Effect of citrulline on muscle functions during moderate dietary restriction in healthy adult rats.

Low calorie diets are designed to reduce body weight and fat mass, but they also lead to a detrimental loss of lean body mass, which is an important problem for overweight people trying to lose weight. In this context, a specific dietary intervention that preserves muscle mass in people following a slimming regime would be of great benefit. Leucine (LEU) and Citrulline (CIT) are known to stimulate muscle protein synthesis (MPS) in post-prandial and post-absorptive state, respectively. This makes them interesting bioactive components to test in the context of dietary restriction. We tested the concept of combining LEU and CIT in adult female rats. We postulated that the sequential administration of LEU (mixed in chow) and CIT (given in drinking water before a rest period) could be beneficial for preservation of muscle function during food restriction. Sixty female rats (22 weeks old) were randomized into six groups: one group fed ad libitum with a standard diet (C) and five food-restricted groups (60 % of spontaneous intake for 2 weeks) receiving a standard diet (R group), a CIT-supplemented diet (0.2 or 1 g/kg/day, CIT0.2 group and CIT1 group, respectively), a LEU-supplemented diet (1.0 g/kg/day) or a CIT + LEU-supplemented diet (CIT + LEU 1.0 g/kg/day each). At the end of the experiment, body composition, muscle contractile properties and muscle protein synthesis (MPS) rate were studied in the tibialis anterior muscle. Dietary restriction tended to decrease MPS (R: 2.5 ± 0.2 vs. C: 3.4 ± 0.4 %/day, p = 0.06) and decrease muscle strength (R: 3,045 ± 663 vs. C: 5,650 ± 661 A.U., p = 0.03). Only CIT administration (1 g/kg) was able to restore MPS (CIT1: 3.4 ± 0.3 vs. R: 2.5 ± 0.2 %/day, p = 0.05) and increase muscle maximum tetanic force (CIT1: 441 ± 15 vs. R: 392 ± 22 g, p = 0.05) and muscle strength (CIT1: 4,259 ± 478 vs. R: 3,045 ± 663 A.U., p = 0.05). LEU had no effect and CIT + LEU supplementation had few effects, limited to adipose mass and fatigue force. The results of this study highlight the ability of CIT alone to preserve muscle function during dietary restriction. Surprisingly, LEU antagonized some effects of CIT. The mechanisms involved in this antagonistic effect warrant further study.

HLA-B27 rats develop osteopaenia through increased bone resorption without any change in bone formation.

Osteopaenia is a common complication of inflammatory bowel diseases (IBD). However, the mechanisms of bone loss are still the subject of debate. The aims of this study were to investigate bone loss in HLA-B27 transgenic rats, a spontaneous model of colitis and to compare the results provided by the usual markers of bone remodelling and by direct measurement of bone protein synthesis. Systemic inflammation was evaluated in HLA-B27 rats and control rats from 18 to 27 months of age. Then bone mineral density, femoral failure load, biochemical markers of bone remodelling and protein synthesis in tibial epiphysis were measured. Bone mineral density was lower in HLA-B27 rats than in controls. Plasma osteocalcin, a marker of bone formation, and fractional protein synthesis rate in tibial epiphysis did not differ between the two groups of rats. In contrast, urinary excretion of deoxypyridinoline, a marker of bone resorption, was significantly increased in HLA-B27 rats. The present results indicate that bone fragility occurs in HLA-B27 rats and mainly results from an increase in bone resorption. Systemic inflammation may be the major cause of the disruption in bone remodelling homeostasis observed in this experimental model of human IBD.

Common degradative pathways of morpholine, thiomorpholine, and piperidine by Mycobacterium aurum MO1: evidence from (1)H-nuclear magnetic resonance and ionspray mass spectrometry performed directly on the incubation medium.

In order to see if the biodegradative pathways for morpholine and thiomorpholine during degradation by Mycobacterium aurum MO1 could be generalized to other heterocyclic compounds, the degradation of piperidine by this strain was investigated by performing (1)H-nuclear magnetic resonance directly with the incubation medium. Ionspray mass spectrometry, performed without purification of the samples, was also used to confirm the structure of some metabolites during morpholine and thiomorpholine degradation. The results obtained with these two techniques suggested a general pathway for degradation of nitrogen heterocyclic compounds by M. aurum MO1. The first step of the degradative pathway is cleavage of the C---N bond; this leads formation of an intermediary amino acid, which is followed by deamination and oxidation of this amino acid into a diacid. Except in the case of thiodiglycolate obtained from thiomorpholine degradation, the dicarboxylates are completely mineralized by the bacterial cells. A comparison with previously published data showed that this pathway could be a general pathway for degradation by other strains of members of the genus Mycobacterium.

Methods of controlling cephalosporin use in Canadian hospitals.

Cephalosporin antibiotics contribute significantly to hospital antibiotic costs. A survey was conducted to determine cephalosporin use and prescribing control in Canadian hospitals over 300 beds. Of the 125 hospitals surveyed, 84 responses were received; 76 were included in data analysis. Thirty-two percent of hospitals had no restriction policies for intravenous cephalosporins and 88 percent had none for oral cephalosporins. Restrictions were more common for the second and third generation agents. The most common method of restricting cephalosporins was by requiring consultation with an infectious disease service. The yearly cost of cephalosporins varied considerably and was unrelated to the number of beds in the hospital. The data provided allows hospitals to compare their use of cephalosporin antibiotics with other institutions in Canada.