Clinical outcomes associated with proton pump inhibitor use among clopidogrel-treated patients within CYP2C19 genotype groups following acute myocardial infarction.

We examined clinical outcomes with proton pump inhibitors (PPI) use within CYP2C19 genotype groups during clopidogrel treatment following acute myocardial infarction (AMI). 2062 patients were genotyped for CYP2C19*2 and *17 variants in TRIUMPH. 12 month clinical outcomes were analyzed among patients discharged on clopidogrel within CYP2C19*2 carrier, CYP2C19*17 carrier, and CYP2C19*1 homozygote genotype groups. PPI use was not associated with a difference in mortality. Among clopidogrel-treated Caucasians following AMI, PPI use was associated with a significantly higher rate of cardiac rehospitalization (HR 1.62, 95% CI 1.19-2.19; P=0.002) compared with no PPI use. PPI users who were carriers of the CYP2C19*17 variant experienced significantly higher rates of cardiac rehospitalization (HR 2.05, 95% CI 1.26-3.33; P=0.003), carriers of the CYP2C19*2 variant had a trend toward increased 1-year cardiac rehospitalization (HR 1.69, 95% CI 0.95-2.99; P=0.07), while no significant differences were observed among CYP2C19*1 homozygotes. These results indicate that the risks associated with PPI use among clopidogrel-treated Caucasian post-MI patients are impacted by CYP2C19 genotype, and suggest knowledge of genotype may be useful for personalizing PPI use among patients following AMI to reduce rehospitalization.

Identification of a 36,000-molecular weight, gag-related phosphoprotein in lymphoma cells transformed by radiation leukemia virus.

Radiation leukemia virus (RadLV) causes thymic lymphoma in 90% of susceptible mice after a latent period of several months. The virally encoded polypeptides produced by RadLV-induced lymphoma cells were analyzed by immunoprecipitation and NaDodSO4/polyacrylamide gel electrophoresis. Along with the expected precursor and mature forms of gag and env gene products, a polypeptide of 36,000 molecular weight (p36) was precipitated by anti-gag antisera. It was not precipitable by normal sera or anti-env antibodies. Like the gag-associated fusion proteins of some acute leukemia viruses, p36 was found to be phosphorylated in vivo, although it lacked detectable ATP-specific protein kinase activity in vitro. By kinetics during pulse-chase labeling experiments and by comparison of two-dimensional tryptic peptide maps, this protein is not an intermediate in gag precursor processing. One lymphoma cell line is described that resembles a nonproducer RadLV-transformant, synthesizing relatively large amounts of p36 in the absence of Pr66gag or p30 production. Several RadLV-induced lymphoma cell lines also produce p36, while it was not detectable in the radiation-induced lines tested. In addition, p36 was not produced by mouse or mink fibroblasts or cultured thymocyte cell lines infected with virus passaged from the RadLV-induced lymphomas. We conclude that p36 may represent a previously unrecognized transformation-related protein induced directly or indirectly by infection with RadLV.

Enhanced responsiveness of endothelium in the growing/motile state to tumor necrosis factor/cachectin.

Some in vivo observations have suggested that growing or perturbed endothelium, such as that which occurs during angiogenesis, is more sensitive to the action of cytokines (TNF/cachectin, TNF, or IL-1) than normal quiescent endothelial cells. This led us to examine the responsiveness of endothelium to TNF as a function of the growth/motile state of the cell. TNF-induced modulation of endothelial cell surface coagulant function was half-maximal at a concentration of approximately 0.1 nM in subconfluent cultures, whereas 1-2 nM was required for the same effect in postconfluent cultures. Perturbation of endothelial cell shape/cytoskeleton was similarly more sensitive to TNF in subconfluent cultures. Consistent with these results, radioligand binding studies demonstrated high affinity TNF binding sites, Kd approximately 0.1 nM on subconfluent cultures, whereas only lower affinity sites (Kd approximately 1.8 nM) were detected on postconfluent cultures. The mechanisms underlying this change in the affinity of endothelium for TNF were studied in four settings. Crosslinking experiments with 125I-TNF and endothelium showed additional bands corresponding to Mr approximately 66,000 and approximately 84,000 with subconfluent cultures that were not observed with postconfluent cultures. Experiments with X-irradiated endothelium, whose growth but not motility was blocked, indicated that proliferation was not required for induction of high affinity TNF sites. Postconfluent endothelium, triggered to enter the proliferative cycle by microbutuble poisons, expressed high affinity TNF binding sites together with changes in cell shape/cytoskeleton well before their entry into S phase. Using wounded postconfluent monolayers, cells that migrated into the wound and those close to the wound edge displayed enhanced TNF binding and modulation of coagulant properties. These results suggest a model for targetting TNF action within the vasculature; regulation of high affinity endothelial cell binding sites can direct TNF to activated cells in particular parts of the vascular tree.

Procoagulant activity associated with plasma membrane vesicles shed by cultured tumor cells.

Thirteen of 14 tumor cells or tumor cell lines of guinea pig, mouse, and human origin spontaneously shed procoagulant activity in short-term (4 or 14 to 22 hr) tissue culture under conditions of high cell viability. This released procoagulant activity was pelletable in the ultracentrifuge and was associated with plasma membrane-derived vesicles as determined by transmission electron microscopy and marker enzyme analysis. The procoagulant activity shed corresponded to a substantial fraction of that expressed by intact or sonicated tumor cells and was composed of activities interacting at more than a single step in the clotting sequence. One procoagulant activity associated with shed human tumor vesicles behaved as tissue factor, requiring Factor VII for activity and being inhibited by a specific anti-bovine tissue factor antibody. Guinea pig tumor vesicles also exhibited tissue factor-like activity in a two-stage assay using homologous first-stage Factor VII/X concentrate. None of the human vesicles tested expressed a direct Factor X cleaving activity, independent of Factor VII. Shed tumor vesicles also acted at a second step late in the clotting cascade at the level of prothrombinase generation, presumably by providing a phospholipid surface. Taken together, these data indicate that a wide variety of tumor cells release plasma membrane vesicles with procoagulant activity. Such vesicles, as well as intact tumor cells themselves, may play an important role in the biology of tumor growth by inducing the local fibrin deposits found in association with many solid tumors.

Predictors of mortality and mortality from cardiac causes in the bypass angioplasty revascularization investigation (BARI) randomized trial and registry. For the BARI Investigators.

BACKGROUND: The impact of percutaneous transluminal coronary angioplasty (PTCA) and coronary artery bypass grafting (CABG) on long-term mortality rates in the presence of various demographic, clinical, and angiographic factors is uncertain in the population of patients suitable for both procedures. METHODS AND RESULTS: In the Bypass Angioplasty Revascularization Investigation (BARI) randomized trial and registry, 3610 patients who were eligible to receive PTCA and CABG were revascularized between 1989 and 1992. Multivariate Cox models were used to identify factors associated with 5-year mortality and cardiac mortality, with particular attention to factors that interact with treatment. Diabetic patients receiving insulin had higher mortality and cardiac mortality rates with PTCA compared with CABG (relative risk [RR] 1.78 and 2.63, respectively, P<0.001), and patients with ST elevation had higher cardiac mortality rates with CABG than with PTCA (RR 4.08, P<0.001). Factors most strongly associated with high overall mortality rates were insulin-treated diabetes, congestive heart failure, kidney failure, and older age. Black race was also associated with higher mortality rates (RR 1.49, P=0.019). CONCLUSIONS: A set of variables was identified that could be used to help select a revascularization procedure and to evaluate risk of long-term mortality in the population of patients considering revascularization.

Clinical outcome of deferring angioplasty in patients with normal translesional pressure-flow velocity measurements.

OBJECTIVES: The objective of this study was to determine the feasibility, safety and outcome of deferring angioplasty in patients with angiographically intermediate lesions that are found not to limit flow, as determined by direct translesional hemodynamic assessment. BACKGROUND: The clinical importance of some coronary stenoses of intermediate angiographic severity frequently requires noninvasive stress testing. Direct translesional pressure and flow measurements may assist in clinical decision making in patients with such stenoses. METHODS: Translesional spectral flow velocity (Doppler guide wire) and pressure data were obtained in 88 patients for 100 lesions (26 single-vessel and 74 multivessel coronary artery lesions) with quantitative angiographic coronary narrowings (mean +/- SD diameter narrowing 54 +/- 7% [range 40% to 74%]). Target lesion angioplasty was prospectively deferred on the basis of predetermined normal values, defined as a proximal/distal velocity ratio < 1.7 or a pressure gradient < 25 mm Hg, or both. Patients were followed up for 9 +/- 5 months (range 6 to 30). RESULTS: In the deferred angioplasty group, translesional velocity ratios were similar to those of a normal reference group (mean 1.1 +/- 0.32 vs. 1.3 +/- 0.55) and significantly lower than those of a reference cohort of patients who had undergone angioplasty (2.27 +/- 1.2, p < 0.05). The mean translesional pressure gradient in the deferred angioplasty group was also lower than that in the angioplasty group (10 +/- 9 vs. 45 +/- 22 mm Hg, p < 0.001). At follow-up in the deferred angioplasty group, four, six, zero and two patients, respectively, had had subsequent angioplasty, coronary artery bypass graft surgery or myocardial infarction or had died. In one patient, death was related to angioplasty of a nontarget artery lesion, and one patient with multivessel disease had a cardiac arrest due to ventricular fibrillation 12 months after lesion assessment. Among the 10 patients requiring later angioplasty or coronary artery bypass grafting, only six procedures were performed on target arteries. No patient had a complication of translesional flow or pressure measurements. CONCLUSIONS: These data demonstrate the safety, feasibility and clinical outcome of deferring angioplasty of coronary artery narrowings associated with normal translesional coronary hemodynamic variables. Given the practice of performing angioplasty without ischemic testing or when testing is inconclusive, translesional hemodynamic data obtained at diagnostic catheterization can identify patients in whom it is safe to postpone angioplasty.

Assessing the hemodynamic significance of coronary artery stenoses: analysis of translesional pressure-flow velocity relations in patients.

OBJECTIVES: The purpose of this study was to examine the relation among the angiographic severity of coronary artery lesions, coronary flow velocity and translesional pressure gradients. BACKGROUND: Determination of the clinical and hemodynamic significance of coronary artery stenoses is often difficult and inexact. Angiography has been shown to be an imperfect tool for determining the physiologic significance of eccentric or irregular coronary lumen narrowing. METHODS: Using a 0.018-in. (0.046 cm) intracoronary Doppler-tipped angioplasty guide wire, spectral flow velocity data both proximal and distal to coronary stenoses were compared with translesional pressure gradient measurements and angiographic data obtained during cardiac catheterization in 101 patients. There were 17 patients with normal angiographic findings and 84 with coronary artery disease, with lesions ranging from 28% to 99% diameter narrowing. Patients with coronary disease were assigned to two groups on the basis of translesional gradients at rest. Group A (n = 56) had gradients < 20 mm Hg, and Group B (n = 28) had gradients > or = 20 mm Hg. RESULTS: Proximal average peak velocity, diastolic velocity integral and total velocity integral were slightly but statistically lower in Group A; however, the distal average peak velocity and diastolic and total velocity integrals were all markedly (all p < 0.01) decreased in patients with gradients > or = 20 mm Hg (Group B). In addition, the ratio of proximal to distal total flow velocity integral was higher in Group B (2.4 +/- 1.0) than in group A (1.1 +/- 0.3, p < 0.001). There was a strong correlation between translesional pressure gradients and the ratios of the proximal to distal total flow velocity integrals (r = 0.8, p < 0.001), with a weaker relation between quantitative angiography and pressure gradients (r = 0.6, p < 0.001). In angiographically intermediate stenoses (range 50% to 70%), angiography was a poor predictor of translesional gradients (r = 0.2, p = NS), whereas the flow velocity ratios continued to have a strong correlation (r = 0.8, p < 0.001). Only two patients with a proximal/distal total flow velocity ratio < 1.7 had a translesional gradient > 30 mm Hg. Both patients had a very proximal lesion in a nonbranching right coronary artery. CONCLUSIONS: These data demonstrate that in branching human coronary arteries, a close relation exists between translesional hemodynamics and distal coronary flow velocity. Translesional coronary flow velocity is a new and easily applicable method for determining the hemodynamic significance of coronary artery stenoses that is superior to angiography and can be applied at the time of diagnostic catheterization. These data will provide a rational approach to making decisions on the use of coronary interventional techniques when angiographic findings are questionable.

Variations in normal coronary vasodilatory reserve stratified by artery, gender, heart transplantation and coronary artery disease.

OBJECTIVES: The purpose of the study was to assess the spectrum of coronary vasodilatory reserve values in patients with angiographically normal arteries who had atypical chest pain syndromes or remote coronary artery disease or were heart transplant recipients. BACKGROUND: The measurement of post-stenotic coronary vasodilatory reserve, now possible in a large number of patients in the cardiac catheterization laboratory, is increasingly used for decision making. Controversy exists regarding the range of normal values obtained in angiographically normal coronary arteries in patients with different clinical presentations. METHODS: Quantitative coronary arteriography was performed in 214 patients classified into three groups: 85 patients with chest pain syndromes and angiographically normal arteries (group 1); 21 patients with one normal vessel and at least one vessel with > 50% diameter lumen narrowing (group 2); and 108 heart transplant recipients (group 3). Coronary vasodilatory reserve (the ratio of maximal to basal average coronary flow velocity) was measured in 416 arteries using a 0.018-in. (0.04 cm) Doppler-tipped angioplasty guide wire. Intracoronary adenosine (8 to 18 micrograms) was used to produce maximal hyperemia. RESULTS: Coronary vasodilatory reserve was higher in angiographically normal arteries in patients with chest pain syndromes (group 1:2.80 +/- 0.6 [group mean +/- SD]) than in normal vessels in patients with remote coronary artery disease (group 2: 2.5 +/- 0.95, p = 0.04); both values were significantly higher than those in the post-stenotic segment of the diseased artery (1.8 +/- 0.6, p < 0.007). Coronary vasodilatory reserve in transplant recipients (group 3) was higher than that in the other groups (3.1 +/- 0.9, p < 0.05 vs. groups 1 and 2) as a group and for individual arteries. When stratified by vessel, coronary vasodilatory reserve was similar among the left anterior descending, left circumflex and right coronary arteries. There were no differences between coronary vasodilatory reserve values on the basis of gender for patients with coronary artery disease and transplant recipients. In group 1 (chest pain), there was a trend toward higher coronary vasodilatory reserve in men than in women (2.9 +/- 0.6 vs 2.7 +/- 0.6, p = 0.07). CONCLUSIONS: These findings identify a normal reference range for studies assessing the coronary circulation and post-stenotic coronary vasodilatory reserve in patients with and without coronary artery disease encountered in the cardiac catheterization laboratory.

Risk stratification after successful coronary revascularization: the lack of a role for routine exercise testing.

OBJECTIVE: The objective of this study was to evaluate the American College of Cardiology/American Heart Association (ACC/AHA) guidelines for exercise testing (EXT) after successful coronary revascularization (CR) using the Bypass Angioplasty Revascularization Investigation experience. BACKGROUND: The ACC/AHA guidelines state that EXT within three years of successful CR is not useful. METHODS: The 1,678 patients randomized to CR by either angioplasty or bypass surgery were required to take symptom-limited treadmill tests one, three and five years after revascularization. RESULTS: Patients who took the test at each specified time had a much lower subsequent two-year mortality than those who did not (1.9% vs. 9.4%, 3.5% vs. 12.6% and 3.3% vs. 11.0% at one, three and five years, respectively, after CR [p < 0.0001 for each]). Exercise parameters at the one- and three-year test did not improve a multivariable model of survival after including clinical parameters. Exercising to Bruce stage 3 or generating a Duke score >-6 were independently predictive of two-year survival after the five-year test. ST depression on the one-year test was associated with more revascularizations (relative risk = 1.6; p < 0.001). CONCLUSIONS: Patients with stable multivessel coronary disease who took a protocol-mandated exercise test at one, three and five years after revascularization were at low risk for mortality in the two years subsequent to each test. Exercise parameters did not improve prediction of mortality in the two years after the one- and three-year tests. The ACC/AHA guidelines on exercise testing after CR (no value for routine testing in stable patients for three years after revascularization) are supported by these results.

Role of coronary artery lumen enlargement in improving coronary blood flow after balloon angioplasty and stenting: a combined intravascular ultrasound Doppler flow and imaging study.

OBJECTIVES: This study sought to examine the mechanism of increasing coronary flow reserve after balloon angioplasty and stenting. BACKGROUND: Coronary vasodilatory reserve (CVR) does not improve after percutaneous transluminal coronary angioplasty in > or = 50% of patients, postulated to be due to impaired microvascular circulation or inadequate lumen expansion despite adequate angiographic results. METHODS: To demonstrate the role of coronary lumen expansion, serial coronary flow velocity (0.014-in. Doppler guide wire) was measured in 42 patients before and after balloon angioplasty and again after stent placement. A subset (n = 17) also underwent intravascular ultrasound (IVUS) imaging of the target sites after angioplasty and stenting. CVR (velocity) was computed as the ratio of adenosine-induced maximal hyperemic to basal average peak velocity. RESULTS: The percent diameter stenosis decreased from (mean +/- SD) 84 +/- 13% to 37 +/- 18% after angioplasty and to 8 +/- 8% after stenting (both p < 0.05). CVR was minimally changed from 1.70 +/- 0.79 at baseline to 1.89 +/- 0.56 (p = NS) after angioplasty but increased to 2.49 +/- 0.68 after stent placement (p < 0.01 vs. before and after angioplasty). IVUS lumen cross-sectional area was significantly larger after stenting than after angioplasty (8.39 +/- 2.09 vs. 5.10 +/- 2.03 mm2, p < 0.05). Anatomic variables were related to increasing coronary flow velocity reserve (CVR vs. IVUS lumen area: r = 0.47, p < 0.005; CVR vs. quantitative coronary angiographic percent area stenosis: r = 0.58, p < 0.0001). CONCLUSIONS: In most cases, increases in CVR were associated with increases in coronary lumen cross-sectional area. These data suggest that impaired CVR after angioplasty is often related to the degree of residual narrowing, which at times may not be appreciated by angiography. A physiologically complemented approach to balloon angioplasty may improve procedural outcome.

Influence of hemodialysis on the mean blood flow velocity in the middle cerebral artery.

BACKGROUND: Several effects of hemodialysis, including hemoconcentration, alterations of hemostasis or hemorheology and endothelial activation, could potentially interfere with cerebral blood flow (CBF) regulation. These treatment-specific changes may also be crucial for the enhanced incidence of stroke in uremic patients. Nevertheless, the influence of hemodialysis on CBF has not been yet adequately studied. PATIENTS AND METHODS: We registered mean blood flow velocity (MFV) in the middle cerebral artery (MCA) during hemodialysis treatment in order to evaluate its contribution on CBF changes. Transcranial Doppler ultrasonography (TCD) of the MCA was performed continuously during hemodialysis treatment in 18 stable patients (10 males and 8 females, mean age 62 +/- 11 years) with end-stage renal disease of various origin. Blood pressure (mmHg), heart rate (/min), ultrafiltration volume (ml), BV changes (deltaBV by hemoglobinometry, %), arterial blood gases (pO2, blood oxygen content, pCO2), hemostasis activation (thrombin-antithrombin III complex, ELISA) and fibrinogen (Clauss) were measured simultaneously at the beginning of treatment and every hour thereafter. RESULTS: Before the hemodialysis session the MFV in the MCA was within normal range (57.5 +/- 13.0 cm/s, ref. 60 +/- 12) and was mainly dependent on the patients' age (r = -0.697, p < 0.01). The blood flow velocity in the MCA decreased significantly from 57.5 +/- 13.0 cm/s before the beginning to 48.3 +/- 11.1 cm/s after four hours (n = 18, p < 0.05) and to 43.9 +/- 8.9 cm/s after five hours (n = 9, p < 0.05) of hemodialysis treatment. During hemodialysis treatment, the percentual changes of MFV in the MCA (delta%MFV) were interrelated to the ultrafiltration volume (r = -0.486, p < 0.01), the blood volume (BV%, r = 0.369, p < 0.01) and the percentual changes of the hematocrit (r = -0.358, p < 0.01), of the arterial blood oxygen content (delta%acO2, r = -0.420, p < 0.01) and of the plasma fibrinogen levels (delta%fibrinogen, r = 0.244, p < 0.05). CONCLUSION: A significant continuous decrease of the MFV in the MCA was observed during hemodialysis treatment, which inversely correlated both with ultrafiltration volume, BV changes and changes of plasma fibrinogen. The ultrafiltration-induced hemoconcentration with concomitant rise of hematocrit and oxygen transport capacity, may partly explain the alterations in the cerebral MFV observed during hemodialysis.

Role of smooth muscle cell death in advanced coronary primary lesions: implications for plaque instability.

OBJECTIVE: Instability of coronary atheroma leads to the onset of acute coronary syndromes including myocardial infarction and death, as well as to the progression of the arteriosclerotic disease. As yet, the underlying factors and mechanisms causing plaque rupture are not completely understood. Since a low content of smooth muscle cells (SMCs) apparently plays a key role, the question points to the events leading to the loss of intimal SMCs. METHODS: We compared coronary atherectomy specimens from 25 patients with unstable angina to those from 25 patients with stable angina. Transmission electron microscopy was used to identify intimal cell population, to detect stage and cell type of apoptosis, and to differentiate between apoptosis and necrosis. RESULTS: Plaques associated with unstable angina contained more macrophages/lymphocytes and significantly less SMCs (P = 0.01), compared with stable angina plaques. Specific cell death forms, apoptosis and necrosis, were present in all coronary atheroma. As key findings, both the proportion of SMCs undergoing apoptosis and the frequency of cytoplasmic remnants of apoptotic SMCs (matrix vesicles) were significantly increased in unstable versus stable angina lesions (P = 0.002 and P = 0.002). In addition, cellular necrosis was more frequent in the first coronary atheroma group (P = 0.02). Positive correlations were found between the frequency of apoptotic cells and necrosis (r = 0.41, P = 0.04), and that of matrix vesicles and necrosis (r = 0.63, P = 0.001) only in plaques with unstable angina, but not in those with stable angina. CONCLUSIONS: Our data demonstrate that high cell death due to apoptosis and necrosis is a basic in situ feature found in advanced coronary primary lesions associated with unstable angina, possibly explaining their low density of (viable) SMCs. Thus, antagonization of intimal cell death should be considered in order to stabilize the intimal plaque texture of coronary atheroma with the ultimate goal to prevent plaque rupture.

Interleukin-2 receptor-specific fusion toxin inhibits barotrauma-induced arterial atherosclerosis.

Immunocytochemical analyses of human plaques and experimental arterial lesions have implicated activated lymphocytes and monocytes in the pathogenesis of atherosclerosis, as demonstrated by the expression of interleukin-2 (IL-2) membrane receptors and major histocompatibility complex class II epitopes. The objective is to determine if targeting these cells with an IL-2 receptor-specific chimeric toxin, DAB486-IL-2, can inhibit experimental post-angioplasty vascular neointimal thickening. Twenty-two atherogenically modeled rabbits were treated in vivo with DAB486-IL-2 (0.1 mg/kg per day i.v.; n = 11) or placebo (n = 11) for 10 days following aortic balloon angioplasty (4 atm x 30 s each x 2 dilatations). In vitro 3H-leucine incorporation studies of mononuclear leukocyte and vascular smooth muscle cell protein synthesis inhibition by DAB486-IL-2 were also performed. Angioplasty sites were examined for evidence of hyperproliferative atherosclerotic narrowing by quantitative angiography and histomorphometry of neointimal cross-sectional area at baseline and 6 weeks after injury. In vitro Concanavalin-A stimulated rabbit mononuclear leukocyte protein synthesis was 50% inhibited by DAB486-IL-2 at a concentration (IC50) of 6 x 10(-11) M. Rabbit vascular smooth muscle cells were approximately 150-fold less sensitive to DAB486-IL-2 (IC50 = 10(-8) M). In vivo studies showed no change in angioplasty site angiographic minimum luminal diameter at 6 weeks in DAB486-IL-2 treated animals (from 2.96 +/- 0.52 to 2.96 +/- 0.48 mm; percent cross-sectional area reduction = 1 +/- 10%; P = N.S.). In control animals, luminal diameter decreased from 2.79 +/- 0.4 to 2.32 +/- 0.52 mm at 6 weeks, and percent cross-sectional area was reduced by 34 +/- 14% (P < 0.01 vs. placebo). Quantitative histomorphometric angioplasty segmental intimal cross-sectional area reduction of treated and placebo vessels also differed significantly (19 +/- 16% vs. 31 +/- 21%; P < 0.05). DAB486-IL-2 caused no adverse effects on animal survival, weight or hepatic transaminase levels. We conclude that post-angioplasty administration of the chimeric toxin DAB486-IL-2 inhibits angiographic narrowing and neointimal thickening in the atherogenic rabbit model. Although this IL-2 receptor-specific molecule was cytotoxic in vitro for activated mononuclear leukocytes and vascular smooth muscle cells, systemic toxicity did not occur in vivo at a dose comparable to that evaluated in clinical trials of this agent. Potential anti-proliferative effects of this chimeric toxin may be mediated by direct local inhibition of leukocyte-mediated inflammation, or through the indirect modification of vascular cell mitogenesis and cytokine release.

Induction of endothelial tissue factor by endotoxin and its precursors.

The structural determinants of lipopolysaccharide required for the induction of tissue factor in human umbilical vein endothelial cells were studied. Intact lipid A was essential for the induction of tissue factor whereas the incomplete lipid A precursors lipid IVA and lipid X, as well as monophosphoryl lipid A and acyloxyacyl hydrolase-treated lipopolysaccharide, were unable to induce tissue factor and tissue factor specific mRNA. However, the lipid A precursor, lipid IVA, was able to inhibit LPS-mediated induction of tissue factor; structural determinants distal to lipid A were found to be required for maximal induction of tissue factor activity and tissue factor mRNA. The presence of serum in the assay was found to amplify but was not obligate for tissue factor induction by LPS.

Molecular cloning, characterization and expression of cDNA for rabbit brain tissue factor.

Tissue factor (TF) is a membrane anchored glycoprotein that initiates blood coagulation by forming a complex with circulating factor VII or VIIa. TF has been identified in atherosclerotic plaques and may possibly trigger thrombosis after spontaneous plaque rupture as seen in acute myocardial infarction or angioplasty. We have previously developed an atherosclerotic rabbit model for study of the acute and chronic outcomes following angioplasty. As a first step in developing inhibitors of TF, we have isolated and characterized a rabbit cDNA coding for the mature TF. The sequence comparison of rabbit TF cDNA with those of human and mouse TFs show considerable similarity at both the nucleotide and amino acid levels. The TF cDNA when expressed in E. coli demonstrates a procoagulant activity comparable to that of native rabbit brain TF. The TF activity can be blocked by a polyclonal antibody against rabbit TF.

Induction of tissue factor procoagulant activity in myelomonocytic cells inoculated by the agent of human granulocytic ehrlichiosis.

Human granulocytic ehrlichiosis (HGE) is a recently recognized rickettsial tick-borne febrile illness that may occasionally be complicated by coagulopathy. The agent of HGE (aHGE) is an obligate intracellular pathogen, which replicates in endosomes within neutrophils and their precursors. We hypothesized that aHGE might cause DIC via induction of monocyte tissue factor procoagulant activity (TF PCA). Peripheral blood mononuclear cells (PBMNC) and HL-60 cells were used to model the effect of aHGE infection on monocytes/macrophages. Mononuclear cells inoculated with aHGE in vitro demonstrated approximately a 12-15-fold increase in TF PCA, with peak activity occurring at 8-12 h. HL-60 cells inoculated with aHGE also manifested a 4-6 fold induction of TF PCA, with maximal activity occurring at about 8 h. By comparison, E. Coli lipopolysaccharide (LPS) also induced an increase in TF PCA of an equivalent magnitude, and with a similar time course. Induction of TF did not require inoculation of HL-60 cells with live organism, since heat-inactivated aHGE still stimulated TF PCA expression in the target cells. Furthermore, filtered supernatants from heat-inactivated organisms induced TF PCA suggesting that the effect is due to a soluble mediator produced by the organism. Although aHGE is a gram negative organism, the soluble mediator did not appear to be classic endotoxin in that the supernatants tested negative for endotoxin by the Limulus Amoebocyte assay, and polymixin had no inhibitory effect on aHGE supernatants. We conclude that aHGE induces cells of the myelo-monocytic lineage to synthesize TF, which may contribute to the clinical coagulopathy that can be observed in this condition. An atypical soluble mediator or cellular component of the organism appears to be critically important in TF induction by aHGE.

Whole blood tissue factor procoagulant activity remains detectable during severe aplasia following bone marrow and peripheral blood stem cell transplantation.

Using a novel whole blood assay, we recently demonstrated that tissue factor procoagulant activity (TF PCA) is present in normal individuals. Preliminary experiments suggested that this activity is localized in the mononuclear cell fraction. Postulating that whole blood TF PCA would therefore be undetectable when monocytes and neutrophils are absent from peripheral blood, we assayed TF PCA during the peri-transplant period in 15 consecutive patients undergoing allogeneic (n = 12) or autologous (n = 3) bone marrow transplantation (BMT) or peripheral blood stem cell transplantation (PBSCT). Baseline (pre-transplant) mean TF PCA was higher in patients compared to normal controls (P <0.005). Unexpectedly, although TF PCA during the period of profound aplasia was significantly reduced compared to baseline (p <0.05), fully 55% of the initial activity remained detectable. During the engraftment phase, TF PCA returned to pre-transplant levels, with a linear correlation between monocyte counts and TF PCA (r = 0.63). In contrast to normal whole blood, incubation of aplastic samples with E. Coli lipopolysaccharide ex vivo failed to induce TF PCA. Throughout the period of study--but especially during the aplastic phase--the absolute number of circulating endothelial cells (CECs) that were TF antigen-positive was increased compared to normals (P <0.001). However, removal of these cells from whole blood samples failed to significantly diminish total TF PCA indicating that CECs alone could not account for the detectable TF PCA during aplasia. We conclude that neither circulating mature myelo-monocytic cells nor endothelial cells can account for all the functionally intact TF in peripheral blood. Further studies are needed to identify the other source(s) of TF PCA.

Long-acting angiotensin-converting enzyme inhibition: once-daily lisinopril versus twice-daily captopril in mild-to-moderate heart failure.

Once-daily lisinopril (5-20 mg) was compared with twice-daily captopril (12.5-50 mg) in a double-blind, randomized, parallel-group study of angiotensin-converting enzyme (ACE) inhibition conducted in 31 centers for 12 weeks in patients with heart failure (New York Heart Association class II-III) who were currently receiving digitalis and/or diuretics. The drugs were compared with regard to their effects on exercise duration, measured with bicycle ergometry, and on ectopic activity, measured using Holter monitoring. Both drugs significantly increased exercise duration after both 6 and 12 weeks of randomized treatment. Neither ACE inhibitor had any significant impact on the hourly rate of either ventricular ectopic counts or couplets, nor was there any difference between treatments with regard to the proportions of patients in whom ventricular ectopic counts were reduced. Both drugs were well tolerated, with no differences observed between treatments. Potassium, urea, and creatinine levels remained stable for both treatments throughout the study.

Treatment of unstable angina pectoris (European experience).

Unstable angina pectoris is used to describe accelerated angina, new onset of angina, or prolonged angina. The natural history of the angina varies according to clinical presentation. The 1-year mortality rate ranges from 2% to nearly 40%. Specific therapy includes nitrates, beta-adrenergic blockers, and/or calcium antagonists as well as antithrombotic therapy in the form of aspirin. Patients with severe angina at rest and ST- and T-wave changes should be admitted to a coronary care unit where full-dose heparin is administered. Coronary angiography should be performed in individuals who fail to respond to the conventional therapy in order to evaluate other therapeutic options, including percutaneous transluminal coronary angioplasty (PTCA) and coronary bypass surgery. In some cases, especially in patients with intracoronary thrombus, thrombolytic therapy may be beneficial.

Effects of percutaneous transluminal coronary angioplasty balloon compliance on angiographic and clinical outcomes.

The effect of balloon compliance on the safety and outcome of percutaneous transluminal coronary angioplasty (PTCA) is controversial. It has been proposed that PTCA balloons constructed from compliant polymers contribute to an increased risk of angiographic coronary dissection and potentially to adverse clinical results. To determine the effect of balloon material compliance on PTCA outcome, 1,076 PTCA procedures using balloons differing in compliance characteristics (polyethylene teraphthalate [noncompliant], polyethylene [intermediately compliant] or polyolefincopolymer [compliant]) were retrospectively analyzed. Baseline clinical, angiographic and procedural variables were similar among the 3 balloon material groups. In the noncompliant, intermediately compliant and compliant groups, the occurrence rates of intimal tears (10, 14 and 10%, respectively; p = NS for all comparisons) and coronary dissection (7, 9 and 8%, respectively; all p = NS) were also equivalent. The rates of acute occlusion, myocardial infarction, emergency bypass surgery and death were low and similar, and likewise unaffected by balloon material. The results provide evidence that the occurrence of adverse outcomes after PTCA is unrelated to balloon material compliance and support the clinical safety of balloons constructed of compliant or noncompliant polymers when used for appropriate coronary interventions.