ISSN:1068-3097    

出版商:OVID    

年代:2000

数据来源: OVID

ISSN:1068-3097    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Since it was discovered that parathyroid hormone related protein (PTHrP) is the major mediator of hypercalcemia of malignancy, there has been intense interest in defining the biological roles and mechanism action of the protein. Gene-knockout studies demonstrated that a functionalPTHrPgene is required for postnatal survival, and that the growth plates of embryonic mice lacking PTHrP display premature cartilage differentiation. Further studies have demonstrated that PTHrP serves as an intermediary in the actions of the patterning geneIndian hedgehog(Ihh) to delay and coordinate chondrocyte differentiation. Rescue of the lethal phenotype ofPTHrP–/– mice has revealed other defects including lack of normal breast, skin, and tooth development. PTHrP is secreted by epithelial elements of developing tissues and appears to promote the expression of inductive factors by acting on PTH/PTHrP receptors in adjacent mesenchyme. PTHrP is also expressed in a variety of smooth muscle beds, where it serves as a locally produced muscle relaxant. Expression of PTHrP has been detected in many parts of the central nervous system, and recent evidence suggests that PTHrP protects neurons from excitotoxicity. The classical mechanism of action of PTHrP is through activation of the PTH/PTHrP receptor. However, evidence has accumulated that PTHrP can also act as in intracrine agent by targeting to the nucleus following synthesis. Recent studies have characterized the mechanisms underlying the nuclear targeting of PTHrP and have suggested ways in which nuclear signaling by PTHrP may effect cellular responses.

ISSN:1068-3097    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Osteoporosis in men has become much more prominent as its prevalence and impact have become apparent. Fractures in men are common and of great importance to both individuals and society. Although in many ways the character of osteoporosis in men is similar to that in women, there are important differences as well. For instance, the rate of morbidity and mortality after a hip fracture is greater in men, probably because of more concomitant illness. The causation of osteoporosis in men and the approach to diagnosis are also somewhat different. Of particular importance is the impact of gonadal insufficiency and the relative roles of androgens and estrogen in male skeletal health. Apparently both sex steroids are essential, but the mechanisms by which each affects bone metabolism are unclear. Approaches to the prevention and therapy of osteoporosis in men have been developed. Evidence supports the effectiveness of vitamin D and calcium supplementation, and bisphosphonates are effective in preventing bone loss and fractures in several situations. New therapies (parathyroid hormone, selective estrogens and androgens) are on the horizon.

ISSN:1068-3097    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Osteoporosis is a common disease in postmenopausal women and can result in considerable morbidity and mortality as a consequence of spontaneous fractures. Fortunately, effective therapeutic agents that prevent or slow bone resorption are now available for the prevention and treatment of osteoporosis. Most patients treated with antiresorptive agents gain bone mass and have a reduced risk of fractures. There are few studies that compare different antiresorptive agents, and those evaluate bone density not fractures. Antifracture efficacy has been established in separate randomized, placebo-controlled studies and results of studies using raloxifene and risedronate have been published this year. Current advances with alendronate include different dosing regimens, combination with other drugs, and extension to other patient populations. Advances with estrogen involve the effect of lower dosages. In choosing an agent for osteoporosis prevention or treatment, the variable effects on bone and nonskeletal sites must be taken into consideration.

ISSN:1068-3097    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Glucocorticoids cause profound effects on bone resorption and formation that result in osteoporosis. Glucocorticoids increase bone resorption by stimulating new osteoclastogenesis. This seems to be due to an increase in osteoclast differentiation factor and a decrease in osteoprotegerin. Glucocorticoids inhibit bone formation by decreasing osteoblast formation and function and by decreasing the synthesis and activity of locally produced factors. Clinically, most of the bone loss occurs in the first few months of glucocorticoid exposure, and doses of prednisolone of 2.5 to 7.5 mg daily are sufficient to increase the risk of fractures of the spine and hip. Bisphosphonates inhibit bone resorption and prevent the bone loss that follows glucocorticoid exposure and are likely to diminish fracture risk. Eventually, patients with glucocorticoid-induced osteoporosis develop decreased bone remodeling, and anabolic agents may be necessary for therapeutic purposes. Parathyroid hormone increases bone mineral density significantly in postmenopausal women with glucocorticoid-induced osteoporosis.

ISSN:1068-3097    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Short-term hormone replacement therapy (HRT) in postmenopausal women is effective for the treatment of estrogen deficiency symptoms such as vasomotor flushes and vaginal dryness. Most practitioners would agree that short-term use (up to 3 years) of HRT (combined estrogen and progestin for those with a uterus) is not associated with significant health risks. Specifically, no study has demonstrated an increased risk of breast cancer with short-term use. On the other hand, long-term use of HRT to prevent osteoporosis and coronary heart disease might be associated with possible risks, in particular breast cancer. At this time, it remains unclear which postmenopausal women are candidates for long-term HRT. Specific areas of controversy include (1) the role of estrogen in primary versus secondary prevention of coronary heart disease, (2) the impact of estrogens and progestins on breast cancer risk, and (3) the risk of venous thromboembolic events with postmenopausal estrogen use.

ISSN:1068-3097    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Hypogonadism is common among men with HIV disease, particularly among those with the AIDS wasting syndrome. The mechanisms of androgen deficiency in this population remain unknown but may relate to the effects of chronic illness per se, poor nutrition, cytokines, or specific drugs used in the treatment of HIV disease. Recent studies suggest that the prevalence of androgen deficiency among men with HIV disease remains increased, although to a lesser extent, in the current era of highly active antiretroviral therapy. Androgen therapy has now been established as an effective therapy to reverse muscle loss in men with AIDS wasting and is an important therapy in the management of such patients. Similarly, androgen deficiency is common among women with HIV disease, in whom androgen levels correlate with muscle mass and functional status. Preliminary studies indeed suggest a benefit of androgen replacement in HIV-infected women. Research is ongoing into the mechanisms of androgen deficiency and the therapeutic role of androgens in the management of HIV-infected patients, including the large population of HIV-infected women.

ISSN:1068-3097    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

With the advent of immunoassays specific for inhibin A and activin A, much has been learned about the role of these proteins in female physiology. Both are prominent products of the placenta and, as such, can be found in high concentrations in maternal serum throughout pregnancy. This has led to the exploration and application of inhibin and activin measurement as markers of pregnancy complications. Most notably, inhibin A is used clinically in Europe and the United States as part of prenatal serum screening protocols for fetal Down syndrome. Other potential clinical applications are discussed.

ISSN:1068-3097    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

The polycystic ovary syndrome is a prevalent disorder characterized by chronic anovulation and hyperandrogenism. It has recently been appreciated that insulin resistance with a compensatory hyperinsulinemia is also a prominent feature of the disorder and plays a key role in its development in many affected women. The purpose of this review is to highlight clinical studies in this area that were published during the past year. Areas discussed include the use of insulin-sensitizing drugs for treatment, D-chiro-inositol and insulin resistance, syndrome X (ie, the dysmetabolic syndrome), genetics of polycystic ovary syndrome, precocious puberty and adrenarche as early manifestations of polycystic ovary syndrome, and early pregnancy loss in polycystic ovary syndrome.

ISSN:1068-3097    

出版商:OVID    

年代:2000

数据来源: OVID