Allenamide-Initiated Cascade [2+2+2] Annulation Enabling the Divergent Total Synthesis of (-)-Deoxoapodine, (-)-Kopsifoline†D and (±)-Melotenine†A.

A facile method for the construction of the aspidosperma core from indoles functionalized with a nonterminal N-allenamide and dimethyl methylenemalonate is described. Various polysubstituted tetracyclic spiroindolines (27 examples) were afforded in good yields (61-90 %) with >99/1 dr and >99/1 Z/E selectivity under mild conditions. The annulation reaction provides straightforward access to the tetracyclic spiroindoline skeleton with substituents at the C5 position occurring in many natural products. As an application of this reaction, the total synthesis of three important natural products, (-)-deoxoapodine, (-)-kopsifoline D and (±)-melotenine A, was possible in short routes from tryptamine.

Comparison between synthetic and rosemary-based antioxidants for the deep frying of French fries in refined soybean oils evaluated by chemical and non-destructive rapid methods.

Using natural antioxidants instead of synthetics ones has been the tendency for retarding the oil deterioration during repeated deep frying process. Concerning this, the comparison between synthetic tertiarybutyl hydroquinone (TBHQ) and rosemary-based antioxidants in frying French fries was hereby evaluated. The quality and stability of frying oils with rosemary-based antioxidants showed higher efficiency than TBHQ regarding oxidation parameters (i.e., chemical indices, sensory, etc.), where rosmarinic acid (RA) was the most effective, followed by rosemary extracts (RE) and carnosic acid (CA). LF-NMR results were highly correlated (R2 = 0.909-0.998) to the change in physicochemical properties tested, where RA could effectively regulate the relaxation spectrum (T2) change and decrease single component relaxation time (T2W). The PCA graph of NIRS also revealed the dynamic change of antioxidant effectiveness in accordance with that obtained by chemical methods. Hence, both LF-NMR and NIRS can be expected as rapid and efficient methods for future monitoring the frying process.

Visualizing the Transport of Porcine Reproductive and Respiratory Syndrome Virus in Live Cells by Quantum Dots-Based Single Virus Tracking.

Quantum dots (QDs)-based single particle analysis technique enables real-time tracking of the viral infection in live cells with great sensitivity over a long period of time. The porcine reproductive and respiratory syndrome virus (PRRSV) is a small virus with the virion size of 40-60 nm which causes great economic losses to the swine industry worldwide. A clear understanding of the viral infection mechanism is essential for the development of effective antiviral strategies. In this study, we labeled the PRRSV with QDs using the streptavidin-biotin labeling system and monitored the viral infection process in live cells. Our results indicated that the labeling method had negligible effect on viral infectivity. We also observed that prior to the entry, PRRSV vibrated on the plasma membrane, and entered the cells via endosome mediated cell entry pathway. Viruses moved in a slow-fast-slow oscillatory movement pattern and finally accumulated in a perinuclear region of the cell. Our results also showed that once inside the cell, PRRSV moved along the microtubule, microfilament and vimentin cytoskeletal elements. During the transport process, virus particles also made contacts with non-muscle myosin heavy chain II-A (NMHC II-A), visualized as small spheres in cytoplasm. This study can facilitate the application of QDs in virus infection imaging, especially the smaller-sized viruses and provide some novel and important insights into PRRSV infection mechanism.

KCNQ1 loss-of-function mutation impairs gastric acid secretion in mice.

The KCNQ1 channel is abundantly expressed in the gastric parietal cells. Although the functional coupling of KCNQ1 with the H(+)/K(+)-ATPase has already been confirmed on the basis of pharmacological kinetics, the effect of a KCNQ1 loss-of-function mutation on gastric acidification remains unclear. In this study, parietal cells and gastric glands from both C57BL/6 J mice (normal control) and J343 mice (mice with a KCNQ1 loss-of-function mutation) were isolated to study the effects of KCNQ1 on gastric acidification. We found that the mutation limited intracellular acidification of parietal cells and H(+) secretion of the stomach in response to histamine. Thus, a KCNQ1 loss-of-function mutation may impair gastric acid secretion.

Effects of potassium channel blockers on changes in refractoriness of atrial cardiomyocytes induced by stretch.

Shortening of the effective refractory period (ERP) is regarded as one of the key mechanisms of atrial fibrillation (AF). Stretch is an important predisposing factor in the pathogenesis of AF. However, effective methods to counteract alteration of ERP induced by stretch still need to be explored. Although potassium channels play important roles in cardiac repolarization and refractoriness, the effects of potassium channel blockers on the alteration of repolarization and refractoriness induced by stretch are still unknown. Action potential duration (APD) and ERP were recorded using the standard intracellular microelectrode technique in the left atrial appendage cardiomyocytes of guinea pigs. Stretch accelerated repolarization of atrial cardiomyocytes and also shortened the ERP (P < 0.05). Dofetilide, a rapid delayed rectifying potassium ion channel (I(Kr)) blocker; 4-AP, a transient outward potassium ion channel (I(to)) blocker; and BaCl(2), an inward rectifying potassium ion channel (I(K1)) blocker could counteract the shortening of APD and ERP (P < 0.01). Glibenclamide, an ATP-sensitive potassium ion channel (I(KATP)) blocker; 293-B, a slow delayed rectifying potassium channel (I(Ks)) blocker; and DPO-1, an ultra-rapid delayed rectifying potassium ion channel (I(Kur)) blocker all had no effect on APD and ERP (P > 0.05). Stretch could accelerate repolarization of atrial cardiomyocytes and shorten their ERP, and the I(to), I(Kr), and I(K1) blockers could counteract the effects of stretch.

Spatial heterogeneity of muscarinic type 2 receptors in the atrium.

Atrial fibrillation (AF) is the most common arrhythmia in clinical practices. Mediated by muscarinic type 2 receptors (M(2)Rs), acetylcholine affects electrophysiological activities of atrial myocytes and may contribute to the onset of AF. In order to characterize the distribution of M(2)Rs in the atrial myocardium, different atrial regions in both the SD rat and human were dissected. Atrial myocytes were isolated with type II collagenase. The M(2)Rs expression in these atrial tissues and myocytes was detected by immunofluorescent staining and confocal laser scanning biological microscope. The results showed the highest density of M(2)Rs in atrial myocytes of the left atrial posterior wall. It is concluded that there is a marked spatial heterogeneity in the expression of the M(2)Rs in the atrium, which might create a substrate that would favor the initiation and maintenance of acetylcholine-induced AF.