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The number of patients with cardiac failure admitted to hospital in Zaria, Nigeria, month by month during 1972-75 differed highly significantly between the cooler dry months and the hot wet months. The reasons are uncertain, but seasonal changes in blood-pressure and the effects of heat on the circulation and of humidity on the efficiency of sweating may be responsible.
A method is described by which the changes in shape that accompany hydration of Brassica pollen grains may be rapidly measured. Using this technique it has proved possible to chart the small amount of hydration that takes place on anthesis, in addition to the response of pollen to a range of relative humidities in vitro and in vivo. Such measurements, together with pollen transfer experiments, indicate that under normal field conditions self-pollen undergoes a brief period of hydration followed by some loss of water and that, in the course of this hydration, many pollen grains are inhibited from further growth. Raised levels of atmospheric water cause a variety of responses in self-pollen, ranging from tube growth through the pistil to the ovary, to tubes inhibited at the stigmatic surface, accompanied by the formation of callose. Surprisingly, compatible cross-pollen is also affected by high humidity, often developing extended tubes that are incapable of penetrating the stigmatic cuticle. The development of stigmatic callose is also stimulated by these tubes, as also occurs when other members of the Cruciferae are induced to germinate on Brassica stigmas by high levels of atmospheric water. This formation of callose in response to challenge by all types of pollen tube suggests models for the self-incompatibility response in Brassica that involve a direct linkage between S (incompatibility) gene products and the formation of callose may require some reexamination. Close study of the operation of the self-incompatibility system in a number of individuals has revealed all aspects of the response to be heavily dependent on the particular S genes possessed by the plant.
The effect of suggestion on the airway response to ten inhalations of normal saline followed by doubling concentrations of isoprenaline was assessed in 12 normal and 30 asthmatic subjects. It was suggested that the first 5 saline solutions contained a bronchoconstrictor and the second 5 a bronchodilator, or vice-versa, and that the first four isoprenaline solutions were inert whilst the last was a bronchodilator. Nine asthmatic but no normal subjects bronchoconstricted after saline inhalation with a mean 40% fall in specific airway conductance (sGaw). This was dose-dependent and abolished when inhalations were carried out at 37 degrees C 100% relative humidity. Suggestion did not affect the airway response to saline or isoprenaline in either group. We conclude that bronchoconstriction following saline inhalation, previously attributed to the effect of suggestion, is caused by airway cooling.
The effect of suggestion on the airway response to 10 inhalations of normal saline followed by doubling concentrations of isoproterenol was assessed in 12 normal and 30 asthmatic subjects. It was suggested that the first 5 saline solutions contained a bronchoconstrictor and that the second 5 contained a bronchodilator, or vice versa, and that the first 4 isoproterenol solutions were inert, whereas the last was a bronchodilator. Nine asthmatic, but no normal subjects, bronchoconstricted after saline inhalation, with a mean fall in specific airway conductance (SGaw) of 40%. This was dose-dependent and was abolished when inhalations were carried out at 37 degrees C 100% relative humidity. Suggestion did not affect the airway response to saline or isoproterenol in either group, but it did influence the subjective impression of airway caliber recorded on a visual analogue scale. In this study, the bronchoconstriction after saline inhalation, previously attributed to the effect of suggestion, was caused by airway cooling.
The purpose of this investigation was to evaluate the influence of lean body mass (LBM) and body weight (BW) on the thermoregulatory responses and endurance performance of male and female athletes in warm, humid environments. Ten (5 males, 5 females) healthy, moderately trained athletes with varying physiques performed a self-paced 30-min run on a motorized treadmill in warm (30 degrees C), humid (60% relative humidity) conditions, with the aim of running the greatest distance possible. Males completed one trial, while females completed two trials, one in each of the follicular (Fol) and luteal (Lut) phases of the menstrual cycle in a randomized fashion. There were no significant differences among groups for distance run (males, 5.2 +/- 0.4 km; Fol, 4.9 +/- 0.1 km; Lut, 4.7 +/- 0.1 km). However, following analysis of covariance accounting for LBM and BW, the distances run were significantly different. The adjusted means for distance run after accounting for LBM were 3.4 km for males (P < 0.05), 5.9 km for Fol, and 5.6 km for Lut. Adjusted means accounting for BW resulted in run distances of 6.5 km for males (P < 0.05), 4.2 km for Fol, and 4.0 km for Lut. Thermoregulatory responses such as rectal and skin temperatures were similar among groups. Avenues of heat loss and gain were altered relative to the menstrual cycle phase. The results suggest that one reason for the disparity in performance between male and female athletes over similar race distances might in part be related to unequal body characteristics and in particular to differences in LBM.
This study compared physiological responses associated with exercise tolerance in girls (G) and women (W) of similar fitness and heat acclimatization level during exercise in a hot and humid outdoor environment (33.4 degrees C and 55.1 % RH; WBGT = 29.9 +/- 0.2 degrees C). Nine pre-menarcheal G (age = 11.3 yr) and nine W (age = 26.8 yr), matched for aerobic capacity and heat acclimatization level, performed a cycling session at 60 % VO2max until fatigue. A sports drink was provided periodically to prevent dehydration. Tolerance time was not different between the groups (G = 56.9 +/- 6.3, W = 76.5 +/- 9.9 min, p > 0.05). During exercise, sweat rate (G = 9.1 +/- 1.1, W = 12.0 +/- 1.1 ml.m(-2).min(-1)), the increase in rectal temperature [T(re)] (G = 0.9 +/- 0.1, W = 1.1 +/- 0.1 degrees C), and heat storage (G = 10.6 +/- 5.3, W = 20.5 +/- 4.5 W.m(-2)) did not differ between the groups. At fatigue, T(re) (G = 38.2 +/- 0.1, W = 38.4 +/- 0.1 degrees C), heart rate (G = 167.3 +/- 7.3, W = 171 +/- 3.3 beats.min(-1)), stroke index (G = 48.3 +/- 1.5, W = 52.4 +/- 1.8 ml.m(-2)), and forearm skin blood flow (G = 9.5 +/- 1.3, W = 11.7 +/- 1.5 ml.100 ml(- 1).min(-1)) did not differ between the groups. Similar to women, the main reasons reported by girls to stop exercising in the heat were localized leg fatigue and gluteus muscle discomfort. We conclude that heat-acclimatized girls exhibit an adequate cardiovascular and thermoregulatory adjustment while exercising in a hot and humid outdoor environment when hypohydration is prevented.
The temporal and thermal response of various commonly used ion chambers (NEL, Exradin, PTW) with different wall and electrode materials is studied in a water phantom. Measurements were taken in heating water bath having an automatic temperature control mechanism. All chambers were submersed at 3 cm depth in water phantom and connected to separate electrometers for simultaneous readings for a given dose from a 6 MV beam. The temporal response was studied at approximately +/- 10 degrees C from room temperature, i.e., 10 degrees C and 30 degrees C. Temporal results show that all chambers reach quick equilibrium response within < 2 minutes of submersion in water. The steady-state thermal response was dependent upon the water temperature and wall and electrode compositions. The temperature and pressure corrected response of the NEL chamber was least affected by the changes in water temperature, where as the Exradin chamber has positive and PTW has negative slope with water temperature. The response varied within +/-1.5% between 10 degrees C-50 degrees C temperature and is mainly dependent on volume changes rather than the humidity. A correction factor based on thermal coefficients is derived for each chamber. It is concluded that ion chamber correction factors can be divided into first order; temperature and pressure connection, second order; volume correction for thermal expansion, and third order; humidity correction. To eliminate dosimetric error, the temporal and thermal response should be known for a chamber or water phantom temperature should be maintained close to room temperature.
Engineering ultraviolet irradiation systems as a control against infectious airborne diseases requires a knowledge of intrinsic ultraviolet (UV) inactivation rates of airborne bacteria. Ultraviolet inactivation rates for airborne Mycobacterium bovis bacillus Calmette-Guérin (BCG) were determined at 50% and 95% relative humidity (RH) in a 0.8 m3 bioaerosol reactor. Ultraviolet inactivation response of waterborne M. bovis BCG pure cultures was also determined. At 50% RH the airborne UV inactivation rates observed were two times greater than those observed in saturated air (RH = 95%), and rates at 95% RH were similar to those observed in otherwise identical cultures suspended in water. Intrinsic UV inactivation rates for M. bovis BCG were statistically similar to rates observed for Mycobacterium parafortuitum at 50% and 95% RH, indicating that M. parafortuitum is a valid surrogate for studying airborne UV responses of M. bovis BCG and Mycobacterium tuberculosis. Results also confirm that UV inactivation responses for bacteria suspended in water cannot be used to estimate UV dose response in unsaturated air.
Six healthy young men breathed room air or one of nine hot humid air conditions on separate days for one hour while walking on a treadmill (40% VO2 max). Inspired wet bulb temperatures ranged from 18.9 (room air) to 49.3 degrees C. Tissue temperatures in the mouth were measured by means of thermocouples placed on the tongue and hard palate. Analysis of variance on repeated measures showed significant increases in both tongue and hard palate tissue temperatures (p less than 0.001) as a result of increasing wet bulb temperatures; however, core temperature and heart rate were not affected (p greater than 0.05). Ratings of subjective discomfort increased proportionally with increases in wet bulb temperature of the inspired air. It was concluded that wet bulb temperature of inspired air is a valuable measure to uses in studying temperature responses of mouth tissues when inhaling hot humid air, particularly when investigating human tolerance levels in order to recommend federal standards for the design of breathing apparatus.
Human skin is exposed to an environment that varies in humidity from 100 to 0%, leading to seasonal variations in the condition of the skin. Exposure to a low humidity environment creates an osmotic gradient across the stratum corneum, which is known to modulate cutaneous barrier function. Heat shock proteins protect against stress-induced destabilization of proteins. We investigated whether osmotic shock (sorbitol) induced a heat shock protein response in normal human keratinocytes, and used heat shock as a positive control. Both heat shock and osmotic stress (200 and 300 mM sorbitol) clearly induced heat shock proteins 70 and 27 mRNA levels. The induction of heat shock protein 70 mRNA levels by osmotic stress peaked at 16 h and persisted until 24 h, whereas upregulation of heat shock protein 70 mRNA levels by heat peaked at 2 h and returned to baseline levels by 6 h. Sorbitol also increased heat shock protein 70 levels in a concentration-dependent manner. The kinetics of heat shock protein 27 mRNA induction by osmotic stress and heat were similar with peak induction at 6 h. The mitogen activated protein kinase family of proteins plays an important part in the coordination of gene responses to various stress conditions. We have demonstrated that the p38 mitogen activated protein kinase was strongly activated by 200 mM and 300 mM sorbitol. The specific p38 mitogen activated protein kinase inhibitor PD169316 almost completely blocked heat shock protein 70 mRNA induction by 200 mM and 300 mM sorbitol and completely suppressed heat shock protein 27 mRNA induction with 200 mM sorbitol. PD169316 also counteracted upregulation of heat shock protein 70 levels by sorbitol. These data indicate that keratinocytes respond to osmotic stress by p38 mitogen activated protein kinase regulated induction of heat shock proteins. This molecular pathway may be relevant for the mechanisms regulating the response of human skin to variations in environmental humidity.
This paper presents and compares two capacitive humidity sensors with interdigitated electrodes for a portable clinical application. A polyimide-sensitive layer covers the first structures and the optimized ones include a benzocyclobutene-sensitive layer and a heating resistor. Humidity measurements results are presented, in particular sensors response time in absorption, which are very small (inferior to 500 ms). Next, mechanisms of absorption and adsorption in a polymer layer are described and the two structures are compared. Suitability of optimized sensors for our application is discussed: new structures allow us to increase sensitivity and decrease response time. When the structure is maintained at 40 degrees C by its heater, the response time is 200 ms and the total desorption time is 11 s.
Gravitropic responses of oat coleoptiles were measured in different growth media; humid air, natural soil and artificial soil (glass beads). The oat coleoptiles in soil and glass beads were monitored by NMR imaging, while those in humid air were imaged in darkness with an infrared-sensitive charge-coupled device (CCD) camera. The present study shows for the first time that gravitropic experiments can be performed in artificial soil using NMR imaging as a convenient and suitable recording method. Not only was it possible to follow the gravitropic curvatures in natural soil, but the artificial soil allowed plant images of sufficient spatial and temporal resolution to be recorded. The advantages of using artificial soil in magnetic resonance imaging studies are that the iron content of glass beads is very low compared with natural soil, and that the artificial soil matrix can easily, be standardized with regard to particle size distribution and nutrient content. Two types of glass beads were used, the diameter of the small and the large beads being 300-400 and 420-840 micrometers, respectively. The growth rate of the coleoptiles in soil and in big beads was roughly the same and only slightly lower than in humid air, whereas small beads reduced the growth rate by approx. 16%. The bending rate of the coleoptiles during the gravitropic response was reduced by c. 65% in soil and 75% in bead mixtures relative to bending in air. It should be noted, however, that the maximum curvature of the coleoptile tip was of the same order in all cases, about 35 degrees. This value may represent the largest possible curvature of the organ. The potential of NMR imaging to study, how plant organs penetrate the soil under the influence of gravitropism, mechanical impedance and thigmotropism is also discussed.
We conducted a survey and audit of thermal equipment use in very low-birth-weight infants in five Ohio neonatal intensive care units (NICUs) to document regional practice. The survey indicated a variety of thermal care styles. Two NICUs preferred to admit infants to incubators, the other three favoring radiant warmers. These three NICUs moved infants from radiant warmers into incubators at significantly different mean ages. The audit demonstrated inconsistent use of plastic covers, warming mattresses, and added humidity under radiant warmers, and discrepancies between survey responses and actual use within NICUs. Inter-NICU variability of thermal equipment use may complicate fluid management.
Growth chamber experiments were conducted to study the physiological and growth response of peanut (Arachis hypogaea L.) to 50% and 85% relative humidity (RH). The objective was to determine the effects of RH on pod and seed yield, harvest index, and flowering of peanut grown by the nutrient film technique (NFT). 'Georgia Red' peanut plants (14 days old) were planted into growth channels (0.15 x 0.15 x 1.2 m). Plants were spaced 25 cm apart with 15 cm between channels. A modified half-Hoagland solution with an additional 2 mM Ca was used. Solution pH was maintained between 6.4 and 6.7, and electrical conductivity (EC) ranged between 1100 and 1200 microS cm-1. Temperature regimes of 28/22 degrees C were maintained during the light/dark periods (12 hours each) with photosynthetic photon flux (PPF) at canopy level of 500 micromoles-m-2s-1. Foliage and pod fresh and dry weights, total seed yield, harvest index (HI), and seed maturity were greater at high than at low RH. Plants grown at 85% RH had greater total and individual leaflet area and stomatal conductance, flowered 3 days earlier and had a greater number of flowers reaching anthesis. Gynophores grew more rapidly at 85% than at 50% RH.
Observations of high acidity (pH as low as 1.7) in fogwater collected in polluted areas have provoked concern for public health. Effects of exposure to acidic pollutants have not been studied under foggy conditions; thus there is no directly relevant information from which to estimate the health risk. Indirectly relevant information is available from numerous studies of volunteers exposed to "acid fog precursors" under controlled conditions at less than 100% relative humidity. The effect of fog in modifying responses to inhaled acidic pollutants is difficult to predict: depending on circumstances, fog droplets might either increase or decrease the effective dose of pollutants to the lower respiratory tract. Fog inhalation per se may have unfavorable effects in some individuals. Sulfur dioxide is known to exacerbate airway constriction in exercising asthmatics, at exposure concentrations attainable in ambient air. Nitrogen dioxide has shown little untoward respiratory effect at ambient concentrations in most studies, although it has been suggested to increase bronchial reactivity. Sulfuric acid aerosol has shown no clear effects at concentrations within the ambient range. At somewhat higher levels, increased bronchial reactivity and change in mucociliary clearance have been suggested. Almost no information is available concerning nitric acid.
We have partially characterized root hydrotropism and its interaction with gravitropism in maize (Zea mays L.). Roots of Golden Cross Bantam 70, which require light for orthogravitropism, showed positive hydrotropism; bending upward when placed horizontally below a hydrostimulant (moist cheesecloth) in 85% relative humidity (RH) and in total darkness. However, the light-exposed roots of Golden Cross Bantam 70 or roots of a normal maize cultivar, Burpee Snow Cross, showed positive gravitropism under the same conditions; bending downward when placed horizontally below the hydrostimulant in 85% RH. Light-exposed roots of Golden Cross Bantam 70 placed at 70 degrees below the horizontal plane responded positively hydrotropically, but gravitropism overcame the hydrotropism when the roots were placed at 45 degrees below the horizontal. Roots placed vertically with the tip down in 85% RH bent to the side toward the hydrostimulant in both cultivars, and light conditions did not affect the response. Such vertical roots did not respond when the humidity was maintained near saturation. These results suggest that hydrotropic and gravitropic responses interact with one another depending on the intensity of one or both factors. Removal of the approximately 1.5 millimeter root tip blocked both hydrotropic and gravitropic responses in the two cultivars. However, removal of visible root tip mucilage did not affect hydrotropism or gravitropism in either cultivar.
The radon absorption ability and the track etch properties of the polycarbonate material of commercial compact disks make them very useful as sensitive retrospective 222Rn detectors. The basic idea is to remove, after exposure, a surface layer that is thicker than the range of the alpha particles of the 222Rn and 220Rn progenies and to count the electrochemically etched tracks at the corresponding depths (>80 microm). The effects on the response due to differences in pressure, temperature, and humidity have been studied experimentally. The effect of the growing of 210Po after long-term exposures was also estimated. The effect of all listed factors except the temperature is either absent or restricted to maximum--about 10% for the very extreme cases. The variation of the response at 83 microm depth over the temperature interval 15-25 degrees C is +/-12% around the 20 degrees C value. The dependence of the calibration factor on the etched depth beneath the surface was studied at 4 different temperatures within the range expected indoors. The results show that the depth dependence is exponential with the parameters of the exponent also being dependent on the temperature. In practice, using the track density obtained in two or more depths beneath the compact disk's front surface, an a posteriori temperature correction could be made. By this correction it is possible to substantially reduce the bias in the results due to the unknown temperature during exposure. The results imply that by using home stored compact disks long-term retrospective 222Rn measurements could be made with an uncertainty that could be potentially better than 10%. The useful range of the method starts at about 3 Bq m(-3) (for 10 y exposure time) and appears to cover practically the whole range of indoors 222Rn concentrations.
Laboratory tests with generated aerosols were conducted to test the efficacy of two recent design modifications to the well-established tapered element oscillating microbalance (TEOM) continuous particulate matter (PM) mass monitor. The two systems tested were the sample equilibration system-equipped TEOM monitor operating at 30 degrees C, which uses a Nafion dryer as part of the sample inlet, and the differential TEOM monitor, which adds a switched electrostatic precipitator and uses a self-referencing algorithm to determine "true PM mass." Test aerosols included ammonium sulfate, ammonium nitrate, sodium chloride, copper (II) sulfate, and mixed aerosols. Aerosols were generated with an atomizer or a vibrating orifice generator and were equilibrated in a 450-L slow flow chamber before being sampled. Relative humidity in the chamber was varied between 10 and 90%, and step changes in humidity were executed while generating aerosol to test the response of the instruments. The sample equilibration system-equipped TEOM monitor does reduce, but not totally eliminate, the sensitivity of the TEOM mass monitor to changes in humidity. The differential TEOM monitor gives every indication of being a very robust technique for the continuous real-time measurement of ambient aerosol mass, even in the presence of semi-volatile particles and condensable gases.