Comparabilidad del autorrefractómetro portátil Retinomax K-plus 3 en modo rápido versus autorrefractómetro de sobremesa en modo estándar / Comparability of the Retinomax K-plus 3 handheld autorefractometer in quick mode versus on-table autorefractometer in standard mode

I ntroducción Este estudio analiza la comparabilidad de las medidas tomadas por un autorefractómetro portátil Retinomax K-plus 3 en modo Quick (rápido) y un autorrefractómetro de sobremesa Topcon KR-800 en modo estándar sobre la población pediátrica, y establece su correlación. Método Es un estudio comparativo retrospectivo. Se midieron las variables potencia dióptrica esférica (SPH), potencia dióptrica cilíndrica (CYL), ángulo del eje cilíndrico (AX) y equivalente esférico (SE) con el Retinomax en modo Quick y con el Topcon en modo estándar. Cada paciente fue evaluado en condiciones ciclopléjicas y no ciclopléjicas por ambos autorefractómetros. Se realizó la prueba t de Student entre ambos instrumentos para SPH, CYL y SE. Se calculó el coeficiente de correlación de Pearson y se representó la dispersión mediante gráficas de Bland-Altman, evaluándose también el subgrupo de pacientes menores de 4 años. Se realizó un análisis descriptivo de los porcentajes de medidas que diferían. Resultados Incluyó 98 ojos de 49 sujetos (rango de edad: 3-16 años). Los datos de SPH sin cicloplejia son prácticamente idénticos, mientras que con cicloplejia hay un sesgo hipermetrópico de +0,5 dioptrías medidas con Retinomax. Los resultados de CYL son muy similares con y sin cicloplejia. Existe una gran correlación de Pearson para ambos instrumentos (>0,91) y un bajo grado de dispersión en los gráficos de Bland-Altman bajo cicloplejia. Conclusión Los datos del Retinomax fueron consistentes con los obtenidos por el Topcon. El Retinomax es un instrumento útil para detectar errores de refracción en niños de entre 3 y 16 años (AU)

Introduction This study analyzes the comparability of measurements taken by a Retinomax K-plus 3 handheld autorefractometer in quick mode and a Topcon KR-800 on-table autorefractometer in standard mode on the pediatric population, and establishes their correlation. Methods It is a retrospective comparative study. Spherical diopter power (SPH), cylindrical diopter power (CYL), angle of cylindrical axis (AX), and spherical equivalent (SE) were measured with the Retinomax in quick mode and with the Topcon in standard mode. Each patient was evaluated in cycloplegic and non-cycloplegic conditions by both autorefractometers. Student's t-test was performed between the two instruments for SPH, CYL, and SE. The Pearson correlation coefficient was calculated and the dispersion was represented using Bland-Altman graphs, also evaluating the subgroup of patients under 4 years of age. A descriptive analysis of the percentages of measures that differed was performed. Results It included 98 eyes of 49 subjects (age range: 3-16 years). The data for HPS without cycloplegia are virtually identical, whereas with cycloplegia there is a hyperopic bias of +0.5 diopters measured with Retinomax. CYL results are very similar with and without cycloplegia. There is a high Pearson correlation for both instruments (>0.91) and a low degree of dispersion in the Bland-Altman plots under cycloplegia. Conclusion The Retinomax data were consistent with those obtained by Topcon. The Retinomax is a useful instrument for detecting refractive errors in children between 3 and 16 years of age (AU)

Comparability of the Retinomax K-plus 3 handheld autorefractometer in quick mode versus on-table autorefractometer in standard mode.

INTRODUCTION: This study analyzes the comparability of measurements taken by a Retinomax K-plus 3 handheld autorefractometer in Quick mode and a Topcon KR-800 on-table autorefractometer in standard mode on the pediatric population, and establishes their correlation. METHODS: It is a retrospective comparative study. Spherical diopter power (SPH), cylindrical diopter power (CYL), angle of cylindrical axis (AX), and spherical equivalent (SE) were measured with the Retinomax in Quick mode and with the Topcon in standard mode. Each patient was evaluated in cycloplegic and non-cycloplegic conditions by both autorefractometers. Student's t-test was performed between the two instruments for SPH, CYL, and SE. The Pearson correlation coefficient was calculated and the dispersion was represented using Bland-Altman graphs, also evaluating the subgroup of patients under 4 years of age. A descriptive analysis of the percentages of measures that differed was performed. RESULTS: It included 98 eyes of 49 subjects (age range: 3-16 years). The data for HPS without cycloplegia are virtually identical, whereas with cycloplegia there is a hyperopic bias of +0.5 diopters measured with Retinomax. CYL results are very similar with and without cycloplegia. There is a high Pearson correlation for both instruments (>0.91) and a low degree of dispersion in the Bland-Altman plots under cycloplegia. CONCLUSION: The Retinomax data were consistent with those obtained by Topcon. The Retinomax is a useful instrument for detecting refractive errors in children between 3 and 16 years of age.

Sequential teratoma in pediatric patients: causation or coincidence? / Teratoma de aparición secuencial en edad pediátrica: ¿casualidad o causalidad?

We describe the unusual case of a female patient with a history of two mature teratomas non-correlated in terms of location and occurrence. A 12-year-old girl presented at our consultation as a result of a growing tumor in the hypogastric region, with no further clinical signs. She had undergone surgery neonatally due to a mature cystic sacrococcygeal teratoma, which was fully removed. No clinical sequelae were noted and no additional treatment was required over a 10-year follow-up. Radiological examination showed a large 20 × 12 × 18 cm cystic mass extending from the pelvic region to the lower hemiabdomen, associated with two similar small formations adjacent to the right ovary. Tumor markers were negative, and a laparoscopic right salpingoophorectomy was carried out, with an excellent postoperative progression. Pathological examination revealed it was, again, a mature cystic teratoma. The genetic study ruled out causation in this respect.

Describimos el inusual caso de una paciente con antecedente de dos teratomas maduros no relacionados en cuanto a su localización y debut. Una niña de 12 años consultó por la aparición de una tumoración en la región hipogástrica de crecimiento progresivo sin otra clínica asociada. Había sido intervenida por un teratoma quístico maduro sacrococcígeo en el periodo neonatal con su extirpación completa y, ausencia secuelas clínicas y tratamiento adicional durante diez años de seguimiento posterior. Los exámenes radiológicos mostraron una gran masa quística de 20 × 12 × 18 cm que se extendía entre la región pélvica y el hemiabdomen inferior, acompañada por otras dos pequeñas formaciones similares adyacentes al ovario derecho. Los marcadores tumorales resultaron negativos y se llevó a cabo una salpingooforectomía derecha laparoscópica con una excelente evolución postoperatoria. El examen histopatológico, de nuevo, informó la lesión como teratoma quístico maduro. El estudio genético descartó una posible causalidad en este ámbito.

[Pacemaker, implanted cardiac defibrillator and irradiation: Management proposal in 2010 depending on the type of cardiac stimulator and prognosis and location of cancer]. / Pacemaker, défibrillateur et radiothérapie : propositions de conduite à tenir en 2010 en fonction du type de stimulateur cardiaque, du pronostic et du site du cancer.

Ionizing radiation may interfere with electric components of pacemakers or implantable cardioverter-defibrillators. The type, severity and extent of radiation damage to pacemakers, have previously been shown to depend on the total dose and dose rate. Over 300,000 new cancer cases are treated yearly in France, among which 60% are irradiated in the course of their disease. One among 400 of these patients has an implanted pacemaker or defibrillator. The incidence of pacemaker and implanted cardioverter defribillator increases in an ageing population. The oncologic prognosis must be weighted against the cardiologic prognosis in a multidisciplinary and transversal setting. Innovative irradiation techniques and technological sophistications of pacemakers and implantable cardioverter-defibrillators (with the introduction of more radiosensitive complementary metal-oxide-semiconductors since 1970) have potentially changed the tolerance profiles. This review of the literature studied the geometric, dosimetric and radiobiological characteristics of the radiation beams for high energy photons, stereotactic irradiation, protontherapy. Standardized protocols and radiotherapy optimization (particle, treatment fields, energy) are advisable in order to improve patient management during radiotherapy and prolonged monitoring is necessary following radiation therapy. The dose received at the pacemaker/heart should be calculated. The threshold for the cumulated dose to the pacemaker/implantable cardioverter-defibrillator (2 to 5 Gy depending on the brand), the necessity to remove/displace the device based on the dose-volume histogram on dosimetry, as well as the use of lead shielding and magnet are discussed.

[Bevacizumab and lung cancer: eligible patients in daily practice]. / Bévacizumab et cancer bronchique: population cible en pratique quotidienne.

BACKGROUND: Combining bevacizumab with platinum-based chemotherapy significantly improves survival for patients with advanced non-squamous non-small cell lung cancer. The objective of this study was to assess the proportion of patients who could receive this combined therapy. METHODS: This was a retrospective single centre analysis of patients treated between 2007 and 2008. Exclusion criteria for bevacizumab included: squamous cell carcinoma, contraindication to platinum-based chemotherapy, uncontrolled hypertension, haemoptysis superior to 2.5 mL, recent surgery, and/or tomodensitometric criteria after independent review by two radiologists (contact with a proximal vessel, tracheobronchial involvement, cavitation). Cardiovascular diseases and central tumour location were not systematically considered as contraindications. RESULTS: Among 194 patients analysed, 21 (10.8%) to 35 (18%) patients were eligible for bevacizumab, whether or not cardiovascular diseases and central tumour location were considered as contraindications. The kappa coefficient was 0.49. CONCLUSION: Even though the proportion of patients who can receive chemotherapy plus bevacizumab may vary according to the eligibility criteria chosen and the interpretation of the CT scan, it is unlikely to exceed 25% of patients in daily practice.

Obstructive sleep apnea has little impact on quality of life in the elderly.

STUDY OBJECTIVE: To analyze the impact of the number of respiratory sleep disorders or clinically related conditions (especially excessive daytime sleepiness [EDS]), on health related quality of life (HRQoL) in subjects over 65 years of age, as compared to younger subjects and the general population. METHODS: Two hundred and twelve adult patients with obstructive sleep apnea (OSA, AHI> or =10) divided into two age groups, over 65 (n=109, mean age 74.6 [6,8] years, and 65 or under (n=103, mean age 51.7, [6,5] years). General, anthropometric and clinical data related to OSA (epworth sleepiness score [ESS]), comorbidities (Charlson comorbidity index [CCI]), HRQoL (SF-36 questionnaire), use of psychotropic medications and habitual polygraphic/polysomnographic parameters were recorded and compared between the two age groups. The HRQoL values in each age group were compared with the values in the general population, adjusted for age and gender. RESULTS: In patients 65 and under, both the presence of OSA as well as the presence of EDS (ESS>11) were associated with an important deterioration in HRQoL as compared to normal reference values. The principal determinants of HRQoL were the presence of EDS (p<0.04), body mass index (p<0.03) and the apnea-hypopnea index (AHI) (p<0.04). Nevertheless, in subjects over 65 years of age, the presence of OSA or EDS had only a slight impact on HRQoL, relative to normal values. In this age group, the principal determinants of HRQoL were the presence of comorbidities (CCI, p<0.01), age (p<0.01), oxygen desaturation parameters (p<0.04) and the use of psychotropic medications (p<0.04). CONCLUSION: In elders, the presence of OSA with or without EDS has little impact on HRQoL measures.

Dental and periodontal lesions in patients with gastro-oesophageal reflux disease.

OBJECTIVE: Dental erosion has been considered an extraesophageal manifestation of gastro-oesophageal reflux disease, but few reports have studied the relationship between this disease and other periodontal or dental lesions. The aim of this study was to investigate the prevalence of dental and periodontal lesions in patients with gastro-oesophageal reflux disease. PATIENTS AND METHODS: A total of 253 subjects were prospectively studied between April 1998 and May 2000. Two study groups were established: 181 patients with gastro-oesophageal reflux disease and 72 healthy volunteers. Clinical assessment, including body mass index and consumption of tobacco and alcohol, was performed in all subjects, as well as a dental and periodontal examination performed by a dentist physician, blind as to the diagnosis of subjects. Parameters evaluated were: (a) presence and number of dental erosion, location and severity, according to the Eccles and Jenkins index [Prosthet Dent 1979;42:649-53], modified by Hattab [Int J Prosthes 2000;13:101-71; (b) assessment of dental condition by means of the CAO index; and (c) periodontal status analysed by the plaque index, the haemorrhage index, and gingival recessions. RESULTS: Clinical parameters were similar in both groups (p > 0.05). Age was statistically associated with the CAO index, presence of dental erosion, and gingival recession (p < 0.001, Student's t-test). Compared with the control group, the percentage of dental erosion was significantly higher in the gastro-oesophageal reflux disease group (12.5 vs. 47.5%, p < 0.001, chi2-test), as was the number and severity of dental erosions (p < 0.001, Student's t-test). Location of dental erosion was significantly different between groups. Age was not statistically related to either the amount or severity of dental erosion. CAO and periodontal indices were similarly distributed between groups. CONCLUSIONS: Dental erosion may even be considered as an extraesophageal manifestation of gastro-oesophageal reflux disease. The fact that the prevalence of caries and periodontal lesions is similar in patients with gastro-oesophageal reflux disease and in healthy volunteers suggests a lack of relationship with gastro-oesophageal reflux disease.

[Macular translocation in myopic patient wearing a phakic intraocular lens]. / Translocación macular en paciente miope portador de lente fáquica intraocular.

UNLABELLED: PURPOSE/MATERIAL AND METHOD: To report a case of macular translocation surgery in a myopic patient with a phakic intraocular lens, which developed subfoveal choroidal neovascularization. RESULTS: A 45 year-old woman wearing a phakic intraocular lens to correct a high myopia presented a 0.3 visual acuity because of subfoveal choroidal neovascularization. Peripheral retina had been treated by argon laser for lattice degeneration. Limited macular translocation was performed. Chorioscleral infolding was created by a circular scleral buckle. Her visual acuity, six months after surgery became 0.7. CONCLUSION: This report shows the feasibility of the use of limited macular translocation for the management of high myopic eyes with phakic intraocular lenses, in patients who suffer from subfoveal choroidal neovascularization.

Translocación macular en paciente miope portador de lente fáquica intraocular / Macular translocation in myopic patient wearing a phakic intraocular lens

Objetivo/métodos: Se presenta un caso de cirugía de translocación macular realizada en una paciente miope portadora de lente intraocular fáquica que desarrolló neovascularización coroidea subfoveal. Resultados: Una paciente de 45 años de edad, portadora de lente fáquica intraocular, presentó una agudeza visual de 0,3 debido a neovascularización coroidea subfoveal secundaria a alta miopía. La paciente presentaba lesiones degenerativas en retina periférica tratadas con láser de Argón. Fue intervenida de translocación macular limitada utilizando un implante escleral circunferencial para soportar el plegamiento corioescleral. La agudeza visual era de 0,7 seis meses después de la intervención. Conclusión: El tratamiento de la neovascularización subfoveal coroidea en pacientes miopes portadores de lente intraocular fáquica puede ser realizado mediante translocación macular limitada (AU)

The concept of habitat diversity between and within ecosystems applied to river side-arm restoration.

Since returning an ecosystem to its pristine state may not be realistic in every situation, the concept of habitat diversity is proposed to help decision-makers in defining realistic restoration objectives. In order to maintain habitat diversity and enhance the long-term success of restoration, process-oriented projects should be preferred to species-oriented ones. Because the hydrogeomorphological processes that influence biodiversity operate at different spatiotemporal scales, three scales are considered: river sectors, floodplain waterbodies, and mesohabitats within each waterbody. Based on a bibliographical review, three major driving forces are proposed for incorporation into the design of restoration projects: (1) flow velocity and flood disturbances, (2) hydrological connectivity, and (3) water supply. On the sector scale, increased habitat diversity between waterbodies can be achieved by combining various intensities of these driving forces. On the waterbody scale, increased habitat diversity within the ecosystem can be achieved by varying water depth, velocity, and substrate. The concept is applied to a Rhjne River sector (France) where three terrestrialized side arms will be restored. Two were designed to be flood scoured, one having an additional supply of groundwater, the other being connected to the river at both ends. The third cannot be scoured by floods because of upstream construction and would be supplied by river backflow through a downstream connection. Habitat diversity within the ecosystem is exemplified on one side arm through the design of a sinuous pathway combined with variation of water depth, wetted width, and substrate grain size. Self-colonization of the side arms is expected owing to the restoration of connectivity to upstream sources of potential colonizers.

ENVIRONMENTAL AUDITING: A Vegetation-Based Method for Ecological Diagnosis of Riverine Wetlands.

/ The management of riverine wetlands, recognized as a major component of biodiversity in fluvial hydrosystems, is problematic. Preservation or restoration of such ecosystems requires a method to assess the major ecological processes operating in the wetlands, the sustainability of the aquatic stage, and the restoration potential of each riverine wetland. We propose a method of diagnosis based on aquatic macrophytes and helophytes. Plant communities are used because they are easy to survey and provide information about (1) the origin of a water supply (i.e., groundwater, seepage, or surface river water) and its nutrient content, (2) effects of flood disturbances, and (3) terrestrialization processes. The novelty of the method is that, in contrast to available typologies, it is based on the interference of gradients resulting from several processes, which makes it possible to predict wetland sustainability and restoration potential. These predictions result from knowledge of the processes involved in terrestrialization, i.e., the influence of flood disturbances, occurrence of groundwater supplies, trophic degree, and water permanency of the habitat during a yearly cycle. The method is demonstrated on five different river systems.

Prevalence of HTLV infection in the Dominican Republic: association with neurological disease.

The presence of the human T-cell leukemia virus (HTLV) in Dominican blood donors and patients with tropical spastic paraparesis (TSP) was first detected in 1987. To define further the seroprevalence in the country, nearly 4,000 samples from high- and low-risk populations, as well as patients with neurological disease and with leukemia or lymphoma were tested for HTLV antibodies. A 1-2% seropositivity rate was found among the low-risk population, a 2-5% in the high-risk, and at least 87% in those with TSP. A few patients with malignancy also had antibodies to HTLV. An increase in seropositivity with age and a predominance of female seropositive individuals were found. Infectious virus was isolated from TSP patients, prostitutes, and family members of index patients. These data indicate the substantial level of HTLV infection in another Caribbean country and its relation to neurologic disease.

Effect of continuous heat exposure on sleep stages in humans.

Six young men were exposed to a thermoneutral environment of air temperature (Ta) 20 degrees C for 5 days and nights followed by an acclimation period of 5 days and nights at Ta 35 degrees C and 2 recovery days and nights at Ta 20 degrees C. Electrophysiological measures of sleep, esophageal temperature, and mean skin temperature were continuously monitored. The total nocturnal body weight loss was measured by a sensitive platform scale. Compared with the 5 nights of the baseline period at 20 degrees C, sleep patterns showed disturbances at 35 degrees C. Total sleep time was significantly reduced, while the amount of wakefulness increased. The subjects exhibited fragmented sleep patterns. The mean duration of REM episodes was shorter at 35 degrees C than at 20 degrees C of Ta, while the REM cycle length shortened. In the acclimation period, there was no change in sleep pattern from night to night, despite adaptative adjustments of the thermoregulatory response. The protective mechanisms of deep body temperature occurring with heat adaptation did not interact with sleep processes. Upon return to baseline condition, a recovery effect was observed on a number of sleep parameters which were not significantly affected by the preceding exposure to prolonged heat. This would suggest that during exposure to dry heat, the demand for sleep could overcome that of other regulatory functions that are temperature-dependent. Therefore, a complete analysis of the effect of heat on sleep parameters can be assessed only if heat exposure is compared with both baseline and recovery periods.

Local sweating responses of different body areas in dehydration-hydration experiments.

Five subjects performed intermittent exercise on a bicycle ergometer (25 min work, 5 min rest cycles for 2 hours, and 20 min work, 10 min rest cycles for a further hour) in a hot environment (air and wall temperatures = 36 degrees C; dew-point temperature = 10 degrees C; air velocity = 0.6 m.s-1). The relative mechanical work load was of 70 W (30% of the maximal aerobic capacity). Seven experimental tests were carried out in order to induce a plasma hypovolemia associated with either a plasma hypo- or hyperosmolarity. The preexercise level of body hydration was also manipulated by giving a diuretic, or by ingestion of 500 ml of isotonic electrolyte sucrose solution before the start of exercise. Continuous measurements were made of rectal and mean skin temperatures. The sweating responses of the chest and of the thigh (over the active muscles of the leg) were monitored from 4 sweat collection capsules highly ventilated. On each of these body areas, the local skin temperatures under one of the 2 capsules was kept at a constant level (37 degrees C). The effects of the level of body hydration on the sweating response only appear when a high local thermal clamp is imposed beneath the capsule. This local effect is particularly strong over the active muscles of the thigh. The influence of the preexercise hydration appears during dehydration tests. This effect is not significant when fluid is given to the subject during the exercise. The change in the sensitivity of the thermoregulatory system is more strongly associated with plasma osmolarity than hypovolemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Thermoregulatory adjustments during continuous heat exposure.

Body temperature regulation was studied in 6 male subjects during an acclimation procedure involving uninterrupted heat exposure for 5 successive days and nights in a hot dry environment (ambient temperature = 35 degrees C, dew-point temperature = 7 degrees C; air velocity = 0.2 m.s-1). Data were obtained at rest and during exercise (relative mechanical workload = 35% VO2max). At rest, hourly measurements were made of oesophageal and 4 local skin temperatures, to allow the calculation of mean skin temperature, and of body motility and heart rate. During the working periods these measurements were made at 5 min intervals. Hourly whole-body weight loss was measured at rest on a sensitive platform scale while in the working condition just before starting and immediately after completing the bicycle exercise. The results show that, in both exercise and at rest, the successive heat exposures increased the sweat gland output during the first 3 days. Afterwards, sweat rate decreased without any corresponding change in body temperature. For the fixed workload, the sweat rate decline was associated with a decrease in circulatory strain. Adjustments in both sweating and circulatory mechanisms occur in the first 3 days of continuous heat exposure. The overall sweat rate decline could involve a redistribution of the regional sweating rates which enhances the sweat gland activities of skin areas with maximal evaporative efficiencies.

Effects of triazolam on heart rate level and on phasic cardiac response to noise during sleep.

The influence of triazolam on cardiac and respiratory activity of healthy male subjects was examined during nights disturbed by airplane noises and during undisturbed nights. Twenty-four subjects, divided into three groups of eight, slept in the laboratory for 7 nights (N0-N6). Following a double blind design, group A (control group) received a placebo every night. Group B received 0.25 mg triazolam and group C received 0.5 mg on nights N3, N4 and N5. On the other nights, they received a placebo. For all three groups, the nights N0, N3 and N5 were disturbed by 32 semi-randomly distributed airplane noises. Air and wall temperatures (20 degrees C) and air humidity (10 degrees C, 52%) were kept constant. Sleep measures, heart rate and respiratory rate were continuously recorded. Results showed that the largest dose of hypnotic drug produced an increase in tonic heart rate in the first part of each night throughout the treatment period (N3, N4, N5). When compared to baseline disturbed night N0, the phasic cardiac response to the noises was significantly attenuated on only the 1st treatment night (N3). Triazolam had no significant effect on nocturnal respiratory rate. No after-effects of the drug were observed for cardiac and respiratory activity on the withdrawal night (N6). The results suggest that, with regard to the drug action, there was either an increase in arousal threshold or a dissociation between long-lasting and short-lasting modifications of heart rate. Contrary to the single night attenuation of phasic cardiac responses, there was no drug tolerance for the hypnotic-related increase in tonic heart rate.

Sweating responses and body temperatures during nocturnal sleep in humans.

The changes in the central control of sweating were investigated in five sleeping subjects under neutral and warm conditions [operative temperature (To) = 30, 33, and 34 degrees C; dew-point temperature = 10 degrees C]. Esophageal (Tes) and mean skin (Tsk) temperatures, chest sweat rate (msw,1), and concomitant electroencephalographic data were recorded. Throughout the night, msw,1 was measured under a local thermal clamp of 38 degrees C. Results showed that the thermal environment exerted a strong influence on both the levels and the time patterns of body temperatures. Moreover, local sweating rate correlated positively with Tes, and this relationship varied according to sleep stages. For a given Tes level, there was a sleep stage-related gradation in msw,1 that was higher in slow-wave sleep (SWS) than in stage 1-2 and the lowest in rapid-eye-movement (REM) sleep. This is explained by a change in the excitability or the sensitivity of the thermoregulatory system. The msw,1 differences between stage 1-2 and SWS are accounted for by a decrease in the Tes threshold (Tset) for sweating while the slope of the msw,1-Tes relation remains unchanged. The lower msw,1 in REM sleep is explained by a lesser slope for the msw,1-Tes relation without any Tset change from stage 1-2.

Hydration during exercise. Effects on thermal and cardiovascular adjustments.

Five young unacclimatised subjects were exposed for 4 h at 34 degrees C (10 degrees C dew-point temperature and 0.6 m X s-1 air velocity), while exercising on a bicycle ergometer: 25 min work--5 min rest cycles for 2 hours followed by 20 min work--10 min rest cycles for two further hours. 5 experimental sessions were carried out: one without rehydration (NO FLUID) resulting in 3.1% mean loss of body weight (delta Mb), and four sessions with 20 degrees C fluid ingestion of spring water (WATER), hypotonic (HYPO), isotonic (ISO) and hypertonic (HYPER) solutions to study the effects of fluid osmolarity on rehydration. Mean final rehydration (+/- SE) after fluid intake was 82.2% (+/- 1.2). Heart rate was higher in NO FLUID while no difference among conditions was found in either delta Mb or hourly sweat rates. Sweating sensitivity was lowest in the dehydration condition, and highest in the WATER one. Modifications in plasma volume and osmolarity demonstrated that NO FLUID induced hyperosmotic hypovolemia, ISO rehydration rapidly led to plasma isoosmotic hypervolemia, while WATER led to slightly hypoosmotic normovolemia. It is concluded that adequate rehydration through ingestion of isotonic electrolyte-sucrose solution, although in quantities much smaller than evaporative heat loss, rapidly restored and expanded plasma volume. While osmolarity influenced sweating sensitivity, the plasma volume changes (delta PV) within the range -6% less than or equal to delta PV + 4% had little effect on temperature adjustments in our conditions.

Sweat gland response to local heating during sleep in man.

In order to assess whether the fluctuations in the sweating response occurring during sleep are related to changes in central drive or in peripheral sweat gland reactivity, 4 healthy male subjects spent 6 non-consecutive nights in a climatic chamber. Air temperature was 25 degrees C, dew-point temperature was 10 degrees C and air velocity was 0.3 m X s-1, while wall temperature was either 38 degrees C, 46 degrees C or 48.7 degrees C giving 3 levels of operative temperature (To = 30, 33 or 34 degrees C). During the whole night, 2 local sweating rates on the right and the left sides of the upper chest were continuously recorded from 12 cm2 area capsules using a dew-point hygrometer technique, while applying local thermal clamps, a constant 2 degrees C difference in local skin temperatures being imposed between the two symmetrical skin areas. Continuous measurements were made of rectal temperature, 10 local skin temperatures, 2 EEGs, 2 EOGs, 1 EMG and 1 ECG. Results show that the multiplicative relationship between the peripheral influence of local skin temperature and the central drive for sweating described in waking subjects, is still valid in sleeping subjects. No peripheral change appears in sweat gland reactivity between the different sleep stages. Changes in the sensitivity of the thermoregulatory system occurring during sleep cannot be explained by a local factor acting at the sweat gland level.

Temperature regulation during intermittent exercise with progressive dehydration.

Effects of dehydration (3% of initial body weight) on temperature regulation were investigated in 5 men during intermittent exercise of 4 h duration at a dry air temperature of 34 degrees C. Relative mechanical work load was 50% of the subject's steady state heart rate, which was 170 beats . min-1. During rehydration from the 70th min to the end of the exercise, the subjects drank, every 10 min in equal portions, an amount of water (20 degrees C) totaling up to 80% of the body weight loss recorded during dehydration runs. Continuous measurements were made of rectal (Tre) and mean skin (Tsk) temperatures and of whole body weight loss. Chest sweating rate (msw) was measured from a capsule located under a local thermal clamp (36 degrees C). Blood samples were obtained during rest periods and after the 1st and the 4th hour of exercise. Compared to dehydration runs, water intake did not always cause an increase of msw while body temperatures always decreased. Dehydration resulted in a decrease in plasma volume and in increases of plasma osmolality, [Na+] and [K+]. Water intake induced a thermoregulatory response whose intensity largely differs from one body area to another. The change in the slope of the relation of msw to Tre features a decrease in the sensitivity of the thermoregulatory system with dehydration. The whole body water loss is significantly correlated with the change in plasma volume and body temperatures (Tre, Tsk). This suggests that the reduced sweating response observed during dehydration can be related to plasma hypovolemia.