The effect of okra (Abelmoschus esculentus l.) Powder Addition on Qualities of Gluten-free Chiffon Cake.

Rice flour (100%, 97.4%, 94.7%, 89.5% (w/w)) and okra powder (2.6%-10.5%) were used to replace wheat flour to make gluten-free chiffon cakes. The effects of okra powder addition on the physicochemical, color, texture, moisture content, total phenolic content, antioxidant, and sensory scores of cakes were evaluated. The batter viscosity, chewiness, ash, protein, fat, total phenolics, and antioxidant activities (1,1-diphenyl-z-picrylhydrazyl hydrate and reducing power) of cakes showed an increasing trend with okra powder addition. Gluten-free chiffon cake containing 5.3% okra powder showed significantly (p < 0.05) higher protein and ash contents as compared to their control and chiffon cake made with wheat flour. Nevertheless, center height, volume index, L*, a*, and b* values, and white index of gluten-free cake decreased with increased okra powder levels. The sensory characteristics of wheat and gluten-free chiffon cakes substituted with 2.6%-5.3% okra powder showed no difference (p > 0.05). Nevertheless, the sensory scores of the 5.3% okra powder addition cake obtained a higher preference than other gluten-free cakes. Although the overall acceptability of gluten-free chiffon cake supplemented with 10.5% okra flour had a lower (p < 0.05) overall acceptability (2.84) than all cake samples, it was still shown acceptable to consumers. Gluten-free rice chiffon cakes with high nutrient contents and antioxidant activities can be processed by the incorporation of okra powder of less than 10.5% to increase the diversification of gluten-free foods. Gluten-free cakes with high amounts of okra powder addition would produce cake having high water content, total phenol content, 1,1-diphenyl-z-picrylhydrazyl hydrate radical scavenging activity, reducing power, hardness, chewiness, cohesiveness, batter viscosity, ash, and crude protein content through principal component analysis.

Atmospheric oxidation of fluoroalcohols initiated by ˙OH radicals in the presence of water and mineral dusts: mechanism, kinetics, and risk assessment.

The transport and formation of fluorinated compounds are greatly significant due to their possible environmental risks. In this work, the ˙OH-mediated degradation of CF3CF2CF2CH2OH and CF3CHFCF2CH2OH in the presence of O2/NO/NO2 was studied by using density functional theory and the direct kinetic method. The formation mechanisms of perfluorocarboxylic/hydroperfluorocarboxylic acids (PFCAs/H-PFCAs), which were produced from the reactions of α-hydroxyperoxy radicals with NO/NO2 and the ensuing oxidation of α-hydroxyalkoxy radicals, were clarified and discussed. The roles of water and silica particles in the rate constants and ˙OH reaction mechanism with fluoroalcohols were investigated theoretically. The results showed that water and silica particles do not alter the reaction mechanism but obviously change the kinetic properties. Water could retard fluoroalcohol degradation by decreasing the rate constants by 3-5 orders of magnitude. However, the heterogeneous ˙OH-rate coefficients on the silica particle surfaces, including H4SiO4, H6Si2O7, and H12Si6O18, are larger than that of the naked reaction by 1.20-24.50 times. This finding suggested that these heterogeneous reactions may be responsible for the atmospheric loss of fluoroalcohols and the burden of PFCAs. In addition, fluoroalcohols could be exothermically trapped by H12Si6O18, H6Si2O7, and H4SiO4, in which the chemisorption on H12Si6O18 is stronger than that on H6Si2O7 or H4SiO4. The global warming potentials and radiative forcing of CF3CF2CF2CH2OH/CF3CHFCF2CH2OH were calculated to assess their contributions to the greenhouse effect. The toxicities of individual species were also estimated via the ECOSAR program and experimental measurements. This work enhances the understanding of the environmental formation of PFCAs and the transformation of fluoroalcohols.

Inhibitory Effects of Cyclopiazonic Acid on the Pacemaker Current in Sinoatrial Nodal Cells.

OBJECTIVE: The spontaneous action potential of isolated sinoatrial node (SAN) cells is regulated by a coupled-clock system of two clocks: the calcium clock and membrane clock. However, it remains unclear whether calcium clock inhibitors have a direct effect on the membrane clock. The purpose of this study was to investigate the direct effect of cyclopiazonic acid (CPA), a selective calcium clock inhibitor, on the function of the membrane clock of SAN cells. METHODS: at SAN cells were isolated by trypsinization and identified based on morphology and electrophysiology. If and HCN currents were recorded via patch clamp technique. The expression of the HCN channel protein was determined by Western blotting analysis. RESULTS: The diastolic depolarization rate of spontaneous action potentials and the current densities of If were reduced by exposure to 10 µM CPA. The inhibitory effect of CPA was concentration-dependent with an IC50 value of 16.3 µM and a Hill coefficient of 0.98. The effect of CPA on If current was also time-dependent, and the If current amplitude was partially restored after washout. Furthermore, the steady-state activation curve of the If current was shifted to a negative potential, indicating that channel activation slowed down. Finally, the protein expression of HCN4 in HEK293 cells was markedly downregulated by CPA. CONCLUSIONS: These results indicate that the direct inhibition effect of CPA on the If current in SAN cells is both concentration- and time-dependent. The underlying mechanisms may involve slowing down steady-state activation and the downregulation of pacemaker channel protein expression.

TGFß1 and HGF regulate CTGF expression in human atrial fibroblasts and are involved in atrial remodelling in patients with rheumatic heart disease.

OBJECTIVE: This study aimed to investigate the effects of transforming growth factor ß1 (TGF ß1) and hepatocyte growth factor (HGF) on the expression of connective tissue growth factor (CTGF) in human atrial fibroblasts, and to explore the relationship of these factors in atrial fibrosis and atrial anatomical remodelling (AAR) of patients with atrial fibrillation (AF). METHODS: Fresh right auricular appendix tissue of 20 patients with rheumatic heart disease undergoing valve replacement surgery was collected during surgeries, 10 patients had sinus rhythm(SR), and 10 patients had chronic atrial fibrillation (CAF). Atrial fibroblasts were then cultured from the tissues with differential attachment technique and treated with either TGFß1 (10 ng/mL) or HGF (100 ng/mL). CTGF mRNA levels were measured by RT-PCR, and CTGF protein content was determined using immunofluorescence and Western blotting assays. RESULTS: CAF group had higher left atrial diameters (LADs) and higher CTGF mRNA expression in atrial fibroblasts compared with SR group. The CTGF protein content in CAF group was higher than that of SR group and positively correlated with LAD and AF duration. After CAF group was treated with TGFß1, CTGF mRNA and protein expression were significantly down-regulated, whereas when treated with HGF, expression was up-regulated compared with SR group. CONCLUSIONS: Increased CTGF expression was associated with enlarged LAD, atrial fibrosis and AAR in patients with AF. TGFß1 and HGF regulate CTGF expression in human atrial fibroblasts with up-regulation of mRNA and down-regulation of protein, therefore, either promote or inhibit atrial fibrosis, which could be related to the incidence and persistence of AF.

[Effect of neurotrophin p75 receptor activation on transmural dispersion repolarization in rabbits with myocardial infarction].

OBJECTIVE: To elucidate the effect of neurotrophin p75 receptor (p75NTR)on transmural dispersion repolarization (TDR) of the layers of left ventricular myocytes in rabbits with myocardial infarction (MI). METHODS: Forty Japanese rabbits were divided into four groups (n = 10): (1) Sham group, (2) Heald myocardial infarction (HMI) group, (3) p75 NTR activation group, (4) p75 NTR inhibition group. Cardiomyocytes were isolated with enzyme digestion and the currents were recorded by whole-cell patch-clamp technique. RESULTS: Compared with those in the sham group, the duration of 90% action potential repolarization (APD90) and transmural dispersion repolarization of three layers of left ventricular myocytes were obviously raised (P < 0.05). But significant reduction was observed in p75NTR(-) group. Current densities of Ito and I(Ks, tail) in the p75NTR(+) group and HMI group were significantly reduced (P < 0.05), especially in mid myocytes. And no obvious changes were observed in p75NTR(-) group. CONCLUSION: Activation of p75NTR(+) increases transmural dispersion repolarization, which may lead to the incidence of arrhythmia.

Effects of nerve growth factor on the action potential duration and repolarizing currents in a rabbit model of myocardial infarction.

OBJECTIVES: To investigate the effect of nerve growth factor (NGF) on the action potential and potassium currents of non-infarcted myocardium in the myocardial infarcted rabbit model. METHODS: Rabbits with occlusion of the left anterior descending coronary artery were prepared and allowed to recover for eight weeks (healed myocardial infarction, HMI). During ligation surgery of the left coronary artery, a polyethylene tube was placed near the left stellate ganglion in the subcutis of the neck for the purpose of administering NGF 400 U/d for eight weeks (HMI + NGF group). Cardiomyocytes were isolated from regions of the non-infarcted left ventricular wall and the action potentials and ion currents in these cells were recorded using whole-cell patch clamps. RESULTS: Compared with HMI and control cardiomyocytes, significant prolongation of APD50 or APD90 (Action potential duration (APD) measured at 50% and 90% of repolarization) in HMI + NGF cardiomyocytes was found. The results showed that the 4-aminopyridine sensitive transient outward potassium current (I to), the rapidly activated omponent of delayed rectifier potassium current (I Kr), the slowly activated component of delayed rectifier potassium current (I Ks), and the L-type calcium current (I CaL) were significantly altered in NGF + HMI cardiomyocytes compared with HMI and control cells. CONCLUSIONS: Our results suggest that NGF treatment significantly prolongs APD in HMI cardiomyocytes and that a decrease in outward potassium currents and an increase of inward Ca(2+) current are likely the underlying mechanism of action.

[Age-related changes in transient outward potassium current of rat ventricular myocyte].

The study aimed to investigate the age-related changes and drug reactions of transient outward potassium current (Ito) of ventricular myocytes. Twenty-eight Sprague Dawley rats were divided into young (3-5 months), adult (13-15 months) and aged (22-24 months) groups, and Ito currents of isolated myocytes from each group were recorded respectively by patch-clamp. The perfusion of 2.0 mmol/L 4-AP or 1.0 µmol/L isoproterenol was added respectively in each group, and the changes of Ito were observed. In comparison with young and adult groups, Ito densities of ventricular myocytes in aged group was significantly increased, the curve of steady-state activation of Ito shifted to the left, the close-state inactivation rate significantly decreased, and recovery rate from the steady-state inactivation became quicker. However, no significant changes could be detected for the Ito steady-state inactivation of ventricular myocytes in aged group. The similar responsiveness to 4-AP was observed in all three groups, but the responsiveness to isoproterenol was weaker in the aged group (55.9%) than in the other two groups (127.5% and 125.8%). In conclusion, the results show that Ito of rat ventricular myocyte of aging heart has increased current density and decreased response to isoproterenol.

Frequency- and state-dependent blockade of human ether-a-go-go-related gene K+ channel by arecoline hydrobromide.

BACKGROUND: The rapidly activating delayed rectifier potassium current (I(Kr)), whose pore-forming alpha subunit is encoded by the human ether-a-go-go-related gene (hERG), is a key contributor to the third phase of action potential repolarization. The aim of this study was to investigate the effect and mechanism of arecoline hydrobromide induced inhibition of hERG K(+) current (I(hERG)). METHODS: Transient transfection of hERG channel cDNA plasmid pcDNA3.1 into the cultured HEK293 cells was performed using Lipofectamine. A standard whole-cell patch-clamp technique was used to record the I(hERG) before and after the exposure to arecoline. RESULTS: Arecoline decreased the amplitude and the density of the I(hERG) in a concentration-dependent manner (IC(50) = 9.55 mmol/L). At test potential of +60 mV, the magnitude of I(hERG) tail at test pulse of -40 mV was reduced from (151.7 ± 6.2) pA/pF to (84.4 ± 7.6) pA/pF (P < 0.01, n = 20) and the magnitude of I(hERG) tail at test pulse of -110 mV was reduced from (-187.5 ± 9.8) pA/pF to (-97.6 ± 12.6) pA/pF (P < 0.01, n = 20). The blockade of arecoline in the open and inactivated state was significant in a state-dependent manner. The maximal blockade was achieved in the inactivated state. Studies of gating mechanism showed that the steady-state activation curve of I(hERG) was significantly negatively shifted by arecoline. Time constants of activation were shortened. Steady-state inactivation curve and time constants of fast inactivation were not significantly affected by arecoline. Furthermore, the inhibition of I(hERG) by arecoline was characterized markedly by a frequency-dependent manner from 0.03 to 1.00 Hz pulse. CONCLUSION: Arecoline could potently block I(hERG) in both frequency and state-dependent manner.

Hyperpolarization activated cation current (I(f)) in cardiac myocytes from pulmonary vein sleeves in the canine with atrial fibrillation.

OBJECTIVE: To investigate the characteristics of ectopic automaticity and cation current (I(f)) of cardiac myocytes from pulmonary vein sleeves (PVs) in canines with atrial fibrillation. METHODS: The canines (8-10 years old) were subjected to long-term, rapid atrial pacing (RAP) for 10 weeks, which induced the atrial fibrillation model. Disassociation of PVs of canines yielded single cardiac myocytes from a Landengorff column. Action potential, I(f) and hyperpolarisation activated cyclic nucleotide-gated (HCN) currents were measured with the patch-clamp technique. RESULTS: Compared with the control group, cardiac myocytes from the RAP canine PVs had spontaneous diastolic depolarization, shorter action potential duration, and larger I(f) densities. In the group of RAP cells, the half maximal activation potential (V(1/2)) was found to be less negative (-105.5 ± 5.2 mV) compared to control cells (-87.3 ± 4.9 mV). Current densities of I(f) were increased significantly by ß-adrenergic receptor stimulation with isoproterenol and caused an acceleration of current activation. In contrast, I(f) currents in the RAP were reduced by carvedilol, a selective beta-adrenergic receptor. Another important finding is that HCN4-based channels may make a significant contribution to I(f) in PVs cells, but not HCN2. Meanwhile, HCN4 current significantly increases in canine PVs cardiac myocytes with RAP. CONCLUSIONS: The spontaneous action potential and larger I(f) current were observed in the PVs cardiac myocytes using RAP, which may contribute to more ectopic activity events to trigger and maintain atrial fibrillation.

[Study on residue analysis method of imidacloprid in Ephedrae sinica].

OBJECTIVE: To establish residue analysis method of imidacloprid in Ephedra sinica by HPLC. METHOD: Imidacloprid was extracted with dichloromethane, cleaned up with chromatography column, then separated on Spherisorb C18 column by using Methanol-water (20:80), detected at 270 nm. RESULT AND CONCLUSION: The limit of detection (LOD) and limit quantification (LOQ) were 0.4 x 10(-9) g and 0.02 mg x kg(-1), mean recovery and related standard deviation (RSD) were 85.37%-90.65% and 2.23%-3.45%. It is concluded that the method could satisfy the pesticide residue analysis demands in sensitivity, accuracy and precision.