In situ effect of an erosive challenge on different restorative materials and on enamel adjacent to these materials

Objectives: This in situ study evaluated the effect of an erosive challenge on different restorative materials and on enamel restored with these materials, as well as the ability of these materials to protect the adjacent enamel against erosion. Methods: Ten volunteers wore palatal devices with eight bovine enamel blocks, randomly selected and distributed into two vertical rows, corresponding to the following groups: GI/GV, resin-modified glass ionomer; GII/GVI, conventional glass ionomer; GIII/GVII, composite resin; GIV/GVIII, amalgam. one row (corresponding to groups I-IV) was immersed in a cola drink and the other row (corresponding to groups V-VIII) was subjected to saliva only. The palatal device was continuously worn for 7 days and only half of the appliance (groups I-IV) was immersed in the soft drink (Coca-Cola (R), 150 mL) for 5 min, three times a day. The study variables comprised the wear (profilometry, mu m) and the percentage of surface microhardness change (%SMHC). Data were tested for significant differences by two-way ANOVA and Tukey`s tests (p < 0.05). Results: Considering the restorative materials, for %SMHC and wear, there were no differences among the materials and between the saliva and the erosive challenge. For enamel analyses, the erosive challenge promoted a higher wear and %SMHC of the enamel than did the saliva. There were no significant differences in wear and %SMHC of the enamel adjacent to the different restorative materials. Conclusion: This research data suggest that there is little %SMHC and wear of the studied restorative materials and none of them had a preventive effect against erosion on adjacent enamel, which showed a pronounced wear. (c) 2007 Elsevier Ltd. All rights reserved.

Push-out strength of methacrylate resin-based sealers to root canal walls

P>Aim To assess the push-out strength of Epiphany SE, Epiphany and Hybrid Root SEAL to the dentine walls of root canals. Methodology Sixty roots of canines were prepared and distributed to six groups (n = 10) according to the filling material: GI - Epiphany SE, GII - Epiphany primer and sealer, GIII - Epiphany primer, sealer and resinous solvent, GIV - Clearfil DC Bond and Epiphany sealer, GV - Clearfil, Epiphany sealer and solvent and GVI - Hybrid Root SEAL. Resilon cones were used in all groups. Roots were sectioned transversally to obtain three slices from each third. One slice was subjected to the push-out test (MPa), and results were analysed by anova and Tukey`s test (P < 0.05). The other two slices were prepared for scanning electron microscopy (SEM). Failure mode was also analysed. Results A statistically significant difference (P < 0.05) occurred between Hybrid Root SEAL (5.27 +/- 2.07) and the other materials, GI (0.40 +/- 0.23), GII (0.78 +/- 0.45), GIII (0.57 +/- 0.28), GIV (0.40 +/- 0.24) and GV (0.50 +/- 0.41), which did not differ significantly from each other (P > 0.05). Adhesive failures predominated in groups I, II, IV and V, whilst mixed and cohesive failures were the most frequent in groups III and VI, respectively. There were gaps in the adhesive interface of GI and GII, continuity areas of the filling material with dentine in GIV and GV and good adaptation of the interface of GVI. Conclusion Hybrid Root SEAL had greater push-out strength to root canal dentine than Epiphany SE and Epiphany. The use of primer, solvent and adhesive system did not influence the adhesion of Epiphany.

Coronal resistance to fracture of endodontically treated teeth submitted to light-activated bleaching

Objectives: The aim of this study was to assess the fracture resistance of endodontically treated teeth submitted to bleaching with 38% hydrogen peroxide activated by light-emitting diode (LED)-laser system. Methods: Fifty maxillary incisors were endodontically treated, received a zinc phosphate barrier and were embedded in acrylic resin until cemento-enamel junction. The specimens were distributed into five groups (n = 10) according to the number of bleaching sessions: GI, no treatment (control); GII, one session; GIII, two sessions; GIV, three sessions and GV, four sessions. The whitening gel was applied to the buccal surface of the tooth and inside the pulp chamber for three times in each session, followed by LED-laser activation. Specimens were submitted to the fracture resistance test (kN) and data were submitted to the Tukey-Kramer multiple comparisons test. Results: No significant difference (p > 0.05) was found between GI (0.71 +/- 0.30) and GII (0.65 +/- 0.13), which presented the highest strength values to fracture. Groups III (0.35 +/- 0.17), IV (0.23 +/- 0.13) and V (0.38 +/- 0.15) showed lower resistance to fracture (p < 0.01) when compared to GI and GII. Conclusions: The fracture resistance of endodontically treated teeth decreased after two sessions of bleaching with 38% hydrogen peroxide activated by LED-laser system. (c) 2008 Elsevier Ltd. All rights reserved.

Influence of different endodontic filling materials on root fracture susceptibility

Objective: To evaluate the influence of different endodontic materials on root fracture susceptibility. Methods: Seventy-two mandibular incisors were sectioned 1 mm below the cementoenamel junction to obtain roots of 12 mm length. Roots were submitted to chemomechanical preparation with the rotary instruments of Profile system. The obturation of root canals were performed with the following filling materials (n = 12): GI, unfilled teeth (control); GII, Endofill + gutta-percha; GIII, Sealer 26 + gutta-percha; GIV, AH Plus + gutta-percha; GV, Epiphany + gutta-percha; GVI, Epiphany + Resilon. After the sealers setting time, each root was embedded in acrylic resin. The specimens were then submitted to fracture resistance test using an Instron testing machine at 1 mm/min. Results: The ANOVA test showed no significant statistical difference (p > .05) among GI (162.16 +/- 41.4N), GII (168.46 +/- 37.5N), GIII (164.83 +/- 35.7N), GIV (168.29 +/- 38.7N), GV (172.36 +/- 20.6N) and GVI (193.11 +/- 42.8N). Conclusion: The core materials (gutta-percha or Resilon) combined with the tested endodontic sealers are not able to increase the root fracture resistance in canals submitted to chemomechanical preparation. (c) 2007 Elsevier Ltd. All rights reserved.

Influence of Artificial Accelerated Aging on Dimensional Stability of Acrylic Resins Submitted to Different Storage Protocols

Purpose: The aim of this study was to evaluate the influence of artificial accelerated aging on dimensional stability of two types of acrylic resins (thermally and chemically activated) submitted to different protocols of storage. Materials and Methods: One hundred specimens were made using a Teflon matrix (1.5cmx0.5mm) with four imprint marks, following the lost-wax casting method. The specimens were divided into ten groups, according to the type of acrylic resin, aging procedure, and storage protocol (30 days). GI: acrylic resins thermally activated, aging, storage in artificial saliva for 16 hours, distilled water for 8 hours; GII: thermal, aging, artificial saliva for 16 hours, dry for 8 hours; GIII: thermal, no aging, artificial saliva for 16 hours, distilled water for 8 hours, GIV: thermal, no aging, artificial saliva for 16 hours, dry for 8 hours; GV: acrylic resins chemically activated, aging, artificial saliva for 16 hours, distilled water for 8 hours; GVI: chemical, aging, artificial saliva for 16 hours, dry for 8 hours; GVII: chemical, no aging, artificial saliva for 16 hours, distilled water for 8 hours; GVIII: chemical, no aging, artificial saliva for 16 hours, dry for 8 hours GIX: thermal, dry for 24 hours; and GX: chemical, dry for 24 hours. All specimens were photographed before and after treatment, and the images were evaluated by software (UTHSCSA-Image Tool) that made distance measurements between the marks in the specimens (mm), calculating the dimensional stability. Data were submitted to statistical analysis (two-way ANOVA, Tukey test, p = 0.05). Results: Statistical analysis showed that the specimens submitted to storage in water presented the largest distance between both axes (major and minor), statistically different (p < 0.05) from control groups. Conclusions: All acrylic resins presented dimensional changes, and the artificial accelerated aging and storage period influenced these alterations.

Early rise in blood pressure following administration of adrenocorticotropic hormone-[1-24] in humans

1. An elevation in blood pressure has been consistently observed 24 h after adrenocorticotropic hormone (ACTH) administration and is caused by increased ACTH-stimulated cortisol secretion, in association with increased cardiac output. The aim of the present study was to investigate the previously undefined time of onset of this increase in blood pressure in normal humans. 2. Ten normal healthy volunteers received 250 mug ACTH-[1-24], in 500 mL normal saline, infused at a constant rate over 8 h. Six subjects also received a placebo infusion (normal saline only). Blood pressure, heart rate and cortisol levels were determined hourly. Adrenocorticotropic hormone (ACTH-[1-24] plus native ACTH) was measured at 0, 1, 7 and 8 h. 3. Infusion of ACTH-[1-24] produced maximal secretion rates of cortisol, resulting in a mean peak plasma level of 985 +/- 46 nmol/L at 8 h. In response, blood pressure and heart rate rose significantly by 2 h and remained generally elevated for the duration of the infusion. 4. The early onset of haemodynamic responses is consistent with classical steroid receptor-mediated genomic mechanisms, but could be due non-genomic mechanisms. 5. The cardiovascular consequences of therapeutic use of ACTH are well recognized. This results of the present study suggest that even diagnostic administration of ACTH, delivered over a few hours, may raise blood pressure.

Coal dust exposures in the longwall mines of New South Wales, Australia: a respiratory risk assessment

This paper presents an analysis of personal respirable coal dust measurements recorded by the Joint Coal Board in the underground longwall mines of New South Wales from 1985 to 1999. A description of the longwall mining process is given. In the study, 11 829 measurements from 33 mines were analysed and the results given for each occupation, for seven occupational groups, for individual de-identified mines and for each year of study. The mean respirable coal dust concentration for all jobs was 1.51 mg/m(3) (SD 1.08 mg/m(3)). Only 6.9% of the measurements exceeded the Australian exposure standard of 3 mg/m(3). Published exposure-response relationships were used to predict the prevalence of progressive massive fibrosis and the mean loss of FEV1, after a working lifetime (40 years) of exposure to the mean observed concentration of 1.5 mg/m(3). Prevalences of 1.3 and 2.9% were predicted, based on data from the UK and the USA, respectively. The mean loss of FEV1 was estimated to be 73.7 ml.

Tratamento de hérnia umbilical em bovinos

Bovinos jovens são frequentemente acometidos por hérnias umbilicais. Neste trabalho, avaliou-se a ocorrência e estabeleceu-se o tratamento cirúrgico para hérnias umbilicais em bovinos jovens, empregando 78 bezerros distribuídos em seis grupos. Em GI e GIV, na laparorrafia, utilizou-se sutura jaquetão; em GII e GV, jaquetão modificado e, em GIII e GVI, sutura separada simples com pontos de relaxamento. Em GI, GII e GIII utilizou-se fio de algodão e, em GIV, GV e GVI, de náilon. Dados não paramétricos, envolvendo a recuperação dos animais e sua independência ou associações com o padrão de sutura foram analisados pelo teste do Qui-quadrado e Exato de Fisher, fazendo-se uso do programa computacional Statistical Analysis System, a 5% (p < 0,05). Os demais resultados foram analisados descritivamente. A ocorrência de hérnia umbilical em bovinos foi expressiva e a herniorrafia, empregando-se fio de algodão, apresentou maiores complicações pós-operatórias; porém a maioria dos animais recuperou-se. O fio e o padrão de sutura, manejo pós-operatório, resposta individual e o tamanho do anel herniário influenciam na reabilitação dos animais e na redução das complicações pós-operatórias.

Selection of full-sib families of Panicum maximum Jacq under low light conditions

The silvopastoral system is a viable technological alternative to extensive cattle grazing, however, for it to be successful, forage grass genotypes adapted to reduced light need to be identified. The objective of this study was to select progenies of Panicum maximum tolerant to low light conditions for use in breeding programs and to study the genetic control and performance of some traits associated with shade tolerance. Six full-sib progenies were evaluated in full sun, 50% and 70% of light reduction in pots and subjected to cuttings. Progeny genotypic values ​​(GV) increased with light reduction in relation to plant height (H) and specific leaf area (SLA). The traits total dry mass accumulation (DM) and leaf dry mass accumulation (LDM) had GV higher in 50% shade and intermediate in 70% shade. The GV of tiller number (TIL) and root dry mass accumulation (RDM) decreased with light reduction. The highest positive correlations were obtained for the traits H and RDM with SLA and DM; the highest negative correlations were between TIL and SLA and RDM, and H and LDM. The progenies showed higher tolerance to 50% light reduction and, among them, two stood out and will be used in breeding programs. It was also found that it is not necessary to evaluate some traits under all light conditions. All traits had high broad sense heritability and high genotypic correlation between progenies in all light intensities. There is genetic difference among the progenies regarding the response to different light intensities, which will allow selection for shade tolerance

Efeitos de níveis de privação alimentar sobre a oogênese de Panstrongylus megistus

Os efeitos da privação alimentar sobre a oogênese de P. megistus foram estudados em laboratório. Imediatamente após a ecdise imaginária, foram formados seis grupos (GI a GVI) de 15 casais, que receberam alimentação da seguinte maneira: GI -- no 5º e no 25º dias de jejum; GII -- no 5º e 35º dias; GIII -- no 5º e no 45º dias; GIV -- no 20º dia; GV -- no 30º dia; GVI -- no 40º dia de jejum. Após esses períodos, todos os grupos receberam alimentação a cada 15 dias. O grupo de controle foi formado por 15 casais, alimentados no 5º dia após a ecdise imaginária e, subseqüentemente, a cada 15 dias. GI apresentou o maior número de acasalamentos, produziu mais ovos e maior fertilidade. GII teve maior vida média, maior fecundidade e maior número de eclosões. GIII apresentou o menor período de sobrevivência, baixas fecundidade, fertilidade e eclosões. GVI apresentou os resultados menos favoráveis em todos os parâmetros, exceto em relação ao período de pré-ovipostura. O grupo de controle apresentou os melhores resultados em todos os parâmetros.

Image quality of myocardial perfusion-gated studies: effect of ingestion of different fat content in the reduction of extra-myocardial abdominal signal

Myocardial perfusion-gated-SPECT (MP-gated-SPECT) imaging often shows radiotracer uptake in abdominal organs. This accumulation interferes frequently with qualitative and quantitative assessment of the infero-septal region of myocardium. The objective of this study is to evaluate the effect of ingestion of different fat content on the reduction of extra-myocardial uptake and to improve MP-gated-SPECT image quality. In this study, 150 patients (65 ^ 18 years) who were referred for MP-gated-SPECT underwent a 1-day-protocol including imaging after stress (physical or pharmacological) and resting conditions. All patients gave written informed consent. Patients were subdivided into five groups: GI, GII, GIII, GIV and GV. In the first four groups, patients ate two chocolate bars with different fat content. Patients in GV – control group (CG) – had just water. Uptake indices (UI) of myocardium (M)/liver(L) and M/stomach–proximal bowel(S) revealed lower UI of M/S at rest in all groups. Both stress and rest studies using different food intake indicate that patients who ate chocolate with different fat content showed better UI of M/L than the CG. The UI of M/L and M/S of groups obtained under physical stress are clearly superior to that of groups obtained under pharmacological stress. These differences are only significant in patients who ate high-fat chocolate or drank water. The analysis of all stress studies together (GI, GII, GIII and GIV) in comparison with CG shows higher mean ranks of UI of M/L for those who ate high-fat chocolate. After pharmacological stress, the mean ranks of UI of M/L were higher for patients who ate high- and low-fat chocolate. In conclusion, eating food with fat content after radiotracer injection increases, respectively, the UI of M/L after stress and rest in MP-gated-SPECT studies. It is, therefore, recommended that patients eat a chocolate bar after radiotracer injection and before image acquisition.

Treatment of T. cruzi infected human platelet concentrates with aminomethyltrimethyl psoralen (AMT) and ultravioleta (UV-A) light: preliminary results

The present measures adopted to prevent transfusion-associated Chagas' disease include screening of blood donors. and/or the inactivation of T. cruzi in collected blood using gentian violet (GV) as a trypanocidal agent. In this study, we investigated the efficacy of the combined use of AMT and UV-A in inactirating T. cruzi in infected human platelet cuncentrates. Human platelet concentrates were infected with T. cruzi (2x10/ml) of the Y strain transfered to PL 269 (Fenwal Laboratories) containers and treated with GV (250řg,/ml). and ascorbic acid (1 mg/ml); GV. ascorbic acid and UV-A; GV and UV-A; AMT (40/tG/ml) and ascorbic acid; AMT, ascorbic acid and UV-A; AMT and UV-A; UV-A alone; and untreated (control). All UV-A treated platelet concentrates were exposed to UV-A doses of 24, 92, 184, 276, 368 and 644 kj/m². and the microscopical research of active T. cruzi was performed, using the microhematocrit technique, 1, 6 and 24 hours after each treatment. A high number of active forms of T. cruzi was observed in all condictions, except when GV was used as the trypanocidal agent, providing evidence of the failure of AMT and UV-A in inactivating T cruzi in infected human platelet concentrates.

Pyruvate kinase and glucose-6-phosphate dehydrogenase deficies and their association with malaria - population genetics and proteomic studies

A malária é reconhecida como uma das principais forças selectivas a actuar na história recente no genoma humano. Inúmeros polimorfismos genéticos têm sido descritos como protectores contra a gravidade da malária, como o alelo HbS (designado de traço falciforme) e o alelo G6PD A- (associado à deficiência de G6PD). Mais recentemente, também a deficiência de PK foi associada com a protecção contra a malária. Evidências desta associação foram obtidas em estudos com modelos de roedor e estudos in vitro utilizando GV humanos deficientes em PK. Até à data, não foram obtidos dados em populações humanas que revelem esta associação: ainda não foi identificada uma variante de PK com uma prevalência elevada em regiões endémicas de malária e não foram identificadas marcas de selecção na região do gene que codifica para a PK (gene PKLR). Além disso, os mecanismos subjacentes à protecção contra a malária por deficiências enzimáticas dos GV não estão bem esclarecidos. Assim, os objectivos do presente estudo foram: investigar os polimorfismos genéticos humanos com associação com a malária em Cabo Verde; pesquisar marcas de selecção da malária na região do gene PKLR em populações Africanas; determinar a frequência da deficiência em PK e identificar uma eventual variante da enzima que possa estar sob selecção positiva em regiões endémicas de malária; avaliar o efeito das duas deficiências enzimáticas (PK e G6PD) na invasão e maturação do parasita em culturas in vitro de Plasmodium usando GV normais e deficientes; e analisar o perfil proteómico de GV infectados e não infectados, normais e com deficiência (em PK e G6PD), bem como de parasitas isolados de GV tanto deficientes como normais. Em Cabo Verde (área epidémica), não foram identificadas marcas de selecção pela malária, através da análise dos vários polimorfismos. No entanto, quando a análise foi realizada em dois países endémicos (Angola e Moçambique), foram detectadas várias marcas de selecção: a genotipagem de microssatélites (STRs) e polimorfismos de base única (SNPs) localizados na vizinhança do gene PKLR revelou uma diferenciação consideravelmente maior entre as populações Africana e Europeia (Portuguesa), do que a diferenciação determinada aquando da utilização de marcadores genéticos neutros. Além disso, uma região genómica de maior amplitude apresentou um Desequilíbrio de Ligação (LD) significativo no grupo de malária não grave (e não no grupo de malária grave), sugerindo que a malária poderá estar a exercer pressão selectiva sobre a região do genoma humano que envolve o gene PKLR. No estudo que incidiu na determinação da prevalência da deficiência de PK no continente Africano (realizado em Moçambique), esta revelou-se elevada - 4,1% - sendo o valor mais elevado descrito até ao momento a nível mundial para esta enzimopatia. Na pesquisa de mutações que pudessem estar na causa deste fenótipo (baixa actividade de PK), foi identificada uma mutação não sinónima 829G>A (277Glu>Lys), significativamente associada à baixa actividade enzimática. Esta mutação foi também identificada em Angola, São Tomé e Príncipe e Guiné Equatorial, onde a frequência de portadores heterozigóticos foi entre 2,6 e 6,7% (valores que se encontram entre os mais elevados descritos globalmente para mutações associadas à deficiência em PK). Não foi possível concluir acerca da associação entre a deficiência de PK e o grau de severidade da malária e da associação entre o alelo 829A e a mesma, devido ao baixo número de amostras. Os resultados dos ensaios de invasão/maturação do parasita sugeriram que, nos GV com deficiência de PK ou G6PD, a invasão (onde está envolvida a membrana do GV hospedeiro e o complexo apical do parasita) é mais relevante para a eventual protecção contra a malária do que a maturação. Os resultados da análise proteómica revelaram respostas diferentes por parte do parasita nas duas condições de crescimento (GV com deficiência de PK e GV com deficiência de G6PD). Esta resposta parece ser proporcional à gravidade da deficiência enzimática. Nos parasitas que cresceram em GV deficientes em G6PD (provenientes de um indivíduo assintomático), a principal alteração observada (relativamente às condições normais) foi o aumento do número de proteínas de choque térmico e chaperones, mostrando que os parasitas responderam às condições de stress oxidativo, aumentando a expressão de moléculas de protecção. Nos parasitas que cresceram em condições de deficit de PK (GV de indivíduo com crises hemolíticas regulares, dependente de transfusões sanguíneas), houve alteração da expressão de um maior número de proteínas (relativamente ao observado em condições normais), em que a maioria apresentou uma repressão da expressão. Os processos biológicos mais representados nesta resposta do parasita foram a digestão da hemoglobina e a troca de proteínas entre hospedeiro e parasita/remodelação da superfície do GV. Além disso, uma elevada percentagem destas proteínas com expressão alterada está relacionada com as fendas de Maurer, que desempenham um papel importante na patologia da infecção malárica. É colocada a hipótese de que a protecção contra a malária em GV deficientes em PK está relacionada com o processo de remodelação da membrana dos GV pelo parasita, o que pode condicionar a invasão por novos parasitas e a própria virulência da malária. Os resultados da análise do proteoma dos GV contribuirão para confirmar esta hipótese.

Synthesis, physical and magnetic properties of BaFe12O19/P(VDF-TrFE) multifunctional composites

Composite films with filler microparticles of Barium ferrite dispersed within P(VDF-TrFE) as polymeric matrix have been prepared by solvent evaporation. The lowest BaFO content of 1% wt acts as a small defect within the polymeric matrix, reducing the values of the dielectric and mechanical properties of the pure P(VDF-TrFE). For filler contents up to a 20%, the BaFO filler reinforces the matrix and measured properties increase their values. This trend is not followed by the electrical conductivity. We extended the study to fibers composed by BaFe12O19 microparticles in a PVDF matrix. Due to the big size of BaFO particles (1 micron in diameter), proper fabrication of the fiber shaped composites has not been achieved. We found that true BaFO content are always lower than nominal ones. Results are discussed in terms of the influence of size and morphology of the BaFO particles on the initial properties of the polymeric matrix.

Energy harvesting device based on a metallic glass/PVDF magnetoelectric laminated composite

A flexible and low cost energy harvester device based on the magnetoelectric (ME) effect has been designed using Fe64Co17Si7B12 as amorphous magnetostrictive ribbons and PVDF as the piezoelectric element. Sandwich-type laminated composite of 3 cm long has been fabricated by gluing these ribbons to the PVDF with the Devcon 5 minute epoxy. Good power output and power density of 6.4 μW and 1.5 mW/cm3, respectively, have been obtained through a multiplier circuit. All values have been measured at the magnetomechanical resonance of the laminate. The effect of the length of the ME laminate on the power output has been also studied, exhibiting a decay as the length of the ME laminate does. Nevertheless, good performance of such device has been obtained for a 0.5 cm long device, working already at 337 KHz, within the low radio frequency (LRF) range.