Biomedical subjects

R Lomský

Publications and source records attributed to R Lomský.

18 recordsLinked to original sources

PubMed2001

Deltins: immunochemical evidence for a novel population of peptides of the D cells of the gastro-entero-pancreatic endocrine system.

Differences between the immunocytochemical behaviour of antisera to partially purified porcine gastrins and antisera to either synthetic human gastrin-17-I or highly purified porcine gastrin-17-I raised the hypothesis that hog antral gastrin extracts contain peptides different from somatostatin and gastrin that are responsible for the immunocytochemical reaction of the former antisera in the D (delta) cells of the gastro-entero-pancreatic (GEP) endocrine system. This study was performed to prove this hypothesis. A discard fraction obtained after gel filtration of hog antral gastrin extracts on Sephadex G-50 Superfine was employed to immunize five rabbits. The discard fraction is highly heterogeneous on two-dimensional electrophoresis and contains merely traces of somatostatin and gastrin in RIA. However, rabbit antisera to the discard fraction give strongly positive immunocytochemical reactions exclusively in the D cells of the human antroduodenal mucosa and of the pancreatic islets. Absorption of the antisera with the lyophilized discard fraction abolishes the staining of the D cells, whereas absorption of the antisera with several somatostatins does not affect the staining. Vice versa, staining of the D cells with antisera to cyclic somatostatin-14 is abolished by absorption of the antisera with somatostatin-14 but not by absorption with excess of the discard fraction. In RIA, antisera to the discard fraction do not bind radiolabelled (Tyr(1))-somatostatin-14, Tyr-somatostatin-28 or synthetic human gastrin-17-I. Two-dimensional electrophoresis of acid extracts of isolated canine pancreatic islets followed by Western blotting shows different patterns of distribution of immunoreactive spots obtained with antisera to the discard fraction, to somatostatin-14, and to human proinsulin respectively. These results indicate the existence of a novel population of peptides of the D cells of the GEP endocrine system, for which we propose the term deltins.

Animals↗

PubMed1999

Increased glucagon-stimulated insulin secretion of cryopreserved rat islets transplanted into nude mice.

Cryopreservation is the only available technique for long-term storage of pancreatic islets. The freezing/thawing protocol may cause considerable loss of viable islet tissue and impair its function in vivo. The aim of this study was to investigate glucose and insulin levels after transplantation of fresh and cryo/thawed rat islets. Rat pancreatic islets were isolated following intraductal collagenase injection and Ficoll gradient purification. After isolation, islets were cultured for 24 h and then either transplanted or frozen after stepwise addition of DMSO according to Rajotte et al. and stored in liquid nitrogen. After rapid thawing islets were stepwise transferred into RPMI medium and cultured for another 24 h. The recipients were athymic mice with streptozotocine-induced diabetes. Two hundred fresh (n=13) or cryo/thawed (n=15) islets were transplanted beneath the renal capsule. Glucose levels were measured for 14 days and blood samples for insulin determination were obtained 15 min after i.p. glucagon (10 mg/kg) administration on day 14. Glucose levels were normalized (<9 mmol/l) in all recipients within 3 days since transplantation. On day 14, mean fasting values+/-SE in fresh and cryo/thawed islet groups were 4.0+/-0.6 and 4.4+/-0.4 mmol/l, respectively (P>0.05). Fasting insulin levels were higher in the cryo/thaw than in the fresh islet group (1.67+/-0.33 vs 0.57+/-0.13 ng/ml; P<0.01). Post-glucagon levels did not differ significantly (1.45+/-0.24 vs 0.86+/-0.24 ng/ml; P=0.06). While glucagon significantly increased insulin levels (P<0.01) in the fresh islet group, no change in insulin levels was observed (P>0.05) in the cryo/thaw group. Immunohistochemical staining demonstrated fragmentation of viable islet tissue which was more apparent in the cryo/thaw group. We conclude that in a short-term study cryo/thawed rat islets produce higher insulin levels than fresh islets transplanted into nude mice. This may be due to better islet survival or loss of feed-back regulation.

Animals↗

PubMed1996

Immunoradiometric and luminescence immunoenzymometric assay of human thyrotropin from dried blood spots for screening of neonatal hypothyroidism.

Two monoclonal antibodies to thyrotropin prepared in our laboratory were employed for the development of two-site immunometric assays in two modifications for the estimation of human thyrotropin in dried blood spots designed for the screening of neonatal hypothyroidism. The immunoradiometric assay using the second antibody labelled with 125I is simple and fast (one incubation step lasting 2 h). The detection limit of 1 mU/l and the absence of the hook effect up to a concentration of more than 1000 mU/l are optimal for neonatal screening; the presence of other glycoprotein hormones does not interfere with the assay. In the luminescence immunoenzymometric assay the second antibody is labelled with peroxidase. In spite of the two-step configuration the method is fast (4.5 h) and enables specific determination of thyrotropin levels in the range of 2.4-1100 mU/l. The conditions and properties of both immunometric assays described are comparable with the time-resolved immunofluorometric assay widely used in Europe.

Antibodies, Monoclonal↗

PubMed1980