Duration Of Anoxia Research Articles

Current Procedures in China on Replantation of Severed Limbs and Digits

Since the first successful replantation of a severed right hand was reported in 1963, surgeons in China have performed more than 3735 replantations of limbs and digits with increasing improvement in the survival rate. Of special interest is that local hospitals have reported numerous successful cases revealing a popularization of this kind of operation in China. The replantation survival rate is related to the type of injury and duration of anoxia. The types of injury include avulsion or crush amputation, severed distal segments of fingers, immersion conditions, amputated limbs or digits in children, and segmental resection of diseased tissues. The results are analyzed by a special system of functional evaluation.

Heterogeneity of cell response to early anoxia and reoxygenation in rat heart

Heterogeneous cell injury and increased tissue calcium levels were observed in the isolated rat hearts perfused with anoxic medium for 5, 10, 15, 20, 25 and 30 min. These changes were intensified after reoxygenation of the anoxic hearts. The cell injury was quantitated using a score of 0, 1, 2 or 3 (0 being normal and 3 being severe injury). All four classes of cells were present even after 5 min of anoxia. The injury and calcium content increased with increase in duration of anoxia. Reduction in the percentage of injured cells was observed on reoxygenation of hearts perfused with anoxic medium for 5 to 20 min. However, reoxygenation of hearts initially perfused with anoxic medium for 25 to 30 min resulted in a higher percentage of injured myocytes. Beneficial effects of reoxygenation were observed in the anoxic hearts when the percentage of cells with an injury score of 1 and glycogen deposit were high, coupled with low calcium levels.

Effect of hemorrhage and anoxia on hepatic gluconeogenesis and potassium balance in the rat.

Previous investigations have demonstrated impairment of hepatic gluconeogenic activity during both hypovolemia and sepsis, but the mechanisms responsible remain unclear. The present study was designed to determine the influence of lack of oxygen on gluconeogenesis independent of humoral factors, products of ischemic peripheral tissues or pH changes. Livers obtained from Sprague-Dawley rats fasted 24 hours were perfused with Krebs-Henseleit buffer containing 5 mM lactate for 30 minutes. In the control group (n = 8) perfusion was continued; in others, anoxia was induced by perfusing with buffer equilibrated with 95% N2 and 5% CO2 for periods of 15, 30, or 60 minutes (n = 4, 5, and 5, respectively). The initial conditions were then reinstituted for an additional 45 minutes. Anoxia caused hepatic release of K+, indicative of disordered hepatic cellular ionic gradients and an abrupt cessation of gluconeogenesis. Reoxygenation partially reversed these alterations but some impairment of gluconeogenesis persisted and the degree of uptake of K+ from the perfusion media was decreased as the duration of anoxia increased. The degree of restoration of gluconeogenesis after a period of anoxia was closely associated with restoration of cellular uptake of K+. By comparison, livers taken from hypovolemic animals maintained at a mean arterial blood pressure of 40 mm Hg until the beginning of the decompensatory stage of shock exhibited a gluconeogenic capacity of only 41% of control animals and was comparable to the compromise induced by between 30 and 60 minutes of anoxia. These results suggest that the abilities to restore hepatic electrolyte balance and gluconeogenesis after oxygen deprivation are affected in parallel and may reflect a common dependence on the restoration of ATP stores after the insult.

Anaerobic heat production of bivalves (Polymesoda caroliniana andModiolus demissus) in relation to temperature, body size, and duration of anoxia

Anaerobic heat-production rates of two co-occurring species of estuarine bivalves (a clam and a mussel) were measured with double-twin heat-flow calorimeters, one at 20°C, the other at 30°C. There is no significant difference between the two species in metabolic rates. There is evidence of initial aerobic metabolism in some individuals, as shown by high initial rates exponentially decreasing with time, while others had fluctuating but stable average metabolic activity from the beginning. During aerobic as well as anaerobic metabolism, the bivalves showed rhythmic periods of activity and quiescence. The two species differed in their rhythmic pattern of active and resting metabolism. In the case ofPolymesoda caroliniana, periods of resting metabolism tend to be longer and periods of active metabolism shorter at 30°C than at 20°C. There is a similarity between thermograms ofModiolus demissus at 20° and 30°C. Following acute temperature changes from 5° to 20° and 30°C, the bivalves showed stable metabolic rates in a matter of hours. The stabilized average rates [pooled averages for both species of 1.34×10-4 (standard error of the mean=0.17×10-4) W g-1 dry weight of tissue at 20°C and 2.10×10-4 (SE=0.20×10-4) W g-1 at 30°C] signify a temperature coefficient (Q10) of 1.56 between 20° and 30°C, or partial temperature acclimation. Subtracting heat production as a result of physical activity, i.e., considering only resting metabolism, the corresponding means and standard errors of the means are 1.24×10-4 and 0.14×10-4 W g-1 at 20°C and 1.91×10-4 and 0.077×10-4 W g-1 at 30°C. Anaerobic heat production rate at 20°C is proportional to body size (r=0.84, 9 degrees of freedom, DF). ForM. demissus, measured anaerobic heat production is on the order of 7.5% of the level of aerobic respiration reported in the literature.

Effect of local anoxia upon endocochlear potential of guinea pig (author's transl)

The effect of local anoxia upon the endocochlear potential (EP) was examined by pressing the labrinthine artery for 10 to 120 minutes on 30 normal guinea pigs. The EP started to decline within a few seconds after cessation of the blood supply and the survival time (the time elapsed to reach 0mV)was 48.8±8.0 seconds. After the varying period of anoxia, the pressure was released to reestablish the blood suppy and the effect of re-oxygenation upon the EP was examined.In animals subjected to 10 to 20 minutes' anoxia, the EP returned to the preischemic level by the release. When the duration of anoxia was 30 milnutes or longer, the recovery of the potential was incomplete and the duration of anoxia was directly related to the recovery of EP. In other words, the longer the duration of anoxia is, the lower the level of the EP after re-oxygenation.It should be noted that the EP showed the recovery to the level of+20 to 40 mV even after 120 minutes of anoxia. The possible role of transient anoxia on sudden deafness was discussed based on these results.

Enhanced lysosome fragility in the anoxic perfused guinea pig heart: Effects of glucose and mannitol

Guinea pig hearts were perfused under aerobic and anoxic conditions in the presence and absence of glucose or mannitol. Samples of the coronary perfusate were collected and assayed for creatine phosphokinase (CPK), hydroxybutyrate dehydrogenase (HBDH), leucyl-β-naphthylamidase (LBN) and lysosomal enzyme activities. After various periods of perfusion samples of left ventricle were homogenized and the specific activities (mu/mg protein) of N-acetyl-β-glucosaminidase, N-acetyl-β-galactosaminidase, β-glucuronidase and cathepsin C were determined. Estimates of lysosomal integrity were made from measurements of the latency and sedimentability of the marker enzymes. In control aerobic studies, with or without glucose or mannitol, there was an initial wash-out of CPK, HBDH and LBN with no further enzyme release for up to 6 h. The specific activities and the latency and sedimentability values of the lysosomal enzymes in cardiac homogenates were generally unaffected by aerobic perfusions. In contrast, during anoxic perfusions in the absence of glucose large amounts of CPK, HBDH and LBN were released into the coronary perfusate. The latency and sedimentability of each of the lysosomal enzymes was considerably decreased as a result of anoxic perfusion indicating enhanced lysosome fragility. These changes were significant after 30 min and progressed with the duration of anoxia. The specific activities of the lysosomal enzymes were significantly increased after 6 h anoxic perfusion. Inclusion of glucose in the anoxic perfusion medium did not prevent the release of CPK, HBDH and LBN in the early stages of anoxia but a reduction in myocardial enzyme release was observed in the later stages. The presence of glucose considerably delayed the onset of lysosomal membrane labilization but caused further increases in the specific activities of three of the acid hydrolases. Equimolar concentrations of mannitol had a limited effect on lysosome stability indicating that the protective effect of glucose was mainly due to its metabolic action.

Anaerobic respiration in the polychaete Euzonus (Thoracophelia) mucronata

The intertidal polychaete Euzonus mucronata (Treadwell) is found in great numbers within beach sands that undergo periodic anoxia. Short-term exposures (2 to 4 h) to anaerobicity are withstood through the use of a supply of oxyhemoglobin to support continued aerobic metabolism. Longer periods of environmental anoxia activate an anaerobic metabolism capable of sustaining life for up to 20 days, and characterized by the excretion of succinate and propionate. These two mechanisms appear to be adaptations to the variations in occurrence and duration of anoxia within the intertidal sands inhabited by E. mucronata.

An accurate method for estimating 5-phosphoribosyl 1-pyrophosphate in animal tissues with the use of acid extraction

In determination of the tissue content of 5-phosphoribosyl 1-pyrophosphate (PRPP), heat treatment has been generally used for the extraction. However, the procedure appeared to need well-controlled conditions which should be determined for each different tissue by preliminary examinations. Thus, extraction with perchloric acid was examined and found to give satisfactory results if combined with rapid processing of the tissues. The decomposition of the compound, though less than 20% by the procedure used, was corrected based on the recovery of 3H-labeled PRPP which was added at the step of homogenization. The acid extraction eliminated interfering enzyme activities in the extract and assured, together with the use of the internal standard, a high degree of reproducibility. It was also shown that the duration of anoxia that inevitably happens when animal tissues are excised must be minimized to the order of a few seconds.

Metabolic alterations in brain during anoxic-anoxia and subsequent recovery.

Until a few years ago, it was generally thought that irreversible brain damage would result from any condition that produced a profound cerebral anoxia of greater than eight to ten minutes' duration. This conclusion was based on observations made by physicians during clinical emergencies and by investigators using experimental models in which the onset, degree, and duration of anoxia could be controlled. 1-6 Most techniques for producing anoxia in the intact animal also produce ischemia and there is some evidence to suggest that cerebral anoxia is exacerbated by ischemia. 7 However, the results of recent studies with totally ischemic brain tissue suggest that many of the variables measured approach normal after reoxygenation. This has led some workers to question whether cerebral anoxia actually causes irreversible brain damage within so short a period as ten minutes. 8-11 If proper protocols are to be established for the treatment of cardiac arrests and

INFLUENCE OF OXYGEN, HELIUM, AND METABOLIC INHIBITION ON X-RAY INDUCED DOMINANT LETHALITY IN STAGE 7 AND STAGE 14 OOCYTES OF DROSOPHILA MELANOGASTER.

Experiments designed to test the effects of various oxygen tensions given before, during, and after the x irradiation of adult females on the survival of Stage 7 and Stage 14 oocytes support the conclusion that no significant differences in the relative radiosensitivity between Stage 7 and Stage 14 oocytes is attributabie to differential amounts of intracellular oxygen. Extended helium pre- or posttreatment causes a significant increase in x-ray- induced dominant lethality in Stage 7 oocytes. This increase in lethality is proportional to the duration of anoxia. No such sensitizing effect of helium treatment is observed with the Stage 14 cells. The effect of anoxia in increasing dominant lethality is prevented when the flies are given anoxic treatments at 4 deg C. The effects of anoxic pretreatment are reversed when the cells are allowed to recover in air prior to irradiation. The results are interpretable in terms of a system that repairs chromosome breaks and that is depleted during prolonged anoxia. (auth)

ACUTE TUBULAR NEPHROSIS IN THE NEWBORN INFANT, A MANIFESTATION OF ANOXIA

The presence of cellular renal casts in the newborn infant is considered evidence of renal tubular injury. A cause-and-effect relationship between anoxia and these renal lesions is suggested by this study. The histopathologic manifestations of tubular disease best demonstrated in sections stained for fat and with the periodic acid-Schiff routine are dependent not only upon the severity and duration of anoxia, but also upon the length of survival after injury. In this regard, the finding of urinary cellular casts in the newborn infant may suggest to the clinician an early and vigorous approach against the pathologic effects of anoxia.

Asphyxia neonatorum: An experimental study in the guinea pig

Asphyxia neonatorum: An experimental study in the guinea pig