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PubMed1979

Effects of noradrenaline and nicotinic acid on plasma free fatty acids and oxygen consumption in cold-adapted rats.

A 3-h noradrenaline (NA) infusion (1.5 microgram kg-1 min-1) produced a sustained enhanced oxygen consumption (O2 cons.) in cold-adapted rats. Plasma free fatty acid (FFA) levels were elevated by NA in control and in cold-adapted rats, but to lesser extent in cold-adapted rats; the increase was maintained at a plateau in both groups during the entire period of NA infusion. A 1-h nicotinic acid (Nic A) infusion (1.5 mg kg-1 min-1) added to the NA infusion inhibited the calorigenic response to NA in cold-adapted rats and reduced the elevated plasma FFA concentration in control and in cold-adapted rats to values below basal levels. However, when the Nic A infusion was stopped, the O2 cons. was increased again in cold-adapted rats by the uninterrupted NA infusion, without the simultaneous increase of the plasma FFA concentration; the plasma FFA concentration was maintained in cold-adapted rats below basal values and merely brought back to basal levels in control rats. From these results, it is suggested that plasma FFA are not an essential substrate to the calorigenic response to NA observed in cold-adapted rats, as 85% of the response can occur when the plasma FFA concentration is very low.

Adaptation, Physiological↗
PubMed1992

The different types of general cold adaptation in man.

Different types of general cold adaptation have been described over the last 50 years. Metabolic adaptation (Alacaluf Indians, Arctic Indians Eskimos), insulative adaptation (coastal Aborigines of tropical northern Australia), hypothermic adaptation (bushmen of the Kalahari desert, Peruvian Indians) and insulative hypothermic adaptation (Central Australian Aborigines, nomadic Lapps, Korean and Japanese diving women). These different types of cold adaptation are related to the intensity of the cold stress and to individual factors such as diet, the level of physical fitness and body fat content. Thus, in natural environments, man develops a strategy of adaptation to cold, which takes into account environmental and individual factors. This strategy is susceptible to be modified when these conditions change. Caloric intake deficit could have been responsible for the hypothermic adaptation observed after J.-L. Etienne's journey to the North Pole. Physiological responses were adapted to maintain an acceptable level of energetic reserves with a moderate hypothermia, which was not life threatening for the climatic conditions encountered by the polar explorer.

Acclimatization↗
PubMed1993

Molecular and biological changes in the cold-adapted "master strain" A/AA/6/60 (H2N2) influenza virus.

The live cold-adapted (ca) A/AA/6/60 influenza vaccine is being commercially developed for worldwide use in children and is being used as a model for other live vaccines. Although it has been proven safe and immunogenic, the molecular basis of cold adaptation has never been determined. To identify sequence changes responsible for cold adaptation, we have compared the sequence of the master ca vaccine strain to its progenitor wild-type virus, wt A/AA/6/60 E2 (wt2). Only 4 nt differences encoding 2 aa differences were found in three gene segments. Computer-predicted RNA folds project different secondary structures between the ca and wt2 molecules based on the two silent differences between them. Genes coding for the acidic polymerase, matrix, and nonstructural proteins are identical between the two viruses. The few differences found in the ca A/AA/6/60 virus after its long stepwise passage at 25 degrees C in primary chicken kidney cells suggest that cold adaptation resulted in greater genetic stability for the highly variable RNA genome.

Adaptation, Physiological↗
PubMed1978

[Concentration of acid proteins in the nuclei of rat hypothalamic neuron and glial cell nuclei during cold adaptation].

By means of two-wave length cytospectrophotometry the acid protein content per cell was determined in the nuclei of the neurons and their glial satellite cells of the medial peroptic area and the supraoptic nucleus of the hypothalamus of rats kept at 2--4 degrees C for 1, 3, 7, or 15 days (adaptation to cold). This colling resulted in an initial decrease in the nuclear acid protein content in the whole neuron-neuroglia system of the medail preoptic area with a gradual restoration to the normal by the 15th day of constant cooling. In the glial cells of this area the acid protein content increased temporarily above the control level before the restoration to the normal. A gradual accumulation of acid proteins and its following restoration to the control level was revealed in the neuron-neuroglia system of the supraoptic nucleus. By the 15th day of the adaptation to cold the content of neuronal and glial acid proteins of this nucleus became somewhat lower than in the control.

Acclimatization↗
PubMed1997

Cold-adapted microtubules: characterization of tubulin posttranslational modifications in the Antarctic ciliate Euplotes focardii.

In cold poikilotherm organisms, microtubule assembly is promoted at temperatures below 4 degrees C and cold-induced depolymerization is prevented. On the basis of the results of investigations on cold-adapted fishes, the property of cold adaptation is ascribed to intrinsic characteristics of the tubulins. To fully understand cold adaptation, we studied the tubulins of Euplotes focardii, an Antarctic ciliated protozoan adapted to temperatures ranging from -2 to +4 degrees C. In this organism, we had previously sequenced one beta-tubulin gene and, then identified three other genes (denoted as beta-T1, beta-T2, beta-T3 and beta-T4). Here we report that the amino acid sequence of the carboxy-terminal domain predicted from the beta-T3 gene (apparently the most expressed of the gene family) contains six modifications (five substitutions and one insertion) of conserved residues, unique with respect to all the other known beta-tubulin sequences. These modifications can change the structural conformation of the carboxy-terminal domain. Furthermore, in the variable terminal end of that domain, a consensus sequence for a phosphorylation site is present, and the residue Glu-438, the most frequent site for polyglutamylation in beta-tubulin, is substituted by Asp. Starting from these observations, we showed that in E. focardii only alpha-tubulin is polyglutamylated, while beta-tubulin undergoes phosphorylation. Polyglutamylated microtubules appear to colocalize with cilia and microtubular bundles, all structures in which microtubules undergo a sliding process. This finding supports the idea that alpha-tubulin polyglutamylation is involved in the interaction between tubulin and motor microtubule-associated proteins. Phosphorylation, usually a rare posttranslational modification of beta-tubulin, which is found extensively distributed in the beta-tubulin of this cold-adapted organism, may play a determinant role in the dynamic of polymerization and depolymerization at low temperatures.

Acclimatization↗
PubMed1999

Identification of mutations contributing to the temperature-sensitive, cold-adapted, and attenuation phenotypes of the live-attenuated cold-passage 45 (cp45) human parainfluenza virus 3 candidate vaccine.

The live-attenuated human parainfluenza virus 3 (PIV3) cold-passage 45 (cp45) candidate vaccine was shown previously to be safe, immunogenic, and phenotypically stable in seronegative human infants. Previous findings indicated that each of the three amino acid substitutions in the L polymerase protein of cp45 independently confers the temperature-sensitive (ts) and attenuation (att) phenotypes but not the cold-adaptation (ca) phenotype (29). cp45 contains 12 additional potentially important point mutations in other proteins (N, C, M, F, and hemagglutinin-neuraminidase [HN]) or in cis-acting sequences (the leader region and the transcription gene start [GS] signal of the N gene), and their contribution to these phenotypes was undefined. To further characterize the genetic basis for the ts, ca, and att phenotypes of this promising vaccine candidate, we constructed, using a reverse genetics system, a recombinant cp45 virus that contained all 15 cp45-specific mutations mentioned above, and found that it was essentially indistinguishable from the biologically derived cp45 on the basis of plaque size, level of temperature sensitivity, cold adaptation, level of replication in the upper and lower respiratory tract of hamsters, and ability to protect hamsters from subsequent wild-type PIV3 challenge. We then constructed recombinant viruses containing the cp45 mutations in individual proteins as well as several combinations of mutations. Analysis of these recombinant viruses revealed that multiple cp45 mutations distributed throughout the genome contribute to the ts, ca, and att phenotypes. In addition to the mutations in the L gene, at least one other mutation in the 3' N region (i.e., including the leader, N GS, and N coding changes) contributes to the ts phenotype. A recombinant virus containing all the cp45 mutations except those in L was more ts than cp45, illustrating the complex nature of this phenotype. The ca phenotype of cp45 also is a complex composite phenotype, reflecting contributions of at least three separate genetic elements, namely, mutations within the 3' N region, the L protein, and the C-M-F-HN region. The att phenotype is a composite of both ts and non-ts mutations. Attenuating ts mutations are located in the L protein, and non-ts attenuating mutations are located in the C and F proteins. The presence of multiple ts and non-ts attenuating mutations in cp45 likely contributes to the high level of attenuation and phenotypic stability of this promising vaccine candidate.

Adaptation, Biological↗
PubMed1993

[Changes in body fluids and minerals after cold adaptation].

To characterize fluid and ion shifts during 5-weeks cold adaptation, 6 nonadapted volunteers underwent cold acclimation programme (CAP), consisted of 1 h head-out immersion in water 14 +/- 1 degrees C 3 times a week. Blood samples were analyzed before/after the immersion and in the first and in the last week of CAP. Urine was collected for 10 h before, during, and after immersion for 4 h. Plasma volume (PV) decreased during first immersion (-18%) and less after CAP (-12). Blood volume reduction was 8.5% before and 5.2% after the CAP. Mean corpuscular volume was not changed either after the cold exposition or after the cold adaptation. The concentration of serum proteins increased by 12.1% after first immersion and by 8.1% after the CAP. The changes in serum concentration of Na+, K+ and Cl- before and after the CAP were not significant. Urine flow increased by 102% after first immersion, and by 165% after CAP. Urinary excretion of Na+ increased by 167% and 283%, excretion of K+ by 222% and 362% during first immersion and after CAP, respectively. Serum concentration of aldosterone increased nonsignificantly (+30%) during immersion before CAP and it did not changed after CAP. After the cold adaptation we observed the reduction of PV decrease, and increased diuresis with higher excretions of cations.

Acclimatization↗
PubMed1976

[The role of ketone bodies in nonshivering thermogenesis in cold-adapted rats (author's transl)].

In spite of the ill fame of useless products of metabolism that only accumulate in the blood under abnormal conditions, ketone bodies (KB) have now regained the fame as an important fuel of respiration for the brain and muscles in prolonged starvation in humans and other animals. In cold-adapted animals, ketosis has been well documented, but little is known about the physiological role of KB in cold adaptation. In this study, role of KB in nonshivering thermogenesis was investigated in warm- and cold-adapted rats with or without norepinephrine (NE) loads, a decisive lipid metabolizing hormone in cold adaptation. First, levels of blood KB and plasma free fatty acid (FFA) and FFA turnover rate were examined along with rectal temperature under continuous infusions of various doses of NE. Good dose-response relationship of rectal temperature was obtained with increasing doses of NE in cold-adapted rats, but not in warm-adapted ones. The levels of blood KB and plasma FFA in cold-adapted rats remained almost unaltered during the observation period of 30 minutes. Infusion of NE, however, greatly enhanced FFA turnover rate in cold-adapted rats as compared with controls. Next, fractional turnover rate and half-life of beta-OH-butyrate were obtained from decay curves of endogenous beta-OH-butyrate, using functionally eviscerated rats in which no KB were produced. Calculated turnover rate of KB was also found significantly increased in cold-adapted rats. Finally, the effect of NE on the production of KB was examined using the liver in situ perfusion technique of Mortimore with minor modifications. Viability of the liver preparation was guaranteed by sufficiently high rates of bile production as well as oxygen consumption. The production rate of KB in the preparation under palmitate loads of physiological medium concentration was significantly higher in cold-adapted rats than in warm-adapted controls. However, no significant effect of NE loaded simultaneously was observed in either group. Quantitative analysis shows that the turnover rate of KB in vivo essentially equals the production rate in the perfused liver when no exogenous NE is added. In contrast NE infusion the turnover rate in vivo was almost doubled that of the perfused liver. All these results indicate KB are used as an important energy source with the significancy of FFA in nonshivering thermogenesis. Moreover, it may be surmised that production of KB in vivo, particulary in the cold-adapted state, is effected by other unknown factors than NE.

Acclimatization↗
PubMedDate not supplied

[Attenuated recombinant influenza type B virus obtained during crossing of virus B/Ann Arbor/2/86 with the cold-adapted strain B/Leningrad/14/17/55].

Crossing the cold-adapted B/Leningrad/14/17/55 strain with the temperature-sensitive virulent B/Ann Arbor/2/86 strain yielded a recombinant B/14/5/1 which, by the antigenic specificity of hemagglutinin and neuraminidase, corresponded to the B/Ann Arbor/2/86 strain but, like the attenuated donor, had the cold-adapter characteristics. The B/14/5/1 recombinant inherited the genes coding for proteins PB2, PB1, PA, NP, and M from the attenuated master strain and the genes coding for hemagglutinin, neuraminidase, and proteins NS from the virulent master strain. This strain was nonreactive for adults and for children with the initial anti-hemagglutinin antibody titre less than or equal to 1:20 (the reactogenic index being 1 and 0.9% respectively) and was moderately antigenic inducing a 4-fold or more rise of anti-hemagglutinins in the blood of 48.8% of seronegative adults and in 46.6% of seronegative children of 3 to 15 years of age. The highest indices of seroconversions (60%) were recorded in a group of preschool children.

Adaptation, Biological↗
PubMed1998

Evaluation of live, cold-adapted influenza A and B virus vaccines in elderly and high-risk subjects.

We have evaluated the use of live cold-adapted influenza A and B virus vaccines in the elderly. Cold-adapted influenza A and B virus vaccines are safe and modestly immunogenic in individuals over 65 years of age. However, our studies and those of other groups have shown that immune response to cold-adapted vaccines in this age group are modest. Administration of combined cold-adapted influenza A and inactivated influenza vaccine has resulted in slightly higher frequencies of local and systemic humoral immune responses than inactivated vaccine alone in some, but not all, studies. In a double-blind field trial conducted in nursing homes over a 3 year period, combined cold-adapted influenza A (H3N2) and trivalent inactivated influenza vaccine resulted in a 60% decrease (95% CI, 18-82%) in the rate of laboratory documented influenza A compared with inactivated vaccine alone. Further studies of multivalent cold-adapted influenza vaccines used in combination with inactivated vaccine should be performed.

Aged↗
PubMed1984

[Effect of cold adaptation on the transmission of excitation in a myoneural synapse].

In cold-adapted rats, synaptic excitability of single muscle fibers of fast (m. gastrocneiraus ) and slow (m. soleus) muscles as well as lability of their synapses were studied with the intracellular recording of APs. A decrease of thresholds of the synaptic excitability both in fast and in slow muscle fibers was found in cold-adapted rats. The lability of neuromuscular synapses in both types of muscles was also higher in the cold-adapted rats than in the control group. Cold adaptation seems to induce changes of synaptic transmission of excitation in fast and slow muscle fibers which reduces their excitability difference.

Action Potentials↗
PubMed1982

The acute regulation of mitochondrial proton conductance in cells and mitochondria from the brown fat of cold-adapted and warm-adapted guinea pigs.

Cells and mitochondria were prepared from the brown adipose tissue of adult guinea-pigs adapted to either 4-7 degrees C or 22-25 degrees C. The cold-adapted cells displayed noradrenaline-stimulated, propranolol-sensitive respiration, but noradrenaline failed to increase the respiration of the warm-adapted cells. Purine-nucleotide-sensitive proton conductance was greater in cold-adapted mitochondria than in warm-adapted controls. At the same time cold-adapted mitochondria were extremely sensitive to the uncoupling effect of endogenous and infused fatty acids, and resembled the mitochondria from the brown adipose tissue of cold-adapted hamsters. Warm-adapted mitochondria were ninefold less sensitive, and resembled liver mitochondria. With cold-adapted, but not warm-adapted mitochondria, respiration increased proportionately to the rate of fatty acid infusion. It is concluded that the presence of the 32000-Mr proton conductance pathway is necessary for the expression of a high sensitivity to fatty acid uncoupling, suggesting that the fatty acids interact directly with this protein to modulate the proton conductance during the acute regulation of thermogenesis.

Acclimatization↗
PubMed2004

Optimisation of the surface electrostatics as a strategy for cold adaptation of uracil-DNA N-glycosylase (UNG) from Atlantic cod (Gadus morhua).

Cold-adapted enzymes are characterised by an increased catalytic efficiency and reduced temperature stability compared to their mesophilic counterparts. Lately, it has been suggested that an optimisation of the electrostatic surface potential is a strategy for cold adaptation for some enzymes. A visualisation of the electrostatic surface potential of cold-adapted uracil-DNA N-glycosylase (cUNG) from Atlantic cod indicates a more positively charged surface near the active site compared to human UNG (hUNG). In order to investigate the importance of the altered surface potential for the cold-adapted features of cod UNG, six mutants have been characterised and compared to cUNG and hUNG. The cUNG quadruple mutant (V171E, K185V, H250Q and H275Y) and four corresponding single mutants all comprise substitutions of residues present in the human enzyme. A human UNG mutant, E171V, comprises the equivalent residue found in cod UNG. In addition, crystal structures of the single mutants V171E and E171V have been determined. Results from the study show that a more negative electrostatic surface potential reduces the activity and increases the stability of cod UNG, and suggest an optimisation of the surface potential as a strategy for cold-adaptation of this enzyme. Val171 in cod UNG is especially important in this respect.

Animals↗
PubMed1994

Effect of simultaneous administration of cold-adapted and wild-type influenza A viruses on experimental wild-type influenza infection in humans.

On the basis of the ability of the attenuated cold-adapted strain of influenza A virus to suppress disease production in ferrets simultaneously infected with epidemic influenza virus (P. Whitaker-Dowling, H.F. Maassab, and J.S. Youngner, J. Infect. Dis. 164:1200-1202, 1991), an evaluation of the ability of the cold-adapted virus to modify clinical disease in humans was made. Adult volunteers with prechallenge serum hemagglutination-inhibition titers to the influenza A/Kawasaki/86 (H1N1) virus of < or = 1:8 received either 10(7) 50% tissue culture infective doses of the wild-type A/Kawasaki virus or a mixture of 10(7) 50% tissue culture infective doses of each of the wild-type virus and a cold-adapted A/Kawasaki reassortant virus by intranasal drops in a randomized, double-blind fashion. Symptoms and wild-type virus shedding were assessed daily for 6 days following challenge. Results were compared with those derived from another group of volunteers who received only cold-adapted virus. Volunteers who received the mixed inoculum of cold-adapted and wild-type viruses had lower symptom scores than those who received wild-type virus alone, suggesting that coinfection with the cold-adapted virus may modify wild-type virus infection, but the differences were not statistically significant in this small study. The data demonstrate that administration of cold-adapted influenza A virus to humans at the time of wild-type virus infection is a safe procedure.

Adaptation, Physiological↗
PubMed1994

Evaluation of cold-adapted, reassortant influenza B virus vaccines in elderly and chronically ill adults.

The safety and immunogenicity of two recent cold-adapted reassortant influenza B viruses were evaluated in persons at high risk for influenza-related morbidity and mortality. Ambulatory adults > 65 years old or with chronic high-risk conditions were randomly assigned to receive parenteral trivalent inactivated influenza vaccine containing either influenza B/Ann Arbor/86 or B/Yamagata/88 hemagglutinin antigens, cold-adapted reassortant influenza B/Ann Arbor/1/86 or B/Yamagata/16/88 viruses (10(7.2) TCID50), or placebo in double-blind fashion. Cold-adapted vaccine viruses were well tolerated, with similar rates of respiratory symptoms in all groups. There were no changes in spirometry or oxygen saturation following vaccination. Immune responses to both types of vaccine were modest, with serum antibody responses occurring significantly more frequently and with higher magnitude in those receiving inactivated than in those receiving cold-adapted vaccine. Cold-adapted, reassortant influenza B vaccines are safe in the elderly and those with chronic illness but are not optimally immunogenic in this group.

Aged↗
PubMed2005

Crystal structure of a subtilisin-like serine proteinase from a psychrotrophic Vibrio species reveals structural aspects of cold adaptation.

The crystal structure of a subtilisin-like serine proteinase from the psychrotrophic marine bacterium, Vibrio sp. PA-44, was solved by means of molecular replacement and refined at 1.84 A. This is the first structure of a cold-adapted subtilase to be determined and its elucidation facilitates examination of the molecular principles underlying temperature adaptation in enzymes. The cold-adapted Vibrio proteinase was compared with known three-dimensional structures of homologous enzymes of meso- and thermophilic origin, proteinase K and thermitase, to which it has high structural resemblance. The main structural features emerging as plausible determinants of temperature adaptation in the enzymes compared involve the character of their exposed and buried surfaces, which may be related to temperature-dependent variation in the physical properties of water. Thus, the hydrophobic effect is found to play a significant role in the structural stability of the meso- and thermophile enzymes, whereas the cold-adapted enzyme has more of its apolar surface exposed. In addition, the cold-adapted Vibrio proteinase is distinguished from the more stable enzymes by its strong anionic character arising from the high occurrence of uncompensated negatively charged residues at its surface. Interestingly, both the cold-adapted and thermophile proteinases differ from the mesophile enzyme in having more extensive hydrogen- and ion pair interactions in their structures; this supports suggestions of a dual role of electrostatic interactions in the adaptation of enzymes to both high and low temperatures. The Vibrio proteinase has three calcium ions associated with its structure, one of which is in a calcium-binding site not described in other subtilases.

Adaptation, Physiological↗