Role of Differential Air Pressure Zones in the Control of Aerosols in a Large Animal Isolation Facility

The uncontrolled transmission of hog cholera in a large animal isolation facility, designed to control the movement of aerosols within and between individual wings of a multiunit building, indicated the need for a critical study of aerosol behavior under existing conditions of operation. Studies with aerosols of Escherichia coli B T3 bacteriophage (T3 coliphage) conclusively demonstrated the impossibility of obtaining the desired control by means of a "static" air balance relationship between adjacent areas within the facility. Modifications needed to provide the desired control of the air-handling system are outlined and discussed.     

Adventitious shoot regeneration from leaf tissue of three pear (Pyrus sp.) cultivars in vitro

To develop an adventitious regeneration system for pear cultivars, several experiments were conducted with 2 cultivars of Pyrus communis L. (Seckel and Louise Bonne) and one cultivar of P. bretschneideri Rehd. (Crystal Pear). Half-leaves, taken from shoots proliferating on Lepoivre medium, were plated in petri-dishes on medium supplemented with various combinations of cytokinins and auxins. Cultures of the above cultivars had been established from mature trees. Among the growth regulators tested, thidiazuron (TDZ), combined with naphthalene-acetic acid (NAA), was the most efficient for stimulation of adventitious shoots. The optimum level of TDZ was about 3 uM; shoot regeneration was observed over a wide range of TDZ and NAA concentrations (0.5 to 5 uM and 2.5 to 13 um, respectively). Among different macronutrient compositions, 1/2 and 1/4 Murashige and Skoog were the most effective. Sucrose concentrations (10 to 50 g L-1) had a linear significant effect on shoot regeneration of Crystal Pear.Abbreviations BAP 6-benzylaminopurine - IBA indole-3-butyric acid - NAA a-naphthaleneacetic acid - NoA 2-naphthoxyacetic acid - 2,4-D 2,4-dichlorophenoxyacetic acid - TDZ thidiazuron (N-phenyl-N'-1,2,3-thidiazol-5-ylurea) - MS Murashige and Skoog (1962) macroelements - L Lepoivre (Quoirin and Lepoivre, 1977) macroelements     

Temperature dependence of inorganic nitrogen uptake and assimilation in Antarctic sea-ice microalgae

Summary The influence of temperature on NO ₃ ^- and NH ₄ ⁺ uptake, and the activity of the assimilatory enzyme NO ₃ ^- reductase (NR) was compared to inorganic C uptake (photosynthesis) in natural assemblages of Antarctic sea-ice microalgae. NO ₃ ^- and NH ₄ ⁺ uptake reached a maximum between 0.5°–2.0°C and 2.0°–3.0°C, respectively, which was close to that for photosynthesis (2.5°–3.0°C). NR showed a distinctly higher temperature maximum (10.0°–12.0°C) and a lower Q₁₀ value than inorganic N and C transport. Our data imply that, owing to differential temperature characteristics between N transport and N assimilation at in situ temperature (-1.9°C), the incorporation of extracellular NO ₃ ^- into cellular macromolecules, may be limited by transport of NO ₃ ^- into the cell rather than the intracellular reduction of NO ₃ ^- to NH ₄ ⁺ . Despite differences in temperature maxima between N transport and N assimilation, the overall low temperature maxima of inorganic N metabolism characterizes Antarctic sea-ice microalgae as psychrophilic. Our study is the first to examine the temperature dependence of inorganic N uptake and assimilation in sea-ice microbial communities.     

Linkage analysis of seven kindreds with the X-linked lymphoproliferative syndrome (XLP) confirms that the XLP locus is near DXS42 and DXS37

Summary Analysis of seven kindreds indicates that the XLP locus exhibits 1% recombination with DXS42 (lod = 17.5) and no recombination with DXS37 (lod = 13.3).     

Antigenic specificity of antibody-dependent cell-mediated cytotoxicity directed against human immunodeficiency virus in antibody-positive sera.

Antibody-dependent cell-mediated cytotoxicity (ADCC) specific for human immunodeficiency virus (HIV) has been described for HIV-infected individuals. To determine the antigenic specificity of this immune response and to define its relationship to the disease state, an ADCC assay was developed using Epstein-Barr virus-transformed lymphoblastoid cell line targets infected with vaccinia virus vectors expressing HIV proteins. The vaccinia virus vectors induced appropriate HIV proteins (envelope glycoproteins gp160, gp120, and gp41 or gag proteins p55, p40, p24, and p17) in infected lymphoblastoid cell lines as demonstrated by radioimmunoprecipitation and syncytia formation with c8166 cells. Killer cell-mediated, HIV-specific ADCC was found in sera from HIV-seropositive but not HIV-seronegative hemophiliacs. This HIV-specific response was directed against envelope glycoprotein but was completely absent against target cells expressing the HIV gag proteins. The ADCC directed against gp160 was present at serum dilutions up to 1/316,000. There was no correlation between serum ADCC titer and the stage of HIV-related illness as determined by T-helper-cell numbers. These experiments clearly implicated gp160 as the target antigen of HIV-specific ADCC activity following natural infection. Vaccines which stimulate antibodies directed against gp160, which are capable of mediating ADCC against infected cells, could be important for protection against infection by cell-associated virus.     

Effect of sampling on variability and plateau in oxygen uptake

To evaluate the effect of the gas exchange sampling interval on variability and plateau in O2 uptake (VO2), 10 subjects underwent steady-state treadmill exercise at 50% maximal VO2 and 6 subjects underwent maximal testing using a ramp protocol. During steady-state exercise, gas exchange data were acquired by using 10 different sampling intervals. The variability in VO2 was greater as the sampling interval shortened (SD = 4.5 ml.kg-1.min-1 for breath-by-breath vs. 0.8 ml.kg-1.min-1 for 60-s samples). The breath-by-breath data suggested a Gaussian distribution, and most of the variability was attributable to tidal volume (51%). During ramp testing, the slope of the change in VO2 (for each sample) was regressed with time. Considerable variability in the slopes was observed throughout exercise, and in each subject the slopes varied about zero, demonstrating both positive and negative values throughout submaximal effort. These observations were made despite the use of large sampling intervals. Shortening the sample resulted in even greater variability. We conclude that 1) the sampling interval can have a major impact on gas exchange data during exercise and 2) considerable variability exists in the slope of the change in VO2 with a consistent change in external work regardless of the sample used, suggesting that a plateau (defined as the slope of a VO2 sample at peak exercise that does not differ significantly from a slope of zero) in VO2 is not a reliable physiological marker for maximal effort.