954 resultados para Capacitor-clamped three-level inverter
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Includes bibliography
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Epithelial cells play an important role in reparative events. Therefore, therapies that can stimulate the proliferation and metabolism of these cells could accelerate the healing process. To evaluate the effects of low-level laser therapy (LLLT), human keratinocytes were irradiated with an InGaAsP diode laser prototype (LASERTable; 780 ± 3 nm; 40 mW) using 0.5, 1.5, 3, 5, and 7 J/cm2 energy doses. Irradiations were done every 24 h totaling three applications. Evaluation of cell metabolism (MTT assay) showed that LLLT with all energy doses promoted an increase of cell metabolism, being more effective for 0.5, 1.5, and 3 J/cm2. The highest cell counts (Trypan blue assay) were observed with 0.5, 3, and 5 J/cm2. No statistically significant difference for total protein (TP) production was observed and cell morphology analysis by scanning electron microscopy revealed that LLLT did not promote morphological alterations on the keratinocytes. Real-time polymerase chain reaction (qPCR) revealed that LLLT also promoted an increase of type I collagen (Col-I) and vascular endothelial growth factor (VEGF) gene expression, especially for 1.5 J/cm2, but no change on fibroblast growth factor-2 (FGF-2) expression was observed. LLLT at energy doses ranging from 0.5 to 3 J/cm2 promoted the most significant biostimulatory effects on cultured keratinocytes. © 2012 Springer-Verlag London Ltd.
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Background: Past studies have shown that mean values of Interleukin-6 (IL-6) and C-reactive protein (CRP) do not change significantly in COPD patients over a one-year period. However, longer period follow-up studies are still lacking. Thus, the aim of this study is to evaluate plasma CRP and IL-6 concentration over three years in COPD patients and to test the association between these inflammatory mediators and disease outcome markers. Methods: A cohort of 77 outpatients with stable COPD was evaluated at baseline, and 53 (mean FEV1, 56% predicted) were included in the prospective study. We evaluated Interleukin-6 (IL-6), C-reactive protein (CRP), six-minute walking distance (6MWD), and body mass index (BMI) at baseline and after three years. Plasma concentration of IL-6 was measured by high sensitivity ELISA, and CRP was obtained by high sensitivity particle-enhanced immunonephelometry. Results: IL-6 increased significantly after 3 years compared to baseline measurements [0.8 (0.5-1.3) vs 2.4 (1.3-4.4) pg/ml; p < 0.001] and was associated with worse 6MWD performance. In the Cox regression, increased IL-6 at baseline was associated with mortality [Hazard Ratio (95% CI) = 2.68 (0.13, 1.84); p = 0.02]. CRP mean values did not change [5 (1.6-7.9) vs 4.7 (1.7-10) pg/L; p = 0.84], although eleven patients (21%) presented with changes >3 mg/L in CRP after 3 years. Conclusions: The systemic inflammatory process, evaluated by IL-6, seems to be persistent, progressive and associated with mortality and worse physical performance in COPD patients. Trial registration: No.:NCT00605540. © 2013 Ferrari et al; licensee BioMed Central Ltd.
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The aim of the present study was to evaluate the effect of low-level laser therapy (LLLT) on odontoblast-like MDPC-23 cells exposed to carbamide peroxide (CP 0.01 %-2.21 μg/mL of H2O2). The cells were seeded in sterile 24-well plates for 72 h. Eight groups were established according to the exposure or not to the bleaching agents and the laser energy doses tested (0, 4, 10, and 15 J/cm2). After exposing the cells to 0.01 % CP for 1 h, this bleaching solution was replaced by fresh culture medium. The cells were then irradiated (three sections) with a near-infrared diode laser (InGaAsP-780 ± 3 nm, 40 mW), with intervals of 24 h. The 0.01 % CP solution caused statistically significant reductions in cell metabolism and alkaline phosphate (ALP) activity when compared with those of the groups not exposed to the bleaching agent. The LLLT did not modulate cell metabolism; however, the dose of 4 J/cm2 increased the ALP activity. It was concluded that 0.01 % CP reduces the MDPC-23 cell metabolism and ALP activity. The LLLT in the parameters tested did not influence the cell metabolism of the cultured cells; nevertheless, the laser dose of 4 J/cm2 increases the ALP activity in groups both with and without exposure to the bleaching agent. © 2013 Springer-Verlag London.
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This study describes the comparison of three methods for genotyping of Mycobacterium tuberculosis, namely MIRU-VNTR (mycobacterial interspersed repetitive units-variable number of tandem repeats), spoligotyping and, for the first time, MLST (Multilocus Sequence Typing). In order to evaluate the discriminatory power of these methods, a total of 44 M. tuberculosis isolates obtained from sputum specimens of patients from Brazil were genotyped. Among the three methods, MLST showed the lowest discriminatory power compared to the other two techniques. MIRU-VNTR showed better discriminatory power when compared to spoligotyping, however, the combination of both methods provides the greatest level of discrimination and therefore this combination is the most useful genotyping tool to be applied to M. tuberculosis isolates. © 2013 Elsevier B.V.
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A finite element analysis was used to compare the effect of different designs of implant-retained overdentures and fixed full-arch implant-supported prosthesis on stress distribution in edentulous mandible. Four models of an human mandible were constructed. In the OR (O'ring) group, the mandible was restored with an overdenture retained by four unsplinted implants with O'ring attachment; in the BC (bar-clip) -C and BC groups, the mandibles were restored with overdentures retained by four splinted implants with bar-clip anchor associated or not with two distally placed cantilevers, respectively; in the FD (fixed denture) group, the mandible was restored with a fixed full-arch four-implant-supported prosthesis. Models were supported by the masticatory muscles and temporomandibular joints. A 100-N oblique load was applied on the left first molar. Von Mises (σvM), maximum (σmax) and minimum (σmin) principal stresses (in MPa) analyses were obtained. BC-C group exhibited the highest stress values (σvM=398.8, σmax=580.5 and σmin=-455.2) while FD group showed the lowest one (σvM=128.9, σmax=185.9 and σmin=-172.1). Within overdenture groups, the use of unsplinted implants reduced the stress level in the implant/prosthetic components (59.4% for σvM, 66.2% for σmax and 57.7% for σmin versus BC-C group) and supporting tissues (maximum stress reduction of 72% and 79.5% for σmax, and 15.7% and 85.7% for σmin on the cortical and trabecular bones, respectively). Cortical bone exhibited greater stress concentration than the trabecular bone for all groups. The use of fixed implant dentures and removable dentures retained by unsplinted implants to rehabilitate edentulous mandible reduced the stresses in the periimplant bone tissue, mucosa and implant/prosthetic components. © 2013 Elsevier Ltd.
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Low-level laser therapy (LLLT) has been considered as an adjuvant treatment for bisphosphonate-related osteonecrosis, presenting positive clinical outcomes. However, there are no data regarding the effect of LLLT on oral tissue cells exposed to bisphosphonates. This study aimed to evaluate the effects of LLLT on epithelial cells and gingival fibroblasts exposed to a nitrogen-containing bisphosphonate - zoledronic acid (ZA). Cells were seeded in wells of 24-well plates, incubated for 48 h and then exposed to ZA at 5 μM for an additional 48 h. LLLT was performed with a diode laser prototype - LaserTABLE (InGaAsP - 780 nm ± 3 nm, 25 mW), at selected energy doses of 0.5, 1.5, 3, 5, and 7 J cm-2 in three irradiation sessions, every 24 h. Cell metabolism, total protein production, gene expression of vascular endothelial growth factor (VEGF) and collagen type I (Col-I), and cell morphology were evaluated 24 h after the last irradiation. Data were statistically analyzed by Kruskal-Wallis and Mann-Whitney tests at 5% significance. Selected LLLT parameters increased the functions of epithelial cells and gingival fibroblasts treated with ZA. Gene expression of VEGF and Col-I was also increased. Specific parameters of LLLT biostimulated fibroblasts and epithelial cells treated with ZA. Analysis of these in vitro data may explain the positive in vivo effects of LLLT applied to osteonecrosis lesions. © 2013 Astro Ltd.
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Low-level laser therapy (LLLT) has been used for the treatment of dentinal hypersensitivity. However, the specific LLL dose and the response mechanisms of these cells to transdentinal irradiation have not yet been demonstrated. Therefore, this study evaluated the transdentinal effects of different LLL doses on stressed odontoblast-like pulp cells MDPC-23 seeded onto the pulpal side of dentin discs obtained from human third molars. The discs were placed in devices simulating in vitro pulp chambers and the whole set was placed in 24-well plates containing plain culture medium (DMEM). After 24 h incubation, the culture medium was replaced by fresh DMEM supplemented with either 5% (simulating a nutritional stress condition) or 10% fetal bovine serum (FBS). The cells were irradiated with doses of 15 and 25 J cm-2 every 24 h, totaling three applications over three consecutive days. The cells in the control groups were removed from the incubator for the same times as used in their respective experimental groups for irradiation, though without activating the laser source (sham irradiation). After 72 h of the last active or sham irradiation, the cells were evaluated with respect to succinic dehydrogenase (SDH) enzyme production (MTT assay), total protein (TP) expression, alkaline phosphatase (ALP) synthesis, reverse transcriptase polymerase chain reaction (RT-PCR) for collagen type 1 (Col-I) and ALP, and morphology (SEM). For both tests, significantly higher values were obtained for the 25 J cm-2 dose. Regarding SDH production, supplementation of the culture medium with 5% FBS provided better results. For TP and ALP expression, the 25 J cm-2 presented higher values, especially for the 5% FBS concentration (Mann-Whitney p < 0.05). Under the tested conditions, near infrared laser irradiation at 25 J cm -2 caused transdentinal biostimulation of odontoblast-like MDPC-23 cells. © 2013 Astro Ltd.
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It is known that low level laser therapy is able to improve skin flap viability by increasing angiogenesis. However, the mechanism for new blood vessel formation is not completely understood. Here, we investigated the effects of 660 nm and 780 nm lasers at fluences of 30 and 40 J/cm2 on three important mediators activated during angiogenesis. Sixty male Wistar rats were used and randomly divided into five groups with twelve animals each. Groups were distributed as follows: skin flap surgery non-irradiated group as a control; skin flap surgery irradiated with 660 nm laser at a fluence of 30 or 40 J/cm2 and skin flap surgery irradiated with 780 nm laser at a fluence of 30 or 40 J/cm2. The random skin flap was performed measuring 10 × 4 cm, with a plastic sheet interposed between the flap and the donor site. Laser irradiation was performed on 24 points covering the flap and surrounding skin immediately after the surgery and for 7 consecutive days thereafter. Tissues were collected, and the number of vessels, angiogenesis markers (vascular endothelial growth factor, VEGF and hypoxia inducible factor, HIF-1α) and a tissue remodeling marker (matrix metalloproteinase, MMP-2) were analyzed. LLLT increased an angiogenesis, HIF-1α and VEGF expression and decrease MMP-2 activity. These phenomena were dependent on the fluences, and wavelengths used. In this study we showed that LLLT may improve the healing of skin flaps by enhancing the amount of new vessels formed in the tissue. Both 660 nm and 780 nm lasers were able to modulate VEGF secretion, MMP-2 activity and HIF-1α expression in a dose dependent manner. © 2013 Published by Elsevier B.V.
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The aim of this study was to analyze the effect of muscle fatigue in active and inactive young adults on the kinematic and kinetic parameters of normal gait and obstacle crossing. Twenty male subjects were divided into active (10) and inactive (10), based on self-reported physical activity. Participants performed three trials of two tasks (normal gait and obstacle crossing) before and after a fatigue protocol, consisting of repeated sit-to-stand transfers until the instructed pace could no longer be maintained. MANOVAs were used to compare dependent variables with the following factors: physical activity level, fatigue and task. The endurance time in the fatigue protocol was lower for the inactive group. Changes of gait parameters with fatigue, among which increased step width and increased stride speed were the most consistent, were independent of task and physical activity level. These findings indicate that the kinematic and kinetic parameters of gait are affected by muscle fatigue irrespective of the physical activity level of the subjects and type of gait. Inactive individuals used a slightly different strategy than active individuals when crossing an obstacle, independently of muscle fatigue. © 2013.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Tumor response to antineoplastic drugs is not always predictable. This is also true for bladder carcinoma, a highly recurrent neoplasia. Currently, the combination of cisplatin and gemcitabine is well accepted as a standard protocol for treating bladder carcinoma. However, in some cases, this treatment protocol causes harmful side effects. Therefore, we investigated the roles of the genes TP53, RASSF1A (a tumor suppressor gene) and hMLH1 (a gene involved in the mismatch repair pathway) in cell susceptibility to cisplatin/gemcitabine treatment. Two bladder transitional carcinoma cell (TCC) lines, RT4 (wild-type TP53) and 5637 (mutated TP53), were used in this study. First, we evaluated whether the genotoxic potential of cisplatin/gemcitabine was dependent on TP53 status. Then, we evaluated whether the two antineoplastic drugs modulated RASSF1A and hMLH1 expression in the two cell lines. Increased DNA damage was observed in both cell lines after treatment with cisplatin or gemcitabine and with the two drugs simultaneously, as depicted by the comet assay. A lack of RASSF1A expression and hypermethylation of its promoter were observed before and after treatment in both cell lines. On the other hand, hMLH1 downregulation, unrelated to methylation status, was observed in RT4 cells after treatment with cisplatin or with cisplatin and gemcitabine simultaneously (wild-type TP53); in 5637 cells, hMLH1 was upregulated only after treatment with gemcitabine. In conclusion, the three treatment protocols were genotoxic, independent of TP53 status. However, cisplatin was the most effective, causing the highest level of DNA damage in both wild-type and mutated TP53 cells. Gemcitabine was the least genotoxic agent in both cell lines. Furthermore, no relationship was observed between the amount of DNA damage and the level of hMLH1 and RASSF1A expression. Therefore, other alternative pathways might be involved in cisplatin and gemcitabine genotoxicity in these two bladder cancer cell lines.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)