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B J Hering

Publications and source records attributed to B J Hering.

At least 109 records · Page 6Linked to original sources
PubMed1990

Impact of culture and cryopreservation on MHC class II antigen expression in canine and porcine islets.

Canine and porcine islets were either cultured for 10 days at 37 degrees C or cryopreserved. The effect of these treatments on MHC class II antigen expression was examined by indirect immunofluorescence test using the class II monoclonal antibody 2MC3. Within untreated canine islets exclusively round shaped cells as leukocytes and monocyte/macrophage like cells with dendritic branches were positive with 2MC3. Porcine islets additionally exhibited strong immunofluorescence of the vascular endothelium. Tissue culture significantly reduced the class II antigen expression in both species. The majority of the untreated canine islets had between 5 and 19 2MC3 positive cells. Cell culture reduced the number of class II positive cells to a maximum of 3 and even 84.9% of the islets were completely negative for class II antigens. Porcine islets showed a total class II antigen loss of the vascular endothelium, whereas leukocytes and monocytes/macrophages remained class II antigen positive. Cryopreservation did not have clear-cut effects on the MHC expression in both species.

Animals↗
PubMed1990

The evaluation of neutral density separation utilizing Ficoll-sodium diatrizoate and Nycodenz and centrifugal elutriation in the purification of bovine and canine islet preparations.

This study evaluates the potential of a neutral density separation technique using iodinated gradient media in combination with Ficoll or alone at two different densities for the purification of bovine and canine islets isolated by a continuous digestion-filtration technique. In addition, centrifugal elutriation is applied to the purification of isolated bovine islets. A single density layer of Ficoll-sodium diatrizoate or Nycodenz at densities of 1.080 g/ml or 1.085 g/ml resulted in an recovery of 47.4% to 77.4% bovine islet volume with bovine islet purities ranging from 43.5% to 49.0%. The use of a single density layer of Ficoll-sodium diatrizoate at 1.080 g/ml and Nycodenz at 1.085 g/ml resulted in recoveries of 86.4% and 56.2% canine islet volume with canine islet purities of 58% and 63.5%, respectively. The bovine islet enriched fraction (flow rates 50-90 ml/min at a rotor speed of 200 rpm) obtained by centrifugal elutriation was 20.0 +/- 3.5% pure, the average recovery of bovine islet volume obtained by centrifugal elutriation was 59.0 +/- 10.7%. It is suggest that a further refinement of factors like osmolality, viscosity, pH, ionic composition and temperature of iodinated density gradient media may allow continued improvement of islet purity and recovery obtained by the simple neutral density separation technique.

Animals↗
PubMed1989

Bovine islets of Langerhans. Potential source for transplantation?

Two methods are described for large-scale isolation of islets from the bovine pancreas. With the single-endpoint technique the average number of islets isolated from a 73.3-g pancreas sample was 150,560, representing an estimated total islet volume of 0.391 ml. Pancreases processed by the continuous digestion-filtration method yielded an average of 246,229 islets from a 93.9-g pancreas sample, representing an estimated total islet volume of 0.458 ml. Isolated bovine pancreatic islets demonstrated a well-preserved endocrine cell ultrastructure, responded to acute stimulation with propionic acid, and temporarily reversed experimental diabetes in mice.

Animals↗
PubMed1989

[Islands of Langerhans of cattle--potential donor tissue for clinical islet transplantation?].

A standard method for bovine islet isolation has been developed. The mean islet yield per gram pancreas obtained from the last twelve consecutive glands was 2,098 +/- 292 representing an insulin recovery of 36.1 +/- 6.5%. The static incubation of freshly isolated bovine islets in the presence of glucose resulted in a less distinct increase of insulin secretion than in the presence of free fatty acids. Nevertheless, xenotransplantation of bovine islets to immunosuppressed C57BL6J mice did reverse streptozotocin-induced diabetes for 2 to 6 days.

Animals↗
PubMedDate not supplied

Islet isolation assessment in man and large animals.

Recent progress in islet isolation from the pancreas of large mammals including man, accentuated the need for the development of precise and reproducible techniques to assess islet yield. In this report both quantitative and qualitative criteria for islet isolation assessment were discussed, the main topics being the determination of number, volume, purity, morphologic integrity and in vitro and in vivo function tests of the final islet preparations. It has been recommended that dithizone should be used as a specific stain for immediate detection of islet tissue making it possible to estimate both the total number of islets (dividing them into classes of 50 mu diameter range increments) and the purity of the final preparation. Appropriate morphological assessment should include confirmation of islet identification, assessment of the morphological integrity and of the purity of the islet preparation. The use of fluorometric inclusion and exclusion dyes together have been suggested as a viability assay to simultaneously quantitate the proportion of cells that are intact or damaged. Perifusion of islets with glucose provides a dynamic profile of glucose-mediated insulin release and of the ability of the cells to down regulate insulin secretion after the glycemic challenge is interrupted. Although perifusion data provides a useful guide to islet viability the quantity and kinetics of insulin release do not necessarily predict islet performance after implantation. Therefore, the ultimate test of islet viability is their function after transplantation into a diabetic recipient. For this reason, in vivo models of transplantation of an aliquot of the final islet preparation into diabetic nude (athymic) rodents have been suggested. We hope that these general guidelines will be of assistance to standardize the assessment of islet isolations, making it possible to better interpret and compare procedures from different centers.

Animals↗