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Biomedical subjects

L Lebrun

Publications and source records attributed to L Lebrun.

At least 19 recordsLinked to original sources
PubMed1993

Diffusion of sucrose and dextran through agar gel membranes.

Mass transfer limitations severely impede the performance of bioreactions involving large molecules by gel-entrapped microorganisms. This paper describes a quantitative investigation of such diffusional limitations in agar gel membranes. Sucrose and commercial dextran fractions with (weight-average) molecular weights ranging from 10,000 to 2,000,000 Da were used as standard diffusants. For all tested solutes but sucrose, the values of the agar/water partition coefficients highlighted steric hindrance at the entrance of the membrane pores. The effective diffusivity of sucrose in agar was similar to that in water. All dextran fractions, however, displayed restricted diffusion in the agar membranes. Their effective diffusivities were a decreasing function of the agar content of the gel membrane (0.5, 1.0, or 1.5% w/v). The effective diffusivity in a given membrane decreased as the molecular weight of the diffusing molecule increased. T500 (Mw = 470,000 Da) and T2000 (Mw = 1,950,000 Da) fractions were unable to diffuse through 1.0 or 1.5% agar membranes. The diffusion data did not agree with the classical (Renkin) model for a hard sphere diffusing through a cylindrical pore. These results are discussed in terms of gel and diffusant characteristics.

Agar↗
PubMed1992

Impaired functions of normal peripheral polymorphonuclear leukocytes in cirrhotic ascitic fluid.

The function of normal polymorphonuclear cells in the ascitic fluid of 32 patients with cirrhotic ascites and 17 patients with malignant ascites was studied independently of ascitic fluid heat-labile factors. Polymorphonuclear (PMN) function was assessed by a chemiluminescence method using preopsonized zymosan as stimuli. The chemiluminescence response was higher in malignant ascitic fluid than in cirrhotic ascitic fluid (0.84 and 0.15, respectively, p < 0.001). These results were confirmed by a microbiological assessment of phagocytosis. Suppressive factors were evidenced by making ascitic fluid dilutions and using cell-free chemiluminescence measurements. Addition of malignant ascitic fluid to cirrhotic ascitic fluid showed that there is also a deficiency in supportive factors other than C3. The impaired PMN production of oxidative metabolites we observed in cirrhotic ascitic fluid can partly explain the high susceptibility of cirrhotic patients to spontaneous bacterial peritonitis independently of C3 levels.

Adult↗
PubMed1992

Enhancement of normal polymorphonuclear cells respiratory burst in ascitic fluid by fibronectin. Comparison between cirrhotic and malignant ascitic fluids.

The chemiluminescence (CL) response of normal peripheral blood polymorphonuclear cells (PMN) in ascitic fluids (cirrhotic = 32; malignant = 17) was studied independently of the ascitic fluid complement activity. CL response and fibronectin levels were higher in malignant ascitic fluid than in cirrhotic ascitic fluid (p less than 0.001). Addition of pure fibronectin or malignant ascitic fluids to cirrhotic ascitic fluids increased the CL response of normal PMN. These findings suggest that the susceptibility of cirrhotic patients to spontaneous bacterial peritonitis (SBP) is a multifactorial defect involving factors distinct from low C3 levels. Fibronectin is an important factor in the promotion of the respiratory burst of normal PMN stimulated by opsonized zymosan or PMA in ascitic fluid. Our results suggest that low levels of ascitic fluid fibronectin could partly explain the high susceptibility of cirrhotic patients to spontaneous bacterial peritonitis.

Adult↗
PubMed1992

Evaluation of nonradioactive DNA probes for identification of mycobacteria.

Commercial chemiluminescent DNA probes (Accuprobe; Gen-Probe, San Diego, Calif.) for the identification of Mycobacterium tuberculosis (MTB) complex, M. avium complex (MAC), M. gordonae, and M. kansasii were evaluated with 134 clinical isolates. These included 36 MTB complex, 40 MAC, 27 M. gordonae, 9 M. kansasii, and 22 Mycobacterium spp. The specificity was 100% for the four probes. The sensitivity was 100% for the MTB complex and M. gordonae probes and 95.2% for the MAC probe. Five of the nine M. kansasii isolates tested were not detected with the probe.

DNA Probes↗
PubMed1991

[Value and limits of research on Mycoplasma hominis and Ureaplasma urealyticum in the gastric fluid of newborn infants].

Mycoplasma hominis and Ureaplasma urealyticum were cultured and counted in the gastric fluid of 153 neonates divided into three groups: 28 preterm neonates managed in an intensive care unit (Group I); 83 full term neonates with suspected infection (Group II); and 42 full term neonates with no evidence of infection (Group III). The colonization rate (17.85%) in the intensive care unit group was not significantly different from the rates seen in the two other groups. These results do not militate against the pathogenic role of the two organisms studied but rather suggest a contributory role of other factors.

Colony Count, Microbial↗
PubMed1991

[The cost of HIV infection: method and results].

The project concerned hospital costs: in-patient, out-patient, clinics and home-hospitalisation. It included asymptomatic HIV-infected individuals as well as AIDS patients. The annual cost per patient was calculated according to the various types of disease management described by involved physicians. Standard annual per-patient cost was between 2,470 and 338,000 according to the severity of the disease (four stages of severity have been defined). The standard annual cost per HIV-infected patient with Kaposi's sarcoma was in the range FF 89,000 to FF 131,000. The standard cost of surveillance for an asymptomatic HIV-infected pregnant woman was just over FF 3,400. The standard annual cost per child born to an asymptomatic HIV-infected mother was FF 12,300 for a child enrolled in an epidemiology protocol; it was FF 42,000 or FF 196,000 for a child with AIDS according to the severity of the illness. Furthermore, the study highlights the heterogeneity of medical practice, greater in the earlier stages of the disease, and the incidence of difference forms of disease management upon costs.

Acquired Immunodeficiency Syndrome↗
PubMed1991

[Value and limitations of the research of Mycoplasma hominis and Ureaplasma urealyticum in gastric fluid in newborn infants].

Mycoplasma hominis and Ureaplasma urealyticum were cultured and counted in the gastric fluid of 153 neonates divided into three groups: 28 preterm neonates managed in an intensive care unit (Group I); 83 full term neonates with suspected infection (Group II); and 42 full term neonates with not evidence of infection (Group III). The colonization rate (17.85%) in the intensive care unit group was not significantly different from the rates seem in the two other groups. These results do not militate against the pathogenic role of the two organisms studied but rather suggest a contributory role of other factors.

Gastric Juice↗
PubMed1990

Human seminal plasma suppresses the chemiluminescence of polymorphonuclears without modifying phagocytosis.

The suppressive activity of human seminal plasma was confirmed on the luminol-amplified chemiluminescent reaction of human polymorphonuclears. This suppression was found to be dose-dependent and noncytotoxic. The responsible factor appeared to be a radical scavenger of low molecular weight, acting selectively on hydrogen peroxide. Correlation with glandular markers of semen indicated this molecule to have a prostatic origin. Neither crude seminal plasma nor this factor were found to suppress intracellular engulfment and killing of bacteria. This molecule seems to cooperate with the other semen antioxidants to protect sperm cells from extracellular oxygen radicals.

Humans↗
PubMed1990

[A study of fetal pulmonary maturity using amniotic fluid obtained from the vagina after premature rupture of membranes].

Amniotic fluid was obtained from the vagina not more than 24 hours before delivery in 100 patients who had premature rupture of the membranes. Thirty per cent of these cases had contamination with blood or with meconium. Phosphatidylglycerol (PG) estimate the degree of lung maturity using an immunological method (AMNIOSTAT-FLM test). In the 22 cases where the gestational age was 35 weeks or less there were two cases of hyaline membrane disease. In 68% of the 22 cases, the PG was negative, intermediate in 14% and positive in 18%. One of the cases of hyaline membrane disease was accompanied by fluid that was not infected and that was negative for PG; the other case had infection with S. faecalis and the PG was intermediate. On the other hand in the 78 cases when the pregnancies had lasted longer than 35 weeks there were no children who had hyaline membrane disease. The PG reaction was positive in only 57% of these cases. Search for bacteria showed infection in 10 cases (three with alpha-haemolytic streptococci, four with group B beta-haemolytic streptococci and three with E. coli). Determination of PG on the supernatant of reference strain cultures showed positive results for S. faecalis and E. coli. In conclusion, the poor specificity of the test (48%) and the possibility that when there was bacterial contamination false positive results were obtained shows that looking for fetal maturity by testing amniotic fluid from the vagina is unreliable and is contra-indicated.

Amniotic Fluid↗
PubMed1989

Direct testing of blood culture for detection of the serotype 5 and 8 capsular polysaccharides of Staphylococcus aureus.

Monoclonal antibodies (MAbs) reactive with serotype 5 and 8 capsular polysaccharides of Staphylococcus aureus have been used to test, by enzyme-linked immunosorbent assay (ELISA), blood culture fluids for the presence of S. aureus. A total of 748 blood cultures from 665 patients yielding 706 bacterial isolates belonging to more than 26 bacterial species were studied. All blood cultures containing bacterial strains belonging to species other than S. aureus were negative in ELISA. All 23 blood cultures containing serotype 5 S. aureus were positive in ELISA with the corresponding MAb. Out of 20 blood cultures containing serotype 8 S. aureus, 19 were positive with the corresponding MAb. All 5 blood cultures containing nontypeable S. aureus were negative in ELISA with both MAbs. This method provides reliable identification of serotype 5 or serotype 8 S. aureus by direct testing of blood culture fluids with ELISA.

Animals↗
PubMed1987

Predominance of capsular polysaccharide type 5 among oxacillin-resistant Staphylococcus aureus.

The relationship between capsular polysaccharide types 5 and 8 and resistance of Staphylococcus aureus to oxacillin was studied with a collection of 406 clinical isolates from six French hospitals. Of 175 type 5 isolates, 84 (48%) were resistant to oxacillin. In contrast, only 8 of 160 type 8 isolates (5%) and 5 of 71 nontypeable isolates (7%) were resistant to oxacillin. Therefore, capsular typing of clinical isolates of S. aureus may facilitate the choice of first-line antibiotic therapy.

Bacterial Capsules↗
PubMed1987

[Comparative pharmacokinetics of fosfomycin in the neonate: 2 modes of administration].

In newborn, fosfomycin-cefotaxime in combination is more and more commonly used for the treatment of nosocomial infections. A pharmacokinetic study was conducted in ten newborns in the aim of suggesting a therapeutic schedule of the fosfomycin. Each newborn received 200 mg/kg, intravenously twice a day. Two groups have been formed according to the time of perfusion: 2 h or 30 min. The study of pharmacokinetic parameters do not demonstrated significant difference between the two populations. In addition, residual serum concentrations, twelve hours after the administration, are greater than the minimal inhibitory concentrations of most common pathogens causing nosocomial infections in neonates.

Age Factors↗
PubMed1986

Human Fc(gamma) receptors for differentiation in throat cultures of group C "Streptococcus equisimilis" and group C "Streptococcus milleri".

The biochemical characteristics and the presence of human Fc(gamma) receptors of 52 throat isolates of group C beta-hemolytic streptococci were examined. Among these isolates, 38 were identified as "Streptococcus milleri" and 14 were identified as "Streptococcus equisimilis." The differentiation of group C "S. equisimilis" from "S. milleri" with identical group antigens was easy to perform by the measurement of the size of the hemolytic zone on a sheep blood agar plate in an anaerobic atmosphere and by biochemical tests (Voges-Proskauer test). A clear-cut criterion for differentiation was noted among these isolates, i.e., the presence of Fc(gamma) receptors. "S. equisimilis," which are generally associated with pharyngitis, possess human Fc(gamma) receptors, while "S. milleri", which are generally isolated from healthy persons, have no such receptors.

Humans↗
PubMed1986

Immunofluorescence characterization of Legionella: narrow specificity of polyclonal immunsera to various serogroups and species.

This study was to determine by direct fluorescent antibody staining with antibodies prepared in rabbits, the degree of cross-reactions between serogroups of Legionella pneumophila (1 to 6) and the other antigenic species of Legionella (L. bozemanii, L. dumoffii, and L. micdadei), in order to increase the accuracy of diagnosis and to allow us to reduce the number of conjugates. The polyclonal antibodies were highly species and serogroup-specific without absorption for characterization of Legionella either in patient specimens or in isolated cultures by direct fluorescent antibody staining. No cross-reaction was observed with non-legionella bacteria isolated from sputum specimens. A battery of conjugates for different serogroups and species is necessary for increasing the accuracy of diagnosis of legionellosis.

Animals↗
PubMed1985

[Technic for detecting several yeasts in the same sample].

The frequent association of Torulopsis glabrata with other yeasts of the genus Candida in the same clinical specimen may lead to false results because of the large number of negative characters in this yeast. We describe here a technique of detection based on the pigmentation of colonies obtained by reduction of triphenyl-tetrazolium chloride added to the Sabouraud medium.

Aged↗
PubMed1982

A critical study of the use of staphylococci containing protein A for separation of IgG and IgM antibodies.

This study was to determine the best conditions for using staphylococci bearing protein A to separate IgG from IgM. The validity of the technique was evaluated for detection of IgM with antimicrobial activity and for typing monoclonal IgM. The results indicate that separation of IgG and IgM is not entirely satisfactory in normal sera and worse in hyperglobulinemic sera. The detection and titration of IgM antimicrobial antibodies (rubella and hepatitis B core (HBc) specific IgM) was unreliable because IgG was only partially absorbed by staphylococcal cells, while a significant portion of IgM was bound. The use of higher concentrations of staphylococci did not improve the results because the more IgG was absorbed, the more IgM was also bound. It is shown that with anti-HBc specific IgM the risk of misinterpretation is very high with a sensitive radioimmunoassay technique allowing detection of trace amounts of nonabsorbed IgG. In contrast staphylococcal protein A proved useful in typing monoclonal IgM.

Animals↗