The Role of Nutrients and Nutritional Signals in the Pathogenesis of Vibrio cholerae.

Vibrio cholerae, the agent of cholera, is a natural inhabitant of aquatic environments. Over the past decades, the importance of specific nutrients and micronutrients in the environmental survival, host colonization, and pathogenesis of this species has become increasingly clear. For instance, V. cholerae has evolved ingenious mechanisms that allow the bacterium to colonize and establish a niche in the intestine of human hosts, where it competes with commensals (gut microbiota) and other pathogenic bacteria for available nutrients. Here, we discuss the carbon and energy sources utilized by V. cholerae and what is known about the role of nutrition in V. cholerae colonization. We examine how nutritional signals affect virulence gene regulation and how interactions with intestinal commensal species can affect intestinal colonization.

The pattern of intestinal substrate oxidation is altered by protein restriction in pigs.

BACKGROUND & AIMS: Previous studies indicate that amino acids and glucose are the major oxidative substrates for intestinal energy generation. We hypothesized that low protein feeding would lower the contribution of amino acids to energy metabolism, thereby increasing the contribution of glucose. METHODS: Piglets, implanted with portal, arterial, and duodenal catheters and a portal flow probe, were fed isocaloric diets of either a high protein (0.9 g/[kg/h] protein, 1.8 g/[kg/h] carbohydrate, and 0.4 g/[kg/h] lipid) or a low protein (0.4 g/[kg/h] protein, 2.2 g/[kg/h] carbohydrate, and 0.5 g/[kg/h] lipid) content. They received enteral or intravenous infusions of [1-13C]leucine (n = 17), [U-13C]glucose (n = 15), or enteral [U-13C]glutamate (n = 8). RESULTS: CO2 production by the splanchnic bed was not affected by the diet. The oxidation of leucine, glutamate, and glucose accounted for 82% of the total CO2 production in high protein-fed pigs. Visceral amino acid oxidation was substantially suppressed during a low protein intake. Although glucose oxidation increased to 50% of the total visceral CO2 production during a low protein diet, this increase did not compensate entirely for the fall in amino acid oxidation. CONCLUSIONS: Although low protein feeding increases the contribution of enteral glucose oxidation to total CO2 production, this adaptation is insufficient. To compensate for the fall in amino acid oxidation, other substrates become increasingly important to intestinal energy generation.

Nonresponding schizophrenia: differentiation by neurological soft signs and neuropsychological tests.

Schizophrenia patients have higher scores on neurological soft-signs (NSS) and show greater deficits on a variety of neuropsychological tests than normal control subjects and mixed groups of psychiatric patients. Among chronic schizophrenia patients it is unclear which of these types of deficits most strongly differentiates patients who remain consistently symptomatic in spite of treatment with several conventional neuroleptics (nonresponders) as compared with relapsing chronic schizophrenia patients who improve substantially with treatment (relative responders). In this study, 25 nonresponders and 20 relative responders to conventional neuroleptics were compared on an NSS battery and a limited number of neuropsychological tests, which evaluated deficits influenced by functioning of frontal and nonfrontal brain areas. NSS scores showed the largest difference between relative responders and nonresponders, and statistical analyses suggested that NSS scores were the strongest differentiator between the two groups of chronic schizophrenia patients. Scores differentiating the two groups involved deficits influenced by both frontal and nonfrontal functioning. A predominance of negative symptoms in the current clinical picture was highly correlated with high NSS scores.