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Biomedical subjects

R L Gregory

Publications and source records attributed to R L Gregory.

At least 19 recordsLinked to original sources
PubMed2002

Antibacterial and physical properties of resin modified glass-ionomers combined with chlorhexidine.

The purpose of this study was to determine the effect on mechanical properties and antimicrobial activity of the addition of chlorhexidine (CHX) to a resin modified glass-ionomer (Photac-fil, ESPE, Norristown, PA, USA). Chlorhexidine diacetate was combined with a resin modified glass-ionomer material at a concentration of 5%. The samples were tested for hardness, tensile strength and erosion at 24 h and 6-week intervals and for elution of CHX and antimicrobial activity weekly for 6 weeks. At 24 h there was no significant difference in hardness between the two groups, but at 6 weeks the resin modified glass-ionomer group was significantly harder than the CHX groups (P < 0.05). The diametral tensile strength test indicated no difference between the control and CHX groups at 24 h or at 6 weeks. The jet erosion test demonstrated significantly less erosion with the CHX group at 24 h but at 6 weeks the CHX group showed significantly more erosion than the control group. The chemical assay data demonstrated a peak elution of CHX at week 1 with residual amounts at weeks 2 and 3. The microbial data demonstrated that the CHX group had a significant reduction in Streptococcus mutans numbers for weeks 1-3, but after week 4 there was no difference between the glass-ionomer with and without CHX. The addition of CHX to resin modified glass-ionomer altered hardness and erosion of the resin-modified glass-ionomer, but because there are no material specifications, it is difficult to determine clinical implications. Chlorhexidine did significantly improve the antimicrobial effect of the glass-ionomer which was consistent with the chemical assay data. The results indicated that the addition of CHX to resin modified glass-ionomer material (Photac-fil) did not seriously degrade the physical properties during the time period tested and that the addition of CHX resulted in a greater reduction in S. mutans when compared with glass-ionomer alone.

Analysis of Variance↗
PubMed2001

Salivary immunoglobulin A antibodies to gp41 in human immunodeficiency virus-seropositive patients: lack of correlation with disease progression.

Mucous membranes are the main route of transmission of human immunodeficiency virus (HIV). Interestingly, some viral inhibitory activities have been found in saliva. The purpose of this study was to determine the level of salivary immunoglobulin A (IgA) antibodies to gp41 in HIV+ patients at various disease stages to identify whether gp41 was able to induce vigorous humoral responses. Unstimulated saliva samples were obtained from three groups of subjects (n=37): group A (HIV-), group B (HIV+, CD4+ <200/mm3), and group C (HIV+, CD4+ >200/mm3). IgA antibody levels to purified gp41 were determined by enzyme-linked immunosorbent assay (ELISA). Western blot analyses were performed using HIV+ saliva to confirm IgA reactivity to gp41. ELISA demonstrated that HIV+ subjects had higher IgA antibody to gp41 than HIV- individuals. No significant differences were noted between HIV+, CD4+ <200/mm3 and CD4+ >200/mm3 subjects. High (81.25%) IgA reactivity to gp41 was demonstrated by Western blotting of saliva from all HIV+ individuals. In conclusion, gp41 responses are important in the HIV disease process, as indicated by the high IgA levels and gp41 reactivity in saliva of HIV+ patients.

Acquired Immunodeficiency Syndrome↗
PubMed2001

Modified immunogenicity of a mucosally administered antigen.

Streptococcus mutans is present in the saliva of most individuals and is modified by salivary components bound to the cells. These saliva-bound S. mutans are swallowed, exposed to high levels of acidity in the stomach, and presented to the common mucosal immune system. Much effort has been directed to identifying the specific S. mutans antigens that the mucosal immune responses are directed against. However, little is known about the host-altered antigenic determinants that the mucosal immune system recognizes. The immunogenicity of gastrically intubated untreated S. mutans cells, cells coated with whole human saliva, cells treated with HCl (pH 2.0), and saliva-coated and acid-treated cells in mice was investigated. Saliva and serum samples were assayed by enzyme linked immunosorbent assay for immunoglobulin A (IgA) and IgG antibodies, respectively, against the untreated or treated S. mutans cells. In general, the levels of salivary IgA and serum IgG antibodies to the antigen against which the mice were immunized were significantly higher (P < or = 0.05). In addition, human saliva and serum samples from 12 subjects were assayed for naturally occurring antibody against the untreated or treated S. mutans cells. In every case, significantly higher reactivity was directed against the saliva-coated and acid-treated cells followed by the saliva-coated S. mutans. These results provide evidence for the altered immunogenicity of swallowed S. mutans in humans by coating native S. mutans antigens with salivary components and/or denaturing surface S. mutans antigens in the acidic environment of the stomach, which would lead to an immune response to modified S. mutans determinants and not to native S. mutans antigens.

Animals↗
PubMed2000

Neuro-archeology.

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Behavior↗
PubMed2000

A memo on Meno.

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Humans↗
PubMed2000

An In vitro microbial-caries model used to study the efficacy of antibodies to Streptococcus mutans surface proteins in preventing dental caries.

The first step for a pathogenic bacterium to initiate infection is via attachment (i.e., through surface determinants) to a suitable receptor. An in vitro microbial artificial-mouth model was used to test the efficacy of polyclonal antibodies to Streptococcus mutans cell surface proteins (CsAb) and a cell surface 59-kDa protein (59Ab) in preventing S. mutans colonization and carious lesion formation. In study 1, groups of 12 human teeth specimens were inoculated with S. mutans, which were incubated with different concentrations of CsAb (A1 [positive control], sterile saline, no antibody; A2, 0.007 mg of antibody protein/ml; and A3, 0.7 mg of antibody protein/ml) for 1 h at 37 degrees C. The negative control group (B1) was not infected and was incubated with Trypticase soy broth (TSB) without dextrose supplemented with 5% sucrose (TSBS). In study 2, the same study design was used except that 59Ab was used instead of CsAb, normal rabbit serum was used in the positive control group (A1), and TSB supplemented with 1% glucose was used as the nutrient to control for sucrose-dependent colonization. All groups were exposed for 4 days to circulating cycles of TSBS and TSB (study 1 and study 2, respectively; 30 min each, three times per day) and a mineral washing solution (21 h per day). Prior to each nutrient cycle, 1 ml of the appropriate CsAb or 59Ab solution was administered to each group and allowed to mix for 30 min before cycling was resumed. Data obtained by confocal laser scanning microscopy demonstrated the presence of a significantly smaller (P < 0.05) lesion area and a smaller total lesion fluorescence in group A3 than in group A1 for both studies. In study 1, group A2 had significantly smaller values than A1 for lesion depth and area. There were no significant differences between groups A2 and A3 for lesion area or between groups A1 and A2 for total lesion fluorescence. In study 2, there were no significant differences among groups A1 and A2 for lesion depth or between groups A2 and A3 for all of the parameters studied. In both studies, there were no significant differences between S. mutans plaque CFU numbers among any of the groups. These studies demonstrated the efficacy of CsAb and 59Ab in reducing primary caries development in this model, although the underlying mechanism remains unclear.

Antibodies, Viral↗
PubMed1999

Oral lichen planus: an immunohistochemical study of heat shock proteins (HSPs) and cytokeratins (CKs) and a unifying hypothesis of pathogenesis.

The expression of heat shock proteins HSP60 and HSP70 and cytokeratins CK1/10 and CK7/18 were compared in epithelium of oral lichen planus (OLP) lesions and oral fibromas using an avidin-biotin-peroxidase complex (ABC) immunohistochemical method. An immunostaining intensity distribution (IID) index was developed to assess staining intensity and the proportion of positively stained cells in different layers of the epithelium. The expression of HSP60 in the basal layer was significantly higher in OLP than in fibromas. No difference in HSP70 expression was evident between OLP and fibromas. The expression of CK1/10 in the epithelial basal and suprabasal layers was significantly higher in OLP than in fibromas. There was no demonstrable staining for CK7/18 in either OLP or fibromas. A significant correlation was evident between the expression of HSP60 and CK1/10 in the basal epithelial cells in OLP. The findings support a role for HSP60 in the pathogenesis of OLP. A unifying hypothesis of the pathogenesis of OLP, involving two sequential immune reactions, is proposed.

Adult↗
PubMed1999

Interactions of Streptococcus mutans fimbria-associated surface proteins with salivary components.

Streptococcus mutans has been implicated as the major causative agent of human dental caries. S. mutans binds to saliva-coated tooth surfaces, and previous studies suggested that fimbriae may play a role in the initial bacterial adherence to salivary components. The objectives of this study were to establish the ability of an S. mutans fimbria preparation to bind to saliva-coated surfaces and determine the specific salivary components that facilitate binding with fimbriae. Enzyme-linked immunosorbent assay (ELISA) established that the S. mutans fimbria preparation bound to components of whole saliva. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot techniques were used to separate components of whole saliva and determine fimbria binding. SDS-PAGE separated 15 major protein bands from saliva samples, and Western blot analysis indicated significant binding of the S. mutans fimbria preparation to a 52-kDa salivary protein. The major fimbria-binding salivary protein was isolated by preparative electrophoresis. The ability of the S. mutans fimbria preparation to bind to the purified salivary protein was confirmed by Western blot analysis and ELISA. Incubation of the purified salivary protein with the S. mutans fimbria preparation significantly neutralized binding of the salivary protein-fimbria complex to saliva-coated surfaces. The salivary protein, whole saliva, and commercial amylase reacted similarly with antiamylase antibody in immunoblots. A purified 65-kDa fimbrial protein was demonstrated to bind to both saliva and amylase. These data indicated that the S. mutans fimbria preparation and a purified fimbrial protein bound to whole-saliva-coated surfaces and that amylase is the major salivary component involved in the binding.

Amylases↗
PubMed1999

Intranasal immunization against dental caries with a Streptococcus mutans-enriched fimbrial preparation.

Streptococcus mutans has been identified as the major etiological agent of human dental caries. The first step in the initiation of infection by this pathogenic bacterium is its attachment (i.e., through bacterial surface proteins such as glucosyltransferases, P1, glucan-binding proteins, and fimbriae) to a suitable receptor. It is hypothesized that a mucosal vaccine against a combination of S. mutans surface proteins would protect against dental caries by inducing specific salivary immunoglobulin A (IgA) antibodies which may reduce bacterial pathogenesis and adhesion to the tooth surface by affecting several adhesins simultaneously. Conventional Sprague-Dawley rats, infected with S. mutans at 18 to 20 days of age, were intranasally immunized with a mixture of S. mutans surface proteins, enriched for fimbriae and conjugated with cholera toxin B subunit (CTB) plus free cholera toxin (CT) at 13, 15, 22, 29, and 36 days of age (group A). Control rats were either not immunized (group B) or immunized with adjuvant alone (CTB and CT [group C]). At the termination of the study (when rats were 46 days of age), immunized animals (group A) had significantly (P < 0.05) higher salivary IgA and serum IgG antibody responses to the mixture of surface proteins and to whole bacterial cells than did the other two groups (B and C). No significant differences were found in the average numbers of recovered S. mutans cells among groups. However, statistically fewer smooth-surface enamel lesions (buccal and lingual) were detected in the immunized group than in the two other groups. Therefore, a mixture of S. mutans surface proteins, enriched with fimbria components, appears to be a promising immunogen candidate for a mucosal vaccine against dental caries.

Administration, Intranasal↗
PubMed1999

Intranasal immunization confers protection against murine Pneumocystis carinii lung infection.

To evaluate the feasibility of mucosal immunization against Pneumocystis carinii (Pc) experimental infection, female BALB/c mice were intranasally immunized three times with soluble Pc antigens plus cholera toxin fraction B (Pc-CTB); control groups received either Pc antigen, CTB, or phosphate-buffered saline (PBS) alone. Two weeks after the last immunization, five animals from each group were sacrificed, and cellular and humoral immune responses were evaluated. The remaining five mice were CD4 depleted using a monoclonal antibody against mouse CD4 and inoculated with viable Pc. Significantly higher specific lymphoproliferative responses from tracheobronchial lymph node cells, immunoglobulin M (IgM) and IgG antibody levels in serum, and bronchoalveolar lavage (BAL)-derived IgA antibody concentrations were observed in the Pc-CTB group of mice relative to control groups (P < 0.01). Five weeks after challenge, no Pc organisms were observed in the lung smears of the Pc-CTB group, while the animals receiving antigen, adjuvant, or PBS had progressively higher numbers of Pc microorganisms. By Western blot analysis, a strongly reactive 55- to 60-kDa antigen was recognized by BAL IgA and by serum IgG. In summary, mucosal immunization elicited specific cellular and humoral immune responses and protected against Pc lung infection after immunosuppression.

Administration, Intranasal↗
PubMed1998

Differential activation of human neutrophils by Streptococcus mutans isolates from root surface lesions and caries-free and caries-active subjects.

Phagocytosis of bacterial pathogens is an important defense mechanism and may contribute to regulating Streptococcus mutans-induced dental caries, particularly at root surfaces. This study was undertaken to examine and compare differences in polymorphonuclear leukocyte or neutrophil activation by clinical isolates of S. mutans collected from the saliva of caries-free or caries-active individuals with S. mutans isolates from root surface lesions. S. mutans clinical isolates (5 caries-free, 5 caries-active, 5 root caries isolates and a laboratory strain) were incubated with neutrophils in the presence of normal human serum and the luminol dependent chemiluminescence was measured for 1 h at 37 degrees C. Results indicated that the caries active and laboratory strains activated neutrophils equally. The mean integration stimulated by caries-free strains, however, displayed a 25-30% enhanced neutrophil activation over the caries-active and laboratory strains. In contrast, neutrophil activation by root caries strains of S. mutans was 45-50% lower than all other S. mutans strains, possibly suggesting a natural selection for S. mutans strains that can evade neutrophil recognition and subsequent phagocytosis. Stimulation of neutrophils with the cell wall and membrane surface component preparations indicated that extracts from all four groups activated neutrophils significantly. Again, caries-free preparations activated neutrophils significantly more than caries active, laboratory strain and root caries isolates. This selection may become more important on root surfaces due to increased exposure to crevicular fluid and neutrophils. The data provide evidence for the presence or onset of mechanisms or biological alterations in S. mutans developed to circumvent neutrophil recognition and/or phagocytosis, thus increasing S. mutans survival and colonization on tooth surfaces, resulting in an enhanced risk of dental caries, particularly at root surfaces.

Adult↗
PubMed1997

Influence of heat inactivation of human serum on the opsonization of Streptococcus mutans.

Phagocytosis of bacteria, such as Streptococcus mutans, is important to host defense. One mechanism by which phagocytosis can be enhanced is by antibody or complement-mediated opsonization of bacteria. Many studies utilize opsonization of bacteria to enhance a cellular response, but little information has been found examining methodology or validity of the opsonization process following the denaturization of the serum. Human serum was inactivated by heat in order to disrupt the classical and alternative pathways of the complement cascade. S. mutans isolated from human subjects were opsonized with heat-inactivated human serum before exposing them to viable neutrophils in vitro. Luminol-dependent chemiluminescence (CL) was used to measure neutrophil activation. Human serum used to opsonize the bacteria was denatured by incubation at 57 degrees C for intervals of 30 and 60 min to inactivate complement. The results from the opsonization data indicated that there was significantly increased CL with 60-min inactivation of the serum (34% increase in mean integration mV.min; p < or = 0.05) over the nonopsonized control. This indicated a successful opsonization of the bacteria. In addition, the data demonstrate that the inactivation of serum requires a minimum of 60 min at 57 degrees C to disrupt the complement cascade, while 30- and 15-min inactivations produced no significant increase in CL activity over the control. Standard sandwich ELISA assays, detecting complement binding to S. mutans, confirmed successful heat inactivation of serum showing a significant decrease (p < or = 0.001) in complement binding to S. mutans after 30 min, but could not explain the increased CL response after 60-min heat deactivation of the serum.

Adult↗