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Biomedical subjects

J Thyberg

Publications and source records attributed to J Thyberg.

160 records · Page 9Linked to original sources
PubMed1975

Electron microscopie and enzyme cytochemical studies on the guinia pig metaphysis with special reference to the lysosomal system of different cell types.

A transmission electron microscopic study of demineralized, methaphyseal bone of the young guinea pig is presented. Special attention is paid to the lysosomal system of the different cell types. Visualization of acid phosphatase and aryl sulfatase activity was used to identify tissue components as belonging thereto. The distribution of alkaline phosphatase activity, a plasma membrane marker, was also examined. Osteoblasts were distinguished by a marked development of the granular endoplasmic reticulum and the Golgi complex. Perivascular cells type A, morphologically resembled the osteoblasts, and are believed to represent an early stage in the specialization of the latter. A few lysosomes were normally found in the osteoblasts; they were less common in the type A cells. In contrasts to their regular occurrence in guinea pig epiphyseal cartilage, dense bodies of lysosomal nature ("type I vesicles") were only rarely seen in the bone matrix. Structures analogous to the type II vesicles in cartilage were, however, normally present. Their membrane showed activity of alkaline phosphatase. Possible functions of lysosomes and matrix vesicles in osteogenesis are discussed. Perivascular cells type B and chondroclasts both contained a prominent Golgi complex and large numbers of free ribosomes, mitochondria and lysosomes. In the type B cells, inclusion material of varying appearance often occurred in the lysosomes and in endocytic vesicles. The chondroclasts sometimes presented a ruffled border, with associated vacuoles and lysosomes in the subjacent cytoplasm. It is suggested that both cell types participate in the resorption of the epiphyseal cartilage. Chondroclasts presumably arise by fusion of type B cells and/or monocytic precursors from the peripheral blood.

Acid Phosphatase↗
PubMed1975

Electron microscopic studies on the uptake of exogenous marker particles by different cell types in the guinea pig metaphysis.

Guinea pig metaphyseal bone was exposed to horse spleen ferritin in vitro and to colloidal thorium dioxide in vivo. The cellular uptake and intracellular accumulation of these marker particles were studied ultrastructurally. In vitro, the ferritin molecules were found to spread evely throughout the tissue. After 1-2 hours ferritin was mainly found in plasma membrane invaginations and in endocytic vesicles of varying size. At 4-6 hours a successive accumulation of the marker in secondary lysosomes could be observed. In addition to ferritin, the lysosomes and the large endocytic vesicles often contained other inclusions. In vivo, the pattern of intracellular accumulation of the marker particles was identical to that in vitro. Moreover, the presence within the cells of similar amounts of thorium dioxide after 1 and 4 days suggested that these indigestible molecules are stored intracellularly for a considerable time. In accordance therewith there were no definite signs of extrusion of labeled bodies or secretion of the exogenous marker by exocytosis. Ferritin and thorium dioxide were taken up by all cell types in the metaphysis. Both in vitro and in vivo perivascular cells type B ingested large amounts of marker particles, whereas chondroclasts, endothelial cells. perivascular cells type A and osteoblasts showed a more restricted endocytizing ability. On the basis of these observations, the functional significance of different cell types in the resorption of the epiphyseal cartilage and the formation of bone is discussed.

Animals↗
PubMed1975

Proteoglycans of hyaline cartilage: Electron-microscopic studies on isolated molecules.

Proteoglycan monomers from guinea-pig costal cartilage, bovine nasal and bovine tracheal cartilage were observed in the electron microscope after being spread in a monomolecular layer with cytochrome c. The proteoglycan molecule appeared as an extended central core filament to which side-chain filaments were attached at various intervals. The molecules from the three sources displayed great ultrastructural similarities. On average, the core filament was about 290 nm long, there were about 25 side-chain filaments per core filament, the side-chain filaments were about 45 nm long, and the distance between the attachment points of the side-chain filaments to the core filament was about 11 nm. With regard to the overall size of the molecules, no evidence of distinct subpopulations was obtained. Good correlation was found between ultrastructural data for the proteoglycan molecules and chemical data obtained by enzyme digestions and gel chromatography. Together these data strongly support the interpretation of the electron-microscopic pictures as indicating a central filament corresponding to the protein core and side-chain filaments corresponding to the chondroitin sulphate chain clusters of the proteoglycan monomers.

Animals↗
PubMedDate not supplied

The synthetic metalloproteinase inhibitor batimastat suppresses injury-induced phosphorylation of MAP kinase ERK1/ERK2 and phenotypic modification of arterial smooth muscle cells in vitro.

Smooth muscle cell (SMC) migration and proliferation are important events in the formation of intimal lesions associated with atherosclerosis and restenosis following balloon angioplasty. The extracellular matrix has important functions in modulating SMC structure and function, but less is known about the role of the matrix metalloproteinases (MMPs) and their endogenous tissue inhibitors. The present study investigates the effects of the synthetic MMP inhibitor batimastat (BB94) on vascular SMCs. As experimental model, rat aortic smooth muscle cells in primary and secondary cultures were employed. Electron microscopy was used to investigate the effects of BB94 on the overall phenotypic properties of the cells. Induction of DNA synthesis and migration was studied by thymidine autoradiography and counting of cells moving into an injured zone. Gelatin zymography was used for the detection of BB94-mediated inhibition of injury-induced MMP activity. Phosphorylation of the mitogen-activated protein kinases ERK1/ERK2, two potential mediators of the injury-induced activation of the cells, was measured by Western blotting. The results show that BB94 restrained the phenotypic modulation of vascular SMCs in primary cultures and suppressed injury-induced DNA synthesis and migration. Moreover, the upregulation of ERK1/ERK2 phosphorylation in injured secondary cultures and in cells treated with bFGF was markedly reduced by BB94, whereas TIMP-2 lacked a clear effect. Our data suggest that BB94 inhibits injury-induced activation of vascular SMCs by acting on MMPs as well as other targets.

Animals↗
PubMedDate not supplied

Fine structure of-and some histochemical observations on-chondroid regions of benign mixed parotid tumours.

Seven cases of mixed parotid tumour were studied at the light-and of these, three-at the electron microscopical level. In the latter group, special attention was paid to the fine structure of the chondroid regions of the tumours. The chondroid regions showed a typical cartilage fine structure-of greater interest was the finding that this tissue was mixed type of both hyaline and elastic cartilage. This was evident with respect to both cell and extracellular matrix. Two cell types were found: (A) cells similar to cells of hyaline cartilage and (B) cells resembling cells shown to be involved in synthesis of elastic fibres (elastic tendon fibroblasts, elastic cartilage chondrocytes and arterial smooth muscle cells). As in normal calcifying cartilage the chondroid regions contain numerous membrane-delimited matrix vesicles. However, mineral deposits within the latter were rare, indicating either a suppressed tendency towards mineralization of a lower stage of tissue maturation at which the mineralization process has not yet started.

Adenoma, Pleomorphic↗