Cationic and secretory response of perifused rat pancreatic islets to ramp increase and fall in D-glucose concentration

info:eu-repo/semantics/nonPublishe

Mathematical modelling of cyclic AMP-Ca2+ interactions in pancreatic islets

A mathematical model is proposed to account for the interactions between Ca2+ and cyclic AMP in the process of glucose-induced insulin release. This model allows simulation of experimental findings such as the glucose-induced accumulation of cyclic AMP in islet cells, the calcium dependency of the latter accumulation, the time course of 45Ca net uptake by the islets exposed to glucose and/or a phosphodiesterase inhibitor, the stimulation of insulin release by glucose, the suppression of such a release by glucose, the suppression of such a release at low extracellular Ca2+ concentration and its amplification by phosphodiesterase inhibitors, the restoration of a significant secretory response to glucose in islets deprived of Ca2+ but exposed to a phosphodiesterase inhibitor, and the usual relationship between 45Ca net uptake and insulin release. All these data refer to studies performed over a 90-min incubation. The model is not suitable however, to simulate the rapid response of the islet cells during the first few minutes that follow a change in the environment of the islets.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

A comparative study of the fit of four different functions to longitudinal data of growth in height of Belgian girls

We have fitted Preece-Baines model 1, double logistic, logistic and Gompertz functions to longitudinal data on the growth in height of 35 Belgian girls, followed from birth to 18·0 years. The Preece-Baines model 1 showed significantly lower residual mean squares than the double logistic function, when fitted to data beyond the age of 1·0 year. The former model was also more robust towards variations in the lower age bound of the subject's data series and always described the adolescent spurt better than the latter. Both models fitted the data badly when measurements before the age of 1·0 year were included, and they usually estimated the point at take-off too early. Over the adolescent cycle only, the logistic function fitted our data slightly better than the Gompertz function, with significantly lower pooled residual mean squares, though a slightly worse performance in the runs-test. © 1980 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted.SCOPUS: ar.jinfo:eu-repo/semantics/publishe