A comparative study between crack analysis and a mechanical test for assessing the polymerization stress of restorative composites

Objectives. To verify the hypothesis that crack analysis and a mechanical test would rank a series of composites in a similar order with respect to polymerization stress. Also, both tests would show similar relationships between stress and composite elastic modulus and/or shrinkage. Methods. Soda-lime glass discs (2-mm thick) with a central perforation (3.5-mm diameter) received four Vickers indentations 500 mu m from the cavity margin. The indent cracks were measured (500x) prior and 10 min after the cavity was restored with one of six materials (Kalore/KL, Gradia/GR, Ice/IC, Wave/WV, Majesty Flow/MF, and Majesty Posterior/MP). Stresses at the indent site were calculated based on glass fracture toughness and increase in crack length. Stress at the bonded interface was calculated using the equation for an internally pressurized cylinder. The mechanical test used a universal testing machine and glass rods (5-mm diameter) as substrate. An extensometer monitored specimen height (2 mm). Nominal stress was calculated dividing the maximum shrinkage force by the specimen cross-sectional area. Composite elastic modulus was determined by nanoindentation and post-gel shrinkage was measured using strain gages. Data were subjected to one-way ANOVA/Tukey or Kruskal-Wallis/Mann-Whitney tests (alpha: 5%). Results. Both tests grouped the composites in three statistical subsets, with small differences in overlapping between the intermediate subset (MF, WV) and the highest (MP, IC) or the lowest stress materials (KL, GR). Higher stresses were developed by composites with high modulus and/or high shrinkage. Significance. Crack analysis demonstrated to be as effective as the mechanical test to rank composites regarding polymerization stress. (c) 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Interaction between Trypanosoma rangeli and the Rhodnius prolixus salivary gland depends on the phosphotyrosine ecto-phosphatase activity of the parasite

Trypanosoma rangeli is the trypanosomatid that colonizes the salivary gland of its insect vector, with a profound impact on the feeding capacity of the insect. In this study we investigated the role of the phosphotyrosine (P-Tyr) ecto-phosphatase activity of T. rangeli in its interaction with Rhodnius prolixus salivary glands. Long but not short epimastigotes adhered to the gland cells and the strength of interaction correlated with the enzyme activity levels in different strains. Differential interference contrast microscopy demonstrated that clusters of parasites are formed in most cases, suggesting cooperative interaction in the adhesion process. The tightness of the correlation was evidenced by modulating the P-Tyr ecto-phosphatase activity with various concentrations of inhibitors. Sodium orthovanadate, ammonium molybdate and zinc chloride decreased the interaction between T. rangeli and R. prolixus salivary glands in parallel. Levamisole, an inhibitor of alkaline phosphatases, affected neither process. EDTA strongly inhibited adhesion and P-Tyr ecto-phosphatase activity to the same extent, an effect that was no longer seen if the parasites were pre-incubated with the chelator and then washed. When the P-Tyr ecto-phosphatase of living T. ranged epimastigotes was irreversibly inactivated with sodium orthovanadate and the parasite cells were then injected into the insect thorax, colonization of the salivary glands was greatly depressed for several days after blood feeding. Addition of P-Tyr ecto-phosphatase substrates such as p-nitrophenyl phosphate (pNPP) and P-Tyr inhibited the adhesion of T. rangeli to salivary glands, but P-Ser, P-Thr and beta-glycerophosphate were completely ineffective. Immunoassays using anti-P-Tyr-residues revealed a large number of P-Tyr-proteins in extracts of R. prolixus salivary glands, which could be potentially targeted by T. rangeli during adhesion. These results indicate that dephosphorylation of structural P-Tyr residues on the gland cell surfaces, mediated by a P-Tyr ecto-phosphatase of the parasite, is a key event in the interaction between T. rangeli and R. prolixus salivary glands. (C) 2012 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.

Comparative study of the proton beam effects between the conventional and Circular-Gate MOSFETs

The study of ionizing radiation effects on semiconductor devices is of great relevance for the global technological development and is a necessity in some strategic areas in Brazil. This work presents preliminary results of radiation effects in MOSFETs that were exposed to 3.2 Grad radiation dose produced by a 2.6-MeV proton beam. The focus of this work was to electrically characterize a Rectangular-Gate MOSFET (RGT) and a Circular-Gate MOSFET (CGT), manufactured with the On Semiconductor 0.5 mu m standard CMOS fabrication process and to verify a suitable geometry for space applications. During the experiment, I-DS x V-GS curves were measured. After irradiation, the RGT off-state current (I-OFF) increased approximately two orders of magnitude reaching practically the same value of the I-OFF in the CGT, which only doubled its value. (C) 2011 Elsevier B.V. All rights reserved.

Association between systemic corticosteroids and outcomes of intensive care unit-acquired pneumonia

Objective: The use of corticosteroids is frequent in critically-ill patients. However, little information is available on their effects in patients with intensive care unit acquired pneumonia. We assessed patients' characteristics, microbial etiology, inflammatory response, and outcomes of previous corticosteroid use in patients with intensive care unit acquired pneumonia. Design: Prospective observational study. Setting: Intensive care units of a university teaching hospital. Patients: Three hundred sixteen patients with intensive care unit acquired pneumonia. Patients were divided according to previous systemic steroid use at onset of pneumonia. Interventions: None. Measurements and Main Results: Survival at 28 days was analyzed using Cox regression, with adjustment for the propensity for receiving steroid therapy. One hundred twenty-five (40%) patients were receiving steroids at onset of pneumonia. Despite similar baseline clinical severity, steroid treatment was associated with decreased 28-day survival (adjusted hazard ratio for propensity score and mortality predictors 2.503; 95% confidence interval 1.176-5.330; p = .017) and decreased systemic inflammatory response. In post hoc analyses, steroid treatment had an impact on survival in patients with nonventilator intensive care unit acquired pneumonia, those with lower baseline severity and organ dysfunction, and those without etiologic diagnosis or bacteremia. The cumulative dosage of corticosteroids had no significant effect on the risk of death, but bacterial burden upon diagnosis was higher in patients receiving steroid therapy. Conclusions: In critically-ill patients, systemic corticosteroids should be used very cautiously because this treatment is strongly associated with increased risk of death in patients with intensive care unit acquired pneumonia, particularly in the absence of established indications and in patients with lower baseline severity. Decreased inflammatory response may result in delayed clinical suspicion of intensive care unit acquired pneumonia and higher bacterial count. (Crit Care Med 2012; 40:2552-2561)

Effect of the interaction between food state and the action of estrogen on oxytocinergic system activity

Increased plasma osmolality by food intake evokes augmentation of plasma oxytocin (OT). Ovarian steroids may also influence the balance of body fluids by acting on OT neurones. Our aim was to determine if estrogen influences the activity of OT neurones in paraventricular nucleus (PVN) and supraoptic nucleus (SON) under different osmotic situations. Ovariectomized rats (OVX) were treated with either estradiol (E-2) or vehicle and were divided into three groups: group I was fed ad libitum, group II underwent 48 h of fasting, and group III was refed after 48 h of fasting. On the day of the experiment, blood samples were collected to determine the plasma osmolality and OT. The animals were subsequently perfused, and OT/FOS immunofluorescence analysis was conducted on neurones in the PVN and the SON. When compared to animals which were fasted or fed ad libitum, the plasma osmolality of refed animals was higher, regardless of whether they were treated with vehicle or E-2. We observed neural activation of OT cells in vehicle-or E-2-treated OVX rats refed after 48 h of fasting, but not in animals fed ad libitum or in animals that only underwent 48 h of fasting. Finally, the percentage of neurones that co-expressed OT and FOS was lower in both the PVN and the SON of animals treated with E-2 and refed, when compared to vehicle-treated animals. These results suggest that E-2 may have an inhibitory effect on OT neurones and may modulate the secretion of OT in response to the increase of osmolality induced by refeeding. Journal of Endocrinology (2012) 212, 129-138

Association between parental guilt and oral health problems in preschool children

Parents may feel guilty about their children's oral problems, which can affect their quality of life. The aim of this study was to assess the presence of parental guilt and its association with early childhood caries (EGG), traumatic dental injuries (TDI) and malocclusion (AMT) in preschool children. All 2 to 5 year-old children (N = 305), and their parents, seeking dental care at the University of Sao Paulo Dental School one-week Screening Programme, were asked to participate in the study, and 260 agreed. Children were examined by two calibrated dentists, and their parents answered a socioeconomic and ECOHIS questionnaire; the question on guilt was used as the dependent variable. Regression analyses examined the association between parental guilt and EGG, TDI, AMT and socioeconomic factors. A total of 35.8% of parents felt guilty. This was only associated with caries severity. No association was found between guilt and TDI, AMT or socioeconomic factors. EGG was present in 63.8% of the children; the mean (+/-sd) dmf-t score was 7.29 (+/-2.78). Thus, the number of parents feeling guilty increases with the increase of their children's dental caries severity. Parental guilt is related to caries but is not associated with TDI or AMT.

Comparison of INAA elemental composition data between Lago Grande and Osvaldo archaeological sites in the central Amazon: a first perspective

In this work, 50 ceramic fragments from the Lago Grande and 30 from the Osvaldo archaeological site were compared to assess elemental similarities. The aim is to perform a preliminary comparison between the sites, which are located in the central Amazon, Brazil. The analytical technique employed to obtain the ceramics elemental composition was instrumental neutron activation analysis (INAA). The data set obtained was explored by the multivariate statistical techniques of cluster, principal component and discriminant analysis. The analyzed elements were: Na, Lu, U, Yb, La, Th, Cr, Cs, Sc, Fe, Eu, Ce and Hf. The results showed the existence of at least two compositional groups for Lago Grande and Osvaldo. Each compositional group of Osvaldo archaeological site matches with one group of Lago Grande. Correlated with the archaeological background, the results suggest commercial or cultural exchange in the region, which is an indicative of socio-cultural interactions between those sites.

Assessing apical transportation in curved canals: comparison between cross-sections and micro-computed tomography

The aim of this study was to compare two methods of assessing apical transportation in curved canals after rotary instrumentation, namely, cross-sections and micro-computed tomography (mu CT). Thirty mandibular molars were divided into two groups and prepared according to the requirements of each method. In G1 (cross-sections), teeth were embedded in resin blocks and sectioned at 2.0, 3.5, and 5.0 mm from the anatomic apex. Pre- and postoperative sections were photographed and analyzed. In G2 (mu CT), teeth were embedded in a rubber-base impression material and scanned before and after instrumentation. Mesiobuccal canals were instrumented with the Twisted File (TF) system (SybronEndo, Orange, USA), and mesiolingual canals, with the Endo Sequence (ES) system (Brasseler, Savannah, USA). Images were reconstructed, and sections corresponding to distances 2.0, 3.5, and 5.0 mm from the anatomic apex were selected for comparison. Data were analyzed using Mann-Whitney's test at a 5% significance level. The TF and ES instruments produced little deviation from the root canal center, with no statistical difference between them (P > 0.05). The canal transportation results were significantly lower (0.056 mm) in G2 than in G1 (0.089 mm) (p = 0.0012). The mu CT method was superior to the cross-section method, especially in view of its ability to preserve specimens and provide results that are more closely related to clinical situations.

Relationship between function, strength and electromyography of upper extremities of persons with tetraplegia

Study design: Cross-sectional. Objective: To analyze the relationships between functional tests, arm strength and root mean square of surface electromyography (EMG). Setting: Sao Paulo, Brazil. Methods: Twenty-four individuals with chronic tetraplegia participated. Upper extremity motor score (UEMS), functional independence measure (FIM) motor score, spinal cord independence measure III and capabilities of upper extremity (CUE) were performed. Muscle strength of the right elbow flexors-extensors was assessed using dynamometry and manual muscle test (MMT) and EMG of right biceps and triceps brachii were performed. Spearman's rank correlation coefficients and Mann-Whitney's U-test were used. Results: Functional tests and UEMS correlated strongly among them. UEMS highly correlated with triceps dynamometry and EMG. The dynamometry showed a very high correlation with MMT on the extensor group and a moderate correlation with flexor group. Triceps EMG showed moderate correlation with FIM and CUE. High correlations between triceps EMG and elbow extensors dynamometry and MMT were observed. A significant better performance on functional tests was observed on lower ASIA motor levels. The low-tetraplegia group showed a significant higher score on triceps EMG and dynamometry. Conclusion: Arm strength and EMG seem to be related to functional capabilities and independence in chronic tetraplegia. Spinal Cord (2012) 50, 28-32; doi:10.1038/sc.2011.95; published online 30 August 2011

Association between celiac disease and Crohn's disease - a challenge to the coloproctologist

Over the past few years, many studies on the association between celiac disease and inflammatory bowel disease have been reported. The genetic origin of this association has prompted research that searches for a common link for the concomitant manifestation of these pathologies. Clinical studies aim not only to demonstrate this relation, but also to establish the epidemiological frequencies among affected individuals and their relatives as compared to the general population. The similar clinical symptoms, difficulties, diagnoses, and therapeutics are still a challenge, since this association is unknown to most coloproctologists, thereby culminating in treatments and surgical procedures with no benefits for the patient.

Association between IL8 haplotypes and pathogen levels in chronic periodontitis

Chronic periodontitis (CP) is considered to be a multifactorial disease influenced by microbial and genetic factors. The aim of the present study was to investigate whether the genetic susceptibility to CP in individuals with the IL8 ATC/TTC haplotype is associated with subgingival levels of periodontopathogens. Sixty-five individuals, grouped according to the presence (n=28) or absence (n=37) of the IL8 haplotype, were evaluated. After clinical periodontal evaluation, each group was subdivided according to the presence (CP) or absence (H) of periodontitis. Four subgingival samples were obtained from CP and two samples per subject from H patients. The levels and proportions of Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola were analyzed using quantitative real-time polymerase chain reaction (q-PCR). No differences were found in the proportion of periodontopathogenic bacteria between groups with the presence or absence of the IL8 haplotype. However, in the CP groups, the levels of periodontopathogens were significantly higher in the individuals withou the IL8 haplotype than in the individuals with the IL8 haplotype. These results suggest that periodontal destruction may occur in patients who are considered to be genetically susceptible to CP with a lower microbial challenge because of the presence of the IL8 ATC/TTC haplotype than in patients without this haplotype.

Relation between Tcc,bb and Xc,b from QCD.

We have studied, using double ratio of QCD (spectral) sum rules, the ratio between the masses of Tcc and X(3872) assuming that they are respectively described by the D−D∗ and D− ¯D∗ molecular currents. We found (within our approximation) that the masses of these two states are almost degenerate. Since the pion exchange interaction between these mesons is exactly the same, we conclude that if the observed X(3872) meson is a D ¯D∗ + c.c. molecule, then the DD∗ molecule should also exist with approximately the same mass. An extension of the analysis to the b-quark case leads to the same conclusion. We also study the SU(3) breakings for the T s Q Q /TQ Q mass ratios. Motivated by the recent Belle observation of two Zb states, we revise our determination of Xb by combining results from exponential and FESR sum rules.