Effect of inspired air conditions on exercise-induced bronchoconstriction and urinary CC16 levels in athletes

Injury to the airway epithelium has been proposed as a key susceptibility factor for exercise-induced bronchoconstriction (EIB). Our goals were to establish whether airway epithelial cell injury occurs during EIB in athletes and whether inhalation of warm humid air inhibits this injury. Twenty-one young male athletes (10 with a history of EIB) performed two 8-min exercise tests near maximal aerobic capacity in cold dry (4°C, 37% relative humidity) and warm humid (25°C, 94% relative humidity) air on separate days. Postexercise changes in urinary CC16 were used as a biomarker of airway epithelial cell perturbation and injury. Bronchoconstriction occurred in eight athletes in the cold dry environment and was completely blocked by inhalation of warm humid air [maximal fall in forced expiratory volume in 1 s = 18.1 ± 2.1% (SD) in cold dry air and 1.7 ± 0.8% in warm humid air, P < 0.01]. Exercise caused an increase in urinary excretion of CC16 in all subjects (P < 0.001), but this rise in CC16 was blunted following inhalation of warm humid air [median CC16 increase pre- to postchallenge = 1.91 and 0.35 ng/μmol in cold dry and warm humid air, respectively, in athletes with EIB (P = 0.017) and 1.68 and 0.48 ng/μmol in cold dry and warm humid air, respectively, in athletes without EIB (P = 0.002)]. The results indicate that exercise hyperpnea transiently disrupts the airway epithelium of all athletes (not only in those with EIB) and that inhalation of warm moist air limits airway epithelial cell perturbation and injury.     

The feeling of dampness at low temperatures

The widely held view that in cold weather one feels colder when the atmosphere is damp than when it is dry was investigated on clothed subjects. Subjective coldness and dampness, determined by a panel of six people who walked about half a mile in the open in winter, were compared with measurements of temperature, relative humidity, and other meteorological variables. The panellists comments showed that when the weather is cold, people think it is damp when the sky is overcast, irrespective of relative humidity. However, when this factor has been allowed for there still appears to be some correlation between subjective dampness and relative humidity. Relative humidity does appear to have an effect on how cold one feels at low temperatures, but only to a limited extent, and in the opposite direction to popular belief.     

Effect of Temperature on Hospital Admissions for Myocardial Infarction in a Subarctic Area

In a study of the effect of mean daily temperature on the admission and fatality rates of 771 patients with myocardial infarction the admission rate was found to be significantly higher on cold (temperature below 0°C.) than on warm (temperature above 0°C.) days. The fatality rate was almost equal in cold and warm weather. Thus the seasonal fluctuation in the admission rate of patients with myocardial infarction is probably due to a direct effect of environmental temperature.     

A technique to measure the ability of the human nose to warm and humidify air.

To assess the ability of the nose to warm and humidify inhaled air, we developed a nasopharyngeal probe and measured the temperature and humidity of air exiting the nasal cavity. We delivered cold, dry air (19-1 degrees C, <10% relative humidity) or hot, humid air (37 degrees C, >90% relative humidity) to the nose via a nasal mask at flow rates of 5, 10, and 20 l/min. We used a water gradient across the nose (water content in nasopharynx minus water content of delivered air) to assess nasal function. We studied the characteristics of nasal air conditioning in 22 asymptomatic, seasonally allergic subjects (out of their allergy season) and 11 nonallergic normal subjects. Inhalation of hot, humid air at increasingly higher flow rates had little effect on both the relative humidity and the temperature of air in the nasopharynx. In both groups, increasing the flow of cold, dry air lowered both the temperature and the water content of the inspired air measured in the nasopharynx, although the relative humidity remained at 100%. Water gradient values obtained during cold dry air challenges on separate days showed reproducibility in both allergic and nonallergic subjects. After exposure to cold, dry air, the water gradient was significantly lower in allergic than in nonallergic subjects (1,430 +/- 45 vs. 1,718 +/- 141 mg; P = 0.02), suggesting an impairment in their ability to warm and humidify inhaled air.     

Cold spots in neonatal incubators are hot spots for microbial contamination

Thermal stability is essential for the survival and well-being of preterm neonates. This is achieved in neonatal incubators by raising the ambient temperature and humidity to sufficiently high levels. However, potentially pathogenic microorganisms also can thrive in such warm and humid environments. We therefore investigated whether the level of microbial contamination (i.e., the bacterial load) inside neonatal incubators can be predicted on the basis of their average temperature and relative humidity settings, paying special attention to local temperature differences. Swab samples were taken from the warmest and coldest spots found within Caleo incubators, and these were plated to determine the number of microbial CFU per location. In incubators with high average temperature (≥ 34°C) and relative humidity (≥ 60%) values, the level of microbial contamination was significantly higher at cold spots than at hot spots. This relates to the fact that the local equilibrium relative humidity at cold spots is sufficiently high to sustain microbial growth. The abundance of staphylococci, which are the main causative agents of late-onset sepsis in preterm neonates, was found to be elevated significantly in cold areas. These findings can be used to improve basic incubator hygiene.     

Effect of cold and warm dry air hyperventilation on canine airway blood flow

Tracheobronchial blood flow increases with cold air hyperventilation in the dog. The present study was designed to determine whether the cooling or the drying of the airway mucosa was the principal stimulus for this response. Six anesthetized dogs (group 1) were subjected to four periods of eucapnic hyperventilation for 30 min with warm humid air [100% relative humidity (rh)], cold dry air (-12 degrees C, 0% rh), warm humid air, and warm dry air (43 degrees C, 0% rh). Five minutes before the end of each period of hyperventilation, tracheal and central airway blood flow was determined using four differently labeled 15-micron diam radioactive microspheres. We studied another three dogs (group 2) in which 15- and 50-micron microspheres were injected simultaneously to determine whether there were any arteriovenous communications in the bronchovasculature greater than 15 micron diam. After the last measurements had been made, all dogs were killed, and the lungs, including the trachea, were excised and blood flow to the trachea, left lung bronchi, and parenchyma was calculated. Warm dry air hyperventilation produced a consistently greater increase in tracheobronchial blood flow (P less than 0.01) than cold dry air hyperventilation, despite the fact that there was a smaller fall (6 degrees C) in tracheal tissue temperature during warm dry air hyperventilation than during cold dry air hyperventilation (11 degrees C), suggesting that drying may be a more important stimulus than cold for increasing airway blood flow. In group 2, the 15-micron microspheres accurately reflected the distribution of airway blood flow but did not always give reliable measurements of parenchymal blood flow.     

Exercise-induced HSP-72 elevation and cardioprotection against infarct and apoptosis.

Successive bouts of endurance exercise are associated with both increased cardiac levels of heat shock protein-72 (HSP-72) and improved cardioprotection against ischemia-reperfusion (I/R)-induced cardiac cell death. Although overexpression of HSP-72 has been shown to be cardioprotective in transgenic animals, it is unclear whether increased levels of HSP-72 are essential for exercise-induced cardioprotection against I/R-mediated cell death. We tested the hypothesis that exercise-induced increases in myocardial levels of HSP-72 are required to achieve exercise-mediated protection against I/R-induced cardiac cell death. To test this postulate, we investigated the effect of preventing the exercise-induced increase in cardiac HSP-72 on myocardial infarction and apoptosis after 50 min of in vivo ischemia and 120 min of reperfusion. Adult male rats remained sedentary or performed successive bouts of endurance exercise in cold (8 degrees C) or warm (22 degrees C) environments. We found that, compared with sedentary control animals, exercise in a warm environment significantly increased myocardial HSP-72 content. In contrast, exercise in the cold environment prevented the exercise-induced increase in myocardial HSP-72 levels. After in vivo myocardial I/R, infarct size was reduced in both exercised groups compared with sedentary animals. Furthermore, compared with sedentary rats, I/R-induced myocardial apoptosis (as indicated by terminal deoxynucleotidyl transferase dUTP-mediated nick-end labeling-positive nuclei and caspase-3 activity) was attenuated in both groups of exercised animals. Therefore, although HSP-72 has cardioprotective properties, our results reveal that increased myocardial levels of HSP-72 (above control) are not essential for exercise-induced protection against I/R-induced myocardial infarction and apoptosis.     

大鼠心肌梗死模型构建和评价方法的改良

目的 优化和改良大鼠心肌梗死模型的构建和评价方法,提高模型的可靠性和稳定性.方法 取雄性SD大鼠结扎左冠状动脉前降支建立心肌梗死模型,在模型的构建过程中从麻醉、插气管、保温、手术操作、术后护理等环节进行优化和改进,并观察不同的麻醉方法和术后时间对心肌梗死程度的影响,用不同的染色方式进行心肌梗死模型的评价.结果 对比大鼠心肌梗死模型构建过程中各组大鼠麻醉时间、术后恢复以及心肌梗死面积的结果,戊巴比妥钠是更合适的麻醉药;结扎手术后时间对模型心肌梗死范围无明显影响（P＆gt;0.05）,但心肌缺血危险区面积随术后时间的延长明显减少（P〈0.01）;TTC与依文思蓝双重染色相对TTC染色能明显观察到心肌缺血危险区和梗死区范围.结论 优化和改进后的大鼠心肌梗死模型,提高了动物福利,制备和评价方法更加客观准确.     

Effect of autonomic blockade on tracheobronchial blood flow

Tracheobronchial blood flow increases two to five times in response to cold and warm dry air hyperventilation in anesthetized tracheostomized dogs. In this series of experiments we have attempted to attenuate this increase by blockade of the autonomic nervous system. Four groups of anesthetized, tracheostomized, open-chest dogs were studied. Group 1 (n = 5) were hyperventilated for 30 min with 1) warm humid [approximately 26 degrees C, 100% relative humidity, (rh)] air followed by bilateral vagotomy, 2) warm humid air, 3) cold (-22 degrees C, 0% rh) dry air, and 4) warm humid air. Groups 2, 3, and 4 (n = 3/group) were hyperventilated for 30 min with 1) warm humid (approximately 41 degrees C, 100% rh) air, 2) warm dry (approximately 41 degrees C) air, 3) warm humid air, and 4) warm dry air. Group 2 were controls. Group 3 were given phentolamine, 0.6 mg/kg intravenously, as an alpha-blockade, and group 4 were given propranolol, 1 mg/kg, as a beta-blockade after warm dry air hyperventilation (period 2). Five minutes before the end of each 30-min period of hyperventilation, measurements of vascular pressures, cardiac output, arterial blood gases, and inspired, body, and tracheal temperatures were measured, and differently labeled radioactive microspheres were injected into the left atrium to make separate measurements of airway blood flow. After the last measurements had been made animals were killed and their lungs were excised. Blood flow to the airways and lung parenchyma was calculated.(ABSTRACT TRUNCATED AT 250 WORDS)     

Phenotypic flexibility in cutaneous water loss and lipids of the stratum corneum in house sparrows (Passer domesticus) following acclimation to high and low humidity

Resistance to water-vapor diffusion through the skin is thought to be conferred by lipids in the stratum corneum (SC), the outer layer of the epidermis. We tested the effect of ambient humidity on cutaneous water loss (CWL) and lipid composition of the SC by acclimating house sparrows (Passer domesticus) to either a dry (6.5 g/m(3) absolute humidity) or a humid (31 g/m(3)) environment for 3 wk at a thermoneutral temperature (30 degrees C). Sparrows in the dry-acclimated group reduced CWL by 36% compared with those in the humid environment. Relative to initial values, both groups of sparrows decreased CWL, 45% in the dry-acclimated group and 23% in the humid group, suggesting that temperature is also an important stimulus for CWL apart from humidity. Both groups of acclimated sparrows decreased quantities of cholesterol, free fatty acids, and cerebrosides and increased the proportion of ceramides in their SC. Lipid amounts or proportions in the SC did not differ between dry- and humid-acclimated sparrows, but the free fatty acid : ceramide ratio was significantly lower in dry-acclimated birds. Also, lipid composition was only correlated with CWL in dry-acclimated sparrows, suggesting that structural changes to SC lipids are more tightly linked to CWL regulation in response to low humidity. Our results demonstrate phenotypic flexibility in CWL and lipid composition of the SC and provide support for a functional relationship between these traits.     

Effect of Eleutherococcus on the subcellular structures of the heart in experimental myocardial infarct

The effect of Eleutherococcus on subcellular heart organization in rats with or without myocardial infarction was investigated. It was found that Eleutherococcus decreases ultrastructural lesions in the ischemic area, intensifies regeneration of subcellular structures and accelerates the recovery after myocardial infarction. The accumulation of glycogen, lipids and lysosomes is observed in lipocytes. It is suggested that positive effect of Eleutherococcus during myocardial infarction is related to lipid transformation into glycogen.     

Tracheal vascular and smooth muscle responses to air temperature and humidity in dogs

Twenty-five dogs were anesthetized, paralyzed, and artificially ventilated. Their cranial tracheal arteries were perfused bilaterally with blood at constant flow, and the perfusion pressures (Patr) were measured. Tracheal smooth muscle function was assessed by recording changes in external diameter (delta Dtr). The perfused segment of the trachea was exposed to air at a constant unidirectional airflow of 25 l/min. Group 1 (n = 6) was exposed to cold dry air, ambient room air, and hot dry and hot humid air, each for 10 min with exposures starting from zero flow. The tracheal vascular responses to all four conditions were small vasodilations (delta Patr from -2 to -6%) followed by recovery or small vasoconstrictions. In group 2 (n = 19), exposures to cold dry and hot humid air were preceded and followed by body-temperature fully humidified air. Cold dry air caused a sustained vasodilation (delta Patr -9.0 +/- 1.1%), and hot humid air usually caused a biphasic response: a vasoconstriction (delta Patr 4.4 +/- 1.0%) followed by a vasodilation (delta Patr -5.7 +/- 1.9%). The warm humid air after cold dry air or hot humid air caused a further vasodilation, which lasted a short time after cold dry air (delta Patr -3.7 +/- 0.4%) but greater than 10 min after hot humid air (delta Patr -13.8 +/- 1.4%). In both groups, all exposures that cooled the trachea (cold dry air, ambient room air, and hot dry air) caused smooth muscle contraction, and hot humid air that warmed the trachea caused relaxation.     

Environmental temperature and mortality from acute myocardial infarction

Mortality from acute myocardial infarction (MI) over the 5 year period 1982–1987 in Brown County, Wisconsin, was analyzed to assess the relationship with environmental temperature. Deaths occurrring on the day of and the day following a significant snowfall as well as deaths occuring in health care facilities were eliminated from consideration because the focus was upon temperature, not snowfall or events within a hospital. These criteria resulted in the inclusion of 1,802 days and 926 cases of acute MI. The mean temperature on the day of death was obtained from climatological data and were grouped into six categories covering a range of temperatures from<–17.8°C (0°F) to 16.1°C (61°F). The number of deaths in each category was tabulated. The effect of temperature, sex, and age were analyzed by regression analysis. The results indicated a linear increase in mortality as mean daily temperature decreased over the temperature range. The inverse temperature effect was most pronounced in males over the age of 60. These results indicate that cold temperatures appear to be associated with an increased mortality from myocardial infarction.     

蓝莓花色苷预处理对大鼠心肌梗死的保护作用

目的观察蓝莓花色苷（blueberryanthocyanin,BBA）预处理对实验性急性心肌梗死大鼠心肌梗死面积,心肌肌钙蛋白-T（cTn-T）表达,Bax、Bcl-2mRNA表达的影响,探讨其干预心肌梗死的机制。方法40只Wistar大鼠随机分为假手术组,心肌梗死模型组,BBA低、中、高剂量组,药物干预4周,末次给药30min后结扎左冠状动脉前降支建立心梗动物模型。24h后,TTC检测心肌梗死面积;Westernblotting方法检测心肌细胞cTn-T蛋白表达;realtimePCR方法检测Bcl-2mRNA、BaxmRNA表达。结果模型组和假手术组相比,模型组心肌梗死面积显著升高（P〈0．01）,心肌细胞cTn．T蛋白表达下降（P〈0．05）,Bcl-2mRNA表达下降（P〈0．05）,BaxmRNA表达显著升高（P〈0．01）,Bcl-2／Bax比值显著降低（P〈0．01）。BBA干预给药组和模型组相比,中剂量组心肌梗死面积低于模型组（P〈0．05）,低剂量组心肌细胞cTn-T蛋白表达升高（P〈0．05）,中剂量组Bcl-2mRNA表达升高（P〈0．05）,低、中剂量组BaxmRNA表达下降（P〈0．05）,中剂量组Bcl-2／Bax比值升高（P〈0．05）。结论蓝莓花色苷对心肌梗死后心肌细胞具有明确的保护作用,其机制可能与减少心肌梗死面积,上调心肌细胞eTn-T蛋白的表达,上调Bcl-2mRNA表达、下调BaxmRNA表达,抑制心肌梗死后心肌细胞凋亡有关。     

Realised toxicity of plant defences to an insect herbivore depends more on insect dehydration than on energy reserves

1. Climate effects on plant defences, and subsequently insect herbivores, have received considerable attention. However, climate also directly affects the physiological condition of insects that may influence their ability to combat plant defences. 2. This study tested the effects of body fat and water content on the ability of mountain pine beetles, Dendroctonus ponderosae Hopkins, to tolerate monoterpenes, the primary defences of their host pine trees. To manipulate their physiological condition, we exposed beetles to one of three environmental treatments: cold (4 °C, 30% RH), humid (21 °C, 70% RH) or dry (21 °C, 30% RH). Beetles had the highest fat and water content in the cold treatment, followed by lower fat but the same water content in the humid treatment, and the lowest of both in the dry treatment. Following environmental treatments, beetles were exposed to 0, 312.5 or 625 ppm vapours of monoterpenes (−)-α-pinene or (R)-(+)-limonene. 3. Survival during both environmental and monoterpene treatments was highest for the cold treatment, less for the humid treatment, and lowest for the dry treatment. Fat and water content positively predicted survival. In response to increasing monoterpene concentration, survival, body condition and water content, but not fat, declined. 4. These results indicate that water content of insect herbivores was important for the realised toxicity of plant defences, presumably due to the process of excreting detoxified compounds. Energetic costs of detoxification were less evident. Dehydration of insects has not been widely considered in insect–plant interactions, but effects of climate change on humidity may become increasingly important for these interactions.     

Immediate,lag and time window effects of meteorological factors on ST-elevation myocardial infarction incidence

The influence of several meteorological parameters on acute myocardial infarction (AMI) incidences with immediately and/or delayed effects has been widely reported. It remains unknown whether the individual AMI subtypes reveal similar patterns. To date, generally seasonal variation in ST elevation MI (STEMI) has been investigated. However, these approaches couldn’t detect the effects of changes in multiple meteorological variables on STEMI incidence within a specific season. Therefore, the aim of our study is to explore immediate, delayed and cumulative effects of average daily temperature, atmospheric pressure and humidity on nation-wide STEMI hospital admissions. We linked daily hospitals’ STEMI admission data with meteorological stations’ data according to the patient’s permanent residence. Subsequently, a multivariate analysis based on a main effect generalised linear model, assuming a log-link function with a Poisson distribution, was conducted. With the help of lags, we were able to analyse delayed effects, while the cumulative effects of specific meteorological variables were analysed utilising time windows. As a result, we confirmed immediate and delayed negative effect of low temperature and low relative humidity for all observed lags as well as cumulative average effects of low temperature and low relative humidity for all observed time windows. However, no delayed, single-day effect for atmospheric pressure was detected. Nevertheless, the cumulative average effect was confirmed in all time windows suggesting that prolonged low pressure influences the incidence of STEMI. A novelty of our approach is the comparative examination of immediate, delayed and cumulative effect of specific meteorological variables on the incidence of STEMI. This approach enables us to gain a new insight into the phenomenon studied.     

The effect of insulin on the heart

Insulin infusion has been advocated in the treatment of myocardial ischaemia and myocardial infarction. There is evidence from experimental animal studies for a protective effect of high-dose insulin administration in myocardial ischaemia and myocardial infarction. In some relatively small study populations a reduction in mortality was reported in those patients who received glucose-insulin-potassium (GIK) during myocardial infarction, which was confirmed in two meta-analyses. However, it has not been possible to reproduce these positive results in large randomised clinical trials. (Neth Heart J 2010;18:255-9.)     

Precooling leg muscle improves intermittent sprint exercise performance in hot, humid conditions.

We used three techniques of precooling to test the hypothesis that heat strain would be alleviated, muscle temperature (Tmu) would be reduced, and as a result there would be delayed decrements in peak power output (PPO) during exercise in hot, humid conditions. Twelve male team-sport players completed four cycling intermittent sprint protocols (CISP). Each CISP consisted of twenty 2-min periods, each including 10 s of passive rest, 5 s of maximal sprint against a resistance of 7.5% body mass, and 105 s of active recovery. The CISP, preceded by 20 min of no cooling (Control), precooling via an ice vest (Vest), cold water immersion (Water), and ice packs covering the upper legs (Packs), was performed in hot, humid conditions (mean +/- SE; 33.7 +/- 0.3 degrees C, 51.6 +/- 2.2% relative humidity) in a randomized order. The rate of heat strain increase during the CISP was faster in Control than Water and Packs (P < 0.01), but it was similar to Vest. Packs and Water blunted the rise of Tmu until minute 16 and for the duration of the CISP (40 min), respectively (P < 0.01). Reductions in PPO occurred from minute 32 onward in Control, and an increase in PPO by approximately 4% due to Packs was observed (main effect; P < 0.05). The method of precooling determined the extent to which heat strain was reduced during intermittent sprint cycling, with leg precooling offering the greater ergogenic effect on PPO than either upper body or whole body cooling.     

Herbivore grazing—or trampling? Trampling effects by a large ungulate in cold high‐latitude ecosystems

Mammalian herbivores have important top‐down effects on ecological processes and landscapes by generating vegetation changes through grazing and trampling. For free‐ranging herbivores on large landscapes, trampling is an important ecological factor. However, whereas grazing is widely studied, low‐intensity trampling is rarely studied and quantified. The cold‐adapted northern tundra reindeer (Rangifer tarandus) is a wide‐ranging keystone herbivore in large open alpine and Arctic ecosystems. Reindeer may largely subsist on different species of slow‐growing ground lichens, particularly in winter. Lichen grows in dry, snow‐poor habitats with frost. Their varying elasticity makes them suitable for studying trampling. In replicated factorial experiments, high‐resolution 3D laser scanning was used to quantify lichen volume loss from trampling by a reindeer hoof. Losses were substantial, that is, about 0.3 dm³ per imprint in dry thick lichen, but depended on type of lichen mat and humidity. Immediate trampling volume loss was about twice as high in dry, compared to humid thin (2–3 cm), lichen mats and about three times as high in dry vs. humid thick (6–8 cm) lichen mats, There was no significant difference in volume loss between 100% and 50% wetted lichen. Regained volume with time was insignificant for dry lichen, whereas 50% humid lichen regained substantial volumes, and 100% humid lichen regained almost all lost volume, and mostly within 10–20 min. Reindeer trampling may have from near none to devastating effects on exposed lichen forage. During a normal week of foraging, daily moving 5 km across dry 6‐ to 8‐cm‐thick continuous lichen mats, one adult reindeer may trample a lichen volume corresponding to about a year's supply of lichen. However, the lichen humidity appears to be an important factor for trampling loss, in addition to the extent of reindeer movement.     

De- and rehydration behavior of alpha,alpha-trehalose dihydrate under humidity-controlled atmospheres

Effects of humidity were investigated on de- and rehydration behavior of alpha,alpha-trehalose dihydrate (T(h)) throughout simultaneous measurements of differential scanning calorimetry and X-ray diffractometry (DSC-XRD) and simultaneous thermogravimetry and differential thermal analysis (TG-DTA). When T(h) was heated from room temperature under dry nitrogen atmosphere, a metastable anhydrous crystal (T(alpha)) was formed at 105 degrees C after dehydration of T(h). The resulting T(alpha) melted at 125 degrees C and became amorphous, followed by cold crystallization from 150 degrees C giving rise to a stable anhydrous crystal T(beta). Under a highly humid atmosphere, on the other hand, T(beta) was formed at 90 degrees C directly as a result of T(h) dehydration. T(alpha) was readily rehydrated and turned back to T(h) when nitrogen gas with low water vapor pressure of 2.1kPa was admitted, whereas high water vapor pressure up to 7.4kPa was required for rehydration of T(beta) into T(h). This study provided a picture of pathways that link various solid forms of trehalose, taking into account the effects of a humid environment.