d-Allulose Ameliorates Skeletal Muscle Insulin Resistance in High-Fat Diet-Fed Rats

Background: d-Allulose is a rare sugar with antiobesity and antidiabetic activities. However, its direct effect on insulin sensitivity and the underlying mechanism involved are unknown. Objective: This study aimed to investigate the effect of d-allulose on high-fat diet (HFD)-induced insulin resistance using the hyperinsulinemic–euglycemic (HE)-clamp method and intramuscular signaling analysis. Methods: Wistar rats were randomly divided into three dietary groups: chow diet, HFD with 5% cellulose (HFC), and HFD with 5% d-allulose (HFA). After four weeks of feeding, the insulin tolerance test (ITT), intraperitoneal glucose tolerance test (IPGTT), and HE-clamp study were performed. The levels of plasma leptin, adiponectin, and tumor necrosis factor (TNF)-α were measured using the enzyme-linked immunosorbent assay. We analyzed the levels of cell signaling pathway components in the skeletal muscle using Western blotting. Results: d-allulose alleviated the increase in HFD-induced body weight and visceral fat and reduced the area under the curve as per ITT and IPGTT. d-Allulose increased the glucose infusion rate in the two-step HE-clamp test. Consistently, the insulin-induced phosphorylation of serine 307 in the insulin receptor substrate-1 and Akt and expression of glucose transporter 4 (Glut-4) in the muscle were higher in the HFA group than HFC group. Furthermore, d-allulose decreased plasma TNF-α concentration and insulin-induced phosphorylation of stress-activated protein kinase/Jun N-terminal kinase in the muscle and inhibited adiponectin secretion in HFD-fed rats. Conclusions: d-allulose improved HFD-induced insulin resistance in Wistar rats. The reduction of the proinflammatory cytokine production, amelioration of adiponectin secretion, and increase in insulin signaling and Glut-4 expression in the muscle contributed to this effect.     

Proposal of a new optical system for prism-based surface-plasmon-resonance imaging

Optical Review - We propose a new prism-based surface-plasmon-resonance microscope (PB-SPRM) with a diffraction grating. Unlike the conventional PB-SPRM, the proposed one is free from distortion...     

Transition metal-free oxidation of ynamides for synthesis of α-keto-imides

Transition metal-free double oxidation of triple bonds in ynamides for synthesis of α-keto-imides is described. The successful key was combination of NIS and DMSO under atmospheric air in CPME solvent, and the reaction quickly proceeds at 0 °C within 1 h. Although the yields and substrate generality are moderate, yet the prototype protocol avoids the use of expensive, moisture-sensitive, toxic, and explosive additives, which make it potentially and significantly greener than current alternatives.     

Utility of parallel-plate plastometer for rheological study of filled polymer melts

Summary In order to test the applicability of the parallel-plate plastometer to the rheological study of filled polymer melts, viscous properties of polyethylene and polystyrene filled with particles and short fibers were measured by this apparatus. Flow curves in the low range of shear rate were obtained by approximating the materials as Ostwald-de-Waele liquids. Up to about 0.5 of the volume fraction of the filler,, there was no problem and the utility of the apparatus was clearly shown. When increased more, the results were not necessarily self-consistent because the flow became unstable. Experiments on samples with high showed that the unstable flow resulted in an apparent yield stress which agreed with that estimated from the Casson's plots.

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Zusammenfassung Um die Anwendbarkeit des Parallel-Platten-Plastometers für die rheologische Untersuchung von Schmelzen gefüllter Polymerer zu prüfen, wurden mit einem solchen Gerät die viskosen Eigenschaften von Polyäthylen und Polystyrol-Proben gemessen, die mit Teilchen oder kurzen Fasern gefüllt waren. Im Bereich niedriger Schergeschwindigkeiten ließen sich die Fließkurven mit Hilfe der Ostwald-de Waele-Gleichung approximieren. Bis zu einer Füllstoff-Volumenkonzentration von etwa 50% traten keine Komplikationen auf, so daß die Eignung des Geräts für diese Fälle klar erwiesen werden konnte. Wenn jedoch noch weiter gesteigert wurde, waren die Ergebnisse durchweg nicht mehr widerspruchsfrei, da dann der Fließvorgang instabil wurde. Versuche mit hohen Volumenkonzentrationen zeigten, daß die Fließinstabilität eine scheinbare Fließgrenze zur Folge hat, deren Größe mit dem aus einer Casson-Darstellung abgeschätzten Wert in etwa übereinstimmt.

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With 8 figures and 1 table     

Synthesis of 1,3‐Bis(tetracyano‐2‐azulenyl‐3‐butadienyl)azulenes by the [2+2] Cycloaddition–Retroelectrocyclization of 1,3‐Bis(azulenylethynyl)azulenes with Tetracyanoethylene

1,3‐Bis(azulenylethynyl)azulene derivatives 9–14 have been prepared by palladium‐catalyzed alkynylation of 1‐ethynylazulene 8 with 1,3‐diiodoazulene 1 or 1,3‐diethynylazulene 2 with the corresponding haloazulenes 3–7 under Sonogashira–Hagihara conditions. Bis(alkynes) 9–14 reacted with tetracyanoethylene (TCNE) in a formal [2+2] cycloaddition–retroelectrocyclization reaction to afford the corresponding new bis(tetracyanobutadiene)s (bis(TCBDs)) 15–20 in excellent yields. The redox behavior of bis(TCBD)s 15–20 was examined by using CV and differential pulse voltammetry (DPV), which revealed their reversible multistage reduction properties under the electrochemical conditions. Moreover, a significant color change of alkynes 9–14 and TCBDs 15–20 was observed by visible spectroscopy under the electrochemical reduction conditions.     

Fluorogenic aldehydes bearing arylethynyl groups: turn-on aldol reaction sensors for evaluation of organocatalysis in DMSO

Fluorogenic aromatic aldehydes bearing arylethynyl groups were developed. They were used for monitoring the reaction progress of organocatalytic aldol reactions in DMSO through an increase in the fluorescence intensity based on the formation of the florescent aldol product. The ratios of the fluorescence intensities of the aldols to the aldehydes were more than 300. These results suggest that the fluorescence assay system using the aldehyde is useful for the rapid identification of superior aldol catalysts and reaction conditions.     

Regio- and stereoselective hydrohalogenation of ynamide components in 1,3-butadiynes with in situ generated HX

A simple protocol for regio-, and stereoselective hydrohalogenation of ynamide moieties in 1,3-butadiyne structures is described. The facile approach enables exact syn-addition of HX to the diyne components, giving just single isomer of the corresponding dienes and enynes.