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Biomedical subjects

J K Dyer

Publications and source records attributed to J K Dyer.

At least 37 records · Page 2Linked to original sources
PubMed1994

Gingival cell IL-2 and IL-4 in early-onset periodontitis.

The purpose of this study was to compare, using cell blot analysis, the association of gingival tissue mononuclear cells (GTMC) isolated from lesions displaying histories of early-onset periodontitis (EOP; typically B-lymphocyte dominated) and gingivitis (typically T-lymphocyte dominated) with the B-cell stimulating cytokine, interleukin (IL)-4, and the T-cell stimulating cytokine, IL-2. Eleven EOP patients and 11 age- and gender-similar gingivitis control (GC) subjects participated. Gingival tissue adjacent to the alveolar crest normally removed during surgery was digested in collagenase-containing media and GTMC were isolated by density gradient centrifugation. Cells were separated into four aliquots. One was left unstimulated; the remainder were stimulated for 2 hours with Porphyromonas gingivalis outer membrane protein, mitogen Concanavalin A, or common antigen tetanus toxoid. Cells then were centrifuged onto transfer membranes and incubated in RPMI 1640 media for 6 hours to allow absorption of secreted cytokine. Membranes were treated with monoclonal anti-IL-2 or anti-IL-4, followed by a biotin-conjugated second layer, streptavidin-alkaline phosphatase and nitro blue tetrazolium/5-bromo-4-chloro-indolyl-phosphate (NBT/BCIP) color development. A higher percentage of GTMC from EOP patients were IL-2+ when stimulated with P. gingivalis compared with GTMC from GC patients (20 +/- 2% vs. 12 +/- 2%, P < 0.003). A higher percentage of non-stimulated GTMC from EOP patients produced IL-4 than from GC (22 +/- 4% vs. 6 +/- 3%, P < 0.00007), as well as when stimulated with P. gingivalis (22 +/- 3% vs. 13 +/- 2%, P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adsorption↗
PubMed1993

Solubilisation partial characterisation of the alpha-MSH receptor on primary rat Schwann cells.

The ACTH/MSH melanocortin core peptide sequence possesses neurotrophic properties in peripheral nerve. During functional neuroanatomical recovery after damage to peripheral nerves, Schwann cells play a significant role in facilitating regeneration. Here we employ a modified super-potent alpha-MSH analogue to solubilise alpha-MSH receptor proteins from cultured primary rat Schwann cells. [125I-Tyr2,Nle4,D-Phe7,ATB-Lys11]-alpha-MSH photoaffinity labelled proteins from Schwann cells were analyzed by SDS-PAGE followed by autoradiography. The results indicate that the alpha-MSH receptor proteins labelled have a molecular weight of 42-45 kDa. These data are the first to demonstrate solubilisation and characterisation of alpha-MSH receptors from non-melanoma cells.

Amino Acid Sequence↗
PubMed1993

HLA-D and T lymphocyte reactivity to specific periodontal pathogens in type 1 diabetic periodontitis.

Bacterial antigen fragments complexed with class II major histocompatibility molecules (HLA-D) on antigen presenting cells (APCs) stimulate CD4+ T lymphocyte proliferation, presumably to protect the host. This study examined these responses to antigens of two periodontal pathogens in four groups (n = 15) of age- (young adult) and sex-matched Caucasian subjects with or without type 1 diabetes and moderate to severe periodontitis: Group DP = diabetics with periodontitis; Group DnP = diabetics without periodontitis; Group nDP = nondiabetics with periodontitis; and Group nDnP = nondiabetics without periodontitis. HLA-D phenotypes for each subject were determined by lymphocytotoxicity assays. T lymphocytes purified from peripheral blood were stimulated in cell culture with APC pulsed with various concentrations of tetanus toxoid, Porphyromonas gingivalis, and Capnocytophaga sputigena antigens. T lymphocyte reactivity (3H thymidine incorporation) was numerically lower in cultures from diabetics stimulated with unpulsed APC (not significant), and antigen-pulsed cultures showed low proliferation and no significant differences among groups. Stimulation indices in cultures from diabetic patients stimulated with P. gingivalis or C. sputigena, however, were significantly elevated at all antigen concentrations compared to nondiabetic cultures. The occurrence of HLA-DR4 was moderately associated with diabetes (P < 0.05) and highly associated with periodontitis (P < 0.001, log-linear model for categorical variables); and HLA-DR53 and HLA-DQ3 were significantly associated with periodontitis (P < or = 0.02). HLA-DR was crucial to lymphocyte stimulation (anti-HLA-DR blocking experiments), but the low peripheral blood T cell reactivity to antigens of periodontal pathogens could not be linked with HLA-D type or periodontitis susceptibility.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Serum antibody responses in human periodontitis to cellular components of Capnocytophaga.

Serum levels of IgM, IgG and IgG-antibody subclasses directed against cell envelopes, lipopolysaccharides and cytoplasmic fractions from Capnocytophaga sputigena, C. gingivalis and C. ochracea were examined in age-, race- and sex-matched periodontally healthy (n = 25) subjects and subjects with adult periodontitis (n = 25). The envelopes and cytoplasmic fractions were obtained by ballistic disintegration of the cells and ultracentrifugation. Cell envelopes were treated with DNase, RNase and lysozyme. Lipopolysaccharides were obtained by hot phenol-water extraction and treated with DNase and RNase. The relative levels of the antibodies in response to the cell fractions were measured by the streptavidinbiotin micro enzyme-linked immunosorbent assay. Both groups showed IgM and IgG antibodies to each fraction of the three Capnocytophaga species, but the frequency of positive IgG subclass responses varied. The IgG4 responses were lower than the other subclasses. There were no significant differences between the IgM antibody levels of the two groups. However, the adult periodontitis group had significantly lower IgG antibody titres to the cell envelopes and cytoplasmic fractions of C. gingivalis and C. ochracea, and lipopolysaccharide of C. gingivalis. These results were reflected in the depressed levels of IgG1 and/or IgG2 to these cellular fractions from the same bacterial species. The adult periodontitis group also showed a lower level of IgG1 to the cytoplasmic fractions of C. sputigena without any depression in the total IgG antibody level. There were no significant differences between the groups in IgG3 and IgG4 antibody levels to any of the cellular fractions.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Bacterial↗
PubMed1991

Acute-phase protein detection and quantification in gingival crevicular fluid by direct and indirect immunodot.

The development of an assay for markers of active periodontitis, obtained directly from gingival crevicular fluid (GCF) and simply quantified, would be of great importance to the dental practitioner. The purpose of this study was to evaluate direct and indirect immunodot techniques as to their potential in easily quantifying acute-phase proteins within periodontally diseased and healthy site GCF. Indirect immunodots (GCF eluates dotted onto nitrocellulose membrane) using monoclonal antibodies and a radioactive isotope label were used to identify and establish relative amounts of C-reactive protein (CRP) and alpha-2-macroglobulin (A2M) in 2 diseased and 2 healthy sites in 24 periodontitis patients. Periodontally diseased sites were found to contain significantly lower concentrations of A2M than healthy sites (p less than 0.001), but CRP levels did not vary significantly between healthy and diseased locations. Using a direct immunodot assay (GCF absorbed directly into nitrocellulose membrane strips), A2M levels quantified with radioactive isotopes at healthy and diseased sites could be correlated with A2M levels determined by enzyme-linked antibody-colormetric probes at those same sites. Such a direct sampling and quantification system shows promise for future "in-office" diagnostic methodology.

Acute-Phase Proteins↗
PubMed1990

Intracrevicular application of tetracycline in white petrolatum for the treatment of periodontal disease.

In vitro tests in our laboratory have shown that 40% tetracycline HCl in a white petrolatum carrier (TTC-WP) has potential as a sustained release, autodissipating system. The present study tested subgingival placement of TTC-WP via syringe in vivo. Quadrants (2 diseased sites in each) in 9 patients with moderate/severe periodontitis were randomly assigned to receive the following treatments: (1) TTC-WP; (2) WP only; (3) scaling and root planing; (4) untreated control. TTC release into gingival crevicular fluid (GCF) over time (baseline, 1, 8, 24, 72 and 168 h) was measured using an agar diffusion bioassay. Clinical parameters and subgingival bacterial morphotypes (darkfield analysis) were also evaluated over time (baseline, 2, 4, 8, 12 weeks). Results indicated that TTC-WP was easily placed into periodontal pockets and biologically effective TTC was released into GCF for at least 3 days (mean concentration = 115.8 +/- 43.1 micrograms/ml at 3 days). TTC-WP reduced probing pocket depths and bleeding on probing relative to baseline measurements for 8-12 weeks post-treatment, and reduced %s of motile rods and spirochetes, with an accompanying increase in cocci, for 2-8 weeks. Similar effects were noted in the scaled and root-planed sites, but for a longer duration. TTC-WP and WP were clinically dissipated after 2 weeks and no adverse tissue reactions were observed. From these findings, subgingival TTC-WP cannot replace scaling and root planing therapy, but has characteristics useful in subgingival plaque control.

Administration, Topical↗
PubMed1988

Evaluation of four modalities of periodontal therapy. Mean probing depth, probing attachment level and recession changes.

Eighty-two periodontally involved patients were treated in a split mouth design such that one quadrant received coronal scaling (CS), root planing (RP), modified Widman surgery (MW), and flap with osseous resection surgery (FO). The therapy was performed in three phases: Phase I: the teeth previously designated to receive RP, MW, and FO were thoroughly root planed and the teeth designated to receive CS were scaled with no subgingival instrumentation, plaque control was initiated and reinforced for the entire mouth; Phase II: the designated teeth received MW or FO surgery; and Phase III: maintenance therapy every three months. The CS teeth received coronal scaling and polishing during maintenance appointments, while RP, MW, and FO teeth received supragingival instrumentation, subgingival instrumentation and polishing. Clinical measurements were taken initially, four weeks post-Phase I, 10 weeks post-Phase II, and after each of two years of maintenance care. All therapy modalities resulted in a decrease of mean probing depth with the FO producing the greatest decrease followed by MW, RP, and CS. The deeper the initial probing depth, the greater was the mean reduction of probing depth. FO created a loss of mean probing attachment in the 1 to 4 mm category. RP and MW produced the greatest gain of mean probing attachment in the 5 to 6 mm category. RP, MW, and FO produced similar gains in the greater than or equal to 7 mm category. FO created the most gingival recession followed by MW, RP, and CS.

Adult↗
PubMed1987

The response of human pulpal tissue after orthodontic force application.

Previous investigations have dealt with significant alterations in pulpal respiration associated with dental materials and methods. The purpose of this investigation was to note if significant alterations in pulpal respiration remained after the insult had been removed. A rest period of 1 week was chosen to evaluate the pulpal respiration response after application of an initial 72-hour orthodontic force. A radiorespirometric method was used to determine differences in experimental and control pulpal tissue respiration rates within individuals. These data showed that the mean respiration rates of experimental pulpal tissue compared with control pulpal tissue remained depressed approximately 33.2% after the 7-day rest period. However, it was found upon further investigation that there were really two groups present--one that had returned to normal respiration rates and one that did not within a 1-week rest period. Age and apical opening size correlated with the return of the respiration rates to normal during the 1-week rest period. Age was negatively correlated with respiration rate and apical opening size correlated with the return of the respiration rates to normal during the 1-week rest period. Age was negatively correlated with respiration rate and apical opening size was positively correlated with respiration rate.

Adolescent↗
PubMed1987

Localization of acid phosphatase activity in Giardia lamblia and Giardia muris trophozoites.

Numerous membrane-bounded vacuoles are found adjacent to the plasma membrane of the pathogenic protozoan Giardia lamblia. The function of these vacuoles has been discussed by several authors. Approximately 100-400 nm in diameter with a core of low electron density, they have been suggested to be mitochondria, mucocysts, lysosomes, and endocytotic vacuoles. Enzyme cytochemical localization for acid phosphatase activity using cerium as a capturing agent demonstrates reaction product in these vacuoles as well as in the endoplasmic reticulum and nuclear envelope cisternae. The distribution of reaction product suggests the vacuoles are lysosome-like; however, their function and development remain in question.

Acid Phosphatase↗
PubMed1985

Induction of spheroplasts in Capnocytophaga ochracea.

A gentle technique for preparing spheroplasts of Capnocytophaga ochracea strain 25 is described. Cells in the exponential phase were washed with 1.0 M-NaCl, agitated in 1.0 M-NaCl for 2 h at 30 degrees C and exposed to lysozyme in a Tris/salts buffer, pH 7.0. This procedure resulted in 98% spheroplast formation with complete removal of the peptidoglycan layer as detected by both phase-contrast and electron microscopy in combination with chemical analysis.

Capnocytophaga↗
PubMed1985

Purification and chemical characterization of an exopolysaccharide isolated from Capnocytophaga ochracea.

Purification and chemical characterization of an immunosuppressive exopolysaccharide from Capnocytophaga ochracea strain 25 are described. This polysaccharide was extracted from spent culture medium by cold ethanol precipitation. Purification was accomplished by trichloroacetic acid and pronase treatments in combination with diethylaminoethyl-Sepharose and concanavalin A-Sepharose chromatography. Purity of the exopolysaccharide was ascertained by polyacrylamide gel electrophoresis using periodic acid--Schiff staining. The exopolysaccharide was free of protein, nucleic acid, and lipopolysaccharide, but contained large amounts of mannose with lesser quantities of glucose, galactose, glucuronic acid, and glucosamine.

Capnocytophaga↗
PubMed1983

Suppression of murine lymphocyte mitogen responses by exopolysaccharide from Capnocytophaga ochracea.

An extracellular polysaccharide was purified from culture supernatants of Capnocytophaga ochracea 25, a gram-negative bacillus associated with human periodontal disease. The extracellular polysaccharide suppressed in vitro mitogenic responses of murine splenic lymphocytes to concanavalin A and lipopolysaccharide. This suppression wad dose dependent, persisted up to 120 h, and was not caused by direct toxicity of the extracellular polysaccharide.

Animals↗