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H J Hahn

Publications and source records attributed to H J Hahn.

At least 145 records · Page 8Linked to original sources
PubMed1982

Functional and morphological characteristics of isolated pancreatic islets in tissue culture.

Islets were isolated from the pancreas of female rats by using the collagenase technique. After culturing for 4 days, the islets were taken for measurement of insulin release biosynthesis as well as glucose utilization in subsequent short-time incubations. A low glucose concentration was insufficient to maintain a glucose-stimulated insulin release in vitro. A high glucose concentration had a protecting and restoring effect on the insulin release: ultrastructurally, such islets showed signs of an active biosynthesis in the electron micrograph. The enhancement of Mg++ in the culture medium resulted in an improvement of insulin storage in the islets, accompanied by a well-preserved action of glucose in a subsequent incubation.

Animals↗
PubMed1982

The effect of litter size on the development of the endocrine rat pancreas.

The influence of litter size on the development of the endocrine rat pancreas in the fetal period has been investigated. Rats from 3 spontaneously different litter sizes were chosen to estimate sex, body weight, food uptake, pancreatic wet weight, insulin and glucagon concentrations, plasma glucose and insulin. With increasing litter size we could observe an enhancement of the pancreatic insulin concentration whereas the glucagon content was decreased. Food uptake caused an increase of insulin and glucagon in the pancreas. The observed changes were not sex dependent. Our results show that the litter size has an obvious effect on the endocrine pancreas already in the fetal and early neonatal phase of development.

Animals↗
PubMed1982

[Studies into human foetal pancreas--critical appraisal of methods for tissue preparation (author's transl)].

Three different methods of legal abortion were applied to 23 patients, who had asked for termination of pregnancy, between the eleventh and 14th weeks of pregnancy. In vitro studies into human foetal pancreas were taken into consideration, when the choice was made. Carbohydrate tolerance was normal in all cases (50 g oGTT). Timing of intra-uterine foetal death, in the context of the three above methods (B-scan ultrasonic diagnosis and HPL level measurement) as well as studies into in vitro stimulation of foetopancreatic insulin secretion have shown purely mechanical, surgical abortion, sometimes following prostaglandin cervical gel priming, to be indispensable a condition for successful in vitro elucidation of the aetiopathogenesis of foetal diabetes. Extra-amniotic prostaglandin induction of abortion has failed to yield any relevant information, in that context.

Abortion, Induced↗
PubMed1981

[Transplantation of the endocrine pancreas].

The transplantation of the endocrine pancreas has been investigated intensively as one way to optimize the therapy of diabetes mellitus. Starting with the free pancreas transplantation 1966 in diabetics, more recently research has been focused on transplantation of pancreatic islets or fetal pancreatic slices and the segmental pancreas transplantation. These forms of transplantation of the endocrine induced diabetes in various animals. Whereas the transplantation of a dispersed pancreatic preparation (islets or fetal pieces) is not connected with any acute or chronic alternation for the patient, the complication rate of the segmental pancreatic transplantation has to be reduced for a broader clinical application. In the case of islet transplantation the research efforts were concentrated on the improvement of tissue preparation and prolongation of the tissue survival.

Animals↗
PubMed1981

Insulin immunohistochemistry of rodent CNS: apparent species differences but good correlation with radioimmunological data.

Using an indirect immunofluorescence technique the distribution of insulin was mapped in brains of Wistar strain rats and mice. Insulin immunoreactivity was found to be widely distributed throughout mouse CNS, whereas in rat brain a restriction of immunoreactive material to cerebral blood vessels and ependymal cells and/or tanycytes of the brain ventricles was observed. In radioimmunological studies the amount of insulin (IRI) was estimated for different brain areas (cerebral cortex, brain stem, cerebellum, hippocampus, thalamus and hypothalamus). In the case of Wistar rats very low levels of IRI were found. On the contrary, the same regions in mouse brain contained considerably greater amounts of IRI. The comparison between histochemical and biochemical data revealed a good correlation. It is concluded that part of the insulin measured by radioimmunoassay is associated with neuronal structures.

Animals↗
PubMed1981

Immunoreactive glucagon in neurons of various parts of the human brain. Demonstration by immunofluorescence technique.

The presence of glucagon-like immunoreactivity in nerve cells of different parts of the human brain was demonstrated by the indirect immunofluorescence technique. A bright fluorescent reaction was observed in the pyramidal cells of lamina V of the Neocortex. Less prominent concentrations of the glucagon-like material were detected in a few pyramidal cells of the Hippo-campus and in some neurons of the Presubiculum and Subiculum. Within the Corpus amygdaloideum, only a few magnocellular neurons showed a positive reaction. The Hypothalamus was evidenced by a moderate, but widely distributed, reaction in magnocellular and medium-sized nerve cells in different nuclei (especially Nuc. ventromedialis and Nuc. arcuatus). A strong immunofluorescence was localized to some neurocytes in the Nuc. amibigus, and Nuc. n. hypoglassi. The Purkinje cells of the cerebellar cortex were free from immunoreactive material, but fluorescence occurred in some very small nerve cells of the Cerebellum (probably granular cells). A dependence of the strength of immunofluorescence of the time delay between autopsy and death is shown.

Amygdala↗
PubMed1981

[Immunohistochemical evidence of some peptidohormones in the central nervous system of normoglycemic and hyperglycemic rodents (author's transl)].

The content and the distribution of insulin, glucagon and somatostatin were studied in normoglycemic and hyperglycemic rodents by immunohistochemical techniques. A manifest Diabetes mellitus caused a striking decrease in somatostatin immunofluorescence. The insulin content suffered in a less pronounced manner. Data obtained with glucagon did not permit to draw unequivocal conclusions. In general, our findings speak about certain regulatory influence of the brain on glucose homeostasis.

Animals↗
PubMed1981

Effect of glucose on human fetal pancreatic tissue in vitro.

For investigating insulin secretion in vitro human fetal pancreatic slices prepared from women with a normal carbohydrate tolerance at a mean gestational age of 12 +/- 1 weeks were incubated in the presence of various secretagogues. Glucose concentration up to 20 mmol/l failed to enhance insulin secretion, whereas an increase of glucose up to 40 mmol/l, the addition of the phosphodiesterase inhibitor IBMX or a priming period of 30 min in the presence of 20 mmol/l glucose resulted in an enhancement of hormone release, calculated per microgram dry weight. For the first time the results demonstrates an intact secretory machinery of the B-cells under controlled conditions in an early stage of gestational development.

1-Methyl-3-isobutylxanthine↗
PubMed1981

Reversal of diabetes by isogeneic transplantation of cultured pancreatic islets.

Pancreatic islets were isolated by collagenase digestion from female Wistar rats and cultured at 20 mmol/l glucose. The enhancement of Mg++ concentration from 0.8 mmol/l up to 5.3 mmol/l had a protecting effect on the glucose-induced insulin release in the subsequent short-time incubation and prevented the age-depending decrease of B-cell function. About 1,000 cultured islets injected into portal vein normalized the plasma glucose of streptozotocin-diabetic rats. The plasma glucose patterns during the glucose load were nearly identical to healthy controls. These findings suggest that the cultured islets maintain the ability to secrete insulin in response to glucose in vitro as well as in vitro and that such islets can reverse an experimentally induced diabetes.

Animals↗
PubMed1981

[Transplantation register for pancreas and island of Langerhans].

A new registry for human pancreas and islet transplantation has been established (D. E. R. Sutherland). Between 17 December 1966 and 31 December 1980, 108 pancreas transplantations were performed. Six patients had grafts that functioned for more than 12 months. In most of the 68 islet allotransplants performed, little or no evidence of islet function has been obtained. Three diabetic patients were dependent on insulin for 2.5 to 8 months after the operation. One of these, however, still has a functioning graft. Autotransplants of dispersed pancreatic islet tissue have been performed on 59 patients after total or partial pancreatectomy for benign disease. The 28 patients who had 90% pancreatectomies did not require insulin. Information from the registry should be helpful to the various transplant teams attempting clinical application of these procedures.

Diabetes Mellitus↗
PubMed1981

[Islet cell culture as a method of short-term preservation before islet transplantation].

Pancreatic islets were isolated by collagenase digestion of the pancreas from inbred Wistar rats and cultured at 20 mmol/l glucose and 5.3 mmol/l Mg++ for 4 days. About 1,000 cultured islets injected into the portal vein normalized the plasma glucose of severe diabetic rats induced by streptozotocin (45 mg/kg body weight). Spontaneous recovery of streptozotocin-treated rats was not observed in diabetic controls. Although the insulin response of transplanted rats after i.v. glucose injection (5 mmol per kg body weight) was significantly below control animals, the amount of insulin released was obviously sufficient to sustain a persisting normoglycemia of fed animals up to 1 year. The sufficient preservation of insulin content (I) and the rapid depletion of amylase content (A) of collagenase-treated pancreas fragments cultured for 48 h resulted in a significant rise in the I/A ratio. Because islet isolation is associated with islet loss, especially in the human pancreas, the short term culture enhances hopefully the possibilities for successful transplantation.

Animals↗
PubMed1981

Secretion and biosynthesis of (pro)insulin by pancreatic islets isolated from fetuses of normal and diabetic women.

Insulin secretion, biosynthesis and content of isolated pancreatic islets prepared for fetuses of nondiabetic or insulin-dependent diabetic women were investigated in vitro. Glucose failed to stimulate the hormone release during an incubation period of 60 min in islets of fetuses from non-diabetic women. Prolongation of the glucose exposure or the addition of theophylline resulted in a significantly enhanced insulin release. The islets isolated from fetuses of insulin-dependent mothers are glucose-sensitive with respect to hormone release and biosynthesis. The results demonstrated that the human fetal B-cell is glucose-sensitive after glucose exposure. The differences between the islets of fetuses of nondiabetic and diabetic women are discussed as a response to the fetal plasma glucose levels.

Diabetes Mellitus↗
PubMed1980

Calcium and pancreatic beta-cell function. 7. Evidence for cyclic AMP-induced translocation of intracellular calcium.

The effect of cyclic AMP on calcium movements in the pancreatic beta-cell was evaluated using an experimental approach based on in situ labelling of intracellular organelles of ob/ob-mouse islets with 45Ca. Whereas the glucose-stimulated 14Ca incorporation by mitochondria and secretory granules was increased under a condition known to reduce cyclic AMP (starvation), raised levels of this nucleotide (addition of 3-isobutyl-1-methylxanthine or N6,O2'-dibutyryl adenosine 3',5'-cyclic monophosphate) reduced the mitochondrial accumulation of 45Ca. Conditions with increased cyclic AMP were associated with a stimulated efflux of 45Ca from the secretory granules but not from the mitochondria. The microsomal fraction differed from both the mitochondrial and secretory granule fractions by accumulating more 45Ca after the addition of 3-isobutyl-1-methylxanthine. The results suggest that cyclic AMP potentiates glucose-stimulaated insulin release by increasing cytoplasmic Ca2+ at the expense of the calcium taken up by the organelles of the pancreatic beta-cells.

1-Methyl-3-isobutylxanthine↗