Characterization of a halotolerant-psychroloterant bacterium from dry valley Antarctic soil.

The saline soils of the ice free dry valleys of Victoria Land, Antarctica may provide the closest analog on Earth to Martian conditions. We have initiated a study aimed at examining microbial adaptations to the harsh environment of these dry valley soils. In this report we describe the characterization of one bacterium, strain A4a, isolated from Taylor Valley soil. Strain A4a was an obligately aerobic, orange-pigmented, Gram-positive coccus that grew over wide ranges of both temperature (0 degrees C-40 degrees C) and sodium chloride concentration (0-2.0M). The optimal temperature for growth at all NaCl concentrations was 25 degrees C. Phospholipid composition and guanine plus cytosine content of the DNA of the isolate indicate a close relation to the genus Planococcus.

SMS 201-995: a very potent and selective octapeptide analogue of somatostatin with prolonged action.

Stepwise modification of a conformationally stabilised analogue of the fragment of somatostatin which had been thought to be essential biologically active moiety has enabled us to synthesise the analogue H-(D) Phe-Cys-Phe-(D) Trp-Lys-Thr-Cys-Thr(ol) code-named SMS 201-995, which in vitro is three times more potent than the native hormone in inhibiting the secretion of growth hormone, which is highly resistant to degradation by pure enzymes and by tissue homogenates, which in vivo in rat and rhesus monkey is (depending on test system) at least 20 times more active than somatostatin, which is much longer acting, and which moreover in both species is much more selective in inhibiting the secretion of growth hormone than that of insulin. The compound is active by several routes of administration including the oral, is well tolerated both in laboratory animals and in man, and is currently undergoing preliminary clinical trial.

[Non-occupational accidents in Switzerland]. / Nichbetriebsunfälle in der Schweiz.

Of the over 3000 people killed in Switzerland through accidents, some 1300 die on the roads, 600 to 700 lose their lives as a result of accidents in the home, and a further number are killed in sporting accidents. these nonindustrial accidents are described in terms of their epidemiology and causes. In addition measures are discussed for preventing accidents in these three areas. At the center of the problems of traffic accidents are those caused by alcohol, the readiness of young people to take risks, and the orientation problems of children and the elderly. In sport, skiing accidents are very common, also falls in the home.

Resistance of FK 33-824 and other enkephalin analogues to peptidase degradation.

The stability of analogues of Met-enkephalin containing different chemical substitutions in the amino acid sequence to enzymatic degradation by a mouse brain extract and by rat striatal membranes have been compared. On incubation with the mouse brain extract, the naturally occurring Met-enkephalin was completely destroyed within 5 min and 50% of (D-Ala2)Met-enkephalinamide was degraded within 2 1/2 hr, with the release of Tyr, Phe, Met, D-Ala-Gly and partially (D-)Ala and Gly. (D-Ala2, MePhe4, Met(O)ol5) enkephalin (FK 33-824) was degraded to 50% within 5 hr, giving merely Tyr and the tetrapeptide D-Ala-Gly-MePhe-Met(O)ol as degradation products. No metabolism was observed after incubation for 24 hr of (MeTyr1, D-Ala2, MePhe4, Met(O)ol5) enkephalin (FW 34-569) with the mouse brain extract. On incubation with rat striatal membranes in the presence of puromycin, Met-enkephalin was rapidly inactivated, principally by cleavage of the Gly3-Phe4 bond, whereas FK 33-824 was not split.

Frost-weathering on Mars: experimental evidence for peroxide formation.

A laboratory study of the interaction of H2O frost with samples of the minerals olivine (Mg,Fe)2SiO4 and pyroxene (Mg,Fe)SiO3 at -11 degrees C to -22 degrees C revealed that an acidic oxidant was produced. Exposure of the frost-treated minerals to liquie H2O produced a sudden drop in pH and resulted in the production of copious O2(g) (as much as approximately 10(20) molecules g-1). Exposure of frost-treated samples to 5 ml of 0.1M HCOONa solution resulted in the rapid oxidation of up to 43% of the formate to CO2(g). These reactions were qualitatively similar to the chemical activity observed during the active cycles of the Viking lander Gas Exchange and Labeled Release Biology experiments. Attempts to identify the oxidant by chemical indicators were inconclusive, but they tentatively suggested that chemisorbed hydrogen peroxide may have formed. The formation of chemisorbed peroxide could be explained as a byproduct of the chemical reduction of the mineral. The following model was proposed. H+ was incorporated into the mineral from surface frost. This would have left behind a residual of excess OH-(ads) (relative to surface H+). Electrons were then stripped from the surface OH-(ads) (due to the large repulsive potential between neighboring OH-(ads)) and incorporated into the crystal to restore charge balance and produce a chemical reduction of the mineral. The resultant surface hydroxyl radicals could then have combined to form the more stable chemisorbed hydrogen peroxide species. While the chemisorbed peroxide should be relatively stable at low temperatures, it should tend to decay to O(ads)+ H2O(g) at higher temperatures with an activation energy of greater than or approximately 34 kcal mole-1. This is consistent with the long-term storage and sterilization behavior of the Viking soil oxidants. It is possible that as little as 0.1--1% frost-weathered material in the martian soil could have produced the unusual chemical activity that occurred during the Viking Gas Exchange and Labeled Release experiments.

Surface oxidation: a major sink for water on Mars.

Surface oxidation irreversibly removes both oxygen and hydrogen from the martian atmosphere at a rate of 10(8) to 10(11) per square centimeter per second. This rate corresponds to a net loss of 10(25) to 10(28) per square centimeter (10(2) to 10(5) grams per square centimeter) of H(2)O, if it is assumed that the loss rate is uniform over geologic time. Heretofore, exospheric escape was considered to be the principal irreversible sink for H(2)O, but the loss rate was estimated to be only 10(8) per square centimeter per second. It is possible that surface oxidation may have had a minor effect on the supply of H(2)O in the regolith and polar caps.