Postextrasystolic potentiation and dobutamine echocardiography in predicting recovery of myocardial function after coronary bypass revascularization

BACKGROUND: Identification of viable but hibernating myocardium remains a relevant issue in the current era of myocardial revascularization. Echocardiography can be helpful in detecting reversible contractile dysfunction and optimizing the selection of patients for coronary bypass surgery. METHODS AND RESULTS: Eighty-four consecutive candidates for bypass surgery with chronic multivessel coronary artery disease were screened, and 60 were included in this prospective study. Preoperative evaluation of a reversible contractile dysfunction in asynergic myocardial regions was performed by dobutamine infusion at 5 (low dose) and 10 (intermediate dose) microg x kg(-1) x min(-1) with each stage lasting at least 5 minutes; postextrasystolic potentiation (PESP), with a coupling interval ranging from 500 to 300 ms with a progressive 10-ms decrease; or a combination of both dobutamine infusion and PESP. Sensitivity (92% versus 86%) and predictive accuracy (89% versus 84%) were higher with PESP than dobutamine (P=.009 and P=.001, respectively), but the combination did not improve sensitivity or accuracy. Dobutamine induced ischemic dysfunction in 15% of patients at the intermediate dose; however, the low dose resulted in loss of sensitivity. CONCLUSIONS: PESP echocardiography is a useful and cost-effective method to identify viable myocardium in patients with multivessel coronary disease undergoing revascularization and is more sensitive and accurate than dobutamine infusion.     

Cleavage of silicon-carbon bonds and relative rates of hydrolysis of ormosil precursors for optical materials

¹H NMR spectroscopy of methyltrimethoxysilane (MTMS) has revealed that cleavage of the Si—C bond occur during hydrolysis in the presence of HCI. A mechanism is suggested involving nuleophillic attack by CI^? with electrophilic promotion. Optical materials based on tetramethoxysilane (TMOS) and MTMS are vsually transparent and ¹H NMR reveals the similarity of the hydrolysis rates of these precursors under acid catalysis. ¹H NMR indicates that residual unhydrolysed methoxide groups in the finished optical materials are a possibility.     

Application of a Model Based on the Central Limit Theorem to Predict Growth of <Emphasis Type="Italic">Pseudomonas</Emphasis> spp. in Fish Meat

The purpose of this research was to develop an alternative approach to construct a primary model to describe microbial growth. This method was based on the use of the Central Limit Theorem to provide a link between the physiological state of individual cells and the specific growth rate of the population. The resulting model included two parameters that are not usually found in classical models: a logarithmic inflection point, which is related to the exponential phase duration, and a new parameter, alpha, ranging from 0 to 1, which can provide a quantitative measurement of the physiological state of the cells. Once the model was constructed, it was applied to both isothermal and non-isothermal growth of Pseudomonas spp. in fish meat and compared to other models commonly used in the literature. The results showed that the model accurately matched the experimental data and that detailed knowledge of this new parameter can provide new insights into the underlying mechanisms that affect bacterial growth.     

Cardiac involvement in Becker muscular dystrophy

OBJECTIVES: The purpose of this study was to assess the incidence of myocardial involvement and the relation of cardiac disease to the molecular defect at the deoxyribonucleic acid (DNA) or protein level in Becker muscular dystrophy. BACKGROUND: Dystrophin gene mutations produce clinical manifestations of disease in the heart and skeletal muscle of patients with Becker muscular dystrophy. METHODS: Thirty-one patients underwent electrocardiographic and echocardiographic examination and 24-h Holter monitoring. The diagnosis was established by neurologic examination, dystrophin immunohistochemical assays or Western blot on muscle biopsy, or both, and DNA analysis. RESULTS: Electrocardiographic and echocardiographic findings were abnormal in 68% and 62% of the patients, respectively. Right ventricular involvement was detected in 52%. Left ventricular impairment was observed either as an isolated phenomenon (10%) or in association with right ventricular dysfunction (29%). Right ventricular disease was manifested in the teenagers, and an impairment of the left ventricle was observed in older patients. Right ventricular end-diastolic volumes were significantly increased compared with those in a control group. The left ventricular ejection fraction was significantly lower in older patients than in control subjects or younger patients. Life-threatening ventricular arrhythmias were detected in four patients. No correlations were found between skeletal muscle disease, cardiac involvement and dystrophin abnormalities. In our patients, exon 49 deletion was invariably associated with cardiac involvement. Exon 48 deletion was associated with cardiac disease in all but two patients. CONCLUSIONS: The cardiac manifestation of Becker muscular dystrophy is characterized by early right ventricular involvement associated or not with left ventricular impairment. Exon 49 deletion is associated with cardiac disease.     

Comparative effect of different test methodologies on Bacillus coagulans spores inactivation kinetics in tomato pulp under isothermal conditions

Heat resistant micro‐organisms are an ongoing challenge to the food industry. Various factors may influence the heat resistance of micro‐organisms including type and strain; the environmental influences during cell and spore formations and during heat exposure; and the equipment and test tools used to perform the experimental process. In an attempt to analyse the influence of different test tools used on the heat inactivation processes, this study aimed to define the isothermal inactivation kinetics of Bacillus coagulans spores in tomato pulp at different temperatures and compare the inactivation of this bacterium when thermal death time (TDT) and capillary tube methods were used. Temperature ranges from 95 °C to 120 °C were studied, and inactivation kinetic parameters were estimated through the application of primary models. TDT inactivation curves consisted of shoulder and linear decline, while capillary method inactivation curves consisted of shoulder, linear decline and long tail. A secondary model was used to describe the influence of the temperature on spore inactivation parameters. The results showed test methods are at least as important in determining thermal processes as the micro‐organisms and media used.     

Encapsulation of the phenolic compounds of the blackberry (Rubus fruticosus)

Microencapsulated phenolic extracts of blackberry (PE) were obtained by lyophilization in matrixes of β-cyclodextrin (β-CDS), chitosan (C), xanthan (X) and hydrogel (H). The encapsulation was confirmed by Scanning Electron Microscopy (SEM) and Thermogravimetric Analysis (TGA); their antioxidant activity, controlled release of phenolics and efficiency of encapsulation were determined. However, coated chitosan and xanthan only showed the characteristic shape. In fact, encapsulation efficiency depended on the phenolic compound and the encapsulated coating used; gallic acid and epicatechin were predominantly in microcapsules coated with β-cyclodextrin and xanthan. The highest antioxidant activity in microcapsules coated with β-cyclodextrin (84.43 ± 3.5%) and xanthan (90.75 ± 0.09%) was related to the equitable presence of encapsulated phenolic compounds. The controlled release of phenolic extract capsules was influenced by coating, solvent and pH.     

Revisiting the Proposition of Binding Pockets and Bioactive Poses for GSK-3β Allosteric Modulators Addressed to Neurodegenerative Diseases

Glycogen synthase kinase-3 beta (GSK-3β) is an enzyme pertinently linked to neurodegenerative diseases since it is associated with the regulation of key neuropathological features in the central nervous system. Among the different kinds of inhibitors of this kinase, the allosteric ones stand out due to their selective and subtle modulation, lowering the chance of producing side effects. The mechanism of GSK-3β allosteric modulators may be considered still vague in terms of elucidating a well-defined binding pocket and a bioactive pose for them. In this context, we propose to reinvestigate and reinforce such knowledge by the application of an extensive set of in silico methodologies, such as cavity detection, ligand 3D shape analysis and docking (with robust validation of corresponding protocols), and molecular dynamics. The results here obtained were consensually consistent in furnishing new structural data, in particular by providing a solid bioactive pose of one of the most representative GSK-3β allosteric modulators. We further applied this to the prospect for new compounds by ligand-based virtual screening and analyzed the potential of the two obtained virtual hits by quantum chemical calculations. All potential hits achieved will be subsequently tested by in vitro assays in order to validate our approaches as well as to unveil novel chemical entities as GSK-3β allosteric modulators.