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Biomedical subjects

C M Cobb

Publications and source records attributed to C M Cobb.

17 recordsLinked to original sources
PubMed1992

A preliminary study on the effects of the Nd:YAG laser on root surfaces and subgingival microflora in vivo.

The purpose of this study was to examine the effects of root preparation using the pulsed Nd:YAG laser, either alone or in combination with manual instrumentation. Study specimens consisting of 18 teeth with associated periodontal pockets from 8 different patients were treated as follows: 5 specimens were root planed with curets followed by laser exposure for 3 minutes using energy settings of 3.0 W at 20 pps; 2 specimens were root planed and then laser treated for 3 minutes using settings of 2.25 W and 20 pps; 4 specimens were treated by laser for 1 minute at settings of 1.75 W and 20 pps followed by root planing; 4 specimens were treated by laser only for 1 minute using settings of 1.75 W and 20 pps; and the remaining 3 teeth served as untreated controls. Both prior to and after completion of the laser and root planing treatments, microbiological samples were obtained from the treated pockets and submitted to a commercial laboratory for analysis of levels of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Prevotella intermedia. With the exception of two 7-day specimens, all others were extracted immediately post-therapy and processed for SEM examination. All treated specimens, regardless of treatment sequence, exhibited some degree of laser-induced root surface alteration. Notably, laser-treated calculus deposits were free of their characteristic surface layer of microbial plaque. Microbial sampling indicated a post-therapy reduction in levels of all 3 putative microbial pathogens compared to pre-treatment samples and control specimens. However, SEM examination revealed residual deposits of plaque and calculus in all treatment groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1976

Activation of fibroblast procollagenase by mast cell proteases.

Proteases capable of activating procollagenase from gingiva and from fibroblast and macrophage monolayer cultures were harvested from homogenates of canine tumor mast cells. The mast cell proteases lysed casein and Azocoll but not native collagen. In low salt concentrations the enzymes existed at high molecular weight complexes, which were dissociated by increasing the salt concentration above 1.0 M (NaCl, KCl). Gel filtration in 1.4 M KCl separated the protease activity into three peaks, all of which activated procollagenase. Two of the enzymes showed substrate specificities (hydrolysis of p-tosyl-L-arginine methyl ester and benzoyl-tyrosine ethyl ester) and reactive center reactivities similar to pancreatic trypsin and chymotrypsin. Based on gel filtration, apparent molecular weights of 160 000 (p-tosyl-L-arginine methyl ester esterase), 90 000 (main procollagenase activator) and 36 000 benzoyl-tyrosine ethyl ester esterase) were determined. Activation of procollagenase resulted in a 18-20 000 decrease of the molecular weight. The activation was directly related to the amount of activator added within certain limits. Further addition of activator resulted in proteolytic inactivation of collagenase.

Animals↗
PubMed1976

Synthesis and release of procollagenase by cultured fibroblasts.

An inactive collagenase was harvested from both serum-free and serum-supplemented fibroblast monolayer cultures in periods of active collagen synthesis. The latent collagenase did not hydrolyze collagen and did not bind the potent collagenase inhibitor alpha2-macroglobulin. Activation with trypsin imparted to the enzyme the ability to hydrolyze collagen at neutral pH in a typical manner and to form an inhibited complex with alpha2-macroglobulin. The molecular weights, determined by calibrated gel filtration, were 78,000 and 60,000 for the latent and active enzymes, respectively. The data indicate that collagenase is released from the cells in inactive form, as a zymogen.

Amino Acids↗
PubMed1976

Procollagenase from bovine gingiva.

1. Collagenase (EC 3.4.24.3) is released from bovine gingival explants in vitro as a zymogen. The zymogen does not hydrolyze collagen and does not form a complex with alpha2-macroglobulin (alpha2-M). It elutes in gel filtration with an apparent molecular weight of approx. 80 000. 2. Incubation of the zymogen with trypsin results in a 15 000-20 000 dalton decrease in molecular weight and imparts to the enzyme the ability to hydrolyze collagen and to form a complex with alppha2-M. 3. The zymogen can be completely separated from the active enzyme to alpha2-M. Likewise, the zymogen can be harvested from cultures supplemented with serum.

Animals↗
PubMed1976

Potential of elastin and collagen as initiators of in vivo calcification.

The osseous repair response of the guinea pig to purified bovine elastin from ligamentum nuchae and decalcified rat femur collagen was studied by implantation of these materials into an extraction socket. A nylon mesh tube was used to carry the respective implant materials to place, and in one group of animals only the nylon tube was implanted, thereby serving as a control for the study. Neither the collagen or elastin matrix appeared to elicit an immune rejection response from the host animal. Histologic and quantitative results indicated that collagen implants accelerated the osseous repair of the extraction socket. Elastin implants, which characteristically resulted in ossicle formation, did not appear to accelerate healing, but the results were quantitatively similar to those in the experimental control animals.

Alveolar Process↗
PubMed1976

Ultrastructural features of the verruciform xanthoma.

The verruciform xanthoma, a rare lesion of the oral cavity, was studied by light and electron microscopy. The major cell type associated with the lesion was shown to contain appreciable amounts of lipid and was characterized as a macrophage. It was characteristic of the endothelial cells associated with subepithelial capillaries to exhibit multiple basal laminae. A rather unusual observation was the migration of lipid-filled cells into the stratum germinativum of the overlying epithelium.

Adult↗
PubMed1976

Mast cell distribution in oral tissues of germ-free vs. conventional beagle dogs.

Light microscopic examination of the mast cell distribution in various oral tissues in germ-free and conventional beagle dogs revealed no differences between the two animals. Mast cells were observed in all tissues examined, with an increasing order of incidence as follows: cervical lymph node, parotid and submandibular glands, marginal gingivae, buccal mucosa and the middle one-third of the tongue. All four types (round, oval, elongated, and pseudopodial) of mast cells cell shapes previously described in the literature were observed. The marginal gingivae associated with the mandibular, second bicuspids was examined by light microscopy and was classified as to degree of inflammatory involvement. In a comparison of germ-free and conventional animals, the distribution of the degree of inflammation proved to be random. Correlation between mast cell densities and the degree of inflammatory infiltration was not statistically significant. However, mast cells tended to decrease as the inflammation became more severe. Electron microscopic examination of mast cells in the buccal mucosa revealed no difference in morphology of cells from germ-free or conventional animals. Cytoplasmic granules were of two basic types, one exhibited an amorphous matrix of uniform density and the other consisted of laminated coils of various sizes and densities.

Animals↗
PubMed1975

Ultrastructural characteristics of mast cells from a canine mastocytoma maintained in vitro.

Mast cells obtained from a canine mastocytoma were maintained in cell culture for a period of 11 weeks. Samples of these cells were harvested for electron microscopic examination after 9 weeks in vitro. Although the overall morphologic appearance was sufficient to allow their identification as mast cells, the tumor cells differed in several respects from descriptions of normal tissue mast cells. In contrast to normal tissue mast cells, the tumor cells exhibited peripheral accumulations of microfilaments, randomly dispersed microtubules, and small clusters of smooth endoplasmic reticulum. The tumor mast cells also presented three different granule types: spherical granules with an amorphous and electron dense matrix; irregularly shaped granules possessing a limiting external membrane and an internal matrix containing laminated and/or coiled structures; and granules containing loosely coiled, unorganized membrane structures similar in appearance to myelin whorls. The canine mastocytoma is an excellent source of mast cells as they can be obtained in large numbers without contamination by extraneous cell types and the cells can be maintained in vitro for extended periods of time.

Animals↗