Biomedical subjects

E R Leadbetter

Publications and source records attributed to E R Leadbetter.

28 records · Page 2Linked to original sources

PubMed1980

Capnocytophaga spp. contain sulfonolipids that are novel in procaryotes.

A group of unusual sulfonolipids was found in bacteria of the genus Capnocytophaga. One of these lipids, to which we have assigned the trivial name capnine, was isolated in 98% pure form and was identified, by infrared absorption spectrometry, high-resolution mass spectrometry, and other methods, as 2-amino-3-hydroxy-15-methylhexadecane-1-sulfonic acid. Another lipid appears to be an N-acylated version of capnine; after acid hydrolysis, its sulfur was recovered in a form chromatographically indistinguishable from that of capnine. The new lipids are related structurally to sphingosine and the ceramides, respectively, but differ markedly from those compounds in important respects, notably the presence of the sulfonate group. Some Capnocytophaga strains accumulated mostly capnine, whereas others accumulated mostly N-acylcapnine. All seven strains examined were found to contain the new lipids, in amounts ranging from 7 to 16 mumol/g of cells (wet weight). The lipids were found in isolated cell envelopes, where they were present in amounts ranging up to 400 mg/g of envelope protein; they are, accordingly, major cell components.

Alkanesulfonates↗

PubMed1979

Capnocytophaga: new genus of gram-negative gliding bacteria. I. General characteristics, taxonomic considerations and significance.

The characteristics of gliding bacteria isolated from both healthy and diseased sites in the oral cavity are, summarized and the taxonomic position of the bacteria discussed. Uniform attirubtes of the fusiform isolates include gliding motility, strictly fermentative metabolism dependent on the presence of CO2 (or HCO3-), under either anaerobic or aerobic conditions, presence of benzidine-reactive components, and the production of acetic and succinic acids as the major or sole, acidic, metabolic and products. Given the guanine and cytosine content of DNA, their gliding motility, and the ability of many strains to attack polysaccharide a relationship to the cytophagus is suggested. This relationship, along with the CO2-dependent growth is recognized by the generic name Capnocytophaga given them. Many of the isolates are grouped into three species C. ochracea, C. Sputigena, and C. gingivalis, separated on the basis of morphological and physiological traits.

Adult↗

PubMed1979

Capnocytophaga: new genus of gram-negative gliding bacteria. II. Morphology and ultrastructure.

Gram-negative, anaerobic gliding bacteria were isolated from normal supragingival plaque and from periodontal lesions. Isolates could be divided into two size classes: small 2.4-4.2 micrograms x 0.38-0.5 microgram and large 4.8-5.8 micrograms x 0.42-0.6 microgram cells. The outer membrane was either loose-fitting and wavy, or taut, and of variable thickness. An electron-dense fuzz was discernible on several of the isolates. The periplasmic region was of variable electron-density. The genus Capnocytophaga has been proposed for these organisms based on morphological and cultural characteristics.

Adult↗

PubMed1979

Capnocytophaga: new genus of gram-negative gliding bacteria. III. Physiological characterization.

Sixty-eight strains of capnophilic fusiform Gram-negative rods from the human oral cavity were subjected to extensive physiologic characterization, tested for susceptibility to various antibiotics, and the mol-percent guanine plus cytosine of each isolate determined. The characteristics of the isolates were compared with 10 fresh and 2 stock isolates of Fusobacterium nucleatum. The isolates clearly differed from the Fusobacterium species on the basis of mol-percent guanine plus cytosine, end products, growth in a capnophilic environment and fermentation of carbohydrates. All of the gliding isolates required CO2 and formed acetate and succinate, but not H2S, indole or acetylmethylcarbinol. All fermented glucose, sucrose, maltose and mannose. The organisms may be differentiated on the basis of fermentation of additional carbohydrates, hydrolysis of polymers and reduction nitrate. Three species are proposed: Capnocytophaga ochracea, Capnocytophaga sputigena and Capnocytophaga gingivalis. Ten isolates did not fit into the proposed species.

Adult↗

PubMed1979

Ultrastructure of Bacteroides species: Bacteroides asaccharolyticus, Bacteroides fragilis, Bacteroides melaninogenicus subspecies melaninogenicus, and B. melaninogenicus subspecies intermedius.

Representative strains of two subspecies of Bacteroides melaninogenicus (subspecies melaninogenicus and subspecies intermedius) and Bacteroides asaccharolyticus as well as B. asaccharolyticus strain 536B isolated from a human perirectal abscess and Bacteroides fragilis ATCC 25285 were examined by glutaraldehyde-osmium fixation, ruthenium red fixation and staining, and thorium hydroxyde staining as well as by the physical preparative techniques of critical point drying--transmission electron microscopy (CPD--TEM) and scanning electron microscopy (SEM). All strains, with the exception of B. fragilis 25285, possessed an electron-dense material external to their outer membranes. Ruthenium red staining further revealed a layer, external to the surface of the outer membrane, that was distinct for each species examined. Thorium hydroxide, as well as CPD--TEM and SEM, showed the cells to be interconnected by thin fibers that not only connected adjacent cells but also traversed several microns to connect cell aggregates.

Bacteroides↗

PubMed1976

Comparative ultrastructure of selected oral streptococci: thin-sectioning and freeze-etching studies.

The ultrastructure of Streptococcus mutans, serotypes a-e, S. sanguis, S. mitis, and S. salivarius HHT, were examined by the techniques of thin-sectioning and freeze-etching. The cell walls varied in width between 15 and 46 nm and were covered with an electron-dense fibrillar or fuzz layer. The cytoplasmic membrane was in close association with numerous mesosomes which were, in turn, either closely associated or in contact with the bacterial chromosome. In freeze-etch replicas, the outermost layer of the cell wall was fibrous, and the cytoplasmic membrane was covered with particles composed of several subunits. Both particle-clusters and particle-free areas occurred on the surfaces of the cytoplasmic membrane, as well as a crystalline array in the ground plasm of the cell.

Cell Membrane↗

PubMed1969