Word: calcium
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...Fittingly, the initial discovery of the potentially neurotoxic effect of anesthesia occurred by accident. In the 1990s, scientists discovered that the brain cells of patients in the midst of a stroke were flooded with calcium. Doctors wishing to treat these patients hypothesized that blocking the receptor that enables calcium to enter cells could protect stroke patients from severe brain damage. But in the course of researching this possibility, they found that switching off the receptor in a healthy brain cell led to the death of that cell - an unexpected and troubling result, given that many common anesthetics block the same...
...role of calcium in the healthy brain is critical, particularly in young children, whose brains undergo rapid neural development from the last trimester in utero up through ages 1 to 2. Infants' brains expand quickly, then ruthlessly prune back brain cells - a process of orderly cell death, known as apoptosis. In an experiment in young rats undergoing this crucial stage of neural development, Christopher Turner, an assistant professor of neurobiology and anatomy at Wake Forest University School of Medicine, witnessed out-of-control apoptosis in the brains of rats treated with drugs that mimicked the action of the general anesthetic...
...already been shown to cause cognitive impairment in rats.) He saw a vicious cycle of apoptosis and the accumulation of beta-amyloid protein - the sticky plaques that build up in Alzheimer's patients' brains - among the cells. But in this case, it may have been an excess of calcium that led to cell death. Xie and his colleagues have since found that the Alzheimer's drug memantine, which works by reducing calcium levels inside cells, can slow the rate of isoflurane-induced cell death. "That certainly suggests that Dr. Turner and we could be looking at the different sides...
...blame for the lakes' sorry state: deforestation, construction of new hotels and private homes too close to the lakes, sewage and waste dumping, and poor governance, bribes and corruption. Nakamura was particularly critical of regional marble-cutting industries that dump white sludge, a waste powder made of calcium carbonate and other impurities from the marble. Some 100 factories in the area leave large tracts of the white stuff, which not only contaminate the air, the ground and eventually the waters, but also cause the huge areas of white to reflect the sunlight, creating their own micro-climatic-warming effect...
Scientists are unsure exactly how the patina is formed but most agree it is composed of deposits of solid calcium carbonate that come by way of rain or groundwater. It can contain particles added by wind and perhaps biological. Additionally, depending on the levels of acidity, it may also involve a chemical reaction with the surface of the object. Some scientists say the process is similar to the way stalagmites grow in caves; others disagree...