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At least 937 records · Page 52Linked to original sources
PubMed1985

Peroxidase Activity in Relation to Suberization and Respiration in White Spruce (Picea glauca [Moench] Voss) Seedling Roots.

Peroxidase (EC 1.11.1.7) activity is associated with suberization during endodermal development and metacutization in roots of white spruce (Picea glauca [Moench] Voss) seedlings. Histochemical analysis indicates a relationship between suberization and peroxidase activity, but peroxidase is ubiquitous. Increased peroxidase activity results from the induction of four anodic peroxidase isozymes in addition to quantitative increases in two anodic peroxidase isozymes. Four of these polymerized eugenol. Cold temperatures induce formation of two anodic isozymes and result in suberization. The increased peroxidase activity associated with suberization is correlated to residual respiration. In an attempt to elucidate this relationship, the effect of respiratory inhibitors on respiration and peroxidase activity are compared.

Journal Article↗
PubMed1990

Cold acclimation in Arabidopsis and wheat : a response associated with expression of related genes encoding ;boiling-stable' polypeptides.

Changes in gene expression occur during cold acclimation in a wide variety of plant species. Here we show that a number of the polypeptides encoded by cold-regulated (cor) genes of Arabidopsis thaliana L. (Heyn) and wheat share the unusual biochemical property that they remain soluble upon boiling in aqueous solution. Further, cDNA cloning in conjunction with Southern and Northern analyses indicate that wheat has a cor gene that is related to Arabidopsis cor47, a gene encoding a 47 kilodalton ;boiling-stable' COR polypeptide. We suggest it is likely that the boiling-stable COR polypeptides have a fundamental role in plants acclimating to cold temperatures and discuss the possibility that they may act as cryoprotectants.

Journal Article↗
PubMed1996

Ceramides are transported through the Golgi apparatus in human keratinocytes in vitro.

The intercellular lipid sheets of the stratum corneum constitute the epidermal permeability barrier that permits terrestrial life. Although lamellar granules are known to deliver the precursors of the stratum corneum lipids into the intercellular spaces, their site of origin remains unknown. Lamellar granules have characteristics of both secretory granules and lysosomes, which are known to originate from the Golgi apparatus in other cell types. Glucosylceramides, a major component of lamellar granule contents and the precursors of stratum corneum ceramides, have been found to be synthesized primarily in the early compartments of the Golgi apparatus in other cell types. We have investigated the transport and metabolism of a fluorescently labeled ceramide in human keratinocyte cultures using laser-scanning confocal microscopy and lipid analysis. We found that ceramide is metabolized to glucosylceramide and sphingomyelin as it passes through the Golgi apparatus and the metabolites are then delivered to the plasma membrane. Cold temperature, Brefeldin A, and monensin, all known to inhibit transport from the Golgi to the plasma membrane, prevented ceramide metabolites from appearing at the plasma membrane. Because glucosylceramides are one of the most important lipid constituents of lamellar granules, these results support the hypothesis that the Golgi is the origin of lamellar granules.

Biological Transport↗
PubMed1994

Reduced mite allergen levels in dwellings with mechanical exhaust and supply ventilation.

Seventy similar bungalows constructed between 1968 and 1970 in the same suburban area of Stockholm were investigated regarding the content of house dust mite allergen, absolute indoor humidity, type of ventilation and basement construction. Houses with mechanical exhaust and supply ventilation had an indoor humidity above 7 g/kg less often than houses without this type of ventilation (Odds ratio 0.1, 95% confidence interval 0.0-0.2). Furthermore, only five of the 24 houses with exhaust and supply ventilation contained mattress dust mite allergen concentrations exceeding the median value (98.5 ng/g) compared with 30 of 46 hours which did not have such ventilation (odds ratio = 0.1, C.I. 0.0-0.5). Houses with both natural ventilation and crawl space basement harboured significantly less mattress mite allergen than houses having the same type of ventilation, but with a concrete slab basement. In a cold temperature climate, type of building construction and ventilation seem to be important for the occurrence of house dust mite allergens in dwellings. Our results indicate that modern energy-efficient houses should be equipped with mechanical exhaust and supply ventilation to reduce indoor air humidity during the dry winter months and the risk of mite infestation.

Air Pollution, Indoor↗
PubMed2005

Improvement of semen quality by nocturnal scrotal cooling in oligozoospermic men with a history of testicular maldescent.

For infertile men with a history of testicular maldescent only few therapeutic options exist beside assisted reproduction. The aim of our study was to evaluate the influence of nocturnal scrotal cooling on semen quality in such patients presenting with oligozoospermia. Twenty infertile men with a history of testicular maldescent and oligozoospermia were included for nocturnal scrotal cooling over 12 weeks for every night. To increase nocturnal periscrotal air circulation we used a membrane pump connected via plastic tubes to receptacles placed in both groins. Semen analysis was performed at the beginning of the cooling period and at weeks 4, 8 and 12. Another 20 infertile patients with a history of testicular maldescent and oligozoospermia were followed without specific treatment and served as a retrospectively built control group. Scrotal cooling at night by means of a perigenital air stream resulted in a scrotal temperature drop by 0.8 degrees C (median). A significant increase in sperm concentration and total sperm count was achieved by nocturnal cooling after 8 weeks (p < 0.01; p < 0.05; respectively) and 12 weeks (p < 0.01; p < 0.01; respectively). The improvement of sperm motility and sperm morphology was statistically insignificant. The present study suggests nocturnal scrotal cooling as a therapeutic option to improve semen quality. In a further controlled prospective study the influence on pregnancy rates should be evaluated.

Adult↗
PubMed1988

The expression of CR1 and CR3 on non-modulated and modulated granulocytes of healthy blood donors as measured by flow cytofluorometry.

Complement receptors, CR1 and CR3, on neutrophils increase their cellular spontaneously at 37 degrees C or after mechanical stress during the cell preparation. We have established a cell preparation procedure and a cytofluorometric immunoassay method to evaluate the receptor expression in vivo in this study. The expression of CR1 and CR3 was studied after haemolysis in NH4Cl at different temperatures and incubation intervals. It was shown that cell preparation and receptor analysis must be performed at 15 degrees C or lower to avoid up-regulation of the receptor structures. Two minutes' incubation at 20 degrees C was sufficient to modulate the cells in this regard. Granulocytes from healthy blood donors were analysed and the mean fluorescence intensity (MFI), which reflects the number of receptors on the cell surface, showed a normal distribution for the CR1 (n = 158) and CR3 (n = 76) expression in the healthy population. The MFI of the two receptors showed a correlation (r = 0.71). Granulocytes from all donors could be modulated at 37 degrees C to a similar degree for both receptors (r = 0.76), despite the fact that they are supposed to be mobilized from different intracellular pools. A group of patients with localized inflammatory processes, such as sinusitis, differed from the healthy controls. In this group, the CR1 expression was not normally distributed, but 15 out of 26 patients (58%) had granulocytes with a CR1 expression exceeding the mean +/- SD of the normal population.

Adolescent↗
PubMed1992

Core temperature measured in the auricular canal: comparison between four different tympanic thermometers.

Four different tympanic thermometers, absorbing infra-red radiation, (FirstTemp, Diatek, Ivac and Genius) were studied. Variations from repeated measurements and reliability of tympanic temperature compared to oesophageal, rectal and pulmonary artery temperature were studied. Core temperature measured by the "FirstTemp" and the "Genius" thermometers showed slightly higher values than core temperature measured by oesophageal, rectal and pulmonary artery thermistors. Compared to oesophageal temperature "FirstTemp" showed 0.56 degrees C and "Genius" 0.28 degrees C higher values, while the "Diatek" and the "Ivac" gave slightly lower values (-0.5 degrees C and -0.28 degrees C). All four thermometers were found accurate for repeated measurement both in terms of standard deviation and coefficient of variance. All four tympanic thermometers showed good accuracy for changes in core temperatures compared to the reference thermistors (r2 values 0.96 for "FirstTemp", 0.88 for "Diatek", 0.96 for "IVAC" and 0.95 for "Genius"). The tympanic thermometer was found to be a valuable alternative for measuring core temperature in most clinical settings.

Body Temperature↗
PubMed1995

Effects of hypothermia on the elimination of ethanol, diazepam and oxazepam in rat liver slice incubations.

The elimination of ethanol, diazepam and oxazepam which are metabolised by different enzymes, has been studied for 30, 60, 90 and 120 min at 37, 27, 17 and 7 degrees C in rat liver slice incubations. Ethanol elimination followed zero-order kinetics at all temperatures, while the benzodiazepines consistently displayed first-order kinetics. No sign of phase transition was observed in the respective Arrhenius-plots. Ethanol elimination was more temperature dependent than the elimination of diazepam, while the elimination of oxazepam was little influenced by temperature. This is shown by the temperature ratios (Q10) and energies of activation (Ea) of 1.76, 1.56, 1.24 and 40.5, 31.9, 15.2 for ethanol, diazepam and oxazepam, respectively. This means that ethanol, diazepam and oxazepam elimination was reduced by 25, 22 and 14%, respectively, for each 10 degrees C of temperature reduction, which is considerably lower than the commonly observed 50% reduction of enzyme activity. We conclude that observations made for one drug on temperature dependent elimination may not apply to other drugs.

Animals↗
PubMed2004

Evolution of viviparity in horned lizards (Phrynosoma): testing the cold-climate hypothesis.

The cold-climate hypothesis for evolution of viviparity in squamates predicts a correlation between reproductive mode, altitude and latitude. I tested this prediction in horned lizards within a phylogenetic context. I first determined whether all viviparous species were monophyletic using Monte Carlo simulations. Secondly, I tested for presence of phylogenetic signal using randomization tests. Thirdly, I analysed relationships between reproductive mode and minimum, midpoint, and maximum altitudes and latitudes by computing conventional correlations and phylogenetically independent contrasts. Viviparous species do not form a monophyletic group suggesting viviparity evolved twice in the genus. Viviparity and altitude showed strong phylogenetic signal based on randomization tests and were significantly correlated, while latitude was not correlated with reproductive mode. This study partially supports the cold-climate model, but also suggests that altitude either may be a better predictor of cold temperatures or may be a surrogate for other selective factors important in the evolution of viviparity.

Adaptation, Physiological↗
PubMed1991

Fatal Yersinia enterocolitica (serotype 0:5,27) sepsis after blood transfusion.

Septicemia is a rare complication of blood transfusion. This is probably primarily due to the use of sealed disposable containers for blood collection and the storage of red cell-containing components at 4 degrees C. However, despite these measures, septicemia due to blood transfusion continues to occur. We report here a fatal case of Yersinia enterocolitica septicemia due to a contaminated unit of red cells which was collected from an apparently healthy, asymptomatic blood donor. The organism grows at cold temperature and multiplies during storage of red blood cell-containing components. Contaminated components do not show any visible abnormalities. The possibility of transfusion-transmitted Y. enterocolitica should be considered in patients who have symptoms of sepsis or shock following transfusion.

Female↗
PubMed1987

The interaction of cystamine with bovine brain tubulin.

Microtubule assembly in vitro is sensitive to a variety of non-physiological sulfhydryl-oxidizing agents, but the physiological significance of this phenomenon is unknown, since no physiological sulfhydryl-oxidizing agent has been shown to affect microtubule assembly in vitro. We have accordingly investigated the interaction of tubulin with cystamine. We have found that millimolar concentrations of cystamine inhibit microtubule assembly and induce an abnormal form of tubulin polymerization. Cystamine-induced polymerization does not occur at cold temperature. Formation of the polymer requires reaction of cystamine with two sulfhydryls which become available at 37 degrees C. In addition, cystamine reacts with about three sulfhydryls at 0 degrees C without inducing polymerization. This latter set of sulfhydryls appear to include one or both of the previously defined beta s sulfhydryls whose reaction with N, N'-ethylene-bis(iodoacetamide) is markedly inhibited by GTP, maytansine and vinblastine [Roach, M. C. & Luduena, R. F. (1984) J. Biol. Chem. 259, 12063-12071]. Cystamine's specific manner of interacting with tubulin suggests that it may mimic an endogenous sulfhydryl-directed regulator of microtubule assembly.

Animals↗
PubMed1977

Role of 5-hydroxytryptamine in morphine-, pethidine-, and methadone-induced hypothermia in rats at low ambient and room temperature.

1 The effect of morphine (10 or 20 mg/kg s.c.), pethidine (25 or 50 mg/kg s.c.) or methadone (4 or 8 mg/kg s.c.) on the body temperature of nontreated and p-chlorophenylalanine-pretreated rats was studied at room (21+/-0.2 degrees C) or low ambient (12+/-0.2 degrees C) temperature. 2 Neither pethidine nor smaller doses of morphine and methadone altered the mean rectal temperature of rats kept at room temperature but larger doses of morphine and methadone produced significant hypothermia. 3 All narcotic analgesics at doses used in the present investigation produced significant hypothermia in rats maintained in a low ambient temperature. The hypothermia was prevented by naloxone (1 mg/kg s.c.). 4 The administration of p-chlorophenylalanine (PCPA, 320 mg/kg i.p.) 48 h before the narcotic injection prevented the fall in body temperature both at room and low ambient temperature. 5 The administration of narcotic analgesics at doses, which when administered by themselves did not alter the body temperature of rats, produced significant hyperthermia in rats pretreated with PCPA. 6 When rats pretreated with PCPA were given 5-hydroxytryptophan (75 mg/kg s.c.) 30 min before narcotic administration, the usual response to narcotics was restored. 7 It appears that pethidine and methadone as well as morphine have both hyperthermic and hypothermic actions in rats and that 5-hydroxytryptamine may be involved in the narcotic-induced hypothermia not only at room temperature but also at low ambient temperature.

5-Hydroxytryptophan↗
PubMed1986

Survival of herpes simplex virus during cryosurgery with liquid nitrogen.

Because many viruses can survive extremely cold temperatures for extended periods of time, transmission of viral diseases from person to person using improper cryosurgical techniques might conceivably occur. To investigate the survivability of herpes simplex virus during cryotherapy, virus was first inoculated onto cotton-tipped applicators from either tissue cultures or from active lesions on patients, and then frozen for variable times in liquid nitrogen (-196 degrees C). After thawing, the applicators were cultured for the virus. The virus survived 12 hours of freezing (the maximum time of freezing in the study), which suggests that herpes simplex could be transmitted between cryosurgical patients if care is not taken to use separate cotton-tipped applicators and liquid nitrogen containers for each case.

Cryosurgery↗
PubMed1977

Effects of low tissue temperature on peripheral vascular control mechanisms.

Influence of low temperatures on vascular effects produced adrenaline, noradrenaline and vasoconstrictor nerve stimulation was studied in the feet of ducks. Observations were made on isolated preparations as well as on intact ducks with one or both feet immersed in ice-water. Isolated preparations were perfused with physiological solution and information on changes in vascular resistance obtained by direct measurement of flow changes during perfusion at constant pressure or by measuring changes in perfusion pressure during perfusion at constant flow. In intact ducks changes in blood flow were recorded as changes in digital subcutaneous tissue temperature. The study revealed that in the duck foot a relatively large fraction of the resistance to blood flow is found in the arteries of the proximal part of the foot. During cooling of the foot the influence of vasoconstrictor nerve stimulation and low doses of adrenaline and noradrenaline on vascular resistance is gradually lost, and it is negligible at temperatures below 8 degrees C. At these low temperatures the blood vessels stay dilated and blood flow through the web seems to be determined by the digital arterial blood pressure.

Animals↗
PubMed1993

Gross efficiency of muscular work during step exercise at -15 degrees C and 21 degrees C.

In an effort to assess the effect of ambient temperature on the gross efficiency (Effg) of step exercise 12 subjects performed a modified step test either at -15 degrees C or 21 degrees C ascending to three different heights (corresponding to light, moderate and heavy work), for 20 min each with a frequency of 18 steps min-1. Heart rate (HR), rectal temperature, skin temperatures and heat flux from skin were continuously measured. Oxygen consumption was measured during the last 5 min of each step height and perceptions of thermal sensation were recorded. The results indicate that, while using conventional clothing adequate in these temperatures, Effg is altered in a contradictory manner. At -15 degrees C Effg increased with increasing work load, whereas at 21 degrees C it decreased when the work load increased. The highest Effg (heavy work at -15 degrees C and light work at 21 degrees C) values are reflected as rather similar rectal temperatures. (37.4-37.7 degrees C) and identical mean skin temperatures (32.8 degrees C) as well as the same (slightly warm) thermal sensation of the legs. At -15 degrees C the lowest Effg in light work was probably due to the need to warm up the muscles. At 21 degrees C, on the contrary, the activation of heat dissipation systems was probably responsible for the lowest Effg in heavy work.

Adult↗