Bubble formation in crabs induced by limb motions after decompression

In vivo bubble formation was studied in the megalopal stage of the crab Pachygrapsus crassipes. The animals were equilibrated with elevated argon, nitrogen, or helium pressures then rapidly decompressed to atmospheric pressure. Voluntary motions induced bubble nucleation in leg joints after exposures to as low as 2 atm nitrogen (gauge pressure). Delays of several minutes sometimes passed between decompression and bubble formation. Mechanically stimulating the animals to move their legs increased this bubble formation, whereas immobilizing the legs before gas equilibration prevented it, even in animals decompressed from 150 atm nitrogen. We conclude that preformed nuclei are not responsible for bubbles developing in the legs of this animal. Instead, tribonucleation of bubbles apparently occurs as a result of limb motions at relatively low gas supersaturations.     

Glycolytic intermediates induce amorphous calcium carbonate formation in crustaceans

It has been thought that phosphorus in biominerals made of amorphous calcium carbonate (ACC) might be related to ACC formation, but no such phosphorus-containing compounds have ever been identified. Crustaceans use ACC biominerals in exoskeleton and gastroliths so that they will have easy access to calcium carbonate inside the body before and after molting. We have identified phosphoenolpyruvate and 3-phosphoglycerate, intermediates of the glycolytic pathway, in exoskeleton and gastroliths and found them important for stabilizing ACC.     

Blood biochemical factors in humans resistant and susceptible to formation of venous gas emboli during decompression

Blood biochemical parameters were measured in 12 male human subjects before and after exposure to a staged decompression protocol, with simulated extravehicular activity, during 3 days. Following the exposure, significant changes occurred in several parameters, including increases in blood urea nitrogen, inorganic phosphate, potassium, and osmolality, and decreases in uric acid and creatinine. Pre-exposure blood samples from subjects who were susceptible to formation of venous gas emboli (VGE) during decompression exhibited significantly greater levels of total cholesterol, high density lipoprotein cholesterol, potassium, inorganic phosphate, calcium, and magnesium. The results indicate that, following this decompression profile, small but significant (P less than 0.05) changes occur in several blood biochemical parameters, and that levels of certain blood factors may be related to susceptibility to VGE formation during decompression.     

Renal functions following hyperbaric oxygen toxicity in conscious rats

The after-effects of renal function were studied in rats exposed to hyperbaric oxygen (HBO) at either 4.8 ATA for 60 min or 6.8 ATA until the onset of convulsions. Only the rats which suffered from HBO convulsions were found to have alterations in renal function. It was observed that 4 hr after convulsions, there was a decrease in urinary excretion of urea and creatinine, which resulted in an elevation of blood urea nitrogen (BUN) and creatinine. Clearances of inulin and p-aminohippuric acid showed a decrease in the glomerular filtration rate and effective renal blood flow 4 hr after HBO convulsions. These parameters nearly returned to normal in 24 hr after convulsions. The renal handling of a large volume of infused saline was also retarded 4 hr after HBO convulsions, but by the end of 24 hr after HBO convulsions, it was much improved. Therefore, it was concluded that the renal function was altered after HBO convulsions, but nearly recovered in 24 hr.     

Acetylcholine formation from glucose following acute choline supplementation

The effects of choline administration on acetylcholine metabolism in the central nervous system are controversial. Although choline supplementation may elevate acetylcholine (ACh) content in brain, turnover studies with labelled choline precursors suggest that systemic choline administration either has no effect or actually diminishes brain ACh synthesis. Since choline supplementation elevates brain choline levels, the apparent decreases in previous turnover studies may reflect dilution of the labelled choline precursor pool rather than altered ACh formation. Therefore, brain ACh formation from [U-¹⁴C]glucose was determined after choline supplementation. A two to three fold elevation of brain choline did not alter ACh levels or [U-¹⁴C]glucose incorporation into ACh in the cortex, hippocampus or striatum. Although atropine stimulated ACh formation from [U-¹⁴C]glucose in hippocampus, two to three fold increases in brain choline did not augment ACh synthesis or content in atropine pretreated animals. Atropine depressed brain regional glucose utilization and this effect was not reversed by choline treatment. These results suggest that shorttern elevation of brain choline does not enhance ACh formation from [U-¹⁴C]glucose, and argue against enhanced presynaptic cholinergic function after acute, systemic choline administration.Special issue dedicated to Dr. Louis Sokoloff.     

Reparative processes in cardiac muscle following exposure to hyperbaric oxygenation

In 150 rabbits by means of histoautoradiographic, histochemical and certain histological methods, reparative processes in the cardiac muscle have been studied at experimental myocardial infarction and its combination with atherosclerosis under various regimes of hyperbaric oxygenation (HBO). It has been demonstrated that HBO (pO2--2 kgs/cm2, saturation time--45 min, 3-7 sessions) positively affects the proliferative processes in the ischemic zone, contributes to better preservation of the periinfarction parts of the myocardium and enhances maturation of the scar. If HBO is used in another regime (pO2--1 kgs/cm2, saturation time--30 min, 1-7 sessions), its positive effect on the regenerative processes in the ischemic zone is preserved, while its toxic effect on distant cardiac zones decreases considerably.     

Trace metals in edible marine molluscs and crustaceans from Lebanon

Samples of the edible tissue of cephalopod molluscs (cuttlefish, squid, octopus) and crustaceans (lobster, shrimp) collected off the coast of Lebanon were found to concentrate similar levels of cadmium, copper, nickel, and chromium. Lead and zinc were highest in the cephalopods and iron was highest in the crustaceans.The molluscs collected from Beirut had higher levels of many metals than those taken from the other locations. The Beirut octopus had higher lead, cadmium, copper, iron, and chromium. Lead, cadmium, and copper were also highest in the Beirut cuttlefish while iron and zinc were elevated. The crustaceans from Beirut showed no strong tendency to concentrate higher metal levels, except for the Beirut lobster which had higher copper than the other samples.In the cuttlefish, the analysis of bone showed generally higher cadmium, zinc, nickel, and chromium but lower copper and iron than the muscle. However, at Beirut, the bone samples had much higher iron. Levels of most metals in the exoskeletons of the lobster and shrimp were quite similar to those in the muscle tissue with the exception of iron in the lobster which was highest in the exoskeleton, and zinc in both crustaceans, which was more highly concentrated in the muscle.     

Genotype- and age-associated in vivo cytogenetic alterations following mutagenic exposures in mice

We studied mice from eight genetic strains at two ages (young, 10 weeks; and old, more than 80 weeks) for cytogenetic alterations (sister chromatid exchange (SCE), micronuclei, and metaphase indices) following challenges by two known mutagens: N-nitrosoethyl urea (ENU, 17 mg/kg) and cyclophosphamide (CP, 4.5 mg/kg) on bone marrow cells in vivo. The data were used to evaluate the effect of age, genotype, and differential aging patterns of genotypes in relative susceptibility to chromosomal breakage and instability in otherwise normal individuals. The older animals had a higher frequency of micronuclei, reduced metaphase indices, and lower SCE/cell as compared with their younger counterparts. Treatment with both mutagens significantly increased micronuclei and SCEs/cell in almost all strains at both ages but had little effect on the frequency of cells in metaphase. Among individual differences for SCEs/cell at most treatment combinations were not significant. In general, the induced SCEs (treatment-control) are significantly higher in older animals, variable among strains, and relatively higher as a result of CP than the ENU treatment. When the age effect was evaluated as the difference of SCE/cell in old and SCE/cell in young animals of each genotype-treatment combination, an age-dependent pattern was evident. In the presence of a mutagen the pattern in aging response was highly variable and strain (genotype) dependent. This variability may be viewed as subtle inherent genetic predisposition of sensitivity to mutagens that could be evaluated only using sensitive measures (e.g., SCE and not micronuclei) following more than one mutagenic challenges. These subtle differences could become pronounced when these parameters are evaluated at different ages on the same genotype.(ABSTRACT TRUNCATED AT 250 WORDS)     

Recovery of protein from reverse micelles through gas hydrate formation

The recovery of cytochrome c and ribonuclease A from di-2-ethylhexyl sodium sulfosuccinate (AOT) reverse micelles have been examined by the gas hydrate formation. The recovery of cytochrome c depended upon the kind of gas and the water content (w0=[H₂O]/[AOT]) of reverse micellar solution containing cytochrome c prepared. Recoveries of cytochrome c and ribonuclease A were more than 80%, when 1,1,1,2-tetrafluoroethane (TFE) was used as a hydrating gas. The activity of cytochrome c recovered from reverse micelles was maintained perfectly.     

Lactic acid formation in crustaceans and the liver function of the midgut gland questioned.

1. The possibility of the midgut gland of the crustacean (Cherax destructor) functioning as a liver has been investigated. 2. Seven species of crustaceans accumulate lactic acid in the haemolymph when exercised. The rate of disappearance of lactate in Homarus gammarus and in C. destructor is very slow when compared with man. 3. In the midgut gland of C. destructor no firm evidence was obtained for gluconeogenesis from lactate and for ketogenesis from fatty acids. 4. It is concluded that there is at present no justification for the common practice of calling the midgut gland an hepatopancreas.     

A high incidence of jaagsiekte following experimental cold exposures in housed sheep

The fortuitous occurrence of cases of jaagsiekte (sheep pulmonary adenomatosis) in a group of young Scottish Blackface sheep exposed to experimental cold stress is described. The incidence (11/62 cases) was high and the age of onset early (less than 20 months) by comparison with the authors' local experience of the disease. There was also some indication that males were more susceptible (9/26) than females (2/36). The results are not conclusive, but suggest the need for similar cold stress experiments in animals deliberately infected with the disease.

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Zusammenfassung Es wird über das zufällige Auftreten von Jaagsiekte (Lungenadenomatose der Schafe) in einer Gruppe von Schottisch-Blackface Schafen berichtet, die in einem Kältebelastungsversuch verwendet wurden. Die Häufigkeit war hoch (11/62 Fälle) und nach den Erfahrungen der Autoren früh, denn die Tiere waren unter 20 Monate alt. Ausserdem bestanden Hinweise auf Geschlechtsunterschiede in der Empfindlichkeit, weil mehr männliche (9/26) als weibliche Tiere (2/36) erkrankten. Die Ergebnisse sind nicht endgültig. Zur weiteren Abklärung sind Versuche erforderlich, in denen vorsätzlich infizierte Tiere der gleichen Kältebelastung ausgesetzt werden.

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Resume On rapporte ici sur l'apparition fortuite de "Jaagsiekte" (adénomatose pulmonaire du mouton) dans un groupe de moutons de la race écossaise à face noire faisant l'objet d'un essai de contrainte au froid. La fréquence des cas d'infections était élevée (11 bêtes malades sur 62) et très précoce selon l'expérience des auteurs, les animaux n'étant âgés que de 20 mois au plus. En outre, on en tire certaines indications concernant une différence possible entre les sexes, vu que la proportion des béliers atteints (9/26) est nettement plus élevée que celle des brebis malades (2/36). Ces résultats ne sont cependant pas définitifs. Afin de les compléter, il faudrait placer des animaux préalablement infectés dans des conditions semblables de contrainte au froid.

     

Chromosome aberrations in relation to radiation dose following partial-body exposures in three populations

Structural chromosome aberrations were evaluated in peripheral blood samples obtained from three populations exposed to partial-body irradiation. These included 143 persons who received radiotherapy for enlarged thymus glands during infancy and 50 sibling controls; 79 persons irradiated for enlarged tonsils and 81 persons surgically treated for the same condition during childhood; and 77 women frequently exposed as young adults to fluoroscopic chest X rays during lung collapse treatment for tuberculosis (TB) and 66 women of similar ages treated for TB with other therapies. Radiation exposures occurred 30 and more years before blood was drawn. Doses to active bone marrow averaged over the entire body were 21, 6, and 14 cGy for the exposed thymic, tonsil, and TB subjects, respectively. Two hundred metaphases were scored for each subject, and the frequencies of symmetrical (stable) and asymmetrical (unstable) chromosome aberrations were quantified in 97,200 metaphases. Cells with stable aberrations were detected with greater frequency in the irradiated subjects compared with nonirradiated subjects in all three populations, and an overall test for an association between stable aberrations and partial-body ionizing radiation was highly significant (P less than 0.001). We found no evidence that radiation-induced aberrations varied by age at exposure. These data show that exposure of children or young adults to partial-body fractionated radiation can result in detectable increased frequencies of stable chromosome aberrations in circulating lymphocytes 30 years later, and that these aberrations appear to be informative as biological markers of population exposure.     

Cerebral hypoperfusion during hypoxic exercise following two different hypoxic exposures: independence from changes in dynamic autoregulation and reactivity

We examined the effects of exposure to 10-12 days intermittent hypercapnia [IHC: 5:5-min hypercapnia (inspired fraction of CO(2) 0.05)-to-normoxia for 90 min (n = 10)], intermittent hypoxia [IH: 5:5-min hypoxia-to-normoxia for 90 min (n = 11)] or 12 days of continuous hypoxia [CH: 1,560 m (n = 7)], or both IH followed by CH on cardiorespiratory and cerebrovascular function during steady-state cycling exercise with and without hypoxia (inspired fraction of oxygen, 0.14). Cerebrovascular reactivity to CO(2) was also monitored. During all procedures, ventilation, end-tidal gases, blood pressure, muscle and cerebral oxygenation (near-infrared spectroscopy), and middle cerebral artery blood flow velocity (MCAv) were measured continuously. Dynamic cerebral autoregulation (CA) was assessed using transfer-function analysis. Hypoxic exercise resulted in increases in ventilation, hypocapnia, heart rate, and cardiac output when compared with normoxic exercise (P < 0.05); these responses were unchanged following IHC but were elevated following the IH and CH exposure (P < 0.05) with no between-intervention differences. Following IH and/or CH exposure, the greater hypocapnia during hypoxic exercise provoked a decrease in MCAv (P < 0.05 vs. preexposure) that was related to lowered cerebral oxygenation (r = 0.54; P < 0.05). Following any intervention, during hypoxic exercise, the apparent impairment in CA, reflected in lowered low-frequency phase between MCAv and BP, and MCAv-CO(2) reactivity, were unaltered. Conversely, during hypoxic exercise following both IH and/or CH, there was less of a decrease in muscle oxygenation (P < 0.05 vs. preexposure). Thus IH or CH induces some adaptation at the muscle level and lowers MCAv and cerebral oxygenation during hypoxic exercise, potentially mediated by the greater hypocapnia, rather than a compromise in CA or MCAv reactivity.     

Formation of gas bubbles in biological tissues in decompression (a mathematical model)

A mathematical model simulating transport of gases between a bubble resulted from decompression and tissue around is presented. With the help of the model the influence of gas mixture and density of the bubble forming centres upon the growth rate was studied. An important part of CO2 in the bubble forming was found out. The bubbles with He have been shown to grow faster than those with N2. At a 5-10-fold decrease of the outer pressure during 1-2 seconds the bubbles can reach sizes which violate hemodynamics in the system of microcirculation.     

Hemolymph clotting in crustaceans: Implications for neuropeptide extraction from invertebrate hemolymph

The hemolymph of invertebrates contains factors that facilitate clotting as a defense mechanism for injury. However, the clotting process may impair the measurement of hormone titers by interfering with the extraction of peptides. Using hemolymph from freshwater crayfish, our results demonstrate that hemolymph clotting appears to reduce both the amount of an endogenous peptide(s) (Dippu-AST 11-like) extracted from hemolymph, as well as the amount of spiked peptide tracer ([125I]-Dippu-AST 11) recovered from hemolymph. The efficacy of peptide extraction from hemolymph was improved by collecting the hemolymph into a variety of different media prior to hemolymph coagulation. Hemolymph samples collected into media containing the anticoagulant, citrate, had the highest amount of endogenous Dippu-AST 11-like peptide extracted as well as the highest percent recovery of spiked tracer.