(Press-News.org) In the largest human study to date on the topic, researchers have uncovered evidence of the possible influence of human sex hormones on the structure and function of the right ventricle (RV) of the heart.
The researchers found that in women receiving hormone therapy, higher estrogen levels were associated with higher RV ejection fraction and lower RV end-systolic volume — both measures of the RV's blood-pumping efficiency — but not in women who were not on hormone therapy, nor in men. Conversely, higher testosterone levels were associated with greater RV mass and larger volumes in men, but not in women, and DHEA, an androgen which improves survival in animal models of pulmonary hypertension, was associated with greater RV mass and volumes in women, similar to the findings with testosterone in men.
"This study highlights how little is known about the effects of sex hormones on RV function. It is critical from both research and clinical standpoints to begin to answer these questions," said Steven Kawut, M.D., M.S., senior investigator on the study, associate professor of medicine and epidemiology, and the director of the Pulmonary Vascular Disease Program at the University of Pennsylvania School of Medicine in Philadelphia.
The study was published online ahead of the print edition of the American Thoracic Society's American Journal of Respiratory and Critical Care Medicine. The research was funded by the National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health.
Study participants were part of The MESA-Right Ventricle Study (or MESA-RV), an extension of the Multi-Ethnic Study of Atherosclerosis (MESA), a large, NHLBI-supported cohort focused on finding early signs of heart, lung and blood diseases before symptoms appear. MESA recruited almost 7,000 Caucasian, African-American, Hispanic and Chinese individuals between the ages of 45 and 84 from six U.S. cities. Using blood samples and magnetic resonance imaging (MRI) of the heart, researchers measured sex hormones and RV structure and function in 1957 men and 1738 post-menopausal women. Because the MESA population is ethnically mixed and covers a broad age range of apparently healthy people, the results may be widely applicable to the general U.S. population.
"One of the most interesting things about this research is that we are focusing on individuals without clinical cardiovascular disease so that we may learn about determinants of RV morphology before there is frank RV dysfunction, which is an end-stage complication of many heart and lung diseases," said Dr. Kawut. "When we study people who already have RV failure from long-standing conditions, the horse has already left the barn. We are trying to assess markers that could one day help us identify and intervene in individuals at risk for RV dysfunction before they get really sick."
Because the RV plays a critical role in supplying blood to the lungs and the rest of the body, RV function is closely tied to clinical outcomes in many diseases where both the heart and lungs are involved, such as pulmonary hypertension, COPD and congestive heart failure. However, the RV is more difficult to study and image than the left ventricle and comparatively little is known about its structure and function and how to treat or prevent right heart failure.
"MESA-RV is, to our knowledge, the only published study of the relationship between sex hormones and the RV in humans," said Corey E. Ventetuolo, M.D., lead author of the study and an instructor of medicine at Columbia University College of Physicians and Surgeons. "Our results have generated some interesting questions about RV response to the hormonal milieu. For example, the finding that higher levels of testosterone (and DHEA) were associated with greater RV mass would first appear to have adverse clinical consequences, since increasing cardiac mass is traditionally thought to be maladaptive. However, another study from MESA-RV has shown that higher levels of physical activity are also linked to greater RV mass, which would suggest an adaptive effect. So, whether the increased RV mass seen with higher hormone levels is helpful or harmful is not yet clear. The sex-specific nature of the associations we found was unexpected and reflect the complexity of the actions of sex hormones."
Sex hormone levels could help explain a key paradox in pulmonary arterial hypertension (PAH), where the RV response is an important determinant of survival. While women are far more likely to develop PAH, they also have better RV function and may have a better survival than men. "It is possible that hormone balance could predispose them to developing PAH, but confer a protective benefit in terms of RV adaptation," explained Dr. Kawut.
"We have shown differences in RV structure that go beyond the sexes and may depend on specific hormone levels," he concluded. "We have future opportunities to pursue these findings. The MESA cohort is currently undergoing repeat MRI, a decade later. These studies could lend important insights into sex hormone-related changes in RV function over time in adults. The ultimate goal would be strategies to treat or prevent RV failure in those at high risk."
INFORMATION:
END
Long term exposure to low-level air pollution may increase the risk of severe chronic obstructive pulmonary disease (COPD), according to researcher s in Denmark. While acute exposure of several days to high level air pollution was known to be a risk factor for exacerbation in pre-existing COPD, until now there had been no studies linking long-term air pollution exposure to the development or progression of the disease.
The research was published online ahead of the print edition of the American Thoracic Society's American Journal of Respiratory and Critical Care Medicine.
"Our ...
A research team from Emory University School of Medicine investigated the role between adiponectin and leptin in obesity-related carcinogenesis. Their findings, published in the November issue of Hepatology, suggest that the protein hormone adiponectin has potential for inhibiting the oncogenic actions of leptin, namely in hepatocellular carcinoma (HCC), and could offer a promising therapy for the disease.
Obesity is on the rise and is associated with increased risk and progression of a number of cancers including colon, prostate, breast, and liver cancers. The World ...
Researchers at the University of Palermo in Italy provide the evidence that a higher visceral adiposity index score—a new index of adipose dysfunction—has a direct correlation with viral load and is independently associated with both steatosis and necroinflammatory activity in patients with genotype 1 chronic hepatitis C (G1 CHC). Details of this study are available in the November issue of Hepatology, a journal published by Wiley-Blackwell on behalf of the American Association for the Study of Liver Diseases (AASLD).
According to public health surveillance data gathered ...
Washington, DC (Oct. 19, 2010) The latest research into the health effects and safety of a soy-based compound called S-equol was described in talks and presentations by experts at a special session on Tuesday, Oct. 19 during the Ninth International Symposium on the Role of Soy in Health Promotion and Chronic Disease Prevention and Treatment, held Oct. 16 to 19 in Washington, D.C.
S-equol is a compound resulting -- when certain bacteria are present in the digestive track -- from the natural metabolism, or conversion, of daidzein, an isoflavone found in whole soybeans. ...
Analysts examining a firm and the qualifications of its top management team discount the educational background of African American managers who graduated from prestigious universities while accepting the qualifications of white managers with the same college credentials, according to two experiments reported in the current issue of Organization Science, a journal of the Institute for Operations Research and the Management Sciences (INFORMS®).
"We found that possessing high educational prestige was less beneficial for firms led by African Americans than for firms with ...
CINCINNATI - A newly identified regulatory process affecting the biology of immune system T cells should give scientists new approaches to explore the causes of autoimmunity and immune deficiency diseases.
In findings posted online ahead of publication in Proceedings of the National Academy of Sciences (PNAS), scientists at Cincinnati Children's Hospital Medical Center report a novel process of coordinated cellular communications vital to the maintenance of T cells. If the process breaks down, T cells proliferate rapidly and die off. This could disrupt the immune system's ...
In the United States, friends often share intimate details of their lives and problems. However, such self-disclosure is much less common in Japan. A new study by an American researcher living in Japan finds that this may be because of the different social systems in the two countries, and in particular the extent to which there are opportunities to make new friends.
"At first, it seemed strange that in Japan, people didn't open up and share a lot about themselves with each other," says Joanna Schug of Hokkaido University. "But Japanese often look at Americans and think, ...
TORONTO, October 19, 2010 – Pharmaceutical promotion may cause doctors to prescribe more expensively, less appropriately and more often, according to a new study co-authored by York University professor Joel Lexchin.
The findings, published today in the journal, PLoS Medicine, offer a broad look at the relationship between doctors' prescribing habits and their exposure to information provided by drug companies. Researchers analyzed 58 separate studies of this phenomenon from Canada, the United States, Europe and Australia, dating from the 1960s.
"Many doctors claim ...
An international collaboration led by academics at the University of Sheffield, has shed new light into Parkinson's disease, which could help with the development of cures or treatments in the future.
The collaboration, which was led by Professor Peter Redgrave from the University's Department of Psychology, suggests that many of the problems suffered by patients with Parkinson's disease - difficulties in initiating actions, slow laboured movements and tremors – can be understood in terms of damage to control circuits in the brain responsible for habits.
The analysis, ...
Mobile phone-based games could provide a new way to teach basic knowledge of Chinese language characters that might be particularly helpful in underdeveloped rural areas of China, say researchers in Carnegie Mellon University's Mobile & Immersive Learning for Literacy in Emerging Economies (MILLEE) Project.
Earlier this year, researchers reported that two mobile learning games, inspired by traditional Chinese games, showed promise during preliminary tests with children in Xin'an, an underdeveloped region in Henan Province, China. The researchers from Carnegie Mellon, ...
