Biomedical subjects

F Moussy

Publications and source records attributed to F Moussy.

22 records · Page 2Linked to original sources

PubMed1989

In vitro evaluation of a bioartificial pancreas under various hemodynamic conditions.

A bioartificial pancreas in which isolated islets of Langerhans are placed between two polyacrylonitrile membranes, blood circulating successively above the upper and below the lower membranes following a U-shaped circuit, has been developed. The two parts are connected by an outer loop consisting of a thin tubing. The length of this tubing determines the magnitude of the flow rate of blood through the device. The aim of this work was to determine experimentally the optimal configuration of the system containing isolated rat islets and a Krebs buffer circulating through the device. The amount of insulin released by the bioartificial pancreas was determined during a 20-mM square-wave glucose stimulation. First, the inlet pressure was set at 100 mm Hg, and the effect of the length of the tubing was investigated with two devices perfused simultaneously. For a short tubing (flow rate, 20 ml/min), a sharp increase in insulin release in response to glucose was observed; it increased within 4 min from 217 +/- 50 to 761 +/- 237 microU/500 islets/min (p less than 0.05), the peak value being reached at 11 +/- 2 min following the beginning of the stimulation. For a long tubing (flow rate, 3 ml/min), the increase in insulin release was more sluggish. It increased from 133 +/- 53 to 222 +/- 43 microU/500 islets/min at 4 min, the peak value being reached only at 20 +/- 3 min. These data are consistent with a more efficient diffusional transfer of insulin in the case of the high circulating flow.(ABSTRACT TRUNCATED AT 250 WORDS)

Acrylic Resins↗

PubMed1988

Absence of effect of heparin on insulin secretion.

Bioartificial pancreatic devices containing isolated islets of Langerhans have been designed, in which the blood of the recipient circulates in contact with an artificial membrane, protecting the islets against immune rejection. This system assumes that heparin, required to prevent blood clotting, does not alter insulin secretion. However, heparin has been reported to inhibit in vitro insulin secretion by rat islets and to suppress in vivo insulin secretion in dogs. Therefore, the following evaluation was made on the effect of different heparin preparations on insulin secretion. (a) Isolated rat islets of Langerhans were perfused or incubated in the absence or presence of 20 micrograms/ml heparin; insulin secretion in response to a stimulation by glucose 20 mM was not altered by the presence of heparin. (b) Insulin secretion by an insulin-secreting cell line (RINm5F) in response to leucine and theophylline was not suppressed by heparin up to 100 micrograms/ml concentration. However, an inhibitory effect was observed at 200 micrograms/ml, which is 100 times higher than the heparin concentration commonly used for therapeutic use. (c) Neither in normal rats nor in dogs did heparin alter portal plasma insulin levels and the increase in plasma insulin following an intravenous injection of glucose. In conclusion, these data do not confirm the formerly observed inhibitory effect of heparin, which can therefore be used for the in vivo evaluation of a bioartificial pancreas.

Animals↗

PubMedDate not supplied

Characterization of implantable biosensor membrane biofouling.

The material-tissue interaction that results from sensor implantation is one of the major obstacles in developing viable, long-term implantable biosensors. Strategies useful for the characterization and modification of sensor biocompatibility are widely scattered in the literature, and there are many peripheral studies from which useful information can be gleaned. The current paper reviews strategies suitable for addressing biofouling, one aspect of biosensor biocompatibility. Specifically, this paper addresses the effect of membrane biofouling on sensor sensitivity from the standpoint of glucose transport limitations. Part I discusses the in vivo and in vitro methods used to characterize biofouling and the effects of biofouling on sensor performance, while Part II presents techniques intended to improve biosensor biocompatibility.

Biocompatible Materials↗

PubMedDate not supplied

The force of detachment of endothelial cells from different solid surfaces.

With the use of a technique based on the detachment of single cells by suctioning of the cells with a glass micropipette, the authors studied human endothelial cell adhesion on 4 different surfaces (Fluorocarbon FC 721, polyester, nylon, glass) versus time of contact in phosphate buffered solution and a complete culture medium. It was observed that the force of detachment from solid surfaces of endothelial cells increases significantly with time and with increasing substrate surface tension in PBS and decreasing substrate surface tension in complete culture medium. This dependence of cell-fiber interactions with surface tension of the fibers demonstrates that cell adhesion in the authors' experimental conditions in primarily controlled by surface tension.

Biomechanical Phenomena↗