Gut bacteria may influence thoughts and behaviour

The human gut contains a diverse community of bacteria which colonize the large intestine in the days following birth and vastly outnumber our own cells. These intestinal microflora constitute a virtual organ within an organ and influence many bodily functions. Among other things, they aid in the uptake and metabolism of nutrients, modulate the inflammatory response to infection, and protect the gut from other, harmful micro-organisms. A new study by researchers at McMaster University in Hamilton, Ontario now suggests that gut bacteria may also influence behaviour and cognitive processes such as memory by exerting an effect on gene activity during brain development.

Jane Foster and her colleagues compared the performance of germ-free mice, which lack gut bacteria, with normal animals on the elevated plus maze, which is used to test anxiety-like behaviours. This consists of a plus-shaped apparatus with two open and two closed arms, with an open roof and raised up off the floor. Ordinarily, mice will avoid open spaces to minimize the risk of being seen by predators, and spend far more time in the closed than in the open arms when placed in the elevated plus maze.

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Removal of a parasitic worm from the brain

Fox 10 News has a rather gruesome story about the removal of a live parasitic worm from a woman’s brain, which is accompanied by a film clip  containing footage of the surgical procedure.

As the film explains, the woman, who lives in Arizona, first started to experience flu-like symptoms, followed by numbness in her left arm which grew progressively worse. Neurosurgeon Peter Nakaji operated, expecting to find a tumour in the brainstem, but instead found and removed a tapeworm.

It goes on to say that the woman was infected either by eating uncooked pork or unwashed food contaminated with infected human faeces (making this most probably a pork tapeworm infection); that this was the sixth such case seen by Nakaji in the past few months; and that this is extremely rare but has started to increase recently.

Horrific as this all sounds, the woman in the film was in fact very fortunate, because if it had been the tapeworm larvae, instead of the worm itself, which had entered her brain, the consequences of her infection would have been much more severe.

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