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Biomedical subjects

H J Hahn

Publications and source records attributed to H J Hahn.

At least 109 records · Page 6Linked to original sources
PubMed1986

[Pancreatic donor operation for islet cell isolation and transplantation].

Preservation of B-cells, following organ collection and cold ischaemia, was defined on 19 donor organs by means of histological tests and testing for insulin content in pancreatic tissue. The degree of preservation declined by 50 per cent after two hours of cold ischaemia. The Velcro technique and uncrushed organ digestion were used for isolation. Islet yield was calculated by determination of insulin levels in isolated tissue (nmol/ml) and in the islet (pmol/islet). The average islet yield was 2 076 islets to one gram pancreas, that is ten per cent of the original amount. Studies conducted into in-vitro insulin secretion from isolated islets have revealed damage to organs due to handling, especially to organs which had undergone extended cold ischaemia.

Adolescent↗
PubMed1986

[Relation between the labeling index and thymidine incorporation in cultured islands of Langerhans of the rat: stimulation of DNA synthesis by EGF-S3].

DNA synthesis and labelling index of isolated neonatal rat islets were investigated during a 4 to 5 culture period in TCM 199 (10 mmol/l glucose) under selected conditions, as change of serum concentration in the medium or addition of a proliferation stimulating fraction. Additionally it should be proved whether the DNA-synthesis of pancreatic islets, measured as [3H]-thymidine incorporation, is representative for the amount of cells during the S-phase (= "growth fraction"). There is a correlation between the incorporation of [3H]-thymidine into the TCA-precipitate and the labelling index of islets determined on HE-stained radioautographs. For this reason and because of being less time-consuming, the measurement of DNA synthesis is a suitable screening method for selection of factors increasing the growth fraction of pancreatic beta-cells. Only the addition of FGF-S3 (growth stimulating raw prepared isolated from bovine brain) during culture caused a significant increase of DNA synthesis and labelling index of the islets. The labelling index of radioautographs stained by immunofluorescence method for insulin did not differ significantly from that determined at HE-stained radioautographs. Insulin secretion and content of the islets were not influenced by the addition of FGF-S3.

Animals↗
PubMed1985

Pregnancy-associated changes in the endocrine pancreas of normoglycaemic streptozotocin-treated Wistar rats.

The effect of pregnancy on pancreatic insulin content and relative B-cell volume has been studied in normoglycaemic Wistar rats treated with streptozotocin 14 days before mating. A single intravenous injection of streptozotocin (30 mg/kg body weight) caused a significant reduction of pancreatic insulin content and B-cell volume. The islet insulin content was 60% of control values. However, pregnancy-associated adaptation was preserved in these streptozotocin-treated animals. Plasma insulin levels, pancreatic insulin and B-cell volume were significantly enhanced compared with non-pregnant rats investigated on the same date. The incorporation of [3H]-thymidine into islets from pregnant rats (day 10.5) was higher than that in islets isolated from non-pregnant animals. After delivery insulin content and B-cell volume returned to pre-pregnant values. Also during a longer period after streptozotocin treatment (156 days), no measurable enhancement of B-cell volume and pancreatic insulin content was observed indicating the unresponsiveness of residual B cells to compensate spontaneously for the loss despite persisting normoglycaemia.

Animals↗
PubMed1985

Insulin recovery in pancreas and host organs of islet grafts.

The method of insulin determination is a useful tool for detecting surviving beta cells in the pancreas of diabetic animals and in organs used as sites of islet graft. Therefore, we have studied the insulin recovery in tissue homogenates. The data show that a high recovery rate of insulin (more than 95%) was reached, when the phosphoric acid-alcoholic tissue extract was stored at -20 degrees C and diluted with RIA buffer immediately before radioimmunoassay. When acid-ethanol supernatants were neutralized the recovery rate was diminished to 73.4 +/- 4.0% in pancreas and to 61.0 +/- 6.2% in liver homogenates, respectively. Glucagon was degraded when diluted extracts were stored at -20 degrees C for different periods of time. The diabetogenic action of streptozotocin (STZ) could be demonstrated for doses ranging between 30 and 55 mg/kg body weight. STZ caused a dose-dependent decrease of pancreatic insulin whereas the glucagon content was significantly enhanced in diabetic animals. The glucagon content was not normalized when normoglycemia was achieved by syngeneic islet transplantation. Insulin extracted from spleen used as a site for transplantation of 900 neonatal rat islets showed a high biological variation ranging from 0.7 to 6.4 nmol insulin per spleen, 10-100% of the content of the equivalent number of freshly isolated islets these animals received.

Animals↗
PubMed1985

[Suitability of specific staining methods for the estimation of beta cell volume in rat pancreas with normal and reduced insulin content].

Investigations were carried out on streptozotocin (SZ)-treated female Wistar rats (single i.v. injection of 30 mg/kg body weight) and control animals with normal pancreatic insulin content. After staining of the pancreatic slices with aldehyde fuchsin (AF), Victoria Blue (Ivic 1959), and FITC-labelled antiserum (indirect), the beta-cell volume was determined with a point sampling method. For control animals, all 3 selected beta-cell specific staining methods are equivalent. After reduction of the pancreatic and the beta-cell insulin content by SZ-treatment the sensitivity of the common histochemical methods is diminished in comparison to the immunofluorescence method. In normoglycemia SZ-treated animals (pancreatic insulin content about 30% of control values) 0.22% AF-stained beta-cells are demonstrable, after IVIC-staining 0.14% beta-cell volume is visible. In hyperglycemic SZ-treated rats (about 6% of pancreatic insulin content of controls) with AF-staining only 0.08% and with IVIC-staining 0.03% beta-cell volume could be measured whereas with fluorescence technique in both SZ treated groups 0.34% beta-cell volume is measurable. The reduction of pancreatic insulin content after the injection of 30 mg/kg SZ is caused by a reduction of the beta-cell volume and a diminution of the insulin content in the remaining beta-cells.

Animals↗
PubMed1985

The effects of subdiabetogenic streptozotocin doses on rat beta cell volume and functions.

The influence of a single i.v. injection of 30 mg/kg streptozotocin (SZ) into female Wistar rats on plasma glucose, pancreatic insulin content, volume and function of the remaining beta-cells has been investigated. 14 days after SZ treatment most animals remained normoglycemic; only about 15% showed permanent hyperglycemia. The pancreatic insulin content in normoglycemic rats was reduced to 30%, whereas in hyperglycemic rats only 6% of control values could be detected. The remaining beta-cell volume was comparable in the two groups, indicating no correlation between pancreatic insulin content and residual beta-cell volume. The glucose- and IBMX-stimulated insulin release of islets isolated from normoglycemic cats 14 days after SZ application was not significantly altered whereas the islets insulin content of SZ treated animals was significantly lowered in comparison to controls.

1-Methyl-3-isobutylxanthine↗
PubMed1985

Morphological investigations in human islets of Langerhans isolated by the Velcro-technic.

The lower yield of viable, isolated islets from one donor pancreas and the immunogenicity are responsible for disappointing results in human islet transplantation. Our preliminary results in the application of Velcro-technic (Lacy, 1982) studied by morphological investigations demonstrate the feasibility of this technic in human islet isolation. If we compare the influence of Velcro-technic with regard to the first step of Velcro-technic, the duct perfusion, we can conclude that A-cell granules, stained by Grimelius, are reduced during the collagenase perfusion. On the other side, we recognized B-cell granules up to 60 min after duct perfusion. Connective tissue is reduced by the isolation technic and absent completely up to the Ficoll separation. The exocrine tissue of the pancreas is damaged continuously, and after Ficoll separation we detected singular acinar cells only. The yield from the used lienal human pancreas were about 80 000 islets. Islets after Ficoll separation, studied by electron microscopic investigation, showed non-damaged A and B cells with granules in the typical manner.

Cell Separation↗
PubMed1985

Effects of islet transplantation on the recipient endocrine pancreas.

Streptozotocin diabetic rats were treated with a syngeneic splenic islet transplantation. 17 weeks later the insulin content and the beta-cell mass were investigated in the host pancreas and compared with untreated diabetic or normal rats. The diabetic animals retained 8% of beta-cells, and 2.5% of insulin content as compared with normal controls. Successfully grafted rats are characterized by an increase of beta-cell volume (420%) and insulin content (2350%) in comparison to untreated diabetic rats. However, a detailed individual analysis revealed a marked differentiation between the animals investigated, the cause of which remains to be clarified.

Animals↗
PubMed1985

The encapsulation of pancreatic islets. Investigation of insulin secretion and content in vitro.

Polyelectrolyte complex capsules from cellulose sulphate can be formed by precipitation in a polycation bath. The application of this new method for encapsulation of pancreatic islets requires investigations whether and to what extent cellulose sulphate injures viability and functionality of the pancreatic islets. Islets cultures in the presence of 2% cellulose sulphate for up to 3 weeks are characterized by unchanged insulin content, secretion and biosynthesis when compared to appropriate controls.

Animals↗
PubMed1984

The in vitro insulin secretion of human fetal pancreatic slices from diabetic and non-diabetic women--a methodical study.

The in vitro insulin secretion of pancreatic slices between the 11th and 15th week of pregnancy of fetuses from non diabetic ( FNDW ) and diabetic women ( FDW ) after incubation in media supplemented with different secretagogues was investigated in order to study the development of diabetic fetopathy during human pregnancy in diabetic women. There was a stimulatory effect on the insulin secretion in FNDW even if glucose alone was used, which became more pronounced if IBMX was added to the incubation medium. The insulin secretion was significantly enhanced in FDW compared to FNDW . This incubation model using fetal pancreatic slices seems to be appropriate for studying the ontogenesis of the human fetal pancreas.

Female↗
PubMed1984

Serum zinc levels in retinitis pigmentosa.

Serum zinc and copper levels were analyzed in 26 retinitis pigmentosa patients and compared with serum zinc levels of a control group. Serum zinc levels were documented to be decreased with a mean concentration of 0.735 +/- 0.167 micrograms/ml (p less than 0.001). Serum copper levels, on the other hand, were found to be increased in retinitis pigmentosa patients with a mean value of 1.261 +/- 0.348 micrograms/ml (p less than 0.001).

Adolescent↗
PubMed1984

Animal model of the insulin-dependent Diabetes mellitus in BB rats: their RT1u homogeneity and prolonged survival of allogeneic skin grafts.

Two substrains of BB rats spontaneously developing the insulin-dependent diabetes-like syndrome were studied. Both the partially inbred BB/K and randombred BB/DK substrains proved RT1u homozygous. Their ancestral WOK stock was shown to be heterogeneous for the RT1u (f = 0.84) and RT1a (f = 0.16) haplotypes. Regarding the H-loci of the RT1 complex, the RT1 haplotype of BB rats seems not to be a recombinant between RT1u and RT1a from the ancestral WOK stock. The generally lowered immune responsiveness of BB recipients to allogeneic skin grafts might be caused by a mutation event at their RT1u haplotype or by some other "major gene(s)" from their genetic background.

Animals↗
PubMed1984

[Effect, on the newborn infant, of carbohydrate metabolism in pregnancy in insulin-dependent diabetics].

The influence of the moment in pregnancy of insulin dependent diabetic women, at which normoglycemia by insulin therapy could be reached, on cord blood insulin concentration and neonatal morbidity was investigated. There is a positive correlation between the moment of normoglycemia (HbA1-values less than or equal to 8.5%) and the insulin concentration and furthermore the incidence of respiratory distress syndrome and macrosomia in the newborn. It is concluded that a tight metabolic control in insulin dependent diabetic women already prior to or early in pregnancy (at least until the 16th week) will be able to decrease the incidence of morbidity in infants of diabetic mothers.

Adult↗
PubMed1984

Brain gastrin/CCK immunoreactivity in sand rat (Psammomys obesus): decrease of number of positive neurons in diabetic animals.

Gastrin/CCK immunoreactivity appears to be widely distributed throughout the mammalian CNS, being most abundant in the cerebral cortex [Vanderhaeghen et al. 1975; Straus et al. 1977; Beinfeld et al. 1981]. Besides its putative role as a co-transmitter in dopaminergic neurotransmission [Hökfelt et al. 1980], cholecystokinin is apparently involved in the central regulation of appetite and satiety [Gibbs et al. 1973; Antin et al. 1975; Parret and Batt 1980; Smith 1980; Smith and Gibbs 1981] Furthermore, it has been shown that the brain concentration of the peptide is decreased in genetically obese mice as compared to non-obese animals [Strauss and Yalow 1979]. The sand rat (Psammomys obesus) is a desert rodent which tends to become diabetic when it is fed with normocaloric diet and restricted in movement [Haines et al. 1965; Hahn et al. 1971]. However, the usefulness of this animal as a paradigm of diabetes is now being revised, since because in its typical expression this metabolic dysfunction appears to be an obesity syndrome [Rice and Robertson 1980]. Therefore, it seems to be necessary to study the distribution of gastrin/CCK-immunoreactive nerve cells in the brain of normal and diabetic (obese) sand rats to get further information about mechanism underlying the development of this form of diabetes.

Animals↗
PubMed1984

[Quantitative-histologic studies of human fetal pancreas from metabolically healthy and insulin-dependent diabetic women].

Human fetal pancreases from nondiabetic (n = 26) and insulin-dependent diabetic women (n = 14) between the 13th and 26th week of pregnancy were investigated morphologically. There was in enhanced islet cell volume in fetuses from diabetic patients compared to those from nondiabetics, mainly caused by nesidioblastosis. This phenomenon could be caused by the metabolic state of the insulin-dependent diabetic patients. There were also single beta cells or groups of beta cells, which could be found between the exocrine pancreatic tissue, already at an early stage in pregnancy. It is assumed, that the nesidioblastosis in fetuses from diabetic women is caused by a continuous stimulation of the fetal endocrine pancreas during pregnancy. These results are in a good correlation to the in vitro results of the insulin secretion of human fetal pancreatic slices after incubation.

Adult↗