Stories of using the little blue pill for bone marrow transplants, how pregnancy stress is related to the baby's sex, and a vaccine for breast cancer proliferated on the Internet this week. Here's why you didn't read about them on Medscape.

Researchers at the University of California, Santa Cruz, seem to think Viagra has more to offer in medicine. In a recent study of mice, they tested whether the vasodilator couldspeed up the migration of hematopoietic stem cells and progenitor stem cells from the bone to the blood, where the cells could be harvested noninvasively.

The standard protocol for preparing bone marrow donors for the harvesting procedure, a 5-day regimen of granulocyte-colony stimulating factor (G-CSF),is "complex, costly, unsuccessful in a significant proportion of donors," the study authors write, and typically results in fatigue, nausea, and bone pain. Using a two-drug strategy, oral Viagra and a single injection of the CXCR4 antagonist AMD3100 (plerixafor), elicited the same mobilization of stem cells in 2 hours.

We didn't cover the study because it's still too early to say whether this strategy might be effective in people. After this mouse study, the next step is testing the approach in larger animals before human clinical trials.

A study of 187 healthy pregnant women age 18 to 45 years suggests that preterm mental and physical stress may be related to the baby's sex and increase the risk for preterm birth. In the study, 16% of women were physically stressed, as measured by higher blood pressure and calorie intake; and 17% were mentally stressed with high levels of depressionand anxiety; 66% of the women were in the healthy (nonstressed) group.

Women who were stressed during pregnancy were more likely to give birth to a girl. Typically, 105 males are born for every 100 females, but the study authors found that the male-to-female ratio decreased to 2:3 in psychologically stressed patients and 4:9 in physically stressed patients. Physically stressed mothers also gave birth an average of 1.5 weeks earlier than mothers in the healthy group, with 22% giving birth preterm compared with 5% in the healthy group.

The study authors say the findings demonstrate the importance of maternal mental health. Medscape has covered the consequences of maternal stress extensively, including preterm birth, neurobehavioral risks, and potential links to hyperactivity during the offspring's teen years. However, the sample size in this study was small: the mentally and physically stressed groups combined only included about 60 women. That's not sufficient to inform clinical practice in counseling women who want to get pregnant about how stress may affect the sex of their baby, so we didn't cover it.

News spread this week that Floridian Lee Mercker became the first woman to "beat" breast cancer with the help of a new vaccine. The vaccine, which stimulates the immune system to fight off early-stage breast cancer, was developed and administered by researchers at the Mayo Clinic in Jacksonville, Florida. The vaccine is currently in an early trial.

Reports of Mercker's success raise hopes, but she's reportedly the first participant in the trial. The news report also says she underwent a double mastectomy after her diagnosis in March, so it's unclear what evidence of the vaccine's efficacy the researchers measured. Before this experimental vaccine is relevant to Medscape readers, we need to see additional detailed data from more patients in the clinical trial published in a peer-reviewed journal.

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The Week That Wasn't: Viagra BMTs, Pregnancy Stress, Breast Cancer Vaccine - Medscape