Resazurin metabolism assay for root canal disinfectant evaluation on dual-species biofilms

Introduction

Endodontic infections are caused by polymicrobial biofilms. Therefore, novel root canal disinfectants should be evaluated not only on single-species biofilms but also on dual- or mixed-species biofilms. A simple, high-throughput assay is urgently needed for this. In this study, the application of the resazurin metabolism assay was investigated for the evaluation of a root canal disinfectant on dual-species biofilms.

Methods

Enterococcus faecalis with or without Streptococcus mutans in biofilms were formed in an active attachment biofilm model for 24 hours. Subsequently, the biofilms were treated with various concentrations of NaOCl for 1 minute. After resazurin metabolism by both organisms was confirmed, treatment efficacies using 0.0016% resazurin were evaluated.

Results

During NaOCl treatments, resazurin metabolism displays a clear dose response, not only in single-species E. faecalis (or S. mutans) biofilms but also in dual-species biofilms. Notably, the assay revealed that the resistance of dual-species biofilms to NaOCl was 30-fold higher than in single-species E. faecalis biofilms. Viability counts on a selected NaOCl treatment (0.004%) confirmed this result and showed the increased resistance of E. faecalis in dual-species biofilms.

Conclusions

Clearly, the high-throughput and low cost resazurin metabolism assay has a great potential for testing novel root canal antimicrobial agents in mixed-species biofilms.     

Evaluation of a Fixed,Weight-Based Dose of 3-Factor Prothrombin Complex Concentrate Without Adjunctive Plasma Following Warfarin-Associated Intracranial Hemorrhage

Introduction

Data regarding use of prothrombin complex concentrate (PCC) for international normalization ratio (INR) reversal in warfarin-associated intracranial hemorrhage (wICH) is variable with regards to dosages, adjunctive agents, and product choice. In 2012, we implemented a fixed, weight-based [30 IU/kg] dosing protocol of 3-factor PCC (3PCC) utilizing a rapid infusion rate and no requirement for fresh frozen plasma (FFP) following factor product administration. We aimed to evaluate the impact of this protocol on immediate and delayed INR reversal in patients admitted with wICH in the absence of FFP co-administration.

Methods

We conducted a retrospective review of patients receiving 3PCC following wICH between January 1, 2012 and December 10, 2013. The primary objective was to determine the percentage of patients achieving goal INR (≤1.4) following 3PCC administration. Patients were excluded if their bleed was not intracranial in origin, received a dose outside of the specified protocol, or were given FFP as an adjunctive agent.

Results

We included 35 patients with a mean presenting INR of 3.2 ± 1.3. Thirty patients (85.7 %) achieved goal INR (≤1.4) following one dose of 3PCC. The mean INR after infusion of 3PCC was 1.3 ± 0.2. The median duration between 3PCC infusion and subsequent INR was 48.0 min (30–70.1 min). Vitamin K was utilized in 33 (94.3 %) patients. No patient experienced a thromboembolic event within 7 days of 3PCC administration.

Conclusions

Fixed, weight-based dosing of 3PCC without adjunctive FFP resulted in high rates of complete INR reversal without significant adverse events.     

Long-Term Lithium Treatment Reduces Glucose Metabolism in the Cerebellum and Hippocampus of Nondemented Older Adults: An [18F]FDG-PET Study

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Temperature Control of Hypertensive Rats during Moderate Exercise in Warm Environment

The control of body temperature in Spontaneously Hypertensive Rat (SHR) subjected to exercise in warm environment was investigated. Male SHR and Wistar rats were submitted to moderate exercise in temperate (25°C) and warm (32°C) environments while body and tail skin temperatures, as well as oxygen consumption, were registered. Total time of exercise, workload performed, mechanical efficiency and heat storage were determined. SHR had increased heat production and body temperature at the end of exercise, reduced mechanical efficiency and increased heat storage (p < 0.05). Furthermore, these rats also showed a more intense and faster increase in body temperature during moderate exercise in the warm environment (p < 0.05). The lower mechanical efficiency seen in SHR was closely correlated with their higher body temperature at the point of fatigue in warm environment (p < 0.05). Our results indicate that SHR exhibit significant differences in body temperature control during moderate exercise in warm environment characterized by increased heat production and heat storage during moderate exercise in warm environment. The combination of these responses result in aggravated hyperthermia linked with lower mechanical efficiency.

Key Points

• The practice of physical exercise in warm environment has gained importance in recent decades mainly because of the progressive increases in environmental temperature;
• To the best of our knowledge, these is the first study to analyze body temperature control of SHR during moderate exercise in warm environment;
• SHR showed increased heat production and heat storage that resulted in higher body temperature at the end of exercise;
• SHR showed reduced mechanical efficiency;
• These results demonstrate that when exercising in a warm environment the hypertensive rat exhibit differences in temperature control.

Key words: Thermoregulation, physical exercise, hypertension, heat stress, exercise performance     

Topical 5‐azacytidine accelerates skin wound healing in rats

The development of new methods to improve skin wound healing may affect the outcomes of a number of medical conditions. Here, we evaluate the molecular and clinical effects of topical 5‐azacytidine on wound healing in rats. 5‐Azacytidine decreases the expression of follistatin‐1, which negatively regulates activins. Activins, in turn, promote cell growth in different tissues, including the skin. Eight‐week‐old male Wistar rats were submitted to 8.0‐mm punch‐wounding in the dorsal region. After 3 days, rats were randomly assigned to receive either a control treatment or the topical application of a solution containing 5‐azacytidine (10 mM) once per day. Photo documentation and sample collection were performed on days 5, 9, and 15. Overall, 5‐azacytidine promoted a significant acceleration of complete wound healing (99.7% ± 0.7.0 vs. 71.2% ± 2.8 on day 15; n = 10; p < 0.01), accompanied by up to threefold reduction in follistatin expression. Histological examination of the skin revealed efficient reepithelization and cell proliferation, as evaluated by the BrdU incorporation method. 5‐Azacytidine treatment also resulted in increased gene expression of transforming growth factor‐beta and the keratinocyte markers involucrin and cytokeratin, as well as decreased expression of cytokines such as tumor necrosis factor‐alpha and interleukin‐10. Lastly, when recombinant follistatin was applied to the skin in parallel with topical 5‐azacytidine, most of the beneficial effects of the drug were lost. Thus, 5‐azacytidine acts, at least in part through the follistatin/activin pathway, to improve skin wound healing in rodents.     

The epidural approach to the Meckel’s cave: a how I do it

Background

Meckel’s cave (MC) is a meningeal cleft lying in the middle fossa laterally to the cavernous sinus. Tumours that develop inside the MC may require a surgical resection. The authors describe the surgical technique of the intracranial epidural approach to the MC.

Methods

Based upon anatomical dissection showing the relevant surgical anatomy, and illustrated by the video of an operated case, the authors detail the surgical procedure. The key point is to shave the floor of the middle fossa and skeletonize the superior orbital fissure, rotundum and ovale foramen in order to delineate the plane of dural elevation and expose the lateral wall of the MC. The rules of exposure and resection of the tumour are then shown. Variations and limitations of the approach are discussed.

Conclusion

Conducted in a stepwise manner and following relevant landmarks, the epidural anterolateral approach offers a safe and reliable exposure to the diseases that develop within the MC.     

Comparison of long-term outcomes between open and laparoscopic Thal fundoplication in children

Objectives

In recent years laparoscopic fundoplication is increasingly performed in pediatric surgery. The aim of this study was to compare the long-term outcomes between open and laparoscopic Thal fundoplication in children.

Methods

This retrospective study includes children who underwent a Thal fundoplication between 3/1997 and 7/2009. The minimum follow-up time to enter the study was 2 years; the overall median follow-up was 77 months (range, 29–176 months).

Results

A total of 101 patients were included, of which 47 underwent an open and 54 a laparoscopic Thal. Intraoperative problems, early postoperative complications, time to establish enteral feeds and length of stay did not differ among both groups. The mean duration of surgery was significantly less in the open group (OPG) (108.0 (± 7.72) versus 144.1 (± 6.36) minutes; p = 0.001) and this was mainly attributed to patients with neurological problems. Severe dysphagia requiring endoscopy was observed in 10 patients, but this did not differ significantly between groups (n = 2 in the OPG vs. n = 8 in the laparoscopic group (LAPG); p = 0.10). Overall 12 patients (11.9%) (6 in each group) required a redo-fundoplication after a median of 18.7 months (range, 6–36 months). In the whole study group, 80 patients (79.2%) were classified as having surgical results being excellent, good or satisfactory and this did not differ significantly between groups.

Conclusions

In the long-term open and laparoscopic Thal fundoplication have similarly good outcomes. The laparoscopic approach can be considered as an alternative, however there is not a clear superiority compared with the open counterpart.