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Biomedical subjects

J Caen

Publications and source records attributed to J Caen.

At least 19 recordsLinked to original sources
PubMed1992

Procoagulant activity of endotoxin or tumor necrosis factor activated monocytes is enhanced by IgG from patients with lupus anticoagulant.

The effect of lupus anticoagulant (LA) positive plasma on the expression of human monocyte procoagulant activity (PCA) was studied. LA positive plasma were able to enhance the endotoxin or TNF alpha induced monocyte associated PCA. The monocyte PCA had the characteristic of tissue factor activity (factor VII, factor X dependence). The enhancement of monocyte PCA could be confirmed using purified LA positive IgG. The stimulating effect was supported by the F(ab')2 fragments.

Adult↗
PubMed1992

Inhibition effects of KRDS, a peptide derived from lactotransferrin, on platelet function and arterial thrombus formation in dogs.

KRDS (Lys-Arg-Asp-Ser), a tetrapeptide from human lactotransferrin, was tested for its effects in vitro on dog platelet function and in vivo on femoral arterial thrombus formation in dogs. KRDS inhibited ADP (8 microM)-induced platelet aggregation (IC50: 350 microM) and arachidonic acid (2 mM)-induced thromboxane B2 generation (IC50: 175 microM). In addition, the thrombin (0.2 U/ml)-induced serotonin release was inhibited by KRDS (IC50: 525 microM) and the expression of alpha-granule membrane protein (GMP-140) was also inhibited (IC50: 350 microM). The results show that KRDS is an inhibitor for platelet aggregation and secretion to which the inhibition is more potent. Meanwhile, in the experiment of arterial thrombosis in dogs, KRDS (5 microM/kg) and 125I-SZ-51 (a monoclonal antibody against GMP-140) were injected before operation and immediately after the thrombus formation, respectively. In the KRDS group, the weight of removed thrombi was reduced to 50% of that in controls and the radioactivity per mg of labeled thrombi to 33.3% while in blood the radioactivity increased 2 times that in controls at the 4th hour after the injection of 125I-SZ-51. The radioactivity ratio between removed thrombi and blood was only 16% of that in controls. These results indicate that KRDS can inhibit thrombus formation in vivo and is a promising antithrombotic agent.

Amino Acid Sequence↗
PubMed1991

Platelet membrane glycoproteins and platelet functions during storage in the presence of a proteinase inhibitor.

The effect of the proteinase inhibitor aprotinin on membrane glycoproteins and functions of platelets stored for 5 days in platelet-rich plasma was tested. Platelet membrane glycoprotein content was determined by flow cytometry or immunoblot techniques using different monoclonal antibodies. ADP- and ristocetin-induced platelet aggregation and adhesion to collagen were tested in parallel. Using the flow-cytometry technique i) a progressive decrease in the percentage of platelets reacting with the different monoclonal antibodies was observed during storage ii) a 30% reduction of the GPIb mean fluorescence intensity (MFI) was observed after 5 days storage while the MFI of the GP IIb-IIIa complex was not modified. Using the immunoblot technique, a decrease in the amount of both the GPIb alpha and the component of Mr 100,000 was observed, while a 50,000 Mr fragment appeared progressively. Platelet adhesion and aggregation were reduced after 24 hours of storage. Aprotinin prevented neither the GPIb alpha reduction nor the modifications of the functions of human platelets stored in their autologous plasma.

Aprotinin↗
PubMed1991

Functional antithrombin-III variant (41 Pro----Leu) identified by liquid secondary ion mass spectrometry.

A genetic variant of antithrombin with impaired heparin cofactor activity was identified in 4 members of a French family. Both the variant and normal antithrombin component were purified by affinity chromatography on heparin Sepharose. Reverse phase peptide mapping revealed a single altered peak when tryptic digests of both antithrombins were compared. After further purification of the aberrant peptide, amino acid analysis indicated a substitution of 41 Leu----Pro (antithrombin Basel). This result was confirmed by liquid secondary ion mass spectrometry which gave a measured mass of 816.4655 Da for the new peptide compared to a calculated mass of 800.3579 Da for the normal peptide and 816.4579 for the Leu----Pro substitution.

Adult↗
PubMed1991

Association of autoimmune thrombocytopenic purpura (AITP), Graves' disease and ovarian carcinoma.

We report here the case of a patient suffering sequentially from autoimmune thrombocytopenic purpura (AITP), Grave's disease and an ovarian carcinoma. An autoimmune mechanism was indicated by the presence of platelet associated immunoglobulins and the detection of antithyroid microsomal antibodies. However, the exact mechanism associating these autoimmune manifestations with the ovarian tumour remains unexplained. Specific therapy for hyperthyroid led to a moderate increase of the platelet count. But complete remission of AITP now lasting for more than eight years was only obtained by ablation of the ovarian tumour.

Autoimmune Diseases↗
PubMed1991

Platelet surface glycoprotein changes in patients with cerebral ischemia.

In vitro abnormalities of platelet behaviour have been described in patients with ischemic cerebrovascular disease (ICD) suggesting that changes in platelet receptors and/or platelet a granules may occur in the circulation. We investigated the frequency of such alterations in 95 patients that were studied within a few days after acute stroke. Using specific antibodies to two intrinsic plasma membrane glycoproteins (GPs), the GPIIb-IIIa complex and GPIV, and to thrombospondin (TSP), a a-granular protein that becomes expressed on the platelet surface upon activation, we were able to distinguish two groups of patients: 16 patients presented an increased concentration of TSP on their platelets demonstrating in vivo platelet secretion. These patients could constitute a group with increased risk of thrombosis. In contrast, 20 patients presented a decreased concentration of GPIIb-IIIa and GPIV. This decrease in intrinsic plasma membrane GPs was associated with a decrease in mean platelet volume and may suggest the occurrence of platelet fragmentation in the circulation.

Acute Disease↗
PubMed1991

Immunocytochemical study of a Ca(2+)-ATPase enzyme in the human megakaryocytic lineage.

We report the presence of a Ca(2+)-ATPase in human megakaryocytes (MK) using an immunofluorescence technique on bone marrow smears and especially on normal MK progenitors in culture. This finding is based on the comparative staining of MK with 1) a well-characterized antibody raised against purified rabbit skeletal sarcoplasmic reticulum Ca(2+)-ATPase, 2) antibody P2 raised against the glycoprotein IIb-IIIa complex as a marker of megakaryocytic lineage, and 3) anti-glycophorin A as a marker of erythroid lineage. On bone marrow smears, all cells recognized by P2 were also labeled with the anti-Ca(2+)-ATPase antibody. In culture, a maximum number of MK colonies was observed at day 11. From days 2-4, some MK precursors appeared stained both with the anti-Ca(2+)-ATPase and P2 antibodies; other cells were reactive with both anti-Ca(2+)-ATPase and anti-glycophorin A antibodies. From day 5 of culture, cells were either simultaneously stained with P2 and anti-Ca(2+)-ATPase antibodies or with anti-glycophorin A antibody, but not with the anti-Ca(2+)-ATPase antibody. Besides this first evidence of an early expression of a Ca(2+)-ATPase in MK, this work provides a useful tool for identification of MK by immunofluorescence.

Bone Marrow↗
PubMed1990

KRDS, a new peptide derived from human lactotransferrin, inhibits platelet aggregation and release reaction.

KRDS (Lys-Arg-Asp-Ser), a tetrapeptide from human lactotransferrin, was tested in vitro on human platelet function, and its effects were compared to those of RGDS, a tetrapeptide from human fibrinogen. Both peptides had a high probability of initiating a beta-turn and were highly hydrophilic. KRDS inhibited ADP-induced platelet aggregation [median inhibitory concentration (IC50) 350 microM] and fibrinogen binding (IC50 360 microM) to a lesser extent than RGDS (IC50 75 microM and 20 microM, respectively). Different from RGDS, thrombin-induced serotonin release was inhibited by KRDS (750 microM) on normal platelets (55 +/- 10%) and type I Glanzmann's thrombasthenia platelets (43% +/- 1). However, KRDS had no effect on cytoplasmic Ca2+ mobilization, inositol phospholipid metabolism or protein phosphorylation (myosin light chain P20 and P43). In contrast to RGDS, KRDS does not inhibit the binding of monoclonal antibody PAC-1 to activated platelets. KRDS and RGDS inhibited 4 beta-phorbol-12-myristate-13-acetate (PMA)-induced aggregation and fibrinogen binding, while proteins were normally phosphorylated. Thus, the tetrapeptide KRDS is (a) an inhibitor of serotonin release by a mechanism independent of protein phosphorylation and (b) an inhibitor of fibrinogen binding and, hence, aggregation by a mechanism that may not necessarily involve its direct binding to the glycoprotein IIb-IIIa-complex.

Adenosine Diphosphate↗
PubMed1990

Identification of an endothelial cell growth-inhibitory activity produced by human monocytes.

The control of endothelial cell proliferation is important in a variety of processes including wound healing and tumor-induced angiogenesis. We have observed that normal unstimulated human monocytes isolated from the blood can inhibit human endothelial cell proliferation. Monocyte-conditioned medium was fractionated by gel filtration chromatography, yielding a 175-fold enrichment of a growth inhibitory activity, designated monocyte-derived endothelial cell inhibitory factor (MECIF). MECIF was found to be protease sensitive, resistant to acid treatment, and heat labile. When conditioned medium was subjected to HPLC gel filtration, the inhibitory activity was eluted as a single peak with a molecular weight of 50-70 kDa. Several characteristics distinguish MECIF from previously described monocyte/macrophage-derived inhibitory factors. Unlike TGF-beta, MECIF is heat labile and does not induce a mitogenic response in growth-arrested normal rat kidney cells. In addition, polyclonal antibodies specific for TGF-beta or INF-gamma do not inhibit MECIF activity. MECIF preparations show low levels of TNF-alpha, insufficient to promote the observed growth inhibitory effect. MECIF activity on human endothelial cells was found to be dose dependent and reversible. MECIF also appeared to be target cell selective in that it did not significantly alter the growth of human smooth muscle cells or skin fibroblasts. These data suggest that monocyte-derived factors may play a key role in inhibiting endothelial cell proliferation.

Cell Division↗
PubMed1989

Interaction of platelets with endothelial cells: activation of a novel neutral protease.

The activation of a new neutral protease of MW 85,000 was demonstrated on interaction between porcine aortic endothelial cells and human and porcine platelets in culture. The activity of this enzyme, PECAP (platelet endothelial cell activated protease), was detected by electrophoresis on polyacrylamide gels impregnated with the substrate casein. Our results showed that the platelet-endothelial cell interaction did not involve induction of synthesis of de novo enzyme, but rather an activation of a latent enzyme. PECAP cleaved casein and fibrinogen, but had no activity against gelatin or elastin. It was not inhibited by inhibitors of metalloproteases (EDTA, 1.10 phenanthroline), serine proteases (phenylmethylsulfonyl fluoride, elastatinal), or cysteine proteases (iodoacetate, N-ethylmaleimide) and it seems to be unrelated to the previously known proteases of mesenchymal and hematopoietic cells.

Animals↗
PubMed1989

Interrelationship of plasma triglyceride and coagulant factor VII levels in normotriglyceridemic hypercholesterolemia.

We have evaluated the potential relationships between plasma levels of certain coagulation factors, i.e. factor VII antigen (F VIIag) and factor VII coagulant activity (F VIIc), and parameters of lipid transport in a group of 90 normotriglyceridemic patients displaying hypercholesterolemia (Fredrickson's type IIa hyperlipoproteinemia). Levels of factor VIIc were significantly elevated (P less than 0.01) in this patient group as compared to a group of healthy normolipidemic subjects. By contrast, levels of factor VIIag were also increased, but such differences were not significant in relation to those of controls. Furthermore, concentrations of F VIIc and F VIIag in hypercholesterolemic males and females resembled each other. Similar observations were made when patients were divided into those either presenting or lacking symptoms of vascular disease. However, plasma levels of both F VIIc and F VIIag were positively correlated with circulating triglyceride concentrations in the hypercholesterolemic group, but not with other parameters of lipid transport such as serum cholesterol, HDL-cholesterol, and apolipoprotein B. When patients were treated with a lipid-lowering agent (cholestyramine), lower levels of both F VIIc and F VIIag were found concomitantly with a decrease of similar order in triglyceride concentrations. We conclude that serum triglyceride levels, even within the normal range, may be associated with elevation in the activity of factor VII in hypercholesterolemic patients, thereby increasing their risk of thrombosis.

Adult↗
PubMed1989

Prelining of polytetrafluoroethylene grafts with cultured human endothelial cells isolated from varicose veins.

Prelining graft material with autologous functioning endothelial cells might be one of the ultimate requirements to obtain a biocompatible surface. Accordingly, endothelial cells from stripped varicose veins were enzymatically harvested and grown on a fibronectin matrix. Proliferation was investigated in defined medium supplemented with various concentrations of endothelial cell growth supplement (ECGS) (25, up to 150 micrograms/ml) and heparin (10(-8), up to 10(-5)mol/L): optimal growth required both 150 micrograms/ml of ECGS and 10(-5)mol/L heparin. Under these conditions, cell culture achieved cell densities at a confluence of 1.2 +/- 1.1 10(5) cells/cm2 with a doubling time of 1 day. During subcultivation cultured cells consistently exhibited characteristic cobblestone morphology and immunofluorescent staining for factor VIII-related antigen, whereas prostacyclin production determined by enzyme-linked immunosorbent assay for 6-keto-prostaglandin F1 alpha reached 21.1 +/- 1.2 ng/10(6) cells after 15-minute stimulation with 1 U/ml of thrombin. Heparin-containing culture medium-endothelial cell interactions were particularly studied, and with iodine 125-heparin, binding was demonstrated with an apparent dissociation constant (Kd) of 0.36 +/- 0.04 mumol/L. A cold storage technique at -80 degrees C was sought, and freezed cells were used to coat in vitro polytetrafluoroethylene grafts. Protein-treated material allowed cell attachment and growth to a confluent monolayer as assayed by light and scanning electron microscopy. These data validate the feasibility of prelining grafts in vitro with autologous functioning endothelial cells. This approach may be useful in improving the performance of small-caliber vascular grafts according to prostacyclin production and surface-bound heparin of these cells.

Adult↗