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Biomedical subjects

L Drouet

Publications and source records attributed to L Drouet.

At least 19 recordsLinked to original sources
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↗
PubMed1992

Characterization of a thrombopathy (type delta storage pool disease) affecting a pig colony.

An autosomal recessive thrombopathy in pigs is described and characterized functionally, morphologically and biochemically. The affected pigs have a severe bleeding diathesis and a markedly prolonged bleeding time but normal plasma and platelet von Willebrand factor (vWF) levels. Electron micrographs and fluorescence microscopy with mepacrine reveal reduced numbers of dense granules in platelets as compared to normals. This thrombopathy is a pure delta storage pool disease (SPD), as evidenced: a) biochemically by platelet serotonin content and metabolism and by comparative ATP/ADP content and secretion; b) functionally by reduced aggregability to low concentrations of convulxin and collagen but normal aggregability to other agents and normal synthesis of thromboxane B2. The affection was first discovered in a colony of von Willebrand's disease (vWD) pigs, but is biologically and genetically distinct. It is possible to completely separate the SPD from the vWD, although originally animals could be affected by both vWD and SPD. Normal plasma and platelet alpha granule content of vWF are found in diseased animals. An intermediate disorder is also detected in animals not severely affected, which may represent the heterozygous state.

Acetylserotonin O-Methyltransferase↗
PubMed1991

Liver veno-occlusive disease after bone marrow transplantation changes in coagulation parameters and endothelial markers.

Veno occlusive disease (VOD) is a frequent complication of allogenic bone marrow transplantation (BMT) for which no predictive blood markers are available. 39 patients grafted for severe aplastic anemia (18), and leukemia (21) were prospectively studied. Of the 39 patients, 5 leukemic patients, but no aplastic patients developed VOD. In all the 5 patients with VOD complications we demonstrated a decrease in factor VII and in protein C before the clinical onset of the disease and before any changes in hepatic enzymes were observed. This decrease is the earliest sign of hepatic involvement by the VOD suggesting that the determination of Factor VII and protein C can be used as a prediction test to identify the patients who are at risk of developing VOD after transplantation. In addition, a toxicity of the endothelial cells was suggested by the observed increase in von Willebrand factor and in Serum Angiotensin Converting Enzyme. Signs of endothelial toxicity was more pronounced in leukemic than in aplastic patients.

Biomarkers↗
PubMed1991

Heterogeneous distribution of Weibel-Palade bodies and von Willebrand factor along the porcine vascular tree.

Vessels obtained from different levels of pig vascular tree were examined by transmission electron microscope, with the aim of determining whether or not their endothelial cells contain Weibel-Palade bodies (WPB). As these organelles are known to store the von Willebrand factor (vWF), a two-step immunogold labeling of this protein also was performed. Our results showed for the first time a heterogeneous distribution of WPB along the vascular tree of the normal pig: These structures were absent from the thoracic aorta, rare in the abdominal aorta, present in myocardial capillaries, and numerous in the inferior vena cava and pulmonary artery. Atypical WPB devoid of tubules were seen in all endothelial cells. The ultrastructural labeling of vWF demonstrated its presence only in the WPB, being absent in the subendothelium, and showed the same variation in its distribution along the vascular tree as for its storage organelle. Pigs homozygous for the von Willebrand disease were found to have only the atypical WPB, and do not express the vWF.

Aging↗
PubMed1990

Use of prostaglandin E1 for prevention of liver veno-occlusive disease in leukaemic patients treated by allogeneic bone marrow transplantation.

Prostaglandin E1 (PGE1) was used to prevent veno-occlusive disease (VOD) of the liver after allogeneic bone marrow transplantation (BMT) for leukaemia. It was given in continuous i.v. infusion from day--8 to day 30 after BMT at a dose of 0.3 micrograms/kg/h. The patients were studied according to the risk factors for VOD: diagnosis, intensification of the conditioning and previous liver abnormalities. The diagnosis of VOD was made on at least two of the following factors: weight gain, hepatomegaly, jaundice, ascitis, pain of the right upper quadrant, increased platelet consumption. 109 patients were studied, 50 were treated by PGE1 and 59 did not receive it. The actuarial incidence of VOD was 12.2% in the PGE1 group and 25.5% in the non PGE1 group (P = 0.05). In acute leukaemia, the incidence was 39.1% in the non-treated group and 12.8% in the PGE1 treated group (P = 0.02). Patients with previous hepatitis had an incidence of 62.5% in the non treated group and 15.5% in the treated group (P = 0.05). A positive cytomegalovirus (CMV) serology seemed to increase the risk of VOD: the incidence of VOD was 31.4% in non-treated patients and 22% in PGE1 treated patients. The multivariate analysis of the risk factors for VOD shows that unfavourable factors were: recipient positive CMV serology (P = 0.06), hepatic disease prior to transplant (P = 0.02) and the absence of PGE1 treatment (P = 0.02). This study suggests that prophylactic PGE1 treatment may decrease the incidence of VOD in patients treated for leukaemia by allogeneic bone marrow transplantation.

Adult↗
PubMed1990

Role of serotonin in arteriolar thrombosis and secondary vasospasm.

Platelets are implicated both in the thrombotic reaction to an intimal lesion of the arteriolar wall and to the resulting vasospasm even if the two phenomena are not linked directly. The spastic reaction is a consequence of the thrombotic process because without localized platelet activation (thrombus formation) there is no vasospastic reaction, but by pharmacological manipulation, the thrombotic reaction can develop without resulting vasospasm. We developed an original experimental model that allowed us to study the thrombotic reaction secondary to localized endothelial injury in arterioles of the mesentery of the rat, as well as the vasospastic reaction downstream to the site of thrombus formation. In this setting, we studied the reactivity of Sprague-Dawley rats treated with three 5-HT2 serotonergic antagonists (ketanserin, ritanserin, and naftidrofuryl) and that of Fawn-Hooded rats (a strain affected by a congenital reduction of platelet dense granules, with a resulting decrease in platelet content of serotonin, ADP, and catecholamines). Naftidrofuryl had antithrombotic properties similar to those of ritanserin but was less potent than ketanserin. It possessed antispastic activity against the reaction secondary to intravascular platelet activation. Its potency was similar to that of ketanserin but greater than that of ritanserin. Naftidrofuryl had no significant antispastic activity against platelet-derived agents reaching the ateriolar wall from the adventitial side. Compared to the Sprague-Dawley rat, Fawn-Hooded rats had a minimal reduction of the thrombotic process and of the intraluminal induced vasospasm but a similar response to adventitial stimulation of the arterial wall by vasoactive factors released from a neighboring hemostatic plug.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Endothelial cells: target for the HIV1 virus?

Plasmatic levels of endothelial markers [von Willebrand's factor (VWF), fibronectin (FN), and angiotensin converting enzyme (ACE)] were measured in patients at various stages of evolution of HIV1 infection. VWF levels were elevated at all stages, while other markers were significantly altered only for the most advanced stages. These results can be interpreted as indicating an endothelial involvement during HIV infection and VWF being the most sensitive marker. Endothelial markers, mainly VWF, could be used as prognosis marker of the infection. Capillary density was measured in the dermis of uninvolved skin showing a significant angiogenesis associated with the HIV1 infection. These biochemical and histological results however do not indicate whether these changes are directly linked to endothelial infection by the virus or to an indirect effect. The endothelial cell being an immunocompetent cell what is its involvement in the genesis of the immuno deficiency syndrome?

Acquired Immunodeficiency Syndrome↗
PubMed1990

Role of PGE1 to prevent veno-occlusive disease of the liver after bone marrow transplantation.

Prostaglandin E1 was used to prevent veno-occlusive disease of the liver after allogeneic bone marrow transplantation for leukemia. It was given in continuous IV infusion from day -8 to day 30 after BMT at the dose of 0.3 microgram/kg/h. The patients were studied according to the risk factors of VOD: diagnosis, intensification of the conditioning and previous liver abnormalities. The diagnosis of VOD was made on at least two of the following factors: weight gain, hepatomegaly, jaundice, ascitis, pain of the right upper quadrant, increased platelet consumption. One hundred and nine patients were studied, 50 were treated by PGE1 and 59 did not receive it. Univariate analysis shows that the actuarial incidence of VOD was 12.2% in the PGE1 group and 25.5% in the non PGE1 group (P = 0.05). In acute leukemia, it was 39.1% in the non treated group and 12.8% in the PGE1 treated group (P = 0.02). Patients with previous hepatitis had an incidence of 62.5% in the non treated group and 15.5% in the treated group (P = 0.05). A positive CMV serology seemed to increase the risk of VOD: the incidence of VOD was 31.4% in non treated patients and 22% in PGE1 treated patients. The multivariate analysis of the risk factors of VOD show that unfavorable factors were: recipient positive CMV serology (P = 0.06), hepatic disease prior to transplant (P = 0.02) and the absence of PGE1 treatment (P = 0.02). This study suggests that prophylactic PGE1 treatment may decrease the incidence of VOD in patients at risk treated for leukemia by allogeneic bone marrow transplantation.

Alprostadil↗
PubMed1990

The antithrombotic effect of KRDS, a lactotransferrin peptide, compared with RGDS.

Due to the functional homologies between milk and plasma coagulations and the molecular homologies between a plasma protein (human gamma-chain fibrinogen) and a milk protein (Kappa-casein), we thought to characterize a RGDS sequence in milk proteins. A KRDS sequence theoretically analogous to RGDS was found in human lactotransferrin. This study compares in 2 species (rat and guinea-pig) in vitro (on platelet aggregation) and in vivo (in an experimental model of arteriolar thrombosis), relative to RGDS, the effects of KRDS and of a modified sequence KRDR. In vitro, in the rat, while RGDS and KRDR did not affect significantly the platelet aggregation induced by ADP, KRDS had a significant inhibitory effect; on the guinea-pig platelets, KRDS and RGDS had an inhibitory effect of similar magnitude, and KRDR, a minimal effect. In vivo and in the two species, KRDS and RGDS had an antithrombotic activity much more pronounced than KRDR. Additionally, when KRDS and RGDS were studied together in vitro, no more than additive effect could be noticed in the guinea-pig. But in vivo, in the guinea-pig and even more pronounced in the rat, a potentiating activity was evidenced. These results indicate that KRDS, a peptide present in the human lactotransferrin sequence, has, in vitro, an anti-platelet activity and, in vivo, an anti-thrombotic activity. The mechanism of action is probably different from that of RGDS and is specific of the sequence since a similar KRDR sequence loses most of these actions.

Amino Acid Sequence↗
PubMed1989

Expression of von Willebrand factor in porcine vessels: heterogeneity at the level of von Willebrand factor mRNA.

The expression of the von Willebrand factor (vWF) gene by cultured endothelial cells from the porcine pulmonary artery, aorta, and lung was compared at the levels of messenger (m)RNA and antigen. Steady-state levels of vWF mRNA were determined by dot-blot analysis using a partial human vWF cDNA as the hybridization probe; vWF mRNA from cultured aortic endothelial cells, and vWF antigen secreted into the culture supernatants were barely detectable. In contrast, vWF mRNA and antigen from the pulmonary artery endothelial cells were approximately eight to nine times that demonstrated by aortic cells. Levels of vWF mRNA and antigen in cultured lung cells were intermediate of those found in the pulmonary artery and aorta and correlated with the estimated number of cells demonstrated to be of endothelial origin in the mixed cell populations grown from the lung. Differences between the levels of vWF mRNA found in cultured cells from the pulmonary artery and those found in the aorta were maintained in cells processed directly from these vessels. Correlation between the levels of vWF mRNA and antigen in endothelial cells from different vessels of the pig suggests that the differential control of vWF synthesis is at the level of transcription. Furthermore, maintenance in cultured cells of the difference in transcription rates that were observed in vivo suggests that vWF gene expression is not exclusively regulated through environmental factors.

Animals↗
PubMed1989

Current perspectives in the treatment of thrombotic disorders.

New trends in antithrombotic therapy should reside in a better adaptation, both in potency and in target to the involved thrombogenic mechanism. Thrombogenesis as hemostasis is the result of cooperation between plasma coagulation factors and platelet functions, and these two systems are themselves in equilibrated antagonism with the vessel wall, mainly endothelial cells. These triangular relations between coagulation factors, platelet functions, and endothelial cell reactivity are quantitatively regulated by flow conditions. The relative importance of each of these protagonists in the genesis of vascular thrombosis varies along the vascular tree, mainly due to changes in flow characteristics, and explain the usual separation between venous and arterial thrombosis: venous thrombosis involves mainly coagulation factors and the vascular fibrinolytic response whereas arterial thrombosis involves the thromboresistant characteristics of the endothelial cell membrane and platelet functions. The real blood flow characteristics may be altered by local disease and influences the relative involvement of coagulation and fibrinolytic factors, platelet functions, and endothelial cells. Prevention of thrombosis must take into account all these phenomena and must be targeted to the predominant factor or factors. Depending on the local conditions, the therapeutical goal can be: (1) limitation of platelet functions or coagulation factors; (2) stimulation of thromboresistant properties of the endothelium (mainly its profibrinolytic characteristics); and (3) modification of the flow conditions. Several targets can be associated: the level of inhibition or stimulation of a function depends on the dysequilibrium, and efficient prevention does not always require complete inhibition of a function. Once a thrombus has developed, antithrombotic treatment will prevent its extension, and thrombolytic therapy will try to restore vascular patency. Once patency has been restored antithrombotic therapy is still needed to prevent recurrence of the thrombus. Even if the main targeting is on platelets, the choice in the molecule to be clinically used must be defined by the function of the platelet involved: thrombogenesis or vasospasm, and even by the metabolic pathway predominantly activated. In coagulation strategy, differences must be drawn between antithrombotic therapy directed against thrombin formation, complexes of coagulation, free enzymes or activation phases. In thrombolytic therapy all procedural uses of extrinsic thrombolytic agents (natural, modified, or artificial), increase of susceptibility to endogenous thrombolytic systems, and stimulation of endogenous thrombolytic activity do not bear the same efficiency. As a consequence, the responsibility for clinical use of new molecules with more specific activity can allow more efficient antithrombotic therapy directed at the condition of an indication targeted at the exact mechanisms involved.(ABSTRACT TRUNCATED AT 400 WORDS)

Fibrinolytic Agents↗
PubMed1989

Cutaneous necrosis associated with the lupus anticoagulant.

Extensive cutaneous necrosis of the limbs with sudden onset was observed in 3 women suffering from benign systemic lupus erythematosus. All 3 had a circulating anticoagulant and a positive venereal diseases reference laboratory test without anticardiolipin antibodies. They were successfully treated with pulse methylprednisolone therapy and plasmapheresis. The necrosis-lupus anticoagulant relationship is discussed due to the absence of another possible etiology for cutaneous necrosis and the latter's histological aspect, i.e., thromboses of the dermal and hypodermal vessels without vasculitis. This cutaneous necrosis resembles that observed in congenital protein C deficiencies and favors the hypothesis of interaction between the lupus anticoagulant and the protein C-S complex.

Adult↗
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↗