Biomedical subjects
Publications and source records attributed to J R O'Connor.
A series of N,N'-polyalkylenebis[4-(substituted-amino)pyridines] has been prepared, and members have been evaluated as potential anti-dental plaque agents. From among the most active members of the series, one compound, N,N'-[1,10-decanediyldi-1(4H)-pyridinyl-4-ylidene]bis(1-octanam ine) dihydrochloride, octenidine, was selected as a candidate for clinical study.
The antibacterial activity of octenidine dihydrochloride (WIN 41464-2) against intact preformed in vitro plaques of four indigenous oral plaque-forming microorganisms, Streptococcus mutans, Streptococcus sanguis, Actinomyces viscosus, and Actinomyces naeslundii, was studied. Both absolute (plaque bactericidal index) and relative (chlorhexidine coefficient) indices of antiplaque efficacy were established. Octenidine dihydrochloride compared favorably with chlorhexidine digluconate with respect to overall antiplaque potency in this in vitro plaque bactericidal model. These data indicate that prudent selection of treatment concentration and duration and frequency of exposure should provide an effective means to aid in controlling dental caries and Actinomyces-associated disease in vivo.
A series of bispyridines were examined for their bactericidal activities against in vitro, preformed, pure-culture plaques of selected oral plaque-forming bacteria. The antimicrobial activities of these agents were examined in relation to their molecular configurations. These studies demonstrated that the length of the interpyridine polymethylene group bridge and the length of the alkyl side chain were important determinants of antiplaque and antimicrobial efficacy. The most potent compounds of the bispyridine series were studied to determine the minimal conditions (concentration, duration, and frequency) of treatment required for likely clinical efficacy.
The syntheses of 1-(arylamino)-1H-pyrroles and 4-(1H-pyrrol-1-ylimino)-2-5-cyclohexadienes are described. Several of these compounds express in vitro antibacterial activity or can be metabolized to show in vitro antibacterial activity, and a few examples have shown efficacy against tuberculosis in mice. One compound, N,N'-(2,5-cyclohexadiene-1,4-diylidene)bis-1H-pyrrol-1-amine, is completely effective at 6.25 mg/kg against Mycobacterium tuberculosis H37Rv.
The antimicrobial activity of rosoxacin, a new quinoline antibacterial compound, was determined against the causative organisms of three sexually transmitted diseases. Rosoxacin demonstrated a high degree of activity against Neisseria gonorrhoeae clinical isolates, with the minimal inhibitory concentrations for 50% of these being 0.03 microgram/ml. The corresponding minimal inhibitory concentrations for penicillin, ampicillin, tetracycline, and spectinomycin were 0.25 U/ml, 0.125 microgram/ml, 0.25 microgram/ml, and 16 microgram/ml, respectively. Eleven strains of Chlamydia trachomatis were inhibited by 5 microgram of rosoxacin per ml, and each of seven Ureaplasma urealyticum strains was inhibited by 2 to 8 microgram of rosoxacin per ml. The results of these susceptibility studies, coupled with those of an earlier evaluation of the pharmacokinetics of rosoxacin, provide support for extending or undertaking clinical evaluations of this compound against infections with N. gonorrhoeae, C. trachomatis, and U. urealyticum.
Win 42122-2 is a new aminoglycoside antibiotic obtained from a mutant strain of Micromonospora purpurea. In vitro and in vivo comparisons of Win 42122-2 with gentamicin and amikacin revealed that Win 42122-2 generally was less active than gentamicin against Pseudomonas and many Enterobacteriacae, especially Klebsiella and indole-negative Proteus. Against most gentamicin-susceptible isolates, Win 42122-2 was more active than amikacin. Gentamicin-resistant clinical isolates were usually resistant to Win 42122-2, although it was active against certain gentamicin-resistant organisms, depending upon the aminoglycoside-modifying enzymes harbored by the organism. However, Win 42122-2 was markedly less toxic than gentamicin in subacute nephrotoxicity studies in rats, ototoxicity experiments in guinea pigs, and ataxia determinations in cats. This series of antibacterial determinations and toxicity evaluations indicated that the reduced toxicity of the antibiotic may be sufficient to provide an improved therapeutic ratio over gentamicin and other aminoglycosides, even though Win 42122-2 is less potent than gentamicin against some bacteria.
A new polycrystalline form of hydroxylapatite, CHA, has been shown to closely mimic dental enamel, in vitro, in regard to rate and degree of plaque formation and effectiveness of antiplaque drugs. The material has successfully been exploited as a standardized hydroxylapatite plaque growth substrate in conjuntion with a mass antidental plaque drug screening program.
The use of computer technology is becoming increasingly important in the handling of medical records. The cardiology data system used at The Hospital for Sick Children has greatly simplified the review and analysis of patient records. The methods of capturing data are logical and straightforward and have assisted fellows, residents and students in learning the systematic approach to the diagnosis of heart disease in children. The review of particular defects conducted as a research project has often led to further studies which have made important contributions to the knowledge of heart disease in childhood.
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