Relative risk of conversion from normoglycaemia to impaired glucose tolerance or non-insulin dependent diabetes mellitus in polycystic ovarian syndrome.

BACKGROUND: Cross-sectional studies have shown a high frequency of impaired glucose tolerance (IGT) and non-insulin dependent diabetes mellitus (NIDDM) in women with polycystic ovarian syndrome (PCOS). However, little is known about the change in glucose tolerance that occurs over a period of several years in women with PCOS. METHODS: Sixty-seven women with PCOS received a 75 g glucose tolerance test and measurement of lipids at baseline and at follow-up after an average time of 6.2 years. All women followed prospectively had normal glucose tolerance (n = 54) or IGT (n = 13) at the start of the study. RESULTS: Change in glycaemic control from baseline was frequent, with 5/54 (9%) of normoglycaemic women at baseline developing IGT and a further 4/54 (8%) moving directly from normoglycaemic to NIDDM. For women with IGT at baseline, 7/13 (54%) had NIDDM at follow-up. Body mass index (BMI) at baseline was an independent significant predictor of adverse change in glycaemic control. CONCLUSIONS: Women with PCOS, particularly those with a high BMI, should be reviewed regularly with respect to IGT or NIDDM, as the frequency of impaired glycaemic control is high, and that the rate of conversion from normal glucose tolerance to IGT or NIDDM, or from IGT to NIDDM is substantial.

Circulating follistatin concentrations are higher and activin concentrations are lower in polycystic ovarian syndrome.

Familial polycystic ovarian syndrome (PCOS) has been proposed to be linked to a site near the follistatin gene. We studied the concentrations of circulating follistatin, activin A and inhibin B in well-characterized subjects with PCOS (n = 108) and controls without PCOS (n = 20). Mean (+/- SEM) concentrations of follistatin were higher (P < 0.05) in PCOS (0.27 +/- 0.03 ng/ml) than controls (0.15 +/- 0.02 ng/ml) and activin A were lower (P < 0.05) in PCOS (0.20 +/- 0.01ng/ml) than controls (0.24 +/- 0.02 ng/ml). Inhibin B concentrations were not different between the two groups: PCOS (0.06 +/- 0.01ng/ml), and controls (0.06 +/- 0.01ng/ml). It is proposed that higher concentrations of follistatin with lower concentrations of activin A may relate to follicular development not proceeding beyond 8-10 mm and may be partly responsible for the lack of pre-ovular follicle development in PCOS.

The in vivo and in vitro effects of exogenous leptin on ovulation in the rat.

Leptin, a hormonal product of the Lep gene, is expressed by adipocytes and is thought to play a role in regulating food intake and reproduction. The leptin protein has been localized in many reproductive tissues, including the ovary. Several publications indicate that the ovary is directly affected by leptin and that leptin may be a factor linking obesity and reproductive dysfunction. In this study, the effect of systemic leptin administration on ovulation in the rat ovary, both in vivo and in vitro, was investigated. Ip administration of leptin (30 microg at 3 hourly intervals for 15 h) to immature gonadotropin-primed rats caused a decline in ovulation in vivo, from 15.9+/-2.0 oocytes in the control animals to 5.3+/-1.6 oocytes in the leptin-treated animals (P < 0.001). Plasma progesterone and estradiol levels were analyzed immediately before ovulation, and neither was altered significantly in animals receiving the leptin treatment. Food consumption and body weight decreased following leptin treatment; however, a loss in body weight alone (pair-fed controls) was insufficient to explain the decrease in ovulation observed in the leptin-treated animals. In vitro perfusion of FSH-primed whole ovaries showed that treatment with leptin in combination with LH significantly decreased ovulations from 5.7+/-1.6 per ovary perfused with LH alone to 1.3+/-0.6 in those with LH and 1 microg/ml leptin (P < 0.05). Progesterone and estradiol levels in the samples taken during the perfusion period were unaffected by leptin treatment. In summary, leptin administration resulted in fewer ovulations, both in vivo and in vitro, but did not influence steroid levels. Systemic leptin administration at these doses can therefore inhibit ovulation, a process that occurs through a direct effect on the ovary.

No association between the -308 polymorphism in the tumour necrosis factor alpha (TNFalpha) promoter region and polycystic ovaries.

The tumour necrosis factor (TNF)2 allele appears to be linked with increased insulin resistance and obesity, conditions often found in overweight patients with polycystic ovary syndrome (PCOS). The significance of TNFalpha polymorphism in relation to the clinical and biochemical parameters associated with PCOS was investigated in 122 well-characterized patients with polycystic ovaries (PCO). Of these, 84 had an abnormal menstrual cycle and were classified as having PCOS, while the remaining 38 had a normal menstrual cycle and were classified as having PCO. There were a further 28 individuals without PCO (non-PCO) and 108 individuals whose PCO status was undetermined (reference population). The promoter region of the TNFalpha gene was amplified by polymerase chain reaction (PCR), and the presence or absence of the polymorphism at -308 was determined by single-strand conformational polymorphism (SSCP) analysis. The less common TNF allele (TNF2) was found as TNF1/2 or TNF2/2 in 11/38 (29%) of PCO subjects, 25/84 (30%) of PCOS subjects, 7/28 (25%) of non-PCO subjects, and 45/108 (42%) of the reference population. There was no significant difference in the incidence of the TNF2 allele between the groups. The relationship of TNF genotype to clinical and biochemical parameters was examined. In both the PCO group and the PCOS group, the presence of the TNF2 allele was significantly associated with lower glucose values obtained from the glucose tolerance testing (P<0.05). The TNF genotype was not significantly associated with any clinical or biochemical parameter measured in the PCO, PCOS or non-PCOS groups. Thus, the TNFalpha -308 polymorphism does not appear to strongly influence genetic susceptibility to polycystic ovaries.

Colorimetric measurement of plasma lactate.

A rapid and simple enzymatic method for plasma lactate is proposed using stable reagents to produce the formazan color. This method agrees well with a reference kit method, r = 0.955 and the regression equation is y = 0.99x + 0.09. The over-all recovery averages 100%, with a precision ranging from 0.6 to 3.3%. No interferences have been shown with the formazan reaction. The proposed method is inexpensive, ideal for batch analyses, and is an attractive method for the busy clinical laboratory.

A note of caution on the use of the LD ratio in myocardial infarction.

Different LD1/LD2 ratios for both normal and pathological samples were obtained with two different reagent kits. These ratio differences are due to the substrate formulation and not to the electrophoresis separation technique. In 45 patients with abnormal serum "cardiac" enzymes, results obtained by the two kit methods showed 17% and 50% "flipped ratio" abnormalities as against 78% and 67% abnormalities when the ratios were compared against appropriate reference ranges. The improper use of the LD ratio test is probably the main cause for its diminished diagnostic usefulness.

An appraisal of CSF glutamine measurement by acid hydrolysis.

The hydrolysis of CSF glutamine as proposed by Harst et al. (2) was shown to be incomplete due to the low acid concentration in the reaction. Complete hydrolysis was achieved with a higher acid concentration. Because glutamine is stoichiometrically converted to ammonia and glutamic acid, both ammonia and glutamine can be used as standard solutions. It was further shown that glutamine standard solution, even though deaminated, can still be used. CSF urea, if very high, will give falsely elevated glutamine concentrations. Correction is possible by subtraction of its glutamine equivalent value. An optimum Berthelot reaction was developed for our modified assay.

Detection of alkaline phosphatase/immunoglobulin complexes.

We report another patient with a circulating alkaline phosphatase/immunoglobulin complex in his blood, and describe a simple method of demonstrating such complexes. On electrophoresis on cellulose acetate, the complex was relatively slow moving and there was no activity in the normal bone/liver isoenzyme region. When the serum was treated with trypsin, the slow band disappeared and the normal pattern was restored.

Correction for the suppressive effect of haemoglobin on NADH absorbance in the transketolase assay.

The kinetic transketolase assay measures the absorbance change of NADH in the presence of haemoglobin. Haemoglobin was shown to suppress NADH absorbance which resulted in an apparently lower enzyme activity. To minimise this suppression, the transketolase assay was performed on samples with haemoglobin concentration of 30 g/l. At this level the absorbance of NADH in the presence of haemoglobin averaged 90.5% of that in Tris buffer. It is proposed that the calculation of the enzyme activity should be corrected for this suppression.

The effect of pre-incubation and direct procedure for the alanine transaminase assay in two kits compared.

The kinetic measurement of serum alanine transaminase was carried out on two enzyme kits (Roche and Calbiochem), done as a direct method and a pre-incubation method. Variable results from commercial control sera and patient sera by these four procedures were obtained. Pre-incubation enzyme values were generally lower than the direct values (mean difference 10%), but there were marked differences between the results from the two kits. This finding has important significance especially for laboratories participating in external QC Programmes. Frequent precision checks of the method and a local reference range are therefore necessary.