SynopsisThe grafting of methyl methacrylate (MMA) onto chitin initiated by tributylborane (TBB) was investigated at ordinary temperature. It was found that water was essential to the grafting. No grafting was observed in the usual organic solvents such as n-hexane, tetrahydrofuran, and cyclohexanone. The total conversion and the percentage and efficiency of grafting increased with increasing chitin content. The extent of homopolymer formation also increased with increasing chitin content. The optimum concentrations of TBB and MMA for the grafting were determined. Activation energies were estimated to be about 22.8 and 27.4 kcal/mole for the grafting and homopolymerization, respectively. On the basis of these results the mechanism of the grafting onto chitin was discussed.
ObjectiveTo assess the cerebral blood flow (CBF) in patients with diabetic neuropathic pain, and its changes after duloxetine therapy.MethodsUsing iodine-123-N-isopropyl-p-iodoamphetamine single-photon emission computed tomography (IMP-SPECT), we performed a cross-sectional study of 44 patients with diabetes, and compared CBF in those with (n = 24) and without neuropathic pain (n = 20). In patients with neuropathic pain, we also longitudinally assessed changes in CBF 3 months after treatment with duloxetine.ResultsIMP-SPECT with voxel-based analyses showed a significant increase in cerebral blood flow in the right anterior cingulate cortex and a decrease in the left ventral striatum in patients with neuropathic pain, compared with those without pain. After duloxetine treatment, volume of interest analyses revealed a decrease in cerebral blood flow in the anterior cingulate cortex in patients with significant pain relief but not in non-responders. Furthermore, voxel-based whole brain correlation analyses demonstrated that greater baseline CBF in the anterior cingulate cortex was associated with better pain relief on the numerical rating scale.ConclusionsOur results suggest that the development of neuropathic pain is associated with increased activity in the anterior cingulate cortex, and greater baseline activation of this region may predict treatment responsiveness to pharmacological intervention.Trial registration numberUMIN000017130;Results.
Since Johnson's finding in poly(N-vinylcarbazole) (PVCz)l of a high-energy trap, which he referred to as a second excimer, considerable interest has been aroused in the nature of the high-energy trap and its relationship to the normal low-energy e~c i m e r .~-~ Despite the obvious implication that bulky pendant chromophores, in general, may cause second-excimer-like trap formation, no work along this line has been reported to our knowledge. This might be partially due to the finding of Johnson' and Keyanpour-Rad et al.5 that other carbazole-containing polymers do not afford second excimer emission. This implies that among various vinyl aromatic polymers, only PVCz fulfills the strict geometric requirements for formation of the high-energy trap and subsequent emission.In the present communication we present evidence that polymers having sterically hindered naphthalene chromophores do, in fact, form second-excimer-like high-energy traps in a film and to a lesser extent in fluid solution.The monomer 2-tert-butyl-6-vinyhaphthalene (tBVN), its homopolymer (PtBVN, M, = 79000), and its copolymer with styrene (P(tBVN-co-St), 8 mol % in tBVN content,
The effects of the pendant group structure on intramolecular singlet energy migration and excimer formation in poly(2-naphthylmethyl methacrylate) (PNMMA), poly[l-(2-naphthyl)ethyl methacrylate] (P-1-NEMA), poly[2-(2-naphthyl)ethyl methacrylate] (P-2-NEMA), and poly[3-(2-naphthyl)propyl methacrylate] (P-3-NPMA) were examined by fluorescence quenching experiments in deaerated 2-methyltetrahydrofuran. Introduction of steric hindrance near the naphthalene chromophore (P-1-NEMA) or of a polymethylene bridge between the polymer main chain and the naphthalene chromophore (P-2-NEMA and P-3-NPMA) was found to reduce excimer formation but retard energy migration as well, suggesting that more specific chromophore arrangement along the polymer chain is desirable for selective promotion of energy migration and suppression of excimer formation. In film, these polymers exhibited little monomer emission; extensive emission from excimer (PNMMA, P-2-NEMA, and P-3-NF'MA) or that from a second-excimer-like trap (P-1-NEMA) indicates efficient trapping of excitation energy at these trap sites. The formation of the higher energy trap in P-1-NEMA film is discussed in terms of the conformational constraints, Le., increased chromophore separation and chain rigidity, imposed by the pendant group structure.
Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease that favors the cerebrum and typically occurs in immunosuppressed patients. We herein report the case of a 66-year-old man with PML, idiopathic CD4 + T lymphocytopenia (ICL), and chronic renal failure. Cranial magnetic resonance imaging (MRI) showed a crescent-shaped lesion in the left cerebellum, brainstem, and middle cerebellar peduncle. Although the patient did not present with HIV infection, collagen diseases, or tumors, JC virus DNA was detected in the cerebrospinal fluid. Clinicians should consider PML and ICL in the differential diagnosis if the patient develops progressive ataxia and a crescent-shaped cerebellar lesion on MRI.
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