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Biomedical subjects

G Ravagnan

Publications and source records attributed to G Ravagnan.

At least 73 records · Page 4Linked to original sources
PubMed1988

Transglutaminase in cell proliferation and transformation.

Transglutaminase (TGase) activity was reduced in intact mitogen-stimulated human peripheral blood lymphocytes (PBL) when compared to intact resting PBL. Moreover, a treatment of the same quiescent immunocompetent cells with purified liver TGase and Ca2+ completely suppressed the mitogen-induced blast transformation. A decrease in TGase activity in neoplastically transformed seminal vesicle epithelial cells with respect to their normal parent counterpart was also observed. Our data support the notion of a possible implication of TGase in cell proliferation and transformation.

Animals↗
PubMed1987

A protein family immunorelated to a sperm-binding protein and its regulation in human semen.

In human seminal plasma a family of proteins that is immunologically related to the RSV-IV protein secreted under androgen control from the epithelium of the rat seminal vesicles was detected by a radioimmunoassay. Evidence for the origin of these antigens from human seminal vesicle is presented. Quantitative measurements of this family of proteins were performed in men with low levels of serum testosterone (idiopathic hypogonadotropic hypogonadism) and in individuals having serum testosterone in the normal range of values but carrying sex chromosome aberrations (Klinefelter's syndrome). In the first case we have found a marked decrease in the total amount of the RSV-IV-related proteins. An increase of about 40% in the total amount of these antigens was obtained in these subjects by gonadotropin treatment. A decreased amount of these proteins was also detected in the subjects affected by Klinefelter's syndrome. The possibility that some factor(s) under genetic control is involved, in addition to testosterone, in the regulation of this family of proteins is discussed.

Adult↗
PubMed1987

Comparative in vitro activities of 13 antimicrobial agents against Morganella-Proteus-Providencia group bacteria from urinary tract infections.

We examined 741 urinary tract isolates of the Morganella-Proteus-Providencia group, including the recently defined species Proteus penneri, for susceptibilities to aminoglycosides, semisynthetic penicillins, and cephalosporins. The data emphasize the importance of identification to the species level on the basis of marked species differences in patterns of susceptibility.

Anti-Bacterial Agents↗
PubMed1987

Preliminary studies on the effect of glutathione S-transferase from Providencia stuartii on the antimicrobial activity of different antibiotics.

Glutathione S-transferase has been isolated and purified from a Providencia stuartii CH 114 strain. The effect of the enzyme on the antimicrobial activity of amikacin, cefotaxime, cephalexin, ampicillin, nalidixic acid, and ofloxacin was tested. The efficiency of all antibiotics tested, except nalidixic acid and ofloxacin, is relevantly decreased by the presence of glutathione S-transferase in the medium culture, as proved by the increased value of MIC. The effect of glutathione S-transferase on the drugs is not significantly affected by the addition of exogenous glutathione. The possible mechanism of action of the enzyme is also discussed.

Anti-Bacterial Agents↗
PubMed1987

Adhesive properties of Proteus genus related to antimicrobial agents resistance.

The in vitro attachment of 49 Proteus spp. to human urinary tract epithelial cells was determined. The antibacterial spectrum to all species of the Proteus isolates from hospitalized patients was measured against the most common antibiotics (Amikacin, Cefamandole, Cefoxitin, Ceftriaxone, Cephalothin, Kanamycin, Nalidixic acid, Oxolinic acid, Pipemidic acid, Piromidic acid, Tobramycin). 18 of them were multiresistant and the other 31 expressed susceptibility to the above antibiotics. Bacterial adherence to uroepithelial cells was studied in relation to susceptibility on antibiotics. The mean of bacteria per cell for the 31 strains grouped as susceptible was 20.2 and for the 18 strains grouped as resistant the mean was 55.1. Our results demonstrate a significant relationship between bacterial adhesion and antibiotic susceptibility pattern by Student's t test (P less than 0.01).

Adult↗
PubMed1986

Comparative "in vitro" activity of ciprofloxacin (Bay o9867) and other antimicrobial agents against urinary bacterial isolates.

Ciprofloxacin (Bay o9867) is a new quinolone derivative. Its activity against 537 urinary bacterial isolates was compared with those of ampicillin, amikacin, carbenicillin, cefazolin, cefotaxime, cefoxitin, ceftazidime, nalidixic and oxolinic acids, norfloxacin, trimethoprim, and other antimicrobial agents, when appropriate. It inhibited 90% of Citrobacter freundii, Enterobacter spp., E. coli, Klebsiella spp., Proteus spp., and Serratia spp. at 0.78 microgram/ml. The majority of Pseudomonas aeruginosa, including gentamicin-resistant strains, was inhibited by 0.78 microgram/ml. The minimal inhibitory concentrations of ciprofloxacin for 90% of Staphylococcus aureus, including methicillin-resistant strains, and Streptococcus faecalis were 0.78 microgram/ml and 1.56 micrograms/ml respectively. Ciprofloxacin inhibited organisms resistant to ampicillin, carbenicillin, cefazolin, nalidixic and oxolinic acids, and trimethoprim. Ciprofloxacin was less active in urine at pH 5.8 than in broth, but serum did not decrease minimal inhibitory concentrations or minimal bactericidal concentrations. There was no major difference between minimal inhibitory concentrations and minimal bactericidal concentrations. Spontaneous rates of mutation to resistance of representative urinary bacteria were studied. For ciprofloxacin these rates ranged from 8.2 X 10(-9) to 1.5 X 10(-11).

Anti-Bacterial Agents↗
PubMed1985

In vitro synergistic activity of some chinolinic compounds combined with beta-lactam antibiotics against gram-positive and gram-negative clinical isolates.

The antimicrobial activities of nalidixic acid-cephalexin (ratio 1:1) and cinoxacin-cefadroxil (ratio 1:2) combinations have been evaluated against 396 clinical isolates; many of them were nalidixic acid- or cinoxacin-resistant organisms (MIC greater than or equal to 100 micrograms/ml). We have also tested the nalidixic acid-amoxicillin combination (ratio 1:1) against 225 amoxicillin-resistant bacterial strains (MIC greater than or equal to 800 micrograms/ml). Synergy was found for 62-70% of the Enterobacteriaceae and nonfermenter bacilli tested and for 85-92% of the gram-positive bacterial strains. The 225 clinical isolates resistant to amoxicillin (MIC greater than or equal to 800 micrograms/ml) were synergistically inhibited by the nalidixic acid-amoxicillin combination.

Amoxicillin↗
PubMed1985

Inhibition of conjugal transfer by new quinolinic compounds.

We found that nalidixic acid is a good inhibitor of conjugal transfer of R-plasmids and that related compounds show the same properties. We investigated recently synthetized quinolinic molecules. The inhibition was not due to bacterial activity of the compounds against donors, recipients or R transconjugants; in fact, the drug concentrations were twice or four times lower than the M.I.C. values. The new molecules showed a marked inhibitory effect in various R-mating experiments.

4-Quinolones↗
PubMed1984

In vitro interaction of penicillins and cephalosporins with human placenta GSH S-transferase.

Human purified placenta GSH S-transferase was generally inhibited by penicillins and cephalosporins to a different extent. Among the seven penicillins tested the dihalogenate dicloxacillin and flucloxacillin were the strongest inhibitors. All cephalosporins showed competitive inhibition for the electrophilic substrate, while penicillins acted as non-competitive inhibitors. Exposure of the enzyme to cephalosporins led to the loss of the catalytic activity. Addition of reduced glutathione in the incubation system would induce the formation of a conformational state of the enzyme which prevents cephalosporins binding.

Cephalosporins↗
PubMed1984

In vitro synergism of nalidixic acid with other broad spectrum antibiotics.

In vitro studies of the activity of antibiotic combinations in the ratio 1:1: nalidixic acid plus cephaloridine, nalidixic acid plus kanamycin and nalidixic acid plus erythromycin were performed by using an agar dilution technique with Mueller-Hinton Agar. Of 156 Enterobacteriaceae tested, nalidixic acid plus cephaloridine were synergistic for 96 (61.5%) strains compared with 101 (64.7%) with nalidixic acid plus kanamycin (P less than 0.01) and 85 (54.5%) with nalidixic acid plus erythromycin (P less than 0.001). These data suggest these combinations as possible effective tools in clinical trials, especially directed toward high level resistant urinary tract pathogens.

Anti-Bacterial Agents↗
PubMed1981

[The production of enzymes inactivating various antibiotics obtained from Gram-negative bacteria recently isolated in the province of Chieti].

The Authors have studied the ability of producing enzymes blocking various antibiotics by 274 Gram-negative germs isolated in the years 1978-80 in the Province of Chieti (Italy). The results have showed that a high percentage of examined strains presents a polyresistance towards penicillins, cephalosporins, chloramphenicol and amino-glucosides producing in the same time beta-lactamase, acetyl-transferases and phospho-transferases.

Acetyltransferases↗
PubMed1980

[Evaluation of the antibacterial activity in vitro of various cephalosporins on different gram-negative bacterial species of recent clinical isolation].

The Authors have compared the antibacterial activity "in vitro" of new cephalosporines (cephuroxim, cephoxitin and cephaclor) with other cephalosporines having an action which is already known (cephaloridine, cephazoline and cephalexine) on the Gram-negative bacterial strains of recent clinical isolation. The results show that the cephalosporines of last generation, having in their molecular nucleus a methoximinic group, realize a greater antibacterial protection than those cephalosporines of antecedent preparation.

Cephalosporins↗
PubMed1977

Association of halogenated isoxazolylpenicillins with penicillinase-sensitive beta-lactam antibiotics. Microbiological evaluation on beta-lactamase-producing Enterobacteriaceae.

The validity of nonsimultaneous association of penicillinase-sensitive beta-lactam antibiotics with halogenated isoxazolylpenicillins was tested in various Enterobacteriaceae strains. With several bacterial strains, expecially if producers of beta-lactamase type IV, exposure of either the bacterial suspensions of the brothsupernatant to the isoxazolylpenicillins appears both in vivo and in vitro to reduce the extent of subsequent hydrolysis of penicillinase-sensitive beta-lactam antibiotics.

Animals↗