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Biomedical subjects

M G Newman

Publications and source records attributed to M G Newman.

At least 91 records · Page 5Linked to original sources
PubMed1982

Effect of Chinese and western antimicrobial agents on selected oral bacteria.

The susceptibility of selected oral bacteria, including suspected periodontopathogens, to a commonly employed Chinese herbal medicine Huang-chin (HC, Scutellaria baicalensis) was tested in vitro. The minimum inhibitory concentration (MIC) and minimum bactericidal concentrations (MBC) were determined. HC was also compared with tetracycline, alexidine, and stannous fluoride. HC decoction, at a concentration of 2%, was bacteriostatic in eight of 11 bacteria tested, but a concentration of 3.13% or greater was required for bactericidal effect. Among the tested bacteria, Bacteroides melaninogenicus ss intermedius was the most sensitive (MIC = 1.57%, MBC = 2%); Actinomyces viscosus was the least sensitive (MIC = 6.25%, MBC = 12.5%). Tetracycline, alexidine, and SnF2 were bactericidal in vitro in all bacteria tested at concentrations lower than those used clinically.

Bacteria↗
PubMed1982

A scanning electron microscopic study of leukocytes and their interaction with bacteria in human periodontitis.

Shape, size, topographical relationships, surface morphology, phagocytosis and locomotion were used to identify and study leukocytes in human cases of periodontitis. These cells were described in the following locations: in peripheral blood vessels adjacent to the pocket epithelium; gingival connective tissue; basement lamina; sectioned pocket epithelium; surface of pocket epithelium; junctional epithelium; and cementum surface. The interaction of leukocytes and bacteria was documented in the phases of recognition, attachment and engulfment of bacteria. Morphologic data suggesting the process of degranulation was also presented.

Bacteria↗
PubMed1982

Bacterial invasion of gingiva in advanced periodontitis in humans.

Using scanning electron microscopy, bacteria were found invading the epithelial wall of deep periodontal pockets in five out of eight cases. In one case, bacteria had reached the connective tissue. The following bacterial morphotypes were identified: cocci, short rods, filaments and spirochetes. A corncob-like formation with a few scattered spirochetes was found in one case between the junctional epithelial cells. Numerous cocci, rods and filaments were found in intercellular spaces of the epithelium in the lateral wall of the pocket and accumulating on the epithelial side of the basement lamina. Bacterial invasion of gingival tissue may have important pathogenic and therapeutic implications.

Aged↗
PubMed1981

Clinical and antimicrobial effect of stannous fluoride on periodontitis.

The antimicrobial effect of stannous fluoride (SnF2) on suspected pathogenic morphotypes of bacterial plaque in chronic periodontal disease was assessed. Alterations in morphological groups of subgingival and supragingival plaque bacteria from three diseased sites and one periodontally healthy site were determined by darkfield microscopy in 10 male patients with advanced periodontitis. In addition, clinical indices were also measured. The three diseased sites received either 1.64% SnF2, 0.4% SnF2 or sterile saline by subgingival irrigation. The healthy site received sterile saline only. The patients were seen weekly over a 10-week period and at each appointment bacterial sampling and clinical indices were measured. Results indicated that 1.64% SnF2 caused a dramatic and sustained decrease of subgingival motile bacteria and spirochetes following irrigation. By the sixth week these bacteria returned to 50% of their original concentration. Bleeding index scores, which were significantly reduced, correlated positively to the reduction in motile bacteria and spirochetes. Sites irrigated with 0.4% SnF2 also demonstrated a similar pattern of reduction of motile bacteria and spirochetes but without their total elimination and a more rapid return to original levels. In the diseased sites receiving sterile saline there was a decrease in motile bacteria and spirochetes, corresponding with saline irrigation, which rapidly returned to baseline levels. The healthy control sites were unchanged. Supragingival plaque index scores did not correlate with the bleeding index, motile bacteria and spirochetes, or with subgingival irrigation.

Adult↗
PubMed1981

Antimicrobial susceptibility of Capnocytophaga.

Capnocytophaga (Bacteroides ochraceus, Center for Disease Control biogroup DF-1) is associated with sepsis in granulocytopenic patients and is isolated in large numbers from the affected periodontal pockets in patients with juvenile periodontosis. The minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) of 17 antimicrobial agents for 13 strains of Capnocytophaga organisms were determined. In addition, the ratio of the MBC to the MIC for each antimicrobial agent was determined for each strain. At concentrations of 1 microgram/ml or less, penicillin, ampicillin, carbenicillin, erythromycin, and clindamycin killed 90% of the strains. At concentrations of 3.12 microgram/ml or less, tetracycline, metronidazole, cefoxitin, and chloramphenicol killed 90% of the strains. None of the aminoglycosides tested demonstrated antibacterial activity at 50 microgram/ml. Penicillin, ampicillin, carbenicillin, and cefoxitin exhibited MBC/MIC ratios of 4 or less with all strains. Erythromycin, tetracycline, and metronidazole exhibited MBC/MIC ratios of 4 or less for 12 of 13 strains. The MICs of cephalothin and cefazolin for 90% of the strains were 25 and 50 microgram/ml, respectively. The MBC/MIC ratios for these drugs were 4 or less for 12 of 13 and 7 of 13 strains, respectively. The MIC of cefamandole for 90% of the strains was 3.12 microgram/ml; however, only nine strains had an MBC/MIC ratio of 4 or less.

Agranulocytosis↗
PubMed1981

Scanning electron-microscopy of plague in Papillon-Lef:evre syndrome.

Supra and subgingival plaque associated with periodontal lesions in patients with Papillon-Lefèvre syndrome were studied by examining extracted teeth and associated soft tissue by scanning electron and light microscopy. Four zones of plaque were described according to their location along the tooth surface. Supragingivally, cocci, filamentous bacilli and "corncob" formations were seen. Fusiform bacilli colonized the surface of supragingival plaque on the root surface. Subgingival sites, particularly apical areas, had numerous spirochetes adherent to the plaque surface as well as directly to the cementum surface. Microcolonies of bacteria, probably Mycoplasma, could be seen in the subgingival plaque. The findings of a potentially pathogenic plaque, attached subgingival spirochetes and microcolony formation may have important therapeutic and research implications.

Bacteria↗
PubMed1980

Capnocytophaga sepsis: a newly recognised clinical entity in granulocytopenic patients.

10 episodes of Capnocytophaga sepsis occurred in 6 patients with granulocytopenia, malignancy, and oral mucosal ulcerations. Capnyocytophaga is a newly described genus of gliding gram-negative bacilli which is physiologically and genetically identical to Bacteroides ochraceus and biogroup DF-1 of the United States Center for Disease Control and is commonly responsible for periodontal infections.

Adenocarcinoma↗
PubMed1980

Antimicrobial effect of fluorides on Bacteroides melaninogenicus subspecies and Bacteroides asaccharolyticus.

This study was undertaken to determine whether the suspected periodontopathogens Bacteroides melaninogenicus ss melaninogenicus and intermedius and Bacteroides asaccharolyticus are killed by clinically used topical fluorides. The viability of each organism was examined after exposure to three fluoride compounds, stannous (SnF2), acidulated phosphate (APF), and neutral sodium (NaF), for 1 and 8 h. Stannous fluoride was found to be effective at lowest fluoride concentrations with APF next in effectiveness. NaF required the highest concentrations of fluoride to kill test organisms. Longer exposure times were found to be more effective at lower concentrations. Data obtained in this study with gram-negative organisms support and extend previous information regarding the antibacterial effect of fluorides against gram-positive periodontopathogens.

Acidulated Phosphate Fluoride↗
PubMed1979

Detection, identification, and comparison of Capnocytophaga, Bacteroides ochraceus, and DF-1.

Working independently, three laboratories had recognized considerable similarity among certain strains of dysgonic, fermentative, capnophilic, surface translocating, gram-negative bacilli referred to as Capnocytophaga, Bacteroides ochraceus, and Center for Disease Control biogroup DF-1. To determine the relationship among these groups, 21 strains were exchanged and independently characterized by the three laboratories. Additionally, a fourth laboratory examined the deoxyribonucleic acid homologies of the same strains. Using methods common to dental microbiology, eight of the strains had been isolated from the gingival sulcus and periodontal lesions and identified as Capnocytophaga. Three strains isolated from blood and transtracheal aspirate had been characterized by conventional anaerobic methods and recorded as B. ochraceus. Ten strains isolated from sputum, blood, throat, spinal fluid, and tracheal aspirate had been identified as DF-1 with the methods of E. O. King and a buffered single-substrate technique. All strains were similar in respect to colonial and microscopic morphology, surface translocation, biochemical features, gas-liquid chromatograms of metabolic end products, and deoxyribonucleic acid composition. We conclude that these biogroups should be termed Capnocytophaga species.

Bacterial Infections↗
PubMed1979

Simplified technique for sonication and processing of dental plaque samples.

A simplified method for processing dental plaque samples was devised and compared to previously used methods. Analysis of 36 nonstandardized subgingival plaque samples from various states of periodontal health and disease and 12 standardized supragingival plaque samples demonstrated that there was no significant difference between the recovery offered by the two techniques. Comparable recovery, increased convenience, and adaptation to the clinical setting suggests that implementation of this simplified technique may be of great value.

Aged↗
PubMed1979

Antibacterial susceptibility of plaque bacteria.

Selected anaerobic, capnophilic and facultative bacteria isolated from patients with various forms of periodontal health and disease were tested for their susceptibility to antibiotics and antimicrobial agents. Specific bactericidal and minimum inhibitory concentrations were compared to disc zone diameters, thereby generating new standards for the potential selection of antimicrobial agents.

Ampicillin↗