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At least 253 records · Page 14Linked to original sources
PubMed1987

Development at Cold-Hardening Temperatures : The Structure and Composition of Purified Rye Light Harvesting Complex II.

Light harvesting complex II (LHCII) was purified from cold-hardened (RH) and nonhardened winter rye (RNH) (Secale cereale L. cv Puma) employing a modified procedure of JJ Burke, CL Ditto, CJ Arntzen (Arch Biochem Biophys 187: 252-263). Triton X-100 solubilization of thylakoid membranes followed by three successive precipitations with 100 mm KCl and 10 mm MgCl(2) resulted in yields of up to 25% on a chlorophyll (Chl) basis and a purity of 90 to 95%, based on polypeptide analysis within 4 hours. Polypeptide and pigment analyses, 77 K fluorescence emission and room temperature absorption spectra indicate the LHCII obtained by this modified method is comparable to LHCII obtained by other published methods. Comparison of purified RH and RNH LHCII indicated no significant differences with respect to polypeptide, amino acid, Chl, and carotenoid compositions as well as no differences in lipid content. However, RH LHCII differed from RNH LHCII specifically with respect to the fatty acid composition of phosphatidyldiacylglycerol only. RH LHCII exhibited a 54% lower trans-Delta(3)-hexadecenoic acid level associated with PG and a 60% lower oligomeric LHCII:monomeric LHCII (LHCII(1):LHCII(3)) than RNH LHCII. Both RH and RNH LHCII exhibited a 5-fold enrichment in PG specifically. Complete removal of PG by enzymic hydrolysis resulted in a significant reduction in the oligomeric content of both RH and RNH LHCII such that LHCII(1):LHCII(3) of RH and RNH LHCII preparations were the same. This confirms that this specific compositional change accounts for the structural differences between RH and RNH LCHII observed in situ and in vitro.

Journal Article↗
PubMed1990

[Studies on the health standard for room temperature in cold regions].

The microclimate of 205 rooms of single storey houses in four new rural residential districts in coastal and inland Shandong was monitored and studied the blood circulation of the finger, skin temperature, sweating function and other physiological indexes among 2,401 peasants. We interrogated their personal sensation to cold and warmth. The count was done by the application of thermal equilibrium index (TEI), predicted 4-hour Sweat Rate (P4SR) and the uncomfortable index. The standard room temperature is recommended as follows. In rural area in winter the appropriate room temperature is 14-16 degrees C, the comfortable room temperature is 16-20 degrees C, the lowest room temperature must not be below 14 degrees C. In summer the appropriate room temperature is 25-28 degrees C, the comfortable room temperature is 26-27 degrees C, the highest temperature must not be above 28 degrees C.

Fingers↗
PubMed1989

Reversibility of retinal adhesion in the rabbit.

We have studied retinal adhesion in the rabbit using a new technique for quantifying adhesiveness by the observation of how much pigment remains adherent to the photoreceptors after separation. Previous in vitro work has shown that retinal adhesiveness falls within 3 min after enucleation, is weakened by low pH or the removal of calcium and magnesium, and is increased by cold temperature. This report shows that the effects of low pH, low calcium/magnesium and temperature are all rapidly reversible. Thus, restoring normal pH or normal calcium/magnesium will restore adhesiveness to control levels, and adhesion may be repeatedly weakened or strengthened by the adjustment of temperature or the ionic environment. The actions of pH and calcium/magnesium are in part additive, while cold temperature can maintain adhesion even in low pH or low calcium/magnesium. These findings suggest that irreversible processes such as metabolic or enzymatic decay are not primarily responsible for the loss of retinal adhesion which occurs so rapidly after enucleation or death. They also suggest that retinal adhesion is a multifactorial process.

Adhesiveness↗
PubMed1998

[Study of skin temperature, microclimate and comfort of clothing of old females at rest--ambient temperature x humidity: 30 degrees C. R.H.80%, 30 degrees C. R.H.45%, 20 degrees C. R.H.45%].

Old females are compared to young females for the purpose of studying the difference in comfort caused by the environmental variables of temperature and humidity as well as the form of clothing. Eight experiments were performed in three settings: (a) 30 degrees C R.H.80%; 30 degrees C R.H.45%; and 20 degrees C R.H.45%. The ages of the subjects range from 62 to 68 (Mean = 65.17, S.D. = 1.68) among old females and from 20 to 23 (Mean = 20.83, S.D. = 0.76) among young females. The following results were obtained: (1) The young females were sensitive to hot temperatures, while the old females were not. On the other hand, the old females were more sensitive to cold temperatures, under 20 degrees C R.H.45%, than the young females. In temperatures under 30 degrees C R.H.80%, the heat radiation from the young females was higher than that of the old females. Under 20 degrees C R.H.45%, the heat radiation from the old females was higher than from the young females. The old females are thought to decline in physiogenic function due to enduring both hot and cold temperatures. (2) The correlation between the temperature in clothes and comfort among the old females is not different from the same correlation among the young females. This conclusion agrees with previously published studies of the young females. (3) Skin temperature and bloodstream are measured, according to clothing form. As a result, a long skirt is the highest in thermal insulation, long pants the next highest, and a short skirt is the lowest. (4) The effect of thermal insulation provided by a lap robe was tested in both groups. The lap robe was found to be more effective for the older group than the younger in temperatures under 20 degrees C R.H.45%. Hence, the role of clothes in offsetting for the decline in the thermoregulation function that compensates for environmental change is more important for old females than for young.

Aged↗
PubMedDate not supplied

Augmentation of transgene expression in cold-preserved organs using vascular endothelial growth factor receptor-mediated adenoviral vector combined with hyperbaric oxygen.

Adenovirus-mediated gene transfer has been widely used in gene therapy for congenital metabolic, cardiovascular, and malignant diseases. It has been reported that a gene transfer technique into transplanted organs may suppress rejection reactions and inhibit preservation injury. However, the magnitude of transgene expression in organs preserved at a cold temperature remains to be determined. In this study, we compared the transgene expression using vascular endothelial growth factor receptor (VEGFR)-mediated adenoviral vector at cold versus warm temperatures alone and combined with hyperbaric oxygen in cold-preserved organs. The transgene expression by porcine endothelial cells transduced with adenoviral vector was significantly higher after a 24 hour-incubation at warm temperature than after a 1 hour-incubation with warm or cold temperature. Moreover, the transgene expression of after a 1-hour incubation at cold temperature was significantly lower than a 1-hour incubation at warm temperature. The VEGFR-mediated adenoviral vector augmented transgene expression during a 1-hour incubation at cold temperature compared to the control vector. A/J skin graft survival in C3H mice was significantly prolonged compared to control or standard vector with CTLA4Ig cDNA using VEGFR-mediated adenoviral vector with CTLA4Ig cDNA in a 1-hour cold preservation. Furthermore, combined use of VEGFR-mediated adenoviral vector with CTLA4Ig cDNA plus FK506 showed an augmented effect on graft prolongation. It is concluded that adenovirus-mediated gene transfer in 1-hour cold-preserved organ is difficult compared to that in the warm condition. However, VEGFR-mediated gene transfer can augment the transgene expression in 1-hour cold-preserved organs, followed by the effective suppression of rejection reactions in allogeneic transplantation.

Abatacept↗
PubMed1999

Influence of normothermic systemic perfusion temperature on cold myocardial protection during coronary artery bypass surgery.

OBJECTIVE: To determine the effect of normothermic systemic perfusion on myocardial injury when using cold cardioplegic techniques in patients undergoing coronary artery bypass surgery. METHOD: Sixty six patients with stable angina pectoris were prospectively randomized into three groups according to cardiopulmonary bypass temperature: hypothermia (28 degrees C, n = 22), moderate hypothermia (32 degrees C, n = 22) and normothermia (37 degrees C, n = 22). All patients received cold antegrade crystalloid cardioplegia and topical cooling with saline at 4 degrees C. Serum samples were collected for troponin T and I estimation preoperatively, 4 hours after removal of the aortic cross clamp, and 12, 24, 36 and 48 hours postoperatively. In addition, serial electrocardiographic studies were undertaken on days 1, 3 and 5. RESULTS: Patients were similar with regard to preoperative and intraoperative characteristics Four patients showed ECG changes typical of perioperative myocardial infarction but remained clinically well (28 degrees C, one; 32 degrees C, one; 37 degrees C, two). In the remaining 62 patients, serum troponin T increased significantly from a mean baseline value of 0.02 ng/ml to 1.5+/-0.9 ng/ml 4 hours after removal of the aortic cross-clamp (P<0.0001). Similarly, troponin I increased from 0.06 ng/ml to 0.63+/-0.47 ng/ml 12 hours after reperfusion (P<0.0001). Serum concentrations of both markers subsequently declined with time but remained higher than preoperative values at 48 hours. There were no differences between the three groups with respect to peak and cumulative serum troponin release. Normothermic cardiopulmonary bypass did not compromise the efficacy of cold myocardial protection when assessed by serum troponin concentrations in low risk patients undergoing coronary revascularization.

Aged↗
PubMed1981

Isolation and purification of Giardia trophozoites from rat intestine.

A method for the isolation of Giardia trophozoites based on their ability to attach to warm surfaces has been developed. Mucosal scrapings were obtained from the small intestine of rats infected with Giardia and suspended in Hanks' balanced salt solution (HBSS). Trophozoites were concentrated by centrifugation and allowed to attach to the surfaces of polystyrene petri dishes incubated at 37 C. Incubation temperature significantly affected the recovery of trophozoites. After attachment at 37 C, trophozoites were separated from contaminating intestinal debris by incubation at cold temperature. The trophozoites detach at 4 C, whereas the intestinal debris remain adherent. Then the detached trophozoites were isolated by reattachment at 37 C. Examination by scanning electron microscopy revealed a marked reduction in contamination of attached trophozoites and dish surfaces after the use of cold temperature detachment and reattachment at 37 C. Viability of trophozoites as measured by erythrosin-B dye exclusion, remained above 90% up to 120 min after isolation. This method of isolation facilitates the recovery of this protozoan directly from small intestine for morphological and experimental study.

Animals↗
PubMed1986

[Thyroid reactions in Wistar rats during the circadian rhythm after ganglionectomy at normal temperature and under cold exposure with regard to the influence of the epiphysis cerebri].

Serum thyroxin (T4), serum TSH, and pituitary TSH were measured by radioimmunoassay (RIA) and serum cholesterol by Liebermann-Burchard reaction in rats 4 times a day (light-dark cycle: 14 L: 10 D) after gangliectomy (bilateral extirpation of the Ganglia cervicalia superiora) at cold and normal temperature conditions. 80 male Wistar rats were divided into 4 groups: sham-operated group, 24 degrees C (297 K); sham-operated group, 10 degrees C (283 K); gangliectomy, 24 degrees C (297 K), and gangliectomy, 10 degrees C (283 K). We have sacrificed the rats 30 d after operations at the following day-times: middle light, middle darkness, 1 h after light "on" and 1 h after light "off" (they were exposed to cold 72 h before killing). It was found that gangliectomy significantly depressed blood level of thyroxin. On the other hand, it enhanced the serum cholesterol and TSH levels as well as the pituitary TSH content. Exposure to cold increased thyroxin, serum TSH and pituitary TSH. The cholesterol level, however, was significantly decreased. Gangliectomy causes a reduction of the cold-induced stimulation of thyroxin (significant), serum TSH, and pituitary TSH content (significant). The cholesterol (in relation to the cold-exposure alone) was significantly increased under these conditions. We have found similar results in another long-time experiment (90 d exposure) after gangliectomy as well as after pinealectomy. There also appears a lowered thyroxin and an increased cholesterol level (in dependency on the seasons). Gangliectomy induced a decrease of the pineal weight and a compensatory thyroid growth. Exposure to cold induced an increase of pituitary and pineal weights. Gangliectomy provokes a reduction of the cold-induced augmentation of the pineal weight. The results indicate that gangliectomy diminishes the total levels of circulating T4 in the presence of an intact pineal gland and reduces the cold-induced increase of T4 in long-time experiments (30 and 90 d post operationem). Both gangliectomy and cold condition led to an enhancement of serum TSH and pituitary TSH content. The exposure to cold was found to have a more severe influence. In the present study, we also have discussed the sympathetic denervation effect of the gangliectomy in relation to the thyroid and pineal gland. Due to certain contradictory data in the literature, we have also discussed the TRH-5-hydroxytryptamine (respectively melatonin) antagonism, though we were not able to determine whether peripheral and/or central mechanisms play the more important role in their regulation.

Animals↗
PubMed2002

The consequences of acute cold exposure on protein oxidation and proteasome activity in short-tailed field voles, microtus agrestis.

During cold exposure, animals upregulate their metabolism and food intake, potentially exposing them to elevated reactive oxygen species (ROS) production and oxidative damage. We investigated whether acute cold (7 +/- 3 degrees C) exposure (1, 10, or 100 h duration) affected protein oxidation and proteasome activity, when compared to warm controls (22 +/- 3 degrees C), in a small mammal model, the short-tailed field vole Microtus agrestis. Protein carbonyls and the chymotrypsin-like proteasome activity were measured in plasma, heart, liver, kidney, small intestine (duodenum), skeletal muscle (gastrocnemius), and brown adipose tissue (BAT). Trypsin-like and peptidyl-glutamyl-like proteasome activities were determined in BAT, liver, and skeletal muscle. Resting metabolic rate increased significantly with duration of cold exposure. In skeletal muscle (SM) and liver, protein carbonyl levels also increased with duration of cold exposure, but this pattern was not repeated in BAT where protein carbonyls were not significantly elevated. Chymotrpsin-like proteasome activity did not differ significantly in any tissue. However, trypsin-like activity in SM and peptidyl-glutamyl-like activity in both skeletal muscle and liver, were reduced during the early phase of cold exposure (1-10 h), correlated with the increased carbonyl levels in these tissues. In contrast there was no reduction in proteasome activity in BAT during the early phase of cold exposure and peptidyl-glutamyl-like activity was significantly increased, correlated with the lack of accumulation of protein carbonyls in this tissue. The upregulation of proteasome activity in BAT may protect this tissue from accumulated oxidative damage to proteins. This protection may be a very important factor in sustaining uncoupled respiration, which underpins nonshivering thermogenesis at cold temperatures.

Adipose Tissue, Brown↗
PubMed1983

Osmotic Adjustment and the Development of Freezing Resistance in Fragaria virginiana.

Cold temperature acclimation in strawberry (Fragaria virginiana) leaves apparently involves the alteration of cellular osmotic properties. Alterations in leaf osmotic potential were closely correlated with alterations in soluble carbohydrate content of the leaf tissue and changing temperatures. Leaf starch content was inversely related to soluble carbohydrate levels, suggesting that starch is a partial source of osmoticum during osmotic adjustment associated with cold temperature stress. Free amino acid changes were more closely linked to senescence and growth processes while changes in ion content suggested a rapid mobilization of solutes at the onset of freezing temperatures. This was supported by changes in whole plant gradients in leaf osmotic potential before and after exposure to freezing temperatures. In terms of freezing resistance and the role of osmotic adjustment in the development of resistance, it was found that of all leaves undergoing osmotic adjustment only the younger leaves survived, suggesting an age-dependent component to freezing resistance in leaves. Freezing resistance appears to involve alterations in several cellular properties that act in concert to confer a hardy state of the tissue. Although osmotic adjustment may be an important component of the final combination of cellular properties, this study indicates that solute accumulation does not function alone to confer freezing resistance.

Journal Article↗
PubMed2003

[Numerical analysis of finger temperature distribution in a cold environment].

OBJECTIVE: Temperature distribution over the finger was discussed, so as to provide reference for thermal protection of the hand. METHOD: Mathematical model for thermoregulation of trunk including hands was established. In the model, the trunk was divided into 15 segments and the hand was divided into palm and 5 fingers. The model was presented as a consistent set of bio-heat equations and was solved by a finite element method. RESULT: Effect of wind speed on the finger temperature is so evident, while the effect of artery blood temperature on the finger temperature is so little. CONCLUSION: Through the comparison with the result of literature, the establishment of the model was proved to be reasonable and the method feasible.

Body Temperature↗