Biomedical subjects

F C Mooren

Publications and source records attributed to F C Mooren.

21 records · Page 2Linked to original sources

PubMed1993

In vitro permeability of PBCA nanoparticles through porcine small intestine.

Peroral nanoparticle-mediated drug absorption was studied using a laser scanning confocal microscope. Additional diffusion studies in side-by-side diffusion cells with radiolabelled polybutylcyanoacrylate (PBCA) nanoparticles were carried out to confirm the results of this study. Fluorescence-labelled PBCA nanoparticles were incubated in vitro in the lumen of freshly excised intestine. Computer-aided optical sectioning of thick samples with dramatically improved resolution and the possibility of rejecting out-of-focus noise enabled tracking of the fluorescence-labelled PBCA nanoparticles in the intestinal tissue after incubation of the particles in freshly excised porcine small intestine. The results of this study suggest that the nanoparticles are absorbed by the surface of the gut wall, creating a high concentration gradient, thereby enhancing the absorption of drugs that may be loaded to the nanoparticles. A significant amount of particles was found in hot (very fluorescent) spots that were assumed to be Peyer's patches. No particles, however, traversed the entire gut wall over a period of 2 to 4 h. These results were confirmed by the diffusion study. No radioactivity permeated through Peyer's-patch-free intestine within 4 h, whereas the amount of radioactivity that was transported through intestine with Peyer's patches during this time was 1.1% of the total amount in the donor chamber.

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PubMedDate not supplied

Non-invasive single cell pH measurements in the isolated perfused pancreas.

1. A new method was developed for non-invasive investigations of intracellular pH (pHi) regulation in different cell types of the isolated perfused pancreas using a confocal laser scanning technique. 2. After removal of the rat pancreas the coeliac artery was cannulated and the splenic segment of the pancreas was perfused with dextran (5%)-Ringer solution at a constant flow rate of 2 mL/min. In a temperature-controlled (37 degrees C) chamber, pH regulation was studied using the pH-sensitive fluorescent dye 2',7'-bis-(2-carboxyethyl)-5-(-6)-carboxyfluorescein (BCECF) with a confocal microscope (MRC-600; Bio-Rad, Hercules, CA, USA). 3. Image analysis permitted the identification and comparison of different cell types with a pHi of 7.26+/-0.1 in acinar cells and of 7.02+/-0.1 in endothelial cells. Increasing PCO2 from 5 to 20% resulted in a rapid decrease in pHi. Omission of sodium from the perfusate resulted in a smooth decline in pHi. Both decreases were found to be fully reversible. Increasing PCO2 under sodium-free conditions also resulted in a drop of pHi that was, however, not fully reversible, suggesting involvement of the Na+/H+ exchanger in the regulation of pHi in the intact organ. 4. The above method completely preserves tissue integrity and, therefore, allows the study of pH regulation in different cell types of the pancreas simultaneously and without interference with their functional arrangement. The technique should be of specific value to investigate experimental disease states of the pancreas.

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PubMedDate not supplied

Hypotonicity-evoked release of organic osmolytes from distal renal cells: systems, signals, and sidedness.

After a detailed description of early cellular, membrane and intracellular events in rat renal medullary collecting duct cells when exposed to hypotonicity, a synopsis on organic osmolyte transport properties, possible trigger mechanisms, and the cellular location of transport pathways is given. From the data currently available on renal and nonrenal cells, it is concluded that hypotonicity-evoked efflux of all organic osmolytes appears to be mediated by transport proteins which share a variety of properties more typical for channels than for carriers. A large diversity seems to exist, however, for the signalling mechanisms. Such diversity allows the cells to regulate the intracellular concentration of different organic osmolytes independently of each other, giving flexibility to the spectrum of osmotic responses. The site of release also varies from cell to cell; here conservation of organic osmolytes for future reuptake or further metabolism appears to be the major determinant.

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