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Query: UMLS:C0003128 (anovulation)
 1,718 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Many different disease processes can result in a phenotype of hirsutism, anovulation, and oligomenorrhea or amenorrhea. An important goal of reproductive endocrinologists is to identify specific genetic diseases that can produce the hyperandrogenic phenotype. Two genetic disorders that can result in the hyperandrogenic phenotype are 1) mutations in the 21-hydroxylase gene (adrenal hyperplasia), and 2) mutations in the insulin receptor gene (the syndrome of hyperandrogenism-insulin resistance and acanthosis nigricans). The identification of these two genetic causes of hyperandrogenism provides the opportunity to investigate new approaches to prenatal diagnosis and therapy, genetic analysis of pedigrees, and innovative forms of therapy.
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PMID:Hyperandrogenism: new insights into diagnosis and therapy. 181

Women with polycystic ovary syndrome (PCOS) are markedly insulin-resistant, but the molecular mechanisms of these changes and their relationship to the hyperandrogenic state remain to be clarified. Mutations have recently been identified in the insulin receptor gene of patients with extreme forms of insulin resistance associated with hyperandrogenism (eg, type A insulin resistance), and these mutations account for the insulin resistance in such patients. We performed this study to determine whether mutations in the coding portion of the insulin receptor gene were responsible for insulin resistance in PCOS. Insulin binding studies using cultured skin fibroblasts of three obese (body mass index > 27 kg/m2) women with PCOS (ie, mild hyperandrogenemia and chronic anovulation of unknown etiology) and documented insulin resistance showed no apparent abnormalities in either the number or affinity of insulin binding sites. Direct sequencing of all 22 exons of the insulin receptor gene from two of the women with PCOS did not reveal any mutations. Furthermore, both alleles of the gene were expressed at equal levels. In a third insulin-resistant PCOS woman, there was no evidence for a mutation in the coding portion of the insulin receptor gene as determined by denaturing gradient gel electrophoresis (DGGE). We conclude that the insulin resistance in these PCOS women was caused by a defect extrinsic to the insulin receptor.
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PMID:Absence of insulin receptor gene mutations in three insulin-resistant women with the polycystic ovary syndrome. 799 Jul 13

Polycystic ovary syndrome (PCOS) is a common disorder characterized by chronic anovulation and infertility, hyperandrogenaemia, and frequently insulin resistance. This study investigated whether mutations in the insulin receptor gene could explain the insulin resistance in subjects with PCOS. From a total of 108 women with PCOS, a subgroup of 24 were selected on the criteria of being in the upper quartile for insulin resistance as assessed by fasting serum insulin, insulin area under the curve following 75 g oral glucose tolerance test, and endogenous glucose disposal as a measure of insulin sensitivity. An additional five normal women were also investigated. The entire coding region of the insulin receptor gene, comprising of 22 exons, was amplified by the PCR using genomic DNA and then subjected to single-stranded conformation polymorphism (SSCP) analysis to screen for single-base DNA sequence changes. DNA sequencing revealed that SSCP variants were detected in regions encompassing exons 3, 6-8, 11, 13, 15, 17, and 22. SSCP variants in regions of exons 3, 6, 7, 11, 15 and 22 were caused by nucleotide substitutions within intronic regions flanking the exon. The considerable variation seen in the 5' intron of exon 3 was found to be caused by variation in the number of (ATTT, 8-11) and (TC, 10-13) short sequence repeats. SSCP variants in exons 8 (Asp519, Ala523), 13 (Asn 838), and 17 (Tyr984, His1058) were caused by known silent polymorphisms. Southern blotting experiments excluded major gene deletions, insertions, or rearrangements. We conclude that insulin resistance in subjects with PCOS is not commonly a consequence of missense or nonsense mutations in the insulin receptor gene.
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PMID:Molecular scanning of the insulin receptor gene in women with polycystic ovarian syndrome. 862 68

Almost two decades of research have greatly increased our knowledge in the complex field of metabolic aberrations in polycystic ovary syndrome, but still many problems remain unsolved. The statistical association between insulin levels and androgens originally put the focus on possible direct cause-and-effect relationships between these factors. Indeed there is evidence that insulin may affect ovarian functions in multiple ways, presumably in some cases causing anovulation and hyperandrogenism. Clearly, insulin may increase biologically active testosterone through reducing SHBG levels. Conversely, major increases in androgen levels may induce muscular changes leading to reduced insulin-mediated glucose uptake. There are suggestions of increased steroidogenesis in both ovarian and adrenal pathways, with the net result of increased androgen production. There are also findings supporting increased corticosteroid production, which could contribute to insulin resistance directly or through promoting accumulation of abdominal fat, a typical feature of over-weight women with PCOS. Free fatty acids, released in great amounts from abdominal fat, may induce insulin resistance. Insulin resistance may also be due to a primary aberration in the insulin receptor. Putatively increased serine phosphorylation may cause both impairment of the insulin signal and increased 17,20 lyase activity, thus suggesting a common cause for insulin resistance and increased androgen production. There are also findings supporting a high prevalence of beta-cell dysfunction in PCOS, ranging from increased insulin secretion, not explained by insulin resistance or BMI, to failing beta-cell function, mainly in obese women during progress to glucose intolerance and NIDDM. Recent genetic findings also support a multifactorial genesis to PCOS, notably with positive findings both in genes regulating steroidogenesis and insulin secretion. It is suggested that PCOS is the result of "thrifty" genes, providing advantages in times of shortage of nutrition such as muscular strength, moderate abdominal fatness and decreased insulin sensitivity, i.e. an anabolic, energy saving constitution. However, when this constitution is exposed to unlimited food supplies and modern sedentary life style a full-blown PCOS with insulin resistance and infertility is triggered, presumably via several mechanisms, which follow a logical amplification system between two basic anabolic hormones, insulin and testosterone.
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PMID:Polycystic ovary syndrome and insulin resistance: thrifty genes struggling with over-feeding and sedentary life style? 985 13

Insulin has a stimulatory effect on steroidogenesis by granulosa cells of normal and polycystic ovaries and interacts with gonadotropins in an additive or, as in the case of LH, a synergistic manner. These actions seem to be mediated specifically by the insulin receptor rather than by cross-reaction with the type I IGF receptor, even in tissue obtained from women with PCOS with biochemical evidence of insulin resistance. The authors suggest that hyperinsulinemia makes a significant contribution to premature arrest of follicle growth, which is characteristic of anovulation in women with PCOS, and that the interaction of insulin with LH is a key element in this process. Insulin may also have a role in amplifying LH-induced androgen production by theca cells, which may help explain the prominence of symptoms of hyperandrogenism in obese subjects with PCOS. The results of recent clinical studies of insulin-sensitizing agents such as metformin and the thiazoladinedione troglitazone in PCOS have provided encouragement that improvement of insulin sensitivity and consequent lowering of circulating insulin levels by these agents may be of therapeutic value in the management of both anovulation and hirsutism.
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PMID:Insulin action in the normal and polycystic ovary. 1035 23

Polycystic ovary syndrome (PCOS) is the most common disorder of ovarian function in premenopausal women. PCOS is characterised by chronic anovulation and androgen excess with clinical manifestation of irregular menstrual cycles, hirsutism and/or acne. Insulin resistance with resultant hyperinsulinaemia, irrespective of excess weight or frank obesity, has been reported in patients with PCOS, and, as insulin has a direct effect on ovarian androgen production in vitro, insulin resistance may play a crucial role in the physiopathology of PCOS. Although the molecular mechanism(s) of insulin resistance in PCOS is unclear, excessive insulin-independent serine phosphorylation of the beta subunit of the insulin receptor, as reported in some patients with PCOS, has been put forward as a new mechanism for insulin resistance. Insulin-sensitising agents have recently been investigated for their role in the short term treatment of insulin resistance in PCOS. Controlled studies have shown that metformin administration, by promoting bodyweight loss, can decrease fasting and stimulated plasma insulin levels. However, other studies have shown metformin 500 mg 3 times daily to decrease insulin secretion and to reduce ovarian production of 17alpha-hydroxyprogesterone with recovery of spontaneous or clomifene-induced ovulation, independently of weight loss. These findings suggest a new indication for metformin and present insulin-sensitising agents as a novel approach in the treatment of ovarian hyperandrogenism and abnormal ovulation in PCOS. They also suggest that long term administration of metformin might be helpful in treating insulin resistance, thus reducing risks of type 2 (non-insulin-dependent) diabetes and cardiovascular disease in these patients.
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PMID:Insulin resistance, polycystic ovary syndrome and metformin. 1057 24

The polycystic ovary syndrome (PCOS) is the most frequent endocrine disease in women of reproductive age. Hyperandrogenism, anovulation and metabolic syndrome are the cardinal features of PCOS. Hyperandrogenism results from a diffuse enzymatic hyperactivity at the theca-interstitial cell level. Anovulation is due to an impairment of the selection of a dominant follicle, while the number of smaller follicles is exaggerated. The molecular grounds of insulin resistance could be an increased Serine phosphorylation of the insulin receptor. The clinical classification of PCOS distinguishes three forms: the classic PCOS, where the three above mentioned features are present, the non classic PCOS and the asymptomatic PCOS, revealed by ultrasonography. Only the increased ovarian volume or surface (>11ml and> 5.5cm(2), respectively) must be viewed as a specific ultrasonic sign of PCOS. Cyproterone acetate remains the basic treatment of hyperandrogenism. The treatment of anovulation and infertility follows a consensual strategy. The insulin sensitizing treatment allows to decrease hyperandrogenism, to reverse the menstrual cycle irregularity and to obtain spontaneous or induced pregnancies.
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PMID:[Polycystic ovary syndrome]. 1113 21

In-vitro studies of adipose tissue have shown that patients with polycystic ovarian syndrome (PCOS) have marked insulin resistance, the abnormalities being more pronounced during amenorrhoea compared to following an ovulatory cycle. If the insulin resistance in PCOS is a reflection of anovulation then patients with hypogonadotrophic hypogonadism (HH) should also have a reduction in insulin sensitivity. This study was designed to investigate insulin sensitivity in patients with HH. Seven patients with HH were studied and compared with eight age and body mass index matched female controls. Adipocyte insulin receptor binding was measured and adipocyte insulin action was assessed by measuring initial rates of 3-O-methylglucose uptake and inhibition of lipolysis. The specific insulin receptor binding per 10 cm(2) cell surface was 0.95 +/- 0. 25% in HH and 1.85 +/- 0.14% in control patients (P < 0.01). Maximum rates of glucose uptake were also impaired in HH compared with controls (3-O-methylglucose transport 0.81 +/- 0.22 versus 1.83 +/- 0.2 pmol/10 cm(2)/5 s)(P < 0.01). Hence, patients with HH have impaired insulin sensitivity to a degree similar to that seen in PCOS, suggesting a direct effect of anovulation on insulin sensitivity.
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PMID:Adipocyte insulin action in hypogonadotrophic hypogonadism. 1092 84

Polycystic ovary syndrome (PCOS) is a common endocrine disorder affecting approximately 5-10% of women of reproductive age. The clinical features of PCOS include oligo/anovulation, hyperandrogenemia, and hyperinsulinemia. Because P450c17 is the single enzyme catalyzing both 17alpha-hydroxylase and 17,20-lyase activities in the ovary and adrenal, some have suggested that defects in P450c17 may cause the hyperandrogenism of PCOS. Previous studies have shown that serine hyperphosphorylation of P450c17 increases the enzyme's 17,20-lyase activity, thereby favoring androgen production, and that serine phosphorylation of the insulin receptor beta-chain (IR-beta) inhibits IR-beta tyrosine phosphorylation, causing insulin resistance in vitro. We previously suggested that a gain of function mutation in a single serine kinase might cause the hyperandrogenism and insulin resistance observed in PCOS patients by excessive phosphorylation of both P450c17 and IR-beta. To test this hypothesis, we obtained fibroblasts from nine previously studied patients: three controls, three PCOS patients with normal levels of IR-beta serine phosphorylation, and three PCOS patients with increased levels of IR-beta serine phosphorylation. Initial studies showed that such skin fibroblasts could not be transfected effectively by calcium phosphate, diethylaminoethyl-dextran, lipofection or adenovirus procedures. Therefore, we employed a retroviral infection system to stably express human P450c17 in the primary cultures of fibroblast cells from the PCOS patients and controls and measured the resulting 17alpha-hydroxylase and 17,20-lyase activity. The cells were analyzed in a blinded fashion until the study was complete. The 17alpha-hydroxylase and 17,20-lyase activities in each cell line correlated well with the amount of P450c17 protein expressed, but there was no correlation between either enzymatic activity (or their ratio) with the clinical phenotype of the cells' donors even when results were corrected for the number of P450c17 complementary DNA inserts per cell line. Overnight incubation with 1 micromol/L insulin also did not affect enzymatic activity. Thus, we were unable to find evidence for the hypothesis that in PCOS a single abnormal kinase hyperphosphorylates both IR-beta, causing insulin resistance, and P450c17, causing hyperandrogenism. However, because fibroblasts do not normally express either P450c17 or the accessory proteins needed for its optimal activity, these results cannot exclude a role for serine phosphorylation in the hyperandrogenism and insulin resistance of PCOS.
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PMID:Enzymatic activities of P450c17 stably expressed in fibroblasts from patients with the polycystic ovary syndrome. 1109 77

The polycystic ovary syndrome (PCOS) is one of the commonest female endocrinopathies affecting 5-10% of women of reproductive age. The disorder, characterized by chronic anovulation and signs of hyperandrogenism, results from a complex interaction between genetic predisposing factors and environmental triggers. We have studied 85 Caucasian PCOS patients and 87 age-matched Caucasian control women for associations with four candidate genes: follistatin, CYP19 (aromatase), CYP17a, and the insulin receptor (INSR). These genes were analyzed using microsatellite markers located near or inside the genes. We found that only the insulin receptor gene marker D19S884 was significantly associated with PCOS (p=0.006 and even after a conservative correction p=0.042). The INSR gene region was then fine mapped with an additional panel of 9 markers but only marker D19S884, located 1 cM telomeric to the INSR gene, was again associated with PCOS. In conclusion, our results suggested that a susceptibility gene for PCOS was located on chromosome 19p13.3 in the insulin receptor gene region. It remains to be determined if this susceptibility gene is the insulin receptor gene itself or a closely located gene. Since insulin stimulates androgen secretion by the ovarian stroma it is likely that INSR function in the ovary is involved in the genetic susceptibility ot PCOS.
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PMID:Evidence for association of polycystic ovary syndrome in caucasian women with a marker at the insulin receptor gene locus. 1123 39


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