Biomedical subjects

A Siegbahn

Publications and source records attributed to A Siegbahn.

At least 55 records · Page 3Linked to original sources

PubMed1998

Demonstration of mast-cell chemotactic activity in nasal lavage fluid: characterization of one chemotaxin as c-kit ligand, stem cell factor.

Mast cells are known to accumulate in tissue during allergic inflammation. However, the chemotaxins responsible are undefined. Using a modified Boyden chamber and the human mast-cell line HMC-1, we first identified mast-cell chemotactic activity in nasal lavage fluid collected before the pollen season after allergen provocation of allergic patients (n=29) (mean migratory response compared to medium control was 121%, range 85-198%). Mast-cell chemotactic activity was also detected in lavage fluid collected after allergen provocation at the end of a Swedish birch-pollen season from three different treatment groups: topical steroid treatment with budesonide; the topical antihistamine, levocabastine; and placebo. There was no significant difference in mast-cell chemotactic activity between nasal lavage fluid collected from the placebo group (mean=102%), the budesonide-treated group (mean=114%), or the levocabastine group (mean=125%). Stem cell factor (SCF), a known mast-cell chemotaxin, was present in the nasal lavage fluids from all three groups, and correlated with the mast-cell chemotactic activity (r=0.67, P<0.01). The mast-cell chemotactic activity was inhibited (range 5-100%) in some, but not all, nasal lavage fluids by a polyclonal antibody directed against SCF. This report describes the presence of mast-cell chemotactic activity in nasal lavage fluid during an allergic reaction. These findings show that SCF may play a pivotal role in the recruitment of mast cells in allergic rhinitis.

Allergens↗

PubMed1998

Plasminogen activator inhibitor-1 activity is independently related to both insulin sensitivity and serum triglycerides in 70-year-old men.

Increased levels of plasminogen activator inhibitor-1 (PAI-1) have been discussed as a part of the insulin resistance syndrome. However, it is not clear whether the relationship between PAI-1 and insulin resistance is independent of or mediated by increased triglycerides levels. The aim of this study was to investigate whether PAI-1 activity is associated with insulin sensitivity independently of serum triglycerides (sTG) and of other potential confounders. Seventy-year-old men (n=871), participating in a cohort study undergoing extensive metabolic investigations, had blood samples taken for determination of PAI-1 activity. Insulin sensitivity was determined by the euglycemic hyperinsulinemic clamp. In multivariate correlation and regression analyses, insulin sensitivity was a statistically significant determinant of PAI-1 activity (partial r=-.12; P<.001), independent of sTG, body mass index, waist-hip ratio, and other potential confounders. The levels of sTG were also independently related to PAI-1 activity (partial r=.18; P<.001). The relationships between PAI-1 and insulin sensitivity and sTG were independent of fasting glucose levels. Aggregation of risk factors of the insulin resistance syndrome was associated with increased activity of PAI-1 in men with normal glucose tolerance. We conclude that PAI-1 activity is related to insulin sensitivity and sTG, independently of each other and of other potential confounders, and that increased levels of PAI-1 should be regarded as a component of the insulin resistance syndrome.

Aged↗

PubMed1998

Cell interactions with collagen matrices in vivo and in vitro depend on phosphatidylinositol 3-kinase and free cytoplasmic calcium.

We have investigated the role of phosphatidylinositol 3-kinase (PI3-kinase) in cellular interactions with collagenous matrices. Platelet-derived growth factor-BB (PDGF-BB) elicited a mobilization of intracellular Ca2+ in pig aortic endothelial (PAE) cells transfected with wild type PDGF beta-receptor. This response was greatly reduced in PAE cells transfected with PDGF beta-receptors mutated at positions Y740 and Y751 to prevent PI3-kinase binding. The experimental drug 1D-myo-inositol 1,2,6-trisphosphate (alpha-trinositol) induced a rapid increase and subsequent oscillations of the cytoplasmic Ca2+ concentration in cultured fibroblasts. This response was not due to an effect of alpha-trinositol on inositol 1,4,5-trisphosphate (IP3) receptors. alpha-Trinositol did not influence PDGF-BB elicited chemotaxis through collagen-coated membranes of PAE cells transfected with the wild-type PDGF beta-receptor, but restored PDGF-BB elicited chemotaxis of PAE cells transfected with the PI3-kinase binding-site mutated PDGF beta-receptor. Collagen gel contraction has been suggested to serve as a model for cellular control of interstitial fluid pressure (PIF) in dermis. The PI3-kinase inhibitors wortmannin (50 nM) and LY294002 (5 microM) inhibited the stimulation of fibroblast-mediated collagen gel contraction by 0.4 nM PDGF-BB. Injection of wortmannin in rat paw skin induced a lowering of PIF, and this effect was abolished in animals pre-treated with alpha-trinositol. Pretreatment of rats with alpha-trinositol abolished the decrease in PIF induced by injecting monoclonal anti-rat alpha 2 beta 1 integrin IgG in rat paw skin. Taken together our data indicate that cell-collagen interactions in vivo and in vitro depend on PI3-kinase, and that this dependence can be bypassed by a drug eliciting intracellular Ca2+ mobilization.

Androstadienes↗

PubMed1998

Low-molecular weight heparin reduces the generation and activity of thrombin in unstable coronary artery disease.

Unstable coronary artery disease (UCAD) is associated with an increased risk of further coronary events. In the FRISC study, the risk was decreased during treatment with a high, twice-daily, dose of dalteparin, a low-molecular-weight heparin. However, lowering the dose resulted in raised risk of recurrences. To investigate the underlying pathophysiology, the thrombin generation and activity in patients with UCAD randomized to a 6-week placebo-controlled treatment with dalteparin were evaluated. Plasma prothrombin fragment 1+2 (F1+2) (n = 342), thrombin-antithrombin complex (TAT) (n = 186) and soluble fibrin (SF) (n = 298) were analyzed before and during treatment with dalteparin/placebo administered subcutaneously, 120 IU/kg bw twice daily for 5-8 days and 7.500 IU once daily the following 35-40 days. High-dose treatment with dalteparin resulted in significantly reduced levels of all coagulation markers, demonstrating diminished thrombin generation and activity. When reducing the dalteparin dose, plasma TAT and SF remained low, indicating minimal fibrin formation. However, F1+2 increased during this period. though the level at day 45 was still lower than in the placebo group. In the placebo group elevated thrombin generation and activity persisted during the entire period. In conclusion, high-dose treatment with dalteparin twice daily resulted in significantly reduced thrombin generation and activity. However, after changing to a lower, once-daily dose, the treatment was not sufficient in preventing a return to a procoagulable state. These changes of the coagulation activity might explain the changes in event rate observed during dalteparin treatment.

Aged↗

PubMed1998

Thromboprophylaxis with low molecular mass heparin, 'Fragmin' (dalteparin), during pregnancy--a longitudinal safety study.

Twenty-five women with previous verified thromboembolic complications were treated with delteparin (Fragmin) during pregnancy and puerperium. Women with known hereditary thrombophilia (antithrombin, protein C and protein S deficiencies) or with phospholipid antibodies were excluded. The dose at entry was calculated according to body weight and thereafter monitored by anti-FXa activity aiming at 0.20-0.40 IU/ml plasma 3 h post injection. Dalteparin or dextran was used during delivery. Twenty-two women completed the study and 14 of these could be given the same dose throughout pregnancy. There was an increased dose response postpartum. There were no thromboembolic recurrences or severe bleeding complications. The level of antithrombin activity remained normal. Our thrombosis-prone pregnant women had initially increased levels of thrombin markers but no further increase was observed during the dalteparin thromboprophylaxis. Retrospectively, three heterozygous and three homozygous individuals for the FV Leiden mutation leading to activated protein C resistance were identified. In conclusion, dalteparin could safely be used as thromboprophylaxis during pregnancy in these thrombosis-prone women. Women weighing 50-79 kg at entry could be treated with 5000 IU of dalteparin once daily during pregnancy, without monitoring. Postpartum, many of the women were given a reduced dose.

Adult↗

PubMed1997

Prognostic influence of increased fibrinogen and C-reactive protein levels in unstable coronary artery disease. FRISC Study Group. Fragmin during Instability in Coronary Artery Disease.

BACKGROUND: The prognostic influences of fibrinogen and C-reactive protein levels and their relations to myocardial damage in unstable coronary artery syndromes have not been well described. METHODS AND RESULTS: Fibrinogen and C-reactive protein were determined at inclusion and related to outcome after 5 months in 965 patients with unstable angina or non-Q-wave myocardial infarction randomized to 5 weeks with low-molecular-weight heparin or placebo. The probabilities of death were 1.6%, 4.6%, and 6.9% (P=.005) and the probabilities of death and/or myocardial infarction were 9.3%, 14.2%, and 19.1% (P=.002), respectively, in patients stratified by tertiles of fibrinogen (< 3.38, 3.38 to 3.99, and > or = 4.0 g/L). The probabilities of death were 2.2%, 3.6%, and 7.5% (P=.003) after stratification of patient data by tertiles of C-reactive protein level (< 2, 2 to 10, and > 10 mg/L). In logistic multiple regression analysis, increased fibrinogen levels were independently associated with the incidence of death and/or myocardial infarction (P=.013), and elevated C-reactive protein level was associated with the incidence of death (P=.012). The increased relative risk of subsequent death or myocardial infarction in individuals with an elevated fibrinogen level was consistent in most subgroups evaluated; although significantly so only in patients with signs of myocardial damage. CONCLUSIONS: Increased levels of both fibrinogen and C-reactive protein are associated with a worse outcome in patients with unstable coronary artery disease. The increased risk associated with elevated fibrinogen levels is independent of, and additive to, the prognostic influence of myocardial damage.

Aged↗

PubMed1997

Tissue factor expression in human monocytic cell lines.

Tissue factor (TF) is a main initiator of the coagulation protease cascade. Control of the expression of this protein in monocytes is essential, since these cells are the only circulating blood cells responsible for TF expression. In this report we have used two human cell lines, arrested at different stages of monocytic differentiation, to study TF expression. The monoblastic cell line U-937 had a constitutive expression of TF surface protein and low TF mRNA levels detected by immunofluorescence or quantitative reverse transcriptase polymerase chain reaction respectively. The phorbol-12-myristate-13-acetate (PMA) was a potent enhancer of TF expression in U-937. Lipopolysaccharide (LPS) and tumor necrosis factor (TNF) had no effect on TF expression in U-937. The Mono Mac 6 cell line, with phenotypic features similar to that of mature monocytes, expressed lower basal levels of TF mRNA and surface TF antigen. However, in Mono Mac 6 cells TF expression was induced in response to LPS and TNF. These results indicate differences in basal and induced TF expression between U-937 and Mono Mac 6 cell lines.

Carcinogens↗

PubMed1997

Involvement of phosphatidylinositide 3'-kinase and Rac in platelet-derived growth factor-induced actin reorganization and chemotaxis.

Previous work has suggested a role for phosphatidylinositide 3'-kinase (PI3-kinase) in platelet-derived growth factor (PDGF)-induced actin reorganization and chemotaxis. In support of this notion, we show in this report that the PI3-kinase inhibitor wortmannin inhibits chemotaxis of PDGF beta-receptor expressing porcine aortic endothelial (PAE/PDGFR-beta) cells. Treatment with wortmannin resulted in a dose-dependent decrease in chemotaxis with an IC50 value of about 15-20 nM. Higher concentrations of wortmannin also reduced basal random migration of transfected cells in the absence of PDGF. We also investigated the role of Rac in PDGF-induced actin reorganization and cell motility. Overexpression of wt Rac in PAE/PDGFR-beta cells led to an increased cell motility and edge ruffling in response to PDGF-BB, compared to control cells. In PAE/PDGFR-beta cells transfected with inducible V12Rac (a constitutively active Rac mutant), membrane ruffling occurred in the absence of PDGF stimulation and was independent of PI3-kinase activity. On the other hand, PAE/PDGFR-beta cells transfected with inducible N17Rac (a dominant negative Rac mutant) failed to show membrane ruffling in response to PDGF stimulation. Together with previous observations, these data indicate that activation of PI3-kinase is crucial for initiation of PDGF-induced cell motility responses and that Rac has a major role downstream of PI3-kinase, in this pathway.

Actins↗

PubMed1997

Monocyte tissue factor expression, cell activation, and thrombin formation during cardiopulmonary bypass: a clinical study.

OBJECTIVES: Cardiopulmonary bypass is associated with extensive thrombin generation and cell activation. Our main hypothesis in this study was that the expression of tissue factor on circulating monocytes contributes to the formation of thrombin. METHODS: Markers of activation of the coagulation cascade and cell activation were measured in 26 patients undergoing elective heart operations randomized to the use of heparin-coated (Duraflo II, n = 13) or standard cardiopulmonary bypass circuits (n = 13). RESULTS: Thrombin generation, measured as the thrombin-antithrombin complex, increased considerably during cardiopulmonary bypass with peak levels 3 hours afterward and with remaining elevation 20 hours later. Despite increased monocyte and granulocyte activation and increased levels of monocyte chemotactic protein-1, which upregulates monocyte tissue factor expression in vitro, monocyte tissue factor expression was not increased at the end of cardiopulmonary bypass. Furthermore, at this time the monocytes were less sensitive to in vitro stimulation by endotoxin. These results might be explained by simultaneous enhanced levels of interleukin-10, which effectively downregulates monocyte tissue factor expression in vitro. Twenty hours after cardiopulmonary bypass was discontinued, the tissue factor expression on freshly isolated monocytes and on monocytes stimulated by endotoxin was significantly increased compared with preoperative levels. At this time increased activation markers of granulocytes, monocytes, and lymphocytes were also recorded. None of the measured parameters was found to be different between the groups. CONCLUSIONS: The tissue factor expression on circulating monocytes is upregulated the day after heart operations. The clinical relevance and the regulatory mechanism behind the enhanced expression, however, are not fully elucidated.

Aged↗

PubMed1997

Venous thrombosis: factor V G1691A genotyping related to APC resistance as measured by 2 methods.

Blood samples were collected from consecutive unrelated patients with venous thrombosis. The patients originate from the middle part of Sweden. We investigated the presence of the reported point mutation at nt 1691 of factor V which renders the protein resistant to cleavage by activated protein C (APC). Thirty-seven per cent of the patients were heterozygote carriers, and 4.5% were homozygotes for a mutated factor V gene. In addition, resistance to coagulation induced by APC was measured, both by the conventional APTT assay and by a modified APTT assay which has been reported to have an increased resolution. Compared to a control group of healthy people, the mean value was significantly lower in the patient group. A strong correlation between low APC ratio and presence of the factor V mutation was found. By using the modified method, a complete resolution of carriers of the factor V mutation and people with normal factor V alleles was found. However, there was still an overlap between heterozygote carriers and people homozygous for the mutation. The modified method was also found useful in patients treated with warfarin. Among 40 healthy blood donors 7% were found to be heterozygous.

Adolescent↗

PubMed1997

Growth hormone (GH)-deficient men are more responsive to GH replacement therapy than women.

Thirty-six patients with adult-onset GH deficiency (GHD) were examined before and after 9 months of treatment with recombinant GH. The study was conducted as a double blind, placebo-controlled, 21-month trial with a cross-over design, with each treatment period lasting for 9 months. The same dose, adjusted for body surface area, was given to men (n = 21) and women (n = 15), and the effects on body composition and biochemical parameters were evaluated with respect to gender. The extent of GHD, assessed before therapy from basal GH secretion and GH release in response to provocative tests, did not differ between the two groups. The men, however, had higher serum insulin-like growth factor I concentrations than the women (mean +/- SD, 126 +/- 71 vs. 61 +/- 32 micrograms/L; P = 0.0003), less body fat, and greater lean body mass. Upon treatment, insulin-like growth factor I concentrations increased more in men than in women (by 305 +/- 136 and 198 +/- 96 micrograms/L, respectively; P = 0.02). The men lost more body fat than the women (7.4 +/- 4.1% vs. 3.3 +/- 3.8%; P = 0.002), whereas the difference in gain in lean body mass failed to reach statistical significance. Serum levels of total cholesterol, low density lipoprotein cholesterol, apolipoprotein B, and plasminogen activator inhibitor-1 decreased in the male group (P = 0.003, P = 0.03, P = 0.0009, and P = 0.01, respectively), but not in the females. Serum markers of bone formation, namely osteocalcin, procollagen type I, bone-specific alkaline phosphatase, and a marker of bone resorption, telopeptide of collagen type I, increased more markedly in men than in women. Lipoprotein(a) increased to a similar extent in the male and female groups. The data demonstrate that men and women with GHD display marked differences in their responsiveness to GH replacement therapy. These differences should be taken into consideration when optimizing the treatment of GHD patients.

Adult↗

PubMed1997

Myeloperoxidase mediates cell adhesion via the alpha M beta 2 integrin (Mac-1, CD11b/CD18).

Myeloperoxidase is a leukocyte component able to generate potent microbicidal substances. A homologous invertebrate blood cell protein, peroxinectin, is not only a peroxidase but also a cell adhesion ligand. We demonstrate in this study that human myeloperoxidase also mediates cell adhesion. Both the human myeloid cell line HL-60, when differentiated by treatment with 12-O-tetradecanoyl-phorbol-13-acetate (TPA) or retinoic acid, and human blood leukocytes, adhered to myeloperoxidase; however, undifferentiated HL-60 cells showed only minimal adhesion. No cells adhered to horseradish peroxidase, and cell adhesion to myeloperoxidase was not decreased by catalase, thus showing that peroxidase activity, per se, was neither sufficient nor necessary for the adhesion activity. Mannan, which has been reported to inhibit the binding of peroxidases to cells, did not affect adhesion to myeloperoxidase. However, adhesion to myeloperoxidase was inhibited by monoclonal antibodies to alpha M (CD11b) or to beta2 (CD18) integrin subunits, but not by antibodies to alpha L (CD11a), alpha M (CD11c), or to other integrins. Native myeloperoxidase mediated dose-dependent cell adhesion down to relatively low concentrations, and denaturation abolished the adhesion activity. It is evident that myeloperoxidase supports cell adhesion, a function which may be of considerable importance for leukocyte migration and infiltration in inflammatory reactions, that alpha M beta2 integrin (Mac-1 or CD11b/CD18) mediates this adhesion, and that the alphaM beta2 integrin-mediated adhesion to myeloperoxidase is distinct from the previously reported ability of this integrin to bind to certain denatured proteins at high concentrations.

Antibodies, Monoclonal↗

PubMed1996

Mutation of a Src phosphorylation site in the PDGF beta-receptor leads to increased PDGF-stimulated chemotaxis but decreased mitogenesis.

Ligand induced activation of the beta-receptor for platelet-derived growth factor (PDGF) leads to activation of Src family tyrosine kinases. We have explored the possibility that the receptor itself is a substrate for Src. We show that Tyr934 in the kinase domain of the PDGF receptor is phosphorylated by Src. Cell lines expressing a beta-receptor mutant, in which Tyr934 was replaced with a phenyalanine residue, showed reduced mitogenic signaling in response to PDGF-BB. In contrast, the mutant receptor mediated increased signals for chemotaxis and actin reorganization. Whereas the motility responses of cells expressing wild-type beta-receptors were attenuated by inhibition of phosphatidylinositol 3'-kinase, those of cells expressing the mutant receptor were only slightly influenced. In contrast, PDGF-BB-induced chemotaxis of the cells with the mutant receptor was attenuated by inhibition of protein kinase C, whereas the chemotaxis of cells expressing the wild-type beta-receptor was less affected. Moreover, the PDGF-BB-stimulated tyrosine phosphorylation of phospholipase C-gamma was increased in the mutant receptor cells compared with wild-type receptor cells. In conclusion, the characteristics of the Y934F mutant suggest that the phosphorylation of Tyr934 by Src negatively modulates a signal transduction pathway leading to motility responses which involves phospholipase C-gamma, and shifts the response to increased mitogenicity.

Actins↗

PubMed1996

Platelet-derived growth factor-BB and monocyte chemotactic protein-1 induce human peripheral blood monocytes to express tissue factor.

Monocytes induced to express tissue factor (TF), the initiator of the clotting cascade, might play an important role in the pathogenesis of atherosclerosis. We have investigated the TF-inducing capacity of two factors thought to be involved in atherogenesis, i.e. the platelet derived growth factor-BB (PDGF-BB) and monocyte chemotactic protein-1 (MCP-1), a member of the chemokine superfamily. PDGF-BB and MCP-1 are potent chemotactic and activating factors for human blood monocytes. alpha-thrombin which is known to induce TF in endothelial cells and that recently has been shown to induce secretion of MCP-1 from endothelial cells and monocytes was also studied. PDGF-BB induced a dose-dependent expression of TF-antigen in monocytes with maximal response at 20-50 ng/mL. At higher concentrations the expression was reduced. No synergistic effect between PDGF-BB and LPS was seen. MCP-1 also induced a dose-dependent TF-expression with maximal response at 50 ng/mL. In contrast to these results thrombin did not. MCP-1 had a slight, but not significant, priming effect on LPS-induced TF expression. These data show that PDGF-BB and MCP-1 are potent inducers of TF in human peripheral blood monocytes. We suggest that this TF-induction might be an important link between hemostasis and inflammation.

Arteriosclerosis↗

PubMed1996

C3a and C5a are chemotaxins for human mast cells and act through distinct receptors via a pertussis toxin-sensitive signal transduction pathway.

Mast cells are known to accumulate at sites of inflammation, however, the chemotaxins involved are undefined. Since most natural leukocyte secretagogues also induce cell migration, and since the anaphylatoxins C3a and C5a are mast cell secretagogues, we hypothesized that both C3a and C5a are also mast cell chemotaxins. Here we report that C3a and C5a are, in fact, potent chemotaxins for the human mast cell line HMC-1. The optimal concentrations, half-maximal effective concentrations (a measure of agonist potency) and the efficacy (response at the optimal concentration) compared with medium control were, for C3a: 10 nM, 0.5 nM, and 256%, respectively; for C5a: 1 nM, 10 pM and 145%. Chemotaxis of HMC-1 cells to both C3a and C5a was blocked by pertussis toxin, suggesting that Gi-coupled receptors are involved in signal transduction. C3a and C5a also induced transient pertussis toxin-inhibitable increases in [Ca2+]i (ED50 = 1 nM for both) that could be homologously but not heterologously desensitized, suggesting that the receptors for C3a and C5a are distinct. These results make C3a the most effective mast cell chemotaxin identified to date. The chemotactic potency described here for C3a is also 100- to 1000-fold greater than for all of its previously described cellular actions. Direct chemoattraction of mast cells by C3a and C5a may help explain the rapid accumulation of mast cells at sites of inflammation.

Adenosine Triphosphate↗

PubMed1996

Structural determinants in the platelet-derived growth factor alpha-receptor implicated in modulation of chemotaxis.

Activation of the platelet-derived growth factor (PDGF) beta-receptor leads to cell growth and chemotaxis. The PDGF alpha-receptor also mediates a mitogenic signal, but fails to induce cell migration in certain cell types. To examine this difference in signal transduction, a series of point-mutated PDGF alpha-receptors were analyzed. Porcine aortic endothelial cells expressing mutant PDGF alpha-receptors, in which tyrosine residues 768, 993, or 1018 were changed to phenylalanine residues migrated toward PDGF, whereas wild-type alpha-receptors and mutant alpha-receptors changed at tyrosine residues 720, 944, or 988 failed to migrate. All mutant receptors were mitogenically active and their capacity to activate phosphatidylinositol 3'-kinase and phospholipase C-gamma was not different from that of the wild-type receptor. Tyr-768 was found to be phosphorylated in PDGF-stimulated cells; in the Y768F mutant, there was a considerable increase in phosphorylation of Ser-767. Tyr-993 was not phosphorylated, but mutation of this tyrosine residue to a phenylalanine residue resulted in increased efficiency of phosphorylation on Tyr-988. Tyr-1018 is known to be an autophosphorylation site. Phosphorylated Tyr-768 and Tyr-1018 may bind signal transduction molecules involved in negative modulation of the chemotactic signaling capacity, whereas phosphorylated Tyr-988 may mediate increased chemotaxis. Thus our data indicate that the PDGF alpha-receptor has an intrinsic ability to transduce a chemotactic signal, and that this signal is counteracted by overriding negative signals.

Amino Acid Sequence↗

PubMed1996

Inhibition of tissue factor surface expression in human peripheral blood monocytes exposed to cytokines.

Interleukin (IL)-4, IL-10, IL-13 and transforming growth factor beta (TGF-beta) are known to regulate several monocyte functions, including inhibition of the synthesis of different cytokines. Using quantitative RT-PCR and flow cytometry analysis we investigated the effects of these cytokines on bacterial lipopolysaccharide (LPS)-induced tissue factor (TF) expression in human monocytes. The effects of IL-4 and IL-10 on monocyte chemoattractant protein-1 (MCP-1)-and C-reactive protein (CRP)-induced TF expression were also studied. A direct comparison revealed that IL-4, IL-10 and IL-13 all down-regulated LPS-induced TF expression in a concentration-dependent manner without the need for priming. In contrast, TGF-beta required 4 h of priming to inhibit TF expression induced by LPS. IL-10 was the most powerful inhibitor, causing almost complete inhibition at 5 ng/ml. IL-4 and IL-13 exhibited a significantly lower inhibitory capacity even at concentrations of 100 ng/ml. IL-4 and IL-10 showed similar concentration-dependent inhibition of MCP-1- and CRP-induced TF expression. We also showed that the regulatory effect of the interleukins occurred at the mRNA level. In vivo, these inhibitory cytokines may play an important regulatory role in preventing thrombosis. IL-10, in particular, may be a possible candidate as a TF-preventing drug.

C-Reactive Protein↗

PubMed1995

PDGF-BB triggered cytoplasmic calcium responses in cells with endogenous or stably transfected PDGF beta-receptors.

Platelet-derived growth factor-BB (PDGF-BB) triggered signal transduction was investigated in human foreskin fibroblasts with endogenous PDGF beta-receptors, and porcine aortic endothelial (PAE) cells with stably transfected PDGF beta-receptors. Immunoprecipitation and immunoblotting showed that PDGF induced dose-dependent autophosphorylation of PDGF beta-receptor, and the PLC-gamma associates with autophosphorylated PDGF beta-receptors and becomes phosphorylated. Activation of PLC-gamma is known to induce fluctuations of the concentration of cytoplasmic calcium ([Ca2+]i). Microfluorometry and digital imaging were employed for measurements of the concentration of [Ca2+]i. In both cell types the growth factor induced four types of [Ca2+]i responses; no rise, a small and sluggish monophasic rise, a biphasic rise with an initial transient peak followed by a sustain elevation, and finally regular oscillations. The frequencies and amplitudes of the oscillatory responses were independent of agonist concentration after stimulation with PDGF-BB. Latency, the period from application of stimulus to the first [Ca2+]i peak, was reduced at higher concentrations of agonist. Also, the proportion of responding cells increased with higher concentrations of ligand. Oscillations of [Ca2+]i were elicited at submaximal concentrations of agonist. In PAE cells PDGF-BB triggered a single [Ca2+]i peak in absence of external Ca2+. Ligand-induced oscillations and sustained increases of [Ca2+]i were counteracted by the inorganic Ca2+ channel blocker Ce3+. These results show that similar types of [Ca2+]i responses occur in different cell types independently of whether the PDGF beta-receptors are expressed endogeneously or after transfection. Potentially, the different [Ca2+]i responses have distinct physiological consequences.

Animals↗