Sympathetic innervation is essential for metabolic homeostasis and pancreatic beta cell function in adult rats.

Obesity is associated with an imbalance in the activity of the autonomic nervous system (ANS), specifically in the organs involved in energy metabolism. The pancreatic islets are richly innervated by the ANS, which tunes the insulin release due to changes in energy demand. Therefore, changes in the sympathetic input that reach the pancreas can lead to metabolic dysfunctions. To evaluate the role of the sympathetic ends that innervate the pancreas, 60-day-old male Wistar rats were subjected to sympathectomy (SYM) or were sham-operated (SO). At 120 day-old SYM rats exhibited an increase in body weight, fat pads and metabolic dysfunctions. Decreases in the HOMA-IR and reductions in insulin release were observed both in vivo and in vitro. Furthermore, the SYM rats exhibited altered pancreatic islet function in both muscarinic and adrenergic assays and exhibited high protein expression of the alpha-2 adrenergic receptor (α2AR). Because α2AR has been linked to type 2 diabetes, these findings demonstrate the clinical implications of this study.

Proteomics-based identification of differentially abundant proteins reveals adaptation mechanisms of Xanthomonas citri subsp. citri during Citrus sinensis infection.

BACKGROUND: Xanthomonas citri subsp. citri (Xac) is the causal agent of citrus canker. A proteomic analysis under in planta infectious and non-infectious conditions was conducted in order to increase our knowledge about the adaptive process of Xac during infection. RESULTS: For that, a 2D-based proteomic analysis of Xac at 1, 3 and 5 days after inoculation, in comparison to Xac growth in NB media was carried out and followed by MALDI-TOF-TOF identification of 124 unique differentially abundant proteins. Among them, 79 correspond to up-regulated proteins in at least one of the three stages of infection. Our results indicate an important role of proteins related to biofilm synthesis, lipopolysaccharides biosynthesis, and iron uptake and metabolism as possible modulators of plant innate immunity, and revealed an intricate network of proteins involved in reactive oxygen species adaptation during Plants` Oxidative Burst response. We also identified proteins previously unknown to be involved in Xac-Citrus interaction, including the hypothetical protein XAC3981. A mutant strain for this gene has proved to be non-pathogenic in respect to classical symptoms of citrus canker induced in compatible plants. CONCLUSIONS: This is the first time that a protein repertoire is shown to be active and working in an integrated manner during the infection process in a compatible host, pointing to an elaborate mechanism for adaptation of Xac once inside the plant.

Glibenclamide treatment blocks metabolic dysfunctions and improves vagal activity in monosodium glutamate-obese male rats.

BACKGROUND/AIMS: Autonomic nervous system imbalance is associated with metabolic diseases, including diabetes. Glibenclamide is an antidiabetic drug that acts by stimulating insulin secretion from pancreatic beta cells and is widely used in the treatment of type 2 diabetes. Since there is scarce data concerning autonomic nervous system activity and diabetes, the aim of this work was to test whether glibenclamide can improve autonomic nervous system activity and muscarinic acetylcholine receptor function in pre-diabetic obese male rats. METHODS: Pre-diabetes was induced by treatment with monosodium L-glutamate in neonatal rats. The monosodium L-glutamate group was treated with glibenclamide (2 mg/kg body weight /day) from weaning to 100 days of age, and the control group was treated with water. Body weight, food intake, Lee index, fasting glucose, insulin levels, homeostasis model assessment of insulin resistance, omeostasis model assessment of ß-cell function, and fat tissue accumulation were measured. The vagus and sympathetic nerve electrical activity were recorded. Insulin secretion was measured in isolated islets challenged with glucose, acetylcholine, and the selective muscarinic acetylcholine receptor antagonists by radioimmunoassay technique. RESULTS: Glibenclamide treatment prevented the onset of obesity and diminished the retroperitoneal (18%) and epididymal (25%) fat pad tissues. In addition, the glibenclamide treatment also reduced the parasympathetic activity by 28% and glycemia by 20% in monosodium L-glutamate-treated rats. The insulinotropic effect and unaltered cholinergic actions in islets from monosodium L-glutamate groups were increased. CONCLUSION: Early glibenclamide treatment prevents monosodium L-glutamate-induced obesity onset by balancing autonomic nervous system activity.

HPA axis and vagus nervous function are involved in impaired insulin secretion of MSG-obese rats.

Neuroendocrine dysfunctions such as the hyperactivity of the vagus nerve and hypothalamus-pituitary-adrenal (HPA) axis greatly contribute to obesity and hyperinsulinemia; however, little is known about these dysfunctions in the pancreatic ß-cells of obese individuals. We used a hypothalamic-obesity model obtained by neonatal treatment with monosodium l-glutamate (MSG) to induce obesity. To assess the role of the HPA axis and vagal tonus in the genesis of hypercorticosteronemia and hyperinsulinemia in an adult MSG-obese rat model, bilateral adrenalectomy (ADX) and subdiaphragmatic vagotomy (VAG) alone or combined surgeries (ADX-VAG) were performed. To study glucose-induced insulin secretion (GIIS) and the cholinergic insulinotropic process, pancreatic islets were incubated with different glucose concentrations with or without oxotremorine-M, a selective agonist of the M3 muscarinic acetylcholine receptor (M3AChR) subtype. Protein expression of M3AChR in pancreatic islets, corticosteronemia, and vagus nerve activity was also evaluated. Surgeries reduced 80% of the body weight gain. Fasting glucose and insulin were reduced both by ADX and ADX-VAG, whereas VAG was only associated with hyperglycemia. The serum insulin post-glucose stimulation was lower in all animals that underwent an operation. Vagal activity was decreased by 50% in ADX rats. In the highest glucose concentration, both surgeries reduced GIIS by 50%, whereas ADX-VAG decreased by 70%. Additionally, M3AChR activity was recovered by the individual surgeries. M3AChR protein expression was reduced by ADX. Both the adrenal gland and vagus nerve contribute to the hyperinsulinemia in the MSG model, although adrenal is more crucial as it appears to modulate parasympathetic activity and M3AChR expression in obesity.

Unravelling potential virulence factor candidates in Xanthomonas citri. subsp. citri by secretome analysis.

Citrus canker is a major disease affecting citrus production in Brazil. It's mainly caused by Xanthomonas citri subsp. citri strain 306 pathotype A (Xac). We analysed the differential expression of proteins secreted by wild type Xac and an asymptomatic mutant for hrpB4 (ΔhrpB4) grown in Nutrient Broth (NB) and a medium mimicking growth conditions in the plant (XAM1). This allowed the identification of 55 secreted proteins, of which 37 were secreted by both strains when cultured in XAM1. In this secreted protein repertoire, the following stand out: Virk, Polyphosphate-selective porin, Cellulase, Endoglucanase, Histone-like protein, Ribosomal proteins, five hypothetical proteins expressed only in the wild type strain, Lytic murein transglycosylase, Lipoprotein, Leucyl-tRNA synthetase, Co-chaperonin, Toluene tolerance, C-type cytochrome biogenesis membrane protein, Aminopeptidase and two hypothetical proteins expressed only in the ΔhrpB4 mutant. Furthermore, Peptidoglycan-associated outer membrane protein, Regulator of pathogenicity factor, Outer membrane proteins, Endopolygalacturonase, Chorismate mutase, Peptidyl-prolyl cis-trans isomerase and seven hypothetical proteins were detected in both strains, suggesting that there was no relationship with the secretion mediated by the type III secretory system, which is not functional in the mutant strain. Also worth mentioning is the Elongation factor Tu (EF-Tu), expressed only the wild type strain, and Type IV pilus assembly protein, Flagellin (FliC) and Flagellar hook-associated protein, identified in the wild-type strain secretome when grown only in NB. Noteworthy, that FliC, EF-Tu are classically characterized as PAMPs (Pathogen-associated molecular patterns), responsible for a PAMP-triggered immunity response. Therefore, our results highlight proteins potentially involved with the virulence. Overall, we conclude that the use of secretome data is a valuable approach that may bring more knowledge of the biology of this important plant pathogen, which ultimately can lead to the establishment of new strategies to combat citrus canker.

Early treatment with metformin induces resistance against tumor growth in adult rats.

It is known that antidiabetic drug metformin, which is used worldwide, has anti-cancer effects and can be used to prevent cancer growth. We tested the hypothesis that tumor cell growth can be inhibited by early treatment with metformin. For this purpose, adult rats chronically treated with metformin in adolescence or in adulthood were inoculated with Walker 256 carcinoma cells. Adult rats that were treated with metformin during adolescence presented inhibition of tumor growth, and animals that were treated during adult life did not demonstrate any changes in tumor growth. Although we do not have data to disclose a molecular mechanism to the preventive metformin effect, we present, for the first time, results showing that cancer growth in adult life is dependent on early life intervention, thus supporting a new therapeutic prevention for cancer.

Vagus nerve contributes to metabolic syndrome in high-fat diet-fed young and adult rats.

NEW FINDINGS: What is the central question of this study? Different nerve contributes periods of life are known for their differential sensitivity to interventions, and increased parasympathetic activity affects the development and maintenance of obesity. Thus, we evaluated the involvement of the vagus nerve by performing a vagotomy in young or adult rats that were offered an obesogenic high-fat diet. What is the main finding and its importance? Although the accumulation of adipose tissue decreased in both younger and older groups, the younger rats showed a greater response to the effects of vagotomy in general. In addition to the important role of the parasympathetic activity, we suggest that the vagus nerve contributes to the condition of obesity. Obesity has become a global problem, and this condition develops primarily because of an imbalance between energy intake and expenditure. The high complexity involved in the regulation of energy metabolism results from several factors besides endocrine factors. It has been suggested that obesity could be caused by an imbalance in the autonomous nervous system, which could lead to a condition of high parasympathetic activity in counterpart to low sympathetic tonus. High-fat (HF) diets have been used to induce obesity in experimental animals, and their use in animals leads to insulin resistance, hyperinsulinaemia and high parasympathetic activity, among other disorders. The aim of this work was to evaluate the effects of a vagotomy performed at the initiation of a HF diet at two different stages of life, weaning and adulthood. The vagotomy reduced parasympathetic activity (-32 and -51% in normal fat-fed rats and -43 and -55% in HF diet-fed rats; P < 0.05) and fat depots (-17 and -33%, only in HF diet-fed rats; P < 0.05). High-fat diet-fed rats exhibited fasting hyperinsulinaemia (fivefold higher in young rats and threefold higher in older rats; P < 0.05); however, vagotomy corrected it in younger rats only, and a similar effect was also observed during the glucose tolerance test. The insulin resistance exhibited by the HF diet-fed groups was not altered in the vagotomized rats. We suggest that the vagus nerve, in addition to the important role of parasympathetic activity, contributes to the condition of obesity, and that non-vagal pathways may be involved along with the imbalanced autonomic nervous system.

Insulin oversecretion in MSG-obese rats is related to alterations in cholinergic muscarinic receptor subtypes in pancreatic islets.

BACKGROUND/AIMS: Impaired pancreatic beta cell function and insulin secretion/action are a link between obesity and type 2 diabetes, which are worldwide public health burdens. We aimed to characterize the muscarinic acetylcholine receptor (mAChR) M1-M4 subtypes in isolated pancreatic islets from pre-diabetic obese rats that had been treated neonatally with monosodium L-glutamate (MSG). METHODS: At 90 days of age, both the MSG and the control groups underwent biometric and biochemical evaluation. Anti-muscarinic drugs were used to study mAChR function either in vivo or in vitro. RESULTS: The results demonstrated that atropine treatment reduced insulin secretion in the MSG-treated and control groups, whereas treatment with an M2mAChR-selective antagonist increased secretion. Moreover, the insulinostatic effect of an M3mAChR-selective antagonist was significantly higher in the MSG-treated group. M1mAChR and M3mAChR expression was increased in the MSG-obese group by 55% and 73%, respectively. In contrast, M2mAChR expression decreased by 25% in the MSG group, whereas M4mAChR expression was unchanged. CONCLUSIONS: Functional changes in and altered content of the mAChR (M1-M4) subtypes are pivotal to the demand for high pancreatic beta cell insulin secretion in MSG-obese rats, which is directly associated with vagal hyperactivity and peripheral insulin resistance.

Comparative proteomic analysis reveals that T3SS, Tfp, and xanthan gum are key factors in initial stages of Citrus sinensis infection by Xanthomonas citri subsp. citri.

The bacteria Xanthomonas citri subsp. citri (Xac) is the causal agent of citrus canker. The disease symptoms are characterized by localized host cell hyperplasia followed by tissue necrosis at the infected area. An arsenal of bacterial pathogenicity- and virulence-related proteins is expressed to ensure a successful infection process. At the post-genomic stage of Xac, we used a proteomic approach to analyze the proteins that are displayed differentially over time when the pathogen attacks the host plant. Protein extracts were prepared from infectious Xac grown in inducing medium (XAM1) for 24 h or from host citrus plants for 3 or 5 days after infection, detached times to evaluate the adaptation and virulence of the pathogen. The protein extracts were proteolyzed, and the peptides derived from tryptic digestion were investigated using liquid chromatography and tandem mass spectrometry. Changes in the protein expression profile were compared with the Xac genome and the proteome recently described under non-infectious conditions. An analysis of the proteome of Xac under infectious conditions revealed proteins directly involved in virulence such as the type III secretion system (T3SS) and effector proteins (T3SS-e), the type IV pilus (Tfp), and xanthan gum biosynthesis. Moreover, four new mutants related to proteins detected in the proteome and with different functions exhibited reduced virulence relative to the wild-type proteins. The results of the proteome analysis of infectious Xac define the processes of adaptation to the host and demonstrate the induction of the virulence factors of Xac involved in plant-pathogen interactions.

Maternal diet, bioactive molecules, and exercising as reprogramming tools of metabolic programming.

Nutrition and lifestyle, particularly over-nutrition and lack of exercise, promote the progression and pathogenesis of obesity and metabolic diseases. Nutrition is likely the most important environmental factor that modulates the expression of genes involved in metabolic pathways and a variety of phenotypes associated with obesity and diabetes. During pregnancy, diet is a major factor that influences the organ developmental plasticity of the foetus. Experimental evidence shows that nutritional factors, including energy, fatty acids, protein, micronutrients, and folate, affect various aspects of metabolic programming. Different epigenetic mechanisms that are elicited by bioactive factors in early critical developmental ages affect the susceptibility to several diseases in adulthood. The beneficial effects promoted by exercise training are well recognised, and physical exercise may be considered one of the more prominent non-pharmacological tools that can be used to attenuate metabolic programming and to consequently ameliorate the illness provoked by metabolic diseases and reduce the prevalence of obesity, type 2 diabetes, and cardiovascular diseases. Literature on the different outcomes of unbalanced diets and the beneficial effects of some bioactive molecules during gestation and lactation on the metabolic health of offspring, as well as the potential mechanisms underlying these effects, was reviewed. The importance of the combined effects of functional nutrition and exercise as reprogramming tools of metabolic programming is discussed in depth. Finally, this review provides recommendations to healthcare providers that may aid in the control of early programming in an attempt to optimise the health of the mother and child.

Ability of chemomechanical preparation with either rotary instruments or self-adjusting file to disinfect oval-shaped root canals.

INTRODUCTION: Oval-shaped root canals might represent a great challenge for proper disinfection. This study compared the capability of a newly developed instrument, the self-adjusting file (SAF), and rotary nickel-titanium (NiTi) instrumentation to eliminate Enterococcus faecalis populations from long oval root canals of extracted human teeth. As a secondary purpose, the ability of a modification in sampling technique to recover bacteria lodged in recesses of oval canals was evaluated. METHODS: Long oval canals from mandibular incisors and maxillary second premolars were infected with E. faecalis (ATCC 29212) for 30 days and then randomly distributed into 2 experimental groups. In group 1, canals were prepared up to a 40/04 rotary BioRaCe instrument by using irrigation with NaviTip needles; in group 2, canals were prepared by using the SAF system with continuous irrigation. NaOCl and ethylenediaminetetraacetic acid were used as irrigants. Bacteriologic samples were taken before (S1) and after preparation (S2a and S2b). RESULTS: Reduction in the bacterial populations was highly significant in both groups (P < .001). Preparation of long oval canals with the SAF was significantly more effective than rotary NiTi instrumentation in reducing intracanal E. faecalis counts (P = .01). Frequency of positive cultures in S2 samples was 11 of 20 (55%) for rotary instrumentation and 4 of 20 (20%) for SAF instrumentation (P = .048). S2b samples (modified method) yielded more positive samples than S2a (12/40 vs 5/40), but this difference reached no statistical significance (P > .05). CONCLUSIONS: The SAF system was significantly more effective than rotary NiTi instrumentation used with syringe/needle irrigation in disinfecting long oval root canals in vitro. A modified sampling technique might be necessary for oval canals.

Effects of electropolishing surface treatment on the cyclic fatigue resistance of BioRace nickel-titanium rotary instruments.

INTRODUCTION: This study evaluated the influence of electropolishing surface treatment on the number of cycles to fracture of BioRace rotary nickel-titanium endodontic instruments. METHODS: BioRace size BR5C instruments with or without electropolishing surface treatment were used in an artificial curved canal under rotational speed of 300 rpm until fracture. Fractured surfaces and the helical shafts of fractured instruments were analyzed by scanning electron microscopy (SEM). RESULTS: Polished instruments displayed a significantly higher number of cycles to fracture when compared with nonpolished instruments (P < .001). Actually, the number of cycles to fracture of a polished BR5C instrument was 124% higher than that of a nonpolished instrument. SEM analysis showed that the fractured surface of both polished and nonpolished BR5C instruments had ductile morphologic characteristics. Evaluation of the separated fragments after cyclic fatigue testing showed the presence of microcracks near the fracture surface. Polished instruments exhibited fine cracks that assumed an irregular path (zigzag crack pattern), whereas nonpolished instruments showed cracks running along the machining grooves. CONCLUSIONS: Electropolishing surface treatment of BioRace endodontic instruments significantly increased the cyclic fatigue resistance.

Cyclic fatigue resistance of ProTaper Universal instruments when subjected to static and dynamic tests.

OBJECTIVE: This study evaluated the number of cycles to fracture of ProTaper Universal S2 instruments when subjected to static and dynamic cyclic fatigue tests. STUDY DESIGN: ProTaper Universal S2 instruments were used until fracture in an artificial curved canal under rotational speed of 300 rpm in either a static or a dynamic test model. Afterward, the length of the fractured segments was measured and fractured surfaces and helical shafts analyzed by scanning electron microscopy (SEM). RESULTS: The number of cycles to fracture was significantly increased when instruments were tested in the dynamic model (P<.001). Instrument separation occurred at the point of maximum flexure within the artificial canals, i.e., the midpoint of the curved canal segment. SEM analysis revealed that fractured surfaces exhibited characteristics of the ductile mode. Plastic deformation was not observed in the helical shaft of fractured instruments. CONCLUSIONS: The number of cycles to fracture ProTaper Universal S2 instruments significantly increased with the use of instruments in a dynamic cyclic fatigue test compared with a static model. These findings reinforce the need for performing continuous pecking motions during rotary instrumentation of curved root canals.

Novel insights into the genomic basis of citrus canker based on the genome sequences of two strains of Xanthomonas fuscans subsp. aurantifolii.

BACKGROUND: Citrus canker is a disease that has severe economic impact on the citrus industry worldwide. There are three types of canker, called A, B, and C. The three types have different phenotypes and affect different citrus species. The causative agent for type A is Xanthomonas citri subsp. citri, whose genome sequence was made available in 2002. Xanthomonas fuscans subsp. aurantifolii strain B causes canker B and Xanthomonas fuscans subsp. aurantifolii strain C causes canker C. RESULTS: We have sequenced the genomes of strains B and C to draft status. We have compared their genomic content to X. citri subsp. citri and to other Xanthomonas genomes, with special emphasis on type III secreted effector repertoires. In addition to pthA, already known to be present in all three citrus canker strains, two additional effector genes, xopE3 and xopAI, are also present in all three strains and are both located on the same putative genomic island. These two effector genes, along with one other effector-like gene in the same region, are thus good candidates for being pathogenicity factors on citrus. Numerous gene content differences also exist between the three cankers strains, which can be correlated with their different virulence and host range. Particular attention was placed on the analysis of genes involved in biofilm formation and quorum sensing, type IV secretion, flagellum synthesis and motility, lipopolysacharide synthesis, and on the gene xacPNP, which codes for a natriuretic protein. CONCLUSION: We have uncovered numerous commonalities and differences in gene content between the genomes of the pathogenic agents causing citrus canker A, B, and C and other Xanthomonas genomes. Molecular genetics can now be employed to determine the role of these genes in plant-microbe interactions. The gained knowledge will be instrumental for improving citrus canker control.

Photodynamic therapy with two different photosensitizers as a supplement to instrumentation/irrigation procedures in promoting intracanal reduction of Enterococcus faecalis.

INTRODUCTION: This in vitro study aimed to investigate the antibacterial effects of photodynamic therapy (PDT) with methylene blue (MB) or toluidine blue (TB) (both at 15 microg/mL) as a supplement to instrumentation/irrigation of root canals experimentally contaminated with Enterococcus faecalis. METHODS: Seventy extracted teeth had their root canals contaminated with an endodontic strain of E. faecalis for 7 days, instrumented with nickel-titanium instruments and irrigated either with 2.5% NaOCl or with 0.85% NaCl, and then randomly distributed into four experimental groups: MB/NaOCl (PDT with MB and NaOCl as the irrigant), TB/NaOCl (PDT with TB and NaOCl as the irrigant), MB/NaCl (PDT with MB and NaCl as the irrigant), and TB/NaCl (PDT with TB and NaCl as the irrigant). For PDT, the photosensitizer remained in the canal for 2 minutes before exposed to red light emitted from a diode laser for 4 minutes. Samples were taken before and after instrumentation/irrigation and following the specific PDT procedure for each group, plated onto Mitis-salivarius agar and the colony forming units counted. RESULTS: Regardless of the irrigant used (NaOCl or NaCl), instrumentation significantly reduced bacterial counts in comparison to the baseline (p < 0.001). NaOCl as the irrigant was significantly more effective than NaCl, and this difference persisted after PDT, irrespective of the photosensitizer used (p < 0.05). PDT with either MB or TB did not significantly enhance disinfection after chemomechanical preparation using NaOCl as irrigant (p > 0.05). No significant differences were observed between the two photosensitizers (p > 0.05). CONCLUSION: These in vitro results suggest that PDT with either MB or TB may not exert a significant supplemental effect to instrumentation/irrigation procedures with regard to intracanal disinfection. Further adjustments in the PDT protocol may be required to enhance predictability in bacterial elimination before clinical use is recommended.

Distribution and biological role of the oligopeptide-binding protein (OppA) in Xanthomonas species.

In this study we investigated the prevalence of the oppA gene, encoding the oligopeptide binding protein (OppA) of the major bacterial oligopeptide uptake system (Opp), in different species of the genus Xanthomonas. The oppA gene was detected in two Xanthomonas axonopodis strains among eight tested Xanthomonas species. The generation of an isogenic oppA-knockout derivative of the Xac 306 strain, showed that the OppA protein neither plays a relevant role in oligopeptide uptake nor contributes to the infectivity and multiplication of the bacterial strain in leaves of sweet orange (Citrus sinensis) and Rangpur lime (Citrus limonia). Taken together these results suggest that the oppA gene has a recent evolutionary history in the genus and does not contribute in the physiology or pathogenesis of X. axonopodis.

Outpatient vs. home-based pulmonary rehabilitation in COPD: a randomized controlled trial.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is a common cause of morbidity and mortality affecting a large number of individuals in both developed and developing countries and it represents a significant financial burden for patients, families and society. Pulmonary rehabilitation (PR) is a multidisciplinary program that integrates components of exercise training, education, nutritional support, psychological support and self-care, resulting in an improvement in dyspnea, fatigue and quality of life. Despite its proven effectiveness and the strong scientific recommendations for its routine use in the care of COPD, PR is generally underutilized and strategies for increasing access to PR are needed. Home-based self-monitored pulmonary rehabilitation is an alternative to outpatient rehabilitation. In the present study, patients with mild, moderate and severe COPD submitted to either an outpatient or at-home PR program for 12 weeks were analyzed. METHODS: Patients who fulfilled the inclusion criteria were randomized into three distinct groups: an outpatient group who performed all activities at the clinic, a home-based group who performed the activities at home and a control group. PR consisted of a combination of aerobic exercises and strengthening of upper and lower limbs 3 times a week for 12 weeks. RESULTS: There was a significant difference in the distance covered on the six-minute walk test (p < 0.05) and BODE index (p < 0.001) in the outpatient and at-home groups after participating in the rehabilitation program compared to baseline. CONCLUSION: A home-based self-monitoring pulmonary rehabilitation program is as effective as outpatient pulmonary rehabilitation and is a valid alternative for the management of patients with COPD.

Comparison of the effectiveness of three irrigation techniques in reducing intracanal Enterococcus faecalis populations: an in vitro study.

INTRODUCTION: Several irrigation techniques have been recently introduced with the main objective of improving root canal disinfection. This in vitro study aimed at comparing the intracanal bacterial reduction promoted by chemomechanical preparation with 3 different irrigation techniques. METHODS: Root canals from extracted teeth were contaminated with Enterococcus faecalis ATCC 29212 for 7 days and then randomly distributed into 3 experimental groups of 20 teeth each: group 1, conventional irrigation with NaviTip needles inserted up to 3 mm short of the working length; group 2, same as group 1, but supplemented with final irrigant activation by the EndoActivator system; and group 3, irrigation with the EndoVac system. NaOCl and ethylenediaminetetraacetic acid (EDTA) were the irrigants used in all experimental groups. The overall preparation time was kept constant for the groups, but the total volume ranged from 20 mL (groups 1 and 2) to 43 mL (group 3). The control group was irrigated with saline solution (total volume, 43 mL). Samples taken before and after chemomechanical procedures were cultured, and the colony-forming units (CFUs) were counted. RESULTS: Reduction in the bacterial populations was highly significant for all groups. The 3 experimental groups with NaOCl and EDTA as irrigants were significantly more effective than the control group with saline in reducing CFU counts. There were no significant differences between the 3 techniques tested. CONCLUSIONS: There was no evident antibacterial superiority of any of the irrigation techniques evaluated in the present in vitro model.

Influence of rotational speed on the cyclic fatigue of rotary nickel-titanium endodontic instruments.

INTRODUCTION: During the preparation of curved canals, rotary nickel-titanium (NiTi) instruments are subjected to cyclic fatigue, which can lead to instrument fracture. Although several factors may influence the cyclic fatigue resistance of instruments, the role of the rotational speed remains uncertain. This study was intended to evaluate the effects of rotational speed on the number of cycles to fracture of rotary NiTi instruments. METHODS: ProTaper Universal instruments F3 and F4 (Maillefer SA, Ballaigues, Switzerland) were used in an artificial curved canal under rotational speeds of 300 rpm or 600 rpm. The artificial canal was made of stainless steel, with an inner diameter of 1.5 mm, total length of 20 mm, and arc at the end with a curvature radius of 6 mm. The arc length was 9.4 mm and 10.6 mm on the straight part. The number of cycles required to fracture was recorded. Fractured surfaces and the helical shafts of the fractured instruments were analyzed by scanning electron microscopy. RESULTS: The results showed approximately a 30% reduction in the observed number of cycles to fracture as rotational speed was increased from 300 to 600 RPM (p < 0.05). The morphology of the fractured surface was always of ductile type, and no plastic deformation was observed on the helical shaft of fractured instruments. CONCLUSIONS: The present findings for both F3 and F4 ProTaper instruments revealed that the increase in rotational speed significantly reduced the number of cycles to fracture.

Postoperative pain following the use of two different intracanal medications.

This study evaluated the incidence of postoperative pain after intracanal dressings with either 0.12% chlorhexidine digluconate gel (CHX) or a calcium hydroxide/camphorated paramonochlorophenol/glycerin paste (CH/CPMC). Overall, 138 asymptomatic teeth had their canals instrumented under irrigation with 2.5% NaOCl and then dressed with either CH/CPMC or CHX. The incidence of different intensity levels of postoperative pain was registered for the period between appointments. Data revealed that 84% of the total number of cases treated with either medicament showed absence of any level of pain. No case medicated with CH/CPMC and four cases (5.8%) medicated with CHX were categorized as flare-ups. There were no statistically significant differences between all possible comparisons involving the two medicaments in treatment/retreatment cases and teeth with/without apical periodontitis lesions. The low incidence of postoperative pain after the use of both medications, coupled to their antimicrobial effectiveness, gives support to using one or the other in routine treatment/retreatment.