all hormones stories

Hormones in milk can be dangerous

50443248 — Thu, 04 Oct 2007 09:58:49 -0400

Ganmaa Davaasambuu is a physician (Mongolia), a Ph.D. in environmental health (Japan), a fellow (Radcliffe Institute for Advanced Study), and a working scientist (Harvard School of Public Health).

On Monday (Dec. 4), she drew on all those roles during a lunchtime talk to most of her fellow fellows.

Ganmaa's topic was lunch-appropriate: the suspected role of cow's milk, cheese, and other dairy products in hormone-dependent cancers. (Those include cancers of the testes, prostate, and breast.)

The link between cancer and dietary hormones - estrogen in particular - has been a source of great concern among scientists, said Ganmaa, but it has not been widely studied or discussed.

Hormone mix raises breast cancer risk

Thu, 12 Jul 2007 14:41:01 -0400

Women who try to ease the symptoms of menopause by taking a testosterone-estrogen mix raise their risk for breast cancer, according to a Harvard Medical School study.

"As women age, their natural levels of testosterone decrease, along with those of estrogen," according to Rulla Tamimi, lead researcher of the study. "Evidence suggests that a testosterone drop is associated with a poorer quality of life, including decreased sex drive and bad moods, experienced by women at this time of life."

Molecular middleman puts thyroid hormone in developmental signaling pathway

70652986 — Mon, 26 Mar 2007 06:21:29 -0400

Tissues such as muscle and brain convert the inactive form of thyroid hormone, T4, into T3, the active form of thyroid hormone, when necessary. In the 1980s, researchers discovered that this conversion is accomplished by the deiodinase enzymes.

Several years ago, Antonio Bianco, Harvard Medical School associate professor of medicine at Brigham and Women's Hospital, and colleagues discovered that the deiodinase D2 is regulated by the ubiquitination pathway. Postdoctoral fellow Monica Dentice found that the protein WSB1 was the D2 ligase, the molecular adapter that fits the ubiquitination machinery to the protein.

It is known that WSB1 is induced by the hedgehog proteins, a family studied by Cliff Tabin, HMS professor of genetics. Development balances between proliferation and differentiation, and the hedgehog family is known for accomplishing this feat. Yet there are gaps in understanding the process. For example, Indian hedgehog (Ihh) promotes proliferation in the bones of young embryos by turning on a hormone, PTHrP, but it was unclear how it accomplishes this.

The researchers thought WSB1 regulation of D2 and thyroid hormone activation might play a role. Working with Tabin's lab, Dentice infected developing chick legs with a virus that overproduces Ihh, and she confirmed that D2 levels decreased in response to hedgehog's command, and WSB1 and PTHrP levels increased.

Studies chip away at sex hormone roles in prostate and breast cancers

70652986 — Mon, 26 Mar 2007 06:20:54 -0400

In recent work, Myles Brown and colleagues combined chromatin immunoprecipitation (ChiP) assays with measures of DNA structure and large-scale gene chip analyses to study where, when, and how androgen and estrogen receptors attach to DNA and control gene transcription. Their results should lead to new ways of manipulating receptor activity and shutting down cancer genes while leaving normal genes intact.

Appetite hormone restores fertility

70652986 — Mon, 26 Mar 2007 05:35:50 -0400

A hormone called leptin has been trumpeted as an appetite suppressor and a possible treatment for obesity. New research shows that "a clear connection also exists between fat, or energy storage, and the ability to reproduce," says Corrine Welt, an assistant professor of medicine who works at Massachusetts General Hospital, a Harvard affiliate. The women whose fertility was boosted by leptin injections had stopped menstruating as a result of losing an abnormal amount of fat, mainly by overexercising. In their 20s and early 30s, they pared themselves down to carrying about 40 percent less fat than is average for women their age. Such loss of menses, or amenorrhea, is also associated with abnormal levels of thyroid hormones and a loss of bone mass, which can lead to brittle, easily fractured bones. The findings thus raise the possibilities of new treatments for exercise-induced bone loss and for eating disorders, as well as for certain cases of infertility.

Study finds no direct links between testosterone therapy, diseases

70652986 — Mon, 26 Mar 2007 05:35:05 -0400

A comprehensive review of 72 studies addresses the current controversy about testosterone replacement therapy and its potential health risks to men. “We reviewed decades of research and found no compelling evidence that testosterone replacement therapy increases the incidence of prostate cancer or cardiovascular disease,” said Abraham Morgentaler, a urologist at Beth Israel Deaconess Medical Center (BIDMC) and associate clinical professor at Harvard Medical School. “Although it would be helpful to have data from long-term, large-scale studies, it must also be recognized that there already exists a substantial body of research on the effects of testosterone in men.” Since the 1940s researchers have known that severe reductions of testosterone can cause shrinkage of metastatic prostate cancer, and therefore there has been a concern that raising testosterone levels might cause growth of any hidden prostate cancers. However, the study by Ernani L. Rhoden and Morgentaler found no connection between higher testosterone levels and prostate cancer, nor did they find evidence that testosterone treatment causes prostate cancer. Also, studies of testosterone replacement therapy have not demonstrated an increased incidence of cardiovascular disease, myocardial infarction, stroke, or angina, according to the retrospective analysis.

Leptin serves body as energy signal

70652986 — Mon, 26 Mar 2007 06:21:00 -0400

Much leptin research in humans has focused on feasting rather than famine, but Christos Mantzoros's team, led by Jean Chan, a Harvard Medical School clinical fellow in medicine, took a different approach.

Mantzoros, lead author and HMS assistant professor of medicine at BIDMC, and his group studied eight healthy men to see how the changes in leptin induced by fasting regulated other neuroendocrine signals in normal humans.

Testosterone drives away the blues

70652986 — Mon, 26 Mar 2007 05:26:43 -0400

In the 1940s, experiments showed that major depression can be relieved by injecting testosterone into men with low levels of that hormone. The treatment never caught on because the shots are painful, and effective antidepressant drugs started coming to market. More recently, however, testosterone patches and gels became available. In June 2000, the United States Food and Drug Administration approved a new form of gel for treating muscle loss, decreased sex drive, lack of energy, and other symptoms of so-called hypogonadism, or underactivity of the testes. Harrison Pope, a Harvard professor of psychiatry, wondered if the gel might also help males with the combination of low testosterone and depression not treated successfully with drugs.

Hormone replacement therapy may lower degenerative eye disease risk in postmenopausal women

70652986 — Mon, 26 Mar 2007 05:26:32 -0400

ARM is a degenerative eye disease that affects the macula, which is responsible for central vision, which is necessary for reading, driving and recognizing people's faces. Advanced ARM is the leading cause of irreversible blindness among elderly individuals worldwide. Approximately 1.7 million people have decreased vision due to ARM, and 200,000 people develop advanced ARM with visual loss each year. A study published in the December 2002 issue of the American Journal of Ophthalmology showed that postmenopausal hormone therapy may reduce the risk of having advanced ARM among women with signs of maculopathy. "Decisions regarding postmenopausal hormone therapies are becoming increasingly complex, and it is important to evaluate their effects, including testing their relationship to eye diseases of aging," said lead author Johanna M. Seddon, director of the Epidemiology Unit at the Massachusetts Eye and Ear Infirmary and associate professor of ophthalmology at Harvard Medical School.

Hormone receptor variation linked to cancer risk

70652986 — Mon, 26 Mar 2007 05:24:34 -0400

Endometrial cancer is the fourth most common cancer in women in this country, according to National Cancer Institute statistics. Progesterone's important protective role showed up three decades ago, articulated in the unopposed estrogen theory. In the early 1970s, researchers documented that a woman on unopposed estrogen replacement therapy had a 10 times higher chance of endometrial cancer, but adding progesterone reduced the estrogen-associated risk substantially. Now Harvard researchers have found that women with a common variation in the progesterone receptor gene may have nearly double the risk of endometrial cancer. The variant was present in 15 percent of the endometrial cancer cases studied and may confer extra risk in the presence of certain environmental exposures.

Marriage lowers testosterone

70652986 — Mon, 26 Mar 2007 05:23:44 -0400

Results of a study done by a team of Harvard University anthropologists increase our knowledge of human biology -- and may have implications for so-called "male menopause." Researchers have long suspected that levels of testosterone -- the hormone largely responsible for fighting, competing, and mating -- decrease when men settle down and start a family. Other studies have shown that testosterone begins to decline shortly after marriage, but surges upward when unions end in divorce. "It makes sense," notes Peter Ellison, professor of anthropology.

Studies find milk consumption, use of HRT, and pregnancy may influence hormone levels associated with cancer risk in women

70652986 — Mon, 26 Mar 2007 05:24:49 -0400

IGF-1 is a hormone important to the growth and function of many organs. Higher levels of IGF-1 have been associated independently with an increased risk of a number of cancers, including prostate, colon, lung and breast cancer. Two studies examined the relationship between modifiable lifestyle factors and circulation levels of IGF-1 to potentially define new methods of cancer prevention. Women with four or more pregnancies had IGF-1 levels that were on average 15 percent lower than in women who had no history of pregnancy. "Our most important new finding is that there is an inverse association of circulating IGF-1 levels with increasing parity in healthy women," said researcher Michelle Holmes. "This association may define one way in which pregnancy exerts a protective influence on cancer, reducing risk in women." A second related study examined how diet affects IGF levels in well-nourished individuals. The most consistent finding was a positive association between protein with circulating IGF-1 concentrations, largely attributable to milk intake. "We concluded that greater milk consumption was associated with higher levels of IGF-1," said Holmes.

Hormone leptin tied to fat breakdown in muscle

70652986 — Mon, 26 Mar 2007 05:18:55 -0400

Research has shown that leptin is an important hormone with a hand in many metabolic processes. It undoubtedly has widespread effects that may influence diabetes as well as obesity. Recent work from Harvard researchers has tied leptin to a crucial pathway in fat metabolism in muscle. This pathway suggests a role for leptin in clearing fat out of cells and sheds light on the connection between diabetes and obesity. In the Jan. 17, 2002, issue of the journal Nature, a team led by Barbara Kahn, Harvard Medical School professor of medicine and chief of the Division of Endocrinology, Diabetes and Metabolism at Beth Israel Deaconess Medical Center, and Yasuhiko Minokoshi, visiting associate professor of medicine, established the new connection in the body's metabolic machinery.

Women's menstrual cycle holds clue to cocaine response

70652986 — Mon, 26 Mar 2007 05:14:02 -0400

During the first half of their menstrual cycles, when their estrogen levels are high, women are protected from the brain-damaging effects of cocaine use, according to a research study conducted at McLean Hospital in Belmont, Mass., by a Harvard researcher and colleagues. Researcher Marc Kaufman believes that the finding could lead to a new drug to help in treating cocaine addiction. Cocaine harms the brain by constricting blood supply. In the study, estrogen counteracted the effect of cocaine administered to the test subjects. An estrogen-like drug, therefore, would minimize the damage that cocaine abuse causes. Kaufman believes that the results could apply to drugs other than cocaine. "There are other drugs that people are using like methamphetamines and other stimulants," he said. "We don't really know what those drugs do to the brain but some of them are vasoconstrictive like cocaine. Stimulants in general have the potential for altering blood flow in the brain." The findings also could have much wider applications, such as reducing strokes.