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Biomedical subjects

Philippe Bertin

Publications and source records attributed to Philippe Bertin.

25 records · Page 2Linked to original sources
PubMed2002

Effect of mild acid pH on the functioning of bacterial membranes in Vibrio cholerae.

In this paper, we initiated the first two-dimensional electrophoresis map of Vibrio cholerae, the aetiological agent of cholera disease. In this pathogen the efficient adaptation to detrimental conditions plays an important role in its survival in both the aquatic reservoir and human intestine. By proteome analysis we investigated the effect of mild acid treatment on the physiology of V. cholerae. More than 50 proteins were identified by matrix-assisted laser desorption/ionization-time of flight mass spectrometry and database searching. Amongst them, pH regulated proteins belong to various functional classes such as intermediary metabolism and bacterial envelope. Several proteins whose accumulation level was decreased in response to acidic pH are known to be involved in the organization and the functioning of membranes, including lipopolysaccharide. Consistent with this, we observed an increased susceptibility to hydrophobic drugs, a loss of motility and a reduction in the ability to form a biofilm in cells grown at pH 6. Our results suggest that V. cholerae is able to sense a moderate decrease in pH and to modify accordingly its structure and physiology.

Bacterial Proteins↗
PubMed2002

Is the relationship between spondyloarthropathy and Sjögren's syndrome in women coincidental? A study of 13 cases.

OBJECTIVE: To determine the prevalence of Sjogren's syndrome (SS) in women with spondyloarthropathy (SpA). METHODS: Forty-one women with SpA manifesting as inflammatory back pain and/or peripheral arthritis were diagnosed as having ankylosing spondylitis, undifferentiated spondyloarthropathy, psoriatic arthritis, or enteropathic arthropathy based on accepted criteria. A validated questionnaire was used to look for sicca symptoms in the SpA group and in 102 controls with degenerative rheumatic diseases. Women with SpA and sicca symptoms and/or positive antinuclear antibodies (ANA) were investigated for SS by minor salivary gland biopsy. In the SpA group, the following tests were done: HLA B27; HLA DR, DQ; ENA; and serology for CMV, EBV, HIV, hepatitis B, and hepatitis C. RESULTS: Thirteen women (31.7%) met European criteria for SS, compared to three (2.9%) of the controls. Of the 41 women with SpA, 16 (39%) were ANA-positive. ANA were detected in eight of the 16 (50%) patients with SS. HLA B27 was present in 11 of the 13 (84.6%) SS patients. HLA DR 04.04 and DQ 03.03 seemed more common in SS patients, but the difference was not statistically significant. CONCLUSION: SS was far more common in the women with SpA (31.7%) than in the controls (2.9%), suggesting that the SpA-SS association may not be coincidental.

Adolescent↗
PubMed2002

Identification, characterization, and regulation of a cluster of genes involved in carbapenem biosynthesis in Photorhabdus luminescens.

The luminescent entomopathogenic bacterium Photorhabdus luminescens produces several yet-uncharacterized broad-spectrum antibiotics. We report the identification and characterization of a cluster of eight genes (named cpmA to cpmH) responsible for the production of a carbapenem-like antibiotic in strain TT01 of P. luminescens. The cpm cluster differs in several crucial aspects from other car operons. The level of cpm mRNA peaks during exponential phase and is regulated by a Rap/Hor homolog identified in the P. luminescens genome. Marker-exchange mutagenesis of this gene in the entomopathogen decreased antibiotic production. The luxS-like signaling mechanism of quorum sensing also plays a role in the regulation of the cpm operon. Indeed, luxS, which is involved in the production of a newly identified autoinducer, is responsible for repression of cpm gene expression at the end of the exponential growth phase. The importance of this carbapenem production in the ecology of P. luminescens is discussed.

Antibiosis↗
PubMedDate not supplied

[Is osteoporosis well treated in elderly people?].

Osteoporosis is an increase in bone fragility resulting from a decrease in bone mineral density and abnormalities in the bone micro-architecture. The frequency of osteoporosis is increasing with the aging of patients, and its clinical consequences, vertebral or peripheral fractures, are potentially extremely serious, especially in the very elderly. It is probable that osteoporosis is underdiagnosed--and when it is diagnosed it is often not well treated. It should be realised that a loss in bone mineral density is not the only risk factor for osteoporotic fractures: iatrogenic and environmental factors are also involved, and these are responsive to preventive intervention. Although elderly people usually take multiple drugs, drug treatment, initially calcium and vitamin D, but also bisphosphonates, should also be considered for osteoporosis.

Aged↗
PubMedDate not supplied

[Contribution of sacroiliac magnetic resonance imaging (MRI) to the evaluation of infliximab efficacy in spondyloarthropathy (a prospective study of 34 patients)].

Thirty-four patients who met ESSG criteria for spondylarthropathy and were eligible for anti-TNFalpha treatment (infliximab) were enrolled in this open-label study lasting 14 weeks. The aims were to evaluate the progression of sacroiliitis by means of MRI, and to determine the positive predictive value of this exam for the treatment response. Patients underwent MRI of the sacroiliac region at baseline (W0), and also at 14 weeks if the baseline MRI showed sacroiliitis. Two blinded readers reviewed all imaging studies. The patients also had a physical examination and ESR and CRP assays at W0 and W14. Sacroiliitis was found in 22 patients (65%) at W0, but only 18 of these patients had a second MRI at W14, for technical reasons. After 14 weeks of therapy, MRI signs of sacroiliac inflammation diminished by 77.7% on average. Clinical and biological parameters also improved. However, MRI was not predictive of the treatment response. Sacroiliac MRI seems to be interesting for objective therapeutic evaluation and monitoring of patients with spondyloarthropathy.

Adult↗