testosterone and libido in surgically and naturally menopausal women

The assessment and then treatment of a change in libido, or a change in the desire to partake in sexual activity, during the menopausal transition and beyond has been a challenging and elusive area of clinical research. This is partly due to the multidimensional nature of female sexuality, the difficulties of measuring testosterone in women in a reliable and accurate manner, and the complexity of the neurobiology and neurobehavior of female sexual desire. In addition, there is a lack of evidence for diagnostic specificity of low free testosterone levels for the symptom of low libido in women for whom there are no confounding interpersonal or psychological factors; although, in the symptomatic population of surgically or naturally menopausal women, a low level of free testosterone often accompanies a complaint of reduced desire/libido. The randomized clinical trial research on testosterone replacement for naturally and/or surgically menopausal women with sexual dysfunction has been criticized for a high placebo response rate, supraphysiological replacement levels of testosterone, the perception of modest clinical outcome when measuring objective data such as the frequency of sexual intercourse relative to placebo, and the unknown safety of long-term testosterone replacement in the estrogen-replete surgically or naturally menopausal woman. A careful review of current evidence from randomized, controlled trials lends support to the value of the replacement of testosterone in the estrogen-replete menopausal woman for whom libido and desire has declined. The issue of long-term safety remains to be answered. Multifactorial nature of female sexuality The assessment and then treatment of a change in libido, or a change in the desire to partake in sexual activity, during the menopausal transition and beyond has been a challenging and elusive area of clinical research. There is a lack of evidence for the diagnostic specificity of low free testosterone levels for the symptom of low libido in the women for whom there are no confounding interpersonal or psychological factors; although, in the symptomatic population of surgically or naturally menopausal women, a low level of free testosterone often accompanies a complaint of reduced desire/libido [1–6]. Female sexuality is dependent on biological, psychosexual, sociocultural and context-related factors [7–9]. As a consequence, any movement or change in any of these realms may increase or decrease a woman's perception of her drive or motivation to participate in sexual activity. The presence of any chronic medical illness such as diabetes, pulmonary or cardiovascular problems, or depression will in many instances impact a woman's sexuality concurrent with changes related to age [10,11]. The length of the relationship with a partner, as well as aging, has been demonstrated to impact sexual interest and frequency of sexual activity [12,13]. The menopause has been shown to have an incremental effect on a woman's sexuality, separate from the change brought about by aging [14]. The quality of her intimate relationship and the degree to which she feels empowered in it have been demonstrated to affect sexual desire [15]. The culture in which she lives has been shown to affect frequency of sexual intercourse [16]. The degree of stress she is under, as well as her general wellbeing, has also been shown to affect her libido. A recent longitudinal study demonstrated that higher stress lowers wellbeing, resulting in a decrease in sexual arousal, enjoyment, orgasm and desire [17]. In addition, the balance between sexual inhibition and sexual excitement may be unique to each woman and may change according to her circumstances, along with any other change she may have with regard to these opposing forces [18]. Thus, the treatment of any woman distressed by a change in desire at midlife and beyond is driven by many factors. The clinician's task is to elucidate which one or more of these many variables changed in her life, concurrent with her change in sexual desire, and then to determine whether or not these changes are related to her change in sexual desire

Plasticity Through Canalization: The Contrasting Effect of Temperature on Trait Size and Growth in Drosophila

In most ectotherms, a reduction in developmental temperature leads to an increase in body size, a phenomenon known as the temperature size rule (TSR). In Drosophila melanogaster, temperature affects body size primarily by affecting critical size, the point in development when larvae initiate the hormonal cascade that stops growth and starts metamorphosis. However, while the thermal plasticity of critical size can explain the effect of temperature on overall body size, it cannot entirely account for the effect of temperature on the size of individual traits, which vary in their thermal sensitivity. Specifically, the legs and male genitalia show reduced thermal plasticity for size, while the wings show elevated thermal plasticity, relative to overall body size. Here, we show that these differences in thermal plasticity among traits reflect, in part, differences in the effect of temperature on the rates of cell proliferation during trait growth. Counterintuitively, the elevated thermal plasticity of the wings is due to canalization in the rate of cell proliferation across temperatures. The opposite is true for the legs. These data reveal that environmental canalization at one level of organization may explain plasticity at another, and vice versa

Restoring Rivers One Reach at a Time: Results from a Survey of U.S. River Restoration Practitioners

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72915/1/j.1526-100X.2007.00244.x.pd