Rats, Mice, and People: Rodent Biology and Management

Farm Management,

The Effect of Microcosm Biofilm Decontamination on Surface Topography, Chemistry, and Biocompatibility Dynamics of Implant Titanium Surfaces

Since the inception of dental implants, a steadily increasing prevalence of peri-implantitis has been documented. Irrespective of the treatment protocol applied for the management of peri-implantitis, this biofilm-associated pathology, continues to be a clinical challenge yielding unpredictable and variable levels of resolution, and in some cases resulting in implant loss. This paper investigated the effect of microcosm biofilm in vitro decontamination on surface topography, wettability, chemistry, and biocompatibility, following decontamination protocols applied to previously infected implant titanium (Ti) surfaces, both micro-rough -Sandblasted, Large-grit, Acid-etched (SLA)-and smooth surfaces -Machined (M). Microcosm biofilms were grown on SLA and M Ti discs. These were treated with TiBrushes (TiB), combination of TiB and photodynamic therapy (PDT), combination of TiB and 0.2%CHX/1%NaClO, plus or minus Ultraviolet-C (UV-C) radiation. Surface topography was evaluated by Scanning Electron Microscopy (SEM) and Laser Surface Profilometry. Surface function was analysed through wettability analysis. Surface chemistry evaluation of the discs was performed under SEM/Energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). Biocompatibility was tested with the cytocompatibility assay using human osteoblast-like osteosarcoma cell line (MG-63) cells. Elemental analysis of the discs disclosed chemical surface alterations resulting from the different treatment modalities. Titanium, carbon, oxygen, sodium, aluminium, silver, were identified by EDX as the main components of all the discs. Based on the data drawn from this study, we have shown that following the decontamination of Ti surfaces the biomaterial surface chemistry and topography was altered. The type of treatment and Ti surface had a significant effect on cytocompatibility (p = 0.0001). Although, no treatment modality hindered the titanium surface biocompatibility, parameters such as the use of chemical agents and micro-rough surfaces had a higher cytotoxic effect in MG-63 cells. The use of smooth surfaces, and photofunctionalisation of the TiO2 layer had a beneficial effect on cytocompatibility following decontamination

Development of remineralizing, antibacterial dental materials

Light curable methacrylate dental monomers containing reactive calcium phosphate filler (monocalcium phosphate monohydrate (MCPM) with particle diameter of 29 or 90 mu m) and beta-tricalcium phosphate (beta-TCP) at 1: 1 weight ratio in a powder:liquid ratio (PLR) of 1:1 or 3:1 and chlorhexidine diacetate (0 or 5 wt.%), were investigated. Upon light exposure, approximately 90% monomer conversion was gained irrespective of the formulation. Increasing the PLR promoted water sorption by the set material, induced expansion and enhanced calcium, phosphate and chlorhexidine release. Concomitantly, a decline in compressive and biaxial flexural strengths occurred. With a reduction in MCPM particle diameter, however, calcium and phosphate release was reduced and less deterioration in strength observed. After 24 h, the remaining MCPM had reacted with water and beta-TCP, forming, within the set materials, brushite of lower solubility. This provided a novel means to control water sorption, component release and strength properties. Measurable chlorhexidine release was observed for 6 weeks. Both diffusion rate and total percentage of chlorhexidine release decreased with lowering PLR or by adding buffer to the storage solutions. Higher chlorhexidine release was associated with reduced bacterial growth on agar plates and in a biofilm, fermenter. In cell growth media, brushite and hydroxyapatite crystals precipitated on the composite material surfaces. Cells spread on both these crystals and the exposed polymer composite surfaces, indicating their cell compatibility. These formulations could be suitable antibacterial, biocompatible and remineralizing dental adhesives/liners. (C) 2009 Published by Elsevier Ltd. on behalf of Acta Materialia. Inc

Systemic effects of periodontitis treatment in patients with type 2 diabetes: a 12 month, single-centre, investigator-masked, randomised trial

BACKGROUND: Chronic inflammation is believed to be a major mechanism underlying the pathophysiology of type 2 diabetes. Periodontitis is a cause of systemic inflammation. We aimed to assess the effects of periodontal treatment on glycaemic control in people with type 2 diabetes. METHODS: In this 12 month, single-centre, parallel-group, investigator-masked, randomised trial, we recruited patients with type 2 diabetes, moderate-to-severe periodontitis, and at least 15 teeth from four local hospitals and 15 medical or dental practices in the UK. We randomly assigned patients (1:1) using a computer-generated table to receive intensive periodontal treatment (IPT; whole mouth subgingival scaling, surgical periodontal therapy [if the participants showed good oral hygiene practice; otherwise dental cleaning again], and supportive periodontal therapy every 3 months until completion of the study) or control periodontal treatment (CPT; supra-gingival scaling and polishing at the same timepoints as in the IPT group). Treatment allocation included a process of minimisation in terms of diabetes onset, smoking status, sex, and periodontitis severity. Allocation to treatment was concealed in an opaque envelope and revealed to the clinician on the day of first treatment. With the exception of dental staff who performed the treatment and clinical examinations, all study investigators were masked to group allocation. The primary outcome was between-group difference in HbA1c at 12 months in the intention-to-treat population. This study is registered with the ISRCTN registry, number ISRCTN83229304. FINDINGS: Between Oct 1, 2008, and Oct 31, 2012, we randomly assigned 264 patients to IPT (n=133) or CPT (n=131), all of whom were included in the intention-to-treat population. At baseline, mean HbA1c was 8·1% (SD 1·7) in both groups. After 12 months, unadjusted mean HbA1c was 8·3% (SE 0·2) in the CPT group and 7·8% (0·2) in the IPT group; with adjustment for baseline HbA1c, age, sex, ethnicity, smoking status, duration of diabetes, and BMI, HbA1c was 0·6% (95% CI 0·3-0·9; p<0·0001) lower in the IPT group than in the CPT group. At least one adverse event was reported in 30 (23%) of 133 patients in the IPT group and 23 (18%) of 131 patients in the CPT group. Serious adverse events were reported in 11 (8%) patients in the IPT group, including one (1%) death, and 11 (8%) patients in the CPT group, including three (2%) deaths. INTERPRETATION: Compared with CPT, IPT reduced HbA1c in patients with type 2 diabetes and moderate-to-severe periodontitis after 12 months. These results suggest that routine oral health assessment and treatment of periodontitis could be important for effective management of type 2 diabetes. FUNDING: Diabetes UK and UK National Institute for Health Research.Diabetes UK and UK National Institute for Health Researc

Effects of Streptococcus pneumoniae Strain Background on Complement Resistance

Background: Immunity to infections caused by Streptococcus pneumoniae is dependent on complement. There are wide variations in sensitivity to complement between S. pneumoniae strains that could affect their ability to cause invasive infections. Although capsular serotype is one important factor causing differences in complement resistance between strains, there is also considerable other genetic variation between S. pneumoniae strains that may affect complement-mediated immunity. We have therefore investigated whether genetically distinct S. pneumoniae strains with the same capsular serotype vary in their sensitivity to complement mediated immunity.Methodology and Principal Findings: C3b/iC3b deposition and neutrophil association were measured using flow cytometry assays for S. pneumoniae strains with different genetic backgrounds for each of eight capsular serotypes. For some capsular serotypes there was marked variation in C3b/iC3b deposition between different strains that was independent of capsule thickness and correlated closely to susceptibility to neutrophil association. C3b/iC3b deposition results also correlated weakly with the degree of IgG binding to each strain. However, the binding of C1q (the first component of the classical pathway) correlated more closely with C3b/iC3b deposition, and large differences remained in complement sensitivity between strains with the same capsular serotype in sera in which IgG had been cleaved with IdeS.Conclusions: These data demonstrate that bacterial factors independent of the capsule and recognition by IgG have strong effects on the susceptibility of S. pneumoniae to complement, and could therefore potentially account for some of the differences in virulence between strains

Rats, mice and people: rodent biology and management

Australian Centre for International Agricultural Research Canberra 2003Infectious diseases in rodent populations are discussed from the twin viewpoints of their threat to human health and their role in rodent population dynamics. This is not, though, a definitive or exhaustive review, but an attempt to identify important and/or interesting themes. As regards human health, most recent attention has been directed at emerging infections, but some rodent-reservoir zoonoses are ‘sleeping giants’ that may awake at any time. Many human infections are never assigned an aetiological agent, and the ‘sources’ of many human pathogens remain unknown. Rodent-reservoir zoonoses may be important in both cases. In some cases, the economic damage caused by a pathogen may demand action even though medical effects, by most measures of public health, are trivial. Finally, the ‘hottest’ topic in human infectious diseases is bioterrorism. Rodent-reservoir zoonoses account for many of the apparently prime candidates. As regards rodent populations, four topics are addressed, focusing on work from our group at Liverpool—the effects of endemic pathogens on host fecundity as evidenced by experimental studies; their effects on host survival as evidenced by the analysis of field data; analyses of the transmission dynamics of infection and the light these throw on common theoretical assumptions; and the possible role of pathogens in microtine rodent cycles. Finally, at the interface between rodent populations and human health, the importance of distinguishing between reservoir, liaison and incidental hosts is emphasised; the contrasts between controlling zoonotic infections and other human infections are discussed; and a connection between contrasting types of rodent zoonosis and the nature of pathogen virulence is suggested

Oral Microcosm Biofilms Grown under Conditions Progressing from Peri-Implant Health, Peri-Implant Mucositis, and Peri-Implantitis

Peri-implantitis is a disease influenced by dysbiotic microbial communities that play a role in the short- and long-term outcomes of its clinical treatment. The ecological triggers that establish the progression from peri-implant mucositis to peri-implantitis remain unknown. This investigation describes the development of a novel in vitro microcosm biofilm model. Biofilms were grown over 30 days over machined titanium discs in a constant depth film fermentor (CDFF), which was inoculated (I) with pooled human saliva. Following longitudinal biofilm sampling across peri-implant health (PH), peri-implant mucositis (PM), and peri-implantitis (PI) conditions, the characterisation of the biofilms was performed. The biofilm analyses included imaging by confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM), selective and non-selective culture media of viable biofilms, and 16S rRNA gene amplification and sequencing. Bacterial qualitative shifts were observed by CLSM and SEM across conditions, which were defined by characteristic phenotypes. A total of 9 phyla, 83 genera, and 156 species were identified throughout the experiment. The phyla Proteobacteria, Bacteroidetes, Firmicutes, Fusobacteria, and Actinobacteria showed the highest prevalence in PI conditions. This novel in vitro microcosm model provides a high-throughput alternative for growing microcosm biofilms resembling an in vitro progression from PH&ndash;PM&ndash;PI conditions

Drinking Habits Are Associated with Changes in the Dental Plaque Microbial Community▿

Caries and gingivitis are the most prevalent oral infectious diseases of humans and are due to the accumulation of dental plaque (a microbial biofilm) on the tooth surface and at the gingival margin, respectively. Several in vitro and in vivo studies have shown that many natural components of foods and beverages inhibit the adhesion of and/or exert activity against oral bacteria. These biological activities have mainly been attributed to the polyphenol fraction. In order to explore the possibility that diet can alter the dental plaque community, in this study we evaluated the composition of the microbiota of supra- and subgingival plaque samples collected from 75 adult subjects with different drinking habits (drinkers of coffee, red wine, or water for at least 2 years) by analyzing the microbial population through the separation of PCR-amplified fragments using the denaturing gradient gel electrophoresis (DGGE) technique. The mean numbers of bands of the DGGE profiles from all three categories were evaluated. There were no significant differences between the two kinds of plaque collected from the control group (water drinkers), and this group showed the highest number of bands (supragingival plaque, 18.98 ± 3.16 bands; subgingival plaque, 18.7 ± 3.23 bands). The coffee and wine drinker groups generated the lowest numbers of bands for both supragingival plaque (coffee drinkers, 8.25 ± 3.53 bands; wine drinkers, 7.93 ± 2.55 bands) and subgingival plaque (coffee drinkers, 8.3 ± 3.03 bands; wine drinkers, 7.65 ± 1.68 bands). The differences between coffee drinkers or wine drinkers and the control group (water drinkers) were statistically significant. A total of 34 microorganisms were identified, and the frequency of their distribution in the three subject categories was analyzed. A greater percentage of subjects were positive for facultative aerobes when supragingival plaque was analyzed, while anaerobes were more frequent in subgingival plaque samples. It is noteworthy that the frequency of identification of anaerobes was significantly reduced when the frequencies for coffee and wine drinkers were compared with the frequencies for subjects in the control group. The DGGE profiles of the organisms in both plaque samples from all groups were generated and were used to construct dendrograms. A number of distinct clusters of organisms from water, coffee, and wine drinkers were formed. The clustering of some of the DGGE results into cohort-specific clusters implies similarities in the microbiotas within these groups and relevant differences in the microbiotas between cohorts. This supports the notion that the drinking habits of the subjects may influence the microbiota at both the supragingival and the subgingival levels

Rats, mice and people: rodent biology and management

Australian Centre for International Agricultural Research Canberra 2003Infectious diseases in rodent populations are discussed from the twin viewpoints of their threat to human health and their role in rodent population dynamics. This is not, though, a definitive or exhaustive review, but an attempt to identify important and/or interesting themes. As regards human health, most recent attention has been directed at emerging infections, but some rodent-reservoir zoonoses are ‘sleeping giants’ that may awake at any time. Many human infections are never assigned an aetiological agent, and the ‘sources’ of many human pathogens remain unknown. Rodent-reservoir zoonoses may be important in both cases. In some cases, the economic damage caused by a pathogen may demand action even though medical effects, by most measures of public health, are trivial. Finally, the ‘hottest’ topic in human infectious diseases is bioterrorism. Rodent-reservoir zoonoses account for many of the apparently prime candidates. As regards rodent populations, four topics are addressed, focusing on work from our group at Liverpool—the effects of endemic pathogens on host fecundity as evidenced by experimental studies; their effects on host survival as evidenced by the analysis of field data; analyses of the transmission dynamics of infection and the light these throw on common theoretical assumptions; and the possible role of pathogens in microtine rodent cycles. Finally, at the interface between rodent populations and human health, the importance of distinguishing between reservoir, liaison and incidental hosts is emphasised; the contrasts between controlling zoonotic infections and other human infections are discussed; and a connection between contrasting types of rodent zoonosis and the nature of pathogen virulence is suggested

One-Year Clinical Outcomes of the Hybrid CTO Revascularization Strategy After Hospital Discharge:A Subanalysis of the Multicenter RECHARGE Registry

OBJECTIVES: Percutaneous coronary intervention (PCI) of chronic total occlusion (CTO) has historically been associated with higher event rates during follow-up. The hybrid algorithm and contemporary wiring and dissection re-entry (DR) techniques can potentially improve long-term outcomes after CTO-PCI. This study assessed the long-term clinical outcomes of the hybrid CTO practice, when applied by operators with varying experience levels. METHODS: We examined the 1-year clinical events after hospital discharge of the RECHARGE population, according to technical outcome and final technique. The primary endpoint was major adverse cardiac event (MACE) rate. Centers that provided ≥90% complete 12-month follow-up were included. RESULTS: Follow-up data of 1067 out of 1165 patients (92%) were provided by 13 centers. Mean follow-up duration was 362.8 ± 0.9 days. One-year MACE-free survival rate was 91.3% (974/1067). MACE included death (1.9%; n = 20), myocardial infarction (1.4%; n = 15), target-vessel failure (5.9%; n = 63), and target-vessel revascularization (TVR) (5.5%; n = 59). Non-TVR was performed in 6.7% (n = 71). MACE was significantly in favor of successful CTO-PCI (8.0% vs 13%; P=.04), even after adjusting for baseline differences (adjusted hazard ratio, 0.59; 95% confidence interval, 0.36-0.98; P=.04). Other events, including individual MACE components, were comparable with respect to technical outcome and final technique (DR vs non-DR techniques). CONCLUSIONS: The use of the hybrid algorithm with contemporary techniques by moderate to highly experienced operators for CTO-PCI is safe and associated with a low 1-year event rate. Successful procedures are associated with a better MACE rate. DR techniques can be used as first-line strategies alongside intimal wiring techniques without compromising clinical outcomes