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Molecular responses of plants to cold shock and cold acclimation.

The Plant Kingdom encompasses a grouping of mostly sessile organisms that show extreme variation in morphology, size, ecological adaptation, life cycle, and climatic tolerance. With the exception of low elevation tropical environments, plants living just about anywhere else in the world may be subject to temperatures below that which are optimal for growth and survival. Consequently, the range of tolerance to low temperature stress in the Plant Kingdom is as great as the natural variation in low temperatures. For mesophilic plants, sub-optimal low temperature could range from 15 degrees C down to -55 degrees C. In the past 10 years, more than 100 genes have been shown to be preferentially expressed in response to low temperatures. Significant progress in understanding the responses of plants to low temperature has occurred in the areas of signal perception and transduction pathways, transcriptional control and the characterization of a variety of stress-related proteins. A common aim of much of the research on cold stress in plants is to find ways to enhance the stress tolerance and reduce economic losses.

Amino Acid Sequence↗

[Detection and stimulus-detection electromyography (EMG), blink-reflex and trigeminal (V2 and V3) somatosensory evoked potentials (SSEP) in peripheral facial paralyses induced by cold. Importance of the systematic use of V SSEP in facial paralyses induced by cold].

Thirty-six patients afflicted with cold-induced peripheral facial paralysis were examined by classical detection and stimulus-detection E.M.G. methods (Blink Reflex) complemented by V (V2, V3) S.E.P. These examinations were carried out 4 to 7 weeks after the deficiency set in. Detection and stimulus-detection E.M.G. is the best method of confirming clinical diagnosis of peripheral facial paralysis. If there is the slightest sign of Charles Bell, the Blink-Reflex is an excellent confirmation test. S.E.P. of the V allows infra-clinical damage to the nerve to be discerned in 45% of the cases. The cause of this damage is a subject of debate.

Blinking↗

Comparative cold responses of men and women to external and internal cold stimuli.

Experiments were conducted comparing the relative contribution of internal and external cold stimuli in the initiation of horripilation (cutis anserina or "goose flesh") in men and women. Five men and five women were compared. Subjects wore a water perfused vest which covered the entire thorax and allowed torso skin temperature to be maintained at either 34 degrees C, 30 degrees C, 26 degrees C, or 22 degrees C in four separate experiments. After stabilization, the subject's legs were immersed in water maintained at 16 degrees C for 20 min. After removing their legs from the water, subjects then pedalled a stationary bicycle ergometer at minimum resistance to facilitate the return of cooled venous blood to the thoracic core. Horripilation was episodic in both men and women but related significantly to torso skin temperature in men and percent body fat in women over the range of torso skin temperatures tested. There was no significant association between horripilation episodes and either the stabilization, immersion, or minimal exercise phase of the experiment. Core body temperature, as measured by rectal and esophageal thermistors, decreased significantly in men from 37.0 degrees C and 36.6 degrees C at 34 degrees C torso skin temperatures, but remained unchanged in women. The results suggest that skin cooling initiates horripilation whose occurrence and pattern are affected by different combinations of morphological or physiological variables in men and women.

Adult↗

Effects of different cold preservation solutions on restoration of hepatic energy metabolism during cold reperfusion.

Rat livers were flushed with different preservation solutions and stored at 4 degrees C for 24 h before being reperfused with a synthetic air-equilibrated, water-based solution. Four solutions were tested using this isolated rat liver model: Marshall's hypertonic citrate (HC); modified University of Wisconsin solution (Mod UW); a histidine-based solution (HIS); and a histidine-lactobionate-raffinose-based solution (HLR). After storage, livers were perfused at 4 degrees C for a period of 2 h and biopsy samples taken, at different time points, to investigate energy metabolism. Livers stored in HLR and HIS had higher 24-h storage levels of ATP (0.41 and 0.24 mumol/g respectively; P < 0.05) than those stored in Mod UW and HC. On reperfusion, all groups regenerated ATP by 1-2 h. However, significantly greater levels of ATP regeneration occurred in livers stored in the HLR (1.6 +/- 0.08 mumol/g) and Mod UW (1.3 +/- 0.18) than HC (0.58 +/- 0.19) and HIS (0.96 +/- 0.12); P < 0.05. Energy charge (1) (EC) recovered in all groups but was significantly higher in HLR and Mod UW (0.79 and 0.68, respectively; P < 0.05) than HC and HIS. These represent 95% (HLR) and 80% (Mod UW) of values observed in FIL. During the reperfusion period, total adenine nucleotide levels (TA) did not vary significantly within each storage group, except in the HIS solution. However, TAs were greater with livers stored for 24 h in HLR (2.5 +/- 0.25) and Mod UW (2.7 +/- 0.20) than those the other two storage groups (P < 0.05 in each case). This study has demonstrated that it was possible to resuscitate liver energetics after prolonged hypothermic ischemia by a period of cold reperfusion, and the method can differentiate between preservation solutions. The livers stored in each solution showed varying degrees of success in regeneration of ATP and EC, demonstrating that oxygen was not a limiting factor when using an air-equilibrated perfusate. The solutions providing the better preservation conditions gave the greater resuscitation of liver energetics (Mod UW and HLR). Overall, livers stored in HLR had the greatest resuscitation of energy metabolism, which correlates with survival data from other studies (29-31, 33).

Adenosine↗

Evaluation in children of cold-adapted influenza B live attenuated intranasal vaccine prepared by reassortment between wild-type B/Ann Arbor/1/86 and cold-adapted B/Leningrad/14/55 viruses.

A reassortant cold-adapted (ca) influenza B experimental live attenuated intranasal vaccine was evaluated for safety and immunogenicity in children by means of a blind, placebo controlled study. The vaccine contained the haemagglutinin and neuraminidase genes, and the gene for its non-structural proteins from wild-type (wt) B/Ann Arbor/1/86 virus, the contemporary strain at the time of the study. Other genes were derived from ca B/Leningrad/14/55 virus. No increase in illness rates was seen in the children from ages 3-15 years given vaccine at maximum potency (a one in two dilution of infectious allantoic fluid, having a titre of 10(7.0) EID50) compared to children given placebo. About 60% of seronegative children, ages 3-7 years, exhibited a detectible antibody response following one dose of intranasal vaccine, with the seroresponse rate rising to greater than 70% after two doses of vaccine. Immunogenicity was lowest in seropositive children age 8-15 years, reaching a maximum of 36% after two doses. Results indicated that the vaccine was highly attenuated, and probably of adequate immunogenicity for kindergarten age children. The lower immunogenicity in older children suggests the vaccine might be overly attenuated for use in school-age children who are more likely to have a history of prior natural infection with influenza B virus. Further clinical and epidemiological studies of protection are needed to fully assess this.

Administration, Intranasal↗

The end of the cold era: from intermittent cold to intermittent warm blood cardioplegia.

BACKGROUND: A major reduction in the energy demand of the myocardium results from the electromechanical arrest, and cooling contributes to a lesser degree to this reduction. It is from this assumption that strategies of myocardial protection, utilizing warm blood cardioplegic induction, followed by cold cardioplegia with terminal warm reperfusion before removal of the aortic cross clamp, became established as optimal myocardial protection. Continuous normothermic perfusion 'closed the loop' by avoiding myocardial ischemia and linking warm induction and terminal reperfusion. A series of laboratory and clinical data confirmed the benefits of warm heart surgery on myocardial function and metabolism. The disadvantages of continuous warm blood cardioplegia including disturbance of the operative field, led surgeons to administer warm hyperkalaemic blood intermittently as a new cardioplegic strategy. METHODS: This review examines the laboratory and clinical data with reference to the intermittent warm blood cardioplegia, to establish its experimental basis and place in clinical practice. CONCLUSIONS: Experimental observation and clinical application have established intermittent warm blood cardioplegia as a practical, effective and cheap myocardial protection technique, particularly with reference to coronary artery surgery.

Animals↗

Cold storage of 'cryohydrocytosis' red cells: the osmotic susceptibility of the cold-stored erythrocyte.

'Cryohydrocytosis' is an unusual human haemolytic anaemia of the 'hereditary stomatocytosis' group, in which the red cell membrane is abnormally permeable to Na and K+ at both body and (even more prominently) refrigerator temperatures. If whole cryohydrocytosis blood is anticoagulated in heparin or EDTA and stored on ice overnight, about 50% of the cells will lyse. Citrate phosphate dextrose adenine (CPDa) anticoagulant, empirically verified as an optimal anticoagulant for storage of normal blood before transfusion, very markedly ameliorated this overnight lysis, suggesting that these cells might form an informative model in which cold storage of the red cell could be studied in a short time scale. Accordingly, we conducted studies of ion flux, cell swelling and lysis in different media used historically for blood preservation and compared the experimental data with an 'integrated red cell model', which seeks mathematically to model the osmotic behaviour of red cells under different conditions. Upon experiment, lysis in these cells was reduced by additives that could be regarded as impermeant extracellular solutes (citrate, mannitol) and by low pH, but not by those agents that are regarded as protecting the cell against energy depletion or oxidation (adenine, glucose, nicotinic acid). The protective effects of these extracellular additives were all reproduced by the computer simulation, confirming the validity of this model, although the effect of pH could be simulated only semi-quantitatively, possibly because Na+ permeability itself depends on pH.

Anemia, Hemolytic↗