Antti U. Arstila

Improvements in the method for the electron microscopic localization of arylsulphatase activity

SummaryThe optimal conditions for the demonstration of arylsulphatase activity in the proximal convoluted tubule cells of the rat kidney were studied at light and electron microscopic level. 8-hydroxyquinoline sulphate, p-nitrophenyl sulphate and 2-hydroxy-5-nitrophenylsulphate were used as substrates and barium and lead as capturing ions. The effect of fixation, capturing ions, substrate concentration and pH was studied biochemically. The results of these biochemical studies were then verified histochemically. Finally a recommended method for the light and electron microscopic demonstration of arylsulphatase activity was presented.

Studies on the pathogenesis of multiple sclerosis. 2',3'-Cyclic nucleotide 3-phosphohydrolase as marker of demyelination and correlation of findings with lysosomal changes.

Abstract 2′,3′-Cyclic nucleotide 3-phosphohydrolase, an enzyme proven in earlier studies to be associated with myelin, was used as indicator of demyelination in autopsy specimens of brain in 8 cases of multiple sclerosis and 2 of subacute sclerosing panencephalitis. Our results revealed that areas which showed demyelination on light microscopy showed also decreased phosphohydrolase values. The activity of phosphohydrolase increased in areas immediately outside plaques. These results compared well with cerebroside and other lipid data. However it was found that there was some discrepancy between lipid amounts and phosphohydrolase activity. Some areas where phosphohydrolase values were 3–4 times lower than in corresponding control specimens showed only half of the normal cerebroside content. The so-called normal white matter outside plaques did not show any constant decrease of phosphohydrolase activity but our material is too limited for any conclusion to be drawn. Our second major finding in this study was an increased response of lysosomes in areas where phosphohydrolase or lipid data did not reveal significant pathological changes. These results suggest that before demyelination begins there is a cellular response, possibly in glial cells, and demyelination seems to be only one of the consequences of this response.

On the epithelium of the rat pituitary residual lumen

SummaryHistology, enzyme histochemistry, and electron microscopy of the epithelium covering the rat pituitary residual lumen was studied. The anterior and posterior epithelium have similar histological and histochemical appearance, although the posterior epithelium shows stronger enzyme reactions for an esterase and many dehydrogenases. Electron microscopic studies reveal that both epithelia form a continuous lining. Anterior epithelium is in immediate contact with the interstitial spaces of the anterior lobe, while the posterior epithelium is separated from the intermediate lobe by a continuous basement lamina. The cytological features of both epithelia are also remarkably similar with scanty rough-surfaced endoplasmic reticulum, inconspicuous Golgi apparatus, round or oval mitochondria, and moderate number of lysosomal bodies. The apical surface of these cells is covered by microvilli and in some, especially posterior epithelial cells, by numerous cilia. Anterior epithelial cells and the apical portions of the posterior epithelial cells contain a number of large vacuoles with material possibly related to the colloid within the residual lumen. Electron microscopic findings suggest that both epithelia are possibly active in transfer and/or disposal of the colloid material rather than being secretory themselves. Enzyme histochemical findings support the hypothesis of an active role of these cells in metabolic processes related to phagocytosis. Based on these observations the colloid seems to be the product of the anterior lobe function.

Further studies on neutral proteinase activity of CNS myelin.

Abstract CNS myelin was prepared by six different gradient systems. The purity of the preparations was evaluated by electron microscopy and chemical markers. Electron-microscopic analysis of crude myelin preparations revealed contamination by axonal contents, mitochondria and lysosomes, while final preparations were characterized by small myelin fragments with little or no contamination. Chemical analysis revealed an approximately 500–1000-fold decrease in soluble, mitochondrial and lysosomal markers. The final preparations revealed a typical myelin structure and an absence of significant contamination by DNA. 7–14% of the neutral proteinase activity of the crude brain homogenate was found in purified myelin. This may favour the possibility that a part of the neutral proteinase is intimately linked to the myelin. The possible function of neutral proteinase in the formation of myelin buds during demyelination is discussed.

Guillan-Barré Syndrome

A 66-years-old man suffering from Guillan-Barre syndrome (GBS) died 11 days after the onset of the disease and was autopsied 12 h later. The histopathological preparations showed oedema and demyelinat

Development of the acrosomic system of the spermatozoon in the Norwegian lemming (Lemmus lemmus)

SummaryAn electronmicroscopic study on the development of the acrosome system of the spermatozoon in the Norwegian lemming (Lemmus lemmus) has been performed. The proacrosomal granules were found to be few and to consist of a dense center and a less dense periphery, and the acrosomal vesicle to contain stainable material of the same structure but of lower density than that of the acrosomal granule. Like in the guinea pig, two zones of different density exist throughout acrosome development and are visible also in mature spermatozoa. A large osmiophilic formation consisting of saccular, tubular, and lamellar structures, was found between the apex of the condensed nucleus and the acrosome and was identified as perforatorium.

Nuclear and cytoplasmic microfilaments in the pineal chief cells of the rat

SummaryThe presence of identical groups of parallel microfilaments in the nucleus and in the cytoplasm of the rat epiphyseal chief cells are described. The areas of microfilaments are not surrounded by any membranes and the single filaments are about 70–80 Å in diameter and vary largely in length. At higher magnification the filaments are shown to be composed of an inner light and outer dark zone. Since the filaments in the nucleus and in the cytoplasm are morphologically identical, they are suggested to originate in the same part of the cell and thus to be involved in the nucleo-cytoplasmic interaction.ZusammenfassungDie Anwesenheit von gleichartigen Gruppen paralleler Mikrofilamente in Kern und Zytoplasma von „Haupt-Zellen“ in der Rattenepiphyse wird beschrieben. Die Mikrofilamentareale werden nicht von Membranen umgeben; die einzelnen Filamente weisen einen Durchmesser von etwa 70–80 A auf und variieren stark in der Länge.Bei starker Vergrößerung zeigt sich, daß die Filamente aus einem inneren hellen und äußeren dunklen Streifen zusammengesetzt sind.Da die Filamente im Kern und im Zytoplasma morphologisch identisch sind, kann man fragen, ob sie am selben Ort in der Zelle entstehen und folglich in der Wechselwirkung von Kern und Zytoplasma eine Rolle spielen.

Neurochemical and morphological studies on demyelination in multiple sclerosis with special reference to etiological aspects

SummaryLight microscopic studies were used as control for neurochemical studies and these showed that some micro plaques could be found also in areas which were normal on visual inspection. Also foreign cell infiltrates were found outside any clear plaque material. The number of these cells did not correlate with other findings like lipid or enzyme chemistry. In electronmicroscopic studies astrocytes demonstrated most lysosomes and phagocytosis of myelin. This increased lysosomal reaction was demonstrated also in biochemical analyses performed on MS biopsy specimens. Occasional nuclear changes like inclusion bodies and protrusion of inner nuclear membrane were observed suggesting some exogenous, possibly viral factor as an origin of the disease. Neurochemical studies showed that demyelination as a sense of decrease in myelin lipid and phosphohydrolase activity is only a later phenomenon and increased lysosomal activities possibly originating from various glial cells are found before demyelination. However myelin-like material found inside lysosomes suggests the early moderate demyelination before classical plaques can be found. Acid hydrolases were mostly increased at areas around plaques and encephalitogenic protein was not demonstrable at plaque areas. Our combined study suggests early changes of glial cells as a basic mechanism of the disease. However, the clarification of the basic course of these changes remains to be seen although nuclear changes may suggest a slow viral infection.ZusammenfassungLichtmikroskopische Untersuchungen als Kontrolle neurochemischer Studien zeigten, daß einige Mikroplaques auch in Bezirken zu finden waren, die bei visueller Betrachtung normal erschienen. Weiterhin fanden sich Infiltrate fremder Zellen auch außerhalb des eigentlichen Plaquematerials. Die Zahl dieser Zellen korrelierte jedoch nicht mit anderen Befunden wie Lipid- und Enzymchemie. Elektronenmikroskopisch wiesen Astrocyten die meisten Lysosomen und die stärkste Myelinphagocytose auf. Diese verstärkte lysosomale Reaktion ließ sich auch an Hand der an MS-Biopsiematerial durchgeführten biochemischen Analysen nachweisen. Gelegentlich wurden auch nukleare Veränderungen wie Einschlußkörperchen und eine Protrusion der inneren Kernmembran beobachtet, die aufeinen exogenen, möglicherweise viralen Faktor als Ursache der Erkrankung hinweisen. Neurochemische Analysen zeigten, daß die Erkrankung im Sinne einer Abnahme der Myelinlipide und der Phosphohydrolyseaktivität erst später in Erscheinung tritt, während vermehrte lysosomale Aktivitäten, die von verschiedenartigen Gliazellen ausgehen, vor der Entmarkung zu finden sind. Myelin-ähnliches Material in den Lysosomen läßt jedoch vermuten, daß eine mäßige Entmarkung der Ausbildung klassischer Plaques vorausgeht. Saure Hydrolysen waren vornehmlich in der Umgebung der Plaques vermehrt, encephalitogenes Protein war im Bereich der Plaques nicht nachzuweisen. Unsere kombinierte Studie läßt vermuten, daß frühe Veränderungen der Gliazellen einen grundlegenden Mechanismus dieser Krankheit darstellen. Die Klärung des eigentlichen Verlaufes dieser Veränderungen steht jedoch noch aus, wenngleich nukleare Veränderungen auf eine langsame Virusinfektion hinweisen.

The loss of enzyme reaction products from ultrathin sections during the staining for electron microscopy

SummaryThe effects of heavy metal salt staining procedures on the reaction products obtained in the demonstration of arylsulphatase and of acid phosphatase were studied.Lead citrate staining at pH 12 was found to cause a very marked dissolution of barium sulphate and a moderate dissolution of lead sulphate. The staining with uranyl acetate was found to dissolve moderately both barium and lead sulphate.Neither lead citrate nor uranyl acetate staining had any remarkable effect on lead phosphate.The mechanism of the dissolution and the possibilities to avoid it were discussed.

Esterases in developing CNS myelin

Abstract Changes in the car☐ylic acid esterase activities from crude myelin fractions and subfractions of myelin were followed during the development of guinea-pig brains. Animals from 15 days to 1 year of age were used. A rapid decrease of activity towards α-naphthyl acetate and β-naphthyl acetate was observed especially in the first myelin-like (M2) fraction. This decrease was somewhat more moderate in the second myelin-like (M2) fraction. On the other hand, α-naphthyl propionate and β-naphthyl laurate activities were quite different. Only minor changes could be demonstrated in the M2 fraction during myelination, and there were no significant alterations in the second myelin-like fraction during the same period. These results fit with earlier findings concerning changes in short- and long-chain fatty acid patterns of myelin during development.