Gene transfer in bacterial biofilms.
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Bacteria↗
Biomedical subjects
M Wilson
Publications and source records attributed to M Wilson.
Antibacterial activity of particulate bioglass against supra- and subgingival bacteria.
Particulate Bioglass is a bioactive material used in the repair of periodontal defects. This material undergoes a series of surface reactions in an aqueous environment which lead to osseointegration. The aim of this study was to determine whether these reactions exerted an antibacterial effect on a range of oral bacteria. Streptococcus sanguis, Streptococcus mutans and Actinomyces viscosus were suspended in nutrient broth (NB), artificial saliva (AS) or Dulbecco's modified eagle medium plus 10% foetal calf serum (DMEM + 10%FCS), with or without particulate Bioglass. All bacteria showed reduced viability following exposure to Bioglass in all the media after 1 h. This antibacterial effect increased after 3 h. Porphyromonas gingivalis, Fusobacterium nucleatum, Prevotella intermedia and Actinobacillus actinomycetemcomitans were suspended in either BM broth or 40% horse serum (HS) in RPMI. A considerable reduction in viability was observed with all bacteria tested, in both media, compared to inert glass controls. In further experiments it was found that the viability of S. sanguis was significantly reduced following exposure to NB pre-incubated with Bioglass. Additionally, it was found that neutralisation of this highly alkaline solution eliminated the antibacterial effect. Moreover, a solution of NB and NaOH (of equivalent pH) exerted an antibacterial effect of similar magnitude to that of the solution pre-incubated with Bioglass. Thus, particulate Bioglass exerts an antibacterial effect on certain oral bacteria, possibly by virtue of the alkaline nature of its surface reactions. This may reduce bacterial colonisation of its surface in vivo.
Actinomyces viscosus↗
Genomic organization and differential expression of channel catfish MHC class I genes.
Two clones, designated Icpu-UA/3 and Icpu-UA/26, were isolated from a genomic library prepared from a single homozygous gynogenetic channel catfish. Sequence analysis showed that each clone encoded a gene product containing features conserved among MHC class I molecules. The genomic organization of both clones indicated that each domain, with the exception of the cytoplasmic, was encoded by a separate exon. Moreover, like mammals, catfish cytoplasmic regions were encoded by three exons rather than two as previously described for other teleost MHC class I genes. Analysis of nucleotide sequences upstream of catfish class I genes revealed the presence of several regulatory motifs similar to those seen in mammalian class I genes. These included a TATA box, Enhancer B, Site alpha, ISRE, and GAS elements. To determine the functional significance of these elements, EMSAs and tissue expression assays were performed. EMSAs demonstrated that an Enhancer B element within Icpu-UA/26, and an imperfect Enhancer B element and/or a GC-rich region within Icpu-UA/3 were responsible for formation of specific DNA/protein complexes. Expression studies detected Icpu-UA/26 transcripts in all tissues tested, whereas Icpu-UA/3 encoded messages were seen in a limited number of tissues. These results define the intron/exon organization of catfish MHC class I genes, suggest that Icpu-UA/3 encodes a nonclassical gene, and provide the first functional evidence that upstream sequences, similar to those seen in mammalian class I genes, play important roles in regulating teleost MHC gene expression.
Amino Acid Sequence↗
A case of open-air carbon monoxide poisoning in a 10-year-old boy.
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Carbon Monoxide Poisoning↗
Reversal of chronic cyclosporin nephrotoxicity after heart transplantation.
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Journal Article↗
Staphylococcus aureus accessory regulators: expression within biofilms and effect on adhesion.
Many of the genes encoding the virulence factors for Staphylococcus aureus are controlled by the accessory gene regulator (agr) and staphylococcal accessory regulator (sar). This regulation may be affected by the environment in which the organisms are grown. In the majority of ecosystems, bacteria grow attached to surfaces and form biofilms. We used S. aureus strains containing mutations inactivating agr and sar to determine whether the presence of these genes influences the attachment of the bacterium to a surface. We also used strains harbouring reporter constructs of the agr and sar operons to determine their expression in biofilms. The attachment study results showed that the sarA mutant strain adhered better to glass than did the agrA mutant or the wild type. There was an increased adherence to fibronectin-coated glass for all three strains compared to glass. Thus, these adhesion studies demonstrate that agr and sar have pleiotrophic effects on the surface expression of molecules responsible for binding to different substrata. In the biofilms higher numbers of bacteria and the greatest expression were observed at the base, but there were no observable differences between the reporter constructs. Expression of the agr and sar reporter fusions was significantly higher in the deepest layers of the biofilms where the greatest numbers of bacteria were also observed, perhaps as one might expect for genes that are regulated in a cell density dependent fashion.
Bacterial Adhesion↗
Amine and tin fluoride inhibition of Streptococcus sanguis adhesion under continuous flow.
This study evaluated the ability of topically applied amine fluoride (AmF) and AmF-tin fluoride to inhibit the adhesion of Streptococcus sanguis within a parallel plate flow cell system. One of three AmF compounds and two tin fluoride preparations significantly reduced the net bacterial adhesion to conditioned glass over a 1-h period. Tin(IV) fluoride inhibited S. sanguis adhesion to the greatest extent, and this was shown to be dependent on the formation of the conditioning film prior to agent application.
Bacterial Adhesion↗
Capnocytophaga granulosa and Capnocytophaga haemolytica: novel species in subgingival plaque.
BACKGROUND: The oral cavity accommodates one of the most diverse microfloras in the human body. Knowledge of this microflora, and of the periodontal microflora in particular, proves crucial towards an understanding of the bacterial-host interactions which lead to the development of infectious inflammatory periodontal diseases. Capnocytophaga species have been implicated as putative periodontal pathogens. To date, only 3 members of this genus (C. gingivalis, C. ochracea and C. sputigena) have been isolated from subgingival plaque. AIM: This communication reports the isolation of 2 recently-speciated strains, namely C. granulosa and C. haemolytica, from subgingival plaque collected from adult periodontitis patients. MATERIAL AND METHODS: Subgingival plaque was collected from 29 patients with chronic adult periodontitis. Plaque samples were inoculated onto fastidious anaerobe agar and incubated anaerobically for 5 days. Routine identification of clinical isolates was performed by 16S rRNA PCR-RFLP analysis, using Cfo I as restriction enzyme and corroborated by 16S rRNA gene sequencing. RESULTS: 16 of 29 patients (55%) tested positive for either C. granulosa and or C. haemolytica. A total of 70 isolates (63 C. granulosa and 7 C. haemolytica) were cultivated from subgingival plaque. 15 (51%) patients tested positive for C. granulosa, and 3 (10%) patients tested positive for C. haemolytica. CONCLUSION: This is the 1st report which recounts the presence of C. granulosa and C. haemolytica in subgingival plaque. Further research is required to establish the relative proportions of these species subgingivally in health and disease.
Adult↗
Perceiving imitatible stimuli: consequences of isomorphism between input and output.
For more than a century, psychologists have been intrigued by the idea that mental representations of perceived human actions are closely connected with mental representations of performing those same actions. In this article, connections between input and output representations are considered in terms of the potential for imitation. A broad range of evidence suggests that, for imitatible stimuli, input and output representations are isomorphic to one another, allowing mutual influence between perception and motoric planning that is rapid, effortless, and possibly obligatory. Thus, the cognitive consequences of imitatibility may underlie such diverse phenomena as phoneme perception; imitation in neonates; echoic memory; stimulus-response compatibility; conduction aphasia; maintenance rehearsal; and a variety of developmental and social activities such as language acquisition, social learning, empathy, and monitoring one's own behavior.
Cognition↗
Bigger is better: maternal and neonatal predictors of hematopoietic potential of umbilical cord blood units.
Umbilical cord blood (CB) is a useful stem cell source for patients without matched family donors. CB banking is expensive, however, because only a small percentage of the cord units stored are used for transplantation. In this study, we determined whether maternal factors, such as race, age, and smoking status have an effect on laboratory parameters of hematopoietic potential, such as viability, cell counts, CD34+ cell counts, and CFU-GM. We studied the effect of neonatal characteristics such as birth order, birth weight, gestational age, and sex of the baby on the same laboratory parameters. Race and maternal age had no effect on these laboratory parameters. In multivariate analysis, babies of longer gestational age had higher cell counts, but lower CD34+ cell counts and CFU-GM. Bigger babies had higher cell counts, more CD34+ cells, and more CFU-GM. Women with fewer previous live births also produced cord units with higher cell counts, CFU-GM, and CD34+ cell counts. Specifically, each 500 g increase in birth weight contributed to a 28% increase in CD34+ cell counts, each week of gestation contributed to a 9% decrease in CD34+cell counts, and each previous birth contributed to a 17% decrease in CD34+ cell counts (all P < 0.05). These data may be used to select the optimal cord blood donors and allow CB banks efficient resource allocation.
Adult↗
An in vitro evaluation of the antimicrobial efficacy of irrigants on biofilms of root canal isolates.
AIM: The bactericidal effect of four antimicrobial agents was investigated against single-species biofilms derived from a range of root canal isolates. METHODOLOGY: Single-species biofilms of Prevotella intermedia, Peptostreptococcus micros, Streptococcus intermedius, Fusobacterium nucleatum and Enterococcus faecalis were generated on membrane filter discs and subjected to 15 min or 1 h incubation with 5 p.p.m. colloidal silver, 2.25% sodium hypochlorite (NaOCl), 0.2% chlorhexidine, 10% iodine or phosphate buffered saline (PBS) as a control. The antimicrobial activity of the agents was neutralized and the bacterial cells were harvested from the discs by vortexing, serially diluted in reduced transport fluid, plated on fastidious anaerobe agar containing 5% horse blood, incubated anaerobically and colony-forming units calculated. RESULTS: Iodine and NaOCl were more effective than chlorhexidine except against P. micros and P. intermedia where they were all 100% effective. Iodine and NaOCl elicited a 100% kill after 1 h incubation for all strains used. However, after 15 min, they showed differing bactericidal effects depending on the strain. None of the agents were effective against F. nucleatum after 15 min but NaOCl, iodine and chlorhexidine were all effective after 1 h. Colloidal silver was generally ineffective. CONCLUSIONS: The effectiveness of a particular agent was dependent on the nature of the organism in the biofilm and on the contact time. NaOCl was generally the most effective agent tested, followed by iodine. However the clinical efficacy of these agents must be considered in light of the complex root canal anatomy and polymicrobial nature of root canal infections.
Anti-Infective Agents, Local↗
A new in vitro model for the study of microbial microleakage around dental restorations: a preliminary qualitative evaluation.
AIM: The aim of this study was to develop an in vitro model to replicate microbial microleakage at a tooth/ restoration interface using a constant depth film fermentor (CDFF). METHODOLOGY: Amalgam restorations were placed in machined bovine dentine cylinders and sealed externally with varnish, leaving a 1-mm perimeter exposed around the tooth/restoration interface. The dentine cylinders were housed in a CDFF and 300-microm thick microcosm dental plaques were grown over their exposed surfaces. The biofilms were maintained with a mucin-containing artificial saliva for up to 8 weeks. Cylinders were aseptically removed from the CDFF (at 1, 2, 4, & 8 weeks) and surface-decontaminated with validated protocols prior to splitting and sampling of apposing amalgam and dentine surfaces. Scanning electron microscopy (SEM) was used to ascertain the position and structure of the bacterial aggregates. Bacterial viability was determined by vital staining of the bacteria in situ. RESULTS: At all sampling times, SEM showed cocci, rods and filaments on both amalgam and dentine surfaces; some originated as cascades from the surface biofilm and extended into the tooth/restoration microspace. Vital staining showed the majority of bacteria from both dentine and amalgam surfaces to be viable. CONCLUSION: This preliminary investigation showed that the CDFF may be a valuable tool for the in vitro study of the dynamics of microbial microleakage around dental restorations.
Animals↗
The effects of surface roughness and type of denture acrylic on biofilm formation by Streptococcus oralis in a constant depth film fermentor.
AIMS: To investigate the effects of surface roughness and type of denture acrylic on the early development of a Streptococcus oralis biofilm in a constant depth film fermentor (CDFF). METHODS AND RESULTS: Streptococcus oralis was incubated with acrylic of known surface roughness in the CDFF. Adherent Strep. oralis were enumerated by viable counting. Cold-cure acrylic was rougher (P < 0.01) than heat-cure acrylic after polishing with abrasive paper of any given grit-grade. Heat-cure acrylic was colonized by fewer (P < 0.001) bacteria than cold-cure acrylic at any given surface roughness. The number of bacteria adhering to heat-cure and cold-cure acrylic increased linearly with mean surface roughness after 2 h incubation, the increase being greater (P < 0.001) for the cold-cure compared with the heat-cure acrylic. However, after 4 h incubation, surface roughness appeared to have no effect on the number of adherent bacteria. CONCLUSION: The type of acrylic used, and its roughness, affect the early stages of biofilm formation by Strep. oralis. SIGNIFICANCE AND IMPACT OF THE STUDY: Choosing an appropriate type of smooth acrylic could lead to reduced biofilm formation in vivo.
Biofilms↗
Assessment of five culture media for the growth and isolation of Capnocytophaga spp.
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Bacteriological Techniques↗
Clinical evaluation of atypical glandular cells of undetermined significance.
OBJECTIVE: This study was undertaken to determine the clinical implications of the finding of atypical glandular cells of undetermined significance in cervical cytologic specimens in our patient population. STUDY DESIGN: A retrospective study was performed. All cervical cytologic examinations with the diagnosis of atypical cells of undetermined significance between January 1992 and June 1997 were identified by means of a computerized database. Medical records were reviewed to identify patient demographic characteristics and to determine the presence or absence of associated pathologic conditions of the cervix and endometrium. The chi2 test and analysis of variance were applied to dichotomous and continuous variables, respectively, to determine the implications of a cytologic evaluation of atypical glandular cells of undetermined significance. RESULTS: Cytologic results reported as atypical glandular cells of undetermined significance were obtained in a patient cohort of 492. Atypical glandular cells of undetermined significance was the only cytologic diagnosis in 224 patients; 268 patients had both atypical glandular cells of undetermined significance and an additional squamous abnormality, including atypical squamous cells of undetermined significance and cervical intraepithelial neoplasia I, II, or III. Two patients were excluded because of a history of endometrial cancer. A histologic evaluation was obtained within 1 year in 353 cases. Among the 353 patients who had a histologic evaluation performed, 227 (64%) had benign cervical and endometrial findings. There were 18 glandular lesions (5%), including complex hyperplasia with atypia, adenocarcinoma in situ of the cervix, adenocarcinoma of the cervix, and adenocarcinoma of the endometrium. A squamous lesion was present in 108 patients (31%). Most squamous lesions (81%) were found in patients with atypical glandular cells of undetermined significance associated with a squamous abnormality, whereas only 19% were found in patients with atypical glandular cells of undetermined significance as the only diagnosis. Women <35 years old had a much higher frequency of histologic abnormalities than did women >50 years old (P <.0001), with most of these lesions being squamous. Women >50 years old had a much higher frequency of glandular histologic abnormalities (P <.001). CONCLUSION: More than a third of women with Papanicolaou smears reported as showing atypical glandular cells of undetermined significance will be found to have a histologic abnormality. Women <35 years old with a cytologic evaluation of atypical glandular cells of undetermined significance have a higher frequency of histopathologic findings, with most being squamous lesions. Women with a cytologic evaluation of atypical glandular cells of undetermined significance who are >50 years old have more glandular lesions than do younger women. The term atypical glandular cells of undetermined significance is a misnomer. The significance of this cytologic finding has been defined and represents a marker for serious pathologic processes.
Adenocarcinoma↗
Solar ultraviolet exposures at ground level in tree shade during summer in south east Queensland.
Data are presented on the effect of the tree canopy transmittance in the visible waveband (VT), canopy width, height and height of the start of the tree canopy (CH) on the solar UV in tree shade on a horizontal plane at ground level during a Southern Hemisphere summer. Of these factors, the VT and CH have an influence on the UV irradiances in the tree shade. The shade ratios (UV in tree shade to that in full sun) for erythemal UV ranged from 0.71 to 0.42, 0.54 to 0.29 and 0.63 to 0.41 for morning, noon and afternoon, respectively, for the VT range of 0.4-1.0. Over the same VT range, the shade ratios for UVA ranged from 0.61 to 0.28, 0.50 to 0.22 and 0.49 to 0.29 for morning, noon and afternoon, respectively. The UV exposures in the tree shade decreased with the VT with a marginally higher decrease in the irradiances for the UVA compared to the erythemal UV. Despite the protection by the tree shade, significant UV in the tree shade of approximately 4 MED (minimum erythemal dose) were received for the latitude in this research on a cloud free summer day on a horizontal plane over a 2-h period centred about solar noon.
Environmental Exposure↗
Papillary renal cell carcinoma: analysis of germline mutations in the MET proto-oncogene in a clinic-based population.
Approximately 10% of all renal cell carcinomas (RCCs) present a distinctive papillary histology. Familial papillary RCC (PRCC) has been described, but the majority of cases appear to be sporadic. Recently, germline mutations in the MET proto-oncogene on chromosome 7 have been identified in families with hereditary PRCC. We evaluated 59 patients with PRCC for the frequency of MET germline mutations to determine the value of genetic screening of this patient population. Between 1976 and 1997, 165 patients were identified with PRCC by retrospective chart review. Fifty-nine of 133 surviving patients agreed to provide a family history, a blood specimen, and informed consent for genetic research. DNA was isolated from peripheral blood leukocytes. Denaturing high-performance liquid chromatography (DHPLC) followed by genomic sequencing was performed on eight exons of the MET proto-oncogene, including exons 5-7 of the extracellular domain, exon 14, and exons 16-19 of the tyrosine kinase domain. The 59 patients in this study included 49 men and 10 women with a mean age at diagnosis of 61 years. Bilateral and/or multifocal disease was present in 13 cases (22%). No germline mutations were detected in the studied exons of the MET proto-oncogene (exons previously reported to contain deleterious mutations in familial PRCC). No pathological MET proto-oncogene germline mutations were identified in 59 patients with PRCC. The germline mutation rate in this clinic-based population of individuals with PRCC approaches 0% (CI = 0-6.18). MET proto-oncogene germline mutation screening does not appear to be clinically indicated in patients with PRCC without additional evidence for a genetic predisposition (positive family history, unusual age at onset, bilateral disease).
Aged↗
IL-2 linked to a peptide from influenza hemagglutinin enhances T cell activation by affecting the antigen-presentation function of bone marrow-derived dendritic cells.
Chimeric proteins containing antigen linked to cytokines have shown some promise as vaccine candidates but little is known of their mechanism of action, particularly at the level of the antigen-presenting cell. We have investigated this using a chimeric protein in which an immunodominant T cell epitope from influenza hemagglutinin peptide (HA), recognized in the context of I-E(d), was fused to IL-2. Immature murine dendritic cells (DC) derived from bone marrow (BMDC) were used to present the chimeric protein to a T cell hybridoma with TCR specific for the HA peptide (A5 cell line). HA-IL-2 was found to induce significantly higher T cell activation than HA alone. Although the inclusion of IL-2 and HA separately did increase the response of A5 cells compared to HA alone, they were not as effective as the HA-IL-2 chimeric protein. When an antibody known to block IL-2 receptor alpha chain (CD25) was included, A5 activation was reduced, suggesting a role for the receptor in this process. Expression of CD25 on A5 cells was low during activation, implying that the effect was mediated by CD25(+) BMDC. Antigen uptake and processing of HA-IL-2 by BMDC was required since fixing BMDC, prior to antigen exposure, greatly reduced their ability to activate A5 cells. The function of CD25 on DC is currently unknown. Our results suggest this receptor may play a role in antigen uptake and subsequent T cell activation by receptor-mediated endocytosis of antigen attached to IL-2. This finding that may have implications for the development of a new generation of vaccines.
Adjuvants, Immunologic↗