NMR study of 13CO2 incorporation into short-chain fatty acids by pig large-intestinal flora

The nuclear magnetic resonance technique was used to study carbon dioxide reduction by the pig large-intestinal flora. Washed bacterial cell suspensions were incubated for 6 and 15 h under 13CO2 and H2 as the gas phase and with a buffer containing NaH13CO3 and cellobiose and amino acids (casein hydrolysate) as substrates. Methane was produced in all incubation media. Significant amounts of single- as well as multiple-labelled acetate and butyrate were formed, demonstrating synthesis of acetate from H2 + CO2. Propionate was labelled mainly on the carboxyl group, which was attributed to an enzymatic exchange of the carboxyl group of propionate with 13CO2. These results indicate that the reduction of CO2 to acetate may be an important pathway for microbial production of acetate in the pig large intestine even in the presence of methanogenesis.     

Randomised controlled trial of enalapril and beta blockers in non-diabetic chronic renal failure.

OBJECTIVE--To compare the ability of angiotensin converting enzyme inhibitors and beta blockers to slow the development of end stage renal failure in non-diabetic patients with chronic renal failure. DESIGN--Open randomised multicentre trial with three year follow up. SETTING--Outpatient departments of six French hospitals. PATIENTS--100 hypertensive patients with chronic renal failure (initial serum creatinine 200-400 mumol/l. 52 randomised to enalapril and 48 to beta blockers (conventional treatment). INTERVENTIONS--Enalapril or beta blocker was combined with frusemide and, if necessary, a calcium blocker or centrally acting drug in patients whose diastolic pressure remained above 90 mm Hg. RESULTS--17 patients receiving conventional treatment and 10 receiving enalapril developed end stage renal failure. The cumulative renal survival rate was significantly better in the enalapril group than in the conventional group (P < 0.05). The slope of the reciprocal serum creatinine concentration was steeper in the conventionally treated patients (-6.89 x 10(-5)l/mumol/month) than in the enalapril group (-4.17 x 10(-5)l/mumol/month; P < 0.05). No difference in blood pressure was found between groups. CONCLUSION--In hypertensive patients with chronic renal failure enalapril slows progression towards end stage renal failure compared with beta blockers. This effect was probably not mediated through controlling blood pressure.     

Molecular Reclassification of Crohn’s Disease: A Cautionary Note on Population Stratification

Complex human diseases commonly differ in their phenotypic characteristics, e.g., Crohn’s disease (CD) patients are heterogeneous with regard to disease location and disease extent. The genetic susceptibility to Crohn’s disease is widely acknowledged and has been demonstrated by identification of over 100 CD associated genetic loci. However, relating CD subphenotypes to disease susceptible loci has proven to be a difficult task. In this paper we discuss the use of cluster analysis on genetic markers to identify genetic-based subgroups while taking into account possible confounding by population stratification. We show that it is highly relevant to consider the confounding nature of population stratification in order to avoid that detected clusters are strongly related to population groups instead of disease-specific groups. Therefore, we explain the use of principal components to correct for population stratification while clustering affected individuals into genetic-based subgroups. The principal components are obtained using 30 ancestry informative markers (AIM), and the first two PCs are determined to discriminate between continental origins of the affected individuals. Genotypes on 51 CD associated single nucleotide polymorphisms (SNPs) are used to perform latent class analysis, hierarchical and Partitioning Around Medoids (PAM) cluster analysis within a sample of affected individuals with and without the use of principal components to adjust for population stratification. It is seen that without correction for population stratification clusters seem to be influenced by population stratification while with correction clusters are unrelated to continental origin of individuals.     

Sex-biased dispersal promotes adaptive parental effects

Background  

In heterogeneous environments, sex-biased dispersal could lead to environmental adaptive parental effects, with offspring selected to perform in the same way as the parent dispersing least, because this parent is more likely to be locally adapted. We investigate this hypothesis by simulating varying levels of sex-biased dispersal in a patchy environment. The relative advantage of a strategy involving pure maternal (or paternal) inheritance is then compared with a strategy involving classical biparental inheritance in plants and in animals.     

Comparative diffusion of 14C-ethionine and 14C-methionine in rat tissue]

The pancreas is the tissue which traps the most intensively the trace-dosis injected ethionine -14C; 30 min after the injection, the pancreas fixes the labelled product twice more than the liver and five times more than the stomach. This trapping might explain the pancreatic modifications occuring during the intoxication. In the same experimental conditions, the pancreas fixes the ethionine -14C twice less than methionine. Urinary excretion of ethionine is faster and more important than that of methionine.