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Biomedical subjects

B Guggenheim

Publications and source records attributed to B Guggenheim.

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

Caries and plaque inhibition in rats by five topically applied dentifrices.

The effectiveness of 5 different brands of dentifrices on caries and plaque were tested in rats in 2 experiments. 10 litters of rats each were infected with Streptococcus sobrinus OMZ-176 and Actinomyces viscosus Ny1. The rats were offered the diet 2000a containing either 40% of sucrose (study I) or 10% of sucrose (study II). The following products were tested topically: (1) H2O, (negative control); (2) chlorhexidine diacetate, (positive control); (3) Parodontax NF; (4) Meridol; (5) Colgate Total; (6) Mentadent C; (7) Dent Xpress. Comparisons with the water control in study I showed that plaque extent was decreased by chlorhexidine diacetate, Dent Xpress and by Mentadent C only. All fluoride-containing dentifrices tested reduced caries. In study II, comparisons with the water control showed that plaque extent was reduced by chlorhexidine diacetate, Parodontax, Meridol, Dent Xpress and by Mentadent C. All dentifrices reduced caries, however, the incidence was low. These 2 studies confirm that fluorides incorporated in dentifrices decrease dental caries in the rat. Differences in the effectiveness of caries inhibition between the 5 dentifrices could not be explained either by the form of fluoride utilized or by the antimicrobials added. Rather, the performance of a given dentifrice depended upon the concerted action of the particular ingredients. It appears that the effect of antiplaque agents should be evaluated in the rat model using a diet containing sucrose at a low level.

Actinomyces viscosus↗
PubMed1996

Treponema maltophilum sp. nov., a small oral spirochete isolated from human periodontal lesions.

A novel culture medium for cultivation of fastidious oral anaerobes is described. This medium, OMIZ-Pat, consists of a rich chemically defined basal medium supplemented with asialofetuin, as well as yeast extract and Neopeptone fractions. Addition of 1 mg of rifampin per liter and 100 mg of fosfomycin per liter allowed routine isolation of spirochetes by a limit dilution method in 96-well plates containing liquid OMIZ-Pat. In addition to members of the four previously recognized species of oral treponemes (Treponema denticola, Treponema pectinovorum, Treponema socranskii, and Treponema vincentii), 26 previously undescribed spirochete strains belonging to one group were isolated. We propose the name Treponema maltophilum sp. nov. for these small spirochetes, which have two endoflagella; one endoflagellum is attached at each cell pole, and the endoflagella overlap in the middle of the cell. Growth of these organisms was dependent on a carbohydrate like D-arabinose, L-fucose, D-maltose, L-rhamnose, D-ribose, D-sucrose, or D-trehalose and was inhibited by fetal bovine serum. T. Maltophilum is distinguished from other oral Treponema species by its 16S rRNA sequence, its protein and antigen patterns as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting, and its characteristic alpha-glucosidase activity. The strains included in the new species on the basis of their 16S rRNA sequences are heterogeneous with respect to their alpha-fucosidase, and beta-glucuronidase activities, their dependence on N-acetylglucosamine, and their antigens as detected with patient antibodies. Strain BR is designated the type strain, and strains HO2A and PNA1 are reference strains of the new species.

Antibodies, Bacterial↗
PubMed1996

Human root caries: microbiota of a limited number of root caries lesions.

The microbiota of root caries lesions of different grades of severity were studied. Fourteen lesions were examined. The experimental design of the study allowed correlation of histopathologically distinguishable stages with specific and distinct microbial populations. Dentin samples were ground in a sterile mortar and cultured anaerobically on nonselective Columbia blood agar plates supplemented with 5% hemolyzed human blood and on media selective for Lactobacillus spp. and streptococci. The cultivable microbiota were quantitatively speciated using Rapid ID 32A, Rapid ID 32 Strep, API 20 Strep, APIZYM, and API50 CH tests and SDS-PAG electrophoresis. In initial as well as in advanced lesions gram-positive bacteria accounted for approximately 90% of the CFUt. The proportion of Actinomyces, and in particular A. naeslundii was significantly higher (p < 0.05) in initial lesions than in advanced lesions. In contrast, the percentage of Streptococcus and especially S. mutans was higher (p < 0.05) in advanced than in initial lesions. Surprisingly low (0.8% of the CFUt) was the percentage of lactobacilli in advanced lesions. Gram-negative bacteria formed a minor part of the microbiota in both initial and advanced lesions. Among the gram-negative isolates, Prevotella, Selenomonas, and Bacteroides spp. were most noticeable. In advanced lesions, only the outermost layer of 0.5 mm thickness was populated by a high number of bacteria; the following segments harbored a negligible number of bacteria only. It is concluded that root caries is a continuous destruction process which is restricted to a subsurface zone of limited depth. The necrotic dentin is successively worn away, leading to a saucer-shaped cavitation which is repopulated by plaque. The creation of cavitations favors an aciduric flora. This might explain the succession of bacterial populations observed during the destruction process.

Actinomyces↗
PubMed1996

Incorporation of caseinoglycomacropeptide and caseinophosphopeptide into the salivary pellicle inhibits adherence of mutans streptococci.

The protective effects of milk and milk products against dental caries have been demonstrated in many animal studies. We have shown that this effect was mediated by micellar casein or caseinopeptide derivatives. A reduction in the Streptococcus sobrinus population in the oral microbiota of animals fed diets supplemented with these milk components was consistently observed. A possible explanation for these findings is that milk components are incorporated into the salivary pellicle, thereby reducing the adherence of S. sobrinus. This hypothesis was tested in vitro by the incubation of bovine enamel discs with unstimulated saliva. The resulting pellicle was washed and incubated with caseinoglycomacropeptide (CGMP) and/or caseinophosphopeptide (CPP) labeled with 17- and 12-nm gold particles. All samples were prepared for electron microscopy by high-pressure freezing followed by freeze-substitution. It was demonstrated by high-resolution scanning electron microscopy with back-scattered electron imaging, as well as by transmission electron microscopy, that both peptides were incorporated into the pellicle in exchange for albumin, confirming previous findings. This protein was identified with a mouse anti-human serum albumin followed by goat anti-mouse IgG labeled with 25-nm gold particles. Incorporation of CGMP and/or CPP into salivary pellicles reduced the adherence of both S. sobrinus and S. mutans significantly. It is suggested that the calcium and phosphate-rich micellar casein or caseinopeptides are incorporated into the pellicle. The resulting ecological shifts, together with the increased remineralization potential of this biofilm, may explain its modified cariogenic potential.

Adult↗
PubMed1996

Potential of diagnostic microbiology for treatment and prognosis of dental caries and periodontal diseases.

Most evidence suggests that only a finite number of bacteria are responsible for dental caries and periodontal diseases. This knowledge led to the development of microbial tests which can identify suspected pathogens. Current evaluation of the diagnostic power of microbial tests has shown that they have a low sensitivity and a low prognostic value. Despite these shortcomings, there are valid indications for microbiological-based diagnosis. Salivary microbial tests for the detection of mutans streptococci and lactobacilli may be useful, for example, in young children, oligosialic patients, and orthodontic patients. These tests can be used to monitor the success of chemopreventive measures or compliance with dietary recommendations. Microbial diagnosis, may also be valuable in the treatment of early-onset periodontitis or in subjects who respond poorly to periodontal therapy. The use of microbial tests to monitor the efficacy of chemotherapy or mechanical treatment is of particular interest.

Aggressive Periodontitis↗
PubMed1995

A 23 kDa membrane glycoprotein bearing NeuNAc alpha 2-3Gal beta 1-3GalNAc O-linked carbohydrate chains acts as a receptor for Streptococcus sanguis OMZ 9 on human buccal epithelial cells.

Streptococcus sanguis colonizes several human oral surfaces, including both hard and soft tissues. Large salivary mucin-like glycoproteins bearing sialic acid residues are known to bind various S.sanguis strains. However, the molecular basis for the adhesion of S.sanguis to human buccal epithelial cells (HBEC) has not been established. The present study shows that S.sanguis OMZ 9 binds to exfoliated HBEC in a sialic acid-sensitive manner. The desialylation of such cells invariably abolishes adhesion of S.sanguis OMZ 9 to the cell surface. A soluble glycopeptide bearing short sialylated O-linked carbohydrate chains behaves as a potent inhibitor of the attachment of S.sanguis OMZ 9 to exfoliated HBEC. The resialylation of desialylated HBEC with CMP-sialic acid and Gal beta 1,3GalNAc alpha 2,3-sialyltransferase specific for O-glycans restores the receptor function for S.sanguis OMZ 9, whereas a similar cell resialylation with the Gal beta 1,4GlcNAc alpha 2,6-sialyltransferase specific for N-glycans is without effect. Finally, the same resialylation reaction carried out with CMP-9-fluoresceinyl-sialic acid as a substrate yields exfoliated HBEC bearing fluorescence on a single 23 kDa protein, when using the alpha 2,3-sialyltransferase as the catalyst. The latter finding demonstrates that this 23 kDa cell surface glycoprotein bears NeuNAc alpha 2-3Gal beta 1-3GalNAc O-linked sugar chains, a carbohydrate sequence which is recognized by S.sanguis OMZ 9 on exfoliated HBEC. In similar experiments carried out with a buccal carcinoma cell line termed SqCC/Y1, S.sanguis OMZ 9 did not attach in great numbers to such cultured cells, and these cells were shown to not express membrane glycoprotein bearing alpha 2,3-sialylated O-linked carbohydrate chains.

Bacterial Adhesion↗
PubMed1995

The action of thymol on oral bacteria.

Several effects of thymol, a plant-derived antimicrobial agent, on Porphyromonas gingivalis, Selenomonas artemidis and Streptococcus sobrinus were examined. The extremely rapid efflux of intracellular constituents evoked by thymol is consistent with its postulated membranotropic effects. Correlations between leakage-inducing concentrations of thymol and minimal inhibitory concentrations and minimal bactericidal concentrations suggest that membrane perforation is a principal mode of action of this substance. The thymol-induced decline in intracellular ATP in S. sobrinus appears to be entirely attributable to leakage, whereas in P. gingivalis thymol may also inhibit ATP-generating pathways. Relative changes in the transmembrane potential of resting cells of S. sobrinus pulsed with glucose are as sensitive to thymol as is leakage from this organism. The effects of thymol on transmembrane potential are probably secondary to those arising from leakage of intracellular substances.

Adenosine Triphosphate↗
PubMed1995

Human root caries: microbiota in plaque covering sound, carious and arrested carious root surfaces.

The plaque microbiota covering sound or carious root surfaces were studied and compared with that covering arrested root caries lesions. From each of these categories five extracted teeth were examined. The experimental design of the study allowed us to relate the qualitative and quantitative microbial composition to the degree of integrity of the root surface. Plaque was sampled by a newly developed 'mowing' technique. Plaque samples were cultured anaerobically on nonselective Columbia blood agar plates supplemented with 5% hemolyzed human blood and on media selective for Lactobacillus spp. and streptococci of the mutans group. The cultivable microbiota were quantitatively speciated using Rapid ID 32A, Rapid ID 32 Strep, API 20 Strep, API ZYM, and API 50 CH tests and SDS-PAG electrophoresis. Regardless of the state of mineralization, the microbiota on all surfaces resembled marginal plaque associated with gingivitis. In addition to the gram-positive predominant facultative anaerobic genera Streptococcus, Staphylococcus, Lactobacillus and Actinomyces, gram-negative anaerobes, predominantly Bacteroides, Prevotella, Selenomonas, Fusobacterium, Leptotrichia, and Capnocytophaga, showed the highest isolation frequencies. On all surfaces Actinomyces spp. predominated, with streptococci and lactobacilli forming a minor part of the microbiota. With respect to the detected proportions of anaerobes, microaerophiles, Actinomyces naeslundii, Prevotella buccae and Selenomonas dianae, significant differences were observed between the three categories of root surfaces. The total CFU's on both caries-free and caries-active surfaces were significantly higher than on arrested lesions. In general, the results support a polymicrobial etiology for caries initiation on root surfaces, with A. naeslundii, Capnocytophaga spp., and Prevotella spp. making specific contributions to the processes of cementum and dentin breakdown.

Actinomyces↗
PubMed1995

[The Chemiklaven 7000/8000 on the test bench].

Sterilization of metal instruments in Chemiclaves is undoubtedly the most protective mode of sterilization, because corrosion and formation of spots is minimal. In the past sterilization with Chemiclaves was criticised, because of the emission of formaldehyde by older models and the questionable efficacy of formaldehyde sterilization for wrapped instruments. In the present investigation the capability of the newest Chemiclaves (7000/8000) to sterilize dental instruments was investigated. To monitor sterilization efficacy filter paper strips loaded with spores of Bacillus stearothermophilus or dental instruments directly contaminated with these spores were used as biological indicators. The performance of the Chemiclaves was assessed with and without a full load of instruments; after running half of the program cycle, the spore strips in the chamber being either unpacked or packed into paper bags. In addition it was investigated, whether it was feasible to use a formaldehyde free sterilization solution (Steri-Vap) with these sterilizers. The daily performance of the Chemiclaves in a dental practice and the emission of formaldehyde were tested in a room < 10 m3, in which both apparatus were operated at the same time. The Chemiclaves 7000/8000 sterilized reliably under the set test condition, however, the formaldehyde-free sterilization solution did not lead to an acceptable efficacy of sterilization. The new Chemiclaves efficiently adsorbed formaldehyde vapours. Harvey sterilizers require a meticulous observation of the producer's instruction, because in comparison to saturated steam the chemical vapours have a lower heat capacity. The Chemiclaves 7000/8000 are recommended for the sterilization of well cleaned, dry instruments wrapped in original MDT paper bags.

Dental Equipment↗
PubMed1994

In vitro modulation of oral bacterial adhesion to saliva-coated hydroxyapatite beads by milk casein derivatives.

Bovine caseinate, derivatives of its glycosylated moiety [caseinoglycomacropeptide (CGP)], and caseinophosphopeptides were evaluated as inhibitors of adhesion of oral bacteria to saliva-coated hydroxyapatite beads (S-HA). All milk casein-derived components behaved as potent inhibitors of Streptococcus sanguis OMZ 9 and Streptococcus sobrinus OMZ 176 adhesion to S-HA, whereas neither bovine serum albumin nor polyethyleneglycol were able to interfere with the adhesion of these strains. By contrast, none of the molecular species tested was able to inhibit the attachment of Actinomyces viscosus Ny 1 to S-HA. On the other hand, casein derivatives were shown to displace human serum albumin from S-HA beads. They were also able to bind to the bacterial cell surface of all strains examined. Collectively, these findings suggest that interactions between acidic casein-derived milk components and the biological surfaces involved in bacterial adhesion to S-HA result in an inhibitory effect that is selective for the oral streptococci examined.

Actinomyces viscosus↗
PubMed1994

The antimicrobial activity of essential oils and essential oil components towards oral bacteria.

A method for reproducibly determining minimal inhibitory concentrations and minimal bactericidal concentrations of plant extracts towards fastidiously and facultatively anaerobic oral bacteria, predicated upon measurements of optical densities in microtitre plate wells, was devised. The antimicrobial properties of some botanical oils were surveyed; of these, Australian tea tree oil, peppermint oil, and sage oil proved to be the most potent essential oils, whereas thymol and eugenol were potent essential oil components.

Actinomyces viscosus↗
PubMed1994

Interdental supragingival plaque--a natural habitat of Actinobacillus actinomycetemcomitans, Bacteroides forsythus, Campylobacter rectus, and Prevotella nigrescens.

The aim of this study was to test the hypothesis that suspected periodontal pathogens form a minor component of the supragingival plaque of individuals without periodontal diseases. Twenty-one dental hygienist trainees with a mean age of 23.5 years were twice sampled for interdental plaque between 1st and 2nd molars in all quadrants. The samples were assessed for Actinobacillus actinomycetemcomitans, Bacteroides forsythus, Campylobacter rectus, Porphyromonas gingivalis, and the Prevotella intermedia/Prevotella nigrescens group of organisms. Bacteria of this group were predominantly P. nigrescens and showed both the highest prevalence (100%) and the highest colonization density of the investigated species. Seven of 21 samples harbored A. actinomycetemcomitans. Serotypes a, b, and c were found in three samples each, while serotype e was present in one sample. Three subjects had two different A. actinomycetemcomitans serotypes. Bacteroides forsythus and C. rectus were detected in 10 (48%) and nine (43%) subjects, respectively. The detected cell numbers accounted for approximately 0.01% to 1% of the sampled flora. In contrast, P. gingivalis was found only in a single sample, which in addition harbored B. forsythus, C. rectus, A. actinomycetemcomitans (serotypes b and e), and P. intermedia. These results suggest that the investigated periodontal bacteria are not "exogenous pathogens", but amphibiotic, opportunistic microorganisms which may have a natural habitat in the supragingival plaque of the interproximal area of molars.

Adult↗
PubMed1994

Effects of blunt scaling on periodontal status and subgingival microorganisms. A pilot study.

Clinical and microbiological effects of 3 periodontal treatments were investigated: (i) scaling and root planing with sharp instruments combined with pocket flushing, (ii) scaling with blunt plastic curettes and pocket flushing, and (iii) pocket flushing alone. Clinically comparable, randomized sites of 8 patients with progressive adult periodontitis were treated 4 times in intervals of approximately 4 months. Prior to each re-treatment and at the end of the study all sites were clinically monitored and the subgingival microflora was examined. Results showed that all treatments were effective in reducing pocket depths and the subgingival microflora, while attachment levels remained unchanged. At individual sites treatment responses were of considerable heterogeneity. In general, clinically improving sites had strongly reduced and sites loosing > or = 3 mm of attachment high residual bacterial cell numbers. Sites with intermediate residual subgingival plaque levels showed quite variable clinical responses. This preliminary study suggests that weakly abrasive procedures could be very valuable for the initial treatment of periodontal lesions. This hypothesis should be further tested in comprehensive clinical trials.

Adult↗
PubMed1993

Seroclassification of hitherto nontypeable Actinobacillus actinomycetemcomitans strains: evidence for a new serotype e.

Serotyping of 89 Actinobacillus actinomycetemcomitans isolates by indirect immunofluorescence with serotype-specific monoclonal antibodies yielded 10 nontypeable strains. The aim of the present study was to re-evaluate the seroclassification of these strains with a different assay. Electroblotted antigens of nontypeable isolates and selected reference strains were immunostained with 37 human sera containing high antibody titers to A. actinomycetemcomitans. Such immunoblots typically showed an immunodominant, serotype-specific antigen smear. Twelve human sera were found to recognize specifically serotype a, 10 serotype b and 9 serotype c. Three sera contained antibodies to 2 or all 3 serotype antigens; 3 sera had no activity to any reference strain smear antigen. There was complete agreement between the seroclassification of the reference strains with the monoclonal and the polyclonal reagents. Seven of the 10 strains, nontypeable with monoclonal antibodies, could also not be typed by the human sera. Of the remaining 3 strains, one belonged to a previously unrecognized serovar of serotype a, and 2 isolates expressed a novel smear antigen detected by the 3 human sera containing no antibodies to the serotype a, b, or c antigens. We propose that these 2 strains be assigned to a new A. actinomycetemcomitans serotype, designated serotype e.

Aggregatibacter actinomycetemcomitans↗