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Biomedical subjects

A Vaheri

Publications and source records attributed to A Vaheri.

At least 271 records · Page 15Linked to original sources
PubMed1987

Microvillus-specific Mr 75,000 plasma membrane protein of human choriocarcinoma cells.

We have previously purified from cultured JEG-3 choriocarcinoma cells an Mr 75,000 protein, originally detected using antibodies to a retrovirus-related synthetic peptide. Using polyclonal antibodies, we have now localized this protein immunocytochemically in JEG-3 cells at both light and electron microscopic levels. In immunofluorescence microscopy of saponin-permeabilized cells, the antigen appeared as dots and short strands at the apical cell surface. In pre-embedding immunoperoxidase electron microscopy, the Mr 75,000 protein was specifically localized to microvilli on the apical cell surface. Immunoferritin electron microscopy was used to assess more quantitatively the antigen distribution in the plane of the plasma membrane, and to define the position of the antigenic site(s) with respect to the membrane. The immunoferritin results confirmed the microvillus specificity of the Mr 75,000 protein and showed that the antigenic portion of the protein is within a few nanometers from, and on the cytoplasmic side of, the lipid bilayer. In detergent extraction experiments, the Mr 75,000 antigen was highly enriched in the soluble fractions. These results demonstrate that the Mr 75,000 protein is a membrane protein highly specific for microvilli.

Cell Compartmentation↗
PubMed1987

Viral antibodies and interferon in acute psychiatric disorders.

In a prospective study of 54 patients with acute psychiatric disorders, interferon and antibodies in serum and CSF were measured to 19 microbes by the complement fixation (CF) test and to 7 viruses by enzyme immunoassay (EIA). The CF test revealed a fourfold or greater change (p less than .001) in serum antibody titers in 20 patients, and EIA showed a twofold or greater change in CSF titers in 7 patients. Pathological serum/CSF antibody ratio by EIA was observed in 8 patients. The results suggest that viral infections and inflammatory processes have significance in the etiopathogenesis of acute psychiatric disorders.

Acute Disease↗
PubMed1986

A family of fibronectin mRNAs in human normal and transformed cells.

Previously, two fibronectin mRNAs, generated by alternative splicing of the extra domain (ED) and type III connecting segments (IIICS) sequences, have been described in a human transformed cell line and in human liver, respectively. We now report on a family of fibronectin mRNAs identified by Northern blotting analysis in two normal human fibroblast strains (HEL 299 and Flow 7000) and five transformed cell lines (8387 and HT-1080, fibrosarcomas; G-361, melanoma; JEG-3, choriocarcinoma; and RD, rhabdomyosarcoma). Seven different fibronectin mRNA forms with electrophoretic mobilities ranging between 8.6 and 7.7 kb were identified. Each cell line contains three (HEL 299, Flow 7000 and 8387) or two (HT-1080, G-361, JEG-3 and RD) fibronectin mRNAs species with characteristic size. In all cell lines we detected one fibronectin mRNA form which lacks the ED sequence (ED- fibronectin mRNA) and one or two fibronectin mRNAs containing it (ED+ fibronectin mRNA). These data show that the presence of ED+ and ED- fibronectin mRNAs is a general feature of all cells tested. Moreover, the fibronectin mRNA pattern is characteristic of the cell type analyzed, suggesting the occurrence of specifically programmed splicing mechanisms in each cell line.

Cell Line↗
PubMed1986

Deficient production of lysyl oxidase in cultures of malignantly transformed human cells.

Lysyl oxidase activity in the culture medium of eight malignantly transformed human cell lines was very low compared with that in four control fibroblast lines, being 9-16% in five sarcoma cell lines and 7-11% in three other tumour cell lines. The low enzyme activity was probably due to deficient enzyme synthesis rather than impaired secretion into the cell medium, as low activity was also found in urea extracts of the cell pellets. Lysyl oxidase production thus appears to be closely regulated with deficient collagen gene expression in malignant transformation.

Amino Acid Oxidoreductases↗
PubMed1986

Human tumor cells synthesize and secrete alpha-2-macroglobulin in vitro.

In previous studies we showed that human sarcoma and melanoma cell lines synthesize and secrete into culture medium a glycoprotein, migrating in urea sodium dodecyl sulfate-polyacrylamide gel electrophoresis at Mr 140,000. It is not detected in cultures of the corresponding normal cells. Conditioned medium of the melanoma cell line HMB-2, producing among the cell lines tested the largest amounts of this glycoprotein, has now been used as a source for purification of the protein. NH2-terminal amino-acid sequence determination of the purified glycoprotein showed that it is identical to human alpha 2-macroglobulin (alpha 2M). Rabbit antibodies raised against the glycoprotein specifically reacted in immunoblotting and immunodiffusion tests with alpha 2M present in human plasma. Likewise, these antibodies immunoprecipitated from the conditioned media of 35S-methionine-labelled melanoma and osteosarcoma cell lines the protein which had a molecular weight corresponding to alpha 2M. alpha 2M was also synthesized and secreted by 2 strains of fetal lung fibroblasts but not by fetal skin fibroblasts or adult skin fibroblasts autologous to the osteosarcoma cell line.

Cells, Cultured↗
PubMed1986

Fibronectin is expressed by astrocytes cultured from embryonic and early postnatal rat brain.

In early primary cultures from newborn rat brain, few glial fibrillary acidic protein (GFAP)-positive glial cells expressed intracytoplasmic immunoreactivity for fibronectin. After the second week in culture, however, fibronectin was expressed by a distinct population of GFAP-positive flat astrocytes, irrespective of which brain region was studied. In cerebellar cultures, these cells were more abundant than in cortical or neostriatal cultures and often formed a major population of the GFAP-positive cells. The difference in fibronectin expression between cerebellum and the other areas studied was statistically significant. When cultures were started from 9-day-old postnatal rat brain, fibronectin-positive astrocytes appeared earlier than in those from newborn animals, in all areas studied. Further, especially in the case of cerebellum, the number of fibronectin-positive astrocytes increased as a function of time in culture. In cultures started from whole brains of 12-day-old rat embryos, fibronectin was expressed within 24 h in culture by all the cells with morphology of flat astrocytes, positive for vimentin but negative for GFAP. These results indicate that astrocytes cultured from newborn and early postnatal rat brain are a heterogeneous population of cells: depending on the brain region studied and also depending on the age of brain tissue or the time in culture, less than 1-60% of the GFAP-positive flat astrocytes expressed fibronectin. This, together with the fact that fibronectin was present in early embryonic brain cells in culture, suggests that fibronectin may be a prerequisite for the development or interactions of brain cells.

Animals↗
PubMed1986

Effect of low level immunity on response to live rubella virus vaccine.

Serum specimens of 1075 young adults representing nursing and medical staff were collected for determination of rubella immunity using the radial haemolysis (RH) technique, also know as the haemolysis in gel (HIG) test. Of the sera 84 (7.8%) were negative (RH titre less than 4 mm) and an additional 93 (8.7%) gave an RH titre of 4-5 mm, which was regarded as the limit of immunity. Initially, 64 persons of these 177 were vaccinated with the RA27/3 strain of live attenuated rubella virus. Their serum samples were collected at the time of vaccination and at three weeks and three months after vaccination. Altogether 54 vaccinees could be followed for their immune response throughout the study. It became obvious that vaccination generally caused seroconversion only after three months rather than within three weeks. Only one person remained seronegative - even after a booster dose of vaccine. The mean final antibody titres in individuals with pre-existing low level immunity was 6 mm whereas in initially seronegative persons the antibody titre after vaccination was 8.5 mm on average. Thus a pre-existing low level immunity will effectively block the immune response to live rubella virus vaccine and this phenomenon may explain some apparent vaccination failures.

Adult↗
PubMed1986

The extracellular matrix is an integrated unit: ultrastructural localization of collagen types I, III, IV, V, VI, fibronectin, and laminin in human term placenta.

The human term placenta is used extensively as a source of extracellular matrix components. To elucidate the tissue distribution and interrelationships of seven of these components, monospecific antibodies directed against collagen types I, III, IV, V, VI, fibronectin, and laminin were reacted with human term placenta and studied by light and electron immunohistochemistry. Type I collagen was the basic structural unit of human term placenta, present as 30-35 nm, cross-banded fibers, often in the form of large fiber bundles. Type III collagen was present as thin 10-15 nm, beaded fibers often forming a meshwork which encased type I collagen fibers. Types V and VI collagen were present as 6-10 nm filaments, often closely associated with types I and III collagen. Type VI collagen also coated collagen fibers of all diameters, enhancing their periodicity, providing a staining pattern often similar to that observed with anti-fibronectin antibodies. Fibronectin was present in both maternal and fetal plasma and throughout the stroma of the chorionic villus, as both free filaments and coating collagen fibers. Basement membranes contained laminin and type IV collagen, but no fibronectin. In summary, the non-basement membrane proteins studied often codistributed with type I collagen, between and apparently attached to fibers, suggesting that they may act as binding proteins, linking type I fibers and bundles, to themselves and to other structures.

Collagen↗
PubMed1985

Structure and interactions of proteoglycans in the extracellular matrix produced by cultured human fibroblasts.

Subconfluent cultures of human embryonic skin fibroblasts were labelled with [35S]sulphate for 3 days, after which cell-free extracellular matrix was isolated. A chondroitin sulphate proteoglycan (CSPG) and a heparan sulphate proteoglycan (HSPG) were purified from the matrix. Chromatography on Sepharose CL-2B gave peak Kav. values of 0.35 and 0.38 respectively for the CSPG and the HSPG. The polysaccharide chains released from the two PGs were of similar size (Kav. 0.50 on Sepharose CL-4B). Approx. 50% of the CSPG showed affinity for hyaluronic acid (HA). However, it differed immunologically from the HA-aggregating CSPG of human articular cartilage, and had a larger core protein (apparent molecular mass 290 kDa) than had the cartilage PG. Neither metabolically [35S]sulphate-labelled PGs, isolated from the medium of fibroblast cultures, nor chemically 3H-labelled polysaccharides (HA, CS, HS and heparin) were incorporated into the extracellular matrix when added to unlabelled cell cultures. These results indicate that the matrix PGs are not derived from the PGs present in the medium and that an interation between polysaccharide chains and matrix components is not sufficient for incorporation of PGs into the matrix. Incubation of cell-free 35S-labelled matrix with unlabelled polysaccharides did not lead to the release of any 35S-labelled material, supporting this conclusion. Furthermore, so-called 'link proteins' were not present in the fibroblast cultures, indicating that the CSPGs were anchored in the matrix in a manner different from the link-stabilized association of CSPG with HA in chondrocyte matrix. The identification of a proteinase, secreted by fibroblasts in culture, that after activation with heparin has the ability to release 35S-labelled PGs from the matrix may also indicate that the core proteins are important for the association of the PGs to the matrix.

Cartilage, Articular↗