PubMed Health⌕ Search

Biomedical subjects

B Poutrel

Publications and source records attributed to B Poutrel.

79 records · Page 5Linked to original sources
PubMed1978

Cell-wall proteins of Staphylococcus aureus : a kinetic study of release by lysostaphin.

The kinetics of cell-wall hydrolysis of Staphylococcus aureus (strain Cowan I) by lysostaphin was studied by turbidity, quantitative determination of hexosamines, phosphorus, total proteins, protein A and by electron microscopy. In our experimental conditions, the lytic activity of lysostaphin was very fast and no characteristic cell-wall structures could be seen after five minutes. The release of hexosamines, phosphorus and protein A was synchronous and could be recorded even though turbidity had become stable. At the end of the hydrolysis, the totality of these components was solubilized. Total proteins represented about 14% of the cell-wall dry weight. During hydrolysis protein A was the only protein solubilized.

Bacterial Proteins↗
PubMed1978

Study of factors influencing the effectiveness of two treatments, penicillin-streptomycin and rifamycin, against experimentally induced staphylococcal mastitis in lactating cows.

The effectiveness of two antibiotic preparations, a combination of Penicillin-Streptomycin and Rifamycin SV, was measured on persistent subclinical infections produced experimentally by two strains of Staphylococus aureus in the bovine mammary gland. Effects of different parameters upon the efficiency of these treatments were analysed. The combination Penicillin-Streptomycin cured 23 quarters of 46 treated (50 %) against 14 out of 55 for the Rifamycin SV (25 %). This difference was significant (P less than 0.02). Whatever the antibiotic preparation used the highest cure rate was observed for the cows in first lactation (60 % against 24 %) and beyond the second month of lactation (43 % against 10 %). The factors dependent on the cow were related to these two parameters. Front quarters were cured in higher percentage (43 %) than rear quarters (29 %), although the difference was not statistically significant. The influence of other parameters on the cure rate, such as previous cleared infections and number of CFU and somatic cells in the quarters at the time of treatment, depended on the treatment used. The bacteriological results showed that cures could be correctly evaluated only after a minimum interval of three weeks post treatment. From the data a standardised model is proposed for the evaluation of the effectiveness of treatments.

Animals↗
PubMed1977

[Validity of quantitative protein A determination of "Staphylococcus aureus" by radial immunodiffusion].

The validity of quantitative determination of protein A by radial immunodiffusion has been tested using human serum, human IgG and porcine serum. The best results are obtained with porcine serum. Maximal sensitivity is obtained after 48 h of incubation with 15 microliters of porcine serum per 13 ml of gel. For these particular conditions the range of linearity varies between 20 and 300 microgram/ml.

Animals↗
PubMedDate not supplied

Quantification of C5a/C5a(desArg) in bovine plasma, serum and milk.

Complement activation generates two potent inflammatory mediators from C5, C5a and its derivative C5a(desArg), which results from the removal of the C-terminal arginine by ubiquitous carboxypeptidases. In this paper we describe the purification of milligram amounts of bovine C5a(desArg) by a simplified procedure, and the preparation of mouse monoclonal antibodies (MAbs) to C5a/C5a(desArg) which do not recognize native C5. A MAb was used to develop a sandwich ELISA which made it possible to quantify levels of C5a/C5adesArg in bovine biological fluids. Small amounts (means +/- SEM) of C5a/C5a(desArg) were found in EDTA-plasma (0.58 +/- 0.06 ng.mL-1). The anticoagulant EDTA was more efficient than citrate or heparin in inhibiting in vitro activation of the complement system. Complement activation occurred during coagulation since the baseline concentration of C5a/C5a(desArg) (15.4 +/- 4.1 ng.mL-1) was higher than in plasma. Zymosan, a potent activator of the complement cascade, was used to generate C5a/C5a(desArg). The time-course of the reaction and the dose-effect of zymosan were investigated. Optimal conditions were incubation at 39 degrees C for 1 or 2 h with 2 mg of zymosan per mL of serum. The maximal concentration of C5a/C5a desArg attained in zymosan-activated serum was 4.28 +/- 0.14 micrograms.mL-1. Normal milk (from healthy, uninflamed mammary glands) contained on average 0.12 ng of C5a/C5a(desArg).mL-1 (range 0.02-0.19 ng.mL-1). The maximal amount of C5a/C5a(desArg) which was generated in milk with zymosan was 1.1 ng.mL-1 (range 0.68-2.17 ng.mL-1). In milk from quarters with subclinical infections by coagulase-negative staphylococci, values were 0.18 ng.mL-1 and 2.37 ng.mL-1 for spontaneous and zymosan-generated C5a/C5a(desArg) concentrations, respectively. In milk from Escherichia coli endotoxin-induced mastitis, C5a/C5a(desArg) concentrations (means of four cows) before and after zymosan activation reached 6.5 ng.mL-1 and 55 ng.mL-1, respectively. These results indicate that a C5-convertase can operate in normal milk, that only minute amounts of C5a/C5a(desArg) can be generated (less than 1/1,000 of plasma potential), but that much higher concentrations are reached in milk during endotoxin-induced inflammation. The ELISA made it possible to determine normal ranges of C5a/C5a(desArg) in bovine blood plasma and in milk, and is a valuable tool to define the variations of its concentrations in exudates during inflammatory reactions.

Animals↗