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Biomedical subjects

D A Preston

Publications and source records attributed to D A Preston.

9 recordsLinked to original sources
PubMed1979

Summary of laboratory studies on the antibacterial activity of cefaclor.

Laboratory aspects of cefaclor, a new orally-effective cephalosporin antibiotic, are summarized. On the basis of data from a variety of studies, the useful antibacterial spectrum of cefaclor is shown to include all classes of bacteria that are generally susceptible to cephalothin and cephalexin. Cefaclor has a significant potency advantage over cephalexin against many Enterobacteriaceae, Haemophilus sp. and Streptococcus pneumoniae. Bacteria that are susceptible to cefaclor are killed by concentrations at or near the inhibitory concentration. In vitro enzymatic hydrolysis experiments have shown that cefaclor is a relatively good substrate for several beta-lactamases. Orally administered cefaclor is effective in protection of mice from the lethal effects of intraperitoneal challenges with cefaclor-susceptible bacteria. The chemical instability of cefaclor, test medium composition and inoculum density influence the results of in vitro susceptibility tests with cefaclor. Methods for routine susceptibility testing are described.

Animals↗
PubMed1979

Orally active esters of cephalosporin antibiotics. 3. Synthesis and biological properties of aminoacyloxymethyl esters of 7-[D(-)-mandelamido]-3-[[(1-methyl-1H-tetrazol-5-yl)thio]methyl]-3-cephem-4-carboxylic acid.

The synthesis of six amino acid acyloxymethyl esters of cefamandole (1), a semisynthetic broad-spectrum cephalosporin antibiotic, is described. These esters were examined as potentially useful orally active antibiotic prodrugs. When tested for oral efficacy against Streptococcus pyogenes C203 in mouse protection tests, the esters were not notably more active than lithium cefamandole. Further studies demonstrated that significant blood and urine levels of 1 were not obtained after dosing 2a, 2b, and 2f orally at 17 mg/kg in mice. A study of the stability to chemical hydrolysis and the possible relationship of hydrolysis to the lack of oral absorption of these esters is also presented.

Administration, Oral↗
PubMed1979

Alcohol consumption and the incidence of violent crime.

The incidence of violent crime in an industrialized area of Ontario was positively correlated with sales of alcoholic beverages to establishments licensed to serve them on premises and negatively correlated with mean income and percentage of owner-occupied dwellings.

Alcohol Drinking↗
PubMed1979

Summary of laboratory studies on the antibacterial activity of cefaclor.

Laboratory aspects of cefaclor, a new orally-effective cephalosporin antibiotic, are summarized. On the basis of data from a variety of studies, the useful antibacterial spectrum of cefaclor is shown to include all classes of bacteria that are generally susceptible to cephalothin and cephalexin. Against many Enterobacteriaceae, Haemophilus sp. and Streptococcus pneumoniae, cefaclor has a significant potency advantage over cephalexin. Bacteria that are susceptible to cefaclor are killed by concentrations at or near the inhibitory concentration. In vitro enzymatic hydrolysis experiments have shown that cefaclor is a relatively good substrate for several beta-lactamases. Orally administered cefaclor is effective in protection of mice from the lethal effects of intraperitoneal challenges with cefaclor-susceptible bacteria. The chemical instability of cefaclor, test medium composition and inoculum density influence the results of in vitro susceptibility tests with cefaclor. Methods for routine susceptibility testing are described.

Animals↗
PubMed1979

The effect of constructive coercion on the rehabilitative process. A study of the employed alcoholics in an alcoholism treatment program.

Two groups of employed men in an alcoholic rehabilitation program--one referred through an organized policy of constructive coercion and the other volunteer--were compared to test the efficacy of constructive coercion in the rehabilitation process. It was found that the patients referred by constructive coercion were younger, had fewer psychosocial problems, had a higher percentage who were abstinent and had higher rates of compliance with follow-up. A policy of constructive coercion allows earlier identification of workers with alcohol problems and improves the chances for a positive treatment outcome.

Adult↗
PubMed1977

Delineation of the relative antibacterial activity of cefamandole and cefamandole nafate.

By conventional laboratory evaluation procedures, the in vitro antibacterial activities of cefamandole and its O-formyl ester, cefamandole nafate, appear virtually identical. When the activities of these two compounds were examined for their ability to lyse log-phase cultures of susceptible bacteria, however, cefamandole was found to be about 10 times more active than cefamandole nafate. Cefamandole nafate was shown to be rapidly converted to cefamandole in bacteriological media, with a half-life of less than 1 h at a pH of 7.0 or above. At pH 6.0, in log-phase inhibition experiments, however, cefamandole nafate is more stable, allowing delineation of the activity between cefamandole and cefamandole nafate. The efficacy of cefamandole was identical to that of cefamandole nafate in treating experimental animal infections, indicating that rapid conversion of cefamandole nafate to cefamandole occurs in vivo.

Animals↗
PubMed1976

Evaluation of antibiotic efficacy using electron microscopy: morphological effects of guanylureido cephalosporin, chlorobenzoylureido cephalosporin, BL-P1654, and carbenicillin on Pseudomonas aeruginosa.

The response of Pseudomonas aeruginosa to carbenicillin, BL-P1654, and two cephalosporins (112384 and 112883) was evaluated by minimal inhibitory concentration determinations, [(14)C]leucine uptake studies, morphological studies of colonial growth, and mouse intraperitoneal inoculations. Spheroplast formation and bacterial lysis were not the early response; instead, cell division was inhibited and long filaments were formed. Spheroplast formation and bacterial lysis were not observed in the first 7 h of incubation in minimal inhibitory concentrations of antibiotic.

Animals↗
PubMed1976

Evaluation of antibiotic efficacy using electron microscopy: morphological effects of guanylureido cephalosporin, BL-P1654, and carbenicillin on Escherichia coli.

Early response of Escherichia coli to minimal inhibitory concentrations of 112883, BL-P1654, and carbenicillin was determined by [(14)C]leucine uptake and scanning electron microscopy morphology studies. [(14)C]leucine uptake was inhibited later by carbenicillin than by BL-P1654 or 112883. Cellular swelling at 30 min, septal region swelling, and lysis were the progressive morphological changes with BL-P1654 and 112883. Carbenicillin-treated cells showed septal region swelling, beaded chains, and lysis.

Carbenicillin↗