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At least 649 records · Page 36Linked to original sources

PubMed1990

Effects of humid air breathing during arm or treadmill exercise on exercise-induced bronchoconstriction and refractoriness.

Although it has been reported that inhibitory prostaglandins may be a causal factor in exercise refractoriness, it is still unclear whether exercise-induced bronchoconstriction (EIB) and/or other specific "exercise factors" are necessary to trigger their release and render a subject refractory to subsequent exercise. The purpose of this study was to determine whether non-EIB-producing exercise with the legs or arms could produce refractoriness to a standard treadmill challenge. Eight asthmatic subjects with EIB completed three sessions consisting of two exercise challenges separated by a 30-min rest. In all sessions, the second challenge was done on a treadmill while breathing dry air. Conditions for Challenge 1 were the following: Session A = treadmill, dry air; Session B = treadmill, humid air; Session C = arm cranking, humid air. All three conditions produced a significant degree of refractoriness. There was a tendency for the percent protection index to be greater for Session A; however, no significant differences were found among the three sessions. Therefore, it can be concluded that although both exercise and bronchoconstriction may play a role in producing the refractory period, neither severe bronchoconstriction nor intense exercise with the same muscle groups are required to produce refractoriness.

Adult↗

PubMedDate not supplied

Effect of temperature and humidity on the adhesive strength of orthodontic direct bonding materials.

The effects of temperature and humidity on the adhesive strength of two direct bonding orthodontic materials were investigated. Tensile testing showed that the adhesive bond was much stronger than the polycarbonate brackets. There is a significant increase in tensile and shearlike strength after 15-, 22-, and 30-day incubation at 37 C and 100% humidity, as compared with initial strength (after 30 minutes) at room temperature.

Acrylic Resins↗

PubMed2001

Pharmacokinetics of norelgestromin and ethinyl estradiol delivered by a contraceptive patch (Ortho Evra/Evra) under conditions of heat, humidity, and exercise.

The objectives of this randomized, open-label, three-period, incomplete block design study were to evaluate the pharmacokinetics of norelgestromin (NGMN) and ethinyl estradiol (EE) delivered by the contraceptive patch, Ortho Evra/Evra, and to evaluate patch adhesion under conditions of heat, humidity, and exercise. During each treatment period, 30 healthy women wore Ortho Evra on the abdomen for 7 days under one of six conditions (normal activity, sauna, whirlpool, treadmill, cool water immersion, or a combination of activities). Blood samples were collected before and several times to 240 hours after patch application. Mean serum concentrations of NGMN and EE generally remained within the reference ranges, 0.6 to 1.2 ng/ml and 25 to 75 pg/ml, respectively, during the 7-day wearperiodfor all activities. Only 1 (1.1%) of 87 patches completely detached spontaneously. Peel force measurements were comparable for all activities. Ortho Evra was well tolerated. In conclusion, Ortho Evra delivers efficacious concentrations of NGMN and EE and maintains adhesive reliability through 7 days of wear even under conditions of heat, humidity, and exercise.

Adhesiveness↗

PubMed1994

A multicentre comparison of the efficacy of terbutaline Turbuhaler and salbutamol pressurized metered dose inhaler in hot, humid regions.

Twenty seven adults and 20 children with previously diagnosed stable asthma, using a salbutamol pressurized metered dose inhaler (P-MDI) and living in Cairns, Townsville and Southport, Queensland, Australia participated in a randomized, open-label cross-over comparison of terbutaline administered via Turbuhaler and salbutamol administered via P-MDI. The aim of the study was to compare the clinical effectiveness and patient acceptance of the two treatments in hot, humid regions. Terbutaline was administered via Turbuhaler and salbutamol via P-MDI on at least two occasions per day during each four week treatment period. Spirometry was performed at the start of the study, after the two week run-in and at the end of each treatment period. Patients used diary cards to record morning and evening peak expiratory flows, daily symptom scores and daily intake of beta 2 agonist medication. At the end of the study, patients answered a treatment preference question. Forty six patients completed the study. No statistically significant differences were observed between the two treatments in peak expiratory flow, change in morning peak expiratory flow pre- and post-beta-agonist, daily symptom scores, diurnal variability and spirometry. Forty four percent of patients preferred the terbutaline Turbuhaler and 39% preferred salbutamol P-MDI. Both agents were similarly tolerated. Terbutaline delivered by Turbuhaler is as clinically effective as salbutamol delivered by P-MDI in patients with asthma living in hot, humid regions.

Aerosols↗

PubMed1981

Relative humidity and manic admissions in the London area.

This report describes an investigation into a possible relationship between barometric pressure and relative humidity, and depressive and manic admissions in the London area. A negative correlation between manic admissions and relative humidity was observed when the data were examined in several ways.

Affective Disorders, Psychotic↗

PubMed2026

Whole-genome sequencing reveals divergent and shared selection signatures of heat stress adaptation in indigenous Ethiopian zebu cattle from dry-hot and humid-hot environments.

African zebu cattle (Bos indicus) exhibit remarkable adaptations to extreme thermal conditions, yet the genomic basis of this resilience remains incompletely characterized. Ethiopia provides a unique natural setting in which closely related zebu populations have adapted divergently to dry-hot (DHETZ) and humid-hot (HHETZ) climates. In this study, we reanalyzed publicly available whole-genome sequencing datasets from 46 Ethiopian zebu cattle from five populations and compared them with Asian zebu, Sudanese zebu, African taurine, and European taurine breeds. By integrating genome-wide SNP analysis, population genetic structure assessment, and multiple selection scans (iHS, Hp, XP-EHH, and XP-CLR), we identified distinct and shared selection signatures between DHETZ and HHETZ. We detected 33.7 million and 34.2 million biallelic autosomal SNPs in DHETZ and HHETZ, respectively. Ethiopian zebu clustered closely with Sudanese zebu but showed clear divergence from Asian zebu and taurine breeds. DHETZ and HHETZ exhibited very low genetic differentiation (FST = 0.0063), consistent with their shared ancestry; however, each group displayed unique selection signals. In DHETZ, iHS and Hp detected 298 and 113 candidate regions, respectively, whereas in HHETZ, they detected 244 and 138 regions, respectively. Cross-population XP-EHH and XP-CLR analyses identified 163 and 227 divergent regions between DHETZ and HHETZ, respectively. Integration of the four selection scans identified 19 high-confidence candidate regions in DHETZ and 13 in HHETZ. DHETZ showed strong selection in genes involved in oxidative stress regulation, protein folding, mitochondrial function, and vascular remodeling, including SESN2, DNAJC8, GRPEL2, ABLIM3, and AFAP1L1. In contrast, HHETZ displayed signatures in genes associated with immune responses, energy metabolism, and angiogenesis inhibition, including MYD88, PRKACA, PRKACB, and WIF1. Several genes, including VEGFC, TNIP3, and DMXL2, were under selection in both groups, suggesting conserved mechanisms of thermotolerance and reproductive adaptation. The shared VEGFC signal and the HHETZ-specific WIF1 signal may indicate a distinct vascular regulatory mechanism in the dry-hot and humid-hot environments. Our results reveal a dual pattern of genomic adaptation in Ethiopian zebu cattle and provide candidate loci for future validation and climate-resilient livestock breeding.

Animals↗

PubMed1990

Inspired gas relative humidity affects systemic to pulmonary bronchial blood flow in humans.

To our knowledge, the effects of humidity of inspired air on bronchial blood flow in humans are unknown. During total cardiopulmonary bypass, we measured systemic to pulmonary bronchial blood flow (Qbr[s-p]) which is the volume of blood accumulating into the left side of the heart in the absence of pulmonary and coronary flow. A cannula was introduced into the right upper pulmonary vein and advanced into the lowermost portion of the left side of the heart. From this cannula Qbr(s-p) was vented by gravity and measured. Inspired gas (10 L/min, endotracheal tube, 50 percent O2 + 50 percent N2O) relative humidity was less than 20 percent and greater than 85 percent in group A (n = 25) and in group B (n = 25), respectively. Mean (+/- SE) Qbr(s-p) was 40.7 +/- 0.06 ml/min or 1.32 +/- 0.12 ml/min (percent cardiac output) in group A and 21.7 +/- 1.8 ml/min or 0.68 +/- 0.06 ml/min in group B. These data indicate that under these conditions Qbr(s-p) is increased by dry gas lung inflation in humans.

Cardiopulmonary Bypass↗

PubMed2006

Human resting extracellular heat shock protein 72 concentration decreases during the initial adaptation to exercise in a hot, humid environment.

Heat shock protein (Hsp) 72 is a cytosolic protein that also is present in the circulation. Extracellular Hsp72 (eHsp72) is inducible by exercise and is suggested to act as a danger signal to the immune system. The adaptive response of eHsp72 to repeated exercise-heat exposures in humans remains to be determined. An intracellular animal study found a reduced Hsp72 response, with no change in resting levels, during heat stress after a single day of passive heat acclimation. The current study therefore tested whether adaptations in human eHsp72 levels would similarly occur 24 hours after a single exercise-heat exposure. Seven males completed cycle exercise (42.5% V(O2peak) for 2 hours) in a hot, humid environment (38 degrees C, 60% relative humidity) on each of 2 consecutive days. Blood samples were obtained from an antecubital vein before exercise and 0 hours and 22 hours postexercise for the analysis of eHsp72. Exercise-heat stress resulted in enhanced eHsp72, with a similar absolute increase found on both days (day 1: 1.26 ng/mL [0.80 ng/mL]; day 2: 1.29 ng/mL [1.60 ng/mL]). Resting eHsp72 decreased from rest on day 1 to day 2's 22-hour postexercise sample (P < 0.05). It is suggested that the reduction in resting eHsp72 after 2 consecutive exercise-heat exposures is possibly due to an enhanced removal from the circulation, for either immunoregulatory functions, or for improved cellular stress tolerance in this initial, most stressful period of acclimation.

Adaptation, Physiological↗

PubMed1992

[Suitability of capacitive sensors for measuring relative humidity in anesthetic gas systems].

A capacitive sensor was tested for its suitability for measuring relative humidity in an anaesthetic gas circuit. The valvo sensor PH1 was tested using various different anaesthetic gas mixtures. Measuring accuracy was influenced neither by such volatile anaesthetics as isoflurane and halothane, nor by oxygen or nitrous oxide. The response time of the sensor depends on its position within the gas, and in the most favourable case is about 3 minutes. The sensor is readily incorporated within an existing gas circuit. The linearity of the characteristic curve must be corrected by external electronic compensation to avoid measuring problems in the lower humidity range.

Anesthesia, Endotracheal↗

PubMed1998

[Measuring breath alcohol concentration during artificial ventilation. Model studies of the effect of temperature and humidity on measurements by various sampling systems].

The present paper examined the question as to the extent to which the taking of gas samples for the purpose of measuring the breath alcohol concentration (BAC) in the expired air of patients on artificial respiration is influenced by temperature and humidity. For this purpose a lung model standardized at different alcohol concentrations was used, in which the temperature (T: 25, 30 and 35 degrees C) and the relative humidity (RH: 50, 75 and 95%) were varied.

Breath Tests↗

PubMed2000

[Rapid measurement of water vapor partial pressure at the saturation point with a new hybrid humidity sensor].

A new hybrid humidity sensor comprising a conventional capacitance humidity sensor and a planar heating element is described. Owing to its short response time of only a few milliseconds, its great measuring accuracy, large measuring range, and simplicity in handling, the sensor is suitable for measuring water vapour partial pressure in gases with rapidly changing flow and direction, e.g. in ventilated patients in the fields of anaesthesia and intensive care medicine. The small dimensions permit measurements at almost any location within the ventilation system.

Anesthesia↗

PubMedDate not supplied

Development of Rhodnius prolixus (Hemiptera: Reduviidae) under constant and cyclic conditions of temperature and humidity.

Development of Rhodnius prolixus after eclosion until the adult stage was studied at constant temperatures (T), 15, 20, 25, 28, 35 C, and relative humidities (RH), 75, 86 and 97%, and fluctuating (16/8 hr) temperatures, T I/II, 15/28 C, 20/25 C, 25/28 C and 25/35 C, and relative humidities, RH I/II, 86/75% and 97/75%. Eclosion or molting were not observed at 15 C and 86 or 97% RH, respectively. At 35 C and 75% RH only few insects molted. By alternating T I/II, 15/28 C and 25/35 C, insects developed at high frequency. Cumulating the average lengths of the interphases within independent groups for each instar, R. prolixus reached the adult stage most rapidly (86.7 days) and at highest frequency per instar (mean: 91.8%) at 28 C and 75% RH. Under fluctuating T I/II, development was completed within 100 days or less at 25/28 C and 25/35 C with high rates of hatch and molting. Development was slowest at fluctuating TI/II, 15/28 C and 20/25 C (>185 days), and at constant 20 C (>300 days). Mortality was higher at constant 97% RH or fluctuating RH I, 97%, than at constant or fluctuating 86% RH. Refeeding was minimal at optimal conditions of T and RH for development. The most refeeding was observed at a constant 35 C.

Animals↗

PubMed2002

Variation of the oviposition preferences of Aedes aegypti in function of substratum and humidity.

Two Aedes aegypti (L.) populations were studied in the laboratory regarding the preference for three types of breeding sites, i.e., flasks containing only water, flasks with a plant and flasks with a stick. Each of these breeding units was placed in one cage and the choice of the oviposition sites was determined for individual females and three females per experimental unit at two humidity levels. Preference for ovipositing on the water surface was observed and varied according to experimental unit and humidity. Mean hatching of eggs in water surface was 46.6%. Experiments with three females showed a more marked difference than when only one female was used. Inter and intrapopulation variability regarding oviposition sites was observed. The discrimination between the different oviposition substrates, hatching in water surface and its implication for mosquito control are discussed.

Aedes↗

PubMed2006

Effect of temperature and humidity on insecticidal effect of SilicoSec against Ephestia kuehniella (Lepidoptera: Pyralidae) larvae.

Laboratory experiments were carried out to assess the insecticidal effect of the diatomaceous earth formulation SilicoSec against larvae of Ephestia kuehniella Zeller (Lepidoptera: Pyralidae), in stored wheat (Triticum durum Desf.). Larvae were exposed to wheat treated with SilicoSec at 400 and 800 ppm and held at 20, 25, and 30 degrees C and 55 and 75% RH. Larval mortality was assessed after 24 h, 48 h, 7 d, and 14 d of exposure in the treated wheat. At both dose rates, mortality increased with temperature, but this increase varied with the exposure interval. At short (< or = 48-h) exposures, larval mortality was significantly higher at 30 degrees C than at the other two temperatures. In contrast, no significant differences were noted between 20 and 25 degrees C. At longer exposures (> or = 7 d), the increase of temperature increased mortality at 800 ppm, but no significant differences were noted between 25 and 30 degrees C at 400 ppm. Furthermore, significant differences in larval mortality were noted between the two humidity levels, but only at exposures > or = 7 d. After 14 h of exposure, at both dose rates examined, the increase of temperature significantly decreased mortality. The results of the current study indicate that E. kuehniella is susceptible to SilicoSec, but temperature and relative humidity should be taken into consideration.

Animals↗

PubMed2000

Experimental teratogeny in the tick Hyalomma marginatum marginatum (Acari: Ixodida: Ixodidae): effect of high humidity on embryonic development.

The effect of 90% RH on the embryonic development of Hyalomma marginatum marginatum Koch was investigated at 25 degrees C. Under the influence of this factor, 2.1% dead eggs, 13.0% dead embryos, 6.9% abnormally hatched larvae, 0.2% larvae with malformations, and 77.8% normal larvae appeared. The embryos died during the cleavage of nuclei, the formation of the blastoderm, the formation of the germ band and its metamerization, and the differentiation of the leg anlagen. Egg hatch was also inhibited in various phases. Various kinds of anomalies were observed in larvae of Hyalomma m. marginatum. Most teratological changes (70.8%) occurred within the idiosoma. They were hetromorphose (32.6%), oligomely (15.4%), heterosymely (12.3%), symely (1.5%), atrophy (6.1%), and ectomely (3.1%). Anomalies within the gnathosoma occurred rarely (3.1%). As many as 26.2% larvae had composite anomalies (oligomely, heterosymely, atrophy) together. They contained various structures of the gnathosoma or idiosoma. These anomalies decreased the survival rate of the larvae. The investigations showed that during the formation of the blastoderm, the formation of the germ band and its metamerization the embryos have the largest susceptibility of being affected by high humidity. Some anomalies in specimens collected from nature may develop under influence of unfavorable humidity levels.

Animals↗

PubMed2004

Kinetics of toluene sorption and desorption in Ca- and Cu-montmorillonites investigated with Fourier transform infrared spectroscopy under two different levels of humidity.

Clays in soils or groundwater aquifer materials play roles in the sorption of organic pollutants. The intrinsic sorption kinetics of toluene in dry and humid clay films was investigated by tracking the change of infrared absorbance. Under the humid condition, similar toluene-sorbed intensities were found in Ca- and Cu-montmorillonites. However, a higher intensity of sorbed toluene was found in the Cu-form than in the Ca-form under the dry condition, which indicates a stronger interaction occurring in dry Cu-montmorillonite. The general time scale of sorption of toluene on clays is around 100 s. In both forms of montmorillonite, some portion of toluene was desorbed at an extremely slow rate under the dry condition. Some newly identified peaks were persistent against desorption from montmorillonites, suggesting the existence of irreversibly sorbed species and the possibility of toluene transformation occurring in clay systems.

Adsorption↗

PubMed2003

Determination of the surface sorption properties of talc, different salts, and clay minerals at various relative humidities using adsorption data of a diverse set of organic vapors.

Adsorption constants of a diverse set of organic vapors have been measured on NaCl, KNO3, (NH4)2SO4, NH4Cl, kaolinite, bentonite. and talc at different relative humidities at 15 degrees C. Together with the earlier studied quartz (SiO2), CaCO3, and alpha-Al2O3, these surfaces represent relevant sorbents for organic vapors in the environment. An equation that describes the van der Waals and H-bond interactions between the sorbate and the surface can be used to describe the sorbate and sorbent variability in the measured data and to predict sorption constants of organic compounds that have not been tested on the respective surface. The unknown properties of the sorbent surfaces are used as fitting parameters in this equation. These data provide important insights into the variability of sorption properties of natural, inorganic surfaces as a function of relative humidity.

Adsorption↗

PubMedDate not supplied

Physiological change in nasal patency in response to changes in posture, temperature, and humidity measured by acoustic rhinometry.

BACKGROUND: Acoustic rhinometry has been used to assess nasal patency and to calculate nasal cavity volume. This study used acoustic rhinometry to assess changes in nasal patency after alterations in posture, unilateral mechanical obstruction, temperature, and humidity. METHODS: Eight healthy adult volunteer subjects underwent acoustic rhinometry during the following conditions: (1) sitting position (control), (2) supine position, (3) left lateral recumbent position, (4) nostril unilaterally mechanically blocked, (5) ice pack on neck, (6) drinking cold water, (7) drinking hot water, (8) nasal nebulizer, and (9) oxymetazoline decongestant. RESULTS: Two distinct patterns emerged based on the total nasal cavity volumes in response to the decongestant. Subjects with initial unilateral nasal cavity volumes near the mean had an expected increase in total volume after the topical decongestant administration. There were two subjects with initial volumes of 1 SD above the mean that had a paradoxical decrease in total volume in response to the decongestant. In all subjects, there was a significant decrease in the volume of each of the nasal cavities in response to ingestion of hot water at 1 minute. There was a significant decrease in the volume of the smaller of the two nasal cavities in response to nebulizer treatment and hot water ingestion at 5 minutes. Total nasal cavity volume changes were not significant for any of the variables. CONCLUSION: Changes in nasal cavity volumes were detected by acoustic rhinometry after alterations in posture, unilateral mechanical obstruction, temperature, and humidity. Nebulizer treatment and hot water ingestion caused a significant decrease in nasal volume. The nose of a healthy patient was able to adapt to environmental and physiological changes to maintain a consistent total nasal volume within 15 minutes.

Adult↗