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Biomedical subjects

D Aunis

Publications and source records attributed to D Aunis.

At least 199 records · Page 11Linked to original sources
PubMed1980

Immunohistochemical and immunocytochemical localization of myosin, chromogranin A and dopamine-beta-hydroxylase in nerve cells in culture and in adrenal glands.

Dopamine-beta-hydroxylase, chromogranin A and myosin were purified from bovine adrenal medulla and antibodies prepared against these proteins. Indirect immunocytochemical methods were used to localize dopamine-beta-hydroxylase, chromogranin A and myosin in bovine adrenal medulla and myosin in rat adrenal glands and cells from rat C.N.S. maintained in primary culture. Dopamine-beta-hydroxylase and chromogranin A were found in chromaffin granules, in agreement with biochemical data and, using electron microscopy, dopamine-beta-hydroxylase was found within the matrix and in the surrounding membrane of the storage granule, whereas chromogranin A was confined to the granule matrix. Myosin was localized in the vascular system irrigating adrenal glands, fibroblasts lining the vessels and chromaffin cells. In chromaffin cells, staining was found at the cell boundaries and electron microscopy showed myosin to be associated with the plasma membrane. Faint immunocytochemical staining by antimyosin antibodies was observed around certain exocytotic profiles but particular association with such structures was not demonstrable. Myosin localization was also studied in bovine adrenal cortex, where it was found in vascular channels and faintly in adrenal cortical cells, as in rat adrenal cortex and medulla, where identical patterns were obtained. In neuronal and glial cells dissociated from 13 day rat embryo cerebral hemispheres and cultured for 48 h, localization of myosin was studied using immunohistochemistry. The neuritic expansions and growth cones of neurons were fluorescent, whereas in glial cells, filamentous networks were visualized enclosing the nucleus and as long fibres traversing the entire cytoplasm.

Adrenal Glands↗
PubMed1979

Freeze-fracture study of the chromaffin cell during exocytosis: evidence for connections between the plasma membrane and secretory granules and for movements of plasma membrane-associated particles.

Exocytosis was studied in acetylcholine-stimulated bovine adrenal medulla. During a pre-exocytotic stage, chromaffin granules are found in juxtaposition to the plasma membrane and separated from it by an electron dense space 25--27 A in width. Freeze-fracture studies show this stage to be characterized by connections between the granules and the plasma membrane. These connections are apparently cytoplasmic but bridge both membranes; they are presumably proteinaceous, but their exact nature remains to be elucidated. Later stages of exocytosis were also studied by the freeze-fracture technique; a typical feature is the lack of intramembrane particles around the fusion site. Both connections and membrane particle movement are discussed in terms of recent biochemical findings.

Acetylcholine↗
PubMed1979

Some observations on bipolar filaments formed by non-muscle myosins.

Adrenal medullary and retinal myosins formed bipolar filaments in vitro. These filaments showed features suggesting flexibility in the rod region of the myosin molecules composing such filaments; in certain cases the myosin heads spread away from the filament backbone, in others the backbone itself was twisted. In addition the bare central backbone showed transverse striations.

Adrenal Medulla↗
PubMed1979

Immunofluorescent localization of microfilaments in neuronal and glial primary cell cultures with antibody against adrenal medullary myosin.

The localization of myosin was studied in rat neuronal and glial cell maintained in primary culture, using the double antibody immunofluorescent method. Antibodies were raised against myosin purified from bovine adrenal medulla. Myosin-specific immunoreactivity was found in the cell body and neurites of neuronal cells and in the cytoplasm of glial cells. In the former no typical substructure was observable, whilst in the latter myosin-rich filaments were found forming either a cage entrapping the nucleus or as long cables in cellular morphogenic expansions.

Adrenal Medulla↗
PubMed1978

Properties of partially purified bovine brain dopamine beta-hydroxylase.

Dopamine beta-hydroxylase has been partially purified from bovine brain. A 140-fold purification factor was achieved using solubilization with Triton X-100, ammonium sulphate fractionation between 20-50 per cent saturation, affinity chromatography on concanavalin A-Sepharose 4 B and then filtration through Sephadex G200. The specific activity at the end was 51 nmoles/h/mg protein. The majority of endogenous inhibitors were lost. Immunological studies, kinetic studies, studies on the interaction with lectins and the effect of carboxylic acids on enzyme activity were carried out. Our data are in favour of the close similarity between the bovine brain and adrenal enzymes. No major differences could be found, at least with the characterization experiments using in the present study.

Adrenal Glands↗
PubMed1977

Gangliosides and phospholipids of the membranes from bovine adrenal medullary chromaffin granules.

The lipid and ganglioside compositions of membranes of chromaffin granules isolated from bovine adrenal medulla have been investigated. The detailed lipid analysis revealed the presence of high levels of lysophosphatidylcholine, in agreement with previous studies, but also of sphingomyelin and plasmalogens. From these membranes, gangliosides have been extracted and separated by thin-layer chromatography and analysed. 95% of the total recovered gangliosides were hematosides (GM3), which migrated as three major species. Sugar analyses have been performed, as well as the fatty acid compositions. The three hematoside gangliosides appeared to differ on the basis of their fatty acid composition. Compared with the brain, chromaffin granule membranes showed a simple ganglioside composition, thus offering a good model for the study of the metabolism and the role of gangliosides. The simple ganglioside composition of chromaffin granule membranes has allowed us to state that there are 60 mol phospholipid and 30 mol cholesterol per mol ganglioside.

Adrenal Medulla↗
PubMed1976

Plasma dopamine beta-hydroxylase in a noradrenalin-secreting pheochromocytoma.

Circulating dopamine beta-hydroxylase activity was studied in a case of a hypertensive patient bearing a pheochromocytoma. The tumour secreted noradrenalin. The enzyme activity was found to decrease gradually after removal of the tumour, and to reach a stable value, in correlation with the decrease of urinary catecholamines. It is concluded that some pheochromocytoma tumours are able to secrete dopamine beta-hydroxylase.

Adult↗
PubMed1976

[Dopamine beta hydroxylase. Value and limits of its study in neurology].

Plasma dopamine-beta-hydroxylase was studied in 96 subjects, 33 of them controls and 63 of them patients (Parkinson's disease, chronic chorea, torsion dystonia, postural tremor and epilepsy). Only the epileptics showed a significant decrease in the average level of dopamine-beta-hydroxylase activity in comparison with the controls. During the cold test, DBH did not vary except in one case. On the other hand, during epileptic attacks, DBH activity underwent considerable fluctuations. Therefore, except in special pathological conditions, such as epileptic attacks, measurement of plasma or serum DBH activity is of limited value for neurological pathology and is not a good indication of the activity of the sympathetic nervous system.

Amantadine↗
PubMed1975

Studies on the interaction of dopamine beta-hydroxylase from various sources with phytohaemagglutinins.

1. Bovine adrenal medulla dopamine beta-hydroxylase, a glycoprotein with terminal mannose residues in carbohydrate moiety, did not precipitate with any lectins tested except concanavalin A. After digestion with neuraminidase, the enzyme was shown to interact with ricin, and a good correlation was found between the amount of liberated sialic acids and the extent of agglutination. This finding show either that more than one type of carbohydrate unit occurs on the protein or that three are multibranched chains in the carbohydrate moiety. 2. Dopamine beta-hydroxylase from human serum, pheochromocytoma and normal adrenal were incubated with concanavalin A, ricin, wheat germ agglutinin and lectins from Dilochos biflorus and Robinia pseudoacacia. 83% of dopamine beta-hydroxylase from pheochromocytoma was precipitated by ricin, whereas the enzyme from human serum precipitated to a lesser extent (5-15%). Neuraminidase digestion of human serum dopamine beta-hydroxylase led to an increase of precipitation with ricin. The low extent of native human serum dopamine beta-hydroxylase precipitation with ricin can be explained by the attack of plasma membrane sialidases of liver cells, whereas the greater ricin precipitation of pheochromocytoma and normal adrenal dopamine beta-hydroxylases could be due to post-mortem effects. The clinical implications of possibility of difference concerning the carbohydrate moiety structures of pheochromocytoma and normal enzymes is discussed.

Adrenal Medulla↗
PubMed1975

Bovine adrenal medullary chromogranin A: studies on the structure and further evidence for identity with dopamine-beta-hydroxylase subunit.

1. Chromogranin A was purified by the use of polyacrylamide gel electrophoresis. The amino acid composition of chromogranin A appeared to be nearly identical to that reported by other investigators and, moreover, was confirmed to be similar to that of dopamine beta-hydroxylase. 2. Dansyl-end group analysis revealed the presence of leucine as the only amino-terminal residue and quantitative estimations showed the presence of two leucine residues per molecule of 77 000 molecular weight. 3. Tryptic and CNBr patterns were obtained. Data are in good agreement with the concept of two nearly identical polypeptide chains per chromogranin A molecule of mol. wt 77 000. Patterns were compared with those obtained in parallel dopamine beta-hydroxylase and support the idea that chromogranin A and the dopamine beta-hydroxylase subunit are identical. Digestion with leucine amino peptidase gave further additional evidence for this suggestion. 4. Chromogranin A appeared to be free of carbohydrates. No cross-reaction was detected between chromogranin A and rabbit antibody against bovine adrenal dopamine beta-hydroxylase.

Adrenal Medulla↗