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Biomedical subjects

A Maseri

Publications and source records attributed to A Maseri.

At least 37 records · Page 2Linked to original sources
PubMed2000

Myocardial cell death in human diabetes.

The renin-angiotensin system is upregulated with diabetes, and this may contribute to the development of a dilated myopathy. Angiotensin II (Ang II) locally may lead to oxidative damage, activating cardiac cell death. Moreover, diabetes and hypertension could synergistically impair myocardial structure and function. Therefore, apoptosis and necrosis were measured in ventricular myocardial biopsies obtained from diabetic and diabetic-hypertensive patients. Accumulation of a marker of oxidative stress, nitrotyrosine, and Ang II labeling were evaluated quantitatively. The diabetic heart showed cardiac hypertrophy, cavitary dilation, and depressed ventricular performance. These alterations were more severe with diabetes and hypertension. Diabetes was characterized by an 85-fold, 61-fold, and 26-fold increase in apoptosis of myocytes, endothelial cells, and fibroblasts, respectively. Apoptosis in cardiac cells did not increase additionally with diabetes and hypertension. Diabetes increased necrosis by 4-fold in myocytes, 9-fold in endothelial cells, and 6-fold in fibroblasts. However, diabetes and hypertension increased necrosis by 7-fold in myocytes and 18-fold in endothelial cells. Similarly, Ang II labeling in myocytes and endothelial cells increased more with diabetes and hypertension than with diabetes alone. Nitrotyrosine localization in cardiac cells followed a comparable pattern. In spite of the difference in the number of nitrotyrosine-positive cells with diabetes and with diabetes and hypertension, apoptosis and necrosis of myocytes, endothelial cells, and fibroblasts were detected only in cells containing this modified amino acid. In conclusion, local increases in Ang II with diabetes and with diabetes and hypertension may enhance oxidative damage, activating cardiac cell apoptosis and necrosis.

Angiotensin II↗
PubMed2000

Evidence for antigen-driven T-cell response in unstable angina.

BACKGROUND: Activation of T cells and macrophages has been associated with unstable angina (UA), but whether this reflects specific immune responses remains unclear. METHODS AND RESULTS: We analyzed the repertoire and the length of complementarity-determining region 3 of the T-cell receptor (TCR) beta-chain variable (BV) gene segments of activated lymphocytes in 23 patients with UA, 13 patients with chronic stable angina (CSA), and 6 normal control subjects. We also tested the proliferation of systemic T cells in response to autologous coronary plaque proteins, oxidized LDL, and Chlamydia pneumoniae as candidate antigens, in vitro. The activated T cell-TCRBV repertoire was perturbed in 13 (57%) of 23 UA patients versus 3 (23%) of 13 CSA patients (P=0.016) and was restricted to 6 (28%) of 21 expanded TCRBV families; all were significantly higher in UA than in CSA patients. At least one monotypic or oligotypic activated TCRBV population was found in 15 (65%) of 23 UA patients and in 3 (23%) of 13 CSA patients (P<0.001). Finally, T cells from UA patients, but not from CSA patients or normal control subjects, proliferated in response to autologous proteins from coronary culprit lesions and/or to oxidized LDL. CONCLUSIONS: Our findings suggest that the T-cell response observed in UA patients is antigen-driven and directed to antigens contained in the culprit coronary atherosclerotic plaques.

Angina, Unstable↗
PubMed2000

Major racial differences in coronary constrictor response between japanese and caucasians with recent myocardial infarction.

BACKGROUND: Enhanced coronary vasomotion may contribute to acute coronary occlusion during the acute phase of myocardial infarction (AMI). Japanese have a higher incidence of variant angina than Caucasian patients, but racial differences in vasomotor reactivity early after AMI are controversial. METHODS AND RESULTS: The same team studied 15 Japanese and 19 Caucasian patients within 14 days of AMI by acetylcholine injection into non-infarct-related (NIRA) and infarct-related (IRA) coronary arteries followed by nitroglycerin. Incidence of vasodilation, vasoconstriction, spasm, and basal tone were assessed in proximal, middle, and distal segments after each drug bolus by quantitative angiography. Japanese patients had much lower cholesterol levels than Caucasians (183+/-59 versus 247+/-53 mg/dL, P<0.006) but showed a lower incidence of vasodilation (2% versus 9% of coronary segments) and a greater incidence of spasm after acetylcholine (47% versus 15% of arteries, P<0.00001). Incidence of spasm was higher in IRAs than in NIRAs in both populations (67% versus 39% and 23% versus 11%, respectively). Multivessel spasm was more common (64% versus 17%, P<0.02) and vasoconstriction of nonspastic segments was greater in Japanese patients (-23.4+/-14.9% versus -20.1+/-15.7%, P<0.02) in the presence of similar average basal coronary tone with respect to post-nitroglycerin dilation and of nonsignificant differences of coronary atherosclerotic score. CONCLUSIONS: Soon after AMI, Japanese patients exhibited a 3-fold-greater incidence of spasm and greater vasoconstriction of nonspastic segments after acetylcholine than Caucasians. The causes of such differences warrant further investigation because they may have relevant pathophysiological and therapeutic implications.

Acetylcholine↗
PubMed2000

Large, sustained cardiac lipid peroxidation and reduced antioxidant capacity in the coronary circulation after brief episodes of myocardial ischemia.

OBJECTIVES: We sought to investigate whether a brief episode of myocardial ischemia produces a detectable cardiac oxidative stress in patients undergoing elective coronary angioplasty (PTCA). BACKGROUND: Although cardiac oxidative stress has been clearly demonstrated in experimental models of ischemia-reperfusion, its presence in patients after transient myocardial ischemia is still unclear. METHODS: In order to evaluate oxidative stress in ischemic cardiac regions, plasma conjugated dienes (CD), lipid hydroperoxides (ROOHs) and total antioxidant capacity (TRAP), independent indexes of oxidative stress, were measured in the aorta and great cardiac vein (GCV) before (t0), 1, (t1), 5 (t5) and 15 min (t15) after first balloon inflation in 15 patients undergoing PTCA on left anterior descending coronary artery (Group 1); six patients with right coronary artery stenosis (Group 2), which is not drained by the GCV, were studied as controls. RESULTS: In Group 1 at baseline, CD and ROOHs levels were higher in GCV than in aorta (p < 0.01 for both), and TRAP levels were lower (p < 0.01). Aortic levels of CD, ROOHs and TRAP did not change at any time after to; venous levels of CD and ROOHs levels markedly increased at t1, at t5 and remained elevated at t15 (p < 0.01 for all comparisons vs. to); venous levels of TRAP decreased at t1 and t5 (p < 0.01 vs. t0) and returned to normal at t15. In Group 2, CD, ROOHs and TRAP levels were similar in the aorta and GCV and did not change throughout the study. CONCLUSIONS: Short episodes of myocardial ischemia during PTCA induce a sustained oxidative stress, which is detectable in the venous effluent of reperfused myocardium.

Angioplasty, Balloon, Coronary↗
PubMed2000

Inflammation and acute coronary syndromes.

The presence of inflammatory infiltrates in unstable coronary plaques suggests that inflammatory processes may contribute to the pathogenesis of these syndromes. In patients with unstable angina, coronary atherosclerotic plaques are characterized by the presence of macrophages, and to a lesser extent, T-lymphocytes, at the immediate site of either plaque rupture or superficial erosion; moreover, the rupture-related inflammatory cells are activated, indicating ongoing inflammation at the site of plaque disruption. These observations are confirmed by clinical studies demonstrating activated circulating neutrophils, lymphocytes and monocytes, and increased concentrations of pro-inflammatory cytokines, such as interleukin (IL) 1 and 6, and of acute phase reactants in patients with unstable angina and myocardial infarction. In particular elevated levels of C-reactive protein are associated with an increased risk of in-hospital and 1 to 2 years new coronary events in patients with unstable angina, but are also associated with an increased long-term risk of death and myocardial infarction in apparently normal subjects. Thus, accumulating evidence suggests that inflammation may cause local endothelial activation and, possibly, plaque fissure, leading to unstable angina and infarction. Although no information is yet available on the causes of inflammation and on its localization, these novel lines of research may open the way to a different approach to the patient with acute coronary syndromes.

Acute Disease↗
PubMed2000

Coronary Artery Spasm.

Attacks of variant angina usually respond promptly to sublingual administration of short-acting nitrates (nitroglycerin, 0.3 to 0.4 mg, or isosorbide dinitrate, 5 to 10 mg), which may be repeated after 3 to 5 minutes if pain persists. In the rare cases resistant to sublingual nitrates, sublingual nifedipine (5 to 10 mg) or, when readily available, intravenous nitrates (nitroglycerin or isosorbide dinitrate, 2 to 10 mg) or calcium antagonists (verapamil, 5 to 10 mg, or diltiazem, 0.15 mg/kg) can be given. All attempts to prevent ischemic attacks by means of specific receptor blockade in patients with vasospastic angina have been unsatisfactory. This may be either because the doses of the blockers used were insufficient or, more likely, because the blockade of a single receptor-agonist interaction leaves receptors for other vasoconstrictor stimuli unopposed and therefore capable of eliciting spasm. Thus, for instance, alpha-adrenergic, serotoninergic, and thromboxane A(2) antagonists all failed to reduce significantly the number of anginal attacks, although they appeared to be effective in some patients. Until the actual causes of the coronary smooth muscle hyperreactivity to constrictor stimuli are known, treatment of vasospastic angina is based on the use of nonspecific vasodilators. Indeed, the mainstay of pharmacologic treatment of coronary artery spasm is calcium channel blocking agents together with nitrates to cover the periods in which spasm is most likely to occur. These powerful vasodilating agents, at their usual doses, are able immediately and completely to control the recurrences of ischemic attacks in as many as 80% of patients. Moreover, some studies have shown that use of calcium antagonists significantly improves clinical outcome in patients with variant angina.

Journal Article↗
PubMed2000

Myocardial ischemia-reperfusion damage after pacing-induced tachycardia in patients with cardiac syndrome X.

The presence of myocardial ischemia in syndrome X (chest pain, "ischemia-like" electrocardiogram changes, and normal coronary angiograms) is uncertain possibly because, when focally distributed, it may not cause contractile dysfunction or lactate production. We measured lipid hydroperoxides (ROOHs) and conjugated dienes (CDs), two sensitive, independent markers of ischemia-reperfusion oxidative stress, in paired aortic and great cardiac vein blood samples before and after pacing-induced tachycardia in nine patients with syndrome X. Diagnostic ischemic S-T segment changes during pacing were followed by a consistent increase in ROOH and CD levels in the great cardiac vein (from 4.83 +/- 1.18 micromol/l at baseline to 7.88 +/- 1.12 micromol/l and from 0.038 +/- 0.002 to 0.051 +/- 0.003 arbitrary units, respectively, P < 0.01). In controls, ROOH and CD levels did not change after pacing. The large postpacing cardiac release of lipid peroxidation products, consistently observed in all patients and similar to that previously observed after ischemia caused by percutaneous transluminal coronary angioplasty, is consistent with an ischemic origin of syndrome X.

Adult↗
PubMed2000

Oxidative stress in ischemia-reperfusion injury: assessment by three independent biochemical markers.

BACKGROUND: Oxidative stress plays a key role in ischemia-reperfusion injury, causing peroxidation of tissue lipids and proteins. However, it is debated whether brief ischemic episodes are sufficient to cause detectable oxidative stress in humans, since biochemical markers used so far in the setting of percutaneous transluminal coronary angioplasty (PTCA) gave conflicting results. METHODS: We determined lipid hydroperoxides (ROOHs), conjugated dienes (CD) and total radical-trapping antioxidant capacity (TRAP), three different independent markers of oxidative stress, in aortic and great cardiac vein blood of 5 patients undergoing PTCA before a single balloon inflation lasting 115 +/- 38 s (t0), and 1 min (t1), 5 min (t5), 15 min (t15) after balloon deflation (Group 1). ROOHs and CD were also determined in aortic and great cardiac vein blood of 5 patients with mitral valve disease (Group 2). RESULTS: In Group 1, great cardiac vein levels of ROOHs and CD at t1 increased by 219% and 79%, respectively, compared to t0 (p < 0.01); this sharp and consistent increase persisted up to t15 (+189% and +63%, respectively, compared to t0; p < 0.01). Great cardiac vein levels of TRAP were significantly lower than aortic levels at t0, and exhibited a further decrease at tl. No significant differences in aortic and great cardiac vein levels of ROOHs and CD at t0 were observed between Group 1 and Group 2. CONCLUSIONS: The three methods we used showed a remarkable sensitivity for the detection of post-ischemic reperfusion injury in cardiac venous blood and may be useful for detecting small foci of ischemia-reperfusion injury in microvascular angina.

Angioplasty, Balloon, Coronary↗
PubMed1999

Perturbation of the T-cell repertoire in patients with unstable angina.

BACKGROUND: Monocytes are constitutively activated in unstable angina (UA), resulting in the production of IL-6 and the upregulation of acute phase proteins. Underlying mechanisms are not understood. To explore whether the production of the potent monocyte activator IFN-gamma is altered in UA, we compared cytokine production by T lymphocytes in patients with UA (Braunwald's class IIIB) and with stable angina (SA). METHODS AND RESULTS: Peripheral blood lymphocytes were collected at the time of hospitalization and after 2 and 12 weeks. Cytokine-producing CD4(+) and CD8(+) T cells were quantified by 3-color flow cytometry after stimulation with phorbol myristate acetate and ionomycin. UA was associated with an increased number of CD4(+) and CD8(+) T cells producing IFN-gamma, whereas patients with SA had higher frequencies of IL-2(+) and IL-4(+) CD4(+) T cells. Expansion of the IFN-gamma( +) T-cell population in UA persisted for at least 3 months. Increased production of IFN-gamma in UA could be attributed to the expansion of an unusual subset of T cells, CD4(+)CD28(null) T cells. CONCLUSIONS: Patients with UA are characterized by a perturbation of the functional T-cell repertoire with a bias toward IFN-gamma production, suggesting that monocyte activation and acute phase responses are consequences of T-cell activation. IFN-gamma is produced by CD4(+)CD28(null) T cells, which are expanded in UA and distinctly low in SA and controls. The emergence of CD4(+)CD28(null) T cells may result from persistent antigenic stimulation.

Adult↗