Thesis (M.Sc.)--York University, 2003. Graduate Programme in Kinesiology and Health Science. / Typescript. Includes bibliographical references (leaves 113-122). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pMQ99371

Thesis (M.D.)--University of Hong Kong, 1990. / Also available in print.

Inaug.-Diss.--Marburg. / At head of title: Aus der Universitäts-frauenklinik zu Marburg (Lahn) ... Lebenslauf. "Literaturverzeichnis": p. 25-29.

Made available in DSpace on 2014-06-11T19:27:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2003Bitstream added on 2014-06-13T19:55:39Z : No. of bitstreams: 1 carmo_mt_me_botfmvz.pdf: 1897708 bytes, checksum: fa05c4ad728f9d308be62b06ac394c0f (MD5) / Vários estudos têm relatado que a égua é refratária a todas as drogas rotineiramente utilizadas, visando superovulação em outras espécies, como o FSH e o eCG (Mc Cue, 1996). O extrato de pituitária eqüina (EPE) é um preparado parcial de gonadotrofina eqüina, e o único composto que consistentemente induz ovulações múltiplas em éguas (Squires et al, 1999); contudo, a resposta superovulatória tem sido baixa (1-3 ovulações/égua) (Mc Cue, 1996). Estudos mais recentes demonstram uma melhora no percentual de ovulações múltiplas em éguas superovuladas com a administração do EPE duas vezes ao dia (4-7ovulações/égua), entretanto com baixa taxa de recuperação embrionária (Scoggin et al., 2002; Alvarenga et al., 2001). Este fato pode estar relacionado a produção de oócitos de baixa qualidade (anormalidade na maturação folicular e oocitária) (Dippert et al., 1994; Palmer et al., 1993), a falha do folículo em liberar o oócito e a dificuldade na captação do mesmo para o interior do oviduto, assim como o trânsito deste ou do embrião pelo oviduto (Dippert et al., 1994). O extrato de pituitária eqüina (EPE) foi preparado no laboratório do Departamento de Reprodução Animal e Radiologia Veterinária da Universidade Estadual Paulista (UNESP), campus de Botucatu - SP, através do método proposto por Guillon & Combarnous, (1983). Seis éguas em bom estado nutricional, com idade variando entre quatro e 15 anos e massa corpórea de 400 a 500 Kg, além de um bom histórico reprodutivo, foram monitoradas diariamente durante os períodos compreendidos entre os meses de novembro (2001) a março (2002). Foram utilizados dois ciclos estrais de cada égua subdivididos em dois grupos: doses constantes e doses decrescentes; porém entre os tratamentos esperou-se um intervalo de dois ciclos estrais. O experimento foi conduzido no posto de monta... / Several studies have reported the is unresponsive to all the routinely used drugs aiming the superovulation in other species, such as the FSH and the eCG. The equine pituitary extract (EPE) is a partial equine gonadotropin preparation, and the only compound which consintenty induces multiple ovulation in mares; however, the superovulatory response has been low (1-3 ovulations/mare). More recent studies demonstrate some improvement in the percentage of multiple ovulation in superovulated mares with the EPE administration twice a day (4-7 ovulations/mare), nevertheless with a low rate of embryo recovery. This fact can be related to the low quality oocyte production (abnormality in the follicular and oocytary maturation), the follicular failure in releasing the oocyte and its collection towards the inner part of the oviduct, as its or the embryo traffic through the oviduct. The improvement on embryo recovery rate has been shownin cows with the utilization of decreasing doses of FSH. The present experiment aimmed to compare the ovulatory answer and embryo production of mares treated twice daily with constant and decreasing doses of EPE. Six mares in good nutrition status, with ages ranging from four and 15 years old and weighing from 400 to 500 Kg, together with a good reproductive history, were monitored daily through the preiods between the months of november/2001 to march/2002. Two estrous cytrous cycles were used from each mare and subdivided into two groups: constant doses and decresing doses;however between the treatments na interval of two estrous cycles was given. The experiment was carried out in the riding station (UNESP), placed in Lageado, a farm in the city of Botucatu - SP. For both groups, the treatment was started in the seventh post-ovuatory day, presenting a very evident corpora lutea and follicles equal or under 25 mm of diameter in the... (Complete abstract, click electronic address below)

INTRODUÇÃO: O hipopituitarismo está associado, em cerca de 40% dos casos, à ectopia da neuro-hipófise observada em imagem por ressonância magnética (RM). Nestes pacientes a visualização da haste ocorre predominantemente nos que têm deficiência isolada de GH (DIGH), enquanto a não visualização da mesma está mais associada à deficiência hipofisária múltipla (DHM). A etiologia deste quadro, no entanto, permanece indeterminada na maioria dos pacientes. A elevada freqüência de parto pélvico e de complicações neonatais sugere uma causa traumática, enquanto que relatos de casos familiares, associação com outras patologias do SNC e descrição de mutações nos genes HESX1, LHX4 e SOX3 apontam para uma causa genética. O LHX4 é um fator de transcrição envolvido na embriogênese hipofisária fundamental para a formação da bolsa de Rathke definitiva. O LHX4 está localizado no cromossomo 1q 25, possui 6 éxons e estende-se por mais de 45 kb de DNA genômico. A única mutação publicada neste gene em humanos é a IVS4-1G>C, associada a um fenótipo caracterizado por baixa estatura, deficiências de GH, TSH e ACTH, neuro-hipófise ectópica e malformação Arnold-Chiari tipo I. O objetivo do estudo é analisar as regiões exônicas e éxon-íntron do LHX4 e caracterizar o perfil hormonal, correlacionando com os achados de RM, em 63 pacientes com hipopituitarismo associado a neurohipófise ectópica. MÉTODOS: Os pacientes foram submetidos à avaliação hormonal e por imagem através de ressonância magnética. A análise molecular incluiu amplificação do gene por PCR, seqüenciamento automático e uso de enzima de restrição. RESULTADOS: A visualização da haste ocorreu em 21 pacientes; destes, 10 (48%) apresentaram DIGH. A não visualização da haste foi mais associada a DHM, o que ocorreu em 40 (95%) dos 42 pacientes. Não encontramos diferença significativa quando comparamos pacientes com haste visualizada e não visualizada quanto à freqüência de partos vaginais em apresentação pélvica, à freqüência de malformações do SNC e à posição precisa da neuro-hipófise ectópica. Identificamos 6 variações alélicas no gene LHX4 em nossos pacientes: GGT>GGC, no códon 21; GAC>GAT, no códon 128; AAC>AAT, no códon 150; AGC>AGT, no códon 230; GGA>GGT, no códon 283 e AAT>AGT no códon 329 (N329S), esta já descrita como polimorfismo no GenBank. Nenhuma das outras variações determina troca de aminoácidos, altera o sítio de \"splice\" ou se correlaciona com um padrão de deficiência hormonal característico. As variações alélicas nos códons 21, 128 e 150 foram caracterizadas como polimorfismos. Não foi possível estabelecer uma relação entre as variações alélicas e o fenótipo dos pacientes. CONCLUSÃO: Mutações no LHX4 são causas raras de hipopituitarismo / INTRODUCTION: Ectopic posterior pituitary lobe (EPL) is observed using magnetic resonance imaging (MRI) scans in about 40% of patients with hypopituitarism. In these patients, the pituitary stalk is visualized mainly in patients with isolated GH deficiency (IGHD), whilst it is not visualized predominantly in patients with combined pituitary hormone deficiency (CPHD). Nevertheless, the etiology of EPL remains undetermined in most of the patients. A traumatic etiology is proposed for this figure, which presents a high frequency of breech delivery and perinatal damages. On the other hand, a genetic cause is suggested by associations to other CNS abnormalities and reports of gene mutations in HESX1, LHX4 and SOX3, as well as familial cases. LHX4 is a transcription factor implicated in pituitary embryogenesis which is essential to definitive Rathke\'s pouch development. It is located in chromosome 1q25, has 6 exons and is stretched out for more than 45 kb of genomic DNA. The only documented human mutation in this gene, IVS4-1G>C, is associated to a phenotype characterized by short stature, GH, TSH and ACTH deficiencies, EPL and Arnold-Chiari type I malformation. The aim of this study is to analyze exonic and exon-intron regions of LHX4 gene and characterize the hormonal deficiency profiles, establishing relationships to MRI findings in 63 patients with hypopituitarism associated to EPL. METHODS: All patients were submitted to hormonal evaluation and MRI scans. The molecular analysis included amplification of the gene using PCR, direct automatic sequencer and digestion with restriction enzymes. RESULTS: The pituitary stalk was visualized in 21 patients; of these, 10 (48%) exhibited IGHD. The stalk was not visualized in 42 patients, most of them with CPHD (95%). We did not find a statistical difference, when patients with and without visualized pituitary stalk were compared, regarding breech deliveries, CNS malformations and exact position of EPL. We identified 6 allelic variations in LHX4 gene: GGT>GGC in codon 21, GAC>GAT in codon 128, AAC>AAT in codon 150, AGC>AGT in codon 230, GGA>GGT in codon 283 and AAT>AGT in codon 329 (N329S), this already related as a polymorphism in GenBank. None of the former variations determine amino acid changes, nor splicing site changes, not even are related to a typical profile of hormonal deficiency. The allelic variations in codons 21, 128 and 150 were described as polymorphisms. It was not possible to establish a relationship between the allelic variations and the phenotype. CONCLUSION: LHX4 gene mutations are rare causes of hypopituitarism

No description available.

No description available.

The anterior pituitary gland is the major hormonal regulator in the body. The gland contains five secretory cell types whose emergence during development is defined by a tightly regulated array of transcription factors. In adult life, the gland is plastic with the relative proportions of cells varying depending on physiological context. Tumours of the pituitary gland account for 15% of all intracranial tumours in man and are caused by the selective proliferation of one of the secretory cell types. The majority of these (60%) are prolactinomas which consist of very slowly proliferating lactotroph cells, which produce the hormone prolactin. Pituitary tumours are almost never malignant and do not express common genetic markers for cancer, suggesting endogenous proliferative stimuli in the pituitary are the cause of tumour development. Oestrogen causes lactotroph hyperplasia during pregnancy and increases prolactin secretion. Our group previously showed that Wnt-4 mRNA was upregulated during oestrogen-induced lactotroph hyperplasia in Fischer 344 rats. Wnt molecules are key regulatory proteins controlling differentiation, proliferation and migration in development and adult life. Wnt-4 is involved in the emergence of lactotrophs during development, and has been implicated in pituitary tumour formation. Wnt molecules signal through three pathways. The well studied canonical pathway has been implicated in numerous cancers and centres around gene transcription initiated by translocation of β-Catenin into the nucleus. There are two non-canonical pathways: the Wnt-planar cell polarity (PCP) pathway and the Wnt-calcium pathway which are both poorly understood. In this thesis, the expression of Wnt-4 was studied in the pituitary, and effects of downstream signalling pathways in response to oestrogen were assessed. Wnt-4 was expressed in all secretory cell types of the pituitary, as well as the marginal zone (MZ), a region of the pituitary that may harbour stem cells. Oestrogen upregulated Wnt-4 protein in the somatolactotroph GH3 cell line, though this could not be replicated in primary tissue. A number of approaches (western blotting, immunofluorescence, reporter gene assays and mutant β-Catenin overexpression) were utilised to show that the canonical pathway was not activated in the pituitary. Wnt-4 had a clear inhibitory effect on calcium oscillations in GH3 cells, showing for the first time a non-canonical effect in the pituitary, though the downstream effects are currently unknown. Attempts made to study the activation of the PCP pathway were inconclusive. Efforts focused on the distribution of key structural and regulatory proteins in the anterior pituitary and the MZ. The MZ was characterised by a single layer of cells at the border of the anterior and intermediate lobes of the pituitary, with high expression of E-Cadherin and Sox 9, though no change in distribution was observed with oestrogen treatment. In the anterior lobe, oestrogen treatment decreased N and E-Cadherin expression, which could be an indicator of PCP pathway activation during oestrogen induced-lactotroph hyperplasia. Overall, data suggest that Wnt-4 does not directly cause oestrogen-induced lactotroph proliferation, but is likely to play a role in regulating tissue plasticity in the adult gland, as well as in the pathogenesis of pituitary tumours.

Xenopus Laevis has provided, during the last ten years, the basis of a growing body of physiological enquiries initiated by Jolly's research on reflex action. Its viability in the laboratory and amenability to operative procedure in particular, make it a peculiarly suitable object for investigation. It is regrettable therefore, that existing literature on the anatomy of Xenopus has been directed to elucidating those characteristics which are of especial interest to the Systematists and Morphologists rather than detailed information of a type which is essential to operative procedure. There is in particular no extant account of the endocrine system of Xenopus, although it is evident from superficial inspection that the suprarenal complex differs from that of the more familar Anura. The present enquiry concerns the Thyroid Gland, Pituitary and Epiphyseal Complexes with some observations concerning the possible occurrence of chromophil cells in the kidney of Xenopus laevis. The data have been placed on record specifically and constitution of these organs in physiological operations.

Although exocytosis is the major mechanism by which cells secrete products into their environment, little is known about the mechanism of this fundamental process. Previous studies on the regulation of luteinizing hormone (LH) exocytosis have used intact cells exclusively. It is not possible, however, to determine the precise requirements for exocytosis in intact cells since the cytosol is not directly accessible. Permeabilization of the plasma membrane allows experimental manipulation of the intracellular milieu while preserving the exocytic apparatus. The diameter of the atoxin pores (2-3 nm) allowed the exchange of small molecules such as ATP while larger cytosolic proteins such as lactate dehydrogenase were retained. Because of the slow exchange of small molecules through a-toxin pores a protocol was developed which combines prolonged pre-equilibration of the permeabilized cells at 0°C before stimulation with strong Ca²⁺ buffering. Under these conditions an increase in the [Ca²⁺]free stimulated a 15-20 fold increase in LH exocytosis (EC₅₀ pCa 5.5). After 12-15 minutes the rate of exocytosis declined and the cells became refractory to Ca²⁺. At resting [Ca²⁺]free (pea 7), cAMP stimulated a rapid, 2 - 3 fold, increase in LH exocytosis. cAMP caused a modest enhancement of Ca²⁺-stimulated LH exocytosis by causing a left shift in the EC₅₀ for Ca²⁺ from pCa 5.6 to pCa 5.9. Activation of protein kinase C (PKC) with phorbol 12-myristate 13-acetate (PMA) synergistically enhanced cAMP-stimulated LH exocytosis, an effect which was further augmented by increasing the [Ca²⁺]free· Gonadotrophin-releasing hormone (GnRH) was found to stimulate cAMP production in intact pituitary cells. Since previous studies have shown that GnRH activates PKC and stimulates a rise in cytosolic [Ca²⁺]free, these results suggest that a synergistic interaction of the cAMP, PKC and Ca²⁺ second messenger systems is of importance in the mechanism of GnRH-stimulated LH exocytosis. When permeabilized cells were equilibrated for prolonged periods in the absence of MgATP, Ca²⁺-stimulated LH exocytosis declined. The time course of the decline closely followed the leakage of intracellular ¹⁴C-ATP. Addition of MgATP rapidly restored full Ca²⁺-stimulated LH exocytosis. Ca²⁺-, cAMP-, and PMA-stimulated LH exocytosis were all dependent on millimolar MgATP concentrations (EC₅₀ 1 .5-3 mM). It has been postulated that PKC is a mediator of Ca²⁺- stimulated exocytosis. Several findings in the present study argue against this hypothesis. Firstly, PMA and Ca²⁺ had additive effects on LH exocytosis at all [Ca²⁺]free· Secondly, PMA was able to stimulate further LH release from cells made refractory to high [Ca²⁺]free· Thirdly, the PKC inhibitor staurosporine did not inhibit Ca²⁺-stimulated LH exocytosis under conditions in which it inhibited PMAstimulated exocytosis. Fourthly, in cells desensitized to PMA by prolonged exposure to a high PMA concentrations, Ca²⁺-stimulated LH exocytosis was not inhibited. And finally, Ba²⁺+ was able to stimulate LH exocytosis to a maximal extent similar to Ca²⁺ despite the fact that Ba²⁺+ is an extremely poor activator of PKC. Since Ba²⁺+ is also a poor activator of calmodulin, this latter result implies that calmodulin does not mediate the effect of Ca²⁺. In agreement with this, the calmodulin inhibitor calmidazolium did not inhibit Ca²⁺-stimulated LH exocytosis. Since GTP-binding proteins have been implicated in regulated exocytosis in other cell systems, the effects of guanine nucleotides on LH exocytosis were examined. At resting cytosolic [Ca²⁺]free (pea 7), the GTP analogues GTPyS and GMPPNP stimulated LH exocytosis with similar potencies (EC₅₀ 20-50 μM). Additional experiments indicated that the effects of these GTP analogues could not be explained by activation of either PKC alone or cAMP-dependent protein kinase alone. In the presence of both PMA and cAMP, GMPPNP did not stimulate a further increase in the rate of LH exocytosis, suggesting that the stimulatory actions of guanine nucleotides may be mediated by the combined activation of PKC and generation of cAMP, as a result of activation of signal-transducing G proteins. In contrast, pretreatment of cells with GTPyS at low [Ca²⁺]free markedly inhibited subsequent responses to Ca²⁺, cAMP, PMA, and cAMP plus PMA. This inhibitory effect required lower GTPyS concentrations than the stimulatory effect (IC₅₀ 1-10 μM), and was not observed with GMPPNP. These findings indicate the involvement of a distinct guanine nucleotide-binding protein in exocytosis at a site distal to second messenger generation.