Thesis (Ph. D.)--University of Wisconsin--Madison, 1981. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 176-180).

Thesis (D.V.M.)--Université de Zurich, 1979. / Vita. Bibliography: p. 50-58.

Mares have an atypical hormone profile during pregnancy. Systemic progesterone (P4) levels approach zero by day 220 of gestation. Other reduced pregnanes such as 5��-pregnane-3, 20-dione (5��), 5��-pregnane-3��, 20��-diol (����), 3��-hydroxy-5��-pregnan-3-one (3��) and 20��-hydroxy-5��-prenan-3-one (20��), increase to near ��g/mL levels in the peripheral system of the mare until directly before parturition when they decrease. This unusual hormone profile during gestation indicates the possibility that other pregnanes, not P4, are responsible for uterine quiescence and gonadotropin inhibition during pregnancy. Three experiments were conducted to determine if these steroids have biologic activity. Experiment 1 consisted of jugular vein blood samples taken from mares from ten days pre-partum until the foal heat ovulation, approximately 15 days postpartum. Samples were analyzed for luteinizing hormone (LH), follicle stimulating hormone (FSH), and pregnane content. Concentrations of these hormones were analyzed for serial correlations. There was a serial negative correlation with pregnanes and FSH (p=0.0138), which were analyzed on a same day basis, day -5 to day of foaling. There also was a positive correlation with pregnanes and FSH analyzed from day of foaling to 10 days post-foaling (p<0.00l). There was also a significant negative correlation (p=0.0196) between pregnanes and LH, analyzed on a lag basis, day -5 to day of foaling for pregnanes, and day -5 to day of ovulation for LH. There was also a significant negative correlation when pregnanes were analyzed from day of foaling to 10 days post foaling, and LH was analyzed from 10 days before ovulation to day of ovulation (p=0.004). Maximum pre-partum pregnane levels did not affect time to ovulation (p=0.34). In experiment 2 equine anterior pituitary glands were harvested and the cells plated to begin a primary cell culture. After attachment, the cells were divided into treatment groups: P4, 5��, ����, 20��, 3�� or a control and each group subjected to a 1.0nM Gonadotropin Hormone Releasing Hormone (GnRH) challenge. Subsequently cells and medium were collected and analyzed for LH and FSH content using radioimmunoassay (RIA). The cells did exhibit a response to GnRH (p=0.015 between positive and negative controls) and there was a treatment effect for FSH (p=0.0058); only 3�� resulted in significantly more FSH release than the positive control (p=0.043) after stimulation with GnRH. There was no treatment effect on LH (p=0.56). Experiment 3 analyzed the response of equine uterine myometrial tissue to pregnane treatment. Myometrial tissue was harvested and placed in a 37��C Krebs buffered saline bath, connected to a physiograph and repetitive spontaneous smooth muscle contraction was induced with oxytocin. Tissue was then treated with P4, 5��, ����, 20��, 3�� or a control (ethanol). The amplitude and frequency of the spontaneous contractions were measured and compared to the control. There were no differences between post treatment responses of the control and pregnane treated samples in either frequency (p=0.78) or amplitude (p=0.63) of myometrial contractions. From these data we conclude that in vivo there is a significant and differential physiologic relationship between pre-partum pregnanes and gonadotropins. Due to lack of response it is unlikely that pregnanes inhibit pituitary secretion, and thus may exert their effects elsewhere, such as at the hypothalamus. The involvement of pregnanes in modulating myometrial contractions remains unclear. It is likely that P4 does play a role in decreasing myometrial responses to OT, however, that result was inconsistent in this study. / Graduation date: 2003

An increase in time to ovulation following parturition could result in economic loss if the mare cannot successfully conceive within a short time after foaling. To evaluate if a difference exists in reproductive efficiency of fat- (body condition score of 7 to 8) versus moderately-conditioned (body condition score of 5 to 6), 24 mares were allotted to and maintained in their respective group from late gestation until pregnancy was confirmed following breeding on the second post-partum estrus. Days to ovulation, interovulatory intervals, conception rates, and endocrine profiles were analyzed. Serum concentrations of thyroxine (T4), insulin-like growth factor-1 (IGF-1) and leptin were assayed in order to characterize normal circulating blood concentrations. There were no differences (P>0.05) in mean interval from parturition to first ovulation (14.41 ± 1.07 and 16.18 ± 1.06 d), first to second postpartum ovulation (22.91 ± 1.07 and 24.33 ± 0.93 d), or in conception rates (91.67% and 83.33%) between the 2 groups. However, mares in moderate conditioning did lose a greater percentage of body fat upon foaling as compared to fleshier mares (0.82% versus 0.35%). Leptin concentrations were not different between the groups (P>0.05). Nevertheless, serum concentrations of T4 were higher (P<0.01) and IGF-1 concentrations lower (P<0.01) in moderate- as compared to fat-conditioned mares during times of ovulation and the interovulatory period. Results indicate that mares maintained in a fleshy body condition are not prone to reproductive dysfunction or lowered levels of fertility. The significance of the current results is important as it reassures the breeder that mares in a fatter body condition score (BCS of 7-8) should not demonstrate sub-fertility related to level of body fat. Additionally, results indicate that mares may need to be kept in a BCS of 6 in order to avoid losing enough weight upon parturition and early lactation to bring the BCS below 5. It suggests that varying amounts of circulating T4 and IGF-1 do not affect reproductive capabilities of mares in a BCS of greater than 5 following parturition.

An increase in time to ovulation following parturition could result in economic loss if the mare cannot successfully conceive within a short time after foaling. To evaluate if a difference exists in reproductive efficiency of fat- (body condition score of 7 to 8) versus moderately-conditioned (body condition score of 5 to 6), 24 mares were allotted to and maintained in their respective group from late gestation until pregnancy was confirmed following breeding on the second post-partum estrus. Days to ovulation, interovulatory intervals, conception rates, and endocrine profiles were analyzed. Serum concentrations of thyroxine (T4), insulin-like growth factor-1 (IGF-1) and leptin were assayed in order to characterize normal circulating blood concentrations. There were no differences (P>0.05) in mean interval from parturition to first ovulation (14.41 ± 1.07 and 16.18 ± 1.06 d), first to second postpartum ovulation (22.91 ± 1.07 and 24.33 ± 0.93 d), or in conception rates (91.67% and 83.33%) between the 2 groups. However, mares in moderate conditioning did lose a greater percentage of body fat upon foaling as compared to fleshier mares (0.82% versus 0.35%). Leptin concentrations were not different between the groups (P>0.05). Nevertheless, serum concentrations of T4 were higher (P<0.01) and IGF-1 concentrations lower (P<0.01) in moderate- as compared to fat-conditioned mares during times of ovulation and the interovulatory period. Results indicate that mares maintained in a fleshy body condition are not prone to reproductive dysfunction or lowered levels of fertility. The significance of the current results is important as it reassures the breeder that mares in a fatter body condition score (BCS of 7-8) should not demonstrate sub-fertility related to level of body fat. Additionally, results indicate that mares may need to be kept in a BCS of 6 in order to avoid losing enough weight upon parturition and early lactation to bring the BCS below 5. It suggests that varying amounts of circulating T4 and IGF-1 do not affect reproductive capabilities of mares in a BCS of greater than 5 following parturition.

Thesis--Auburn University, 2007. / Abstract. Includes bibliographic references (p.30-40).

Thesis--Auburn University, 2008. / Abstract. Vita. Includes bibliographical references (p. 43-50).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1983. / Typescript. Vita. Includes bibliographical references.

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Filosofia e Ciências Humanas. Programa de Pós-Graduação em Geografia. / Made available in DSpace on 2012-10-21T02:43:24Z (GMT). No. of bitstreams: 1 204217.pdf: 3539671 bytes, checksum: 5bdf890e97360c3454f81757f6c9f3ca (MD5) / O presente estudo teve como principal objetivo comparar as variações morfodinâmicas ocorridas na praia dos Ingleses, Ilha de Santa Catarina # SC, em dois períodos distintos, buscando identificar os fatores responsáveis por essas mudanças. Através do monitoramento de perfis praiais e do levantamento de informações climáticas e oceanográficas foi possível estabelecer as principais relações entre as variações dos perfis e seus agentes modificadores. As maiores variações do perfil estiveram associadas às ondulações de leste e a fortes e constantes ventos do quadrante norte, mostrando a forte relação entre a forma e orientação da praia e a incidência desses agentes. Por sua vez, fases de estabilidade/acresção estiveram associadas às ondulações de sul e sudeste, assim como a menor energia de ondas. O primeiro período da pesquisa (outubro/1996 a setembro/1997), teve como característica a alternância de episódios erosivos/acrescivos, resultando na maior variação dos perfis e conseqüentemente maior mobilização do material sedimentar da praia (444 m³/m). O segundo período (setembro/2000 a outubro/2001) foi caracterizado pelo predomínio de uma fase deposicional, resultando na menor mobilidade dos perfis (290 m³/m).

Made available in DSpace on 2014-06-11T19:25:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2003-04-24Bitstream added on 2014-06-13T20:53:32Z : No. of bitstreams: 1 mana_mr_me_rcla.pdf: 1988551 bytes, checksum: 727d480808d02d1fd8b410fb25a79499 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Phobos e Triton são dois satélites que estão decaindo devido efeitos da maré. Ambos passarão por várias \ressonâncias seculares sendo que Triton, cruzará também ressonâncias orbitais envolvendo os satélites mais internos de Netuno. Este problema foi inicialmente estudado por Yokoyama (2002) considerando várias hipóteses simplicado- ras. Aqui fazemos importantes generalizacões incluindo a elipticidade da órbita de Marte, perturbações planetárias, precessão do equador e integracões por tempos muito mais significativos. Os resultados mostram interessantes capturas e escapes, os quais são altamente sensíveis æas condicões iniciais. Na dupla ressonância (Marte-Phobos) , observa-se uma variação da inclinaçao muito mais significativa do que aquela apontada em Yokoyama (2002). Nas ressonâncias orbitais para o problema de Netuno-Triton, verifica-se a não ocorrência de capturas nas comensurabilidades retrógradas. O efeito da perturbação do achatamento é muito importante. Por outro lado, mesmo para valores relativamente próximos dos semi-eixos (satélite e Triton) que ocorrer~ao no futuro, algumas experi encias mostraram que o satélite interno pode permanecer estável por tempo relativamente longo, que os planos de suas órbitas estarão ainda mais separados devido o efeito da maré que aumentará o sin(IT ). / Under the action of the tides, the orbits of Phobos and Triton are spiralling in towards their host planets. The main purpose of this work is to analyze some interesting features that will occur while these orbits are contracting, i. e., these satellites will pass through some secular and orbital resonances. Here we revisit a previous work of Yokoyama (2002) taking a more complete model for the motion of the planet. The integrations are extended to much longer time. Then it is shown that the escapes are very sensitive to the initial con- ditions. The possibility of the existence of an \universal inclination is brie°y discussed. Phobos will face an interesting case of \double resonance which plays an important role , because a new resonance will be subsequently encountered. For Neptune-Triton system, it is shown that the e®ect of some orbital retrograde resonances can be very weak if the oblateness of the planet is neglected. No capture in these resonances seems to be possible. Due to the high inclination of Triton's orbit, in some cases an inner satellite can survive for some moderate time even when it's semi major axis is rather close to Triton's semi major axis.