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Biomedical subjects

M Osborn

Publications and source records attributed to M Osborn.

At least 217 records · Page 12Linked to original sources
PubMed1981

The distribution of keratin type intermediate filaments in human breast cancer. An immunohistological study.

Antibodies to different intermediate filament proteins can be used to distinguish cells of epithelial, mesenchymal, muscle, glial and neuronal origin. Antibodies to prekeratin which characterize cells of epithelial origin, and antibodies to vimentin which recognize cells of mesenchymal origin have been used to study twenty cases of breast carcinoma (sixteen infiltrating ductal carcinomas and four infiltrating intraductal carcinomas), two cases of cystic breast disease, two fibroadenomas and one case of benign cystosarcoma phylloides. The prekeratin and vimentin were detected using specific antibodies to these proteins by immunofluorescence microscopy using alcohol fixed paraffin-embedded tissues. In eighteen out of the twenty carcinomas the tumor cells were strongly and specifically stained by antibodies to prekeratin. DIfferent tumors gave different patterns of prekeratin staining. In contrast, when the same specimens were tested with the vimentin antibody, the tumor cells were unstained, and instead only the usual strong staining to fibroblasts and blood vessels in the stroma was observed. In cystic breast disease, fibroadenomas, and benign cystosarcoma phylloides, cells of epithelial origin were strongly stained by the prekeratin but not by the vimentin antibody.

Adenofibroma↗
PubMed1981

Immunofluorescence microscopy of organized microtubule arrays in structurally stabilized meristematic plant cells.

Cells were prepared for indirect immunofluorescence microscopy after paraformaldehyde fixation of multicellular root apices and brief incubation in cell wall-digesting enzymes. This allowed subsequent separation of the tissue into individual cells or short files of cells which were put onto coverslips coated with polylysine. Unlike spherical protoplasts made from living tissues, these preparations retain the same polyhedral shape as the cells from which they are derived. Cellular contents, including organized arrays of microtubules, are likewise structurally stabilized. Antibodies to porcine brain tubulin react with all types of microtubule array known to occur in plant meristematic cells, namely, interphase cortical microtubules, pre-prophase bands, the mitotic spindle, and phragmoplast microtubules. The retention of antigenicity in permeabilized, isolated, stabilized cells from typical, wall-enclosed plant cells has much potential for plant immunocytochemistry, and in particular should facilitate work on the role of microtubules in the morphogenesis of organized plant tissues.

Chromosomes↗
PubMed1981

Expression of glial and vimentin type intermediate filaments in cultures derived from human glial material.

Several cultures established from biopsies of apparently normal adult human glial material showed no cells positive for glial fibrillary acidic protein (GFA) when examined after seven or more cumulative population doublings (CPD), although the established glioma line U251 MG showed approximately 3% GFA-positive cells, and U333 CG/343 MG clone 3 showed greater than 98% GFA-positive cells. Both the human glia delivered cultures and the glioma lines were positive when assayed with sera specific for vimentin. We therefore investigated the expression of GFA as a function of cumulative population doublings after the establishment of primary cultures. Under our experimental conditions, although GFA-positive cells were clearly present in the primary cultures accounting for some 3%-14% of the cells present, the GFA marker was subsequently lost, and the proliferating cultures expressed only the vimentin type of intermediate filament. Those cells that were GFA-positive also appeared to be vimentin-positive. GFA expression was not reinduced in cultures that had lost the GFA marker by treatment with dibutyryl cyclic AMP. We discuss two alternate hypotheses for the origin of the GFA-negative cells: (1) the cultures area of astrocyte origin but lost the ability to express GFA on culturing; (2) the cultures originate from cells of nonastrocyte origin present in the primary material.

Cell Division↗
PubMed1981

Heterogeneity of intermediate filament expression in vascular smooth muscle: a gradient in desmin positive cells from the rat aortic arch to the level of the arteria iliaca communis.

The display of the two distinct intermediate filament proteins, desmin and vimentin, in rat vascular smooth muscle tissue was studied by immunofluorescence microscopy on frozen sections of aorta and other blood vessels. Vascular smooth muscle cells present in these vessels always appeared rich in vimentin. However, staining of sections covering six distinct but contiguous parts of the aorta showed that the number of desmin containing cells was low distal to the truncus brachiocephalicus, but increases until in distal parts of the aorta and in the arteria iliaca communis almost all cells appear positive for desmin. Thus blood vessels show heterogeneity of intermediate filament expression not only in cross-section but can also display heterogeneity along their length. Muscular arteries such as the renal artery femoralis, as well as arterioles and veins including the vena jugularis and the vena cava also contain desmin. Thus it may be that low numbers of desmin-positive cells are typical of elastic arteries, while muscular arteries and other blood vessels are characterized by large numbers of desmin-positive cells. We discuss whether desmin-positive and desmin-negative vascular smooth muscle cells may perform functions and raise the possibility that desmin expression may coincide with the turn on of a specially regulated contractility program.

Animals↗
PubMed1981

Ultrastructure of multiple microtubule initiation sites in mouse neuroblastoma cells.

Morphologically undifferentiated and differentiated mouse neuroblastoma N115 and N18 cells were examined after serial sectioning by electron microscopy. A sizeable percentage of the cells revealed multiple centrioles, usually clustered together in the perinuclear area with 2 preferential locations, i.e. above and below the largest nuclear diameter. These results indicate that the multiple microtubule-organizing centres previously visualized by immunofluorescence microscopy with tubulin antibody in neuroblastoma cells recovering from Colcemid poisoning are most likely in majority related to multiple centrioles. This interpretation is further strengthened by experiments in which cells are first recorded in the fluorescence microscope and then after serial sectioning in the electron microscope. The results show that under optimal conditions immunofluorescence microscopy is able to visualize single centrioles. The possible biological significance of the combined electron and immunofluorescence microscopical results is discussed.

Animals↗
PubMed1981

Arrangement of neurofilaments, microtubules and microfilament-associated proteins in cultured dorsal root ganglia cells.

Using the indirect immunofluorescence technique, a study was made of the distribution of the major cytoskeletal proteins in cultures of cells derived from chicken embryo and newborn rat dorsal root ganglia. An antibody raised against the 200 000 molecular weight neurofilament "triplet" polypeptide isolated from rat sciatic nerve strongly stained some, but not all neurones in these cultures. In contrast filamin and vimentin antibodies stained Schwann cells and fibroblasts but not neurones. Antibody to fibronectin only stained material associated with fibroblasts. Thus these four antibodies can be used to distinguish between neurones, Schwann cells and fibroblasts, as well as to detect a heterogeneity in the neuronal population. In addition these antibodies, plus antibodies to actin, myosin, alpha-actinin, tropomyosin, fimbrin and tubulin allow a more detailed description of the cytoskeleton of cultured neurones at the light microscopic level.

Animals↗
PubMed1981

An immunofluorescence microscopical study of the neurofilament triplet proteins, vimentin and glial fibrillary acidic protein within the adult rat brain.

A collection of antibodies specific to different intermediate filament proteins were applied to frozen sections of adult rat brains. The relative distribution of these proteins was then studied using double label immunofluorescence microscopy. Antibodies specific to each of the neurofilament "triplet" proteins (of approximate molecular weight 68 K, 145 K and 200 K) stained exclusively neuronal structures. The distribution of these three antigens was in general identical, except that certain neurofilament populations such as those in the dendrites and cell bodies of pyramidal cells of the hippocampus and cerebral cortex, contained relatively little if any 200 K protein. Some neurone populations, such as the granule cells of the cerebellar cortex, could not be visualized by neurofilament antibodies, indicating that neurofilaments may not be essential for function of all neurones in vitro. Antibodies to GFA and vimentin stained an entirely different population of processes, none of which stained with any of the neurofilament antibodies. Vimentin antibody stained sheath material around the brain, a monolayer of ependymal cell bodies lining the ventricles, fibrous material associated within the choroid plexus, the walls of blood vessels and capillaries, and the processes of cells in certain regions. GFA antibody stained a second layer of sheath material under the vimentin layer, and numerous processes visible throughout the brain. Some specific populations of GFA-positive processes proved to stain also with vimentin. These included the processes of Golgi "epithelial" cells (Bergmann glial fibres), those of certain astrocytes in bundles of myelinated fibers. In addition, some processes apparently derived from ependymal cells proved to stain for both vimentin and GFA, whilst other could only be reliably visualized by vimentin alone. These results are discussed in terms of the previously described morphological characteristics of the various cell types of the brain.

Animals↗
PubMed1981

The cytoskeleton of blood platelets viewed by immunofluorescence microscopy.

Immunofluorescence microscopy has been used to characterize the morphological transitions that occur as platelets spread on a surface. Antibodies to the microfilament-specific proteins, actin, myosin, tropomyosin, alpha-actinin and filamin as well as antibodies to tubulin were used. Antibody to tubulin reveals the marginal band of microtubules as a bright fluorescent ring, the diameter of which decreases at a time coincident with pseudopod formation. The latter process is dictated by the assembly of microfilament bundles. Although the change in morphology of the platelet was not studied in detail, our data support the idea that microfilament reorganization influences the display of the marginal band of microtubules. A further conclusion is that the platelet in spite of its small diameter is a system suitable for immunofluorescence microscopy, a method which allows the rapid and simultaneous screening of many cells.

Actinin↗
PubMed1981

Coiling of intermediate filaments induced by microinjection of a vimentin-specific antibody does not interfere with locomotion and mitosis.

Microinjection of polyclonal sheep anti-vimentin IgGs purified by affinity chromatography into a rat fibroblastoid line leads to a specific reorganization of the cytoskeleton. Immunofluorescence microscopy shows that cytoplasmic microtubules and microfilaments are unaffected by intermediate filaments collapse and are collected into a tight perinuclear cap containing antibody-crosslinked vimentin filaments. The crosslinking was further documented by electron microscopy after treatment with Triton X-100 and ferritin-labelled anti-sheep IgGs. Inspite of the presence of the caps, which are retained for about 30 h, cells show a normal morphology and are locomotive. The collapsed intermediate filaments do not interfere with subsequent mitosis or with cytokinesis. After mitosis the capped filaments can be distributed either to both daughter cells or to only one of the two daughter cells.

Animals↗
PubMed1981

Vimentin, the 57 000 molecular weight protein of fibroblast filaments, is the major cytoskeletal component in immature glia.

Comparison of cytoskeletal preparations obtained from newborn and adult rat brain showed similar patterns on SDS-PAGE. However, coelectrophoresis of the newborn and adult preparations revealed distinct differences in the mobility of 2 major bands in the molecular weight range of 50--70 000. In adult brain cytoskeletons, the main band in the 50 000 range co-migrated with purified rat GFA protein (apparent molecular weight 53 000). No major band co-migrated with purified rat vimentin (apparent molecular weight 57 000). The reverse was true for newborn brain cytoskeleton. In adult and newborn brain cytoskeleton a major band co-migrated with the 150 000 neurofilament polypeptide isolated from rat spinal cord by immunoaffinity chromatography. Another neurofilament polypeptide (apparent molecular weight 72 000) was prominent in adult but not in newborn brain cytoskeleton. Conversely, newborn brain cytoskeleton comprised a band trailing behind the 72 000 neurofilament polypeptide. This band was not present in adult brain cytoskeleton. The distribution of vimentin in newborn rat brain was studied by immunofluorescence microscopy and compared to the distribution of GFA protein. As previously reported, a relatively limited number of GFA positive cells are present in the brain at this stage compared to later in development. Conversely, the large number of vimentin positive cells in newborn brain was well in keeping with the presence of a prominent vimentin band in cytoskeletal preparations obtained from this tissue. With the exception of meninges and blood vessels, vimentin appeared to be mainly localized in immature glia: periventricular glia; glia in non-myelinated white matter; radial glia in cerebral cortex and basal ganglia; Bergmann glia in cerebellum (Bergmann glia are still GFA negative in newborn rat). The neuroblastic germinal layers in hippocampus and cerebellum did not stain with vimentin antisera.

Animals↗