Organ Regeneration: Researchers used stem cells to grow a replacement tooth for an adult mouse, the first time scientists have developed a fully functioning three-dimensional organ replacement, according to a report in the Proceedings of the National Academy of Sciences. The researchers at the Tokyo University of Science created a set of cells that contained genetic instructions to build a tooth, and then implanted this “tooth germ” into the mouse’s empty tooth socket. The tooth grew out of the socket and through the gums, as a natural tooth would. Once the engineered tooth matured, after 11 weeks, it had a similar shape, hardness and response to pain or stress as a natural tooth, and worked equally well for chewing. The researchers suggested that using similar techniques in humans could restore function to patients with organ failure.
Caveat: The researchers didn’t report any attempts to test their technique on humans yet.
Factors for Poor Sleep: Children whose mothers drank the alcoholic equivalent of one glass of wine per week during pregnancy slept much worse than children not exposed to alcohol in the womb, according to a study in SLEEP. The researchers used movement sensors and sleep logs to measure the sleeping habits of 289 eight-year-old Finnish children and matched the data to their mothers’ use of alcohol and tobacco during pregnancy. Children who were exposed to alcohol in the womb were three times as likely to sleep fewer than 7.7 hours per night as were non-exposed children, independent of related factors like low birth weight, premature birth or parents’ continued use of alcohol. Maternal tobacco use during pregnancy didn’t have a significant effect on the children’s sleep quality.
Caveat: The study was small, and the researchers cautioned that unrecognized environmental factors could have influenced the findings. Additionally, mothers could have felt pressure to under-report their alcohol consumption, but the researchers said the self-reports matched closely with more rigorous estimates of alcohol consumption during pregnancy.
Predicting Diabetes: Men and women with high levels of sex-hormone-binding globulin in their blood were significantly less likely to develop Type 2 diabetes than subjects with low levels of the protein, according to a study in the New England Journal of Medicine. Previous studies had found an inverse association between sex-hormone-binding globulin, a molecule that attaches to and temporarily deactivates testosterone and estradiol, and insulin resistance. This study was the first to examine whether the association was reflected in the risk for diabetes. Indeed, the molecule was considerably more predictive of diabetes than traditional risk factors. The 25% of subjects with the highest levels of the protein appeared to be 10 times less likely to develop Type 2 diabetes than subjects in the lowest quartile.
Caveat: The study was relatively small—fewer than 600 subjects with newly diagnosed Type 2 diabetes, and an equal number of control subjects.
Blood Transfusions: Heart-bypass patients who received transfusions of another person’s blood during the procedure were twice as likely as non-transfused patients to become infected while in the hospital, according to a large study of Medicare beneficiaries in BMC Medicine. Of the nearly 25,000 coronary artery bypass graft patients, 83.9% were transfused with such “allogeneic” blood, 1.2% with their own or a twin’s blood, and the rest not at all. Eighteen percent of the patients who received allogeneic blood then became infected while in the hospital, compared to just 6.6% of nontransfusion patients, and 9.7% of patients transfused with their own or genetically identical blood. The researchers suggested that the infections were due not to tainted blood but to a general suppression of the immune system by the introduction of foreign blood into the body.
Caveat: The researchers were unable to measure underlying factors, such as pre-existing diseases, that could have confounded the findings—these could have led to both higher rates of transfusion and higher rates of infection independently. However, the researchers said that such factors were unlikely to significantly alter the results.
Itch vs. Pain: Itch is a distinct sensation from pain and not, as had been commonly hypothesized, a sub-sensation of pain, according to an experiment published in Science. The researchers destroyed the neurons known to transmit itch sensations in the spinal cords of mice. When the researchers applied itch-inducing substances to the skin of these mice, the altered mice scratched approximately 75% less often as did normal mice. By contrast, destroying the neurons had no effect on the sensation of pain; the altered mice responded no differently than normal mice to stimuli known to cause pain, such as acute heat or the application of mustard oil.
Caveat: The researchers didn’t discuss how the results might differ for human sensations of itch and pain.
Cancer Screening: Cervical screenings for women ages 20 to 24 provided no protection against invasive cervical cancer during the following five years, according to a study in BMJ. The exams, known as PAP smears, have been shown to prevent as much as 80% of cervical cancer cases in older women, by identifying precancerous tissue before it fully progresses. But the latest study, which compared the medical records of 4,012 U.K. women with the cancer to 7,889 cancer-free but otherwise similar control cases, found that women who had been screened for cervical cancer before age 25 weren’t less likely than unscreened women to develop the disease up to age 30. The test didn’t reduce the overall cases of invasive cervical cancer for this age group. The researchers suggested a biological basis for the findings: In young women, most cervical cancers may progress slowly enough that they remain benign for much of early adulthood, while cases that pose a threat may progress so quickly that they may be undetectable during such early screenings.
Caveat: The study didn’t examine the possible harms of early cervical screening, but said the most common were the anxiety of receiving abnormal test results and the side effects of treating suspect tissue that would never have become cancerous.
As reported in the Wall Street Journal Online 2009