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At least 1,171 records · Page 65Linked to original sources
PubMed1977

Effects of a heatwave on mortality-rates in elderly inpatients.

The relation between the number of in-patient deaths occurring in a department of geriatric medicine and external air temperatures recorded during the heatwave of 1976 in the U.K. was investigated. There was a close correlation between the mortality-rate and the weekly average of peak daily temperatures. There was less of an increase in mortality among the elderly patients in the better insulated buildings. The total number of deaths among elderly patients increased threefold during the hottest period of the heat-wave. These results suggest that measures may need to be taken in the elderly to combat the harmful effects of heatwaves.

Age Factors↗
PubMed1997

Computer analysis of environmental temperature, light and noise in intensive care: chaos or chronome nurseries?

Lighting, noise and temperature were monitored in two perinatal nurseries. Rhythms of several frequencies were found, including prominent 24-hour rhythms with acrophases around 13:00 (light intensity) and 16:00 (noise). For light and noise, the ratio formed by dividing the amplitude of a 1-week (circaseptan) or half-week (circasemiseptan) fitted cosine curve by the amplitude of a 24-hour fitted cosine curve is smaller than unity, since 24-hour rhythms are prominent for these variables. The amplitude ratios are larger than unity for temperature in the newborns' unit but not in the infants' unit. Earlier, the origin of the about-7-day rhythms of neonatal physiologic variables was demonstrated to have, in addition to a major endogenous, also a minor exogenous component. Hence, the possibility of optimizing maturation by manipulating environmental changes can be considered, using, as gauges of development, previously mapped chronomes (time structures of biologic multifrequency rhythms, trends and noise).

Circadian Rhythm↗
PubMed2001

Antioxidant status and stress resistance in long- and short-lived lines of Drosophila melanogaster.

The purpose of this study was to understand the nature of the biochemical and physiological variations between genetically different lines of Drosophila melanogaster. Selection for early or delayed reproduction has given rise to lines with substantial and heritable differences in longevity. The hypotheses tested were that either: (i) a compensatory slowing of metabolism, (ii) increased antioxidative enzyme activities, or (iii) elevated resistance to stressful conditions underlie these differences in longevity. The metabolic rate, metabolic potential (i.e. total amount of oxygen consumed during average lifespan) and speed of walking were all greater in long-lived than in short-lived flies, but there was no enhancement of antioxidant defenses. In fact, catalase activity was significantly lower in the long-lived flies. Long life was largely maintained under heat stress and starvation conditions, and was maintained to a lesser extent upon exposure to paraquat, a superoxide radical generator. In contrast, the 'short-lived' flies had a longer lifespan under cold stress and hyperoxia, also an inducer of radical generation. These results contradict the first two hypotheses and suggest that alleles underlying either long or short life are linked with enhanced resistance to specific kinds of stress, which may account for the preservation of these alleles in the parental population.

Animals↗
PubMed1990

Environmental effects on thermoregulation and nutrition of horses.

Horses are reared in all types of weather. Temperatures as diverse as -40 degrees C to 40 degrees C are tolerated by horses. The nutrient requirement most influenced by cold weather is energy. In cold weather, feeding good quality hays free-choice is usually sufficient for mature horses in good body condition. Grain may have to be fed when poor quality hays are used. Hot weather (greater than 30 degrees C) necessitates heat loss to maintain body core temperature. Horses sweat to reduce body heat. Heat stress can be minimized by feeding diets that reduce the heat increment. Use of grain and fat in the diet, which have a lower heat increment than fibrous feeds such as hays, may benefit horses in hot climates. Wind or precipitation necessitate protection to minimize chilling in cold weather and discomfort in hot weather. However, it is a moot point whether horses will use shelters under these circumstances.

Animal Nutritional Physiological Phenomena↗
PubMed2001

Theoretical foundation for a simple method for simultaneous measurements of the unattached fraction and activity median diameter of attached radon progeny.

Calculation of lung dose from established lung dosimetry models requires use of the unattached fraction of potential alpha energy concentration (PAEC) of radon progeny and the activity median diameter (AMD) of attached radon progeny, in addition to the total PAEC. In the present work, for indoor environments without the nucleation mode of aerosols, a method based on the wire screen penetration theory using two wire screens and a filter is proposed for simultaneous measurements of these two parameters. It is shown that the traditional wire screen method can overestimate or sometimes underestimate the unattached fraction, depending on the properties of the wire screen and the true unattached fraction. The present method eliminates such uncertainties.

Alpha Particles↗
PubMed1998

Preliminary study of dose equivalent evaluation for residents in radioactivity contaminated rebar buildings.

It has recently been found that several resident and office buildings in Taiwan were constructed with 60Co-contaminated reinforcing steel bar (rebar). Both governmental officials and the residents of such buildings have been concerned about this finding. In order to respond to the situation, the government has adopted a number of remedial measures, including full-scale radiation survey, dose evaluation and physical examinations of residents. This article presents three methods for evaluating the dose equivalents of the residents living in the contaminated rebar buildings by means of gamma-ray survey, necklace-type thermoluminescence dosimeters (TLDs) and the human lymphocyte chromosome aberration analyses. The results reveal that the dose evaluation by gamma-ray survey is rather conservative. Generally for the residents whose annual dose equivalents are greater than 5 mSv (0.5 rem) by gamma-ray survey, the dose equivalents from necklace-type TLDs are only within the range of 20 to 50% of the evaluated values mentioned above. For chromosome analyses, at least 500 lymphocyte cells were scored and analyzed for each resident. Most of the chromosome analysis data show that the dose equivalents received by residents are lower than the detection limit of the method (100 mSv) and quite different from the estimated dose obtained from either gamma-ray survey or necklace-type TLD measurements.

Air Pollution, Indoor↗
PubMed1998

Active measurements of indoor concentrations of radon and thoron gas using charcoal canisters.

Standardized charcoal canisters with diameters of 4 inch, of a type recommended by the USEPA for passive measurement of radon gas concentrations, have been modified for active air sampling. Simultaneous measurement of the concentrations of radon (Rn) and thoron (Tn) in air can be obtained by counting the areas under gamma-ray peaks. Sample results obtained in a laboratory and in a residence with different conditions are also given. The largest uncertainties are about 2% and 3% for Rn and Tn respectively. The minimum detection limits are around 2.0 Bq/m3 for both gases. If only Rn concentration is required, the measurement time can be significantly shortened.

Air Pollution, Indoor↗
PubMed1998

Measurement of equilibrium factor and unattached fraction of radon progeny in Kaohsiung, Taiwan.

To reasonably estimate the population dose from radon, equilibrium factor, Fp, and unattached fraction, fp, of radon progeny are important parameters. A Lucas cell and a working level monitor was used for most Fp measurement. The unattached fraction was measured by SARAD EQF3020. A detached house was chosen to measure the Fp in different rooms. The Fp value depended mainly on the ventilation rate and surface to volume ratio of the rooms. Fp and fp were measured in bedrooms of 14 other dwellings. Two hospitals were also chosen for measurement of Fp in the working place using rooms located in the basement. The average Fp for dwellings was about 0.5 and the average unattached fraction was about 0.055. The radon levels in the hospitals were higher than those in the dwellings but the equilibrium factors in the hospital were very low (about 0.06). The low Fp was attributed to the use of a dehumidifier in the hospitals. Dehumidifiers are popular for reducing fungi problem induced by the high humidity in Taiwan.

Air Pollution, Indoor↗
PubMed2004

Protocols for simulating the thermal component of fever: preclinical and clinical experience.

An increase in body temperature in association with inflammation or infection has been evolutionarily conserved in all cold and warm-blooded vertebrates and even in several invertebrates thus far examined. This change in temperature is strongly correlated with survival from infection in many animal models. Although the means by which body temperature is increased and maintained differs between cold- versus warm-blooded species, there are strong similarities in terms of the magnitude of temperature change and its duration. Despite these intriguing observations and significant biological sequelae, temperature manipulation is rarely considered in the context of most experimental immunological investigations. We have hypothesized that the thermal microenvironment plays a critical role in regulating events in the immune response and that an increase in ambient temperature can serve as a natural trigger or "danger signal" to the immune system. To examine the direct effects of fever-like temperatures on immunological parameters, we have designed and characterized protocols for performing whole body heating of mice and humans in vivo, and heating of cultured cells in vitro. Our studies have now progressed to the development of therapeutic uses of fever-range hyperthermia in combination with other therapies. This chapter describes the experimental procedures that have been developed for these studies and summarizes several of the immunologically relevant effects that we have noticed following mild heat treatments in vivo and in vitro.

Animals↗
PubMed2003

The effect of modified atmospheres on the survival of the eggs of four storage mite species.

The results of a laboratory investigation into the effects of modified atmospheres (MA) on the eggs of mite pests of grain and cheese are presented. Four species of astigmatid mite were tested; Acarus farris (Oudemans). A. siro L., Lepidoglyphus destructor (Schrank) and Tyrophagus longior (Gervais). All are found in many habitats including grain and cheese stores. Three low oxygen (O2) MA mixtures were used, based on carbon dioxide (CO2), nitrogen (N2) or simulated burner gas (0.5 or 2% O2, 10% CO2, balance N2) plus 60% CO2 in air (8% O2). The mites were exposed at 15 degrees C and 80% r.h., a combination of conditions that occurs at the surface of stored grain during the autumn which promotes mite population growth. The exposure periods required to prevent egg hatch for each species in every mixture are given. Tyrophagus longior was the most tolerant species, followed by A. siro and A. farris, with L. destructor the most susceptible. Burner gas was the most effective mixture overall with 0.5% O2 but with an increase in the O2 level to 2% for all the mixtures, CO2 became the more effective control agent. With 60% CO2 in air some loss of efficacy was observed against the three most tolerant species and even more so for L. destructor. Sublethal exposures to MAs for at least 4 days in L. destructor, 6 days in A. farris and A. siro and 8 days for T. longior caused a delay in egg hatch.

Animals↗
PubMed2003

Predictive validity of discriminant analysis for genetic data.

We examined the predictive validity of the results using discriminant analysis to distinguish statistically among two or more populations with a large sample of random amplified polymorphic DNA (RAPD) loci, but a small sample of genotypes from each population. We compared and contrasted results from randomized data with results from real data of three studies by 100 randomized shuffling of genotypes into various populations. We generally obtained substantial differences between results from randomized data compared to those from the real data in several characteristics of discriminant analysis. We showed that a high level of correctly classified percentage is also obtainable in the analysis of randomized data, mainly with a low number of populations. However, the correctly classified percentage obtained from the real data was generally significantly higher than the percentage obtained from the randomized data. We suggested that the high level of real differences in allele frequencies of the RAPD polymorphic loci clearly distinguished the various populations and that the populations differ significantly in their RAPD contents in accordance with ecological heterogeneity. We obtained either no or a low level of difference between the correct classification rate obtained by the leaving-one-out procedure and that obtained from the original data, attributed to a low number of loci selected by the stepwise method. The results strengthen and support our conclusion and lead us to focus on the discriminant analysis by selecting only low numbers of discriminating variables.

Discriminant Analysis↗
PubMed1989

Microgeographic variation in rDNA intergenic spacers of Anopheles gambiae in western Kenya.

The genetic population structure of Anopheles gambiae (Diptera: Culicidae) in western Kenya was investigated by hybridizing a rapidly evolving rDNA intergenic spacer sequence to restriction endonuclease digests of genomic DNA extracted from single mosquitoes from seven localities. Significantly different distributions of restriction fragment arrays were obtained from field sites less than 10 km apart, which suggests restricted gene flow and a subdivided population structure. Eight of twenty-one possible comparisons between pairs of populations yielded significant differences. An eastern Kenya coastal population did not share its restriction fragment arrays with any of the western populations, suggesting that isolation by distance can be complete on a relatively small geographic scale (700 km).

Animals↗
PubMed2006

Adaptive differentiation of thermotolerance in Drosophila along a microclimatic gradient.

We examined whether a remarkable occurrence - the physiological evolution of two Drosophila melanogaster populations, despite a spatial separation of only 100-400 m, was idiosyncratic and temporary, or persisted over multiple years. We ascertained the high-temperature tolerance of Drosophila descended from populations on the north-facing slope (NFS) and south-facing slope (SFS) of 'Evolution Canyon' (Lower Nahal Oren, Mt Carmel, Israel), which were collected in 1997, 1999, and 2000. Results for these Drosophila uniformly resembled other studies in many respects: an inverse relationship between survival and heat-shock temperature, male-female differences in thermotolerance, and inducible thermotolerance. Importantly, for all years of collection, SFS flies consistently exceeded NFS flies in basal and inducible thermotolerance after diverse heat shocks, with and without thermal pretreatment, and whether isofemale lines, synthetic populations, or inbred lines were compared. Inbred lines, however, had lower thermotolerance than outbred lines. Several nonexclusive processes may explain the evolution of such physiological differentiation.

Acclimatization↗
PubMed2003

["Breathing freely" in schools--results and model approaches concerning the air quality in classrooms].

Seven schools in Lower Saxony participated in a scientific re-search project measuring the concentration of carbon dioxide (CO2), indoor air temperatures and the relative air humidity in naturally ventilated classrooms on 58 days during the period of one year. The results are as follows: The hygienic reference value of 1500 ppm CO2 (in accordance with the official German regulation DIN 1946-2) was exceeded on 7 days in summer when measurements were taken (32% of all samples in summer) and on 32 days in winter (89% of all samples in winter). The mean CO2-concentration was 1316 ppm, 766 ppm and 1652 ppm in all samples (58 measuring days), summer samples (22 measuring days) and winter samples (36 measuring days), respectively. The mean indoor air temperature was 21.7 degrees C, 22.9 degrees C and 20.9 degrees C. The mean relative humidity was 50.7%, 54.3% and 48.5%. The mean number of persons per classroom (including the teacher) was 25.1, corresponding to a mean volume of 8.5 m3 for each person and a mean area of 2.9 m2 per person. A statistical association of CO2 concentration with season, outdoor temperature and the age of the windows was found. A software programme has been developed for calculating the concentration of CO2 depending on the number of persons and the ventilation rate in a classroom. A 3-level scheme based on CO2 concentration was developed to assess the air quality. The results showed that the classrooms were not ventilated regularly but depending on the outdoor temperature and the season. Deficits concerning all 3 parameters were found. It is very likely that the deficits are not limited to the schools participating in this project. Ventilation and indoor climate deficits might cause health problems and therefore lead to costly measurement programmes. To enable schools to take their own health-related measurements, measuring instruments were purchased which can be loaned to schools in Lower Saxony.

Air Pollution, Indoor↗