Biomedical subjects

A Siegbahn

Publications and source records attributed to A Siegbahn.

86 records · Page 5Linked to original sources

PubMed1990

B-type receptor for platelet-derived growth factor mediates a chemotactic response by means of ligand-induced activation of the receptor protein-tyrosine kinase.

Porcine aorta endothelial cells are devoid of receptors for platelet-derived growth factor (PDGF). We have transfected such cells with cDNA for the PDGF B-type receptor, both the wild-type receptor and a mutant form of the receptor (K634A), in which the putative nucleotide-binding lysine of the protein-tyrosine domain has been changed to alanine. Immunoprecipitation studies of metabolically labeled cells showed that both types of receptors were synthesized and processed to the mature form of Mr 190,000. In cells expressing the wild-type receptor, PDGF-BB, the natural ligand for the B-type receptor, induced membrane ruffling and reorganization of actin. Such a response has previously been seen in cells expressing the natural PDGF B-type receptor in response to PDGF-BB. No such effect was induced in nontransfected cells or in cells expressing the K634A mutant receptor. PDGF was also shown to be chemotactic for cells expressing the wild-type receptor, whereas no chemotactic response was elicited in control cells or in cells expressing the K634A mutant receptor. Our study thus provides formal evidence that the PDGF B-type receptor mediates a motility response including actin reorganization and chemotaxis. Furthermore, the results establish a role for the receptor-associated protein-tyrosine kinase in the transduction of the chemotactic signal.

Animals↗

PubMed1990

Differential effects of the various isoforms of platelet-derived growth factor on chemotaxis of fibroblasts, monocytes, and granulocytes.

The chemotactic activities of three different isoforms of platelet-derived growth factor (PDGF) on fibroblasts, monocytes, and granulocytes of human origin were investigated. PDGF-AB and PDGF-BB induced strong, dose-dependent responses in both fibroblasts and monocytes, whereas PDGF-AA did not stimulate chemotaxis of these cell types. Instead, PDGF-AA inhibited the chemotactic activity of PDGF-AB and PDGF-BB on fibroblasts and monocytes. However, PDGF-AA was not able to block monocyte chemotaxis induced by FMLP. In contrast, in granulocytes, dose-dependent chemotactic responses were obtained with all three isoforms of PDGF. All isoforms gave maximal responses at concentrations between 5 and 20 ng/ml. At higher concentrations the migration was reduced. Reduction and alkylation of the PDGF molecule, which leads to loss of the mitogenic activity, also caused a loss of the chemotactic activities for all three cell types. The data suggest that the various isoforms of PDGF stimulate and inhibit chemotaxis in an isoform- and cell type-specific manner.

Alkylation↗

PubMed1989

Subcutaneous treatment of deep venous thrombosis with low molecular weight heparin. A dose finding study with LMWH-Novo.

Treatment of deep venous thrombosis with low molecular weight heparin (LMWH-Novo, Logiparin) was carried out with two different doses of Logiparin, 75 XaI U/kg b.w. twice daily and 150 XaI U/kg b.w. once daily subcutaneously for 5 days. Simultaneously warfarin was given from the first day of heparin treatment. Mean age of the twenty patients was 65 years and one third was females. No serious side effects, hematomas, pulmonary emboli or signs of recurrent thrombosis occurred during treatment with either dose regime. Venografic assessment with Marder scoring one week after initiation of Logiparin treatment showed a slight not significant improvement apparent in 40% of the patients. The activities of F-IIaI and F-XaI in the blood plasma were found to increase after injection of Logiparin. These two parameters seem to be the most suitable for monitoring the effect during treatment. For future studies on the therapeutic effect of Logiparin in deep venous thrombosis a single dose of 150 to 200 F-XaI activity per 24 hours seems to be most suitable.

Aged↗

PubMed1989

Coagulation and fibrinolysis during the normal menstrual cycle.

Thirteen healthy women (age 24-44 yrs) were studied during their menstrual cycle. Samples were taken 2-3 times weekly for six consecutive weeks. Plasma concentrations of oestradiol and progesterone were determined in each blood sample and only women found to be ovulatory were included. From the hormone data the cycles were divided in five phases (early follicular phase, late follicular phase, early luteal phase, late luteal phase and menstrual period). The samples for the coagulation and fibrinolysis assays as well as the venous occlusion (20 min) tests were drawn or performed between 8-9 a m after fasting for 8 hrs. The fibrinogen F VIII:C and AT III were assayed and did not show any variations through the study period. Neither were any differences found in platelet counts, platelet mean volumes or platelet function measured as platelet adhesion and plasma beta-thromboglobulin. The fibrinolytic activity after venous occlusion decreased slightly during the late luteal phase (phase 4) as compared with the other phases. Large individual differences were, however, seen and no statistically significant differences between the five different phases were found. The plasminogen activator inhibitor (PAI-1) varied during the cycle but in most individuals within the normal range. In 7/13 women substantial fluctuations of the fibrinolytic activities during the cycle were seen. Four women had a significant fall of the fibrinolytic activity after venous occlusion during the late luteal phase (phase 4) and 3 others during the menstrual phase (phase 5). No co-variation between the fibrinolytic activities and PAI-1 was found. Multiple regression analysis showed a co-variation between fibrinolytic activities and progesterone.

Adult↗

PubMed1988

Age dependence of blood fibrinolytic components and the effects of low-dose oral contraceptives on coagulation and fibrinolysis in teenagers.

Basal t-PA antigen concentration, PAI-I activity and fibrinolytic capacity was studied in plasma from 20 healthy teenager girls (age 15.9 +/- 1.3 years) and two groups of older healthy volunteers, consisting of 17 women (age 32 +/- 8 years, group 1) and 35 men (age 34 +/- 8 years, group 2). Basal t-PA antigen concentrations in plasma were found to be highly age-dependent with higher values with increasing age. The teenager girls had significantly lower values compared with the two groups of elderly volunteers. PAI-I levels were significantly higher in plasma from the teenager girls and the fibrinolytic capacity after 15 min of venous occlusion was significantly lower. In this study we also determined the effect of low-dose oral contraceptives (OC) on coagulation and fibrinolysis in the teenager group. Each teenager served as her own control with samples drawn before and on OC after 4 months of use. The coagulation parameters, factor VIII activity, AT III, Protein C and platelet counts were all within reference values before and on OC. The fibrinolytic activity in plasma after venous occlusion (15 min) increased significantly when the teenagers had used OC for 4 months. This phenomenon was explained by significantly decreased PAI levels and also by significantly increased t-PA antigen release from the vessel wall after venous occlusion.

Adolescent↗

PubMed1988

A glioma-derived PDGF A chain homodimer has different functional activities from a PDGF AB heterodimer purified from human platelets.

Glioma-derived growth factor I (GDGF-I) is structurally similar to a platelet-derived growth factor (PDGF) A chain homodimer, whereas PDGF purified from human platelets is a heterodimer of one A and one B chain. Binding experiments revealed that GDGF-I and PDGF bound to a common receptor on human fibroblasts, but also suggested the presence of a second receptor type recognizing only PDGF. In contrast to PDGF, GDGF-I had only a limited mitogenic activity, a low ability to stimulate receptor autophosphorylation and actin reorganization, and no chemotactic activity. GDGF-I did, however, cause transmodulation of EGF receptors, suggesting that it, like PDGF, activates protein kinase C in fibroblasts. These data indicate that different PDGF-like growth factors have different functional activities, which are possibly mediated via different receptors.

Binding, Competitive↗

PubMed1987

Specific binding of B-CLL cell-derived chemokinetic inhibitory factor (CIF) to human polymorphonuclear leukocytes.

The chemokinetic inhibitory factor (CIF) is a recently described B-cell derived lymphokine that mediates a chemokinetic inhibitory effect on human polymorphonuclear leukocyte (PMN) migration. In the present report the interaction of CIF with the neutrophil plasma membrane was studied. Normal human peripheral blood neutrophils and purified neutrophil plasma membranes selectively removed biologic activity from CIF-containing concentrates obtained during the purification procedure from conditioned medium. Removal was obtained at both 4 degrees C and 37 degrees C. Furthermore, HL-60 cells treated with dimethyl sulfoxide removed CIF activity (granulocyte-like cells) but HL-60 cells treated with 12-O-tetradecanoylphorbol-13-acetate (macrophage-like cells) did not. Purified human blood monocytes, cells from the macrophage-like U-937 cell line and cells from the basophilic leukemia cell line KU-812 did not remove CIF. These studies suggest that neutrophils express specific binding sites for CIF-activity.

Binding Sites↗

PubMed1986

Production of chemokinetic inhibitory factor (CIF) by normal blood and spleen B lymphocytes.

We have recently reported the partial purification and characterization of of a new lymphokine, the heat-labile chemokinetic inhibitory factor (CIF) which inhibits neutrophil movement. We have also shown that this lymphokine is produced and secreted by cultured B-chronic lymphocytic leukaemia (CLL) cells in vitro. The present study shows that highly purified resting normal B lymphocytes from blood and spleen have the capacity to produce CIF spontaneously. After activation with anti-IgM or EBV-infection the lymphocytes produced a number of other factors, heat-stable chemokinetic inhibitory factors and heat-labile chemokinetic enhancing factors. Supernatants from a collection of human B-cell lines representing different stages of B-cell differentiation were also investigated. None of these cell lines produced CIF. The present results show that the production of CIF is not restricted to the malignant B-CLL cell but is also produced by a subset of normal blood and spleen B cells.

B-Lymphocytes↗

PubMed1986

The chemokinetic inhibitory factor derived from chronic lymphocytic leukaemia cells. Partial purification and characterization of a new lymphokine.

We have recently described a heat-labile and cell-directed neutrophil migration inhibitory activity that is present in serum from patients with chronic lymphocytic leukaemia (CLL). The inhibitory activity is produced and secreted by CLL cells in vitro. In the present study the inhibitory activity was partially purified from short-term cultures of monoclonal leukaemic B-CLL cells. On gel filtration the calculated molecular weight was apparently 30,000. By anion exchange chromatography, the inhibitory factor was recovered in the fractions that eluted with 0.3 mol/l NaCl. The active material applied to preparative agarose gel electrophoresis migrated towards the anode. The inhibitory factor was totally destroyed by trypsin. In addition it bound to concanavalin A-Sepharose. These properties indicate that the inhibitory factor is a glycoprotein. Antibodies against the isolated inhibitory factor were raised in rabbits. CLL serum was separated by means of gel filtration and the inhibitory activity was recovered in the pool with a molecular weight of approximately 30,000. The activity was completely neutralized by the antibodies raised against the CLL-cell-derived inhibitor, indicating the similarity between this and the serum-derived inhibitor. We have shown the existence of a new lymphokine, derived from B-CLL cells, in serum from patients with CLL.

Cell-Free System↗

PubMed1985

The chemokinetic inhibitory factor (CIF) in serum of CLL patients: correlation with infection propensity and disease activity.

We have recently described the partial purification and characterization of a neutrophil migration inhibitory activity present in serum from patients with chronic lymphocytic leukaemia (CLL). This new lymphokine, the chemokinetic inhibitory factor (CIF), is produced by B-CLL cells. It is a heat-labile glycoprotein of an approximate molecular weight (m. w.) of 30000. In this extended investigation 64/89 CLL-patients had CIF in their serum. CLL serum diluted to a concentration of 0.02% gave significantly decreased chemokinetic activity, suggesting that CIF is potent at very low concentrations. 31/89 patients had increased infection propensity. Significantly more patients with CIF in serum had infections compared to the group with normal susceptibility to infections. The combination of low Ig levels and CIF in serum discriminated even better between the infection-prone and non-infection-prone patients. CIF in serum was not correlated to tumour cell mass - estimated by Rai clinical staging - tumour progression or deoxythymidine kinase, S-TK, an enzyme that may reflect proliferating cells. The existence of this new lymphokine in serum seems to contribute to the increased susceptibility to infections seen in CLL patients.

Adult↗

PubMed1983

Cellular origin of the chemokinetic inhibitor of polymorphononuclear leucocytes found in sera from patients with chronic lymphocytic leukaemia.

In a previous study, we demonstrated the existence in serum from patients with chronic lymphocytic leukaemia (CLL) of a cell-directed, heat-labile chemokinetic inhibitor of polymorphonuclear leucocytes (PMN). The aim of this investigation was to study the cellular origin of this inhibitor. Supernatants from short term cultured lymphocytes from 3 healthy persons and 5 patients with CLL, and from 16 different established human non-haematopoietic and haematopoietic cell lines were analyzed. Only the leukaemic B-lymphocytes from the CLL patients produced the inhibitor. The presence of the inhibitor was also demonstrated in supernatants from the fresh CLL cells from one CLL patient and a leukaemic cell line established from these cells using Epstein-Barr virus as the immortalizing agent. A lymphoblastoid cell line derived from the normal B-cells of the same CLL patient did not produce the chemokinetic inhibitor. We therefore conclude that the cellular origin of the heat-labile, cell-directed chemokinetic inhibitor of PMN migration is the CLL cell.

B-Lymphocytes↗

PubMed1983

Prognostic value of serum lactic dehydrogenase in non-Hodgkin's lymphoma.

Lactic acid dehydrogenase (LDH) is a glycolytic enzyme that may be elevated in the serum of patients with non-Hodgkin's lymphoma (NHL). In this investigation LDH was assayed in sera from 155 untreated patients with NHL. Serum LDH (S-LDH) was found to be significantly correlated both to the spread of the disease and to the histological grade of malignancy i.e. more advanced disease or more aggressive histopathology was associated with higher S-LDH values. A high pretreatment S-LDH level (greater than 8.0 mukat/l) in stages III and IV correlated significantly to a decreased survival time. The patients with a pretreatment level of less than 8.0 mukat/l had an actuarial 2-year survival of 80%, compared to 30% in the patients with levels greater than 8.0 mukat/l (P less than 0.001). In stages I and II all 6 patients with a high pretreatment level (greater than 8.0 mukat/l) relapsed during or a short time after radiotherapy. In a longitudinal study of 24 patients it was found that S-LDH reflected in the clinical course. In patients treated to partial or complete remission, S-LDH decreased and at relapse it rose again. It is concluded that S-LDH might be useful both as a prognostic marker and to monitor the course of the disease.

Adolescent↗

PubMed1982

Identification of a chemokinetic inhibitor in serum from patients with chronic lymphocytic leukaemia.

The effects of serum from patients with chronic lymphocytic leukaemia (CCL) on normal polymorphonuclear leucocyte migration (PMN) were examined by means of the leading front technique, using a modified Boyden chamber. 18 randomly selected patients were studied. 13 patients had a reduced chemokinetic activity. The defective migration was explained by the finding in serum from these patients of cell-directed inhibitory activity which was destroyed by heating (56 degrees C, 30 min). The B-lymphocytes as the origin of the inhibitory activity was suggested by the presence of a similar activity in supernatants from cultured tumour cells. 6 of the 18 patients had the combination of a defective chemokinetic activity and low levels of immunoglobulins. These 6 patients had an increased tendency towards infections.

Aged↗

PubMedDate not supplied

Tyr1009 and Tyr1021 in the platelet-derived growth factor beta-receptor mediate agonist triggered calcium signalling.

Calcium signalling was studied in porcine aortic endothelial cells stably transfected with wild type or mutants of the human platelet-derived growth factor (PDGF) beta-receptor and fibroblast growth factor (FGF) receptor-1 (FGFR1). Phospholipase C-gamma (PLC-gamma) has a consensus binding site at phosphorylated Tyr1021 in the PDGF beta-receptor. The phosphorylated tyrosine at 1009 is a binding site for Syp/PTP1D, an adaptor molecule mediating Grb2/RAS signalling. Also, Tyr1009 has been shown to be a minor binding site for PLC-gamma; however previous data have indicated that it does not have any functional significance in PLC-gamma signalling. The concentration of cytoplasmic calcium ([Ca2+]i) was measured by microfluorometry and digital imaging. About 72% of the cells transfected with wild type PDGF beta-receptor responded to a challenge with PDGF-BB. Mutants in which both Tyr1009 and Tyr1021 in the PDGF beta-receptor were exchanged for phenylalanine totally lacked [Ca2+]i responses. However, in those with a single mutation at Tyr1009 or Tyr1021, 36% and 12% of the cells responded, respectively. In cells transfected with FGFR1 or FGFchim, with the kinase insert of FGFR1 replaced by the insert of the PDGF beta-receptor, a [Ca2+]i increases was observed in similar proportions of cells. The amplitudes of the growth factor-induced [Ca2+]i responses was comparable in the different transfectants. Thrombin, activating a G-protein coupled receptor, triggered [Ca2+]i peaks more rapidly, and in a higher proportion of cells compared to the growth factors. The present data indicate that both Tyr1009 and Tyr1021 alone and in cooperation mediate PDGF-BB triggered calcium signalling.

Amino Acid Sequence↗