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Biomedical subjects

J A Mayo

Publications and source records attributed to J A Mayo.

At least 19 recordsLinked to original sources
PubMed2006

Inhibition of Porphyromonas gingivalis proteinases (gingipains) by chlorhexidine: synergistic effect of Zn(II).

BACKGROUND/AIMS: Gingipains, proteolytic enzymes produced by the periodontal pathogen Porphyromonas gingivalis, are regarded as virulence factors in the pathogenesis of periodontitis. Inhibition of gingipain activity therefore may have therapeutic potential, and it has been suggested that chlorhexidine may inhibit the activities of these enzymes. The purposes of the present study were to examine systematically the inhibitory effects of chlorhexidine on three purified gingipains and to determine the effect of Zn(II) on chlorhexidine inhibition. METHODS: The activities of lys-gingipain (Kgp) and two forms of arg-gingipain (RgpB and HRgpA) were measured in the presence of varying concentrations of chlorhexidine and with chlorhexidine supplemented with Zn(II). Inhibition constants (K(i)'s) were determined for chlorhexidine alone and in the presence of Zn(II). Fractional inhibitory constant indices were calculated to assess the synergy of the chlorhexidine-Zn(II) inhibition. RESULTS: RgpB, HRgpA, and Kgp were all inhibited by chlorhexidine with K(i)'s in the micromolar range. For RgpB and HRgpA, the inhibitory effects of chlorhexidine were enhanced 3-30-fold by Zn(II). The chlorhexidine-Zn(II) interaction was synergistic for inhibition of HRgpA and RgpB. For Kgp, the effect of Zn(II) on chlorhexidine inhibition was antagonistic. CONCLUSIONS: Chlorhexidine is an effective inhibitor of gingipains, and the inhibition of R-gingipains is enhanced by Zn(II). A mixture of chlorhexidine and Zn(II) may be useful as an adjunct in the treatment of periodontitis and in the post-treatment maintenance of periodontitis patients.

Adhesins, Bacterial↗
PubMed2005

Characterization of an extracellular dipeptidase from Streptococcus gordonii FSS2.

PepV, a dipeptidase found in culture fluids of Streptococcus gordonii FSS2, was purified and characterized, and its gene was cloned. PepV is a monomeric metalloenzyme of approximately 55 kDa that preferentially degrades hydrophobic dipeptides. The gene encodes a polypeptide of 467 amino acids, with a theoretical molecular mass of 51,114 Da and a calculated pI of 4.8. The S. gordonii PepV gene is homologous to the PepV gene family from Lactobacillus and Lactococcus spp.

Amino Acid Sequence↗
PubMed2002

Extracellular arginine aminopeptidase from Streptococcus gordonii FSS2.

Streptococcus gordonii is a primary etiological agent in the development of subacute bacterial endocarditis (SBE), producing thrombus formation and tissue damage on the surfaces of heart valves. This is ironic, considering its normal role as a benign inhabitant of the oral microflora. However, strain FSS2 of S. gordonii has been found to produce several extracellular aminopeptidase- and fibrinogen-degrading activities during growth in a pH-controlled batch culture. In this report, we describe the purification, characterization, and partial cloning of a predicted serine class arginine aminopeptidase (RAP) with some cysteine class characteristics. Isolation of this enzyme by anion-exchange, gel filtration, and isoelectric focusing chromatography yielded a protein monomer of approximately 70 kDa, as shown by matrix-assisted laser desorption ionization, gel filtration, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis under denaturing conditions. Nested-PCR cloning enabled the isolation of a 324-bp-long DNA fragment encoding the 108-amino-acid N terminus of RAP. Culture activity profiles and N-terminal sequence analysis indicated the export of this protein from the cell surface. Homology was found with a putative dipeptidase from Streptococcus pyogenes and nonspecific dipeptidases from Lactobacillus helveticus and Lactococcus lactis. We believe that RAP may serve as a critical factor for arginine acquisition during nutrient stress in vivo and also in the proteolysis of host proteins and peptides during SBE pathology.

Amino Acid Sequence↗
PubMed2001

Novel extracellular x-prolyl dipeptidyl-peptidase (DPP) from Streptococcus gordonii FSS2: an emerging subfamily of viridans Streptococcal x-prolyl DPPs.

Streptococcus gordonii is generally considered a benign inhabitant of the oral microflora, and yet it is a primary etiological agent in the development of subacute bacterial endocarditis (SBE), an inflammatory state that propagates thrombus formation and tissue damage on the surface of heart valves. Strain FSS2 produced several extracellular aminopeptidase and fibrinogen-degrading activities during growth in culture. In this report we describe the purification, characterization, and cloning of a serine class dipeptidyl-aminopeptidase, an x-prolyl dipeptidyl-peptidase (Sg-xPDPP, for S. gordonii x-prolyl dipeptidyl-peptidase), produced in a pH-controlled batch culture. Purification of this enzyme by anion exchange, gel filtration, and hydrophobic interaction chromatography yielded a protein monomer of approximately 85 kDa, as shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (PAGE) under denaturing conditions. However, under native conditions, the protein appeared to be a homodimer on the basis of gel filtration and PAGE. Kinetic studies indicated that purified enzyme had a unique and stringent x-prolyl specificity that is comparable to both the dipeptidyl-peptidase IV/CD26 and lactococcal x-prolyl dipeptidyl-peptidase families. Nested PCR cloning from an S. gordonii library enabled the isolation and sequence analysis of the full-length gene. A 759-amino-acid polypeptide with a theoretical molecular mass of 87,115 Da and a calculated pI of 5.6 was encoded by this open reading frame. Significant homology was found with the PepX gene family from Lactobacillus and Lactococcus spp. and putative x-prolyl dipeptidyl-peptidases from other streptococcal species. Sg-xPDPP may serve as a critical factor for the sustained bacterial growth in vivo and furthermore may aid in the proteolysis of host tissue that is commonly observed during SBE pathology.

Amino Acid Sequence↗
PubMed2001

pH-regulated secretion of a glyceraldehyde-3-phosphate dehydrogenase from Streptococcus gordonii FSS2: purification, characterization, and cloning of the gene encoding this enzyme.

Streptococcus gordonii and other viridans streptococci (VS) are primary etiologic agents of infective endocarditis, despite being part of the normal oral microflora. Recently, a surface-bound glyceraldehyde-3-phosphate dehydrogenase (GAPDH) has been found on the cells of all tested streptococcal species, where it has been implicated as a virulence factor. In contrast, we observed that a soluble extracellular GAPDH was the major secreted protein from S. gordonii FSS2, an endocarditis strain. The biochemical properties and gene sequence of S. gordonii GAPDH are almost identical to those of other streptococcal GAPDHs. Growth at defined pHs showed that secretion of GAPDH is regulated by environmental pH. GAPDH was primarily surface-associated at growth pH 6.5 and shifted to > 90% secreted at growth pH 7.5. Others have identified S. gordonii promoters that are up-regulated by a pH shift similar to that experienced by organisms entering the blood stream (neutral) from the oral cavity (slightly acid). Analysis of our results suggests that secretion of GAPDH may be a similar adaptation by S. gordonii.

Adaptation, Physiological↗
PubMed2001

Isolation and characterization of a highly specific serine endopeptidase from an oral strain of Staphylococcus epidermidis.

Infection by Staphylococcus epidermidis, an opportunistic pathogen, has become a major problem due to the increased use of implanted medical devices and the growing number of patients who are therapeutically or infectiously immunosuppressed. These infections appear to proceed via modulation of the coagulation and complement systems. In this communication we describe the purification and characterization of a novel extracellular proteinase from an oral strain of S. epidermidis that can degrade fibrinogen, complement protein C5, and several other proteins. This proteinase has a strong preference for cleavage after glutamic acid residues, but not after aspartic acid. The S. epidermidis enzyme may be a multifunctional protein which not only provides this organism with both the ability to evade the complement defense system and to dysregulate the coagulation cascade, but also supplies nutrients for its growth through the degradation of Glu-rich proteins.

Amino Acid Sequence↗
PubMed1999

beta-Hemolytic streptococci and other beta-hemolytic organisms in apical periodontitis and severe marginal periodontitis.

Thirteen teeth with necrotic pulps and apical periodontitis and nine severe periodontal pockets were cultured for presence of beta-hemolytic streptococci and other beta-hemolytic organisms. Samples were dispersed and plated on two non-selective and one selective growth media and incubated anaerobically and in 10% CO2 in air. A total of 59 beta-hemolytic colonies were purified and identified. Eight beta-hemolytic streptococcal isolates were obtained from three of the severe marginal periodontitis sites. All were identified as belonging to the Streptococcus sanguis group. No beta-hemolytic streptococci were detected in apical periodontitis samples. Twenty obligately anaerobic isolates were detected, all of which were known periodontal and endodontic pathogens. Isolates from apical periodontitis sites were identified as Propionibacterium acnes, Actinomyces naeslundii, Actionomyces odontolyticus and Peptostreptococcus micros, while severe marginal periodontal sites contained the same species with the addition of Actinomyces viscosus and Actinomyces meyeri. Of 19 staphylococci and micrococci, Staphylococcus epidermidis was the predominant isolate in both apical periodontitis and severe marginal periodontitis sites. However, less commonly known organisms such as Staphylococcus cohnii and Micrococcus sp. were identified in severe marginal periodontitis sites. The isolation of Bacillus sp. (12 isolates) in one severe marginal periodontitis and two apical periodontitis subjects was especially interesting, warranting consideration of this organism as a legitimate isolate and potential pathogen in oral disease.

Bacillus↗
PubMed1999

Effect of in-line bacteriological filters on numbers of heterotrophic bacteria in water emitted from non-autoclavable dental air-water syringes.

PURPOSE: To determine the effect of in-line bacteriological filters on the heterotrophic bacterial count of water from non-autoclavable dental air-water syringes. MATERIALS AND METHODS: In-line bacteriological filters were placed in the waterlines of non-autoclavable dental air-water syringes. Filters were placed either as close as possible to the air-water syringe or at a distance of approximately 6 feet (1.8 meters) from the air-water syringe. After routine flushing of water lines and air-water syringes, water samples were collected aseptically. Samples were diluted, plated on NWRI agar, and incubated, and numbers of heterotrophic bacteria per ml were determined. RESULTS: Filtration substantially reduced heterotrophic contamination of air-water syringe water when the filter was placed immediately adjacent to the air-water syringe. However, there was no beneficial effect when the filter was at a distance from the air-water syringe. Furthermore, filtered water containing no detectable heterotrophic bacteria was re-contaminated upon passage through the non-autoclavable air-water syringe.

Colony Count, Microbial↗
PubMed1995

Modulation of glycosidase and protease activities by chemostat growth conditions in an endocarditis strain of Streptococcus sanguis.

The effects of growth conditions on the properties of the endocarditis-producing oral bacterium Streptococcus sanguis FSS2 were studied. This strain produces a variety of proteases and glycosidases, including a thrombin-like activity that is a potential virulence factor for endocarditis. Cultures were grown with limiting glucose or galactose in chemostats over a range of dilution rates and pH levels, and the following activities were measured at pH 7.5: thrombin-like, Hageman factor-like, N-acetyl-beta-D-galactosaminidase, beta-D-glucosidase, and beta-D-galactosidase. At growth pH 6.5, specific activities generally decreased as the dilution rate increased from 0.05 to 0.40 h(-1). At a dilution rate of 0.1 h(-1), specific activities generally were highest at growth pH 6.5 and lower and approximately equal at growth pH 5.5 and 7.5. The major exception was the thrombin-like activity, for which the specific activity at growth pH 7.5 was approximately 5-fold higher than at growth pH 5.5. Hageman factor-like activity was apparently glucose catabolite repressible, as its activity was 3-fold higher in galactose cultures. The measured activities changed as functions of growth conditions and thus were modulated by environment. Environmental regulation of thrombin-like activity by pH is consistent with an activity that is less important on tooth surfaces than in tissues.

Adaptation, Physiological↗
PubMed1994

Reduction of caries and of demineralization around orthodontic brackets: effect of a fluoride-releasing resin in the rat model.

The effectiveness of fluoride in reduction of caries is well known. This study examined the ability of a fluoride-releasing resin to reduce caries, as well as demineralization around orthodontic brackets, by using the Sprague-Dawley rat as a model. Eighteen-day-old rats were infected with cariogenic Streptococcus sobrinus 6715. After infection was confirmed, standard orthodontic techniques were used to bond miniature orthodontic brackets to the lingual surfaces of maxillary first molars, with either a fluoride-releasing resin (group I) or a conventional resin (group II). A control group was infected but not bonded (group III). Bonding was done at age 34 days. Rats were fed a cariogenic diet and were killed at age 72 days. Lingual surfaces of maxillary first molars were evaluated for area of demineralization, and mandibular molars were scored for caries. Mean percent area of demineralization for group I was 4.7%, for group II 35.7%, and for group III 0%. The difference between groups I and II was statistically significant (p < 0.01). Mean mandibular molar enamel carious lesion unit count for group I was 9.8, for group II 16.3, and for group III 13.7. Group I had significantly fewer lesions than groups II and III (p < 0.01), and group II had significantly more lesions than group III (p < 0.01). These results indicate that a fluoride-releasing resin reduces demineralization at the site of application and reduces caries at distant sites in the experimental rat model.

Animals↗
PubMed1994

Prevention of root caries with dentin adhesives.

This in vitro investigation determined the feasibility of using dentin adhesives to protect root surfaces against caries. The roots of 22 recently extracted human teeth were all painted with a protective lacquer leaving two unprotected small windows. On each specimen, one window (control) was left untreated and the other window (experimental) was treated using a dentin adhesive (Scotchbond Multi-Purpose). The roots were then immersed in an in vitro acetate/calcium/phosphate demineralization model at pH 4.3. After 70 days, the samples were removed and sectioned through the windows. The undecalcified ground sections were examined under transmitted and polarized light. Lesions characteristic of natural root caries were seen in the untreated control windows. No such lesions were apparent in the experimental windows. The results of this preliminary study suggest that dentin adhesives may provide protection against root caries.

Dentin-Bonding Agents↗
PubMed1992

Effects of the Nd:YAG dental laser on plasma-sprayed and hydroxyapatite-coated titanium dental implants: surface alteration and attempted sterilization.

The Nd:YAG dental laser has been recommended for a number of applications, including the decontamination or sterilization of surfaces of dental implants that are diseased or failing. The effects of laser irradiation in vitro (1) on the surface properties of plasma-sprayed titanium and plasma-sprayed hydroxyapatite-coated titanium dental implants, and (2) on the potential to sterilize those surfaces after contamination with spores of Bacillus subtilis have been examined. Surface effects were examined by scanning electron microscopy, energy dispersive spectroscopy, and x-ray diffraction after laser irradiation at 0.3, 2.0, and 3.0 W using either contact or noncontact handpieces. Controls received no laser irradiation. Melting, loss of porosity, and other surface alterations were observed on both types of implants, even with the lowest power setting. For the sterilization study, both types of implants were first sterilized by exposure to ethylene oxide and then contaminated with spores of B subtilis. After laser irradiation, the implants were transferred to sterile growth medium and incubated. Laser irradiation did not sterilize either type of implant. The spore-contaminated implants in the control group were successfully sterilized with ethylene oxide.

Bacillus subtilis↗
PubMed1991

PDQ-R personality disorders in bipolar patients.

The prevalence of personality traits and disorders in bipolar patients as reported in the literature varies widely. The Personality Diagnostic Questionnaire-Revised (PDQ-R) is a self-report instrument for DSM-IIIR personality disorders found to have validity, but with high sensitivity and moderate specificity. This study was designed to assess personality disorders in bipolar patients using the PDQ-R. Fifty bipolar patients in a long-term lithium treatment program completed the PDQ-R. Over one half the patients (58%) scored for one or more personality disorders. A total of 71 diagnoses was made among the 50 patients, or a mean of 1.42 per patient. The majority of the axis II diagnoses were from cluster B, with borderline the most prevalent, followed by histrionic. The PDQ-R has high sensitivity but moderate specificity and may overdiagnose personality disorders in bipolar patients. The PDQ-R may register subclinical aspects of affective disorder as personality.

Adult↗
PubMed1991

Outcome of bipolar disorder on long-term treatment with lithium.

The long-term treatment outcome of 248 bipolar patients in an out-patient lithium programme was assessed. Over half of the patients (138 or 56%) had no affective episodes in the year observed. Patients were divided into outcome groups according to GAS scores: the outcome for 40% of patients was good, for 41% fair, and for 19% poor. More frequent psychiatric admissions before starting lithium treatment was the best predictor of poor outcome, followed by a negative affective style in the family and lower social class. Current alcohol and drug abuse was associated with poor outcome. Although familial and psychosocial factors were significantly associated with outcome, the findings suggest there may be inherent differences in the pathophysiology of bipolar disorder reflected in an increased frequency of episodes which account for a large variance in lithium treatment outcome.

Adult↗
PubMed1991

Subgingival bacteria associated with hydroxylapatite-coated dental implants: morphotypes and trypsin-like enzyme activity.

This study investigated the colonization of teeth and hydroxylapatite-coated dental implants by different groups of oral bacteria. Periodontal and gingival health were assessed and subgingival plaque samples were taken. Bacterial morphotypes in subgingival plaque samples were enumerated and expressed as percent of bacteria counted, and presence of trypsin-like enzymes was detected by hydrolysis of benzoyl-arginine naphthylamide (BANA). For both pooled and separate implant and teeth data, positive correlations were found between pocket depth and both BANA hydrolysis and percent spirochetes, and a negative correlation was found between pocket depth and percent cocci. With one exception, analysis of variance revealed no significant differences between implants and teeth for presence of bacterial morphotypes when considering both periodontal and gingival health.

Adult↗
PubMed1989

Comparison of properties of collected cells and cells from the culture vessel during continuous culture of Streptococcus mutans Ingbritt.

In continuous-culture studies chemostat effluents are usually collected into a receiving flask in an ice bath to obtain enough cells for an experiment. It is assumed that the properties of these are not significantly different from those of the culture in the chemostat vessel. This assumption has been tested for the dental pathogen Streptococcus mutans Ingbritt. Collected supernatant fluid and cells were compared with supernatant fluid and cells taken directly from the culture vessel, for four major groups of culture properties: viability and biomass, concentrations of metabolites and nutrients, activities of selected enzymes, and glycolytic rates. The assumption held true except for glycolytic rate during endogenous metabolism. It is suggested that comparison of collected and culture vessel cells is an important control which should be done in all continuous culture studies of microbial physiology and biochemistry, but that the properties of Strep. mutans cells collected on ice up to 16 h do reflect those of cells actively growing in the chemostat.

Bacteriological Techniques↗
PubMed1988

The role of social factors in affective disorders: a review.

A number of researchers, dissatisfied with traditional models of affective illness, have developed multidimensional systems models that more accurately reflect how genetic, biological, and social factors may interact to increase vulnerability or resilience to stressors and illness. The role of five social factors in this process--demographics, early childhood experiences, life events, social support, and families--is reviewed. Serious methodologic difficulties hamper the study of social factors in affective illness, prompting the authors to suggest that researchers develop a new research paradigm that attempts not only to quantify social factors but to understand their meaning to the individual.

Humans↗