Electron solvation in finite systems: femtosecond dynamics of iodide. (Water)n anion clusters

Electron solvation dynamics in photoexcited anion clusters of I-(D2O)n=4-6 and I-(H2O)4-6 were probed by using femtosecond photoelectron spectroscopy (FPES). An ultrafast pump pulse excited the anion to the cluster analog of the charge-transfer-to-solvent state seen for I- in aqueous solution. Evolution of this state was monitored by time-resolved photoelectron spectroscopy using an ultrafast probe pulse. The excited n = 4 clusters showed simple population decay, but in the n = 5 and 6 clusters the solvent molecules rearranged to stabilize and localize the excess electron, showing characteristics associated with electron solvation dynamics in bulk water. Comparison of the FPES of I-(D2O)n with I-(H2O)n indicates more rapid solvation in the H2O clusters.     

Renin-angiotensin role in thirst: paradoxical enhancement of drinking by angiotensin converting enzyme inhibitor

A competitive angiotensin converting enzyme antagonist SQ 20, 881 (SQ), was used to examine the role of the renin-angiotensin system in putative renin-dependent thirst in the albino rat. Significant enhancement of "renin-dependent" as well as renin-independent drinking was observed in the presence of peripheral SQ. Intraventricular SQ obviated this enhancement of drinking but did not affect the water intake caused by the original stimulus itself, whereas it sharply reduced drinking evoked by peripheral renin in nephrectomized rats. Prior renin depletion likewise had no influence on so-called renin-dependent thirst.     

Pathogenicity and immunogenicity of piliated and nonpiliated phases of Moraxella bovis in calves

Pathogenicity evaluations of Moraxella bovis strain EPP 63 grown in the piliated and nonpiliated phase indicated that the organism grown in the piliated phase induced clinical keratoconjunctivitis, whereas the organism grown in the nonpiliated phase did not induce disease under identical challenge conditions. Calves inoculated with culture grown in the piliated phase developed significantly (P less than 0.01) higher lesion scores than did calves inoculated with culture grown in the nonpiliated phase. Vaccination/challenge exposure evaluations indicated that calves immunized with vaccine prepared from piliated culture had significantly lower lesion scores than did control calves (P less than 0.001) or calves immunized with vaccine prepared from nonpiliated culture (P less than 0.05). Similarly, calves immunized with piliated vaccine developed a significantly higher antibody titer against purified pili. Nonvaccinated controls and calves immunized with nonpiliated vaccine did not develop a significant increase in antibody titer. The results indicate that M bovis pili constitute an important factor in the pathogenicity of keratoconjunctivitis and may be used as a vaccine in the control of keratoconjunctivitis in cattle.     

Comparison of the mucosal immune response in dogs vaccinated with either an intranasal avirulent live culture or a subcutaneous antigen extract vaccine of Bordetella bronchiseptica

Healthy dogs with low antibody titer to Bordetella bronchiseptica were vaccinated intranasally with an avirulent live vaccine, subcutaneously with an antigen extract vaccine, or subcutaneously and intranasally with a placebo. Intranasally vaccinated dogs developed B. bronchiseptica-specific IgA titers in nasal secretions that remained at high levels until the end of the study; dogs vaccinated subcutaneously with the antigen extract or placebo did not develop measurable antigen-specific IgA titers in nasal secretions. Dogs were challenged with virulent live B. bronchiseptica 63 days after vaccination. Intranasally vaccinated dogs had significantly lower cough scores (P < or =.0058) and shed significantly fewer challenge organisms (P <.0001) than dogs in either of the other groups. Cough scores of subcutaneously vaccinated dogs were not significantly different from placebo-vaccinated dogs.     

Serologic and protective characterization of Moraxella bovis pili

This study was conducted to determine the protective nature of purified M. bovis EPP 63 pili in controlling experimentally induced Infectious Bovine Keratoconjunctivitis, and to determine antigenic similarity of pili isolated from various M. bovis isolates. Ten calves were vaccinated twice, 28 days apart, with 5.0 mg (protein) EPP 63 purified pili. Ten calves were maintained as non-vaccinated controls. All calves were exposed to ultraviolet light prior to challenge. The calves were challenged by instilling approximately 2.0 X 10(8) CFU of EPP 63 piliated organisms into the conjunctival sac. Antisera to respective pili types were prepared by immunizing the rabbits with purified pili from M. bovis strains EPP 63, FLA 64, IBH 68, MED 72 and ATCC 10900. Rabbit serum was evaluated for cross reactivity by enzyme-linked immunosorbent assay (ELISA). Purity of pili preparations was demonstrated on SDS-PAGE gels. Molecular weight of pili subunit was determined to be approximately 20,000 for EPP 63, 19,500 for IBH 68 and ATCC 10900, and 17,500 for FLA 64 and MED 72. One of 10 (10%) calves vaccinated with EPP 63 purified pili, and 6 of 10 (60%) nonvaccinated controls developed IBK, respectively. Average eye scores for vaccinates and controls were 0.05 and 0.85, respectively. Significant cross-reaction was found between EPP 63 and MED 72 pili. FLA 64 and ATCC 10900 were similar; however, antiserum to IBH 68 pili showed some degree of cross reaction with other pili.     

Sigmoid models for the uptake,concentration and effects of metals in consumer organisms

The uptake, concentration and effects of metals contamination in consumer organisms have been successfully described with the flexibly-shaped Richards sigmoid model. This model allows the simultaneous estimation of: (1) final asymptotic level of contaminant uptake or body growth, (2) the time required to approach asymptote, and (3) the particular path or trajectory taken by the function in approaching asymptote within the designated time. Analyses using the Richards model have shown that data for a variety of contaminants fail to conform to the shape of the classic monomolecular model and rather show an initial lag in the early uptake rate. In effects studies, the use of the Richards model to analyze body growth data from waterfowl exposed to dietary intake of Cd and other contaminants has shown that growth curve shape is more likely to change in response to contaminant intake than are either final asymptotic levels or the times required for asymptotes to be attained. Failure to consider such changes in growth curve shape could cause significant errors in the identification of growth responses to contaminant intake stress.

     

Biosorption of lead and chromium by penicillium preparations

Penicillium sp. mycelium can accumulate Pb from aqueous solutions of nitrate. Uptake of Pb by mycelial preparations after heat treatment was more rapid, but the maximum quantity bound remained unchanged. Chromium was not accumulated from solutions of potassium dichromate unless the mycelial preparation was first incubated in Pb nitrate. In the example given, 0.14 g of dry mycelium incubated in Pb nitrate (50 ppm, 2 hr) contained 850 gg of Pb and subsequently accumulated 120 μg of Cr in 5 min from 20 mL of 20 ppm dichromate solution. We suggest that the binding of divalent Pb cations to negative fungal wall sites reverses their charge, enabling them to accumulate Cr anions.     

Gas conductance during high-frequency oscillatory ventilation in large animals

Three sheep, a foal, a pony, and a calf were anesthetized and ventilated for short periods, using a high-frequency oscillatory ventilator. The efficiency of CO2 elimination was characterized at various oscillatory frequencies (50 to 30 Hz) and various tidal volumes, although the tidal volume used was always less than the measured dead space of the animal. In general, increasing either the oscillatory frequency or tidal volume increased CO2 elimination, but increasing the tidal volume had more effect. The relationship between these 3 variables was best described by a power law equation. Ventilatory frequencies and tidal volumes required to maintain eucapnia in the species studied were extrapolated from the results and, when technically possible, the potential of the technique to maintain eucapnia was tested in extended runs. The animals were supported successfully over this period, with normal blood gas tensions and no detrimental effects to heart rate and rhythm or arterial blood pressure.