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Background: Abnormal values of the transient ischemic dilation (TID) ratio are associated with severe and extensive coronary artery disease (CAD). The objective of this study was to determine the relationship between TID, determined from stress and rest ventricular volumes during regadenoson gated single-photon emission computed tomography myocardial perfusion imaging (MPI) dual isotope studies, and the extent of CAD found during coronary angiography., Methods: 195 patients who underwent dual isotope MPI with regadenoson and cardiac angiography between March 2009 and February 2010 were analyzed. TID was calculated using commercially available software, Emory Cardiac Toolbox. Mean TID values were compared across disease types. A threshold for abnormal TID was determined by adding two standard deviations (SDs) to the mean TID of the "non-obstructive CAD" subgroup., Results: In the 195-patient group analyzed, the mean TID ratio for non-obstructive CAD (n = 104) was found to be 1.09 with a SD of 0.15. In a subgroup of patients whose angiogram was within 3 months of MPI (n = 155), the mean TIDs for non-obstructive disease (n = 81), single-vessel disease (n = 35), and multi-vessel disease (n = 39) were 1.09, 1.15, and 1.19 with SDs of 0.16, 0.19, and 0.26, respectively. Those with an abnormal TID had a crude and adjusted odds ratio of 3.4 for multi-vessel disease which was statistically significant. History of diabetes was not found to be a significant confounder, effect modifier, or mediator of the relationship between the TID and the vessel disease., Conclusion: The mean TID ratio in patients with multi-vessel disease was 1.19. The threshold for an abnormal TID was 1.39 with specificity of 95% and sensitivity of 15% for determining multi-vessel CAD status. We conclude that the level of TID in gated SPECT MPI using regadenoson is associated with the degree of CAD on angiography.

Imaging metabolic processes in the human heart yields valuable insights into the mechanisms contributing to myocardial pathology and allows assessment of the efficacy of therapies designed to treat cardiac disease. Recent advances in fatty acid (FA) imaging using positron emission tomography (PET) include the development of a method to assess endogenous triglyceride metabolism and the design of new fluorine-18 labeled tracers. Studies of patients with diabetes have shown that the heart is resistant to insulin-mediated glucose uptake and that metabolism of nonesterified FA is upregulated. Cardiac PET imaging has also recently shown the increase in myocardial FA uptake seen in obese patients can be reversed with weight loss. And a pilot study of patients with chronic kidney disease demonstrated that PET imaging can reveal myocardial metabolic alterations that parallel the decline in estimated glomerular filtration rate. Recent advances in FA imaging using single photon emission computed tomography (SPECT) have been accomplished with the tracer β-methyl-p-[(123)I]-iodophenyl-pentadecanoic acid (BMIPP). Two meta-analyses showed this imaging technique has a diagnostic accuracy for the detection of obstructive coronary artery disease that compares favorably with SPECT myocardial perfusion imaging and that BMIPP imaging yields excellent prognostic data in patients across the spectrum of coronary artery disease. A recent multicenter study of patients presenting with acute coronary syndromes found BMIPP SPECT imaging has greater diagnostic sensitivity than, and enhances the negative predictive value of, clinical assessment alone. Because of their exquisite sensitivity, nuclear imaging techniques facilitate the study of physiologic processes that are the key to our understanding of cardiac metabolism in health and disease.

Background: The significance of ischemic ECG changes during adenosine infusion in patients with normal myocardial perfusion imaging (MPI) is controversial. We evaluated the prevalence of, and defined the predictors for, severe coronary artery disease (CAD) in patients with such discordant findings., Methods: The findings of 3700 adenosine MPI studies performed at our institution between June 2005 and March 2009 were reviewed., Results: Data for 76 patients who had not previously undergone coronary revascularization and who had sufficient follow-up were analyzed; 22 (29%) were referred for coronary angiography and 10 (13%) underwent revascularization. None had left main disease and only three (14%) had multivessel disease. Diabetes mellitus was more prevalent (70% vs. 23%; P = .010) and ischemic ST-segment depressions more often lasted >5 minutes (50% vs. 15%; P = 0.021) in patients undergoing revascularization. During a 24 ± 13 month follow-up period, there were no deaths or myocardial infarctions, while an eleventh patient underwent revascularization 19 months after MPI., Conclusions: In the presence of normal MPI, the specificity of ischemic ECG changes during adenosine infusion for the detection of severe obstructive CAD is poor, although patients with multiple coronary risk factors, particularly diabetes mellitus, should undergo further investigation.

Objectives: To investigate the prevalence of coronary artery disease (CAD) in active New York City police officers as detected by coronary artery calcium (CAC) scoring., Methods: We assessed 2064 New York City police officers who underwent electron beam computed tomography for quantification of CAC., Results: The mean age of study subjects was 42 +/- 6 years. A CAC score of 0 was present in 74% of men and 80% of women. A subset of 75 officers with known early exposure to World Trade Center dust were evaluated separately., Conclusion: New York City police officers do not have an increased prevalence of CAD compared with the general population as assessed with CAC scoring. At 5 years, exposure to World Trade Center dust does not appear to increase the risk of premature CAD.

Background: Nuclear stress imaging is used frequently to evaluate patients with end-stage liver disease who are being considered for orthotopic liver transplantation., Methods and Results: We present three patients who, following graft failure, developed sinus arrest during adenosine stress testing performed in anticipation of repeat liver transplantation. All had undergone uneventful adenosine stress imaging prior to initial transplantation. The mechanisms of action, pharmacokinetics, and pharmacodynamics of adenosine are reviewed, and possible reasons for this phenomenon are discussed. Finally, cautions regarding the use of adenosine and treatment of adenosine-induced sinoatrial and atrioventricular block are reviewed., Conclusion: Adenosine should be used with caution in patients following orthotopic liver transplantation due to an increased risk of sinus arrest. Should sinus arrest or atrioventricular block occur, it appears to respond readily to cessation of adenosine infusion and intravenous aminophylline with no significant sequelae.

Percutaneous coronary intervention (PCI) has become a mainstay in the treatment of patients with coronary artery disease. Currently, more than one million coronary angioplasty and stent implantation procedures are performed annually. Although increasingly complex lesions and higher risk patients are being successfully treated percutaneously, restenosis and disease progression continue to cause significant morbidity. Restenosis occurs in approximately one-third of patients, one-half of who remain asymptomatic, while disease progression occurs at rates approaching 7% per year. Despite technological advances, unadjusted mortality rates have actually increased since the mid-1980s, and the current annual risk of a major adverse cardiac event following PCI is 5% to 7%. Although randomized clinical trials are needed to more definitively show a benefit, when performed six or more months following PCI, myocardial perfusion imaging reliably identifies patients most at risk of a poor long-term outcome. Directed reintervention can have a salutary impact on the prognosis of these patients. In view of recent data showing a positive impact of imaging and reintervention in patients after PCI, current guidelines should be reassessed.

Purpose: Intracoronary gamma or beta radiation from centrally located sources at the time of overstretch balloon injury inhibits neointimal proliferation. In an effort to deliver homogeneous, centered radiation fields in a technically straightforward fashion, we studied the effects of a beta-emitting solution used as a balloon inflation fluid to deliver radiation at the time of coronary injury., Methods: Twenty-one coronary arteries in 13 juvenile swine underwent irradiation (control and 11 or 25 Gy media dose). Radiation was delivered using a perfusion balloon inflated with an Re-188 solution. Subsequently, overdilatation percutaneous transluminal coronary angioplasty was performed at the pretreated segment. Histopathologic and histomorphometric analysis was performed at 30 days after injury on the entire irradiated artery., Results: Balloon overdilation was associated with significant vascular injury and marked neointimal proliferation in control and low-dose (11 Gy)-treated arteries. High-dose radiation (25 Gy) significantly inhibited neointima formation compared with controls (neointimal area: 0.49 +/- 0.29 mm2 vs. 1.51 +/- 0.22 mm2, respectively; p = 0.02) and low-dose radiation (neointimal area 1.75 +/- 0.54 mm2, p > 0.1 compared with controls)., Conclusions: Liquid Re-188 is an effective beta-emitting vehicle to deliver intracoronary radiation and prevent restenosis in this model. Intracoronary radiation treatment using aqueous radioisotope sources is technically straightforward and provides the optimally achievable radiation dose distribution.

Platelet-derived growth factor (PDGF)-induced smooth muscle cell (SMC) fibrinolysis is necessary for SMC migration. In order to determine whether the T-cell lymphokines interleukin-4 (IL-4) and gamma interferon (gamma-IFN) affect SMC fibrinolysis and migration, we examined the effects of human recombinant IL-4 and gamma-IFN on human aortic SMC tissue-type plasminogen activator (TPA), urokinase-type plasminogen activator (UPA), and plasminogen activator inhibitor type-1 (PAI-1) antigen production, as determined by enzyme-linked immunosorbent assays. Although IL-4 had no direct effect on SMC TPA antigen, IL-4 potentiated SMC TPA antigen levels and activity in conditioned media and cellular lysates in media containing 2% fetal bovine serum but did not change UPA or PAI-1 production. gamma-IFN attenuated IL-4 augmentation of SMC TPA antigen production in conditioned media, although gamma-IFN itself had no direct effects on SMC TPA and PAI-1 antigen production. IL-4 augmented PDGF induction of SMC TPA antigen. gamma-IFN inhibited PDGF induction of SMC TPA antigen and IL-4 potentiation of this process. gamma-IFN diminished the promigratory effects of both IL-4 and PDGF on in vitro SMC migration. Tranexamic acid, a plasmin inhibitor, abrogated the stimulation of SMC migration by IL-4. Therefore, IL-4 and gamma-IFN modulate the induction of SMC TPA and SMC migration by 2% fetal bovine serum and PDGF.

The binding of human erythrocyte ankyrin (band 2.1) to the erythrocyte membrane has been characterized by reassociating purified ankyrin with ankyrin-depleted inside-out vesicles. Ankyrin reassociates at high affinity with a limited number of protease-sensitive sites located only on the cytoplasmic side of the erythrocyte membrane. Depleting the vesicles of band 4.2 does not affect their binding capacity. A 45,000-dalton polypeptide derived from the cytoplasmic portion of band 3 competitively inhibits the binding of ankyrin to inside-out vesicles. Although the bulk of band 3 molecules appear to have the potential for binding ankyrin, nly a fraction of the band 3 molecules in native membranes or in reconstituted liposomes actually provides accessible high affinity ankyrin binding sites.

Neutrophils respond to a variety of stimuli by generating superoxide anion, degranulating, and aggregating. Because it has been suggested that fusion of granules with the plasmalemma (degranulation) is necessary for aggregation and superoxide anion generation, we have tested whether these responses can be demonstrated in "neutrophilic cytoplasts" (granule-free vesicles of cytoplasm enclosed by plasmalemma). When examined by electron microscopy, cytoplasts were found to be approximately 4 microns in diameter and essentially granule free. Cytoplasts exposed to fMet-Leu-Phe (0.1 microM) generated superoxide anion after a lag of 16 sec but released no detectable beta-glucuronidase, lysozyme, or elastase. Aggregation of cytoplasts, as measured by changes in light transmission, was also activated by fMet-Leu-Phe; no lag period was observed. Electron microscopy of the aggregates demonstrated clusters of cytoplasts with a scalloped appearance. Superoxide anion generation and aggregation of cytoplasts were also activated by phorbol 12-myristate 13-acetate, concanavalin A, and leukotriene B4. Exposure of cytoplasts to the dye 3,3'-dihexyloxacarbocyanine iodide (DiOC6(3)] led to dye uptake and enhancement of fluorescence, implying that the vesicles were sealed and maintained a membrane potential across the plasmalemma. Exposure of DiOC6(3)-loaded cytoplasts to fMet-Leu-Phe and PMA caused a rapid loss of dye fluorescence that was not inhibited by CN-, compatible with their lack of mitochondria. Exposure of dye-loaded cytoplasts to concanavalin A or leukotriene B4 caused an increase in fluorescence--i.e., a hyperpolarization. These results demonstrate that degranulation is not a prerequisite for aggregation or superoxide anion generation. The retention of ionic gradients and changes in membrane potential, as measured by DiOC6(3) fluorescence changes, suggest a fundamental role for ionic movements in activating superoxide anion generation and aggregation.

Leukotriene B4 [LTB4, (5S,12R)-hydroxyeicosa-6,14-cis-8,10-trans-tetraenoic acid], a potent mediator of inflammation, is released from neutrophils by agonists that provoke degranulation of the cell. To examine whether degranulation is a necessary requirement for synthesis and metabolism of LTB4 (or of other arachidonate metabolites), we prepared neutrophil-derived cytoplasts (neutroplasts), organelle-depleted vesicles of cytoplasm surrounded by the plasma membrane. In the presence of extracellular Ca2+ with or without exogenous arachidonic acid (150 microM), neutroplasts were exposed to the Ca2+ ionophore A23187 (10 microM) and the resultant lipoxygenation products of arachidonate were determined. Neutrophils metabolize arachidonic acid to 5-HETE greater than 15-HETE greater than LTB4 greater than all-trans-LTB4 isomers. Neutroplast products of arachidonate lipoxygenation were 15-HETE greater than 5-HETE greater than LTB4 greater than all-trans-LTB4 isomers. Neutroplasts, like neutrophils, were capable of converting LTB4 into its 20-hydroxy and 20-carboxy metabolites. Finally, neutroplasts could utilize intrinsic arachidonate, since the neutroplasts synthesized LTB4 (30 pmol/mg of protein) in the absence of added arachidonic acid. The data demonstrate that neutrophil degranulation is not required for synthesis or metabolism of LTB4 by neutrophils.

Neutroplasts, which are vesicles consisting of cytoplasm enclosed by plasmalemma, have been prepared and found to be incapable of degranulation in response to f-Met-Leu-Phe. However, neutroplasts generate superoxide anion in response to f-Met-Leu-Phe and PMA, and therefore, degranulation is not essential for superoxide anion generation. In addition, neutroplasts aggregate and show shape changes in response to f-Met-Leu-Phe and PMA, and thus degranulation is not essential for aggregation. Neutroplasts take up the carbocyanine dye DiOC6(3), thereby providing evidence for ionic gradients. Dye-loaded neutroplasts show fluorescence changes in response to a variety of stimuli. This response is not CN--inhibitable; therefore, activation of neutroplasts is associated with changes in membrane potential at the plasmalemma, suggesting a role for ion fluxes in the activation sequence for aggregation and superoxide anion generation.

Leukotriene B4 (5S,12R-dihydroxy-6,14-cis,8,10-trans-eicosatetraenoic acid, LTB4) is released from neutrophils exposed to calcium ionophores. To determine whether LTB4 might be produced by ligand-receptor interactions at the plasmalemma, we treated human neutrophils with serum-treated zymosan (STZ), heat-aggregated IgG and fMet-Leu-Phe (fMLP), agonists at the C3b, Fc and fMLP receptors respectively. STZ (10 mg/ml) provoked the formation of barely detectable amounts of LTB4 (0.74 ng/10(7) cells); no omega-oxidized metabolites of LTB4 were found. Adding 10 microM-arachidonate did not significantly increase production of LTB4 or its metabolites. Addition of 50 microM-arachidonate (an amount which activates protein kinase C) before STZ caused a 40-fold increase in the quantity of LTB4 and its omega-oxidation products. Neither phorbol myristate acetate (PMA, 200 ng/ml) nor linoleic acid (50 microM), also activators of protein kinase C, augmented generation of LTB4 by cells stimulated with STZ. Neither fMLP (10(-6) M) nor aggregated IgG (0.3 mg/ml) induced LTB4 formation (less than 0.01 ng/10(7) cells). Moreover, cells exposed to STZ, fMLP, or IgG did not form all-trans-LTB4 or 5-hydroxyeicosatetraenoic acid; their failure to make LTB4 was therefore due to inactivity of neutrophil 5-lipoxygenase. However, adding 50 microM-arachidonate to neutrophil suspensions before fMLP or IgG triggered LTB4 production, the majority of which was metabolized to its omega-oxidized products (fMLP, 20.2 ng/10(7) cells; IgG, 17.1 ng/10(7) cells). The data show that neutrophils exposed to agonists at defined cell-surface receptors produce significant quantities of LTB4 only when treated with non-physiological concentrations of arachidonate.

Crystalline monosodium urate (MSU) produces inflammation in vivo and kills phagocytes in vitro. A plausible hypothesis to account for crystal-induced cell death is that ingested crystals perforate the phagocytic vacuole into which lysosomes have degranulated: "lysis from within." However, it has also been contended that degranulation is not required for crystal-induced cell death. To resolve this controversy, we have prepared neutrophil-derived cytoplasts ("neutroplasts") which are devoid of most cellular organelles, including lysosomal granules. Both intact neutrophils and neutroplasts ingested MSU crystals, but inhibition of phagocytosis by cytochalasin B reduced crystal-induced death of neutrophils (release of lactate dehydrogenase) from 42% to 16% without altering lysis of neutroplasts (27% with MSU alone and 26% with MSU and cytochalasin B). Moreover, addition of serum, which prevents direct interaction of crystals with the outer plasma membrane, reduced lysis of neutrophils, reducing cell death from 42% to 25%. After 60 min incubation, serum was totally ineffective in reducing neutrophil death but continued to reduce lysis of neutroplasts from 61% to 13%. Thus, the MSU lysed neutroplasts under conditions in which it ruptured membranes of nonphagocytic structures (erythrocytes, liposomes), i.e., in the absence of serum: "lysis from without." These data suggested that death of neutrophils after internalization of MSU requires a component that is lacking in neutroplasts. Granules (lysosomes) are the best candidates for this component, supporting the general validity of the "lysis from within" hypothesis.

Neutrophils which ingest particles (serum-treated zymosan, monosodium urate crystals) or are exposed to calcium ionophore A23187 generate leukotriene B4 (LTB4). Earlier work has shown that cells exposed to colchicine before exposure to monosodium urate crystals produce less LTB4; the formation of 5-HETE is unaffected. To determine whether inhibition by colchicine of LTB4 generation was stimulus-specific and was mediated by microtubule integrity, the effects of colchicine (10 microM, 60 min) on the release of lipoxygenase products from neutrophils exposed to ionophore A23187 (10 microM, 5 min) were examined. In the presence of exogenous arachidonic acid (100 microM, 15 min), colchicine decreased LTB4 to 48% +/- 11.7 of control and 5-HETE to 60.5% +/- 5.7 of control (mean +/- SEM); 15-HETE was also decreased to 61% +/- 10.3 of control. In the absence of exogenous arachidonate, LTB4 was decreased to 22.2% +/- 11.7 of control and 5-HETE to 13% +/- 4.8 of control. Lumicolchicine did not significantly affect formation of 5-HETE or LTB4. However, vinblastine sulfate (20 microM, 60 min), another microtubule-disruptive agent, decreased the formation of both 5-lipoxygenase products. The effects of colchicine and vinblastine were not due to impairment of cell viability because the release of cytoplasmic lactic dehydrogenase was unaffected. Ultrastructural analysis of centriolar microtubules showed that decrements in microtubule numbers of colchicine- and vinblastine-treated cells paralleled decrements in 5-lipoxygenase products. These pharmacologic manipulations suggested that functional microtubules might be required for optimal lipoxygenase activity. Consequently, we prepared neutrophil-derived cytoplasts, devoid of an intact microtubule system. No significant decreases in the 5- or 15-lipoxygenase products were found when cytoplasts were exposed to colchicine in the presence of exogenous arachidonate and A23187. The data show that colchicine inhibits the formation of lipoxygenase products from neutrophils stimulated with A23187, most likely via its effect on microtubules, the integrity of which appears necessary for full expression of 5- and 15-lipoxygenases.