Word: braine
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Dates: during 2000-2009
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...Zhongcong Xie, now an associate professor of anesthesia at Massachusetts General Hospital, and colleagues published the first in a series of studies demonstrating that commonly used general anesthetics can cause cell death and plaque accumulation in brain cells - both potential hallmarks of dementia and Alzheimer's disease. More recently, at the Mayo Clinic, in Minnesota, anesthesiologist Dr. Robert Wilder published a study that found a link between exposure to anesthesia and surgery in infancy and learning disabilities later in life. Both doctors have since been approached with inquiries from concerned patients - but armed only with early data, neither can offer...
...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...
...separate area of research, Xie at Massachusetts General tested another anesthetic, isoflurane, on a culture of human brain cells. (Isoflurane had 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...
...animals." If anesthetics have always been neurotoxic, one slide in her presentation asked, "Why is it only an issue now?" She and others point out that non-human testing of anesthetic safety has an unreliable history. Ten years ago, for instance, lab researchers found evidence that isoflurane protected brain cells during surgery and trauma, only to be contradicted by more recent lab findings...