S. Hinan Ahmed

Specific Temporal Profile of Matrix Metalloproteinase Release Occurs in Patients After Myocardial Infarction Relation to Left Ventricular Remodeling

Background— Changes in matrix metalloproteinase (MMP) and tissue inhibitors of MMPs (TIMPs) contribute to left ventricular (LV) remodeling after myocardial infarction (MI). We tested the hypothesis that a specific plasma MMP/TIMP profile would emerge after MI and be associated with the degree of LV dilation. Methods and Results— LV end-diastolic volume and MMP/TIMP plasma profiles were determined in 53 age-matched control subjects and 32 post-MI patients from day 1 through 180 after MI. LV end-diastolic volume increased by >38% at day 90 after MI (P<0.05). MMP-9 increased by >150% from control at day 1 after MI (P<0.05) and remained elevated. MMP-8 rose to >120% at day 3 after MI (P<0.05) and fell to control values by day 5. TIMP-1 increased by >60% from control at day 1 after MI (P<0.05), whereas TIMP-2 increased only at later time points. Cardiac-specific TIMP-4 fell by 40% at day 5 after MI and remained reduced. A persistent or elevated MMP-9 at day 5 was accompanied by a 3-fold end-diastolic volume increase at day 28 (P<0.05). Conclusions— A specific temporal pattern of MMP/TIMPs occurred in post-MI patients that included an early and robust rise in MMP-9 and MMP-8 and a uniform fall in TIMP-4. These findings suggest that a specific MMP/TIMP plasma profile occurs after MI and holds both prognostic and diagnostic significance.

iNOS and nitrotyrosine expression after spinal cord injury

Secondary tissue damage after spinal cord injury (SCI) may be due to inflammatory mediators. After SCI, the nuclear factor-kappaB (NF-kappaB) transcription factor can activate many pro-inflammatory genes, one of which is inducible nitric oxide synthase (iNOS). iNOS catalyzes the synthesis of nitric oxide (NO), a key inflammatory mediator, which in turn reacts with superoxide to generate peroxynitrite. Peroxynitrite is a strong oxidant that can damage cellular enzymes, membranes, and subcellular organelles through the nitration of tyrosine residues on proteins. The presence of nitrotyrosine (NT) is an indirect chemical indicator of toxic NO and peroxynitrite-induced cellular damage. Using a New York University (NYU) impactor to induce SCI in adult rats, we examined the temporal and cellular expression of iNOS and NT. We observed a progressive increase in iNOS expression in the injured cord starting at day 1 with maximal expression occurring at day 7, as determined by Western blot analysis. iNOS expression corresponded temporally to an increase in iNOS enzyme activity after SCI. In parallel with the progressive increase in iNOS activity, NT expression also increased with time after SCI. The iNOS and NT immunoreactivity was localized in neurons, astrocytes, endothelial cells and ependymal cells at the epicenter and adjacent to the region of spinal cord impact and injury. Results from the present study suggest that increased iNOS and peroxynitrite anion, as reflected by the progressive accumulation of NT in the injured impacted spinal cord, may contribute to the secondary injury process after SCI.

Oxygen-Glucose Deprivation Induces Inducible Nitric Oxide Synthase and Nitrotyrosine Expression in Cerebral Endothelial Cells

BACKGROUND AND PURPOSE The cerebral endothelial cells (ECs) are a primary target of hypoxic or ischemic brain insults. EC damage may contribute to postischemic secondary injury. Massive production of NO after inducible NO synthase (iNOS) expression has been implicated in cell death. This study aimed to characterize bovine cerebral EC death in relation to iNOS expression after oxygen-glucose deprivation (OGD) in vitro. METHODS OGD in bovine cerebral ECs in culture was induced by deleting glucose in the medium and by incubating the cells in a temperature-controlled anaerobic chamber. The extent of cell death was assessed by trypan blue exclusion, MTT assay, and LDH release. ELISA, gel electrophoresis, and staining by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling were used to examine DNA fragmentation. The expression of iNOS mRNA and protein was detected by reverse transcription-polymerase chain reaction and Western blotting, respectively. Nitrotyrosine expression was confirmed with Western blot analysis and immunostaining. RESULTS Bovine cerebral EC death was dependent on the duration of OGD and showed selected biochemical, morphological, and pharmacological features suggestive of apoptosis. OGD also induced the expression of iNOS mRNA and protein in bovine cerebral ECs. Increased expression of nitrotyrosine, the product formed by peroxynitrite reaction with proteins, was also detected after OGD. The involvement of iNOS in EC death was suggested by partial reduction of cell death by NO synthase inhibitors, including L-N(G)-(1-iminoethyl)ornithine and nitro-L-arginine, and an NO scavenger, the Fe(2+)-N-methyl-D-glucamine dithiocarbamate complex. CONCLUSIONS OGD-induced bovine cerebral EC death involves an apoptotic process. Induction of iNOS with subsequent peroxynitrite formation may contribute to bovine cerebral EC death caused by OGD.

Impact of Parallel Micro-Engineered Stent Grooves on Endothelial Cell Migration, Proliferation, and Function An In Vivo Correlation Study of the Healing Response in the Coronary Swine Model

Background— Stent luminal surface characteristics influence surface endothelialization. We hypothesize that luminal stent microgrooves created in the direction of coronary flow accelerate endothelial cell migration, resulting in lower levels of neointimal formation. Methods and Results— Surface coverage efficiency was evaluated in vitro by allowing human aortic endothelial cells (HAEC) to migrate onto microgrooved (G) or smooth (NG) surfaces. HAEC functionality was assessed by proliferation rate, apoptosis rate, nitric oxide production, and inflammatory markers TNF-&agr; and VCAM-1 expression. Early endothelialization and restenosis studies were performed using the porcine coronary injury model. Stainless steel stents of identical design with (GS) and without (NGS) luminal microgrooves were used. The commercially available Multi-Link Vision (MLVS) stent of identical design was used as a control. The degree of GS and NGS surface endothelialization was compared at 3 days. Biocompatibility and tissue response outcomes were evaluated at 28 days. The in vitro study demonstrated that at 7 days the presence of surface microgrooves increased HAEC migration distance >2-fold. Cell proliferation rate and nitric oxide production were increased and apoptosis rate was decreased. There was no difference in inflammatory marker expression. At 3 days, coronary artery stent endothelialization was significantly increased in GS compared with NGS (81.3% versus 67.5%, P=0.0002). At 28 days, GS exhibited lower neointimal thickness compared with either NGS (21.1%, P=0.011) or MLVS (40.8%, P=0.014). Conclusion— Parallel microgrooves on coronary stent luminal surfaces promote endothelial cell migration and positively influence endothelial cell function, resulting in decreased neointimal formation in the porcine coronary injury model.

Comparison of safety and efficacy of bivalirudin versus unfractionated heparin in percutaneous peripheral intervention: a single-center experience.

OBJECTIVES The aim of this study was to determine the efficacy and safety of bivalirudin versus low-dose unfractionated heparin (UFH) in percutaneous peripheral intervention (PPI). BACKGROUND Anticoagulation strategies used in PPI are based primarily on studies of percutaneous coronary intervention where higher doses of heparin are used usually in combination with a glycoprotein IIb/IIIa inhibitor. There are no studies comparing bivalirudin alone versus low-dose heparin in PPI. METHODS Consecutive patients who underwent PPI at our institution were treated with either bivalirudin or low-dose UFH. Patients were assessed prospectively during index hospital stay for procedural success and bleeding complications. Of 236 patients, 111 were dosed with UFH at 50 U/kg (goal activated clotting time of 180 to 240 s), and 125 were dosed with bivalirudin at 0.75-mg/kg/h bolus followed by a 1.75-mg/kg infusion. Procedural success was defined as <20% post-procedure residual stenosis with no flow-limiting dissections or intravascular thrombus formation and major bleeding as intracranial or retroperitoneal hemorrhage or a fall in hemoglobin >or=5 g/dl. Anticoagulation cost analysis was conducted. RESULTS Procedural success and major bleeding rates were similar with bivalirudin versus heparin (98% vs. 99% and 2.4% vs. 0.9%, respectively). There were no differences in minor bleeding, time to ambulation, and length of hospital stay. The hospital cost for bivalirudin was

Impact of 24‐hr in‐hospital interventional cardiology team on timeliness of reperfusion for ST‐segment elevation myocardial infarction

547 and <

Titin Phosphorylation Myocardial Passive Stiffness Regulated by the Intracellular Giant

1.22 for heparin (10,000 U). Two activated clotting time levels cost

Is Primary Hyperaldosteronism a Risk Factor for Aortic Dissection

4.00. CONCLUSIONS Low-dose UFH is as effective and safe as bivalirudin when used as an anticoagulation strategy in patients undergoing PPI, and low-dose UFH is less costly than bivalirudin. Larger randomized studies are required to further evaluate these findings.

Concomitant anomalous right coronary artery and iatrogenic left circumflex artery entrapment, treated successfully with percutaneous coronary intervention.

Objective: We studied the effect of 24 hr a day, 7 days a week interventional cardiology staff on door‐to‐balloon (D2B) time and mortality in patients undergoing primary percutaneous coronary intervention (PPCI) for ST‐segment elevation myocardial infarction (STEMI). Background: Any delay in PPCI in acute STEMI is associated with higher mortality and, therefore, time to treatment should be as short as possible. Despite the use of several strategies, goal D2B time of <90 min remains elusive. Methods: The study examined 790 consecutive STEMI patients treated with PPCI as the reperfusion therapy of choice. Patients were grouped into a pre‐24×7 and post‐24×7 cohort to study the impact of the new protocol on D2B time and major adverse cardiovascular events (MACE) and mortality. Results: Median D2B time decreased from 99 min in the pre‐24×7 group to 55 min in the post‐24×7 group (P = 0.001) and was not influenced by time of day or day of week. Adjusted for patient and clinical characteristics, the pre‐24×7 group had increased in‐hospital cardiovascular mortality (odds ratio 1.94, 95% confidence interval 0.95–3.94; P = 0.048) and MACE (odds ratio 1.66, 95% confidence interval 1.10–2.49; P = 0.009) compared with the post‐24×7 group. Prolonged D2B time was also associated with higher 1‐year overall mortality in the pre‐24×7 group compared with the post‐24×7 group (12.8% vs. 8.1%; hazard ratio 1.17, 95% confidence interval 1.04–2.66; P = 0.044). Conclusions: Round‐the‐clock, in‐hospital interventional cardiology team consistently and significantly reduces D2B time, in‐hospital cardiovascular mortality, MACE, and 1‐year mortality in patients with STEMI.

Tibio-pedal arterial minimally invasive retrograde revascularization: Pushing the limits of endovascular therapy in critical limb ischemia

See related articles, pages 631–638 Diastolic performance is regulated by net myocardial stiffness, which is determined by the mechanosensitive protein network comprised of extracellular proteins such as collagen, intracellular sarcomeric proteins, and cell surface integrins. Mechanical force and its regulation are sensed and propagated by each of these components in a concerted fashion.1 During diastole, titin filaments serve as tensiometers and passive force generators. This is accomplished by modulation via directional signaling of multiple linkages between different regions within the titin molecule and the cellular contractile apparatus. An intricate network of signaling molecules coordinates the extracellular and intracellular components in the contraction of a sarcomere. In this issue of Circulation Research , Hidalgo et al present an elegant set of experiments that reveal a novel mechanism whereby altering the phosphorylation state of titin modulates myocardial passive stiffness.2 Specifically, they demonstrated that titin, in addition to being a protein kinase (PK)A and PKG substrate, is also a PKCα substrate. They further identified the PEVK region of titin as the prominent site of PKCα phosphorylation, and showed that phosphorylation at this site increased passive tension. Titin is an approximately 3000-kDa molecular-mass sarcomeric protein that spans the Z disk to the M line of the sarcomere.3 Originally thought to only provide structural scaffolding to link the many regulatory, contractile, and structural proteins within the sarcomere, titin is now recognized to be a major regulator of intracellular myocyte stiffness. Titin determines the passive tension of the intracellular component of cardiomyocytes, which, together with collagen, determines the total myocardial passive stiffness. Although the immunoglobulin-like domain and fibronectin type III repeats make up 90% of the titin molecule, titin also includes a unique I-band region that is flexible and specifically serves as a molecular spring to determine passive stiffness. …