Hyperbaric effects on cold stored whole blood following a military dive mission profile.

BACKGROUND: Whole blood (WB) is carried by special operations forces as part of a remote damage control resuscitation strategy. The effects of an underwater mission on the quality and coagulation profile of WB were simulated by exposure to hyperbaric pressures in a chamber. METHODS: WB units collected in CPDA-1 were exposed to three different combinations of hyperbaric pressure and duration of exposure: Group A 153.52 kPa (15.24 msw; 1.52 atm) for 4 h; n = 9, Group B 506.63 kPa (50.29 msw; 5.00 atm) for 1 h; n = 9, Group C 153.52 kPa (15.24 msw; 1.52 atm) for 1 h; n = 7. The following parameters were measured on each unit: prothrombin time/international normalized ratio, activated partial thromboplastin time, thromboelastography and concentration determinations of platelets, lactate, fibrinogen, and lactate dehydrogenase. Each sample underwent baseline, prepressurization, immediate postpressurization, and 6 h postpressurization laboratory testing. RESULTS: Six hours following hyperbaric exposure, the lactate concentration in group C was higher than prepressurization measurement and the platelet concentration in Group A was lower than prepressurization measurement. There were no changes in any of the other analyzed biochemical, coagulation and thromboelastogram parameters following exposure to hyperbaric stress. DISCUSSION: These data suggest that pressurization of WB up to 5 atm did not impact parameters tested. Changes observed in lactate and platelet count need further study, as well as complementary testing of red blood cell integrity. Further investigation of the hyperbaric extremes is necessary to determine if there is a damage inducing pressure to which WB should not be exposed.

Low concentrations of contaminants in an invasive cyprinid, the rudd, in a Great Lakes Area of Concern.

The invasive, omnivorous rudd Scardinius erythrophthalmus is abundant in the upper Niagara River, a Great Lakes Area of Concern. Invasive species can alter trophic and contaminant pathways, but complex ontogenetic and seasonal diet shifts by rudds make it difficult to predict their chemical burdens relative to other fishes. We quantified concentrations of chemical residues in rudds and compared them to six fish species from various trophic levels. Rudds contained low concentrations of total dichlorodiphenyltrichloroethane (mean = 0.02 µg/g), Hg (mean = 0.03 µg/g), and polychlorinated biphenyls (mean = 0.06 µg/g); these concentrations were among the lowest for all species examined. Concentrations of aldrin, heptachlor, hexachlorobenzene, total hexachlorocyclohexanes, mirex, and total chlordanes were less than the method detection limit for all rudds examined. If reducing rudd biomass is determined to be beneficial, resource managers could consider targeted harvest, given the low concentrations of contaminant in rudds and their susceptibility to capture.

Chiral interactions of histidine in a hydrated vermiculite clay.

Recent work shows a correlation between chiral asymmetry in non-terrestrial amino acids extracted from the Murchison meteorite and the presence of hydrous mineral phases in the meteorite [D. P. Glavin and J. P. Dworkin, Proc. Natl. Acad. Sci. U. S. A., 2009, 106, 5487-5492]. This highlights the need for sensitive experimental tests of the interactions of amino acids with clay minerals together with high level computational work. We present here the results of in situ neutron scattering experiments designed to follow amino acid adsorption on an exchanged, 1-dimensionally ordered n-propyl ammonium vermiculite clay. The vermiculite gel has a (001) d-spacing of order 5 nm at the temperature and concentration of the experiments and the d-spacing responds sensitively to changes in concentration, temperature and electronic environment. The data show that isothermal addition of D-histidine or L-histidine solutions of the same concentration leads to an anti-osmotic swelling, and shifts in the d-spacing that are different for each enantiomer. This chiral specificity, measured in situ, in real time in the neutron beam, is of interest for the question of whether clays could have played an important role in the origin of biohomochirality.

Structure of pi-pi interactions in aromatic liquids.

High-resolution neutron diffraction has been used in conjunction with hydrogen/deuterium isotopic labeling to determine with unprecedented detail the structure of two archetypal aromatic liquids: benzene and toluene. We discover the nature of aromatic pi-pi interactions in the liquid state by constructing for the first time a full six-dimensional spatial and orientational picture of these systems. We find that in each case the nearest neighbor coordination shell contains approximately 12 molecules. Benzene is the more structured of the two liquids, showing, for example, a sharper nearest neighbor coordination peak in the radial distribution function. Superficially the first neighbor shells appear isotropic, but our multidimensional analysis shows that the local orientational order in these liquids is much more complex. At small molecular separations (<5 A) there is a preference for parallel pi-pi contacts in which the molecules are offset to mimic the interlayer structure of graphite. At larger separations (>5 A) the neighboring aromatic rings are predominantly perpendicular, with two H atoms per molecule directed toward the acceptor's pi orbitals. The so-called "anti-hydrogen-bond" configuration, proposed as the global minimum for the benzene dimer, occurs only as a saddle point in our data. The observed liquid structures are therefore fundamentally different than those deduced from the molecular dimer energy surfaces.