RESUMEN
The rhythmic variations of body temperature in two groups of mice located in Moscow and Novosibirsk were compared with geomagnetic undulations within Pc5/Pi3 (1-5 mHz) range measured in Borok and Novosibirsk middle-latitude geophysical observatories located at the same longitudes as the examined mice. The spectral maxima of geomagnetic undulations and body temperature variations were observed with greatest probability at the frequencies of 1.6, 2.3, and 3.1 mHz. At this, the mean square of the distance between the frequencies of spectral maxima of simultaneous oscillations was smaller than that of random intervals favoring the hypothesis on geomagnetic undulations as the synchronizer of biorhythms. In both groups of mice, the share of intervals with a high spectral coherency between geomagnetic undulations and body temperature variations had common maximum in the pre-midnight sector of local time and it was higher for the large-scale geomagnetic undulations. Dependence of geomagnetic undulations on spatial scale suggests that body temperature is affected by electrotelluric field.
Asunto(s)
Temperatura Corporal/efectos de la radiación , Campos Electromagnéticos , Radiación Electromagnética , Animales , Temperatura Corporal/fisiología , Regulación de la Temperatura Corporal/efectos de la radiación , Ritmo Circadiano/fisiología , Ritmo Circadiano/efectos de la radiación , Campos Electromagnéticos/efectos adversos , Fenómenos Geológicos , Masculino , Ratones , Federación de Rusia , Factores de TiempoAsunto(s)
Regulación de la Temperatura Corporal/efectos de la radiación , Teléfono Celular , Neoplasias Inducidas por Radiación/fisiopatología , Estrés Fisiológico/efectos de la radiación , Animales , Temperatura Corporal/fisiología , Temperatura Corporal/efectos de la radiación , Femenino , Masculino , Ratones , Estrés Fisiológico/fisiología , Factores de TiempoRESUMEN
Health and performance impairments provoked by thermal stress are societal challenges geographically spreading and intensifying with global warming. Yet, science may be underestimating the true impact, since no study has evaluated effects of sunlight exposure on human brain temperature and function. Accordingly, performance in cognitively dominated and combined motor-cognitive tasks and markers of rising brainstem temperature were evaluated during exposure to simulated sunlight (equal to ~1000 watt/m2). Acute exposure did not affect any performance measures, whereas prolonged exposure of the head and neck provoked an elevation of the core temperature by 1 °C and significant impairments of cognitively dominated and motor task performances. Importantly, impairments emerged at considerably lower hyperthermia levels compared to previous experiments and to the trials in the presents study without radiant heating of the head. These findings highlight the importance of including the effect of sunlight radiative heating of the head and neck in future scientific evaluations of environmental heat stress impacts and specific protection of the head to minimize detrimental effects.
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Cognición/fisiología , Ejercicio Físico/fisiología , Trastornos de Estrés por Calor/fisiopatología , Luz Solar/efectos adversos , Adulto , Temperatura Corporal , Regulación de la Temperatura Corporal/fisiología , Regulación de la Temperatura Corporal/efectos de la radiación , Cognición/efectos de la radiación , Fiebre/etiología , Fiebre/fisiopatología , Cabeza/fisiopatología , Cabeza/efectos de la radiación , Trastornos de Estrés por Calor/etiología , Respuesta al Choque Térmico/fisiología , Respuesta al Choque Térmico/efectos de la radiación , Calor/efectos adversos , Humanos , Masculino , Energía Solar , Análisis y Desempeño de TareasRESUMEN
We studied the dynamics of the body temperature in mature male Wistar rats maintained under condition of constant illumination. It was shown that body temperature under these conditions varied with a 3-5-h period. The daily dynamics of body temperature summed up over 20-23-day intervals showed a 4-h ultradian rhythm with maxima at 3.35-4.30, 7.35-8.30, 11.35-12.30, 15.35-16.30, 19.35-20.30, and 23.35-00.30 h. During these hours, pronounced (>0.9°C) increase in body temperature was observed by 1.6 times more often than in other eriods. Thus, there are periods during the day when the increase in body temperature in rats in the absence of light cues occurs more often than in other periods of the day. Hence, about 4-h ultradian rhythm of body temperature has an external synchronizer that differs from lighting conditions.
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Temperatura Corporal , Iluminación , Ritmo Ultradiano/fisiología , Animales , Temperatura Corporal/efectos de la radiación , Regulación de la Temperatura Corporal/efectos de la radiación , Ritmo Circadiano/fisiología , Masculino , Fotoperiodo , Ratas , Ratas Wistar , Factores de TiempoRESUMEN
Otani, H, Goto, T, Goto, H, Hosokawa, Y, and Shirato, M. Solar radiation exposure has diurnal effects on thermoregulatory responses during high-intensity exercise in the heat outdoors. J Strength Cond Res 33(10): 2608-2615, 2019-This study investigated the diurnal effects of variations in solar radiation associated with changing solar elevation angle on thermoregulatory responses during high-intensity exercise in the heat outdoors. Ten male high school soccer players completed two 2-hour soccer training sessions under a clear sky in the heat of summer. These sessions were commenced at 0900 hours (AM) and 1600 hours (PM) on separate days. Solar radiation and elevation angle were higher in AM (820-1,070 W·m and 45-69°) than PM (620-110 W·m and 34-10°: both p < 0.001). Neither ambient temperature (AM 29-32° C; PM 31-31° C) nor wet-bulb globe temperature was different between trials. Although mean skin temperature was not different between trials, infrared tympanic temperature was higher at the end of exercise in AM than PM (p < 0.001). Heart rate (p < 0.01) and body heat gain from the sun (p < 0.001) were greater during exercise in AM than PM. Dry heat loss was smaller, but evaporative heat loss was greater in AM than PM (both p < 0.001). Thermal sensation and rating of perceived exertion were similar between trials, but GPS measurements showed a less total distance and distance covered by walking, jogging, and running in AM than PM (p < 0.01). This study demonstrates a greater thermoregulatory strain in AM than PM during 2-hour high-intensity soccer training in the heat under a clear sky. This observation is accompanied by a progressive increase in environmental heat stress with rising solar radiation and elevation angle in AM and a greater body heat gain from the sun in AM compared with PM.
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Regulación de la Temperatura Corporal/efectos de la radiación , Exposición a la Radiación , Fútbol/fisiología , Estrés Fisiológico/efectos de la radiación , Luz Solar , Adolescente , Temperatura Corporal , Regulación de la Temperatura Corporal/fisiología , Ritmo Circadiano/efectos de la radiación , Ejercicio Físico/fisiología , Frecuencia Cardíaca , Calor , Humanos , Masculino , Estrés Fisiológico/fisiología , Sensación Térmica , Pérdida Insensible de AguaRESUMEN
BACKGROUND: Two international guidelines/standards for human protection from electromagnetic fields define the specific absorption rate (SAR) averaged over 10 g of tissue as a metric for protection against localized radio frequency field exposure due to portable devices operating below 3-10 GHz. Temperature elevation is suggested to be a dominant effect for exposure at frequencies higher than 100 kHz. No previous studies have evaluated temperature elevation in the human head for local exposure considering thermoregulation. This study aims to discuss the temperature elevation in a human head model considering vasodilation, to discuss the conservativeness of the current limit. METHODS: This study computes the temperature elevations in an anatomical human head model exposed to radiation from a dipole antenna and truncated plane waves at 300 MHz-10GHz. The SARs in the human model are first computed using a finite-difference time-domain method. The temperature elevation is calculated by solving the bioheat transfer equation by considering the thermoregulation that simulates the vasodilation. RESULTS: The maximum temperature elevation in the brain appeared around its periphery. At exposures with higher intensity, the temperature elevation became larger and reached around 40 °C at the peak SAR of 100 W/kg, and became lower at higher frequencies. The temperature elevation in the brain at the current limit of 10 W/kg is at most 0.93 °C. The effect of vasodilation became notable for tissue temperature elevations higher than 1-2 °C and for an SAR of 10 W/kg. The temperature at the periphery was below the basal brain temperature (37 °C). CONCLUSIONS: The temperature elevation under the current guideline for occupational exposure is within the ranges of brain temperature variability for environmental changes in daily life. The effect of vasodilation is significant, especially at higher frequencies where skin temperature elevation is dominant.
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Regulación de la Temperatura Corporal/efectos de la radiación , Temperatura Corporal/fisiología , Temperatura Corporal/efectos de la radiación , Encéfalo/efectos de la radiación , Exposición a la Radiación/efectos adversos , Ondas de Radio/efectos adversos , Piel/efectos de la radiación , Adulto , Encéfalo/irrigación sanguínea , Encéfalo/fisiología , Humanos , Masculino , Modelos Biológicos , Flujo Sanguíneo Regional/efectos de la radiación , Piel/irrigación sanguínea , Fenómenos Fisiológicos de la Piel/efectos de la radiaciónRESUMEN
In the past decade, a handful but growing number of groups have reported worldwide successful low intensity focused ultrasound induced neurostimulation trials on rodents. Its effects range from movement elicitations to reduction of anesthesia time or reduction of the duration of drug induced seizures. The mechanisms underlying ultrasonic neuromodulation are still not fully understood. Given the low intensities used in most of the studies, a mechanical effect is more likely to be responsible for the neuromodulation effect, but a clear description of the thermal and mechanical effects is necessary to optimize clinical applications. Based on five studies settings, we calculated the temperature rise and thermal doses in order to evaluate its implication in the neuromodulation phenomenon. Our retrospective analysis shows thermal rise ranging from 0.002 °C to 0.8 °C in the brain for all setups, except for one setup for which the temperature increase is estimated to be as high as 7 °C. We estimate that in the latter case, temperature rise cannot be neglected as a possible cause of neuromodulation. Simulations results were supported by temperature measurements on a mouse with two different sets of parameters. Although the calculated temperature is compatible with the absence of visible thermal lesions on the skin, it is high enough to impact brain circuits. Our study highlights the usefulness of performing thermal simulations prior to experiment in order to fully take into account not only the impact of the peak intensity but also pulse duration and pulse repetition.
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Regulación de la Temperatura Corporal/efectos de la radiación , Temperatura Corporal/fisiología , Encéfalo/diagnóstico por imagen , Encéfalo/patología , Terapia por Estimulación Eléctrica/métodos , Terapia por Ultrasonido/métodos , Animales , Temperatura Corporal/efectos de la radiación , Ratones , Ratas , Estudios RetrospectivosRESUMEN
The use of electronic devices with light-emitting screens has increased exponentially in the last decade. As a result, humans are almost continuously exposed to unintentional artificial light. We explored the independent and combined effects of two aspects of screen illumination, light wavelength, and intensity, on sleep, its biological regulation, and related functional outcomes. The 2 × 2 repeated-measure design included two independent variables: screen light intensity (low ([LI] versus high [HI]) and wavelength (short [SWL] versus long [LWL]). Nineteen participants (11F, 8M; mean age 24.3 [±2.8] years) underwent four light conditions, LI/SWL, HI/SWL, LI/LWL, and HI/LWL, in counterbalanced order. Each light exposure lasted for two hours (21:00-23:00), following which participants underwent an overnight polysomnography. On each experimental night, oral temperature and urine samples (for melatonin analysis) were collected at multiple time points. Each morning, participants filled out questionnaires and conducted a computerized attention task. Irrespective of light intensity, SWL illumination significantly disrupted sleep continuity and architecture and led to greater self-reported daytime sleepiness. SWL light also altered biological rhythms, subduing the normal nocturnal decline in body temperature and dampening nocturnal melatonin secretion. Light intensity seemed to independently affect sleep as well, but to a lesser degree. Both light intensity and wavelength negatively affected morning attention. In sum, light wavelength seems to have a greater influence than light intensity on sleep and a wide-range of biological and behavioral functions. Given the widespread use of electronic devices today, our findings suggest that screen light exposure at evening may have detrimental effects on human health and performance.
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Atención/efectos de la radiación , Ritmo Circadiano/efectos de los fármacos , Computadores , Luz/efectos adversos , Trastornos del Sueño-Vigilia/etiología , Sueño/efectos de la radiación , Adulto , Biomarcadores/orina , Regulación de la Temperatura Corporal/efectos de la radiación , Femenino , Humanos , Masculino , Melatonina/orina , Distribución Aleatoria , Medición de Riesgo , Factores de Riesgo , Trastornos del Sueño-Vigilia/diagnóstico , Trastornos del Sueño-Vigilia/fisiopatología , Factores de Tiempo , Adulto JovenRESUMEN
This is a review/modeling study of heating of tissue by microwave energy in the frequency range from 3 GHz through the millimeter frequency range (30-300 GHz). The literature was reviewed to identify studies that reported RF-induced increases in skin temperature. A simple thermal model, based on a simplified form of Pennes' bioheat equation (BHTE), was developed, using parameter values taken from the literature with no further adjustment. The predictions of the model were in excellent agreement with available data. A parametric analysis of the model shows that there are two heating regimes with different dominant mechanisms of heat transfer. For small irradiated areas (less than about 0.5-1 cm in radius) the temperature increase at the skin surface is chiefly limited by conduction of heat into deeper tissue layers, while for larger irradiated areas, the steady-state temperature increase is limited by convective cooling by blood perfusion. The results support the use of this simple thermal model to aid in the development and evaluation of RF safety limits at frequencies above 3 GHz and for millimeter waves, particularly when the irradiated area of skin is small. However, very limited thermal response data are available, particularly for exposures lasting more than a few minutes to areas of skin larger than 1-2 cm in diameter. The paper concludes with comments about possible uses and limitations of thermal modeling for setting exposure limits in the considered frequency range.
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Regulación de la Temperatura Corporal/fisiología , Regulación de la Temperatura Corporal/efectos de la radiación , Modelos Biológicos , Temperatura Cutánea/fisiología , Temperatura Cutánea/efectos de la radiación , Piel/efectos de la radiación , Animales , Simulación por Computador , Relación Dosis-Respuesta en la Radiación , Humanos , Microondas , Dosis de RadiaciónRESUMEN
We investigated the thermal effects of radiofrequency electromagnetic fields (RF-EMFs) on the variation in core temperature and gene expression of some stress markers in rats. Sprague-Dawley rats were exposed to 2.14 GHz wideband code division multiple access (W-CDMA) RF signals at a whole-body averaged specific absorption rate (WBA-SAR) of 4 W/kg, which causes behavioral disruption in laboratory animals, and 0.4 W/kg, which is the limit for the occupational exposure set by the International Commission on Non-Ionizing Radiation Protection guideline. It is important to understand the possible in vivo effects derived from RF-EMF exposures at these intensities. Because of inadequate data on real-time core temperature analyses using free-moving animal and the association between stress and thermal effects of RF-EMF exposure, we analyzed the core body temperature under nonanesthetic condition during RF-EMF exposure. The results revealed that the core temperature increased by approximately 1.5°C compared with the baseline and reached a plateau till the end of RF-EMF exposure. Furthermore, we analyzed the gene expression of heat-shock proteins (Hsp) and heat-shock transcription factors (Hsf) family after RF-EMF exposure. At WBA-SAR of 4 W/kg, some Hsp and Hsf gene expression levels were significantly upregulated in the cerebral cortex and cerebellum following exposure for 6 hr/day but were not upregulated after exposure for 3 hr/day. On the other hand, there was no significant change in the core temperature and gene expression at WBA-SAR of 0.4 W/kg. Thus, 2.14-GHz RF-EMF exposure at WBA-SAR of 4 W/kg induced increases in the core temperature and upregulation of some stress markers, particularly in the cerebellum.
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Regulación de la Temperatura Corporal/efectos de la radiación , Encéfalo/efectos de la radiación , Campos Electromagnéticos , Ondas de Radio , Irradiación Corporal Total , Animales , Conducta Animal/efectos de la radiación , Encéfalo/metabolismo , Citocinas/genética , Citocinas/metabolismo , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Regulación de la Expresión Génica/efectos de la radiación , Factores de Transcripción del Choque Térmico , Proteínas de Choque Térmico/genética , Proteínas de Choque Térmico/metabolismo , Masculino , Actividad Motora/efectos de la radiación , Ratas Sprague-Dawley , Factores de Tiempo , Factores de Transcripción/genética , Factores de Transcripción/metabolismoRESUMEN
Sebocytes, which are characterized by lipid accumulation that leads to cell disruption, can be found in hair follicle-associated sebaceous glands (SGs) or in free SGs such as the Meibomian glands in the eyelids. Because genetic tools that allow targeting of sebocytes while maintaining intact epidermal lipids are lacking, the relevance of sebaceous lipids in health and disease remains poorly understood. Using Scd3, which is expressed exclusively in mature sebocytes, we established a mouse line with sebocyte-specific expression of Cre recombinase. Both RT-PCR analysis and crossing into Rosa26-lacZ reporter mice and Kras(G12D) mice confirmed Cre activity specifically in SGs, with no activity in other skin compartments. Importantly, loss of SCD3 function did not cause detectable phenotypical alterations, endorsing the usefulness of Scd3-Cre mice for further functional studies. Scd3-Cre-induced, diphtheria chain A toxin-mediated depletion of sebaceous lipids resulted in impaired water repulsion and thermoregulation, increased rates of UVB-induced epidermal apoptosis and caused a severe pathology of the ocular surface resembling Meibomian gland dysfunction. This novel mouse line will be useful for further investigating the roles of sebaceous lipids in skin and eye integrity.
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Apoptosis/efectos de la radiación , Ojo/efectos de la radiación , Lípidos/química , Glándulas Sebáceas/química , Rayos Ultravioleta , Agua/química , Animales , Regulación de la Temperatura Corporal/efectos de la radiación , Síndromes de Ojo Seco/complicaciones , Síndromes de Ojo Seco/patología , Homocigoto , Humanos , Inflamación/complicaciones , Inflamación/patología , Integrasas/metabolismo , Glándulas Tarsales/metabolismo , Glándulas Tarsales/efectos de la radiación , Ratones Endogámicos C57BL , Tamaño de los Órganos , Especificidad de Órganos/efectos de la radiación , Fenotipo , Proteínas Proto-Oncogénicas p21(ras)/metabolismo , Sebo/metabolismoRESUMEN
BACKGROUND: Schizophrenia is accompanied by altered motor activity and abnormal thermoregulation; therefore, the presence of these symptoms can enhance the face validity of a schizophrenia animal model. The goal was to characterize these parameters in freely moving condition of a new substrain of rats showing several schizophrenia-related alterations. METHODS: Male Wistar rats were used: the new substrain housed individually (for four weeks) and treated subchronically with ketamine, and naive animals without any manipulations. Adult animals were implanted with E-Mitter transponders intraabdominally to record body temperature and locomotor activity continuously. The circadian rhythm of these parameters and the acute effects of changes in light conditions were analyzed under undisturbed circumstances, and the effects of different interventions (handling, bed changing or intraperitoneal vehicle injection) were also determined. RESULTS: Decreased motor activity with fragmented pattern was observed in the new substrain. However, these animals had higher body temperature during the active phase, and they showed wider range of its alterations, too. The changes in light conditions and different interventions produced blunted hyperactivity and altered body temperature responses in the new substrain. Poincaré plot analysis of body temperature revealed enhanced short- and long-term variabilities during the active phase compared to the inactive phase in both groups. Furthermore, the new substrain showed increased short- and long-term variabilities with lower degree of asymmetry suggesting autonomic dysregulation. CONCLUSIONS: In summary, the new substrain with schizophrenia-related phenomena showed disturbed motor activity and thermoregulation suggesting that these objectively determined parameters can be biomarkers in translational research.
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Regulación de la Temperatura Corporal , Actividad Motora , Esquizofrenia/fisiopatología , Investigación Biomédica Traslacional , Animales , Temperatura Corporal/efectos de la radiación , Regulación de la Temperatura Corporal/efectos de la radiación , Ritmo Circadiano/efectos de la radiación , Modelos Animales de Enfermedad , Luz , Masculino , Actividad Motora/efectos de la radiación , Ratas , Ratas WistarRESUMEN
This study considers the computationally determined thermal profile of a fully clothed, finely discretized, heterogeneous human body model, subject to the maximum allowable reference level for a 1-GHz radio frequency electromagnetic field for a worker, and also subject to adverse environmental conditions, including high humidity and high ambient temperature. An initial observation is that while electromagnetic fields at the occupational safety limit will contribute an additional thermal load to the tissues, and subsequently, cause an elevated temperature, the magnitude of this effect is far outweighed by that due to the conditions including the ambient temperature, relative humidity, and the type of clothing worn. It is envisaged that the computational modeling approach outlined in this paper will be suitably modified in future studies to evaluate the thermal response of a body at elevated metabolic rates, and for different body shapes and sizes including children and pregnant women.
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Regulación de la Temperatura Corporal/efectos de la radiación , Vestuario , Exposición a Riesgos Ambientales/efectos adversos , Monitoreo del Ambiente/métodos , Fiebre/fisiopatología , Modelos Biológicos , Irradiación Corporal Total/efectos adversos , Adulto , Regulación de la Temperatura Corporal/fisiología , Simulación por Computador , Relación Dosis-Respuesta en la Radiación , Exposición a Riesgos Ambientales/análisis , Fiebre/etiología , Calor , Humanos , Humedad , Masculino , Dosis de Radiación , Ondas de Radio/efectos adversosRESUMEN
This paper presents a new thermal stress index for dairy cows in inter-tropical regions, with special mention to the semi-arid ones. Holstein cows were measured for rectal temperature (T R), respiratory rate (F R) and rates of heat exchange by convection (C), radiation (R), skin surface evaporation (E S) and respiratory evaporation (E R) in the north eastern region of Brazil, after exposure to sun for several hours. Average environmental measurements during the observations were air temperature (T A) 32.4 °C (24.4-38.9°), wind speed (U) 1.8 m.s(-1) (0.01-11.0), relative humidity 63.6 % (36.8-81.5) and short-wave solar radiation 701.3 W m(-2) (116-1,295). The effective radiant heat load (ERHL) was 838.5 ± 4.9 W m(-2). Values for the atmospheric transmittance (τ) were also determined for tropical regions, in order to permit adequate estimates of the solar radiation. The average value was τ = 0.611 ± 0.004 for clear days with some small moving clouds, with a range of 0.32 to 0.91 in the day period from 1000 to 1300 hours. Observed τ values were higher (0.62-0.66) for locations near the seacoast and in those regions well-provided with green fields. Effects of month, location and time of the day were all statistically significant (P < 0.01). A total of 1,092 data were obtained for cows exposed for 1 to 8 h to sun during the day; in 7 months (February, March, April, July, August, September and November), 4 days per month on the average. A principal component analysis summarised the T R, F R, C, R, E S and E R measurements into just one synthetic variable (y 1); several indexes were then obtained by multiple regression of y 1 on the four environmental variables and its combinations, by using Origin 8.1 software (OriginLab Corp.). The chosen equation was the index of thermal stress for cows, ITSC = 77.1747 + 4.8327 T A - 34.8189 U + 1.111 U (2) + 118.6981 P V - 14.7956 P V (2) - 0.1059 ERHL with r (2) = 0.812. The correlations of ITSC with T R, F R, C, E S, R and E R were 0.275, 0.255, -0.493, -0.647, -0.818 and 0.075, respectively. Correlations of the index with the physiological variables are presented, and ITSC is compared to three other indexes.
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Regulación de la Temperatura Corporal/fisiología , Bovinos/fisiología , Respuesta al Choque Térmico/fisiología , Respuesta al Choque Térmico/efectos de la radiación , Energía Solar , Clima Tropical , Animales , Regulación de la Temperatura Corporal/efectos de la radiación , Brasil , Clima , Ecosistema , Dosis de Radiación , Frecuencia Respiratoria/fisiología , Frecuencia Respiratoria/efectos de la radiaciónRESUMEN
PURPOSE: This article investigates the safety of radiofrequency induced local thermal hotspots within a 1.5T body coil by assessing the transient local peak temperatures as a function of exposure level and local thermoregulation in four anatomical human models in different Z-positions. METHODS: To quantize the effective thermal stress of the tissues, the thermal dose model cumulative equivalent minutes at 43°C was employed, allowing the prediction of thermal tissue damage risk and the identification of potentially hazardous MR scan-scenarios. The numerical results were validated by B1 (+) - and skin temperature measurements. RESULTS: At continuous 4 W/kg whole-body exposure, peak tissue temperatures of up to 42.8°C were computed for the thermoregulated model (60°C in nonregulated case). When applying cumulative equivalent minutes at 43°C damage thresholds of 15 min (muscle, skin, fat, and bone) and 2 min (other), possible tissue damage cannot be excluded after 25 min for the thermoregulated model (4 min in nonregulated). CONCLUSION: The results are found to be consistent with the history of safe use in MR scanning, but not with current safety guidelines. For future safety concepts, we suggest to use thermal dose models instead of temperatures or SAR. Special safety concerns for patients with impaired thermoregulation (e.g., the elderly, diabetics) should be addressed.
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Regulación de la Temperatura Corporal/efectos de la radiación , Quemaduras por Electricidad/etiología , Quemaduras por Electricidad/fisiopatología , Imagen por Resonancia Magnética/efectos adversos , Imagen por Resonancia Magnética/instrumentación , Irradiación Corporal Total/efectos adversos , Irradiación Corporal Total/instrumentación , Carga Corporal (Radioterapia) , Simulación por Computador , Diseño de Equipo , Análisis de Falla de Equipo , Humanos , Imagen por Resonancia Magnética/normas , Modelos Biológicos , Dosis de Radiación , Radiometría/métodos , Valores de Referencia , SuizaRESUMEN
Acetaminophen (paracetamol) is a commonly used over-the-counter analgesic and antipyretic and has previously been shown to improve exercise performance through a reduction in perceived pain. This study sought to establish whether its antipyretic action may also improve exercise capacity in the heat by moderating the increase in core temperature. On separate days, 11 recreationally active participants completed two experimental time-to-exhaustion trials on a cycle ergometer in hot conditions (30°C, 50% relative humidity) after ingesting a placebo control or an oral dose of acetaminophen in a randomized, double-blind design. Following acetaminophen ingestion, participants cycled for a significantly longer period of time (acetaminophen, 23 ± 15 min versus placebo, 19 ± 13 min; P = 0.005; 95% confidence interval = 90-379 s), and this was accompanied by significantly lower core (-0.15°C), skin (-0.47°C) and body temperatures (0.19°C; P < 0.05). In the acetaminophen condition, participants also reported significantly lower ratings of thermal sensation (-0.39; P = 0.015), but no significant change in heart rate was observed (P > 0.05). This is the first study to demonstrate that an acute dose of acetaminophen can improve cycling capacity in hot conditions, and that this may be due to the observed reduction in core, skin and body temperature and the subjective perception of thermal comfort. These findings suggest that acetaminophen may reduce the thermoregulatory strain elicited from exercise, thus improving time to exhaustion.
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Acetaminofén/farmacología , Regulación de la Temperatura Corporal/efectos de los fármacos , Temperatura Corporal/efectos de los fármacos , Ejercicio Físico/fisiología , Fatiga/tratamiento farmacológico , Adulto , Temperatura Corporal/fisiología , Regulación de la Temperatura Corporal/efectos de la radiación , Método Doble Ciego , Ingestión de Alimentos/fisiología , Prueba de Esfuerzo/métodos , Fatiga/fisiopatología , Frecuencia Cardíaca/efectos de los fármacos , Frecuencia Cardíaca/efectos de la radiación , Calor , Humanos , Masculino , Adulto JovenRESUMEN
This comprehensive clinical and laboratory study was designed to elucidate the antioxidant status of the volunteers before and after a course of general infrared irradiation. It was shown that the effect of high temperatures promotes the development of oxidative stress that is followed by the formation of adaptive reactions in the form of activation of antioxidant protection, enhancement of non-specific responses of the cells, increase of stability and restoration of structural homeostasis of erythrocyte membranes. The molecular mechanism of endothelium-independent vasodilation develops by the end of the treatment period; it may serve as the compensatory-adaptive reaction needed to maintain the adequate tone of the vascular wall and thereby to support the functioning of mechanisms supporting physical thermoregulation. The results of the study give evidence of the stimulatory influence of the described method on the adaptive and protective potential of the organism. It is concluded that the proposed scheme of physiotherapeutic treatment may be used for prophylactic purposes.
Asunto(s)
Antioxidantes/metabolismo , Regulación de la Temperatura Corporal/efectos de la radiación , Membrana Eritrocítica/metabolismo , Rayos Infrarrojos/uso terapéutico , Baño de Vapor , Vasodilatación/efectos de la radiación , Adulto , Endotelio Vascular , Humanos , MasculinoRESUMEN
The effects of radiofrequency electromagnetic fields (RF-EMF) on the control of body energy balance in developing organisms have not been studied, despite the involvement of energy status in vital physiological functions. We examined the effects of chronic RF-EMF exposure (900 MHz, 1 V m(-1)) on the main functions involved in body energy homeostasis (feeding behaviour, sleep and thermoregulatory processes). Thirteen juvenile male Wistar rats were exposed to continuous RF-EMF for 5 weeks at 24 °C of air temperature (T a) and compared with 11 non-exposed animals. Hence, at the beginning of the 6th week of exposure, the functions were recorded at T a of 24 °C and then at 31 °C. We showed that the frequency of rapid eye movement sleep episodes was greater in the RF-EMF-exposed group, independently of T a (+42.1 % at 24 °C and +31.6 % at 31 °C). The other effects of RF-EMF exposure on several sleep parameters were dependent on T a. At 31 °C, RF-EMF-exposed animals had a significantly lower subcutaneous tail temperature (-1.21 °C) than controls at all sleep stages; this suggested peripheral vasoconstriction, which was confirmed in an experiment with the vasodilatator prazosin. Exposure to RF-EMF also increased daytime food intake (+0.22 g h(-1)). Most of the observed effects of RF-EMF exposure were dependent on T a. Exposure to RF-EMF appears to modify the functioning of vasomotor tone by acting peripherally through α-adrenoceptors. The elicited vasoconstriction may restrict body cooling, whereas energy intake increases. Our results show that RF-EMF exposure can induce energy-saving processes without strongly disturbing the overall sleep pattern.
Asunto(s)
Envejecimiento , Regulación de la Temperatura Corporal/efectos de la radiación , Campos Electromagnéticos/efectos adversos , Conducta Alimentaria/efectos de la radiación , Ondas de Radio/efectos adversos , Sueño/efectos de la radiación , Animales , Masculino , Prazosina/administración & dosificación , Ratas , Ratas Wistar , Cola (estructura animal)/irrigación sanguínea , Cola (estructura animal)/efectos de la radiación , Temperatura , Factores de Tiempo , Vasoconstricción/efectos de la radiación , Vasodilatadores/administración & dosificaciónRESUMEN
The daily solar cycle allows organisms to synchronize their circadian rhythms and sleep-wake cycles to the correct temporal niche. Changes in day-length, shift-work, and transmeridian travel lead to mood alterations and cognitive function deficits. Sleep deprivation and circadian disruption underlie mood and cognitive disorders associated with irregular light schedules. Whether irregular light schedules directly affect mood and cognitive functions in the context of normal sleep and circadian rhythms remains unclear. Here we show, using an aberrant light cycle that neither changes the amount and architecture of sleep nor causes changes in the circadian timing system, that light directly regulates mood-related behaviours and cognitive functions in mice. Animals exposed to the aberrant light cycle maintain daily corticosterone rhythms, but the overall levels of corticosterone are increased. Despite normal circadian and sleep structures, these animals show increased depression-like behaviours and impaired hippocampal long-term potentiation and learning. Administration of the antidepressant drugs fluoxetine or desipramine restores learning in mice exposed to the aberrant light cycle, suggesting that the mood deficit precedes the learning impairments. To determine the retinal circuits underlying this impairment of mood and learning, we examined the behavioural consequences of this light cycle in animals that lack intrinsically photosensitive retinal ganglion cells. In these animals, the aberrant light cycle does not impair mood and learning, despite the presence of the conventional retinal ganglion cells and the ability of these animals to detect light for image formation. These findings demonstrate the ability of light to influence cognitive and mood functions directly through intrinsically photosensitive retinal ganglion cells.
Asunto(s)
Afecto/efectos de la radiación , Aprendizaje/efectos de la radiación , Luz , Células Ganglionares de la Retina/metabolismo , Células Ganglionares de la Retina/efectos de la radiación , Opsinas de Bastones , Afecto/efectos de los fármacos , Afecto/fisiología , Animales , Antidepresivos/farmacología , Regulación de la Temperatura Corporal/fisiología , Regulación de la Temperatura Corporal/efectos de la radiación , Ritmo Circadiano/fisiología , Cognición/efectos de los fármacos , Cognición/fisiología , Cognición/efectos de la radiación , Corticosterona/metabolismo , Depresión/etiología , Depresión/fisiopatología , Desipramina/farmacología , Fluoxetina/farmacología , Aprendizaje/efectos de los fármacos , Aprendizaje/fisiología , Potenciación a Largo Plazo/efectos de los fármacos , Masculino , Memoria/fisiología , Memoria/efectos de la radiación , Ratones , Fotoperiodo , Células Ganglionares de la Retina/efectos de los fármacos , Opsinas de Bastones/análisis , Sueño/fisiología , Vigilia/fisiologíaRESUMEN
The effects of ultrahigh-frequency electromagnetic radiation (UHF EMR) and low-intensity laser irradiation (LILI) on the body and skin temperature, oxygen consumption, production of carbon dioxide and heat release were investigated in the experiments on intact rats and during LPS-induced polyphasic fever. It was found that UHF EMR with the wavelength of 4,9 mm, 5,6 mm or 7,1 mm and LILI with the wavelength of 0.47 microm, 0.67 microm and 0.87 microm caused modulation of basal metabolism and thermal response to systemically administered lipopolysaccharide (LPS). These findings suggest that the most pronounced antipyretic and hypometabolic effects were observed after the treatment with UHF EMR at 7,1 mm and LILI at 470 microm.