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At least 883 records · Page 49Linked to original sources
PubMed1985

Absence of refractoriness in asthmatic subjects after exercise with warm, humid inspirate.

Twelve asthmatic adults each completed two six minute treadmill runs separated by an interval of 20 minutes. Running speed was constant for each subject, and inspired air temperature averaged 5.5 degrees C (SD 1.5 degree) for both tests. Total minute ventilation and total respiratory heat loss showed no significant difference between the two runs. Forced expiratory volume in one second (FEV1) was measured before exercise and at five minute intervals throughout the recovery periods, during which subjects breathed room air at an average temperature of 17.8 degrees C (1.8 degree). Reduction in FEV1 from pre-exercise readings averaged 39.3% (13.3%) for the first run and 11.5% (7.3%) for the second. On another day the subjects underwent an identical procedure except that the first exercise period was performed with the saturated inspirate at 37.3 degrees C (1.7 degree). This run produced a mean FEV1 reduction of only 3.1% (7.3%). The ensuing run, during which the inspiratory temperature averaged 6.0 degrees C (2.0 degrees), led to a mean fall in FEV1 of 37.3% (17.3%). This was not significantly different from the value recorded for the first of the paired runs with cool air. We therefore have been unable to confirm that exercise with warm humid inspirate may induce refractoriness to exercise induced asthma. Our data are compatible with the theory that refractoriness may be due to depletion of mediators during an initial exercise induced asthma attack.

Asthma↗
PubMed1992

A mask to modify inspired air temperature and humidity and its effect on exercise induced asthma.

BACKGROUND: Heat and moisture loss from the respiratory tract during exercise are important triggers of exercise induced asthma. METHODS: A new heat and moisture exchange mask has been developed which both recovers exhaled heat and water and has a sufficiently low resistance for use during exercise. The effect of the mask on inspired air temperature was studied in four normal subjects. Eight asthmatic subjects performed identical exercise protocols on three separate days, breathing room air through a conventional mouthpiece, a dummy mask, and the new heat and moisture exchange mask. Seven different asthmatic subjects exercised while breathing cold air at -13 degrees C through a dummy or active mask. RESULTS: All subjects found the new mask comfortable to wear. The mean inspired temperature when the mask was used rose to 32.5 (1.4) degrees C when normal subjects breathed room air at 24 degrees C and to 19.1 (2.7) degrees C when they inhaled subfreezing air at -13 degrees C. The heat and moisture exchange mask significantly reduced the median fall in forced expiratory volume in one second (FEV1) after exercise to 13% (range 0-49%) when asthmatic subjects breathed room air compared with 33% (10-65%) with the dummy mask and 28% (21-70%) with the mouthpiece. The fall in FEV1 when the asthmatic subjects breathed cold air was 10% (0-26%) with the heat and moisture exchange mask compared with 22% (13-51%) with the dummy mask. CONCLUSION: Use of a heat and moisture exchange mask can raise the inspired temperature and humidity and ameliorate the severity of exercise induced asthma. The mask may be of practical value in non-contact sport or for people working in subzero temperatures.

Adolescent↗
PubMed1979

Plasma volume changes during rest and exercise in different postures in a hot humid environment.

Plasma volume shifts were investigated in five male subjects who rested and exercised in the upright, low-sit, and supine postures in a hot humid environment (49.5 degrees C, 28.9 Torr). The resting and exercise periods were each 45 min in duration. Weight losses during rest were 0.3% with an additional weight loss of 1.1% during exercise. During exercise subjects worked at either 360 or 540 kpm.min-1 in each of three postures. Each experiment was preceded by a 30-min control period in the supine posture at an ambient temperature of 22 degrees C. At rest plasma volume was reduced 17.3% in the upright, 9.0% in the low-sit, and 2.2% in the supine postures (using the end of the supine rest as the zero reference point). Supine exercise resulted in a plasma volume decrease of 11%, the low-sit 7.1%, and the upright 2.7%. The total reduction in plasma volume during the rest and exercise period was 20% in the upright, 16.1% in the low-sit, and 13.3% in the supine. No significant differences in plasma volume shifts were observed between the high and low work loads. The results indicate that the plasma volume shifts observed during rest and exercise in the heat are qualitatively similar to those observed in a cool environment.

Adult↗
PubMed1980

Thermoregulation during rest and exercise in different postures in a hot humid environment.

The time course of whole-body sweating and thermal regulation during rest and exercise in a hot humid environment was investigated in three body postures. After 45 min rest in the upright, low-sit, or supine posture, five unacclimatized men exercised for 45 min on a bicycle ergometer in the same posture in an environment of 49.5 degrees C, 28.9 Torr. Exercise was performed at two different work loads, corresponding to about 30 and 45% of VO2max. During exercise auditory canal temperature, rectal temperature, and mean skin temperature increased linearly being highest in the supine and lowest in the upright posture. Percentage of evaporated sweat from the skin to secreted sweat was 65% in upright, 52% in the low-sit, and only 46% in the supine posture during the last 20 min of exercise regardless of work load. The time course of the rate of body heat storage was different from predictions based on the thermal balance equation. Evaporative heat loss was not 100% effective in cooling the skin surface.

Adult↗
PubMed1979

Development of puberty in Large White boars in a humid tropical environment.

The development of puberty in Large White boars raised and maintained in a humid tropical environment was studied histologically and by a preputial smear technique. The growth curves for the testes, epididymides and body weight were similar and exhibited a spurt between the ages of 150 and 180 days. The accessory sex glands increased slowly but steadily until the animals were about 180 days old at which time a marked increase in their growth rate was noted. Thus from morphological and histological assessment, puberty in these animals was placed between 150 and 180 days. The preputial smear technique was successfully applied in the boar. By this method, the animals were found to be 165.74 days old at puberty and to weigh 51.65 kg. These results further indicate that the development of puberty is genetically controlled and also imply that this could be slightly modified by the environment.

Age Factors↗
PubMed1980

Genetic and sex influences on the histomorphometric characteristics of porcine adrenals under hot humid climatic condition.

Histomorphometric measurements of the adrenal glands of three straight-bred and two cross-bred lines of pigs maintained in hot humid climatic conditions showed that adrenal gland function is not affected by sex. Striking breed influences were however observed in the parameters studied. Paired absolute adrenal weight was higher in Large White (LW) pigs than in the others but the relative adrenal weight was similar and higher in LW, Landrace (LD), West African indigenous (WA) and two-way cross (2X) pigs than in three-way cross (3X) pigs. The adrenal cortex thickness was thinnest in WA pigs while the area of the cortical zone and the cortex/medulla ratio were respectively smaller in WA and 3X and WA and 2X pigs than in the others. Relative paired adrenal weight did not change during early pregnancy unlike the thickness and area of the cortex and the cortex/medulla ratio which were highly increased.

Adrenal Cortex↗
PubMed1981

Regional distribution of acetylcholinesterase activity in the brain and hypophyses of crossbred European boars reared in the humid tropics.

The distribution of acetylcholinesterase (AChE) activity in the brain and hypophyses of crossbred European boars that had been raised and maintained in the humid tropics was studied. AChE activity varied between brain and hypophyseal parts. Compared to results obtained from rats, the results of this study imply some evolutionary changes in the importance of the different brain parts with respect to the regulation of animal behaviour.

Acetylcholinesterase↗
PubMed1983

Genetic and sex influences on the regional distribution of acetylcholinesterase activity in the porcine brain and hypophyses under humid tropical climatic conditions.

The adaptability of one indigenous and four exotic breeds of pigs to the humid tropical climatic conditions of Ibadan was comparatively evaluated with acetylcholinesterase activity (AChE) of brain and hypophyseal parts as the parameter. Significant breed differences were observed in the weight and AChE of the hypophyses and in the AChE of the brain parts. With regard to sex, only the relative adenohypophyseal weight and the AChE of the cerebellum and medulla oblongata were influenced. The results demonstrate the greater adaptability of the indigenous pigs to their native environment than the exotic breeds. A reduced sensitivity to the various stressing factors of the indigenous pigs and the females was implied. Results also suggest that the Large White breed may be more suited to the conditions prevalent in Ibadan than the other exotic breeds.

Acetylcholinesterase↗
PubMed1978

Influence of heat and humidity on the airway obstruction induced by exercise in asthma.

We examined the degree of airway obstruction that developed in eight asthmatics who exercised while breathing air under four conditions: (a) ambient room temperature and water content; (b) body temperature and ambient water content; (c) ambient room temperature fully saturated; and (d) body temperature fully saturated. These test conditions were performed in random order. Multiple aspects of pulmonary mechanics were measured before and 5 min after exercise. When air at ambient conditions was inhaled, the expected airway obstruction developed after exercise, and all variables changes significantly from their pre-challenge values. Heating the air to body temperature did not influence this response. Increasing the humidity at ambient temperatures significantly blunted the response, and by inhaling body temperature, fully saturated air completely prevented it from occurring. Thus, the water content of inspired air is an important variable in the development of exercise induced asthma.

Adult↗
PubMed1981

Response of plasma prolactin to changes in ambient temperature and humidity in man.

The present study examined the relationship between plasma PRL and ambient temperature and relative humidity (RH) in man. Six normal men sat in an environmental room on four occasions. On each occasion, a thermoneutral control period at 27 C dry bulb (db)/16 C wer bulb (wb; 32% RH) was followed by a 90-min exposure to 27 C db/16 C wb, 13 C db/9 C wb, 45 C db/26 C wb, or 27 C db/26 C wb (92% RH) and a recovery period. Blood was drawn at 30-min intervals. Plasma PRL rose 53% (P < 0.05) in the heat and fell 37% (P < 0.05) in the cold in comparisons with control levels. No changes occurred during increased RH alone. Maximum PRL changes were associated with an increase in mean skin temperature of 3.0 C in the heat and a decrease of 4.3 C in the cold. Corresponding changes in auditory meatal temperature were +1.0 and -0.2 C, respectively. Plasma osmolality and serum Na+ and K+ levels did not change, except in the cold where serum K+ rose 0.6 meq/liter (P < 0.01). These data suggest an association between ambient temperature and plasma PRL in man which is not associated with changes in water and electrolyte status.

Adult↗
PubMed1998

[Study of skin temperature, microclimate and comfort of clothing of old females at rest--ambient temperature x humidity: 30 degrees C. R.H.80%, 30 degrees C. R.H.45%, 20 degrees C. R.H.45%].

Old females are compared to young females for the purpose of studying the difference in comfort caused by the environmental variables of temperature and humidity as well as the form of clothing. Eight experiments were performed in three settings: (a) 30 degrees C R.H.80%; 30 degrees C R.H.45%; and 20 degrees C R.H.45%. The ages of the subjects range from 62 to 68 (Mean = 65.17, S.D. = 1.68) among old females and from 20 to 23 (Mean = 20.83, S.D. = 0.76) among young females. The following results were obtained: (1) The young females were sensitive to hot temperatures, while the old females were not. On the other hand, the old females were more sensitive to cold temperatures, under 20 degrees C R.H.45%, than the young females. In temperatures under 30 degrees C R.H.80%, the heat radiation from the young females was higher than that of the old females. Under 20 degrees C R.H.45%, the heat radiation from the old females was higher than from the young females. The old females are thought to decline in physiogenic function due to enduring both hot and cold temperatures. (2) The correlation between the temperature in clothes and comfort among the old females is not different from the same correlation among the young females. This conclusion agrees with previously published studies of the young females. (3) Skin temperature and bloodstream are measured, according to clothing form. As a result, a long skirt is the highest in thermal insulation, long pants the next highest, and a short skirt is the lowest. (4) The effect of thermal insulation provided by a lap robe was tested in both groups. The lap robe was found to be more effective for the older group than the younger in temperatures under 20 degrees C R.H.45%. Hence, the role of clothes in offsetting for the decline in the thermoregulation function that compensates for environmental change is more important for old females than for young.

Aged↗
PubMed2003

Adverse environmental health effects of ultra-low relative humidity indoor air.

In Japan, relative humidity (RH) shows the lowest achievement rate among the various general air quality standards for work environment. It has been mainly contributed by airtight design of modern buildings and occurrence of dry outdoor air in winter. Furthermore, an ultra-dry air environment of nearly 0% RH is often required in sophisticated industries. In order to assess the adverse health effects of the ultra-dry air environment, using a self-reported questionnaire, we have undertaken a study of over 200 employees of a high-tech device developing laboratory having a room at 2.5% RH (ultra-dry room). Those who worked in the ultra-dry room were identified and the prevalence of symptoms was compared with the other workers. Analysis was performed by Wilcoxon's test and Fisher's exact test. In the ultra-dry room, all the twelve workers covered their skin with long-sleeve clothes, paper caps, paper masks and latex gloves. They reported skin symptoms more often (p<0.05) than the other workers (N=143). The prevalence of atopic dermatitis was also higher in the exposed workers (p<0.05). The complaints of workers in the ultra-dry environment were similar to preceding reports concerning moderately dry environmental exposures. The current precautions to protect the workers from the adverse effects of ultra-low RH appear to be insufficient, indicating that additional measures such as selection of appropriate clothing to mere skin coverage should be considered.

Cross-Sectional Studies↗
PubMed2002

Photoreduction of bacteriorhodopsin Schiff base at low humidity. A study with C13=C14 nonisomerizable artificial pigments.

The retinal protonated Schiff base of bacteriorhodopsin is photoreactive to reducing agents such as NaBH4. In the present work we have studied the effect of different protein hydration levels on the photoreductive reaction, as well as the consequences of preventing isomerization around the critical C13=C14 retinal double bond. It was revealed that the rate of light-induced NaBH4 reaction can be fitted to three phases, between 100 and 87%, from 87 to 35% and below 35% relative humidities (r.h.). The three phases are attributed to three protein regions characterized by different water affinities. Furthermore, it is shown that the PSB reduction reaction is light catalyzed even in artificial pigments derived from retinal analogs, in which isomerization around the C13=C14 double bond is prevented. It is suggested that the protein experiences light-induced conformational alterations that are not associated with C13=C14 double bond isomerization. In the 13-cis locked pigment the rate of reduction reaction is affected by r.h. levels only below 35%. The relatively low r.h. required for withdrawing water from the protein is attributed to the increased protein-water affinity in this specific pigment.

Bacteriorhodopsins↗
PubMedDate not supplied

[Items sterilized in humid heat: validation of the storage system].

We aimed at identifying the period of validity of the sterilization of items by humid heat, taking into account the conditions of sterilization and storage. The validation was carried out by means of microbiological tests performed with instruments in the same load and evaluated in 0, 7, 10, 15, and 25 days. 30% of the instruments in each package were analysed and put in a Mueller Hinton solution and incubated at 37 degrees C for 72 hours. The reading was accomplished taking into consideration how dark the solution was. Out of the samples evaluated in nine loads, none showed microbiological growth. It was concluded that, although sterilization and storage conditions of the material were not fully in accordance with parameters recommended by the literature, the sterilization happened and was maintained for a period of 25 days.

Hot Temperature↗
PubMedDate not supplied

The influence of humidity on the residual action of benzene hexachloride (BHC).

In controlled humidity chambers in the laboratory differences in the absorption velocity of BHC were observed depending on the substrate sprayed. While BHC is no longer used in Chagas' disease control this data could have relevance to spraying houses in a control programme with other insecticides.

Hexachlorocyclohexane↗
PubMedDate not supplied

[Influence of the temperature and humidity on the biology of Rhodnius neglectus Lent, 1954, in laboratory conditions (Hemiptera, Reduviidae, Triatominae)].

The objective of the present paper was to study the development of R. neglectus in the laboratory under different conditions of temperature and humidity. Three groups were prepared: 33/40 (33+/- 1 degree C and 40% +/-5% UR), 33/70 (33+/- 1 degree C and 70% +/-5% UR), and 28/70 (28+/- 1 degree C and 70% +/-5% UR). All these groups were observed daily to evaluate the eggs' incubation period, the development period of each instar nymph, the mortality rate of each stage, the frequency of feeding and the hatching - adult ecdysis period. The embryonic development showed significant differences between the treatment given, the group 33/40 presented the lowest incubation period. The lowest bloodmeals number was observed in the group 33/40 except for the first instar (group 28/70). The period of nymphal development was significantly reduced in the group 33/40, however, the mortality was high and the specimens did not reach the adult phase.

Animals↗
PubMed1996

Effects of carbon dioxides and/or relative humidity on the growth and the transpiration of several plants.

In order to estimate the effects of "global warming" on plants, the effects of carbon dioxide concentration (500 ppm or 1000 ppm CO2) and/or relative humidity (37% or 79% RH) on the growth and the transpiration of several C3 plants and a C4 plant (corn) were investigated by using artificially-lighted growth cabinets. The dry weight growths of all species, especially C3 plants, were accelerated by an elevated concentration of CO2, but were reduced, especially tomato and eggplant, by lowering RH. The leaf area growths of tomato and eggplant were accelerated by a high CO2, while those of all species were reduced by a low RH. A high CO2 increased net assimilation rates (NARs) more than relative growth rates (RGRs) of all species. It decreased leaf area ratio (LAR) due to a decrease in specific leaf area (SLA). A low RH decreased RGRs of all plants. while it affected NARs or LARs of some species. The partitioning of dry matter was insignificantly affected by CO2 or RH. Effects of CO2 on the transpiration rate were not observed clearly with C3 species, though a high CO2 decreased the transpiration of corn obviously. A low RH increased the transpiration rates of all species. From these results, the water use efficiencies of many plants, especially corn were kept at a high level by a high CO2 with a high RH condition. The interactive effects between CO2 and RH on the growth and the transpiration were insignificantly observed in these plants.

Biomass↗