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The pharmacological effects of clopidogrel, administered once daily at a dose of 75 mg for 12 weeks, were monitored in a group of 35 healthy male subjects. The maximum intensity of platelet aggregation induced by 5 microM of ADP and the velocity of aggregation were determined before treatment, and at regular intervals during and after treatment. The long-term effect of clopidogrel on ADP-induced platelet aggregation was analyzed by comparing maximum aggregation intensities at baseline, at steady state (average for days 8, 10, and 12), and at week 12. The percent inhibition in maximum intensity from baseline was calculated for each time point. A paired, one-tailed Student's t-test was used to test for a change of less than 10% in the maximum intensity of platelet aggregation from steady state to week 12. Bleeding time was measured before treatment, on four occasions during treatment, and at follow-up. A sustained inhibition of platelet aggregation was observed from week 1 through the remainder of the 12-week treatment period, with return to baseline within 2 weeks after the end of treatment. Mean percent inhibition was 43+/-11.6% (+/-SD) at steady state and 39+/-17% at week 12. The difference in mean maximum intensity of aggregation between steady state and week 12, 3.28% (95% CI: [-1.46, 8.01]), was significantly less than the specified limit of 10% (p <0.001). No statistically significant difference between these two time points was observed for the velocity of aggregation. The bleeding time prolongation factor during treatment remained stable at 2.1. These results indicate that the activity of clopidogrel on the inhibition of platelet aggregation was maintained with long-term treatment.

The potential pharmacological interaction between clopidogrel and heparin was assessed in a randomized, placebo-controlled study carried out in 12 healthy male subjects. Clopidogrel 75 mg once daily or placebo was given in a randomized fashion for 12 days during two periods separated by a 21-day washout period. Sodium heparin was administered as a prolonged intravenous infusion at a starting dose of 300 IU/kg/24 hours then adjusted so as to maintain the activated partial thromboplastin time (APTT) ratio for subject versus control within the therapeutic range of 1.7 to 2.3 for 4 days from day 9 through day 13 of each period. For each period, the following main parameters were measured: total heparin consumption; APTT on days 1 and 8 to 12 before drug intake and on days 13, 14 and 26; bleeding time and platelet aggregation induced by 5 microM ADP on days 1, 8 to 10 and 12 before drug intake, and on days 14 and 26; APTT measured 3 times on day 9, i.e., before the start of heparin infusion, then 3 and 6 hours later. During day 9 to 13 period, the subject/control APTT ratio remained within the specified 1.7 to 2.3 range with no statistically significant difference between the clopidogrel and placebo treatments. The mean (+/-s.e.m.) volumes of heparin infused in each group were 81384+/-2793 IU and 79867+/-2788 IU in the clopidogrel and placebo groups, respectively. The 90% confidence interval of the mean heparin volume difference fell within the+/-10% interval of the placebo mean centered on zero. Bleeding time in the placebo group remained practically unchanged throughout the study. In the clopidogrel group, bleeding time prolongation factor was significantly increased from baseline to day 9, with clopidogrel alone then remained stable at 1.2 following co-administration of heparin until the end of treatment; hence, it was not modified by the coadministration of heparin. ADP (5 microM)-induced platelet aggregation was inhibited by 27+/-12% after 7 days of clopidogrel administration alone, and no significant further change was observed when heparin was coadministered. There were no adverse events that could be related to clopidogrel. In conclusion, under the study conditions, no interactions between clopidogrel and heparin were observed.

Clopidogrel, a potent novel platelet ADP-receptor antagonist, induces a significant inhibition of ADP-induced platelet aggregation. Maximum inhibition of 40 to 50% is observed 2 to 5 hours after a single 400 mg dose. The same level of inhibition is achieved with 75 mg once daily at steady state, i.e., after 3 to 7 days of repeated dosing. Based on these data, two studies were undertaken to investigate whether a treatment regimen comprising a large initial dose (loading dose) of clopidogrel, followed by daily doses of 75 mg, might provide a sustained steady-state level of inhibition of platelet aggregation induced by 5 microM of ADP within hours after first dosing. In one study, 10 healthy male subjects received a 375 mg loading dose of clopidogrel on day 1, then daily doses of 75 mg from day 2 to day 10. Mean inhibition of platelet aggregation, already significant at 30 minutes, reached 55+/-8.2% (+/-SEM) at 60 minutes, and a maximum of 80+/-3.6% at 5 hours. No further significant change was observed between 5 hours and 24 hours, and from day 2 through day 10 with subsequent daily doses of 75 mg. In the second study, conducted according to a randomized, single-blind design, four parallel treatment groups of nine healthy male subjects received a loading dose of 75 mg, 150 mg, 225 mg, or 300 mg of clopidogrel on day 1, respectively, and 75 mg once daily from day 2 to day 5. Mean (+/-SD) inhibition of platelet aggregation over the 2 to 24 hours post-loading dose period was 22+/-14.5%, 21+/-13.4%, 35+/-20.6% and 31+/-13.3%, respectively. On day 5, it was 48+/-14.7%, 33 +/-14.1%, 51+/-15.7% and 40+/-10.9% for the 75, 150, 225 and 300 mg loading dose groups, respectively. The smallest day 1 to day 5 difference was observed for the 300 mg group and the largest for the 75 mg group, indicating that the development of the full inhibitory effect of clopidogrel was faster with the loading doses higher than with 75 mg, and fastest with the 300 mg loading dose. These data and those of previous studies indicate that a dose of 300 to 400 mg produces a rapid onset of the pharmacodynamic action of clopidogrel, with levels of inhibition close to steady-state reached within 2 hours.

The effect of repeated doses of clopidogrel, a novel platelet ADP-receptor antagonist, on platelet aggregation and its tolerance were assessed in two randomized, double-blind studies in healthy male adults. In each of the four successive dose groups in Study I, 6 subjects received either clopidogrel 25, 50, 100, or 150 mg once daily and 2 received placebo for 16 days, according to a rising dose design. In each of the three successive treatment groups of Study II, 9 subjects received clopidogrel (50, 75, or 100 mg once daily) in the morning, 3 received triclopidine 250 mg twice daily and 3 received placebo for 14 days. In both studies, the inhibition of platelet aggregation induced by 5 microM of ADP was measured before dosing (baseline), then at regular intervals during and after treatment. Bleeding time was generally assessed at the same time points as platelet aggregation. In both studies, the inhibition of platelet aggregation reached steady state after day 6 dosing. Mean steady-state percent inhibition of platelet aggregation was 30%, 46%, 53%, and 73% for clopidogrel 25, 50, 100, and 150 mg, respectively, in Study I; and 54%, 52%, 47%, and 43% for clopidogrel 50, 75, 100 mg, and for ticlopidine, respectively, in Study II. After treatment discontinuation, statistically significant inhibition of platelet aggregation persisted for up to 8 days. In Study I, up to 75 mg repeated doses, mean bleeding time prolongation factor did not exceed 2, but increased further to 3.5 and 5.5 at a clopidogrel dose of 100 mg and 150 mg, respectively. In study II, prolongation factors during treatment did not exceed 2.2 for clopidogrel (in the 75 mg dose group) and 1.6 for ticlopidine 500 mg. Recovery of bleeding time was observed within 7-8 days. Treatments were well tolerated, and no serious clinical events or important changes in laboratory parameters were recorded. These data were consistent with those obtained in atherosclerotic patients and showed that the plateau response for the inhibition of platelet aggregation was reached at the 75 mg dose, for which bleeding time prolongation was approximately 2.

The safety and tolerability of clopidogrel coadministration to patients with recent acute myocardial infarction (AMI) treated with recombinant tissue plasminogen activator (rt-PA) and heparin were assessed. Patients of either sex who had a recent uncomplicated AMI with ischemic pain lasting at least 20 minutes and ST-segment elevation, and with indication for thrombolysis were included. Treatment was started within 12 hours after the onset of pain. Clopidogrel 75 mg was administered within 3 hours of starting the rt-PA infusion, and was continued at 75 mg once daily over the next 6 days. Heparin was administered as a 5000 IU intravenous bolus followed by a 1000 IU/h infusion for at least 48 hours to maintain an activated partial thromboplastin time at 1.8 to 2.2 times the control value. rt-PA was administered as a 15 mg bolus injection, followed by a 0.75 mg/kg (up to 50 mg) infusion over 30 minutes and a subsequent 0.50 mg/kg (up to 35 mg) infusion over 60 minutes. The patients were hospitalized at least during the 7-day study period, after which they were followed for 10 days. The primary end point of the study was the occurrence of bleeding complications validated by a data monitoring and safety committee as severe (intracerebral or with substantial hemodynamic alteration requiring treatment), moderate (need for transfusion), or minor (other bleeding). Based on the statistical assumption, at alpha = 0.05 of a true probability of severe bleeding < or =0.06, the required minimum number of patients was calculated as 45, 65, or 94 if no, one, or two moderate-to-severe bleeding events occurred, respectively. Efficacy was assessed based on mortality, reinfarction, or need for emergency revascularization procedures. One intracranial hemorrhage occurred among the first 49 patients included, and one after the inclusion of 16 additional patients (total of 65). After further increase in the number of patients to 94, then to 116 in order to secure a number of 94 evaluable patients for safety, there were no additional cases of severe bleeding. Hence, the observed rate of moderate-to-severe bleeding was estimated at 1.7%, with a 95% probability that the underlying rate was below 7.5%. Deaths occurred in 3.6% compared to 6.3% in the GUSTO trial. Recurrent myocardial infarctions occurred in 4.5% and emergency revascularization procedures in 14.5% of the 110 patients deemed evaluable for efficacy, rates which are similar in this study and the GUSTO trial. The results of the study compare favorably with historical data showing a moderate-to-severe bleeding rate of 6% with aspirin given concomitantly with rt-PA and suggest that clopidogrel could be safely given as platelet aggrega

The inhibition of platelet aggregation by clopidogrel, a novel platelet ADP-receptor antagonist, was evaluated in healthy male volunteers in two single-dose studies. In one study, 10 subjects received, in increasing order, single doses of 100, 200, 400 and 600 mg of clopidogrel or placebo in five study periods, according to a randomized, doubleblind, protocol design. In the second study, 12 subjects received a single 400 mg dose of clopidogrel as capsules and as tablets, according to an open-label, randomized, crossover design. The interval between the two administrations was seven days. Platelet aggregation induced by ADP (2, 5 and 10 microM) and by collagen (0.5 and 1 microg/mL; rising-dose study only) was assessed from blood samples collected over a period of 24 hours to 72 hours postdose. The inhibition of platelet aggregation was expressed as the mean percent change from baseline in maximum platelet aggregation. The effect of clopidogrel on bleeding time was also assessed. Clopidogrel induced a statistically significant inhibition of ADP-induced platelet aggregation at all doses. With 5 microM of ADP, the inhibition was dose-related up to a dose of 400 mg, with no further increase at a dose of 600 mg. At 2 hours, mean inhibition ranged from 12+/-6% (100 mg) to 42 +/-6% (400 mg), and at 24 hours, it ranged from 17+/-7% (100 mg) to 43+/-9% (400 mg). After 400 mg, the inhibition of platelet aggregation remained stable from 2 hours up to 72 hours, with mean percentages of inhibition ranging from 49 to 39%. Clopidogrel only showed a slight-to-moderate inhibitory effect on collagen-induced platelet aggregation. A mean bleeding time prolongation of 1.7 was observed 5 hours after the 400 mg and 600 mg doses; it was statistically significant only following the higher dose. Individual bleeding time prolongations ranged from 1 to 2.85. Clopidogrel was well tolerated at all doses. The results of these studies were part of the rational for the choice of the loading dose.

We have compared the anticoagulant and the antithrombotic effects of unfractionated heparin (Calciparine) and low molecular weight heparin (Fraxiparine) in an experimental human venous thrombosis model. One single subcutaneous injection of Calciparine or Fraxiparine was administered to healthy male volunteers at one month interval in a randomised and cross-over design. Ten subjects received doses used in man for preventing venous thrombosis (5,000 IU and 3,075 IU, respectively), and seven other subjects received curative doses (12,500 IU and 6,150 IU, respectively). Thrombus formation was measured 3 h and 8 h after drug administration. Non-anticoagulated human blood was drawn for 5 min directly from an antecubital vein over confluent cultured endothelial cells positioned in a parallel-plate perfusion chamber. The cells were previously stimulated for 4 h with lipopolysaccharides (10 micrograms/ml) and interleukin 1 beta (50 U/ml), resulting in optimal expression of biological active tissue factor. The wall shear rate at the cell surface was 50 s-1 and mimicked venous blood flow conditions. Immunologically quantified fibrin deposition on the stimulated cells was reduced only by curative doses of Calciparine and Fraxiparine at 3 h (3.4 +/- 0.8 versus 1.0 +/- 0.2 micrograms/cm/ and 2.6 +/- 0.8 versus 1.0 +/- 0.1 micrograms/cm2, respectively, p < or = 0.05). The influence of Calciparine and Fraxiparine on the formation of thrombin and fibrin was determined by measuring the plasma levels of thrombin-antithrombin III complexes and fibrinopeptide A (FPA) in blood samples collected distally to the perfusion chamber. The generation of these markers was significantly inhibited (50-83%) by both prophylactic and curative doses of Calciparine and Fraxiparine (p < or = 0.05). However, Fraxiparine still significantly inhibited the thrombin and fibrin generation at 8 h (p < or = 0.05), whereas Calciparine did not. The antithrombotic effects of both heparins were correlated with their plasma activities as measured by the antifactor Xa or the antithrombin assays. Thus, it appears in this model that Calciparine and Fraxiparine produce comparable antithrombotic effects at clinically comparable doses. However Fraxiparine has a longer-lasting anticoagulant activity than Calciparine. These results are in good agreement with clinical observations in man, and thus in favour of our model of human venous thrombogenesis for further studies of antithrombotic molecules.

Recent studies have shown inhibition of collagen synthesis by interferon gamma (IFN-gamma) in monolayer human fibroblast cultures on a plastic solid phase. However, the existence of this effect in vivo has not yet been demonstrated. Three-dimensional fibroblast cultures in collagen matrices (collagen lattices or dermal equivalents) provide a more physiological model than conventional cultures and fairly closely simulate in vivo conditions. This model was used for studying effects of IFN-gamma on normal and scleroderma fibroblasts. IFN-gamma induced a dose-dependent inhibition of fibroblast-mediated retraction of collagen lattices. IFN-gamma also inhibited total protein and collagen synthesis. Scleroderma fibroblasts were especially susceptible to the inhibitory effects of IFN-gamma. Since fibrotic scleroderma lesions are associated with tissue retraction and increased production of extracellular matrix macromolecules, these data confirm the potential value of IFN-gamma for the treatment of scleroderma and other fibrotic diseases.

Three-dimensional collagen lattice cultures of fibroblasts mimic the in vivo situation better than monolayer cultures. Here, skin fibroblasts from scleroderma patients and healthy controls were cultivated in collagen lattices, and the effects of recombinant human gamma-interferon (IFN-gamma) on these cultures investigated. IFN-gamma inhibited collagen lattice retraction in a dose-dependent way at concentrations ranging from 10 to 10,000 U/ml. This effect was independent of any alteration to the cell proliferation within the lattices. The inhibition was of the same order of magnitude in normal and pathological fibroblasts. The synthesis of collagen and non-collagen proteins, particularly fibronectin, was increased in scleroderma cultures. It was inhibited in both normal and scleroderma fibroblasts by IFN-gamma, with a maximal effect at the concentration 1000 U/ml, but the inhibition of protein synthesis was far more intense in scleroderma than in normal cells. In situ hybridization, Northern blot and dot blot analyses showed that mRNA coding for pro alpha 1(I) collagen was decreased in IFN-gamma-treated cells, indicating an effect at the pretranslational level. IFN-gamma also inhibited glycosaminoglycan synthesis, but in scleroderma cells only. This study shows that IFN-gamma regulates cell behavior in three-dimensional collagen matrices: (i) it decreases protein and specifically glycosaminoglycan synthesis in scleroderma fibroblasts, (ii) it modulates the interactions between cells and matrix that lead to the retraction of the lattice. Whereas collagen synthesis is largely decreased in lattice cultures like in vivo, it remains increased in the case of scleroderma compared to normal fibroblasts and may be down-regulated by IFN-gamma. Similar conclusions may be drawn for fibronectin and glycosaminoglycans. The inhibitory effect of IFN-gamma on the retraction capacity of fibroblasts and on their ability to synthesize increased amounts of extracellular matrix macromolecules may be of potential interest for therapeutic use of IFN-gamma in scleroderma patients.

We have studied the lectin-induced production of Interleukin II (IL-2) by peripheral blood leucocytes (PBL) obtained from recipients of kidney grafts. Pre-graft values (haemodialysed patients) are similar to those of healthy individuals. After grafting and during the first year the IL-2 levels produced by PBL from recipients with well functioning grafts are very low (p less than 0.001). Years after grafting the IL-2 yields tend towards restoration. At the onset of an acute rejection the IL-2 production rises significantly. These data show that an increase in IL-2 production may play a role in the rejection process.

A patient with Ph1 positive chronic myeloid leukemia developed accelerated phase with cytological abnormalities of platelets and megakaryocytes, and persistence of a high platelet count, after the failure of a course of intensive chemotherapy. During this phase, the karyotype analysis revealed two different Ph1 positive clones: one with a pericentric inversion of chromosome 3, the other with the same abnormality and a paracentric inversion of the second chromosome 3. Cases of acute leukemia with normal thrombopoiesis and abnormalities of chromosome 3, especially paracentric inversion, have already been reported. The significance of this association is discussed.

In this study we investigate the relationship between the Interleukin 2 (IL-2) yield produced by kidney allograft recipient's peripheral blood lymphocytes (PBL) under lectin stimulation and the occurrence of acute rejection episodes. PBL were harvested prospectively before grafting, after grafting in steady-state period, and at the onset of acute rejection episodes. In addition, we tested retrospectively the ability of PBL of recipients engrafted for more than 1 yr to produce IL-2. IL-2 levels were assessed on the IL-2-dependent CTL-L2 murine cell line. Our data show: 1) before grafting, hemodialysed patients (N = 14) produced normal IL-2 yield compared with healthy donors (N = 21); 2) the IL-2 secretion of PBL of recipients with good graft function (N = 18) is decreased markedly during roughly the first 12 months following transplantation (P less than 0.01); 3) when acute rejection crisis occurred during this time period (N = 24), a sharp and highly significant increment (P less than 0.01) in lectin-induced IL-2 production of recipient's PBL was seen. After 1 yr, the capacity to secrete IL-2 upon lectin stimulation tends to be restored. Finally, our data correlate rejection and high PBL-IL-2 secretion clearly at a time when recipients with well-functioning grafts have markedly impaired IL-2 secretion.

The lupus anticoagulant is a risk factor of thrombosis. The non thrombogenic endothelial surface could be a target for the lupus anticoagulant. We have investigated the effect of purified immunoglobulins G of five patients with LA on the thrombomodulin activity of cultured human endothelial cells from umbilical cord vein. The rate of activation of purified protein C (PC) (30 nM) by the endothelial cells in the presence of thrombin (0.1 U/dish) has been measured by hydrolysis of substrate S 2366. Activated PC has been 7.37 +/- 0.78 pmoles X ml-1 X h-1 in the presence of buffer and 7.2 +/- 0.78 pmoles X ml-1 X h-1 in the presence of control IgG (2 mg/dish). Heat aggregated IgG did not induce any significant change. Patient's IgG lowered significantly the rate of PC activation (4.86 +/- 1.04 pmoles X ml-1 X h-1, p less than 0.001). Fab fragment from two of these patient's IgG displayed the same inhibition. Moreover neutralization of this effect was obtained by addition of phospholipids (70% phosphatidylcholine, 30% phosphatidylserine) in excess to patient's IgG. Activation of PC has been also performed using purified rabbit thrombomodulin and a similar inhibition by patient's IgG was found. These results seem to indicate that antibodies present in the IgG fractions containing LA could be directed against phospholipids associated to thrombomodulin activity. Reduction of PC activation if present in the patients with LA could play a role in the occurrence of thrombosis.

We have investigated the effect of purified immunoglobulin G (IgG) on endothelial cell functions in 16 patients with lupus anticoagulant, 9 of whom had systemic lupus erythematosus (SLE). Spontaneous or thrombin-stimulated secretion of prostacyclin (PGI2) by cultured human endothelial cells from umbilical cord vein (HUVEC) was not inhibited by the patient's IgG. Nor was spontaneous release of tissue plasminogen activator (t-PA) or of its inhibitor (PAI) modified in the presence of patient's IgG. The rate of activation of purified protein C (PC) by HUVEC in the presence of thrombin was significantly lowered by patient's IgG or Fab' fragment (inhibition of 43%). Neutralization of this effect was obtained by incubation of a greater quantity of phospholipids (phosphatidylcholine, phosphatidylserine) with the patient's IgG. Activation of PC was also performed using purified rabbit thrombomodulin (TM) and a similar inhibition of the patient IgG was observed (inhibition of 48%) but the activation of Gla-domainless PC was not modified.

Between 1975 and 1979, 137.526 annual X-ray examinations of the chest were performed among the employees of a large Paris administration. Fifty-four cases of tuberculosis, 28 cases of sarcoidosis, 10 cases of bronchial carcinoma and 26 miscellaneous chest diseases were detected. This study confirms the inadequacy of radiological examination for detecting chronic obstructive bronchopulmonary conditions. The small proportion of tuberculosis (0.39 p.1000) and bronchial carcinoma (0.07 p.1000) revealed by this method suggests that it should be reserved to high risk patients.

Amyloidosis of bone and bone marrow is rarely symptomatic and is generally limited to deposits diagnosed by histological examination. Four cases with lytic bone lesions are reported. In 2 cases, amyloidosis was associated with Waldenstroem's Macroglobulinemia, in one case with multiple myeloma and in 1 case with solitary plasmocytoma. These 4 cases are compared to 14 cases already published in the literature, including 2 cases of plasmocytic dyscrasias. The role of amyloidosis in the genesis of bone lesions is discussed.