Search PubMed⌕ Search

Biomedical subjects

G Wick

Publications and source records attributed to G Wick.

At least 325 records · Page 18Linked to original sources
PubMed1980

A three-layer immunoradiometric assay for antibodies in different immunoglobulin classes and its application to the detection of chicken thyroglobulin autoantibodies and of antibodies to sheep erythrocytes.

A versatile solid-phase assay for detection of antibodies in different immunoglobulin classes is described. The assay has been applied to: (1) the detection of IgG and IgM anti-thyroglobulin autoantibodies in chickens with spontaneous autoimmune thyroiditis, and (2) the detection of anti-sheep cell antibodies in normal chickens. Thyroglobulin-coated plastic tubes or formaldehyde-fixed sheep erythrocytes were used as the solid phase. Antisera were added in succession to the solid-phase antigen so as to form 3 antibody layers: (1) chicken antibody against the solid-phase antigen; (2) heavy-chain-specific rabbit anti-chicken immunoglobulin; and (3) 125I-labelled goat anti-rabbit immunoglobulin. The assay is suitable for routine determinations on large numbers of samples; its sensitivity enables small volumes of serum to be tested and allows considerable economy in the use of valuable class-specific antisera. The radiolabelled reagent can be readily applied to other assays employing rabbit antisera.

Animals↗
PubMed1980

E receptors and T antigens are different antigenic entities on human T lymphocytes.

ATS contains antibodies of different specificity directed against E receptors and T specific antigens, respectively. E-receptors are trypsin-sensitive, T-antigens are trypsin-resistant. Absorption of ATS with trypsinized thymocytes thus removes anti-T, but leaves anti-E antibodies unaffected. The rosette inhibitory potential of the absorbed antiserum (anti-E) remains unaltered. Immunization with trypsinized thymocytes on the other hand results in the production of anti T-cell sera highly specific in immunofluorescence and cytotoxicity tests without contaminating anti-E antibodies and, therefore, also lacking any rosette inhibitory capacity. E receptors and T antigens are independently mobile within the cell membrane as shown by differential capping.

Animals↗
PubMed1980

Characterization of antibodies to basement membrane (type IV) collagen in immunohistological studies.

Antisera were produced in rabbits and guinea pigs against basement membrane (type IV) collagens which were extracted from a mouse tumor with acetic acid and from human placenta after limited digestion with pepsin. The antisera were specific for type IV collagen and did not crossreact with collagens type I, II and III from interstitial connective tissue, with collagen type V (AB2) from placenta and with a non-collagenous protein (laminin) obtained from basement membranes. Purified antibodies against both human and type IV collagen reacted in indirect immunofluorescence tests with the mouse tumor matrix and with authentic basement membranes in various human and mouse tissues. These antibodies failed to react with interstitial connective tissue. Absorption of antibodies against type IV tumor collagen with mouse or human kidney homogenate abolished or significantly decreased their reaction with tumor tissue. The findings indicate that various basement membranes may contain related or identical collagenous proteins which show a high degree of interspecies homology.

Absorption↗
PubMed1980

Distribution of basement membrane proteins in normal and fibrotic human liver: collagen type IV, laminin, and fibronectin.

Specific antibodies to collagen type IV, laminin, and fibronectin were used to localise these proteins by indirect immunofluorescence in frozen sections of normal and fibrotic liver. In normal livers distinct staining was found in basement membranes of blood and lymph vessels, of bile ducts and ductules and around nerve axons. Positive reactions for type IV collagen and fibronectin were also observed in the perisinusoidal space, while hepatocytes and most of the interstitial matrix of portal fields remained unstained. Liver specimens obtained from patients with alcoholic liver disease (fatty liver, hepatitis or cirrhosis) and chronic active hepatitis showed a more intense reaction with the antibodies in the perisnusoidal space including now distinct staining for laminin. These patterns were particularly prominent at borders between fibrotic septa and remnants of parenchyma or pseudolobules. Strong reactions were also found for type IV collagen and fibronectin in the periportal interstitium and in large fibrotic areas. The findings support previous electron-microscopical and chemical evidence for increased basement membrane production in human liver fibrosis and demonstrate that this may involve different proteins and occur at different anatomical sites.

Adolescent↗
PubMed1980

Short time bleaching of fluorescein isothiocyanate. A possible parameter for the specific binding of conjugates in immunofluorescence.

The fluorescence kinetics of fluorescein isothiocyanate (FITC)-antibody conjugates during short (0.01 sec) laser excitations were analyzed for possible information about the immunological specificity of binding to antigenic substrates in direct immunofluorescence assays with antigen-coated Sephadex beads. First results of these investigations suggest marked differences in the bleaching characteristics of specifically and nonspecifically bound FITC conjugates: FITC-anti-bovine serum albumin (BSA) and FITC-anti-rabbit immunoglobulin (Ig) were found to fade significantly more slowly when bound to the respective homologous antigen (anti-BSA to BSA, and anti-rabbit Ig to rabbit Ig) as compared to nonspecifically adherent anti-BSA to rabbit Ig, and anti-rabbit Ig to BSA. Possible implications of these data for discrimination of nonspecific staining in immunofluorescence are discussed.

Antigens↗
PubMed1980

Mummies from Peru. Demonstration of antigenic determinants of collagen in the skin.

This paper describes immunofluorescence studies on the possible preservation of antigenic determinants of different types of collagen in sections of the skin of human mummies from Peru. The age of the mummies was dated from the 4th to the 14th century AD. Using specific antibodies, it was possible to demonstrate type I and type III collagen. The antigenic determinants specific for procollagen type I, procollagen type III and the type IV collagen component of basement membranes were not preserved.

Adolescent↗
PubMed1980

Study on the nature of the Goodpasture antigen using a basement membrane-producing mouse tumour.

Autoantibodies in the sera of patients with Goodpasture's syndrome showed a strong reaction in indirect immunofluorescence tests on unfixed, frozen sections of a mouse tumour (EHS sarcoma), previously shown to produce extracellular basement membrane. Anti-basement membrane antibodies from patients with bullous pemphigoid failed to react with the mouse tumour, but showed a distinct reaction with cylindroma tissue. Absorption of Goodpasture sera with tumour homogenate completely abolished their reaction on sections of human and murine kidney. Basement membrane (type IV) collagen and a high molecular weight, non-collagenous glycoprotein were isolated from the tumour matrix and studied in absorption experiments and radioimmunoassays. Little or not reaction was observed with Goodpasture patients' sera indicating that neither of these two proteins is the major antigen involved in the disease. Antigenic material reacting with Goodpasture sera was extracted from the tumour in neutral salt solutions, suggesting that it is a non-collagenous protein.

Animals↗
PubMed1980

Quantitative immunohistochemistry.

In general there exist two possibilities to obtain quantitatively information in immunohistochemical work: (1) Titration of an antibody of defined specificity and concentration on different antigenic substrates. (2) The measurement of the "specific signal" of the marker molecule used for the visualization of the specific fixation of antibody to the homologous antigen in histological preparations. Examples for both kinds of approach are given by recent data from quantitative immunofluorescence (IF) studies performed in this laboratory. In the second part of this talk some theoretical aspects of quantitative IF are discussed concerning the fluorescence properties of fluorescein isothiocyanate, the most widely used fluorochrome. Macrospectrofluorometric measurements revealed marked effects on the emission intensity of the composition of the embedding medium and the concentration of the dye. Furthermore, the conjugation to protein is shown to cause a considerable quenching of UV excited fluorescence, but not at excitation with visible blue (496 nm). A further critical point in quantitative IF is the illumination source. The great advantages of laser light excitation as compared to filtered light of the most widely used mercury arcs are discussed. Finally some experimental data concerning the recovery of already faded fluorescence as observed with short, repeated laser light pulses are mentioned. The practical significance of these theoretical data are stressed.

Animals↗
PubMed1980

Characterization of antisera against bovine prolactin for in vivo studies on prolactin function in the rat.

The IgG fraction of rabbit antisera to bovine prolactin (PRL), intended for in vivo studies on the role of PRL in the rat, was prepared and characterized in vitro and in vivo. The antibodies showed a strong reaction with bovine PRL in double diffusion, immunoelectrophoresis, radioimmunoassay and passive haemagglutination using bovine PRL-coated erythrocytes. In indirect immunofluorescence on paraffin sections of bovine pituitary glands the antibodies could be used for the detection of PRL-producing cells. Cross-reaction with rat PRL was observed in passive haemagglutination with rat PRL-coated erythrocytes and in indirect immunofluorescence on rat pituitary gland, but not in any of the other test systems. The ability of the antibodies to neutralize homologous, i.e. bovine, PRL was tested in lactating rats depleted of endogenous PRL by bromergocriptin treatment. The impaired lactation performance of such animals can be restored by substitution with bovine PRL. If the bovine PRL used for substitution was complexed with anti-bovine PRL-IgG, it lost its biological activity. On the other hand, injections of even high amounts of the antibodies into lactating rats failed to reveal any effect on lactation. It is concluded that either the antibodies do not cross-react with circulating rat PRL in contrast to pituitary PRL (preprolactin?) or that the cross-reacting antibody-populations(s) lack(s) the ability to neutralize the biological function of rat PRL.

Animals↗
PubMed1979

Avian antigen binding cells: enrichment methods.

Data are presented comparing different methods for the fractionation and enrichment, respectively, of specific antigen binding lymphoid cells from immunized chickens. The bovine serum albumin (BSA) anti-BSA system was chosen as a model. To enrich avian antigen binding cells (ABC) from a mixture of chicken peripheral blood and spleen lymphocytes 3 different methods were used: (1) separation of cells forming rosettes with antigen-coated sheep red blood cells (SRBC) from non-rosetting cells by density centrifugation; (2) isolation of ABC by their specific adherence to antigen bound to immunoadsorptive surfaces (gelatin, plastics); (3) column affinity chromatography with antigen-coated agarose, cross-linked dextran for plastic beads. The most efficient method was column affinity chromatography with antigen-coated polyacrylamide beads which affords up to 12-fold enrichment of ABC. Both the other methods are also suitable for separation and enrichment of specific ABC but can only with difficulty be adapted for processing the large numbers of cells which would be necessary, e.g., for in vivo transfer studies.

Animals↗
PubMed1979

Immunofluorescence demonstration of type IV collagen and a noncollagenous glycoprotein in thickened vascular basal membranes in protoporphyria.

Specific rabbit antibodies to type IV collagen isolated from a basement membrane producing mouse tumor were used in indirect immunofluorescence tests to study the thickened vascular basement membrane in skin biopsies from patients with erythropoietic porphyria (EPP) and from protoporphyric mice. In addition, rabbit antibodies to a noncollagenous, basement membrane specific glycoprotein also derived from the mouse tumor were tested. It was shown that normal as well as altered vascular basement membranes in both the human and the murine skin specimens react with the anti-type IV collagen and the antiglycoprotein antibodies. A particular strong reaction in the diseases skin indicated that formation of new vascular basement membrane layers involved deposition of the major structural proteins which also constitute normal basement membrane matrices.

Animals↗
PubMed1979

Immunochemical characterization of the basement membrane glycoprotein laminin.

Laminin was recently characterized as being a major non-collageneous protein of the basement membrane matrix produced by a mouse tumor. It was extracted from the tumor matrix with neutral buffer and purified under non-denaturing conditions. Rabbit and guinea pig antisera raised against laminin or a large pepsin fragment P1 of laminin showed strong binding to both laminin and peptide P1 but only a weak reaction with reduced and alkylated laminin. The major antigenic determinants of laminin were located in a disulfide knot, comprising one third of the molecule, which resisted degradation by pepsin or cyanogen bromide. Minor antigenic determinants shared by the native and reduced protein could also be identified. The data were interpreted as showing that laminin consists of conformationally rigid as well as more flexible domains. Absorption studies with mouse kidney homogenate indicated that authenic basement membranes contain a protein immunologically identical to laminin. Tissues from other species contain a related protein which exhibits partial cross-reaction with mouse laminin. Together with immunofluorescence data the findings demonstrate that laminin, like type IV collagen, occurs in most basement membranes of the body.

Animals↗
PubMed1979

Immunochemical study on basement membrane (type IV) collagens.

Basement membrane (type IV) collagens were extracted from a mouse tumour with acetic acid and from human placenta after limited enzymatic digestion. Antisera were produced against both collagens in rabbits and guinea-pigs and examined by various assays. These antisera were found to be specific for basement membrane collagen and showed little or no cross-reactions with the interstitial collagens, types I, II and III or with human placenta collagen consisting of alpha A and alpha B chains. Varying degrees of cross-reaction were observed between antisera to human and mouse type IV collagen. Immunochemical analyses demonstrated the presence of three distinct determinants in the tumour type IV collagen. Rabbit antisera against this antigen reacted with either collagenase-resistant segments or with a collagenous, disulphide-bonded segment (P3). Guinea-pig antisera recognized primarily antigenic determinants in the P3 segment. Antisera to placenta type IV collagen reacted with another collagenous, pepsin fragment (P1) which lacks disulphide bonds. These antisera showed complete cross-reaction with collagenous alpha 1 (IV) chains prepared from pepsin-digests of human placenta and bovine lens capsule.

Animals↗