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Biomedical subjects

O Lindvall

Publications and source records attributed to O Lindvall.

At least 217 records · Page 12Linked to original sources
PubMed1976

[An improved histofluorescence procedure for freeze-dried paraffin-embedded tissue based on combined formaldehyde-glyoxylic acid perfusion with high magnesium content and acid pH].

A technique is described for highly sensitive and precise visualization of central catecholamine systems in paraffin sections of freeze-dried tissue. The procedure is based on perfusion of the animal with a solution containing formaldehyde and/or glyoxylic acid, in the presence of a very high magnesium content (40 g MgSO4/150 ml solution) and acid pH. The perfused tissue is rapidly frozen, freeze-dried, treated with formaldehyde vapours (at +80 degrees C for 1 h), embedded in parffin in vacuo, and finally sectioned. The present technique has a sensitivity for the dopamine- and noradrenaline-containing systems that is comparable with that of the glyoxylic acid-Vibratome technique, which utilizes fresh, glyoxylic acid-perfused tissue. Thus, the preterminal axon pathways become fluorescent throughout their full extent and the several new terminal systems, discovered with the glyoxylic acid-Vibratome method, are well demonstrable. The method is also highly useful for the study of the cell bodies and their dendritic processes. The catacholamine fibre systems are visualized without any signs of diffusion and with a richness in detail. In animals pretreated with L-tryptophan and MAO-inhibitor the technique is also useful for studies on central indolamine-containing systems.

Animals↗
PubMed1976

On the occurrence of cysteinyldopa and dopa in melanocytes and benign nevi cells.

Previous studies have demonstrated a specific cytoplasmic fluorescence in human melanocytes, as well as in pigmented nevi and in malignant melanomas, when the formaldehyde histofluorescence method for visualization of certain catechol and indole derivatives was used. In malignant melanoma two fluorogenic substances, dopa and cysteinyldopa, were found previously. In human melanocytes and benign nevi cells the fluorogenic catechols have so far not been characterized, since chemical analyses are difficult to perform on skin, due to the small amounts of catechols present. However, using split thickness skin quantitative determinations are possible by sensitive fluorometric methods. The chemical analyses of cysteinyldopa showed that in human adult skin most or all was located in the superficial layers. The only specific fluorescence in the thin skin was found in dendritic melanocytes. The findings leave little doubt that cysteinyldopa is stored in melanocytes although the possibility of a concomitant occurrence of other thioethers is not excluded. Nevi and giant nevi were also similarly studied and we found considerable amounts of cysteinyldopa in the nevi. It seems as if the cysteinyldopa is stored in the fluorescent nevi cells. There was no consistent difference in the content of the catechol derivatives between intradermal and compound nevi.

Adolescent↗
PubMed1975

Evidence of an incerto-hypothalamic dopamine neurone system in the rat.

With the recently introduced glyoxylic acid histochemical fluorescence method, a previously unknown catecholamine-containing fibre system has been revealed in the zona incerta, hypothalamus and the caudal septum. These fibres, designated the incerto-hypothalamic system, have a characteristic, very delicate, finely varicose appearance, and they have a weak fluorescence, indicating an unusually low intra-neuronal amine content. On the basis of their distribution a caudal and a rostral part can be discriminated: the caudal part extends from the area of the dopamine-containing cell bodies in the caudal thalamus, the posterior hypothalamic area and the medial zona incerta (the A11 and A13 cell groups) into the dorsal part of the dorso-medial nucleus and the dorsal and anterior hypothalamic areas; the rostral part extends from the area of the rostral periventricular dopaminergic cell system (the A14 cell group) into the medial preoptic area and the periventricular and suprachiasmatic preoptic nuclei. The system probably extends also into the most caudal portion of the lateral septal nucleus. From a series of lesions and in vitro uptake studies, evidence has been obtained that the incerto-hypothalamic fibres are the projections of short, intradiencephalic dopaminergic neurones whose cell bodies are located in the A11, A13 and A14 cell groups. The projection areas of these neurones signify an involvement of the system in the control of secretion of pituitary hormones.

Animals↗
PubMed1975

Studies on the fluorophore forming reactions of various catecholamines and tetrahydroisoquinolines with glyoxylic acid.

Strongly fluorescent 2-carboxymethyl-3,4-dihydro-7-hydroxyisoquinolin-6-ones are formed in high yields when catecholamines are reacted with glyoxylic acid. Formation of the fluorophores has been found to take place in two steps; i. e. via virtually non-fluorescent tetrahydroisoquinoline-1-carboxylic acids, which react to give the fluorophores in a subsequent, rapid reaction with glyoxylic acid. The rates of reaction (pseudo first-order) with glyoxylic acid for 6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline, 6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline-1-carboxylic acid, and 6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline-3- carboxylic acid show that introduction of a carboxyl group at either C-1 or C-3 in a tetrahydroisoquinoline highly facilitates the reaction with glyoxylic acid. This behaviour is discussed in terms of a mechanism involving both intramolecular acid catalysis by the C-1 or C-3-carboxyl groups during dehydration of the carbinolamine intermediate, and facilitation of the prototropic shifts of the resulting Schiff's base by decarboxylation.

Catecholamines↗