Influence of thermal and mechanical cycling on the flexural strength of ceramics with titanium or gold alloy frameworks

Objectives. The aim of this study was to evaluate the effect of thermal and mechanical cycling alone or in combination, on the flexural strength of ceramic and metallic frameworks cast in gold alloy or titanium. Methods. Metallic frameworks (25 mm x 3 mm x 0.5 mm) (N = 96) cast in gold alloy or commercial pure titanium (Ti cp) were obtained using acrylic templates. They were airborne particle-abraded with 150 mu m aluminum oxide at the central area of the frameworks (8 mm x 3 mm). Bonding agent and opaque were applied on the particle-abraded surfaces and the corresponding ceramic for each metal was fired onto them. The thickness of the ceramic layer was standardized by positioning the frameworks in a metallic template (height: I mm). The specimens from each ceramic-metal combination (N = 96, n = 12 per group) were randomly assigned into four experimental fatigue conditions, namely water storage at 37 degrees C for 24 h (control group), thermal cycling (3000 cycles, between 4 and 55 degrees C, dwell time: 10 s), mechanical cycling (20,000 cycles under 10 N load, immersion in distilled water at 37 degrees C) and, thermal and mechanical cycling. A flexural strength test was performed in a universal testing machine (crosshead speed: 1.5 mm/min). Data were statistically analyzed using two-way ANOVA and Tukey`s test (alpha = 0.05). Results. The mean flexural strength values for the ceramic-gold alloy combination (55 +/- 7.2MPa) were significantly higher than those of the ceramic-Ti cp combination (32 +/- 6.7 MPa) regardless of the fatigue conditions performed (p < 0.05). Mechanical and thermo-mechanical fatigue decreased the flexural strength results significantly for both ceramic-gold alloy (52 +/- 6.6 and 53 +/- 5.6 MPa, respectively) and ceramic-Ti cp combinations (29 +/- 6.8 and 29 +/- 6.8 MPa, respectively) compared to the control group (58 +/- 7.8 and 39 SA MPa, for gold and Ti cp, respectively) (p < 0.05) (Tukey`s test). While ceramic-Ti cp combinations failed adhesively at the metal-opaque interface, gold alloy frameworks exhibited a residue of ceramic material on the surface in all experimental groups. Significance. Mechanical and thermo-mechanical fatigue conditions decreased the flexural strength values for both ceramic-gold alloy and ceramic-Ti cp combinations with the results being significantly lower for the latter in all experimental conditions. (C) 2007 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Prevalence of cognitive and functional impairment in a community sample from Sao Paulo, Brazil

Aims: To present the prevalence of cognitive and functional impairment (CFI) in community-dwelling elderly subjects from the city of Sao Paulo. Methods: The population was aged 60 years and older (n = 1,563; 68.7% women and 31.3% men) and lived in different socioeconomic areas. The following instruments were administered to the elderly: the Mini Mental State Examination and the Fuld Object Memory Evaluation. The Informant Questionnaire on Cognitive Decline in the Elderly and the Bayer-Activities of Daily Living scale were administered to an informant. Results: The prevalence of CFI (n = 250) was 16% (95% confidence interval, CI: 14.2-17.8%) or 15.8% (95% CI: 13.8-17.8%). In regression models, the increase in the odds ratio (OR) of CFI was associated with age, for elderly individuals aged 75 years or older, illiterates or with 1-4 years of schooling, and with a history of stroke and diabetes mellitus. On the other hand, for subjects with a tumor history, the OR of CFI was significantly reduced. Conclusion: CFI was high and increased at older ages and in subjects with low education. Potentially changeable factors were identified (stroke and diabetes), and the possible `protective effect` of tumor/cancer against CFI should be further investigated by longitudinal studies. Copyright (C) 2007 S. Karger AG, Basel.

Tension band wire fixation for valgus osteotomies of the proximal femur: A biomechanical study of three configurations of fixation

Background. A variety of techniques can be used to achieve stabilization of femoral valgus osteotomies in children, but what is lacking is a versatile fixation system that associates stability and versatility at different ages and for different degrees of deformity. Methods. Mechanical tests of three configurations used to fix femoral valgus osteotomies, based oil the tension band wire principle, were carried out. A 30 degrees wedge valgus osteotomy was performed at the subtrochanteric level in 60 swine femurs and fixed with three different systems. In Group 1, two Kirschner wires (K wire) were introduced from the tip of the greater trochanter to the medial cortex, crossing the osteotomy. A flexible steel wire was anchored to the K wires into holes in the lateral cortex and tightened to form a tension band. The same setup was used in Group 2, but two additional smooth K wires were inserted into the lateral surface of the greater trochanter and driven to the femoral head with the distal extremities bent and tied around tile bone shaft. In Group 3, the fixation was similar to that in Group 2, but tile ascending K wires were introduced below the osteotomy level, crossing the osteotonly. Mechanical tests in bending-compression and torsion were used to access the stability. Findings. The torsional relative stiffness was 116% greater for Group 3 (0.27 N m/degree) and no significant difference was found between Group 1 (0.10 N m/degree) and Group 2 (0.12 N m/degree). The average torque was 103% higher for Group 3 (1.86 N m). Stiffness in bending-compression was significantly higher in Group 3 (508 x 10(3) N/m) than in Group 1 (211 x 10(3) N/m) and Group 2 (219 x 10(3) N/m). Interpretation. Fixation as used in Group 3 was significantly more stable, both in torsion and bending-compression tests, than tile other two techniques. (c) 2007 Elsevier Ltd. All rights reserved.

Role of Interleukin (IL)-18 in experimental paracoccidioidomycosis

Interleukin (IL)-18 has been regarded as a Th1 type cytokine involved in many fungal and parasitic infections. Since there have been no studies, as of yet, evaluating the role of this cytokine in paracoccidioidomycosis (PCM), we assessed the function of IL-18 by using an experimental PCM model. Our results showed that IL-18 knockout (IL-18-/-) BALB/c were more resistant to Paracoccidioides brasiliensis than their littermate controls (WT). In fact, mortality rate was higher in WT mice and in the first month of infection, the number of colony forming units of the etiologic agent recovered from the lungs was greater in WT mice. In histopathological analyses, well-formed granulomas were seen in both WT and IL-18-/- mice. However, substantial differences were observed at the second month of infection when epithelioid cells predominated in the lesions of IL-18-/- mice, which could infer that IL-18 postpones pulmonary healing. The levels of IL-10 were significantly higher in IL-18 sufficient mice at early stages of infection and therefore account for the delayed fungal clearance observed in WT mice. TNF- augmented later in the infection of WT mice, seemingly to compensate high levels of IL-10. Our results demonstrated that IL-18 has a critical role in protecting BALB/c mice against disseminated PCM.

Descriptive findings on the morphology of dendritic spines in the rat medial amygdala

The rat posterodorsal medial amygdala (MePD) is a brain area in which gonadal hormones induce notable plastic effects in the density of dendritic spines. Dendritic spines are post-synaptic specializations whose shape and spacing change neuronal excitability. Our aim was to obtain new data on the dendritic spines morphology and density from MePD neurons using the carbocyanine dye Dil under confocal microscopy. In adult male rats, the dendritic spine density of the medial branches of the left MePD (mean +/- SD) was 1.15 +/- 0.67 spines/dendritic mu m. From the total sampled, approximately 53% of the spines were classified as thin, 22.5% as ""mushroom-like"", and 21.5% as stubby/wide. Other spine shapes (3%) included those ramified, with a filopodium-like or a gemule appearance, and others with a protruding spinule. Additional experiment joining Dil and synaptophysin (a pre-synaptic protein) labeling suggested synaptic sites on dendritic shafts and spines. Dendritic spines showed synaptophysin puncta close to their head and neck, although some spines had no evident labeled puncta on them or, conversely, multiple puncta appeared upon one spine. These results advance previous light microscopy results by revealing features and complexities of the dendritic spines at the same time that give new insight on the possible synaptic organization of the adult rat MePD. (C) 2010 Elsevier Ireland Ltd. All rights reserved.

Oropouche virus entry into HeLa cells involves clathrin and requires endosomal acidification

Oropouche virus (ORO), family Bunyaviridae, is the second most frequent cause of arboviral febrile illness in Brazil. Studies were conducted to understand ORO entry in HeLa cells. Chlorpromazine inhibited early steps of ORO replication cycle, consistent with entry/uncoating. The data indicate that ORO enters HeLa cells by clathrin-coated vesicles, by a mechanism susceptible to endosomal acidification inhibitors. Transmission electron microscopy and immunofluorescence indicated that ORO associates with clathrin-coated pits and can be found in association with late endosomes in a time shorter than 1 h. (C) 2008 Elsevier B.V. All rights reserved.

New transposons to generate GFP protein fusions in Candida albicans

Transposon elements are important tools for gene function analysis, for example they can be used to easily create genome-wide collections of insertion mutants. Transposons may also carry sequences coding for an epitope or fluorescent marker useful for protein expression and localization analysis. We have developed three new Tn5-based transposons that incorporate a GFP (green fluorescent protein) coding sequence to generate fusion proteins in the important fungal pathogen Candida albicans. Each transposon also contains the URA3 and Kan(R) genes for yeast and bacterial selection, respectively. After in vitro transposition, the insertional allele is transferred to the chromosomal locus by homologous recombination. Transposons Tn5-CaGFP and Tn5-CaGFP-URA3:FLIP can generate C-terminal truncated GFP fusions. A URA3 flipper recycling cassette was incorporated into the transposon Th5-CaGFP-UFRA3:FLIP. After the induction of Flip recombinase to excise the marker, the heterozygous strain is transformed again in order to obtain a GFP-tagged homozygous strains. In the Tn5-CaGFP-FL transposon the markers are flanked by a rare-cutting enzyme. After in vitro transposition into a plasmid-borne target gene, the markers are eliminated by restriction digestion and religation, resulting in a construct coding for full-length GFP-fusion proteins. This transposon can generate plasmid libraries of GFP insertions in proteins where N- or C-terminal tagging may alter localization. We tested our transposon system by mutagenizing the essential septin CDC3 gene. The results indicate that the Cdc3 C-terminal extension is important for correct septin filament assembly. The transposons described here provide a new system to obtain global gene expression and protein localization data in C. albicans. (c) 2008 Elsevier B.V. All rights reserved.

Oropouche virus experimental infection in the golden hamster (Mesocrisetus auratus)

Oropouche virus (OROV), of the family Bunyaviridae, is the second most frequent arbovirus causing febrile disease in Brazil. In spite of this, little is known about pathogenesis of OROV infection. This report describes an experimental model of OROV in golden hamster (Mesocricetus auratus). Following subcutaneous inoculation of OROV, over 50% of the animals developed disease characterized by lethargy, ruffled fur, shivering, paralysis, and approximately one third died. Animals were sacrificed on days 1, 3, 5, 8 and 11 post-inoculation to collect tissue samples from brain, heart, liver, lung, spleen, muscle and blood for virus titration, histology and OROV immunohistochemistry. OROV was detected in high titers in blood, liver and brain, but not in the other organs. Histopathology revealed meningoencephalitis and hepatitis, with abundant OROV antigen detected in liver and brain. Diffuse galectin-3 immunostaining in brain and liver supports microglial and Kupfer cells activation. This is the first description of an experimental model for OROV infection and should be helpful to study pathogenesis and possibly to test antiviral interventions such as drugs and vaccine candidates. (C) 2010 Elsevier B.V. All rights reserved.

Evaluation of an Enzyme-Linked Immunosorbent Assay Based on Araraquara Virus Recombinant Nucleocapsid Protein

Laboratory diagnosis of hantavirus cardiopulmonary syndrome (HCPS) in Brazil has been performed mostly by a detection of IgM antibodies to recombinant antigen purified from Sin Nombre virus and Andes Virus (ANDV). Recently, a recombinant nucleocapsid (rN) protein of Argentina virus (ARAV), a Brazilian hantavirus, was Obtained in Escherichia coli. To evaluate ARAV rN as antigen for antibody detection, serum samples from 30 patients front Argentina seropositive for hantavirus were tested. All samples were positive for IgG and IgM by enzyme-linked immunosorbent assay (ELISA) using either ARAV rN or ANDV rN antigens. In Brazil, six of 00 serum samples from patients With suspected HCPS (10%) were positive for IgM by ELISA Using ARAV rN antigen and 7 were positive Using ANDV rN antigen. For results obtained with 90 serum samples analyzed by IgM ELISA with ANDV rN antigen, the sensitivity of the IgM ELISA using ARAV rN antigen was 97.2%,, the specificity was 100%, the positive predictive value was 100% and the negative predictive value was 98.1%. The results show that ARAV rN is a Suitable antigen for diagnosis Of hantavirus infection in Brazil and Argentina.

Role of mixed Th1 and Th2 serum cytokines on pathogenesis and prognosis of hantavirus pulmonary syndrome

The hantavirus pulmonary syndrome (HPS) is an emerging syndrome in the Americas. The disease results from intense immune activation and changes in vascular permeability. The aim of this study was to determine the profile of serum cytokines in HPS patients looking for correlation with the clinical parameters, severity and outcome of illness. Studying 21 HPS patients, we found that IL-6 may have an important role in the pathogenesis of HPS, being associated with fatal outcome. Our results also support a mixed Th1/Th2 immune response during the course of HPS and that the magnitude of Th1 response effector cytokines is correlated to HPS severity. The decreased levels of TGF-beta observed in HPS patients suggest that immunoregulatory activity could be damaged in these patients. (c) 2008 Elsevier Masson SAS. All rights reserved.

Turbulent blood flow plays an essential localizing role in the development of atherosclerotic lesions in experimentally induced hypercholesterolaemia in rats

Taking into account that atherosclerosis is a focal disease and high levels of plasma cholesterol are closely correlated with its pathogenesis, it is a challenge to explain how equal concentrations of cholesterol bathing the endothelium can produce local, rather than global, effects on arteries. The focal distribution of atherosclerotic lesions has been considered to be dependent, at least in part, on hydrodynamic factors. The present study was carried out to further test the hypothesis that these forces are an important localizing factor in rats feeding a hypercholesterolaemic diet and submitted to infra-diaphragmatic aortic constriction. These animals develop a normotensive prestenotic region with laminar blood flow that serves as control for a normotensive poststenotic region with turbulent blood flow. Our findings clearly demonstrated that the combination of turbulent blood flow and low wall shear stress (WSS) in the presence of hypercholesterolaemia and oxidative stress creates conditions to the formation of focally distributed incipient atherosclerotic lesions observed in the poststenotic segment. In contrast, only diffuse fatty streaks could be observed in the normotensive prestenotic segment with laminar blood flow and normal WSS in the presence of hypercholesterolaemia and oxidative stress. Although haemodynamic forces are not by themselves responsible for the pathogenesis of atherosclerosis, they prime the local vascular wall in which the lesion develop. Further studies are required to establish how haemodynamic forces are detected and transduced into chemical signalling by the cells of the artery wall and then converted into pathophysiologically relevant phenotypic changes.

Natural Host Relationships and Genetic Diversity of Rodent-Associated Hantaviruses in Southeastern Brazil

Objective: Hantaviruses are rodent-borne RNA viruses that have caused hantavirus cardiopulmonary syndrome in several Brazilian regions. In the present study, geographical distribution, seroprevalence, natural host range, and phylogenetic relations of rodent-associated hantaviruses collected from seven counties of Southeastern Brazil were evaluated. Methods: ELISA, RT-PCR and phylogenetic analysis were used in this study. Results: Antibodies to hantavirus were detected in Bolomys lasiurus, Akodon sp. and Oligoryzomys sp., performing an overall seroprevalence of 5.17%. All seropositive rodents were associated with grasslands or woods surrounded by sugar cane fields. Phylogenetic analysis of partial S- and M-segment sequences showed that viral sequences isolated from B. lasiurus specimens clustered with Araraquara virus. However, a sequence from Akodon sp. shared 100% similarity with Argentinian/Chilean viruses based on the partial S- segment amino acid sequence. Conclusion: These results indicate that there are associations between rodent reservoirs and hantaviruses in some regions of Southeastern Brazil, and suggest the existence of additional hantavirus genetic diversity and host ecology in these areas. Copyright (C) 2008 S. Karger AG, Basel

Influence of Nocturnal Asthma on Chronotype

Individual differences in circadian rhythm have been studied since the past century. Chronotypes are a chronobiology classification based on the preferential times for beginning and ending activities throughout the day. Chronotypes can be classified as definitely morning, moderately morning, indifferent, moderately evening, and definitely evening. We aim to assess the distribution of chronotypes in asthmatics and the relationship of chronotype to the presence of nocturnal symptoms. Two hundred subjects were evaluated, 100 asthmatics and 100 non-asthmatics. The Morningness/Eveningness questionnaire was applied for chronotype determination. The asthmatics were subdivided according to the presence or absence of nocturnal symptoms. The chronotype distribution did not differ significantly between asthmatics and non-asthmatics. Thirty-five percent of the asthma group reported nocturnal symptoms. There was a significant difference in chronotype distribution between asthmatics with and without nocturnal worsening. The asthmatics with nocturnal symptoms had a lower prevalence of morning types and had a greater predominance of indifferent chronotype compared to asthmatics without nocturnal symptoms (p = 0.011). In conclusion, asthmatics with nocturnal symptoms present deviation from the chronotype distribution curve when compared to asthmatics without nocturnal symptoms. This is the first study to show the effect of a disease on chronotypes.

Combining two potential causes of metalloproteinase secretion causes abdominal aortic aneurysms in rats: a new experimental model

P>Progress in understanding the pathophysiology of abdominal aortic aneurysms (AAA) is dependent in part on the development and application of effective animal models that recapitulate key aspects of the disease. The objective was to produce an experimental model of AAA in rats by combining two potential causes of metalloproteinase (MMP) secretion: inflammation and turbulent blood flow. Male Wistar rats were randomly divided in four groups: Injury, Stenosis, Aneurysm and Control (40/group). The Injury group received a traumatic injury to the external aortic wall. The Stenosis group received an extrinsic stenosis at a corresponding location. The Aneurysm group received both the injury and stenosis simultaneously, and the Control group received a sham operation. Animals were euthanized at days 1, 3, 7 and 15. Aorta and/or aneurysms were collected and the fragments were fixed for morphologic, immunohistochemistry and morphometric analyses or frozen for MMP assays. AAAs had developed by day 3 in 60-70% of the animals, reaching an aortic dilatation ratio of more than 300%, exhibiting intense wall remodelling initiated at the adventitia and characterized by an obvious inflammatory infiltrate, mesenchymal proliferation, neoangiogenesis, elastin degradation and collagen deposition. Immunohistochemistry and zymography studies displayed significantly increased expressions of MMP-2 and MMP-9 in aneurysm walls compared to other groups. The haemo-dynamic alterations caused by the stenosis may have provided additional contribution to the MMPs liberation. This new model illustrated that AAA can be multifactorial and confirmed the key roles of MMP-2 and MMP-9 in this dynamic remodelling process.

The H63D genetic variant of the HFE gene is independently associated with the virological response to interferon and ribavirin therapy in chronic hepatitis C

Background Conflicting results have been reported in studies evaluating the relationship between serum markers of iron overload, liver iron deposits, and HFE mutations (C282Y and H63D) in chronic hepatitis C patients, and also their impact on the response to therapy in these patients. Aim To evaluate the role of HFE mutations in the severity of liver disease and in the response to therapy in chronic hepatitis C. Methods Two hundred and sixty-four hepatitis C patients treated with standard interferon and ribavirin were divided into two groups according to type of antiviral response: sustained virological response (SVR) and nonresponse or relapse. We evaluated the relationship between HFE mutation and the type of antiviral response, clinical data, biochemical tests, liver histopathology, virological data, and HFE mutations. Results Of the 264 patients, 88 (32.1%) had SVR whereas 67.9% had nonresponse or relapse. Liver iron deposits were observed in 49.2% of the patients. The factors associated with SVR were hepatitis C virus genotype 2 or 3, transferrin saturation value of 45% or less, and detection of the H63D mutation. HFE mutation was more frequent in patients with iron deposits, but without association with serum iron biochemistry or severity of liver disease. Steatosis was more frequent in patients with liver iron deposits. Conclusion The H63D mutation was an independent factor associated with SVR in chronic hepatitis C patients, as also were hepatitis C virus genotype 2 or 3 and transferrin saturation value of 45% or less. Moreover, the H63D mutation was associated with liver iron deposits. Eur J Gastroenterol Hepatol 22: 1204-1210 (C) 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins.