946 resultados para radical superóxido


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Background: Widespread use of prostate-specific antigen screening has resulted in younger and healthier men being diagnosed with prostate cancer. Their demands and expectations of surgical intervention are much higher and cannot be adequately addressed with the classic trifecta outcome measures. Objective: A new and more comprehensive method for reporting outcomes after radical prostatectomy, the pentafecta, is proposed. Design, setting, and participants: From January 2008 through September 2009, details of 1111 consecutive patients who underwent robot-assisted radical prostatectomy performed by a single surgeon were retrospectively analyzed. Of 626 potent men, 332 who underwent bilateral nerve sparing and who had 1 yr of follow-up were included in the study group. Measurements: In addition to the traditional trifecta outcomes, two perioperative variables were included in the pentafecta: no postoperative complications and negative surgical margins. Patients who attained the trifecta and concurrently the two additional outcomes were considered as having achieved the pentafecta. A logistic regression model was created to evaluate independent factors for achieving the pentafecta. Results and limitations: Continence, potency, biochemical recurrence-free survival, and trifecta rates at 12 mo were 96.4%, 89.8%, 96.4%, and 83.1%, respectively. With regard to the perioperative outcomes, 93.4% had no postoperative complication and 90.7% had negative surgical margins. The pentafecta rate at 12 mo was 70.8%. On multivariable analysis, patient age (p = 0.001) was confirmed as the only factor independently associated with the pentafecta. Conclusions: A more comprehensive approach for reporting prostate surgery outcomes, the pentafecta, is being proposed. We believe that pentafecta outcomes more accurately represent patients` expectations after minimally invasive surgery for prostate cancer. This approach may be beneficial and may be used when counseling patients with clinically localized disease. (C) 2011 European Association of Urology. Published by Elsevier B. V. All rights reserved.

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The kinetics and mechanisms of thermally initiated (using 2,2'-azobisisoburyronitrile (AIBN) as initiator) radical homopolymerizations of a series of maleimides, including N-phenymaleimide (PHMI) [l-phenyl-1H-pyrrole-2,5-dione]; N-n-hexylmaleimide (nHMI) [l-(n-hexyI)-1H-pyrrole-2,5-dione]; and N-cyclohexylmaIeimide (CHMI) [l-cyclohexyl- 1H-pyrrole-2,5-dione] have been investigated in THF solution by an on-line FT-NIR technique. It was found that the order of the activation energies for the three N-sub-MIs is: E-a PHMI < E-a (PHMI) < E-a (CHMI). The overall polymerization rate parameter k and the pre-exponential factor A were calculated. The kinetic order with respect to the N-sub-MIs was in the range of 0.71 < m < 0.75 for the initiator and n = 1.0 for the monomer. Radical transfer to solvent was found to be the key factor in determining the apparent order with respect to the initiator. All of the homopolymers had a relatively low molecular weight. The end groups of the polymer chains were characterized by MALDI-TOF, GPC and NMR methods and the results clearly indicate that the polymerization was initiated by THF radicals, and that the termination reaction is mainly controlled by chain transfer to solvent through an hydrogen abstraction mechanism. (C) 2001 Elsevier Science Ltd. All rights reserved.

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The structure of the product from the free radical bulk copolymerization of methyl methacrylate (MMA) and allyl acetate (AAc) was investigated. The mole fraction of AAc plays an important role in the copolymerization of these two monomers. Molecular weight (MW) and molecular weight distribution (MWD) are completely altered when the feed composition is dominantly AAc. NMR spectroscopy confirmed the incorporation of AAc into the polymer. However, no allyl-allyl linkages were observed at low conversions. T-g was found to be affected by the incorporation of AAc into the polymer. (C) 2001 Society of Chemical Industry.

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The free radical polymerization of styrene in bulk was monitored by ESR and FT near-infrared spectroscopy at 70°C for a series of concentrations of the initiator, dimethyl 2,2′-azobis(isobutyrate). In order to obtain detailed kinetic information over the intire conversion range, and the gel effect range in particular, conversion and free radical concentration data points were accumulated with exceptionally short time intervals. The polystyrene radical concentration ([St•]) went through a sharp maximum at the gel effect, a feature that has hitherto escaped observation due to the rapid concentration changes in the gel effect range relative to the data point time intervals of previous studies. Temperature measurements throughout the polymerization were employed to calculate that a temperature increase was not the cause of the [St•] maximum, which thus appeares to be a genuine feature of the gel effect of this system under isothermal conditions. The propagation rate constant (kp) as a function of monomer conversion exhibited a marked dependence on initiator concentration at high monomer conversion; the sharp decrease in kp with increasing conversion was shifted to higher conversions with increasing initiator concentration.

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The radicals formed on gamma-radiolysis of a series of copolymers of methacrylic acid and acrylonitrile have been investigated by ESR spectroscopy. This series of copolymers spanned the full composition range and the study was carried out at 77 K and ambient temperature. The radicals formed in the copolymers at 77 and 303 K were found to be similar to those found in the two homopolymers, but in the intermediate composition range the presence of acrylonitrile propagation radicals was also detected. These radicals were not observed to be formed in significant quantities on the radiolysis of polyacrylonitrile. They are believed to result from a scission of the main chain at methacrylic acid/acrylonitrile diad sequences following loss of the methacrylic acid carboxyl group. At 77 K, the copolymers with high methacrylic acid contents were found to be more sensitive to radical formation than the methacrylic acid homopolymer, but this enhanced sensitivity was not evident at ambient temperature, where the G-values for radical formation for the copolymers were slightly less than the values for the homopolymers. (C) 2003 Society of Chemical Industry.

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The kinetics of chain reactions of octanedithiol with styrene, thermally initiated with TX29B50 (a 50:50 wt% solution of TX29 diperoxy initiator in a phthalate plasticizer), have been studied over a range of initiator concentrations, a range of mixture formulations and a range of temperatures. This system has been investigated as a model system for the reactions of polyfunctional thiols with divinyl benzene. The reactions have been shown to follow first-order kinetics for both the thiol and the ene species and to be characterized by a dependence on the initiator concentration to the power of one half. The kinetic rate parameters have been shown to adhere to Arrhenius behaviour. A kinetic model for the chain reactions for this system has been proposed. (C) 2003 Society of Chemical Industry.

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O paradigma terapêutico para o CEC do andar inferior da boca sofreu modificações em decorrência da sobrevida. OBJETIVO: Estudo comparativo do esvaziamento cervical radical e seletivo. MATERIAL E MÉTODO: Análise de 460 pacientes atendidos no Depto. de CCP e ORL do Hospital Heliópolis, de 1978 a 2002. Para esvaziamento radical foram avaliados os padrões de metastatização dos níveis IV e V, para o seletivo a ocorrência e localização das recidivas. O método estatístico utilizado foi o teste do qui-quadrado. RESULTADOS: Nos esvaziamentos radicais a taxa de metastatização nos níveis IV e V foram 5,8% e 4,6%, nos pacientes cNO e de 9,9% (nível IV) e 5,9% (nível V) para cN+, enquanto o nível I isolado estava comprometido em 11,0% nos cN0 e 5,5% nos cN+. Nos esvaziamentos seletivos ocorreram 4 recidivas (4,1%) em 97 esvaziamentos nos pN0 e 2 (10,0%) em 20 esvaziamentos. Nos casos pN+, não houve vantagens na indicação de radioterapia sobre os não irradiados (5,6% e 5,7% respectivamente). CONCLUSÃO: É possível realizar esvaziamento seletivo no tratamento das metástases do andar inferior de boca.

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O tratamento do carcinoma da laringe tem como desafio a cura do paciente e a preservação do órgão. OBJETIVO: A avaliação dos subsítios na disseminação do carcinoma e a sua influência no tratamento cirúrgico da laringe, no controle local e na sobrevida. MATERIAL E MÉTODO: Cento e sessenta pacientes tratados na Escola Paulista de Medicina - Hospital São Paulo, no período de janeiro de 1998 a dezembro de 2004, foram compilados para análise da disseminação do carcinoma dos subsítios da laringe. Foram incluídos pacientes com seguimento mínimo de 2 anos, após diagnóstico e tratamento. A avaliação estatística foi: Teste X2, Teste de Fisher e a Curva de Kaplan-Meier. Forma de Estudo: Estudo de Coorte Histórica Longitudinal (Trabalho Clínico Retrospectivo). RESULTADOS: A comissura posterior e a infraglote, respectivamente, foram significantes para a laringectomia total: tumores glóticos AC: (p=0,03) AP: (p=0,0001); AC: (p=0,0007) AP: (p<0,0001). A infraglote foi significante nos tumores G+SG na AP: (p=0,04), e na taxa de óbitos AP: (p=0,03). CONCLUSÃO: A laringectomia total é o tratamento de eleição na presença de alto comprometimento da comissura posterior e da infraglote. Esta última pode comprometer a sobrevida, conforme a invasão local, mesmo na presença de margens cirúrgicas livres.