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PubMed1975

[Successful treatment of a severe drowning accident after 20 minutes submersion].

Report on successful post-drowning cardiopulmonary resuscitation of a 2-year-old boy who had lain for 20 min in cold water at 5-7 degrees C. Because of severe pulmonary complications after primary resuscitation--e.g. pulmonary edema, repeated mediastinal and subcutaneous emphysema, pneumoperitoneum and bilateral pneumothorax--spontaneous respiration remained insufficient for 36 days. Under appropriate treatment the patient recovered completely except for slight muscular hypotrophy of the left thigh. 14 months after the submersion no other neurological or pulmonary sequelae could be detected.

Adrenal Cortex Hormones↗
PubMed1975

[Diploid radiation gynogenesis in carp. I. Massive production of diploid gynogenetic progeny].

Mass lost of diploid gynogenetic carp offspring were obtained with the use of fish-farm method of reproduction. The average yield of gynogenetic diploids in usual experiments was 0.1% (from fertilized eggs). The cooling of unfertilized spawn (at the stage of metaphase II) to 8--10 degrees C during 3.5--4.5 hours in 50% of cases permitted to increase by tens of times (in the most successful experiments up to 8%) the yield of gynogenetic diploids. The rate of survival of carps remained relatively low during the first two years of life, particularly during the first hibernation that is a critical period. No specific depression of growth in gynogenetic diploid carps was observed. A high yield of gynogenetic diploids (3.9% of fertilized eggs) and their relatively high rate of survival were observed in the second generation of artificially induced gynogenesis.

Animals↗
PubMedDate not supplied

Reversible atrial lead dysfunction of DDD pacemaker after recent inferior myocardial infarction--a case report.

A patient with DDD pacemaker had pacing dysfunction following an inferior myocardial infarction. The threshold of that implanted right atrial pacing lead was abnormally high but the generator was normal. A temporary lead was inserted into the high right atrium near the appendage and near the low atrium for testing of threshold, which was abnormally high in these 2 places. Forty days after stent implantation in the proximal segment of the right coronary artery, the threshold spontaneously returned to normal. The change threshold of electrode-tissue interface in the right atrium was suspected due to hibernation of right atrium ischemia.

Aged↗
PubMed1993

Myocardial hibernation in the infarcted region cannot be assessed from the presence of stress-induced ischemia: usefulness of delayed image of exercise thallium-201 scintigraphy.

To examine the relationship between the improvement of wall motion in infarcted regions after percutaneous transluminal coronary angioplasty (PTCA) and thallium-201 uptake in the delayed image of exercise thallium-201 scintigraphy before PTCA, 14 patients with anterior old myocardial infarction were studied. Exercise thallium-201 scintigraphy was performed before PTCA of left anterior descending artery, and mean percent thallium-201 uptake of abnormal segments was calculated in the initial and 4-hour delayed images. Left ventricular angiography was performed during catheterization, before, and 4 to 13 months after PTCA; and regional ejection fraction of anterior wall was calculated. Atrial pacing stress test with the measurement of lactate concentration of aorta and great cardiac vein was performed during catheterization before PTCA. In five patients with mean percent thallium-201 uptake in the delayed image < or = 50% (group I), regional ejection fraction did not increase after PTCA (23% +/- 9% to 24% +/- 12%). In the other nine patients with mean percent thallium-201 uptake > 50% (group II), regional ejection fraction increased significantly after PTCA (39% +/- 18% to 47% +/- 14%; p < 0.05). There was no significant difference in regional ejection fraction, lactate extraction ratio during maximal pacing, and the redistribution of exercise thallium-201 scintigraphy between the two groups before PTCA. Thus the delayed image before PTCA is useful to detect reversible nonfunctioning viable myocardium (hibernating myocardium) in the infarcted region. However, the wall-motion abnormality and the degree of stress-induced ischemia in the infarcted region before PTCA may not be necessarily useful for the detection of hibernating myocardium.

Aged↗
PubMed1994

Laboratory rearing of a hibernating animal, pocket mouse (Perognathus flavus).

Hibernating pocket mice (Perognathus flavus) were obtained from the Department of Veterinary Medicine, Hokkaido University, in September 1990, and attempted to rear them in National Institute of Neuroscience, NCNP. Rearing of pocket mice was possible under the general conditions used for rearing mice. As a result of random mating of 4 females to 2 males for breeding, gestation was achieved in only one pair of animals, and parturition under artificial rearing conditions was observed for the first time. The animal gave birth to 3 offspring that had no body hair. Their eyes were closed. Each of the offspring weighed about 1.0g. The mean body weight of the females was 6.5g and that of males 5.6g at 3 weeks. Weaning was possible at this age. Subsequently the animals grew rapidly; the body weight was almost equal to that of an adult animal (8.0g) at 5 weeks of age for the females and 7 weeks for the males. The gestation period was estimated to be 26 days. These findings indicate that pocket mice can be bred and reared under general laboratory conditions.

Animal Husbandry↗
PubMed2003

Sugar preferences and feeding strategies in the hawkmoth Macroglossum stellatarum.

Hummingbird hawkmoths were tested for their preferences for different types of sugar. In triple choice tests, moths sucked for longer periods from sucrose than from fructose and glucose. Naive moths released in a large flight cage and monitored over 24 days, drank on average 137 mul sucrose, 67 mul fructose and 7 mul glucose daily. In an independent test, moths spent more time feeding from sucrose than from fructose and more time feeding from fructose than from glucose. Animals in hibernation made less but longer feeding bouts, whereas animals that fed every day and newly eclosed animals were more likely to make more but shorter visits to feeders. The hawkmoths learned to associate colour with the preferred sugar. In a dual choice test, flower-naive moths chose blue rather than yellow artificial flowers. After the initial test, these animals received sucrose from the yellow and glucose from the blue feeders. A week later they chose yellow more frequently than blue indicating that they had learned to associate a colour with the preferred type of sugar.

Animals↗
PubMed1979

Hornet building orientation in a vertically rotating centrifuge.

Hornets build combs that are clearly oriented toward the center of gravity and they compensate for any change made in the direction of their cells, provided the gravitational vector remains unchanged. Under natural conditions the first few cells are built by the queen in the spring, following the hibernation period, and building is then continued by the workers. Recently several reports have been published concerning the fact that groups of hornets (V. orientalis workers) may build in the absence of the queen and that such combs resemble those built by the queen. In previous investigations on building orientation, hornets placed in artificial breeding boxes (ABBs) on a horizontal centrifuge were subjected to constant centrifugal and gravitational forces, the resultant of which ranged between 1-1.5 g. Under these conditions young hornets (1-2 days of age) built combs in the direction of the resultant force, while the direction of building by adult hornets (3-7 days of age) was dependent on the presence or absence of a straight roof. Adults placed in the ABBs of rectangular shape built combs the orientation of which was determined by the Earth's gravity alone (perpendicular to the roof) whereas those in spherical ABBs with a convex roof built combs in the direction of the resultant gravitational and centrifugal forces, much the same as combs built by the young hornets. We were, however, also interested in studying the building orientation of hornets placed under conditions of changing resultant forces. The present paper describes comb building by hornets under the alternating gravitational forces of a vertical centrifuge.

Age Factors↗
PubMed1998

Inorganic phosphate content and free energy change of ATP hydrolysis in regional short-term hibernating myocardium.

OBJECTIVE: Short-term myocardial hibernation is characterized by an adaptation of contractile function to the reduced blood flow, the recovery of creatine phosphate content and lactate balance back towards normal, whereas ATP content remains reduced at a constant level. We examined the hypothesis that, despite the absence of ATP recovery, the short-term hibernating myocardium regains an energetic balance. METHODS: An enzymatic method was modified for the measurement of inorganic phosphate (Pi) in transmural myocardial drill biopsies (about 5 mg). In 12 anaesthetized swine, moderate ischemia was induced by reduction of coronary inflow into the cannulated left anterior descending coronary artery to decrease regional myocardial function (sonomicrometry) by 50%. RESULTS: The development of short-term hibernation was verified by the recovery of creatine phosphate content, the persistence of inotropic reserve in response to dobutamine and the absence of necrosis (triphenyl tetrazolium chloride). At 5-min ischemia, Pi was increased from 3.6 +/- 0.3 (SD) to 8.1 +/- 1.1 mumol/gwet wt (p < 0.05). The free energy of ATP hydrolysis (delta GATP) was decreased from -57.8 +/- 0.8 to -52.2 +/- 1.4 kJ/mol (p < 0.05). The relationships between function and Pi (r = -0.81) and delta GATP (r = -0.83), respectively, during control and at 5-min ischemia became invalid at 90-min ischemia, as myocardial blood flow and function remained reduced at a constant level, but Pi decreased back to 4.9 +/- 0.9 mumol/g (p < 0.05 vs. control and 5-min ischemia), and delta GATP fully recovered back to -57.2 +/- 1.3 kJ/mol (p < 0.05 vs. 5-min ischemia). CONCLUSIONS: In short-term hibernating myocardium, myocardial inorganic phosphate content recovers partially and the free energy change of ATP hydrolysis returns to control values. Contractile function remains reduced by mechanisms other than an energetic deficit.

Adenosine Triphosphate↗
PubMed2003

Hibernating myocardium retains metabolic and contractile reserve despite regional reductions in flow, function, and oxygen consumption at rest.

Hibernating myocardium, characterized by reductions in flow and function at rest, has limited contractile reserve in response to increases in external workload. We hypothesized that this attenuation of function reflects an adaptive downregulation that prevents the development of metabolic evidence of ischemia during stress. To test this hypothesis, pigs were chronically instrumented with a proximal left anterior descending artery stenosis for 3 months, resulting in severe anteroapical hypokinesis with reduced resting perfusion (0.78+/-0.05 versus 0.94+/-0.07 mL x min(-1)x g(-1) in remote, P<0.01; and 0.99+/-0.08 in controls, P<0.05). Open-chest studies confirmed resting dysfunction compared with normal controls (segment shortening 9.2+/-2.2% versus 23.5+/-1.1%, P<0.05). Resting myocardial oxygen consumption was reduced (63+/-3 versus 77+/-6 microL x g(-1) x min(-1) in controls, P<0.05), yet lactate consumption was normal. Although subendocardial perfusion failed to increase during graded, intravenous epinephrine infusion (n=8), peak segment shortening (to 17.3+/-3.1%, P<0.05) and oxygen consumption (to 90+/-6 microL x g(-1) x min(-1), P<0.01) increased from the depressed resting levels. There was no lactate production in hibernating myocardium, and lactate uptake increased during stress (0.7+/-0.1 to 1.2+/-0.1 micromol x g(-1) x min(-1), P<0.05). The absence of metabolic evidence of ischemia was also confirmed during atrial pacing to a rate of 120 bpm (n=8). Thus, despite reductions in function and oxygen consumption at rest, hibernating myocardium retains the ability to increase metabolism without the development of acute ischemia. This supports the hypothesis that the downregulation of oxygen consumption and function in hibernating myocardium is an adaptive response that prevents a supply-demand imbalance during submaximal increases in cardiac workload when coronary flow reserve is limited.

Adaptation, Physiological↗
PubMed2003

The cardiac innervation of a marsupial heterotherm, the fat-tailed dunnart (Sminthopsis crassicaudata).

This study investigated the pattern of autonomic innervation of the heart of the fat-tailed dunnart (Sminthopsis crassicaudata) using isolated cardiac preparations. While the pattern of autonomic innervation of the atria was consistent with that found in other mammals, the ventricles displayed an unusual pattern of mammalian cardiac innervation. Transmural stimulation of the intramural nerves of isolated right ventricular preparations caused a decrease in the force of contraction of 46.8+/-3.2% followed by a rebound increase in the force of contraction beyond basal levels of 40.9+/-6.9%. These responses could be blocked independently by the application of the muscarinic receptor antagonist hyoscine and beta-adrenoreceptor antagonist propranolol respectively and could also be mimicked by the application of the agonists acetylcholine (Ach) and noradrenaline (NA). These findings indicated the presence of a functional cholinergic innervation of the ventricles that was capable of reducing the force of contraction below basal levels. This pattern of innervation has only been found previously in one other mammal, the bent-winged bat (Miniopterus schreibersii). Given that both of these species are heterotherms, it is possible that such a pattern of innervation may relate to the control of cardiac output during torpor. These findings are the first that demonstrate the homogeneity of a physiological control mechanism in a so-called 'shallow, daily torpidator' (S. crassicaudata) and a 'deep hibernator' (M. schreibersii) that is absent in mammalian homeotherms. These findings are consistent with recent work suggesting that there may be little difference between these types of heterothermy.

Adrenergic Agonists↗
PubMed2000

Hibernating myocardium, stunning, ischemic preconditioning: clinical relevance.

Hibernation is a chronic condition that can be due to either chronic low perfusion or repetitive stunning. When oxygen demands increase, prolonged periods of ischemia occur, resulting in multiple episodes of stunning. Because hibernation may play a significant role in refractory failure, the diagnosis of hibernation followed by reperfusion can be life saving. Myocardium that has sustained a transient sublethal injury but has the potential for recovery with time is referred to as stunned myocardium. Myocardial stunning is commonly seen after coronary artery bypass surgery: variable periods of myocardial ischemia are sustained during coronary artery bypass graft surgery, and when these patients return to the intensive care unit, their ventricular function is severely impaired because of the prolonged anoxia during bypass. With the support of artificial assist devices, counterpulsation or temporary use of catecholamines, these patients improve and have a favorable prognosis. Similarly, recovery occurs with time in stunning that follows AMI or cardiac transplantation because in either case the heart had been temporarily anoxic. Clinical observations of ischemic preconditioning include the following: (1) first-effort angina or "warm-up phenomenon," i.e., angina with exercise early, but similar or greater effort the rest of the day does not cause any angina and (2) mortality of AMI is lower in patients with a history of angina preceding AMI. Angina 1 to 2 hours before AMI is the most effective time window for ischemic preconditioning. A less potent "second window" is observed when angina occurs during the second to fourth day before AMI. Adenosine possesses marked cardioprotective properties and has been used to pharmacologically induce ischemic preconditioning with some success. Work is still in progress.

Adenosine↗
PubMed1998

Radiation exposure and dose to small mammals in radon-rich soils.

Protection of the environment from radionuclide releases requires knowledge of the normal background levels of radiation exposure in the exposed biotic community and an estimate of the detriment caused by additional exposure. This study modeled the background exposure and dose to the lungs of small burrowing mammals from 222Rn in artificial burrows in radon-rich soils at a site in southeastern Manitoba. E-PERM chambers used to measure 222Rn in soil showed good reproducibility of measurement, with an average coefficient of variance (CV) of about 10%. Geometric mean (GM) 222Rn concentrations at nine randomly selected sites ranged from 5,490 Bq/m3 (GSD = 1.57, n = 7) to 41,000 Bq/m3 (GSD = 1.02, n = 5). Long-term monitoring of 222Rn concentrations in artificial burrows showed large variation within and between burrows and did not show consistent variation with season, orientation of the burrow opening, or levels of 226Ra in the soil. Annual GM concentrations in individual burrows ranged from 7,480 Bq/m3 (GSD = 1.60) to 18,930 Bq/m3 (GSD = 1.81) in burrows several meters apart. A grand GM of 9,990 Bq/m3 (GSD = 1.81, n = 214) was measured over the site for the year. An exposure model was constructed for five small mammal species based on their respiration rates and the number of hours spent in the burrow, active or hibernating, exposed to soil gas 222Rn, and the time spent out of the burrow exposed to atmospheric 222Rn. A background dose of 0.9 mGy/a from atmospheric 222Rn (40 Bq/m3) was estimated for a large-bodied (80 kg), nonburrowing animal living on the soil surface. The highest exposures (mJ/a) in burrowing mammals occurred in those species with the highest respiration rates. Hibernation accounted for a small fraction of total annual exposure (<5%) because of very low respiration rates during this period. Absorbed dose to lung (mGy/a) was highest in the pocket gopher and decreased in the larger animals because of larger lung mass. Using mean 222Rn concentrations from the field studies and an equilibrium factor (F) of 0.5, doses to lung ranged from 90 mGy/a in the badger to 700 mGy/a in the pocket gopher. These doses closely correspond to those estimated from published dose conversion factors (DCFs) of 1.4 mGy per mJ . h/m3 for whole lung. For the ground squirrel, the DCF approach gives an estimated dose of 300 mGy/a versus 270 using the respiratory flow rate method. Based on these results, doses exceeding 500 mGy/a may be common in mammals and birds (i.e. the burrowing owl) living in radon-rich soils. Published risk coefficients for small mammals suggest that about 17 cancers would occur in 1,000 animals at these exposure rates. Although the potential effects from these exposures were not examined in this study, the study raises questions about how the animals may respond physiologically to this largely natural stress.

Animals↗
PubMed1995

cAMP-dependent protein kinase and anoxia survival in turtles: purification and properties of liver PKA.

The catalytic subunit of turtle (Trachemys scripta elegans) liver cyclic AMP-dependent protein kinase (PKAc) was purified to homogeneity with a final specific activity of 65,783 pmol phosphate transferred.min-1.mg protein-1. Subunit molecular weight was 42-43 kDa as determined by SDS-PAGE and Sephacryl S-300 chromatography. The isolectric point was pH 6.41 +/- 0.02. Turtle liver PKAc showed highest activity with kemptide as its substrate; activity with other artificial substrates, histone IIA and protamine, was only 21 and 11%, respectively, of the activity with kemptide. Km values were 83 +/- 6.5 microM for Mg.ATP and 11.7 +/- 0.5 microM for kemptide and enzyme activity was strongly reduced by inhibitors of mammalian PKA (H-89, PKA-1) but not by inhibitors of other protein kinases. The enzyme was also inhibited by salts, especially fluoride salts (I50 about 30 mM), and showed a sharp break in the Arrhenius plot (0-45 degrees C) with activation energy increasing by 4-fold from 27.9 +/- 1.85 to 115 +/- 2.5 kJ/mol for temperatures above versus below 15 degrees C. Temperature effects may be important in suppressing PKA function, and therefore PKA-mediated responses, in vivo to enhance anoxic survival time during winter hibernation under water. Analysis of the effects of in vivo anoxia exposure at 7 degrees C on PKA in turtle organs showed a rapid 2.3-fold increase in the amount of active enzyme in liver within 1 h of anoxic submergence accompanied by a 60% increase cAMP levels; with longer anoxia (5 or 20 h) the percentage of active PKA was suppressed to 2.1-3.7% of the total.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2004

Electrical stunning and hibernation: suggestion of new terms for short- and long-term cardiac memory.

Persistent T wave changes following resumption of sinus rhythm induced by pacing or arrhythmias that cause altering of ventricular activation sequence are named "cardiac memory". After this initial definition there has been a discussion whether such T wave changes are primary, secondary or pseudoprimary. In addition according to the results of pathophysiological studies investigating the mechanism and nature of this repolarization abnormality some authors have preferred to use the term "electrical remodelling" instead of cardiac memory. But these two terms are still not well defined. In this article, the previous terms are discussed and a new term instead of cardiac memory is introduced.

Arrhythmias, Cardiac↗
PubMed1995

Application and perspectives of transesophageal stress echocardiography using monoplane and biplane instruments.

Transesophageal stress echocardiography has been reported to have a high sensitivity and specificity for noninvasive identification and assessment of coronary artery disease. Its advantage is the virtually never obstructed acoustic window on the heart yielding superior image quality in almost all patients. Pharmacological stress as well as simultaneous atrial pacing--attaching electrodes to the echoscope--have been applied as stress modalities. Both transesophageal stress echocardiography modalities have been shown to be well tolerated, safe, and feasible in most patients. These promising initial experiences led to clinical application of this method for preoperative risk evaluation, for detection of restenosis after PTCA, and for evaluation of hibernating myocardium. This technique was also successful for evaluation of stress induced changes of transmitral and pulmonary venous flow in patients with left ventricular hypertrophy and coronary artery disease. Although all studies published so far were performed with monoplane technique, the sensitivity for detection of one-vessel and, even more so, multivessel disease was high. However, apical and basal wall-motion abnormalities may go undetected using monoplane equipment. The advent of biplane transesophageal imaging enables the visualization of more ventricular segments. Future studies will show to which degree biplane transesophageal stress echocardiography improves the diagnostic accuracy.

Angioplasty, Balloon, Coronary↗
PubMed2000

Contrasting stress response of male arctic ground squirrels and red squirrels.

A hormonal-challenge protocol was used to compare the stress response of males of Arctic ground squirrels and red squirrels during the breeding season (May). These squirrels live in the same boreal forest of the Yukon, but have very different life histories and utilize the forest in markedly different ways. Red squirrels had levels of total cortisol, maximum corticosteroid-binding capacity, and free cortisol that were 5, 7, and 2 times, respectively, those of Arctic ground squirrels. Red squirrels were resistant to suppression by an artificial glucocorticoid, dexamethasone (DEX); Arctic ground squirrels were not. Cortisol levels in red squirrels responded slowly but continuously to the ACTH injection; Arctic ground squirrels responded rapidly and then stabilized. Testosterone levels in red squirrels were extremely sensitive to the challenge, being suppressed by both DEX and ACTH; levels in Arctic ground squirrels were resistant to the challenge, being modestly suppressed by DEX and stimulated by ACTH. Energy mobilization, as measured by glucose and free fatty acid responses, was not affected. Red squirrels had four times the levels of white blood cells and higher proportions of lymphocytes and lower proportions of eosinophils than Arctic ground squirrels, indicating that the latter were in worse condition immunologically. Our evidence suggests that the functions associated with the hypothalamic-pituitary-adrenal axis are compromised in breeding male Arctic ground squirrels, but not in red squirrels. We propose that in male red squirrels this axis has evolved in the context of a stable social system based on long-lived animals with individual territories which are needed to deal with unpredictable winter food supplies. In contrast, Arctic ground squirrels escape the rigors of winter by hibernation and this hormonal axis has evolved in short-lived males in the context of intense intra-sexual competition in a social system based on female kin groups and regular male dispersal to avoid inbreeding. J. Exp. Zool. 286:390-404, 2000.

Adaptation, Physiological↗
PubMed1985

[Neurochemical mechanisms of artifical hypobiosis and chemical thermoregulation].

Artificial hypobiosis in rats and rabbits was modelled using ornid which caused the blockade of neurotransmitter release from adrenergic neurons. The data obtained corroborated the hypothesis of the mechanisms of chemical thermoregulation as well as new ways of controlling these processes up to their complete blockade by means of decreasing adrenergic effects in the organism. Warm-blooded animals were transferred into poikilothermic state and then into hypobiosis under any given body temperature. At 18-20 degrees C, metabolism may be decreased to 1/10 of standard values and the state of hypobiosis may be maintained for a prolonged period remaining eversible without application of any drugs activating or blocking physiological functions.

Adrenergic Fibers↗
PubMed1993

Acidosis and metabolic rate in golden mantled ground squirrels (Spermophilus lateralis).

In this study, three series of experiments were conducted on euthermic, anesthetized, artificially ventilated golden mantled ground squirrels (Spermophilus lateralis), each of which altered pHa in a different fashion. In Series I, animals were randomly hypo- or hyper-ventilated. On average, pHa changed from 7.13 to 7.59, PaCO2 from 59.2 to 23.6 Torr, and PaO2 from 45.8 to 57.2 Torr between the two conditions, respectively. VO2 showed a significant positive correlation with pHa (r = +0.84) as well as PaO2 (r = + 0.60). In Series II, respiratory acidosis was produced by pump-ventilating animals with up to 10% inspired CO2 to reduce pHa to within the range 7.40 to 7.20. On average, pHa was reduced to 7.30, PaO2 to 50.1 Torr and PaCO2 was increased to 56.7 Torr. As in Series I, there was a significant positive correlation between VO2 and pHa (r = +0.78) and between VO2 and PaO2 (r = +0.71). In Series III, metabolic acidosis was produced by infusing lactic or acetic acid intravenously for 20 to 30 min. This reduced pHa from 7.56 to 7.32, PaO2 from 70.2 to 58.9 Torr, and elevated PaCO2 from 26.9 to 37.9 Torr (P < 0.05 in all cases). Contrary to Series I and II, VO2 increased with a decline in pHa (r = -0.65, P < 0.05) and PaO2 (r = -0.55, P < 0.05). Thus, despite a significant decline in pHa and PaO2 and an elevation of PaCO2 during all three series, VO2 changed in opposite directions during respiratory and metabolic acidosis. We conclude that whatever the mechanism involved, hypoventilation during the early stages of entrance into hibernation can contribute to the fall in metabolic rate.

Acidosis↗