Decompression outcome following saturation dives with multiple inert gases in rats

This investigation examined the question of whether gas mixtures containing multiple inert gases provide a decompression advantage over mixtures containing a single inert gas. Unanesthetized male albino rats, Rattus norvegicus, were subjected to 2-h simulated dives at depths ranging from 145 to 220 fsw. At pressure, the rats breathed various He-N2-Ar-O2 mixtures (79.1% inert gas-20.9% O2); they were then decompressed rapidly (within 10 s) to surface pressures. The probability of decompression sickness (DCS), measured either as severe bends symptoms or death, was related to the experimental variables in a Hill equation model incorporating parameters that account for differences in the potencies of the three gases and the weight of the animal. The relative potencies of the three gases, which affect the total dose of decompression stress, were determined as significantly different in the following ascending order of potency: He less than N2 less than Ar; some of these differences were small in magnitude. With mixtures, the degree of decompression stress diminished as either N2 or Ar was replaced by He. No obvious advantage or disadvantage of mixtures over the least potent pure inert gas (He) was evident, although limits to the expectation of possible advantage or disadvantage of mixtures were defined. Also, model analysis did not support the hypothesis that the outcome of decompression with multiple inert gases in rats under these experimental conditions can be explained totally by the volume of gas accumulated in the body during a dive.     

Effect of dehydrocorrine-cobalt complex on mitochondria

The effects of the decamethyloctadehydrocorrine-cobalt complex (Co-C) on respiration and the ATP-synthetase activity of rat liver mitochondria were investigated. The Co-C complex was found to be an effective shunt of the respiratory chain. It accepts electrons from ubiquinone and donates them directly to O2. The Co-C complex inhibits the ATPase and ATP-synthetase activities of mitochondria.     

Large deformation mechanics of the enucleated eyeball

Large deformation of enucleated pig eyeballs under rigid cylindrical indenters was studied analytically and experimentally. The analytic model for the eyeball consists of a fluid-filled spherical membrane composed of an incompressible, elastic material with an exponential strain energy function. The Rayleigh-Ritz technique provided an approximate solution via a potential energy formulation. Comparison with results from tests on eyeballs and a water-filled rubber (Mooney-Rivlin) shell shows good agreement at large deflection, where membrane action dominates. Due to the highly nonlinear stress-strain relations for the sclera, the load remains relatively small until the indenter displacement approaches 40-60 percent of the eyeball radius, and then the load increases rapidly. Depending on the indenter size, either a perforation or a rupture type of failure occurs.     

Congenital dyserytropoietic anaemia, type II (HEMPAS) in three siblings

These siblings of a Czech family aged 21, 19 and 6 years, respectively, with congenital dyserythropoietic anemia, type II, (HEMPAS) are reported. In two elder siblings ferrokinetic studies revealed a rapid plasma 59Fe clearance, markedly decreased erythrocyte incorporation and shortened 51Cr red-cell survival. Direct anti-globulin test was found positive in one of them. Further investigations revealed low values of blood plasma cholesterol, total lipids, beta-lipoproteins, beta-carotine and vitamin E and A as well as low values of the prothrombin complex. Liver biopsy demonstrated siderosis and disseminated intravascular coagulation in the liver in both patients. The possible reasons for these humoral aberrations are discussed.     

Inhibition of protein and lipid synthesis in muscle by 2,4-dinitrofluorobenzene, an inhibitor of creatine phosphokinase

A photoaffinity label, 4-azidobenzoyltrimethionine has been synthesized. It competitively inhibits trimethionine uptake in the yeast C. albicans. Upon UV irradiation it irreversibly and specifically blocks oligopeptide uptake. These results give the first example of photoinhibition of peptide uptake in yeast.     

Values,Errors, and Precautions

In the environmental health literature, errors in interpreting studies or data are not infrequent. Many are of the Type II variety. Common solecisms of this type are: treating the criterion of p < 0.05 as a sacrament; demanding complete confounder control; arguing for the existence of phantom confounders; arguing that the effect size is trivial; building nonveridical models; arguing for no effect from inadequate sample size; demanding causal proof; arguing that causality is reversed; conducting a ballot of published studies. These are examined in this paper.     

Diversification of Hawaiian Cyrtandra (Gesneriaceae) under the influence of incomplete lineage sorting and hybridization

Cyrtandra (Gesneriaceae) is a genus of flowering plants with over 800 species distributed throughout Southeast Asia and the Pacific Islands. On the Hawaiian Islands, 60 named species and over 89 putative hybrids exist, most of which are identified on the basis of morphology. Despite many previous studies on the Hawaiian Cyrtandra lineage, questions regarding the reconciliation of morphology and genetics remain, many of which can be attributed to the relatively young age and evidence of hybridization between species. We utilized targeted enrichment, high‐throughput sequencing, and modern phylogenomics tools to test 31 Hawaiian Cyrtandra samples (22 species, two putative hybrids, four species with two samples each, one species with four samples) and two outgroups for species relationships and hybridization in the presence of incomplete lineage sorting (ILS). Both concatenated and species‐tree methods were used to reconstruct species relationships, and network analyses were conducted to test for hybridization. We expected to see high levels of ILS and putative hybrids intermediate to their parent species. Phylogenies reconstructed from the concatenated and species‐tree methods were highly incongruent, most likely due to high levels of incomplete lineage sorting. Network analyses inferred gene flow within this lineage, but not always between taxa that we expected. Multiple hybridizations were inferred, but many were on deeper branches of the island lineages suggesting a long history of hybridization. We demonstrated the utility of high‐throughput sequencing and a phylogenomic approach using 569 loci to understanding species relationships and gene flow in the presence of ILS.