• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 181
  • 145
  • 24
  • 16
  • 11
  • 7
  • 6
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • Tagged with
  • 494
  • 142
  • 40
  • 40
  • 39
  • 34
  • 32
  • 31
  • 31
  • 31
  • 30
  • 30
  • 25
  • 25
  • 24
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
321

Aspectos morfofuncionais da próstata feminina do gerbilo durante o ciclo estral = efeitos da ovariectomia e posteior exposição prolongada ao estradiol e estradio + testosterona / Morphofunctional aspects of gerbil female prostate during the estrous cycle : effects of ovariectomy and subsequent long-term exposure to estradiol and estradiol plus testosterone

Silva, Diego Augusto Lopes da, 1987- 20 August 2018 (has links)
Orientadores: Sebastião Roberto Taboga, Fernanda Cristina Alcântara Santos / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-20T07:20:55Z (GMT). No. of bitstreams: 1 Silva_DiegoAugustoLopesda_M.pdf: 2979999 bytes, checksum: 9599710cd18bf699e32f5e46a65eb134 (MD5) Previous issue date: 2012 / Resumo: A próstata feminina é uma glândula funcionalmente ativa encontrada em diversas espécies de mamíferos, incluindo humanos e roedores. Em fêmeas adultas de gerbilos, a próstata apresenta localização parauretral, exibindo íntimo contato com a parede da uretra média e distal. Esta glândula é homóloga a próstata ventral de roedores machos, sendo formada por um conjunto de glândulas e ductos inseridos em um estroma fibromuscular. O estudo da morfofisiologia prostática nas fases do ciclo estral tem demonstrado que a próstata feminina é influenciada pelas oscilações nos níveis séricos de estradiol e progesterona. Assim, tornam-se necessários estudos que avaliem o efeito da exposição ao estradiol em longo prazo, com o objetivo de observar como este esteróide atua no desenvolvimento de lesões prostáticas. Além disso, de igual importância é avaliar a interação dos estrógenos com outros esteróides circulantes, a fim de se avaliar quais associações hormonais são necessárias para manter o equilíbrio homeostático da próstata feminina do gerbilo. A partir do proposto, o objetivo deste estudo foi avaliar o efeito da administração prolongada de estradiol, e de estradiol + testosterona, sobre a próstata de fêmeas ovariectomizadas. Para isso, as fêmeas adultas foram submetidas à intervenção cirúrgica para remoção dos ovários e, após 10 dias de recuperação, foram submetidas à administração de estradiol, e de estradiol + testosterona. Após trinta dias de tratamento, os animais foram sacrificados e as glândulas prostáticas submetidas a análises morfológicas, morfométrico-estereológicas e sorológicas. Alterações morfológicas e fisiológicas foram observadas em todos os grupos experimentais. A restrição hormonal resultante da ovariectomia causou grande regressão glandular e diminuição da atividade secretora, aspectos revertidos pela exposição dos animais ao estrógeno isolado e conjugado à testosterona. Entretanto, esses hormônios não foram capazes de reestabelecer a histoarquitetura normal do tecido. Foram observadas, inclusive, algumas lesões presentes principalmente nos grupos tratados, tais como inflamações e neoplasias intraepiteliais. A imunorreação para o ER-? foi reduzida nos núcleos do estroma prostático após castração e foi recuperado com os tratamentos. Já a localização de ER-? no núcleo das células epiteliais mostrou-se muito semelhante em todos os grupos. Sugere-se, ainda, uma atuação do estradiol na regulação dos níveis séricos de prosgesterona e testosterona. Sendo assim, conclui-se que a histoarquitetura normal da glândula nas fêmeas está relacionada ao equilíbrio entre os hormônios ovarianos e que, dentre eles, o estradiol e a testosterona desepenham papel importante na homeostasia prostática desses animais / Abstract: The female prostate is a functional gland found in several mammal species, including humans and rodents. In adult female gerbils, the prostate shows paraurethral localization, exhibiting intimate contact with medial and distal urethra wall. This gland is homologous to ventral prostate in male rodents, composed by a group of acini and ducts inserted into a fibromuscular stroma. Prostate morphophysiology estudies during estrous cycle have shown that female prostate is influenced by estradiol and progesterone serum levels oscillations. Thus, studies which evaluate the effect of long-term exposure to estradiol become necessary, in order to observe the way this steroid acts by on prostate lesions development. Furthermore, it is also important to evaluate hormonal interaction among estradiol and other serum steroids with the aim of evaluating which hormonal associations are necessary to maintain the homeostatic balance of gerbil female prostate. Hence, this study role was to evaluate the effect of estradiol and estradiol plus testosterone long-term exposure on the prostate of ovariectomized females. To make it possible, adult females underwent to surgical intervention to remove both ovaries and, after 10 days recovering, they received estradiol or estradiol plus testosterone doses. After 30 days of treatment, the animals were euthanized and de prostate glands were submitted to morphological, morphometric-estereological and serological analysis. Morphological and physiological alterations were observed in all experimental groups. Hormonal deprivation caused by castration brought glandular atrophy and decreased secretory activity. These aspects were reverted by animals exposure to isolated estrogen and estrogen plus testosterone conjugation. However, these hormones were not able to reestablish the tissue normal histoarchitecture. Some lesions were even observed mainly in tratment groups, like inflammations and intraepithelial neoplasias. The imunoreaction for ER-? decreased in prostate stroma nuclei after castration and was restablished with treatments. On the other hand, the epithelium ER-? expression was similar in all groups. It also seems that there is a role played by estradiol in testosterone and progesterone serum levels regulation. In conclusion, normal histoarchitecture of gerbil female prostate is related to ovarian hormones balance and estradiol and testosterone play an important role in prostatic homeostasis in these animals / Mestrado / Histologia / Mestre em Biologia Celular e Estrutural
322

Factors affecting the demography of a lek-mating bird: the greater prairie-chicken

Nooker, Jacqueline Kay January 1900 (has links)
Doctor of Philosophy / Department of Biology / Brett K. Sandercock / Sexual selection via female choice and male-male aggression leads to elaboration of male traits. If male traits correlated with reproductive success are honest signals of male quality, survival costs may be associated with the expression of those traits. Testosterone (hereafter ‘T’) may enhance male breeding success, but T can also reduce immunocompetence and survival. Socially monogamous male birds with higher circulating T experience reproductive advantages, but the role of T in lek mating systems is largely unknown. To address these issues, I individually marked and conducted focal behavioral observations of greater prairie-chickens (Tympanuchus cupido) at five lek sites over a 5-year period. Females were fitted with radio-telemetry to monitor nesting success and survival. I examined the relationship between male traits and mating success using multinomial discrete choice models, a statistical method not previously applied to studies of sexual selection. Male mating success was highly skewed at greater prairie-chicken leks with 18.5% of males obtaining 87.2% of all successful copulations (n = 108 males; 85 copulations). Mating success was influenced most by male behavior, followed by several morphological attributes. The role of T was quantified using blood samples and by experimentally implanting a subset of males with T. T did not consistently affect mating success. Non-territorial males had lower T levels than territorial males. Among territory holders, T was unexpectedly negatively correlated with mating success. However, the odds of receiving a copulation were 4.3 times (0.42 to 45.3) greater for T-implanted males than males with sham implants. Future work should explore the interactions among the immune system, parasite load, and mating success of prairie-chickens. Annual survival of male prairie-chickens was not related to mating success, behavior, age or T level, suggesting there is no cost of increased male mating success. Like males, reproductive success of females was also highly skewed because < 10% of nests successfully hatched young. Comparisons of seasonal and annual survival rates indicate that females experience increased mortality during the breeding season relative to the nonbreeding season. Synthesis of field estimates of demographic parameters indicates prairie-chicken populations will decline without changes in rangeland management to reduce predator numbers or provide more nesting cover.
323

The effect of insulin, leptin and inflammatory cytokines on reproductive health and hypogonadism in males diagnosed with the metabolic syndrome

Leisegang, Kristian January 2013 (has links)
Philosophiae Doctor - PhD / The metabolic syndrome (MetS) is a collection of various metabolic, hormonal and immunological risk factors that cluster together, closely related to poorly understood phenomena such a hyperinsulinaemia (insulin resistance), hyperleptinaemia (leptin resistance), a low grade, systemic and chronic inflammation and, in males, hypogonadism. Infertility is increasing globally, and male factor infertility accounts for a large percentage of couples who are not able to conceive. The relationship between components of MetS and male reproductive health is not clear, and requires further investigation, as does the impact of MetS on male reproductive health in a case controlled study. The impact of hyperinsulinaemia, hyperleptinaemia and inflammatory cytokines on the male reproductive tract also requires investigation. Furthermore, it is hypothesised that these phenomena negatively impact steroidogenesis cascades. In order to investigate this, a case controlled study and TM3 Leydig cell culture experiments were designed.Participants were recruited from public advertisements, and screened for strict exclusion criteria, including acute or chronic inflammation, hormonal treatments, vasectomy and leukocytospermia (> 106/ml). Following clinical diagnostics, 78 males were either placed into a control group (CG) or the MetS group, with numerous parameters compared between them. Serum was assayed for routine risk markers including HDL cholesterol, triglycerides, glucose and C-reactive protein (CRP). Saliva was assayed for free testosterone and progesterone. Semen samples underwent semen analysis for ejaculation volume, sperm concentration and motility, vitality, morphology and leukocyte concentration, in addition to mitochondrial membrane potential (MMP) and DNA fragmentation (DF). Both serum and seminal fluid were further assayed for insulin, leptin, tumour necrosis factor-alpha (TNF ) and interleukins 1-beta (IL1 ), 6 (IL6) and 8 (IL8). Glucose was also assayed in seminal fluid. Separately, hCG stimulated TM3 Leydig cells were exposed to varying concentrations of insulin (0.01, 0.1, 1 & 10 pg/ml), TNF , IL1 , IL6 and IL8 (0.1, 1, 10 & 100 pg/ml) for 48 hours at optimal cell culture conditions. TM3 cell viability, protein concentration and testosterone and progesterone concentrations were assessed.XXII Results indicated that males in the MetS group (n=34) had significantly increased body mass index, waist circumference, blood pressure, triglycerides, glucose, and Creactive protein (CRP) with decreased HDL cholesterol, as compared to the CG. Furthermore, ejaculation volume, sperm concentration, total sperm count, progressive and total motility were significantly decreased in the MetS group, and sperm with abnormal MMP and DF were increased in this group. No difference was found for morphology. Serum and seminal insulin, leptin, TNF , IL1 , IL6 and IL8 were all significantly increased in the MetS group. Both testosterone and progesterone were also significantly decreased in the MetS group. Insulin increased testosterone and decreased progesterone in the TM3 cells. TNF , IL1 and IL6 all decreased testosterone and progesterone concentrations and TM3 cell viability. IL8 increased TM3 cell viability and decreased progesterone, will no effect on testosterone. These results suggest MetS is associated with decreased fertility potential in males. Furthermore, a significant increase in seminal insulin, leptin, TNF , IL1 , IL6 and IL8 suggests local reproductive tract inflammation in the absence of leukocytospermia. Strong correlations between serum and seminal insulin, leptin, TNF , IL1 , IL6 and IL8, as well as serum CRP, imply that these systemic phenomenons are related to the reproductive tract changes observed. Therefore, the underlying pathophysiology of MetS negatively affects male reproduction, in addition to general health and wellbeing. A decrease in progesterone and testosterone suggests a collapse in steroidogenesis cascades. Additionally, inflammation, increased leptin and insulin resistance likely contribute to this collapse in steroidogenesis based on TM3 cell culture experiments. These results provide novel avenues for further investigations.
324

Factors affecting the timing and success of sockeye salmon spawning migrations

Crossin, Glenn Terrence 11 1900 (has links)
Migration timing is a conserved life-history trait. To address the hypothesis that reproductive hormones are principal determinants of migration timing, I physiologically biopsied over 1000 sockeye salmon and monitored their subsequent behaviour with acoustic and radio telemetry as they migrated from the Pacific Ocean toward and into the Fraser River, and then onward to distant spawning areas. Links between physiology, behaviour, and survival were examined. Circulating testosterone was found to be positively correlated with the rates of river entry in Late-run females but not in males, despite having concentrations that were equal if not higher than those of females. The notion of protandrous migration, in which males synchronize their activities to the reproductive and migratory schedules of females, was postulated as the basis for this difference. Once in river however, successful males and females were those that (1) took longest to enter the river, and (2) had high somatic energy, low testosterone, and low gill Na+,K+-ATPase activities. An experimental test of the effect of reproductive hormones on the regulation of migration timing proved inconclusive. Relative to controls, GnRH and (or) testosterone treatment did not influence rates of ocean travel by males. Unfortunately, no females were examined. Nevertheless, significant, positive correlations between initial testosterone and travel times were found irrespective of hormonal treatment, which was unexpected but consistent with the previous studies. In an experimental simulation of an ‘early’ migration, normally timed Late-run sockeye exposed to typical 10 ºC river temperatures and then released to complete migration were 68% successful. In contrast, salmon held at 18 °C and released were half as successful. The expression of a kidney parasite was near maximal in the 18 °C fish and undetectable in the 10 °C fish. Only gill Na+,K+-ATPase activity differed between groups, with a drop in the 18 °C fish. Though no clear stress, reproductive, or energetic differences were observed between groups, the ultimate effect of high temperature treatment was high disease expression, slowed migration speeds, and high migration mortality. Changes in reproductive schedules, due to changes in latitudinal ocean distributions, are discussed as potential causes of early migration by Late-run sockeye. / Forestry, Faculty of / Graduate
325

Rapid social regulation of 3β-HSD activity in the songbird brain

Pradhan, Devaleena S. 11 1900 (has links)
Rapid increases in plasma androgens are generally associated with short-term aggressive challenges in many breeding vertebrates. However, some animals such as song sparrows (Melospiza melodia) are aggressive year-round, even during the non-breeding season, when gonads are regressed and systemic testosterone (T) levels are non-detectable. In contrast, levels of the prohormone dehydroepiandrosterone (DHEA) are elevated year-round in the plasma and brain. The local conversion of brain DHEA to potent androgens may be critical in regulating non-breeding aggression. 3β-hydroxysteroid dehydrogenase/Δ4-Δ5 isomerase (3β-HSD) catalyzes DHEA conversion to androstenedione (AE) and the cofactor NAD⁺ assists in this transformation. In this thesis, I asked whether brain 3β-HSD activity is regulated by social encounters in seasonally breeding male songbirds. In Experiment 1, I looked at the long-term seasonal regulation of brain 3β-HSD activity. 3β-HSD activity was highest in the non-breeding season compared to the breeding season and molt. In Experiment 2, I hypothesized that brain 3β-HSD activity is rapidly regulated by short-term social encounters during the non-breeding season. A 30 min social challenge increased aggressive behavior. Without exogenous NAD⁺, there was ~355% increase in 3β-HSD activity in the caudal telencephalon and ~615% increase in the medial central telencephalon compared to controls (p<0.05). With exogenous NAD⁺, there was no effect of social challenge on 3β-HSD activity. These data suggest that endogenous cofactors play a critical role in the neuroendocrine response to social challenges. The increase in brain DHEA conversion to AE during social challenges may be a mechanism to rapidly increase local androgens in the non-breeding season, when there are many costs of systemic T. / Science, Faculty of / Zoology, Department of / Graduate
326

Effect of Chronic Alcohol Abuse and Resistance Training on the Skeletal Muscle Androgen Receptor Concentration of Rats

Vingren, Jakob L. 08 1900 (has links)
The purpose was to examine the effect of chronic alcohol abuse on the androgen receptor content (AR) in skeletal muscle, and to determine if this effect was influenced by resistance training. Thirty-four male rats (456 ± 1 g; mean ± SE) were divided into 4 groups: Sham exercise-Ethanol, Sham exercise-Normal diet, Exercise-Ethanol, and Exercise-Normal diet. Both Exercise groups underwent a 6-week "squat" resistance training protocol and both Ethanol groups received an alcohol-rich diet throughout the 6-week period. Western blot analysis showed no effect of alcohol or resistance training on the AR of the extensor digitorum longus. For the rectus femoris, alcohol caused a decline in the AR (p=0.01). This reduction was not attenuated by resistance training. The AR of the soleus was not affected by chronic alcohol abuse alone; however, the resistance training induced increase in the AR was prevented by chronic alcohol abuse (p=0.03).
327

A PCOS-like Drosophila Melanogaster model

Badji, Aisha January 2019 (has links)
Polycystic ovary syndrome (PCOS) is a female endocrine disorder defined by high androgen levels and presence of polycystic ovaries. PCOS is characterized by menstrual irregularities, anovulation, infertility, hyperandrogenism, insulin resistance, abdominal obesity, chronic inflammation and increased hair growth. The diagnosis is based on 2003/2004 Rotterdam criteria, which is based on the presence of the following phenotypes: anovulation, clinical and biochemical marks of hyperandrogenism and polycystic ovarian morphology. Theoretical causes could be genetical, environmental or maternal imprinting. Drosophila Melanogaster, a model used broadly in disease research, could bear promising insights to this syndrome. Besides having a lifecycle characterized by a 12 days metamorphism, these species of flies have the ecdysone (steroid) hormone, similar to the human testosterone and the body systems similar to those of the human body. This laboratory work involved the development of a PCOS-like drosophila fly model through exposure to 10mg/ml of testosterone after 24 hours of starvation. Data collection comprised measurements of weight and length, anovulation, triglyceride quantification and RT-qPCR for quantification of inflammatory and PCOS-related genes. Results showed significant differences in response to physical stress among the four groups of flies. Variation in weight and length values, as well as in fecundity, triglyceride assay and relative expression levels were also observed. Although the expression levels of inflammatory and PCOS- related genes were not significantly affected, homeostasis was clearly affected by metabolic disturbances. These observations lead to the conclusion that further experiments should be done in order to establish a more comprehensive definition of the syndrome.
328

Testosterone, Dominance, and Depression in Recently Married Couples

Quiñones-Torres, Gabriela I 29 August 2014 (has links)
Dominance refers to the wide set of behaviors individuals engage in with the intention of achieving or maintaining social status. Considering the relevance of these behaviors in the dynamics of close relationships, this study examined relations among testosterone, dominance, and the emotional health of a total of 225 opposite sex newlywed couples. An original measure of dominance was developed that accounted for both positive and negative manifestations, as well as situational and dispositional qualities of these status-promoting behaviors. Structural equation analyses revealed that dominance behaviors predict depression for both wives and husbands, and that positive and negative aspects of dominance contribute differently to spouses’ depression. Higher levels of depressive symptoms were related to reports of more dispositional hostility for both husbands and wives, as well as to greater submission during a conflict situation. In turn, greater assertiveness was related to fewer depressive symptoms for both husbands and wives. A subset of dominance behaviors reflecting spouses’ appraisals of having had more power, influence, and control relative to their partners during the conflict interaction, exclusively predicted more depressive symptoms for wives. Finally, lower levels of testosterone were indirectly associated with more depressive symptoms for husbands, and this relation was partially mediated by dominance behaviors. Implications of our findings, as well as limitations, are discussed in light of the existent literature and directions for future research on the interpersonal and biological aspects of marital well-being are considered.
329

Alterations in urinary levels of n1-acetylspermidine in response to castration and testosterone replacement therapy in the rat

Lettes, Andrew A. 01 January 1980 (has links)
Castration and testosterone replacement therapy served as a model to assess anabolic activity in the rat. The present study was undertaken to examine more closely whether changes in cellular anabolic activity are reflected in subsequent alterations of urinary N1 -acetylspermidine excretion. A sensitive fluorometric assay was employed which utilized the dansylation reaction . The dansylated derivatives were quantitated by normal phase high pressure liquid chromatography. This assay system exhibited a range of linearity from 0.1 to 10 nanomoles which encompassed the physiological variability observed during analysis of urinary N1-acetyl spermidine. The normal level of N1-acetylspermidine excreted in rat urine was found to be 803.1 ± 208.9 nanomoles per day (mean ± 1 S.D.). In addition both N8-acetylspermidine and acetyl putrescine were detected, but not quantitated. Due to the high variability of the polyamine excretion, no statistically significant difference could be detected between castrated animals, castrated animals receiving testosterone, and sham operated animals. Still some trends were noted which were in agreement with the hypothesis that urinary excretion of polyamines may reflect the anabolic state of the animal. Further studies will be required to determine whether or not a correlation between anabolic activity and urinary excretion of acetylated polyamines exists.
330

The prevalence and associations of low testosterone levels and erectile dysfunction in a male diabetic urban population

Kemp, Tanja January 2014 (has links)
Introduction: According to the literature, low serum testosterone levels are associated with diabetes mellitus. Minimal data exist for its prevalence or predictors in South Africa. Erectile dysfunction is a common condition in diabetic patients. The prevalence and predictors in our patient population is unknown. Methods: An observational, cross-sectional study was performed in 150 consecutive male diabetic patients over the age of 50 years in the Diabetic clinic of Steve Biko Academic Hospital. These patients were evaluated for diabetes control and complications, the presence of erectile dysfunction and for hypogonadism symptoms. Morning serum testosterone levels were done. Subjects with low testosterone levels were compared to those with normal levels. Results: The mean age of the patients was 62 years (standard deviation (SD) 7.87), 91.3% had type 2 diabetes, and 84.7% were on insulin. The mean duration of diabetes was 15 years (SD 8.65). The mean body mass index was 30.7 (SD 5.37), the mean waist circumference was 112.4cm (SD 16.42), the median creatinine was 96μmol/L (interquartile range (IQR) 79-133) and the median HbA1C was 7.85% (IQR 6.80-9.30). Ischaemic heart disease was previously diagnosed in 40.7% of patients. Some degree of erectile dysfunction was reported in 95.3% of the patients with 51.3% reporting serious dysfunction. The prevalence of androgen deficiency symptoms was 94.7%. Fifty percent of the men had low total testosterone levels; 40.7% had low modified calculated bioavailable testosterone levels, and in 27.3% both were low. With multivariate logistic regression the significant factors associated with low total testosterone were waist circumference and known cardiovascular disease. For a low modified calculated bioavailable testosterone level significant variables were age, diabetes duration and body mass index and for an outcome defined as both the above the significant factors were diabetes duration, body mass index, and known cardiovascular disease. With multivariate logistic regression the significant factors associated with erectile dysfunction were age, body mass index, peripheral neuropathy score, and diuretic therapy. The prevalence of symptoms of androgen deficiency was very high with 94.7% of all patients reporting a significant amount of symptoms on the Androgen Deficiency in Adult Males (ADAM) questionnaire. If only the total serum testosterone level was evaluated instead of the modified calculated bioavailable testosterone, the sensitivity was 69%, the specificity was 63%, with a poor positive predictive value of only 56%. The negative predictive value was better at 75%. Differences in quality of life scores were only seen for some erectile dysfunction subgroups but not for low testosterone levels. Conclusion: This study confirms the high prevalence of low testosterone levels and of erectile dysfunction in diabetic male patients in a tertiary setting, and argues in favour of universal screening of this population group. Multiple predictors of low testosterone levels and of erectile dysfunction were identified. The ADAM questionnaire was not useful in identifying subjects with a low testosterone level. Total testosterone testing alone performed poorly in comparison with modified calculated bioavailable testosterone and is not the recommended test of choice. Erectile dysfunction negatively affected the quality of life. / Dissertation (MSc)--University of Pretoria, 2014. / gm2015 / Clinical Epidemiology / MSc / Unrestricted

Page generated in 0.0765 seconds