Cette thèse présente les adaptations spécifiques des hibernants ‘food-storing’ qui s’alimentent au cours de l’hibernation, et les conséquences de la qualité du régime alimentaire sur leur cycle annuel. Tandis que les espèces ‘fat-storing’ jeûnent pendant toute l’hibernation, les ‘food-storing’ alternent jeûnes courts et réalimentations. L’adiponectine stimulerait la lipolyse pendant l’hibernation contribuant ainsi à la cétogenèse. Le maintien d’un système digestif fonctionnel conduisant à la sécrétion d’incrétines, permet l’absorption optimale de nutriments lors des courtes euthermies inter-torpeurs. Une absorption accrue de glucose en particulier permettrait de restaurer la glycémie et les réserves de glycogène. Par ailleurs, un régime appauvri en protéines et enrichi en lipides induit un engraissement augmenté en période pré-hibernatoire provoquant une moindre utilisation de la torpeur donc une perte de masse accrue lors de l’hibernation, et une baisse du succès reproducteur. / This thesis presents the specific adaptations of food-storing hibernators that feed during hibernation, and the impact of diet quality on their annual cycle. In contrast to the fat-Storing species which fast during hibernation, the food-storing presents metabolic responses to an alternation of short fasting phases and hyperphagia. These responses involve one hand use of fat reserves during hibernation contributing to ketogenesis, which would be induced by adiponectin. On the other hand, maintaining a functional digestive system leading to the secretion of incretins, permits optimal nutrient absorption in the short inter-torpor euthermia. Increased glucose uptake in particular would restore body reserves to spare. Moreover, a lean protein diet enriched in fat and induces increased in body mass in pre-hibernation period causing reduced use of torpor thus an increased loss of mass during hibernation, and decreased reproductive success.

Abstract Previous observations have indicated that reproductive endocrine disorders are common among patients with epilepsy. Valproate (VPA) treatment is associated with hyperandrogenism, polycystic ovaries, and obesity in women. Carbamazepine (CBZ) may also induce endocrine disorders, while the hormonal effects of oxcarbazepine (OXC) are poorly known. The aim of this study was to elucidate the effects of antiepileptic drugs on reproductive hormones, linear growth and pubertal maturation in patients with epilepsy. Altogether 223 patients taking VPA, CBZ, or OXC monotherapy for epilepsy and 103 healthy age- and sex-matched volunteers participated in the study. Seventy-eight girls and 90 men with epilepsy participated in the cross-sectional parts of the study. Thirty-nine adult patients with newly diagnosed epilepsy participated in a 3-month longitudinal study and VPA was replaced with lamotrigine (LTG) in 16 women with VPA-related endocrine disorders in a 1-year longitudinal study. The girls were between 8-18 years, the women 17-41 years and the men 17-51 years of age. None of the antiepileptic drugs studied significantly influenced linear growth or pubertal development in girls with epilepsy, but hyperandrogenemia, increased number of ovarian follicles, and weight gain were observed in prepubertal, pubertal and postpubertal girls taking VPA for epilepsy. Increased serum testosterone levels were observed in half of the women after the first 3 months of VPA medication, and high serum concentrations of androgens were common (prevalence 57 %, p < 0.001) in men taking long-term VPA treatment. The women with VPA-related hyperandrogenism and polycystic ovaries were also found to present other features of insulin resistance (i.e. hyperinsulinemia, centripetal obesity, and an unfavorable serum lipid profile). Reproductive endocrine disorders associated with VPA treatment in women began to normalize after VPA was replaced by LTG. CBZ reduced the bioactivity of androgens, whereas OXC did not have similar effects. Serum concentrations of sex hormone-binding globulin (SHBG) were increased and dehydroepiandrosterone sulfate decreased already during the first months of CBZ treatment. Serum hormone levels were normal in patients with low OXC doses (< 900 mg/d), but serum concentrations of testosterone, gonadotropins and SHBG were high in men with a daily OXC dose ≥ 900 mg. The adverse reproductive endocrine effects of antiepileptic drugs should be considered at the beginning of and during antiepileptic medication.

No description available.

Two possible variables of the McKenzie/Stoughton blanching assay, namely amount applied to the test site and occlusion time have been investigated. Subsequently, two topical steroid preparations, Synalar cream (0,025% fluocinolone acetonide) and Betnovate cream (0,1% betamethasone 17- valerate) were extemporaneously diluted with five and six placebo bases respectively. Taking cognizance of the two possible variables, these diluted preparations were assessed in vivo using a modified version of the McKenzie/Stoughton blanching assay for blanching activity over a 14 month period. It was found that the base E45, which is slightly alkali, had the greatest effect on both preparations. In the case of betamethasone 17-valerate this base caused the conversion to the less active isomer, betamethasone 21-valerate whereas at the end of the 14 month test period it was found that the Synalar/E45 dilution contained no fluocinolone acetonide. Quantitative analysis of all the diluted preparations by high performance liquid chromatography using a reverse-phase system was performed. The data obtained from the systematic studies of the effects of varying concentrations and occlusion times were presented at the Eleventh National Congress of the South African Pharmacological Society

Several aspects of the human skin blanching assay were evaluated in an attempt to suggest improvements in the methodology of this assay. Three trials were performed in the unoccluded application mode, using two proprietary creams containing 0,1% betamethasone (as the 17-valerate). Preliminary observations of the influence of ambient temperature and relative humidity on the blanching response did not allow definite conclusions to be drawn. Studies on the number of observers required for reliable results of comparative blanching indicated that at least two trained observers should be employed. Analyses of the results of individual volunteers demonstrated the expected biological variability, and suggest that subjects selected for trials should represent a range of blanching responses. No sex-related differences in blanching responses were found, and both arms exhibited similar sensitivity to corticosteroids. Retrospective analysis of 95 040 observations of blanching responses showed that in the unoccluded application mode blanching is lowest close to the wrist, and in the occluded mode blanching is lowest close to the elbow. Studies on the method of transportation of Betnovate preparations suggest that topical formulations should not be exposed to temperature extremes during transportation. It is proposed that patients should not transport topical formulations in the holds of ships or aircraft, and that exporters and manufacturers should make use of special transportation and storage conditions. In a study of ten topical formulations from three countries it was found that there was no trend of products from one country consistently exhibiting superior blanching to products from the other two countries, or products from one country consistently exhibiting the lowest degree of blanching, although considerable differences in blanching responses were found in some cases. Interpretation of the results of these studies demonstrated the importance of employing a combination of statistical analyses, blanching profiles and AUC values when drawing conclusions regarding comparative bioavailability. A study of the blanching profiles of Betnovate cream included in all 16 trials performed during this work indicated that this preparation behaved in a similar fashion during all trials, thereby giving credence to the results of the trials

The influence of the gonadal sex steroids namely, estradiol, progesterone and testosterone on the two major enzymes responsible for the synthesis of melatonin in the pineal gland was investigated. These enzymes are Serotonin-N-acetyltransferase (SNAT) and Hydroxyindole-O-methyltransferase (Hl0MT). Testosterone was found to be the only sex steroid capable of influencing SNAT activity whereas all three of the sex steroids were found to influence Hl0MT activity in a biphasic dose-dependent manner. The influence of these sex steroids on radiolabeled serotonin metabolism by pineals in organ culture was also investigated. Ovariectomy, castration and the sex steroids were all found to alter the pattern of the radiolabeled serotonin metabolism by these pineal glands in organ culture. / KMBT_363 / Adobe Acrobat 9.53 Paper Capture Plug-in

Recent studies have established that yolk hormones of maternal origin have significant effects on the physiology and behavior of offspring in birds. Herrington (2012) demonstrated that an elevation of progesterone in yolk elevates emotional reactivity in bobwhite quail neonates. Chicks that hatched from progesterone treated eggs displayed increased latency in tonic immobility and did not emerge as quickly from a covered location into an open field compared to control groups. For the present study, three experimental groups were formed: chicks hatched from eggs with artificially elevated progesterone (P), chicks hatched from an oil-vehicle control group (V), and chicks hatched from a non-manipulated control group (C). Experiment 1 examined levels of progesterone with High Performance Liquid Chromatography/tandem Mass Spectroscopy (HPLC/MS) from prenatal day 1 to prenatal day 17 in bobwhite quail egg yolk. In Experiment 2, bobwhite quail embryos were passively exposed to an individual maternal assembly call for 24 hours prior to hatching. Chicks were then tested individually for their preference between the familiarized call and a novel call at 24 and 48 hours following hatching. For Experiment 3, newly hatched chicks were exposed to an individual maternal assembly call for 24-hrs. Chicks were then tested for their preference for the familiarized call at 24 and 48-hrs after hatch. Results of Experiment 1 showed that yolk progesterone levels were significantly elevated in treated eggs and were present in the egg yolk longer into prenatal development than the two control groups. Results from Experiment 2 indicated that chicks from the P group failed to demonstrate a preference for the familiar bobwhite maternal assembly call at 24 or 48-hrs after hatch following 24-hrs of prenatal exposure. In contrast, chicks from the C and V groups demonstrated a significant preference for the familiarized call. In Experiment 3, chicks from the P group showed an enhanced preference for the familiarized bobwhite maternal call compared to chicks from the C and V groups at 24 and 48-hrs after hatch. The results of these experiments suggest that elevated maternal yolk hormone levels in pre-incubated bobwhite quail eggs can influence auditory perceptual learning in embryos and neonates.

A radioimmunoassay was developed, specific for the gastrointestinal polypeptide, motilin. Antisera were raised in guinea pigs and rabbits. The immunogen was porcine motilin, conjugated to bovine serum albumin by the carbodiimide condensation reaction. The routine antiserum behaved identically towards endogenously- released motilin and the pure standard preparation. A radioactive tracer of high 125 specific activity was obtained after incorporation of - iodine into the motilin molecule by the chloramine-T method. The optimum conditions for all other assay variables were established to produce the most sensitive displacement Cstandard) curve. Motilin antiserum, coupled directly to an agarose matrix, retained full antibody activity and sensitivity. It is a feasible technique for use in both the radioimmunoassay and in the extraction of motilin from both serum and tissue extracts. The fasting serum levels of IR- motilin was 190 - 131 pg/ml in men and 294 -'.44 pg/ml in dogs (mean - SD) . The increase in motor activity in the extrinsically denervated fundic pouch of the dog after duodenal alkalinization was associated with a concomitant elevation in serum IR- motilin levels. This increase in serum IR- motilin was in the same range as that achieved by the exogenous administration of the porcine polypeptide which produced the same motor response. Duodenal acidification produced an apparent increase in serum IR-motilin with no associated increase in gastric motor activity. Only one peak of motilin immunoreactivity was detected when serum containing alkali-stimulated motilin or a partially purified duodenal extract were subjected to gel filtration on Sephadex G-50. The distribution of motilin throughout the hog gastrointestinal tract, determined by radioimmunoassay on partially purified extracts, agreed with the immunocytochemical findings that motilin was predominantly located in the duodeninn and jejunum, with traces.in the upper ileum. Virtually the intact molecule was required for the expression of full biological potency. The individual amino acids were important inasmuch as they contributed to the charge distribution and conformation of the molecule. The physiological release and function of motilin have yet to be determined. Elevated levels of circulating IR- motilin have not been associated with any gastro-intestinal function, although they appear to be depressed by feeding. Motilin has been implicated in the control of the interdigestive phase of gastric motor activity. It may be acting in a local or paracrine manner. Motilin has not been implicated in any .•cU'in±cal.rst"ait"eC&s sjffetfce i The hormonal status of gastric inhibitory polypeptide (GIP) has been studied with the existing radioimmunoassay, modified to improve the label specific activity (by ion exchange chromatography). Direct coupling of GIP antisera to agarose beads was unsatisfactory, antibody activity and sensitivity being greatly reduced by the close proximity of the solid matrix. The postulated role of GIP as the enterogastrone1 of Kosaka and Lim, suggested by studies with exogenously-administered polypeptide, was confirmed by experiments in the dog. Pentagastrin-stimulated gastric acid secretion was inhibited by intra-duodenal infusion with glucose or fat; this inhibition being associated with a significant elevation in the circulating serum IR- GIP levels, within the range produced by ingestion of a mixed meal. GIP does not appear to be involved in the inhibition of gastric acid secretion produced by duodenal acidification. Endogenous;GIP.stimulated by either fat or glucose exhibited at least 3 Immunoreactive components after column chromatography. The IR- GIP eluting in the void volume appeared to represent a non-specific complex between GIP and a serum protein and is possibly biologically inactive. A second IR-GIP component with a molecular weight of 7500-8000 (ProGIP), eluted ahead of the established form of GIP (molecular weight = 5105). ProGIP has been found to be relatively unstable. ProGIP and GIP^QQQ have also been detected in extracts of hog duodenal mucosa. The established insulinotropic effect of GIP correlates best with that percentage of the total IR- GIP composed of ProGIP and GIP500(). The relative proportions of IR- GIP500Q and IR- ProGIP in serum samples taken at different times after ingestion of either fat or glucose, suggest that ProGIP is either a precursor of GIP or that the ProGIP-producing cells occupy a more distal region of the duodenal and jejunal mucosa than the GIP- producing cells. Exogenous administration of synthetic somatostatin in dogs and man will inhibit both.GIP release by either fat or glucose and the insulino-tropic action of GIP at the level of the 8/-cell. Naturally-occurring intestinal or pancreatic somatostatin may contribute to the control of GIP release and serve to modulate the GIP- mediated response of the gastric parietal or pancreatic β-cell. / Medicine, Faculty of / Cellular and Physiological Sciences, Department of / Graduate

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.

A thesis submitted to the Faculty of Medicine, University of the Witwatersrand, Johannesburg, for the degree of Doctor of Medicine. / An attempt was made to document iron losses from the body as a whole, as well as from individual excretory routes using a combination of radioisotopic and chemical techniques. The purpose of this work was to gain a better understanding of external body exchange, and to resolve some of the existing controversies regarding the magnitude of daily iron losses. The basis for this controversy is extensively reviewed in the thesis / IT2018