence of this gas. "They are easy to spot," says Carsten Meier of the University of Copenhagen, Denmark, who served as scientific adviser to Aresa, the Danish company that developed the plant. The team doesn't yet know how sensitive the plant is to nitrogen dioxide, and therefore are not sure how much of the gas is needed to make it turn red. But they hope the technique will prove useful in field tests. If it does, it should substantially speed up the process of de-mining. Currently, one person can check and clear just two square metres of land a day, says Meier. "Landmines are laid down faster than they are removed," he adds. "This is a great idea," says Richard Vierstra, a horticulture scientist at the University of Wisconsin, Madison, who works on Arabidopsis. He points out that the plant is quite shallow-rooted, and so will only detect mines near the surface. But this is where most landmines are found, says Geir Bjoersvik, head of the mine action unit for the landmine-removing project at Norwegian People's Aid. http://www.nature.com/nsu/040126/040126-10.html Posted by Robert Karl Stonjek.
