Search PubMed⌕ Search

Biomedical subjects

E J Miller

Publications and source records attributed to E J Miller.

At least 109 records · Page 6Linked to original sources
PubMed1983

Different levels of glycosylation contribute to the heterogeneity of alpha 1(II) collagen chains derived from a transplantable rat chondrosarcoma.

Three collagen fractions, each of which contain molecules composed of alpha 1(II) chains, have been isolated from pepsin-solubilized rat chondrosarcoma collagen. One fraction could be selectively precipitated from the pepsin digest at 0.7 M NaCl. Two additional fractions were obtained on chromatography of the collagen precipitating at 1.2 M NaCl on carboxymethyl cellulose under nondenaturing conditions. When chromatographed on carboxymethyl cellulose under denaturing conditions, each fraction contained components eluting in the position expected for alpha 1(II) chains. One of the fractions precipitating at 1.2 M NaCl contained the recently described 1 alpha and 2 alpha chains in addition to material eluting as alpha 1(II) chains. Comparison of the chains eluting as alpha 1(II) chains in the various fractions with respect to amino acid composition, carbohydrate content, and cyanogen bromide-cleavage products showed that they differed only in the number of glycosylated hydroxylysyl residues. In this regard, alpha 1(II) chains obtained from collagens precipitated at 1.2 M NaCl exhibited significantly higher levels of glucosylgalactosylhydroxylysyl residues than alpha 1(II) chains precipitated at 0.7 M NaCl. These results indicate that molecules composed of alpha 1(II) chains are heterogeneous with respect to levels of hydroxylysine-linked carbohydrate moieties and that the more highly glycosylated molecules require higher salt concentrations for precipitation from acidic solutions. The data also indicate that a proportion of the more highly glycosylated alpha 1(II) chains are involved in the formation of one or more molecular species with 1 alpha and 2 alpha chains.

Amino Acids↗
PubMed1983

Use of bone-marrow culture in prediction of acute leukaemic transformation in preleukaemia.

Bone-marrow granulocyte-macrophage progenitor cell proliferation and regulatory factor (colony-stimulating activity; CSA) production were assessed at presentation and, if possible, subsequently in twenty-one patients with dysmyelopoiesis and less than 5% bone-marrow blasts. Seven patients underwent acute leukaemic transformation 1-35 months after the first marrow culture. Assay of bone-marrow endogenous CSA proved the most useful prognostic test. The rate of transformation in the seven patients with raised CSA at presentation was significantly greater (five transformed and one died at or before 4 months) than that in the fourteen patients with normal, low, or undetectable CSA (two transformed at 27 and 35 months). In one of the latter an increase in bone-marrow CSA occurred 6 weeks before transformation (serial marrow samples were not available in the other case). No other marrow culture feature measured, including the presence or absence of granulocyte-macrophage colony-forming cells and total clone numbers (colonies and smaller clusters) was as useful.

Adult↗
PubMed1983

Isolation and characterization of the cyanogen bromide peptides of the collagen 2 alpha chain from a transplantable rat chondrosarcoma.

The rat collagen 2 alpha chain was isolated from a transplantable Swarm chondrosarcoma following limited pepsin proteolysis. The chromatographically purified 2 alpha chain when cleaved with cyanogen bromide yields nine peptides which have been isolated and characterized with respect to their molecular weight and their amino acid composition. Eight of these peptides can be rapidly separated by gel-permeation high-performance liquid chromatography and retrieved for further purification by ion-exchange chromatography. The nine peptides are recovered in equimolar amounts and together account for a total of 1,014 amino acid residues. The features of the isolated cyanogen bromide peptides of the 2 alpha chain clearly differentiate it from other known collagen polypeptides. The possible homologies between the 2 alpha chain and other collagen alpha chains are noted. Comparison of the cyanogen bromide peptides indicates a close relationship of the 2 alpha to the alpha 1(V) chain.

Amino Acids↗
PubMed1983

Identification of collagen chains as a function of cyanogen bromide peptide patterns using gel permeation high-performance liquid chromatography.

A gel permeation high-performance liquid chromatography system utilizing commercially-available silica-based gels has been developed for evaluation of the cyanogen bromide cleavage products derived from collagen a chains. The high efficiency and precision of the system permits unequivocal identification of various chains by inspection of the peptide elution pattern following a single run requiring 40 minutes. The system is sufficiently sensitive to permit analyses to be performed with as little 1.0 microgram of sample, although the columns utilized may accommodate samples as large as 1.0 mg making the system useful for preparative purposes as well.

Chemical Phenomena↗
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

Nonhelical, fibronectin-binding basement-membrane collagen from endodermal cell culture.

A novel method of affinity chromatography on insolubilized collagen-binding fragments of fibronectin was utilized to isolate a random-coil collagenous protein from culture media of mouse teratocarcinoma-derived endodermal cells. These cells also produced another collagenous protein, which did not bind to fibronectin but could be isolated by differential salt precipitation. The affinity-purified collagen differs from its conventionally isolated counterpart in that it is not triple-helical in structure, its polypeptides are not disulfide-crosslinked and it has affinity for fibronectin in its native state. Both collagens resemble previously characterized type IV basement-membrane collagens with respect to their amino acid composition, cyanogen bromide peptides, chain size, immunological reactivity and tissue localization. The random-coil collagen is directly active in promoting the attachment of some lines of cells, but for attachment of the endodermal cells addition of fibronectin is required. This suggests that the presence of nonhelical, fibronectin-binding collagen may have biological significance in the interaction of cells with the extracellular matrix.

Amino Acids↗
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

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

Isolation and characterization of the cyanogen bromide peptides derived from the human alpha 2(V) collagen chain.

The human alpha 2(V) collagen chain when cleaved with cyanogen bromide yields ten peptides which can be recovered in approximately equimolar quantities. Characterization of the purified peptides with regard to molecular weight and amino acid composition establishes the uniqueness of the peptides and reveals that the alpha 2(V) chain recovered following limited pepsin digestion contain 956 amino acid residues. Possible homologies between the alpha 2(V) peptides and peptides derived from other collagen chains were noted. In addition, a high-performance liquid chromatography system is described for the separation of three of the alpha 2(V) chain peptides which were not resolved by using conventional separation techniques.

Amino Acids↗
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↗
PubMed1981

Evidence for the existence of an alpha 1(V) alpha 2(V) alpha 3(V) collagen molecule in human placental tissue.

Chromatography in native type V collagen from human placenta on phosphocellulose using nondenaturing conditions results in the partial resolution of two cellulose using nondenaturing conditions results in the partial resolution of two fractions. The first fraction contains each of the three type V alpha chains in approximately equal proportions and upon thermal denaturation exhibits a melting temperature of 33 degrees C. Fraction two contains the alpha 1 (V) and alpha 2 (V) chains in approximately a 2:1 ratio, respectively, and has a melting temperature of 35 degree C. These data indicate the presence of two molecular species of type V collagen in placenta, namely an alpha 1 (V) alpha 2 (V) alpha 3 (V) molecule and the previously described [alpha 1 (V)]2-alpha 2 (V) molecule.

Chromatography, Ion Exchange↗
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↗