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PregnantPuertoRicansFearfulofZika

March 14, 2016 -- Ask pregnant women in Puerto Rico if they want a boy or a girl and you’ll get an age-old answer: They don’t care, as long as the baby is healthy.

But that statement carries new meaning in Puerto Rico these days. The news that Zika virus is being spread by the mosquitos here and infecting islanders -- including, at last count, 21 pregnant women --means the health of these women’s unborn children could be stolen at any time with one bite from a pest that’s lurking in their homes.

Some expectant moms have left the island rather than live with the threat.

Amanda Vaccaro, 27, left in February, when she was just a month away from her due date. She moved back to Ohio to live with her parents until after the baby, a girl she will name Grace, is born.

Her husband is in the Coast Guard and is stationed in Puerto Rico. He is still there as she plods through the last and most difficult weeks of her pregnancy.

“We couldn’t live with ourselves if something happened by me staying there,” she says.

Doctors believe that Zika infections may do the greatest damage during the early weeks of pregnancy, when a baby’s organs are still forming. Vaccaro was already in her third trimester when she decided to leave.

When she talked to her doctor about the risks, “He couldn’t really tell me yes or no because they don’t really have too much information on the virus.”

Because many people who get Zika won’t have symptoms, Vaccaro also took a blood test before she left to find out if she’s been exposed to the virus. She still doesn’t know the results.

She says several other Coast Guard moms have also decided to leave.

It wasn’t what she wanted.

“I didn’t want to be away from [my husband], so that was hard. We liked our doctor. Our nursery was there. Our home was there. It was really hard to decide,” she says.

日期:2016年3月15日 - 来自[Health News]栏目
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‘Sterile‘UrineMayBeaMyth

By Robert Preidt

HealthDay Reporter

MONDAY, May 19, 2014 (HealthDay News) -- Many people have heard that human urine is devoid of germs, but a new study seems to question that idea.

"Doctors have been trained to believe that urine is germ-free," Dr. Linda Brubaker, dean of Loyola University Chicago Stritch School of Medicine, said in a university news release. "These findings challenge this notion."

Brubaker's team analyzed urine samples from 90 women. It found bacteria both in the urine of healthy women as well as the urine of women with overactive bladder. However, the germs were different between the two groups, the researchers said.

"The presence of certain bacteria in women with overactive bladder may contribute to overactive bladder symptoms," lead investigator Evann Hilt, a second-year master's student, theorized in the news release. But only more study can confirm whether those bacterial differences are "clinically relevant for the millions of women with overactive bladder," Hilt added.

About 15 percent of women have overactive bladder, which triggers a sudden need to urinate. Forty percent to 50 percent of these women do not respond to medication. Brubaker's team believes differences in bladder bacteria may be why some women respond to drug therapy while others don't.

The study was presented Sunday in Boston at the annual meeting of the American Society for Microbiology. Findings presented at medical meetings are typically considered preliminary until published in a peer-reviewed journal.

"If we can determine that certain bacteria cause overactive bladder symptoms, we may be able to better identify those at risk for this condition and more effectively treat them," co-investigator Alan Wolfe, professor of microbiology and immunology, said in the news release.

The next steps for the Loyola team will be to determine which bladder bacteria are helpful and which are harmful, how these bacteria interact with each other and their host, and how this new knowledge can help patients.

日期:2014年5月21日 - 来自[Health News]栏目

Fitness411

By Steven Reinberg

HealthDay Reporter

THURSDAY, March 27, 2014 (HealthDay News) -- The formula doctors use to evaluate treadmill stress tests, and thereby assess heart health, doesn't account for important differences between men and women, a new study contends.

A revised formula would better determine peak exercise rate, or the maximum number of heart beats per minute, for each sex, the researchers said.

"Exercise physiology has been known to differ for men and women of different ages," said Dr. Gregg Fonarow, associate chief of cardiology at the University of California, Los Angeles, and spokesman for the American Heart Association.

The proposal for a sex-specific maximal heart rate warrants further research, he said. "This may represent a valuable improvement for guiding exercise stress testing," added Fonarow, who was not involved in the study.

Doctors now use the formula "220 minus age" to determine how hard patients should work out during exercise stress tests. Many people also use this formula to set their target heart rate during workouts.

For the new study, a team led by Dr. Thomas Allison, director of stress testing at the Mayo Clinic in Rochester, Minn., reviewed 25,000 stress-test results. They saw significant differences between men and women.

Allison's group found that although peak heart rate declines with age for both sexes, the rate declines more gradually in women. This difference results in an overestimated peak heart rate in younger women and underestimated peak heart rate in older women, the researchers said.

The findings are scheduled for presentation Saturday at the annual meeting of the American College of Cardiology, in Washington, D.C.

Based on their findings, the study authors developed a new formula.

According to the revised formula, the maximum heart rate for women aged 40 to 89 should be 200 minus 67 percent of their age. For men, the preferred formula is 216 minus 93 percent of their age, the study authors said.

"We want to make sure that when people do the stress test, they have an accurate expectation of what a normal peak heart rate is," Allison said in an American College of Cardiology news release.

Because of limited test results for women under 40, the researchers were unable to recommend a new formula for this group.

Allison's team also found that younger men have a lower resting heart rate and higher peak heart rate than women. In addition, men's heart rates rise more dramatically during exercise and return to normal more quickly after stopping, the researchers said.

Heart experts welcomed the preliminary results.

"This is timely and we've needed it for a while," said Dr. Suzanne Steinbaum, director of women and heart disease at Lenox Hill Hospital in New York City.

"All of these differences are very important, not only for diagnosis, but also for teaching people how best to exercise to get the most cardiovascular fitness," she said.

日期:2014年3月28日 - 来自[Health News]栏目
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Multiple Egg Donations Women‘s Future Fertility

By Mary Elizabeth Dallas

HealthDay Reporter

WEDNESDAY, Oct. 16 (HealthDay News) -- Undergoing multiple egg donations does not have a negative effect on women's future fertility, according to a preliminary new study.

This was the case even when subsequent egg-donation cycles required significantly more gonadotropin -- a drug used to stimulate ovulation -- according to researchers from Weill Cornell Medical College, in New York City.

The study involved women who completed at least five egg-donation cycles between January 2004 and April 2012. On average, the women were 26.4 years old at the time of their first egg donation. By the time of their fifth cycle, the average age of the women was 28.7 years.

In conducting the study, the researchers examined the women's anti-Mullerian hormone levels (used to measure women's response to fertility treatments), the amount of hormonal medication they received and how long they took it. They also examined how many eggs were retrieved during each egg-donation cycle.

The study revealed that, over multiple cycles, the average length of time required for stimulation ranged from 9.4 days to 10 days and the average number of eggs retrieved ranged from about 21 to 24.

"This retrospective study is reassuring in that egg donors who undergo up to six cycles do not have evidence of depleting their ovarian reserve, which bodes well for their future fertility," Dr. Linda Giudice, president of the American Society for Reproductive Medicine, said in a society news release.

On the receiving end, a separate study revealed that people who need donated eggs to conceive a child may benefit from using frozen eggs. Researchers at Seattle Reproductive Medicine found that using frozen eggs may be about as efficient as fresh eggs, as well as more cost effective.

For this study, the researchers compared the outcomes of 113 fresh donor egg in vitro fertilization (IVF) cycles with 77 frozen cycles that took place between March 2012 and February 2013.

Although pregnancy rates were 60 percent for fresh cycles and 57 percent for frozen cycles, the study revealed that patients using frozen eggs waited a shorter time from the initial medical consult to the start of a cycle: 217 days for fresh eggs, compared with 172 days for frozen eggs.

Frozen eggs also had much lower patient cancellation rates at 1.2 percent, compared with 12 percent for patients who'd planned to undergo fresh cycles.

Recipients who used frozen eggs also had lower costs: $17,500 per transfer for frozen eggs and an average of more than $30,500 for each pregnancy. For those using fresh eggs, however, the cost per transfer was nearly $30,000 with an average cost per pregnancy of more than $49,500.

During the last six months of the study, 61 percent of all donor egg cycles involved frozen eggs, according to the news release.

"Frozen egg banking is a promising development for patients and donors alike," Giudice said. "Because the costs are lower and a shorter waiting time is involved, more patients are likely to find frozen donor eggs a very appealing alternative to fresh donor eggs."

The studies' findings were expected to be presented Wednesday at the joint meeting of the International Federation of Fertility Societies and the American Society for Reproductive Medicine, held in Boston. Data and conclusions should be viewed as preliminary until published in a peer-reviewed journal.

日期:2013年10月21日 - 来自[Health News]栏目

Testosterone supplementation in aging men and women: possible impact on cardiovascular-renal disease

【关键词】  Testosterone

    Department of Physiology and Biophysics and The Center for Excellence for Cardiovascular-Renal Research, University of Mississippi Medical Center, Jackson, Mississippi

    ABSTRACT

    Treatment of aging men and women with testosterone supplements is increasing. The supplements are given to postmenopausal women mainly to improve their libido and to aging men to improve muscle mass and bone strength, to improve libido and quality of life, to prevent and treat osteoporosis, and, with the phosphodiesterase-5 inhibitors, such as sildenafil, to treat erectile dysfunction. The increased use of testosterone supplements in aging individuals has occurred despite the fact that there have been no rigorous clinical trials examining the effects of chronic testosterone on the cardiovascular-renal disease risk. Studies in humans and animals have suggested that androgens can increase blood pressure and compromise renal function. Androgens have been shown to increase tubular sodium and water reabsorption and activate various vasoconstrictor systems in the kidney, such as the renin-angiotensin system and endothelin. There is also evidence that androgens may increase oxidative stress. Furthermore, the kidney contains the enzymes necessary to produce androgens de novo. This review presents an overview of the data from human and animal studies in which the role of androgens in promoting renal and cardiovascular diseases has been investigated.

    androgen receptor; oxidative stress; angiotensin II; endothelin; cytokines

    THE USE OF TESTOSTERONE SUPPLEMENTS in aging men and women has increased in recent years. Aging men take testosterone supplements to improve muscle mass and bone strength, to improve libido and quality of life, to prevent and treat osteoporosis, and, with the phosphodiesterase-5 inhibitors, to treat erectile dysfunction. Postmenopausal women receive testosterone supplements mainly to improve their libido. In addition to physicians prescribing testosterone supplements, individuals are able to buy androgens, such as androstenedione, over the counter in health food stores. Serum testosterone levels that are achieved with supplements range from physiological to supraphysiological levels (sometimes as high as 3- to 16-fold higher in men and women than physiological levels) depending on the preparation, dose, and method of administration (9, 13, 42). While urologists are sounding the alarm for caution in using testosterone supplements because of their potential to increase the incidence of prostatic cancer (75), there have been few clinical trials to study the safety of testosterone supplements in aging men and/or women in terms of their effect on cardiovascular-renal disease. Earlier this year, the Food and Drug Administration refused to approve the testosterone "patch" for use in postmenopausal women, however, due to the possibility of cardiovascular side effects (79). In this review, research regarding the impact of androgens on cardiovascular and renal disease from human and animal studies will be discussed.

    CHANGES IN TESTOSTERONE WITH AGE

    Several cross-sectional (20, 83) and longitudinal (19, 28) studies documented a decline in total and bioavailable circulating testosterone levels with aging in men. More than 60% of healthy, elderly men over 65 yr of age have free testosterone levels below the normal values of men aged 3035 yr. Because androgen receptors are upregulated in the presence of androgens and downregulated in its absence, it is likely that a reduction in androgen receptors may occur with aging as well. There have been studies in which the expression of androgen receptors in aging men was reduced in reproductive tissues, but there have been no studies in which the expression of androgen receptors has been studied in nonreproductive tissues in aging individuals. The decrease in androgen levels with aging in men appears to be the result of both gonadal and hypothalamic-pituitary failure and is independent of chronic illness, obesity, or medication (28). However, chronic illnesses (52), such as hypertension (81), diabetes (10), chronic kidney disease (33, 74), and end-stage renal disease (38, 39), are associated with a further reduction in serum testosterone levels in men of all ages. The fact that androgen levels decrease with age have led scientists to presume that androgens do not play a role in chronic cardiovascular and renal disease in aging men. However, growing evidence indicates that testosterone, even at levels observed in aging men, can have adverse consequences on cardiovascular-renal function.

    Serum testosterone levels are significantly lower in women than in men, and whether serum testosterone levels decrease after menopause is not clear. The conventional wisdom is that androgen levels, like estrogen, do decrease with age in women. However, Jiroutek and colleagues (37) reported that postmenopausal women who were followed for 10 yr after cessation of cycling and had serial measurements of sex hormones showed increases in serum testosterone and androstenedione and decreases in serum estradiol and dihydrotestosterone as they aged. Other investigators have observed that serum testosterone either does not change (30) or is decreased in postmenopausal women (57). In cross-sectional studies of women in the Rancho Bernardo cohort, Laughlin and colleagues (45) reported that serum testosterone decreased immediately following menopause, but thereafter increased with age, reaching premenopausal levels by 7079 yr. In addition, these investigators found that women who had undergone surgical menopause did not show increases in testosterone with age and the levels of serum testosterone were 4050% lower than in women who had undergone natural menopause. These data support the contention that the natural postmenopausal period in a woman's life is a relatively hyperandrogenic state (2, 44, 60). Furthermore, Sluijmer and colleagues (77) found that the degree of ovarian stromal hyperplasia, a common characteristic of the ovaries in postmenopausal women, is not correlated with the level of estrone and estradiol measured in the ovarian vein but is positively correlated with the level of testosterone and androstenedione. For example, women with atrophic ovaries had little testosterone measured in the ovarian vein, whereas women with moderate to severe hyperplasia had larger levels of ovarian testosterone produced. In addition, the incidence and degree of stromal hyperplasia were quite variable among the women (77). Because the extent of ovarian stromal hyperplasia is rarely measured in most studies of postmenopausal women, this could explain the discrepancies in androgen levels found in various studies.

    ANDROGENS AND CONTROL OF BLOOD PRESSURE

    There is growing evidence that androgens can influence blood pressure regulation. Men have higher blood pressure than do women for most of their lives (41, 86). Following menopause, however, blood pressure increases in women to levels not different or even higher than in men (7). The prevalence of hypertension is also higher in men than women until after menopause (7). However, hypertensive men have been shown to have lower serum testosterone levels than normotensive men of the same age (81). These data have called into question the role that androgens could play in mediating or promoting hypertension.

    Although there have been few studies in men in which the role of androgens in mediating higher blood pressure has been examined, there are several animal models in which a sex difference in blood pressure has been described and the role of androgens has been studied. For example, the spontaneously hypertensive rat (SHR) is a model of hypertension that is androgen mediated (62, 68). Following puberty, males have higher blood pressure than females (68) (see Fig. 1). Castration of males is associated with reductions in blood pressure to the levels found in females. Furthermore, testosterone treatment of ovariectomized females increases their blood pressure in a dose-dependent manner (68, 69). Sex differences in blood pressure have also been found in Dahl salt-sensitive (DS) rats on a high-salt diet (32). The DS males have higher blood pressure than females when placed on 4% salt diets despite the fact that high-salt diet for 3 wk reduces serum testosterone levels in the males by 50% (n = 5/group) (Yanes LL, Iliescu R, and Reckelhoff JF, unpublished observations). Early studies failed to show a reduction in blood pressure with castration in the male DS on a high-salt diet (73). However, as shown in Fig. 2, we have found that castration attenuates the hypertensive response to high salt in male DS. These data support the contention that despite reductions in serum testosterone in DS males with high salt, there is still enough androgen present to play a role in mediating the salt-induced hypertension. It should be noted, however, that testosterone replacement studies have not been performed yet. Thus it is possible that other factors may play a role in the lower blood pressure with castration, although we doubt this will be the case. Nongenetic models of hypertension also exhibit sex differences, such as DOCA-salt-treated rats, in which the hypertension is more severe in males than females (11), but to our knowledge, serum testosterone levels have not been reported for rats receiving DOCA and salt.

    ANDROGENS AND RENAL DISEASE

    Androgens in the Kidney

    To date, there is a paucity of data regarding the role of androgens and the androgen receptor in regulating renal function. However, the kidney expresses the enzymes capable of producing testosterone and the androgen receptor. For example, Quinkler and colleagues (60) found that kidney tissue obtained from tumor nephrectomy samples from postmenopausal women express 5-reductase type 1, 3-hydroxysteroid dehydrogenase type 2, and 17-hydroxylase/17,20 lyase (P450c17) (see Fig. 3). They also found that radiolabeled pregnenolone, produced from cholesterol, was converted effectively to dehydroepiandrosterone (DHEA), and radiolabeled DHEA was converted via androstenedione to testosterone and dihydrotestosterone. Whether androgens can be produced in kidneys of men via these enzymes was not determined in these studies but is highly likely. In support of this hypothesis, in male rats, treatment of inner medullary collecting duct primary cultures with radiolabeled testosterone or androstenedione resulted in production of 5-dihydrotestosterone and 5-androstanedione (47). Androgen receptor expression has been found in the proximal tubule and in the cortical collecting ducts of human kidneys (43).

    Androgens and Proximal Tubule Reabsorption

    One of the most important recent findings regarding the effect of androgens in the kidney is the work of Quan and colleagues (59), who found by micropuncture studies that chronic (10 days) dihydrotestosterone (DHT) injections in Sprague-Dawley rats caused an increase in the proximal tubule volume reabsorption, which could be reduced with blockade of the renin-angiotensin system (RAS). Blood pressure was higher in the DHT-treated rats, but the glomerular filtration rate (GFR) was not affected nor was AT1 receptor binding. This is in contrast to acute infusion of testosterone, which causes renal vasodilation with increases in GFR and renal plasma flow and reductions in renal vascular resistance (Reckelhoff JF, unpublished observations). The data of Quan and colleagues (59) suggest that, in the chronic situation, androgens may upregulate ANG II and the Na/H exchanger, leading to increases in sodium and water reabsorption and elevations in blood pressure.

    Androgens and Chronic Renal Disease

    As in other chronic diseases, serum androgen levels are decreased in men with renal insufficiency (33, 74). Despite the reduction in androgens that occurs with aging, men progress to chronic renal failure at a more rapid rate than do women, even for similar levels of blood pressure (53). For example, Neugarten and colleagues (53) performed a meta-analysis of studies including 11,345 subjects and found that renal disease independent of diabetes progresses at a more rapid rate in men. Several renal diseases are also more common in men than women. Polycystic kidney disease (24, 80) and IgA nephropathy (27) are more common in men and progress more rapidly in men than women. Age-related reductions in renal function also progress at a more rapid rate in men than women (76). Despite the gender differences in the progression of chronic renal disease, Neugarten and colleagues (54) reported that there are few sex differences in normal renal structure that could account for these observations. For example, glomerular number was similar in men and women, and the glomerular volume and kidney weight were similar when corrected for body weight of the individuals.

    In aging rats, serum testosterone levels also decrease with age as found in men. Several investigators have reported that normotensive and hypertensive males experience a more rapid reduction in GFR and more renal injury with age than do females (6, 22, 6466, 68). However, the reduction in GFR cannot be fully accounted for by the level of glomerular injury found in the kidneys (22, 68). For example, in old male Sprague-Dawley rats aged 2022 mo, a model of accelerated renal aging, GFR was reduced by 50% compared with young males and yet only 20% of their glomeruli exhibited any injury (68). These data suggest that aging is a state of renal vasoconstriction. We have made similar findings in the aging SHR. In old male SHR, renal vascular resistance was increased by 30%, whereas blood pressure was only increased by 10% compared with young SHR (22). As in normotensive rats, the reductions in GFR in old male SHR cannot be explained by glomerular injury because <10% of glomeruli are injured in these rats at 18 mo of age, whereas GFR was reduced by 30% (22). In more recent studies in SHR, we found that castration of aging males completely prevents reductions in GFR and glomerular injury (22). In addition, castration prevents the increase in renal vascular resistance found in aging male SHR despite a significant age-related reduction in serum androgens in the intact male. Taken together, these data suggest that remnant androgens mediate the reductions in renal function in the aging animal.

    In another model of hypertension and renal injury that is not genetically mediated, the renal wrap hypertension model, Ji and colleagues (36) recently reported that castration of male rats attenuated the glomerular injury and proteinuria. When castrated rats were treated with DHT, the glomerular injury was exacerbated. Similarly, in renal wrap female rats that were ovariectomized (a model of ovarian hormone deficiency), testosterone treatment also exacerbated renal injury and proteinuria. Thus there is compelling evidence that indicates that testosterone promotes renal injury and declines in renal function.

    Androgens and the RAS in the Kidney

    Androgens play a role in modulating the RAS. Several groups have shown that androgens can stimulate the upregulation of angiotensinogen in the kidneys of normotensive and hypertensive rats (8, 18). In addition, Chen and colleagues (8) reported that renin mRNA was upregulated by androgens in kidneys of SHR. These data suggest that androgens can stimulate the intrarenal RAS. Furthermore, Baltatu and colleagues (4) also reported that renal injury could be abolished by androgen receptor antagonism in a Ren-2 rat model of hypertension that has an overactive RAS.

    How androgens affect the systemic RAS is not clear. In humans, plasma renin activity (PRA) is higher in men than in age-matched premenopausal women (35, 58). We have found previously that testosterone repletion in castrated normotensive rats leads to a dose-dependent increase in PRA (62), which is consistent with the data from human studies. In contrast, Quan et al. (59) found that chronic DHT treatment reduced serum ANG II levels. While estradiol has been shown to modulate the synthesis of AT1 receptors in various tissues, including kidneys and vasculature (29, 55), androgens have only been shown to increase AT1 receptor expression in male reproductive tissues (46). Therefore, the effect of androgens on AT1 receptor expression in kidneys should be examined.

    There are gender differences in the renal response to infusion of ANG II as well. When graded doses of ANG II were infused into healthy young adults, there was a similar increase in blood pressure and reduction in effective renal plasma flow (ERPF) in men and women, but GFR was maintained in men only, leading to an increase in the filtration fraction (FF), which suggests an increase in glomerular capillary pressure (48). In women, the reduction in ERPF was associated with a concomitant reduction in GFR, resulting in no change in FF. These studies were performed without blockade of the endogenous RAS. Therefore, men may have been more responsive because they have higher basal levels of endogenous renal ANG II than women. In any case, these data further support the notion that the combination of androgens and ANG II is important in modulating renal function.

    In SHR, blockade of the RAS with converting enzyme inhibitors (CEI) reduces blood pressure to the same level in both males and females (70), supporting the important role of the RAS in mediating the hypertension in SHR independently of the sex steroids. In addition, CEI also prevents increases in blood pressure in ovariectomized female SHR receiving chronic testosterone supplementation (70). These data suggest that an intact RAS is necessary for androgens to increase blood pressure in SHR. In other words, the mechanism by which androgens are capable of increasing blood pressure in SHR is mediated by their effects on the RAS.

    Whether PRA and RAS activity decrease with age in men and women is somewhat controversial. However, James and colleagues (35) reported from serial analyses that PRA was higher in men than in age-matched women, that PRA was higher in postmenopausal women than in premenopausal ones, and that in white men, PRA did not decrease with age. Blood pressure becomes more salt sensitive with aging in both men and women (85), which suggests that RAS activity and ANG II do not respond appropriately in the presence of salt in aging individuals. Therefore, androgen supplements in aging individuals could be expected to both stimulate reabsorption in the proximal tubule and stimulate PRA, which would further aggravate hypertension and renal injury.

    Androgens and Endothelin

    Endothelin is a potent renal vasoconstrictor and mitogen that plays a role in renal injury associated with aging (5, 25, 26). Goddard and colleagues (26) reported that ETA receptor antagonism in individuals with chronic renal failure caused an increase in renal blood flow and a reduction in blood pressure mainly due to the activation of the ETB receptors, because combined ETA/B receptor antagonism reduced blood pressure but had no effect on renal function. In addition, Elijovich and colleagues (17) reported that hypertensive individuals with nephrosclerosis exhibited increased plasma endothelin that was independent of aldosterone:renin ratios but was positively correlated with the level of proteinuria. In aging male Wistar rats, Ortmann and colleagues (56) recently reported that glomerulosclerosis and proteinuria could be reversed when rats were given darusentan, an ETA receptor antagonist, independently of reductions in blood pressure, changes in renal function, or tubulointerstitial renal injury. In addition, endothelin-1 is secreted from mesangial cells in response to a variety of cytokines, hormones, and oxidative stress (78). There is also evidence that endothelin may play a role in the gender difference in the death rate of rats in response to renal ischemia-reperfusion (51). Muller and colleagues (51) found that 50 min of left vascular pedicle clamping resulted in death in 92% of male rats by day 7, but only 25% of females died during this time period. Castration reduced the number of deaths in males with ischemia-reperfusion to 33%, and pretreatment of males with an endothelin ETA receptor antagonist totally protected males from death (51).

    Androgens can upregulate the production of endothelin. In female-to-male transsexuals who receive testosterone supplements chronically, plasma endothelin levels are elevated (82). In addition, in women who suffer from polycystic ovary syndrome, in which serum testosterone is elevated, endothelin is also elevated (15). Whether the effects of androgens on endothelin production are direct or mediated by the effects of androgens on the RAS, which, in turn, increases endothelin production (3), is not clear. In any case, androgen supplementation in both aging men and women could promote renal injury mediated via endothelin. This is especially important following menopause, because estradiol has been shown to reduce expression of endothelin (82), and thus this protection would be lost in postmenopausal women. In support of this hypothesis, we have found that the postmenopausal increases in blood pressure found in aging female SHR are mediated, in part, by endothelin (87). In contrast, endothelin plays no role in the hypertension of young female SHR (87).

    Androgens and Oxidative Stress

    The role of oxidative stress in acute renal failure and ischemia-reperfusion is widely accepted. However, oxidative stress also plays a role in chronic renal disease (1, 49). Men have higher levels of oxidative stress than do age-matched women as measured by F2-isoprostanes or thiobarbituric acid-reactive substances in plasma (34), despite the reduction in androgen levels in aging men. Postmenopausal women also exhibit higher levels of oxidative stress than premenopausal women (31). Oxidative stress is increased in the kidney with normal aging (72), and we have been able to protect against age-related renal injury in Sprague-Dawley rats by treating them chronically with vitamin E (65).

    The major reactive oxygen species in the kidney is thought to be superoxide, which can quench nitric oxide (NO) (67), leading to a reduction in the NO bioavailability for dilation and thereby causing renal vasoconstriction. It is possible then that a reduction in vasodilator substances could play a role in the age-related renal vasoconstriction in males. We have found previously that there are sex differences in the renal vasculature response to NO. Young male normotensive rats without deficiencies in androgen synthesis are more dependent on the NO system for maintenance of renal hemodynamics than are age-matched females (63). Males had 80% lower renal expression of endothelial NO synthase compared with females, yet when NO synthase was blocked with nitro-L-arginine methyl ester, despite similar blood pressure increases in males and females, renal plasma flow (RPF) decreased by 40% and renal vascular resistance (RVR) increased by 23% in males compared with 20% and 60% for RPF and RVR, respectively, in females. The importance of the NO system in preserving renal hemodynamics is even more striking in aging males. When treated with NO synthase inhibitors, GFR and RPF decreased to a much greater extent and glomerular capillary pressure almost doubled in aging males compared with young males (66).

    Whether androgens can directly produce oxidative stress has not been fully elucidated. In preliminary studies, we have found that physiological concentrations of dihydrotestosterone are capable of increasing dihydroethidium fluorescence in cultured SHR mesangial cells (Cucchiarelli V, Iliescu R, and Reckelhoff JF, unpublished observations). We have also found that castration reduces superoxide production in the kidneys of male SHR. In addition, tempol, a superoxide scavenger, reduces blood pressure and oxidative stress in young and aging male SHR but has little or no effect in females (21, 23).

    Regardless of whether androgen supplementation directly causes oxidative stress, androgens can stimulate the RAS and endothelin production, which have been shown to increase reactive oxygen species. ANG II, at both supraphysiological and physiological levels, can increase oxidative stress (61, 71), mainly via upregulation of the subunits of NADPH oxidase (50). In addition, ANG II can stimulate the production of endothelin (3), which also causes oxidative stress by upregulating NADPH oxidase (16). Furthermore, while endothelin can cause oxidative stress, oxidative stress can also upregulate endothelin synthesis (40), setting up a vicious cycle.

    Therefore, because aging is associated with increased oxidative stress, men at all ages have elevated levels of oxidative stress compared with women, and after menopause oxidative stress increases in women, androgen supplements could cause a further increase in oxidative stress in both men and women, leading to reductions in renal function and renal injury. The renal changes could be caused by the direct effect of androgens on oxidative stress or indirectly via their effect on the RAS or endothelin system. Furthermore, because estradiol is a mild antioxidant and has been shown to inhibit synthesis of NADPH oxidase (84), postmenopausal women would be at increased risk for androgen supplement-induced oxidative stress.

    Androgens and Cytokines

    Aging renal disease is associated with increases in inflammation and cytokine release. Both TNF- and IL-6 have been shown to upregulate or activate the androgen receptor (12, 14). In addition, upregulation of many inflammatory mediators involve the transcription factor, NF-B, and the androgen receptor promoter contains several NF-B enhancer elements. Although the role of the androgen receptor in the inflammation associated with aging renal disease has not been studied, it is attractive to propose that the androgen receptor could be upregulated in renal tissue in response to inflammation. Androgens have also been shown to activate a Fas/Fas ligand-dependent apoptotic pathway in proximal tubule cells, which is characteristic of chronic renal diseases (24). Androgens could, therefore, activate an apoptotic mechanism, leading to renal tubular loss and interstitial fibrosis in the elderly.

    SUMMARY

    Aging men and women frequently receive androgen supplements. Aging men are already at greater risk for cardiovascular and renal disease than women, despite the fact that serum testosterone levels decrease significantly with age and with chronic diseases. We hypothesize that the reduction in testosterone with age and chronic disease is a protective mechanism against even greater cardiovascular-renal disease incidence and poorer outcomes. Therefore, androgen supplements in aging men could offset this natural protective mechanism.

    In women, menopause increases a woman's risk for cardiovascular and renal diseases. However, women are somewhat protected compared with men, but androgen supplements may increase the risk of renal injury and cardiovascular disease in postmenopausal women to levels similar to those in men. It is also possible that androgen levels may increase naturally with age in some women and may further impact disease risk factors naturally.

    As with estradiol-progesterone replacement therapy in postmenopausal women, it is likely that some healthy, active, aging men and women would not have adverse cardiovascular consequences with androgen supplementation. However, in view of the increasing experimental evidence that androgens promote cardiovascular and renal disease, even when the serum levels are decreased, aging men and women who have the predisposition to cardiovascular-renal diseases should take androgen supplements with caution until rigorous clinical trials have been performed.

    As shown in Fig. 4, we hypothesize that androgens can stimulate proximal reabsorption of sodium and water, causing a reduction in the sodium delivery to the macula densa, and, by tubuloglomerular feedback, cause a reduction in afferent resistance that could lead to an increase in glomerular capillary pressure. Androgens could also activate the RAS, leading to further increases in tubular sodium reabsorption, but also increases in efferent resistance and glomerular capillary pressure. ANG II has been shown to increase endothelin synthesis and upregulate NADPH oxidase to increase oxidative stress. Endothelin has also been shown to increase oxidative stress. Furthermore, androgens may directly increase both endothelin and oxidative stress. ANG II, endothelin, and oxidative stress can then increase blood pressure, leading to further increases in glomerular pressure, ultimately leading to glomerular injury and loss of renal function.

    GRANTS

    This work was supported by National Heart, Lung, and Blood Institute Grants HL-66072, HL-69194, and HL-05197.

    FOOTNOTES

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日期:2013年9月26日 - 来自[2005年第288卷第11期]栏目
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More Than a Third of Babies Unintended

July 24, 2012 -- More than one-third of births in the U.S. are the result of an unplanned pregnancy, according to a CDC study.

Despite a decrease in unplanned pregnancies among white women, researchers say the number of unintended births has remained steady at about 37% of all births since 1982.

"The growing proportion of births to unmarried women, most of which were unintended, has kept the overall proportion of unintended births approximately constant," write researcher William Mosher, PhD, of the National Center for Health Statistics at the CDC, and colleagues.

The study is published in the National Health Statistics Reports. It shows that unmarried women accounted for 41% of all births in 2009, up from 18% in 1980.

Researchers say major differences also persist in the number of unplanned pregnancies according to:

  • age
  • race
  • income
  • education

"Unintended births occur disproportionately among non-Hispanic black women, unmarried women, and women with less income and education," they write. "For example, the proportion of all births that were unwanted or mistimed by two years or more was 7% for college graduates compared with 35% for women who did not complete high school."

Slideshow: Birth Control Options?

Unplanned Pregnancy Statistics

The study shows that never-married women and Hispanic women now account for a growing number of births.

Researchers say the percentage of births that were intended among white women who had ever been married has increased during recent years. But these women now represent a much smaller share of overall births. In 1981, they accounted for 66% of all births. But in 2006-2010, this number decreased to 43%.

The study also showed that 60% of women who experienced an unplanned pregnancy in 1998-2002 were not using contraception.

More than a third of those who did not use contraception (36%) said they did not think they could get pregnant.

"Underestimating the risk of pregnancy is the most common reason for not using contraception that leads to unintended pregnancy," the researchers write. "There was no significant variation in the percentage of women who gave this reason by age, marital status, or income. However, Hispanic women were more likely than others to say they did not think they could get pregnant (49%, compared with 35% of white women and 25% of black women)."

Researchers say the most recent unplanned pregnancy statistics from 2006-2010 highlight persistent differences according to the mother's age, ethnicity, and marital status.

During this period:

  • Nearly 4 out of 5 teen births were the result of an unplanned pregnancy.
  • Half of births to women aged 20-24 were intended, compared with 75% of births among women aged 25-44.
  • About 77% of births to women who were married at the time of birth were intended, compared with 49% of births to women who were living with their partner and 33% of births among single women.
  • More than two-thirds of births to white women were intended, compared with 57% among Hispanic women and 47% among African-American women.
日期:2012年11月10日 - 来自[Pregnancy]栏目

Hip Resurfacing ‘Unacceptable for Women‘: Study

Oct. 4, 2012 – An operation known as hip resurfacing -- an alternative to hip replacement often recommended for younger patients -- is prone to frequent failure and should not be used in women, a new study shows.

Researchers looked at data from 434,650 operations carried out in England and Wales between 2003 and 2011, of which 31,932 (7.4%) were resurfacings.

Metal Cap

Hip resurfacing is similar to hip replacement. In a replacement operation, though, the rounded top section of the thigh bone, known as the femoral head, is completely removed and replaced. During resurfacing surgery, the femoral head is ground down to an even surface and given a metal cap.

Hip resurfacings always have metal-on-metal bearings, while total hip replacements can have a variety of bearing options, such as ceramic, metal, or plastic.?

Researchers from the University of Bristol looked at the failure rate of resurfacing implants since the United Kingdom's National Joint Registry was set up in 2003. They used data from the next seven years to compare them with total hip replacements.

Seven-Year Failure Rate

They found that the predicted seven-year failure rate for a 55-year-old woman who had undergone hip resurfacing ranged from 8.54% to 11.67%. This failure rate was dependent on the size of the femoral head, with the smallest sizes more prone to early failure.

These failure rates were much higher than full replacements with a metal ball and a polyethylene socket, where the failure rate was between 1.81% and 2.25% over seven years.

Men also experienced higher failure rates with resurfacing surgery compared to total replacement.?

The findings appear in the online edition of The Lancet.

Unacceptable for Women, Researcher Says

Ashley Blom, MD, PhD, is a professor of orthopaedic surgery in the University of Bristol’s School of Clinical Sciences, and one of the paper's authors. "Resurfacing failure rates in women were unacceptably high. In view of these findings, we recommend that resurfacing procedures are not undertaken in women," she says.

Furthermore, "the National Joint Registry for England and Wales has the biggest joint replacement database in the world, allowing us to analyze over 30,000 hip resurfacings up to seven years after surgery. Our findings show that resurfacings with smaller head sizes are prone to early failure, and in particular that resurfacing in women has much worse implant survival, irrespective of head size," she says.

The researchers also write that their findings cannot simply be explained by the use of smaller head sizes, since women fared worse than men even with the same head size. Women might have a higher risk of osteoporotic fractures in the thigh bone, or they may be more susceptible to complications from metal-on-metal prostheses.

The researchers acknowledge that surgeons will need to weigh other factors when assessing whether hip resurfacing is suitable for a patient, such as the relative benefits of total hip replacement and resurfacing surgery on patient function and quality of life.?

In an editorial to the study, Art Sedrakyan, MD, PhD, of Weill Cornell Medical College in New York, said: "Regulators and surgeons need to make proper recommendations for patients, such as not using resurfacing in women, and developing decision aids for patients to convey the benefits, harms, and uncertainty related to second surgery with large metal-on-metal implants."

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日期:2012年10月5日 - 来自[Health News]栏目
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Study: Ovary Removal Doesn’t Raise Heart Risk

April 25, 2011 -- A new analysis of data from a major women’s health study finds little evidence that ovary removal during hysterectomy increases heart disease risk.

The findings appear to contradict those from another large study in women suggesting a higher risk for heart disease and stroke associated with the practice.

About 600,000 women in the U.S. have their uteruses surgically removed each year. About half of these procedures include removal of the ovaries.

The newly published data from the Women’s Health Study (WHI), which included more than 25,000 women, confirmed that women who had their ovaries removed during hysterectomy developed fewer ovarian cancers than women whose ovaries were not removed.

Keeping ovaries did not appear to be associated with a lower risk for heart disease, osteoporosis, or cancer among the women in the study.

The findings appear in the April 25 issue of the Archives of Internal Medicine.

Choosing Ovary Removal

Ovary removal has benefits for women at high risk for ovarian cancer due to genetic predisposition or family history, and the new analysis appears to tip the scales in favor of removing the ovaries for other women as well.

But it isn’t that simple, experts tell WebMD.

Ovarian cancer is relatively uncommon, while heart disease is the No. 1 killer of older women. More than 10 times as many women die each year from coronary causes as from ovarian cancer.

In the newly published analysis, researchers estimated that one case of ovarian cancer was prevented for every 323 hysterectomies performed with ovary removal.

But keeping ovaries was associated with a clear decrease in heart disease incidence and death from coronary causes in a 2009 analysis of data from the Nurses Health Study (NHS), which included close to 30,000 women.

Health policy researcher Lauren D. Arnold, PhD, MPH, of the University of St Louis, says the contradictory studies can provide a teaching moment for doctors and patients.

“We encourage doctors to practice evidence-based medicine, but that is often interpreted as meaning they need to follow the latest study,” she says. “In this case, we have two very good studies and, for most women, there are still no clear-cut answers.”

Comparing Studies

Two big differences in the studies were the age of the participants and the length of follow-up.

The average age of the women in the Women’s Health Initiative was 63 at enrollment, while women in the NHS trial were enrolled between the ages of 30 and 55. And WHI participants were followed for an average of eight years, while the nurses were followed for 24 years.

NHS researcher William H. Parker, MD, of the University of California, Los Angeles, says the older age of the women in the WHI trial and the fact that the main intent of the study was to examine the impact of hormone replacement treatments on health could have influenced the outcomes.

日期:2011年4月26日 - 来自[Health News]栏目
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