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Biomedical subjects

A Dorn

Publications and source records attributed to A Dorn.

At least 127 records · Page 7Linked to original sources
PubMed1983

[Allogeneic transplantation of isolated islands of Langerhans into the liver of diabetic dogs with reference to its immunologic aspects].

By means of collagenase digestion and Ficoll gradient separation technique, viable islets of Langerhans were isolated from canine pancreases. These islets were transplanted into the liver of diabetic dogs. An experimental diabetes was induced by subtotal pancreatectomy and an application of 25 mg streptocotocin/kg bodyweight done twice. We performed the islet transplantation in several groups: 5 dogs differed from the donors by a strong histoincompatibility (EM-Test more than 15%). 5 dogs with a weak histoincompatibility and immunosuppression by Imuran and anti-thymocyte serum. The best results after transplantation were reached in the group with immunosuppression. There was an ameliorate effect on the hyperglycemia over a period of one year and we found significant differences in the glucose tolerance tests and in the immunoreactive insulin concentrations in contrast to the diabetic control dogs. No signs of portal hypertension and disturbance of the liver function were observed over the whole time of observations.

Animals↗
PubMed1982

Insulin-like immunoreactivity in the human brain- A preliminary report.

The localization and regional distribution of insulin-like immunoreactivity (IRI) was studied in human brain autopsy material using the indirect immunofluorescence technique. A positive reaction for IRI could be observed in many neurons of the hypothalamus, the hippocampus, corpus amygdaloideum, medulla oblongata (especially within the nuclei of cranial nerves IX, X and XII), and the cerebral cortex, whereas the cerebellar cortex was lacking in immunohistochemically detectable insulin-like material. No nerve fibres containing polypeptides could be revealed. Additionally, the insulin content of various brain regions was estimated by radioimmunoassay. Insulin concentrations in human nervous tissue were found to be elevated in comparison to blood plasma levels.

Aged↗
PubMed1982

C-peptide immunoreactive neurons in human brain.

C-peptide/C-peptide-like immunoreactivity was shown to be present in the cytoplasm of the soma and the proximal part of apical dendrites of some pyramidal cells in the Neocortex (Gyrus precentralis) and Hippocampus of man. C-peptide (connecting peptide) is a metabolic product in insulin biosynthesis and its localization in neurons is a proof for extrapancreatic insulin production.

Brain Chemistry↗
PubMed1982

Subclasses of simian-virus-40 large tumor antigen. Partial purification and DNA-binding properties of two subclasses of tumor antigen from productively infected cells.

Two major subclasses of simian virus 40 tumor antigen were prepared from productively infected monkey cells. These subclasses can be distinguished by their sedimentation properties: one tumor antigen form sediments at 5-6S and the other at 14-16S. The DNA-binding properties of these subclasses were investigated by two different experimental procedures. In the first procedure, the DNA binding of subclasses of crude tumor antigen, separated by zone velocity sedimentation, were assayed by immunoprecipitation of the DNA-protein complexes. In the second procedure, the two tumor antigen forms were partially purified by column chromatography and DNA binding was tested in a filter binding assay. Both procedures gave comparable results. (a) The 5-6-S and the 14-16-S tumor antigen bound specifically to a DNA restriction fragment containing the viral genome control regions. (b) At low salt concentrations, both subclasses bound to specific and to nonspecific DNA sequences; competition experiments in the presence of nonspecific DNA showed, however, that the affinity of both tumor antigen forms for the viral genome control region was at least 10-fold higher than their affinity for nonspecific DNA sequences. (c) The binding of the 5-6-S subclass to viral control region DNA was optimal at 60-80 mM NaCl while specific DNA binding of the 14-16-S form was optimal at 150-200 mM NaCl; however, binding of the 14-16-S form to nonspecific DNA sequences was also more resistant to high salt concentrations than that of the 5-6S form. (d) Both tumor antigen forms bound well to specific and to nonspecific DNA at pH 6-6.5; with increasing pH values, binding to nonspecific DNA decreased while binding to specific DNA reached an optimum at pH 7-7.5. Binding of the 14-16-S form to viral origin DNA was more resistant to pH values above 7.5 than binding of the 5-6-S form.

Animals↗
PubMed1982

Neurosecretory nerve cells of rat and fish brain are rich in thiol-protein disulphide oxidoreductase (TPO) immunoreactivity.

Thio-protein disulphide oxidoreductase (TPO) was demonstrated in rat and fish brain by use of the indirect peroxidase-antiperoxidase technique. TPO immunoreactivity was found to be widely distributed throughout rat CNS. Whereas most nerve cells possessed only weak immunoreactivity to the enzyme, the neurosecretory cells of Nuc. supraopticus and Nuc. paraventricularis were heavily laden with immune products. In fishes (rudd) the neurosecret-producing neurons of the Nuc. preopticus were the only locus being positive for TPO. From our findings we conclude that thiol-protein disulphide oxidoreductase might be involved into the process of neurophysin synthesis.

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

The 'embryonic moults' of the milkweed bug as seen by the S.E.M.

Deposition, detachment and removal of the three embryonic cuticles are studied. The membrane-like cuticle 1 covers the embryo during katatrepsis and 'disappears' thereafter. Cuticle 2 deposition starts shortly before dorsal closure. Its apolysis is accompanied by contractions of the embryo. Ecdysis of cuticle 2 takes place during hatching. Only cuticle 3 (= first larval cuticle) shows differentiations like sensilla and cornea. Peaks of ecdysteroid (and probably JH) titre are observed during apolysis of cuticle 1 and cuticle 2 (Dorn, 1981). Transition from ectoderm to epidermis proper takes place shortly before and during onset of cuticle 2 synthesis.

Animals↗
PubMed1981

Poor evidence for insulin/insulin-like immunoreactivity in the CNS of lower vertebrates.

The localization of insulin/insulin-like immunoreactivity was studied in the brain and the pancreas of an amphibian (clawed frog [Xenopus laevis Daudin]) and in the CNS of two teleost fishes (bream [Abramis brama L.] and rudd [Scardinius erythrophthalmus L.] using the indirect immunofluorescence technique. With exception of cerebellar Purkinje cells no neuronal elements were found to contain insulin-like material. The frog pancreas was characterized by a strong immunofluorescence in cells producing the polypeptide.

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↗