Biochemical characterization and role of the proteasome in the oxidative stress response of adult Schistosoma mansoni worms

The trematode Schistosoma mansoni, an important parasite of humans, is the principle agent of the disease schistosomiasis. In the human host, one of the most important stress factors of this parasite is the oxidative stress generated by both the metabolism of the worm and the immune system of the host. The proteasomal system is responsible for protein homeostasis during oxidative stress. The 26S proteasome is a multicatalytic protease formed by two compartments, a 20S core and regulatory particle 19S, and controls the degradation of intracellular proteins, hence regulating many cellular processes. In the present report, we describe the biochemical characterization and role of the 20S proteasome in the response of adult S. mansoni worms exposed to hydrogen peroxide. Characterization of the response to the oxidative stress included the evaluation of viability, egg production, mortality, tegument integrity, and both expression and activity of proteasome. We observed decreases in viability, egg production as well as 100 % mortality at the higher concentrations of hydrogen peroxide tested. The main changes observed in the tegument of adult worms were peeling as well as the appearance of bubbles and a decrease of spines on the tubercles. Furthermore, there were increases in 26S activity to the same extent as 20S proteasome activity, although there was increase of 20S proteasome content, suggesting that degradation of protein oxidized in adult worms is due to the 20S proteasome. It was demonstrated that adult S. mansoni worms are sensitive to oxidative stress, and that a variety of processes in this parasite are altered under this condition. The work contributes to a better understanding of the mechanisms employed by S. mansoni to survive under oxidative stress.     

Undergraduate dentistry students’ perception of difficulties regarding endodontic treatment

The present study aimed to identify students’ perceptions of endodontic treatment at a Brazilian university through a survey, which analysed student profiles and their difficulties in 2016. One hundred and two students who had experienced endodontic, laboratory or clinical procedures answered a survey based on their experiences, regarding their perceptions, experience and self‐confidence levels. Results demonstrated that there was no significant difficulty among students regarding anaesthesia, rubber dam use, chamber access, working length determination, instrumentation, root filling and temporary restoration procedures during endodontic treatment. However, problems were observed regarding radiographic examination (mainly in separating root canals) and the choice of intracanal medication. The present study also raised a question regarding dental education: how can endodontic education be improved by addressing students' perceived difficulties? Evaluating the major student difficulties during root canal therapy can help the improvement of teaching strategies during preclinical and clinical teaching.     

Ciliary neurotrophic factor (CNTF) protects non-obese Swiss mice against type 2 diabetes by increasing beta cell mass and reducing insulin clearance

Aims/hypothesis  

Ciliary neurotrophic factor (CNTF) improves metabolic variables of obese animals with characteristics of type 2 diabetes, mainly by reducing insulin resistance. We evaluated whether CNTF was able to improve other metabolic variables in mouse models of type 2 diabetes, such as beta cell mass and insulin clearance, and whether CNTF has any effect on non-obese mice with characteristics of type 2 diabetes.     

Analysis of the effects of irradiation in osseointegrated dental implants

Objective: The purpose of the present study was to evaluate the influence of radiation in osseointegrated dental implants installed in tibiae of rats. Material and methods: Screw‐shaped implants (2.5 mm diameter by 3.5 mm length) were custom made from commercially pure titanium bars. Titanium implants were blasted and sterilized before implantation. Animals were divided into two groups of 12 animals each and the rats were not paired after the groups' formation. The experimental group (group 1) received external irradiation 4 weeks after surgery while in the control group (group 2) animals were kept free of radiation. The shear strength required to detach the implant from bone was measured by push‐out testing and osseointegration was histologically evaluated. Results: Results showed that the compressive strength of irradiated implants (33.49 MPa) was significantly lower than the compressive strength of non‐irradiated implants (48.05 MPa). Conclusions: We concluded that the mechanical strength bonding between implants and host tissues decreased after irradiation. To cite this article:
Oliveira JAG, Escada ALA, Alves Rezende MCR, Mathor MB, Alves Claro APR. Analysis of the effects of irradiation in osseointegrated dental implants.
Clin. Oral Impl. Res. 23 , 2012 511–514.
doi: 10.1111/j.1600‐0501.2010.02149.x     

Early diagnosis of regional odontodysplasia in an infant

Regional odontodysplasia is a rare and significant dental malformation. It is a dental alteration of unknown etiology, involving both mesodermal and ectodermal dental components, which present clinical, radiographic, and histologic features. This article reports a clinical case of a 10-month-old child who was diagnosed with regional odontodysplasia in the maxilla, confirmed by radiographic examination, with a follow-up of 5 years. The clinical, radiographic, and histologic features were reviewed.     

Prediabetes: diagnosis, evaluation of chronic complications, and treatment

Type 2 diabetes mellitus accounts for 90% of diabetes cases and is associated with macro- and microvascular complications of high morbidity and mortality. Individuals with increased risk for type 2 diabetes include those with impaired fasting glucose (IFG), impaired glucose tolerance (IGT), and especially those with combined IFG and IGT. These individuals are part of a group known as prediabetes patients. Approximately 25% of individuals with prediabetes will develop type 2 diabetes in three to five years. Hyperglycemia, in the absence of diabetes, is also associated with increased risk of cardiovascular disease. Studies have shown that changes in lifestyle and drug interventions are effective in delaying or preventing type 2 diabetes in patients with prediabetes. Metformin is the drug of choice when medical treatment is warranted. IGT and IFG are associated with type 2 diabetes and, despite controversy, most studies reinforce the importance of these conditions in the development of micro- and macrovascular disease. Thus, therapeutic interventions in patients with prediabetes are important in primary prevention of type 2 diabetes and its chronic complications.     

Laser Therapy as an Effective Method for Implant Surface Decontamination: A Histomorphometric Study in Rats

Background: To the best of the authors’ knowledge, a standard protocol for treating peri‐implantitis is not yet established. Methods: A total of 150 titanium disks with smooth or rough surfaces contaminated with microbial biofilm were implanted subcutaneously in rats after undergoing one of three treatments: 1) low‐intensity laser (LIL); 2) antimicrobial photodynamic therapy (aPDT); or 3) toluidine blue O (TBO). Sterile and contaminated disks served as negative (NC) and positive (C) control groups, respectively. After days 7, 28, and 84, tissue inflammation was evaluated microscopically by measuring the density of collagen fibers (degree of fibrosis) and concentration of polymorphonuclear neutrophils. Results: Surface texture did not affect the degree of inflammation, but the area of reactive tissue was significantly greater for rough implants (2.6 ± 3.7 × 10⁶ µm²) than for smooth ones (1.9 ± 2.6 × 10⁶ µm²; P = 0.0377). Group C presented the lowest and group NC presented the highest degree of fibrosis with significance only after day 7; these groups had the highest and lowest scores, respectively, for degree of inflammation. Group C showed the largest area of reactive tissue (9.11 ± 2.10 × 10⁶ µm²), but it was not significantly larger than group LIL (P = 0.3031) and group TBO (P = 0.1333). Group aPDT showed the smallest area (4.34 ± 1.49 × 10⁶ µm²) of reactive tissue among the treatment groups. After day 28, groups LIL, aPDT, TBO, and C resembled group NC in all the studied parameters. Conclusion: Group aPDT showed more favorable results in parameter area of reactive tissue than the other methods after day 7, but over longer time periods all methods produced outcomes equivalent to sterile implants.     

Possible sleep bruxism,circadian preference,and sleep-related characteristics and behaviors among dental students

Objective: To assess sleep bruxism prevalence and its association with circadian preference and sleep-related characteristics among dental students.

Methods: Dental students of the Federal University of Minas Gerais participated in this cross-sectional study. Participants answered a scale assessing individuals' circadian preference, and a questionnaire regarding sleep-related characteristics and behaviors, history of muscle ache in the temporomandibular area, and history of bruxism.

Results: One hundred fifty-two students participated in the study. Sleep bruxism was reported by 11.3%. Most students (63.2%) were classified as intermediary, 34.9% as morningness, and 1.3% as eveningness. Individuals who reported muscle ache in the temporomandibular area in the morning (PR = 3.5; 95% CI = 1.1–11.5) were more likely to be in the group with sleep bruxism.

Conclusion: Muscle ache in the temporomandibular area is an important associated factor with sleep bruxism among dental students. Special attention should be paid to dental students’ circadian preference.