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1
Hopkins, John. "Lymphoid physiology of the sheep." Thesis, University of Edinburgh, 2000. http://hdl.handle.net/1842/29805.
Texte intégralRésumé :
The aim of this thesis is to bring together and summarize the results of twenty-five years of active research into the immunology and physiology of the mammalian lymphoid system using the sheep as the model species. For this work I have exploited the cannulation of peripheral lymphatics, which enables the monitoring of lymph, lymphocytes and dendritic cells that are constantly trafficking from the skin or from lymph nodes. The use of this technique in the sheep permits access to large numbers of lymph-borne cells over extensive periods and in a form far closer to their <i>in vivo</i> non-activated state than from any other species. I have organized the publications into four distinct, but interrelated chapters. Chapter 1 is concerned with the physiology of sheep lymphoid cells and describes the use of the cannulated lymphatic model to answer fundamental questions of lymphoid biology. My earliest work was focused on the non-random migration of lymphocytes and the identification of two lymphocyte populations; one associated with the gastrointestinal tract and other mucosal organs and the other with peripheral lymph nodes and the spleen. Later work identified two separate populations of B cells with distinct recirculation properties and also concentrated on the lymph node response to antigen and the role played by antigen in modulating lymphocyte recirculation. Much of my work in the last few years has been concerned with the biology of dendritic cells (DCs), the cell population uniquely able to induce the primary immune response. The "pseudo-afferent" cannulation system in sheep is, arguably the best system for this study, as the isolation procedure does not lead to aberrant changes in cell phenotype and function. Chapter 2 relates the work to characterize the sheep immune system, in order to exploit further the sheep as a species for immunological study. Much of my efforts involved the production and characterization of anti-sheep MHC and CD1 monoclonal antibodies (mAbs). This resulted in the generation of monoclonal reagents that are now the standards used to define the ovine/bovine homologues of MHC class I, and class II and CD1.
2
Falchi, Laura. "Transcervical artificial insemination and physiology of the cervix of the sheep." Thesis, Royal Veterinary College (University of London), 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.558963.
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3
Nicholls, C. D. "Endoscopy, physiology and bacterial flora of sheep infected with abomasal nematodes." Thesis, University of Leeds, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377967.
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4
Morrow, Robert James. "Blood flow velocity changes in the umbilical artery of the fetal sheep." Thesis, Queen's University Belfast, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356870.
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5
Mamo, John Charles Louis. "Plasma lipoprotein triacylglycerol metabolism in sheep : a thesis submitted to the University of Adelaide in fulfilment of the requirements for the degree of Doctor of Philosophy." Title page, contents and introduction only, 1986. http://web4.library.adelaide.edu.au/theses/09PH/09phm265.pdf.
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6
Swinburne, Sarah Jane. "A study of the molecular and biological characteristics of ovine interleukin-12." Title page, contents and summary only, 2000. http://web4.library.adelaide.edu.au/theses/09PH/09phs9777.pdf.
Texte intégralRésumé :
Bibliography: leaves 172-214. Interleukin-12 (IL-12) is a heterodimeric cytokine composed of two disulphide-linked subunits, p35 and p40, which form biologically active p70. IL-12 is able to induce IFN-y production from T and NK cells, and promote the proliferation of mitogen-activated T cells. It is thought that IL-12 may be an important cytokine in the initiation and progression of allograft destruction. This thesis describes the characterisation of ovine IL-12.
7
Yarney, Thaddeus A. "Sexual maturational changes in the pituitary and testes of ram lambs and predictability of adult reproductive function." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=72049.
Texte intégralRésumé :
Spring-born ram lambs were used to examine: (1) sexual maturational changes in LH, FSH and prolactin (PRL) secretion, testicular gonadotropin receptors, and testicular size and function; (2) predictability of yearling ram reproductive function from juvenile testicular size and reproductive hormone measurements. Despite continuous increases in testis size, serum LH-profile characteristics became greatest between 2 and 4 months and declined thereafter. However, LH-peak frequency increased by about 2-fold between 6 and 7 months; this was associated with marked increases in testosterone (T) secretion and spermatogenic function. Mean FSH and PRL levels were maximum at 2 months and 3 to 5 months, respectively, and decreased thereafter. Increases in steroidogenic and spermatogenic function were due partly to increases in testicular content of LH and FSH receptors. Yearling ram testis size and spermatogenic function were predictable from testis size at 5 to 6 months, neonatal (50 days) secretion of LH and T, and pubertal (150 days) secretion of T. However, combinations of testicular size and reproductive hormone measurements provided greater predictive power.
8
Vasquez, Hidalgo Manuel Alexander. "Effects of Nutrient Restriction, Realimentation, and Twinning on Plasma Volume, Umbilical Hemodynamics and Placental Characteristics in the Pregnant Adolescent Ewe." Diss., North Dakota State University, 2019. https://hdl.handle.net/10365/31573.
Texte intégralRésumé :
Reproductive physiology in production animals is a key economic component of longevity and profitability of animal farming. There are several components that can benefit or compromise adequate pregnancy periods. Sheep production is not only a very important economic activity for farmers around the United States, but sheep are also an important medical and surgical model to study human diseases. Our findings suggest that estradiol-17 beta could be involved in acute increased plasma volume early in gestation which can benefit overall gestation. We report that umbilical blood flow decreases upon nutrient restriction in adolescent ewes and does not recover upon realimentation. Finally, we suggest that a similar umbilical blood flow, placental development and plasma volume expansion in twins and singleton pregnancies could be enough to obtain similar birthweights in singletons and twins.
9
Schoombee, Cornelius Johan Albertus. "The Damara sheep : an appraisal of its reproductive performance and potential." Thesis, Stellenbosch : University of Stellenbosch, 1998. http://hdl.handle.net/10019.1/5481.
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10
Ross, Jacob T. "Hypophysial and local mediators of adrenocortical growth and function before birth /." Title page, contents and summary only, 2000. http://web4.library.adelaide.edu.au/theses/09PH/09phr8242.pdf.
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11
Pretorius, Willem S. "An alternative approach to premature luteal regression." Thesis, Stellenbosch : Stellenbosch University, 2006. http://hdl.handle.net/10019.1/17406.
Texte intégralRésumé :
Thesis (MSc)--University of Stellenbosch, 2006.<br>ENGLISH ABSTRACT: Premature luteal regression occurs on average in 30% of superovulated sheep ewes. This phenomenon occurs early in the cycle before the embryo’s can be collected and is a major contributor to failure in embryo transfer programs. This research was done to understand the physiological mechanisms involved.
Chapter two provides a general background of the physiology of natural luteolysis and the maternal recognition of pregnancy. The chapter introduces some new concepts on the topic of cell death and provides a recent literature review on research done on the phenomenon of premature luteal regression. This chapter forms the base of ideas and arguments that follows in the two studies containing new original work in this field.
The research contained in this thesis comprises of two in vivo studies. The first study (Chapter 3) compare premature luteal regression to Prostaglandin F2α (PGF2α) induced regression with emphasis on the changes in levels of the steroid hormones progesterone (P4) and estradiol - 17β (E2-17β) and changes in structure and ultra structure. The following conclusions were made:
1. Premature luteal regression is not merely inadequate luteal support, but indeed early luteal regression, since seasonal influences could merely be nutritional influences, and a definitive increase in P4 were recorded in animals exhibiting the phenomena. 2. Nutritional influences could play a role, but the type and quality of nutrients and mechanism involved, is still unclear.
3. PGF2α-induced regression differs from premature luteal regression in that:
a) The progression of functional and structural regression in PGF2α -induced regression is slower than in premature luteal regression.
b) Regressed corpora lutea do not occur with normal functioning corpora lutea.
4. There is a distinct second E2-17β peak preceding the decline in P4 in animals that exhibits signs of premature luteal regression.
A threshold initiating premature luteal regression was not established.
The second study (Chapter 4) compares the changes in the ovine β estradiol - 17 β receptor (oERβ) between premature luteal regression and PGF2α induced regression. The study concludes that there could be a potential role for oERβ in premature luteal regression.
The findings of these two studies raise some questions about the conventional perception that early release of PGF2α is the cause of premature luteal regression. The thesis concludes in a hypothesis (Chapter 4) explaining the phenomenon.<br>AFRIKAANSE OPSOMMING: Premature luteale regressie kom gemiddeld in 30% van gesuperovuleerde skaap-ooie voor. Die verskynsel kom vroeg in die siklus voor, voor die embrios gekollekteer kan word, en is een van die belangrikste oorsaake van mislukkings in ‘n embrio-oorplaasingsprogram. Die huidige navorsing poog om die fisiologiese meganismes betrokke by premature luteale regressie te verstaan.
Hoofstuk twee verskaf ‘n algemene agtergrond van die fisiologiese aspekte betrokke by natuurlike luteale regressie en maternale herkenning van swangerskap. Die hoofstuk stel nuwe konsepte voor oor sel afsterwing en verskaf ‘n opgedateerde literatuuroorsig met betrekking tot die navorsing wat in die veld oor die verskynsel gedoen is. Die hoofstuk vorm die basis vir die idees en argumente, wat volg in die twee studies en wat oorspronklike nuwe navorsing bevat oor die onderwerp.
Die navorsing in die tesis bestaan uit twee in vivo studies. Die eerste studie (Hoofstuk 3) vergelyk premature luteale regressie en prostaglandien F2α (PGF2α) ge-induseerde regressie met ‘n klem op die vlakke van die steröiedhormone progesteroon (P4) en estradiol - 17β (E2-17β) en veranderinge in die mikroskopiese struktuur en ultra struktuur van die corpus luteum. Die studie bevind:
1. Premature luteale regressie is nie slegs onvoldoende luteale funksie nie, maar vroë luteale regressie aangesien seisoenale invloede eitlik voedings invloede kan wees en P4 gestyg het in diere waar die verskynsel voorgekom het.
2. Voeding kan ‘n rol speel maar die tiepe en gehalte van die voedingstowwe en die meganismes betrokke is nie duidelik nie.
3. PGF2α - ge-induseerde regressie verskil van premature regressie in dat:
a) Die verloop van funksionele en strukturele regressie is stadiger in PGF2α - ge-induseerde regressie in vergelyking met premature luteale regressie.
b) Corpora lutea wat regressie ondergaan het kom nie voor saam met corpora lutea wat normal voorkom nie.
4. Daar die ‘n duidelike tweede piek van E2-17β gaan die afname in P4 vooraf in diere waar premature regressie voorkom.
5. Daar is nie geslaag om ‘n drempel vas te stel waar premature regressie ge-inisieer word nie.
Die tweede studie vergelyk die veranderinge in estradiol-17β reseptore (oERβ) in die skaap tydens premature luteale regressie en PGF2α geinduseerde regressie. Die studie bevind dat daar ‘n moontlike rol is vir ERβ in premature luteale regressie.
Die bevindinge van die twee studies bevraagteken die konvensionele opvatting dat vroë vrystelling van PGF2α verantwoordelik is vir premature luteale regressie. Die tesis sluit af met ‘n nuwe hipotese om die verskynsel te verduidelik.
12
Williams, Claire Louise. "The effects of molybdenum, iron and sulphur on copper metabolism and physiology of sheep." Thesis, Open University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.403832.
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13
Cuneo, Christine Lesley. "Studies of the physiology and biochemistry of early development in the preimplantation sheep embryo." Thesis, Cuneo, Christine Lesley (1985) Studies of the physiology and biochemistry of early development in the preimplantation sheep embryo. PhD thesis, Murdoch University, 1985. https://researchrepository.murdoch.edu.au/id/eprint/53088/.
Texte intégralRésumé :
Preimplantation sheep embryos were collected during the initial period of embryogenesis by flushing the uteri of ewes in situ at 13, 15, 17 and 19 days after mating. The embryos and associated embryonic structures (trophoblast, yolk sac and allantois) present at each age were separated for further investigation. An initial study established the lyophylised weight of embryonic structures present at each stage of development. These values were used as a basis for later comparison of the metabolism of these structures. Changes in the pool sizes of the macromolecules, glycogen, protein, DNA and RNA with development were also determined.
The major part of the project dealt with estimates of the anabolic metabolism, in particular the synthesis of glycogen, protein and RNA, by the different embryonic structures emerging over this period. Embryos and samples of the embryonic membranes were incubated in a variety of culture media containing radiolabelled precursors. After incubation, samples were recovered, lyophylised, weighed then fractionated to assess uptake and incorporation of precursors. The parameters measured were compared per unit dried weight or in terms of total incorporation per structure. Precursors used were U-14C-glucose, U-14C-amino acids and 5-3H-uridine. The results of these studies indicated that there is both a divergence in synthetic activity between structures and a change in synthetic rate of individual structures as development progresses.
Finally a preliminary study of uterine fluid was undertaken. By analysis of fluid obtained by rinsing uteri in situ the volume of fluid in the uterus of the ewe at various times after ovulation was measured. The concentrations of cations and energy substrates in this fluid were estimated in order to gain some understanding of the environment for the embryo in vivo.
14
Xu, Zheng-Chun. "Regulation of the NaK-ATPase of sheep red blood cells of the low- K+ genotype." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41790.
Texte intégralRésumé :
A genetic polymorphism of sheep red cells characterized by differences in the intracellular K$ sp+$ concentration of their mature red cells reflects differences in their Na/K pump activity as well as pump kinetics. This polymorphism is linked to the ML blood group system, as follows. Homozygous high-K$ sp+$ (HK) cells possess only M antigen, whereas homozygous low-K$ sp+$ (LK) cells have an antigen, L$ rm sb{p},$ which is an endogenous inhibitor of the Na/K pump since isoimmune antiserum, anti-L$ rm sb{p},$ stimulates the Na/K pump of LK cells by relieving this inhibition. In this study, it is shown that the $ rm L sb{p}$ antigen is a molecular entity distinct from the pump. Thus, anti-$ rm L sb{p}$ stimulated the activity (ouabain-sensitive $ rm sp{86}Rb sp+(K sp+)$ influx) of exogenous rat kidney pumps incorporated by fusion of kidney microsomes into immature LK red cells. Moreover, the $ rm L sb{p}$ antigen is responsible for the changes in pump kinetics associated with maturation of LK sheep red cells. The evidence is that treatment of immature LK cells with either anti-L$ rm sb{p}$ or trypsin (which cleaves the $ rm L sb{p}$ antigen) prevents the maturation-associated change in kinetics of the pumps, normally from one of no inhibition (immature cells) to that of marked inhibition by intracellular K$ sp+$ (mature cells). In addition, it was shown that kidney pumps delivered into immature LK red cells develop sensitivity to inhibition by intracellular K$ sp+$ following maturation of the cells in vitro. Mature LK cells have fewer pumps than mature HK cells and, therefore, another question addressed was whether the $ rm L sb{p}$ antigen promotes the greater loss of pumps in LK red cells during maturation. It was observed that modification of the $ rm L sb{p}$ antigen of immature LK cells with either anti-L$ rm sb{p}$ or trypsin diminished the subsequent loss of pumps during maturation in vitro. It was shown also that there is little decline in the number of $ rm
15
Butler, Timothy Garth. "Functional heterogeneity of the corticotroph cells in the fetal sheep pituitary /." Title page, table of contents and summary only, 2003. http://web4.library.adelaide.edu.au/theses/09PH/09phb9851.pdf.
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16
Auclair, Dyane. "Pubertal development in the merino ram lambs and immunization against oestrogens." Title page, contents and summary only, 1993. http://web4.library.adelaide.edu.au/theses/09PH/09pha898.pdf.
Texte intégralRésumé :
Bibliography: leaves 281-316. Presents investigations on pubertal development in South Australian merino ram lambs and examines the effect of active and passive immunizations against oestradiol-17ℓ or oestrone on testicular maturation.
17
Boland, Rochelle Elizabeth 1974. "Factors affecting structural development of the lung in fetal sheep." Monash University, Dept. of Physiology, 2002. http://arrow.monash.edu.au/hdl/1959.1/8135.
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18
Boullin, Julian. "The effects of early life nutrient restriction on the cardiovascular system of the adult sheep." Thesis, University of Southampton, 2008. https://eprints.soton.ac.uk/72958/.
Texte intégralRésumé :
There is now strong epidemiological and animal research showing that undernutrition in gestation and early postnatal life is linked with a higher incidence of cardiovascular disease in adulthood. The physiological processes involved are not yet clear. The aim of this thesis was to investigate how aspects of the cardiovascular system in the adult sheep are affected by early life periods of undernutrition, and to investigate to concept that mismatches in these periods may influence these responses. Welsh Mountain ewes received 100% of global nutritional requirements at all times (C) except from minus 30 to day of conception (B), from minus 15 to 15 days after conception (A), or from day 1 of gestation to 31 days gestation (U) when they received 50% of total nutrient requirements. Offspring of groups C & U were then fed ad libitum (CC & UC) or at a level that reduced body weight to 85% of individual target weight from 12 to 25 weeks postnatal age (CU & UU). The adult sheep cardiovascular function was studied at 2.5 years and 3.3 years. At 2.5 years the UC males showed an increased interventricular wall thickness without loss in function. These effects were not seen if early postnatal restriction was also received. In contrast, females subject in the gestational undernutrition (UC) showed a dampened heart rate response to a stressor, which was not seen when combined with a postnatal challenge (UU). Basal adrenaline was elevated in male and female singletons exposed to the postnatal challenge (CU & UU). The stressor produced an enhanced adrenaline response in the females in the postnatally challenged group (CU). This effect was attenuated when combined with a gestational challenge (UU). Thus early life undernutrition alters adult cardiovascular physiology and may have consequences for cardiovascular function and disease in later life. These effects are sex-specific. The cardiovascular system is affected by the mismatch between gestation and early postnatal nutrition.
19
Alderman, Jay Allen 1961. "DIEL ACTIVITY OF FEMALE DESERT BIGHORN SHEEP IN WESTERN ARIZONA." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/276485.
Texte intégralRésumé :
I studied diel activity patterns of female desert bighorn sheep ( Ovis canadensis mexicana) in the Little Harquahala Mountains, Arizona, July 1985-June 1986. Diurnal activity patterns were similar throughout the year. Nocturnal activity patterns were similar for all seasons except spring when activity significantly (P = 0.003) decreased. Bighorn sheep were active an average of 39 and 33% of any given hour during the day and night, respectively. Diurnal ambient temperatures and relative humidity were significantly (P ≤ 0.048) correlated with bighorn sheep activity during all seasons. Bighorn sheep spent a majority of the time foraging in the fall and winter, but spent more time resting during spring and summer. Bighorn sheep obtain water in their food throughout the day; percent moisture content of forage species remained high (≥ 32%) for any given hour of the day throughout the year.
20
Kind, Karen Lee. "Insulin-like growth factors and growth of the fetal sheep /." Title page, contents and abstract only, 1995. http://web4.library.adelaide.edu.au/theses/09PH/09phk525.pdf.
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21
Flux, Claire Louise. "The effect of conjugated linoleic acid on lipid metabolism in the hamster and the sheep." Thesis, University of Nottingham, 2005. http://eprints.nottingham.ac.uk/11141/.
Texte intégralRésumé :
The term conjugated linoleic acid (CLA) refers to a range of geometric and positional isomers of linoleic acid. Recent research suggests a variety of potential health benefits with consumption of dietary CLA. These include a reduction in body fat deposition that has been demonstrated in a number of monogastric species including the mouse, rat, hamster and pig. This thesis describes the effects of CLA on lipid metabolism in sheep, where CLA may be useful in reducing carcass fat and improving fatty acid profile. The results are contrasted with those in the hamster, a model monogastric species, previously shown to respond to CLA. Ovine adipose tissue metabolism was studied in explants maintained in culture and incubated with a mixture of CLA isomers and individual isomers. Total lipogenesis, and the formation of saturated and monounsaturated fatty acids were examined. Results show no effect of CLA (mixed or individual isomers) on total lipogenesis or desaturation of fatty acids. Furthermore, there was no effect on mRNA concentration for acetyl coenzyme A carboxylase (ACC) or stearoyl coenzyme A desaturase (SCD). The effect of feeding CLA (protected from rumen degradation) to sheep, on lipogenic gene expression was then investigated. While there was no evidence of a decrease in total fat deposition, there was a decrease in the proportion of monounsaturated fatty acids in the tissues. As there was no effect on SCD mRNA levels, it appears likely that CLA inhibits SCD activity rather than affecting gene expression. A further feeding study was undertaken in Golden Syrian hamsters. As in the sheep, CLA feeding reduced the monounsaturated fatty acid content of the tissues but did not change the SCD mRNA concentration in adipose tissue or liver. This further supports the suggestion that CLA directly inhibits SCD activity. Unlike the sheep, there was an overall decrease, of approximately 10%, in total carcass fat. However, paradoxically, there was an increase in adipose tissue ACC and fatty acid synthase (FAS) mRNA concentrations. Thus, suppression of lipogenic enzyme expression does not appear to be the mechanism by which CLA reduces fat deposition.
22
Birtwistle, Mark D. A. "The impact of diet in early life on adipose tissue growth and development in sheep." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/32926/.
Texte intégralRésumé :
Adipose tissue is found in two main forms: white (WAT), which stores energy; and brown (BAT), which dissipates energy as heat by means of a unique mitochondrial protein, UCP1. In large mammals, BAT is rapidly replaced by WAT after birth, but it has recently been found that functional BAT is present in human adults, which raises the possibility that it could be manipulated to burn off excess fat. The main aim of this thesis was to investigate, using sheep as a model, the effect of early nutritional interventions on fat mass and on the expression in adipose tissue of genes involved in adipogenesis, metabolism, thermogenesis and development. A secondary aim was to study their ontogeny in sternal adipose tissue. Study A examined the effect of fat supplements given to lactating ewes on the sternal adipose tissue of their offspring. Ewes were allocated to one of three feeding groups, one control and two supplemented (sunflower or canola oil), for 28 days after parturition, and their lambs were sampled at 7 and 28 days of age. Study B investigated the effect of late gestational and postnatal diet on the sternal and subcutaneous adipose tissue of 6 month-old lambs. Twin-pregnant ewes were divided into three dietary groups for the last 6 weeks of gestation: undernourished, control or overnourished. One lamb from each twin pair was fed a control diet, and the other a high-carbohydrate, high-fat (HCHF) diet. In the first month after birth, changes in gene expression in sternal adipose tissue were comparable to those previously described in perirenal adipose tissue, with the expression of most thermogenic genes declining to almost undetectable levels by 28 days of age. There was a disparity in the expression profiles of the two principal regulators of adipogenesis, PPARγ and C/EBPα, with expression of the former increasing with age, and that of the latter peaking at 7 days of age. A sunflower, but not canola, oil supplement fed to lactating ewes increased the relative adipose tissue weight of female, but not male, lambs at 28 days of age. Both supplements increased the plasma concentration of leptin at 7 and 28 days of age in females, but not males. Supplementation had a greater effect on gene expression at 7 than at 28 days of age, but no overall pattern emerged. Maternal undernutrition reduced birth weight in males, but not females, although body weight was unaffected by 6 months of age. A postnatal HCHF diet increased fat mass in all adipose tissue depots tested, and reduced expression of most adipogenic and metabolic genes in sternal and subcutaneous adipose tissue by around 50 %. Expression of thermogenic genes was barely detectable in either tissue at 6 months of age. In conclusion, expression of thermogenic genes in sternal adipose tissue declines with age, a response that is unaffected by maternal fat supplementation during lactation or a sustained postnatal HCHF diet.
23
Pfister, Riccardo E. (Riccardo Erennio) 1961. "Control of lung liquid throughout late gestation and labour." Monash University, Ritchie Centre for Baby Health Research, 2001. http://arrow.monash.edu.au/hdl/1959.1/9321.
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24
Kakar, Muhammad Azam. "Effect of peri-conceptional feed intake on early embryo development and fetal growth in the Merino ewe /." Title page, table of contents and abstract only, 2003. http://web4.library.adelaide.edu.au/theses/09ANP/09anpk138.pdf.
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25
Bray, Megan. "Regulation of wool and body growth : nutritional and molecular approaches." Title page, contents and abstract only, 2002. http://web4.library.adelaide.edu.au/theses/09PH/09phb8267.pdf.
Texte intégralRésumé :
"May 2002" Includes bibliographical references (leaves 148-164) Describes a series of novel experiments designed to enhance our understanding of nutrient utilisation for growth of wool and the whole body.
26
Kim, James H., and n/a. "A comparison of osseointegration in conventionally versus immediately restored implants in a sheep model." University of Otago. School of Dentistry, 2007. http://adt.otago.ac.nz./public/adt-NZDU20071206.162016.
Texte intégralRésumé :
Objectives: To compare the osseointegration of conventionally and immediately restored tapered implants in a split-mouth animal model, and to compare different methods of analysis for measuring osseointegration.
Materials & Methods: Twenty tapered implants were placed in the posterior mandibles of ten sheep, three months after premolar extractions. Ten control implants were placed and were restored after three months submerged healing. Ten test implants were placed on the contralateral side at this time and immediately restored. Animals were sacrificed after a further three months healing. Resonance frequency analysis (Implant Stability Quotient, ISQ), and standardized radiographs were taken at all stages. Alveolar bone height relative to the implant shoulder was measured on digitized radiographs. Histomorphometric and micro-Computed Tomograph ([mu]CT) morphometric analysis for Bone-to-Implant Contact (BIC) and Bone Density (BD) were performed. Radiographic, stability and morphometric measurements were compared statistically.
Results: Only three (30%) of conventionally restored and two (20%) immediately restored implants survived (p = 0.74). Mean crestal bone level after three months loading differed significantly (control 5.3 � 0.9 mm versus test 0.9 � 1.3 mm; p = 0.02). Control implants lost more crestal bone over three months than test implants but this was not statistically significant (3.5 � 1.0 mm versus 0.7 � 1.0 mm; p = 0.06). The test group showed a higher mean ISQ value (85.4 � 6.9) compared to the control group (72 � 14.4; p = 0.349). Both groups showed a slightly reduced stability during the loaded period. This was more marked for the test group but not statistically significant (-0.5 � 3.8 ISQ versus -4.35 � 6.6 ISQ; p = 0.8). A statistically significant negative correlation was found between the loss of crestal bone and ISQ with loading (Pearson�s coefficient of correlation r = -0.473 p = 0.026). Both groups showed a statistically significant difference in BIC for both histomorphometric analaysis (HMA); p = 0.039 and [mu]CT morphometric analysis; p = 0.013. When the two forms of morphometric analysis were compared, HMA and [mu]CT morphometric analysis differed significantly for both BIC (p = 0.05) and BD (p = 0.048). However, a statistically significant correlation was found between the two measuring techniques, for both BIC (r = 0.335 p = 0.013) and BD (r = 0.439 p = 0.01).
Conclusions: The placement of wide-bodied 3i Osseotite NT[TM] tapered implants into sheep mandible resulted in high failure rate regardless of the loading protocol. The sheep mandibular model may be inappropriate as a model for evaluation of immediate loading, and to test implants which are designed for soft bone. Further investigations are needed to look into the variations in bone microstructure along with their impact on the mechanics of implant-bone union. Although a statistically significant difference was found between the two measurement techniques, a positive correlation was found between HMA and [mu]CT morphometric analysis suggesting non-invasive methods may have a potential in assessing osseointegration. Further research is required to optimize the variables in [mu]CT analysis, such as, voltage, filters, and thresholding to minimize artifacts and to maximize bone contrast when titanium implants are present.
27
Nottle, Mark Brenton. "Short-term nutrition and its effect on ovulation in the ewe." Title page, table of contents and summary only, 1988. http://web4.library.adelaide.edu.au/theses/09PH/09phn921.pdf.
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Wade, Dawn E. "Lutalyse® induces uterine-ovarian PGF₂α release in sheep: a critical component of induced luteolysis". Thesis, Virginia Tech, 1994. http://hdl.handle.net/10919/43803.
Texte intégralRésumé :
Exogenous PGF<sub>2α</sub>, (see Appendix I for definitions of abbreviations) is luteolytic in midluteal (1.e., d 9 of a 17 d estrous cycle) sheep. However, the pharmacokinetic responses to PGF<sub>2α</sub>-induced luteolysis are not known. This study (Exp. 1 and 2) was conducted to determine several pharmacokinetic responses to two dosing regimens of Lutalyse® (PGF<sub>2α</sub>). Experiment 1 was a 2 x 2 factorial design, with Lutalyse and H/Ox as main effects. Lutalyse (15 mg) was injected i.m., and blood samples were collected, relative to the time of injection, from the vena cava at points cranial and caudal to the uteroovarian vein. Progesterone and PGF<sub>2α</sub>, were measured in blood plasma. The PGF<sub>2α</sub> concentrations were greater in H/Ox and sham H/Ox ewes treated-with Lutalyse® than in control ewes. Peak concentrations of PGF<sub>2α</sub> were greatest in sham H/Ox Lutalyse-treated ewes, indicating that the uterus and(or) ovaries secrete PGF<sub>2α</sub>, in response to exogenous PGF<sub>2α</sub>. In Lutalyse-treated ewes, progesterone concentrations decreased by 50% within 8 h after treatment. The design of Exp. 2 was also a 2 x 2 factorial, with Lutalyse (2 x 5mg at 3 h intervals) and H/Ox as main effects. Prostaglandin F<sub>2α</sub> and PGFM were measured in blood plasma collected, relative to the time of injections, from the vena cava at points cranial and caudal to the uteroovarian vein. The PGF<sub>2α</sub> concentrations were greater in sham H/Ox ewes treated-with Lutalyse than in control ewes. Peak concentrations of PGF<sub>2α</sub> were greater in sham H/Ox than in ewes in all other treatment groups, indicating again that the uterus and(or) ovaries secrete PGF<sub>2α</sub> in response to exogenous PGF<sub>2α</sub> In general, PGFM concentrations increased in a pattern similar to that of PGF<sub>2α</sub> after Lutalyse injection; although there was a short delay of approximately 2 min. Caudal vena caval PGF, concentrations in H/Ox Lutalyse-treated ewes were greater than that after saline injection, which indicates that metabolism may depend on the presence or absence of the uterus and(or) ovaries. In Exp. 1, caudal PGF, concentrations were greater in H/Ox ewes injected with 15 mg of Lutalyse than in ewes in all other treatments . However, in response to 5 mg Lutalyse, caudal PGF<sub>2α</sub> concentrations were greater in sham H/Ox ewes than in all other treatment groups. This indicates that the larger dose in H/Ox ewes supersedes the capacity of the lung and kidney to dispose of PGF<sub>2α</sub>, and PGF<sub>2α</sub> is more tightly regulated in intact ewes. The lungs and kidney are capable of metabolizing the smaller dose of Lutalyse but not the resulting PGF<sub>2α</sub> production in intact ewes.
A short validation experiment was conducted to determine the effects of sampling location on progesterone, PGF<sub>2α</sub> and PGFM concentrations. Sampling location did not affect the mean concentration of progesterone or PGFM. However, location affected the mean PGF<sub>2α</sub> concentration. The concentration of PGF<sub>2α</sub>, was greater (P < .05) in saphenous vein and caudal vena caval blood plasma than in jugular plasma.
In summary, the uterus and(or) ovaries produce and regulate PGF<sub>2α</sub> concentration in response to Lutalyse. It is speculated that a threshold PGF<sub>2α</sub> concentration or duration of the PGF<sub>2α</sub> peak concentration exists because these PGF<sub>2α</sub>, responses differed in intact Lutalyse-treated and saline-treated ewes in both experiments. The mean cranial PGF<sub>2α</sub> concentration, peak concentration, duration of the peak, increase in PGF<sub>2α</sub> and AUC were greater in response to 15 mg of Lutalyse, although the two smaller doses have been shown to be more efficacious in inducing luteolysis. The second dose of PGF<sub>2α</sub> may act by mimicking pulses of PGF<sub>2α</sub> and initiate the luteolytic cascade two times.<br>Master of Science
29
Smith, Cameron. "Intravenous Administration of Perfluorocarbon Emulsions as a Non-Recompression Therapy for Decompression Sickness." VCU Scholars Compass, 2008. http://scholarscompass.vcu.edu/etd/1555.
Texte intégralRésumé :
Decompression sickness (DCS) results from a sudden decrease in ambient pressure leading to super-saturation of tissues with inert gas and subsequent bubble formation within both tissues and blood. Perfluorocarbons (PFC) are able to dissolve vast amounts of non-polar gases. The administration of intravenous (I.V.) PFC emulsions reduce both morbidity and mortality of DCS, but the mechanism of this protective effect has not yet been demonstrated. Juvenile Dorper cross sheep between 16 and 24 kg (n=31) were anaesthetized and instrumented for physiological monitoring, the administration of I.V. fluids and sampling of arterial and mixed venous blood. Animals were placed in a hyperbaric chamber and compressed to 6.0 atmospheres absolute for 30 minutes, then rapidly decompressed. Upon chamber exit animals were randomly assigned to receive 6cc/kg of either PFC or saline control over 5 minutes beginning immediately after chamber exit. They were also randomized to receive one of 4 breathing gases post-chamber: 100% O2, 80/20 N2/O2, 50/50 HeO2, or 80/20 HeO2. Blood samples were drawn at 5, 10, 15, 30, 60, and 90 minutes to examine whole-body oxygenation. Respiratory gases were monitored and recorded in real-time using mass spectroscopy to examine nitrogen washout. PFC administration increased arterial oxygen content (16.30±0.27 vs. 14.75±0.25 mL/dL, p<0.0001), oxygen delivery (14.83±0.28 vs. 13.44±0.25 mL/minute/kg, p=0.0004), and tissue oxygen consumption (3.37±0.14 vs. 2.76±0.13 mL/minute/kg, p=0.0018) over saline control, but did not increase mixed venous oxygen content (12.45±0.26 vs. 11.74±0.24 mL/dL, p=0.0558) or extraction ratio (0.23±0.012 vs. 0.21±0.011, p=0.1869). PFC administration lowered the plateau of the curve, increasing the amount of nitrogen washout vs. saline control (22.22±1.566 vs. 15.98±1.380 mmHg, p= 0.0074). Breathing 80/20 HeO2 increased the decay constant of the curve, increasing the rate of washout vs. breathing 100% O2 (0.03176±0.001044 vs. 0.03096±0.0009402, p=0.5777). PFC improves whole-body oxygenation after severe DCS and increases the amount of nitrogen washout. Although the effects of both PFC and 80/20 HeO2 breathing were statistically significant the magnitude of the nitrogen washout effect is quite small, and unlikely to be clinically significant. Thus it is likely that the improved oxygenation is responsible for the previously-observed therapeutic effects of PFC in treating DCS.
30
Chidzanja, Stivelia. "Restricted implantation and undernutrition alter development and growth of the ovine placenta." Title page, abstract and contents only, 1994. http://hdl.handle.net/2440/18519.
Texte intégralRésumé :
Bibliography: 161-199.<br>[xxvi], 199, [151] leaves, [7] leaves of plates : ill. (some col.) ; 30 cm.<br>Title page, contents and abstract only. The complete thesis in print form is available from the University Library.<br>Characterises the normal otogeny of the cellular composition and structure of placentomes in sheep, their relationship to the macroscopic parameters of placentome size and morphology, and the effect of experimental and natural restriction of implantation on the growth and development of placentomes between mid and late gestation.<br>Thesis (Ph.D.)--University of Adelaide, Dept. of Obstetrics and Gynaecology, 1995
31
Scobie, David Roger. "Short term effects of stress hormones on cell division rate in wool follicles : a thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy." Title page, abstract and contents only, 1992. http://web4.library.adelaide.edu.au/theses/09PH/09phs421.pdf.
Texte intégralRésumé :
Includes bibliographical references (leaves 183-207) A local intradermal technique using colchicine to estimate cell division rate in wool follicles is refined and used throughout the thesis. Statistical methods used to analyse data obtained with this method are described and discussed. The implications of the findings are of great significance to research into the influence of physiological changes on wool production, and suggest experiments should be conducted under controlled environmental conditions, with a minimum of stress imposed on the animals.
32
Mason, Susan Leigh. "Metabolism of triacylglycerol-rich lipoproteins in sheep." Lincoln University, 1991. http://hdl.handle.net/10182/1756.
Texte intégralRésumé :
This thesis describes two approaches for studying of lipoprotein metabolism in sheep. The first approach involves the assay of lipoprotein lipase (LPL) activity to determine the role of lipoprotein-triacylglycerol fatty acids in fat deposition in sheep. This enzyme is the rate limiting enzyme in the hydrolysis of fatty acids from lipoprotein-triacylglycerol. The second approach was to characterize and quantify in vivo lipoprotein metabolism using iodinated very low density lipoprotein (¹²⁵I-VLDL) and low density lipoprotein (¹³¹I-LDL). Cross-bred lambs were divided into two treatment groups and either weaned early at 5 weeks of age or remained suckling. Lambs were slaughtered at 12 or 23 weeks at which time the body composition and adipose tissue LPL activity were determined. The differences in rearing led to differences in body composition. The suckled lambs were larger and fatter than weaned lambs. The increased fatness in the suckled lambs was associated with increased LPL activity (U/mg protein) in subcutaneous adipose tissue and was reflected in higher LPL activity in post-heparin plasma (PHP) taken 2 days prior to slaughter. The role of insulin in the regulation of LPL activity was investigated by either infusing a subset of the weaned and suckled lambs with insulin for 7 or 18 weeks or using the euglycemic clamp technique to study the effect of short insulin infusions. The long term infusion of insulin had no significant effect on PHP LPL or on adipose tissue LPL (U/g tissue). However, after infusing insulin for 6h at 6.3 mU.kg⁻·⁷⁵.h⁻¹ during the euglycemic clamps, a two fold increase in LPL activity in biopsied subcutaneous adipose tissue was observed. In the second approach, in vivo lipoprotein metabolism was investigated in 4 lambs using apolipoprotein B as a marker. Following the simultaneous injection of ¹²⁵I VLDL and ¹³¹I VLDL, the specific activities of apoB in VLDL, IDL and LDL fractions were determined. ApoB specific activity curves demonstrated that VLDL is metabolised to IDL and subsequently to LDL. The turnover of VLDL-B (3.45mg.d⁻¹.kg⁻¹) and LDL-B (4.8mg.d⁻¹.kg⁻¹) was calculated by fitting the VLDL-¹²⁵I-B and LDL-¹³¹I-B specific activity data to a mono-exponential equation. The metabolism of lipoproteins, inferred from the study of apoB, was shown to be similar in sheep to that reported in other animals although the amount of lipoprotein synthesised was low. A model to describe the kinetics of apoB metabolism in sheep was developed using SAAM. The proposed model features a three pool delipidation chain for VLDL, and subsystems containing two pools for IDL and LDL. IDL may be catabolised to LDL or cleared directly from the plasma. The developed model can now be used to compare the metabolism of lipoproteins in different physiological states and to design new experiments to study lipoprotein metabolism further.
33
Delaquis, Annick Marie. "The effect of supplementation of alfalfa hay or urea on intake digestibility and rumen fermentation of sheep fed timothy hay /." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63908.
Texte intégral
34
Erkinaro, T. (Tiina). "Fetal and placental haemodynamic responses to hypoxaemia, maternal hypotension and vasopressor therapy in a chronic sheep model." Doctoral thesis, University of Oulu, 2006. http://urn.fi/urn:isbn:9514281659.
Texte intégralRésumé :
Abstract
Knowledge of the effects of maternally administered vasopressors on human fetal and placental haemodynamics is sparse and limited to elective Caesarean deliveries in uncomplicated pregnancies. We hypothesized that, after short-term fetal hypoxaemia, which activates fetal cardiovascular compensatory mechanisms, treatment of maternal hypotension with ephedrine or phenylephrine results in divergent responses in fetal and placental haemodynamics.
Chronically instrumented near-term sheep fetuses with either normal placental function or increased placental vascular resistance following placental embolization were exposed to two subsequent periods of decreased fetal oxygenation caused by maternal hypoxaemia and epidural-induced hypotension. The fetuses that underwent placental embolization were also chronically hypoxaemic.
Fetal and placental haemodynamics were assessed by invasive techniques and by noninvasive Doppler ultrasonography. Our results show that umbilical artery blood flow velocity waveforms cannot be used to derive information of fetal cardiac function. Furthermore, the changes in placental volume blood flows and vascular resistances caused by maternal vasopressor treatment cannot be reliably recognized based on uterine and umbilical artery pulsatility index values.
In response to acute hypoxaemia, a fetus with normal placental function redistributes its right ventricular cardiac output from the pulmonary to the systemic circulation and is able to increase its combined cardiac output, with a concomitant relative decrease in the net forward flow through the aortic isthmus. However, fetal haemodynamic responses to subsequent hypoxaemic insults may vary. Furthermore, the compensatory responses of fetuses with increased placental vascular resistance differ from those of normal fetuses. In these fetuses, repeated episodes of a further decrease in oxygenation lead to lactataemia.
The effects of ephedrine on uteroplacental and umbilicoplacental circulations were more favourable than those of phenylephrine. Ephedrine restored the changes in fetal cardiovascular haemodynamics caused by maternal hypotension to the baseline conditions in both embolized and nonembolized fetuses. Phenylephrine did not reverse fetal pulmonary vasoconstriction or the relative decrease in the net forward flow through the aortic isthmus. Moreover, fetal left ventricular function was impaired by phenylephrine. Although no significant differences in fetal acid-base status were observed in fetuses with normal placental function, the lactate concentrations of the embolized fetuses increased further when maternal hypotension was treated with phenylephrine.
35
Alhamada, Alhamada Moutaz. "Les chevauchements, enregistrés automatiquement lors de la reproduction des ovins, sont indicateurs de la libido des béliers et de la valeur reproductive des brebis." Thesis, Montpellier, SupAgro, 2016. http://www.theses.fr/2016NSAM0032/document.
Texte intégralRésumé :
La demande en produits animaux pousse les éleveurs à réduire les intrants et supprimer les traitements hormonaux pour la maîtrise de la reproduction des ovins. Ces exigences ont relancé les études sur des méthodes qui s’appuient davantage sur les comportements spontanés des mâles et des femelles. Le détecteur électronique des chaleurs, développé par l’UMR Selmet, semblait prometteur et il fallait l’accompagner de validations expérimentales. Ces études ont été réalisées en race Mérinos d’Arles du Domaine du Merle qui sont élevées en système d’élevage extensif et se reproduisent à contre saison. Nous avons tout d’abord validé ce détecteur sur des brebis suivies par vidéo. Nous montrons que 93% des chevauchements sont effectivement enregistrés et comme les brebis en œstrus acceptent plusieurs chevauchements : toutes les brebis sont détectées. Dans une deuxième étape nous avons utilisés plusieurs béliers avec des effectifs plus importants (n=60). Ceci nous a confirmé, pour la brebis des fortes variabilités 1) de la réponse aux traitements hormonaux, 2) de la durée des chaleurs et 3) du nombre de chevauchements par brebis. Pour les béliers, nous avons mis en évidence une forte dispersion du nombre de chevauchements qui s’est répétée, avec les mêmes brebis, sur les cycles suivants. Nous avons ensuite étudié plus précisément le comportement sexuel des béliers en les plaçant en test visuel (méthode de référence) avec quelques brebis en chaleur. Pour cela nous avons évalué 6 béliers entiers Mérinos et 6 béliers vasectomisés Mourérous, à un an d’intervalle lors de la lutte de printemps et aussi à celle d’automne. Nous avons retrouvé les amplitudes classiques des variations saisonnières sur les activités des béliers aux trois saisons.Nous avons montré que la libido des mâles définie par la somme de leurs activités pré-copulatoires ou copulatoires était bien corrélée (r=+0,80, n=18) aux chevauchements mesurés avec le détecteur sur plusieurs centaines de brebis la libido peut être assimilée aux activités copulatoires que nous mesurons avec les chevauchements. De plus, nous obtenons une corrélation claire entre les activités copulatoires observées et collectées automatiquement en troupeaux. Le classement des béliers selon leur libido sont était très répétable intra-saison (de cycle a l’autre) et enter-saison (d’une saison à l’autre). A un an d’intervalle la répétabilité a été meilleur (94%) avec les chevauchements qu’avec les mesures des tests (80%). Sachant que la fertilité des brebis sous-alimentées est plus faible, nous avons étudié les comportements de brebis ayant subi 3 régimes alimentaires contrastés appliqués pendant 3 mois. Nous montrons que la réceptivité et la proceptivité de brebis ne changent pas selon leur état nutritionnel, par contre leur capacité à attirer les béliers (attractivité) est d’autant plus forte qu’elles sont plus lourdes et/ou qu’elles avaient des profils métaboliques favorables (métabolites et hormones). Ces données, obtenues en lot expérimental par des méthodes de référence, ont été validées en troupeau avec le détecteur électronique. Dans la discussion générale, nous reprenons nos résultats pour montrer qu’en système d’élevage extensif les brebis jouent un rôle central dans l’attraction, ou pas, des béliers. Ces béliers, bien que choisis pour la reproduction, ont des libidos très variables mais répétables. Le détecteur de chaleur, inclus dans un système d’élevage de précision, pourrait servir en élevage pour améliorer la reproduction des ovins en s’appuyant sur ces connaissances<br>Automatically recorded mountings of rams provide information on their libido and breeding value of ewes.Abstract:The demand for livestock products pushes farmers to reduce inputs and remove hormonal treatments used to control ewe’s reproduction. These trends put forward research lines that are aimed to study sexual behaviours of both rams and ewes. The electronic oestrus detector, developed by UMR Selmet, looked promising but still had to be accompanied by further experimental validation. Our studies were conducted on Merino’s d’Arles sheep of Domaine de Merle, which are bred in an extensive farming system with a mating period occurring in spring as many other Mediterranean breeds. Our first step was to validate the electronic detector on sheep by comparison to video observation. We showed that 93% of mounts are registered, and as ewes in oestrus accept multiple mounts: all the ewes are detected with this device. In a second step we used several rams (n=6) with a larger number of ewes (n = 60). This confirmed that ewes express a strong variability 1) of the timed response to hormonal treatments, 2) of the oestrus duration and 3) the total number of mounts per ewe. We also demonstrated that the wide dispersion of the number of mounts done by rams was however repeated, with the same flock, in subsequent cycles.Then, we focussed on ram sexual behaviour by placing them with few oestrus ewes under visual test (the reference method). We evaluated 6 intact Merino rams and 6 vasectomized rams of the Mourerous breed, this test was done thrice: at spring one year apart and also at the autumn. We found conventional amplitude of seasonal variations on the activities of rams during the three seasons. We demonstrated that male libido, defined by the sum of their pre-copulatory and copulatory activity, was well correlated (r = + 0.80, n = 18) with the counted mounts by the detector of the same rams but with several hundreds of ewes. Therefore, the libido can be estimated by number of mounts. In addition, we get a clear correlation between the observed copulatory activities and automatically collected mounts within a flock of ewes. We found that ranked rams’ libido scores are repeated. This is very stable within-season (one cycle) and between-seasons (from one season to the next). A one year apart repeatability of mounts was better (94%) within the flock than when measured by mounts number during tests (80%). Given that fertility of undernourished ewes is lower, we studied the behavior of ewes that underwent three contrasting diets applied for 3 months. We observed that receptivity and proceptivity of ewes do not change according to their nutritional status, through against their ability to attract the rams (attractiveness) is much stronger if they are heavier and/or had favorable metabolic profiles (metabolites and hormones). These results were further confirmed within rams’ mating flock (when bodyweight are widespread). In the discussion, we resume our results that show that within extensive livestock system, ewe plays a central role in attracting or not the rams. These rams, although chosen for breeding, have very variable but repeated libido score. The electronic oestrus detector, included in a precision farming system, could be used to improve the breeding of sheep, based on this knowledge.Keywords: sexual behaviour, preferential mating, libido, attractiveness, receptiveness, proceptivity and precision farming
36
O???Connell, Amanda Elizabeth School of Medical Science UNSW. "Consequences of an altered intrauterine environment on the offspring???s renal, cardiovascular and renin angiotensin systems." Awarded by:University of New South Wales. School of Medical Science, 2006. http://handle.unsw.edu.au/1959.4/26320.
Texte intégralRésumé :
This thesis reports the effects of an altered intrauterine environment on the offspring???s renal, cardiovascular and renin angiotensin systems. After a midgestational asphyxial episode in fetal sheep (30 min total umbilical cord occlusion at 90 days; term 150 days) the hydrops that resulted had not completely resolved by 130 days. While the heart and kidneys were apparently unaffected, the brain and lung weights were 37% and 50% lower than sham values, respectively and there were joint contractures. The effects of maternal renal disease on the offspring were investigated. Although in utero fetuses of subtotally nephrectomised ewes (STNx) had altered urine flow rates, sodium excretion, haematocrits, plasma chloride and plasma renin levels, by 1-2 weeks after birth these values in the lambs (STNxL) were similar to controls (ConL) under baseline conditions. Body weight and the weights of most organs were similar, including the kidney, in which glomerular number was normal. In the neonatal period, the lambs were subjected to four challenges: furosemide (2 mg/kg intravenous bolus), infusion of angiotensin II and phenylephrine, intravenous infusion of 0.15M saline (50 ml/kg over 30 min) and haemorrhage (20% estimated blood volume over 10 min). These challenges revealed evidence of programming of several aspects of the renal, cardiovascular and renin angiotensin systems in the STNx offspring. As young adults at 6 months of age, male and female offspring of STNx ewes were normotensive and had normal renal function. On a high salt diet (HSD, 0.17M NaCl in 8L water for 5-7days), female offspring of both groups did not become hypertensive. However, the STNx offspring must have retained salt and water as plasma sodium was increased and haematocrit was decreased. In the STNx offspring only, there was a relationship between glomerular filtration rate (GFR) and mean arterial pressure, indicating an inability to maintain a constant GFR in response to changes in arterial pressure.
37
Joyce, Belinda Jane. "Elastin synthesis in the fetal sheep lung in vivo : effects of physical, metabolic and endocrine factors." Monash University, Dept. of Physiology, 2004. http://arrow.monash.edu.au/hdl/1959.1/5263.
Texte intégral
38
Earl, Colin R. "The regulation of the timing of melatonin secretion in the sheep." Title page, summary and table of contents only, 1989. http://web4.library.adelaide.edu.au/theses/09PH/09phe12.pdf.
Texte intégralRésumé :
Includes bibliographical references (leaves 166-195) Addresses the nature of the central mechanisms involved in the regulation of the circadian pattern of secretion of the pineal hormone melatonin in the highly seasonal Suffolk breed of sheep. Provides new information on the behaviour of the onset and offset of melatonin secretion under different photoperiodic conditions.
39
Stoodley, Marcus A. "Pathophysiology of Syringomyelia /." Title page, contents and abstract only, 1996. http://web4.library.adelaide.edu.au/theses/09PH/09phs882.pdf.
Texte intégral
40
Gore, Mitchell Taylor. "Invitro protein synthesis and degradation and cathepsin D activity in the muscles of selenium-vitamin E deficient sheep." Thesis, Virginia Tech, 1985. http://hdl.handle.net/10919/45729.
Texte intégralRésumé :
Invitro synthesis and degradation capabilities and the cathepsin D activity of the skeletal muscles of experimentally induced Selenium-Vitamin E deficient lambs were investigated. Twenty-one Dorset x Coopworth x Suffolk lambs were blocked by weight and assigned to one of the following treatments: 1) a basal diet of 85% whole shelled corn and 15% mixed grass hay plus a mineral supplement that was low in Se and E (-Se-E), 2) the basal diet and deficient mineral mixture as fed in treatment 1 with the addition of a casein encapsulated fat supplement (-Se-E+fat), 3) the basal diet plus a mineral mixture which contained supplemental Se and E (+Se+E). Upon completion of the feeding trial, lambs which had been receiving the -Se-E treatment had the greatest body and individual muscle weights. The -Se-E+fat treatment had the lowest degradation rates and the highest synthesis rates. Cathepsin D activity was found to be lowest in the -Se-E+fat treatment. The -Se-E treatment was observed to have the highest degradation rate and the next highest synthesis rate indicating an increased rate of muscle turn-over. In all cases, the degradation rates were positively correlated with cathepsin D activity.<br>Master of Science
41
Hough, Denise. "Comparison of two CYP17 isoforms : implications for cortisol production in the South African Merino." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/19951.
Texte intégralRésumé :
Thesis (PhD)--Stellenbosch University, 2012.<br>ENGLISH ABSTRACT: This study describes:
• the comparison of the enzymatic activities of the two ovine cytochrome P450 17 -
hydroxylase/17,20-lyase (CYP17) isoforms expressed in non-steroidogenic COS-1 cells.
The Km and Vmax values for the metabolism of pregnenolone and progesterone were
determined, while time-dependent metabolism of pregnenolone, 17-hydroxypregenolone,
progesterone and 17-hydroxyprogesterone was also reported. The cloning and sequencing of
ovine cytochrome b5 is reported and was co-expressed with CYP17. The results showed that
the wild type 1 (WT1) isoform of ovine CYP17 produce more cortisol precursors than the
wild type 2 (WT2) isoform;
• the analysis of the frequency distribution of the CYP17 genotypes within a South African
Merino population, which were divergently selected for (H-line) or against (L-line) the
ability of a ewe to rear multiple offspring per birthing opportunity. It was observed that the
CYP17 frequency distribution was the same within the H- and L-line, with 78.3 %
heterozygous WT1/WT2 and 21.7 % homozygous WT1/WT1. No homozygous WT2/WT2
individuals were identified;
• the development of a UPLC-MS/MS method for the separation and quantification of all
thirteen adrenal steroids that are produced in the adrenal gland;
• the relative contribution of the CYP17 genotypes in the total steroidogenic output in adult
adrenocortical cells from the adrenal glands of H- and L-line sheep, with particular emphasis
on cortisol production. The adrenocortical cells from the H-line sheep showed a marked
higher cortisol production than the L-line, while adrenocortical cells from homozygous
WT1/WT1 sheep also produced more cortisol than heterozygous WT1/WT2 sheep;
• the blood cortisol responses upon the stimulation of the HPA axis by insulin induced
hypoglycaemia of the H- and L-line sheep with known CYP17 genotypes. It was observed
that the CYP17 genotype and selection line are important factors affecting the cortisol
responses of sheep, where L-line heterozygous WT1/WT2 sheep showed the lowest cortisol
response and glucose recovery; • the association of the CYP17 genotype with behavioural responses of H- and L-line sheep to
flock isolation stress, as well as the association of the CYP17 genotype with ewe
reproduction and lamb output. While reproduction seemed to be unaffected by the CYP17
genotype, the behavioural stress responses of sheep to flock isolation correlated with the
CYP17 genotype, where the heterozygous WT1/WT2 genotype was associated with a wilder
nature.<br>AFRIKAANSE OPSOMMING: Hierdie studie ondersoek:
• die vergelyking van die ensiemaktiwiteite vir twee isoforme van skaap sitochroom P450
17 -hidroksilase/17,20-liase (CYP17), wat uitgedruk was in nie-steroïed genererende COS-
1 selle. Die Km and Vmax waardes was bepaal vir die metabolisme van pregnenoloon en
progesteroon, terwyl die tyd-afhanklike metabolisme van pregnenoloon, 17-
hidroksiepregnenoloon, progesteroon en 17-hidroksieprogesteroon ook gerapporteer word.
Die klonering en volgorde bepaling van skaap sitochroom b5 was gedoen en gevolglik was
sitochroom b5 saam met CYP17 uitgedruk in COS-1 selle. Die resultate het gewys dat wilde
tipe 1 (WT1) meer voorlopers van kortisol produseer as wilde tipe 2 (WT2);
• die frekwensie distrubusie van die CYP17 genotipes in ‘n Suid-Afrikaanse Merino
populasie, waar skape in teenoorgestelde rigtings geselekteer was vir (H-lyn) of teen (L-lyn)
die vermoë van ‘n ooi om geboorte te gee aan veelvoudige lammers per lamgeleentheid. Die
frekwensie distrubusie van CYP17 was dieselfde in beide die H- en L-lyn, waar 78.3 % van
die populasie heterosigoties WT1/WT2 en 21.7 % homosigoties WT1/WT1 was. Geen
homosigote WT2/WT2 individue was geïdentifiseer nie;
• die ontwikkeling van ‘n UPLC-MS/MS metode vir die skeiding en kwantifisering van al
dertien steroïede wat natuurlik geproduseer word in die bynier van die skaap;
• die relatiewe bydrae van die CYP17 isoforme tot die totale steroïedale uitsette vanuit die
bynier kortex selle, vanaf die byniere van H- en L-lyn skape, waar klem geplaas word op die
produksie van kortisol. Die bynierselle van die H-lyn skape het aansienlik meer kortisol
produseer as die L-lyn, terwyl die bynierselle van die homosigotiese WT1/WT1 skape ook
meer kortisol produseer het as heterosigotiese WT1/WT2 skape;
• die bloed kortisol in reaksie tot die stimulering van die hipotalamus-hipofise-adrenale aksis,
deur insulien geïnduseerde hipoglisemiese stress, in skape van die H- en L-lyne met bekende
CYP17 genotipes. Dit was gevind dat die kortisol reaksie geaffekteer word deur beide die
CYP17 genotipe en seleksie lyn, waar L-lyn heterosigotiese WT1/WT2 skape die minste
kortisol geproduseer het en die stadigste herstel van glukose vlakke getoon het; • die assosiasie tussen die CYP17 genotipe en die gedrags reaksies op trop-isolasie, sowel as
ooi-reproduksie en lamuitset, van die H- en L-lyn skape. Die reproduksie parameters was
onafhanklik van die CYP17 genotipe, terwyl ‘n sterk assosiasie gevind was tussen die
CYP17 genotipe en gedrags reaksies op trop-isolasie. Die heterosigotiese WT1/WT2 skape
het ‘n wilder natuur getoon gedurende trop-isolasie in vergelyking met homosigotiese
WT1/WT1 skape.
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Meyer, Amanda Jane. "The impact of prenatal glucocorticoid exposure on the ovine kidney." University of Western Australia. School of Women's and Infants' Health, 2006. http://theses.library.uwa.edu.au/adt-WU2006.0105.
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[Truncated abstract] In obstetric practice, pregnant women at risk of pre-term delivery between 24 and 34 weeks of gestation are administered synthetic glucocorticoids (betamethasone or dexamethasone) to induce fetal organ maturation. During this gestational period, the fetal kidney is undergoing a phase of rapid organogenesis with an increase in renal growth and active nephrogenesis occurring. The studies comprising this thesis examine the effects of prenatal betamethasone exposure on the fetal and adult ovine kidney. The central hypothesis of these studies was that exposure of the fetal kidney to betamethasone in late gestation would change renal structure and induce long-term alterations in the expression of glucocorticoid-sensitive genes and proteins. In the fetal studies, pregnant Merino ewes bearing single fetuses received single or repeated-weekly intra-muscular (i.m.) injections of betamethasone (0.5 mg/kg body weight) or saline commencing on day 104 of gestation (term is 150 days). Kidneys were collected from fetuses at 109, 116, 121 and 146 days of gestation (d). Using gold standard unbiased stereological techniques, the physical disector/fractionator method, total glomerular (nephron) number and glomerular volume were determined in 146 d fetal kidneys exposed to repeated maternal saline or betamethasone administration. In the adult study, kidneys were collected from 3.5-year-old sheep that had been exposed to ... In this thesis I have demonstrated that renal growth restriction as a result of betamethasone exposure is associated with a reduction in fetal nephron endowment. Although betamethasone does not appear to consistently alter nephron number or glomerular size, it may indirectly affect total nephron endowment through effects on renal growth. I have also provided evidence which suggests that lategestation betamethasone exposure in sheep does not program permanent alterations in the renal expression of genes or proteins involved in glucocorticoid hormone action or components of the renin-angiotensin system. Therefore, exposure of the fetal kidney to betamethasone during nephrogenesis may alter renal structure if kidney growth is perturbed; however, there are no persistent alterations in the expression of glucocorticoid-sensitive genes. These findings are consistent with the preservation of normal basal blood pressure in the adult sheep I studied and with the limited results from human studies of late-gestation maternal glucocorticoid administration.
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NEVES, Maria Luciana Menezes Wanderley. "Índices de conforto térmico para ovinos Santa Inês de diferentes cores de pelame em condições de pastejo." Universidade Federal Rural de Pernambuco, 2008. http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/6845.
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Previous issue date: 2008-02-20<br>Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq<br>The objectives of this work were to determine the best physiological parameter indicator of thermal stress in Santa Inês sheeps, to verify coat color influence on tolerance to heat, to determine the most adequate thermal comfort index for these animals under grazing conditions, and to estimate the critical values of comfort index for short hair Santa Inês breed based on the physiological parameters. The experiment was conducted from January to April in agreste region, of Pernambuco state. The rectal temperature (RT), respiratory frequency (RF), and coat surface temperature (CST) were evaluated three times a week in the morning and in the afternoon. The environment was monitored daily, in a meteorological station installed next to the paddock. The measures for regression and correlation analysis among variables were obtained from 15 Santa Inês sheeps with, five animals for each color: white, chestnut, and black. The obtained results showed that the RF was the best physiological parameter for thermal stress. Thermal comfort index (TCI) and the black globe-humidity index (BGHI) were more accurate than the temperature and humidity index (THI) in the heat stress evaluation on Santa Inês sheep. The correlation and regression results suggested a small superiority of the white animals than the others in the heat tolerance. Basing on the RT, the estimated critical values for white, chestnut, and black sheeps were, respectively, 80.0, 79.5, and 78.9 for THI, 92.8, 91.4, and 90.5 for BGHI, and 46.3, 45.5, and 44.5 for TCI. Basing on the RF, the estimated critical values for white, chestnut and black sheeps were, respectively, 76.3; 75.2 and 75.3 for THI, 86.0, 84.0, and 84.2 for BGHI, and 38.0 for TCI in the animals of the three coat colors.<br>Os objetivos deste trabalho foram determinar o melhor parâmetro fisiológico indicador de estresse térmico em ovinos da raça Santa Inês, o índice de conforto térmico mais adequado para estes animais em criação a pasto e estimar os valores críticos dos índices de conforto com base nos parâmetros fisiológicos. O experimento foi conduzido de janeiro a abril na região agreste de Pernambuco. Os parâmetros temperatura retal (TR), freqüência respiratória (FR) e temperatura da superfície do pelame (TSP) foram avaliados três vezes por semana nos períodos da manhã e da tarde. O ambiente foi monitorado diariamente, por intermédio de uma estação meteorológica instalada ao lado do piquete. As medidas para as análises de regressão e correlação entre as variáveis foram obtidas de 15 ovinos da raça Santa Inês, sendo cinco de cada cor: branca, castanha e preta. Os resultados obtidos evidenciaram que a FR foi o melhor parâmetro fisiológico indicador de estresse térmico e que o índice de conforto térmico (ICT) e o índice de temperatura do globo e umidade (ITGU) foram mais precisos que o índice de temperatura e umidade (ITU) na avaliação do estresse 22 pelo calor em ovinos dessa raça. Observou-se pequena superioridade dos animais brancos em relação aos demais quanto a tolerância ao calor. Baseando-se na TR os valores críticos estimados para os ovinos brancos, castanhos e pretos foram, respectivamente de 80,0; 79,5 e 78,9 para o ITU; 92,8; 91,4 e 90,5 para o ITGU e 46,3 45,5 e 44,5 para o ICT. Baseando-se na FR, os valores críticos estimados para os ovinos brancos, castanhos e pretos foram, respectivamente de 76,3; 75,2 e 75,3 para o ITU; 86,0; 84,0 e 84,2 para o ITGU e 38,0 para o ICT nos animais das três cores.
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Relling, Alejandro Enrique. "EFFECT OF GUT PEPTIDES ON HYPOTHALAMIC mRNA CONCENTRATION AND DRY MATTER INTAKE IN RUMINANTS." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1243026530.
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Stackpole, Catherine Amelia. "The effects of isolation and restraint stress, and cortisol, on the responsiveness of the anterior pituitary to gonadotrophin-releasing hormone in rams and ewes." Monash University, Dept. of Physiology, 2004. http://arrow.monash.edu.au/hdl/1959.1/9585.
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McDermott, Joshua D. "The ovine lens cytoskeleton." Lincoln University, 2007. http://hdl.handle.net/10182/700.
Texte intégralRésumé :
The lens of the eye is a vital tissue in the visual system, responsible for the collection and focusing of light on to the retina. Comprised of epithelial cells at differing stages of differentiation, the transparency of the lens is dependent on the highly ordered crystalline structure of lens proteins. The lens consists of several proteins including crystallins (α, β, γ) that make up 90% of the soluble protein, and the lens cytoskeletal proteins. Cytoskeletal proteins contribute only a fraction of the total lens protein, but are thought to play an important role in the establishment and maintenance of transparency. Calpain-induced degradation of these proteins may be involved in the development of cataracts. This has been an area of research at Lincoln University where a flock of sheep genetically predisposed to cataract maintained as a cataract development model. The aim of this research was to investigate the distribution of cytoskeletal proteins in the lens, and to examine the effects of calpain proteolysis on these proteins, with the goal of establishing the role of the lens cytoskeletal proteins in the ovine cataract model. A combination of techniques was used including immunohistochemistry, which required the development of a specific protocol for ovine lenses. Cytoskeletal proteins were identified using immunohistochemistry in lens tissue sections and exhibited characteristic distributions. Actin displayed preferential distribution in the short sides of the fibre cells in the cortex of the lens but was absent in the lens nucleus, while spectrin in the cortex and nucleus was associated with the fibre cell membrane. Filensin was observed in the outer cortex of lens sections associated with the fibre cell membrane and cytoplasm, although the pattern of localisation was indistinct due to the abundance of filensin breakdown products. Vimentin displayed membrane and cytoplasmic association in the outer cortex that diminished toward the lens nucleus, with membrane associated vimentin only persisting in the deeper regions of the cortex and nucleus. Additionally, the effect of novel calpain inhibitors (Cat0059 and Cat811) in preventing proteolysis of lens cytoskeletal protein was investigated and compared with calpain inhibitors developed elsewhere (SJA6017). The inhibitors were tested at between 10 and 0.1 μM (100 nM). All inhibitors were effective at 10 μM. SJA6017 provided significant protection to vimentin at 1 μM. Cat0059 was found to protect spectrin and filensin at 1 μM, but not vimentin, while inhibitor Cat811 was found to protect spectrin only. SJA6017 added to assays at 100 nM offered significant protection to spectrin, and Cat0059 was found to protect filensin and spectrin to a significant degree at 100 nM, indicating the novel inhibitors were comparable to those developed elsewhere in terms of their effectiveness. Taken together, the evidence presented in this thesis shows the cytoskeletal proteins as crucial elements in the lens. Their pervasive presence coupled with evidence that lens cytoskeletal proteins are sensitive to calpain-induced proteolysis that is inhibited with novel calpain inhibitors suggests that the lens cytoskeletal proteins may be useful targets in cataract prevention for future research.
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Corbel, Tanguy. "Mécanismes toxicocinétiques impliqués dans l'exposition foetale au Bisphénol A." Thesis, Toulouse, INSA, 2013. http://www.theses.fr/2013ISAT0034/document.
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Le Bisphénol A (BPA) est un perturbateur endocrinien dont les effets développementaux observés chez les rongeurs soulèvent la question du risque pour la santé humaine relatif à une exposition fœtale au BPA. L’objectif de cette thèse est de déterminer les mécanismes toxicocinétiques impliqués dans l’exposition fœtale au BPA. La caractérisation in vivo dans un modèle intégratif ovin des expositions maternelles et fœtales au BPA et à ses métabolites ont permis d’identifier le transfert placentaire et le métabolisme fœto-placentaire comme les déterminants majeurs de l’exposition fœtale au BPA. Le transfert bidirectionnel du BPA à travers le placenta humain se fait par diffusion passive conduisant à un rapport maximal des concentrations plasmatiques de BPA libre entre le fœtus et sa mère de 1. En revanche, la perméabilité placentaire du BPA-G est très limitée, en particulier dans le sens materno-fœtal. Les activités de conjugaison hépatique du BPA ont été faibles chez le fœtus ovin à un stade précoce de gestation et ont augmenté au cours du développement. Par ailleurs la réactivation des conjugués du BPA mise en évidence ex vivo dans les gonades fœtales ovines pourrait conduire à une exposition locale au BPA actif. L’ensemble de ces données suggère que le début de la gestation pourrait représenter une fenêtre critique d’exposition au BPA<br>Bisphenol A (BPA) an endocrine disruptor interfering with developmental processes in rodents, raises the question of risk for human health related to fetal exposure to BPA. The goal of this work was to determine the toxicokinetic mechanisms involved in fetal exposure to BPA. The disposition of BPA and its metabolites in the maternal-placental-fetal unit in an in vivo ovine model enabled us to identify the placental transfer and the fetal-placental metabolism as the major determining factors of fetal exposure to BPA. Bidirectional placental transfer of BPA occurs by passive diffusion leading to a ratio of free BPA between the fetal and maternal plasma concentrations of about 1. By contrast, the permeability of BPA-G is very limited, particularly in materno-to-fetal direction. The hepatic conjugation activities were very low in ovine fetus at an early stage of development and increased throughout pregnancy. Hydrolysis of BPA conjugates observed ex vivo into fetal ovine gonads could lead to local exposure to native BPA. Altogether, these results suggest that the early stage of pregnancy is a critical window of exposure for the developing fetus
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Tillet, Yves. "Les monoamines de l'encephale du mouton (ovis aries) : etude immunocytochimique de la microanatomie et de l'ontogenese des structures concernees." Paris 6, 1986. http://www.theses.fr/1986PA066580.
Texte intégralRésumé :
L'utilisation d'antiserums reconnaissant la serotonine et les enzymes de synthese des catecholamines a permis la mise en evidence, par immunocytochimie, des structures serotoninergiques et catecholaminergiques dans le snc du mouton. Des investigations identiques faites chez le foetus ont permis de montrer une apparition tres precoce de ces amines dans le snc. Le developpement des structures serotoninergiques est precoce et rapide, plus que celui des structures catecholaminergiques
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Papet, Isabelle. "Catabolisme des acides amines a chaine ramifiee chez l'agneau preruminant : influence d'exces alimentaires en leucine." Clermont-Ferrand 2, 1987. http://www.theses.fr/1987CLF21079.
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Borgs, Peter. "The recirculation of lymphocyte populations in sheep." Phd thesis, 1992. http://hdl.handle.net/1885/143648.
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