Biomedical subjects

M Rocher

Publications and source records attributed to M Rocher.

5 recordsLinked to original sources

PubMed2003

[Complications due to peripheral venous catheterization. Prospective study].

OBJECTIVE: Peripheral venous catheter (PVC)-associated complications were prospectively evaluated in a 2 month-study performed in 3 different wards. METHODS: For each inserted PVC, the following complications were observed daily by an external investigator: tenderness, erythema, swelling or induration, palpable cord and purulence. PVC that were removed were systematically sent to the Microbiology department and analysed according to the semi-quantitative method described by Brun-Buisson et al. RESULTS: A total of 525 PVC (corresponding to 1,036 catheterisation-days) were included. Main clinical complications were erythema (22.1%), tenderness (21.9%), swelling or induration (20.9%), palpable cord (2.7%) and purulence (0.2%). Phlebitis, defined by 2 or more of the following signs: tenderness, erythema, swelling or induration and palpable cord, was observed in 22%. Catheter colonization (> or = 103 CFU/ml) occurred in 13%. Bacteria isolated from colonized catheters were coagulase-negative staphylococci (88.1%), Staphylococcus aureus (7.1%) and Candida sp. (4.8%). Multivariate risk factor analysis showed that age > or = 55 y. (OR = 3.16, p = 0.003), insertion on articulation site (OR = 2.94, p = 0.01) or in jugular vein (OR = 8.18, p = 0.01) and > 72 hour-catheterisation (OR = 4.74, p = 0.0003) were significantly associated with PVC colonization. Risk factors for phlebitis were skin lesions (OR = 1.88, p < 0.016), active infection unrelated to PVC (OR = 2.8, p = 0.001), "poor quality" peripheral vein (OR = 2.46, p < 0.02) and > 72 hour-catherisation (OR = 2.38, p = 0.009). CONCLUSION: Complications associated with peripheral venous catheters are frequent but remain benign. They could probably be reduced by a systematic change every 72-96 hours as recommended by different guidelines.

Adolescent↗

PubMed2001

Excess sludge reduction in activated sludge processes by integrating biomass alkaline heat treatment.

With new EC regulations, alternative treatment and disposal techniques of the excess sludge produced by activated sludge wastewater treatment plants have to be developed. To decrease activated sludge production yield, microbial cell lysis can be amplified to enhance cryptic growth (biomass growth on lysates). Cell breakage techniques (thermal, alkaline and a combination) were studied to generate Ralstonia eutropha (strain model) and waste activated sludge lysates and to evaluate their biodegradability. Gentle treatment conditions by alkaline waste treatment (20 min at 60 degrees C and pH 10 by NaOH addition) allowed waste activated sludge to be solubilized by a two step process (instantaneous and post-treatment) giving a dissolved organic carbon released by the total suspended solids treated of 267 mgDOC x g(-1)TSS. The biodegradation of the soluble fraction of the lysates by fresh sludge reached 75 and 90% after 48 and 350 hrs of incubation respectively. A validation on a laboratory scale by insertion of a liquor alkaline heat treatment loop in a biological synthetic wastewater treatment process was carried out. A reduction of 37% of the excess sludge was obtained without altering the purification yield of the process.

Biodegradation, Environmental↗

PubMed1999

Towards a reduction in excess sludge production in activated sludge processes: biomass physicochemical treatment and biodegradation.

To decrease activated sludge production, microbial cell lysis can be amplified to enhance cryptic growth (biomass growth on lysates). Cell breakage techniques (thermal, alkaline, acid) were studied to generate Alcaligenes eutrophus and sludge lysates and to evaluate their biodegradability. Gentle treatment conditions produced the best results. Complete cell deactivation was obtained for temperatures higher than 55 degrees C. The release kinetics were similar for temperatures varying from 60 degrees C to 100 degrees C. A 20-min incubation was suitable for reaching 80% of the maximum releasable carbon. In thermal-chemical hydrolysis, NaOH was the most efficient for inducing cell lysis. Carbon release was a two-step process. First an immediate release occurred, which was of the same order of magnitude for A. eutrophus and sludge [100-200 mg dissolved organic C (DOC) g total suspended solids (TSS)-1], followed by a post-treatment release. The second step was virtually equivalent to the first for sludge, and weaker for A. eutrophus (< 50 mg DOC g TSS-1). The biodegradability of the soluble fraction, both the immediate and the post-treatment carbon release, was investigated. The optimal degradation yield, obtained with sludge cells, reached 55% after 48 h of incubation and 80% after 350 h. The most consistent lysis and biodegradation results occurred at pH 10 and 60 degrees C after a 20-min incubation.

Alcaligenes↗

PubMed1997

Effects of Low Dissolved-Oxygen Concentrations on Poly-(3-Hydroxybutyrate-co-3-Hydroxyvalerate) Production by Alcaligenes eutrophus.

The bacterial copolyester poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) was produced with Alcaligenes eutrophus DSM 545 from glucose and sodium propionate in a fed-batch fermentation with both nitrogen limitation and low dissolved-oxygen concentrations. When the dissolved-oxygen content was kept between 1 and 4% of air saturation during the polymer accumulation phase, the yield of 3-hydroxybutyrate (3HB) monomer from glucose was not affected, but the propionate-to-3-hydroxyvalerate (3HV) monomer yield was two to three times (0.48 to 0.73 mol of 3HV mol of propionate consumed(sup-1)) that observed in a control experiment (0.25 mol mol(sup-1)), where the accumulation-phase dissolved-oxygen concentration was 50 to 70% of air saturation. The overall polymer productivity of the fermentation was somewhat decreased by low dissolved-oxygen contents, owing to a slower 3HB production rate. The effect of a low dissolved-oxygen concentration is probably attributable to a reduction of the oxygen-requiring decarbonylation of propionyl-coenzyme A (CoA) to acetyl-CoA.

Journal Article↗

PubMed1988

Biological activity of retinoids correlates with affinity for nuclear receptors but not for cytosolic binding protein.

In order to better understand the respective roles of the nuclear retinoic acid receptors (RARs) and the cytosolic retinoic acid binding protein (CRABP) in the mode of action of retinoic acid (RA), several types of RA analogs have been synthesized. Representative compounds have been radiolabeled to a high specific activity and their binding (direct and competition) to RARs and CRABP was determined. Their biological activity on F9 embryonal carcinoma cell differentiation has been determined by a quantitative assay of plasminogen activator (PA). All biologically active analogs studied in this work bound to RARs. A good correlation was found between PA induction and affinity for the RARs, with the exception of RA itself which was a good ligand but a moderate inducer of F9 differentiation. Two biologically active analogs (compounds II and III) did not bind to the CRABP. One biologically inactive analog (compound VIII) bound to CRABP. These results strongly suggest that retinoids must bind to RARs but not necessarily to CRABP in order to induce cell differentiation in F9 cells.

Animals↗