SEARCH · Search PubMed
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
This article highlights the advances in feline endocrinology, excluding diabetes mellitus and hyperadrenocorticism, which have recently been reviewed elsewhere. The goal will be to provide clinically relevant information regarding pathogenesis, diagnosis, and treatment options for these feline endocrine disorders.
Critical illness provides major stresses on all body systems, including those serving important regulatory functions. Endocrinologic and metabolic abnormalities are common on presentation and during hospitalization in the intensive care unit. Some of these abnormalities are the focus of this article. The authors review abnormalities of the adrenal and thyroid glands and in the metabolism of glucose, and include a brief review of abnormalities of sodium and calcium metabolism.
In reviewing the literature, this paper assesses the current level of understanding of the hormonal control of the ovarian cycle and pregnancy in the elephant. Data are compiled from two genera, Elephas maximus and Loxodonta africana, recognizing differences where known to exist. Measurements of various steroid and peptide hormones, but most notably immunoreactive progesterone (iP), indicate an overall cycle length of 15-16 weeks, comprising an 8-11-week luteal phase and a shorter inter-luteal (follicular) period of 4-6 weeks. Oestrogen related phenomena suggest the occurrence of two (possibly more) waves of follicular development with a 3-week periodicity, although oestrogen levels are low and fluctuate without clear pattern. The inter-luteal period is characterized by two discrete LH peaks also 3 weeks apart, but only the second is associated with an iP rise. Ovulation rate is variable and additional luteal structures lacking ovulation points are probably formed each cycle. The post-ovulatory period is associated with elevated progestogen levels, mainly 5alpha-reduced compounds, while progesterone itself is a minor secretory product. A revised model for the elephant ovarian cycle is presented. Detailed information on the endocrinology of pregnancy is lacking. Elevated progestins beyond the normal luteal phase indicate that conception extends the functional lifespan of the CL, with maximum steroidogenic activity between 3-15 months. The nature of the luteotrophic support is not known and placental gonadotrophins have not been conclusively demonstrated. Progestins fluctuate at or slightly above luteal phase values throughout pregnancy. There is a marked increase in prolactin levels after 16-24 weeks and a relationship with oestrogen secretion may exist since circulating and urinary levels show a progressive increase from 6-8 months. A placental contribution to progestin secretion is likely, although direct evidence is lacking. Considerable enlargement of foetal gonads during the second half of pregnancy in African elephants suggests a possible steroidogenic function, but none has been defined. The endocrine events leading to parturition are unknown. In the Asian elephant, a fall in iP precedes parturition; oestrogen levels decline and cortisol increases at the time of birth. The paper concludes with a brief selection of priorities for future research.
The physiology of reproduction with emphasis in endocrinology of llamas and alpacas is addressed. Basic concepts of ovarian follicular dynamics, endocrine events associated with induction of ovulation, corpus luteum formation, pregnancy, parturition, postpartum interval, puberty, and sexual behavior on the female are reviewed. Pathologic conditions of the reproductive process are also reviewed.
Maximizing reproductive efficiency is of major economic importance to dairy and beef producers. The development of new and improved methods of increasing reproductive performance depends on our understanding of the physiologic and endocrinologic mechanisms controlling the reproductive process. This article reviews the mechanisms associated with puberty, estrous cycles, pregnancy, parturition, and postpartum return to estrus.
The endocrinology of late gestation and parturition in the mare has been described, but unlike other domestic animal species, the factors that initiate parturition in the mare have not been elucidated. In contrast to ruminant species, maternal estrogen and progesterone concentrations do not change markedly, and a well-defined fetal cortisol surge is not observed just prior to parturition in the mare. Parturition is associated with large increases in prostaglandin and oxytocin concentrations, which induce uterine contractions and delivery of the foal. There are many methods of inducing parturition in term mares, but the most popular and safest method is through the administration of low-dose oxytocin.
Fluid and energy metabolism and related endocrine changes have been studied nearly from the beginning of human space flight in association with short- and long-duration flights. Fluid and electrolyte nutrition status is affected by many factors including the microgravity environment, stress, changes in body composition, diet, exercise habits, sleep cycles, and ambient temperature and humidity conditions. Space flight exposes astronauts to all these factors and consequently poses significant challenges to establishing dietary water, sodium, potassium, and energy recommendations. The purpose of this article is to review the results of ground-based and space flight research studies that have led to current water, electrolyte, and energy dietary requirements for humans during space flight and to give an overview of related endocrinologic changes that have been observed in humans during short- and long-duration space flight.
The study sought to evaluate the clinical, endocrinologic, and ultrasonographic features in 150 Singaporean adolescent girls with polycystic ovary syndrome (PCOS) before and after treatment, which was composed primarily of a combined hormone therapy of estrogen and cyproterone acetate. The patients' ages ranged from 12 to 22 years with the majority between 15 and 18 years of age. Most of these girls were seen between their third and fifth gynecologic year. A considerable proportion of them had matured early, experiencing menarche between 9 and 12 years of age. Tanner staging was normal except for a greater proportion at higher stages for pubic and axillary hair, most likely a reflection of the substantial degree of androgenization commonly found in subjects with PCOS. All 150 patients presented with menstrual disorders including secondary amenorrhea, menarche only, anovulatory uterine bleeding, oligomenorrhea, and primary amenorrhea. The majority had normal body weight; 10% to 27% were either underweight or overweight, respectively. On ultrasound, patients presented with enlarged ovaries; enlargement was more pronounced in the right ovary with dense stroma and multiple subcapsular cysts. Many subjects had elevated androgen, luteinizing hormone (LH), and LH/ follicle-stimulating hormone (FSH) levels. Although characteristic of PCOS, FSH levels were either low or normal. Prolactin, estradiol, dehydroepiandrosterone sulfate (DHEAS), and androstenedione were generally normal. A substantial proportion of the study group had elevated cortisol levels. It was noted that adolescent girls with PCOS responded well to treatment; more than 60% showed improvement in cycle profiles following at least 1 year of treatment. Our current opinion is that adolescents with PCOS should be managed early, and that treatment should include medical correction of any hormonal or body-weight imbalance and include psychologic intervention when necessary.
Females of the squirrelfish family (Holocentridae) accumulate higher levels of hepatic zinc than any other studied animal. This accumulation is accompanied by high expression of the zinc-binding protein, metallothionein (MT), and is strongly correlated to the onset of sexual maturity. In an attempt to further characterize the timeframe of this accumulation, and to possibly discern any potential mediators, we examined the physiology and endocrinology of the yearly reproductive cycle of mature female squirrelfish. There are two separate reproductive events during the year in December-January and again in March-April, as evidenced by peaks in ovarian growth, VTG production, steroid levels, zinc accumulation and redistribution. Increased hepatic zinc seems to be preceded by a necessary increase in MT, but this was not clearly correlated to plasma 17beta-estradiol, testosterone, or progesterone levels. The plasma zinc protein vitellogenin (VTG) is one, but probably not the predominant, vehicle for the transport of hepatic zinc to the ovary.
Fetal blood was obtained in 35 normal pregnancies undergoing termination for psychosocial reasons between 11 and 17 weeks of gestation. Biochemical and endocrinological analyses were performed on each sample including concentrations of urea, creatinine, beta-microglobulin total protein, electrolytes, enzymes, alpha-fetoprotein (AFP), human chorionic gonadotrophin (HCG), thyroid stimulating hormone (TSH), thyroxin binding globulin (TBG), total thyroxin (TT4) and free thyroxin (FT4). The results were compared with values in maternal serum obtained at the same time. Fetal serum contained significantly higher concentrations of iron, beta-microglobulin, alkaline phosphatase (ALP), aspartate amniotransferase (AST), AFP, HCG and TSH and lower concentration of total protein, TBG and TT4 than maternal serum. Significant positive linear relationships were found between gestational age and the concentration of fetal serum total protein, ALP, TBG and FT4. Significant negative linear relationships were observed between gestational age and fetal serum beta-microglobulin and iron concentration. There were no significant correlations between fetal and maternal values. These data indicate that fetal blood biochemistry is not directly related to placental transfer and that the proteins and enzymes found inside the gestational sac are essentially of feto-placental origin with minimal contribution from the maternal protein metabolism. The comparison of coelomic fluid composition at 10-13 weeks with that of fetal serum at 11-17 weeks suggests that the anatomical changes in the human materno-fetal interface architecture between the early and late pregnancy periods could have a direct impact on materno-fetal transfer pathways.
The fathead minnow (Pimephales promelas) has been proposed as a model species for assessing the adverse effects of endocrine-disrupting chemicals (EDCs) on reproduction and development. The purpose of these studies was to develop baseline reproductive biology and endocrinology data for this species to support interpretation of tests with potential EDCs. Pairs of reproductively-active fathead minnows (n=70) were evaluated with respect to reproductive cyclicity in terms of spawning interval and fecundity. The mode and mean (+/-SE) spawning intervals for the fish in this study were 3.0 and 3.7+/-0.1 days, respectively. The mean number of eggs produced per spawn was 85+/-2.8. Animals were sacrificed at periodic intervals during the established spawning cycle and measurements made of gonadal condition (gonadosomatic index [GSI], histopathology) and plasma concentrations of vitellogenin and sex steroids (beta-estradiol, testosterone, 11-ketotestosterone). The GSI in females varied significantly as a function of spawning interval, with the largest values occurring day 2 post-spawn, just prior to the interval of maximum spawning activity. Plasma beta-estradiol concentrations in females also varied significantly relative to peak values in the GSI and spawning activity. Vitellogenin concentrations in the female, and male GSI and steroid concentrations did not vary significantly relative to position in the spawning cycle. Concentrations of beta-estradiol in females and 11-ketotestosterone in males were positively correlated with testosterone concentrations.
Deficiencies of vitamins B12, B3 and folate, abnormalities of cortisol metabolism, Wilson's disease, renal and hepatic failure, chronic obstructive pulmonary disease, hypo- and hypernatremia, thyroid and parathyroid dysfunction, hyper- and hypoglycemia and Marchiafava-Bignani disease are metabolic and endocrinological abnormalities that may be associated with cognitive impairment. In some cases these abnormalities may be causative of impaired cognition and in other situations merely associated with cognitive impairment. The existence of these conditions provides some justification for routine investigations commonly performed on patients presenting with possible early dementia.
Trenbolone acetate is a growth promoter widely used for beef production in the U.S. Two biologically active metabolites of the acetate, 17beta- and 17alpha-trenbolone, are ligands of vertebrate androgen receptors and comparatively stable in the waste of treated animals. Both have been detected in surface water associated with beef feedlots, suggesting a potential risk to aquatic animals. In previous work we evaluated the effects of beta-trenbolone on reproductive endocrinology of the fathead minnow (Pimephales promelas) in a 21-day test. The purpose of the present study was to conduct a similar set of experiments with alpha-trenbolone which, based on binding to mammalian androgen receptors, was expected to be less potent than beta-trenbolone. Fecundity of the fish was significantly reduced by alpha-trenbolone with an EC50 (95% confidence interval) of 0.011 (0.007-0.016) microg/L. In females, alpha-trenbolone reduced plasma vitellogenin and steroid concentrations and also induced the production of dorsal nuptial tubercles, structures normally present only in spawning males. Overall, effects of alpha-trenbolone on the reproductive system of the fish were qualitatively and quantitatively quite similar to those caused by beta-trenbolone. Part of this similarity might arise from the fact that a substantial amount of the alpha-trenbolone appeared to be converted to beta-trenbolone by the fish. Tissue concentrations of the beta-isomer were consistently similar to or greater than concentrations of alpha-trenbolone, despite the fact that no beta-trenbolone was detected in the exposure water. The present study demonstrates the importance of considering both alpha- and beta-trenbolone in assessing the potential ecological risk of androgens associated with beef feedlot discharges.
Substituted 8,9-diphenyl-6,7-dihydro-5H-benzocycloheptenes 6-8, which are ring-fused analogues of (Z)-trans-4-hydroxytamoxifen, (E)-cis-tamoxifen, and (E)-cis-4-hydroxytamoxifen, were synthesized from 7-methoxy-1-benzosuberone. The hydroxy compounds 6 and 8 were individually prepared via a common synthetic intermediate from which either the perfluoro-p-tolyl or the methyl ether functions could be cleaved specifically. Compounds were assayed for binding affinity to estrogen receptors in cytosol and in MCF-7 whole cells and for growth inhibition of MCF-7 cells in vitro and rat uteri in vivo. The endocrinological properties of the cyclic analogues 5-7 paralleled those of the corresponding derivatives of tamoxifen although in the MCF-7 assay 6 was slightly less effective than 4-hydroxytamoxifen at 10(-6) and 10(-7) M. The compound 8 analogues to cis-4-hydroxytamoxifen antagonized the growth stimulation by estradiol of MCF-7 cell or rat uterus growth, and it is therefore an antiestrogen, but its potency was somewhat less, both as an antiestrogen and an estrogen, than reported for cis-4-hydroxytamoxifen attributable to modification of the biochemical properties of the latter by isomerization to the more potent trans isomer. Curiously, in the absence of estradiol, compound 8 stimulated MCF-7 cell growth at low concentration (10(-8) M) but inhibited growth at higher concentration. In contrast, compound 7, which lacked the hydroxy function, was a full estrogen in the rat uterine growth assay. These compounds should be ideal for further structure-activity studies of triarylethylene-based antiestrogens without complications caused by isomerization.
This study tests the model presented previously by Breivik et al. (1996), in which the extent of periodontitis, an inflammatory disease, is predicted from the reactivity of the HPA-axis. Briefly, the model implies that elevated plasma levels of corticosterone modulate the immune system by shifting the T-helper balance toward a more Th2 response, which, alternately, increases the sensitivity to periodontitis. To test this model, two genetically distinct types of rats that differ both behaviorally and endocrinologically in their response to stress (high corticosterone responding APO-SUS rats and low corticosterone responding APO-UNSUS rats) were compared. Periodontitis was experimentally induced through the placement of a ligature and measured as the extent of tissue (fiber and bone) loss, both histologically and radiographically. The results show that, as expected, APO-SUS animals are more sensitive to periodontitis, i.e., show more fiber and bone loss, than APO-UNSUS animals. These data are in agreement with findings in Fischer and Lewis rats, as well as with corticosterone treated and adrenalectomized animals and suggest that genetic factors underlying the variation in the reactivity of the HPA-axis (and, accordingly, their behavioral response to stress) play an important a role in the development of inflammatory diseases.
Patients with insulin-dependent diabetes mellitus, autoimmune thyroid disease, Addison's disease, and alopecia areata are at increased risk of celiac disease. We investigated whether patients with more than one autoimmune endocrinologic disorder are even more susceptible to celiac disease or have celiac-type mucosal inflammation. All 62 patients found to have such multiple diseases in 1994-1996 were investigated. Small bowel biopsy was performed on all voluntary nonceliac subjects. The villous structure and density of intraepithelial lymphocytes were examined, and HLA-DQ alleles were determined. Seven (11%) patients had celiac disease: six cases were detected earlier and there was one new case; in addition, two had minor villous deterioration and five an increased density of mucosal intraepithelial gammadelta+ T-cells. HLA-DQ2 or DQ8 alleles were found in all subjects with mucosal changes. Patients with multiple autoimmune disorders clearly run an increased risk of developing celiac disease, and some of them have minor mucosal changes compatible with the early signs of the disease.
Family and personal history as well as clinical examination are the basic data to be known before laboratory examinations should be started. To obtain results that can be correctly interpreted, the blood sampling has to be done in the early morning hours between day 1 and 5 of the cycle, and for some hormones on an empty stomach. Depending on the clinical data, the hormonal screening can be selective and well directed, or it has to be broader. The presence or absence of galactorrhea, of hot flushes and of androgenization or virilization play an important role for the decision about the hormones to be determined. Furthermore, an eventual desire infertility will influence the selection of the hormonal tests to be done. The present review intends to propose some simple recommendations to the non-specialist how a gynaecological-endocrinological screening for the most important clinical questions should be organized.
Type and extent of endocrinological alterations were studied in long-term disease-free survivors after cisplatin-based chemotherapy for testicular cancer. A total of 63 patients with a median age of 30 (19-53) years, and median follow-up of 42 (16-128) months were included. Elevated serum follicle-stimulating hormone (FSH) levels were found in 63% of patients, 24% showed pathologically elevated luteinising hormone (LH) levels with normal and 10% with subnormal testosterone levels. The degree of gonadotropin elevation was highly significantly correlated with the cumulative platinum (P) dose. Patients treated with platinum-vinblastine-bleomycin regimens showed higher gonadotropin levels than those treated with platinum-etoposide-bleomycin. The adrenal androgen dehydroepiandrosterone (DHEA), pathologically elevated in 68% of patients, was significantly correlated with the cumulative doses of chemotherapy (ctx) used and to the gonadotropin levels. Treatment variables, such as type and dose of cytotoxic agents used, as well as degree of gonadotropin elevation were further correlated with changes in oestron, testosterone and 17 alpha-OH-progesterone levels. Cholesterol levels were elevated in 32% of patients and significant interactions between the steroid hormone levels and cardiovascular risk factors could be shown.