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Biomedical subjects

R Korec

Publications and source records attributed to R Korec.

At least 19 recordsLinked to original sources

From Langerhans islets to pancreas transplantation over the past 30 years: a review with personal contributions.

Organ, tissue and cell banking is currently an important method used to prevent death of cells in replacement transplantation therapy. From 1975 to 1985 the author performed experimental transplantations of islets isolated by collagenase digestion through injection into the liver through the portal vein, or by transplantation of minced neonatal pancreases under the renal capsule of alloxan or spreptozotocin into severely chronic diabetic rats and mice. Seventy of the 256 transplanted rats and mice were cured for 1 year, i.e. one-third of their life span, at the 3rd to 15th inbreeding and only 2 weeks of immunosuppression by azathioprine or cyclosporin A. The author compares his results with those achieved later with diabetic patients by whole pancreas transplantation, including prevention of diabetic renal and ocular complications, infertility, health of progeny of cured rats, and slow rejection and possibility of cure by repeated transplantation. He welcomes the return to islet transplantation, and possibly also of immunologically tolerant pancreatic stem cell transplantation, or transplantation of subcutaneous fibroblasts, transfected with a complex insulin gene, which will produce adequate insulin to prevent hyperglycemia, as does hepatic pyruvate kinase from an insulin analog, a therapy that will not need permanent immunosuppression.

Animals↗

Effects of the neoflavonoid coutareagenin, one of the antidiabetic active substances of Hintonia latiflora, on streptozotocin-induced diabetes mellitus in rats.

In the present study, diabetes mellitus was induced with streptozotocin in Wistar rats from the inbred strain F > 28, and a blood sugar lowering effect due to the oral or intragastric administration of a copalchi native extract (Hintoniae latiflorae cortex) or intragastric administration of the pure substance, coutareagenin (neoflavonoid) (5-hydroxy-7-methoxy-4-(3,4-dihydroxyphenyl)-2H-benzo-1-pyran-2-on), was demonstrated with statistically significant results. This study enlarged and confirmed the results of earlier studies by other authors with regard to the antidiabetic effect of the copalchi bark extract in various animal species with hyperglycemia induced by different methods. By the use of the synthetically produced neoflavonoid, coutareagenin, the present series of tests provided evidence that coutareagenin, one of the active substances contained in Hintonia latiflora bark (Copalchi bark), produces a reduction of diabetic elevated blood sugar levels. The native extract as a whole, however, has to be regarded as the active substance (active substance complex) of Hintonia latiflora (Copalchi) bark.

Animals↗

Salivary and plasma insulin levels in man.

Changes in plasma and salivary immunoreactive insulin were studied in saliva and blood of 9 healthy subjects following either oral glucose or a test meal ingestion at 30 min intervals for up to 3h. The levels of plasma immunoreactive insulin reached maximum at 60 min with a value of 62.77 +/- 6.52 microU/ml after the glucose load and 62.62 +/- 6.52 microU/ml after the test meal. In the case of salivary immunoreactive insulin levels, the maximum was attained at 90 min with a value of 18.47 +/- 2.68 microU/min after the glucose load and 22.40 +/- 2.01 microU/min after the test meal. Positive linear correlation (r = 0.74) was found between the salivary and plasma immunoreactive insulin levels.

Administration, Oral↗

[Spontaneous and experimental models of human juvenile diabetes mellitus].

The author describes his findings pertaining to spontaneous diabetes mellitus in BB rats and the method and results in juvenile alloxan diabetes in neonatal and adolescent Wistar rats of his own inbreeding F8-10. The author presents also the results of attempts to treat juvenile alloxan diabetes in rats by intrafamilial renal-subscapular allotransplants of 2-5 neonatal collagenase nondigested pancreases. Six of eleven BB females developed latent or manifest insulin dependent diabetes mellitus during the third to fourth month of life. An intraperitoneal injection of alloxan to 2-5-day-old rats causes, after two months of prediabetes, latent or manifest disease, in particular in males. In one-two-month adolescent fasting F6--10 inbred rats (Wistar strain) intravenous injection of 50 mg/kg alloxan causes diabetes mellitus with hyperglycaemia (20-60 mmol/l), glycosuria, polyuria, arrested growth, development of cataract and early death due to pulmonary or intestinal infection. The author tries to prevent these sequelae and complications by insulin therapy or intrafamilial allotransplantations of 2-5 neonatal, collagenase nondigested pancreases beneath the renal capsule, using two-three--week immunosuppression with Cyclosporin A combined with Azathioprine. The author proves permanent cure, histologically and functionally, by repeated allotransplantation which, however, due to the intense thymolymphatic immunological barrier in adolescent rats is less frequent than cure repeatedly achieved by the author in adult diabetic rats.

Animals↗

[Diabetes diagnosis following intravenous and oral glucose load: animal experiment principles].

Aiming at highest possible reduction of causes of individual variability, at determination of diagnostic value of different intravenous and oral (intragastric, per sondam) glucose loads and at comparison of diagnostic value of ivGTT and oGTT after the same load, author first performed ivGTT with 1 g glucose per kg body mass and oGTT with 1, 2, 4 g/kg in normal (non anaesthesized) adult (F 6-7) inbred rats and mice and than repeated these tests with the same loads and the same rats and mice with different extent of B-Cell lesion after i.v. alloxan injection. Results show that for unmasking of latent ("chemical") diabetes a higher load (4 g/kg orally) was necessary, that the assimilation constant of ivGTT was diabetic earlier than the criteria of oGTT after equal oral load (1 g/kg) and that for the diagnosis of early stages of diabetes not only absolute values of GTT curves but also their form are important.

Administration, Oral↗

Treatment of alloxan and streptozotocin diabetes in rats by intrafamiliar homo (allo) transplantation of neonatal pancreases.

A total of 116 adult male and female rats of own inbred F3 up to 8th generation weighing 180-350 g was rendered diabetic by a single i. v. injection of either alloxan (40-50 mg kg-1) or streptozotocin (50-60 mg kg-1) and 1--2 weeks later subjected to the intrafamiliar homo(allo)transplantation of 2--5 minced, collagenase non digested pancreases either from own newborns or from newborns of sisters and brothers of the same family under the renal capsule. Out of the total, 24 animals (20.68%) were successfully cured. The cured rats examined with the aid of intravenous glucose tolerance test (IV) GTT monthly for one year showed fasting normonoglycemia with increased postglucose values and decreased KG being in the range of latent, borderline diabetes. In male rats IV GTT deteriorated in nine months without any transition into manifest diabetes or loss of body weight. Some animals cured by transplantation reached a normal survival time and were able to bring forth litters and suckle their newborns. In the rats with complete reversal of diabetes the transplants with well developed, vascularized islets, consisting predominantly of B-cells were found.

Alloxan↗

Experimental hypoglycemizing tumor of B-cells of Langerhans islets produced by the combined action of streptozotocin annd nicotinamide in the rat.

Young male and female Wistar-Velaz rats were treated with streptozotocin-nicotinamide combination according to the method of Rakieten and examined periodically for 23 months for fasting and postprandial glycemia, by intravenous, intraperitoneal or intragastric glucose tolerance and tolbutamide tests with the aim to detect in vivo the experimentally produced nesidiomas. One male rat with severe hypoglycemia, apparent first on tolbutamide test after twelve months, later also on glucose tolerance test and fasting hypoglycemia associated with paraplegia with macroscopically and microscopically documented nesidioma is described. The exstirpation of this nesidioma was followed first by normalization and later by development of latent diabetes.

Adenoma, Islet Cell↗