576,116 research outputs found

    The behavior of renal-regulating hormones during hypogravic stress

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    The regulation of fluid and electrolyte behavior during space flight is believed to be under control, in large part, of a group of hormones which have their major effects on renal excretion. The hormones studied include renin-angitensin, aldosterone, and antidiuretic hormone (ADH). The regulatory systems of these renal-regulating hormones as they act individually and in concert with each other are analyzed. The analysis is based on simulations of the mathematical model of Guyton. A generalized theory is described which accounts for both short-term and long-term behavior of this set of hormones

    secCl is a cys-loop ion channel necessary for the chloride conductance that mediates hormone-induced fluid secretion in Drosophila

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    Organisms use circulating diuretic hormones to control water balance (osmolarity), thereby avoiding dehydration and managing excretion of waste products. The hormones act through G-protein-coupled receptors to activate second messenger systems that in turn control the permeability of secretory epithelia to ions like chloride. In insects, the chloride channel mediating the effects of diuretic hormones was unknown. Surprisingly, we find a pentameric, cys-loop chloride channel, a type of channel normally associated with neurotransmission, mediating hormone-induced transepithelial chloride conductance. This discovery is important because: 1) it describes an unexpected role for pentameric receptors in the membrane permeability of secretory epithelial cells, and 2) it suggests that neurotransmitter-gated ion channels may have evolved from channels involved in secretion

    Hormone-treated beef: Should Britain accept it after Brexit?

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    This Briefing explains why the use of synthetic, industrially-manufactured hormones in beef production, and the threat of importing hormone-produced beef after Brexit, matter for UK consumers. There is robust scientific evidence showing that meat produced using one key hormone (17β-oestradiol) increases the cancer risk to consumers, while for the rest the available evidence is insufficient to show that their use is acceptably safe. The Briefing outlines the basis of the scientific and policy disputes over the use of supplementary hormones in beef cattle production. It shows that, although the USA is most associated with hormone-reared beef, other countries that want to export their beef to the UK, post Brexit, either allow hormones to be used, or are suspected of doing so. The EU has been reasonably vigilant on consumers’ behalf on this issue, and it has robust scientific grounds for its ban on their use. The risk from beef hormones is one of many issues on which UK consumers have benefited from the EU’s measures to protect public and environmental health. Chlorine-washed chicken is another example

    Interpreting Neuroendocrine Hormones, Corticosterone, and Blood Glucose to Assess the Wellbeing of Anesthetized Rats during Euthanasia

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    Current recommendations for assessing animal wellbeing during euthanasia suggest that measuring neuroendocrine hormones-such as ACTH, noradrenaline, and adrenaline-is preferable to measuring corticosterone and blood glucose because of the sensitivity of neuroendocrine hormones to the acute stress associated with rapid methods of euthanasia. However, theseneuroendocrine hormones can be stimulated in ways that confound interpretation of welfare assessment in euthanasia studies.Although this property does not negate the usefulness of neuroendocrine hormones as tools of assessment, it is importantto differentiate the stress associated with the induction of anesthesia before the loss of consciousness (an animal wellbeingconcern) with the physiologic responses that occur after the loss of consciousness (not an animal wellbeing concern). In thisstudy, rats were anesthetized by using a ketamine-xylazine combination. Once the rats achieved a surgical plane of anesthesia,they were exposed to O2, CO2, or isoflurane, followed by terminal blood collection to assess concentrations of ACTH,noradrenaline, corticosterone, and blood glucose. Compared with animals exposed to O2 or isoflurane, rats exposed to CO2had significant increases in their serum concentrations of ACTH and noradrenaline, but blood glucose and corticosteronedid not differ between groups. These findings indicate that noradrenaline and ACTH should be used with caution to assessanimal wellbeing when the method of euthanasia might confound that assessment

    The hormones of invertebrates

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    Thesis (M.A.)--Boston University, 193

    Sex hormones in allergic conjunctivitis: altered levels of circulating androgens and estrogens in children and adolescents with vernal keratoconjunctivitis

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    PURPOSE: Vernal keratoconjunctivitis (VKC) is a chronic allergic disease mainly affecting boys in prepubertal age and usually recovering after puberty. To evaluate a possible role of sex hormones in VKC, serum levels of sex hormones in children and adolescents with VKC were assessed. METHODS: 12 prepubertal and 7 early pubertal boys with active VKC and 6 male patients with VKC in remission phase at late pubertal age and 48 healthy age and sex-matched subjects were included. Serum concentration of estrone, 17 beta-estradiol, dehydroepiandrosterone-sulfate, total testosterone and free testosterone, dihydrotestosterone (DHT), cortisol, delta-4-androstenedione, follicle-stimulating hormone, luteinizing hormone, and sex-hormones binding globuline (SHBG) were evaluated. RESULTS: Serum levels of Estrone were significantly increased in all groups of patients with VKC when compared to healthy controls (P < 0.001). Prepubertal and early pubertal VKC showed a significant decrease in DHT (P = 0.007 and P = 0.028, resp.) and SHBG (P = 0.01 and P = 0.002, resp.) when compared to controls and serum levels of SHBG were increased in late pubertal VKC in remission phase (P = 0.007). CONCLUSIONS AND RELEVANCE: VKC patients have different circulating sex hormone levels in different phases of the disease and when compared to nonallergic subjects. These findings suggest a role played by sex hormones in the pathogenesis and/or activity of VKC

    CONSUMER DEMAND FOR MANDATORY LABELING OF BEEF FROM CATTLE ADMINISTERED GROWTH HORMONES OR FED GENETICALLY MODIFIED CORN

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    This study estimates the value of policies that would mandate labeling of beef from cattle produced with growth hormones or fed genetically modified corn. At no cost, 85 percent of resondents desired mandatory labeling of beef produced with growth hormones and 64 percent of respondents preferred mandatory labeling of beef fed genetically modified corn. Estimates suggest that consumers would be willing to pay 17.0 percent and 10.6 percent higher prices for beef on average to obtain information provided via mandatory labeling about whether the beef is from cattle produced with growth hormones or fed genetically modified corn, respectively.beef, contingent valuation, genetically modified foods, growth hormones, mandatory labeling, Demand and Price Analysis, Research and Development/Tech Change/Emerging Technologies,

    A case-control study of drug risk factors for age-related macular degeneration.

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    OBJECTIVE: To investigate the association between age-related macular degeneration (AMD) and exposure to antacids, antithyroids, thyroid hormones, and thiazide diuretics. DESIGN: Matched case-control study. PARTICIPANTS: Population-based participants were selected from the United Kingdom General Practice Research Database. A total of 18,007 people with diagnosed AMD were compared with 86 169 controls matched for age, gender, and general practice. METHODS: Conditional logistic regression was used to determine the association between exposure to each drug group of interest and a diagnosis of AMD, adjusting for relevant confounding variables. MAIN OUTCOME MEASURES: The primary outcome was the odds ratio for the association between exposure to antacids, antithyroids, thyroid hormones, or thiazide diuretics and AMD. Secondary analyses were conducted to assess the effect of recent exposure to the drugs of interest, the total number of prescriptions received, and restricting the data set to participants with more than 2 years of observation time. RESULTS: The crude odds ratios for association between any record of drug exposure and AMD were as follows: 1.34 (95% confidence interval [CI], 1.29-1.39) for antacids; 1.15 (95% CI, 0.92-1.44) for antithyroids; 1.34 (95% CI, 1.29-1.39) for thyroid hormones; and 1.13 (95% CI, 1.08-1.17) for thiazide diuretics. After adjusting for consultation rate, observation time, diabetes, heart failure, hyperlipidemia, cardiovascular drug use, atherosclerosis, hypertension, aspirin use, hormone replacement therapy use, body mass index, alcohol consumption, and smoking, the odds ratios reduced to: 1.06 (95% CI, 1.02-1.10) for antacids, 0.98 (95% CI, 0.78-1.24) for antithyroids, 0.99 (95% CI, 0.92-1.06) for thyroid hormones, and 0.98 (95% CI, 0.94-1.02) for thiazides. Secondary analyses were consistent with these findings for all 4 drug categories. CONCLUSIONS: No association was detected between short- and medium-term use of antithyroids, thyroid hormones, and thiazide diuretics and the risk of AMD. Short- and medium-term use of antacids seems to be associated with a small increase in the risk of this disease. However, this increased risk is likely the result of residual confounding by smoking or uncontrolled confounding resulting from socioeconomic status. No conclusions could be drawn regarding longer-term use of each drug category

    DEMAND FOR BEEF FROM CATTLE ADMINISTERED GROWTH HORMONES OR FED GENETICALLY MODIFIED CORN: A COMPARISON OF CONSUMERS IN FRANCE, GERMANY, THE UNITED KINGDOM, AND THE UNITED STATES

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    This study compares consumer valuations of beef steaks from cattle produced without growth hormones or genetically modified corn in France, Germany, the United Kingdom, and the United States. In general, European consumers place a higher value on beef from cattle that have not been administered growth hormones and/or fed genetically modified corn than United States consumers. There is a larger divergence between the two cultures with regard to the issue of biotechnology and genetic engineering than with the issue of growth hormones. Results suggest that liberalizing trade policy for hormone-treated beef may be welfare reducing for the European Union.Consumer/Household Economics, Demand and Price Analysis, Research and Development/Tech Change/Emerging Technologies,
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