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1.
Aquat Toxicol ; 267: 106811, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38159458

RESUMO

The Amphibian Metamorphosis Assay (AMA) is used to determine if a tested chemical has potential to impact the hypothalamic-pituitary-thyroid (HPT) axis of Xenopus laevis tadpoles, while the Fish Short Term Reproduction Assay (FSTRA) assesses potential effects on the hypothalamic-pituitary-gonadal (HPG) axis of fish such as the fathead minnow (Pimephales promelas). Several global regulatory programs routinely require these internationally validated tests be performed to determine the potential endocrine activity of chemicals. As such, they are conducted in accordance with standardized protocols and test criteria, which were originally developed more than a decade ago. Sizeable numbers of AMA and FSTRA studies have since been carried out, which allows for the mining of extensive historical control data (HCD). Such data are useful for investigating the existence of outlier results and aberrant control groups, identifying potential confounding variables, providing context for rare diagnoses, discriminating target from non-target effects, and for refining current testing paradigms. The present paper provides histopathology HCD from 55 AMA studies and 45 fathead minnow FSTRA studies, so that these data may become publicly available and thus aid in the interpretation of future study outcomes. Histopathology is a key endpoint in these assays, in which it is considered to be one of the most sensitive indicators of endocrine perturbation. In the current review, granular explorations of HCD data were used to identify background lesions, to assess the utility of particular diagnostic findings for distinguishing endocrine from non-endocrine effects, and to help determine if specific improvements to established regulatory guidance may be warranted. Knowledge gleaned from this investigation, supplemented by information from other recent studies, provided further context for the interpretation of AMA and FSTRA histopathology results. We recommend HCDs for the AMA and FSTRA be maintained to support the interpretation of study results.


Assuntos
Cyprinidae , Poluentes Químicos da Água , Animais , Poluentes Químicos da Água/toxicidade , Reprodução , Sistema Endócrino , Anfíbios
2.
Cells ; 12(5)2023 02 25.
Artigo em Inglês | MEDLINE | ID: mdl-36899875

RESUMO

In starfish, the addition of the hormone 1-methyladenine (1-MA) to immature oocytes (germinal vesicle, GV-stage) arrested at the prophase of the first meiotic division induces meiosis resumption (maturation), which makes the mature eggs able to respond to the sperm with a normal fertilization response. The optimal fertilizability achieved during the maturation process results from the exquisite structural reorganization of the actin cytoskeleton in the cortex and cytoplasm induced by the maturing hormone. In this report, we have investigated the influence of acidic and alkaline seawater on the structure of the cortical F-actin network of immature oocytes of the starfish (Astropecten aranciacus) and its dynamic changes upon insemination. The results have shown that the altered seawater pH strongly affected the sperm-induced Ca2+ response and the polyspermy rate. When immature starfish oocytes were stimulated with 1-MA in acidic or alkaline seawater, the maturation process displayed a strong dependency on pH in terms of the dynamic structural changes of the cortical F-actin. The resulting alteration of the actin cytoskeleton, in turn, affected the pattern of Ca2+ signals at fertilization and sperm penetration.


Assuntos
Actinas , Estrelas-do-Mar , Animais , Masculino , Actinas/metabolismo , Sinalização do Cálcio/fisiologia , Sêmen/metabolismo , Citoesqueleto de Actina/metabolismo , Oócitos/metabolismo , Meiose , Hormônios/metabolismo , Inseminação
3.
Expert Rev Endocrinol Metab ; 17(4): 319-331, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35748612

RESUMO

INTRODUCTION: Eating disorders (EDs) are common complications in people with type 1 diabetes (PwT1D), given the rigid focus on food and insulin dose adjustment. Dietary recommendations for T1D match those for the general population, yet many fail to achieve target HbA1c. Evidence suggests that lower carbohydrate meals and thus reduced insulin requirements may decrease inconsistencies in insulin absorption, maintain euglycemia and weight. Dietary restriction is a recognized risk factor for ED development, and Ketogenic Diets (KD) involve restriction of common family-based foods, thus impacting social normality and microbiome diversity. We reviewed the current literature on PwT1D following a KD to understand effects on ED risks. AREAS COVERED: Published data from MEDLINE, Embase, and PsycINFO were used. Search terms included: type 1 diabetes mellitus; or insulin dependent diabetes or T1D AND EDs or anorexia or bulimia or disordered eating AND low-carbohydrate diet or carbohydrate restricted diet or low carb diet or ketogenic diet. EXPERT OPINION: Research into the effects of KDs on ED outcomes in PwT1D are limited, given the concerns over risks of diabetic ketoacidosis, hypoglycemia, and dyslipidemia. Longer term studies on the participants' experience and motivations of adhering or admonishing the diet are needed.


Assuntos
Diabetes Mellitus Tipo 1 , Dieta Cetogênica , Transtornos da Alimentação e da Ingestão de Alimentos , Diabetes Mellitus Tipo 1/complicações , Dieta com Restrição de Carboidratos , Dieta Cetogênica/efeitos adversos , Humanos , Insulina
4.
Environ Toxicol Chem ; 39(8): 1534-1545, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32367592

RESUMO

A study was conducted to understand the potential for ibuprofen to impact the hypothalamus-pituitary-gonadal endocrine axis resulting in disruption of fish reproduction. The Good Laboratory Practice study was conducted according to the Organisation for Economic Co-operation and Development 229 Protocol, Fish Short-Term Reproduction Assay, and extended an additional 4 d to evaluate hatching success in the F1 generation. Test organisms were exposed to nominal test concentrations of 0.5, 2.4, 11.5, 55.3, and 265.4 µg ibuprofen/L and a negative control (dilution water). To strengthen the statistical power of the study, twice the number of replicates were used in the negative control versus individual treatment levels. A 21-d pre-exposure to identify groups of actively spawning fish was immediately followed by a 36-d exposure. Results for apical endpoints of survival, growth, and reproduction (fecundity and fertility), as well as the biomarker vitellogenin in the F0 generation and time to hatch and hatching success in the F1 generation are presented. Based on mean measured exposure concentrations and effects on fecundity in the F0 generation and hatching success in the F1 generation, overall no-observed-effect concentration and lowest-observed-effect concentration for the present study were 55.2 and 265.9 µg ibuprofen/L, respectively. Results from the present study indicate a lack of endocrine-mediated reproductive effects in zebrafish at environmentally relevant concentrations of ibuprofen. Environ Toxicol Chem 2020;39:1534-1545. © 2020 SETAC.


Assuntos
Ibuprofeno/toxicidade , Organização para a Cooperação e Desenvolvimento Econômico , Reprodução/efeitos dos fármacos , Peixe-Zebra/fisiologia , Animais , Feminino , Fertilidade/efeitos dos fármacos , Masculino , Óvulo/efeitos dos fármacos , Análise de Sobrevida , Vitelogeninas/metabolismo , Poluentes Químicos da Água/toxicidade , Peixe-Zebra/crescimento & desenvolvimento
5.
PeerJ ; 7: e6886, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31106075

RESUMO

A genotypic sex determination assay provides accurate gender information of individuals with well-developed phenotypic characters as well as those with poorly developed or absent of phenotypic characters. Determination of genetic sex for Xenopus laevis can be used to validate the outcomes of Tier 2 amphibian assays, and is a requirement for conducting the larval amphibian growth and development assay (LAGDA), in the endocrine disruptor screening program (EDSP), test guidelines. The assay we developed uses a dual-labeled TaqMan probe-based real-time polymerase chain reaction (real-time PCR) method to determine the genotypic sex. The reliability of the assay was tested on 37 adult specimens of X. laevis collected from in-house cultures in Eurofins EAG Agroscience, Easton. The newly designed X. laevis-specific primer pair and probe targets the DM domain gene linked-chromosome W as a master female-determining gene. Accuracy of the molecular method was assessed by comparing with phenotypic sex, determined by necropsy and histological examination of gonads for all examined specimens. Genotypic sex assignments were strongly concordant with observed phenotypic sex, confirming that the 19 specimens were male and 18 were female. The results indicate that the TaqMan® assay could be practically used to determine the genetic sex of animals with poorly developed or no phenotypic sex characteristics with 100% precision. Therefore, the TaqMan® assay is confirmed as an efficient and feasible method, providing a diagnostic molecular sex determination approach to be used in the amphibian endocrine disrupting screening programs conducted by regulatory industries. The strength of an EDSP is dependent on a reliable method to determine genetic sex in order to identify reversals of phenotypic sex in animals exposed to endocrine active compounds.

6.
Environ Toxicol Chem ; 38(7): 1549-1559, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-30900773

RESUMO

Chlorothalonil is a fungicide which is highly toxic to aquatic organisms. However, in natural aquatic environments, it is very rapidly degraded, with a half-life typically in hours, reducing exposure of aquatic organisms and the potential for effects. In standard regulatory studies looking at the chronic toxicity of chlorothalonil to fathead minnow, the most sensitive endpoint was fecundity. A standard fish full-life cycle study, where chlorothalonil concentrations were maintained constant throughout, resulted in a no-observed-effect concentration (NOEC) of 1.4 µg/L. Comparing peak modeled exposure concentrations to this NOEC can result in the chronic risk to fish being considered unacceptable. The present study investigated the effect on fecundity in fathead minnow using a fish short-term reproduction assay. Five different exposure profiles were employed with time-varying concentrations based on realistic worst-case modeled environmental exposure profiles, multiplied by an assessment factor of 10, which resulted in maximum measured concentrations up to 15.5 µg/L. There were no effects on fecundity from any of the exposure profiles tested. Therefore, based on these more realistic exposure profiles, the chronic risk to fish could be considered acceptable if these exposures were deemed to be representative of the worst case. Environ Toxicol Chem 2019;38:1549-1559. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.


Assuntos
Cyprinidae/crescimento & desenvolvimento , Fungicidas Industriais/toxicidade , Nitrilas/toxicidade , Reprodução/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Animais , Cyprinidae/fisiologia , Feminino , Fungicidas Industriais/química , Concentração de Íons de Hidrogênio , Nitrilas/química , Óvulo/efeitos dos fármacos , Óvulo/crescimento & desenvolvimento , Óvulo/metabolismo , Medição de Risco , Temperatura , Poluentes Químicos da Água/química
7.
Chemosphere ; 205: 126-136, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29689526

RESUMO

Short-term reproduction assays were conducted with fathead minnow (Pimephales promelas) and Japanese medaka (Oryzias latipes) to evaluate responses from atrazine exposure at environmentally relevant concentrations and above. Breeding groups of fish with multiple males and females were exposed to atrazine under flow-through conditions. Fathead minnows were exposed to mean measured concentrations of 1.0, 10, 26, 52, and 105 µg atrazine/L for 28 days. Medaka were exposed to mean measured concentrations of 9.4, 48, 74, 97, and 244 µg atrazine/L for 28 or 29 days. Fish were evaluated for survival, fecundity, fertility, total length, wet weight, secondary sex characteristics, gonadosomatic index (GSI) (P. promelas only), plasma or hepatic vitellogenin (VTG), and histopathology of gonads. General observations of health and behaviour were also conducted. There were no statistically significant effects (i.e., p < 0.05) of atrazine on survival, size, reproduction, behaviour, GSI, VTG, or secondary sex characteristics in either species at any exposure level. In fathead minnows, there were no histopathological findings associated with atrazine exposure in male fish, but there was an increased proportion of Stage 4.0 ovaries accompanied by an increase in proportion of Grade 3 post-ovulatory follicles in females of the 105 µg/L treatment group. Without a concomitant increase in oocyte atresia, neither of these findings are considered adverse for the health of the fish. In medaka, there were no significant effects of atrazine exposure on histopathology in either sex. These data support current weight-of-evidence assessments that atrazine does not cause direct adverse effects on fish reproduction at environmentally realistic concentrations.


Assuntos
Atrazina/farmacologia , Fertilidade/efeitos dos fármacos , Gônadas/fisiologia , Oryzias/fisiologia , Ovário/fisiologia , Reprodução/efeitos dos fármacos , Poluentes Químicos da Água/farmacologia , Animais , Feminino , Gônadas/efeitos dos fármacos , Herbicidas/farmacologia , Masculino , Ovário/efeitos dos fármacos , Fatores Sexuais
8.
Physiol Rep ; 5(3)2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-28174343

RESUMO

Heat stress has been reported to reduce uncoupling proteins (UCP) expression, which in turn should improve mitochondrial efficiency. Such an improvement in efficiency may translate to the systemic level as greater exercise economy. However, neither the heat-induced improvement in mitochondrial efficiency (due to decrease in UCP), nor its potential to improve economy has been studied. Determine: (i) if heat stress in vitro lowers UCP3 thereby improving mitochondrial efficiency in C2C12 myocytes; (ii) whether heat acclimation (HA) in vivo improves exercise economy in trained individuals; and (iii) the potential improved economy during exercise at altitude. In vitro, myocytes were heat stressed for 24 h (40°C), followed by measurements of UCP3, mitochondrial uncoupling, and efficiency. In vivo, eight trained males completed: (i) pre-HA testing; (ii) 10 days of HA (40°C, 20% RH); and (iii) post-HA testing. Pre- and posttesting consisted of maximal exercise test and submaximal exercise at two intensities to assess exercise economy at 1600 m (Albuquerque, NM) and 4350 m. Heat-stressed myocytes displayed significantly reduced UCP3 mRNA expression and, mitochondrial uncoupling (77.1 ± 1.2%, P < 0.0001) and improved mitochondrial efficiency (62.9 ± 4.1%, P < 0.0001) compared to control. In humans, at both 1600 m and 4350 m, following HA, submaximal exercise economy did not change at low and moderate exercise intensities. Our findings indicate that while heat-induced reduction in UCP3 improves mitochondrial efficiency in vitro, this is not translated to in vivo improvement of exercise economy at 1600 m or 4350 m.


Assuntos
Exercício Físico , Resposta ao Choque Térmico , Mitocôndrias/metabolismo , Células Musculares/metabolismo , Proteína Desacopladora 3/metabolismo , Aclimatação , Adulto , Altitude , Animais , Linhagem Celular , Humanos , Masculino , Camundongos , Consumo de Oxigênio
9.
Environ Toxicol Chem ; 36(9): 2327-2334, 2017 09.
Artigo em Inglês | MEDLINE | ID: mdl-28198566

RESUMO

Breeding groups of Japanese medaka (Oryzias latipes) were exposed to atrazine at measured concentrations of 0.6, 5.5, and 53 µg/L for 35 d. Evaluated endpoints included survival, fecundity, fertility, growth (weight and length), behavior, secondary sex characteristics (anal fin papillae), gonad histopathology, and hepatic vitellogenin. No statistically significant effects of atrazine exposure on survival and growth of medaka were noted during the test, and mean survival was ≥97.5% in all treatment groups on day 35. No significant effects of atrazine exposure on reproduction were observed. The number of mean cumulative eggs produced in the negative control and the 0.6, 5.5, and 53 µg/L treatment groups was 7158, 6691, 6883, and 6856, respectively. The mean number of eggs per female reproductive day was 40.9, 38.2, 40.2, and 39.2, respectively. There were also no dose-dependent effects on mean anal fin papillae counts among male fish or expression of vtg-II in males or females. In addition, atrazine exposure was not related to the developmental stage of test fish, with testes stages ranging from 2 to 3 in all groups and ovaries ranging from stage 2 to 2.5. Overall, exposure to atrazine up to 53 µg/L for 35 d did not result in significant, treatment-related effects on measured endpoints related to survival, growth, or reproduction in Japanese medaka. Environ Toxicol Chem 2017;36:2327-2334. © 2017 SETAC.


Assuntos
Atrazina/toxicidade , Herbicidas/toxicidade , Oryzias/fisiologia , Poluentes Químicos da Água/toxicidade , Animais , Feminino , Fertilidade/efeitos dos fármacos , Fígado/metabolismo , Masculino , Ovário/efeitos dos fármacos , Ovário/fisiologia , Reprodução/efeitos dos fármacos , Caracteres Sexuais , Testículo/efeitos dos fármacos , Testículo/fisiologia , Vitelogeninas/metabolismo
10.
Physiol Rep ; 4(15)2016 08.
Artigo em Inglês | MEDLINE | ID: mdl-27495299

RESUMO

Leg muscle mass and strength are decreased during reduced activity and non-weight-bearing conditions such as bed rest (BR) and spaceflight. Supine treadmill exercise within lower body negative pressure (LBNPEX) provides full-body weight loading during BR and may prevent muscle deconditioning. We hypothesized that a 40-min interval exercise protocol performed against LBNPEX 6 days week(-1) would attenuate losses in leg lean mass (LLM), strength, and endurance during 6° head-down tilt BR, with similar benefits for men and women. Fifteen pairs of healthy monozygous twins (8 male and 7 female pairs) completed 30 days of BR with one sibling of each twin pair assigned randomly as the non-exercise control (CON) and the other twin as the exercise subject (EX). Before and after BR, LLM and isokinetic leg strength and endurance were measured. Mean knee and ankle extensor and flexor strength and endurance and LLM decreased from pre- to post-BR in the male CON subjects (P < 0.01), but knee extensor strength and endurance, ankle extensor strength, and LLM were maintained in the male EX subjects. In contrast, no pre- to post-BR changes were significant in the female subjects, either CON or EX, likely due to their lower pre-BR values. Importantly, the LBNPEX countermeasure prevents or attenuates declines in LLM as well as extensor leg strength and endurance. Individuals who are stronger, have higher levels of muscular endurance, and/or have greater LLM are likely to experience greater losses during BR than those who are less fit.


Assuntos
Repouso em Cama/efeitos adversos , Terapia por Exercício/métodos , Perna (Membro)/fisiologia , Pressão Negativa da Região Corporal Inferior , Força Muscular , Resistência Física , Adulto , Teste de Esforço , Feminino , Humanos , Contração Isométrica , Masculino , Voo Espacial , Adulto Jovem
11.
Temperature (Austin) ; 3(1): 176-85, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27227084

RESUMO

To examine the effect ("cross-tolerance") of heat acclimation (HA) on exercise performance upon exposure to acute hypobaric hypoxia (4350 m). Eight male cyclists residing at 1600 m performed tests of maximal aerobic capacity (VO2max) at 1600 m and 4350 m, a 16 km time-trial at 4350 m, and a heat tolerance test at 1600 m before and after 10 d HA at 40°C, 20% RH. Resting blood samples were obtained pre-and post- HA to estimate changes in plasma volume (ΔPV). Successful HA was indicated by significantly lower exercise heart rate and rectal temperature on day 10 vs. day 1 of HA and during the heat tolerance tests. Heat acclimation caused a 1.9% ΔPV, however VO2max was not significantly different at 1600 m or 4350 m. Time-trial cycling performance improved 28 sec after HA (p = 0.07), suggesting a possible benefit for exercise performance at acute altitude and that cross-tolerance between these variables may exist in humans. These findings do not clearly support the use of HA to improve exercise capacity and performance upon acute hypobaric hypoxia, however they do indicate that HA is not detrimental to either exercise capacity or performance.

12.
Temperature (Austin) ; 3(1): 28-30, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27227090
13.
Cell Biochem Funct ; 34(4): 209-16, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27027694

RESUMO

UNLABELLED: Obesity is a low-grade chronic inflammation condition, and macrophages, and possibly monocytes, are involved in the pathological outcomes of obesity. Physical exercise is a low-cost strategy to prevent and treat obesity, probably because of its anti-inflammatory action. We evaluated the percentage of CD16(-) and CD16(+) monocyte subsets in obese insulin-resistant individuals and the effect of an exercise bout on the percentage of these cells. Twenty-seven volunteers were divided into three experimental groups: lean insulin sensitive, obese insulin sensitive and obese insulin resistant. Venous blood samples collected before and 1 h after an aerobic exercise session on a cycle ergometer were used for determination of monocyte subsets by flow cytometry. Insulin-resistant obese individuals have a higher percentage of CD16(+) monocytes (14.8 ± 2.4%) than the lean group (10.0 ± 1.3%). A positive correlation of the percentage of CD16(+) monocytes with body mass index and fasting plasma insulin levels was found. One bout of moderate exercise reduced the percentage of CD16(+) monocytes by 10% in all the groups evaluated. Also, the absolute monocyte count, as well as all other leukocyte populations, in lean and obese individuals, increased after exercise. This fact may partially account for the observed reduction in the percentage of CD16(+) cells in response to exercise. Insulin-resistant, but not insulin-sensitive obese individuals, have an increased percentage of CD16(+) monocytes that can be slightly modulated by a single bout of moderate aerobic exercise. These findings may be clinically relevant to the population studied, considering the involvement of CD16(+) monocytes in the pathophysiology of obesity. Copyright © 2016 John Wiley & Sons, Ltd. SIGNIFICANCE OF THE STUDY: Obesity is now considered to be an inflammatory condition associated with many pathological consequences, including insulin resistance. It is proposed that insulin resistance contributes to the aggravation of the inflammatory dysfunction in obesity. The effect of obesity on the percentage of monocytes was previously observed in class II and III obese individuals who presented other alterations in addition to insulin resistance. In this study we observed that insulin-resistant obese individuals, but not insulin-sensitive ones, had an increased percentage of CD14(+) CD16(+) monocytes. This fact shows that a dysfunction of the monocyte percentage in class I obese individuals is only seen when this condition is associated with insulin resistance.


Assuntos
Exercício Físico , Resistência à Insulina , Monócitos/patologia , Obesidade/patologia , Obesidade/fisiopatologia , Receptores de IgG/metabolismo , Adolescente , Adulto , Contagem de Células Sanguíneas , Demografia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem
14.
J Appl Physiol (1985) ; 120(10): 1215-22, 2016 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-26893030

RESUMO

Microgravity-induced lumbar paraspinal muscle deconditioning may contribute to back pain commonly experienced by astronauts and may increase the risk of postflight injury. We hypothesized that a combined resistive and aerobic exercise countermeasure protocol that included spinal loading would mitigate lumbar paraspinal muscle deconditioning during 60 days of bed rest in women. Sixteen women underwent 60-day, 6° head-down-tilt bed rest (BR) and were randomized into control and exercise groups. During bed rest the control group performed no exercise. The exercise group performed supine treadmill exercise within lower body negative pressure (LBNP) for 3-4 days/wk and flywheel resistive exercise for 2-3 days/wk. Paraspinal muscle cross-sectional area (CSA) was measured using a lumbar spine MRI sequence before and after BR. In addition, isokinetic spinal flexion and extension strengths were measured before and after BR. Data are presented as means ± SD. Total lumbar paraspinal muscle CSA decreased significantly more in controls (10.9 ± 3.4%) than in exercisers (4.3 ± 3.4%; P < 0.05). The erector spinae was the primary contributor (76%) to total lumbar paraspinal muscle loss. Moreover, exercise attenuated isokinetic spinal extension loss (-4.3 ± 4.5%), compared with controls (-16.6 ± 11.2%; P < 0.05). In conclusion, LBNP treadmill and flywheel resistive exercises during simulated microgravity mitigate decrements in lumbar paraspinal muscle structure and spine function. Therefore spaceflight exercise countermeasures that attempt to reproduce spinal loads experienced on Earth may mitigate spinal deconditioning during long-duration space travel.


Assuntos
Repouso em Cama/efeitos adversos , Exercício Físico/fisiologia , Músculos Paraespinais/fisiologia , Ausência de Peso/efeitos adversos , Astronautas , Teste de Esforço/métodos , Feminino , Decúbito Inclinado com Rebaixamento da Cabeça/fisiologia , Humanos , Pressão Negativa da Região Corporal Inferior/métodos , Vértebras Lombares/fisiologia , Região Lombossacral/fisiologia , Treinamento Resistido/métodos , Voo Espacial/métodos , Contramedidas de Ausência de Peso , Simulação de Ausência de Peso/métodos
15.
Temperature (Austin) ; 3(4): 527-538, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-28090556

RESUMO

The underground gold mines of South Africa offer a unique historical setting to study heat acclimation. The early heat stress research was conducted and described by a young medical officer, Dr. Aldo Dreosti. He developed practical and specific protocols to first assess the heat tolerance of thousands of new mining recruits, and then used the screening results as the basis for assigning a heat acclimation protocol. The mines provide an interesting paradigm where the prevention of heat stroke evolved from genetic selection, where only Black natives were recruited due to a false assumption of their intrinsic tolerance to heat, to our current appreciation of the epigenetic and other molecular adaptations that occur with exposure to heat.

16.
Clin Ophthalmol ; 9: 1931-43, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26604666

RESUMO

INTRODUCTION: Adherence to glaucoma medications is essential for successful treatment of the disease but is complex and difficult for many of our patients. Health coaching has been used successfully in the treatment of other chronic diseases. This pilot study explores the use of health coaching for glaucoma care. METHODS: A mixed methods study design was used to assess the health coaching intervention for glaucoma patients. The health coaching intervention consisted of four to six health coaching sessions with a certified health coach via telephone. Quantitative measures included demographic and health information, adherence to glaucoma medications (using the visual analog adherence scale and medication event monitoring system), and an exit survey rating the experience. Qualitative measures included a precoaching health questionnaire, notes made by the coach during the intervention, and an exit interview with the subjects at the end of the study. RESULTS: Four glaucoma patients participated in the study; all derived benefits from the health coaching. Study subjects demonstrated increased glaucoma drop adherence in response to the coaching intervention, in both visual analog scale and medication event monitoring system. Study subjects' qualitative feedback reflected a perceived improvement in both eye and general health self-care. The subjects stated that they would recommend health coaching to friends or family members. CONCLUSION: Health coaching was helpful to the glaucoma patients in this study; it has the potential to improve glaucoma care and overall health.

17.
Eur J Appl Physiol ; 115(9): 1877-86, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25893562

RESUMO

PURPOSE: This study investigated the effect of creatine (CR) supplementation during cast-immobilization to preserve skeletal muscle total work, power and intramuscular phosphocreatine (PCr) kinetics during dynamic exercise. METHODS: Twenty-five active individuals (24 ± 4 years,) performed wrist flexion exercise within a 1.9 Tesla superconducting magnet before and after 1 week of cast-immobilization. An incremental protocol to fatigue and two constant load (CL1 and CL2) exercise bouts were performed. While casted, participants consumed either 20 g day(-1) of CR or a placebo (PLA). (31)P magnetic resonance spectroscopy was used to quantify in vivo intramuscular PCr levels. RESULTS: No significant group × time interaction effects were found for work or power throughout all exercise bouts. Total work was significantly reduced over time in both groups (p = 0.049) during the incremental exercise bout. Work production in CL1 tended (p = 0.073) to attenuate in the CR group, compared to PLA. No changes were observed in CL2. Baseline PCr significantly decreased with casting in PLA (PRE: 26.6 ± 6.3 vs. POST: 22.5 ± 5.6 mM kg(-1) wet muscle, p = 0.003). No change (p = 0.31) was observed in the CR group. Changes in work production were significantly correlated with changes in resting PCr in CR (r = -0.63, p = 0.021) but not PLA (r = -0.36, p = 0.26) group. CONCLUSIONS: Results suggest decreases in short-term endurance may be due to alternations of PCr status and/or metabolism. More research is needed to fully determine the efficacy of CR supplementation during short-term immobilization.


Assuntos
Creatina/administração & dosagem , Suplementos Nutricionais , Imobilização , Contração Muscular/fisiologia , Músculo Esquelético/fisiologia , Fosfocreatina/metabolismo , Feminino , Humanos , Masculino , Contração Muscular/efeitos dos fármacos , Força Muscular/efeitos dos fármacos , Força Muscular/fisiologia , Músculo Esquelético/efeitos dos fármacos , Resistência Física/efeitos dos fármacos , Resistência Física/fisiologia , Adulto Jovem
18.
Cell Stress Chaperones ; 20(1): 85-93, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25062931

RESUMO

Chronic glutamine supplementation reduces exercise-induced intestinal permeability and inhibits the NF-κB pro-inflammatory pathway in human peripheral blood mononuclear cells. These effects were correlated with activation of HSP70. The purpose of this paper is to test if an acute dose of oral glutamine prior to exercise reduces intestinal permeability along with activation of the heat shock response leading to inhibition of pro-inflammatory markers. Physically active subjects (N = 7) completed baseline and exercise intestinal permeability tests, determined by the percent ratio of urinary lactulose (5 g) to rhamnose (2 g). Exercise included two 60-min treadmill runs at 70 % of VO2max at 30 °C after ingestion of glutamine (Gln) or placebo (Pla). Plasma levels of endotoxin and TNF-α, along with peripheral blood mononuclear cell (PBMC) protein expression of HSP70 and IκBα, were measured pre- and post-exercise and 2 and 4 h post-exercise. Permeability increased in the Pla trial compared to that at rest (0.06 ± 0.01 vs. 0.02 ± 0.018) and did not increase in the Gln trial. Plasma endotoxin was lower at the 4-h time point in the Gln vs. 4 h in the Pla (6.715 ± 0.046 pg/ml vs. 7.952 ± 1.11 pg/ml). TNF-α was lower 4 h post-exercise in the Gln vs. Pla (1.64 ± 0.09 pg/ml vs. 1.87 ± 0.12 pg/ml). PBMC expression of IkBα was higher 4 h post-exercise in the Gln vs. 4 h in the Pla (1.29 ± 0.43 vs. 0.8892 ± 0.040). HSP70 was higher pre-exercise and 2 h post-exercise in the Gln vs. Pla (1.35 ± 0.21 vs. 1.000 ± 0.000 and 1.65 ± 0.21 vs. 1.27 ± 0.40). Acute oral glutamine supplementation prevents an exercise-induced rise in intestinal permeability and suppresses NF-κB activation in peripheral blood mononuclear cells.


Assuntos
Exercício Físico , Trato Gastrointestinal/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , Glutamina/farmacologia , Proteínas de Choque Térmico HSP70/genética , Leucócitos Mononucleares/efeitos dos fármacos , Administração Oral , Adolescente , Adulto , Suplementos Nutricionais , Método Duplo-Cego , Feminino , Trato Gastrointestinal/metabolismo , Glutamina/sangue , Proteínas de Choque Térmico HSP70/metabolismo , Humanos , Proteínas I-kappa B/metabolismo , Leucócitos Mononucleares/metabolismo , Masculino , Inibidor de NF-kappaB alfa , Permeabilidade/efeitos dos fármacos , Fator de Necrose Tumoral alfa/sangue , Adulto Jovem
19.
J Strength Cond Res ; 29(8): 2261-9, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23722108

RESUMO

We previously reported that cold application to the palms between sets of high-intensity bench press exercise produces an ergogenic effect in men. In this study, we hypothesized that palm cooling (PC) or heating during rest intervals between high-intensity weight training sets will increase total repetitions and exercise volume load (kilograms) in resistance trained female subjects in a thermoneutral (TN) environment. Eight female subjects (mean ± SD, age = 25 ± 6 years, height = 160 ± 6 cm, body mass = 56 ± 7 kg, 1-repetition maximum [1RM] = 52 ± 6 kg, weight training experience = 6 ± 2 years) completed 4 sets of 85% 1RM bench press exercise to failure, with 3-minute rest intervals. Exercise trials were performed in a counterbalanced order on 3 days, separated by at least 3 days in TN, Palm heating (PH), and PC conditions. Heating and cooling were applied by placing both hands in a hand cooling device with the hand plate set to 45° C for heating and 10° C for cooling. Data were analyzed using a 2-factor repeated-measures analysis of variance and Tukey's post hoc tests. Palm cooling repetitions were significantly higher than TN repetitions during the second set, and PH repetitions were significantly higher than those of TN during the fourth set. Total exercise volume load (kilograms) for both PC (1,387 ± 358) and PH (1,349 ± 267) were significantly higher than TN (1,187 ± 262). In women, both heating and cooling of the palms between sets of resistance exercise increased the total exercise volume load performed. This ergogenic response to a peripheral sensory input is consistent with the central governor theory of muscular fatigue.


Assuntos
Crioterapia , Mãos/fisiologia , Hipertermia Induzida , Fadiga Muscular/fisiologia , Levantamento de Peso/fisiologia , Adulto , Feminino , Humanos , Treinamento Resistido , Descanso , Adulto Jovem
20.
Explore (NY) ; 10(6): 372-9, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25240635

RESUMO

CONTEXT: Physicians in the United States increasingly confront stress, burnout, and other serious symptoms at an alarming level. As a result, there is growing public interest in the development of interventions that improve physician resiliency. OBJECTIVE: The aim of this study is to evaluate the perceived impact of Physician Well-being Coaching on physician stress and resiliency, as implemented in a major medical center. STUDY DESIGN: Semi-structured interviews were conducted with 11 physician-participants, and three coaches of a Physician Well-being Coaching pilot focused on three main areas: life context, impacts of coaching, and coaching process. PARTICIPANTS: Interviewees were physicians who completed between three and eight individual coaching sessions between October 2012 and May 2013 through the Physician Well-being Coaching pilot program. ANALYSIS: Qualitative content analysis of the 11 physician interviews and three coach interviews using Atlas.ti to generate patterns and themes. RESULTS: Physician Well-being Coaching helped participants increase resilience via skill and awareness development in the following three main areas: (1) boundary setting and prioritization, (2) self-compassion and self-care, and (3) self-awareness. These insights often led to behavior changes and were perceived by physicians to have indirect but positive impact on patient care. CONCLUSIONS: Devaluing self-care while prioritizing the care of others may be a significant, but unnecessary, source of burnout for physicians. This study suggests that coaching can potentially help physicians alter this pattern through skill development and increased self-awareness. It also suggests that by strengthening physician self-care, coaching can help to positively impact patient care.


Assuntos
Esgotamento Profissional/prevenção & controle , Médicos/psicologia , Resiliência Psicológica , Autocuidado , Estresse Psicológico/prevenção & controle , Atitude do Pessoal de Saúde , Conscientização , Empatia , Saúde , Humanos , Entrevistas como Assunto , Satisfação Pessoal , Projetos Piloto , Avaliação de Programas e Projetos de Saúde , Pesquisa Qualitativa , Estados Unidos
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