The Malaysian Insider :: Features
The Malaysian Insider :: Features |
| Why Black Death was the mother of all plagues Posted: 17 Oct 2011 04:59 AM PDT  Bubonic plague bacteria taken from a patient. Plague germs teased from mediaeval cadavers in a London cemetery have shed light on why the bacterium that unleashed the Black Death was so lethal and spawned later waves of epidemics. – AFP pic The DNA of Yersinia pestis shows, in evolutionary terms, a highly successful germ to which the population of 14th-century Europe had no immune defences, according to a study published recently in the British journal Nature. It also lays bare a pathogen that has undergone no major genetic change over six centuries. "The Black Death was the first plague pandemic in human history," said Johannes Krause, lead researcher and a professor at the University of Tuebingen, Germany. "Humans were (immunologically) naive and not adapted to this disease," he said in an email exchange. No bug or virus has wiped out a greater proportion of humankind in a single epidemic than the Black Death. Brought to Europe from China, it scythed through the continent from 1347 to 1351, killing about 30 million people – about one in three of Europe's and nearly one in 12 of the world's population at the time. Remarkably, more recent variants of the bacterium hardly vary compared to the original microbe, says the paper. "Based on the reconstructed genome, we can say that the mediaeval plague is close to the root of all modern human pathogenic plague strains," said Krause. "The ancient plague strain does not carry a single position that cannot be found in the same state in modern strains." This deep similarity between ancient and modern plague calls into question the long-held assumption that virulence-enhancing mutations are what made Y. pestis so deadly to the Middle Ages. Like Native American Indians who were exposed to smallpox, Europeans had never been exposed to the bacterium, said Krause. "Plague was among the strongest sources of selection on the human population in the last few thousand years," he added. "People who were less susceptible due to mutations might have survived, and these (beneficial) mutations may have spread." Another likely factor that worsened the Black Death's toll was social conditions, which were far worse compared to the 18th or 19th centuries. Poverty and malnutrition were rampant, and even the concept of hygiene was non-existent. The onset of the so-called "Little Ice Age" could also have favoured the spread of the disease which, like many pathogens, travels more quickly in cold climes. The same goes for the rats that carried the blood-sucking insects – fleas or lice, perhaps both – that transmit the disease. Indeed, the species of rodent, Ratus ratus, that sowed terror across a continent in the 14th century is not the same as the one that transports plague today, Ratus norvegicus, Krause said. The 1918-19 Spanish flu pandemic killed by some estimates 50 million people. In absolute terms, this was the deadliest pandemic in human history. But with a world population that was close to two billion, the toll in relative terms was far smaller than that of the Black Death, when the number of humans was in the hundreds of millions. The first outbreak of plague occurred in China more than 2,600 years ago before reaching Europe via Central Asia's "Silk Road" trade route, according to a molecular "family tree" – mapped out last year – of 17 Y. pestis strains. It then spread to Africa, probably by an expedition led by Chinese seafarer Zhang He in the 15th century. In the late 19th century, plague came to the United States from China, arriving in the ports of California via Hawaii, according to this evidence. – AFP Full content generated by Get Full RSS. |
| Green vegetables shown to help boost immune system Posted: 17 Oct 2011 12:02 AM PDT  Eating green vegetables like broccoli has been shown to help regulate the immune system. — AFP pic That's the conclusion of a new study from researchers at the Babraham Institute in Cambridge, where scientists found that green vegetables turn out to be the source of a chemical signal that's important for a fully functioning immune system. The study, published online in the journal Cell October 13, found that these chemical signals ensure that immune cells in the gut and skin function properly. Known as intra-epithelial lymphocytes or IELs, the immune cells exist beneath another barrier of cells that cover inner and outer body surfaces and act as a first line of defence and help with wound repair. In lab experiments on mice, researchers found that a diet rich in green vegetables like broccoli or bok choy was found to help regulate this complex immune system, while the same was true of the reverse. After depriving mice of vegetables for three weeks, researchers said they found that 70 to 80 per cent of the protective cells disappeared. The weakened mice showed lower levels of antimicrobial proteins, heightened immune activation and were more vulnerable to injury. When researchers intentionally damaged the intestinal surface, for example, their bodies were slow to recover. The implications of their findings could help with conditions like inflammatory bowel disease, scientists say, which shares the same characteristics observed in the mice. Another study published last year in the British Medical Journal also found that eating more leafy green vegetables can significantly reduce the risk of developing type 2 diabetes. — AFP-Relaxnews Full content generated by Get Full RSS. |
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