145 resultados para Radical Yields


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Current conventional cross-sectional imaging techniques, such as contrast-enhanced computed tomography and magnetic resonance imaging (MRI), are largely inaccurate in detecting local recurrence after radical prostatectomy. We report on five patients with biochemical recurrence after radical retropubic prostatectomy and pelvic lymph node dissection for whom local recurrence could only be detected with diffusion-weighted (DW) MRI. Prior to DW-MRI, all patients had negative digital rectal examinations, negative or equivocal conventional cross-sectional imaging, and negative bone scans. All suspicious lesions on DW-MRI imaging were histologically proved to be local recurrences of prostate cancer after either transrectal ultrasound-guided or transurethral biopsy. These results should encourage other centres to test our findings.

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There is evidence from retrospective studies that radical cystectomy with extended pelvic lymph node dissection provides better staging and outcomes than limited lymph node dissection. However, the optimal limits of extended lymph node dissection remain unclear. We compared oncological outcomes at 2 cystectomy centers where 2 different extended lymph node dissection templates are practiced to determine whether removing lymphatic tissue up to the inferior mesenteric artery confers an additional survival advantage.

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With the increasing use of laparoscopic and robotic radical cystectomy (RC), there are perceived concerns about the adequacy of lymph node dissection (LND).

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A one-pot procedure for the efficient hydroazidation of alkenes involving hydroboration with catecholborane followed by reaction with benzenesulfonyl azide in the presence of a radical initiator is described. The regioselectivity is controlled by the hydroboration step and corresponds in most cases to an anti-Markovnikov regioselectivity. This procedure is applicable to a wide range of alkenes and gives excellent results with 1,2-disubstituted and trisubstituted alkenes.

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The conversion of alkylboranes to the corresponding alkanes is classically performed via protonolysis of alkylboranes. This simple reaction requires the use of severe reaction conditions, that is, treatment with a carboxylic acid at high temperature (>150 degrees C). We report here a mild radical procedure for the transformation of organoboranes to alkalies. 4-tert-Butylcatechol, a well-established radical inhibitor and antioxidant, is acting as a source of hydrogen atoms. An efficient chain reaction is observed due to the exceptional reactivity of phenoxyl radicals toward alkylboranes. The reaction has been applied to a wide range of organoboron derivatives such as B-alkylcatecholboranes, trialkylboranes, pinacolboronates, and alkylboronic acids. Furthermore, the so far elusive rate constants for the hydrogen transfer between secondary alkyl radical and catechol derivatives have been experimentally determined. Interestingly, they are less than 1 order of magnitude slower than that of tin hydride at 80 degrees C, making catechols particularly attractive for a wide range of transformations involving C-C bond formation.

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An efficient synthetic approach to a symmetrically functionalized tetrathiafulvalene (TTF) derivative with two diamine moieties, 2-[5,6-diamino-4,7-bis(4-pentylphenoxy)-1,3-benzodithiol-2-ylidene]-4,7- bis(4-pentylphenoxy)-1,3-benzodithiole-5,6-diamine (2), is reported. The subsequent Schiff-base reactions of 2 afford large p-conjugated multiple donoracceptor (DA) arrays, for example, the triad 2-[4,9-bis(4-pentylphenoxy)-1,3-dithiolo[4,5-g]quinoxalin-2-ylidene]-4,9 -bis(4-pentylphenoxy)-1,3-dithiolo[4,5-g]quinoxaline (8) and the corresponding tetrabenz[bc,ef,hi,uv]ovalene-fused pentad 1, in good yields and high purity. The novel redox-active nanographene 1 is so far the largest known TTF-functionalized polycyclic aromatic hydrocarbon (PAH) with a well-resolved 1H NMR spectrum. The electrochemically highly amphoteric pentad 1 and triad 8 exhibit various electronically excited charge-transfer states in different oxidation states, thus leading to intense optical intramolecular charge-transfer (ICT) absorbances over a wide spectral range. The chemical and electrochemical oxidations of 1 result in an unprecedented TTF+ radical cation dimerization, thereby leading to the formation of [1+]2 at room temperature in solution due to the stabilizing effect, which arises from strong pp interactions. Moreover, ICT fluorescence is observed with large solvent-dependent Stokes shifts and quantum efficiencies of 0.05 for 1 and 0.035 for 8 in dichloromethane.

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Biochemical relapse after radical prostatectomy occurs in approximately 15-40% of patients within 5 years. Postoperative radiotherapy is the only curative treatment for these patients. After radical prostatectomy, two different strategies can be offered, adjuvant or salvage radiotherapy. Adjuvant radiotherapy is defined as treatment given directly after surgery in the presence of risk factors (R1 resection, pT3) before biochemical relapse occurs. It consists of 60-64 Gy and was shown to increase biochemical relapse-free survival in three randomized controlled trials and to increase overall survival after a median followup of 12.7 years in one of these trials. Salvage radiotherapy, on the other hand, is given upon biochemical relapse and is the preferred option, by many centers as it does not include patients who might be cured by surgery alone. As described in only retrospective studies the dose for salvage radiotherapy ranges from 64 to 72 Gy and is usually dependent on the absence or presence of macroscopic recurrence. Randomized trials are currently investigating the role of adjuvant and salvage radiotherapy. Patients with biochemical relapse after prostatectomy should at the earliest sign of relapse be referred to salvage radiotherapy and should preferably be treated within a clinical trial.