Synergistic virulence of Porphyromonas gingivalis and Treponema denticola in a murine periodontitis model

Chronic periodontitis is characterized by the destruction of the tissues supporting the teeth and has been associated with the presence of a subgingival polymicrobial biofilm containing Porphyromonas gingivalis and Treponema denticola. We have investigated the potential synergistic virulence of P. gingivalis and T. denticola using a murine experimental model of periodontitis. An inoculation regime of four intra-oral doses of 1 × 10(10) P. gingivalis cells induced significant periodontal bone loss compared with loss in sham-inoculated mice, whereas doses of 1 × 10(9) cells or lower did not induce bone loss. Inoculation with T. denticola with up to eight doses of 1 × 10(10) cells failed to induce bone loss in this model. However, four doses of a co-inoculum of a 1 : 1 ratio of P. gingivalis and T. denticola at 5 × 10(8) or 1 × 10(9) total bacterial cells induced the same level of bone loss as four doses of 1 × 10(10) P. gingivalis cells. Co-inoculation induced strong P. gingivalis-specific T-cell proliferative and interferon-γ-dominant cytokine responses, and induced a strong T. denticola-specific interferon-γ dominant cytokine response. Only at the higher co-inoculum dose of 1 × 10(10) total cells was a T. denticola-specific T-cell proliferative response observed. These data show that P. gingivalis and T. denticola act synergistically to stimulate the host immune response and to induce alveolar bone loss in a murine experimental periodontitis model.     

The lateral leeway in the habitual intercuspation: experimental studies and literature review

The habitual intercuspation is used ubiquitous for manufacturing small dental restorations. However, a little is known on its precision. The aim of the present study was therefore to investigate the unambiguity and accuracy of the habitual occlusion in mounted plaster casts from fully dentate persons. Eighty-one fully dentate volunteers, 36 women and 45 men aged 26.8 +/- 6.2 years (18-55 years), with minor fillings and no signs or symptoms of TMD took part in the experiments. Silicone impressions were taken, poured with stone plaster and the obtained casts mounted into Dentatus ARL(R)- articulators using an individual face bow transfer. Subsequently, the models were transferred to a custom-made measuring articulator where the lateral leeway and the accuracy of the hand-held habitual intercuspation were quantified in the condylar area. Measurements were repeated seven times with the upper cast pushed either to the maximum right or the maximum left intercuspation. The hand-held habitual intercuspation of upper and lower cast proved ambiguous in 57% of pairs of casts. The average lateral leeway of the habitual intercuspation in the condylar area was 0.10 +/- 0.05 mm (0-0.51 mm; median 0.07 mm) between the maximum right and left occlusal positions. The average accuracy of three repeated measurements was 0.22 +/- 0.09 mm (0.02-1.17 mm; median 0.16 mm). Natural occlusal surfaces in a full dentition do not guarantee an unambiguous habitual intercuspation of the plaster casts. The described leeway and technical limits might be possible causes for occlusal adjustments that are sometimes necessary when inserting restorations manufactured in habitual intercuspation.     

Evaluation of treatment outcomes for Stenotrophomonas maltophilia bacteraemia

Objective

The goal of this study was to retrospectively collect data about treatment outcomes in patients diagnosed with Stenotrophomonas maltophilia bacteraemia over a period of 20 years and evaluate these data with respect to the efficacy of treatment options.

Methods

The setting was a 700-bed tertiary care hospital in a large urban area. Hospital databases and medical records provided information about episodes of S. maltophilia, patient characteristics and treatment outcomes. Patients with at least one positive blood culture for S. maltophilia were included in the study. Data were analysed with respect to clinical improvement and mortality ≤30 days after the onset of infection. We compared patient characteristics, laboratory values and treatments by using the Chi-square or Fisher’s exact tests and the Mann–Whitney test.

Results

We investigated 27 patients with S. maltophilia bacteraemia. The focus of infection was a central venous catheter in 18 (67 %) cases. The 30-day mortality rate was 11 %. All patients who were treated with an antibiotic that was effective in vitro against the pathogen recovered clinically and survived ≥30 days after the onset of infection. The most frequently used antibiotic was trimethoprim–sulfamethoxazole administered alone or in combination with a fluoroquinolone.

Conclusions

Despite the fact that S. maltophilia is resistant to multiple antibiotics, the prognosis for patients with S. maltophilia bacteraemia is good when they are treated with antibiotics that are effective against this pathogen in vitro.     

Impact of a severe acute respiratory syndrome outbreak in the emergency department: an experience in Taiwan

Objectives: To evaluate the impact of a severe acute respiratory syndrome (SARS) outbreak in the emergency department (ED). Methods: Computerised records of all ED visits in January and May 2003 were analysed and compared, representing before and during the SARS epidemic respectively. Data were grouped into two categories. Group 1 was the indicators of impact on patients, including visitor''s condition classification, number of patients that died on arrival (DOA), received cardiopulmonary resuscitation, underwent endotracheal intubation, needed mechanical ventilation, discharged against medical advice (AAD), died in the ED, and the admission rate to wards. Group 2 was the indicators of impact on the quality of medical care, including number of visits that returned within 72 hours (early returns), underwent chest radiography, upper abdomen sonography or computed tomography, and the length of stay. Results: There were 6650 and 3901 consecutive encounters in January and May 2003 respectively. There were significant differences on condition classifications (p = 0.000), increased rate of patients that underwent endotracheal intubation (p = 0.003), needed mechanical ventilation (p = 0.020), and admission (p = 0.000). The rate of AAD decreased significantly (p = 0.024). There was no significant difference on early returns, although the length of stay in the ED increased (p = 0.043). The number of visits that underwent chest radiological examination increased (p = 0.000) and upper abdomen sonography (p = 0.007) decreased significantly in May. Conclusions: SARS had an impact on the medical service system and decreased visits by 40% in the ED. Patients visiting the ED had more severe conditions than before. The impact of SARS on quality of medical care can be minimised when adequate infection control measures are applied.     

Minimal mechanical load and tissue culture conditions preserve native cell phenotype and morphology in tendon—a novel ex vivo mouse explant model

Appropriate mechanical load is essential for tendon homeostasis and optimal tissue function. Due to technical challenges in achieving physiological mechanical loads in experimental tendon model systems, the research community still lacks well‐characterized models of tissue homeostasis and physiological relevance. Toward this urgent goal, we present and characterize a novel ex vivo murine tail tendon explant model. Mouse tail tendon fascicles were extracted and cultured for 6 days in a load‐deprived environment or in a custom‐designed bioreactor applying low magnitude mechanical load (intermittent cycles to 1% strain, at 1 Hz) in serum‐free tissue culture. Cells remained viable, as did collagen structure and mechanical properties in all tested conditions. Cell morphology in mechanically loaded tendon explants approximated native tendon, whereas load‐deprived tendons lost their native cell morphology. These losses were reflected in altered gene expression, with mechanical loading tending to maintain tendon specific and matrix remodeling genes phenotypic of native tissue. We conclude from this study that ex vivo load deprivation of murine tendon in minimal culture medium results in a degenerative‐like phenotype. We further conclude that onset of tissue degeneration can be suppressed by low‐magnitude mechanical loading. Thus a minimal explant culture model featuring serum‐free medium with low mechanical loads seems to provide a useful foundation for further investigations. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1383–1390, 2018.

     

Real-time assessment of anteroposterior stability of spinal segments

Purpose

While anteroposterior instability of spinal segments is regarded as an important biomechanical aspect in the clinical evaluation of lumbar pathologies, the reliability of the available diagnostic tools is limited and an intraoperative method to quantify stability is lacking. The aim of this study was to develop and validate an instrument to measure the anteroposterior stability of a spinal segments in real-time.

Methods

Torsi of five fresh-frozen human cadavers were used for this study. After pedicle screw insertion, a specifically modified reposition tool composed with load and linear sensors was used to measure the segmental anteroposterior motion caused by 100 N anterior and posterior force during 5 loading cycles on either side of the instrumentation by two different operators. The spinal segments were then resected from the torsi and anteroposterior loading with ± 100 N was repeated in an advanced biomechanical spine testing setup as a reference measurement. The Inter-correlation coefficient (ICC) was used for validation of the “intraoperative” device.

Results

Inter-operator repeatability of the measurements showed an ICC of 0.93 (p < 0.0001) and the bilateral (left–right) comparison had an ICC of 0.73 (p < 0.0001). The ICC resulting from the comparison to the reference measurement was 0.82 (p < 0.0001) without offset correction, and 0.9 (p < 0.0001) with offset correction. The ICC converged at this value already after two of the five performed loading cycles.

Conclusion

An accurate and reliable measurement tool is developed and validated for real-time quantification of anteroposterior stability of spinal segments and serves as a basis for future intraoperative use.

     

Inhibition of endogenous pancreatic enzyme secretion by oral pancreatic enzyme treatment

BACKGROUND: The existence of a feedback mechanism for exocrine pancreatic secretion in humans is controversial. Exclusion of proteases from the duodenum stimulates exocrine pancreatic secretion. Conversely, addition of exogenous enzymes could reduce the enzyme secretion. Further investigation of the feedback mechanism should be performed under the most physiological conditions. In the present study we investigated exocrine pancreatic function by measuring fecal enzyme output in healthy volunteers consuming a normal diet, before and during a time course of exogenous pancreatic enzyme supplementation. MATERIAL AND METHODS: Twenty-five healthy subjects (HS) were given two different doses (30 and 60 FIP proteases kg(-1) d(-1)) divided by the number of meals. In all subjects, fecal elastase-1 (E1) concentrations and chymotrypsin (ChT) activities were measured without and with enzyme supplements after 7 days of treatment. In eight subjects, E1 concentrations and ChT activities were measured daily for 10 consecutive days. The subjects were given a dose regimen of 100 FIP proteases kg(-1) d(-1)(divided by the number of meals) for the first 7 days. RESULTS: Oral pancreatic treatment dose-dependently inhibited endogenous pancreatic secretion measured with the use of E1 concentrations. In both regimen groups, the differences were statistically significant. The exogenous enzymes, which interfere with colorimetric method for ChT, dose-dependently increased ChT output. However, only the higher dose resulted in a statistically significant difference. In the subgroup of eight HS, time-dependent changes of fecal enzyme output occurred with a decrease of E1 concentrations and an increase of ChT activity from the second up to eighth or ninth day of the experiment. CONCLUSION: Exogenous applied pancreatic enzymes, dose- and time-dependently inhibited endogenous pancreatic secretion. The obtained results strongly support the existence of a protease mediated feedback mechanism in humans.