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Biomedical subjects

W F Liljemark

Publications and source records attributed to W F Liljemark.

At least 19 recordsLinked to original sources
PubMed2001

Retrieval of biofilms from the oral cavity.

With the use of the removable stents or bonded enamel piece models with or without a continuous bacterial layer, many in vitro or in vivo studies can be initiated. For example, studies on salivary pellicle formation, surface characteristics of biomaterials as they affect plaque development, antiplaque agents, the dynamics of adhesion of bacteria, interspecies adhesion of bacteria, the colonization of bacteria, the dynamics of bacterial growth in vivo, and the succession of growth in older supragingival plaques can be carried out.

Adult↗
PubMed1997

Growth dynamics in a natural biofilm and its impact on oral disease management.

Measurements of the microbial growth dynamics in natural biofilm communities are almost non-existent. In a recent study, the biofilm formation on teeth was examined. A previously unknown active period of bacterial division occurred at a certain density of plaque bacteria on tooth enamel. The density-dependent cell-division phase of plaque formation contributed 90% of the biomass in the first 24 hrs of plaque formation. This suggested that growth was induced by the bacteria. In vitro assays were developed for rapid evaluation of the growth of surface-linked bacteria by the measurement of cellular components associated with growth on a per cell per time basis. Cell-free supernatants (termed START) of media in contact with bacteria were assayed for their effects on DNA synthesis and other cellular components associated with growth. START was found to increase the incorporation of [3H-methyl]-thymidine on a per cell per time basis, when compared with media not in contact with bacteria. Additional in vivo studies and in situ-based models of complex biofilms are needed if all of the mechanisms involved in the rapid accumulation of biofilm bacteria on teeth and other surfaces are to be understood.

Amino Acids↗
PubMed1996

Adherence, accumulation, and cell division of a natural adherent bacterial population.

Developing dental bacterial plaques formed in vivo on enamel surfaces were examined in specimens from 18 adult volunteers during the first day of plaque formation. An intraoral model placing enamel pieces onto teeth was used to study bacterial plaque populations developing naturally to various cell densities per square millimeter of surface area of the enamel (W. F. Liljemark, C. G. Bloomquist, C. L. Bandt, B. L. Philstrom, J. E. Hinrichs, and L. F. Wolff, Oral Microbiol. Immunol. 8:5-15, 1993). Radiolabeled nucleoside incorporation was used to measure DNA synthesis concurrent with the taking of standard viable cell counts of the plaque samples. Results showed that in vivo plaque formation began with the rapid adherence of bacteria until ca. 12 to 32% of the enamel's salivary pellicle was saturated (ca. 2.5 x 10(5) to 6.3 x 10(5) cells per mm2). The pioneer adherent species were predominantly those of the "sanguis streptococci." At the above-noted density, the bacteria present on the salivary pellicle incorporated low levels of radiolabeled nucleoside per viable cell. As bacterial numbers reached densities between 8.0 x 10(5) and 2.0 x 10(6) cells per mm2, there was a small increase in the incorporation of radiolabeled nucleosides per cell. At 2.5 x 10(6) to 4.0 x 10(6) cells per mm2 of enamel surface, there was a marked increase in the incorporation of radiolabeled nucleosides per cell which appeared to be cell-density dependent. The predominant species group in developing dental plaque films during density-dependent growth was the sanguis streptococci; however, most other species present showed similar patterns of increased DNA synthesis as the density noted above approached 2.5 x 10(6) to 4.0 x 10(6) cells per mm2.

Actinomyces↗
PubMed1996

Human oral microbial ecology and dental caries and periodontal diseases.

In the human oral cavity, which is an open growth system, bacteria must first adhere to a surface in order to be able to colonize. Ability to colonize a non-shedding tooth surface is necessary prior to any odontopathic or periodontopathic process. Complex microbe-host relationships occur and must be studied before the commensal-to-pathogenic nature of the human indigenous oral flora can be understood. Medical pathogens, if present in the appropriate host, always produce specific disease. Caries and periodontal diseases are conditional diseases, requiring numbers of certain indigenous species at various sites, particularly the tooth surface. In the case of caries, the condition is related to sugar consumption. Periodontal disease/s may require certain host and environmental conditions, such as local environment or nutritional factors in gingival crevicular fluids. Nonetheless, critical numbers of certain indigenous species must be present in order for these diseases to occur. The aim of this review is to understand the acquisition of the indigenous oral flora and the development of human dental plaque. The role of the salivary pellicle and adherence of indigenous bacteria to it are critical first steps in plaque development. Bacterial interactions with saliva, nutritional factors, growth factors, and microbial physiologic processes are all involved in the overall process of microbial colonization.

Bacteria↗
PubMed1995

Saliva protein binding to layers of oral streptococci in vitro and in vivo.

This paper reports a system for measuring saliva protein binding to oral streptococci. Enamel chips with layers of Streptococcus gordonii Blackburn or Streptococcus oralis 10557 were incubated in vitro with whole saliva from eight persons. Blackburn bound significantly more amylase than 10557; no strain differences were seen for lysozyme or lactoferrin. There were significant correlations between saliva and bound amylase and lactoferrin. Blackburn and 10557 chips were then placed in ten subjects. Sites included the buccal left and right upper premolars and molars (UL, UR), labial upper central incisors (UC), and lingual lower central incisors (LL). That study was repeated three months later; chips with Streptococcus sanguis 13379 were also placed then. Blackburn bound significantly more amylase than the other strains. Blackburn and 10557 both bound the most amylase at UL and UR, and the least amylase at UC. However, strain 13379 bound less amylase at UL. That strain also bound significantly less sIgA at UL. All three strains bound the least sIgA at UC. Lysozyme and lactoferrin binding showed few differences among sites or strains. Bound protein concentrations were significantly correlated across sites and strains within subjects, but not correlated with whole saliva. Strain differences may reflect species differences in amylase binding, or differences in species-specific sIgA titers. Site differences may indicate local variation in protein availability. Differences between chip correlations with whole saliva in vitro and in vivo suggest that the salivary film may be modified as it flows over tooth surfaces.

Amylases↗
PubMed1994

Cephalometric norms for craniofacial asymmetry using submental-vertical radiographs.

The submental-vertical (S-V) radiograph has become popular in the assessment of craniofacial asymmetry because of ease in identifying reliable midline reference structures. To date, no standards of asymmetry that use the S-V projection have been reported. Submental-vertical radiographs were obtained on 44 adults. Subjects were excluded if previous orthodontic treatment or temporomandibular joint symptoms were reported. With the use of a system of asymmetry analysis developed by Ritucci and Burstone, asymmetry was reported for cranial base, zygomaxillary complex, and mandibular structures. Mean and standard deviations were used to report the asymmetry values across 23 pairs of anatomic landmarks. The data showed that asymmetry is present to some degree in all landmarks and patients. Further, strong asymmetry associations existed between landmarks within patients, with most high positive correlation coefficient values found between regionally or geometrically related points. A refined version of the asymmetric analysis was presented that included easily identified and clinically relevant points. This system is more feasible for the orthodontic clinician.

Adolescent↗
PubMed1994

The influence of saliva on interbacterial adherence.

The mechanism of bacterial adherence to the mat of bacteria in preformed dental plaque is not well defined. This study measured the influence of saliva on the adherence of bacteria in suspension to a continuous bacterial surface in vitro. Twenty different pairs of bacteria were tested, consisting of Streptococcus spp., Haemophilus spp. and Actinomyces spp. The species were chosen based on the parameters of coaggregation, and salivary agglutination. The results were expressed as bacteria that adhered per mm2 of bacterial surface. When both the surface bacteria and the bacteria in suspension agglutinated in saliva, interbacterial adherence was increased 2.5-fold when a salivary coating was placed on the surface. When one or both of the bacteria did not agglutinate in saliva, interbacterial adherence was increased only slightly when the surface was saliva-coated. The results suggested that salivary-mediated adherence is significant to plaque formation once the tooth surface becomes covered with bacteria. Thus bacteria that are capable of agglutinating in saliva may have a distinct advantage in colonization of the plaque surface.

Actinomyces viscosus↗
PubMed1993

Comparison of the distribution of Actinomyces in dental plaque on inserted enamel and natural tooth surfaces in periodontal health and disease.

The distribution of Actinomyces naeslundii, Actinomyces viscosus and Actinomyces odontolyticus in healthy and diseased adult populations was studied in 3 different ways. First, supragingival plaque formation at 2 through 72 h was examined in 12 periodontally healthy adults using a removable pre-measured surface of enamel bonded to molars and premolars. Second, a cross-sectional examination of the composition of both supragingival and subgingival plaque of unknown age was conducted in 205 adults exhibiting periodontal health to moderate disease. Third, the effects of oral hygiene instruction and root planing on the subgingival microflora of a subset of 19 subjects with moderate periodontitis were examined. The evaluation of 12 adults revealed that the predominant species in early plaque formation (2, 4 and 8 h) was A. odontolyticus. A. viscosus and A. naeslundii were present in developing plaques in almost all subjects in 2-h plaque, but absent in half the subjects when 4-, 8- or 24-h plaque was examined. These two species significantly increased in numbers per mm2 enamel surface area in 48- and 72-h plaques. A. odontolyticus was not related to clinical signs of periodontal disease in 205 adults, and its subgingival proportions in plaque did not change following periodontal treatment of 19 individuals. A. naeslundii was found in significantly higher numbers in supragingival than subgingival plaques in the 205 adults examined. The mean proportion of A. naeslundii significantly decreased as the magnitude of probing depth and attachment loss increased. The proportions of A. naeslundii and A. viscosus were found to be significantly increased in subgingival plaques following periodontal treatment.

Actinomyces↗
PubMed1993

Dental plaque development on defined streptococcal surfaces.

Coaggregations between bacterial species have been widely studied in vitro but not in the mouth. A new in vivo assay was used to measure the rate and composition of indigenous plaque formation onto bovine enamel chips covered with a continuous layer of bacteria. Chips were covered with Streptococcus oralis ATCC 10557, which coaggregated with many oral species, or Streptococcus gordonii S7, which did not coaggregate with these oral species, and placed in the mouth for 4 and 24 h. There were no differences in the number of most indigenous bacterial species isolated from the two streptococcal surfaces. However, the number of Actinomyces viscosus as a proportion of total Actinomyces spp. was significantly different on the two surfaces at 24 h. With the exception of Actinomyces naeslundii and A. viscosus removed from the S7 surface, all indigenous species increased significantly in number from 4 to 24 h, irrespective of the streptococcal surface. This study demonstrated that interbacterial coaggregation had only a limited effect on in vivo plaque development. Thus suggesting that environmental factors, growth or other adherence phenomena are dominant in in vivo plaque formation.

Actinomyces↗
PubMed1992

A follow-up case report of Actinobacillus actinomycetemcomitans in human periodontal disease.

The purpose of this investigation was to compare clinical and microbial parameters in a follow-up case report of adult subjects harboring Actinobacillus actinomycetemcomitans (Aa) with clinically matched subjects who did not have detectable Aa. 16 subjects with Aa and 16 subjects without Aa at the baseline examination were re-examined at an average of 46 months following collection of baseline data. Clinical measurements were recorded and subgingival plaque sampled and evaluated for microbial flora from each maxillary first molar. In 16 subjects with Aa at baseline, 4 sites in 3 subjects had detectable actinobacilli at the follow-up appointment. 26 sites in 13 individuals with Aa at baseline had a significantly increased gingival index at the follow-up visit (p less than or equal to 0.05), but there was no significant increase in probing depth or attachment loss. 32 sites in the 16 subjects without Aa at baseline still did not have detectable levels of this microorganism at the follow-up examination nor was there any significant difference between baseline and the follow-up appointment for the gingival index, probing depth and attachment level measurements. In subjects with Aa at baseline, 1 of 12 teeth without Aa and 5 of 20 teeth with Aa had been extracted prior to the follow-up visit. In this population group, having sites where Aa was detected, 6 of 9 teeth which had a probing depth greater than or equal to 5 mm were lost before the follow-up data collection appointment. In the control group, which did not have detectable Aa at baseline, 9 teeth with probing depths greater than or equal to 5 mm were not lost. These observations, although not proving, suggest in this population group, that deeper probing depths taken together with the presence of Aa may have placed an individual at greater risk of tooth loss.

Adult↗
PubMed1992

Clustering of an outer membrane adhesin of Haemophilus parainfluenzae.

Haemophilus parainfluenzae synthesizes an outer membrane protein adhesin which mediates binding to oral streptococci, salivary pellicle, and neuraminidase-treated erythrocytes. An indirect gold labeling technique and immunoelectron microscopy verified the location of this outer membrane protein. Further, a clustering of gold particles was observed in irregular patches at the cell surface.

Bacterial Adhesion↗
PubMed1990

The development of penicillin-resistant oral streptococci after repeated penicillin prophylaxis.

Oral streptococci may cause infective endocarditis in patients with susceptible cardiac disease after dental treatment. Multiple dental visits, each preceded by penicillin prophylaxis, may result in the unwanted development of resistant oral streptococci. This study was undertaken to determine whether resistant oral streptococci would develop after the repeated use of penicillin prophylaxis in healthy adults. Plaque samples were collected from 20 subjects on each Monday for 5 successive weeks. Each subject was administered 2 gm penicillin V followed by 1 gm 6 hours later (standard prophylaxis regimen of the American Heart Association), on three successive Mondays (weeks 2, 3, and 4). The total cultivable oral streptococci and penicillin-resistant oral streptococci were determined for each plaque sample, and representative colonies of resistant streptococci were speciated. During the study, there was a significant increase in the number of subjects who harbored penicillin-resistant oral streptococci. However, with the exception of one subject who had resistant streptococci throughout the study, the number of resistant strains represented only 0.0003% to 0.41% of the total cultivable oral streptococci.

Adult↗
PubMed1990

Comparison of plaque microflora between Chinese and Caucasian population groups.

This investigation was designed to compare the predominant plaque micro-organisms from a Chinese group of patients exhibiting periodontitis with an age-, sex- and periodontal disease-matched Caucasian group of patients. In addition to race, the 2 population groups differed with respect to diet and oral hygiene habits, or effectiveness at removing plaque. Clinical measurements were determined along with an evaluation for micro-organisms in supragingival and subgingival plaque. Although the Chinese and Caucasian population groups were similar with respect to composition of micro-organisms in subgingival plaque, notable differences were observed in supragingival plaque. The Chinese group had higher mean proportions of spirochetes, motile rods. Fusobacterium spp. and dark-pigmented Bacteroides species, while the Caucasian group had higher mean proportions of cocci, total Actinomyces spp., A. viscosus and total Streptococcus spp. in supragingival plaque. The microbial differences observed in supragingival plaque may be explained at least in part, if not totally, by the higher plaque index scores of the Chinese versus Caucasian population groups.

Actinobacillus↗
PubMed1990

Purification and characterization of an outer membrane protein adhesin from Haemophilus parainfluenzae HP-28.

Outer membranes were isolated from Haemophilus parainfluenzae HP-28 by a mild extraction method followed by Sephadex G-150 gel filtration chromatography. The first peak (pool 1) recovered contained an activity which inhibited adherence of HP-28 cells to saliva-coated spheroidal hydroxyapatite. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of pool 1 revealed a dominant protein band of 34 kDa. The SDS-PAGE-purified 34-kDa protein was excised from the gel and used for antibody preparation in rabbits. The antiserum produced was analyzed by immunoblot and was shown to be monospecific for the 34-kDa protein. Anti-34-kDa protein antibody was purified from the rabbit antiserum by protein A-Sepharose 6MB affinity chromatography. This antibody was then cross-linked to protein A-Sepharose 6MB to construct a second affinity column. The 34-kDa proteins were purified from outer membranes by this affinity chromatography. The 34-kDa protein was homogeneous, as confirmed by SDS-PAGE, isoelectric focusing, and reverse-phase chromatography analyses. Fab and Fc fragments of the purified anti-34-kDa protein antibodies were prepared by papain digestion, followed by carboxymethyl cellulose chromatography. Fab fragments from the anti-34-kDa protein antibody and the affinity-purified 34-kDa protein both showed significant inhibition of parent H. parainfluenzae HP-28 cell adherence to experimental salivary pellicle and to Streptococcus sanguis SA-1.

Animals↗
PubMed1989

Effect of neuraminidase on the adherence to salivary pellicle of Streptococcus sanguis and Streptococcus mitis.

Neuraminidase-sensitive adherence to experimental salivary pellicles was studied using eight strains of Streptococcus sanguis and five strains of Streptococcus mitis. Approximately 60% of the strains of each species showed significantly lower adherence to neuraminidase-treated versus untreated saliva-coated hydroxyapatite. In addition, the adherence of several of these streptococcal strains to saliva-coated hydroxyapatite and neuraminidase-treated saliva-coated hydroxyapatite was inhibited using galactose and N-acetyl-D-galactosamine. Results from these studies suggested that several salivary receptors mediate adherence of these species.

Acetylgalactosamine↗
PubMed1988

Relationship between lactate dehydrogenase and myeloperoxidase levels in human gingival crevicular fluid and clinical and microbial measurements.

The present study was designed to determine, in a cross-sectional study, whether there was any relationship between levels of lactate dehydrogenase (LDH) and myeloperoxidase (MPO) in gingival crevicular fluid (GCF) and clinical periodontal status or microbial parameters. Another objective was to determine, in a longitudinal study, the effect of a single session of root planning on GCF levels of LDH and MPO and the relation to changes in clinical and microbial measurements. 15 and 12 test subjects with moderate to severe periodontal disease were seen in the cross-sectional and longitudinal study, respectively. 1 healthy and 2 diseased sites were evaluated in each subject. Higher LDH and MPO levels in GCF were closely associated with higher clinical and microbial signs of periodontal disease. Root planing was effective in reducing these enzymes in GCF, with an accompanying decrease in clinical and microbial signs associated with disease. The return of LDH to baseline levels at 3 months after instrumentation, without a corresponding return of clinical signs of disease, may serve as a marker for subclinical periodontal pathology.

Adult↗
PubMed1988

Utilization of a continuous streptococcal surface to measure interbacterial adherence in vitro and in vivo.

Cell-to-cell interactions are essential for the formation of dental plaque. A continuous layer of Streptococcus sanguis SA-1 cells fixed to a solid surface has been used to evaluate interactions among this bacterium, Haemophilus parainfluenzae, and Streptococcus sobrinus. S. sanguis cells were attached to a Falcon 3001 tissue culture plates or bovine enamel chips, coated with a biological adhesive. Scanning electron microscopy of the chips showed the streptococci as a contiguous surface. Radiolabeled bacteria were used to measure a second-species interbacterial adherence to the streptococcal-coated culture plates. Strains of H. parainfluenzae known to coaggregate (strain HP-28) and not to coaggregate (strains HP-42 and HP-80), in suspension with S. sanguis strain SA-1, were studied for adherence. Ten-fold-higher numbers of coaggregating strain HP-28 adhered in vitro to the streptococcal layer than did the non-coaggregating strains. S. sobrinus strain 6715 did not show appreciable adherence to the S. sanguis surface. Saliva did not affect the adherence of coaggregating or non-coaggregating H. parainfluenzae strains to S. sanguis strain SA-1. Bovine enamel chips, coated with streptococci, mounted on modified orthodontic appliances and placed in the mouths of three volunteers, facilitated the measurement of interbacterial adherence in vivo of streptomycin-resistant strains of H. parainfluenzae (HP-28R or HP-42R). Suspensions of bacteria were placed into the mouth, distributed throughout, and expectorated. After 15 or 120 minutes, the appliance with the chips was removed, the chips sonified, and colony-forming units (CFU) of streptomycin-resistant haemophili determined per chip.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗