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Biomedical subjects

B Ziegler

Publications and source records attributed to B Ziegler.

At least 109 records · Page 6Linked to original sources
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

Selective intracoronary thrombolysis in the coronary care unit without cineangiography.

Selective coronary artery visualization was performed in the CCU by means of a movable fluoroscopy device in 96 patients with suspected myocardial infarction within 6 hours after onset of symptoms. Intracoronary streptokinase (SK) was administered in a total dosage of 200 000 to 400 000 U within 30-60 min to 69 patients with complete (N = 57) or subtotal obstruction (N = 12) of the infarct-related vessel. Recanalization was achieved in 39 of the 57 patients (68%) with initially complete occlusion. Three of the 39 successfully treated patients died (7.7%) versus 8 of 33 subjects (24%) with persistent complete obstruction (chi-square 3.21, not significant). Selective cineangiography subsequently performed in 8 patients and postmortem examination of 12 subjects who had died, showed that all haemodynamically significant lesions had been recognized by the examination in the CCU with one exception. It is concluded that intracoronary thrombolysis performed in the CCU, by means of a standard mobile fluoroscopy equipment is effective, safe, inexpensive and may be started virtually without delay after admission.

Cineangiography↗
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

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

Complement-dependent cytotoxicity of monoclonal antibodies against islet cells.

Mouse monoclonal antibodies producing cell lines were generated against rat and human islet cells by somatic cell hybridization using the mouse myeloma cell line P3-X63-Ag8. Four hybrid cell lines are growing as ascites bearing tumors. All four monoclonal antibodies reacted with cytoplasmic islet cell antigens as detected by the indirect immunofluorescence technique on Bouin-fixed pancreatic sections of Wistar rats. Besides their binding to cytoplasmic antigens three of them also recognized antigens expressed at the islet cell surface. Moreover, two of these three monoclonal antibodies were capable of mediating complement dependent cytotoxicity against rat islet cells as revealed in a 51Cr-release assay.

Animals↗
PubMed1984

Effect of long-chain fatty acyl-CoA on mitochondrial and cytosolic ATP/ADP ratios in the intact liver cell.

The effect of long-chain acyl-CoA on subcellular adenine nucleotide systems was studied in the intact liver cell. Long-chain acyl-CoA content was varied by varying the nutritional state (fed and starved states) or by addition of oleate. Starvation led to an increase in the mitochondrial and a decrease in the cytosolic ATP/ADP ratio in liver both in vivo and in the isolated perfused organ as compared with the fed state. The changes were reversed on re-feeding glucose in liver in vivo or on infusion of substrates (glucose, glycerol) in the perfused liver, respectively. Similar changes in mitochondrial and cytosolic ATP/ADP ratios occurred on addition of oleate, but, importantly, not with a short-chain fatty acid such as octanoate. It is concluded that long-chain acyl-CoA exerts an inhibitory effect on mitochondrial adenine nucleotide translocation in the intact cell, as was previously postulated in the literature from data obtained with isolated mitochondria. The physiological relevance with respect to pyruvate metabolism, i.e. regulation of pyruvate carboxylase and pyruvate dehydrogenase by the mitochondrial ATP/ADP ratio, is discussed.

Acyl Coenzyme A↗
PubMed1984

Severe hyperglycaemia caused by autoimmunization to beta cells in rats.

The non-specific activation of the immune system by administration of complete Freund's adjuvant was examined in Wistar rats as a possible means of amplification of the specific immune response directed to pancreatic B cells caused by low dose non-diabetogenic multiple injections of streptozotocin. Rats were given intraperitoneally 0.5 ml of complete Freund's adjuvant to induce polyclonal lymphocyte activation and, 1 day later, the animals were given an intraperitoneal injection of 15 mg streptozotocin/kg body weight (group 1). This combined treatment was given twice at weekly intervals. In two further groups, rats were treated with complete Freund's adjuvant alone (group 2) or streptozotocin alone (group 3) with the same doses and at the same times. Only the rats in group 1 developed delayed but severe and persistent hyperglycaemia. In addition, significant complement-dependent cytotoxicity was detected in nine out of 15 rats (60%) in group 1 in islet cells, but not in spleen lymphocytes. The pancreatic insulin content of the rats in group 1 was depleted by up to 3.1 +/- 0.5%. With these experiments, a new animal model for insulin-dependent diabetes is described; complete Freund's adjuvant/streptozotocin diabetes. In many aspects, this model of diabetes parallels the development of insulin-dependent diabetes in man, including the humoral autoimmunity to islet cell antigens.

Animals↗
PubMed1984

Relationship between insulin secretion and pancreas morphology in subjects with chronic pancreatitis.

In order to investigate whether a relationship exists between in vivo insulin secretion and islet mass, 8 patients suffering from severe chronic relapsing pancreatitis were studied before and after pancreatectomy by glucose-glucagon-test (per os 1.75 g glucose; i.v. glucagon 0.01 mg/kg b.w.) and by intravenous glucose-tolerance-test (iGTT) (i.v. glucose 0.33 g/kg b.w.). Postoperative in vitro assessments of pancreatic insulin and alpha-amylase content were performed, and morphometric studies were carried out. Patients were characterized by reduced c-peptide secretion when compared with healthy subjects. The c-peptide response to the glucose-glucagon-test correlated well with the morphometrically estimated exocrine and islet tissue mass (P less than 0.05) and with the content of insulin and amylase in the tissue. The findings suggest that in subjects suffering from severe chronic relapsing pancreatitis the maximal insulin response might represent a parameter for the patient's islet mass.

Adult↗
PubMed1984

Autoimmune response directed to pancreatic beta cells in rats induced by combined treatment with low doses of streptozotocin and complete Freund's adjuvant.

Despite the existence of circumstantial evidence, a direct proof of an autoimmune basis for beta cell destruction in human type I diabetes has not yet been obtained. The present study was designed to test on Wistar rats whether a low-dose streptozotocin (SZ) treatment in combination with complete Freund's adjuvant (CFA) could be a useful approach to induce an autoimmune response to beta cells. Rats were weekly injected i.p. either with CFA or with SZ alone or with both CFA and SZ. Only the SZ-CFA-treated rats developed severe hyperglycemia. In these animals the pancreatic insulin content was nearly completely depleted. Only in SZ-CFA-treated rats cytotoxic autoantibodies to islet cells were found. The results show that in this new model of type I diabetes autoimmune reactions are involved in the destruction of beta cells.

Animals↗
PubMed1984

Monoclonal antibodies to human insulin and their antigen binding behaviour.

Mouse monoclonal antibodies were raised against human insulin by somatic cell hybridization using the mouse myeloma line P3-X63-Ag8. Five cell lines were grown as ascites producing tumors. Insulin binding data were determined from six monoclonal antibodies by Scatchard analysis. Each anti-insulin hybridoma antibody gave a straight-line Scatchard plot confirming the homogeneity of their binding sites and their monoclonality. The equilibrium dissociation constants ranged from 2.20 X 10(-8) to 4.48 X 10(-10) mol/l. We could demonstrate positive as well as negative cooperativity of monoclonal insulin antibodies by performing insulin binding studies with defined mixtures of two different anti-insulin hybridoma antibodies.

Animals↗
PubMed1983

Quantitative evaluation of functional capacity during isoniazid therapy in Huntington's disease.

Eleven patients with Huntington's disease were treated with high doses of isoniazid. In addition to clinical assessment, the functional capacity was evaluated quantitatively. The symptoms of four of the patients showed a marked improvement and their functional capacity increased. The condition of one patient with the rigid form (Westphal's variant) deteriorated, and the remaining six patients showed no change. Patients with prominent mental disturbances appeared to respond best to isoniazid therapy.

Adult↗
PubMed1983

Protection of insulin secretion by magnesium during islet culture: independence of cAMP/or insulin accumulation.

Pancreatic rat islets cultured for 12 days maintained their insulin content and biosynthesis when cultivated at 10 mmol/l glucose. The glucose-induced insulin secretion investigated in a subsequent incubation period was, however, reduced. At a Mg++ concentration of 5.3 mmol/l in the tissue culture medium not only the content and biosynthesis, but also the secretory response of cultured islets remained fully preserved compared to freshly isolated islets. The secretory response of pancreatic islets cultured at 0.8 or 5.3 mmol/l Mg++ for 4 days was neither related to steady state concentrations of cAMP nor connected to the cAMP accumulation in response to IBMX. The results demonstrated that the favourable effect of Mg++ during a culture period on the subsequent insulin release is not directly related to hormone storage, synthesis and/or cAMP-accumulation.

1-Methyl-3-isobutylxanthine↗
PubMed1982

Formation of islet cell monolayers from fetal human and neonatal rat pancreatic islets: protein biosynthesis, insulin secretion, and binding of islet cell antibodies.

The phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX) has been used to promote monolayer formation in cultured islets isolated from fetal human or neonatal rat pancreas. Immunofluorescence with specific antiserum to insulin revealed B-cells in the outgrown monolayers. The rat islet cells were further characterized by their secretory and biosynthetic response to the action of IBMX. Both glucose-stimulated insulin release and recoverable insulin, i.e. intracellular insulin plus insulin secreted, were increased by the addition of IBMX (0.1 mmol/l) to the medium containing 10 mmol/l glucose. 3H-leucine incorporation into (pro)insulin was significantly higher following culture in 10 mmol/l glucose plus IBMX (0.1 and 1.0 mmol/l) than after cultivation with glucose alone. However, the percentage of (pro)insulin synthesized in relation to total protein synthesis was increased to a lesser extent after an acute incubation for 3 h at 1.5 mmol/l or in the absence of glucose. Moreover, the culture system employed in the present study proved to be useful for detecting islet cell antibodies bound to human as well as rat islet cells after exposure to islet cell antibody-positive sera.

1-Methyl-3-isobutylxanthine↗
PubMed1982

Effects of 3-isobutyl-1-methylxanthine on secretory response, cAMP accumulation and DNA synthesis of islets from postnatal and adult Wistar rats.

A possible role for cyclic adenosine-3'-5'-monophosphate (cAMP) in islet cell replication was examined in collagenase-isolated pancreatic islets from Wistar rats of different age and different metabolic state (non-pregnant, pregnant, days 15.5-17.5). Islets obtained from pregnant rats released significantly more insulin in response to 10 mmol/l glucose (culture for 24 h) and their DNA synthesis (incorporation of [3H]thymidine into islet DNA) was doubled compared to islets from non-pregnant controls. Islets obtained from 4-6 days old rats showed a maximal stimulation of DNA synthesis after exposure to 0.1 mmol/l IBMX (3-isobutyl-1-methylxanthine) whereas the cAMP accumulation and the insulin biosynthesis measured in a subsequent short-term incubation were dose-dependent stimulated up to 1.0 mmol/l IBMX. In islets of 12 days old rats or 3 months old rats, however, IBMX did not stimulate DNA synthesis or insulin release measured during culture, although the cAMP content per islet was significantly enhanced after culture in the presence of IBMX.

1-Methyl-3-isobutylxanthine↗
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↗