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Biomedical subjects

S Gay

Publications and source records attributed to S Gay.

At least 253 records · Page 14Linked to original sources
PubMed1983

Collagen formation by the hepatocyte in primary monolayer culture and in vivo.

Immunohistochemical techniques were used to confirm biochemical evidence that parenchymal cells isolated from adult rat liver and maintained in nonreplicating monolayer culture for 2 days synthesized type IV basement membrane collagen. On continued incubation in serum-free medium, the hepatocytes also synthesized the interstitial collagens, types I and III. Consistent with these results in culture, type IV collagen was localized to the hepatocytes in slices of pathologic rat liver. Hence collagen formation is a previously unrecognized function of the hepatocyte that may be important in the pathogenesis of liver fibrosis or cirrhosis.

Animals↗
PubMed1983

Histological and immunohistological identification of collagens in basement membranes of Schwann cells of neurofibromas.

The application of immunohistological techniques that use antibodies highly specific for collagen allows new comparative studies in the distribution and deposition of genetically distinct types of collagens in neurofibromas. The identification of collagen type IV in basement membranes is unique and marks particularly the sheaths or cytoplasma of proliferating Schwann cells. Cells with greater degrees of atypia show increased amounts of intracellular collagen in basement membranes by immunohistologic examination, which provides an additional diagnostic tool in dermatopathology.

Basement Membrane↗
PubMed1983

What is collagen, what is not.

Collagen represents a series of proteins that are broadly related in terms of chemical features, structure, and function. This presentation focuses on current information relevant to the function, chemistry, and structure of collagen in order to more precisely define the parameters within which a protein may be recognized as collagen. It is noted that ultrastructural investigation of collagen based on transmission and scanning electron microscopy alone is of limited value, but that chemical analyses of tissue specimens and the use of immunohistochemical techniques are essential in evaluating collagenous proteins in normal and pathologic tissues. In addition to the specific types of collagen (I-VI), the role of collagen in the biology and pathophysiology of connective tissue is discussed.

Collagen↗
PubMed1982

Ultrastructural localization of type V collagen in rat kidney.

Antibodies specific for the alpha 1 (V) chain and native collagen molecules containing the alpha 1 (V) chain have been used in electron immunohistochemical studies of rat kidney to determine the ultrastructural distribution of this class of collagen molecules. In addition, antibodies against type I collagen and whole basement membrane were used as markers for interstitial collagen and authentic basement membranes. Our results indicate that type V collagen is present in the renal interstitium in different forms: in close apposition to interstitial collagen fibers; in the stromal aspect of vascular basement membranes; and as particulate material not bound to other structures. On the basis of these findings, we postulate a binding or connecting function for this collagen type.

Animals↗
PubMed1982

Characteristics of bone marrow fibroblast colony-forming cells (CFU-F) and their progeny in patients with myeloproliferative disorders.

Chronic myeloproliferative disorders (MPD) are clonal diseases of the pluripotent hematopoietic stem cell frequently associated with myelofibrosis (MF). There is only indirect evidence indicating that the increased deposition of collagen in bone marrow matrix is a secondary phenomenon. A liquid culture system for cloning and growing bone marrow fibroblasts has permitted us to approach more directly the understanding of the pathogenesis of myelofibrosis by comparing the biophysical, growth, and functional characteristics of fibroblasts from normals, MPD patients without MF, and those with MF. In patients with MF, marrow fibroblast colony (CFU-F) formation could not be studied; fibroblasts were grown from marrow explants. CFU-E from normals and MPD patients exhibited similar cell density distribution and similar cell sedimentation rates. These similarities contrasted sharply with the differences seen when the erythroid and granulocyte-macrophage progenitors were studied by the same methods. There was a marked light density shift and a rapidly sedimenting shift of MPD hematopoietic colony-forming cells. Marrow fibroblasts from MPD patients with and without MF displayed the same in vitro growth characteristics as fibroblasts from normals. Both types of fibroblasts exhibited anchorage and serum dependence, and contact inhibition of growth. Marrow fibroblasts were also characterized for the presence and distribution of fibronectin and collagen types by immunofluorescent staining using monospecific antibodies. Extracellular matrix, membrane-, and cytoplasm-associated fibronectin, type I, type III, and type V collagen showed a similar staining pattern in both normal and myelofibrotic marrow fibroblasts. Plasminogen-dependent fibrinolytic activity elicited from normal and myelofibrotic marrow fibroblasts were equivalent. Chromosomal analysis of hematopoietic cells and marrow fibroblasts from Philadelphia chromosome positive chronic myelocytic leukemia patients with and without MF showed that the Philadelphia chromosome was present only in hematopoietic cells. The results of these studies taken together demonstrate that bone marrow collagen-producing cells from MPD patients with and without MF behave in vitro as do those from normals. These findings support the hypothesis that that the marrow fibrosis observed in patients with MPD results from a reactive process rather than from a primary disorder affecting the marrow collagen-producing cells.

Adult↗
PubMed1982

Laminin-secreting yolk sac carcinoma of the rat. Biochemical and electron immunohistochemical studies.

Basement membranes have been difficult to analyze biochemically because they represent a small fraction of most normal tissues and because they are extremely difficult to solubilize. The use of mouse tumors such as the parietal yolk sac carcinoma and the EHS sarcoma, in which basement membrane is one of the major biosynthetic products, has provided new insights into our understanding of basement membranes. One of the disadvantages of the mouse tumor system is the small size of the tumor-bearing animals. For this reason we decided to explore whether embryo-derived yolk sac carcinomas produced in rats could be suitable models to study basement membranes. Unlike its counterparts in the mouse the rat embryo-derived yolk sac carcinoma produces a multilamellar extracellular matrix that, morphologically, closely resembles basement membranes of non-neoplastic origin. The laminin isolated from the rat embryo-derived yolk sac is similar to that derived from the EHS sarcoma, and antibodies raised against this laminin of neoplastic origin react with all basement membranes of normal tissues tested. These antibodies were used to define the ultrastructural localization of laminin in normal rat kidney. We concluded that the rat embryo-derived yolk sac carcinoma is a useful experimental system to study basement membranes and their components such as laminin, type IV collagen, and heparan sulfate.

Animals↗
PubMed1981

Collagen molecules comprised of alpha 1(V)-chains (B-chains): an apparent localization in the exocytoskeleton.

Antibodies specific for alpha 1(V) chains and native collagen molecules containing the alpha 1(V) chain have been used to study the localization of alpha 1(V)-containing molecules in differentiating hyaline cartilage. Immunofluorescence data show that the undifferentiated mesenchyme contains significant quantities of these molecules throughout the cell-rich tissue matrix. Examination of fully differentiated hyaline cartilage reveals a unique staining pattern wherein the immunofluorescent material is restricted to the pericellular matrix within the chondrocyte lacunae. We conclude from these data in conjunction with other evidence that the Type V collagens function as components of an exocytoskeleton for connective tissue cells.

Animals↗
PubMed1980

Collagen heterogeneity in normal rabbit cornea. I. Isolation and biochemical characterization of the genetically-distinct collagens.

Limited proteolysis of preparations of mature rabbit cornea with pepsin allows the recovery of approximately 90% of the tissue collagen in soluble form. Using recently described selective precipitation techniques, the soluble cornea collagen can be resolved into two major fractions. The predominant fraction, which accounts for about 95% of the solubilized collagen, was identified by means of solubility properties, electrophoretic and chromatographic properties, as well as amino acid analyses of its constituent chains, as Type I collagen. The alternate fraction, which accounts for virtually all of the remainder of the solubilized cornea collagen, was identified by means of the same criteria as collagen comprised of the A and B chains. In addition, the stoichiometry of the latter chains in preparations of cornea collagen indicate that in the cornea these chains are likely to participate in the formation of only one type of collagen molecule with the chain composition, AB2. And finally, the demonstration that Type I and the AB2 collagens are the predominant forms of collagen recoverable from the mature cornea strongly suggests that molecules comprised of the A and B chains are not necessarily confined to basement membrane structures.

Amino Acids↗
PubMed1980

Collagen types synthesized in dermal fibroblast cultures from patients with early progressive systemic sclerosis.

Fibroblast cultures were established by explant culture from upper and lower dermis of 7 normal donors and 10 patients with early progressive systemic sclerosis (PSS). Antibodies against collagens containing the A and B chains, collagens which occur largely in vascular structures, were isolated and used for immunofluorescence studies. Cultures from lower PSS dermis accumulated significantly more of these collagens than fibroblast cultures from upper PSS dermis or cultures from upper or lower dermis of normal skin. These data indicate that the collagens containing the A and B chains in early PSS lesions are produced by cells of vascular origin and support the concept that alterations in vascular tissue play a prominent role in the pathogenesis of PSS.

Adult↗
PubMed1980

Immunoelectron microscopy of type III collagen in normal and scleroderma skin.

Normal and scleroderma skin was studied by indirect immuno-electron microscopy with specific antibodies against Type III collagen. Fine collagen fibrils, 200-400 A in diameter were labeled with antitype III collagen antibodies. These antibodies attached to the collagen fibril forming rings with a 650 A periodicity. Fibrils with more than 600 A in diameter were only labeled with antitype I collagen antibodies. Type III collagen was found around small blood vessels, adipocytes and smooth muscle cells, thus, corresponding to the distribution of reticulin.

Antibodies↗
PubMed1980

Autoantibodies to basement membrane collagen: epidermolysis bullosa simplex versus bullous pemphigoid.

As judged by passive hemagglutination and hemagglutination-inhibition assays, sera from six patients in one family with dominant epidermolysis bullosa contain clearly demonstrable titers of antibodies against the collagen C chain which is derived from basement membrane structures. Moreover, the circulating antibodies observed in these patients are apparently specific for the C chain as no titers were observed when using four additional well-characterized collagen chains in the indicated assays. In contrast to the results with sera from epidermolysis bullosa patients, sera from a series of age- and sex-matched healthy controls, as well as from a group of patients with bullous pemphigoid, did not contain antibodies to any of the test antigens. These results thus clearly differentiate the autoimmune response to basement membranes observed in bullous pemphigoid from that observed in epidermolysis bullosa simplex.

Autoantibodies↗
PubMed1980

Immunohistochemical localization of Type III collagen in the dentin of patients with osteogenesis imperfecta and hereditary opalescent dentin.

The immunohistochemical localization of Type III collagen was studied in the dentin from nine patients with dominantly inherited osteogenesis imperfecta (O.I.) and six patients with hereditary opalescent dentin (H.O.D.). The most consistent localization of Type III collagen was found in patients with O.I. Among these patients an indirect relationship existed between the severity of dentinal involvement and the presence of Type III antibody localization. Although a similar but less intense staining could be observed in some cases of H.O.D., the severity of dentinal alterations in H.O.D. was not correlative to the quantitative presence of material reacting with antibodies to Type III collagen. These observations further indicate that O.I. is not only clinically, but biochemically, a heterogeneous condition.

Adolescent↗