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Biomedical subjects

R E Cohen

Publications and source records attributed to R E Cohen.

At least 37 records · Page 2Linked to original sources
PubMed1997

Phenotypic characterization of mononuclear cells from gingiva associated with periodontitis and peri-implantitis.

The purpose of this study was to compare the phenotypic distribution of resident gingival mononuclear inflammatory cells from tissues associated with peri-implantitis and periodontitis. Inflamed gingiva was obtained from six patients during surgical removal of failed dental implants. Similarly, inflamed gingiva around teeth was obtained from eight patients with moderate to advanced periodontitis. Monoclonal antibodies were used to identify membrane antigens from CD4+ T-lymphocytes, CD4+/CD8(+)-activated T-lymphocytes, tissue macrophages, CD20+ B-lymphocytes, and MHC class II (Ia) antigens. Gingival inflammation associated with both dental implants and natural teeth was characterized by substantial numbers of CD4+ T-lymphocytes, resident macrophages, and B-lymphocytes. In addition, there was an abundance of HLA class II-positive mononuclear cells throughout most specimens. These results suggest that the gingival mononuclear inflammatory response in peri-implantitis and periodontitis is similar and support the hypothesis that similar inflammatory mechanisms are associated with both conditions.

Adult↗
PubMed1997

Clinical evaluation of the effect of a hydrogen peroxide mouth rinse, sodium bicarbonate dentifrice, and mouth moisturizer on oral health.

The objective of this 60-day single-blind, parallel trial, using 150 subjects, was to evaluate the effect of a 20% sodium bicarbonate dentifrice, a 1.5% hydrogen peroxide solution and a mouth moisturizer on oral tissues and microflora. Subjects were randomly assigned to one of five groups. The treatments were: 1) Sage dentifrice (sodium bicarbonate). Toothette Plus containing baking soda saturated with the hydrogen peroxide solution and use of a mouth moisturizer, 2) Crest dentifrice, Toothette Plus containing baking soda saturated with the hydrogen peroxide solution and use of a mouth moisturizer, 3) Crest dentifrice, Toothette Plus containing baking soda with a control solution and no mouth moisturizer, 4) Crest dentifrice, Toothette (without baking soda), saturated with a control solution and no mouth moisturizer, and 5) Crest dentifrice, Toothette saturated with 1.5% flavored H2O2 and no mouth moisturizer. From a subgroup of 35 patients (seven from each group) buccal smears for exfoliative cytology were taken as were supragingival microbiological samples from the mesial aspect of first molars (pooled). Buccal smears were evaluated for signs of histopathological changes. Microbiological samples from supra- and subgingival plaque for P. gingivalis, P. intermedia, A. actinomycetemcomitans. A viscosus, F. nucleatum, F. sanguis and C. albicans were evaluated. Clinical parameters measured were a stain index (SI), the modified gingival index (MGI), and a plaque index (PI). There were no adverse changes in the oral microflora and no anaplastic or other pathological changes in any subjects. Clinical parameters showed a statistically significant reduction in the MGI ranging from 26.7-29.9% with no significant differences among the groups (p > 0.05). The PI showed small reductions in all groups except group 2, but the differences were not statistically significant from each other or baseline (p > 0.05). The SI revealed slight increases in all groups and no differences among the groups. It can be concluded that use of Sage dentifrice, Toothette Plus saturated with Perox-A-Mint and Sage Mouth Moisturizer are safe to oral tissues. Using these components did not result in clinically noticeable stain formation, promote plaque formation, or produce any significant adverse changes in the oral microflora.

Adolescent↗
PubMed1996

Localized cellular inflammatory responses to subcutaneously implanted dental mercury.

Previous reports have demonstrated mercury accumulation and toxicity in oral tissues following exposure to mercury vapor from dental amalgam restorations. In the present study, inflammatory responses to subcutaneously administered mercury were assessed histopathologically and immunocytochemically in a rat model system. A panel of six well-characterized monoclonal antibodies specific for monocytes, macrophage subsets, T and B lymphocytes, and major histocompatibility complex (MHC) class II (la) determinants was used to quantitate alterations in mononuclear cell subsets in situ at time intervals from 2 d to 8 wk. The results revealed acute inflammatory cell infiltration at 2 and 3 d, followed by chronic inflammation that persisted after 8 wk. The numbers of monocytes, resident macrophage subsets, and mononuclear cells expressing la antigen were significantly different from control tissues at 1-2 wk. The numbers of resident macrophages remained significantly higher even after 8 wk. These data showed that in situ mercury accumulation can lead to altered expression of MHC class II determinants with persistent chronic inflammation and shifts in mononuclear cell subpopulations.

Animals↗
PubMed1996

Differential effects of ubiquitin aldehyde on ubiquitin and ATP-dependent protein degradation.

ATP-dependent proteolysis of 125I-labeled human alpha-globin, bovine alpha-lactalbumin, bovine serum albumin, or chicken lysozyme was assessed in a rabbit reticulocyte extract supplemented with ATP, excess ubiquitin, and variable amounts of ubiquitin aldehyde (Ubal), an inhibitor of many ubiquitin-protein isopeptidases. Low concentrations (0.8 microM) of Ubal increased the ATP-dependent degradation of 125I-alpha-globin by approximately 30% after 2 h at 37 degrees C, had little effect on 125I-lysozyme turnover, and decreased 125I-alpha-lactalbumin or 125I-albumin degradation by approximately 20%. The ATP-dependent degradation of all substrates was inhibited by high concentrations (> 3 microM) of Ubal throughout the incubation (15 min to 2 h); after 2 h, this inhibition ranged from 15% for 125I-alpha-globin to approximately 85% for 125I-alpha-lactalbumin and 125I-albumin. Levels of ubiquitin-125I-protein conjugates were increased significantly with Ubal; with > or = 8.0 microM Ubal, high molecular mass multiubiquitinated conjugates were particularly evident for 125I-alpha-globin and 125I-alpha-lactalbumin. These mixtures also accumulated ubiquitin conjugates with sizes expected for di- through pentaubiquitin oligomers. The results are consistent with the following proposed events: The ATP-dependent degradation of 125I-alpha-lactalbumin or 125I-albumin is probably mediated almost exclusively through polyubiquitinated intermediates. High Ubal concentrations inhibit an isopeptidase(s) which normally disassembles "unanchored" polyubiquitin chains that remain after substrate degradation by the 26S proteasome; these chains accumulate to inhibit further conjugate degradation. Much of the ATP-dependent degradation of 125I-alpha-globin and, to a lesser degree, 125I-lysozyme may occur through alternative structures where ubiquitin monomers or short oligomers are ligated to one or more substrate lysines. For 125I-alpha-globin, even low concentrations of Ubal effectively inhibit deubiquitination of these conjugates to enhance alpha-globin degradation.

Adenosine Triphosphate↗
PubMed1996

Cellular inflammatory responses to implanted dental materials.

Cellular inflammatory responses to subcutaneous implantation of amalgam and composite resins were assessed in rats by use of histologic and immunocytochemical methods 2 days to 8 weeks after implantation. Frozen and paraffin sections were obtained from subcutaneous tissues associated with amalgam and composite resin suspensions. The amalgam induced mild inflammation with proliferation of few resident macrophages, but implantation of composite resins was associated with an influx of monocytes, increased numbers of resident connective tissue macrophages, and abnormal major histocompatibility antigen class II (Ia antigen) expression. The data suggest that composite resins may produce a a more pronounced inflammatory response than dental amalgams do when incorporated in soft tissues.

Animals↗
PubMed1996

Morphology of rod stock and compression-moulded sheets of ultra-high-molecular-weight polyethylene used in orthopaedic implants.

Compression-moulded sheets and extruded rods of ultra-high-molecular-weight polyethylene (UHMWPE) are currently used in the production of joint replacement prostheses. Crystallographic texture present in rods and sheets of UHMWPE was measured using a combination of small-angle X-ray scattering and wide-angle X-ray diffraction. Crystallographic texture can induce anisotropy in macroscopic properties of polymers, such as modulus and yield stress. Both rods and sheets of UHMWPE revealed a low but discernible degree of preferred orientation of polyethylene chains within crystallites. There was a spatial variation in crystallographic orientation in extruded rods. The direction of chain alignment within crystallites located near the outer surface of rods was orthogonal to the radial direction, whereas the chain direction was orthogonal to the axial or extrusion direction in crystallites located near the centreline of extruded rods. Crystallographic texture was spatially uniform in compression-moulded sheets with the chain direction within crystallites aligned orthogonal to the moulding direction. In both cases the induced crystallographic texture can be explained in terms of crystallization from an oriented melt.

Anisotropy↗
PubMed1996

The effect of methotrexate on the expression of a cysteine protease inhibitor (type 2 cystatin) in rat sebaceous glands.

The purpose of this study was to assess whether rat cystatin S, a cysteine proteinase inhibitor, is present in rat sebaceous glands, and to measure the effects of methotrexate on the expression of cystatin in these glands. With methotrexate treatment, the number of skin sebaceous cells expressing cystatin increased from 13.9% to 34.3% (P < .05). A smaller increase (from 15.3% to 23.9%; P = .1) was observed in Zymbal sebaceous glands. Type 2 cystatin could not be detected in the major salivary glands, nor in trachea, lung, stomach, small intestine, large intestine, spleen, liver, kidney, or pancreas, in any of the rats given either saline or methotrexate. Our results suggest that type 2 cystatin is a constituent of normal sebaceous glands, and that the amount of cystatin present in these glands increases with methotrexate administration. We speculate that, in addition to the protective functions ascribed to sebaceous lipids, sebum may augment the physical barrier of skin through secretion of cysteine proteinases that may be pharmacologically modulated.

Animals↗
PubMed1996

Iontophoresis of indocyanine green and monastral blue B for gonioscopic diode laser sclerectomy.

Ab interno gonioscopic diode laser sclerectomy should allow the creation of a filtration fistula in glaucoma treatment using light energy in the near infrared range. Diode laser sclerectomy can be facilitated by dying the sclera to optimize laser energy absorption at the appropriate wavelength. Indo-cyanine green (ICG) and Monastral Blue B (MBB) are two dyes that have their peak absorptions in the near infrared region. This study determined the feasibility of ICG and MBB iontophoresis in human cadaver sclera and transconjunctivally in rabbits in vivo. MBB was unable to achieve full-thickness scleral staining in either model. ICG was able to penetrate 400 microns in human cadaver sclera and approximately 500 microns transconjunctivally in rabbit sclera in vivo.

Animals↗
PubMed1995

Showdown time.

There may not be a train wreck this fall, but that doesn't mean that there won't be some close calls as the White House and Congress come to grips on such issues as spending and taxes, health care, welfare and the environment.

Budgets↗
PubMed1995

Mononuclear cells in salivary glands of normal and isoproterenol-treated rats.

The purpose of this study was to analyse the phenotypical distribution of resident cells of the mononuclear phagocyte system in rat salivary glands, and to determine whether isoproterenol induces alterations in macrophage and lymphocyte surface-marker expression. Frozen sections of gland tissues were prepared from five normal rats, and from six rats treated with 20 mg/kg isoproterenol/day for 10 days. A panel of six monoclonal antibodies was used to identify membrane markers associated primarily with monocytes (ED1), mature tissue macrophages (ED2), lymphoid macrophages (ED3), MHC class II (Ia) antigens (OX6), CD5-positive T lymphocytes (OX19), and rat B lymphocytes (OX33). Double-labelling techniques were used to detect the coexpression of ED1/ED2 and OX6/ED2 mononuclear cell markers in the major salivary glands. ED2-positive macrophages were predominant in all three major glands, ranging from 96 cells/0.87 mm2 field in the parotid gland to 165 cells/0.87 mm2 in the submandibular. OX19-positive T lymphocytes were rarely observed in submandibular and parotid glands but represented a distinguishing feature of the sublingual. Moderate numbers of ED3-positive macrophages also were detected in sublingual tissues. In the submandibular and parotid glands, isoproterenol resulted in a decrease in ED2-positive cells, but ED2-positive macrophages increased in sublingual glands with isoproterenol. Isoproterenol resulted in a decrease in MHC class II antigen expression on submandibular and sublingual mononuclear cells but an induction of Ia antigen in the parotid gland. Double labelling revealed that isoproterenol induced coexpression of ED1/ED2 markers on mononuclear cells in the submandibular glands, but ED1/ED2-positive cells were absent from other glands. However, coexpression of MHC class II markers on ED2-positive cells in the sublingual and parotid glands of normal rats was frequently observed, with isoproterenol decreasing coexpression in the sublingual gland and increasing it in the parotid. B lymphocytes were not detected in any of the glands examined. These findings indicate that important differences exist in normal resident mononuclear cell subsets among the major salivary glands of the rat. The differential effects of isoproterenol on inflammatory cells may reflect important differences in local salivary gland immunoregulation. Although salivary gland inflammation induced by isoproterenol does not appear to result from immune mechanisms, the rich population of T lymphocytes and ED3-positive macrophages, and presence of MHC class II antigens, suggest that the sublingual gland may function as an immune organ and have a role in mucosal immunity.

Adrenergic beta-Agonists↗
PubMed1994

Commanding general.

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Health Care Reform↗