[The education system for pharmacists in the GDR--a basis for discussion and further implementation].
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Education, Pharmacy↗
Biomedical subjects
H J Hahn
Publications and source records attributed to H J Hahn.
[Quantitative immunohistochemical studies of insulin and glucagon cells of the fetal rat pancreas before and after cryopreservation].
Fetal pancreas obtained at a gestational age of 19.5 days were morphologically investigated before and after cryopreservation. The relative B-cell and A-cell volume density was determined on immunohistochemically stained section by point sampling.
Animals↗
Is the DNA synthesis of pancreatic islets influenced by the MHC and/or the genetic background?
Neonatal pancreatic rat islets were used to investigate the effect of MHC haplotype RT1u on islet replication measured by incorporation of 3H-thymidine and autoradiography. The special interest in RT1u resulted from the fact that BB rats, which develop an insulin-dependent diabetes, belong to the RT1u haplotype. Thus, the RT1u, when influencing the replication, may be involved in the development of the B-cell deficiency observed in diabetic rats. The incorporation of labeled thymidine into islets obtained from rat strains carrying the RT1u or RTIa haplotype revealed no differences. No matter whether the islets were isolated from Lewis, Wistar, or BB rats, no alteration of islet replication by RT1u islets was found. However, islets obtained from Wistar rats had a higher replicatory activity than islets from Lewis rats. This finding was confirmed by a decrease in DNA synthesis of BB rat islets, in which the Wistar background was substituted by the Lewis background. We conclude from our results that MHC has no influence on islet replication, whereas genetic background seems to be involved in the regulation of islet DNA synthesis.
Animals↗
Neuron-specific enolase (NSE) as a neuroendocrine cell marker in the human fetal pancreas.
Using the PAP technique, we investigated the presence of neuron-specific enolase in the human fetal pancreas of 10, 12, and 14 weeks of gestational age. Neuron-specific enolase is present in the islet cells in the 10th week. Positive cells are situated mainly in duct epithelium. The number of cells with a positive reaction increases from the 12th to the 14th week. In the 14th week, they are clustered either near the ducts or between the acini. The numbers and localizations of the cells correspond to those obtained in previous studies with 4 basic islet cell types in the same material. The present results are a further proof that islet cells are biologically active during early fetal development.
Biomarkers↗
Early enhanced beta cell replication in normoglycaemic Wistar rats in response to a subdiabetogenic dose of streptozotocin.
The effect of a single subdiabetogenic dose of streptozotocin (30 mg/kg body weight) on pancreatic insulin content and relative beta cell volume has been studied in normoglycaemic Wistar rats treated with streptozotocin either 2, 3 or 14 days after STZ was given. A single intravenous injection of streptozotocin caused a significant reduction of pancreatic insulin content, islet and beta cell volume, accompanied by a significantly diminished islet insulin content. The glucose- and 3-isobutyl-1-methylxanthine-stimulated insulin secretion was significantly lower in islets obtained 2 or 3 days after streptozotocin injection compared with those of vehicle-treated controls. 14 days after streptozotocin injection, beta cell volume and pancreatic insulin content partially recovered. At this time islet insulin content and secretory responsiveness were enhanced compared to the early phase following streptozotocin administration. The incorporation of [3H] thymidine into islet DNA was significantly enhanced at day 2 or 3 after streptozotocin application, whereas at day 14 the DNA synthesis corresponded to values from control rats. Despite persisting normoglycaemia, the beta cell volume of streptozotocin-treated rats was only 52% vs. control values, thus indicating the unresponsiveness of residual beta cells to compensate spontaneously for the beta cell loss.
Animals↗
Ciamexone suppressed anti-islet ADCC of mononuclear cells and serum from type 1 (insulin-dependent) diabetic patients.
ADCC (Antibody-dependent cellular cytotoxicity) against xenogenic islets has frequently been found in newly diagnosed Type 1 (insulin-dependent) diabetics suggesting that when combined with autologous serum in vitro, the destruction of islet cells caused by mononuclear cells (MNC) reflects islet destruction in vivo. In this study the ability of Ciamexone to suppress the anti-islet ADCC in vitro was investigated. We selected both ADCC positive and ADCC negative subjects from a group of Type 1 diabetics. The targets, islets from neonatal rats, were incubated for one hour with the probands serum. The ADCC was then measured by the 51Cr-release of the serum-treated islets after a 6h-incubation with MNC of the same donor. Results both with and without co-incubation of Ciamexone were compared. Ciamexone does not influence the spontaneous 51Cr-release from neonatal rat islets treated with the probands serum but significantly suppresses the anti-islet ADCC. The fact that Ciamexone suppresses anti-islet ADCC may explain its possible effectiveness in Type 1 diabetes.
Adjuvants, Immunologic↗
The effect of human amniotic fluid on DNA synthesis of rat pancreatic islets in tissue culture.
In this study we investigated the effect of human amniotic fluid (HAF) on the incorporation of 3H-thymidine into cultured rat islets. The addition of 1% HAF (1% HAF, 99% TCM) did not alter the incorporation of labeled thymidine, in comparison to TCM 199 alone (100%). The culture in the presence of 50% HAF (1:1 diluted with TCM, v/v) resulted in a significantly increased DNA synthesis. To exclude any effect of ionic composition or substrate dilution by the HAF, the TCM 199 was also either diluted (1:1) with saline or Hank's balanced salt solution (HBSS). Islets cultured under these conditions did not show any stimulated thymidine incorporation into islet DNA. From these results we conclude that HAF contains an activity which stimulates islet replication. In order to concentrate this stimulatory activity, HAF was tested after it had been lyophilized or evaporated. Independent of the method used, in no case a stimulatory effect of concentrated HAF was found. In contrast, the concentrated form of HAF inhibited the incorporation of labeled thymidine into islet DNA.
Amniotic Fluid↗
Is the cyclosporin A toxicity on rat pancreatic B-cells modulated by the MHC?
High Cyclosporin A doses (50 mg/kg b.w.) were given male Wistar rats either homozygous for RT1a or RT1u. Both rat strains are characterized by a similar diminished body weight gain. Cyclosporin A exerted in both strains an increased fed plasma glucose, decreased glucose tolerance and diminished pancreatic insulin content, however, the Wistar rat strain with the MHC RT1u was more sensitive to the effect of Cyclosporin A, indicated by a more marked alteration of pancreatic B-cells and a delayed recovery after drug withdrawal. We concluded that the MHC modulated either the Cyclosporin A metabolism (degradation) or the pancreatic B-cell sensitivity to toxic damage.
Animals↗
A comparison between insulin and glucagon release from orthotopically-placed islets of Langerhans and after their transplantation into the liver of diabetic rats.
The ability of islets of Langerhans to release insulin (IRI) and glucagon (IRG) after stimulation with glucose and arginine was analyzed by using isolated perfused pancreas of Lewis-rats and by using perfused liver three months after syngenic portal islet transplantation. Transplanted islets preserve their functional integrity so that the shape and magnitude of IRI and IRG release, respectively, can be compared with normal islet reactivity. They are able to release insulin after stimulation with 16 mM glucose having a typical biphasic secretion profile. The islet and B-cell volume, as well as the insulin and glucagon content of the recipient pancreas, are decreased significantly three months after islet transplantation when compared with healthy controls.
Animals↗
3H-thymidine incorporation into islets obtained from prediabetic BB rats.
DNA synthesis, measured as 3H-thymidine incorporation, was estimated in islets obtained from BB rats before the onset of diabetes and compared with the replication rate of islets obtained from age-matched BB rats having never developed hyperglycaemia. Using a biopsy procedure, splenic pancreas was removed from both 65 and from 80 day old diabetes prone BB rats. After isolation by a modified collagenase method pancreatic islets were incubated with labeled thymidine. The animals submitted to biopsy were followed up until they reached an age of 200 days. The diabetes incidence of the BB rats biopsied at day 65 and at day 80 was comparable (35% and 31%). In both groups approximately 140 mg of splenic pancreas were necessary to isolate 70-90 islets, regardless whether the animals become diabetic or not. Using a retrospective experimental design, the thymidine incorporation into islets obtained from prediabetic (rats which developed hyperglycaemia) and from normoglycaemic BB rats were comparatively analysed. The DNA synthesis of pancreatic islets obtained from 65 day old prediabetic BB rats is not different from that measured in islets from normoglycaemic BB rats. A similar replicatory behaviour was also observed using islets from prediabetic and normoglycaemic 80 day old BB rats. From our results we seek to conclude that a prediabetic state is not related to a diminished replicatory activity of pancreatic islets.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Arginine stimulated insulin and glucagon release from islets transplanted into the liver of diabetic rats.
We investigated the ability of intraportal transplanted islets to release insulin and glucagon after stimulation with arginine. Furthermore, the islet volume and hormone content of the recipient pancreas were analyzed. Three months after syngeneic portal islet transplantation the liver of STZ-diabetic rats was perfused in vitro in the presence of different arginine concentrations. Transplanted islets preserve their functional integrity for at least three months indicated by a stimulus adequate insulin release and contribute substantially to the observed amelioration of the diabetic state. The islet and B-cell volume as well as the insulin and glucagon content of the recipient pancreas are still markedly decreased three months after islet transplantation when compared with healthy controls.
Animals↗
Interleukin 2 receptor targeted immunotherapy in the prevention of autoimmune beta-cell destruction as observed in diabetic BB/OK rats grafted with BB/OK rat islets.
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Animals↗
Effect of temporary IL-2 receptor MAB therapy on islet allograft in autoimmune diabetes.
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Animals↗
Streptozotocin-diabetic BB/OK rats accept permanently BB/OK-islet grafts without immunosuppression.
The recurrence of hyperglycaemia after transplantation of BB rat islets in partially inbred BB rats with an autoimmune diabetes could be either caused by graft rejection or by autoimmune destruction. We investigated in the BB/OK rat substrain which does accept BB/OK rat skin grafts permanently, the survival of BB/OK islet grafts by using streptozotocin-diabetic BB/OK rats as recipients. We observed a permanent acceptance of islet grafts despite using animals inbred for only 8 generations. The results demonstrated homogeneity for islet grafts and provide evidence that an autoimmune B-cell destruction cannot be triggered by a direct (toxic effect on immune cells) or indirect (due to B-cell killing) action of a single large doses of streptozotocin in BB/OK rats.
Animals↗
Immunohistochemical, morphometric, and ultrastructural investigations of the early development of insulin, somatostatin, glucagon, and PP cells in foetal human pancreas.
Fresh autopsy specimens of pancreas, taken from 18 human foetuses at the 10th (n = 4), 12th (n = 7), and 14th (n = 7) weeks of gestation, were analyzed immunohistochemically for the presence of islet parenchymal cells, immunoreactive with antisera raised against insulin (B cells), somatostatin (D cells), glucagon (A cells), and pancreatic polypeptide (PP cells). All four islet cell types were found sporadically within or near the epithelium of the small excretory ducts at the 10th week of development. At the 12th week, their presence appeared to be no longer restricted to the duct epithelium, as some B cells were found also in small clusters outside the ducts. At the 14th week of development, the B cells formed large clusters in the neighborhood of the excretory ducts. It is at this stage that the first parenchymal cells with Grimelius argyrophilia could be found. They were supposed to represent A cells. The B cells were found to be the predominating type of islet cells (about 50%) at the 10th week of gestation. The relative volume density was about 25% for the D cells, about 15% for the A cells, and about 10% for the PP cells. At the 12th and 14th weeks of development, the relative numbers of B and PP cells decreased somewhat (to 36 and 6%, respectively), whereas those of the D and A cells were found to increase (to 30 and 27%, respectively). The relative volume density of the total islet parenchyma was about 2, 6, and 21% at the 10th, 12th, and 14th weeks of development, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
Embryonic and Fetal Development↗
Phenotypical characterization of the cells invading pancreatic islets of diabetic BB/OK rats: effect of interleukin 2 receptor-targeted immunotherapy.
We investigated immunohistochemically the phenotypes of mononucleated cells invading pancreatic islets of diabetic BB/OK rats in comparison to the diabetes-resistant parental strain, and 12 and 120 days after a temporary treatment (10 days) with a monoclonal antibody (1 mg/kg b.w.) directed against interleukin 2 receptor (IL 2R) combined with a subtherapeutic dose of cyclosporin A (1.5 mg/kg b.w.). Using a panel of monoclonal antibodies (OX-19, OX-8, W3/25, KI-M2R, OX-6, OX-17, ART-18) and the alkaline phosphatase anti-alkaline phosphatase system to visualize the bound primary antibodies, we observed an even distribution of mononucleated cells across the endocrine pancreas at a "background" level when obtained from diabetes-resistant parental rat strain. Diabetic BB/OK rats, characterized by a moderate hyperglycemia and a marked decrease of pancreatic insulin content, displayed a remarkable accumulation of mononucleated cells in the endocrine pancreas. Morphometric studies revealed an increase of all phenotypes investigated, nearly all mononucleated cells expressed class II histocompatibility antigens (OX-6+, OX-17+) and the number of cells expressing the IL 2R (ART-18+) was markedly enhanced. Sixty-seven percent of the immunotherapeutically treated BB/OK rats normalized plasma glucose and enhanced pancreatic insulin content. The successfully treated animals are characterized by a decrease of cells invading pancreatic islets (OX-19+, OX-8+, W3/25+, KI-M2R+), a decrease of class II histocompatibility antigen and IL 2R expression. The number of IL 2R cells is also diminished in the endocrine pancreas of unsuccessfully treated BB rats.
Animals↗
The endocrine pancreas of BB/OK-rats before and at diagnosis of hyperglycaemia.
From 148 BB-rats 76 animals (51.4%) developed hyperglycaemia within 55th to 178th day of life. Already before diagnosis of diabetes a great variety in pancreatic insulin content and morphometrically determined relative beta-cell volume density were visible. Despite of this great heterogeneity two types in the course of beta-cell destruction could be observed. Verified by individual retrospective analysis one part of the rats is characterized by a more chronical course of diabetes development (pancreatic insulin content and beta-cell mass already more than 60 days before diagnosis of hyperglycaemia significantly reduced, occurrence of insulitis) whereas other animals show an acute form of beta-cell destruction (still about 20 days before diagnosis of diabetes pancreatic insulin content and relative beta-cell volume density in a normal range). Besides a drastical reduction of pancreatic insulin content at the time of diabetes diagnosis intense mononuclear infiltrations in the islets of Langerhans causing their destruction are demonstrable. As a result the residual beta-cell volume is significantly reduced. Rats with a plasma glucose higher than 13 mmol/l at diagnosis do not have any demonstrable beta-cells and an insulin content on the lowest detection limit of the method. In animals with a more mild hyperglycaemia (plasma glucose 8.3 to 13 mmol/l) there are rats with and the other ones without immunohistochemically detectable beta-cells. We conclude that prospective statements on the development of diabetes on the strength of analysis of residual beta-cells and pancreatic insulin content are not possible at present. We suppose that there exist different processes of beta-cell destruction which have to be investigated in further studies including immunological parameters.
Animals↗
Biphasic release of insulin from islets of Langerhans after their transplantation into the liver of rats.
The ability of transplanted islets to release insulin after stimulation with glucose was analysed. Three months after islet transplantation into the liver of diabetic rats the liver was perfused in vitro with different glucose-containing perfusion fluids. Transplanted islets preserve their functional integrity for at least three months and contribute substantially to the observed amelioration of the diabetic state. They are able to release insulin after stimulation with 16 mM glucose with a typical biphasic secretion profile. Insulin containing islets were identified by light microscopy in the tissue of the liver.
Animals↗