Frequent MRI Scanner Exposure Might Affect Memory: Study

Exposure to magnetic fields generated by MRI scanners may lower a person's mental skills, according to a small new study. The effects were most noticeable in tasks that required high levels of working memory, which could have implications for surgeons and other medical staff who work within the vicinity of MRI scanners, the researchers said. Along with radio waves, MRI uses strong magnetic fields to obtain detailed images of the brain and spine. Three types of magnetic fields-static, switched gradient and radiofrequency are used to create an MRI image. Even when no imaging is taking place, the static magnetic field is always present. Thirty volunteers completed the study. All were exposed to an MRI static magnetic field of zero, 0.5 (medium) and 1 (high). Each exposure was conducted one week apart. After each exposure, the volunteers were given 12 timed mental tasks to test the sorts of skills that a surgeon or other health care professional might use within the area of an MRI scanner. The results showed that the medium and high exposures to the static magnetic field had a significant effect on general functions such as attention, concentration and visual and spatial awareness. After medium and high exposures, volunteers took 5 percent to 21 percent longer to complete complex mental tasks, which rely on working memory. The exact implications and mechanisms of these subtle acute effects in practice remain unclear, researcher said. They noted that the introduction of increasingly powerful MRI machines has raised exposure levels to static magnetic fields for both patients and medical staff. To date, mainly health and safety concerns for patients have been evaluated, but possible consequences are particularly important for professionals since they are repeatedly exposed to static magnetic fields, the investigators noted. While the study found an association between MRI exposure and slower working memory, it did not prove a cause-and-effect relationship.

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 Bottle-Feeding May Raise Baby's Risk for Intestinal Trouble

Infants who are bottle-fed face a higher risk of developing a serious intestinal condition that can lead to surgery, researchers report. With pyloric stenosis, the lower part of the baby's stomach narrows and restricts the amount of food the infant gets and results in forceful vomiting, dehydration and salt and fluid imbalances. The reason it develops is unknown, but bottle-feeding has been suggested as a possible risk factor, the study authors noted. Bottle-feeding is a rather strong risk factor for pyloric stenosis and this adds to the evidence supporting the advantage of exclusive breast-feeding in the first months of life, said lead author. Pyloric stenosis is a severe and potentially fatal condition. It is the most common cause of gastrointestinal obstruction in early childhood and the most common condition requiring surgery in the first months of life. Although etiology of pyloric stenosis remains unclear. But the results of this study contributes with new insight into the etiology of pyloric stenosis and brings us closer to solving the enigma of its development. To look at the connection between bottle-feeding and pyloric stenosis, researchers used data on more than 70,000 infants to identify 65 who had to have surgery for pyloric stenosis. Of these infants, 29 had been bottle-fed. The researchers found bottle-feeding increased the odds of developing pyloric stenosis 4.6-fold. Moreover, the risk was seen even when the baby was breast-fed before being bottle-fed and it started within 30 days after bottle-feeding began, they noted. Although this finding only shows an association between bottle-feeding and pyloric stenosis and not a cause-and-effect link, it suggests that breast milk is protective against this disease, investigator added.

SOURCE: HealthDay News, September 2012

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FDA Approves New Once-a-Day HIV Pill

A new pill to treat HIV infection that combines four medicines and only has to be taken once a day was approved by the U.S. Food and Drug Administration. Stribild, contains the HIV drugs elvitegravir, cobicistat, emtricitabine and tenofovir disoproxil fumarate. It will be prescribed to people who have never been treated for HIV infection. Two of the drugs, elvitegravir and cobicistat, are new, the FDA noted. Elvitegravir interferes with one of the enzymes that HIV needs to multiply, while cobicistat inhibits an enzyme that metabolizes certain HIV drugs and so prolongs the effect of elvitegravir. The combination of emtricitabine and tenofovir disoproxil fumarate is already marketed and they work in concert to block another enzyme that HIV needs to replicate. Through continued research and drug development, treatment for those infected with HIV has evolved from multi-pill regimens to single-pill regimens. New combination HIV drugs like Stribild will help simplify treatment regimens. Earlier this year, the agency approved the first over-the-counter rapid HIV test for home use and gave its blessing to the first drug to be used to prevent HIV infection when used together with safe sex practices. Two clinical trials found between 88 percent and 90 percent of patients treated with Stribild had an undetectable amount of HIV in their blood after 48 weeks of treatment, the FDA said. The drug will carry a boxed warning that says it can cause a build-up of lactic acid in the blood and severe liver problems, both of which can be fatal. In the clinical trials, common side effects included nausea and diarrhea. Serious side effects include new or worsening kidney problems, decreased bone mineral density, fat redistribution and changes in the immune system, the FDA noted. The FDA also mentioned to conduct more research to further determine the drug's safety in women and children, how resistance develops to Stribild and possible interactions with other drugs.

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