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Biomedical subjects

H Nygren

Publications and source records attributed to H Nygren.

106 records · Page 6Linked to original sources
PubMed1979

Ultrastructural localisation of lipopolysaccharide-binding sites with peroxidase-conjugated lipopolysaccharides.

The localisation of lipopolysaccharide-binding sites on erythrocytes with peroxidase-coupled LPS is described. LPS was isolated from Fusobacterium nucleatum (Fus MC-8) by phenol-water extraction. The LPS was coupled to horseradish peroxidase by the two-step method of Avrameas and Ternynck (1971). The biological and serological activities of the conjugated LPS were compared with those of the native material. Peroxidase could be coupled to LPS without significant loss of endotoxic or serological activity. The LPS-peroxidase conjugate could be demonstrated on erythrocytes by light and electron microscopy.

Animals↗
PubMed1979

Diffusion in gel-enzyme linked immunosorbent assay (DIG-ELISA): a simple method for quantitation of class-specific antibodies.

A new method for quantifying class-specific antibodies is presented. The method has been named Diffusion-In-Gel-Enzyme-Linked-ImmunoSorbentAssay (DIG-ELISA), and is briefly as follows. Antiserum ia allowed to diffuse from wells in a gel layered over an antigen-coated plastic surface. The gel is then removed and the preparation is incubated with enzyme-conjugated anti-immunoglobulin. The enzyme is then visualised in situ by a colour reaction produced by pouring a substrate-containing gel over the plastic surface. Bovine serum albumin and rabbit-anti-BSA were used as a model system, and horseradish peroxidase or alkaline phosphatase as enzymes for visualization.

Alkaline Phosphatase↗
PubMed1979

Bacterial lipopolysaccharides bind selectively to lymphocytes from lipopolysaccharide high-responder mouse strains.

Three different concentrations of horseradish peroxidase-labelled lipopolysaccharide (LPS-HRP) were added in vitro to spleen cells from the LPS high-responder strain C3H/Tif and to cells from the low-responder strain C3H/HeJ. After being washed and fixed the cells were exposed to the substrate and prepared for electron microscopy. After addition of 7 and 0.7 microgram/ml of labelled LPS only lymphocytes from the high-responder strain were labelled. About 5-10% of the cells from C3H/Tif bound LPS, which is in accordance with the known frequency of B cells possessing the genetically determined LPS receptor. At the highest dose of labelled LPS (70 microgram/ml) a large proportion of lymphocytes from the low-responder strain also bound LPS. Erythrocytes from both strains bound LPS at all concentrations. It is concluded that LPS-HRP allows the detection at the cellular level of LPS binding to the genetically controlled membrane receptor for LPS.

Animals↗
PubMed1979

Local cholera immunity in mice: intestinal antitoxin-containing cells and their correlation with protective immunity.

Methods for light and electron microscopic identification and characterization of intestinal cholera antitoxin-containing cells (ACC) using peroxidase-labeled immunoreagent are described and used to study the ACC response in mice after immunizations with cholera toxin. Specific ACC appeared in significant numbers after two oral immunizations and increased six- to eightfold with two additional oral boosters, whereas further oral immunizations caused no additional stimulation. Intravenous immunizations had to be repeated seven times before ACC could be detected. After two oral immunizations, most of the ACC were found in the proximal part of the small intestine and no ACC were seen in the colon. This uneven distribution of ACC within the small intestine was eliminated after four oral immunizations, when ACC could also be detected in the colon. The ACC response after four oral immunizations demonstrated a peak at 4 days with far fewer cells present at 2 and 7 days. Electron microscopic studies showed that the ACC were mature plasma cells with the staining localized to the endoplasmic reticulum. Regression analysis of the relationship between the number of ACC and the magnitude of protective immunity against intestinal challenge with cholera toxin indicates a highly significant correlation (r = 0.91, P less than 0.001).

Animals↗
PubMed1979

Human complement activation by lipopolysaccharides from bacteroides oralis, fusobacterium nucleatum, and veillonella parvula.

The properties of different lipopolysaccharide (LPS) preparations to induce C3 conversion in human serum was studied by means of crossed immunoelectrophoresis. C3 conversion by the alternative pathway was evaluated after calcium depletion, and lipid A-dependent activation was measured by means of inhibition with polymyxin B sulfate. LPS from Bacteroides oralis converted Co mainly via the alternative pathway, whereas LPS from Fusobacterium nucleatum and Veillonella parvula const pronounced lipid A-dependent conversion. The results are discussed in relation to the chemical composition of the LPS preparations.

Adult↗
PubMed1979

Studies on the conjugation of horseradish peroxidase to immunoglobulin G via glutaraldehyde.

Horseradish peroxidase was conjugated to immunoglobulin G via glutaraldehyde by a two-step procedure using an increasing excess of peroxidase in the second step reaction. The yield of conjugated monomeric IgG and the amount of free IgG were analyzed by SDS-polyacrylamide electrophoresis and gel-filtration. The antigen binding capacity of the enzyme-antibody conjugates was evaluated by radial immunodiffusion. Conjugation of peroxidase to IgG with a 1:20 molar:molar excess of glutaraldehyde-activated peroxidase resulted in a high yield of conjugated IgG without any detectable amounts of polymers of IgG or residual free IgG. The antigen binding capacity of the conjugate varied between different antigen-antibody systems, but in general it was not significantly different from that of native IgG. The enzyme activity was reduced to 70% of the activity of native peroxidase.

Aldehydes↗
PubMed1978

14-3-2 protein in rat brain.

The distribution of the 14-3-2 protein in rat brain was investigated by immuno-electron microscopy using antiserum to the protein conjugated with peroxidase. 14-3-2 was demonstrated in the nuclear membrane, the endoplasmic reticular membranes and in the plasma membrane of nerve cells. The protein was also localized to the presynaptic densities and to the pre- and postsynaptic membranes. It could not be demonstrated in the membranes of the Golgi complex, inner membrane of mitochondria or in the nucleoplasm of neurons. No 14-3-2 protein was found in astrocytes, oligodendrocytes or in non-neuroectodermal tissue elements.

Animals↗
PubMed1978

Immunoelectron microscopic localization of lipopolysaccharides in the cell wall of Bacteroides oralis and Fusobacterium nucleatum.

Lipopolysaccharides (LPS) have been extracted and purified from two anaerobic gram-negative bacteria: Bacteroides oralis and tfusobacterium nucleatum. Chemical analysis of the preparations showed a great proportion of neutral sugars, mainly glucose, in LPS of B. oralis. In rabbits, LPS of B. oralis induced both immunoglobulin M and G antibodies in contrast to LPS of F. nucleatum, to which only immunoglobulin M antibodies were produced. An immunohistochemical method with horseradish peroxidase-labeled antibodies was used to localize LPS antigens at the ultrastructural level. An electron-dense reaction product, representing an immune complex consisting of bacterial surface antigens and specific rabbit immunoglobulin labeled with peroxidase, was surrounding the cell wall, whereas appropriate controls were negative. The findings of the present study show that LPS of Bacteroides are probably bound to a complex, including glucans, in the outer membrane of the cell wall. LPS of Fusobacterium resemble LPS of other gram-negative bacteria.

Antigens, Bacterial↗
PubMed1978

A kinetic study of the reaction between glutaraldehyde and horseradish peroxidase.

Horseradish peroxidase was reacted with glutaraldehyde under various reaction conditions. The reaction product was, in a second step, bound covalently to aminohexyl groups attached to Sepharose particles. The influence of pH, time and the concentration ratio of enzyme:glutaraldehyde on the reaction was evaluated. A first step reaction with 100-fold molar excess of glutaraldehyde to horseradish peroxidase at pH 9.5 for 2 hr at room temperature results in a high yield of conjugated enzyme with well preserved enzymatic activity.

Aldehydes↗
PubMed1978

Ultrastructural localization of alkaline phosphatases in rat incisor odontoblasts.

The localization of alkaline phosphatases in dentinogenically active rat incisor odontoblasts was studied by means of subcellular fractionation and electron microscopical histochemistry. Subcellular fractionation revealed the predominant phosphatase activity to be present in the microsome fraction and to a lesser extent in the mitochondrial fraction. Adenosine triphosphate degrading enzyme activity was determined in the presence or absence of (+/-)-6(m-bromophenyl)-5, 6-dihydroimidazo(le) (2,1-b) thiazole oxalate (R 8231). Before the histochemical study, the effects on phosphatase activities by aldehyde fixation were studied by biochemical assay. A method of fixation for optimal preservation of phosphatase activity is presented. Phosphatase electron microscopic histochemistry was performed by using ATP as a substrate and with or without addition of the inhibitor R 82319 Precipitates were seen in the membranes of vesicles present in the odontoblast process and the Golgi region. When there were signs of insufficient fixation, precipitates were also seen in the outer membranes of mitochondria. No phosphatase activity was seen in the cell membrane. ATP degrading enzyme activities mediated by nonspecific alkaline phosphatase (APase) and Ca2+ -adenosine triphosphatase thus have the same morphological localization. This close association is consistent with earlier biochemical studies.

Adenosine Triphosphatases↗
PubMed1978

A new method for the study of glutaraldehyde-induced crosslinking properties in proteins with special reference to the reaction with amino groups.

A new method for the study of glutaraldehyde reactions with proteins is presented. Glutaraldehyde-reacted protein is in a first step isolated and then in a second step reacted with aminohexyl groups bound to Sepharose particles. This reaction is linear at low protein concentrations and proceeds rapidly when proteins are reacted with 100-fold and 1000-fold molar excess of glutaraldehyde. This method enables the study of glutaraldehyde-induced crosslinking properties of the modified proteins as an isolated property with high reliability.

Aldehydes↗
PubMed1976

Ultrastructural localisation of proteoglycans in the odontoblast-predentin region of rat incisor.

The localization of proteoglycans in the predentin of the rat incisor was investigated by ultrastructural histochemistry. Ruthenium red stained the cell coat of the odontoblasts as well as intracellular vesicles. There was also a staining of the extracellular matrix, but not of collagen fibers in the predentin. Treatment with the enzyme hyaluronidase prior to staining with ruthenium red abolished the staining of the vesicles and the extracellular matrix but not that of the cell coat. Bismuth nitrate and phosphotungstic acid gave similar staining of odontoblast vesicles and extracellular matrix. It is likely that the stained structures contain proteoglycans. The importance of these proteoglycans and their ultrastructural localization are discussed in relation to intracellular transport and the calcification process.

Animals↗
PubMed1975

Scanning electron microscopic studies of the rat incisor odontoblastema.

A scanning electron microscopic technique was used to investigate the surface structure of dentinogenically active odontoblasts. Thin pieces of rat incisors were fixed, rapidly frozen, freezedried at minus 70 degrees C and fractured to expose new surfaces prior to examination in the SEM. Differences in the appearance of odontoblastic cell surfaces were seen, with the most extensive ridge formations at the distal part of the sides of the odontoblasts. The predentine area displayed a spongy structure which contrasted to the compact appearance of dentine. Results are discussed in relation to previous studies at the light microscopic and transmission electron miscroscopic levels.

Animals↗
PubMedDate not supplied

Urokinase plasminogen activator colocalizes with CD25+ cells in atherosclerotic vessels.

Proteolytic activity in vascular tissue is necessary for cellular migration, remodelling of extracellular matrix and the development of atherosclerotic lesions. Inflammatory cells, mainly macrophages, are numerous in atherosclerotic plaques and may synthesize and secrete proteolytic enzymes. The principal activator of plasminogen in tissues is urokinase plasminogen activator (u-PA). To determine if an activated phenotype of inflammatory cells colocalizes with local expression of u-PA in atherosclerotic vessels, vascular biopsies from 15 patients with peripheral atherosclerotic disease were analyzed by immunohistochemistry on consecutive sections. Anti-CD68 antibodies were used as markers for macrophages and were positive in 14/15 specimens. Anti-CD25 (interleukin-2 receptor-alpha) antibodies were used to identify inflammatory cells with an activated phenotype and were positive in 9/14 CD68+ specimens. The same 9 specimens were positive for u-PA. A positive reaction for u-PA was found only in specimens with CD25+ cells. Specimens with positive reactions for all three antibodies were further analyzed with computer-assisted image analysis. The colocalization with u-PA was higher for CD25 compared to CD68 in all specimens. Mean percentage of the u-PA-positive area in regions positive for cellular markers was 52% (SEM 6%) for CD25 and 19% (SEM 5%) for CD68 (p < 0.01). The results indicated that the activation of macrophages in atherosclerotic vessels may modulate local proteolysis and be of importance in plaque development and stability.

Aged↗
PubMedDate not supplied

Cytotoxicity testing of wound-dressing materials.

A method was developed for testing the cytotoxicity of various bandage-like wound dressings and gel wound dressings. In this method, the ability of human polymorphonuclear neutrophils (PMNs) to initiate a respiratory burst after exposure to the various wound dressings is used as a marker of cytotoxicity. Luminol-amplified chemiluminescence stimulated with opsonised zymosan or phorbol 12-myristate 13-acetate (PMA) is used to measure the degree of activation of the respiratory burst, i.e. the NADPH oxidase activity, after exposure to wound dressings. Opsonised zymosan (material from yeast cell walls) is a phagocytic stimulus that activates the NADPH oxidase by binding to FC-receptors and complement receptors, and functions as an artificial bacterium, whereas PMA activates the NADPH oxidase by direct activation of protein kinase C. NADPH oxidase activity was inhibited by several wound dressings. The down-regulation of the respiratory burst is detrimental to the bactericial effect of PMNs, and can be used as a marker for the cytotoxicity of wound dressing materials.

Bandages↗