Plasma potentiates the priming effects of endotoxin on platelet activating factor-induced pulmonary hypertension in the rabbit lung.

During Gram-negative sepsis, endotoxin lipopolysaccharide (LPS) may activate host inflammatory responses, resulting in the systemic inflammatory response syndrome and the adult respiratory distress syndrome. In cell culture systems, LPS activation of cellular responses may be potentiated by plasma proteins. In the isolated perfused rabbit lung, LPS administration markedly increases the pulmonary hypertensive response to subsequent administration of platelet activating factor (PAF). We examined whether plasma would potentiate the priming effects of LPS in this model. Male New Zealand White rabbits were used in a standard, isolated buffer-perfused rabbit lung preparation, and the pulmonary hypertensive response to 5 nM PAF was measured after 2 h of perfusion with different LPS doses (0, 1, and 10 ng/mL), with and without plasma (10% by volume). In the absence of plasma, 10 ng/mL LPS, but not 1 ng/mL LPS, increased the pulmonary hypertensive response to subsequent administration of 5 nM PAF. However, in the presence of plasma, 1 ng/mL LPS significantly increased the hypertensive response to subsequent administration of 5 nM PAF. We conclude that components of plasma--possibly LPS binding protein and soluble CD14--potentiate the priming effect of endotoxin, resulting in an augmented pulmonary hypertensive response to PAF. Thus, plasma proteins decrease the threshold at which endotoxin primes the lung and may have a critical role in the pathogenesis of endotoxin-induced acute lung injury.

A double-blind, placebo-controlled trial of thymostimulin in symptomatic HIV-infected patients.

The potential therapeutic efficacy of the thymic hormone preparation, thymostimulin (TP1), in HIV infection has been studied in a multi-institutional, randomized, double-blind, placebo-controlled trial. Fifty evaluable patients with advanced AIDS-related complex (ARC) were injected with TP1 or placebo twice weekly for 6 months after 2 weeks of daily injections. The primary endpoint, progression to AIDS, was reached in nine TP1- and 11 placebo-treated subjects after 1 year. CD4 cell numbers were not affected by administration of the study drug. No toxicity was associated with TP1 treatment. We conclude that TP1 is ineffective in altering the progress of HIV disease in patients with advanced ARC.

Some factors affecting the efficiency of settle plates.

An evaluation has been made of some of the factors which may affect the efficiency of settle plates. Water loss was found to be linear with time. Although the count was reduced over an 8 h period the reduction was not statistically significant. No difference in total bacterial counts could be detected between four, 1/2 h exposures and one, 2 h exposure. The addition of water and the surface area of the plates had no effect on the total count.

On methods of expressing dissolution rate data.

The value of the Weibull, logarithmic-logistic, and logarithmic-normal plots in expressing dissolution rate data is considered for the combinations of zero and first-order release with sink and non-sink conditions, and for actual dissolution rate data of diazepam from tablets in a medium of pH2.