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Biomedical subjects

M Carlsson

Publications and source records attributed to M Carlsson.

At least 109 records · Page 6Linked to original sources
PubMed1994

TNF-alpha and IL-6 induce differentiation in the human basophilic leukaemia cell line KU812.

The basophilic leukaemia cell line KU812 can be induced to differentiate into basophil-like cells in vitro when exposed to supernatant from the Mo T-cell line. KU812 cells express affinity receptors for IgE, produce histamine and tryptase and have the capacity for IgE-mediated histamine release. In this study we have examined the cytokines, produced by the Mo cell line, which are responsible for the observed differentiation-inducing effect in the KU812 cell line. It was shown that interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF-alpha) induced differentiation in the KU812 cells and that these cytokines were responsible for the differentiation-inducing effect of the Mo supernatant. Other cytokines tested, IL-1 beta, IL-2, IL-4, IL-5, IL-8, granulocyte-macrophage colony-stimulating factor (GM-CSF) and nerve growth factor (NGF) were without effect on the KU812 cells. KU812 was also shown to express receptors for both TNF-alpha and IL-6 after 3 days cultivation with conditioned media from the Mo T-cell line. Untreated cells showed no detectable levels of TNF-alpha or IL-6 receptors indicating induction of these receptors during differentiation. Spontaneous differentiation was shown to occur under serum-free conditions which may be the result of endogenous IL-6 production through an autocrine loop. The activity of TNF-alpha and IL-6 could be blocked by specific monoclonal antibodies (mAb) to the respective cytokine.

Basophils↗
PubMed1993

Biochemical and in vivo properties of high purity factor IX concentrates.

The purified factor IX concentrates Nanotiv (Kabi Pharmacia), Immunine (Immuno), Factor IX VHP (Bio-transfusion), Alphanine (Alpha) and Mononine (Armour) have been studied in vitro and compared with the prothrombin complex concentrates (PCCs) Preconativ (Kabi Pharmacia) and Prothromplex TIM4 (Immuno). The measured values for factor IX coagulant activity (IX:C) were in good agreement with the manufacturer's label values. In contrast to the PCCs, most of the purified concentrates were virtually devoid of other vitamin K-dependent coagulation factors, the inhibitors protein C and S as well as fibrinogen, fibronectin and immunoglobulins. Indicators of thrombin generation, namely prothrombin fragments 1 and 2 (F 1 + 2) and thrombin-antithrombin complex (TAT), were present in varying amounts in all preparations. The specific activity in the purified concentrates exceeded that in the PCCs by a factor of 50-100. Some differences in purity were found between the purified concentrates. In vivo, Nanotiv was compared with Preconativ and Immunine with Prothromplex TIM4 in crossover studies in patients with severe hemophilia B, and Mononine was tested in a single drug study. Most of the preparations yielded postinfusion increases in TAT, but not in F 1 + 2. Pharmacokinetic variables were analyzed with non-linear curve-fitting combined with model-independent methods. In retrospective comparisons, there were no apparent differences between Nanotiv, Preconativ and Mononine, whereas in vivo recovery seemed lower and the apparent clearance higher for Immunine and Prothromplex. Purified factor IX concentrates were successfully used as cover for surgery or in immune tolerance induction.

Adult↗
PubMed1993

Familial thrombophilia due to a previously unrecognized mechanism characterized by poor anticoagulant response to activated protein C: prediction of a cofactor to activated protein C.

Although patients with thromboembolic disease frequently have family histories of thrombosis, well-defined defects such as inherited deficiencies of anticoagulant proteins are found only in a minority of cases. Based on the hypothesis that a poor anticoagulant response to activated protein C (APC) would predispose to thrombosis, a set of new coagulation assays was developed that measure the anticoagulant response in plasma to APC. A middle-aged man with a history of multiple thrombotic events was identified. The addition of APC to his plasma did not result in a normal anticoagulant response as measured by prolongation of clotting time in an activated partial thromboplastin time (APTT) assay. Four of the proband's relatives had medical histories of multiple thrombotic events, and they and several other family members responded poorly to APC in the APTT-based assay. Subnormal anticoagulant responses to APC were also found in factor IXa- and Xa-based assays. Several possible mechanisms for the observed phenomenon were ruled out, such as functional protein S deficiency, a protein C-inhibitory antibody, or a fast-acting protease inhibitor against APC. Moreover, restriction fragment-length polymorphism analysis excluded possible linkage of the underlying molecular defect to factor VIII and von Willebrand factor genes. We now describe a previously unrecognized mechanism for familial thromboembolic disease that is characterized by poor anticoagulant response to APC. This would appear to be explained best by a hypothesized inherited deficiency of a previously unrecognized cofactor to APC. As we have identified two additional, unrelated cases with thrombosis and inherited poor anticoagulant response to APC, this may constitute an important cause for familial thrombophilia.

Adult↗
PubMed1993

A light emitting diode microspectrophotometer: intracellular Ca2+ measurements in isolated stretch receptor.

A microspectrophotometer was designed to measure absorbance changes in single cells. The device utilizes sequentially activated light emitting diodes (LED) to provide different wave lengths of light. The instrument has the advantage of relative simplicity and less cost compared to other devices. The spectrophotometer was tested by measuring absorbance changes of the metallochromic Ca2+ indicator Arsenazo III (AIII) injected into the crayfish (Astacus astacus) stretch receptor. Under the conditions described the detection limit of the concentration of AIII was 0.05 mM and absorbance changes of 0.0005 can be reliably determined which correspond to a detection limit of 10-20 nM for free Ca2+ changes assuming a light path length of 0.003 cm and an apparent dissociation constant (KD) of 2 microM for the Ca(2+)-AIII complex. The upper frequency limit of the device is 3000 Hz. The absorbance measurements of AIII injected into the crayfish stretch receptor neurons revealed a Ca(i) of 375 +/- 177 nM (mean +/- SD: 14 cells). LiCl substituted for NaCl increased Ca(i) 45-100 nM in different cells, suggesting that a Na+ gradient is necessary for Ca2+ homeostasis in this receptor.

Animals↗
PubMed1993

Interleukin-4 (IL-4) enhances homotypic adhesion of activated B-chronic lymphocytic leukaemia (B-CLL) cells via a selective up-regulation of CD54.

It is well established that cell-to-cell contact modifies cytokine signalling but little is known on the role of homotypic cell adhesion for proliferation and differentiation of B cells. Homotypic adhesion involves mainly the interaction between the adhesion molecules Leukocyte Function Antigen-1 (LFA-1) and its ligand CD54 (ICAM-1). A well-characterized B-chronic lymphocytic leukaemia (B-CLL) clone (I-83) was used as a source of monoclonal B cells inducible to DNA synthesis and differentiation by using 12-O-tetradecanoyl-phorbol-13-acetate (TPA) in combination with interleukin-4 (IL-4) and thioredoxin (Trx)-containing supernatant from a T-cell hybridoma (BSF-MP6). This paper shows that IL-4 alone was able to induce aggregation of B-CLL cells and to strongly enhance TPA+BSF-MP6-induced aggregation. The results from studying the expression of CD11a and CD18, the two subunits of LFA-1, and CD54 during stimulated DNA synthesis and differentiation suggest that IL-4-induced, or enhanced, aggregation was mainly mediated by a selective up-regulation of CD54. It was further demonstrated by antibody blockade to either CD11a, CD18 or CD54 that aggregation could be inhibited without affecting induced DNA synthesis or differentiation.

Antibodies↗
PubMed1993

Pharmacokinetic dosing in prophylactic treatment of hemophilia A.

The aim of this study was to investigate individual pharmacokinetics as a tool for dosing of factor VIII (FVIII) in severe hemophilia A. It is assumed that effective prophylaxis against bleedings is maintained if the plasma FVIII:C activity is kept above 1 U/dl, and the present study is based on this assumption. A current standard dosage regimen for FVIII is 25-40 U/kg up to three times weekly. However, there is considerable individual variation in the pharmacokinetics of FVIII:C. Individual pharmacokinetic data were used to computer-simulate plasma activity curves after repeated doses in 8 patients. Going from prophylaxis regimens of normally 2-3 infusions per week to dosing every 2 days would theoretically reduce their average FVIII consumption by 43% with maintained or increased trough levels of FVIII:C. Daily dosing would reduce their mean FVIII usage by 82%. Modified dosage regimens, infusions every 2 days, were implemented in the patients, and plasma samples were drawn to verify the pharmacokinetic models. The feasibility of the method to generally raise trough levels with a decreased consumption of FVIII was confirmed. Dosing of coagulation factors according to kinetic principles can result in more cost-effective utilization of these very expensive preparations.

Adult↗
PubMed1993

The role of Bcl-2 in the pathogenesis of B chronic lymphocytic leukemia.

At least three categories of genes are envisaged to be involved in the natural history of B-CLL. First, the genes that are responsible for the transforming event(s) in the (presently unknown) target cell; second, the gene(s) that help the progressive accumulation of malignant cells and finally the gene(s) that cause the progression toward a more aggressive lymphoma. The possibility that the clonal expansion of B-CLL is due to a prolonged life-span of monoclonal B cells rather than to an acceleration of their proliferative activity may now be reinterpreted by taking into account some recent findings on the expression of Bcl-2 gene in B-CLL cells. The Bcl-2 gene product regulates programmed cell death and a number of experiments suggest that Bcl-2 is involved in the selection and maintenance of long-lived memory B cells rescuing them from apoptotic death and leading to their accumulation in the GO phase of the cell cycle. Variant chromosomal translocations have been detected in a small fraction (5-10%) of B-CLL, involving Bcl-2 and the Ig light chain gene. Despite the low percentage of Bcl-2 rearrangements the expression of mRNA and protein is appreciable in most samples of fresh B-CLL cells in an amount comparable to that observed in Karpas 422 cells, which contain a t(14;18).(ABSTRACT TRUNCATED AT 250 WORDS)

B-Lymphocytes↗
PubMed1993

A combination of granulocyte colony-stimulating factor and erythropoietin may synergistically improve the anaemia in patients with myelodysplastic syndromes.

In an attempt to obtain a synergistic effect on the hemoglobin levels in anaemic patients with myelodysplastic syndromes (MDS), granulocyte colony-stimulating factor (G-CSF) and erythropoietin (epo) were combined in a clinical phase II trial. Twenty-two patients with MDS were included in the study. G-CSF was given alone for six weeks and then in combination with epo for the following twelve weeks. Eight (38%) of 21 evaluable patients showed a significant increase in hemoglobin. One patient with a previous response and subsequent failure to epo alone improved after the addition of G-CSF. Responses were more frequent in patients with less advanced pancytopenia, lower endogenous levels of serum-epo and in those with ring sideroblasts in the bone marrow. The response frequency of 38% is higher than in any study of epo as monotherapy. Moreover, patients with ring sideroblasts, who respond poorly to epo alone, showed a response rate of 60%. Our findings suggest a synergistic in vivo effect of granulocyte-CSF and erythropoietin in patients with myelodysplastic syndromes.

Adult↗
PubMed1993

Interleukin-2 enhances the production of tumor necrosis factor-alpha in activated B-type chronic lymphocytic leukemia (B-CLL) cells.

Tumor necrosis factor-alpha (TNF-alpha) has recently been implicated as a regulator growth and differentiation of normal and malignant B cells. We utilized a selected clone (I-83) of primary resting B-type chronic lymphocytic leukemia (B-CLL) cells, inducible to activation, growth and differentiation in vitro, as a model system to study the possible role of TNF-alpha as an autocrine growth factor for such cells. Our results show that unstimulated I-83 B-CLL cells produced a low level of TNF-alpha mRNA, as shown by Northern blot analysis, and cytoplasmic TNF-alpha, determined in individual cells by immunocytochemistry. Secreted TNF-alpha could, however, not be detected in the medium by ELISA. TNF-alpha synthesis and secretion was, however, induced to high levels by stimulation of the B-CLL cells with interleukin-2 (IL-2) after activation by 12-O-tetradecanoylphorbol-13-acetate (TPA) or Staphylococcus aureus Cowan strain I (SAC) and B-cell stimulatory factor-MP6 (thioredoxin). A moderate increase in TNF-alpha secretion was also induced by TPA or IL-2 alone. IL-4 did not have any major effects on the production of TNF-alpha in activated cells, but inhibited the IL-2-induced production of TNF-alpha in SAC-activated cells. The cell surface expression of TNF-alpha receptors (TNF-R), as determined by binding assay using 125I-labelled recombinant TNF-alpha (rTNF-alpha), was also induced after SAC or TPA activation, but shed receptors (TNF-binding proteins) were only observed after TPA activation. Exogenously added rTNF-alpha in combination with TPA or SAC induced a high level of DNA synthesis in I-83 B-CLL cells. The increased endogenous production and secretion of TNF-alpha during induced growth stimulation, the induced expression of TNF-R, and the mitogenic effect of TNF-alpha on activated B-CLL cells raise the question whether TNF-alpha may function as an autocrine co-stimulator of B-CLL cell growth as recently suggested. anti-TNF-alpha and anti-TNF-R antibodies, however, failed to inhibit the IL-2- and IL-4-induced proliferation of activated I-83 B-CLL cells.

DNA, Neoplasm↗
PubMed1992

Structure of native and apo carbonic anhydrase II and structure of some of its anion-ligand complexes.

In order to obtain a better structural framework for understanding the catalytic mechanism of carbonic anhydrase, a number of inhibitor complexes of the enzyme were investigated crystallographically. The three-dimensional structure of free human carbonic anhydrase II was refined at pH 7.8 (1.54 A resolution) and at pH 6.0 (1.67 A resolution). The structure around the zinc ion was identical at both pH values. The structure of the zinc-free enzyme was virtually identical with that of the native enzyme, apart from a water molecule that had moved 0.9 A to fill the space that would be occupied by the zinc ion. The complexes with the anionic inhibitors bisulfite and formate were also studied at neutral pH. Bisulfite binds with one of its oxygen atoms, presumably protonized, to the zinc ion and replaces the zinc water. Formate, lacking a hydroxyl group, is bound with its oxygen atoms not far away from the position of the non-protonized oxygen atoms of the bisulfite complex, i.e. at hydrogen bond distance from Thr199 N and at a position between the zinc ion and the hydrophobic part of the active site. The result of these and other studies have implications for our view of the catalytic function of the enzyme, since virtually all inhibitors share some features with substrate, product or expected transition states. A reaction scheme where electrophilic activation of carbon dioxide plays an important role in the hydration reaction is presented. In the reverse direction, the protonized oxygen of the bicarbonate is forced upon the zinc ion, thereby facilitating cleavage of the carbon-oxygen bond. This is achieved by the combined action of the anionic binding site, which binds carboxyl groups, the side-chain of threonine 199, which discriminates between hydrogen bond donors and acceptors, and hydrophobic interaction between substrate and the active site cavity. The required proton transfer between the zinc water and His64 can take place through water molecules 292 and 318.

Anions↗
PubMed1992

Growth- and differentiation-associated expression of bcl-2 in B-chronic lymphocytic leukemia cells.

The bcl-2 gene is translocated into the Ig loci in about 80% of human follicular lymphomas and in 10% of B-type chronic lymphocytic leukemias (B-CLL), resulting in a high level of expression. We have compared the expression of bcl-2 transcripts and protein in B-CLL cells in their normal equivalent CD5+ B cells and in normal B-cell populations representative of different in vivo and in vitro stages of activation and proliferation. We report here that bcl-2 was expressed in 11 of 11 cases of CD5+ B-CLL clones, contrasting with the absent expression in normal CD5+ B cells. Activation of 173 and 183 B-CLL cells by phorbol esters (12-O-tetradecanoylphorbol-13-acetate [TPA]) to IgM secretion without concomitant DNA synthesis resulted in a rapid but transient downregulation of bcl-2 expression. In contrast, the reduction of bcl-2 at both the messenger RNA and protein levels was sustained after mitogenic stimulation, suggesting that bcl-2 expression and proliferation are inversely related in these cells. This notion was further supported by immunocytochemical analysis showing that bcl-2 was primarily expressed in small resting lymphocytes and in cells differentiating to the plasma cell stage, but less expressed in Ki67-positive proliferating B blasts. Moreover, it was also supported by the low level of bcl-2 in exponentially growing Epstein-Barr virus-carrying lymphoblastoid and B-CLL cell lines. The regulation of bcl-2 expression in B-CLL resembled that of normal tonsillar follicular B cells, in which a high level of expression was found in resting mantle zone B cells but not in the proliferating germinal center B cells. Based on these findings and the role of bcl-2 in maintaining B-cell memory, we propose that the phenotype of B-CLL cells corresponds to a mantle zone memory-type B cell.

Aged↗
PubMed1992

Serum levels of lymphokines and soluble cellular receptors in primary Epstein-Barr virus infection and in patients with chronic fatigue syndrome.

The immunopathology in primary Epstein-Barr virus (EBV) infections and in chronic fatigue syndrome was studied by examining serum levels of interleukins (IL) and of soluble T cell receptors in serum samples. Serum samples were from patients during and 6 months after primary EBV-induced infectious mononucleosis and from patients with chronic fatigue syndrome and serologic evidence of EBV reactivation. Markers for T lymphocyte activation (soluble IL-2 and CD8) and for monocyte activation (neopterin) were significantly elevated during acute infectious mononucleosis but not in patients with chronic fatigue syndrome. Interferon-alpha, IL-1 beta, and IL-6 levels were not significantly increased in any patient group but inferferon-gamma levels were significantly increased during the acute phase of infectious mononucleosis. The levels of IL-1 alpha were significantly higher than in controls both in patients with infectious mononucleosis and in those with chronic fatigue syndrome. In the latter, the lack of most markers for lymphocyte activation found in patients with infectious mononucleosis makes it less likely that EBV reactivation causes symptoms.

Adolescent↗