SEARCH · PubMed Health

Results for “Humidity”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 703 records · Page 39Linked to original sources

PubMedDate not supplied

[Infusion pre-hydration and a humid room in the prevention of postoperative adhesions].

The Authors after an overview on the most important causes of postsurgical adhesions, drove their attention to the tissue injury determined, during abdominal surgery, by exposure of pelvic serosa to the humidity of operating area. The AA tested body temperature in the Douglas pouch and under the liver on 30 patients who were operated by conservative surgery (myomectomy) and on 8 patient who underwent laparoscopy. A decrease of one degree in the Douglas pouch after one hour on the patient who had a Pfannestiel incision has been detected. While on the patients with longitudinal laparotomy no difference was evidenced. Serosal biopsies done at the beginning of surgery after pelvis exposure to the external conditions (temperature, humidity) showed a marked phlogosis in the tissue of the patients not treated at all. These tissue injuries were almost absent in the group treated with saline tissue irrigation and absent in the group that had parenteral prehydration, too. The AA suggested the use of the two techniques in conservative surgery in order to obtain in the open abdomen surgery results similar to those of the endoscopic one.

Body Temperature↗

PubMed1995

Clinical observations made in nonheat acclimated horses performing treadmill exercise in cool (20 degrees C/40%RH), hot, dry (30 degrees C/40%RH) or hot, humid (30 degrees C/80%RH) conditions.

Four horses (H, J, N and M) undertook a treadmill competition exercise test (CET), designed to simulate the physiological and metabolic stresses of the Speed and Endurance phase of a 3-day-event, under 3 different environmental conditions: 20 degrees C/40% relative humidity (RH) (cool, dry [CD]: 2 sessions); 30 degrees C/40%RH (hot, dry [HD]) and 30 degrees C/80%RH (hot, humid [HH]) (Marlin et al. 1995). A number of subjective clinical observations were made at designated time points throughout the exercise test and initial recovery period including buccal mucous membrane colouration, capillary refill time, neck and point of shoulder skin pinch recovery time, grade of abdominal sounds; anal sphincter tone as well as the presence or absence of fatigue and ataxia. The aim was to investigate their value in predicting performance in the final canter phase of the CET equivalent to the cross-country or Phase D of a field competition. In addition, the use of a more objective assessment, the cardiac recovery index (CRI), was investigated together with the heart rate, rectal temperature and respiratory frequency at the end of Phase C and at the 8 min point of the 10 Minute Box (8'X). The CRI was calculated according to the formula CRI = P2-P1 where P2 = the heart rate in beats/min at the 8 min point of the '10 Minute Box' (Phase X) of the CET. P1 = the heart rate (beats/min) at the 7 min point just before the horse was made to trot over a distance of 80 m at a speed of 3.7 m/s (at a 3 degrees incline) before returning to a walk. The study suggested that the subjective tests carried out at the 'End-C' and/or '8'X' time points were not useful in predicting subsequent performance in the final canter phase (Phase D) and neither were heart rate, rectal temperature or respiratory frequency. However, the only horse (Horse H) to complete the full CET under HH conditions was the only animal to show a decrease in respiratory frequency between the End-C and 8'X time points. All others showed an obvious increase. Under HH conditions, Horse H also had the lowest CRI. For 3 of the horses the highest CRI value was found under the HH conditions, for the fourth horse an equally high CRI value was found with one of the CD sessions. However, under the HH conditions, both P1 and P2 values were > 100. The study suggested that it could be beneficial if a suitably modified CRI test, as well as a procedure to monitor the change in respiratory frequency during the 10 Minute Box, were evaluated further on the treadmill and in the field with respect to their potential usefulness as additional aids to the assessment of a horse's suitability to proceed to Phase D.

Acclimatization↗

PubMed1995

Electrolyte and total protein changes in nonheat acclimated horses performing treadmill exercise in cool (20 degrees C/40%RH), hot, dry (30 degrees C/40%RH) or hot, humid (30 degrees C/80%RH) conditions.

Four horses (H, J, N and M) undertook a simulated competition exercise test (CET), designed to simulate physiological and metabolic stresses of the Speed and Endurance (S & E) test of a 3-day-event, under 3 different environmental conditions: 20 degrees C/40% relative humidity (RH) (cool, dry [CD] 2 sessions); 30 degrees C/40% RH (hot, dry [HD]) and 30 degrees C/80% RH (hot, humid [HH]) (Marlin et al. 1995a). Venous blood samples for electrolyte and total protein (TP) determinations were collected from indwelling catheters at predetermined time points throughout each CET and initial 30 min recovery period. Venous blood samples were collected by jugular venepuncture at 2 h and 24 h after the end of the final 8 min canter (Phase D). The effects of exercise, environmental condition and horse on venous TP, sodium (Na+), potassium (K+), chloride (Cl-), calcium (Ca2+), magnesium (Mg2+) and phosphate (PO4(3-)) plasma concentrations were investigated. In addition, the effect of environmental condition on estimated cation loss was evaluated. All horses completed the full CET under the CD and HD conditions, but only one horse completed the full 8 min of the final canter Phase D under HH conditions. Exercise had a significant (P < 0.05) effect on all parameters similar to those reported previously in field competitions. There was a significant (P < 0.05) interaction between time and horse for TP, Na+ and Cl-. Overall, the environmental condition had a significant (P < 0.05) effect on all parameters, but the differences were not considered to be of any physiological relevance, other than for Cl- and TP. There was a significant (P < 0.05) interaction between time and environmental condition for Cl- and TP only. During much of the CET and recovery period, mean Cl- values were higher with the first CD session than the second CD session or under the HH or HD conditions. For TP after 2 min of Phase D and during the initial recovery period, concentrations were higher under the HH conditions and returned to the Pre- values less quickly. There were marked individual variations in the estimated cation losses and no consistent effect of environmental condition was found. Although estimated fluid loss was similar following both HD and HH sessions, restoration of bodyweight was slower following the CET studies under HH conditions.

Acclimatization↗

PubMed1977

Histological features of respiratory epithelium of calves held at differing temperature and humidity.

The effect of ambient temperature and humidity on the structure of respiratory epithelium of calves was studied. Four calves of each of three experiments were acclimatized to a nonoperational environmental chamber for six days and then exposed to constant extremes of temperatures and relative humidity of one of 30 degrees C --35%, or 27 degrees C--92%, or 5 degrees C--92% respectively in this chamber for eight days each. Five calves (3 and 2) were similarly acclimatized then exposed to 1 degrees C--40%. Nasal swabs were taken from all animals at regular intervals. Swabs of three animals yielded Mycoplasma spp. and one swab yielded the virus of infectious bovine rhinotracheitis. Detailed histological studies of respiratory epithelium of nose, trachea, major bronchus and terminal bronchioli were conducted at four sites. Goblet cells were least in calves held in hot and dry air; calves held in dry air had the least polymorphonuclear cells and the greatest prevalence of hypochromatic cell layers and vacuolation of epithelial cells. Differences between experiments were evident most for sites of trachea and major bronchus.

Animals↗

PubMed1976

[Changes in the tryptophan content in the body of layers under the effect of an environmental temperature-humidity regimen].

Experiments were carried out with a total of 60 layers of the White Plymouth Rock breed acclimatized to a temperature regime of 15 degrees C and a relative air humidity of 60 per cent and raised under zoohygiene conditions that met the requirements of the industrial technology for the production of eggs. The following temperature and moisture regimes of the air were tested in the course of seven days in a climatic chamber of the Zootron type: I--20 degrees C and 70 per cent; II--24 degrees C and 70 per cent; III--28 degrees C and 50 per cent; and IV--33 degrees C and 50 per cent. The birds of the control group were kept at 15 degrees C and 60-70 per cent relative air humidity. At the end of the first 24-hour period and the end of the seventh 24-hour period the birds were killed after a 12-hour starvation regime in order to determine the tryptophane content in the liver, blood serum, and heart muscle. It was found that under the Ist and IInd regime the amount of tryptophane in the organs studied was higher. The third and fourth regimes led to a dependable decrease in the content of tryptophane in these organs.

Animals↗

PubMedDate not supplied

Composite bonding to dentin and enamel: effect of humidity.

The effect of oral ambient air on shear strength to etched enamel and dentin was determined for OptiBond FL (Kerr Corp., Orange, CA) and Prodigy resin composite (Kerr Corp.). Enamel and dentin specimens of extracted human teeth were treated both in a dry environment and after exposure to oral humidity according to manufacturer's instructions. Shear strengths of this system are 22.6 MPa for etched, dry enamel; 22.2 MPa for etched, wet enamel; and 18.4 MPa for etched, dry or wet dentin. Differences in shear strengths between the wet and dry enamel or the wet and dry dentin were not significant. Multiple Student's t-tests were used for statistical analysis. Fracture modes for all specimens were examined under a stereomicroscope. Within the parameters of this in vitro study, OptiBond FL was not affected by oral humidity.

Composite Resins↗

PubMed1991

Behavioral thermoregulation of the toad, Bufo marinus: effects of air humidity.

Two experiments were performed. The first tested the hypothesis that the toad, Bufo marinus, will select a lower ambient temperature under dry environmental conditions. This behavioral response would reduce evaporative water loss and facilitate survival on land. The second experiment measured the effects of temperature on evaporative water loss. In the first experiment, toads were placed in a thermal gradient (11-40 degrees C) for 3 days. On days 1 and 3, water-filled dishes were placed along the temperature gradient and humid air was circulated through the chamber. On day 2, water dishes were removed, and dry air was circulated through the chamber. Body temperature (Tb) was recorded with a cloacal thermistor. Selected Tb was approximately 8.6 degrees C lower during the dry conditions than during the humid conditions. The behavioral hypothermia took about 6 h to develop. In the second experiment, a reduction in Tb from 17.7 to 12 degrees C reduced evaporative water loss by 42%. Consequently, behavioral hypothermia of the toad is an important adaptation to dry environmental conditions.

Animals↗

PubMed1996

Germination and Viability of Capilliconidia of Neozygites floridana (Zygomycetes: Entomophthorales) under Constant Temperature, Humidity, and Light Conditions

The germination of capilliconidia of Neozygites floridana on the cassava green mite, Mononychellus tanajoa, and the viability of these conidia collected on glass coverslips were studied at different temperatures, humidities (expressed as saturation deficit (SD), measured in mg Hg), and light conditions. Germination began within 2 hr of their attachment to the mites, at which time more than 66.0% of the conidia maintained at between 18 and 28°C, at SDs 0 and 0.2, and in the dark produced germ tubes. Percent germination pooled across all factors significantly increased from 15.7% after 2 hr to 28.2% after 6 hr and 45.0% after 14 hr. Germination at the extreme temperatures tested, 24.5% at 13°C and 14.8% at 33°C, was significantly lower than 40.0, 47.2, and 36.5% recorded at 18, 23, and 28°C, respectively. Percent germination increased with increasing humidity from 2.8% at SD 1.2 to 60.9% at SD 0. Although germination was observed when both light and dark conditions were tested, the 44.9% germination recorded under continuous darkness after 6 hr was significantly higher than 20.3% under continuous light. Rate of germination of capilliconidia declined with increasing storage time from 93.0% before storage to a pooled mean of 81.0% after 1 day and 3.5% after 10 days. Higher germination rates were maintained at lower temperatures. Whereas germination after 7 days did not exceed 8.0% at 28 and 33°C, it was 85.9 at SD 10 in the dark at 18°C. Germination at SD 10 was significantly higher (43.3%) than at SDs 6, 2, and 0 (between 31.34 and 34.95%). Continuous light reduced viability as an average of 47.1% of the conidia maintained in the dark germinated, compared to 23.5% of those in the light.

Journal Article↗

PubMed1996

Production and Germination of Primary Conidia of Neozygites floridana (Zygomycetes: Entomophthorales) under Constant Temperatures, Humidities, and Photoperiods

The production and germination of primary conidia of Neozygites floridana as affected by temperature, humidity, and photoperiod was studied in the laboratory. All tested factors significantly affected the two processes studied. Production increased with increasing temperature between 13 and 23°C, with means of 35.5 and 55.4 conidia, respectively, discharged from each mummified mite cadaver. No conidia were produced at 28 or 33°C. Conidial production dropped significantly from 96.1/mummy in a moisture-saturated environment [saturation deficit (SD) 0] to 33.9/mummy at SD 0.2. Very few conidia were produced at SD 0.7 (0.6/mummy) and none at SD 1.2. Significantly fewer conidia were produced under continuous light (11.2/mummy) than under continuous darkness (40.1/mummy) or 12L:12D (46.7/mummy) photoperiods. Between 82 and 100% of the conidia produced under 12L:12D photoperiod were released in the dark phase. Germination of primary conidia started within 2 hr and increased with decreasing temperature between 13 and 28°C. Percentage germination of 20.1% at 13°C and 17.6% at 18°C was significantly higher than 11.2% at 28°C. There was no germination at 33°C. High humidities (>95%) were necessary to effect germination. Germination at SD 0 (27.2%) and 0.2 (23.4%) was significantly higher than at SD 0.7 (0.4%), where germination began after 6 hr and was observed only at 13, 18, and 23°C. No germination was observed at SD 1.2. There was no germination among conidia maintained under continuous light.

Journal Article↗

PubMed1992

Genetic and environmental variation in reproductive and lactational performance of Jersey cattle in the coastal lowland semi-humid tropics.

Reproductive and lactational performances, including length of productive life, were evaluated from records for 1960 to 1988 for a Jersey herd in coastal lowland semi-humid Kenya. The herd grazed natural pastures and until the mid 1970s received supplementary feeding. Mean performance included 31 months age at first calving, lactation milk yield (MY) of 1,788 kg in 3.3 lactations and a calving interval (CI) of 408 days. Mean milk yields declined from over 2,200 kg in the 1960s to about 1,500 kg in the 1980s with concomitant changes in calving interval, length of productive life and infertility. While annual genetic components of change in MY and CI were not significantly different from zero, the environmental components were large and significant (P < 0.01) showing that the declines in performance probably resulted from decreased feed availability and less efficient disease control. Estimates of genetic parameters were consistent with those in the literature. With good management purebred Jersey cows in coastal lowland semi-humid Kenya were productive, but animal and herd productivity were highly dependent on management level which had a major effect on both milk yield and reproductive wastage.

Age Factors↗

PubMed2000

Radon progeny activity in sweat following radon exposure in a warm and humid environment.

The objective was to evaluate whether activity of radon progenies can be detected in sweat following speleotherapeutic radon exposure (40 kBq/m3) in a warm (38 degrees C) and humid (relative humidity > 70%) environment. A group of 11 male patients with spondyloarthropathy (n = 6) or non-inflammatory rheumatic diseases (n = 5) underwent a 1-h treatment in the gallery of the Gasteiner Heilstollen, and 20 min after leaving the treatment area radon progeny activity was measured in sweat by utilizing a special filter set. The results suggest that radon is discharged with sweat, causing a significant activity of radon and radon progenies on the skin. This finding may be important from a clinical point of view, since specialists experienced in radon therapy have repeatedly emphasized the importance of the degree of radioactivity on the skin for the effectiveness of treatment. It has even been claimed that the skin is the major target for radon therapy, possibly because of the influence on Langerhans' cell function.

Fever↗

PubMed1983

Humidity resistant live-dead stain for spermatozoa.

Live-dead slides of bovine spermatozoa, prepared using conventional procedures, were found to be unstable at high relative humidities (RH) because of migration of water soluble dyes, such as eosin, into previously unstained cells At 85 percent RH, complete loss of contrast between "live" and "dead" cells occurred within 60 minutes. Comparable slides, prepared using erythrosin B and brilliant green, were found to maintain satisfactory contrast between the "live" and "dead" cells, even at 98 percent RH, throughout the seven-day humidity exposure trials.

Journal Article↗

PubMed1997

Collection of three bacterial aerosols by respirator and surgical mask filters under varying conditions of flow and relative humidity.

A variety of respirator filters and surgical masks were challenged with three aerosolized bacteria: Mycobacterium abscessus (M.a.) (a rod), Staphylococcus epidermidis (S.e.) (a sphere), and Bacillus subtilis (B.s.) (a rod). Tests were conducted at two flow rates (45 and 85 l./min) and two humidity levels (30 and 70%). Aerosols were measured with a total-particle, direct-reading, spectrometer and a viable particle cascade impactor. Measurements up- and downstream of the filter or mask were used in determining aerosol penetration; respirator or surgical mask fit was not evaluated. Bioaerosol penetration measured with two aerosol sampling instruments was found to correlate. Additionally, bioaerosol test parameters were evaluated with respect to their effect on penetration. Increasing flow resulted in increased penetration of all organisms while an increase in relative humidity did not exert a consistent effect on all organisms. Of the respirators approved by the National Institute for Occupational Safety and Health (NIOSH), filter efficiency was as expected with dust/mist respirators having the lowest and HEPA filters the highest efficiency. Surgical masks were the least efficient of all filters tested; these are not certified by NIOSH. Bioaerosol penetration was compared to that of a polystyrene latex sphere (PSL) aerosol. Penetration of the test aerosols was predicted on the basis of particle aerodynamic diameter and was expected to be in this order: PSL > M.a. > S.e. = B.s. The PSL aerosol was the most penetrating, as predicted. However, results showed that B.s. was more penetrating than S.e. The aerodynamic diameter may not be the best parameter for predicting aerosol penetration of non-spherical particles in these filters.

Aerosols↗

PubMed2001

Prevention of water vapour adsorption by carbon molecular sieves in sampling humid gases.

The water uptake by the solid sorbents Carbosieve S-III, Carboxen 569, 1000 and 1001, all of which are used for sampling of volatile organic compounds from the atmosphere. was examined using a direct experimental approach. The content of retained water is affected both by the trap temperature and the initial water vapour concentration in the sampled gas. Two different adsorption mechanism are operative. At low relative humidities (RH) only active polar centres are involved. This adsorption is so weak that negative water interferences can easily be managed. Another mechanism, the micropore volume filling, involves substantial amounts of water, becomes operative once the threshold value for relative humidity (RHth) is surpassed. RHth is 45+/-3% for Carboxen 1000 decreasing to 35+/-3% for the three other sorbents studied. A novel but simple strategy was tested for water management: moderate heating of the trap during the sampling (a warm trap method). The temperature elevation required depends on the RHth characteristic for the specific sorbent, and RH and the temperature of the sampled gas. Usually the 5-15 degrees C elevation is sufficient; only under extreme RH conditions is an elevation of 20 degrees C necessary. The diagrams are given to determine this elevation. Since the sample RH is significantly decreased at an elevated temperature the negative effect of water uptake on the safe sampling volume is alleviated. Consequently the sampled gas volume can be as large as desired which decreases detection limits.

Adsorption↗

PubMed1999

Effects of temperature and humidity on transpiration in adults of the lesser mealworm, Alphitobius diaperinus (Coleoptera: Tenebrionidae).

Measurements of water loss were made on adults of the lesser mealworm, Alphitobius diaperinus, using a recording micro-electrobalance and a programmable heat circulator bath. This species originates in tropical regions and infests poultry houses in temperate countries. Two routes of water loss were examined: the general cuticle and via the spiracles. Temperature and relative humidity of the ambient air substantially affect the cuticular transpiration in adults (fresh body weights from 12 mg to 22 mg). At near 0% R.H., between 20 and 40 degrees C the rate of body water loss gradually increased; on the other hand, the insects gained weight in an atmosphere close to saturation. Above 40 degrees C transpiration flow abruptly increased coinciding with the start of vigorous locomotor activity. This critical point corresponds to the opening of the spiracles from which the water is expelled from the tracheal system.In dead specimens, killed by cyanide or solvent, the water vapour slowly diffused out of the spiracles and, as in atracheate insects, the transpiration curves did not show a peak as the air temperature was increased.The thermostupor point (TSP) occurred as the insects became motionless; the corresponding temperature is significantly affected by atmospheric relative humidity (TSP=47.4+/-0.6 degrees C at c. 0% R.H.; TSP=46.6+/-0.7 degrees C at c. 100% R.H.).The transpiration flow was about four times as fast in specimens treated with solvent as in the individuals (live or cyanide-killed) that had undamaged water-proof cuticle. This species has to cope with a double challenge: (i) to adapt its physiology and ecology to poultry-house conditions which constitutes an extension of its primary habitats, and (ii) to survive over winter; high drought resistance and heat tolerance may constitute a pre-adaptation to conquer anthropogenic air-conditioned sites.

Journal Article↗

PubMed2000

Immediate and delayed mortality of Oryzaephilus surinamensis (L.) exposed on wheat treated with diatomaceous earth: effects of temperature, relative humidity, and exposure interval.

Adult Oryzaephilus surinamensis (L.), the sawtoothed grain beetle, were exposed for 4-72 h on wheat treated with diatomaceous earth (Protect-It(TM)), then removed and held for 1 week on untreated wheat. Beetles were exposed and held at 22, 27, and 32 degrees C, 40, 57, and 75% r.h. (nine combinations). Mortality after the initial exposures increased as exposure interval and temperature increased, but humidity effects were inconsistent with temperature. Mortality after the one-week holding period was greater than initial mortality, and also increased as the original exposure interval and the temperature increased. At 22 and 27 degrees C, mortality of beetles exposed from 4 to 24 h at 75% r.h. was significantly lower than mortality of beetles exposed for the same time intervals at 40 and 57% r.h. Nearly all of the beetles exposed for 72 h at all three relative humidities were dead after 1 week. The relationship between exposure interval and mortality was described by sigmoidal and linear regression for both the initial mortality and mortality 1 week after being transferred to untreated wheat. Results indicate that O. surinamensis is susceptible to the Protect-It(TM) formulation of diatomaceous earth, and will continue to suffer from the effects of exposure even after they are removed from the treated environment.

Journal Article↗

PubMed2001

Resistance of Cooperia to ivermectin treatments in grazing cattle of the Humid Pampa, Argentina.

A field experiment and a controlled efficacy trial were conducted to demonstrate resistance of cattle trichostrongylid nematodes to endectocidal compounds in grazing cattle on the Humid Pampa, Argentina. Male Polled Hereford calves, aged 9-11 months old, with a history of frequent treatments with compounds of the avermectin/milbemycin class, were used for the trial. The field experiment involved six groups of 10 animals each, which were subcutaneously treated with either ivermectin (IVM), long-acting ivermectin (LA-IVM), moxidectin (MXD) or doramectin (DRM) at a dosage of 0.2mg/kg BW. A fifth group was treated orally with fenbendazole at a dosage of 5mg/kg BW; the sixth group of calves served as non-treated control. Faecal samples were collected from each animal on the day of treatment and at 14 days after treatment. Nematode egg counts were performed to estimate the faecal egg count reduction test (FECRT). The FECRT showed that reductions were 65% (IVM), -20% (LA-IVM) and 85% (DRM). Egg counts from calves treated with MXD or fenbendazole were reduced by 95 and 100%, respectively. For the controlled efficacy trial, six animals with the highest egg counts from the IVM, LA-IVM and non-treated control groups, were necropsied on day 18 after treatment to determine numbers and nematode species in the abomasum and small intestine. The results indicated that efficacy against Cooperia oncophora was 62.7 and 48% for IVM and LA-IVM, respectively. Neither of the IVM formulations showed efficacy against Trichostrongylus spp. in the small intestine. However, the absence of Trichostrongylus spp. in some animals of both treated and control groups precluded a valid assessment of efficacy or resistance. It was concluded that resistance of trichostrongylid nematodes to the avermectin/milbemycin class of compounds in grazing cattle of the Humid Pampa, Argentina, may be strongly established on farms where cattle are treated at frequent intervals throughout the year.

Animal Husbandry↗

PubMed2000

Adhesion forces measured by atomic force microscopy in humid air

Adhesive forces measured with an atomic force microscope under ambient conditions are generally regarded to be dominated by non-surface-specific capillary force. In this study, the nature of the "pull-off" force on a variety of surfaces was investigated as a function of relative humidity. The results indicate that even under the condition where capillary condensation occurs there is chemical specificity in the measured pull-off force. Issues such as tip-surface contact time and surface roughness were ruled out as possible artifacts. A mathematical model of pull-off force as a function of relative humidity is proposed in which the chemical specificity is explained.

Journal Article↗