RESUMO
Oral infectious diseases are epidemiologically associated with stroke. We previously showed that oral Streptococcus mutans with the cnm gene encoding a collagen-binding Cnm protein induced intracerebral hemorrhage (ICH) experimentally and was also associated with cerebral microbleeds (CMBs) in our population-based cohort study. We therefore investigated the roles of cnm-positive Streptococcus mutans in this single hospital-based, observational study that enrolled 100 acute stroke subjects. The cnm gene in Streptococcus mutans isolated from saliva was screened using PCR techniques and its collagen-binding activities examined. CMBs were evaluated on T2* gradient-recalled echo MRI. One subject withdrew informed consent and 99 subjects (63 males) were analyzed, consisting of 67 subjects with ischemic stroke, 5 with transient ischemic attack, and 27 with ICH. Eleven cases showed Streptococcus mutans strains positive for cnm. The presence of cnm-positive Streptococcus mutans was significantly associated with ICH [OR vs. ischemic stroke, 4.5; 95% CI, 1.17-19.1] and increased number of deep CMBs [median (IQR), 3 (2-9) vs. 0 (0-1), p = 0.0002]. In subjects positive for Streptococcus mutans, collagen binding activity was positively correlated with the number of deep CMBs (R(2) = 0.405; p < 0.0001). These results provide further evidence for the key role of oral health in stroke.
Assuntos
Adesinas Bacterianas/genética , Proteínas de Transporte/genética , Hemorragia Cerebral/etiologia , Streptococcus mutans/metabolismo , Adesinas Bacterianas/química , Adesinas Bacterianas/metabolismo , Idoso , Idoso de 80 Anos ou mais , Encéfalo/diagnóstico por imagem , Proteína C-Reativa/análise , Proteínas de Transporte/química , Proteínas de Transporte/metabolismo , Hemorragia Cerebral/diagnóstico por imagem , Estudos de Coortes , Colágeno/química , Colágeno/metabolismo , DNA Bacteriano/metabolismo , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Razão de Chances , Reação em Cadeia da Polimerase , Ligação Proteica , Saliva/microbiologia , Streptococcus mutans/isolamento & purificação , Acidente Vascular Cerebral/microbiologia , Acidente Vascular Cerebral/patologiaRESUMO
The utility and applicability of polyethylene-g-polyacrylic acid-immobilized dimethylaminopyridine (g-DMAP) as a catalyst in a continuous-flow system were investigated for decarboxylative esterification. High catalytic activity toward acylation was provided by g-DMAP containing a flexible grafted-polymer structure. During decarboxylation, carboxylic acids and alcohols were converted cleanly using di-tert-butyl dicarbonate (Boc2O) as a coupling reagent, which reduced by-products. In addition, the use of Boc2O resulted in the formation of tert-butyl esters. These esterifications dramatically reduced the reaction time under continuous-flow conditions, with a residence time of approximately 2â min. This highly efficient esterification procedure will provide more practical industrial applications.
Assuntos
Resinas Acrílicas/química , Carbonatos/química , Polietilenos/química , Piridinas/química , Acilação , Álcoois/química , Ácidos Carboxílicos/química , Catálise , Descarboxilação , Esterificação , Estrutura MolecularRESUMO
A new heterogeneous organocatalyst, graft polymer supported dimethylaminopyridine (g-DMAP), is developed. This catalyst has a flexible structure and comprises DMAP anchored to the polyethylene-graft-polyacrylic acid (PE-g-PAA). It exhibits higher activity than DMAP supported on polystyrene cross-linked with divinylbenzene and can be recovered in batch mode acetylation. The activity and stability of this catalyst allow its application in continuous flow systems. Continuous acetylation proceeds with excellent conversion, and a turnover number of 560 can be achieved using g-DMAP. Parallel fixed bed reactors were used to scale up the synthesis of this continuous flow system. Eight parallel fixed bed reactors displayed excellent conversion.