José Milei

Comparison of Lipid Peroxidation and Myocardial Damage Induced by Adriamycin and 4′-Epiadriamycin in Mice

Adriamycin (ADM) and 4′-epiadriamycin (4′-ADM) were given to mice in a single dose of 15 mg/kg body weight (i.p.). Twenty-five mice were alloted to 3 groups. One group (Group I; n = 8) was given ADM; another group (Group II; n = 9) was similarly treated with 4′-ADM, and a control group (n = 8) received an equivalent volume of 0.9 % NaCl solution. Mice were sacrificed 4 days after the described treatment. A complete autopsy was carried out in each animal. Hydroperoxide-initiated chemihuninescence and malonaldehyde formation were measured in mouse heart homogenates. Control mice showed a maximal photoemission of 52 ± 2 (×10–3) (mean values ± S.E.M.) cpm/mg protein and a formation of 20 ± 4 nmol malonaldehyde/g organ after a 2 hr-incubation. The ADM-treated mice showed a 24 % enhanced hydroperoxide-initiated photoemission and a 370 % increased malonaldehyde formation. The 4′-ADM-treated mice showed a 15 % increased hydroperoxide-stimulated chemiluminescence and an 85 % increased malonaldehyde formation. Vitamin A (5000 IU), vitamin E (85 IU) and vitamins A and E (same doses as before) given as a single dose i.p. 1 day before doxorubicin administration were able to decrease the hydroperoxide-initiated chemihuninescence by 24 %, 26 % and 44 %, respectively. Microscopically, only scarce isolated microvacuolated subendocardial fibers were found in the ADM-treated animals. Our data showing that 4′-ADM lacks a statistically significant effect in increasing heart peroxidation as compared to ADM may explain its lower myocardial toxicity.

Carotid Artery Stenting Protected With an Emboli Containment System

Background and Purpose— Fear of distal embolization and stroke has aroused concern regarding carotid stenting. Devices to protect the cerebral circulation may make carotid stenting safer. Methods— A multidisciplinary study group tested a balloon occlusion-aspiration emboli entrapment device in conjunction with carotid stenting. The device consists of an elastomeric balloon on a steerable wire with a detachable adapter that inflates and deflates the distal temporary occlusion balloon. An aspiration catheter is used to remove trapped emboli after stenting and before occlusion balloon deflation. Results— Seventy-five patients with severe internal carotid artery stenosis were treated with stents deployed with this cerebrovasculature protection system. All 75 patients (100%) had grossly visible particulate material aspirated, and all were treated successfully without major or minor stroke or death at 30 days. Preintervention stenosis was 81±10%, and residual stenosis was 5±7%. Nine patients (12%) had angiographic evidence of thrombus before intervention, but no patient had thrombus or vessel cutoff after the procedure. Four patients (5%) developed transient neurological symptoms during protection balloon occlusion, but symptoms resolved with balloon deflation. The 22 to 667 particles aspirated per patient ranged from 3.6 to 5262 &mgr;m in maximum diameter (mean, 203±256 &mgr;m). These particles included fibrous plaque debris, lipid or cholesterol vacuoles, and calcific plaque fragments. Conclusions— Protected carotid stenting was performed successfully and safely in this study early in the experience with cerebrovascular protection devices. Particulate emboli are frequent with stenting, and cerebral protection will likely be necessary to minimize stroke. Randomized trials comparing protected carotid stenting with endarterectomy are warranted.

Reduction of reperfusion injury with preoperative rapid intravenous infusion of taurine during myocardial revascularization

To assess a possible free-radical scavenging action of taurine during coronary artery bypass grafting, 12 patients were randomly divided into two equal groups. One to 3 hours before surgery, they received a rapid intravenous infusion of either placebo (group 1) or taurine (5 gm) (group 2). During surgery, biopsy samples were taken before ischemia (preischemic samples) and after 10 minutes of reperfusion (reperfusion samples). Lipoperoxidation was determined by hydroperoxide-initiated chemiluminescence of heart homogenates, and myocardial cell damage was assessed by electron microscopy. The values for chemiluminescence in preischemic and reperfusion samples from group 1 were 7500 +/- 1600 and 18,600 +/- 4600 cpm/mg of protein, respectively (p less than 0.03). This difference was not observed in group 2 where the values were 10,050 +/- 2700 and 11,800 +/- 4200 cpm/mg of protein, for preischemic and reperfusion samples, respectively. The number of severely damaged mitochondria (grades 3 and 4) in reperfusion samples from group 1 increased significantly compared to preischemic samples (25 +/- 8% vs 12 +/- 3%, p less than 0.01). Conversely no differences were observed between the number of severely damaged mitochondria in reperfusion and preischemic samples from group 2 (8 +/- 3% vs 8 +/- 2%). The number of damaged and necrotic myocytes increased in group 1 after reperfusion from 22 +/- 9% to 34 +/- 10% (p less than 0.03) and from 10 +/- 7% to 26 +/- 20% (p = NS), respectively. No changes were observed between reperfusion and preischemic samples in group 2. Treatment with taurine seems to reduce lipoperoxidation and decrease cell damage at the time of reperfusion.

Carotid rupture and intraplaque hemorrhage: Immunophenotype and role of cells involved

BACKGROUND A complete immunohistochemical characterization in complicated carotid plaques is still lacking. The cellular components of 165 carotid endarterectomy specimens were analyzed to assess their role in the pathogenesis of plaque rupture and intraplaque hemorrhage without rupture. METHODS AND RESULTS The fibrous caps at the sites of plaque rupture showed CD68+ macrophages, T-lymphocytes, and scarce B-lymphocytes. Ruptured plaques showed mononuclear infiltrates in the caps, shoulders, and bases of the plaques in 85% of the cases. Only 46% of nonruptured plaques showed such infiltrates (P <.0001). Two types of lipid cores were recognized: avascular or mildly vascularized and highly vascularized. The vessels of the latter type reacted with CD31 and CD34. In 57.5% of the cases, the base and the shoulders of the plaques showed neoformed, CD34+ vessels, often surrounded by mononuclear infiltrates. Intraplaque hemorrhage without rupture had highly vascularized lipid cores in all cases. T-lymphocytes and macrophages were in close contact with neoformed vessels. CONCLUSIONS Plaque rupture is characterized by mononuclear cell infiltration of the caps, whereas intraplaque hemorrhage without rupture is characterized by extensive vascularization of the plaque.

Chagas cardiomyopathy: Europe is not spared!

Chagas’ disease was first described in 1909 by the Brazilian physician Carlos Chagas, who named the parasite Trypanosoma cruzi after his mentor, Oswaldo Cruz.1 It causes more deaths in the Americas than any other parasitic disease.1 Due to the parasite distribution throughout Central and South America, it is commonly known as the ‘American trypanosomiasis’. As such, it is considered to be an ‘exotic’ disease in Europe, where it is virtually undiagnosed. However, thanks to free circulation of individuals and employment opportunities Europe is a magnet for millions of immigrants, many of whom are from South America. We will review the compelling arguments by which chagasic cardiomyopathy should be moved upfront in the mindset of European cardiologists, actively looked for, and appropriately recognized. Vectorial transmission of the disease is the most common form in endemic countries. This occurs through haematophagous insects (Triatominae), which become vectors for Trypanosoma cruzi by biting an infected animal or person; when infected triatominae bite, they transmit the parasite by defecating on the hosts skin.2 The insects vector of the disease is present throughout most of South and Central America, their zone of distribution encompassing southern USA.2 In non-endemic countries, the disease is transmitted through blood transfusions, organ donations, and from mother to child at birth. However, besides possible occurrence of new cases of infection, substantial concern exists regarding the progressive development of cardiomyopathy in many individuals who had already become infected in their native country, and then move to Europe. The disease has three phases. The initial infection is characterized by an acute phase, which in most cases goes asymptomatic. Infection is followed by a long ‘indeterminate phase’.2 The indeterminate form of chronic Chagas’ disease is defined as chronically infected patients with positive serology but no alterations of heart, oesophagus, and …

Assessment of myocardial oxidative stress in patients after myocardial revascularization.

A homogeneous group of six patients, who underwent coronary artery bypass surgery, was studied to determine the presence of oxidative stress caused by oxygen-derived free radicals and its relationship with reperfusion cell damage. Biopsies were performed before ischemia and 10 minutes after reperfusion. The samples were assayed for hydroperoxide-initiated chemiluminescence and histochemical succinic dehydrogenase activity; the specimens were also studied by electron microscopy. The preischemic biopsy specimens showed chemiluminescence of 40 +/- 2 (cpm/mg protein) x 10(3), normal succinic dehydrogenase activity (grade 4), and generally preserved ultrastructure (necrotic/normal cells 5/100). However, the reperfusion biopsy specimens showed an increase in chemiluminescence to 91 +/- 19 (cpm/mg protein) x 10(3) (p less than 0.025), a partial loss of enzymatic activity (grade 2.6), and ultrastructural changes characterized by mitochondrial swelling and focal myofibrillar disorganization (necrotic/normal cells: 15/100; p less than 0.001). These observations seem to indicate the presence of oxidative stress during reoxygenation, a situation that may play a major role in the genesis of reperfusion injury. It appears to be the first observation relating free radical-induced oxidative stress to reperfusion injury in humans.

Amelioration of adriamycin-induced cardiotoxicity in rabbits by prenylamine and vitamins A and E.

The cardioprotective potentials of prenylamine (a calcium antagonist) and of a combination of vitamins A and E (a singlet oxygen quencher and a free radical scavenger, respectively) were evaluated in rabbits given chronically large doses of Adriamycin (ADM) (10.8 mg/kg body weight for 9 to 11 weeks). Among ADM-treated rabbits, 8 of 10 showed post-treatment ECG changes; in rabbits treated with ADM and prenylamine, changes were found in a smaller number (5 of 10); and in animals treated with ADM and vitamins A and E, the incidence was only one in six (p less than 0.05). Heart homogenates from ADM-treated rabbits showed an increased hydroperoxide-initiated chemiluminescence (expressed as cpm/mg protein X 10(-3)) of 77 +/- 4 compared to control animals (52 +/- 1) (p less than 0.01). Prenylamine administration did not alter hydroperoxide-initiated chemiluminescence in ADM-treated rabbits, whereas treatment with a combination of vitamins A and E showed a significant decrease in hydroperoxide-initiated chemiluminescence in control (40 +/- 2) and ADM-treated rabbits (42 +/- 1). Microscopically, myocardial fibers had mild to severe hydropic vacuolization of sarcoplasm, which led to progressive myocytolysis. A total of 103 +/- 13 damaged fibers were detected over 700 counted fibers. Myocardial damage was lowered to 47 +/- 16 by administration of prenylamine and to 28 +/- 8 by administration of vitamins A and E. It is suggested that ADM leads to myocardial lipid peroxidation (ameliorated by vitamins A and E) with membrane damage and to an increase in calcium permeability, the latter being counteracted by prenylamine.

Reduction of reperfusion injury with mannitol cardioplegia

Forty consecutive patients undergoing myocardial revascularization were divided into two equal groups: group 1 received standard cardioplegic solution, and group 2 received a solution containing mannitol, 59.8 mmol/L. In 6 patients in each group, myocardial biopsies were done before ischemia and at the time of reperfusion. Samples were assessed by chemiluminescence to determine oxidative stress and by electron microscopic studies. A significant reduction in atrial arrhythmias was observed in the mannitol group. Chemiluminescence in group 1 showed a photoemission of 37.6 +/- 3.5 cpm/mg of protein x 10(-3) for the preischemia samples and 74.8 +/- 16 cpm/mg of protein x 10(-3) for the reperfusion samples (p less than 0.001). In group 2, the values for chemiluminescence were 37.7 +/- 3.4 cpm/mg of protein x 10(-3) and 40 +/- 6.1 cpm/mg of protein x 10(-3), respectively (p = not significant). Electron microscopic studies showed, for group 1, increased grades of damaged mitochondria in the reperfusion biopsy specimens compared with the preischemia biopsy specimens (p less than 0.01). In group 2, differences for damaged mitochondria were not significant. These results support the hypothesis that mannitol reperfusate significantly reduces myocardial damage in patients undergoing open heart procedures. They also suggest that this protective effect may be in part secondary to the antioxidant property of mannitol, although other mechanisms may have accounted for or contributed to the improved outcome after ischemia.

Chromosomal alterations in atherosclerotic plaques

Alterations of chromosomes 7 and 11 have been involved in the progression of atherosclerosis. Twenty-three carotid endarterectomy specimens were studied for the presence of alterations in chromosomes 7 and 11, and fibroblastic growth factor-3 (FGF-3) gene amplification. Besides classic histological stainings, immunophenotyping of cellular and vascular components and fluorescence in situ hybridization (FISH) were performed. At the caps, unstable plaques (n=18) showed inflammatory infiltration of macrophages, smooth muscle cells, and T-lymphocytes. Specifically in these regions, the FISH showed varying percentages of trisomy (15/18) and tetrasomy (8/15) of chromosome 7. In four cases polisomy 7 was noted in some nuclei. Monosomy of chromosome 11 and gene amplification of FGF-3 gene was observed. The FISH of the five stable plaques and normal arterial walls showed no chromosome alterations; furthermore, chromosome 3, which is not involved in atherosclerotic progression, presented a normal ploidy of smooth muscle cells in stable and unstable plaques and normal arterial walls. In conclusion, chromosome 7 and 11 alterations and FGF-3 gene amplification are components of unstable plaques, and might contribute to the evolution of stable plaques into complicated plaques.

Atherosclerotic plaque rupture and intraplaque hemorrhage do not correlate with symptoms in carotid artery stenosis.

OBJECTIVE Previously we failed to demonstrate a correlation between plaque type and symptoms in 165 carotid endarterectomy specimens. The purpose of this study was to analyze the relation between the anatomy of the carotid plaques and the presence of symptoms in 281 carotid endarterectomy specimens. METHODS The patients were 213 men (mean age, 68 years) and 68 women (mean age, 68.7 years), with symptomatic disease (n = 133) or asymptomatic disease (n = 148). Specimens were processed for histologic analysis and immunohistochemistry. RESULTS Plaques were categorized as complicated or noncomplicated, and ruptured or nonruptured. Risk factors could not be correlated with any pathologic or immunohistochemical findings or between plaque type and clinical symptoms. CONCLUSIONS Almost 70% of plaque specimens demonstrated thrombus, intraplaque hemorrhage, or both. Thrombosis was observed in one fourth of specimens, and intraplaque hemorrhage in almost two thirds of specimens. Sixty four percent of plaques demonstrated neovascularization. It was not possible to demonstrate that complicated plaques (plaque rupture, thrombosis, intraplaque hemorrhage) are associated with symptoms, and it appears that such plaques may occur at any time, irrespective of symptoms.