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Biomedical subjects

M Goldner

Publications and source records attributed to M Goldner.

14 recordsLinked to original sources
PubMed1991

The pH of gingival crevices and periodontal pockets in children, teenagers and adults.

Gingival crevice and periodontal pocket pH, measured directly with glass micro-electrodes, was near neutral at most sites in most individuals (mean pH 6.92 +/- 0.03 SEM, 69 subjects). Periodontal state ranged from healthy to periodontitis but neither clinical evidence of gingivitis at a site nor pocket depth were associated with crevicular pH different from that at healthy sites. This finding contradicts earlier reports that gingivitis is associated with a crevicular pH as alkaline as pH 9.06. Metallic antimony electrodes as used by earlier investigators were found to give pH readings that were too high by as much as 1.5 pH units in the presence of organic reducing agents of the type produced by oral bacteria within gingival crevices. In contrast, glass micro-electrodes respond only to hydrogen ions and thereby provided accurate measurements of pH even in the presence of organic reducing agents. Loss of CO2 to the atmosphere from biological fluids that are bicarbonate buffered resulted in a shift to alkaline pH by as much as 1 pH unit. As a result, only measurements taken within gingival crevices or periodontal pockets can provide accurate measurements of crevice or pocket pH.

Adolescent↗
PubMed1991

Demonstration by confocal laserscanning microscopy of invasive potential with Bacteroides fragilis.

The confocal laserscanning microscopy (CLSM) system provides a stereoscopic view of an object. By this system the penetration of B. fragilis into HeLa cells was observed. The intensity of contact is highlighted with time. The CLSM system consolidates the recently described fluorescence technique to test invasive potential. This work purports that certain gram-negative anaerobes should be considered for invasiveness.

Bacterial Adhesion↗
PubMed1990

A simple technique useful for clinical laboratory testing for invasive potential applied to Bacteroides fragilis.

A simple technique using fluorescent microscopy examines the association between Bacteroides fragilis and different types of tissue cells (epithelial, fibroblast, osteoblast). Through this stepwise intracellular staining and extracellular quenching some latent signs of invasive quality may be exhibited. The bacteria are incubated with monolayers of tissue cells, and the reactions immediately visualized after staining with acridine orange and masking by crystal violet. Intact bacterial rods exhibit a greenish hue which will reveal their location within the tissue cells but varies depending on tissue cell type. This direct means of testing for invasive potential applied to B. fragilis relies on the use of a readily available clinical tool.

Acridine Orange↗
PubMed1979

The intracellular survival and growth of gonococci in human phagocytes.

In reassessment of previous tests for intracellular survival, results have been confirmed and additional evidence obtained indicating that some gonococci can survive and multiply in human phagocytes. Use was made of the ability of penicillin to penetrate phagocytes and to kill only actively growing organisms. In microscopic counts on 33 urethral exudate smears, an average of 49% of gonococci were associated with polymorphonuclear phagocytes. The organisms were unevenly distributed amongst the phagocytes, with most cells uninfected and some containing large numbers. Many phagocytes also remained uninfected in tests in vitro with low gonococcal inocula although experiments with large inocula showed that most phagocytes could ingest gonococci. It is proposed that ingestion of one gonococcus may stimulate the phagocytes to take up more. Phagocytes were killed and disintegrated after ingesting large numbers of gonococci and similar effect in vivo may be responsible for the large clumps of organisms seen in urethral exudate. These results underline the probable importance in the pathogenesis of gonorrhoea of intracellular survival in phagocytes.

Blood Bactericidal Activity↗
PubMed1979

Phenotypically determined resistance of Neisseria gonorrhoeae to normal human serum: environmental factors in subcutaneous chambers in guinea pigs.

Some gonococci obtained from human urethral exudate or from subcutaneously implanted chambers in guinea pigs show a resistance to killing by human serum which is lost on sub-culture in vitro after a few generations. The environmental factors which may influence the phenotypic expression of resistance to serum killing were investigated in guinea pig chambers and in chamber fluid in vitro. The redox potential in chambers before and after infection was lower than that of heart blood but conditions were not anaerobic; H2O2 increased the redox potential but did not decrease gonococcal serum resistance. The chambers were slightly alkaline before and after infection. When the concentration of glucose (depleted in infected chambers by the abundant polymorphonuclear cells) was restored to excess, the serum resistance of the gonococci was unaffected. Concentrations of free amino acids in chambers changed little during infection. Gonococci adapted to growth in chambers and subsequently rendered serum-sensitive by growing once on agar reverted to serum-resistance after 0.5 to 1 h incubation in chamber fluid in vitro at 37 degrees C but not at 25 degrees C or 4 degrees C. After 16 to 24 h growth at 37 degrees C, resistance was again lost. The reversion to serum resistance did not occur in a complex laboratory medium. Examination of the chamber fluid after growth of gonococci in vitro showed depletion of lactate, glutamine and proline.

Acetates↗
PubMed1979

Outer-membrane penetration barriers as components of intrinsic resistance to beta-lactam and other antibiotics in Escherichia coli K-12.

A new technique has been devised to investigate the penetration of antibiotics through the gram-negative outer membrane; the application here was to study intrinsic resistance of Escherichia coli K-12. Exponential cells in broth were briefly treated with 2.5 mM ethylenediaminetetraacetic acid at 5 degrees C to disrupt the outer membrane penetration barrier, and the response of treated and untreated cells to antibiotics was compared by turbidimetry. A barrier index was derived to describe the ability of 7 beta-lactam and 10 other antibiotics to penetrate the outer membrane of strain Y10. There was correlation between the molecular weight and log(10) barrier index (r = 0.59, P congruent with 0.01). The envelope mutant D22 (envA) had low barrier indexes for erythromycin, rifampin, ampicillin, and cloxacillin. For the beta-lactams, outer membrane penetration and affinity for inner membrane target site(s) triggering cell lysis were measured as independent components of the overall activity; although penetration and overall activity varied greatly, the affinities of most were within a narrow range.

Anti-Bacterial Agents↗
PubMed1979

Penetrability of the outer membrane of Neisseria gonorrhoeae in relation to acquired resistance to penicillin and other antibiotics.

Acquired antibiotic resistance in Neisseria gonorrhoeae is principally associated with three genetic markers, penA, mtr, and penB. penA is a specific marker for penicillin resistance, whereas mtr and penB are nonspecific in conferring resistance to penicillin and several other antibiotics as well. It has been suggested that the nonspecific markers may cause a general decrease in the penetrability of the gonococcal outer membrane. To investigate this, antibiotic penetration of the outer membrane was studied in two isogenic strains-FA19 (susceptible parent) and FA140 (containing penA, mtr, and penB)-and also in a clinical isolate with multiple resistance. The method involved brief treatment of exponential cells with ethylenediaminetetraacetic acid at 5 degrees C to disrupt the outer membrane barrier. The 50% inhibitory concentrations of antibiotics for treated and normal cells were measured turbidimetrically, and from their ratios outer membrane penetration barriers were calculated. Small barriers were observed for actinomycin D and benzylpenicillin, and these were very similar in the susceptible and resistant strains. Also, in FA140 no significant barriers for rifampin, erythromycin, and tetracycline were detected. These results suggest that mechanism(s) other than reduced outer membrane penetrability underlie acquired resistance due to penA, mtr, and penB.

Anti-Bacterial Agents↗
PubMed1978

Streptococcus mutans, an assessment of its physiological potential in relation to dental caries.

Streptococcus mutans converts low levels of sucrose to lactic acid, but at high levels favours synthesis of glucans for plaque accumulation. Thus, the continued exposure to sucrose fluxes would select microorganisms in the oral cavity (S. mutans being a prototype) with highly specialized adaptation and potential dental caries activity. The bacteria that have evolved physiological systems to function efficiently under these conditions are the lactic acid bacteria. These organisms survive in environments where carbohydrate availability is constantly changing. High tolerances to acidic environments may be an important determinant in establishing the ecology of the carious lesion. Also, the intercellular polysaccharide storgae (glycogenamylopectin) and extracellular polymer reserves (levan and soluble glucan) are important during carbohydrate depletion. Further, the formation of insoluble glucans is a prerequisite for the caries process on smooth surfaces of teeth through plaque development. These conditions could result in an increase in S. mutans and cariogenic microorganisms. As a result, this process may be best understood as a manifestation of an amphibiotic shift.

Carbohydrate Metabolism↗
PubMed1977

Reagin-like activity of serum in human peridonotal disease.

The serum from patients with periodontitis produced a passive cutaneous anaphylaxis reaction in monkeys when tested against subgingival plaque. This detection of reaginic antibodies shows that patients with periodontitis make immunoglobulin E antibodies to plaque constituents.

Animals↗
PubMed1976

Penicillin tolerance in Neisseria gonorrhoeae: evidence disallowing a penicillinase-mediated mechanism from a refined microbiological assay method.

A microbiological assay method has been developed and applied to Neisseria gonorrhoeae, for the purpose of detecting enzymatic deactivation of benzyl penicillin. Calibration of the method, using strains of Escherichia coli K-12 with previously reported penicillinase (EC 3.5.2.6.) activities, has shown that it is extremely sensitive and may be used in a quantitative manner. At the limit of sensitivity the test is able to detect penicillin breakdown in the order of 3 X 10(-3) mug in 48 h, which is equivalent to about 7 X 10(-8) mumol/min per milligram dry weight of cells. Over 100 strains of N. gonorrhoeae, most of them resistant to penicillin, were screened for their ability to deactivate penicillin during 48 h of growth in the presence of subinhibitory levels. No deactivation was detected. It is concluded, from quantitative evidence, that reduced penicillin sensitivity in N. gonorrhoeae is not due to the enzymatic deactivation of the antibiotic.

Bacteriological Techniques↗
PubMed1975

Level of redox potential as a possible contributing influence in the pathogenicity of oral anaerobes.

Dental plaque anaerobes may be associated with the etiology of periodontal disease. This has created an interest in the potential pathogenicity of oral anaerobes. We compared the metabolic activity of anaerobic corynebacteria (C. parvum, C. anaerobium) and corresponding aerobic species (C. diphtheriae, C. xerosis). The anaerobes exhibited lower levels of RNA synthesis, ranging from 5 to 10 fold over the aerobes. We further examined these anaerobes, plus Actinomyces naeslundi N16 (isolated from the anaerobic region of periodontally-diseased tissues), for the influence of redox potential on RNA level and antigenic function. Notable increases in RNA were found at specific Eh levels; the extent and direction of the changes varied with the different organisms. This environmental feature appeared to effect corresponding changes in agglutinability and PCA reactivity with antisera against the anaerobes cultured at different redox potentials. For example, while antisera against certain organisms (C. parvum, A. naeslundi) cultured under the most reuced conditions showed an intense PCA reaction, other antisera against the same organism cultured under less reduced conditions were non-reactive. Hence, alterations in redox potential may lead to alteredetabolism and to altered antigencity. Our results imply such a microbial response to environmental stress.

Actinomyces↗