Future potential, phase I: nurse practitioners look at themselves.

Nurse practitioners identified as successful were interviewed to evaluate factors related to the viability of nurse practitioners in the health care system. The interviewees believed they were successful because they provided a nursing dimension of primary care, developed strategies to market themselves and their services, collaborated with physicians who saw them as colleagues, and had certain personality characteristics. In addition, the interviewees suggested strategies to enhance practice and potential nurse practitioner roles. These results suggest further research in two areas: investigation of health care administrators and management to solicit their ideas about the future strategic issues for the development of nurse practitioner roles and a broader, more formal survey of nurse practitioners regarding their success in the marketplace.

Regulation of glucose metabolism in pancreatic islets.

We evaluated the possible role of islet glucokinase in controlling the rate of islet glucose metabolism, and thereby the rate of glucose-induced insulin release. The activities of glucokinase, hexokinase, P-fructokinase, and glyceraldehyde-P dehydrogenase were quantitated in sonicated or isotonically homogenized islet preparations using pyridine nucleotide-dependent fluorometric assays. In sonicates, about 1/4 of the islet glucose phosphorylating activity was due to an enzyme with kinetic properties similar to glucokinase; 3/4 of the activity was due to hexokinase. The procedure for determining islet glucokinase activity was improved by centrifuging isotonic islet homogenates at 12,000 x g. The supernatant fraction was enriched for glucokinase. About 1/2 of the glucose phosphorylating activity in this fraction was due to glucokinase and 1/2 was due to hexokinase. The glucokinase activity in islet homogenates was !23 of the activity of hexokinase, 1/40 of the activity of P-fructokinase, and 1/400 of the activity of glyceraldehyde-P dehydrogenase. Detailed concentration dependency curves of glucose and mannose utilization were also obtained with intact isolated pancreatic rat islets. Glucose and mannose usage in islets was governed by two superimposed hyperbolic systems differing in Km and Vmax. A high Km system (Km for glucose 11 mM and for mannose 21 mM) predominated. A low Km system (Km for glucose 215 and for mannose 530 microM) contributed about 15% to the total activity. The available data with intact islets could be rationalized by the existence of two distinct hexose phosphorylating enzymes with differing capacities and kinetic properties. These enzymes, tentatively identified as glucokinase and hexokinase, could coexist in the same cell or could be distributed among different cell types. The possible physiologic significance of these results is discussed, emphasizing the idea of dual control of glycolysis and insulin release by glucokinase and hexokinase. An earlier proposal that glucokinase serves as glucoreceptor of beta-cells [J. Biol. Chem. 243:2730 (1968)] is greatly strengthened by the present studies.

Pirogliride: an oral hypoglycemic drug which accelerates glucose usage and insulin secretion by islets of Langerhans.

Pirogliride potentiates glucose-induced insulin secretion from isolated islets. This effect is accompanied by a facilitated glucose metabolism. Pirogliride partially prevents the known inhibitory effects of mannoheptulose on glucose-induced secretion and utilization. Pirogliride might be useful not only to probe the underlying mechanism of stimulated insulin secretion but also in the therapy of those diabetics who have an impaired beta-cell responsiveness to glucose.