Biomedical subjects

Roger Laham

Publications and source records attributed to Roger Laham.

5 recordsLinked to original sources

PubMed2006

High-dose atorvastatin improves hypercholesterolemic coronary endothelial dysfunction without improving the angiogenic response.

BACKGROUND: Although 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) can restore endothelial function in coronary disease, in vitro and murine studies have shown their effects on myocardial angiogenesis to be biphasic and dose dependent. We investigated the functional and molecular effects of high-dose atorvastatin on the endogenous angiogenic response to chronic myocardial ischemia in hypercholesterolemic swine. METHODS AND RESULTS: Yucatan pigs were fed either a normal (NORM group; n=7) or high-cholesterol diet, with (CHOL-ATR group; n=7) or without (CHOL group; n=6) atorvastatin (3 mg/kg per day) for 13 weeks. Chronic ischemia was induced by ameroid constrictor placement around the circumflex artery. Seven weeks later, microvessel relaxation responses, myocardial perfusion, and myocardial protein expression were assessed. The CHOL group demonstrated impaired microvessel relaxation to adenosine diphosphate (29+/-3% versus 61+/-6%, CHOL versus NORM; P<0.05), which was normalized in the CHOL-ATR group (67+/-2%; P=NS versus NORM). Collateral-dependent myocardial perfusion, adjusted for baseline, was significantly reduced in the CHOL group (-0.27+/-0.07 mL/min per gram versus NORM; P<0.001) as well as the CHOL-ATR group (-0.35+/-0.07 mL/min per gram versus NORM; P<0.001). Atorvastatin treatment was associated with increased phosphorylation of Akt (5.7-fold increase versus NORM; P=0.001), decreased vascular endothelial growth factor expression (-68+/-8%; P<0.001 versus NORM), and increased expression of the antiangiogenic protein endostatin (210+/-48%; P=0.004 versus NORM). CONCLUSIONS: Atorvastatin improves hypercholesterolemia-induced endothelial dysfunction without appreciable changes in collateral-dependent perfusion. Increased myocardial expression of endostatin, decreased expression of vascular endothelial growth factor, and chronic Akt activation associated with atorvastatin treatment may account for the diminished angiogenic response.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗

PubMed2006

Angiogenesis for the treatment of inoperable coronary disease: the future.

Improved treatment options and better management of cardiovascular risk factors have resulted in improved outcomes for patients suffering from severe coronary artery disease. However, coronary artery disease may be of such a diffuse and severe manner that repeated attempts at catheter-based interventions and coronary artery bypass grafting may be unsuccessful at restoring normal myocardial blood flow. It is the goal of therapeutic angiogenesis to restore perfusion to chronically ischemic myocardium using protein growth factors, gene therapy, or, more recently, cell-based therapy, without intervening on the epicardial coronary arteries. However, angiogenesis has not yet provided significant clinical benefit and is still reserved as an experimental treatment for patients who have failed conventional therapies. Once potential endogenous inhibitors of vascular development can be modified, angiogenesis may become more useful for therapeutic purposes. It is hoped that angiogenesis for therapeutic purposes will one day effectively re-create the potent natural processes of vascularization that every human being undergoes during growth and development and become a major modality for the treatment of coronary artery disease.

Angiogenic Proteins↗

PubMed2006

Treatment of stent-jailed side branch stenoses with rotational atherectomy.

UNLABELLED: While debulking with rotational atherectomy (RA) prior to balloon angioplasty (BA) improves acute results by reducing elastic recoil, treatment of an ostial side branch lesion that is covered (jailed) by a stent represents a particular challenge. We report our experience with RA in conjunction with BA for the treatment of ostial stenosis in jailed side branches. METHODS AND RESULTS: Thirty-two lesions in side branches jailed by a stent were treated with RA and BA 39 times in 30 patients. The mean age was 65.5 +/- 11.5 years; 26.3% were women; 18.4% had diabetes mellitus; and 18.4% had a history of prior bypass surgery. Of the treated side branches, 53.9% were diagonals, 71.8% were jailed by a slotted-tube stent, and 86.5% were previously dilated prior to RA. The burr sizes used to treat the jailed side branch origin ranged from 1.25 to 2.25 mm, with a mean burr size of 1.62 +/- 0.31 mm. An average of 1.53 +/- 0.72 burrs were used per lesion. Quantitative coronary angiography was performed prior to, and after, intervention. The mean diameter stenosis of the side branch prior to revascularization was 77.8% +/- 12.6%; this was reduced to a mean stenosis of 23.0% +/- 17.9% following treatment with RA and BA. Angiographic success (residual stenosis < 50% and TIMI 3 flow) in the side branch occurred in 36 of 39 lesions (92.3%). Procedural success (angiographic success in both the side branch and the parent vessel in the absence of death, emergent CABG, urgent TVR, and myocardial infarction (CK-MB > or = 3 times normal) during the index hospitalization) was achieved in 33 of 38 cases (86.8%). One patient suffered a periprocedural myocardial infarction; another patient presented with stent thrombosis in the parent vessel requiring emergency revascularization 36 hours after the index procedure. Clinically-driven revascularization of either the side branch or the side branch or parent was performed in 44.8% and 46.4% of patients, respectively. The estimated freedom from any target lesion revascularization was 47.7% at 300 days. One patient died of unknown causes 253 days following the index procedure. CONCLUSIONS: RA in conjunction with BA can effectively treat stent-jailed ostial side branch stenosis with excellent acute angiographic and procedural results. However, the long-term efficacy is limited by a high rate of repeat revascularization.

Aged↗

PubMed2005

Involvement of COX-2 in VEGF-induced angiogenesis via P38 and JNK pathways in vascular endothelial cells.

OBJECTIVE: Cyclooxygenase-2 (COX-2) is induced by hypoxic stimuli and is also involved in the process of angiogenesis. We previously demonstrated that vascular endothelial growth factor (VEGF) is one of the principal factors produced by hypoxic myocytes and is responsible for the induction of COX-2 expression in endothelial cells. Yet the signaling pathways by which VEGF modulates COX-2 gene expression are still less well defined. We therefore examined the regulation of VEGF-induced COX-2 expression by the mitogen-activated protein kinase (MAPK) family in endothelial cells. METHODS AND RESULTS: Human umbilical vascular endothelial cells (HUVECs) were incubated with U0126 (ERK1/2 inhibitor, 10 microM), SB203580 (p38 inhibitor, 20 microM), and SP600125 (JNK inhibitor, 20 microM), as well as the COX-2 selective inhibitor, NS398, for 1 h before treating with VEGF (20 ng/ml). COX-2 expression induced by VEGF at both mRNA and protein levels was significantly inhibited by selective p38 and JNK inhibitors but not by the ERK1/2 inhibitor. The phosphorylation of p38 and JNK kinases was observed as early as 5 min in HUVECs after VEGF stimulation. Furthermore, the biological significance of the COX-2 gene in endothelial cells was examined by over-expressing or knocking down COX-2 gene expression. (3)H-Thymidine incorporation and Matrigel techniques were used to determine cell proliferation and vascular structure formation. VEGF-induced cell proliferation was significantly reduced when HUVECs were either pre-treated with NS398 (21.52+/-3.6%) or transfected with COX-2 siRNA (34.12+/-5.81%). In contrast, in HUVECs with over-expression of COX-2, VEGF-induced cell proliferation was increased 42.56+/-7.69%. Moreover, the formation of vascular structure assayed by Matrigel demonstrated that VEGF-induced vascular structure formation was accelerated in COX-2 over-expressing cells but attenuated in COX-2 siRNA-transfected cells. CONCLUSION: COX-2 plays an important role in VEGF-induced angiogenesis via p38 and JNK kinase activation pathways. These findings suggest that the cardioprotective role of COX-2 may be, at least in part, through its angiogenic activity.

Anthracenes↗

PubMed2005

A blinded, randomized, placebo-controlled trial of percutaneous laser myocardial revascularization to improve angina symptoms in patients with severe coronary disease.

OBJECTIVES: This study was a randomized, patient- and evaluator-blinded, placebo-controlled trial in patients treated using percutaneous myocardial laser revascularization. BACKGROUND: Previous studies using similar therapies have been confounded by placebo bias. METHODS: A total of 298 patients with severe angina were randomly assigned to receive low-dose or high-dose myocardial laser channels or no laser channels, blinded as a sham procedure. The primary end point was the change in exercise duration from baseline examination to six months. RESULTS: The incidence of 30-day death, stroke, myocardial infarction, coronary revascularization, or left ventricular perforation occurred in two patients in the placebo, eight patients in the low-dose, and four patients in the high-dose groups (p = 0.12); 30-day myocardial infarction incidence was higher in patients receiving either low-dose or high-dose laser (nine patients) compared with placebo (no patients, p = 0.03). At six months, there were no differences in the change in exercise duration between those receiving a sham (28.0 s, n = 100), low-dose laser (33.2 s, n = 98), or high-dose laser (28.0 s, n = 98, p = 0.94) procedure. There were also no differences in the proportion of patients improving to better than Canadian Cardiovascular Society class III angina symptoms at six months. The follow-up visual summed stress single-photon-emission computed tomography scores were not significantly different from baseline in any group and were no different between groups. The modest improvement in angina symptoms assessed by the Seattle Angina Questionnaire also was not statistically different among the arms. CONCLUSIONS: Treatment with percutaneous myocardial laser revascularization provides no benefit beyond that of a similar sham procedure in patients blinded to their treatment status.

Angina Pectoris↗