Changes in expression of adenyl cyclase activity in human endometrium during hormone replacement therapy and ovarian stimulation.

We have investigated membrane fractions prepared from human endometrium for activity of the signalling adenyl cyclase (AC). We characterized the AC guanine nucleotide-binding proteins (G proteins) and examined the changes in AC activity during evaluation cycles of oestrogen and progesterone replacement therapy as well during ovarian stimulation cycles. AC activity was determined by the conversion of substrate ATP into cyclic AMP under basal conditions and in the presence of guanine nucleotide or forskolin.

Melatonin and other antioxidants prolong the postmortem activity of the outer hair cells of the organ of Corti: its relation to the type of death.

The outer hair cells of the organ of Corti transform sound into electrical signals, beginning the nervous auditive process. These cells produce acoustic emissions when working routinely, known as otoacoustic emissions. Otoacoustic emissions (OAEs) are recorded from the hearing duct through a probe which incorporates a sound source and a sensitive microphone.

Mechanisms of gastroprotection by transdermal nitroglycerin in the rat.

Nitric oxide (NO) donors prevent experimentally-induced gastric mucosal damage, but their clinical utility is limited by short duration of action or unsuitability of the pharmaceutical form employed. This study analyses the gastroprotection elicited by a clinically used mode of continuous administration of an NO donor, namely the nitroglycerin patch. Application to rats of a transdermal patch that releases doses of nitroglycerin comparable to those used in man (40, 80, 160 and 400 ng min(-1) rat(-1)) reduced gastric damage induced by indomethacin (25 mg kg(-1), p.

Calpain-calpastatin: a novel, complete calcium-dependent protease system in human spermatozoa.

Calpain, a calcium (Ca2+)-activated cysteine protease presents in several somatic mammalian cells, has been demonstrated to mediate specific Ca2+-dependent reactions including cell fusion. Because spermatozoa cells have an absolute Ca2+ requirement for penetration of oocytes, we have postulated that calpain would also be found in mammalian spermatozoa. Here we show that whole sperm homogenate and cell fractions prepared from ejaculated human spermatozoa contain calpain activity.

Electrochemical treatment of human KB cells in vitro.

Electrochemical treatment (ECT) of cancer is a promising new method by which direct current is delivered into tumor tissue to induce tumor regression. The purpose of this study is to evaluate the effectiveness of ECT on human cancer cells and to investigate the factors that affect ECT. The biological mechanisms of ECT in cancer treatment were also explored.

Insulin signalling in heart involves insulin receptor substrates-1 and -2, activation of phosphatidylinositol 3-kinase and the JAK 2-growth related pathway.

Objective: Hyperinsulinemia is a common feature of obesity and hypertension and may be associated with abnormal metabolism and growth of heart muscle and vascular wall. Most of the known actions of insulin were characterised in muscle, adipose tissue and liver. In this study we investigate the initial steps of insulin signalling in rat heart.

Platelet activation In mice and human Helicobacter pylori infection.

Extracts of Helicobacter pylori (HP) have been shown to induce leukocyte adhesion in mesenteric venules, but the effects of HP infection on gastric microvessels are unknown. Inflammatory cell interactions in the gastric microcirculation were studied by intravital videomicroscopy in mice inoculated with either saline or fresh isolates of HP. Platelet aggregates were detected and quantified in murine portal blood, while endothelial P-selectin expression was determined using the dual radiolabeled mAb technique.

Serum levels of androstenedione, testosterone and dehydroepiandrosterone sulfate in patients with premature ovarian failure to age-matched menstruating controls.

Serum concentrations of androstenedione, testosterone and dehydroepiandrosterone sulfate (DHEAS) were measured in 29 patients with premature ovarian failure (POF) and an identical number of age-matched normal control subjects. The study was aimed at determining possible differences in androgen concentrations of ovarian and adrenal origin in POF patients and age-matched normal menstruating controls. Serum testosterone and DHEAS concentrations in the 2 populations were not significantly different.

Determination of zinc by flow injection with fluorimetric detection in a micellar medium.

A room-temperature flow injection spectrofluorimetric method is presented for the determination of Zn(II), based on the use of salicylaldehyde thiocarbohydrazone in the presence of Triton X-100 and sodium acetate-acetic acid buffer. Various physical and chemical variables affecting the reaction in the flow system were evaluated. The proposed method is very selective.

Evidence that hormone receptors couple and activate a common signal transducer adenylyl cyclase in corpus luteum.

Objectives: To investigate whether membrane-bound hormone receptors in corpus luteum (CL) couple to one common adenylyl cyclase (AC) or whether each receptor is coupled to its own AC.

Design: Plasma membranes from rat CL were used to assess the coupling of hormone receptors to AC under conditions allowing full expression of the enzyme system. The response to hCG, prostaglandin E2 alpha (PGE2), and isoproterenol were analyzed.

Recent developments in derivative ultraviolet/visible absorption spectrophotometery.

The instrumental development and analytical applications of derivative ultraviolet/visible region absorption spectrophotometry produced in the last seven years (since 1987) are reviewed.

Enzymatic amplification of specific deoxyribonucleic acid sequences from single cells: evaluation of a simplified and rapid method for use in preimplantation genetic diagnosis.

Objective: To develop a simplified polymerase chain reaction (PCR) protocol on single cells for the purpose of preimplantation genetic diagnosis. Also to evaluate a new thermal cycler, RoboCycler 40 (Stratagene, La Jolla, CA), for reducing the time to complete PCR amplification.

Design: PCR amplification without DNA purification or reamplification of a 149 base pair (bp) segment of the human Y chromosome was used as a model.

Status of hCG/LH receptor and G proteins in human endometrium during artificial cycles of hormone replacement therapy.

Objectives: We examined the existence of hCG/LH receptors and associated GTP-binding (G) proteins in membrane fractions of nonpregnant human endometrium and investigated whether their expression is affected, in vivo, by estrogen and progesterone replacement therapy.

Methods: A pool of normal endometrial biopsy specimens (n = 5) was initially used to characterize receptors and G proteins. Subsequently, biopsy specimens (n = 22) were obtained from 11 patients undergoing evaluation cycles of hormone replacement therapy (HRT).

Relationship between serum estradiol concentration and IGF-I, IGF-II and IGF-binding proteins in patients with premature ovarian failure on short-term estradiol therapy.

Objective: Insulin-like growth factors (IGFs) exert stimulatory effects on follicular growth and development, and early embryogenesis. In view of this, we studied the effect of short-term estradiol treatment, as used in preparing the uterus for embryo implantation, on the serum concentrations of IGFs and their binding proteins (IGFBP) in patients with premature ovarian failure (POF).

Patients And Methods: Twenty-four patients with POF, enrolled in an assisted reproduction program, were treated with increasing doses of estradiol up to 8 mg daily for 6 weeks.

Stimulation of ovarian adenylyl cyclase activity by gonadotrophins during the natural and gonadotrophin-induced cycles in the hamster.

In this study we utilized the hamster ovary as a model to investigate the effects of ovulation induction with gonadotrophin on the activation of the signal transducer effector system, adenylyl cyclase (AC). For this purpose, we prepared membrane particles from the ovary and analysed both gonadotrophin-sensitive AC and non-receptor-mediated activation during a cycle in which ovulation and luteinization were achieved by pregnant mare's serum gonadotrophin (PMSG)/human chorionic gonadotrophin (HCG) administration. Results were directly compared with AC activation in similarly prepared membranes obtained at different stages of the natural unstimulated cycle.

The predictive value of a single beta human chorionic gonadotropin in pregnancies achieved by assisted reproductive technology.

Objective: To investigate whether a single serum beta-hCG in pregnancies achieved by assisted reproductive technologies (ART) can accurately predict pregnancy viability and, in viable pregnancies, multiple gestation.

Design: Four hundred sixty-one consecutive successful ART pregnancies were studied retrospectively. Seventy-one of the 461 patients were excluded because their beta-hCG was either drawn on the incorrect day or outside our facility.

Evidence for a novel adenylyl cyclase in human epididymal sperm.

Since cAMP is considered to play a major role in the acquisition of maturation and fertilizing capacity of mammalian sperm, we investigated the expression of cAMP-synthesizing adenylyl cyclase (AC) in sperm retrieved directly from the human epididymis. Particulate fractions were prepared from purified epididymal sperm samples and AC was monitored by the direct conversion of ATP into cAMP. We report that in great contrast to human ejaculated sperm and other mammalian sperm cells, the human epididymal sperm do not express a Mn(2+)-sensitive AC.

Mycoflora and toxigenic Aspergillus flavus in Spanish milks.

The isolation, enumeration and identification of moulds were carried out on 64 samples of raw milk and 33 of pasteurized milk. The genera most frequently isolated in the raw milk were: Geotrichum (76.5%), Fusarium (45.

Melatonin and gonadotropin secretion after acute exercise in physically active males.

Serum concentrations of luteinizing hormone (LH), follicle stimulating hormone, testosterone (T) and melatonin were measured in seven physically active male volunteers after exercise on a treadmill using the Bruce protocol. Measurements were made on blood samples obtained before exercise, within 30 s after exercise, at 15 min after exercise, and subsequently at 30-min intervals after exercise for a total duration of 180 min. Serum LH concentration fell from a peak post-exercise level of 15.

Penetration of zona-free hamster oocytes using human sperm aspirated from the epididymis of men with congenital absence of the vas deferens: comparison with human in vitro fertilization.

Objectives: To assess the ability of sperm aspirated from the epididymis of men with congenital absence of the vas deferens to penetrate zona-free hamster oocytes. To directly compare the performance of human epididymal sperm in the zona-free hamster oocyte sperm penetration assay (SPA) with the results of human in vitro fertilization (IVF).

Design: Sperm penetration assay was carried out with epididymal sperm retrieved microsurgically, and with ejaculated sperm obtained from fertile donors (internal controls).

Regulation of cyclic adenosine monophosphate synthesis in human ejaculated spermatozoa. II. The role of calcium and bicarbonate ions on the activation of adenylyl cyclase.

In this study, we have applied our previous data describing the experimental conditions necessary for expression of cyclic adenosine monophosphate (cAMP)-synthesizing adenylyl cyclase in human ejaculated spermatozoa, to investigate the direct effects of calcium (Ca2+) and bicarbonate (HCO3-) upon activation of the enzyme in vitro. We report that the effects of Ca2+ and HCO3- were significantly dependent on the status of the enzyme activity. Thus, at a near saturating (10 mM) concentration of MnCl2 giving high enzyme activity, addition of less than 10 mM HCO3- did not affect adenylyl cyclase activity and higher concentrations inhibited the enzyme, with 50 mM HCO3- reducing the activity by 33%.