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H Nygren

Publications and source records attributed to H Nygren.

At least 55 records · Page 3Linked to original sources
PubMed1988

Molecular and supramolecular structure of adsorbed fibrinogen and adsorption isotherms of fibrinogen at quartz surfaces.

The adsorption of fibrinogen to quartz surfaces was measured by ellipsometry, ELISA, and electron microscopy. The initial adsorption at low concentrations was diffusion rate limited as determined by the ELISA and by counting the number of adsorbed molecules at electron micrographs. From ellipsometry, ELISA, and electron microscopy measurements it was found that the surface concentration of adsorbed fibrinogen increased continuously over four decades in bulk concentration of fibrinogen. At a hydrophilic quartz surface a plateau level of the adsorption isotherm was found at a surface concentration of 0.1 pmol/cm2 where the adsorbed molecules had a mean intermolecular distance of 10 +/- 5 nm between neighbors. At higher surface concentrations the molecules were densely packed and formed a layer where single molecules could not be identified. Adsorbed fibrinogen showed different structure at hydrophobic and hydrophilic quartz surfaces. At a hydrophilic surface, the fibrinogen molecules appeared as a 46 nm nodose rod consisting of 6-7 nodes with a diameter of 4 nm. At a hydrophobic surface, the molecule appeared as a binodular or trinodular rod with a node diameter of 5-9 nm, connected with a thin filament to form a 40-nm rod. Adsorption from higher concentrations of fibrinogen in solution resulted in adsorbed spheric structures with a diameter of 18-24 nm at the hydrophobic surface and in end-to-end polymers at the hydrophilic quartz membrane.

Adsorption↗
PubMed1988

Adsorption of coagulation proteins and adhesion and activation of platelets at the blood-solid interface. An experimental study of human whole blood.

A procedure is presented allowing detailed studies of the adsorption of coagulation factors from whole blood on to surface. Anticoagulant (citrate or hirudin) was added to fresh venous blood. The blood was incubated in hydrophilic or hydrophobic glass tubes without contact with air. The adsorption of fibrinogen, fibronectin and factor IX was measured with an enzyme immunoassay using specific antibodies directed against these proteins. Adsorption of enzymically active kallikrein was measured using a chromogenic peptide substrate. Adhesion and activation of platelets was measured by direct examination in a scanning electron microscope and by measurement of release of beta-thromboglobulin. The results show that the adsorption of plasma proteins at the blood-solid interface is dependent on the anticoagulant used, surface energy of the test surface and incubation time. In experiments using hirudin a specific inactivator of thrombin, as anticoagulant, we found dynamic changes of the adsorbed protein film which could not be studied using citrated blood.

Adsorption↗
PubMed1988

Immunological suppression of delayed hypersensitivity responses in mouse lungs as reflected by numbers of mononuclear cells, mast cells and mucus-producing cells.

The suppression of delayed hypersensitivity (DH) in the lung as reflected by the appearance of mononuclear cells, mast cells and mucus-producing cells was studied in Balb/c mice. Immunosuppression was induced by intravenous and peroral administration of picrylsulfonic acid (PSA) in mice subsequently sensitized with picrylchloride (PiCl). The animals exhibited a decreased DH reactivity as assessed by ear thickness increase compared with mice sensitized but not exposed to PSA pretreatment. In mice exposed to PSA intravenously (suppressed) and sensitized with PiCl there was a decrease in the number of mononuclear cells in the lung after challenge, compared to mice sensitized and challenged only. Similarly, the mast cell and mucus-producing cell numbers were slightly lower in animals immunosuppressed intravenously with PSA compared with sensitized mice. Such a decrease in the numbers of mononuclear cells, mast cells and mucus-producing cells in the lung was not seen in animals treated with PSA perorally, although these animals exhibited suppressed DH reaction in the ears. The present results indicate that induction of mononuclear cells and to some extent mast cells and mucus-producing cells in the lung relates to the DH reaction and its regulation.

Animals↗
PubMed1988

Regulation by T cells of delayed hypersensitivity reaction in mouse lung as reflected by mononuclear cells, mast cells and mucus-producing cells.

The appearance of mononuclear cells, mast cells and mucus-producing cells in the lung and their linkage to the development of delayed hypersensitivity (DH) reactions were studied. Adoptive transfer of immune lymph node cells, spleen cells and serum and in vivo treatment with monoclonal antibodies to L3T4-positive T cells in Balb/c mice were performed to investigate the cellular regulation of the number of mononuclear cells, mast cells and mucus-producing cells in the lung. Immune lymph node cells and, to a lesser extent, immune spleen cells from mice sensitized epicutaneously with picrylchloride transferred DH reactions to the recipients as assessed by ear thickness increase after challenge. Serum from sensitized mice was not able to transfer a DH reaction. Cyclophosphamide treatment of donor mice increased the DH reaction in the recipient mice. Adoptive transfer of immune lymph node cells and spleen cells gave a slight increase in the number of mononuclear cells in the lung of recipient mice compared with controls. This weak accumulation of mononuclear cells in the lungs of recipient mice, however, was not accompanied by a consistent increase in the number of mucus-producing cells and mast cells. The number of spleen cells expressing the L3T4 antigen decreased after in vivo treatment with the monoclonal GK1.5 (anti-L3T4) antibody as assessed by immunohistochemistry. This antibody treatment also resulted in an inhibition of the DH reaction and a decrease in the number of mononuclear cells and mucus-producing cells, but not in mast cells in the lung of sensitized and challenged mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Kinetics of antibody binding to solid-phase-immobilised antigen. Effect of diffusion rate limitation and steric interaction.

The binding of monoclonal antibodies to surface-immobilised antigen was studied. Antibodies against dinitrophenyl-benzene and O6-ethyl-2'-deoxyguanosine with a known affinity for the antigen were used. The amount of bound antibodies was measured by ellipsometry with an accuracy of +/- 0.15 pmol/cm2, and a sensitivity of 0.11 pmol/cm2. The binding rate of the initial antibody binding could become diffusion rate limited, and the binding rate at surface concentrations above 1 pmol/cm2 was affected by steric interaction between bound antibodies. Bound antibodies did not dissociate when rinsed with saline for up to 20 h, but dissociated in the presence of antigen (0.1 mM). The dissociation rate did not follow any identifiable rate constant. The results are discussed in relation to theoretical models of the kinetics of antigen-antibody reactions at solid-liquid interfaces.

Antibodies, Monoclonal↗
PubMed1987

Regulation of the delayed hypersensitivity reaction in the lung reflected as mononuclear, mast cell and mucus cell appearance after T helper cell depletion and adoptive transfer.

Epicutaneous sensitization with picrylchloride (PiCl) induced a strongly delayed hypersensitivity (DH) reaction in mice. Local challenge in the airways of these mice resulted in increased numbers of mononuclear cells, mast cells and mucus cells. Depletion of T helper cells in vivo by treatment with monoclonal antibody (GK 1.5) inhibited the DH reaction. This treatment also resulted in a decrease in the number of mononuclear and mucus cells in the lung after intranasal challenge. The DH reaction was transferred to recipients with immune lymph node cells and spleen cells from mice sensitized epicutaneously with PiCl. The recipient mice also showed a slight increase in the number of mononuclear cells in the lung after intranasal challenge. These results indicate that T cells are not only involved in the DH reaction but also in the accompanying lung reaction.

Animals↗
PubMed1987

An improved negative staining technique using a thin quartz membrane as sample support.

A negative staining technique is presented based on the use of 40-60 nm quartz membrane supported by a silicon grid. The quartz membrane is fabricated by thermal growth of silicon dioxide on a silicon substrate followed by an anisotropic silicon etching step giving rectangular holes in the silicon substrate. The hydrophilic membrane is shown to be ideally suited for negative staining due to its spreading characteristics, homogeneity, heat resistance and mechanical stability. Micrographs of phage lambda are presented showing the detailed structure of the tail. A simple method of calculating the number of adsorbed particles based on diffusion limited association is also presented.

Microscopy, Electron↗
PubMed1986

Determination by ellipsometry of the affinity of monoclonal antibodies.

The reaction between monoclonal antibodies and surface-immobilised hapten was studied by ellipsometry, a method allowing absolute measurement of the surface concentration of proteins. Monoclonal antibodies against 2-phenyloxazolone were used and their affinity for the antigen in solution was determined by calculations of the equilibrium constant from data obtained by measuring fluorescence quenching of the hapten due to antibody binding. The binding rate of antibody to surface-immobilised hapten and the dissociation rate of the complex were measured by ellipsometry. The equilibrium constant of the heterogeneous antigen-antibody reaction was determined by a Scatchard plot. The affinity of the antibodies for the antigen was found to be higher in the heterogeneous than in the homogeneous reaction by a factor which varied between different monoclonal antibodies.

Animals↗
PubMed1986

External diffusion in solid-phase immunoassays.

Calculations are presented describing the influence of external diffusion in the kinetics of solid-phase immunoassays. The analysis is concerned with systems where one reactant is immobilized at the surface of a sphere of arbitrary radius. The solution for a plane surface is found as a limiting case. The factors determining whether the reaction is diffusion or reaction controlled are found to be sphere radius, surface concentration of binding sites, forward reaction rate and diffusion constant of reacting species. Means of determining whether the reaction is diffusion or reaction controlled from observable quantities are described. When applied to heterogeneous antibody-antigen binding it is found that normally the binding to cell-size spheres is not limited by external diffusion. However, when applied to solid-phase assays with high surface concentrations of binding sites immobilized at plane surfaces or macroscopic spheres the binding is found to be diffusion limited. The importance of a mass transfer analysis in this case is also discussed.

Antigen-Antibody Complex↗
PubMed1986

Mast cells in oral lichen planus.

Biopsies from lichen planus affected oral mucosa were compared with biopsies from healthy oral mucosa, in terms of the number of mast cells, their location and their morphological alteration at the light microscopic and electron microscopic level. In comparison with the normal oral mucosa an increased number of mast cells was found below the subepithelial infiltrate. This difference was statistically highly significant (p less than 0.001). In the deeper part of the infiltrate mast cells were found to contain granules which presented an altered morphology upon electron microscopic examination. These cells had many of the ultrastructural changes that have been reported for mast cells undergoing degranulation. The present morphological observations suggest that mast cells participate in the recruitment of lymphocytes to the subepithelial infiltrate.

Adult↗
PubMed1986

Cyclophosphamide-mediated enhancement of delayed hypersensitivity reactions in the lung.

The appearance of mononuclear cells, mast cells and mucous cells in the airways was studied in Balb/c mice in relation to cell-mediated immunity reflected as delayed hypersensitivity (DH). The animals were pretreated with cyclophosphamide (Cy) to increase cell-mediated immunity and to decrease the influence of antibodies. Mice pretreated with Cy and epicutaneously sensitized with picrylchloride (PiCl) had stronger DH reactions as compared with sensitized mice not pretreated with Cy. The Cy treatment decreased the IgG antibody formation after sensitization. The Cy-pretreated, sensitized and challenged mice had increased numbers of mucus-producing cells and to some extent also mononuclear cells in their lungs compared with sensitized and challenged non-Cy-treated animals. However, the mucous cell numbers were also increased in Cy-treated, but nonsensitized mice in which most of the airway epithelium had differentiated into mucus-containing cells. The present results indicate that local cell-mediated immunity involves the appearance of mononuclear cells and mucus-producing cells in the lung. This inflammatory reaction is enhanced by Cy treatment, although mucous cell differentiation seems to be induced by exposure to Cy alone.

Animals↗
PubMed1985

Dissociation of antibodies bound to surface-immobilized antigen.

The dissociation of antibodies bound to surface-immobilized antigen was investigated by the ELISA, using a hapten (TNP) as antigen. Antibody binding was found to be stable, and no half-time of dissociation could be defined within 69 h. The role of the bivalence of antibodies and the difference between a homogeneous and a heterogeneous reaction was investigated by comparing the dissociation rate of antigen-antibody complexes formed by monovalent Fab fragments from surface-immobilized antigen and the dissociation rate of TNP-lysine from antibodies in a homogeneous liquid phase. Fab fragments were found to dissociate with a half-time value of about 16 h, whereas the homogeneous binding of TNP-antibody dissociated with a half-time of less than 4 h, indicating that both the bivalence of antibodies and the solid phase contributed to the stability of surface-bound antigen-antibody complexes. Qualitative differences between antibodies produced by different clones in a polyclonal antibody response to TNP was investigated by a spot assay. The results indicated that a minority of the antibodies produced had the capacity of binding practically irreversibly to solid-phase-immobilized antigen. The impact of the results on the interpretation of data from solid-phase assays is discussed together with the biological importance of the findings.

Animals↗
PubMed1985

Calibration by ellipsometry of the enzyme-linked immunosorbent assay.

The enzyme-linked immunosorbent assay (ELISA) was analyzed with regard to possible diffusion limitations of the binding reaction. The absorbance values of the assay were found to follow the time and concentration relations that would occur when diffusion of antibody to the surface is the rate limiting step. This relationship was used in order to calibrate the absorbance values of the ELISA with antibody concentration by ellipsometry, which itself allows direct measurement of the amount of antibody bound to the solid phase.

Animals↗
PubMed1985

A gel casting technique allowing rapid and sensitive quantitation of antibodies by diffusion-in-gel enzyme-linked immunosorbent assay.

A technique is described which allows rapid and sensitive quantitation of antibodies by diffusion towards an antigen-coated surface through a gel of wedge-shaped profile. A sensitivity of 0.16 micrograms antibody per ml solution was obtained after 45 min incubation with stirring at 22 degrees C and 0.08 micrograms/ml could be detected after 90 min incubation with stirring or with incubation at 37 degrees C.

Animals↗
PubMed1985

A diffusion limited reaction theory for a solid-phase immunoassay.

Theoretical calculations are presented, describing the kinetics of a solid-phase immunoassay where reactants are allowed to diffuse through a gel wedge in the bottom of a circular basin. The analysis is based on the assumption of a diffusion rate limited reaction at the underlaying surface. The influence of initial concentration, incubation time, temperature and the effect of stirring are predicted by the theoretical model. Experimental data are found to follow the theoretical model with parameters consistent with previous values.

Diffusion↗
PubMed1985

Regional and systemic immune responses to trinitrophenyl derivatives after intranasal and subcutaneous sensitization of mice.

The immune responses and accompanying inflammatory local reactions were analyzed in mice sensitized subcutaneously (SC) or intranasally. Administration of picrylsulfonic acid (PSA) by both routes for two 2- or 1-week periods with a 4-week interval resulted in delayed hypersensitivity responses. Serum antibodies of the IgG and IgE and some of the IgA isotype were found, particularly in SC-sensitized animals. The latter animals also had levels of IgG antibodies in their bronchial fluid. Lymph node cells from mice sensitized for 2-week periods demonstrated high spontaneous proliferation. After culture together with spleen cells, these cells exhibited considerable numbers of mast cells, particularly after stimulation with pokeweed and antigen. The lungs from mice sensitized intranasally revealed increased numbers of mononuclear cells around large vessels and mucous cells in the bronchiolar epithelium, although there were individual differences between the animals. The mast cell numbers in the lungs were only slightly increased compared with numbers in nonimmunized animals subjected to ether anesthesia. Animals injected SC with PSA exhibited increased numbers of mast cells in their lungs compared with control mice. Mice sensitized with trinitrophenylated human serum albumin demonstrated some differences in their immune reactivity compared with animals immunized with PSA. Thus, no obvious delayed hypersensitivity appeared, but the IgG antibody titers were higher, and the IgE antibody titers were lower. The cellular responses assessed histologically demonstrated higher mononuclear cell numbers and lower mast cell numbers compared with those observed in animals sensitized with PSA.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Intranasal↗
PubMed1985

Immune stimulated regional inflammatory responses mediating lung reactivity in rats.

Daily sensitization of SPF BNxWi/Fu rats with ovalbumin (OA) in aerosol during 2-week periods with a 4-week interval resulted after 7 weeks in IgE, IgA and IgG antibodies in serum and bronchial fluid. After cultivation of the regional, axillary, brachial and mediastinal (ABM) lymph node cells, IgE antibodies were found in the culture supernatant. Such antibodies were not found in culture supernatants of spleen and inguinal lymph nodes. Regional formation of IgE antibodies was also noted in the ABM lymph node cell culture supernatants after subcutaneous (s.c.) injections of 100 ng OA in the neck region. When the injections were given in the tail-root region, the inguinal but not the ABM lymph nodes produced the IgE antibodies. The s.c. sensitization induced inconsistent and rather low IgG and no IgA antibody responses. The aerosol but not the s.c. sensitization induced accumulations of mononuclear cells and mucous cells in the lungs. Clinically, the rats sensitized s.c. in the neck region reacted to aerosol and intravenous (i.v.) challenge as early as 1 week after sensitization had started, whereas the animals sensitized in the tail-root regions reacted 7 and 8 weeks after repeated sensitization. The animals sensitized by aerosol showed only weak clinical reactivity after i.v. challenge.

Animals↗