Nuciferine stimulates insulin secretion from beta cells-an in vitro comparison with glibenclamide

Ethnopharmacological relevance

Several Asian plants are known for their anti-diabetic properties and produce alkaloids and flavonoids that may stimulate insulin secretion.

Materials and methods

Using Vietnamese plants (Nelumbo nucifera, Gynostemma pentaphyllum, Smilax glabra, and Stemona tuberosa), we extracted two alkaloids (neotuberostemonine, nuciferine) and four flavonoids (astilbin, engeletin, smitilbin, and 3,5,3′-trihydroxy-7,4′-dimethoxyflavone), and studied their insulin stimulatory effects.

Results

Nuciferine, extracted from Nelumbo nucifera, stimulated both phases of insulin secretion in isolated islets, whereas the other compounds had no effect. The effect of nuciferine was totally abolished by diazoxide and nimodipine, and diminished by protein kinase A and protein kinase C inhibition. Nuciferine and potassium had additive effects on insulin secretion. Nuciferine also stimulated insulin secretion in INS-1E cells at both 3.3 and 16.7 mM glucose concentrations. Compared with glibenclamide, nuciferine had a stronger effect on insulin secretion and less beta-cell toxicity. However, nuciferine did not compete with glibenclamide for binding to the sulfonylurea receptor.

Conclusions

Among several compounds extracted from anti-diabetic plants, nuciferine was found to stimulate insulin secretion by closing potassium-adenosine triphosphate channels, explaining anti-diabetic effects of Nelumbo nucifera.     

Contributions of endosonography in ovarian neoplasms: Report of 3 cases

Ovarian investigations are necessary to answer to two questions Intraoperative explorations play a main part for that decision. Endoscopic sonography could contribute to distinguish benign from malignant lesions. We present three cases of endoscopic sonography of ovarian disease. In each case, endoscopic explorations induced to change usual surgical procedure. The authors suggest that endoscopic sonographic becomes an intraoperative step of ovarian surgery.     

四川省农村地区计划生育网络参与艾滋病预防现状调查

目的:了解四川省农村地区人口计生网络参与艾滋病预防的工作现状,提出在农村地区参与艾滋病预防的策略。方法:2005年10月~2006年3月与14组人口计生工作人员进行访谈,内容为人口计生网络参与艾滋病预防的工作情况;与5组育龄人群进行访谈,内容为艾滋病知识掌握与安全套使用情况。结果:人口计生网络已将艾滋病预防结合到日常工作之中;计划生育技术服务者的艾滋病预防意识和能力不足;育龄人群对安全套使用更多停留在避孕功能上。结论:四川省人口计生网络健全,有利于在农村地区广泛开展艾滋病预防宣传工作,但服务人员工作能力有待提高。应加强预防艾滋病的宣传力度,提高人们对安全套的认识和使用率。     

Mitochondrial sequestration and Ca(2+)-dependent release of cytosolic Zn(2+) loads in cortical neurons

The endogenous divalent cations, Ca(2+) and Zn(2+), are both highly toxic upon excessive glutamate triggered intracellular accumulation. Given apparent parallels in their neurotoxic mechanisms, the present study aimed to explore interactions between these cations, by examining effects of moderate intracellular Zn(2+) loading on responses to subsequent Ca(2+) influx. Cortical cultures were briefly exposed to high-K(+) buffer in the presence or absence of Zn(2+) (50-100 microM), to activate and permit a modestly toxic amount of Zn(2+) to enter through VSCC. After 1 h, the cultures were loaded with fluorescent probes, and 2 h after the Zn(2+) exposure, imaged before and after induction of Ca(2+) entry or addition of other drugs. In Zn(2+) preexposed cultures loaded with the Zn(2+) probe, Newport Green, induction of Ca(2+) entry through either VSCC or NMDA channels induced cytoplasmic release of sequestered Zn(2+). The source of this Ca(2+) dependent intracellular Zn(2+) release appears largely to be mitochondria, as indicated by the ability of the mitochondrial protonophore, FCCP, the mitochondrial uncoupler, dinitrophenol with the K(+) ionophore, valinomycin, or the inducer of mitochondrial permeability transition (mPT), phenylarsine oxide (PAO), to substitute for NMDA in triggering Zn(2+) release. Suggesting functional consequences of mitochondrial Zn(2+) uptake, Zn(2+) preexposures resulted in long-lasting mitochondrial depolarization (assessed with rhodamine 123), and reduced mitochondrial reactive oxygen species generation (assessed with hydroethidine) in response to subsequent NMDA triggered Ca(2+) influx.     

Spatiotemporal analysis of the late ERP responses to deviant stimuli

We used a novel application of principal components analysis (spatiotemporal PCA) to decompose the event-related brain potentials (ERPs) obtained with a dense electrode array, with the purpose of elucidating the late ERP components elicited by deviant stimuli under "attend" and "ignore" conditions. First, a "spatial" PCA was performed to identify a set of scalp distributions (spatial factors or "virtual electrodes") that accounted for the spatial variance in the data set. The data were expressed as spatial factor scores or "virtual ERPs" measured at each of the virtual electrodes. These virtual ERPs were submitted to a "temporal" PCA, yielding a set of temporal factors or "virtual epochs." Statistical analyses of the temporal factor scores found that (1) attended deviant stimuli elicited the P300 and Novelty P3 components, the latter being largest for highly salient nontargets: (2) "ignored" deviants elicited a small Novelty P3, and depending on the primary task, a small P300: and (3) the classical Slow Wave consisted of separate frontal-negative and posterior-positive components.     

Differentiating amodal familiarity from modality-specific memory processes: an ERP study

Distinct event-related potential effects have been related to familiarity and recollection processes underlying recognition memory. Familiarity has been conceptualized as similar either to perceptual priming mechanisms supporting implicit memory or to amodal global-matching processes that should show little sensitivity to perceptual variables. The present experiment manipulated the study modality of words (auditory, visual) that were visually tested for recognition memory. The mid-frontal (300-500 ms) old/new effect often attributed to familiarity was not affected by study modality, so it appears related to an amodal familiarity process. An earlier (176-260 ms) fronto-polar old/new effect was perceptually specific in that it was observed only following visual study. The parietal old/new effect (400-800 ms), often attributed to recollection, was similar following both visual and auditory study. Temporal-spatial PCA clarified the separability of these effects.