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Biomedical subjects

L Drouet

Publications and source records attributed to L Drouet.

At least 109 records · Page 6Linked to original sources
PubMed1989

In vitro interactions between ramiprilat and angiotensin I-converting enzyme in endothelial cells.

Ramiprilat is an angiotensin I-converting enzyme (ACE) inhibitor whose particular lipophilicity may modify its inhibitory activity on the cellular form of this enzyme in comparison to ACE inhibitors that are more hydrophilic. The inhibitory activity of ramiprilat on cellular ACE and its binding to plasma membrane ACE have been studied in cultures of pig vascular endothelial cells. ACE activity in pig pulmonary artery endothelial cells is completely inhibited by 100 nM ramiprilat; the IC50 is 2 nM, whatever the form of ACE: soluble ACE released into the culture medium, cellular ACE studied in a cell monolayer homogenate, or tissue ACE purified from pig lung tissue. When added directly to whole living cells in their culture medium, 100 nM ramiprilat inhibits less than 80% of ACE activity in the supernatant while this dose inhibits the cellular form of the enzyme completely, suggesting that ramiprilat reaches and more specifically inhibits membrane-bound ACE rather than ACE secreted by the monolayer of endothelial cells. [3H]ramiprilat binds specifically to the membrane of cultured endothelial cells, in a time and dose-dependent manner (Kd = 6 nM; Bmax = 1,600 fmol/mg of protein); specificity is confirmed by the fact that an anti-ACE antibody prevents binding of [3H]ramiprilat and that both cold ramiprilat as well as other synthetic inhibitor compounds (captopril and enalaprilat) displace [3H]ramiprilat in a dose-dependent manner. Angiotensin I and bradykinin, natural substrates of ACE, do not induce displacement of [3H]ramiprilat bound to the luminal plasma membrane of endothelial cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1988

Molecular weight and shape of angiotensin-I converting enzyme. A neutron scattering study.

The molecular weight of angiotensin-I converting enzyme from pig lung has been determined to be 112000 (+/- 6000) by neutron scattering. This is somewhat lower than the value determined by SDS-PAGE and than previous estimates which, however, show a very wide range of values. A quantitative analysis of the amino acid and carbohydrate content was made in order to determine the enzyme concentration. The small angle neutron scattering technique also gives information on the molecular shape, yielding a radius of gyration of 44.5 +/- 1.5 A which, for the observed molecular weight, indicates that the angiotensin converting enzyme molecule is clearly elongated in aqueous solution. Dynamic light scattering experiments confirm this conclusion.

Amino Acids↗
PubMed1988

Cutaneous and plasma values of von Willebrand factor in AIDS: a marker of endothelial stimulation?

Patients infected by the human immunodeficiency virus (HIV) represent a model in which endothelial proliferation and/or damage are of concern. We studied Von Willebrand factor (VWF) plasma values as a presumed marker of endothelial proliferation in patients with the lymphadenopathy syndrome (LAS) (n = 45), AIDS-related Kaposi's sarcoma (KS) (n = 23), and AIDS opportunistic infections (n = 9), in comparison with normal controls (n = 19) and classical KS (n = 12). VWF was increased in AIDS patients with KS (p less than 10(-6)), in AIDS patients without KS (p less than 10(-7)), and to a lesser extent in classical KS (p less than 10(-3)) and LAS (p less than 10(-2] patients. To evaluate the diffusion of the vascular proliferation in HIV-infected patients, we studied the number of vessels within the superficial dermis of clinically uninvolved skin by an indirect immunoperoxidase method. We used an antibody directed against VWF in skin biopsies from 20 LAS patients and 10 AIDS-related KS patients compared to 11 controls and 10 classical KS patients. An increase in the number of blood vessels in normal skin was found in LAS (p less than 10(-2)), classical KS (p less than 0.05), and AIDS-related KS (p less than 10(-2]. Statistical studies and comparisons between plasma and cutaneous values of VWF indicate that plasma VWF is a good marker of endothelial damage but a poor marker of vascular proliferation in HIV-infected patients.

AIDS-Related Complex↗
PubMed1988

Serum angiotensin-converting enzyme: an endothelial cell marker. Application to thromboembolic pathology.

Aa a plasma marker of an endothelial abnormality, the serum activity of angiotensin-converting enzyme (ACE) was investigated at rest and after stimulation either by local venostasis or infusion of an analogue of lysine-vasopressin (desmopressin acetate). Desmopressin acetate did not induce any significant change in ACE, in contrast to the effect of venostasis. Searching for an endothelial abnormality implicated in the genesis of deep vein thrombosis, we used the local venostasis test in patients affected by recurrent deep vein thrombosis. Patients, divided in three groups (group I, documented history of recurrent deep vein thrombosis; group II, only one deep vein thrombosis or recurrent superficial venous thrombosis; group III, history of arterial thromboembolism), and controls were screened for basal and stimulated levels of serum ACE, together with fibrinolytic activity and von Willebrand factor level. Two types of abnormalities of serum ACE activity were found: low basal level in group I, and low response to venostasis in groups I and III; group II did not differ from controls. Measures of fibrinolytic and ACE activities are not redundant because the two types of ACE abnormalities were not individually encountered in the same patients and were independent from abnormalities of the fibrinolytic system. These findings suggest that an endothelial lesion could participate in the pathogenesis of some forms of recurrent deep vein thrombosis and support interest in the measurement of serum ACE to discriminate some patients at high risk of deep vein thrombosis.

Adult↗
PubMed1988

Analysis of von Willebrand factor mRNA from the lung of pigs with severe von Willebrand disease by using a human cDNA probe.

To examine the control of porcine von Willebrand factor (vWF) biosynthesis we cloned human vWF complementary DNA (cDNA) and investigated the expression of the vWF gene in lungs from normal pigs and pigs with severe von Willebrand's disease (vWD). Recombinant clones spanning approximately 90% of human vWF cDNA were identified in a lambda gt10 human lung cDNA library by screening with oligonucleotides. One clone spanning nucleotides 960 to 3,240 of human vWF cDNA was used to investigate the steady-state levels of vWF mRNA in lungs from normal pigs and from pigs phenotypically determined to be homozygous for vWD. This clone hybridized with genomic DNA from pig leukocytes when Southern blots were processed under very stringent conditions; therefore, human cDNA clones were considered valid probes to detect porcine mRNA. Northern blot analysis of total RNA from normal pig lung and human umbilical vein endothelial cells identified the vWF mRNA as a molecular species of approximately 9.0 kilobases (kb). A very faint to undetectable band at 9.0 kb in total RNA from lungs of vWD pigs suggested a decreased rate of transcription of the vWF gene. Sucrose density gradient centrifugation of RNA from the vWD pigs confirmed by Northern analysis that the high-molecular weight fractions contained vWF mRNA and at the same size as normal pig mRNA. Dot blot hybridization analysis of vWF and actin mRNA processed under stringent conditions demonstrated that the relative ratio of vWF mRNA to actin mRNA in the vWD pigs varied from 21% to 41% of the ratio observed in normal pigs. Because the amount of vWF mRNA is not correlated to the amount of vWF activity or antigen in plasma of vWD pigs we conclude that posttranscriptional events are also probably involved in abnormal expression of vWF in these animals.

Animals↗
PubMed1988

Weibel-Palade bodies in pig megakaryocytes.

Originally described in vascular endothelial cells, Weibel-Palade bodies were considered as specific of this cellular type, as they have never been reported elsewhere. Weibel-Palade bodies serve as storage granules for von Willebrand factor which is stored in microtubular form. Besides endothelial cells von Willebrand factor is also synthetized by bone marrow megakaryocytes. Von Willebrand factor has been located in alpha-granules of megakaryocytes and blood platelets. We describe true Weibel-Palade bodies in pig megakaryocytes, and also alpha-granules which look like an evolutionary form of Weibel-Palade bodies. Von Willebrand Factor is most likely stored in microtubular form in these two types of structure. This is supported by the absence of microtubules in these granules in cells obtained from pigs homozygous for the von Willebrand disease (lacking totally this protein).

Animals↗
PubMed1988

[Hemostasis tests as markers of hepatic and endothelial toxicity in chemotherapy].

Two short-lived vitamin K-dependent factors, factor VII and protein C, were measured by both functional and antigenic techniques in 3 hematological conditions known for their risk of hepatotoxicity: Following use of asparaginase and bisantrene, and patients at high risk of hepatic veno-occlusive disease after allogenic bone marrow transplantation for relapse of acute leukemia of accelerated phase of evoluted chronic myelogenic leukemia. In these 3 conditions functionally measured levels of protein C and factor VII, and antigenically measured levels of both these factors proved to be early markers of incipient hepatic involvement. These tests were easy to use routinely were reproducible, and proved to be predictive of veno-occlusive disease in grafted patients at the preconditioning stage. In the follow-up of bone marrow grafted patients plasma markers of endothelial function (von Willebrand's factor, tissue type plasminogen activator, and plasma activity of angiotensin converting enzyme) were significantly altered at the time of overdose with cyclosporin A, probably due to a drug-induced in vivo lesion of the endothelium. In the search for cytoprotective drugs for the prevention of veno-occlusive disease in bone marrow grafted patients prostaglandin E1 (PGE1) was given prior to and for at least 4 weeks after transplantation and proved to be effective by biological criteria (the level of protein C mainly). This deserves further study in a prospective clinical trial of the potential usefulness of PGE1 in preventing liver veno-occlusive disease in bone marrow grafted patients.

Alprostadil↗
PubMed1987

Binding of heparin to human endothelial cell monolayer and extracellular matrix in culture.

Endothelial binding of heparin contributes to its local antithrombotic action and catabolism. However, it is uncertain whether heparin may be bound to a damaged or even de-endothelialized vessel surface. Therefore, the binding of 3H-heparin to cultured endothelial cell monolayer and extracellular matrix was studied. The binding reached equilibrium after 4 h. 3H-heparin bound to endothelium could be displaced by unlabelled heparin which competed for about 80% of binding. The binding became saturable when the concentration of heparin exceeded 30-times the therapeutical value. Approximately 6 X 10(11) binding sites for heparin per cm2 of endothelium were calculated. Heparin was bound not only to endothelial cells but also to extracellular matrix, even when it was exposed in the absence of cells. About 40% of binding sites were localized in the extracellular matrix fraction. A similar affinity of binding of 3H-heparin to complete endothelium, endothelial cells and extracellular matrix was estimated /Kd of almost 1 microM/. The binding of heparin to extracellular matrix should be considered in the interpretation of heparin interaction with endothelium.

Cells, Cultured↗
PubMed1987

Absence of plasma prostacyclin stimulating activity deficiency in hemolytic uremic syndrome.

We compared the effect of plasma from 19 children with hemolytic uremic syndrome (HUS) on prostacyclin (PGI2) production by fresh rat aortic rings to the effect of plasma from 17 age- and sex-matched normal children, taking into account the PGI2 baseline aortic production (PGI2 release in presence of buffer, 21 determinations). After 10, 20, 30, 40, and 60 minutes incubation of rat aortic tissue with either plasma or buffer, the presence of PGI2 was studied by measuring by radioimmunoassay (RIA) the concentration of 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha). 6-keto-PGF1 alpha production increased with time in the two groups of plasma samples and in the presence of buffer, but 6-keto-PGF1 alpha production (ng/mg dried tissue) after 30 minutes incubation and mean 6-keto-PGF1 alpha production (slope of regression line, ng/mg/min) were significantly (P less than 0.01) lower in the presence of normal plasma compared with buffer, and significantly (P less than 0.01) higher in the presence of HUS plasma compared with normal plasma. There was no significant difference between buffer and HUS plasma. We conclude that, under our experimental conditions, normal plasma had an inhibitory activity on 6-keto-PGF1 alpha production by rat aorta. This inhibitory activity was absent in HUS plasma.

6-Ketoprostaglandin F1 alpha↗
PubMed1986

Effect of L-asparaginase therapy for acute lymphoblastic leukemia on plasma vitamin K-dependent coagulation factors and inhibitors.

Vitamin K-dependent proteins were measured sequentially by immunoassay in eight patients with acute lymphoblastic leukemia receiving L-asparaginase (1000 U/kg/day) for 10 days as induction therapy, in combination with vincristine or vindesine, daunorubicin, cyclophosphamide, and prednisone. The level of each protein was significantly decreased during L-asparaginase therapy, but both the time course of change and the severity of decrease differed among the proteins. The decrease in protein C, factor IX, and factor X was observed earlier than the decrease in protein S and factor II. In the first days of L-asparaginase therapy the protein C level was significantly lower than those of the other vitamin K-dependent proteins. The transient imbalance in the levels of plasma vitamin K-dependent proteins observed in the first days of treatment may contribute to the risk of thrombosis associated with L-asparaginase therapy.

Adolescent↗
PubMed1986

[Incidence of biological intravascular coagulation in legal induced abortions].

A prospective study was designed to evaluate coagulation abnormalities induced by early abortion (before ten weeks of pregnancy). Fifty-two women underwent suction abortion, under diazepam-fentanyl anaesthesia with spontaneous ventilation; they were screened for coagulation parameters before and after surgery. Eight tests were carried out: prothrombin time, activated partial thromboplastin time (APTT), thrombin time platelet count, fibrinogen levels, fibrin split products, fibrin soluble complexes and euglobulin lysis time. Results were consistent with activation. Consequences were limited and one general test (APTT) was not significantly modified. Suction abortion, even performed in early pregnancy, exposed to biological disseminated intravascular coagulation with a general risk of venous thrombosis.

Abortion, Induced↗
PubMed1986

Absence of tubular structures and immunolabeling for von Willebrand factor in the platelet alpha-granules from porcine von Willebrand disease.

The electron microscopic localization of von Willebrand factor (vWF) was studied in platelets from normal and von Willebrand disease (vWD) pigs. In normal pig platelets, immunolabeling for vWF was far more intense and extensive than in human platelets and was either localized at one pole of the alpha-granule or all along its periphery or long axis. As in human platelets, this immunolabeling coincided with the presence of tubules about 200 nm in diameter. These structures were more numerous than in human platelets, with up to 30 tubules per alpha-granule. They were easily identified either in transverse sections, usually grouped in a less electron-dense part of the matrix at one pole of the alpha-granule, or in longitudinal sections parallel to the long axis of the elongated granules, or coiled around the alpha-granule core. They closely resemble those structures found in Weibel-Palade bodies. In platelets from pigs with severe vWD, these structures were absent, as was the immunolabeling for vWF; however, cytoplasmic microtubules were normally present in these platelets. Thus, the granule-associated tubules can be distinguished from the microtubules, which are larger in diameter (250 nm), are present in both normal and vWD platelets, and do not stain for vWF. These results strongly suggest that the tubular structures present in the alpha-granules of normal porcine platelets correspond to the vWF molecule itself.

Animals↗
PubMed1986

[Thrombocytopenia induced by heparin. Diagnosis, treatment, physiopathology: current concepts].

Iatrogenic thrombocytopenia is a rare, but severe complication of treatments with heparin and heparinoids. Mean temporary thrombocytopenia failing to show any complications are usually diagnosed as quite different from acute and delayed thrombocytopenia of which severity depends mainly on thrombotic symptoms demonstrated in 65 p. 100 of cases; the initial evolution of an average thrombocytopenia is not easy to diagnose; it may as well exist a connection between the two diseases, from a physiopathogenic point of view. The diagnosis of severe thrombocytopenia depends:--clinically, on the initial data, delayed as compared with the heparin treatment beginning and existence of arterial and/or venous thrombosis;--biologically, by demonstrating an aggregating activity for platelets in presence of heparin, in the patient plasma. Such an activity requires the suppression of standard heparinotherapy as well as the choice of substitutive anticoagulant treatment in case of evolutive thrombosis. Low molecular weight heparins are prescribed only if in vitro tests of platelet aggregation with the patient's plasma are negative. Antivitamins K are to be used as soon as possible alone or combined with heparin fractions. Antiaggregants are prescribed alone, above all in case of isolated thrombocytopenia and combined with AVK. Treatment of thrombotic complications depends on surgical disobstruction if arterial thrombosis, and use of fibrinolytics if pulmonary embolisms. The acute reaction of some thrombocytopenia to heparin as well as therapeutic difficulties demonstrate the efficiency of an early diagnosis performed thanks to systematic platelet numerations during the first 15 days of a treatment with heparin, as well as to the prevention along with systematic association with aspirin, especially if replaced with AVK.

Heparin↗
PubMed1985

[Hemorrhagic rectocolitis associated with idiopathic thrombopenic purpura].

This case report documents severe autoimmune thrombocytopenia in a 20 yrs. old patient with ulcerative colitis. Diagnosis of idiopathic thrombocytopenic purpura was made on the presence of bound antiplatelet antibodies and on the absence of any other disorder capable of provoking a platelet fall. Colonic lesions were moderate but were resistant to steroids and total parenteral nutrition. Thrombocytopenia resisted to steroids and vincristine and a major fall in the platelet count (less than 10,000/mm3) occurred in two instances. However, platelets rose transiently after high-dose intravenous gamma-globulins. The patient underwent splenectomy, colectomy and ileostomy because of life-threatening colonic hemorrhage. The platelet count rose to normal levels within one week after surgery. Ileorectal anastomosis was subsequently performed. One year later the patient was in good health and his platelet count had returned to normal.

Adult↗
PubMed1985

[Ticlid].

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Anticoagulants↗