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Biomedical subjects

P Auger

Publications and source records attributed to P Auger.

At least 19 recordsLinked to original sources
PubMed1992

Growth factors and cell kinetics: a mathematical model applied to Il-3 deprivation on leukemic cell lines.

We assume the existence of a specific G1 protein which is an initiator of DNA replication. This initiator is supposed to be synthesized according to Michaelis-Menten kinetics. In order to start DNA replication, it is assumed that this G1 specific protein must be produced in a required amount. Intra-cellular growth inhibitors and extra-cellular growth factors control the production of the initiator. This model allows to calculate the average G1 phase time as a function of the various chemical concentrations of nutrients, enzymes, growth inhibitors and growth factors. This model is compared to cell kinetics experiments on a leukemic cell line responding to Interleukin 3 deprivation. The curves giving the experimental average G1 phase times with respect to Interleukin-3 concentrations are fitted by the mathematical model with a quite good agreement.

Cells, Cultured↗
PubMed1992

Interpretation of epicardial mapping by means of computer simulations: applications to calcium, lidocaine and to BRL 34915.

The aim of this work was to compare experimental investigations on effects of lidocaine, calcium and, BRL 34915 on reentries to simulated data obtained by use of a model of propagation based on the Huygens' construction method already described in previous works. Calcium and lidocaine effects are investigated on anisotropic conduction conditions. In both cases, reduction in conduction velocities are observed. In lidocaine case, a refractory area is located along the longitudinal axis. In agreement with experimental electrical mapping, the simulations show that the stabilization of reentrant excitation is mainly due to the existence of this refractory area around which the reentrant circuit can develop. The experimental study shows that BRL 34915 has both arrhythmogenic and antiarrhythmic effects. A detailed electrophysiological analysis has shown that drug infusion act on normal cardiac cells by decreasing the relative and absolute refractory period. BRL 34915 action is simulated by a decrease in the refractory period showing that the time frequency of the reentrant activity is increased and that the spatial size where the reentry is developing is becoming smaller. These two effects are arrhythmogenic, the simulated data being so in good agreement with the experimental ones.

Animals↗
PubMed1992

A multicenter, open comparative study of parenteral cefotaxime and ceftriaxone in the treatment of nosocomial lower respiratory tract infections.

A multicenter Canadian study enrolled 74 persons to compare low-dose cefotaxime at 1 g every 8 hr to ceftriaxone 1 g every 12 hr in patients with nosocomial pneumonia. Of 57 evaluable patients (30 cefotaxime and 27 ceftriaxone) in this preliminary report, 93% responded to therapy in both groups. Ceftriaxone patients tended to have more side effects (14.2%). This study is continuing to accrue patients to achieve 100 evaluable patients. Interim data, however, support the continued use of low-dose cefotaxime as an appropriate alternative for clinically effective and cost-effective management of nosocomially acquired pneumonia.

Adult↗
PubMed1991

Cell walls of normal and lysozyme-damaged blastoconidia of Candida albicans: localization of surface factor 4 antigen and vicinal-glycol staining.

The fungicidal effect of lysozyme on Candida albicans involves ultrastructural modifications previously described (G. Marquis, S. Montplaisir, S. Garzon, H. Strykowski, and P. Auger, Lab. Invest. 46:627-636, 1982). To further define the action of lysozyme on the yeast cell wall, we used the following: (i) the periodic acid-thiocarbohydrazide-silver proteinate (PA-TCH-SP) method to highlight vicinal-glycol-reactive sites of complex carbohydrates; (ii) a monospecific antiserum and a protein A-gold complex to study the expression of surface factor 4, a major Candida antigen; and (iii) the periodic acid-silver methenamine method to stain cell wall glycoproteins. All Candida cells were found to express surface factor 4 antigen. In normal blastoconidia, surface factor 4 was located in a glycoprotein-rich cell wall layer, underneath radially oriented bundles of filaments which form the outermost wall layer. In lysozyme-treated blastoconidia, this glycoprotein-rich layer was lost and the regular brushlike organization of the outer fibrillogranular layer was disrupted. PA-TCH-SP staining and localization of surface factor 4 antigen demonstrated an altered arrangement of bundles of filaments in the outer wall layers of blastoconidia which were morphologically intact but had abnormal cell wall appearance. Next, there was a reduction in thickness of the outer layer and the expression of surface factor 4 antigen was limited to the cytoplasmic membrane area. Later on, the cell wall was almost uniformly highlighted by PA-TCH-SP staining. These data evinced a highly plastic architecture of the cell wall in C. albicans.

Antigens, Fungal↗
PubMed1990

Incidence of occult athlete's foot in swimmers.

Athlete's foot is a dermatophytic infection frequently found in adults. This disease is, in some cases, asymptomatic. In order to evaluate the incidence of subclinical infection, we obtained 300 toe-web samples from the fourth interdigital space of 150 regular swimmers. More over, 66 specimens from the pool area were analysed. The method used was the carpet technique described by Mariat et al. (10). The fungal isolates were identified according to standard methods. A list of epidemiological data was completed for every swimmer. In our results, 22 swimmers had positive cultures (15%), 8 of these cases had no lesions (36%). They included 7 infections with Trichophyton mentagrophytes (87.5%) and one with T. rubrum (12.5%). We observed one case with a dual infection. Only one sample from the inanimate environment was positive. This study showed a significant incidence of occult athlete's foot in swimmers. To control this endemic problem, adequate preventive measures must be taken.

Adolescent↗
PubMed1990

Double-blind comparison of pefloxacin and cefazolin as prophylaxis in elective cardiovascular surgery.

A total of 162 patients (134 males and 28 females) scheduled for coronary artery bypass grafting (144) or valve surgery (18) were randomly assigned to receive, under double-blind conditions, either pefloxacin 400 mg iv or cefazolin 1.0 g 30 min before the surgical incision and then post-operatively 12-hourly x 4 or 6-hourly x 8, respectively. Positive per- and post-operative cultures were seen in 27 patients (11 pefloxacin, 16 cefazolin) and 47 micro-organisms were isolated: 34 per-operatively (21 pefloxacin, 13 cefazolin) and 13 post-operatively (4 pefloxacin, 9 cefazolin). There were five failures of prophylaxis (2 pefloxacin, 3 cefazolin): two early (less than 5 days: 1 pefloxacin, 1 cefazolin) and three late (greater than or equal to 5 days, 1 pefloxacin, 2 cefazolin) divided into (i) one major primary failure in the cefazolin group (1 cefazolin resistant Staphylococcus epidermidis mediastinitis); (ii) two minor primary failures, one in each group (Gram-positive sternal incision abscesses) and (iii) two secondary failures (1 cefazolin resistant Enterobacter cloacae and Pseudomonas aeruginosa UTI in the cefazolin group and one culture negative pneumonia in the pefloxacin group). Tolerance to both antibiotics was excellent. In our sample of patients, the efficacy and safety of pefloxacin was not different from those of cefazolin in prophylaxis in cardiovascular surgery.

Aged↗
PubMed1990

Interest of biotyping Candida albicans in chronic vulvovaginitis.

Chronic vulvovaginitis due to Candida albicans is a major clinical problem for the physician. Although new antifungal drugs are now available, the therapeutic approach of this disease remains disappointing. The aims of this study were two-fold. First, we wanted to evaluate the reliability of a single sampling performed by most clinicians in verifying if the yeast infects the entire genital mucosa or a preferential site and, second, to biotype the strains recovered in order to see if more than one strain are responsible for the infection. We found, in 18 patients suffering from vaginal candidosis, that the entire genital mucosa was infected by the yeast and the strain recovered from the different genital sites in a single patient was the same in 100% of the cases. Only 1.4% of the samples were negative. In addition, we biotyped the strains obtained from the gastrointestinal tract of these patients to evaluate this site as a potential source of infection. We obtained gastrointestinal tract samples for 15 of the 18 patients and we could identify C. albicans in 100% of the cases. Furthermore, 73.3% of the patients harboured the same strains of C. albicans in the gastrointestinal tract as in the vagina.

Adult↗
PubMed1989

Biotyping of Candida albicans: results of an international collaborative survey.

An agar plate system for biotyping isolates of Candida albicans was evaluated in four laboratories for 18 coded yeast isolates, each tested in triplicate on duplicate series of agar plates. The results showed that the biotyping system gave excellent intralaboratory reproducibility. However, because the concordance of data among laboratories was poor, the method must be regarded as suitable only for research applications and not for routine use.

Candida albicans↗
PubMed1989

Treatment of cutaneous candidosis in guinea pigs: effect of zinc oxide on the antifungal efficacy of nystatin.

This article describes the in vivo evaluation of a new topical preparation (Zincostatin) indicated for Candida albicans infected diaper rash. In order to study the influence of the 20% zinc oxide (W/W) (a protectant) on the anti-candidal efficacy of the 100,000 U/g of nystatin found in the ointment, groups of guinea pigs received different treatments with or without local occlusion. Zinc oxide, nystatin, or the combination of both were applied, in the ointment base, on the backs of the animals inoculated with a fresh strain of Candida albicans. Macroscopic and microbiological evaluation of the skin lesions were assessed at regular intervals during 21 days. While the two treatments containing nystatin were more effective than zinc oxide alone, the latter agent did not decrease the efficacy of the antifungal drug in combination therapy. Also, zinc oxide seemed to afford some protection against local maceration induced by occlusion, which increased the severity of the infection.

Animals↗
PubMed1988

Reduction of energy required for defibrillation by delivering shocks in orthogonal directions in the dog.

Reduction of energy required to defibrillate (ERD) seems to represent a necessary condition for intensive development of implantable defibrillator, so as for minimization of cardiac and pulmonary damages provoked by high energy transthoracic defibrillation electric shocks. The present work describes a defibrillation method using shocks delivered in orthogonal directions and separated by a 100 ms delay. Defibrillation threshold measured with classical unidirectional shocks on 30 dogs has been found to be 286.8 +/- 22.2 joules. In the same animals, defibrillation threshold measured by use of orthogonal shocks has been found to be 101.4 +/- 14.9 joules. We conclude that this crossed shocks method leads to a substantial reduction of ERD (64%).

Animals↗
PubMed1988

Genetics of resistance to infection with Candida albicans in mice.

To determine differences in susceptibility, 234 naive mice including xid and beige mutants were infected intravenously with Candida albicans and monitored with survival analysis and quantitative culture of the kidneys. By using survival time as the criterion, animals of seven inbred strains were separated into three groups. C3H/HeJ and Dw/+ were most susceptible; C57BR/cdJ, BRVR and CBA/N (xid) were intermediate in susceptibility; C57BL/KsJ and C57BL/6J were least susceptible. Mean survival times (MST) were markedly influenced by the number of Candida cells injected while the ranking of mouse strains by survival alone was unchanged. There was a dissimilar behaviour of the strains to produce organ weight changes in response to infection when compared with uninfected mice which were matched for age and genetic lineage. Black mice had lower colony forming units (CFU) per mg of tissue at the time of death than animals of other genetic lineage. Nevertheless, the finding that MST and CFU studies were loosely correlated in a few strains of mice indicated that the proliferation of the fungus in the kidneys was not always the major cause of death. The beige mutation was found to determine an increased susceptibility to systemic Candida infection. The differences in survival for beige and nonbeige mice were influenced by the genetic lineage of the host, being much greater in the C57BL/6 strain (36.7 days) than in the C3H/He strain (5 days). C57BL/6 beige-J had significantly higher CFU per organ and per unit of weight than C57BL/6 +/+ mice. These data evinced an important contribution of host genetic factors to resistance to systemic candidiasis. It is suggested that innate resistance genes regulate the differentiation in the bone marrow and the function of cells of granulocyte-macrophage lineage.

Animals↗
PubMed1987

[Prevention of infectious endocarditis following manipulations of the urogenital tract].

Instrumentation of the genito-urinary tract may cause transient bacteremia, it can result in bacterial endocarditis in predispose subject. We studied the incidence of transient bacteremia following urogenital procedure and discovered a 2.6% rate in 196 patients. Therefore we studied antimicrobial prophylaxis against strains isolated from urocultures (35 strains) and blood cultures (6 strains). The strain's minimal inhibitory concentration (MIC) confirms antibioprophylaxis suggested by American Heart Association (AHA). Mean-while, according to our results, netilmicin is the best choice.

Adolescent↗
PubMed1986

Monoclonal antibodies against Candida tropicalis mannan: antigen detection by enzyme immunoassay and immunofluorescence.

Three strains of mice were immunized with Candida tropicalis cell walls, and antibodies against mannan were detected by indirect enzyme immunoassay (EIA) in 3 of 9 BALB/c mice, 4 of 11 C57BL/6 mice, and 4 of 8 CFW mice. Responding mice produced immunoglobulin M (IgM), but IgG was not detected in their sera. Fusion of the high-responder BALB/c mouse with a plasmacytoma cell line resulted in 41 clones secreting antimannan monoclonal antibodies (MAbs). Four clones selected for propagation included one IgM and one IgG MAb that reacted with mannans of Candida albicans serotypes A and B and of C. tropicalis and two IgM MAbs specific for an epitope only in the mannans of C. albicans serotype A and C. tropicalis. One of the IgM MAbs, CB6, was an effective substitute for rabbit antibodies in the double-antibody sandwich EIA to detect antigenemia produced in rabbits infected with C. albicans A or C. tropicalis. It could function either as the peroxidase-conjugated indicator antibody or as the capture antibody. Two MAbs, CB6 (C. tropicalis and C. albicans A specific) and AC3 (C. tropicalis and C. albicans A and B specific), functioned in place of polyclonal antisera in the serotyping of C. albicans by immunofluorescence. There was 95.8% agreement in the results of serotyping using MAbs as reagents compared with rabbit antisera. Competitive inhibition in EIA between CB6 and monospecific antisera against C. albicans factors 1, 4, and 6 indicated that CB6 binds to an epitope which is probably factor 6. Serologic similarity between factor 4 and the binding site of MAb AC3 was also determined.

Animals↗