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The East African : February 17th 2014
34 The EastAfrican OUTLOOK FEBRUARY 15-21,2014 S CI E N C E Is the catalogue of cancer genes done? The National Institutes of Health, sta≥ted a p≥oject in 2005 called the Cance≥ Genome Atlas By CARL ZIMMER Special Correspondent C ancer is a disease of genes gone wrong. When certain genes mu- tate, they make cells behave in odd ways. The cells divide swiftly, they hide from the immune system that could kill them and gain the nourishment they need to develop into tumours. Scientists started identifying these cancer genes in the 1970s, and their list slowly grew over the years. By studying them, scientists came to understand how different types of cancer develop, and in some cases they were even able to develop gene-targeting drugs. Last May, for example, the Food and Drug Administration approved a drug known as Tarceva to treat lung cancer in which a gene called EGFR has mutated. The National Institutes of Health, hoping to speed up the identification of cancer genes, started an ambitious project in 2005 called the Cancer Genome Atlas. They analysed 500 samples from each of more than 20 types of cancer and found a wealth of new genes. The data has helped scientists discover more of the tricks cancer cells use to thrive at our expense. “The Cancer Genome Atlas has been a spectacular success, there’s no doubt about that,” said Bruce Stillman, the president of Cold Spring Harbour Laboratory. But now, as the Atlas project is coming to an end, researchers at the Broad Institute of MIT and Harvard have published a study in the journal Nature that has scientists debating where cancer research should go next. They estimated that scientists would need to examine about BRIEFS 21 suffer from dengue fever in Dar es Salaam Twenty-one people have been admitted to different hospitals in Dar es Salaam following an outbreak of dengue fever. The country’s Ministry of Health said is strengthening its surveillance sites to ensure early detection. The patients were confirmed with the disease after samples tested at the National Institute of Medical Research laboratory turned out positive for dengue fever, a debilitating mosquito-borne disease caused by any one of four closely related dengue viruses. Rwanda signs $204m grant with Global Fund ISSUES RAISED Harold Varmus, the director of the National Cancer Institute, said the study has raised valuable questions. Mr Lander and his colleagues argue for finishing off the cancer gene catalogue. Lander said knowing most genes involved in cancer would be a powerful weapon against the disease. Stillman of Cold Spring Harbour Laboratory said completing the atlas has to be weighed against other needs. For many researchers, the question comes down to whether extending the atlas project would be the best use of existing research funds. 100,000 genes — 10 times as many as the $375 million Cancer Genome Atlas has gathered — to find most of the genes involved in 50 cancer types. “We now know what it would take to get a complete catalogue,” said Eric S. Lander, the founding director of the Broad Institute and a coauthor of the new study. “And we now know we’re not close to done. We have a lot left to learn.” Traditionally, scientists have identified cancer genes by comparing healthy cells with cancerous ones. If they find a statistically unusually high A scientist doing molecular research on DNA. Picture: File number of cells with mutations in a particular gene, they can then examine it to see if it really does help drive cancer — or if it is just carrying a harmless mutation. Mr Lander and his colleagues suspected this method could miss some genes. While some cancer genes affect most cells of a given type of cancer, other genes are only involved in a fraction of them. (EGFR, the gene treated with Tarceva, is mutated in only about 10 per cent of cases of non-small cell lung cancer.) Small samples of cancer cells may not contain the less common mutations. The Broad researchers suspected that they could catch some of these missing genes by looking at several cancer types at once, because some genes are not limited to a single type of cancer. For their new study, the scientists examined cancer samples from the Cancer Genome Atlas, as well as cancer samples from the Broad’s own collection. All told, they analysed 4,742 samples from 21 types of cancer. The new study detected many of the genes that other scientists have previously linked to those 21 types of cancer. But they also found new genes that had been overlooked before. All told, they identified 33 genes that they consider strong candidates for playing a role in cancer — a potential increase of the catalogue of cancer genes of 25 per cent. “This was eye-opening to me,” said Mr Lander. Mr Lander and his colleagues began to wonder how many genes could be found if scientists looked at more cancer samples. Was the cancer catalogue almost finished, or only just begun? They extrapolated from their own results to gauge how many more samples scientists would need to look at to find most cancer genes involved in at least 2 per cent of cancers of a given type. To find most cancer genes in- volved in the 50 most common types of cancer, the researchers estimated that they would have to analyse 100,000 samples. In other words, the atlas has taken us a tenth of the way to the finish line. Human b≥ain has unique a≥ea linked to cognitive powe≥s By A SPECIAL CORRESPONDENT ScienceDaily OXFORD UNIVERSITY researchers have identified an area of the human brain that appears unlike anything in the brains of some of our closest relatives. The brain area pinpointed is known to be in- timately involved in some of the most advanced planning and decision-making processes that we think of as being especially human. “We tend to think that being able to plan into the future, be flexible in our approach and learn from others are things that are particularly impressive about humans. We’ve identified an area of the brain that appears to be uniquely human and is likely to have something to do with these cognitive powers,” says Professor Matthew Rushworth of Oxford University’s Department of Experimental Psychology. MRI imaging of 25 adults was used to iden- tify key components in the ventrolateral frontal cortex area of the human brain, and how these components were connected up with other brain areas. The results were then compared with equivalent MRI data from 25 macaque monkeys. This ventrolateral frontal cortex area of the brain is involved in many of the highest aspects of cognition and language, and is only present in humans and other primates. Language is affected when other parts are damaged after stroke or neurodegenerative disease. A better understanding of the neural connections and networks involved should help the understanding of changes in the brain that go along with these conditions. The Oxford University researchers report their findings in the science journal Neuron. Professor Rushworth explains: ‘The brain is a mosaic of interlinked areas. We wanted to look at this very important region of the frontal part of the brain and see how many tiles there are and where they are placed. “We also looked at the connections of each tile — how they are wired up to the rest of the brain — as it is these connections that determine the information that can reach that component part and the influence that part can have on other brain regions.” From the MRI data, the researchers were able to divide the human ventrolateral frontal cortex into 12 areas that were consistent across all the individuals. “Each of these 12 areas has its own pattern of connections with the rest of the brain, a sort of ‘neural fingerprint,’ telling us it is doing something unique,” said Professor Rushworth. The researchers were then able to compare the 12 areas in the human brain region with the organisation of the monkey prefrontal cortex. Older siblings to get vaccinated to protect the babies. Pic: File Death toll from Hepatitis E in Karamoja now at 19 The death toll from Hepatitis E in Napak district, Karamoja in Uganda has risen from 15 to 19, while 706 people remain infected with the deadly viral disease. According to health officials, the low coverage of pit-latrines in the district, at 22 per cent, and few clean water sources are the major challenges to the fight against hepatitis E in the region. Health Ministry spokesperson, Rukia Nakamatte said the disease is not likely to be prevented soon unless alternative water sources are provided. Rwanda has signed a $204 million grant with the Global Fund for implementation of the five-year national strategic plan for HIV/Aids. The grant is part of an innovative result-based funding mechanism that the two entities agreed upon. The model is only applicable in high performing countries with robust national systems. Under the agreement, Rwanda will continue to monitor the achievement of universal access to HIV/Aids treatment and care for people living with the virus. The Global Fund will jointly verify the results of the programmes with Rwanda. Study urges vaccination of older siblings in Kenya A new study by the University of Warwick in collaboration with the Kenya Medical Research Institute Welcome Trust Research Programme suggests that vaccinating older siblings against Respiratory syncytial virus (RSV), (a disease that leads to mild, cold-like symptoms in adults and older children) could reduce deaths and serious illness in young babies. The study conducted in rural Kenya found that just over half of babies acquire the infection from someone within the household, whereas 32 per cent acquired it from outside the household.
February 10th 2014
February 24th 2014