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Biomedical subjects

D B Drucker

Publications and source records attributed to D B Drucker.

At least 109 records · Page 6Linked to original sources
PubMed1983

Gas chromatographic analysis of bacterial amines as their free bases.

Columns of Chromosorb 103, Tenax-GC, Amine 220 plus potassium hydroxide on Chromosorb W, and Carbowax 20M plus potassium hydroxide on Chromosorb W were compared for their ability to separate bacterial amines as their free bases in aqueous solution. A 1.52 m X 0.6 cm O.D. column of Chromosorb 103 separated eleven amines when operated isothermally at 185 degrees C. A further four high-boiling amines could be separated at 240 degrees C. The other packings separated only eight amines isothermally, except for Tenax-GC which separated seven of the free bases. Chromosorb 103 performed less well than Carbowax 20 M plus potassium hydroxide with respect to number of plates or peak resolution. The maximum number of amines separated, thirteen, required Chromosorb 103 programmed from 170 degrees C to 230 degrees C at 3 degrees C min-1 after an initial holding time of 20 min. It was possible tentatively to identify amines in culture supernatant fluid of Proteus mirabilis, viz. ethylamine, isobutylamine and isoamylamine, after direct injection of culture supernatant fluid.

Amines↗
PubMed1983

Comparative effects of five chlorosucrose analogues on acidogenicity and adherence of the oral bacterium Streptococcus mutans in vitro.

Standardized Streptococcus mutans suspensions were incubated with five chlorosucrose compounds alone and in the presence of sucrose. Fall in pH was recorded over 4 h. Other experiments used image-analysis techniques to measure deposition by sedimentation from similar test suspensions. In the pH experiments, order of acidogenicity was 1'-chlorosucrose or 4,6,6'-trichlorosucrose greater than 1',6'-dichlorosucrose greater than 6,1',6'-trichlorosucrose. The last two compounds statistically significantly reduced fall in pH from metabolism of endogenous carbohydrate. All the chlorosucroses significantly decreased acidogenicity of sucrose; with 6,1',6'-trichlorosucrose and 4,1',6'-trichlorosucrose terminal pH was approximately 1 unit higher than with sucrose alone. In the deposition experiments, all chlorosucroses except 1',6'-dichlorosucrose decreased deposition in the presence of sucrose after either 30 min or 4 h incubation. The greatest reduction in deposition in the presence of sucrose after 4 h was with 6,1',6'-trichlorosucrose or 1'-chlorosucrose.

Adhesiveness↗
PubMed1983

Effect of glucose concentration in the growth medium upon neutral and acidic fermentation end-products of Clostridium bifermentans, Clostridium sporogenes and peptostreptococcus anaerobius.

Clostridium bifermentans, C. sporogenes and Peptostreptococcus anaerobius were grown in Fastidious Anaerobe Broth with glucose concentrations from 0-1.5% (w/v). Gas chromatographic (GLC) analysis of fermentation end-products revealed that a change in glucose concentration markedly affected fermentation patterns of each microorganism. Increased glucose concentration resulted in stimulation of ethanol production by all strains, and of butanol and butyric acid by C. sporogenes. With C. bifermentans, there was a parallel increase in ethanol and acetic acid production and decreased formation of propanol and propionic, iso-butyric and iso-valeric acids. Increased ethanol formation by P. anaerobius was accompanied by an increase in acetic acid and a decrease in butan-1-ol production. The greatest incremental change in GLC profiles occurred when glucose concentration was raised from zero to 0.1% (w/v). These data suggest that glucose concentration in a medium for GLC analysis must be rigorously controlled if reproducible results are to be obtained.

Chromatography, Gas↗
PubMed1983

Effect of eight growth media upon fermentation profiles of ten anaerobic bacteria.

A study was made of the influence of eight growth media upon the fermentation end-product patterns obtained with ten species of anaerobes. Acidic and neutral end-products of fermentation were analysed by gas chromatography and the results were examined statistically by computer. Differences in end-product profile were at least as great between different media used to grow a single anaerobic species, as between different anaerobes grown in a single type of medium. When individual fermentation end-products produced by a single anaerobe species were examined statistically significant differences were found between different media for individual end-products. It is concluded that standardisation of growth medium is essential in diagnostic laboratories concerned with identification of anaerobes with the aid of gas chromatography.

Anaerobiosis↗
PubMed1983

Trimethylsilyl-sugar profiles of Streptococcus milleri and Streptococcus mitis.

Seventy strains of 'viridans-group' streptococci were analysed gas chromatographically after preparation of trimethylsilyl ethers of their cellular sugars. The resulting profiles were evaluated as a possible aid to taxonomy. Glycerol, glucose, galactose, N-acetyl-glucosamine and N-acetylmuramic acid were found in all strains, in varying amounts. Rhamnose was the major neutral sugar in most strains, other than representatives of Streptococcus mitis, which invariably had ribose and usually anhydroribitol but no rhamnose. One strain of Strep. mitis possessed arabitol. Some strains of Strep. mitis and 'Strep. milleri' were alone in containing N-acetylgalactosamine. A combination of N-acetylgalactosamine and rhamnose in the absence of ribose was diagnostic for strains of 'Strep. milleri'.

Acetylgalactosamine↗
PubMed1983

Possible heterogeneity of Streptococcus milleri determined by DNA mol % (guanine plus cytosine) measurement and physiological characterization.

DNA base pair ratios (mol % guanine + cytosine) were calculated, for eighteen strains of Streptococcus milleri, from measurements of DNA melting temperature (Tm). Strains of vaginal origin which were also 'atypical' physiologically had a value of 40.3. The two culture collection of 'minute' beta-haemolytic strains of Lancefield groups G and F had values of 36.8 and 38.8 mol%, respectively. Three other reference strains had a DNA guanine plus cytosine content ranging from 40.4 to 43.0 mol%, including Streptococcus sp MG which had a value of 42.0 mol%. Strain 7H of oral origin had a value of 40.9 mol%. The remaining physiologically typical strains, of medical origin, had guanine plus cytosine contents ranging from 36.6 to 42.1 mol%. It therefore seems possible that genetic heterogeneity may exist among representatives of Streptococcus milleri.

Cytosine↗
PubMed1982

Effects of two potential sucrose-substitute sweetening agents on deposition of an oral streptococcus on glass in the presence of sucrose.

The effects of trichlorogalacto-sucrose (TGS) and xylitol upon deposition by sedimentation of Streptococcus mutans NCTC 10832 were measured in terms of percentage coverage and mean clump size, using computerized image-analysis. The following test solutions were used: sucrose, sucrose plus xylitol, sucrose plus TGS, xylitol, TGS, and saline alone. Xylitol and TGS both significantly reduced the mean clump size of sucrose-incubated cells; TGS also significantly reduced percentage coverage by cells incubated with sucrose. Xylitol and TGS differed significantly from one another regarding their effects upon both percentage coverage and mean clump size of cells incubated in sucrose solution. It was postulated that TGS and xylitol might affect sucrose-associated aggregation of Strep. mutans.

Glass↗
PubMed1982

Bacteriocin production by Streptococcus milleri.

Bacteriocinlike activity was sought among 58 streptococcal strains using a deferred antagonism technique and 50 indicator strains. Antagonist production was generally increased by glucose supplementation of brain heart infusion agar and reduced by addition of calcium carbonate. Activity due to complete bacteriophage was excluded, as was toxic buildup of lactate, acetate, or ethanol. Hydrogen peroxide activity was responsible for all, or part, of antagonist activity in Streptococcus mutans tested and in nine strains of S. milleri. Virtually all isolates of S. milleri tested were sensitive to the bacteriocinlike activity of S. mutans NCTC 10832.

Bacteriocins↗
PubMed1982

Pyrolysis gas chromatography of Streptococcus faecalis: effect of cultural conditions on pyrochromatograms.

Streptococcus faecalis 251 was cultured under a variety of different growth conditions, i.e. incubation for 24 or 70 h; at 22 degrees, 37 degrees or 45 degrees C; on blood agar or on MacConkey agar plates; aerobically or anaerobically. Replicate cultures were analysed by pyrolysis-gas liquid chromatography on columns of 7% Carbowax 2 M, TPA on Chromosorb G (AW-DMCS, 80-100 mesh) programmed from 40 degrees C up to 170 degrees C. Culture grown under identical conditions resulted in reproducible pyrochromatograms which were only slightly modified by change in temperature of growth from 37 degrees to 45 degrees C, or length of growth from 24 to 70 h, or growth on MacConkey agar instead of blood agar. Growth under anaerobic conditions resulted in a modified pyrochromatogram; while growth at only 22 degrees C resulted in a major change in pyrochromatogram.

Chromatography, Gas↗
PubMed1982

Effect of incubation time, and calcium carbonate and glucose in the growth medium, upon the fermentation end-product profile of Clostridium difficile.

The effects of time, glucose and calcium carbonate upon fermentation profiles of Clostridium difficile were determined. The test organism was grown in three media, viz. fastidious anaerobe broth (FAB), FAB with 1% w/v glucose, and FAB with 1% glucose plus calcium carbonate. Fermentation products were analysed after 24, 48 and 72 h incubation. By 48 h, qualitatively 'typical' profiles could be produced. Glucose supplementation of FAB suppressed formation of certain branched-chain carboxylic acids. However, the presence of calcium carbonate, in addition to glucose, resulted in a quantitative increase in products after 48 h and 72 h. This effect was particularly marked with respect to alcohol production by C. difficile.

Calcium Carbonate↗
PubMed1982

Comparison of computer methods for taxonomy of some streptococci using gas chromatographic chemotaxonomic data.

Gas chromatographic fingerprints of eighty-three strains of Streptococcus were analysed by computer. Seven measures of association were compared for their ability to identify strains. The most effective measure was the Stack coefficient which correctly identified 68% of strains, mostly of oral origin. Clustering of strains was carried out by median, average, single-linkage, furthest neighbour, and centroid linkage, Andrew's plots, and Minimum Spanning Trees. Of the clustering methods, centroid linkage produced the most inclusive and compact clusters. Clusters of strains of S. mitis, S. mutans, S. salivarius and S. sanguis showed varying degrees of heterogeneity; while, S. milleri was comprised of three chemotypes corresponding to oral isolates, biochemically atypical vaginal isolates, and biochemically typical strains from other sources.

Chromatography, Gas↗
PubMed1981

Comparison of fatty acid fingerprints of streptococci of Lancefield groups A, D, E, F, G, H, K, O, P and Q.

Twenty-two strains of Lancefield-groupable streptococci were examined by gas chromatographic analysis of their methyl carboxylic esters. In all cases, their major cellular fatty acids had the retention characteristics of myristic, palmitic and octadecenoic acids. Other peaks present in most strains were due to peaks having the retention characteristics of hexadecenoic, stearic, and octadecenoic acids. The quantitative data sets were compared using the coefficient of linear correlation as a measure of association. It was possible to differentiate between certain serotypes, solely on the basis of fatty acid fingerprint. Members of groups E, F, G, H, K, O, P and Q were more similar to reference strains of groups E, F and Q than to A.

Fatty Acids↗
PubMed1980

Effect of cultural conditions on trimethylsilyl-sugar profiles of Streptococcus mutans.

The cellular carbohydrates of Streptococcus mutans NCTC 10832 were converted to methyl glycoside trimethylsilyl ethers and analyzed by gas-liquid chromatography. The resulting profiles revealed the presence of glycerol, xylose, rhamnose, galactose, glucose, N-acetylglucosamine, and N-acetylmuramic acid. The proportions of monosaccharides in the profile were found to be stable with respect to changing growth temperature or duration of growth. However, the type of medium used, and its carbohydrate content, did significantly alter the profile, whereas gaseous atmosphere exerted a lesser effect on carbohydrate composition. By controlling growth parameters, we obtained reproducible profiles. Whole cells are probably a satisfactory alternative to highly purified cell walls.

Carbon Dioxide↗
PubMed1979

Fingerprinting of carbohydrates of Streptococcus mutans by combined gas-liquid chromatography-mass spectrometry.

A modified method is described for the analysis, by gas-liquid chromatography, of various sugars as the trimethylsilyl derivatives of their methyl glycosides. The technique was employed for the analysis of the cellular carbohydrate of Streptococcus mutans NCTC 10832 and provided reproducible fingerprints, consisting of peaks due to glycerol, rhamnose, xylose, galactofuranse, glucose, N-acetylglucosamine and N-acetylmuramic acid. Absolute identification of the latter was by combined gas-liquid chromatography--mass spectrometry.

Carbohydrates↗