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November 3, 2017
Digest
Healthy Lifestyle Lowers Heart Attack, Stroke Risk After Gestational Diabetes

Women who have had gestational diabetes may be able to reduce or even eliminate their risk for cardiovascular disease by following a healthy lifestyle in the years after giving birth, according to a study by researchers at NIH.

The researchers analyzed data from the Nurses’ Health Study following health habits and medical history of more than 90,000 women from before pregnancy through middle age and the early senior years.

The study confirms the links between gestational diabetes and cardiovascular disease found by other studies. It also provides some of the strongest evidence to date that cardiovascular disease after gestational diabetes isn’t inevitable for women who adopt a healthy diet, maintain a healthy weight, exercise moderately and do not smoke.

The study was led by Dr. Cuilin Zhang of NICHD’s Division of Intramural Population Health Research and colleagues. It appeared in JAMA Internal Medicine.

Gestational diabetes is a type of diabetes—or high blood sugar—that occurs only during pregnancy. Although it often disappears after birth, many women who had the condition later develop type 2 diabetes, usually by middle age. Some studies have shown women who had gestational diabetes are also at risk for cardiovascular disease, such as high blood pressure, high blood cholesterol, hardening of the arteries, heart attack and stroke.

In the current study, the researchers found that women who failed to adopt a healthy lifestyle in the wake of gestational diabetes had a 43 percent higher risk for cardiovascular disease, particularly heart attack and stroke.

New Regions of the Human Genome Linked to Skin Color Variation in Some African Populations

In the first study of its kind, an international team of genomics researchers has identified new regions of the human genome that are associated with skin color variation in some African populations, opening new avenues for research on skin diseases and cancer in all populations.

The findings may help researchers determine if humans with certain DNA sequences are more or less susceptible to DNA damage caused by ultraviolet radiation (UVR) or respond to cellular stress differently. NIH researchers contributed to this effort, led by Dr. Sarah Tishkoff at the University of Pennsylvania. The findings were published Oct. 12 in Science.

Studying human skin pigmentation helps researchers understand how the cells that produce skin pigment—melanocytes—and genes work together to protect skin from the damaging effects of UVR. Because equatorial regions receive approximately two times more UVR than more temperate regions, darker pigmentation in people from these regions is thought to reduce skin damage and cancer. In contrast, lighter pigmentation of people in northern countries may increase the production of vitamin D3 needed to prevent rickets, a softening and weakening of bones in children, usually due to inadequate vitamin D.

Researchers studying genes that contribute to skin color for the last hundred years have focused on analyzing differences among European populations. This study of ethnically diverse populations in Ethiopia, Tanzania and Botswana has shed light on regions of the genome not previously associated with skin color.

“This is transformative research because it provides new pathways for studying pigmentation and pigment cell diseases,” said Dr. William Pavan, co-author of the study and senior investigator in NHGRI’s Genetic Disease Research Branch.

“The paper also provides a foundation for others to investigate the DNA loci and associated genes that play roles in skin cancer susceptibility and the effects of UV radiation.”

Experimental Ebola Vaccines Elicit Year-Long Immune Response

A volunteer receives an injection in the PREVAIL Ebola vaccine clinical trial in Liberia
A volunteer receives an injection in the PREVAIL Ebola vaccine clinical trial in Liberia.

PHOTO: PREVAIL

Results from a large randomized, placebo-controlled clinical trial in Liberia show that two candidate Ebola vaccines pose no major safety concerns and can elicit immune responses by 1 month after initial vaccination that last for at least 1 year. The findings, published in the Oct. 12 issue of the New England Journal of Medicine, are based on a study of 1,500 adults that began during the West Africa Ebola outbreak.

The trial is being conducted by a U.S.-Liberia clinical research collaboration known as the Partnership for Research on Ebola Virus in Liberia (PREVAIL) established in 2014. It is sponsored by NIAID and involves scientists and clinicians from Liberia and the United States.

“This clinical trial has yielded valuable information that is essential for the continued development of these two Ebola vaccine candidates and also demonstrates that well-designed, ethically sound clinical research can be conducted during an epidemic,” said NIAID director Dr. Anthony Fauci. “A safe and effective vaccine would be a critically important addition to classical public health measures in controlling inevitable future Ebola outbreaks.”

Ovarian Reserve Tests Fail to Predict Fertility, Study Suggests

Tests that estimate ovarian reserve, or the number of a woman’s remaining eggs, before menopause, do not appear to predict shortterm chances of conception, according to an NIH-funded study of women with no history of infertility. The study appeared in the Journal of the American Medical Association.

“Women are born with a set number of eggs that gradually declines through the reproductive years,” said Dr. Esther Eisenberg of NICHD’s Fertility and Infertility Branch, which funded the study. “This study suggests that testing for biomarkers of ovarian reserve does not predict the chances for conception in older women still of reproductive age.”

As a woman ages and her egg supply declines, cells in the ovary secrete lower amounts of inhibin B and anti-Müllerian hormone, substances considered to be indicators of ovarian reserve. The ovaries also produce higher amounts of follicle stimulating hormone (FSH) in the days before ovulation.

Although there is little research to support their use, tests for anti-Müllerian hormone are routinely offered in many fertility clinics on the assumption that women with a lower ovarian reserve would be less likely to respond to treatment. Moreover, home fertility tests of urinary FSH are commercially available.

“Our study suggests that younger women with biomarker levels indicating lower ovarian reserve should not become anxious that they won’t be able to have a baby,” said Dr. Anne Steiner, first author of the study and professor of reproductive endocrinology and infertility at the University of North Carolina at Chapel Hill.

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