Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Temperature environment”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 1,045 records · Page 58Linked to original sources
PubMed2002

Drinking water temperature effects on laying hens subjected to warm cyclic environments.

Two experiments were conducted to evaluate the effects of drinking water temperature (Tw) on laying hens subjected to warm cyclic air temperature (Ta) conditions. Each experiment consisted of a 1-wk acclimation under thermoneutrality (TN) (Ta = Tw = 21 C), a 4-wk heat exposure or treatment period, and a 2-wk recovery under TN. Each experiment involved 24 individually caged hens at the initial age of 29 wk (Experiment 1) or 30 wk (Experiment 2). In Experiment 1, Tw of 18 or 27 C was provided to 12 birds per Tw regimen under a diurnal Ta of 27 to 35 C (daily mean of 31 C). In Experiment 2, Tw of 15, 19, 23, or 27 C was provided to six birds per Tw regimen under a diurnal Ta of 27 to 38 C (daily mean of 32.5 C). Experiment 1 showed that Tw of 18 C enhanced hourly and daily feed and water intake during the first 2 wk of heat exposure, as compared with Tw of 27 C. Experiment 2 showed that daily feed and water intake were greatest for hens in the 23 C Tw regimen and least for hens in the coolest or warmest Tw regimens. Reduction in daily feed intake with increase in daily mean Ta ranged from 2.0 to approximately 3.2 g/C-day (first week of heat exposure) to 1.1 to approximately 1.9 g/C-day (fourth week of heat exposure). Water to feed intake ratio was 1.8 to approximately 2.0 during acclimation and recovery, but increased to 3.0 to approximately 3.4 during heat exposure. Internal egg quality parameters were in general unaffected by Tw. The two warmer Tw regimens in Experiment 2 had less reduction in egg size than did the two cooler Tw. In both experiments, hens displayed anticipatory increase in feed and water intake 2 to 3 h prior to lights-off. However, the stimulus of lights-on did not elicit a strong return to feed and water consumption as typically seen in broilers. The results revealed the potential existence of an optimal Tw range (near 23 C) for heat-chal lenged laying hens. Larger-scale tests are warranted to further verify the findings.

Acclimatization↗
PubMed1996

The importance of restoration of the atmospheric electrical environment in closed Bioregenerative Life Supporting Systems.

Earth based Bioregenerative Life Supporting Systems (BLSS) are subject to 4 main physical factors: gravity, light, temperature and electrical environment. The first 3 are obvious to everyone, the Electrical Environment (EE) is not under the majority of prevailing conditions perceived directly by our senses. The EE is one of the important physical factors directly influencing some plants and in a less obvious way also the majority of plants. There are only two long range forces in nature: the electromagnetic and the gravitational forces. Gravity is very much weaker than the electromagnetic forces FG/FEL=10(-38), where FG is the gravitational Force and FEL are the electromagnetic Forces. The atmospheric electric field prevails all the time over the entire Earth with a mean intensity of 130 V/m. It is therefore a potent factor which may be used by some plants exposed throughout their entire life time to the atmospheric electric field. What effect should the normal atmospheric electric field have on plants? All living plants are good electrical conductors for electrostatic fields. The plants distort the normally vertical field lines, which have to be perpendicular to the plant tissue everywhere in order to avoid the extraction of energy from the field. The meristems concentrate the field lines, thus the electrically charged nutrients are supplied to the growing parts of the plant exposed to the field. This results in electrotropism in some plants. It is very well known that plants do have adaptive capabilities as compared to animals, it is important for their survival, because they cannot run away from trouble. It is found by careful observations of the behaviour of different plants that some plants do respond to the presence of the atmospheric electric field while other plants exposed to the same environment are indifferent to the atmospheric electric field. The plants growing in the Biosphere II were shielded by the metal structure of the Biosphere II. Because these plants which do make use of the atmospheric electric field are also to be found in the Biosphere II and must be deprived of this natural atmospheric electric field and in consequence of some of their natural nutrients. I have experimental evidence that at least some plants do respond to the atmospheric electric field. This effect is the most likely cause of the oxygen depletion and of the carbon dioxide accumulation in Biosphere II. Under the micro gravity encountered in space habitats the restoration of electric fields is even more important for plant growth than it is on the Earth.

Ecological Systems, Closed↗
PubMed1999

Preterm infant thermal care: differing thermal environments produced by air versus skin servo-control incubators.

OBJECTIVE: Incubator thermal environments produced by skin versus air servo-control were compared. STUDY DESIGN: Infant abdominal skin and incubator air temperatures were recorded from 18 infants in skin servo-control and 14 infants in air servo-control (26- to 29-week gestational age, 14 +/- 2 days postnatal age) for 24 hours. Differences in incubator and infant temperature, neutral thermal environment (NTE) maintenance, and infant and incubator circadian rhythm were examined using analysis of variance and scatterplots. RESULTS: Skin servo-control resulted in more variable air temperature, yet more stable infant temperature, and more time within the NTE. Circadian rhythm of both infant and incubator temperature differed by control mode and the relationship between incubator and infant temperature rhythms was a function of control mode. CONCLUSION: The differences between incubator control modes extend beyond temperature stability and maintenance of NTE. Circadian rhythm of incubator and infant temperatures is influenced by incubator control.

Body Temperature Regulation↗
PubMed1981

Effect of temperature on benzo[a]pyrene-induced hyperplastic and neoplastic skin lesions in mice.

The time required for tumor development and death in inbred C3H/HeJ mice treated with 1.0 or 0.1 mg benzo(a)pyrene (BP) twice weekly was shortest in mice kept in a cool environment (CE), intermediate in mice kept in a normal temperature environment (NE), and longest in mice kept in a warm environment (WE). Incidence of tumors (predominantly squamous carcinomas) and mortality was 100% by 36 weeks in all environments in the high-dose group. In the low-dose group, by 36 weeks tumor incidence was least in the WE compared with that in the NE and CE. Squamous carcinomas predominated in the NE and CE, but the incidence of fibromas and epithelial hyperplasias exceeded that of squamous carcinomas in the WE. Cutaneous epithelial hyperplasia, considered a preneoplastic change, was evaluated by light and electron microscopy at weekly intervals for 70 days. Increased epidermal thickness was induced by the toluene (T) vehicle alone, was significantly enhanced by BP treatment, and was more severe in mice in the CE and NE than in the WE. Although epithelial hyperplasia induced by BP was interpreted as a preneoplastic lesion, no ultrastructural differences were detected between T- and BP-treated mice in any environment. Results indicated that WE diminished the preneoplastic proliferative response of skin to BP and subsequently delayed the onset of squamous carcinomas induced by high doses of BP and reduced the incidence of squamous carcinomas at low doses of BP.

Animals↗
PubMed2001

Decrease in intraoperative brain surface temperature in patients with subarachnoid haemorrhage.

BACKGROUND: Recent experimental and clinical evidence of hypothermic protection against neuronal injury creates new interests regarding human brain temperature. However, very little information is available for the brain temperature under certain pathological conditions. In this study, intra-operative brain temperature in patients with subarachnoid haemorrhage (SAH) is particularly addressed. METHODS: Brain surface temperature and oxygen saturation of jugular bulb (SjO2) were monitored during early surgery undergone within 48 hours after the onset in patients with SAH (n = 16). Those were also measured in patients with unruptured aneurysms during elective surgery as control (n = 15). FINDINGS: The brain surface temperature was significantly lower in SAH than control (35.3 +/- 0.8 vs. 36.1 +/- 0.5 degrees C, P < 0.01). The reduction in brain surface temperature was correlated with the severity of the Hunt and Kosnik's aneurysmal grade (r = 0.837, P < 0.01). SjO2 was significantly lower in SAH than control (51.5 +/- 7.3 vs. 68.5 +/- 7.6%, P < 0.01), and was positively correlated with brain surface temperature (r = 0.642, P < 0.01). INTERPRETATION: These results suggest that the brain temperature and/or the temperature gradient within the brain may be altered in an early period after SAH. Since brain temperature is determined by cerebral blood flow (CBF), metabolism, temperature of both circulating blood and surrounding environment, the brain surface temperature reduction may be explained by depressed CBF and metabolism in SAH.

Aneurysm, Ruptured↗
PubMed2001

Survival and growth of Salmonella and Listeria in the chicken breast patties subjected to time and temperature abuse under varying conditions.

Chicken breast patties were inoculated with a mixture of Salmonella Senftenberg, Salmonella Typhimurium, Salmonella Heidelberg, Salmonella Mission, Salmonella Montevideo, Salmonella California, and Listeria innocua. The initial inoculation of bacteria was approximately 10(7) log10 CFU/g. The inoculated patties were processed in a pilot-scale air convection oven at an air temperature of 177 degrees C, an air velocity of 9.9 m3/min, and a low (a wet bulb temperature of 48 degrees C) or high (a wet bulb temperature of 93 degrees C) humidity condition. The patties were processed to a final center temperature of 65 to 75 degrees C. The survivors of Salmonella and Listeria in the processed patties were evaluated. Processing humidity affected the survivors of bacteria. More survivors of Salmonella and Listeria (>2 logs) were obtained for the patties cooked at low humidity than at high humidity. After thermal processing, the patties were stored under air, vacuum, or CO2 at refrigerated (4 degrees C) or thermally abused (8 to 15 degrees C) temperatures. Storage temperature, time, and gas environment affected the bacteria growth. Higher storage temperature and longer storage time correlated to an increased growth of bacteria in the cooked chicken patties. Less Salmonella (2 logs) and Listeria (0.5 to 1 log) cells were obtained in the patties stored under vacuum than in air. Storing the patties in 30% CO2 reduced the growth of Salmonella more than 2 log10 CFU/g. At a CO2 level of 15%, 1 log10 CFU/g of reduction was obtained for Listeria in cooked chicken patties.

Aerobiosis↗
PubMed1991

Modifications to Thylakoid Composition during Development of Maize Leaves at Low Growth Temperatures.

The effects of reductions in growth temperature on the development of thylakoids of maize (Zea mays var LG11) leaves are examined. Thylakoids isolated from mesophyll cells of leaves grown at 17 degrees and 14 degrees C, compared with 25 degrees C, exhibited a decreased accumulation of many polypeptides, which was accompanied by a loss of activity of photosystems (PS) I and II. Probing the polypeptide profiles with a range of antibodies specific for thylakoid proteins demonstrated that a number of polypeptides encoded by the chloroplast genome failed to accumulate at low temperatures. Although thylakoid protein synthesis was reduced severely at 14 degrees C compared with 25 degrees C, major synthesis of both chloroplast and nuclear encoded polypeptides was detected. It is suggested that the lack of accumulation of some thylakoid proteins at low temperatures may be due to an inability to stabilize the proteins in the membranes. A number of thylakoid polypeptides were found to appear as the growth temperature was decreased. Analyses of pigments and polypeptides demonstrated that decreases in the photosystem reaction center core complexes occur relative to the light harvesting complex associated with PS II at reduced growth temperatures. Differential effects on the development of PSI and PSII were also observed, with PSII activity being preferentially reduced. Reductions in PSII content and activity occurred in parallel with decreases in the quantum yield and light-saturated rate of CO(2) assimilation. Fractionation of thylakoid pigment-protein complexes showed that the ratio of monomeric:oligomeric form of the light harvesting complex associated with PSII increased at low growth temperature, which is consistent with a chill-induced modification of thylakoid organization. Many, but not all, of the characteristic changes in thylakoid protein metabolism, which were observed when leaves were grown at low temperatures in controlled environments, were identified in leaves of a field maize crop during the early growing season when low temperatures were experienced by the crop. Chill-induced perturbations of thylakoid development can occur in the field in temperate regions and may have implications for the photosynthetic productivity of the crop.

Journal Article↗
PubMed2005

Mapping of quantitative trait loci associated with chilling tolerance in maize (Zea mays L.) seedlings grown under field conditions.

The effect of low growth temperature on morpho-physiological traits of maize was investigated by the means of a QTL analysis in a segregating F(2:3) population grown under field conditions in Switzerland. Chlorophyll fluorescence parameters, leaf greenness, leaf area, shoot dry weight, and shoot nitrogen content were investigated at the seedling stage for two years. Maize was sown on two dates in each year; thus, plants sown early were exposed to low temperature, whereas those sown later developed under more favourable conditions. The main QTLs involved in the functioning of the photosynthetic apparatus at low temperature were stable across the cold environments and were also identified under controlled conditions with suboptimal temperature in a previous study. Based on the QTL analysis, relationships between chlorophyll fluorescence parameters and leaf greenness were moderate. This indicates that the extent and functioning of the photosynthetic machinery may be under different genetic control. The functioning of the photosynthetic apparatus in plants developed at low temperature in the field did not noticeably affect biomass accumulation; since there were no co-locations between QTLs for leaf area and shoot dry weight, biomass accumulation did not seem to be carbon-limited at the seedling stage under cool conditions in the field.

Acclimatization↗
PubMed2000

Thermal stability of moniliformin at varying temperature, pH, and time in an aqueous environment.

Moniliformin (MON) is a widely occurring mycotoxin, produced mainly by Fusarium proliferatum and Fusarium subglutinans in corn, that has been shown to be acutely toxic for various animal species and is a suspected cause of Keshan disease in China. The effects of temperature (100, 125, and 150 degrees C) and pH (4, 7, and 9) on the stability of MON were determined in aqueous buffer solutions at processing times ranging from 10 to 60 min. The percentage of MON reduction was positively related to increasing temperature and pH. MON was most stable at pH 4. After 60 min at pH 4 and 150 degrees C, MON was reduced by only 5%. Heating at pH 10 caused major reduction of MON. After 60 min at pH 10 and 100, 125, and 150 degrees C, MON was reduced by 56, 72, and 83%, respectively. One trial done at 175 degrees C and pH 10 showed that less than 1% MON remained after 60 min of processing.

Cyclobutanes↗
PubMed1996

The effect of storage at various temperatures on blood alcohol concentration.

There is a paucity of data available on the effect of storage on blood alcohol concentration (BAC) at elevated temperatures. Changes in serum alcohol concentration (SAC) and BAC were studied. Serum samples spiked with alcohol in the presence or absence of preservative were stored at 26.7 degrees, 32.2 degrees or 37.8 degrees C respectively. Serum alcohol concentrations were determined daily on days 1 through 14, and on days 21 and 35. Under these controlled conditions, no significant change in SAC was observed at the aforementioned temperatures. Whole blood samples submitted from outside agencies were initially analyzed (day 1), then stored for 35 days at different elevated temperatures before a second analysis. The average loss in BAC was 19.20 +/- 15.6, 9.95 +/- 5.7, and 15.60 +/- 6.9% when the samples were stored at 26.7, 32.2 and 37.8 degrees C, respectively. The alcohol loss from whole blood samples may be attributed to chemical oxidation rather than to elevated temperatures. It is, therefore, concluded that a whole blood sample obtained from a living individual and stored in a locker, glove compartment or other environment where the temperature is elevated, may lose 10-19% of its alcohol content over 35 days of storage. On the other hand, when a serum or plasma sample is exposed to the same environment, no significant change in SAC was observed. The utility of this information is significant to the forensic toxicologist. The results of this study suggest that a whole blood sample analyzed after exposure to elevated temperature may have had, originally, a higher BAC.

Blood Preservation↗
PubMed1991

Clean rooms and itchy faces.

Seventy-one male employees whose working environment was a temperature and dust controlled low-humidity 'Clean Room' and 144 male employees working in a natural factory environment were compared by means of period percentage prevalences of occurrence, severity and frequency of subjective symptoms of facial dermatitis. Using a cross-sectional interviewer-administered questionnaire it was possible to assess the percentage prevalence of each of 3 facial dermatitis symptoms among both low humidity exposed and non-exposed workers. The two prevalences were compared by calculating a ratio (the percentage prevalence ratio or PPR) of the prevalence of symptoms in the exposed, to that in the non-exposed workforce. A confidence interval (CI) for the PPR was also calculated. For the symptom of itching, the PPR was 1.65 (CI 1.32-2.07) in favour of the study group, whilst for the symptoms of redness and urticaria the PPRs were 1.96 (CI 1.54-2.48) and 2.53 (CI 1.40-4.59) respectively. The occurrence of a greater prevalence of all symptoms in the low-humidity exposed workforce confirms the clinical and laboratory reports of previous workers. A comparison was also made between the two groups of workers of both the severity, and the frequency of occurrence of symptoms. Whilst there was no statistically significant difference between the exposed and non-exposed groups for prevalence of one symptom, among those who had experienced two symptoms there was a PPR of 2.43 (CI 1.37-4.30) between the two groups. Furthermore, among those workers who had experienced all 3 symptoms of facial dermatitis there was a PPR of 3.38 (CI 1.18-8.93) in favour of the low-humidity exposed workforce.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗