Michael Willenborg

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The role of plasma membrane depolarization as a determinant of the initial phase of insulin secretion was investigated. NMRI mouse islets and beta-cells were used to measure the kinetics of insulin secretion, ATP and ADP content, membrane potential, and cytosolic free Ca(2+) concentration ([Ca(2+)](i)). The depolarization of metabolically intact beta-cells(More)
The first phase of glucose-induced insulin secretion is generally regarded to represent the release of a finite pool of secretion-ready granules, triggered by the depolarization-induced influx of Ca2+ through L-type Ca2+ channels. However, the experimental induction of insulin secretion by imposed plasma membrane depolarization may be more complicated than(More)
Depolarization by a high K(+) concentration is a widely used experimental tool to stimulate insulin secretion. The effects occurring after the initial rise in secretion were investigated here. After the initial peak a fast decline occurred, which was followed by a slowly progressive decrease in secretion when a strong K(+) depolarization was used. At 40 mM(More)
The question whether K⁺ depolarization is an appropriate experimental substitute for the physiological nutrient-induced depolarization of the β-cell plasma membrane was investigated using primary mouse β-cells and islets. At basal glucose 40 mM K⁺ induced a massive monophasic response, whereas 15 mM K⁺ had only a minimal insulinotropic effect, even though(More)
Because of state-based regulation, single-state insurers are subject to oversight by a unique, domiciliary regulator (i.e., regulatory integration), whereas in the case of multi-state insurers, regulatory responsibilities are spread across several regulators (i.e., regulatory separation). In this study, the author draws upon recent theoretical literature(More)
This study examines the conditions under which financial restatements lead corporate boards to dismiss independent auditors and how the market responds to those dismissal announcements. We find that auditors are dismissed at higher than normal rates after restatements, but in contrast to prior research on CEO/CFO turnover, we find no evidence of(More)
OBJECTIVE Epidemiological evidence shows that chronic coffee consumption in humans is correlated with a lower incidence of type 2 diabetes mellitus. For the experimental exploration of the underlying mechanisms, this effect needs to be replicated in an animal model of type 2 diabetes with a short lifespan. DESIGN Male C57BL/6 mice consumed regular coffee(More)
We study auditor going-concern opinion decisions around the time of the recent wave of stressed Internet companies filing to go public on Nasdaq. Our objectives are to investigate the veracity of claims of auditor acquiescence at this time and, more generally, to examine auditor decisions during what was arguably an asset pricing 'bubble'. With regard to(More)
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