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Biomedical subjects

M Hansson

Publications and source records attributed to M Hansson.

At least 127 records · Page 7Linked to original sources
PubMed1989

Structural assessment of the N-linked oligosaccharides of cell-CAM 105 by lectin-agarose affinity chromatography.

The N-linked oligosaccharides of cell-CAM 105, a glycoprotein involved in the intercellular adhesion between rat hepatocytes, were studied by sequential lectin-agarose affinity chromatography of desialylated, [14C]-labelled glycopeptides. These glycopeptides were obtained by extensive pronase digestion followed by N-[14C]acetylation of the peptide moieties and desialylation by mild acid hydrolysis. Assuming that all glycopeptides were radiolabelled to the same specific radioactivity, Concanavalin A-Sepharose chromatography indicated that the majority of the glycans (84%) were of the complex-type of which approximately half were bi-antennary structures. The remainder of the glycans comprised oligomannose-type structures and/or incomplete bi-antennary structures. Pisum sativum lectin-agarose chromatography revealed that part of the bi-antennary glycans contained a fucose residue alpha(1-6)-linked to the N-acetylglucosamine which is attached to asparagine. Furthermore, the presence of tri-, and tetra- and/or tri'-antennary complex-type glycans was demonstrated by chromatography on immobilized Phaseolus vulgaris leukoagglutinating phytohemagglutinin and Aleuria aurantia lectin (AAL). AAL-agarose chromatography furthermore indicated the presence of alpha(1-3)-linked fucose in part of these glycopeptides, whereas no alpha(1-6)-linked fucose could be detected in these structures. The degree of beta-galactosylation of the complex-type glycans was investigated by chromatography on Ricinus communis agglutinin-agarose. The results indicated that only part of the bi-antennary glycans were completely beta-galactosylated. Similarly, at least three beta-galactose residues were present in only a part of the tri-, and tetra- and/or tri'-antennary glycans.

Adenosine Triphosphatases↗
PubMed1989

Cimetidine as an immune response modifier.

Cimetidine, a selective histamine-2 receptor antagonist, has attracted interest because of its potential as an immune response-modifying drug. Most data suggest that cimetidine has a stimulatory action on the immune system, possibly by blocking of receptors on subsets of T-lymphocytes and inhibiting histamine-induced immune suppression. Several studies have shown that cimetidine can affect the relative number of CD8 + ve lymphocytes and increase the NK cell activity as well as the antibody-dependent cellular cytotoxicity. Cimetidine has also been used successfully to restore immune functions in patients with malignant disorders, hypogammaglobulinemia and AIDS-related complexes.

Adjuvants, Immunologic↗
PubMed1989

Cell-surface location and molecular properties of cell-CAM 105 in intestinal epithelial cells.

Cell-CAM 105 is involved in intercellular adhesion of isolated rat hepatocytes in vitro. In addition to liver, cell-CAM 105 occurs in several different epithelia, in platelets, and in granulocytes. In this paper we present a detailed analysis of cell-CAM 105 in the small intestinal mucosa. Isolated rat intestinal epithelial cells and brush-borders were investigated by indirect immunofluorescence. A strong fluorescence occurred in the brush-border region and a much weaker staining was seen in the lateral cell surfaces. The brush-border staining was heterogeneous and concentrated to the periphery where brush-border microvilli from adjacent cells are in contact with each other. It is suggested that cell-CAM 105 might mediate binding between the outer surfaces of neighboring microvilli. Immunoblotting and electrophoretic analyses of the biochemical properties of intestinal cell-CAM 105 demonstrated significant differences compared with cell-CAM 105 isolated from liver. Intestinal cell-CAM 105 was smaller than liver cell-CAM 105 under reducing conditions, whereas it was larger than liver cell-CAM 105 under non-reducing conditions. Chemical reduction decreased the size of intestinal cell-CAM 105, but increased the size of liver cell-CAM 105. Our interpretation of these data is that intestinal cell-CAM 105 occurs as a part of a macromolecular complex. This interpretation was supported by electrophoretic analyses of intestinal cell-CAM 105 isolated by immunoaffinity chromatography on anti-cell-CAM antibodies. In addition to cell-CAM 105, this material contained several other proteins of lower molecular weight than cell-CAM 105. These data suggest that intestinal cell-CAM 105 participates in cell-surface interactions that may regulate the structure and function of the apical brush-border regions of the intestinal epithelial cells.

Adenosine Triphosphatases↗
PubMed1989

Comparison between two Microtox test procedures.

A comparison between the two Microtox test procedures, the standard test and the 100% test, has been made. In the standard Microtox bioassay, effluents can be tested up to a concentration of 45%. The 100% test method, however, has been developed for screening effluents with an EC50 value greater than 45%. The relationship between 5-min EC50 values according to the two methods has been studied with a two-way ANOVA analysis for 14 effluents or process waters and one unpurified municipal wastewater sample. All samples were tested twice with a 3-month interval. An F ratio of 15.46 (n = 56) showed that the test methods differed significantly at the 0.1% level. Nevertheless none of the samples had a drastically different EC50 value when tested by the two methods. Both the treatment of the bacteria and the calculation of the EC50 values, which also affect the width of the 95% fiducial limits, differ in the two procedures. The confidence intervals were found to be 10.4 times broader in the 100% tests than in the corresponding standard test. Although the methods differ from each other both in performance and in statistical comparison of the results, both of them could be useful as prescreening methods for determining toxicity to aquatic organisms.

Bacteria↗
PubMed1988

Dioxins and dibenzofurans in blood and adipose tissue of Agent Orange-exposed Vietnam veterans and matched controls.

Vietnam veterans who were heavily exposed to Agent Orange exceeded matched control subjects in both blood and adipose tissue levels of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) but not in the levels of the 12 other 2,3,7,8-substituted dioxins and dibenzofurans that were detected. Since only TCDD among these compounds was present in Agent Orange but all are present in the population of the industrialized world, it is likely that the elevated TCDD levels arose from wartime exposure. The high correlation (r = +.89) of blood with adipose tissue level suggests that there may be a mobile equilibrium between them and that blood measurement could replace adipose tissue measurement of TCDD levels, making the collection of human data less invasive.

2,4,5-Trichlorophenoxyacetic Acid↗
PubMed1988

In vivo function of natural killer cells as regulators of myeloid precursor cells in the spleen.

In order to study the in vivo effect that natural killer (NK) cells may have on hematopoietic precursor cells in the autologous host, NK-depleted mice were constructed by injection of an anti-NK-1.1 monoclonal antibody. Only the spleen, and not the bone marrow, of such NK-depleted mice shows an increase in the number of myeloid precursur cells able to form colonies in soft agar as compared to control mice with normal levels of NK activity. The increase in number of hematopoietic immature cells due to lack of a regulatory cell (i.e. NK cell) is selective for the committed myeloid precursur cells, and not evident for erythroid or pluripotent progenitor cells. This is direct evidence in support of the hypothesis that NK cells in the autologous host serve as a regulator of extramedullary myelopoiesis.

Animals↗
PubMed1987

Progenitor and pre-B lymphocytes transformed by Epstein-Barr virus.

By rosetting with SRBC coupled to rabbit-anti-human IgM, the surface IgM-negative cells of human fetal bone marrow were enriched, and subsequently infected and transformed by Epstein-Barr virus (EBV). Single clones of the transformed cells were obtained. Ninety percent of the resulting cell clones were surface-immunoglobulin-negative, and of 8 clones which were further studied, 5 lacked intracellular, cytoplasmic Ig as measured by immunofluorescence. Control cell clones derived from the same material without pre-selection expressed surface Ig and also secreted Ig. Utilization of a panel of B-cell-specific monoclonal antibodies (MAbs) showed no difference between the cell clones expressing surface Ig and those that did not. The progenitor B-cell lines did not show a phenotype resembling that of cell lines derived from B-cell malignancies, such as high agarose clonability. In spite of their immature Ig-phenotype, these clones showed rearrangement of at least one heavy chain Ig-allele. Efforts to induce differentiation in these clones were unsuccessful. These clones may represent progenitor B cells, or B cells with faulty heavy-chain rearrangement. EBV can apparently be used as a tool to derive cell lines representing different levels of B-cell differentiation, and can also transform immature B cells, which may be useful in the analysis of B-cell differentiation.

Antibodies, Monoclonal↗
PubMed1987

Fibronectin concentrations in lung lavage fluid after inhalation exposure to low levels of metals.

Groups of rabbits were exposed by inhalation to chlorides of cobalt, nickel, and manganese as well as to tri- and hexavalent chromium at metal concentrations ranging from 0.4 to 3.9 mg/m3 for 1-4 months (5 days/week, 6 hr/day). Fibronectin content and lysozyme (muramidase) activity in lavage fluid were measured after all treatments and in alveolar macrophages after treatment with nickel chloride. In the lavage fluid no marked changes were seen in fibronectin content and lysozyme activity after exposure to tri- or hexavalent chromium or manganese. Nickel exposure significantly decreased the lysozyme activity in the lavage fluid and in the macrophages whereas the fibronectin content was unchanged in the lavage fluid and significantly increased in the macrophages. Both fibronectin content and lysozyme activity were increased markedly in the lavage fluid after cobalt exposure.

Administration, Inhalation↗
PubMed1987

Plasma fibronectin levels during daily plasmapheresis.

Plasma fibronectin concentrations were studied in 10 patients with multiple myeloma. After plasma exchange for 3 d (2.5-3 l plasma daily) the plasma fibronectin decreased to about 50% of the initial level. Resynthesis of fibronectin seemed to increase during 3 d of plasmapheresis, and was sufficient to normalize plasma fibronectin concentration. The plasma fibronectin concentration reached the initial level within 2 d after interrupting plasmapheresis in spite of concurrent cytotoxic treatment. The patients studied showed no signs of infection.

Fibronectins↗
PubMed1986

Comparison of the Microtox test with the 96-hr LC50 test for the harpacticoid Nitocra spinipes.

A comparison between the static 96-hr LC50 test with the brackish water harpacticoid Nitocra spinipes and the Microtox (Beckman Instruments, Inc.) screening method has been done. The relationship between the two bioassays were evaluated for 16 pure and technical chemicals and 11 complex effluents from different types of industries. The correlation between the 96-hr LC50 values for Nitocra and the 5-, 15-, and 30-min effective concentration (EC50) for pure and technical chemicals had R2 values ranging between 0.751 and 0.796. A somewhat better correlation was shown between the two test methods for the complex effluents with R2 values ranging from 0.903 to 0.927. The sensitivity of the two tests for the actual types of samples were found to be in the same order of magnitude. Investigations concerning pretreatments of three chemicals (dibutyl phthalate, 1-octanol, and pentachlorophenol) fairly insoluble in water (less than 1000 mg/liter) have been done. Three solvents, acetone, dimethyl sulfoxide (DMSO), and propylene glycol, were studied with the Microtox system in a low concentration (500 mg/liter). Acetone exerted a slightly stimulatory effect and propylene glycol a slight reduction effect on bacterial luminescence.

Acetone↗
PubMed1985

Strategies and techniques for sample collection and analysis: experience from the Swedish PCB accidents.

A series of polychlorinated biphenyl (PCB) fires and explosion in PCB-filled capacitors and transformers is discussed. A sampling program followed by isomer specific determination of trace levels of polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzo-p-dioxins (PCDDs) is described. Data from a series of Swedish PCB accidents are given. In addition to PCDFs and PCDDs, we have also found a series of polychlorinated biphenylenes (PCBPs). Cleaning of contaminated areas was done by vacuum cleaning followed by high pressure washing.

Accidents, Occupational↗
PubMed1985

Assessment of human exposure to polychlorinated dibenzofurans and dioxins.

Fires, explosions and other accidents in polychlorinated biphenyl (PCB)-filled equipment can result in possible exposure of firemen, cleaning personnel and regular workers. Inhalation, dermal exposure and ingestion are the possible routes of exposure. An indirect assessment of the exposure can be made by analyses of wipes, air and water samples and clothes. A direct assessment of exposure can be made by analyses of blood samples, adipose and other tissue samples, feces and bile.

Adipose Tissue↗
PubMed1983

Epstein-Barr virus transformation of human pre-B cells.

In vitro infection of human B lymphocytes with Epstein-Barr virus (EBV) results in establishment of B lymphoblastoid cell lines that reflect normal B cell phenotypes. In this study we have investigated whether immature B cells from fetal bone marrow and liver can serve as targets for EBV. The fetal bone marrow cells were readily transformed by EBV. Among the resulting cell lines, five were surface Ig (sIg)-negative. Three B cell-associated antigens defined by monoclonal antibodies were expressed to the same extent on the fetal cell lines, whether they belonged to the sIg- or sIg+ group. The various differentiation stages that these cell lines may represent are discussed.

Antibody-Producing Cells↗
PubMed1983

Human natural killer cells can inhibit clonogenic growth of fresh leukemic cells.

The effect of allogenic human natural killer (NK) cells on fresh leukemic cells from three patients was investigated. The low levels of leukemic target cell lysis in the conventional 51Cr-release assay contrasted with a pronounced inhibitory effect on the colony growth of the clonogeneic leukemic target cells (L-CFC). The ability of allogeneic lymphocytes to inhibit L-CFC increased if they were pretreated with interferon (IFN), which also increased their NK activity, monitored in parallel cytotoxicity assay, against K562. Furthermore, cell separation procedures, based on differences in density among nonadherent lymphocytes, revealed that only NK cell containing fractions were inhibitory. We have also compared the susceptibility to NK-mediated L-CFC inhibition of IFN pretreated leukemic target cells with that of nontreated target cells. As in the case of NK lysis in general, this pretreatment of target cells abolished the presumably NK-mediated L-CFC inhibition. In conclusion, these data provide the first indication that NK cells can inhibit the in vitro growth of fresh clonogenic leukemia cells from patients with nonlymphocytic leukemia. The identity of NK cells as effector is strongly suggested by Percoll separation and responsiveness to interferon; the final proof awaits more sophisticated purification of these cells.

Clone Cells↗
PubMed1982

Inhibition of in vitro granulopoiesis by autologous allogeneic human NK cells.

This study demonstrates the ability of human NK cells to inhibit in vitro granulopoiesis of autologous and allogeneic BM cells. NK lytic activity and GM-CFC inhibition was present among nonstimulated lymphocytes from healthy donors and could be increased by treatment of PBL with IFN. Both the cytotoxic NK cells and the GM-CFC inhibitory cells could be enriched for among nonadherent, low-density cells. High-density cells were not cytotoxic, only inhibitory to a small extent, and could become neither cytotoxic nor more inhibitory after IFN treatment. In contrast, low-density cells showed an increased cytotoxic and GM-CFC inhibitory capacity after IFN treatment. The NK mediated GM-CFC inhibition was dependent on cell contact with BM cells, increased with longer preincubation times, and was most efficient against 7-day GM-CFC as compared with 14 day GM-CFC progenitors. In conclusion, these data provide new information about the human NK cell as a potent inhibitor of in vitro granulopoiesis and also as a possible regulator of hematopoiesis in vivo.

Binding, Competitive↗
PubMed1981

Correlation of glycosphingolipids and sialic acid in YAC-1 lymphoma variants with their sensitivity to natural killer-cell-mediated lysis.

Sialoglycoconjugates and glycosphingolipids were quantitated in a series of variants derived from the YAC-1 lymphoma, known to be highly sensitive to natural killer (NK)-cell-mediated lysis. The variants, which had widely diverging sensitivities to NK cells, were obtained by a number of methods, including selection in the presence of NK cells, antibody to H-2, or antibody to the murine leukemia-virus-induced antigen, and by fusion of sensitive cells with an NK-resistant cell line, A9HT. The sensitivities of these cells to NK-cell-mediated lysis did not correlate with their sensitivities to anti-H-2a cytotoxic T cells. While no correlation could be made between the NK-sensitivity of these variants and their total cellular sialic acid, a statistically significant inverse correlation was observed between the levels of percentage neuraminidase releasable surface sialic acid of total labelled sialyl components and sensitivity to NK cells. This correlation with cell surface sialic acid was observed with either endogenous or lymphocytic choriomeningitis virus-induced activated NK cells as effectors. Neuraminidase treatment of insensitive target cells caused a moderate increase in sensitivity but failed to render the resistant targets as sensitive as YAC-1. Analysis of glycosphingolipids among the variants revealed a strong positive correlation between the total cell neutral glycolipid with chromatographic migration of asialo-GM2 and sensitivity to endogenous or activated NK-cell-mediated lysis. Significant correlations were not found with any other neutral glycolipids. However, ganglioside homologues with chromatographic mobility of GM1, GD1a, GD1b, And GT also showed a positive correlation with both endogenous and activated NK-cell-mediated lysis. The ratio of asialo-GM2 to GM2 had a highly significant positive correlation with sensitivity. These correlative results suggest that asialo-GM2 and certain gangliosides could be involved in binding or lytic events in NK cell:target cell interactions, and that high levels of sialic acid and sialylation on the surface may inhibit and/or modify such interactions. Further studies with these YAC variants should be useful for examining the biochemical bases of target cell-effector cell interactions in the NK-system.

Animals↗