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V Dupont

Publications and source records attributed to V Dupont.

11 recordsLinked to original sources
PubMed2001

Bacterial swarming: a biochemical time-resolved FTIR-ATR study of Proteus mirabilis swarm-cell differentiation.

Fourier transform infrared spectroscopy was applied to the study of the differentiation process undergone by Proteus mirabilis. This bacterium exhibits a remarkable dimorphism, allowing the cells to migrate on a solid substratum in a concerted manner yielding characteristic ring patterns. We performed an in situ noninvasive analysis of biochemical events occurring as vegetative cells differentiate into elongated, multinucleate, nonseptate, and hyperflagellated swarm cells. The major findings arising from this study are (i) the real-time monitoring of flagellar filament assembly, (ii) the evidence for de novo synthesis of qualitatively different lipopolysaccharides (LPS) and/or exopolysaccharides (EPS) constituting the slime into which bacteria swarm, and (iii) the alteration in the membrane fatty acid composition with a concomitant 10 degrees C decrease in the gel/liquid crystal phase transition resulting in an elevated membrane fluidity in swarm cells at the growth temperature. The time course of events shows that the EPS-LPS syntheses are synchronous with membrane fatty acid alterations and occur about 1 h before massive flagellar filament assembly is detected. This study not only provided a time sketch of biochemical events involved in the differentiation process but also led to the identification of the major spectral markers of both vegetative and swarm cells. This identification will allow to resolve the time-space structure of P. mirabilis colonies by using infrared microscopy.

Kinetics↗
PubMed1996

Invasive candidiasis complicating spontaneous esophageal perforation (Boerhaave syndrome).

Spontaneous esophageal perforation is a rare condition that frequently results in infectious complications. Empirical broad-spectrum antibacterial therapy is therefore part of the standard management. We describe two patients suffering from spontaneous esophageal perforation who developed invasive candidiasis with hematogenous dissemination. One patient died of multiple organ failure due to Candida sepsis. Preexistent Candida colonization, incomplete mediastinal drainage, broad-spectrum antibacterial therapy, and prolonged intensive care therapy place patients with esophageal perforation at high risk for secondary fungal infection. Intense microbiological searching is mandatory, but the distinction between colonization and infection may be impossible. Empirical antifungal treatment with imidazole derivatives, particularly in patients with potential risk factors, should be considered.

Candidiasis↗
PubMed1994

Turn induction by N-aminoproline. Comparison of the Gly-Pro-Gly and Gly psi [CO-NH-N]Pro-Gly sequences.

The folded structure induced by the N-aminoproline residue (the hydrazino analogue of proline, denoted hPro) in the Boc-Gly1-hPro2-Gly3-NHiPr hydrazino tripeptide has been characterized in the solid state by X-ray diffraction, and compared to the usual beta II-turn structure in the Boc-Gly1-Pro2-Gly36-NHiPr cognate tripeptide. It is stabilized by a bifurcated hydrogen bond in which (Gly3)NH interacts with both (Gly1)CO and (hPro2)N alpha. This conformation is retained in CH2Cl2 and CHCl3 solutions, and allows an overall folded conformation of the hydrazino tripeptide in which (iPr)NH is hydrogen-bonded to (Boc)CO. The hPro alpha-hydrazino acid residue appears to promote a local folded structure, and might behave as a beta-turn mimic.

Amino Acid Sequence↗
PubMed1990

[Enteral nutrition at home with jejunostomy catheter].

Ten patients with obstructive tumors of the upper gastrointestinal tract received a catheter jejunostomy (CJ) for long periods of enteral nutritional support. Seven of those patients received home enteral nutritional support for a period of 2-9 months. Body weight and serum albumin remained constant during the nutritional therapy. Complications (diarrhea, leakage) were rare and could successfully treated without interruption of feeding. In our experience CJ is a safe and effective method for home enteral nutritional support.

Catheters, Indwelling↗
PubMedDate not supplied

Folded structures in protonated reduced dipeptides.

Reduced dipeptides with the general formula RCO-Xaa-rXbb-N+HR'R" (rXbb, reduced analogue of residue Xbb: NH-C alpha HR1-CrH2) are shown to adopt a folded conformation in solution and in the solid state. The protonated reduced amide bond is an active proton donor capable of interacting with a peptide carbonyl to give a strong hydrogen bond topologically equivalent to the i+2 or i+3-->i interaction. The resulting conformation is similar to the y- or beta-turn structure found in peptides and proteins.

Crystallization↗