Дисертації з теми "Endocrine changes"

The effect of forced molt on pituitary function and other endocrine parameters was investigated in three year old hens subjected to a dietary forced molting procedure. In addition to molting, fasting caused cessation of egg production, body and organ weight loss, alterations in hormone secretion and morphological changes in some endocrine glands. Body and ovary weights decreased but returned to normal with ad libitum feeding. Pituitary, thyroid and adrenal weights were not affected but serum hormone levels measured by RIA revealed a decrease in LH, FSH and PRL and increases in TSH, T₃ and GH all of which returned to higher levels with ad libitum feeding. Serum P₄ levels remained low (and egg-laying stopped) until ad libitum feeding was resumed and then increased and egg-laying returned to a typically productive level. Serum ACTH and T₄ increased with fasting and remained elevated. Gonadotrophs and corticotrophs increased in numbers with fasting and/or food restriction but thyrotrophs, somatotrophs and lactotrophs decreased. Correlations between cell populations and serum hormone levels was quite common. Colloid-filled follicles resembling a hypertrophic thyroid gland occurred throughout the pituitary pars distalis. Granules appear to be discharged into the follicular lumen through exocytotic pores in the apical plasmalemma of follicular cells. Lactotrophs, corticotrophs and somatotrophs are commonly arranged in follicles or clusters. PRL-containing granules are in the center of some follicles and are concentrated near pituitary cysts. Pituitary cysts, lined with ciliated epithelium and sparse mucous cells, are more prevalent in fasted hens and decline with the resumption of feeding. Reduced lactotroph populations and presumptively degenerated lactotrophs in cyst lumens are correlated with reduced serum PRL levels. Necrotic cells occurred in the pituitary parenchyma of fasted birds but dilated RER in the thyrotrophs of fasted hens indicate enhanced activity of these cells. Ultrastructural evidence presented here indicates that pituitary secretion by lactotrophs occurs both intraluminally and perivascularly.

Anti-oestrogens and aromatase inhibitors are currently used as endocrine therapies in breast cancer. Despite the significant role that these treatments play in reducing breast cancer mortality, some patients may display intrinsic and acquired therapeutic resistance. Different mechanisms are thought to contribute to endocrine resistance in patients treated with anti-oestrogens such as tamoxifen and aromatase inhibitors such as letrozole. The importance of epithelial-stromal interactions in progression of breast tumour and the potential contribution of these interactions in resistance to tamoxifen have been suggested using data from different studies. Stromal compartment has also been shown to exhibit possible prognostic and therapeutic significance in breast cancer. Therefore it is essential to acquire better understanding of the changes in stromal and epithelial cells that occur during successful and unsuccessful endocrine treatment. In this study an important trial in which patients received tamoxifen for short windows was under investigation. Biopsies were taken from these patients before and after treatment. These biopsies were available as formalin-fixed paraffin-embedded (FFPE) tissue blocks. Responding and non-responding patients were identified according to the Ki67 scores. Laser Capture Microdissection (LCM) was utilised to microdissect epithelial and stromal cells from the biopsies taken after treatment. The samples obtained following microdissection underwent RNA extraction and were subsequently used for gene expression profiling. Several differentially expressed genes in the epithelial and stromal compartments of tamoxifen responding and non-responding cases were identified. To assess the significance of the differentially expressed genes between the non-responding and responding cases, bioinformatics approaches were employed to incorporate the acquired data into functional enrichment analysis, pathway analysis and network construction. To examine the presence of possible predictive markers for therapeutic response and potential targets for therapy in breast cancer within the differentially expressed genes, data was compared to several published gene sets and publicly available datasets. Several significant genes involved in recognised pathways and networks were identified within the list of differentially expressed genes. The presence of previously proposed possible markers within the differentially expressed genes was also confirmed. These findings can be further explored for the future management of breast cancer.

Abstract The prevalence of the isolated ultrasonographic finding of polycystic ovaries (PCO) in the Finnish population and among women with a history of gestational diabetes (GDM) and changes in the present carbohydrate metabolism were investigated in the present study. One aim of this study was to investigate the prevalence of the recently discovered variant type LH (v-LH) in PCOS and to compare patient cohorts from Finland, the Netherlands, the United Kingdom and the United States of America. In addition, this study attempted to evaluate the nature of the ovarian streoidogenic response of women with PCOS to exogenously administered human chorionic gonadotrophin (hCG), human menotrophin (hMG) and follicle stimulating hormone (FSH). The effect of metformin on ovarian steroidogenesis was also studied. The prevalence of PCO was significantly higher in younger (≤ 35 years, 21.6%) than among older women (in ≥ 36 years, 7.8%). The overall prevalence of PCO in Finnish women was 14.2%. Women with previous GDM revealed a high prevalence of PCO (39.4%). The carrier frequency of the v-LHb allele in the entire study population was 18.5%. The frequency of the v-LH carrier was significantly lower in obese PCOS subjects in the Netherlands (2.0%) and Finland (4.5%). Women with previous GDM had impaired insulin sensitivity and β-cell function. They also had higher adrenal androgen secretion than the control women. Women with PCO and previous GDM had marked hyperinsulinemia which was not explained by obesity. Obese PCOS women achieved peak peripheral serum T concentrations at 48 hours after a hCG injection, preceded by peak levels of 17-OHP and E2 at 24 hours. In contrast, all steroids measured in the control women reached their maximum serum concentrations at 96 hours. HMG stimulated the production of ovarian androgens more efficiently than a urinary FSH after pituitary suppression with a gonadotrophin releasing hormone agonist (GnRHa). In conclusion, the prevalence of PCO is common in healthy Finnish women and even more common in women with a history of GDM. The ultrasonographic appearance of PCO may be a predictive factor with regards abnormal glucose tolerance during and after pregnancy and, these women should therefore be advised as to possible consequences. The high overall frequency of the v-LH allele in women in general and its low frequency in obese PCOS patients suggests that v-LH plays a role in reproductive functions and may counteract the pathogenesis of PCOS in obese individuals. The differences observed in steroid responses to hCG between normal and PCOS women might be explained by higher theca cell activity or mass in polycystic ovaries. Women with PCOS did not show a distinctly exaggerated steroidogenic response to hMG or FSH administration compared with control women. FSH administration also resulted in increased A and T production.

Bisphenol A (BPA) is an estrogen receptor binding chemical, widely used in the plastics industry, and as such commonly encountered from plastic containers etc. Even at very low doses, BPA is believed to induce obesity and to have various endocrine disruptive effects. The purpose of this study was to determine possible gene expression changes in gonadal and inguinal adipose tissue from rats perinatally exposed to BPA. The method used was quantitative real-time PCR, and genes found to be up-regulated were PLZF, adiponectin, RXRa and Tcf21, while down-regulated genes were PPARγ, Tmem26, EsR1, Resistin, LPL, Chemerin, Serpina6, TFAM and Ahr. This is so far largely unsupported by other studies, and more research is needed.

Vinclozolin (VCZ), an antiandrogenic fungicide, is an endocrine disrupting chemical that is known to possess high affinity for the androgen receptor (AR) and modulate expression of critical androgen-dependant genes in the prostate. In this study, viability and expression of AR, NKX3.1 and CYP3A4 genes were measured in androgen-sensitive prostate cells LNCaP after exposure to VCZ and VCZ treated with S9 microsomes in a time and dose dependent manner. NKX3.1 is an androgen regulated gene that plays a vital role in prostate development. CYP3A4 is involved in xenobiotic metabolism. VCZ decreased the viability at high doses after 48 hours which was slightly mitigated by treatment with S9 metabolites. Expression of NKX3.1 and CYP3A4 was upregulated while an initial downregulation of AR was observed. NKX3.1 upregulation corroborates with possibility of antiandrogens to act as androgens in LNCaP. The results illustrate that VCZ can interfere with the expression of critical prostate genes.

Endocrine disrupting compounds (EDCs) together with potentially toxic metals (PTMs), are present in large amounts in sewage sludge which was used as a tool to expose terrestrial molluscs to environmental concentrations of these pollutants. Pastures fertilised with sewage sludge had significantly fewer adult slugs collected per replicate (C: 58.4; T: 26.2; S.E.D. 0.14; p<.05) and eggs (C: 16.6; T: 9.1; S.E.D. 0.17; p<0.05).  No differences with treatment, in tissue concentrations of EDCs or PTMs or in hepatopancreas or gonad structure, were detected.  However, hepatopancreatic proteins (cyclophilin, paramyosin and trypsin) were significantly altered (p<0.01). In a laboratory study, exposure, via feed, to 0x (Control), 1x (T1), 10x (T2) or 110x (T3) the environmental dose of sludge extract resulted in a dose-related increase in mean mortality rates (relative to controls) in adult slugs (Deroceras reticulatum).  Exposure for 3 weeks induced no measurable differences in tissue pollutant concentrations or hepatopancreas or gonad histology. Fewer slug eggs exposed to sludge and/or dehydration (2x2; 10 eggs/replicate); hatched following sludge exposure (C hydrated 64.5%;T hydrated 24.5%; p<0.05; S.E.D. 2.169; C dehydrated 48.9%; T dehydrated 17.4%; p<0.05; S.E.D. 4.256) but not following dehydration.  There was no significant interaction between sludge exposure and dehydration but survival was lowest in animals exposed to both. Slug behaviour was affected by exposure to sludge, including increasing avoidance and huddling behaviours. The results indicate that terrestrial molluscs may be used as invertebrate sentinels to assess the effects of ECD and PTM exposure.

Dissertation (PhD)--University of Stellenbosch, 2003.
ENGLISH ABSTRACT: Concern has increased that widespread adverse effects are occurring in humans and wildlife populations as a result of exposure to environmental chemicals (mostly man-made) that disrupt the normal functioning of the endocrine system. Many pharmaceutical, agricultural and industrial chemicals, acting as endocrine modulating compounds (EDCs), have been detected in an accumulated form in food, in drinking water and in the environment. Although the levels of these chemicals can be measured analytically, it is important to evaluate biological activity. For this, animal models are used and relevant bioassays developed. These assays are based on biological markers, which are specific xenobiotically-induced physiological responses and are usually deviations in cellular or biochemical components, processes or structures. Vitellogenin is a large protein complex, produced in the liver under estrogen control and circulates in the plasma, destined for incorporation into the developing oocyte in female oviparous vertebrates. Since vitellogenin production is low or nonexistent in males, its presence may therefore be interpreted as evidence of exposure to estrogenic environmental contaminants. In this study the African Clawed Frog, Xenopus laevis was used as model to study the effects of estrogens on biochemical and physiological parameters associated with vitellogenesis. As a starting point the seasonal female reproductive cycle in a natural Xenopus laevis population in terms of ovarian state, plasma vitellogenin and plasma estrogen levels was studied. It was shown that plasma vitellogenin and estrogen levels were seasonal and correlated to a seasonal ovarian cycle, which peaked during spring. However, although seasonality existed, there were reproductively active individuals at any time during the year. Increases in plasma estrogen levels predated increases in plasma vitellogenin levels and ovarian maturation. Lipoprotein profiles, as well as plasma cholesterol, triglyceride and phospholipid concentrations were determined and it was shown that estrogen affected these in such a way that these parameters could be used as additional markers in estrogen contamination studies. In order to develop an in vitro bioassay to screen for estrogenic activity, the use of hepatic tissue cultures was investigated. Optimal culture conditions were established and increased sensitivity in the estrogenic response was obtained by using liver slices from male frogs that were pre-treated with estrogen. Validation studies proved that this bioassay could be employed for routine screening of water and chemical samples. In order to refine the Xenopus laevis vitellogenin ELISA and liver slice bioassay, existing polyclonal anti-vitellogenin antibodies were replaced by culturing monoclonal antibodies. Selected antibodies were characterised and ELISAs developed and validated. This study showed that the newly developed Xenopus laevis vitellogenin ELISA and liver slice bioassay have the potential to be employed in environmental monitoring programmes.
AFRIKAANSE OPSOMMING: Daar is toenemende besorgdheid dat afwykings in mens- en dierbevolkings voorkom as gevolg van blootstelling aan chemikalieë (hoofsaaklik mensgemaak) in die omgewing wat die normale werking van die endokrienstelsel versteur. Verskeie farmaseutiese, landbou- en industriële chemikalieë, wat as endokrienversteurders optree, is in die omgewing gevind. AI kan die vlakke van hierdie stowwe analities bepaal word, is dit belangrik om hulle biologiese aktiwiteit te evalueer. Hiervoor word diermodelle aangewend om toepaslike toetse daarvoor te ontwikkel. Hierdie toetse word baseer op biologiese merkers, spesifieke xenobioties-geïnduseerde fisiologiese reaksies, en is gewoonlik afwykings van sellulêre- of biochemiese komponente, -prosesse of - strukture. Vitellogeen ('n dooiervoorloper) is 'n lipoproteïenkompleks wat, onder estrogeenbeheer, in die lewer vervaardig word en in die plasma sirkuleer vir uiteindelike inkorporasie in ontwikkelende oësiete van vroulike, ovipare werweldiere. Aangesien daar min of geen vitellogeen in manlike diere geproduseer word, is die teenwoordigheid daarvan 'n aanduiding dat die dier aan estrogeniese omgewingsbesoedeling blootgestel is. In hierdie studie is die Platanna, Xenopus laevis, as model gebruik om die gevolge van estrogene op biochemiese en fisiologiese veranderlikes, wat met vitellogenese geassosieer word, te bestudeer. As vertrekpunt is die seisoenale voortplantingsiklus van die wyfie, in terme van vitellogeen en -estrogeen vlakke in die plasma en aktiwiteit van die ovaria bepaal. Daar is aangetoon dat die estrogeen- en vitellogeenvlakke in die plasma met die ovariumsiklus, wat gedurende die lente hoogtepunte bereik, korreleer. Alhoewel daar seisoenaliteit bestaan, was daar dwarsdeur die jaar wyfies wat ovarium dooierneerlegging getoon het. Verhoging in estrogeenvlakke het vitellogeenpieke en rypwording van die ovaria voorafgegaan. Lipoproteïenprofiele, sowel as die cholesterol- , trigliseried- en fosfolipiedkonsentrasies in die plasma is bepaal en daar is aangetoon dat estrogeen hierdie medeveranderlikes in só 'n mate affekteer dat hulle as bykomende biomerkers vir estrogeenblootstelling in besoedelingstudies gebruik kan word. In vitro Xenopus laevis lewersnitte in die weefselkultuur omgewing is ondersoek om 'n biotoets te onwikkel vir die gebruik in vinnige estrogenisiteits-toetsing van watermonsters en chemise stowwe. Die mees gunstige kultuurtoestande is bepaal en die sensitiwiteit van estrogeenreaksies is verhoog deur lewer van mannetjies, wat vooraf met estrogeen behandel is, te gebruik. Hierdie biotoets se geldigheid is gestaaf en kan in roetine eerstevlaktoetsing van watermonsters gebruik word. Die gebruik van poliklonale teenliggaampies in 'n bestaande enzyme-linked immunosorbent assay (ELISA) is vervang deur spesiaal-ontwikkelde monoklonale anti-Xenopus laevis vitellogeen teenliggaampies. Uitgesoekte teenliggaampies, spesifiek teen die estrogeengeïnduseerde proteïene, is gekarakteriseer en ELISAs saamgestel en die geldigheid gestaaf. Hierdie studie het aangetoon dat die nuut-onwikkelde Xenopus laevis vitellogeen-ELISA en lewerkultuurbiotoets die potensiaal het om In omgewingsmoniteringprogramme gebruik te word.

Objectives: A decrease in Ki67 during neoadjuvant therapy predicts response to tamoxifen. Previous trials have shown a decreased Ki67 in breast tumors with as little as two or more weeks of preoperative tamoxifen. Shortening the preoperative treatment time in window of opportunity clinical trials makes these trials more attractive to women. POWERPIINC examined the effect of 7 days of preoperative tamoxifen on breast tumor proliferation and patient symptoms. Methods: Women with untreated stage I/II, ER-positive, invasive breast cancer with no contraindications to tamoxifen were enrolled. Women received 20 mg of tamoxifen for 7 days up to the day of surgery. Proliferation was assessed by Ki67 immunohistochemistry before and after 7 days of tamoxifen. Symptoms and QOL were assessed by the FACT-ES and MENQOL. Adherence was measured by pill counts. Results: 52 women were enrolled, and 44 were evaluable for Ki67. The median age was 58.5 years, and the median tumor diameter was 1.2 cm. Most women (73%) were post-menopausal. Most tumors were PR positive (88%) and HER2-negative (92%). The Ki67 decreased by a geometric mean of 40% (95% CI 29%-63%), and 73% (95% CI 57%-85%) of women had tumors with decreased proliferation (p = 0.0001 by paired t-test). Adherence to taking tamoxifen during the preoperative period was 100%. Women reported minimal bother from psychosocial or physical symptoms at baseline or on the day of surgery. Conclusion: Seven days of tamoxifen showed a similar relative decrease in Ki67 as that reported for longer courses, was acceptable to women, and could be considered for window of opportunity studies.

Climate change and endocrine disrupting chemicals are currently amongst key drivers for a range of non-communicable diseases and adverse human health conditions. Pesticides constitute an important source of endocrine disrupting chemicals. A growing public health concern is the potential relationship between climate change and adaptive increases in agricultural pesticide use. Effectively, with increases in pesticide use, there may be increased potential for elevated pesticide exposures and, thus, increased endocrine disrupting health risks. The aim of this thesis was to assess whether climate change is a key risk perpetuating factor for endocrine disrupting health risks due to increased agricultural pesticide uses and exposures. The study was conducted in Zimbabwe with farmers in the cotton farming district of Rushinga. Three research methods: 1) interviews with farmers, 2) quantitative structure-activity relationship modelling and, 3) stakeholder interviews with government cotton agronomists working in Rushinga district who acted as key informants. Qualitative in-depth interviews were conducted with 50 active smallholder farmers who had grown cotton for a minimum of 30 years. The interviews gathered farmers' perceptions and observations regarding climate change, changes in pest types, pest populations, pesticide use patterns, pesticide handling practices, and adaptive practices, amongst others. Quantitative structure-activity relationship modelling was, further, applied in identifying key risk pesticides of concern. Amitraz, endosulfan, fenvalerate and lambda-cyhalothrin were determined as having a high likelihood of acting as endocrine disruptors, as validated by literature highlighting the four pesticides' hormone-related cognitive, physiological and reproductive adverse health effects. Findings indicated that a number of farmers' adaptative practices were found to be incremental and, potentially, maladaptive, thereby enhancing pesticide use and exposure. This was indicative of climate change's potential for perpetuating pesticide-related endocrine disrupting health risks. Opportunities exist, however, for farmers to reduce pesticide use, and, thus, potential endocrine disrupting health risks through certain autonomous transformational adaptive practices, such as crop switching and cotton acreage reduction. Assistance to farmers by the government and development agencies, for enhancing opportunities for transformational adaptation is therefore recommended. Furthermore, there is need, at policy level, for phasing out pesticides with endocrine disrupting properties. There is, furthermore, a clear need for enhancing farmers' access to, and comprehension of, pesticide risk information through various innovative means, including research translation to reduce exposure risks.

Thesis (PhD)--Stellenbosch University, 2000.
ENGLISH ABSTRACT: Diabetes Mellitus (DM) is synonymous with "B-cell failure". Ligation of the pancreatic duct distally to its confluence into the bile duct has been shown to induce endocrine tissue regeneration from a number of probable sources. The cells responsible for regeneration are supposed to possess either dormant pluripotent stem cell ability and/or the plasticity to undergo metaplasia to form new and surplus endocrine tissue able to replace pathologically and/or experimentally compromised pancreas. The sequence of events (cell lineage) during this process of neogenesis, has been the source of controversy for quite some time as various studies suggest that the cell lineage differs from in vivo and in vitro studies, according to experimental model and species of laboratory animal. The object of this study was to utilise an established experimental laboratory animal model to study islet morphological changes, neogenesis and or both in vivo. Further aims of the study were to determine the extent, sequence and magnitude of pancreatic duct ligation (PDL) induced endocrine neogenesis/morphogenesis in a laboratory rat model using occlusive pancreatic duct ligation. PDL's were performed on six groups of 25 normal adult Sprague-Dawley (SD) rats (300g+) according to the method of Hultquist and Jonsson (1965). Experimental animals were sacrificed at 12 hr intervals from day one post-PDL to day 10 and every 24 hrs thereafter to day 14 as described by Wang, Klëppel, Bouwens (1995). Animals received BrdU (a thymidine marker and cell proliferation indicator) 50mglkg intraperitoneally as described by Wang et al. (1995), one hour prior to removal of the pancreas after which it was fixed in Bouin's solution and histologically processed. Seven consecutive 3-6 urn thick serial sections were sequentially stained with H & E, insulin (I), glucagon (G), somatostatin (ST), pancreatic polypeptide (PP), neuropeptide tyrosine (NPY) and peptide tyrosine tyrosine (PYY). Immunolabeling was done according to the method of Guesdon, Temynck , Avrameas (1979). Double immunolabeling for BrdU and each pancreatic peptide was performed on the sections on days 3,5, 7, 9 and 11 as described by Wang et al (1994). Cellular transformation between one and 3Yz days was characterised by simultaneous total deletion and/or transdifferentiation of the acinar compartment and the appearance of immunoreactive cells for I (11.53 ±1.5%), G (1.85 ±0.8%), pp (1.50 ±0.09%), and ST (1.96 ±0.24%). Changes in the endocrine composition in existing islets, occurred along a pathway that saw PP- and ST-cells invading the islet core, islet mantle glucagon deletion and random appearance of all endocrine cell types within the inter-islet interstitium on day 3Yz. Days 4 to 6Yz saw further endocrine expansion while days 7 to 14 were distinguished by islet reconstitution and consolidation. NPY immunoreactivity appeared on day 4Y2 and persisted intermittently throughout while PVV first appeared on day 4 and disappeared after day 7Yz. The results suggest that PDL firstly induced the development of endocrine tissue distributed haphazardly throughout the space previously occupied by acinar parenchyma. Secondly, the appearance of insulin is preceded by the appearance of PP, glucagon and somatostatin by 24-hours. A still to be determined proportion of the ligation induced endocrine formation appeared to be associated with existing islets, resulting in a number of very large islets, some of which might have secretory access through the glomerularlike capillary network known to occupy the islet core. The remainder appeared to form separate "new" islets, which have a dubious access to the blood stream. In conclusion, if it is true that the pancreas can regenerate some of its endocrine tissue then it has potential clinical implication for the stabilising of diabetes mellitus. Ligated exocrine pancreatic tissue, devoid of its acinar component, has been shown to contain notable quantities of insulin positive cells. This presents intriguing possibilities as an alternative for donor tissue, usually obtained from rat foetuses, during foetal rat pancreas transplantation studies. Pancreas tissue harvested from duct ligated rats could replace the foetal tissue currently used in the treatment of experimental diabetes mellitus in laboratory animals in this laboratory.
AFRIKAANSE OPSOMMING: Diabetes Mellitus is sinoniem met B-sel disfunksie. Endokriene regenerasie kan segmenteel bewerkstellig word deur eksperimentele afbinding van die pankreasbuis distaal tot sy samesmelting met die gemene galbuis. 'n Verskeidenheid van selle word vermoedelik by hierdie proses betrek. Dormante stamselle besit die vermoë en/of plastisiteit om 'n aantal vorms van metaplasie te ondergaan om nuwe en/of oortollige endokriene weefsel te vorm wat patologiese en/of eksperimenteel gekompromiseerde weefsel vervang. Die selontwikkelings volgorde wat tydens hierdie proses plaasvind is al vir 'n geruime tyd die middelpunt van 'n meningsverskil. Sommige studies dui daarop dat die in vivo selontwikkelingsvolgorde verskil van in vitro, volgens eksperimentele model en tipe proefdier gebruik. Die doel van die studie was die gebruik van 'n bestaande eksperimentele laboratorium proefdier model om pankreas eiland morfologiese verandering en/ofneogenese of beide in vivo te evalueer. Die oogmerk van die studie was om die omvang en volgorde van veranderings in die endokriene kompartement (neogenese/morfogenese) te bepaal deur gebruik te maak van 'n pankreas buis afbindings (PBA) model wat totale afsnyding van die buis tot gevolg het. PBA's is uitgevoer op ses groepe van 25 volwasse normale Sprague-Dawley (SD) laboratorium rotte (±300g) soos beskryf deur Hultquist en Jonsson (1965). Proefdiere is elke 12 uur geoffer vanaf dag een post-PBA tot dag tien en elke 24 uur daarna tot dag 14 soos beskryf deur Wang, Bouwens, Kloppel (1995) na die toediening van 50 mg/kg 5-Bromo-2-deoksi-uridien intraperitoneaal ('n selprolifererings aanduider) soos beskryf deur Wang et al. (1995). Die pankreas is werwyder, in Bouin se oplossing gefikseer en histologies geprosesseer. Sewe openvolgende seriesnitte (3-6 urn) is alternatiewelik gekleur met H & E, en immunositochemies, soos beskryf deur Guesdon, Terugnek, Avrameas (1979), vir insulien (I), glukagon (G), somatostatien (ST), pankreatiesepolipeptied (PP), neuropeptied tirosien (NPY) en peptied tirosien-tirosien (PYY). BrdU dubbel-immuunkleuring is ingesluit op dae 3,5, 7, 9 en 11 soos beskryf deur Wang et al. (1994). Sellulêre transformasie tussen dae een en 3~ dae is gekenmerk deur gelyktydige en totale uitwissing en/ofmetaplasie van die asinêre kompartement en die verskyning van selle immunorektiefvir I(11.53 ±1.5%), G (1.85 ±0.8%), PP (1.50 ±0.09%), ST (1.96 ±0.24%). Metaplasie was verantwoordelik vir merkbare veranderings in bestaande endokriene weefsel langs In transformasie weg waar eiland insulien kemselle vervang is deur PP- en ST-selle, glukagon buitelaag uitwissing en die toevallige verskyning van alle endokriene seltipes in the inter-eiland interstitium teen dag 3Y2. Dae 4Y2deur 6~ is gekenmerk deur verdere endokrinetoename terwyl dag 7 deur 14 gekenmerk is deur eiland hersamestelling en konsolidering. NPY immunoreaktiwiteit was vanaf dag 4~, met afwisseling, te bespeur terwyl PVV slegs tussen dae 4 en 7 In verskyning gemaak het. . Die resultate suggereer eerstens, PBA induseer die ontwikkeling van oortollige endokriene weefsel op In lukrake wyse versprei deur die ruimte voorheen deur asinêre parenchiem beset. Tweedens, dat die verskyning van insulien deur dié van PP, glukagon en somatostatien met minstens 24-uur voorafgegaan is. Die verhouding, van nuutgevormde endokriene weefsel wat met bestaande eilande assosieer om In aantal baie groot eilande te vorm, moet nog vasgestel word. Sulke strukture mag moontlik afskeidings toegang hê tot die bloedstroom, deur die glomerulusagtige kapillêre netwerk, in die eilandkern teenwoordig terwyl die oorblywende nuutgevormde endokrine weefsel "nuwe" apparte eilande vorm wat wel of gladnie toegang tot die bloedstroom mag hê nie. As gevolgtrekking, indien dit waar is dat volwasse pankreas eilandweefsel wel regenerasie kan ondergaan, dan het dit kliniese implikasie vir die stabilisering van diabetes mellitus. Weefsel verkry uit PBA bevat geen asinêre weefsel nie maar wel merkbare hoeveelhede endokriene weefsel, veral insulin positief. Dit bied dan interessante alternatiewe as skenker weefsel by fetal rot pankreas oorplantings. PBA en/of die oorplanting van pankreasbuis afgebinde weefsel, na in vitro weefsel kultuur, bied moontlikhede vir die behandeling van diabetes mellitus.

Cette thèse s'intéresse à la présence et au devenir de sept alkylphénols et du bisphénol A (BPA) sur le bassin de la Seine qui présente à la fois une partie très urbanisée (la région Île-de-France, IDF) et une autre soumise à une exploitation agricole intense. Elle est organisée autour de quatre approches. Dans une première approche les sources urbaines ont été caractérisées. Pour cela, les rejets des cinq plus grandes stations d'épuration (STEP) d'IDF, les surverses unitaires de temps de pluie (SUTP), les eaux des exutoires pluviaux et les retombées atmosphériques ont été analysées. Cette étude a révélé que le BPA était majoritairement présent dans les sources de temps de pluie (SUTP et eau des exutoires pluviaux) tandis que l'acide nonylphénoxy acétique (NP1EC), un précurseur du 4-nonylphénol (4-NP), est dominant dans les rejets de STEP. Le 4-NP a, lui, été retrouvé dans toutes les sources étudiées à des concentrations avoisinant la centaine de nanogrammes par litre (ng.l-1), témoignant de sa forte dissémination dans l'environnement urbain. Dans un second temps, l'imprégnation du milieu a été considérée au niveau des eaux de surface et des sols, à deux échelles d'observation. La première échelle est le bassin de l'Orgeval, caractéristique d'un petit bassin amont, tandis que la seconde échelle intègre l'ensemble de la région IDF et l'agglomération parisienne. Ces deux échelles ont permis de mettre en évidence une dissémination importante du 4-NP à l'ensemble des matrices naturelles du bassin de la Seine. A l'échelle de l'IDF, l'influence de l'agglomération parisienne a été constatée sur les concentrations de NP1EC et BPA dans la Seine. Puis, la biodégradabilité des composés nonylphénoliques dans la Seine a été déterminée par une approche innovante. Les constantes de biodégradation ont été déterminées directement dans la Seine à l'aide du modèle ProSe (développé par le Centre de Géosciences, Ecole des Mines ParisTech) et de campagnes de prélèvement spécifiques sur le fleuve (suivi d'une masse d'eau). Les constantes de biodégradation simulées dans la Seine présentent de très fortes variabilités en fonction des conditions hydrauliques et climatiques. Après un épisode de bloom algal, les constantes de biodégradation des composés nonylphénoliques se sont avérées 10 à 35 fois supérieures à celles retrouvées en conditions classiquement rencontrées en Seine Enfin, les flux d'alkylphénols et de BPA exportés par la Seine ont été comparés aux flux émis par les sources urbaines au niveau annuel. A l'échelle de 2010, les flux de 4-NP et de BPA émis par l'ensemble des sources urbaines considérées ne sont pas prédominants devant les flux exportés par la Seine à l'aval de l'agglomération parisienne. Ce résultat confirme la dissémination importante du 4-NP et du BPA sur la région IDF en raison de leur forte utilisation depuis les années 1960. Il soulève également plusieurs questions concernant les sources actuelles des flux retrouvés et la contamination observée sur les zones amont du bassin de la Seine. Cette thèse a été effectuée dans le cadre des programmes de recherche PIREN-Seine (Programme Interdisciplinaire de Recherche sur l'ENvironnement de la Seine) et OPUR (Observatoire des Polluants URbains).

Le maintien et le renouvellement des populations de poissons coralliens dépendent en grande partie du recrutement larvaire, c’est-à-dire de l’installation des larves pélagiques dans les habitats récifaux adultes, et de leur survie après s’être métamorphosées en juvéniles. De plus en plus d’études révèlent que les changements de composition de l’eau, causés par le changement climatique et la pollution, peuvent altérer les capacités sensorielles des poissons coralliens, diminuant leurs aptitudes à localiser des habitats propices (maximisant leur croissance et diminuant leur mortalité) lors de l’installation. Cependant, les mécanismes internes à l’origine de ces phénomènes sont méconnus. Lors de cette thèse, j’ai examiné le recrutement larvaire du poisson chirurgien bagnard Acanthurus triostegus et mis en évidence que les changements écologiques, morphologiques, physiologiques et comportementaux qui s’y déroulent correspondent à une métamorphose contrôlée par les hormones thyroïdiennes (HT). J’ai ensuite analysé comment des stress d’origine anthropique, tels que l’élévation des températures de surface et la pollution par un pesticide d’origine agricole, peuvent perturber sa métamorphose. Lors de cette étape clé de leur cycle de vie, ces perturbations diminuent les taux d’HT, altérant la maturation de leurs organes sensoriels, leurs capacités sensorielles, et augmentant leur mortalité. Cette thèse est donc une analyse holistique de l’impact des perturbations anthropiques sur les processus moléculaires, et les changements histologiques, anatomiques et comportementaux du recrutement larvaire des poissons coralliens. Elle souligne l’importance du système thyroïdien, et invite à une meilleure compréhension des processus endocriniens du recrutement larvaire, dans l’optique d’une amélioration de la conservation des récifs coralliens
The persistence and sustainability of coral-reef fish populations depends on the continued larval recruitment, i.e. successful settlement by pelagic larvae into adult reef habitats and post-settlement survival through metamorphosis to a juvenile stage. There is growing evidence that changes to water conditions due to global change and waterborne pollution can impair coral-reef fish sensory abilities to locate settlement habitats that maximize growth while minimizing mortality risk. However, the inner mechanisms of such impairments remain unknown. In this thesis, I have examined the recruitment phase of the convict surgeonfish Acanthurus triostegus, and determined that the ecological, morphological, physiological and behavioral changes occurring at recruitment correspond to a metamorphosis mediated by thyroid hormones (TH). Then, I investigated whether this metamorphosis is prone to endocrine disruption under anthropogenic disturbances such as elevated sea water temperature and agricultural pesticide pollution. I demonstrated that such pressures can reduce TH levels at a critical developmental stage in coral-reef fishes, impairing their metamorphic processes such as intestine remodeling, sensory organ maturation, and sensory abilities acquisition, further increasing their mortality rates. Overall, this thesis is a holistic analysis that addresses molecular, histological, anatomical, and behavioral assays of multiple stressors affecting coral-reef fish recruitment. It indicates the importance of a proper endocrine function during coral-reef fish recruitment, highlighting the need for a better understanding of these processes for coral-reef conservation

Thesis (MSc (Physiological Sciences))--University of Stellenbosch, 2006.
Early adverse life events appear to increase the susceptibility of developing psychiatric disorders later in life. The molecular mechanisms involved in the development of pathological behaviour remain unclear. Dysregulation of the hypothalamic-pituitary-adrenal axis and alterations in neurotrophic factors have been implicated.

Indiana University-Purdue University Indianapolis (IUPUI)
Regulation of coronary blood flow is a highly dynamic process that maintains the delicate balance between oxygen delivery and metabolism in order to preserve cardiac function. Evidence to date support the finding that Kv and Cav1.2 channels are critical end-effectors in modulating vasomotor tone and blood flow. Yet the role for these channels in the coronary circulation in addition to their interdependent relationship remains largely unknown. Importantly, there is a growing body of evidence that suggests obesity and its pathologic components, i.e. metabolic syndrome (MetS), may alter coronary ion channel function. Accordingly, the overall goal of this investigation was to examine the contribution coronary Kv and Cav1.2 channels to the control of coronary blood flow in response to various physiologic conditions. Findings from this study also evaluated the potential for interaction between these channels, i.e. electromechanical coupling, and the impact obesity/MetS has on this mechanism. Using a highly integrative experimental approach, results from this investigation indicate Kv and Cav1.2 channels significantly contribute to the control of coronary blood flow in response to alterations in coronary perfusion pressure, cardiac ischemia, and during increases in myocardial metabolism. In addition, we have identified that impaired functional expression and electromechanical coupling of Kv and Cav1.2 channels represents a critical mechanism underlying coronary dysfunction in the metabolic syndrome. Thus, findings from this investigation provide novel mechanistic insight into the patho-physiologic regulation of Kv and Cav1.2 channels and significantly improve our understanding of obesity-related cardiovascular disease.