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Biomedical subjects

P Courtois

Publications and source records attributed to P Courtois.

At least 55 records · Page 3Linked to original sources
PubMed1992

Susceptibility of anaerobic microorganisms to hypothiocyanite produced by lactoperoxidase.

The susceptibility of Capnocytophaga ochracea, Eikenella corrodens, Eubacterium yurii, Fusobacterium nucleatum, Peptostreptococcus micros, Prevotella intermedia, Selenomonas sputigena, Wolinella recta to hypothiocyanite (OSCN-) produced by the lactoperoxidase system was tested. Results showed a decrease of bacterial survival rate after OSCN- exposure, with an intra- and inter-species variability from 0 to 95% for C. ochracea, 34-100% for E. corrodens, 0-83% for E. yurii, 1-15% for F. nucleatum, 8-61% for P. micros, 0-100% for P. intermedia, 0-44% for S. sputigena and 0-8% for W. recta. The survival rate did not correlate with the NADH/OSCN- oxidoreductase activity present in the lysed bacteria (r = -0.3248; N = 15; NS).

Anti-Bacterial Agents↗
PubMed1992

Peroxidase activity loss after filtration and centrifugation of whole saliva. Influence of citrate.

Filtration or centrifugation are two methods frequently used to clarify human whole saliva. This study compares both the drop in peroxidase activity following filtration (49.3% +/- 16.4%; N = 12) or centrifugation (33.6% +/- 15.9%; N = 6) and the drop in total protein concentration after filtration (33.9% +/- 13.4%) and centrifugation (23.6% +/- 8.7%). After filtration, the loss was not only due to retention of the large particle-bound fraction but also to adsorption on the filter membranes. This adsorption could be inhibited by a previous dilution of saliva in a citrate buffer, which also gave rise to active subunits with a molecular weight less than or equal to 100 kDa.

Adsorption↗
PubMed1991

[Circadian variations in the nephrotoxicity of the vancomycin-gentamicin combination in rats].

Male Wistar rats were used to evaluate the influence of time of administration of a single high dose of vancomycin (V), gentamicin (G) or vancomycin-gentamicin combination (V/G) on excretion of a brush border enzyme, alanine aminopeptidase (AAP) and of a lysosomal enzyme, N-acetyl-beta-D-glucosaminidase (NAG). Increased urinary excretion is considered as an early manifestation of renal toxicity. The rats were placed in temperature-controlled quarters with intermittent lighting (12 hours light/12 hours dark). V was given intraperitoneally in a dose of 200 mg/kg, G was given intramuscularly in a dose of 100 mg/kg, and the V/G combination was given in the same doses and by the same routes as each drug alone. A control batch of rats received an intraperitoneal injection of saline. In the four batches, the injection was given at 8 am, 2 pm, 8 pm and 2 am. Substantial brush border toxicity was found. Toxicity of G was greatest at 2 pm and lowest at 2 am, whereas for V, toxicity was greatest at 2 am and lowest at 2 pm. With the V/G combination, brush border toxicity was greatest at 2 am and lowest at 8 am. Lysosomal toxicity was no significant after administration of V or G. In contrast, the V/G combination induced very significant lysosomal toxicity which was greatest at 2 pm and smallest at 8 am. These results show that circadian variations in renal toxicity occur not only with V and G alone but also with the V/G combination.

Acetylglucosaminidase↗
PubMed1990

Seasonal effects on the daily variations of gentamicin-induced nephrotoxicity.

The effect on kidney damage of the season of year at which gentamicin was administered to rats was studied. Rats received a single intramuscular dose of 200 mg/kg gentamicin at four different times of the day (08.00, 14.00, 20.00 or 02.00 hours. Studies were carried out in January-February, March-April, June-July and October-November. The nephrotoxicity was assessed by the increase of three urinary enzymes: two brush border enzymes, gamma-glutamyl transferase and alanine aminopeptidase, and a lysosomal enzyme: N-acetyl-beta-D-glucosaminidase. The results show that when the injection is administered at 20.00 hours in the January-February and the October-November studies and at 08.00 hours in the March-April study and at 14.00 hours in the June-July study there is a significant increase in the excretion of these enzymes. The renal toxicity of gentamicin therefore has circadian variations as well as seasonal variations. The peak enzyme level is displaced from the start to the end of the rest period of rats depending upon the time of year.

Acetylglucosaminidase↗
PubMed1990

Aluminum transfer as glutamate complex through blood-brain barrier. Possible implication in dialysis encephalopathy.

In vitro distribution of aluminium between plasma and erythrocytes has been studied in the presence of variable amounts of sodium L-glutamate. With a red blood cell suspension in isotonic sodium chloride, aluminium remains confined in erythrocytes even when the sodium L-glutamate concentration increases in the medium. Aluminium initially present in plasma penetrates red blood cells when sodium L-glutamate increases in whole blood, showing that this metal is able in vitro to cross the erythrocyte membrane as glutamate complex. In vivo experiments with male Wistar rats prove that aluminium is also able to pass the blood--brain barrier as glutamate complex and deposit in the brain cortex.

Aluminum↗
PubMed1990

Inhibition of HIV infectivity by lactoperoxidase-produced hypothiocyanite.

HIV aliquots, from a supernatant of ARV-4 cell line, were mixed with an equal volume of a OSCN.generating glucose-glucose oxidase + thiocyanate-lacteroperoxidase solution, and then pre-incubated at 37 degrees C for periods of 30 secs to one hour. These mixtures were then inoculated into cultures of phytohaemagglutinin-stimulated lymphocytes. Viral growth was monitored with an ELISA quantitating the specific p24 protein either in the culture cells or in the supernatant. In control experiments, the virus produced both intra- and extra-cellular p24. In the controls, concentration of p24 per 10(6) lymphocytes grew rapidly. By contrast, HIV that was pretreated with the OSCN generating system for 30 sec., produced very little p24, and no detectable amount of this protein could be found after 2 min. pre-treatment.

Antiviral Agents↗
PubMed1990

[Antiseptic properties of saliva and metabolism of activated oxygen in neutrophils: comparison of the 2 enzymatic bactericidal systems and of their behavior in an acid environment].

Growth control of anaerobes in the oral cavity, is secured--among other means--by: 1) phagocytosis of opsonized bacteria; 2) synthesis of hypothiocyanite by the salivary peroxidase system. The former may be inhibited by bacterial acid byproducts. As for the salivary hypothiocyanite, it proved itself able of hindering in vitro the growth of bacterial strains known as customary periodontal pathogens. Its possible effectiveness in vivo remains however hypothetical in the case of deep gingival pockets according to the poor diffusion there of salivary components.

Anti-Bacterial Agents↗
PubMed1989

Protein kinase C deficiency in juvenile chronic myeloid leukemia: a case report.

Protein kinase C activity was assayed in morphologically differentiated and undifferentiated myeloid cells of a 13-month-old girl with chronic myeloid leukemia. A reduced protein kinase C activity was seen in the morphologically differentiated neutrophils, while the activity in the leukemic cells was higher to that of normal neutrophils from control subjects.

Adult↗
PubMed1989

Fluctuation of the biochemiluminescence from PMN leukocytes in a family with a high prevalence of severe periodontitis.

Rapidly progressive periodontal disease was found in three patients belonging to three different generations of the same family. Beyond the clinical inspection, blood examination allowed measurements of the luminol enhanced biochemiluminescence from the circulating PMN leukocytes. Abnormally low values were recorded in the affected individuals (75, 84 and 138 mVolts per 10(6) cells) whereas a sample of healthy individuals exhibited photonic values from 240 up to 910 mVolts per 10(6) cells. These abnormal values, however, were not constantly recorded. They gave way to higher PMN activity indices after the patients had been treated either by antibiotics, scaling, debridement or classical pocket cleaning.

Adolescent↗
PubMed1989

Anaerobes and short-chain fatty acids in crevicular fluid from adults with chronic periodontitis.

Pathogeny of adult chronic periodontitis is still unclear. Bacteriological and chemical analysis of crevicular fluid have shown, in active sites of the disease, a simultaneous presence of anaerobes and their major by-product: short-chain fatty acids. The last can decrease "in vitro" the neutrophil intracellular pH, whenever these cells are incubated in an acid medium. Clinical investigations are scarce which hold out data useful to attempt verifying this possible physiopathological mechanism. This work shows the presence of anaerobes in the active periodontal pockets, together with the presence of short-chain fatty acids likely to reach a concentration level comparable to that used for inhibiting neutrophils "in vitro". Forthcoming studies should investigate about a possible intracellular pH drop in the neutrophils and other cells of the inflamed periodontium.

Adult↗
PubMed1988

Circadian variations in the renal toxicity of gentamicin in rats.

The hypothesis that sublethal doses of aminoglycosides cause renal tubule disorders resulting in changes of urine enzyme levels was investigated. The renal status following injection of a single sublethal dose of gentamicin (200 mg/kg) at different times during a 24 h cycle was studied. Increased excretion of gamma-glutamyl transferase, alanine aminopeptidase and N-acetyl-beta-D-glucosaminidase, used clinically as markers for tubule toxicity of aminoglycosides, was maximal when gentamicin was administered to rats at 2 p.m. and was minimal when injected at 8 p.m. These significant differences in enzyme excretion as a function of injection time are correlated with the concentration of gentamicin in the urine and in the renal cortex.

Acetylglucosaminidase↗
PubMed1988

[Demonstration of seasonal variations of circadian rhythm in gentamicin-induced chrono-nephrotoxicity in rats].

The present study investigates the chronobiological approach of the gentamicin-induced nephrotoxicity in rats treated with a single sublethal dose administered at different times of day and season of year. The nephrotoxicity is appreciated by gamma-glutamyl-transferase and alanine-amino-peptidase, two enzymes of the brush border cells and N-acetyl-beta-D-glucosaminidase, a lysosomal enzyme. These excretions peak out at 8 p.m. and reach a through at 8 a.m. for the experimentation in january-february. In contrast, for the experimentation in June-July, we evidence gamma-glutamyl-transferase and alanine aminopeptidase excretion increased at 2 p.m. and decreased at 8 p.m. So, we evidence with gentamicin not only a circadian but also a seasonal susceptibility in rats.

Acetylglucosaminidase↗
PubMed1987

Comparison of the anti-inflammatory activity of sodium acexamate and zinc acexamate in healing skin wounds in rabbits.

After obtaining an abscess on the inner thigh of rabbits, the resulting inflammatory area was treated with sodium acexamate and zinc acexamate (0.5 ml s.c. of a 7% w/v solution). All animals received labeled leukocytes (111In, 1 mCi, i.v.). The hyperfixation was measured by comparing the inflammatory areas. In the group treated with zinc acexamate, the regression of inflammation was highly significant (p less than 0.001) in comparison with the other groups. These results emphasize the importance of combining zinc with acexamic acid for healing skin wounds.

Aminocaproates↗
PubMed1987

Inhibition of human polymorphonuclear leukocytes phagocytosis and protein-kinase-C activity by low pH concentrations.

PMN leukocytes from circulating blood, were investigated using the following parameters: chemiluminescence, superoxide generation, exocytic degranulation, lactoferrin, myeloperoxydase and protein-kinase-C activities. The results did not allow to point out any significative discrepancy between samples collected from either patients suffering of periodontal disease or healthy individuals. However, the phagocytic ability (as measured by light emission and superoxide production) was found to be severely inhibited in both instances, when PMN leukocytes were incubated in the presence of succinic acid. Similarly, protein-kinase-C activity in these cells, collapsed when the pH was brought down to 5.5. These data and the available literature indicate that pH decrease as well as succinic acid release in the crevicular fluid, may play a role in the pathogeny of chronic periodontitis in adults.

Acid Phosphatase↗