Multitarget Antioxidant NO-Donor Organic Nitrates: A Novel Approach to Overcome Nitrates Tolerance, an Ex Vivo Study

Chronic use of glyceryl trinitrate (GTN) is limited by serious side effects, such as tolerance and endothelial dysfunction of coronary and resistance arteries. Although GTN is used as a drug since more than 130 years, the mechanisms of the vasodilatory effects and of tolerance development to organic nitrates are still incompletely elucidated. New synthesized organic nitrates with and without antioxidant properties were characterized for their ex vivo tolerance profile, in order to investigate the oxidative stress hypothesis of nitrate tolerance. The organic nitrates studied showed different vasodilation and tolerance profiles, probably due to the ability or inability of the compounds to interact with the aldehyde dehydrogenase-2 enzyme (ALDH-2) involved in bioactivation. Furthermore, nitrooxy derivatives endowed with antioxidant properties did not determine the onset of tolerance, even if bioactivated by ALDH-2. The results of this study could be further evidence of the involvement of ALDH-2 in the development of nitrate tolerance. Moreover, the behavior of organic nitrates with antioxidant properties supports the hypothesis of the involvement of ROS in inactivating ALDH-2.

Comparison of the Agatston score acquired with photon-counting detector CT and energy-integrating detector CT: ex vivo study of cadaveric hearts

The purpose of this study was to compare the correlation and agreement between AS derived from either an energy-integrating detector CT (EID-CT) or a photon-counting detector CT (PCD-CT). Reproducibility was also compared. In total, 26 calcified coronary lesions (from five cadaveric hearts) were identified for inclusion. The hearts were positioned in a chest phantom and scanned in both an EID-CT and a prototype PCD-CT. The EID-CT and PCD-CT acquisition and reconstruction parameters were matched. To evaluate the reproducibility, the phantom was manually repositioned, and an additional scan was performed using both methods. The EID-CT reconstructions were performed using the dedicated calcium score kernel Sa36. The PCD-CT reconstructions were performed with a vendor-recommended kernel (Qr36). Several monoenergetic energy levels (50–150 keV) were evaluated to find the closest match with the EID-CT scans. A semi-automatic evaluation of calcium score was performed on a post-processing multimodality workplace. The best match with Sa36 was PCD-CT Qr36 images, at a monoenergetic level of 72 keV. Statistical analyses showed excellent correlation and agreement. The correlation and agreement with regards to the Agatston score (AS) between the two methods, for each position as well as between the two positions for each method, were assessed with the Spearman´s rank correlation. The correlation coefficient, rho, was 0.98 and 0.97 respectively 0.99 and 0.98. The corresponding agreements were investigated by means of Bland–Altman plots. High correlation and agreement was observed between the AS derived from the EID-CT and a PCD-CT. Both methods also demonstrated excellent reproducibility.

Effect of Different Instrumentation and Irrigation Methods on Apical Microbial Extrusion: An Ex Vivo Study

Background: Periapical extrusion of debris, irrigating solution and microorganism are the major contributing factors for flare-ups during root canal therapy. The aim of this ex vivo study was to evaluate the effect of different types of instrumentation in combination with different irrigation methods on apical bacterial expulsion. Material and Methods: Three hundred and ten extracted human permanent teeth were infected with Enterococcus faecalis. After incubation at 37°C for 24 h, three hundred teeth were instrumented with three different instrumentations using two irrigation methods. The remaining ten teeth were used as negative and positive control groups, in which no inoculation was done and no instrumentation was carried out respectively. Three hundred teeth were equally divided in three groups (n = 100), in which instrumentation was performed using a protaper universal rotary file (group 1), WaveOne reciprocating file (group 2) and a flexiCON rotary file (group 3). In each group, 50 samples were irrigated with conventional needle irrigation, and 50 samples were irrigated with the endoVac irrigation method. During instrumentation, apically extruded bacteria were collected in an Eppendorf tube. Microbiological samples were taken from the Eppendorf tube and incubated for 24h, and colony-forming units were counted. The data collected were statistically analysed. Results: The group 2 showed highest bacterial extrusion using conventional irrigation while group 3 showed lowest using endovac irrigation system. Conclusion: FlexiCON rotary instrumentation with the endoVac irrigation system produced significantly less bacterial extrusion than the other techniques.