Indiana University

About: Indiana University is a education organization based out in Bloomington, Indiana, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 64480 authors who have published 150058 publications receiving 6392902 citations. The organization is also known as: Indiana University system & indiana.edu.

Temporally resolved catecholamine spikes correspond to single vesicle release from individual chromaffin cells

Abstract: Secretion of catecholamines from single bovine chromaffin cells in culture was elicited by brief pressure ejections from a micropipette containing nicotine, carbamoylcholine, or potassium ions or by mechanical stimulation. Release was monitored electrochemically with a carbon-fiber microelectrode placed adjacent to the cell. Cyclic voltammetry was used to identify secreted species, whereas constant potential amperometry was used for improved temporal resolution (millisecond range) of catecholamine detection. During secretion, brief current spikes were observed, which were shown to be due to detection of catecholamines by electrooxidation. The spikes have the physical characteristics of multimolecular packets of catecholamines released at random times and locations from the surface of the single cell. The half-width of the spikes was found to increase with an increase in cell-electrode spacing. The properties of the catecholamine spikes correlate well with expectations based on secretion from individual storage vesicles. Spikes do not occur in the absence of Ca2+ in the buffer, and the majority of spikes are found to be distributed between 0.2 and 2 picocoulombs, corresponding to 1-10 attomoles of catecholamine detected. The frequency of the spikes increases with the intensity of the stimulus, but the average quantity of catecholamine in each spike is independent of the stimulus. Thus, these measurements represent time-resolved observation of quantal secretion of catecholamines and provide direct evidence for the exocytotic hypothesis.

Entrepreneurial Orientation Theory and Research: Reflections on a Needed Construct:

Abstract: This article introduces the Special Issue of Entrepreneurship Theory and Practice on the topic of Entrepreneurial Orientation (EO). In addition to overviewing the preparation and structure of the S...

Efficacy of Divalproex vs Lithium and Placebo in the Treatment of Mania

Abstract: Objective. —To compare the effectiveness of divalproex sodium with that of lithium and placebo in patients with acute mania. Design. —Randomized, double-blind, parallel-group study of treatment outcomes in patients with manic-depressive illness. Patients. —A total of 179 hospitalized, acutely manic patients meeting the Research Diagnostic Criteria for manic disorder, approximately half of whom had been nonresponsive to lithium previously, were studied at nine university-affiliated hospitals. Interventions. —After a minimum 3-day washout period, random assignment for 21 days to divalproex, lithium, or placebo in a 2:1:2 ratio. Dosage of divalproex and lithium was increased if tolerated to a target concentration of 1041 μmol/L (150 μg/ mL) or 1.5 mmol/L (conventionally expressed as milliequivalents per liter), respectively. Main Outcome Measures. —Primary outcome measures were changes in the Mania Rating scale derived from the Schedule for Affective Disorders and Schizophrenia. Results. —Intent-to-treat analysis for efficacy was based on data from 68, 35, and 73 patients in the divalproex, lithium, and placebo groups, respectively. Groups were initially comparable except that all eight patients with four or more manic episodes in the previous year were in the divalproex group. In 30%, 33%, and 51% of the above groups, treatment was prematurely terminated due to lack of efficacy, with fewer premature terminations from divalproex than placebo (P=.017). The proportions of patients improving at least 50% were higher for divalproex and lithium groups than for the placebo group: 48% for divalproex (P=.004) and 49% for lithium (P=.025) vs 25% for placebo. Divalproex was as effective in rapid-cycling manic patients as in other patients. Conclusions. —Both divalproex and lithium were significantly more effective than placebo in reducing the symptoms of acute mania. The efficacy of divalproex appears to be independent of prior responsiveness to lithium. (JAMA. 1994;271:918-924)