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The results suggest that a low ratio of progesterone to E(2) is associated with menstrual irregularity and ovulatory status in PCOS.

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It was concluded that uncoupling of hypothalamic E2 inhibition by elevated ovarian A4 associated with E2 related sensitization of pituitary LH leads to neuroendocrine dysfunction in PCOS.

Does subtraction scintigraphy improve the diagnostic utility of scintigraphic evaluation in acute lower gastrointestinal hemorrhage? Methods: This research was a retrospective clinical study using a repeat-measures design of randomized control and experimental groups. A single patient dataset provided both the control group (conventional scintigraphy) and the experimental group (conventional and subtraction techniques). Forty-nine raw 99m Tc-red blood cell studies were randomized and interpreted by 4 independent physicians as conventional scintigraphy data only (round 1). The conventional scintigraphy studies were combined with subtraction images and randomized for reinterpretation (round 2). Results: Although there was a decrease in the mean, no statistically significant difference was noted between the mean time to bleed detection between interpretive rounds 1 and 2 (P 5 0.524). The addition of subtraction scintigraphy to the interpretation process changed the outcome from ''probably present'' to ''absent'' for 14% of patients and from ''equivocal'' to ''absent'' for another 12%, and this change had a marked effect on the false-positive rate. The false-positive rate decreased from 9.6% in round 1 to 3.6% in round 2. Receiver operator characteristic analysis showed that combining conventional scintigraphy with subtraction scintigraphy improved test performance. Conclusion: False-positive studies can be reduced by using subtraction scintigraphy in conjunction with conventional scintigraphy in the interpretive process.

Chromatographic methods (paper chromatography, thin layer chromatography, high performance liquid chromatography, gas chromatography and gas chromatography-mass spectrometry) for the determination of clinically important steroids in biological specimens are reviewed. The emphasis is on the use of gas chromatography, gas chromatography-mass spectrometry and high performance liquid chromatography as reference rather than routine techniques. Chromatographic methods are compared with colorimetric, fluorimetric and radioimmunoassay procedures in terms of simplicity of operation, cost and ability to analyse large numbers of specimens. The importance of correct specimen collection and storage are discussed. Sample preparation techniques for the various analytical methods are described. These include extraction of free and conjugated steroids from serum, plasma, urine and saliva by solvent partition, with polymer-based resins such as Amberlite XAD-2, DEAE-Sephadex and Sephadex resins bonded with various other function groups and, more recently, with chemically bonded reversed-phase silicas.

The choice of experimental animal can have a large impact on experimental results, an example is the anecdotal evidence suggesting that Dark Agouti (DA) rats have a lower reproductive capacity than other rat strains. In this paper we report on an investigation into male reproductive characteristics in three rat strains--Wistar, Sprague-Dawley (outbred strains) and DA (an inbred strain). Reproductive organ weights, blood testosterone levels and sperm counts were measured in mature age-matched male rats. DA animals had significantly smaller testis weights than the Sprague-Dawley and Wistar animals, and this did not appear to be related to the overall smaller body mass of the DAs. There were no differences between the three strains in testicular histology or sperm counts (per gram testis). Although there was also no significant difference in epididymal sperm count, the DA animals had a much greater variability in sperm count than the other strains. There were no differences in relative (to body weight) epididymal, seminal vesicle or ventral prostate weights or in the blood testosterone levels. These results suggest that differences in reproductive capacity in DAs are neither the result of morphological differences in the reproductive organs nor in circulating testosterone levels. Sperm production appears to be normal but the lowered testicular weight and variability in epididymal sperm counts suggests that there are other factors in the testicular or epididymal environment which alter male reproductive function.

The urogenital vasculature of the tammar comprises 4 major paired arteries and veins: the ovarian, the cranial urogenital, the caudal urogenital and the internal pudendal artery and vein. The ovarian artery and vein and their uterine branches which supply the ovary, oviduct and uterus, ramify extensively. Each anterior urogenital artery and vein supplies the caudal regions of the ipsilateral uterus, lateral and median vagina and cranial parts of the urogenital sinus. The caudal urogenital arteries and veins supply the urogenital sinus and caudal regions of the bladder. The internal pudendal artery and vein vascularize the cloacal region, with some anastomoses with branches of the external pudendal vessels. Anastomoses connect the uterine branch of the ovarian artery with the uterine branch of the cranial urogenital and cranial branches of the caudal urogenital arteries, and connect the caudal urogenital and the internal pudendal arteries. Anastomotic connections between the left and right arterial supply also occur across the midline of the cervical regions of the uteri and the anterior lateral vaginae. Similar connections are seen in the venous system. The uterine branch of the ovarian artery ramifies extensively very close to the ovary, giving a plexiform arrangement with the ovarian veins, and also with the uterine venous system on the lateral side of each uterus. This plexiform structure provides an anatomical arrangement which could allow a local transfer of ovarian hormones from ovarian vein into the uterine arterial supply, and thence to the ipsilateral uterus. Progesterone concentrations in plasma from the mesometrial side of the uterine branch of the ovarian vein are markedly higher than in tail vein plasma, especially during the 'Day 5 peak' early in pregnancy, and also at full term. There is also a marked decrease in progesterone concentration from all sites immediately before birth as previously reported for peripheral plasma. These results support the suggestion of a countercurrent transfer mechanism, at least for progesterone, and possibly other hormones, between the ovarian vein and uterine artery. Such a local transfer could explain the different morphological responses of the endometria of the two adjacent uteri during pregnancy in macropodid marsupial species.