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1.
Different morbidities and mortalities of ischemic stroke may occur among seasons. For detecting the seasonal variations of severity after stroke onset and prognosis, we employed a retrospective analysis on a prospective regional hospital-based stroke registry and included a total of 1039 consecutive patients with onset date from January 2014 to December 2015. Patients were divided into four groups according to the onset seasons. Baseline characteristics, stroke subtypes, admission National Institute of Health Stroke Scale (NIHSS) score and modified Rankin Scale (mRS) score in 90 d were recorded and compared. Ordinal logistic regression was used to evaluate the association of seasons and severity or outcomes. Higher proportion of cardiac embolisms appeared in spring and winter (p < 0.001). The median admission NIHSS score was 5 in spring, 3 in summer, 4 in fall and 4 in winter (p = 0.036). After 90 d from onset, 40.5% of patients in spring suffered poor outcome (mRS 3–6), while 24.6% in summer, 33.9% in fall and 40.1% in winter (p < 0.001). After adjusted for age, sex, stroke subtypes and other covariates, patients in spring and winter had 1.76 times (95%CI 1.14–2.70, p = 0.010) and 1.53 times (95%CI 1.08–2.18, p = 0.017) the risk of suffering higher severity category than patients in summer, respectively. Compared with summer group, risk of worse outcomes at 90 d increased to 2.30 times in spring (95%CI 1.53–3.45, p < 0.001), 1.57 times in fall (95%CI 1.14–2.16, p = 0.006) and 2.09 times in winter (95%CI 1.50–2.91, p < 0.001), respectively. In conclusion, onset seasons were associated with severity and outcomes in ischemic stroke, and patients admitted in spring and winter had more severity and worse outcomes than patients in summer. 相似文献
2.
Bolger C Tufvesson E Anderson SD Devereux G Ayres JG Bjermer L Sue-Chu M Kippelen P 《Journal of applied physiology (Bethesda, Md. : 1985)》2011,111(4):1059-1065
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. 相似文献
3.
Poecilogony is a relatively uncommon life-history strategy that results in the production of two different larval forms from the same egg mass (e.g., free-swimming lecithotrophic larvae and post-metamorphic, crawling juveniles). In this study, a population of the opisthobranch gastropod Haminoea zelandiae from Pauatahanui Inlet, New Zealand, was found to exhibit poecilogony. Further, differences in development, hatching times and proportion of hatchlings that were veligers or juveniles were examined for egg masses in two temperature regimes in the laboratory: cool (15-17 °C), and warm (21-23 °C). Hatching proportions were also examined for egg masses collected from the field (where temperatures ranged from 21-23 °C) for varying lengths of time (1 d, 5 d, and 10 d post-spawning). Hatchlings from egg masses in warmer temperatures developed faster and hatched earlier than those in cool temperatures. In the laboratory, egg masses in warm conditions hatched a greater proportion of post-metamorphic juveniles (45.4%) compared to egg masses in cool conditions (24.6%) Further, egg masses that had been in the field 10 d before hatching (i.e., more days at warmer temperatures) exhibited a greater proportion of post-metamorphic juveniles (67.9%) than those that were collected after only 1 d in the field (25.1%). Together these results suggest that temperature may have an important role in mediating dispersal strategies in this poecilogonous species. 相似文献
4.
Jeffries KM Hinch SG Martins EG Clark TD Lotto AG Patterson DA Cooke SJ Farrell AP Miller KM 《Physiological and biochemical zoology : PBZ》2012,85(1):62-73
Some Pacific salmon populations have been experiencing increasingly warmer river temperatures during their once-in-a-lifetime spawning migration, which has been associated with en route and prespawn mortality. The mechanisms underlying such temperature-mediated mortality are poorly understood. Wild adult pink (Oncorhynchus gorbuscha) and sockeye (Oncorhynchus nerka) salmon were used in this study. The objectives were to investigate the effects of elevated water temperature on mortality, final maturation, and blood properties under controlled conditions that simulated a "cool" (13°C) and "warm" (19°C) freshwater spawning migration. After 10 d at 13°C, observed mortality was 50%-80% in all groups, which suggested that there was likely some mortality associated with handling and confinement. Observed mortality after 10 d at 19°C was higher, reaching ≥98% in male pink salmon and female pink and sockeye salmon. Thus, male sockeye salmon were the most thermally tolerant (54% observed mortality). Model selection supported the temperature- and sex-specific mortality patterns. The pink salmon were closer to reproductive maturation and farther along the senescence trajectory than sockeye salmon, which likely influenced their survival and physiological responses throughout the experiment. Females of both species held at 19°C had reduced plasma sex steroids compared with those held at 13°C, and female pink salmon were less likely to become fully mature at 19° than at 13°C. Male and female sockeye salmon held at 19°C had higher plasma chloride and osmolality than those held at 13°C, indicative of a thermally related stress response. These findings suggest that sex differences and proximity to reproductive maturity must be considered when predicting thermal tolerance and the magnitude of en route and prespawn mortality for Pacific salmon. 相似文献
5.
Sappington TW Arnold MD Brashears AD Parajulee MN Carroll SC Knutson AE Norman JW 《Journal of economic entomology》2006,99(1):67-75
We characterized the level of risk of boll weevil, Anthonomus grandis grandis Boheman, reintroduction to an eradication zone posed by dispersal from cotton modules during and after transport to the gin. Mark-release-recapture experiments in August and September in Texas indicated that most weevils disperse rapidly from the module surface, temperature permitting, unless confined under a module tarp, where most died. Nevertheless, 1-5% of released weevils were recovered alive after 24 h on the side and top surfaces of modules, representing potential dispersants. Mortality of boll weevils caged on the top surface of a module was 95-100% after 1-4 d when maximum air temperatures were > or = 33 degrees C and 72-100% when minimum temperatures were -7 degrees C or lower, but a few survived even after experiencing a minimum daily temperature of -12 degrees C. Under warm (daily maximum temperatures > or = 25 degrees C) and cold (daily minimum temperatures < or = 0 degrees C) weather conditions, survival was higher under the tarp than on the open surface of the module (20 versus 7% and 42 versus 26%, respectively), but mortality was 100% in both locations when temperatures reached 34 degrees C. Our results indicate that although the threat to an eradication zone posed by boll weevil dispersal from an infested module is very low under most environmental conditions, it is probably greatest when 1) a module is constructed and transported from an infested zone during weather too cool for flight, followed by warm weather favorable for flight at the gin yard; or 2) such a module is transported immediately after construction in moderate-to-warm weather. 相似文献
6.
A Maran J Lomas H Archibald I A Macdonald E A Gale S A Amiel 《BMJ (Clinical research ed.)》1993,306(6871):167-171
OBJECTIVES--To compare awareness of hypoglycaemia and physiological responses to hypoglycaemia with human and porcine insulin in diabetic patients who reported loss of hypoglycaemia awareness after transferring to human insulin. DESIGN--Double blind randomised crossover study of clinical experience and physiological responses during slow fall hypoglycaemic clamping with porcine and human insulin. SETTING--Clinical investigation unit of teaching hospital recruiting from diabetes clinics of five teaching hospitals and one district general hospital. SUBJECTS--17 patients with insulin dependent diabetes mellitus of more than five years'' duration who had reported altered hypoglycaemia awareness within three months of transferring to human insulin. MAIN OUTCOME MEASURES--Glycaemic control and frequency of hypoglycaemic episodes during two months'' treatment with each insulin. Glucose thresholds for physiological and symptomatic responses during clamping. RESULTS--Glycaemic control did not change with either insulin. 136 hypoglycaemic episodes (eight severe) were reported with human insulin and 149 (nine severe) with porcine insulin (95% confidence interval -4 to 2.5, p = 0.63). 20 episodes of biochemical hypoglycaemia occurred with human insulin versus 18 with porcine insulin (-0.8 to 1, p = 0.78). During controlled hypoglycaemia the mean adrenaline response was 138 nmol/l/240 min for both insulins; neurohormonal responses were triggered at 3.0 (SE 0.2) versus 3.1 (0.2) mmol/l of glucose for adrenaline and 2.5 (0.1) versus 2.5 (0.1) mmol/l for subjective awareness. CONCLUSIONS--These data suggest that human insulin per se does not affect the presentation of hypoglycaemia or the neurohumoral, symptomatic, and cognitive function responses to hypoglycaemia in insulin dependent diabetic patients with a history of hypoglycaemia unawareness. 相似文献
7.
The relationships between photosynthesis, flowering, and growth temperatures were examined experimentally in four populations of the C4 grass genus Bouteloua. Field-collected plants were grown under two temperature regimes, cool (20 C day/6 C night) and warm (30/16), representative of the extreme populations. Populations collected from the warm climates had significantly lower photosynthetic capacity when grown in the cool chamber relative to the warm chamber, while photosynthetic capacity in the cool climate populations did not differ between the growth conditions. Additionally, exposure to a 2-day cold temperature treatment (10/-2), representative of late-season frosts in high altitude sites, resulted in further reductions in photosynthesis in the warm climate plants, but not in the cool climate plants. This effect was greater for plants grown in the cool growth chamber. Flowering was reduced by 70% in the warm climate plants grown in the cool chamber, and was correlated with photosynthetic inhibition following the short-term cold temperature treatment. These results indicate that genetic differentiation for photosynthetic temperature sensitivity has occurred in the cool climate populations, and that long-term exposure to cool temperatures coupled with short-term relatively extreme low temperatures results in greater photosynthetic inhibition in nontolerant populations. 相似文献
8.
Thermal biology, and therefore energy acquisition and survival, of ectotherms can be affected by diel and seasonal patterns of environmental temperatures. Galápagos Lava Lizards live in seasonal environments that are characterized by a warm and wet period when reproductive activity is maximal, and cooler and drier period. With the use of radiotelemetric techniques to record lizard surface temperatures (Ts), we studied the thermal ecology of the San Cristóbal Lava Lizard (Microlophus bivittatus) during both the warm and cool seasons over two years. During the diel activity period and when operative temperatures exceeded Tset-min, at least on rock faces without canopy, 52% or less of the Ts observations fell within the laboratory-determined Tset range (36–40 °C). Therefore, lizards may have avoided very warm midday temperatures in shaded microhabitats and the lag times in changes in Ts values occurred as operative temperatures rose rapidly during late morning warming phase. Lizards effectively thermoregulated during a year with moderate warm season temperatures and during a cool season that was unseasonably warm. In contrast, lizards less effectively thermoregulated during the warmest and coolest years of the study. We did not detect intersexual differences in thermoregulation although males may thermoregulate less effectively than do females during the cool season although we were unable to detect significant differences using our nonparametric statistical techniques. 相似文献
9.
The venodilatory response to nitroglycerin (0.8 mg sublingually) was measured in 10 healthy young male volunteers in a cool [24.3 +/- 0.6 degrees C skin temperature (Tsk)] and a warm environment (34.7 +/- 0.2 degrees C Tsk). Nitroglycerin caused mean arterial pressure to fall and heart rate to rise in both the cool (105 +/- 2 to 96 +/- 3 mmHg; 55 +/- 3 to 62 +/- 3 beats/min) and the warm environment (87 +/- 3 to 81 +/- 3 mmHg; 66 +/- 4 to 75 +/- 3 beats/min), but the fall in pressure was greater in the cool than in the warm environment. Forearm blood flow was reduced and forearm vascular resistance elevated in the cool (117 +/- 19 units; 1.15 +/- 0.08 ml.100 cc arm-1.min-1) compared with the warm environment (15 +/- 3 units; 8.60 +/- 1.89 ml.100 cc arm-1.min-1). Nitroglycerin caused forearm vascular resistance to fall in the cool but had no effect in the warm environment. Venous distensibility (increase in venous volume per 30-mmHg increase in venous pressure) was twice as great in the warm as in the cool environment (3.90 +/- 0.27 vs. 1.88 +/- 0.23 ml/100 cc arm). However, the venodilatory effect of nitroglycerin was similar in the cool and warm environments (0.79 +/- 0.10 vs. 0.67 +/- 0.13 ml/100 cc arm, respectively). Arterioles are not dilated by nitroglycerin in the warmer environment, but the venodilatory effect of nitroglycerin is quantitatively similar in the two environments. 相似文献
10.
The hippopotamus (Hippopotamus amphibius) spends more than 12 h a day in the water. Hippos are often submitted to water temperatures that vary with the seasons. We
hypothesize that this difference between cool and warm water temperatures leads to variations in behavioural thermoregulation.
We recorded the exposure of hippos to sunshine at the beginning and at the end of the dry season. Our results show that (1)
sunshine exposure lasted much longer in cool water and (2) sun-bathing occurred during the hottest hours. It is therefore
likely that in cool water hippos were cold and expressed an original behaviour of search for heat. 相似文献
11.
The objectives of this study were to identify the level and stage of embryonic mortality that occur in dairy cows during hot and cool seasons of the year. Experimental dairy cows, of varying ages, were artificially inseminated with frozen-thawed semen from proven Holstein sires. Females on each dairy unit were then randomly allocated to one of three experimental groups after partitioning by day of artificial insemination, days post partum, parity, and current milk production level. In Group I and Group II, nonsurgical embryo collection was performed on each cow using Dulbecco's phosphate-buffered saline as the flushing medium. Embryos from cows in Group I were collected on Days 6 or 7 post insemination during the hot (n=93) and cool (n=64) seasons. Embryos from cows in Group II were collected on Days 13 or 14 post insemination during the hot (n=97) and cool (n=63) seasons. In Group III, contemporary control cows were also inseminated during the hot (n=106) and cool (n=106) seasons, and fetal heart beat was evaluated via ultrasound between Days 25 and 35 following insemination. Embryo viability decreased (P<0.05) from 59% at Day 7 to 27% at Day 14 in the hot season, but was not decreased during the cool season (52 vs. 60%). Pregnancy rate at Days 25 to 35 was 21% in the hot season, which was less (P<0.05) than the 36% in the cool season. The percentage of unfertilized ova collected in both the hot and cool seasons suggests that fertilization failure was not affected by season of breeding. In summary, embryonic loss after Day 7 of pregnancy appears to be a problem in this hot, dry climate. 相似文献
12.
Membrane phospholipid phase separations in plants adapted to or acclimated to different thermal regimes 总被引:8,自引:4,他引:4
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The phase separation temperatures of total leaf phospholipids from warm and cool climate plants were determined in order to explore the relationship of lipid physical properties to a species' thermal habitat. The separation temperatures were determined by measuring the fluorescence intensity and fluorescence polarization of liposomes labeled with the polyene fatty acid probe trans-parinaric acid. To focus on a single climatic region, Mojave Desert dicots (chiefly ephemeral annuals) were examined, with plants grown under identical conditions whenever possible. Winter active species showed lower phase separation temperatures than the summer active species. A group of warm climate annual grasses showed separation temperatures distinctly higher than those of a group of cool climate grasses, all grown from seed under the same conditions. Growth at low temperature seems correlated with (and may require) a low phase separation temperature. Winter active ephemerals appear genetically programmed to synthesize a mixture of phospholipids which will not phase separate in the usual growth conditions. When the lipids of desert perennials were examined in cool and warm seasons, there was a pronounced seasonal shift in the phase separation temperature, implying environmental influences on lipid physical properties. The relationship of these results to high and low temperature tolerance is discussed. 相似文献
13.
Summary The temperatures at which chlorophyll fluorescence yield is substantially increased and the temperatures at which the quantum yield for CO2 uptake is irreversibly inhibited were measured for three shortgrass prairie species. The experimental taxa include, a cool season species (Agropyron smithii), a warm season species (Bouteloua gracilis), and a species which grows throughout the cool and warm seasons (Carex stenophylla). Agropyron smithii exhibited lower high temperature damage thresholds (43°C in cool grown plants, 46°C in warm grown plants), relative to the other two species. Bouteloua gracilis exhibited the highest tolerance to high temperature, with threshold values being 44–49°C for cool grown plants and 53–55°C for warm grown plants. Carex stenophylla exhibited threshold values which were intermediate to the other two species (43–47°C for cool grown plants, and 51–53°C for warm grown plants). Seasonal patterns in the fluorescence rise temperatures of field grown plants indicated acclimation to increased temperatures in all three species. The results demonstrate a correlation between the high temperature thresholds for damage to the photosynthetic apparatus, and in situ seasonal phenology patterns for the three species. 相似文献
14.
Vincent Le Moing Fran?ois Alla Thanh Doco-Lecompte Fran?ois Delahaye Lionel Piroth Catherine Chirouze Pierre Tattevin Jean-Philippe Lavigne Marie-Line Erpelding Bruno Hoen Fran?ois Vandenesch Xavier Duval VIRSTA study group 《PloS one》2015,10(5)
ObjectivesTo update the epidemiology of S. aureus bloodstream infection (SAB) in a high-income country and its link with infective endocarditis (IE).MethodsAll consecutive adult patients with incident SAB (n = 2008) were prospectively enrolled between 2009 and 2011 in 8 university hospitals in France.ResultsSAB was nosocomial in 54%, non-nosocomial healthcare related in 18% and community-acquired in 26%. Methicillin resistance was present in 19% of isolates. SAB Incidence of nosocomial SAB was 0.159/1000 patients-days of hospitalization (95% confidence interval [CI] 0.111-0.219). A deep focus of infection was detected in 37%, the two most frequent were IE (11%) and pneumonia (8%). The higher rates of IE were observed in injecting drug users (IE: 38%) and patients with prosthetic (IE: 33%) or native valve disease (IE: 20%) but 40% of IE occurred in patients without heart disease nor injecting drug use. IE was more frequent in case of community-acquired (IE: 21%, adjusted odds-ratio (aOR) = 2.9, CI = 2.0-4.3) or non-nosocomial healthcare-related SAB (IE: 12%, aOR = 2.3, CI = 1.4-3.5). S. aureus meningitis (IE: 59%), persistent bacteremia at 48 hours (IE: 25%) and C-reactive protein > 190 mg/L (IE: 15%) were also independently associated with IE. Criteria for severe sepsis or septic shock were met in 30% of SAB without IE (overall in hospital mortality rate 24%) and in 51% of IE (overall in hospital mortality rate 35%).ConclusionSAB is still a severe disease, mostly related to healthcare in a high-income country. IE is the most frequent complication and occurs frequently in patients without known predisposing conditions. 相似文献
15.
John A. Stephenson Kerry P. Reese Peter Zager Patricia E. Heekin Pamela J. Nelle Ashley Martens 《The Journal of wildlife management》2011,75(6):1315-1323
Understanding survival and cause-specific mortality of native and translocated animals can help biologists design more effective recovery programs. We estimated survival rates for 181 native mountain quail (Oreortyx pictus) in west-central Idaho from 1992 to 1996 and for 199 translocated mountain quail in western Idaho and eastern Washington in 2005 and 2006. Spring–summer survival of native birds over 4 yr ranged from 0.210 (SE = 0.116) to 0.799 (SE = 0.103) and fall–winter survival in 2 yr was 0.523 (SE = 0.089) and 0.244 (SE = 0.084). Annual survival rates were 0.418 (SE = 0.088) and 0.174 (SE = 0.065). Spring–summer survival rate of translocated birds was 0.215 (SE = 0.044) in 2005 and 0.059 (SE = 0.021) in 2006. We modeled biweekly survival as a function of sex, age, movement rate, native versus translocated status, and linear time trend, and then we added year and 3 weather covariates (mean biweekly precipitation and maximum and minimum temperatures). Year and climate variables improved the a priori top model which included movement rate and native versus translocated status. Higher mortality rates due to predation coincided with movements to breeding habitat in late winter, periods of higher temperatures in the spring and summer, and periods of higher precipitation and colder temperatures during the fall–winter seasons. High movement rates of native birds in winter to avoid snow and by translocated birds when dispersing may have led to greater exposure to predators and consequently lower survival rates. Mountain quail can experience low and variable survival, stressing the potential need for multiple years of releases in restoration efforts in the eastern portion of their range. More attention is needed to identify optimal habitat (including nest sites) for restoring mountain quail populations to reduce movements, lower mortality risks, and provide conditions for withstanding periods of unfavorable weather. © 2011 The Wildlife Society. 相似文献
16.
The purpose of this study was to examine the running performances and associated thermoregulatory responses of African and Caucasian runners in cool and warm conditions. On two separate occasions, 12 (n = 6 African, n = 6 Caucasian) well-trained men ran on a motorized treadmill at 70% of peak treadmill running velocity for 30 min followed by an 8-km self-paced performance run (PR) in cool (15 degrees C) or warm (35 degrees C) humid (60% relative humidity) conditions. Time to complete the PR in the cool condition was not different between groups ( approximately 27 min) but was significantly longer in warm conditions for Caucasian (33.0 +/- 1.6 min) vs. African (29.7 +/- 2.3 min, P < 0.01) runners. Rectal temperatures were not different between groups but were higher during warm compared with cool conditions. During the 8-km PR, sweat rates for Africans (25.3 +/- 2.3 ml/min) were lower compared with Caucasians (32.2 +/- 4.1 ml/min; P < 0.01). Relative rates of heat production were less for Africans than Caucasians in the heat. The finding that African runners ran faster only in the heat despite similar thermoregulatory responses as Caucasian runners suggests that the larger Caucasians reduce their running speed to ensure an optimal rate of heat storage without developing dangerous hyperthermia. According to this model, the superior running performance in the heat of these African runners can be partly attributed to their smaller size and hence their capacity to run faster in the heat while storing heat at the same rate as heavier Caucasian runners. 相似文献
17.
Filling the interspace—restoring arid land mosses: source populations,organic matter,and overwintering govern success
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Biological soil crusts contribute to ecosystem functions and occupy space that could be available to invasive annual grasses. Given disturbances in the semiarid shrub steppe communities, we embarked on a set of studies to investigate restoration potential of mosses in sagebrush steppe ecosystems. We examined establishment and growth of two moss species common to the Great Basin, USA: Bryum argenteum and Syntrichia ruralis from two environmental settings (warm dry vs. cool moist). Moss fragments were inoculated into a third warm dry setting, on bare soil in spring and fall, both with and without a jute net and with and without spring irrigation. Moss cover was monitored in spring seasons of three consecutive years. Both moss species increased in cover over the winter. When Bryum received spring irrigation that was out of sync with natural precipitation patterns, moss cover increased and then crashed, taking two seasons to recover. Syntrichia did not respond to the irrigation treatment. The addition of jute net increased moss cover under all conditions, except Syntrichia following fall inoculation, which required a second winter to increase in cover. The warm dry population of Bryum combined with jute achieved on average 60% cover compared to the cool moist population that achieved only 28% cover by the end of the study. Differences were less pronounced for Syntrichia where moss from the warm dry population with jute achieved on average 51% cover compared to the cool moist population that achieved 43% cover by the end of the study. Restoration of arid land mosses may quickly protect soils from erosion while occupying sites before invasive plants. We show that higher moss cover will be achieved quickly with the addition of organic matter and when moss fragments originate from sites with a climate that is similar to that of the restoration site. 相似文献
18.
Nowadays, a quest for efficient greenhouse heating strategies, and their related effects on the plant’s performance, exists.
In this study, the effects of a combination of warm days and cool nights in autumn and spring on the photosynthetic activity
and efficiency of Phalaenopsis were evaluated; the latter, being poorly characterised in plants with crassulacean acid metabolism (CAM) and, to our knowledge,
not reported before in Phalaenopsis. 24-h CO2 flux measurements and chlorophyll (Chl) fluorescence analyses were performed in both seasons on Phalaenopsis ‘Hercules’ exposed to relatively constant temperature regimes, 25.5/24.0°C (autumn) and 30/27°C (spring) respectively, and
distinctive warm day/cool night temperature regimes, 27/20°C (autumn) and 36/24°C (spring), respectively. Cumulated leaf net
CO2 uptake of the distinctive warm day/cool night temperature regimes declined with 10–16% as compared to the more constant temperature
regimes, while the efficiency of carbon fixation revealed no substantial differences in both seasons. Nevertheless, a distinctive
warm day/cool night temperature regime seemed to induce photorespiration. Although photorespiration is expected not to occur
in CAM, the suppression of the leaf net CO2 exchange during Phase II and Phase IV as well as the slightly lower efficiency of carbon fixation for the distinctive warm
day/cool night temperature regimes confirms the involvement of photorespiration in CAM. A seasonal effect was reflected in
the leaf net CO2 exchange rate with considerably higher rates in spring. In addition, sufficiently high levels of photosynthetically active
radiation (PAR) in spring led to an efficiency of carbon fixation of 1.06–1.27% which is about twice as high than in autumn.
As a result, only in the case where a net energy reduction between the temperature regimes compensates for the reduction in
net CO2 uptake, warm day/cool night temperature regimes may be recommended as a practical sustainable alternative. 相似文献
19.
Aleš Urban Hana Davídkovová Jan Kyselý 《International journal of biometeorology》2014,58(6):1057-1068
Several studies have examined the relationship of high and low air temperatures to cardiovascular mortality in the Czech Republic. Much less is understood about heat-/cold-related cardiovascular morbidity and possible regional differences. This paper compares the effects of warm and cold days on excess mortality and morbidity for cardiovascular diseases (CVDs) in the city of Prague and a rural region of southern Bohemia during 1994–2009. Population size and age structure are similar in the two regions. The results are evaluated for selected population groups (men and women). Excess mortality (number of deaths) and morbidity (number of hospital admissions) were determined as differences between observed and expected daily values, the latter being adjusted for long-term changes, annual and weekly cycles, and epidemics of influenza/acute respiratory infections. Generally higher relative excess CVD mortality on warm days than on cold days was identified in both regions. In contrast to mortality, weak excess CVD morbidity was observed for both warm and cold days. Different responses of individual CVDs to heat versus cold stress may be caused by the different nature of each CVD and different physiological processes induced by heat or cold stress. The slight differences between Prague and southern Bohemia in response to heat versus cold stress suggest the possible influence of environmental and socioeconomic factors such as the effects of urban heat island and exposure to air pollution, lifestyle differences, and divergence in population structure, which may result in differing vulnerability of urban versus rural population to temperature extremes. 相似文献
20.
Cruz-Gonzalez I Pabón P Rodríguez-Barbero A Martín-Moreiras J Pericacho M Sánchez PL Ramirez V Sánchez-Ledesma M Martín-Herrero F Jiménez-Candil J Maree AO Sánchez-Rodríguez A Martín-Luengo C López-Novoa JM 《Journal of cellular and molecular medicine》2008,12(3):955-961
Endoglin is a proliferation-associated and hypoxia-inducible protein expressed in endothelial cells. The levels of soluble circulating endoglin and their prognostic significance in patients with acute myocardial infarction (AMI) are not known. In this observational prospective study serum endoglin levels were measured by ELISA in 183 AMI patients upon admission to hospital and 48 hrs later and in 72 healthy controls. Endoglin levels in AMI patients on admission were significantly lower than in healthy controls (4.25 +/- 0.99 ng/ml versus 4.59 +/- 0.87 ng/ml; P= 0.013), and decreased further in the first 48 hours (3.65 +/- 0.76 ng/ml, P < 0.001). Upon follow-up (median 319 days), patients who died had a significantly greater decrease in serum endoglin level over the first 48 hrs than those who survived (1.03 +/- 0.91 versus 0.54 +/- 0.55 ng/ml; P= 0.025). Endoglin decrease was an independent predictor of short-term (30 days) (hazard ratio 2.33;95% CI = 1.27-4.23; P= 0.006) cardiovascular mortality, and also predicts overall cardiovascular mortality during the follow-up (median 319 days) in AMI patients (hazard ratio 2.13;95% CI = 1.20-3.78; P= 0.01). In conclusion, early changes in serum endoglin may predict mortality after AMI. 相似文献