Growth of Photorhabdus luminescens in batch and glucose fed-batch culture.

Photorhabdus luminescens, a bacterial symbiont of entomopathogenic biocontrol nematodes, was grown in batch and glucose fed-batch culture. The cell density, bioluminescence, production of antibiotic substances, number of cells with inclusion bodies, glucose concentration and oxygen uptake rate were recorded. The addition of 12.4 g 1(-1) glucose prolonged the growth, and the yield almost doubled, from 6.85 g 1(-1) to 12.45 g 1(-1) dry mass. The production of antibiotic substances increased by 140%. Bioluminescence was higher in the batch culture. A shift of P. luminescens to phase II variants was not detected.

Levodopa-carbidopa and childhood retinal disease.

PURPOSE: Our purpose was to determine the influence of levodopa-carbidopa on visual function in children with retinal disease. METHOD: Two studies were undertaken, a single-dose study and a longitudinal dosing study. A double-masked, placebo controlled single-dose study was undertaken of levodopa-carbidopa (2.08 mg/kg of body weight levodopa with 25% carbidopa) on monocular visual acuity in 14 children with retinal disease. Subjects received two capsules approximately 2.5 hours apart, and monocular visual acuity was measured 2 hours after each capsule ingestion. The second study was a double-masked, placebo-controlled 12-week longitudinal dosing (0.62 mg/kg of body weight) crossover study in which subjects received levodopa-carbidopa for 6 weeks and placebo for 6 weeks. RESULTS: The single-dose study revealed a small but statistically significant improvement in monocular visual acuity after levodopa-carbidopa ingestion. The longitudinal study revealed a small but statistically significant improvement in binocular visual acuity after levodopa ingestion. In both studies placebo had no significant effect on visual acuity. Six subjects participated in both studies and demonstrated a significant correlation (r = 0.76, p < 0.05) between change in visual acuity in the single-dose study and the longitudinal dosing study. CONCLUSION: The results are consistent with the hypothesis that dopamine influences the receptive field characteristics of retinal cells. The results also suggest that there may be low retinal dopamine levels in some types of retinal disease, which may be amenable to treatment.