A low-temperature insulating phase at v=1.5 for 2D holes in high-mobility SiSi1-xGex heterostructures with Landau level degeneracy

Magneto-transport measurements of the 2D hole system (2DHS) in p-type Si-Si1-xGex heterostructures identify the integer quantum Hall effect (IQHE) at dominantly odd-integer filling factors v and two low-temperature insulating phases (IPs) at v = 1.5 and v less than or similar to 0.5, with re-entrance to the quantum Hall effect at v = 1. The temperature dependence, current-voltage characteristics, and tilted field and illumination responses of the IP at v = 1.5 indicate that the important physics is associated with an energy degeneracy of adjacent Landau levels of opposite spin, which provides a basis for consideration of an intrinsic, many-body origin.

Modeling of subcutaneous absorption kinetics of infusion solutions in the elderly using technetium

Absorption kinetics of solutes given with the subcutaneous administration of fluids is ill-defined. The gamma emitter, technitium pertechnetate, enabled estimates of absorption rate to be estimated independently using two approaches. In the first approach, the counts remaining at the site were estimated by imaging above the subcutaneous administration site, whereas in the second approach, the plasma technetium concentration-time profiles were monitored up to 8 hr after technetium administration. Boluses of technetium pertechnetate were given both intravenously and subcutaneously on separate occasions with a multiple dosing regimen using three doses on each occasion. The disposition of technetium after iv administration was best described by biexponential kinetics with a V-ss of 0.30 +/- 0.11 L/kg and a clearance of 30.0 +/- 13.1 ml/min. The subcutaneous absorption kinetics was best described as a single exponential process with a half-life of 18.16 +/- 3.97 min by image analysis and a half-life of 11.58 +/- 2.48 min using plasma technetium time data. The bioavailability of technetium by the subcutaneous route was estimated to be 0.96 +/- 0.12. The absorption half-life showed no consistent change with the duration of the subcutaneous infusion. The amount remaining at the absorption site with time was similar when analyzed using image analysis, and plasma concentrations assuming multiexponential disposition kinetics and a first-order absorption process. Profiles of fraction remaining at the absorption sire generated by deconvolution analysis, image analysis, and assumption of a constant first-order absorption process were similar. Slowing of absorption from the subcutaneous administration site is apparent after the last bolus dose in three of the subjects and can De associated with the stopping of the infusion. In a fourth subject, the retention of technetium at the subcutaneous site is more consistent with accumulation of technetium near the absorption site as a result of systemic recirculation.

In vivo effects of chicken interferon-gamma during infection with Eimeria

Newly hatched chickens are highly susceptible to infection by opportunistic pathogens during the first 1 or 2 weeks of life, The use of cytokines as therapeutic agents has been studied in animal models as well as in immunosuppressed patients, This approach has become more feasible in livestock animals, in particular poultry, with the recent cloning of cytokine genes and the development of new technologies, such as live delivery vectors, We have recently cloned the gene for chicken interferon-gamma (Ch-IFN-gamma), Poly-HIS-tagged recombinant Ch-IFN-gamma was expressed in Escherichia coil, was purified by Ni chromatography, and was found to be stable at 4 degrees C and an ambient temperature for at least several months and Several weeks, respectively, Ch-IFN-gamma was capable of protecting chick fibroblasts from undergoing virus-mediated lysis, induced nitrite secretion from chicken macrophages in vitro, and enhanced MHC class II expression on macrophages, Administration of recombinant Ch-IFN-gamma to chickens resulted in enhanced weight gain over a 12-day period, Furthermore, the therapeutic potential of Ch-IFN-gamma was assessed using a coccidial challenge model, Birds were treated with Ch-IFN-gamma or a diluent control and then infected with Eimeria acervulina. Infected birds treated with Ch-IFN-gamma showed improved weight gain relative to noninfected birds, The ability of Ch-IFN-gamma to enhance weight gain in the face of coccidial infection makes it an excellent candidate as a therapeutic agent.