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Heat Exposure (heat + exposure)
Selected AbstractsSoil seed banks in Mediterranean Aleppo pine forests: the effect of heat, cover and ash on seedling emergenceJOURNAL OF ECOLOGY, Issue 4 2000Ido Izhaki Summary 1 ,East Mediterranean Aleppo pine (Pinus halepensis) forests are subjected to periodic stand-replacing fires. We simulated two of the effects of fire on the germinable soil seed bank in four pine stands on Mt. Carmel, Israel, that differed in their post-fire ages. Soil samples were heated to 100 °C, or covered by pine ash. Vermiculite was used to simulate litter cover. 2 ,Heat exposure increased overall seedling density, richness and taxon diversity in all stands, but density of annual taxa (e.g. grasses and legumes) were not clearly affected. 3 ,Ash cover dramatically decreased germination of all taxa and highest germination was achieved with heating and no cover. Vermiculite cover resulted in intermediate germination levels. 4 ,The combined effect of heat exposure and ash cover, simulating a post-fire situation under a canopy of pine, reduced the germination level of all taxa in the soil seed bank. However, it also creates conditions that facilitate the establishment of pine seedlings from the canopy stored seed bank. [source] ORIGINAL ARTICLE: Ileal endogenous amino acid flow of broiler chickens under high ambient temperatureJOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 5 2010A. F. Soleimani Summary High environmental temperature has detrimental effects on the gastrointestinal tract of poultry. An experiment was conducted to determine the effect of acute heat stress on endogenous amino acid (EAA) flow in broiler chickens. A total of 90, day-old broiler chicks were housed in battery cages in an environmentally controlled chamber. Chicks were fed a nitrogen-free diet on day 42 following either no heat exposure (no-heat) or 2 weeks exposure to 35 ± 1 °C for 3 h from days 28 to 42 (2-week heat) or 1 week exposure to 35 ± 1 °C for 3 h from days 35 to 42 (1 week heat). The most abundant amino acid in the ileal flow was glutamic acid, followed by aspartic acid, serine and threonine in non-heat stressed group. The EAA flow in 1-week heat and 2-week heat birds were significantly (p < 0.05) higher than those under no heat exposure (14682, 11161 and 9597 mg/kg of dry matter intake respectively). Moreover, the EAA flow of 2-week heat group was less than 1-week heat group by approximately 36%. These observations suggest that the effect of heat stress on EAA flow is mostly quantitative; however, heat stress may also alter the content of EAA flow qualitatively. [source] Soil seed banks in Mediterranean Aleppo pine forests: the effect of heat, cover and ash on seedling emergenceJOURNAL OF ECOLOGY, Issue 4 2000Ido Izhaki Summary 1 ,East Mediterranean Aleppo pine (Pinus halepensis) forests are subjected to periodic stand-replacing fires. We simulated two of the effects of fire on the germinable soil seed bank in four pine stands on Mt. Carmel, Israel, that differed in their post-fire ages. Soil samples were heated to 100 °C, or covered by pine ash. Vermiculite was used to simulate litter cover. 2 ,Heat exposure increased overall seedling density, richness and taxon diversity in all stands, but density of annual taxa (e.g. grasses and legumes) were not clearly affected. 3 ,Ash cover dramatically decreased germination of all taxa and highest germination was achieved with heating and no cover. Vermiculite cover resulted in intermediate germination levels. 4 ,The combined effect of heat exposure and ash cover, simulating a post-fire situation under a canopy of pine, reduced the germination level of all taxa in the soil seed bank. However, it also creates conditions that facilitate the establishment of pine seedlings from the canopy stored seed bank. [source] Impact of Thermal Treatment on Color and Pigment Pattern of Red Beet (Beta vulgaris L.) PreparationsJOURNAL OF FOOD SCIENCE, Issue 6 2004K.M. Herbach ABSTRACT: The impact of heating at 85°C during 8 h on overall color and betalain pattern of red beet (Beta vulgaris L. ssp. vulgaris) juice was investigated. Although the hue angle of 358° in fresh juice was indicative of the typical red-purple appearance, heating for 8 h induced an unexpected shift to 62° resulting in a yellow-orange solution. To monitor the underlying structural alterations of betalains, a new high-performance liquid chromatography separation compatible with mass spectrometry was developed. Applying this method, 2 novel yellow neobetanin structures and 2 orange-red betanin degradation products were preliminarily identified, and neobetanin formation resulting from heat exposure was proven for the 1st time. These 5 compounds were held responsible for the orange shift of red beet juice during thermal treatment. The relevance of these findings for industrial beet processing was demonstrated by comparison of pigment patterns of heated red beet juice samples and a commercial concentrate. On the basis of these results, a scheme for the thermal degradation of betanin is proposed. [source] The influence of artificial aging on the microstructure, mechanical properties, corrosion, and environmental cracking susceptibility of a 7075 friction-stir-weldMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 10 2007C. S. Paglia The influence of overaging to the T7451 temper on the microstructure, the mechanical properties, and the corrosion susceptibility of friction-stir-welded 7075 aluminum alloy was investigated by means of transmission electron microscope (TEM), SEM investigations, constant extension rate tests (CERT), alternate immersion tests, and potentiodynamic scans. The overaging that occurs during welding within the heat-affected zones of the friction-stir-welded 7075-O tempered plates promotes a slight formation of intragranular and grain boundary precipitates and increases the mechanical as well as the corrosion resistance properties as compared to the T7451 welded plates. The "double" overaging treatment, consisting of the T7451 temper and the thermal transient experienced by the heat-affected zones of the 7075-T7451 welded plates, increases the size of the intragranular and the grain boundary precipitates as well as the precipitate-free zones. These facts decrease the mechanical and corrosion properties of the 7075-T7451 weld. The T7451 thermal treatment applied after the welding of the 7075-O plates promotes the high presence of small precipitates and reduces the size of the precipitate-free zones. This fact increases the general corrosion resistance, but decreases the mechanical properties. Therefore, the corrosion as well as the mechanical properties are greatly correlated with minute changes in the microstructure, which can arise by short-term heat exposure as for instance during welding. It was also found that the environmental susceptibility measured by means of CERTs may be influenced by "solution-strengthening" corrosion mechanisms which increase the strain. This fact is present in weld microzones particularly susceptible to corrosion. [source] Latest news and product developmentsPRESCRIBER, Issue 19 2008Article first published online: 16 OCT 200 ARBs less effective than ACE inhibitors? The efficacy of angiotensin-II receptor blockers (ARBs) in preventing cardiovascular events in high-risk patients has been challenged by the findings of a large randomised trial (Lancet 2008 published online; doi 10.1016/ S0140-6736(08)61242-8). In the TRANSCEND trial, 5926 patients with cardiovascular disease or diabetes with end-organ damage who could not tolerate ACE inhibitor therapy were randomised to placebo or telmisartan (Micardis) 80mg per day in addition to standard therapies. After 56 months, mean blood pressure was lower with telmisartan (by 4.0/2.2mmHg) but there were no significant differences between telmisartan and placebo in the risk of cardiovascular events , a composite of cardiovascular death, myocardial infarction, stroke, or hospitalisation for heart failure. Hospitalisation for cardiovascular reasons were slightly but significantly reduced by telmisartan (33 vs 30 per cent). MHRA: fentanyl patch errors potentially fatal Errors in dosing, accidental exposure and enhanced absorption from heat exposure have resulted in life-threatening and fatal incidents with transdermal fentanyl, warns the MHRA in its latest Drug Safety Update (September 2008). There is also evidence that fentanyl patches are being prescribed for nonlicensed indications, including treatment of opioid-naive patients. Other topics in this issue include managing adverse reactions to HPV vaccine and an update on new cases of progressive multifocal leucoencephalopathy associated with natalizumab (Tysabri). Call for DURG research The Drug Utilisation Research Group is inviting abstracts for oral and poster presentations at its 20th annual meeting on 5 February 2009. The theme of the morning session is ,Whose prescribing budget is it anyway?'. Abstracts will be accepted on any drug utilisation research studies and will be published in the Journal of Pharmacoepidemiology and Drug Safety. Information is available at www.durg.org.uk the deadline for submissions is 1 December. Early bromocriptine no benefit in Parkinson's Initiating treatment of Parkinson's disease with the dopamine agonist bromocriptine offers no long-term benefit compared with levodopa, the UK Parkinson's Disease Research Group trial has shown (Neurology 2008;71:474-80). After 14 years' follow-up of 166 patients, there were no differences in the prevalence of motor complications, dementia or mortality, but levodopa was associated with superior scores of disability and physical functioning. The authors say the belief that early dopamine agonist treatment is neuroprotective in Parkinson's disease should be abandoned. Ezetimibe with statin cancer risk ,not credible' Analysis of data pooled from two large trials provides ,no credible evidence' that ezetimibe (Ezetrol) is associated with an increased risk of cancer when added to statin therapy (N Engl J Med 2008 published online; doi 10.1056/NEJMsa0806603). A possible link with increased risk of cancer with ezetimibe plus simvastatin was suggested by the SEAS trial (N Engl J Med 2008 published online; doi 10.1056/NEJMoa 0804602). This hypothesis was tested in two trials involving more than 20 500 patients over 1.0-2.7 years. There was no excess of cancer overall or at particular sites; cancer deaths were more numerically but not significantly higher with ezetimibe and there was no evidence of increased risk with duration of treatment. Telmisartan provides no advantage after stroke Adding telmisartan (Micardis) to standard treatment after ischaemic stroke does not reduce morbidity, US investigators report (N Engl J Med 2008 published online; doi 10.1056/NEJMoa 0804593). A total of 20 332 patients with recent ischaemic stroke were randomised to placebo or telmisartan 80mg per day in addition to antiplatelet therapy and antihypertensive agents. After 2.5 years, blood pressure was 3.8/2.0mmHg lower in patients taking telmisartan but there were no significant differences from placebo in the risks of recurrent stroke, cardiovascular events or new-onset diabetes. Copyright © 2008 Wiley Interface Ltd [source] Productivity and energy partition of late lactation dairy cows during heat exposureANIMAL SCIENCE JOURNAL, Issue 1 2010Kyoung Hoon KIM ABSTRACT Three late-lactation Holstein cows were used to determine the effects of environmental temperature on performance and energy partitioning. Each cow was housed in a respiratory chamber for 30 consecutive days and exposed to three different conditions of environmental temperature: (i) 20°C and 20°C (20°C), (ii) 25°C and 20°C (25°C), (iii) 30°C and 25°C (30°C) during the day and night, respectively. The temperature was switched in an interval of 10 days. Humidity in the chamber was maintained at 55,65% through the entire experimental period. The daily mean as well as morning and evening rectal temperatures of Holstein cows increased linearly (P < 0.05) as chamber temperature increased. There was a significant linear reduction in dry matter (DM) intake (P < 0.05) and an increase in DM digestibility (P < 0.05). The response in milk yield, however, was not affected by heat stress. There were no significant differences among treatments for intake energy, heat production, net energy for lactation and net energy for gain. This results of this study disagreed with the assumption that late lactation cows gave priority to increasing body tissue at the expense of milk production under thermal stress. [source] Millimeter wave effects on electrical responses of the sural nerve in vivoBIOELECTROMAGNETICS, Issue 3 2010Stanislav I. Alekseev Abstract Millimeter wave (MMW, 42.25,GHz)-induced changes in electrical activity of the murine sural nerve were studied in vivo using external electrode recordings. MMW were applied to the receptive field of the sural nerve in the hind paw. We found two types of responses of the sural nerve to MMW exposure. First, MMW exposure at the incident power density ,45,mW/cm2 inhibited the spontaneous electrical activity. Exposure with lower intensities (10,30,mW/cm2) produced no detectable changes in the firing rate. Second, the nerve responded to the cessation of MMW exposure with a transient increase in the firing rate. The effect lasted 20,40,s. The threshold intensity for this effect was 160,mW/cm2. Radiant heat exposure reproduced only the inhibitory effect of MMW but not the transient excitatory response. Depletion of mast cells by compound 48/80 eliminated the transient response of the nerve. It was suggested that the cold sensitive fibers were responsible for the inhibitory effect of MMW and radiant heat exposures. However, the receptors and mechanisms involved in inducing the transient response to MMW exposure are not clear. The hypothesis of mast cell involvement was discussed. Bioelectromagnetics 31:180,190, 2010. © 2009 Wiley-Liss, Inc. [source] Exercise-induced hyperthermia in childhood: a case report and pilot studyACTA PAEDIATRICA, Issue 7 2009T Kallinich Abstract Hyperthermia is characterized by an increase of body core temperature due to exogenous heat exposure and/or endogenous heat production. Contrary to fever the hypothalamic-controlled temperature set point remains unchanged. Aim: To demonstrate that exercise-induced hyperthermia is a common phenomenon in childhood. Case: We describe a 5-year-old boy, who attended our outpatient clinic with a 6-month observation period of exercise-induced hyperthermia with rectal temperatures up to 39.0°C. Characteristically temperature dropped to normal values after cessation of exercise. Method: In eight children aged 5,8, tympanic and rectal temperatures were measured before and after exercise. Results: The rectal temperature increases frequently after exercise (p < 0.001), whereas tympanic temperature did not (p = 0.2). Conclusion:, Benign hyperthermia should be considered in children with increased body temperature of unknown sources. The site of temperature measurement might be critical in the identification of this condition. [source] Millimeter wave effects on electrical responses of the sural nerve in vivoBIOELECTROMAGNETICS, Issue 3 2010Stanislav I. Alekseev Abstract Millimeter wave (MMW, 42.25,GHz)-induced changes in electrical activity of the murine sural nerve were studied in vivo using external electrode recordings. MMW were applied to the receptive field of the sural nerve in the hind paw. We found two types of responses of the sural nerve to MMW exposure. First, MMW exposure at the incident power density ,45,mW/cm2 inhibited the spontaneous electrical activity. Exposure with lower intensities (10,30,mW/cm2) produced no detectable changes in the firing rate. Second, the nerve responded to the cessation of MMW exposure with a transient increase in the firing rate. The effect lasted 20,40,s. The threshold intensity for this effect was 160,mW/cm2. Radiant heat exposure reproduced only the inhibitory effect of MMW but not the transient excitatory response. Depletion of mast cells by compound 48/80 eliminated the transient response of the nerve. It was suggested that the cold sensitive fibers were responsible for the inhibitory effect of MMW and radiant heat exposures. However, the receptors and mechanisms involved in inducing the transient response to MMW exposure are not clear. The hypothesis of mast cell involvement was discussed. Bioelectromagnetics 31:180,190, 2010. © 2009 Wiley-Liss, Inc. [source] The effect of fever, febrile illnesses, and heat exposures on the risk of neural tube defects in a Texas-Mexico border populationBIRTH DEFECTS RESEARCH, Issue 10 2004Lucina Suarez Abstract BACKGROUND Hyperthermia produces neural tube defects (NTDs) in a variety of animal species. Elevated maternal body temperatures may also place the developing human embryo at risk. We examined the relation between maternal hyperthermia and the development of NTDs in a high-risk Mexican-American population. METHODS Case-women were Mexican-American women with NTD-affected pregnancies who resided and delivered in any of the 14 Texas counties bordering Mexico, during 1995,2000. Control-women were randomly selected from study area residents delivering normal live births, frequency-matched to cases by hospital and year. Information on maternal fevers, febrile illnesses, exposures to heat generated from external sources, and hyperthermia-inducing activities was gathered through in-person interviews, conducted about six weeks postpartum. RESULTS The risk effect (OR) associated with maternal fever in the first trimester, compared to no fever, was 2.9 (95% CI, 1.5,5.7). Women taking fever-reducing medications showed a lower risk effect (OR, 2.4; 95% CI, 1.0,5.6) than those who did not (OR, 3.8; 95% CI, 1.4,10.9). First-trimester maternal exposures to heat devices such as hot tubs, saunas, or electric blankets were associated with an OR of 3.6 (95% CI, 1.1,15.9). Small insignificant effects were observed for activities such as cooking in a hot kitchen (OR, 1.6; 95% CI, 1.0,2.6) and working or exercising in the sun (OR, 1.4; 95% CI, 0.9,2.2). CONCLUSIONS Maternal hyperthermia increases the risk for NTD-affected offspring. Women intending to become pregnant should avoid intense heat exposures, carefully monitor and manage their febrile illnesses, and routinely consume folic acid supplements. Birth Defects Research (Part A), 2004. © 2004 Wiley-Liss, Inc. [source] | |||||||||||||