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Biomedical subjects

A Pascual

Publications and source records attributed to A Pascual.

At least 127 records · Page 7Linked to original sources
PubMed1993

Effect of polyurethane catheters and bacterial biofilms on the in-vitro activity of antimicrobials against Staphylococcus epidermidis.

The effect of two polyurethane ['Cavafix Certo' (CAV); 'Viacath' (VIA)] catheters on the in-vitro activity of amikacin (AN), clindamycin (CM), cloxacillin (CX), ciprofloxacin (CIP), vancomycin (VA), teicoplanin (TEI) and daptomycin (DAP) against slime producing and non-producing Staphylococcus epidermidis strains was determined using a microdilution assay. None of the antimicrobial agents was significantly affected in the presence of the catheters. The susceptibility of S. epidermidis attached to CAV and VIA catheters was also evaluated. Minimum inhibitory concentration (MIC) values were similar when planktonic and attached bacteria were compared. Minimum bactericidal concentrations (MBCs) markedly increased in the presence of 6 and 48 h bacterial biofilms. These increases in MBC values occurred when either slime producing or non-producing strains were used, and in most cases were higher for CAV catheters than for VIA catheters. This phenomenon was shown not to be due to differences in bacterial adherence. It is concluded that the in-vitro bactericidal activity of certain antimicrobials markedly decreased when bacteria adhered to plastic catheters, but this effect could have been dependent partially on the nature of the catheters.

Anti-Bacterial Agents↗
PubMed1993

Nicotinamide analogs and DNA-damaging agents deplete thyroid hormone receptor and c-erbA mRNA levels in pituitary GH1 cells.

Incubation of pituitary GH1 cells with N'-methylnicotinamide, nicotinamide and 3-acetylpyridine which inhibit nuclear ADP-ribosylation and/or the cellular concentration of its substrate NAD+ reduced the amount of nuclear thyroid hormone receptors in a time- and dose-dependent manner without altering the affinity of the receptors for the hormone. A transient activation of poly(ADP-ribose)polymerase by methyl methanesulfonate, ultraviolet irradiation or spermine caused a rapid depletion of cellular NAD+ content and was followed by a strong inhibition of ADP-ribosylation. These agents also produced a very rapid and marked reduction of receptor numbers. The decrease of receptors caused by the different compounds is not secondary to a generalized inhibition of protein synthesis or to an alteration in hormone availability. The abundance of c-erbA alpha and beta mRNAs, which encode thyroid hormone receptors, was reduced in cells treated with the compounds that decrease receptor number, thus suggesting that this effect is caused by a decrease in the expression of c-erbA genes.

Adenosine Diphosphate Ribose↗
PubMed1993

Late onset Papillon-Lefèvre syndrome? A chromosomic, neutrophil function and microbiological study.

We had the opportunity to study a family with one of the most destructive forms of periodontal disease known, the Papillon-Lefèvre syndrome. The parents had no consanguinity and were not affected, and were therefore to be considered carriers of the disease. 2 sisters, the eldest and youngest, showed periodontal breakdown and hyperkeratotic skin lesions, but their deciduous dentition was not affected. 2 brothers had skin lesions only and another brother and sister were healthy. Furthermore, 2 babies died at birth one after a 9-month pregnancy and the other after a 6-month pregnancy, and the mother also suffered 3 miscarriages. For 4 years, we studied the family: in the case of both sisters, mechanical periodontal treatment and antibiotics were unable to control the disease. In the chromosomic study of the 2 sisters affected, the GTG banding technique found no trace of anomalies in the cells analyzed, whose chromosomic formation was 46,XX. Before treatment, the chemotaxis of the PMN, the phagocytosis of opsonized Staphylococcus aureus, and production of superoxide radicals by PMN was significantly impaired in both sisters. Despite scaling and root planing, the periodontal lesions still progressed, but the PMN functions evaluated were now normal in both sisters. An orally asymptomatic but dermatologically affected brother showed no significant defect in the phagocytic activity and the production of superoxide radicals.

Adult↗
PubMed1993

Uptake and intracellular activity of fluconazole in human polymorphonuclear leukocytes.

The penetration of fluconazole into human polymorphonuclear leukocytes (PMNs) and tissue culture epithelial cells (McCoy) was evaluated. At different extracellular concentrations (0.5 to 10 mg/liter), fluconazole reached cell-associated concentrations greater than the extracellular ones in either human PMNs (intracellular concentration to extracellular concentration ratio, > or = 2.2) or McCoy cells (intracellular concentration to extracellular concentration ratio, > or = 1.3). The uptake of fluconazole by PMNs was rapid and reversible but was not energy dependent. The intracellular penetration of fluconazole was not affected by environmental pH or temperature. Ingestion of opsonized zymosan and opsonized Candida albicans did not significantly increase the amount of PMN-associated fluconazole. At therapeutic extracellular concentrations, the intracellular activity of fluconazole against C. albicans in PMNs was significantly lower than that of amphotericin B. It was concluded that fluconazole reaches high intracellular concentrations within PMNs but shows moderate activity against intracellular C. albicans in vitro.

Amphotericin B↗
PubMed1992

Comparative penetration of lomefloxacin and other quinolones into human phagocytes.

The penetration of lomefloxacin into human polymorphonuclear leukocytes (PMNs) and peritoneal macrophages (PMphis) was evaluated using a fluorometric assay. Lomefloxacin reached high intracellular concentrations into PMNs at extracellular concentrations of 2 and 5 mg/L (cellular to extracellular concentration ratio [C/E] greater than 4). At the same conditions (20 minutes incubation; extracellular concentrations: 2 mg/L) lomefloxacin uptake by human PMNs (C/E: 7.9 +/- 2.6) was slightly higher than those of norfloxacin (C/E 5.1 +/- 1.8), ciprofloxacin (C/E: 6.2 +/- 2.0), and ofloxacin (C/E 7.1 +/- 2.6). Lomefloxacin penetration into human PMphis was significantly lower than PMNs but still with C/E ratios greater than 4. Entry of lomefloxacin into phagocytes was not affected by cell viability but was environmental-temperature dependent. It is concluded that lomefloxacin and the other quinolones evaluated reach high intracellular concentrations in human phagocytic cells.

Analysis of Variance↗
PubMed1992

Effect of several antimicrobial agents on ciprofloxacin uptake by human neutrophils.

The effect of antimicrobial agent active against anaerobes, gram-positive cocci and fungi on the uptake of ciprofloxacin by human neutrophils (PMNs) was evaluated. In the presence of therapeutic extracellular concentrations of these agents, ciprofloxacin reached high intracellular concentrations [cellular-to-extracellular ratio (C/E) greater than or equal to 2.9], this value being higher in the presence of amphotericin B (C/E 6.3 +/- 0.9). The intracellular penetration of ciprofloxacin was higher when PMNs were stimulated with opsonized zymosan (C/E greater than or equal to 5.6). In summary, none of the antimicrobial agents tested significantly impaired the uptake of ciprofloxacin by human PMNs.

Anti-Infective Agents↗
PubMed1992

Entry of lomefloxacin and temafloxacin into human neutrophils, peritoneal macrophages, and tissue culture cells.

The uptake of lomefloxacin (difluoroquinolone) and temafloxacin (trifluoroquinolone) by human polymorphonuclear leukocytes (PMNs), peritoneal macrophages (PM phis), and two tissue culture cells (McCoy and Vero) was measured by a fluorometric assay. Both antimicrobials reached high intracellular concentrations in PMNs [cellular to extracellular ratio (C/E) greater than 4], in PM phis (C/E greater than 3) and lower in tissue culture cells (C/E greater than 1) at an extracellular concentration of 5 mg/L. Lomefloxacin uptake by PMNs was more rapid than that of temafloxacin. Entry of both quinolones into PMNs was environmental temperature-dependent, but not affected by cell viability. Ingestion of opsonized Staphylococcus aureus did not affect the ability of PMNs to concentrate these antimicrobials. Ingestion of opsonized zymosan or stimulation with phorbol myristate acetate significantly increased the PMN association of both quinolones, this effect being particularly marked with temafloxacin. It is concluded that both lomefloxacin and temafloxacin are markedly concentrated within human phagocytes and tissue culture cells, although this phenomenon is not dependent on the degree of fluorination of the molecule.

Animals↗
PubMed1992

Uptake and intracellular activity of sparfloxacin in human polymorphonuclear leukocytes and tissue culture cells.

The penetration of sparfloxacin into human neutrophils (PMN) and different tissue culture cells (HEp-2 and McCoy) was evaluated. The cellular to extracellular concentration ratios (C/E) of sparfloxacin were always higher than 4 at extracellular concentrations ranging from 0.5 to 25 mg/liter. The uptake of sparfloxacin by PMN was rapid, nonsaturable, reversible, not energy dependent, and significantly reduced at pH 8. The penetration of this agent into PMN was similar when viable and Formalin-killed cells were used and was not affected by environmental temperature. Ingestion of opsonized zymosan significantly increased the amount of PMN-associated sparfloxacin. Sparfloxacin at a concentration of 0.5 mg induced a significant reduction in the survival of intracellular Staphylococcus aureus. It is concluded that sparfloxacin reaches intracellular concentrations within leukocytic cells much higher than extracellular concentrations, while remaining active intracellularly.

Anti-Infective Agents↗
PubMed1992

The effect of stainless steel, cobalt-chromium, titanium alloy, and titanium on the respiratory burst activity of human polymorphonuclear leukocytes.

Although infection is a serious complication associated with the use of orthopedic prosthetic implants, the impact of the metal used in these devices on host defense is poorly understood. The authors investigated the effect of stainless steel, titanium, titanium alloy, and cobalt-chromium alloy on the respiratory burst of polymorphonuclear leukocytes (PMN), a vital component of bactericidal activity. In the presence of stainless steel powder or supernatants obtained from the incubation of stainless steel in buffer, superoxide production by PMN was significantly impaired. Titanium, titanium alloy, and cobalt-chrome alloy had no significant effect on superoxide production. Nickel and chromium, the only metal ions detectable in the stainless steel supernatant, did not impair superoxide production when tested at concentrations similar to those found in the supernatant. Inhibition of PMN superoxide production may play a role in the establishment and persistence of stainless steel device-related infections.

Cell Survival↗
PubMed1992

[Effect of cefepime on adhesion and phagocytosis of Pseudomonas aeruginosa].

BACKGROUND: We studied the effect of subinhibitory concentrations of cefepime on cell surface hydrophobicity expression and adherence to epithelial cells of Pseudomonas aeruginosa. We also evaluated the effect of this drug on the interaction between Pseudomonas aeruginosa and human polymorphonuclear leukocytes. METHODS: The bacterial cell surface hydrophobicity was tested on a biphasic system (water/p-xylene). The bacterial adherence to epithelial cells as well as the phagocytosis of Pseudomonas aeruginosa was studied using radiometric techniques. The superoxide production was evaluated by means of cytochrome C reduction method. RESULTS: Pre-incubation of a non mucoid Pseudomonas aeruginosa strain with a 0.25 MIC value of cefepime produces a reduction in the adherence of this microorganism to epithelial cells, but without modifying the surface hydrophobicity. Pre-incubation of a mucoid and a non mucoid P. aeruginosa strain with a 0.25 MIC value of cefepime reduces its phagocytosis by polymorphonuclear leukocytes. The preincubation polymorphonuclear leukocytes with cefepime (1, 10, and 100 mg/ml) did not influence the phagocytosis of Pseudomonas aeruginosa nor the bactericidal mechanisms of PMN (superoxide production). At therapeutic concentrations, cefepime showed intracellular activity against P. aeruginosa in human polymorphonuclear leukocytes. CONCLUSIONS: The incubation of Pseudomonas aeruginosa with sub-MIC inhibit its adherence to epithelial cells and its intake by human polymorphonuclear leukocytes. At therapeutic concentrations, cefepime did not affect the bactericidal mechanisms of polymorphonuclear leukocytes, and shows a significant intracellular activity against P. aeruginosa.

Bacterial Adhesion↗
PubMed1992

[Evaluation of 5 methods for the diagnosis of infections by respiratory syncytial virus].

BACKGROUND: To compare and evaluate four different rapid methods of respiratory syncytial virus antigen detection with the isolation of the virus in cell culture. METHOD: Ninety-eight nasopharyngeal swabs were studied, for respiratory syncytial virus isolation in Hep-2 cell line and for RSV antigen detection using direct immunofluorescence and three ELISA methods: Abbot RSV EIA (ELISA-1), RSV Antigen Detection System (ELISA-2) and Directigen RSV (Directigen). RESULTS: Of all 98 samples studied using the five mentioned methods, 42 (43%) were positive for respiratory syncytial virus. The most sensitive methods were ELISA-1 (82%) and immunofluorescence (82%). The most specific ones were direct immunofluorescence (86%) and Directigen (84%). The higher percentage of concordant positive results with respiratory syncytial virus culture were direct immunofluorescence (84%) and Directigen (82%). CONCLUSIONS: Rapid diagnostic methods for respiratory syncytial virus infection can not substitute the isolation method using cell line culture. We believe that respiratory syncytial virus isolation in cell culture combined direct with direct immunofluorescence or Directigen methods are the first choice diagnostic techniques for achieve a higher number of positive results in respiratory syncytial virus infected patients.

Antigens, Viral↗
PubMed1991

Retinoic acid decreases thyroid hormone receptor expression in pituitary GH1 cells.

Retinoic acid produced a time and dose-dependent depletion of thyroid hormone receptors in GH1 cells without modifying their affinity for triiodothyronine (T3). A maximal decrease (50-70%) was obtained after 24-48 h incubation with 5-10 microM retinoic acid. Treatment with 0.8 nM T3 for 24 h caused a similar reduction and did not potentiate the decrease produced by these concentrations of retinoic acid. However, the combination of sub-maximally effective doses of both ligands had an additive effect on receptor levels. The reduction of receptor caused by retinoic acid is accompanied by a decreased expression of c-erbA alpha 1 and alpha 2 mRNAs, but the retinoid did not reduce the abundance of c-erbA beta mRNA. In contrast, T3 decreased the levels of both alpha and beta transcripts.

Animals↗
PubMed1991

Influence of thyroid hormone on ADP-ribosylation of nuclear proteins in cultured GH1 cells.

We present evidence that T3 can alter the ADP-ribosylation of chromatin associated proteins. Nuclei from GH1 cells were incubated with [adenylate-32P]NAD and the radioactivity incorporated into histone and non-histone proteins was quantitated and analyzed by gel electrophoresis and autoradiography. Incubation of GH1 cells for 24 h with T3 lowered by 40-70% the [32P]ADP-ribose incorporated into nuclear proteins. However, incubation for 3 h with T3 resulted in a stimulation instead of a decrease of in vitro [32P]ADP-ribose incorporation. The major ADP-ribosylated component electrophoresed as a 120,000 molecular mass non-histone protein, and radiolabeled histones were also observed. The same protein species were observed for all the experimental groups and T3 affected the extent of ADP-ribosylation but did not alter the sedimentation of the [32P]ADP-ribosylated components excised from chromatin after micrococcal nuclease digestion.

Adenosine Diphosphate Ribose↗
PubMed1991

Fluorometric and high-performance liquid chromatographic measurement of quinolone uptake by human neutrophils.

A fluorometric assay, based on the natural fluorescence of the quinolone nucleus, and high-performance liquid chromatography (HPLC) were compared to determine the penetration of six quinolones (norfloxacin, ciprofloxacin, ofloxacin, fleroxacin, lomefloxacin and temafloxacin) into human polymorphonuclear neutrophils (PMN). Intracellular concentrations after 20 min incubation of the cells with 10 and 25 mg/l were three or more times higher than the extracellular ones. There were no statistical differences between the two methods. At lower extracellular concentrations (2 and 5 mg/l) the intracellular levels of all the quinolones tested were undetectable by HPLC. Fluorometry is a useful method for determining the intracellular penetration of quinolones. The usefulness of HPLC, however, is questionable since it requires great volumes of cells and extracellular concentrations much higher than the therapeutic ones.

Anti-Infective Agents↗
PubMed1991

Evaluation of a DNA probe of plasmid origin for the detection of Chlamydia trachomatis in cultures and clinical specimens.

This study evaluates five cryptic plasmid-derived DNA probes in a 4-h slot-blot hybridization assay for the detection of Chlamydia trachomatis in cultures and clinical specimens. The probes, consisting of either the entire cloned 7.5 kbp cryptic plasmid pSE8 or one of four Hin dIII/Eco RI fragments measuring 710, 1055, 710, and 500 bp, respectively, were labelled with Photoprobe biotin. The probe was detected using a streptavidin-alkaline phosphatase conjugate followed by addition of BCIP and NBT. The sensitivity of the assay, using 25 ng of probe DNA, ranged from 50 pg (with the entire plasmid as probe) to 5 ng (with the 500 bp fragment as probe). A total of 103 reference strains of Chlamydia trachomatis and other bacteria were tested for reactivity with the probes. All 18 reference strains of C. trachomatis hybridized with the probes. None of the DNA from the heterologous organisms tested was found to hybridize with any of the probes. A total of 174 samples taken from patients visiting the STD clinic at the University Hospital, University of Seville were used in the study. The overall sensitivity of the assay, using the 710 bp biotinylated probe was 94.5% compared to culture while the specificity was 97.5%. Positive and negative predictive values were 96.5% and 97.5%, respectively. It appears that the plasmid-derived probes used in this study could serve as useful tools for the rapid and specific detection of Chlamydia trachomatis in cell cultures and clinical specimens.

Bacteria↗