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Query: UMLS:C0028754 (obesity)
 124,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Insulin resistance, defined as a diminished effect of a given dose of insulin on glucose homeostasis, is a highly prevalent feature of women with PCOS. Insulin resistance in PCOS is closely associated with an increase in truncal-abdominal fat mass, elevated free fatty acid levels, increased androgens, particularly free testosterone through reduced SHBG levels, and anovulation. The causes for insulin resistance in PCOS are still unknown. One line of evidence suggests that an increase in truncal-abdominal fat mass and subsequently increased free fatty acid levels induce insulin resistance in women with PCOS. Increased effects of corticosteroids and a relative reduction in oestrogen and progesterone seem to be involved in the aberrant body fat distribution. Conversely, there are also results supporting primary, genetic target cell defects as a cause of insulin resistance in PCOS. An explanation for these seemingly contradictory results could be that the group of women with PCOS is heterogeneous with respect to the primary event in carbohydrate/insulin disturbances. Also insulin secretion in PCOS is characterized by heterogeneity. At one end of the spectrum is a large subgroup of mainly obese women with reduced insulin secretion, which appears to result from failure of the beta cells to compensate for insulin resistance in susceptible women, resulting in glucose intolerance and NIDDM. In the insulin-resistant patients with normal glucose tolerance, most of the hyperinsulinaemia is probably due to secondarily increased insulin secretion and decreased insulin degradation. However, a component of the increased first-phase insulin release is not due to measurable insulin resistance. Notably, this is also found in lean women with normal insulin sensitivity, and is not reversed after weight reduction, in contrast to the findings for insulin resistance. The implications of this enhanced insulin release are not fully clear, but it may tentatively be associated with carbohydrate craving and subsequently increased risks for development of obesity and insulin resistance. It may represent a primary disturbance of insulin secretion in PCOS or may be associated with the perturbed steroid balance in anovulation. The insulin-androgen connection in PCOS appears to be amplified by several different mechanisms, notably in both directions, the initiating event probably varying between individuals. Thus insulin increases the biological availability of potent steroids, primarily testosterone, through the suppression of SHBG synthesis. Insulin is also involved as a progonadotrophin in ovarian steroidogenesis, with the possible net result of interfering with ovulation and/or increasing ovarian androgen production in states of hyperinsulinaemia. Conversely, testosterone may indirectly contribute to insulin resistance through facilitating free fatty acid release from abdominal fat, but perhaps also through direct muscular effects at higher serum levels. It seems likely that this constitution, presumably genetic, would provide evolutionary advantages in times of limited nutrition, given the energy-saving effects of insulin resistance. Hypothetically, hyperinsulinaemia (primary) could provide a stimulus to ensure intake of nourishment, but unlimited food supplies could in some cases initiate a vicious 'anabolic' circle, in which several of the proposed amplifying mechanisms between insulin and androgens--in both directions--could take part.
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PMID:Disturbances in insulin secretion and sensitivity in women with the polycystic ovary syndrome. 877 46

Observations on body weight, circulating androstenedione concentrations and morphology of ovarian stroma were made in Scotophilus heathi during the period of delayed ovulation to make a comparison with polycystic ovarian syndrome in women. Body weight of bats increased from a level of 31.00 +/- 0.30 g in August and reached a peak of 45.00 +/- 0.46 g in November. This increase in body weight was due to accumulation of adipose tissue. The body weight declined gradually from December onwards and finally reached a basal level in March. The circulating androstenedione concentration showed a gradual increase from 36.80 +/- 15.54 ng/ml in August and reached a peak level of 220.50 +/- 50.10 ng/ml in November. Androstenedione concentration reached the lowest level in the March, just before ovulation. Morphological study showed extensive distribution of luteinized stromal cells or interstitial cells (ICs). Morphometric study showed that during the period of ovulatory delay, more than 75% area of the ovary was occupied by the ICs. Hyperandrogenism, anovulation, obesity (fat deposition) and stromal hyperthecosis present during delayed ovulation in S. heathi may serve as an experimental model for some aspects of the polycystic ovarian condition in women.
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PMID:Adiposity and androstenedione production in relation to delayed ovulation in the Indian bat, Scotophilus heathi. 908 Jun 76

Polycystic ovary syndrome (PCOS) is associated with chronic anovulation, hyperandrogenemia, insulin resistance (IR)/hyperinsulinemia, and a high incidence of obesity. Thus, PCOS serves as a useful model to assess the role of IR and chronic endogenous insulin excess on leptin levels. Thirty-three PCOS and 32 normally cycling (NC) women of similar body mass index (BMI) were studied. Insulin sensitivity (S(I)) was assessed by rapid ivGTT in a subset of 28 PCOS and 29 NC subjects; percent body fat was determined by dual-energy x-ray absorptiometry (DEXA) in 14 PCOS and 17 NC. Fasting (0800 h) and 24-h mean hourly insulin levels were 2-fold higher (P < 0.0001), and S(I) was 50% lower (P = 0.005) in PCOS than in NC, while serum androstenedione (A), testosterone (T), 17-alpha hydroxyprogesterone (17OHP), and estrone (E1) levels were elevated (P < 0.0001), and sex hormone-binding globulin (SHBG) levels were decreased (P < 0.01). Twenty-four hour LH pulse frequency, mean pulse amplitude, and mean LH levels were elevated in PCOS (P < 0.001) as compared with NC. Serum leptin levels for PCOS (24.1 +/- 2.6 ng/mL) did not differ from NC (21.5 +/- 3.5 ng/mL) and were positively correlated with BMI (r = 0.81) and percent body fat (r = 0.91) for the two groups (both P < 0.0001). Leptin levels for PCOS and NC correlated positively with fasting and 24-h mean insulin levels (r = 0.81, P < 0.0001 for both PCOS and NC) and negatively with S(I) and SHBG levels. Leptin concentrations for PCOS, but not NC, correlated positively with 24-h mean glucose levels and inversely with 24-h mean LH levels and 24-h mean LH pulse amplitude. Leptin levels were not correlated with estrogen or androgen levels for either PCOS or NC, although leptin levels were positively related to the ratios of E1/SHBG and E2/SHBG for both PCOS and NC and to the ratio of T/SHBG for PCOS only. In stepwise multivariate regression with forward selection, only 24-h mean insulin levels contributed significantly (P < 0.01) to leptin levels independent of BMI and percent body fat for both PCOS and NC. Given this relationship and the presence of 2-fold higher 24-h mean insulin levels in PCOS, the expected elevation of leptin levels in PCOS was not found. This paradox may be explained by the presence of adipocyte IR specific to PCOS, which may negate the stimulatory impact of hyperinsulinemia on leptin secretion, a proposition requiring further study.
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PMID:Serum leptin levels in women with polycystic ovary syndrome: the role of insulin resistance/hyperinsulinemia. 917 63

Polycystic ovary syndrome (PCOS) is a heterogeneous clinical entity that is defined as the association of hyperandrogenism with chronic anovulation in women without specific underlying diseases of the adrenal or pituitary glands. PCOS is also associated with a metabolic disturbance (insulin resistance). The nature of the complex interrelation of obesity, insulin resistance and endocrine abnormalities in PCOS remains unresolved. However, several studies link obesity, body fat distribution and nutritional habitus with the hormonal and metabolic profiles of PCOS. Moreover, intervention studies have suggested that reducing weight and/or hyperinsulinaemia either by diet alone or by a combination of diet and drugs improves hirsutism, fertility and the hormonal and metabolic profiles of PCOS. In fact, the evaluation of nutritional factors in PCOS is helpful for the screening of metabolic abnormalities and the management of women with PCOS. A point of particular interest in the management of PCOS is that the choice of contraception remains difficult in these high cardiovascular risk women. The impact of pills with ethinyl oestradiol on weight, body fat distribution and carbohydrate metabolism in women with PCOS has not been thoroughly evaluated. The lack of prospective studies to evaluate long-term metabolic and cardiovascular tolerance necessitates care and the assessment of other hormonal possibilities.
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PMID:Influences of weight, body fat patterning and nutrition on the management of PCOS. 940 23

The adverse effects of obesity on reproductive function in women are well recognized, but women with polycystic ovary syndrome (PCOS), the most common cause of anovulatory infertility, seem particularly vulnerable to the effects of excessive intake of calories. Polycystic ovary syndrome is associated with hyperinsulinaemia and insulin resistance, the causes of which remain unclear. These metabolic abnormalities are, in turn, related to a disorder of energy expenditure, characterized by reduced post-prandial thermogenesis. It is proposed that these closely interlinked phenomena that, particularly in overweight subjects, are associated with anovulation, may confer a biological advantage for women with PCOS at times of food deprivation, when such women may reproduce more successfully than those without PCOS. A possible causal link between hyperinsulinaemia and ovulation is explored by reference to the interaction of insulin and LH in granulosa cells.
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PMID:Nutrition, insulin and polycystic ovary syndrome. 941 38

The cardinal clinical features of PCOS are hirsutism and menstrual irregularity from anovulation. Obesity occurs in approximately 50% of hyperandrogenic anovulatory women, some of whom also have non-insulin-dependent diabetes mellitus. Underlying these clinical findings are several biochemical abnormalities, including LH hypersecretion, hyperandrogenism, acyclic estrogen production, decreased SHBG capacity, and hyperinsulinemia, all of which contribute to increased ovarian production of androgens, particularly T. A fundamental mechanism of ovarian hyperandrogenism in PCOS is LH hypersecretion. Whether the central nervous system is a possible locus for initiating LH hypersecretion remains unclear, because exaggerated LH secretion is temporarily reversed by induced ovulatory cycles or physiologic luteal concentrations of progesterone. On the other hand, desynchronization of pulsatile LH secretion from sleep in girls with PCOS and an exaggerated (e.g., masculinized) early LH response to GnRHa testing in women with hyperandrogenic anovulation and congenital adrenal virilizing disorders suggest that events occurring before puberty, perhaps during fetal life, may irreversibly alter neuroendocrine function. Hyperinsulinemia from insulin resistance is an important regulatory mechanism governing ovarian hyperandrogenism. Hyperinsulinemia in hyperandrogenic anovulatory women potentiates ovarian hyperandrogenism by enhancing LH secretion; potentiating 17-hydroxylase and, to a lesser extent, 17,20-lyase activity; and suppressing SHBG capacity. It is a key component of hyperandrogenic anovulation caused by a type of insulin resistance that in independent and additive to that of obesity alone. Although the mechanisms governing insulin action on ovarian steroidogenesis are unknown, abnormalities of intracellular insulin signaling or cytochrome P450c 17[alpha] activity may render the 17-hydroxylase/17,20-lyase enzyme complex more sensitive to insulin. Hyperinsulinemia in hyperandrogenic anovulatory women is accompanied by upper-body obesity characterized by an increased amount of abdominal fat. Upper-body obesity is an important independent risk factor for CVD and diabetes. Although genetic and environmental factors affect fat distribution, sex steroids, particularly androgens, regulate lipid metabolism, suggesting yet another link between the hormonal and metabolic abnormalities of hyperandrogenic anovulation. A careful history and physical examination guide the extent of diagnostic testing. Slowly progressive hirsutism with anovulation of peripubertal onset usually reflects hyperandrogenic anovulation. This type of clinical presentation requires an evaluation to rule out other endocrinopathies (e.g., virilizing tumors, adult-onset CAH, hyperprolactinemia, and Cushing's syndrome). Virilization or severe rapidly progressive hirsutism requires immediate investigation to rule out a possible virilizing tumor. The ultimate goals of therapy for hyperandrogenic anovulatory women are to normalize the endometrium, antagonize androgen action at target tissues, reduce insulin resistance, and correct anovulation, if necessary.
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PMID:Polycystic ovary syndrome. 942 64

Androgenic disorders are those conditions in women characterized by excessive androgen action. They are the most common endocrinopathy of women, affecting from 10% to 20%. Signs are: persistent acne, hirsutism and androgenic alopecia, which is the female equivalent of male pattern baldness. A subgroup, those traditionally labeled as having polycystic ovary syndrome (PCOS), additionally have anovulation, as well as menstrual abnormalities and, often, obesity. Although women with androgenic disorders usually present themselves for help with the skin or menstrual changes, there are other important implications regarding their health. Women with PCOS have varying degrees of insulin resistance, and an increased incidence of Type II diabetes mellitus, as well as unfavorable lipid patterns. The presence of these risk factors is suggested by upper segment obesity, darkening of the skin, and the other skin changes that make up acanthosis nigricans. Diagnosis involves measurement of circulating androgens (of which free testosterone is most important), together with prolactin and FSH when menstrual dysfunction is present. Many women with androgenic skin changes have normal serum androgen levels, suggesting increased end organ sensitivity to androgens. Others have hyperandrogenism (of ovarian or adrenal origin). Treatment is usually successful in controlling acne, reducing hirsutism and stabilizing, or partially reversing, androgenic alopecia. Pharmacological approaches involve suppressing androgen levels, for example, the use of an appropriate oral contraceptive, or antagonizing androgen action with several medications that have this activity. Unfortunately, most women with androgenic disorders are frustrated in their efforts to obtain medical help. Understanding androgenic disorders will enable the physician to significantly help the majority of women with these conditions.
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PMID:Androgens and women's health. 960 8

Polycystic ovary syndrome may result from multiple mechanisms, but full expression of the PCO syndrome with hyperandrogenic anovulation depends upon sustained LH drive and relative FSH deficiency. We have described possible intrinsic and extrinsic factors capable of modifying the hypothalamic-pituitary-ovarian axis. Available evidence suggests the presence of an intrinsic alteration in GnRH-LH drive. The long-term natural history of HAA is variable and depends on several factors including obesity, aberrations in insulin action, intrinsic ovarian function, and end-organ responsiveness to androgens. Figure 1 presents a conceptualization of the pathogenesis of PCOS diagramming the multiple modulators of its expression. Long-term suppression of androgens when fertility is not desired should modify the full expression of the PCO syndrome. It is important to appreciate that therapy with oral contraceptive agents has few drawbacks and many immediate and potential long-term benefits for women with HAA. This therapy may be of greatest benefit when started in adolescence prior to the progression of obesity, hirsutism, and thecal-stromal hyperplasia. Women with HAA represent a large subgroup of patients who require individualization of their health care with sensitivity to issues surrounding anovulation, obesity, hirsutism, and infertility.
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PMID:Role of GnRH drive in the pathophysiology of polycystic ovary syndrome. 976 66

While most studies show a higher body mass in Western women to be positively associated with an increased breast cancer risk in postmenopausal women, they show a negative association in the case of premenopausal women. A review of case-control and cohort studies suggest that such protection applies mainly to obesity in teenage girls, whereas obesity appearing after the teenage years is more likely to be associated with a higher risk of postmenopausal breast cancer. The mechanisms are uncertain. There is evidence that obesity and the components of the Western diet can independently provoke hyperinsulinaemic insulin resistance at puberty, and in adolescent girls this has been related to evidence of abnormal ovarian steroidogenesis and anovulation. This may decrease promotion of mammary carcinogenesis. If however, obesity continues after the teenage years, the higher concentration of insulin-like growth factor 1 (IGF1) associated with hyperinsulinaemia can interact with oestrogen receptors in mammary epithelium to lead to increased proliferative activity. This review postulates that the observed protective effect of early obesity against premenopausal breast cancer is likely to be replaced by an increased risk of postmenopausal breast cancer if obesity continues after the teenage years. The manifestation of breast cancer is merely postponed to an older age. Recent prospective and case-control studies suggest that increased bioavailability of IGF1 is a marker of increased breast cancer risk in premenopausal women. Nutritional intake in early life may programme later activity in the growth hormone-IGF1 axis and influence the progression of transformed cells in mammary tissue. The question remains whether deliberate weight loss can reverse the effects of weight gain.
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PMID:Teenage obesity in relation to breast cancer risk. 982 39

Polycystic Ovary Syndrome has been related with hyperinsulinemia and insulin resistant, is a heterogenous disorder biochemistry and clinical, as a consequence androgens and insulin hypersecretion, the exacerbation for the chronic anovulation and obesity, which is caused frequently of hirsutism and sterility, moreover is related with great variety metabolic pathologies, cardiac sickness and oncologies disease in long time. The most important in this present review is to determine a role of the hyperinsulinaemia and insulin resistance in this syndrome.
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PMID:[Insulin resistance in polycystic ovary syndrome]. 982 1


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