A 28-day oral (dietary) toxicity study of sucromalt in Sprague--Dawley rats.

A new sweetener, sucromalt, was produced via enzymatic conversion of sucrose and maltose to a mixture of fructose, leucrose and gluco-oligosaccharides. The present study evaluated the safety of this sweetener when administered as a dietary admix at concentrations of 50, 100 and 200 g/kg to Sprague-Dawley rats for 28 days. There were no treatment-related effects on the general condition and behavior as determined by clinical observations, functional observational battery and locomotor activity assessments. Evaluation of clinical pathology parameters revealed no toxicologically-relevant treatment-related effects on hematology, serum chemistry or urinalysis. Macroscopic and microscopic findings revealed no treatment-related effects on any organ evaluated. A treatment-related increase in mean food consumption was observed resulting in slightly higher body weight gains (2-4%) for both the male and female rats, which was not toxicologically relevant. Results of this study clearly demonstrate that consumption of high concentrations of sucromalt for 28 days is not associated with obvious signs of toxicity.

Evidence for the requirement of T cell costimulation in the pathogenesis of natural Pneumocystis carinii pulmonary infection.

Pneumocystis carinii pneumonia (PCP) is a frequent and serious opportunistic infection in immunocompromized patients. Although the pathogenesis of PCP-mediated lung injury is poorly understood, a central involvement of host inflammatory responses has been implicated. We have found that while the loss of specific T cell costimulatory signals increases susceptibility to the spontaneous pneumocystis infection, PCP-induced pulmonary injury (and subsequent morbidity and mortality) involves other intact costimulatory pathways. Mice that are genetically deficient for the costimulatory receptor CD154 (CD154 knockout (ko) mice) spontaneously developed PCP, consistent with the increased susceptibility of X-linked hyper IgM syndrome patients (caused by CD154 gene mutations) to P. carinii infection. In these mice PCP was manifested by progressive weight loss, dyspnea and death. In contrast, CD154 ko mice also genetically lacking ICAM1 (CD154 koxICAM1 ko) or CD28 (CD154 koxCD28 ko) costimulatory receptors had later onset of weight loss and significantly prolonged survival. Although onset of infection and age-matched P. carinii organism burden were equivalent, the CD154 single knockout mice had evidence of greater pulmonary inflammation vs. the double ko's. These findings suggest that costimulation-dependent T cell-mediated inflammation plays an important role in both susceptibility to and pathogenesis of PCP, and may identify potential molecular targets for novel immunomodulatory treatment approaches.