bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of the Selective β2-Adrenergic Agonists, Procaterole and Terbutaline, on Protein Secretion by Rat Submandibular Glands
Authors: Abe K. , Inoue H. , Yokota Y. 
Published: November 2010

We examined the secretory effects of two β2-adrenergic agonists, procaterole and terbutaline, on the submandibular glands of anesthetized rats. After stimulation with these agents with and without a range of antagonists (non-specific α- and β-adrenergic blockers), submandibular saliva was collected. The flow rate, protein concentration, the electrophoretic patterns, and amino acid composition of saliva were examined. These parameters were compared with their counterparts in saliva stimulated with isoproterenol (IPR), with and without antagonists. Assessed by these criteria, secreted proteins were classified as the α- or β-type. In addition, IPR-stimulated proteins were compared in submandibular saliva of rats chronically treated with IPR or procaterole.Both β2-agonists were potent secretagogues for the submandibular glands of rats. All β-antagonists completely abolished the secretory effects elicited by both β2-agonists, with the exceptions of carteolol and propranolol. However, no blocking agent abolished the secretory effects of IPR (60 mg/kg). The types of proteins in all submandibular saliva samples elicited by both β2-agonists with and without antagonists were the β-type. Enlargement of the submandibular glands was not observed in rats subjected to chronic administration of procaterole, nor were abnormal and additional proteins observed, as confirmed by electrophoresis and by the amino acid analyses.
Compressive Creep of Dental Composites
Authors: Bapna M.S. , Mueller H.J. , Knoeppel R. 
Published: November 2010

The creep compliance curves for P-10, Adaptic, and Silar composite materials were obtained at 23°C, 37°C, and 50°C and at a number of initial stress levels ranging from 5 to 75% of their compressive strengths. The creep compliance curves were characterized by large instantaneous compliances, followed by retarded strain compliances with very minimal viscous flow. Rupturing occurred only at the higher stresses and temperatures, and was characterized by a sharp upsurge in the compliance just before failure. Empirical curve-fitting of the data indicated that the creep compliances exhibited a very good representation when plotted against log t. Both isochronous stress-strain and isochronous compliance-stress diagrams indicated that linear visco-elasticity was followed below the stress of about 70-100, 50-70, and 120-<240 MPa for Silar, Adaptic, and P-10, respectively. The combined Voight-Maxwell linear viscoelastic model was used to describe the compliance curves. At higher stresses, where compliance was dependent upon stress, a nonlinear visco-elastic model based upon Eyring's thermally activated process was considered.
The Surface Free Energy of Oral Streptococci after being Coated with Saliva and its Relation to Adhesion in the Mouth
Authors: Weerkamp A.H. , Van der Mei H.C. , Busscher H.J. 
Published: November 2010

Contact angle measurements on layers of bacteria were used to determine the bacterial surface free energy (γb) of a variety of oral streptococcal strains, both without and after being coated with human whole saliva. At least four isolates of each species, either freshly isolated or laboratory strains, were used. The species Streptococcus mutans, S. sanguis, and S. salivarius were homogeneous, having high surface free energies, and were not affected by saliva treatment (γb = 106 ± 12 and 107 ± 10 erg·cm-2 in the absence and presence of saliva coating, respectively; n = 20). S. mitis had a very low surface free energy (46 ± 15; n = 5), which was significantly increased after salivary adsorption (71 ± 14 erg·cm-2; p<0.002). The species S. milleri contained strains with both high and low γ b. Calculation of the interfacial free energy of adhesion (ΔF adh) for bacteria from a saliva suspension to solid surfaces with various arbitrary surface free energies (γs) showed that, theoretically, most strains will encounter thermodynamically favorable conditions for adhesion to surfaces with a γs above 62 erg·cm-2. However, S. mitis strains not coated with saliva would only be able to adhere to surfaces with γs lower than this value. Saliva-coating reverses the calculated relationship with γs for these strains. The results indicate that an enamel surface with a low γs value would be thermodynamically unfavorable for adhesion of most oral streptococci.
The Effect of Alternatives to Formocresol on Antigenicity of Proteins
Authors: Ranly D.M. , Horn D. , Zislis T. 
Published: November 2010

As part of an overall evaluation of possible substitutes for the pulpotomy agent formocresol, this study was initiated to compare the antigenicity of the reaction products of protein with formaldehyde, glutaraldehyde, or dimethylsuberimidate (DMS).Rabbits were injected with rabbit serum albumin (RSA) which had been treated with one of the following solutions: phosphate-buffered saline, 2% glutaraldehyde, 4% formaldehyde, or 2% DMS. The antisera from the rabbits were analyzed for elicited antibodies by the enzyme-linked immunosorbent assay (ELISA) and in a horseradish peroxidase (HRP) assay using a spot technique on nitrocellulose paper.These assays demonstrated that DMS-treated RSA was the most antigenic of the reaction products tested. The least provocative was the glutaraldehyde-treated RSA; the reaction product of formaldehyde was intermediate.Our findings suggest that if non-immunogenicity of a pulpotomy agent is a desirable property, then DMS does not meet the criteria of an alternative pulp fixative. In contrast, the relatively low antigenicity of glutaraldehyde reinforces other favorable findings which support its use clinically.
Sulfur Uptake by Type I Collagen from Methyl Mercaptan/Dimethyl Disulfide Air Mixtures
Authors: Johnson P.W. , Tonzetich J. 
Published: November 2010

Type I acid-soluble collagen, suspended in 0.02 M Tris/0.13 M NaCl buffer (pH 7.4), was exposed to air atmosphere admixed with 10.7 × 10-9 moles of [35 S]-labeled dimethyl disulphidelmethyl mercaptan mixture in the ratio of 99.82% (CH 3 S)2 /0.18% CH3SH. Gas chromatographic analyses of head-space following one and four days of incubation indicated that all of the CH3 SH was absorbed from the head-space by the collagen-containing liquid phase, while the (CH3 S)2 concentration of the head-space remained essentially unchanged. Of the total [ 35 S]-activity initially present in the head-space, only 1.0 and 1.86% was absorbed by the collagen-containing liquid phase within one and four days, respectively. Paper chromatographic separation of the reaction mixture showed that only 0.42 and 0.60% of the radioactivity in the head-space was associated with collagen after one and four days of reaction. In comparable [ 35 SJ-H2 S systems devoid of (CH3 S)2 , all of the H2 S was absorbed within 48 hours of incubation with 18.04% (1 day) and 18.28% (4 days) of the available [35 S]-H2 S complexed with collagen. The results provide evidence that the reaction of collagen with H2 S and CH3 SH/(CH3 S)2 mixture proceeded via the H2 S and CH3SH thiol groups.
Adsorption of Zirconyl Salts and Their Acids on Hydroxyapatite: Use of the Salts as Coupling Agents to Dental Polymer Composites
Authors: Misra D.N. 
Published: November 2010

Zirconyl methacrylate (I) and zirconyl-2-ethylhexanoate (II) were synthesized, and their adsorption isotherms from solutions onto synthetic hydroxyapatite were studied. The isotherms of methacrylic and 2-ethylhexanoic acids were also determined from the same solvents. The adsorption of I was irreversible from methylene chloride, and that of II was irreversible from cyclohexane. The adsorption in both cases was constant from solutions above a certain concentration, and exhaustive below this threshold concentration. Both compounds rendered the dried apatite powder extremely hydrophobic; however, the adsorbate was slowly washed off by excess water. The configuration of the adsorbate molecules, deduced from the maximum adsorption and other adsorption characteristics of the two compounds, indicated that: (i) in both cases the adsorbate may be held to the surface by concerted hydrogen bonding of the carboxylate and zirconyl oxygen atoms; and (ii) the hydrocarbon moieties in both adsorbates expose themselves toward the solution, thereby making the dried surface hydrophobic. The adsorptive behavior of the respective acids was similar to that of the salts. Polymer, filled with synthetic hydroxyapatite covered with irreversibly adsorbed I, had a diametral tensile strength about 50% greater than that of the polymer filled with untreated apatite. The strength of the composite was not affected by treatment of the apatite with II or with the acids.
Dentin-Polymer Bond Promoted by Gluma and Various Resins
Authors: Munksgaard E.C. , Irie M. , Asmussen E. 
Published: November 2010

Gluma-treated dentin was covered with various resins before a microfilled composite was applied. The strength of the bond between dentin and composite established by this procedure was measured in shear and tensile tests. The effectiveness of the bonding was further tested by the width of the marginal contraction gap around fillings made in dentin by the above procedure. Resins containing propanal promoted shear bond strength of about 15 MPa. The tensile bond strength exceeded 22 MPa by one of the resins, but could not be measured because of frequent rupture in the composite. Between 30 and 70% of the fillings were without contraction gaps when propanal or p- toluenesulfinate-containing resins were used. It is proposed that oxygen inhibition of the polymerization on the dentin surface suppresses the bonding. Resins containing reducing agents may reduce oxygen inhibition and increase bonding by the adhesive.
Response of Lingual Ascorbic Acid Test and Salivary Ascorbate Levels to Changes in Ascorbic Acid Intake
Authors: Leggott P.J. , Robertson P.B. , Rothman D.L. , Murray P.A. , Jacob R.A. 
Published: November 2010

This study sought to determine whether the lingual ascorbic acid test (LAAT) and measurement of salivary ascorbate refXect plasma and leukocyte ascorbate levels during controlled periods of ascorbic acid depletion and supplementation. Eleven healthy non-smoking men, aged 19-28 years, ate a diet that was repeated every seven days and was adequate in all nutrients except ascorbic acid (AA). This basal diet, which provided less than 5 mg of AA per day, was supplemented with 60 mg of AA per day for two weeks, 0 mg (placebo) per day for four weeks, 600 mg per day for three weeks, and 0 mg per day for four weeks. Oral examinations, the lingual ascorbic acid test, and measurement of salivary, plasma, and leukocyte ascorbate concentrations were conducted throughout the study. Ascorbic acid concentrations in plasma and leukocytes responded rapidly to changes in vitamin C intake. LAAT-derived ascorbate values were unrelated to ascorbic acid intake and plasma and leukocyte ascorbate concentrations. Salivary ascorbate levels approached the lower limits of detection of the assay and remained constant throughout the investigation. Oral hygiene was consistently excellent, and no severe mucosal or periodontal changes were observed. It was concluded that lingual ascorbic acid test values and salivary ascorbate levels are not related to changes in ascorbic acid intake and are not consistent with plasma or leukocyte ascorbate concentrations.
Growth of Micro-organisms from Supragingival Dental Plaque on Saliva Agar
Authors: De Jong M.H. , Van Der Hoeven J.S. , Van Os J.H. 
Published: November 2010

The role of saliva in supporting the growth of dental plaque has scarcely been investigated. We have studied the growth and recovery of micro-organisms from dental plaque samples on saliva-agar plates, prepared from filter-sterilized wax-stimulated whole saliva. Under optimal conditions, the mean recovery of plaque samples on saliva agar was about 50% (range, 22-77) of the recovery on blood agar. Addition of 2.5 mmol/L dithiothreitol (DTT) strongly facilitated filter-sterilization of saliva, but DTT concentrations higher than 1 mmol/L reduced the recovery of plaque micro-organisms on saliva agar. Catalase (100 U/ml) offered protection against the inhibitory effect of DTT. Addition of glucose (1-5 mmol/L) increased only slightly the recovery of plaque micro-organisms on saliva agar. When supragingival plaque was plated on saliva- and blood-agar plates, the composition of the microflora isolated from saliva agar strongly resembled that isolated from blood agar. The predominant species — i.e., Streptococcus and Actinomyces — all grew on saliva agar though usually in numbers somewhat lower than those on blood agar. In addition, most species normally found only in low proportions in supragingival dental plaque were also found to grow on saliva agar. Collectively, the results lead to the conclusion that the supragingival microflora can utilize saliva as a complete source of nutrients.
The Impact of Composite Structure on Its Elastic Response
Authors: Braem M. , Lambrechts P. , Van Doren V. , Vanherle G. 
Published: November 2010

The non-destructive determination of Young's modulus of dental composites by means of the fundamental period was found to be reliable and accurate. Post-polymerization effects could clearly be detected. Exponential regression analysis showed a correlation coefficient of 0.92, after logarithmic transformation, with volumetric filler content. The high accuracy and reliability of the measurements themselves are reflected in low standard deviations. The results are in excellent agreement with those of other investigations. Furthermore, the ease and speed of operation make this new procedure a powerful laboratory tool for material-testing and practical large-scale investigations.
The Effects of Sorbate on Oral Streptococci Grown in Continuous Culture
Authors: Rogers A.H. 
Published: November 2010

The antimicrobial effect of potassium sorbate on Streptococcus mutans and S. milleri grown in continuous culture was determined at pH values of 7.0, 5.5, and 5.0. Organisms were grown glucose-limited at a dilution rate of D = 0.1 h-1, corresponding to a doubling time of ca. seven hours, in a chemically defined medium under an atmosphere of 5% CO2 in N2. After equilibration at the appropriate pH level, the culture vessel was pulsed with potassium sorbate to a final concentration of 20 mmol L-1 or with sorbate followed almost immediately by a pulse of glucose (to 40 mmol L-1); that is, the cultures were exposed to transient excesses of sorbate with and without glucose - such as might occur during meals. At pH 7.0, sorbate had virtually no effect on glucose uptake and on the, albeit transient, increase in growth rate and acid production by both organisms. At pH 5.5 and 5.0, both cell viability and acid production in S. milleri were depressed following a pulse of sorbate, the effect being even more marked after a sorbate/glucose pulse. At low pH, the uptake of glucose in the presence of sorbate was drastically reduced. The effect on S. mutans was less marked, but growth and acid production were greatly depressed at pH 5.0 following consecutive pulses of sorbate. The antimicrobial effect of the widely used preservative potassium sorbate, at low pH, is confirmed for oral streptococci, and it is suggested that continuous culture offers a relevant system for testing potential antimicrobial agents.
In vivo Measurements of Sulcal Plaque pH After Topical Applications of Sorbitol and Sucrose in Rats Fed Sorbitol or Sucrose
Authors: Firestone A.R. , Navia J.M. 
Published: November 2010

To test whether adaptation to sorbitol could be observed in rat plaque, we made pH measurements of rat sulcal plaque in vivo, following topical application of 10% sorbitol solution. Rat pups were inoculated orally with S. mutans 6715 and fed diet MIT 305 (5% sucrose) for 16 days. Baseline sulcal plaque pH response of these rats to topical application of 10% sorbitol solution was measured. One group of 16 rats was then fed 20% sucrose in the diet, and a second group 20% sorbitol. After 13 days' feeding of the experimental diets (four days were used for accommodation to dose, and nine days at the 20% level for sorbitol), there was a significantly greater (p<0.01) drop in pH following topical application of 10% sorbitol in this group than in the sucrose-fed group. There was no difference in the pH response of the two groups to topical application of a 10% sucrose solution when tested six days later. The sulcal enamel caries score was significantly higher (p<0.001) in the sucrose group, but buccal enamel scores were similar in both groups. Adaptation in rat plaque took place, and could be measured in vivo as an increased drop in sulcal plaque pH following topical application of sorbitol. It is not clear whether this adaptation was primarily due to selection of sorbitol-fermenting micro-organisms, or, more likely, by induction of sorbitol-specific enzymes. Relative to the sucrose-containing diet, the sorbitol diet was hypocariogenic, even under experimental conditions.
Prenatal Fluoride Exposure: Measurement of Plasma Levels and Enamel Uptake in the Guinea Pig
Authors: Parker P.R. , Bawden J.W. 
Published: November 2010

This study measured the effects of variations in the maternal fluoride intake on changes in maternal plasma, fetal plasma, and fetal enamel fluoride levels of near-term guinea pig pups. Pregnant sows were divided randomly into one of three groups whose drinking water was either de-ionized or contained 5 ppm or 20 ppm fluoride supplied ad libitum. At approximately 55 days' gestation, maternal and fetal plasma and fetal enamel samples were collected and assayed for fluoride. Results showed an increase in mean fluoride concentration for maternal plasma from the de-ionized to the 20-ppm group. Mean fetal plasma fluoride concentrations were lower at baseline and increased much less than did maternal plasma levels. Mean fetal enamel concentrations increased in a fashion similar to that of the maternal plasma levels and exhibited significant differences among all groups.
In vivo Bovine Enamel Remineralization and Fluoride Uptake from two Dentifrices Containing Different Fluoride Concentrations
Authors: De Kloet H.J. , Exterkate R.A.M. , Rempt H.E. , Ten Cate J.M. 
Published: November 2010

In this study, the differences in lesion remineralization and fluoride uptake after brushing with a 300 ppm F or a 1000 ppm F dentifrice (as NaF) were investigated. Twenty volunteers with partial dentures in their lower jaws were divided into two groups. Bovine enamel slabs with artificial lesions were mounted in the dentures. After a test period of six weeks, the slabs were taken out and analyzed. There was no statistically significant difference between the two groups, in F-uptake and susceptibility of the enamel to demineralization, although the findings favored the 1000 ppm F toothpaste. The microradiograms in the 300 ppm F group showed lesions more pronounced than those in the 1000 ppm group. The present study cannot support the presumption that the fluoride content of regular NaF dentifrices can be lowered to 300 ppm F without undesirable effects on lesion arrest and remineralization.
A Measurement of Galvanic Current and Electrical Potential in Extracted Human Teeth
Authors: Momoi Y. , Asanuma A. , Kohno A. , Yanagisawa K. 
Published: November 2010

When opposing teeth with amalgam and gold restoration are in contact, current flows in the mouth at the instant the dissimilar metals touch. In this study, this condition was simulated by use of resistors and extracted human teeth with amalgam and MOD gold inlay restorations. When both teeth were in contact in a physiological saline solution, we measured current and electrical potential generated in each pulp chamber. Galvanic current generated in the tooth with amalgam was always larger (as much as 18.2 times at the instant of contact) than that in the tooth with gold. Electrical potential generated in the tooth with amalgam was always larger (as much as 9.7 times at the instant of contact) than that in the tooth with gold. It should be emphasized that the larger current generated in the tooth with amalgam was caused mainly by its larger electrical potential. These results correspond well with the clinical phenomenon of galvanic pain, which occurs in the tooth with amalgam rather than in the tooth with gold.
A Simplified Diagnostic System for Cultural Detection and Enumeration of Streptococcus mutans
Authors: Jordan H.V. , Laraway R. , Snirch R. , Marmel M. 
Published: November 2010

A simple dip-slide test (Cariescreen SM®) based on MSB selective agar was devised for detection and quantitation of Streptococcus mutans in oral samples. For this test, a bacitracin tablet is dissolved in a vial containing buffered saline diluent. Paraffin-stimulated saliva is collected in this diluent vial. A dip slide which incorporates a modified MSB agar (minus bacitracin) is immersed briefly in the diluted saliva. After addition of a CO2-generating tablet, the screw-cap dip slide is closed tightly in the vial and incubated for two days at 37°C and one day at room temperature. S. mutans populations in saliva are estimated by comparison with a colony density chart. Growth of reference strains of S. mutans was equivalent on Cariescreen SM dip slides and on MSB agar plates. Reference strains of Streptococcus sanguis, Streptococcus salivarius, Streptococcus mitis, and Streptococcus milleri did not grow on Cariescreen SM dip slides. Aliquots of saliva from 50 schoolchildren and 51 adults were tested by the dip-slide method and by conventional plating methods in MSB agar. Very good correlation (0.93) between the two methods was obtained. This simplified S. mutans detection system is suitable for use by clinical personnel in dental clinics or other non-laboratory settings for identification of subjects potentially at risk for caries.
Structural and Genetic Aspects of Proline-rich Proteins
Authors: Bennick A. 
Published: November 2010

Considerable advances have been made in the genetics of salivary proline-rich proteins (PRP). The genes for acidic, basic, and glycosylated PRP have been cloned. They code for precursor proteins that all have an acidic N-terminal followed by proline-rich repeat sequences. Structural studies on secreted proteins have demonstrated that not only acidic but also some basic PRPs have this general structure. It is possible that mRNA for different PRP may have originated from a single gene by differential mRNA splicing, but post-translational cleavages of the primary translation product apparently also occur. In vitro translation of salivary gland mRNA results in a single precursor protein for acidic PRP. Such in vitro translated protein can be cleaved by salivary kallikrein, giving rise to two commonly secreted acidic PRPs, and kallikrein or kallikrein-like enzymes may be responsible for other post-translational cleavages of PRPs. Acidic as well as some basic PRPs are phosphorylated. A protein kinase has been demonstrated in salivary glands which phosphorylates the PRPs and other secreted salivary proteins in a cAMP and Ca2+-calmodulinindependent manner. Knowledge of the conformation of PRPs is limited. There is no conclusive evidence of polyproline-like structure in the proline-rich part of PRPs. Ca2+ binding studies on acidic PRPs indicate that there is interaction between the Ca2+ binding N-terminal end and the proline-rich C-terminal part. This interaction is relieved by modification of arginine side-chains. 1H, 32P, and 43Ca NMR studies have further elucidated the conformation of acidic PRPs in solution. Present evidence shows that salivary PRPs constitute a unique superfamily of proteins which pose a number of interesting questions concerning gene structure, pre- and post-translational modifications, and protein conformation.