Endocrinology: 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 investigatethe effects of ovulation induction with gonadotrophin on theactivation of the signal transducer effector system, adenylylcyclase (AC). For this purpose, we prepared membrane particlesfrom the ovary and analysed both gonadotrophin-sensitive ACand non-receptor-mediated activation during a cycle in whichovulation and luteinization were achieved by pregnant mare’sserum gonadotrophin (PMSG)/human chorionic gonadotrophin (HCG)administration. Results were directly compared with AC activationin similarly prepared membranes obtained at different stagesof the natural unstimulated cycle. AC activity was quantifiedby the direct conversion of ATP substrate into cyclic adenosinemonophosphate (cAMP). Measurements of ovarian weights, serumoestradiol and progesterone concentrations provided a solidbase from which to evaluate the functional status of the ovaryat each time period during the natural and stimulated cycles.We found that ovarian membranes contain functional componentsof the AC system and demonstrated that AC is highly dependenton hormonal changes and the functional state of the ovary. Thus,during the natural cycle, ovarian AC showed relatively constantresponsiveness to follicle-stimulating hormone (FSH) throughoutthe cycle, whereas responsiveness to luteinizing hormone (LH)/HCGreached its peak during the luteal phase. On the other hand,during the stimulated cycle, sensitivity to FSH and LH/HCG variedconsiderably, being absent during the peri-ovulatory period.AC responsiveness to gonadotrophins was only regained 48 h afterovulation. Also during the peri-ovulatory period of the gonadotrophin-inducedcycle, stimulation of ovarian AC with non-hormonal activatorsdeclined. However, the rate of cAMP production in response tothese activators remained very high, indicating that despiterefractoriness to gonadotrophins, ovarian AC retained the capacityto generate cAMP at near maximal efficiency. Basal (non-stimulated)activity, guanine nucleotide activation, hormone responsivenessand stimulation by the non-hormonal activators NaF and forskolinwere all significantly increased in comparison with the naturalcycle. Basal activity alone was 7-fold higher than the activityobserved during the unstimulated cycle. These results suggestthat subsequent to exogenous gonadotrophin administration, thetransmembrane effector AC system must be primed for a higherlevel of activity in the ovarian tissue. This priming of theovarian AC system by exogenous gonadotrophin was also evidentwhen the enzyme was measured under conditions allowing maximalactivity, i.e. in the presence of a combination of NaF and forskolin.Maximal AC activity increased 4- to 5-fold compared with thenatural cycle. We conclude that gonadotrophin administrationinducing ovulation causes profound alterations in the expressionof AC in ovarian membranes. Gonadotrophin treatment increasedthe enzyme activity and induced a temporal desensitization toFSH and LH/HCG in the peri-ovulatory period of the stimulatedcycle. Because the gonadotrophin-sensitive AC system representsthe capacity of FSH and LH/HCG receptors to couple and elicita biological response, our results provide new insights intothe cellular mechanisms that regulate ovarian activity duringinduction of ovulation.     

Growth hormone co-treatment for ovulation induction may enhance conception in the co-treatment and succeeding cycles, in clonidine negative but not clonidine positive patients

To investigate the effect of co-treatment with growth hormone(GH) for ovulation induction with human menopausal gonadotrophins(HMG) on conception, we compared the pregnancy rate and responseto co-treatment with GH versus HMG/human chorionic gonadotrophin(HCG) alone in a prospective, randomized, cross-over protocolof volation induction for either in-vivo or in-vitro fertilization(IVF). The main outcome measures were the amount of gonadotrophinused and conception. Co-treatment with GH was associated witha reduction of 30% in gonadotrophin requirement. In 24 clonidinenegative patients 14 pregnancies were achieved (58.3%) eitherin the GH/HMG/HCG cycle or in the succeeding one. GH co-treatmentdid not generate any pregnancy in eight clonidine positive patients.We conclude that growth hormone may increase the pregnancy ratewhen combined with HMG/HCG for ovulation induction, not onlyin the co-treatment cycle but also in the succeeding one. Thebeneficial, synergistic effect of GH co-treatment was detectedin clonidine negative but not in clonidine positive infertilepatients.     

Induction of follicular growth and production of a normal hormonal milieu in spite of using a constant low dose of luteinizing hormone in women with hypogonadotrophic hypogonadism

This study was designed to examine ovarian performance, i.e.follicular growth, normal steroidogenesis and luteal phase function,following the administration of multiple increasing doses ofhuman follicle stimulating hormone (FSH) with a constant lowdose of luteinizing hormone (LH) in women with isolated hypogonadotrophichypogonadism. Human meno–pausal gonadotrophin (HMG) wasused in the first treatment cycle, starting with 150 IU of LHand 150 IU of FSH per day, for 7 days. The dose was increaseddaily with 75 IU of LH and 75 IU of FSH for another 7 days ifno response was detected by serial ultrasound measurements andserumoestradiol determinations. In the second treatment cycle,a constant dose of 75 IU of LH (using HMG) was administeredper day and up to 150 IU of FSH (using urofollitrophin) wassupplemented. If no response was detected after 7 days of treatment,the dose of FSH was increased. For the final stage of ovulationinduction, human chorionic gonadotrophin (HCG) was administeredin the presence of at least one follicle >17 mm in diameterbut with no more than three follicles >16mm in diameter.To verify the adequacy of the luteal phase, a pharmacokinetic/pharmacodynamicstudy of -HCG, oestradiol and progesterone was performed followingthe second treatment cycle only. Ovarian stimulation using aconstant dose of 75 IU of LH and increasing doses of FSH upto 225 IU, resulted in normal follicular growth and hormonalmilieu. Both women showed normal luteal phase oestradiol andprogesterone production and both women conceived following thesecond treatment cycle     

Suppression of the endogenous luteinizing hormone surge by the gonadotrophin-releasing hormone antagonist Cetrorelix during ovarian stimulation

Surges of luteinizing hormone (LH) that result In luteinizationbut occur prematurely with respect to the diameter of the leadingfolilde, prevent attempts to induce multiple follicular maturationfor in-vitro fertilization (IVF) in a significant number ofwomen. We examined the possibility of blocking premature LIIsurges by the administration of Cetrorelix, a potent antagonistof gonadotrophin-releasing hormone (GnRH), in a study Including20 patients, some of whom had previously shown premature LHsurges. All patients were treated with human menopausal gonadotrophins(HMG) starting on day 2. From day 7 until the induction of ovulationby human chorionic gonadotrophin (HCG) the GnRII antagon Cetrorelixwas given daily. HCG was injected when the dominant fofficlehad reached a diameter of >18 mm and oestradlol concentrationwas >300 pg/ml for each follicle having a diameter of >15mm. Oocyte collection was performed 36 h later by transvaginalultrasound puncture, followed by IVF and embryo transfer. Thehormone profiles of these patients and the results of IVF andembryo transfer are comparable to those treated with GnRH agonistsand HMG. However, less time and especially less HMG Is neededin comparison to patients stimulated with a long agonist protocol.Hence, treatment with Cetrorelix proved to be much more comfortablefor the patient. In this study we showed that combined treatmentwith gonadotrophins and the GnRH antagonist Cetrorelix is apromising method for ovarian stimulation in patients who frequentlyexhibit premature LH surges and therefore fall to complete treatment.     

Maturation of medullary thymic epithelium requires thymocytes expressing fully assembled CD3-TCR complexes

Unlike meduilary thymic epithelial cells (TEC) of normal mice,meduilary TEC of TCR^– SCID mice are immature and disorganized.In order to assess directly the role of TCR⁺ cells in the developmentof medullary TEC, we bred mice which co-expressed the SCID geneticdefect and transgenes encoding clonotypic TCR chains. Immunohistologicexamination revealed that meduilary thymic epithelial cellsfrom TCRß transgenic SCID mice, whose thymocytes onlyexpress TCRß chains that inefficiently associate withCD3 and , components, remained immature and disorganized. Incontrast, meduilary TEC from TCRß transgenic SCIDmice, whose thymocytes express fully assembled CD3--TCRßcomplexes were mature and organized. Interestingly, the abilityof TCRß⁺-⁺-CD3³ thymocytes to induce maturation ofmeduilary TEC appeared not to be related to the antigen specificityof the TCR as thyml from positively selecting, negatively selectingand non-selecting TCRß transgenic SCID mice all possessedinduced meduilary thymic epithelial cells. In addition, we foundthat induction of meduilary TEC cells was associated with thepresence of meduilary thymocytes, including those of the CD4-CD8-TCRß⁺phenotype. The present findings demonstrate that fully assembledCD3--TCR complexes are required to induce maturation of meduilarythymic epithelial cells and indicate that thymocyte inductionof meduilary thymic epithelial cells may result from signalingindependently of their clonotyplc chains.     

Pilot study of the optimal protocol of low dose step‐up follicle stimulating hormone therapy for infertile women

Purpose

To evaluate the optimized protocol of low dose follicle‐stimulating hormone (FSH) therapy that has a starting dose of 50 IU/62.5 IU with a small increment dose (12.5 IU) for women with World Health Organization (WHO) II ovulatory disorder and unexplained infertility.

Methods

Anovulatory women with WHO group II ovulatory disorder (ovulation induction [OI] patients, n = 29), and with an unexplained infertility (ovarian stimulation [OS] patients, n = 21) were enrolled. The protocol of low dose step‐up FSH therapy was optimized for the starting dose as 50 IU (body mass index [BMI] < 20 group) and 62.5 IU (BMI ≥ 20 group) with the increment dose of 12.5 IU. Study outcomes were ovulation, monofollicular development and other variables.

Results

In the OIpatients, the ovulation rate was 100% (BMI < 20 group) and 90.9% (BMI ≥ 20 group). Monofollicular development was 80.0% (BMI < 20) and 77.3% (BMI ≥ 20). The pregnancy rate was 60% (3/5 BMI < 20) and 18.2% (4/22 BMI ≥ 20). There was no multiple pregnancy. In the OSpatients, the ovulation rate was 100%. Monofollicular development was 85.7% (BMI < 20) and 76.6% (BMI ≥ 20). No pregnancy was achieved in the OSpatients.

Conclusion

Optimized protocol of low dose FSH therapy setting a starting dose 50 IU/62.5 IU by BMI with an increment dose of 12.5 IU was safe and highly effective in WHO group II anovulatory patients. However, this protocol seemed uneffective for patients with unexplained infertility.     

天麻细粉和天麻素降血脂作用的实验研究

目的研究天麻细粉、天麻素的降血脂作用。方法采用金黄地鼠饲喂高脂饲料,分为正常对照组、高脂对照组(HF)、阳性对照组(舒降之)5.0mg/kg,天麻细粉125mg/kg、250mg/kg、500mg/kg、天麻素12.5mg/kg、25.0mg/kg、50.0mg/kg组,口服给药14d取血清测定总胆固醇(TC)、甘油三脂(TG)、高密度脂蛋白胆固醇(HDL-C)和低密度脂蛋白胆固醇(LDL-C)含量。结果天麻细粉和天麻素各剂量组均能降低高脂血症金黄地鼠血清中TC、TG、LDL-C含量,LDL-C/HDL-C比值、动脉硬化指数AI减小,均有显著性差异(P0.01及P0.05)。结论天麻细粉、天麻素具有降血脂作用。     

Anatomical and experimental study of the ductus venosus

Summary The authors report an anatomical study of the ductus venosus in the stillborn fetus based on resin-corrosion casts and angiography. Study in adult material was done by dissection. In the first part of this paper the classical anatomy of the ductus venosus is described and an anomalous case of a hepatic parenchymal bridge between the left and caudate lobes of the liver is reported. In the second part of this paper study of patency and dilation of the ligamentum venosum to a diameter exceeding 10 mm in adult cadavers is presented. A brief study of portal flow demonstrated that an increase in flow of 30% can be obtained by experimental induction of patency. A patent ligamentum venosum was grafted onto the abdominal aorta in the rabbit. The transplanted segment was fully patent and competent immediately after grafting, but showed thrombosis when the animal was sacrified two months after the operation. In the opinion of the authors, it may be possible to use the patent ductus venosus in man once the problems of long term resistance and patency have been solved. The latter problems are currently under investigation in our laboratory.

---

Etude anatomique et expérimentale du canal d'Arantius ou ductus venosus

Résumé Les auteurs rapportent une étude anatomique du canal d'Arantius chez le ftus mort-né, à partir de moulages et d'angiographies, et chez l'adulte à partir de dissections. Ils rappellent l'anatomie classique du Canal d'Arantius et rapportent un cas de pont parenchymateux hépatique entre le lobe gauche et le lobe de Spiegel. Dans une deuxième partie ils réalisent des reperméabilisations et des dilatations jusquá un diamètre de plus de 10 mm sur des cadavres d'adulte. Une courte étude débitmétrique a montré la possibilité d'augmenter le débit portal de 30 %. Un ligament veineux reperméabilisé a été utilisé comme greffon sur une aorte abdominale de lapin. Perméable et étanche d'emblée, il est retrouvé thromboséá deux mois. Les auteurs pensent possible l'utilisation du ligament veineux reperméabilisé chez l'homme lorsqu'auront été résolus les problèmes de résistance et de perméabilité à long terme. Une étude est en cours.

     

Suppressive Effect of Pregnancy on the Development of Experimental Allergic Encephalomyelitis in Rabbits

ABSTRACT: In the present study we have investigated the influence of pregnancy on the induction and development of experimental autoimmune encephalomyelitis (EAE) in rabbits in relation to the time of gestation. Randomly bred rabbits were immunized with encephalitogenic bovine brain homogenate in complete Freund's adjuvant before or during pregnancy. The appearance of EAE was delayed and occurred only after delivery, abortion, or fetal resorption. The incidence of the disease was lower and the duration longer. The levels of antibodies to myelin basic protein, an autoantigen of EAE, as measured by solid phase radioimmunoassay, were lower in the pregnant rabbits as compared to the nonpregnant animals. The suppressive influence of pregnancy on the induction and the development of EAE confirms previous reports demonstrating amelioration of autoimmune diseases and other immunological reactions during the second half of human pregnancy. This effect might be partially attributed to the increased level of alpha-fetoprotein (AFP) and/or other pregnancy-associated factors in maternal serum.