Search PubMed⌕ Search

Biomedical subjects

E J Lesnefsky

Publications and source records attributed to E J Lesnefsky.

At least 19 recordsLinked to original sources
PubMed2001

Ischemic injury to mitochondrial electron transport in the aging heart: damage to the iron-sulfur protein subunit of electron transport complex III.

The aging heart sustains greater injury during ischemia and reperfusion compared to adult hearts. Aging decreases oxidative function in interfibrillar mitochondria (IFM) that reside among the myofibers, while subsarcolemmal mitochondria (SSM), located beneath the plasma membrane, remain unaltered. Aging decreases complex III activity selectively in IFM via alteration of the cytochrome c binding site. With 25 min of global ischemia, complex III activity decreases in SSM and further decreases in IFM in the aging heart. Ischemia leads to a marked decrease in the electron paramagnetic resonance signal of the iron-sulfur protein (ISP) in both SSM and IFM, despite a preserved content of ISP peptide. Thus, ischemia results in a functional decrease in the iron-sulfur center in ISP without subunit peptide loss. In the aging heart, at the onset of reperfusion, IFM contain two tandem defects in the path of electron flow through complex III, providing a likely mechanism for enhanced oxidant production and reperfusion damage.

Age Factors↗
PubMed2001

Aging decreases electron transport complex III activity in heart interfibrillar mitochondria by alteration of the cytochrome c binding site.

Aging alters cardiac physiology and structure and enhances damage during ischemia and reperfusion. Aging selectively decreases the rate of oxidative phosphorylation in the interfibrillar population of cardiac mitochondria (IFM) located among the myofibers, whereas subsarcolemmal mitochondria (SSM) located beneath the plasma membrane remain unaffected. Aging decreased the rate of oxidative phosphorylation using durohydroquinone, an electron donor to complex III, in IFM only. Complex III activity was decreased in IFM, but not SSM. Aging did not alter the content of catalytic centers of complex III (cytochromes b and c(1)and iron-sulfur protein). Complex III activity measured at physiologic ionic strength in IFM from aging hearts was decreased by 49% compared to IFM from adults, whereas activity measured at low ionic strength was unchanged, localizing the aging defect to the cytochrome c binding site of complex III. Subunits VIII and X of the cytochrome c binding site were present in complex III with the aging defect, indicating that loss of subunits did not occur. Study of aging damage to complex III will help clarify the contribution of altered electron transport in IFM to increased oxidant production during aging, formation of the aging cardiac phenotype, and the relationship of aging defects to increased damage following ischemia.

Aging↗
PubMed2001

Mitochondrial dysfunction in cardiac disease: ischemia--reperfusion, aging, and heart failure.

Mitochondria contribute to cardiac dysfunction and myocyte injury via a loss of metabolic capacity and by the production and release of toxic products. This article discusses aspects of mitochondrial structure and metabolism that are pertinent to the role of mitochondria in cardiac disease. Generalized mechanisms of mitochondrial-derived myocyte injury are also discussed, as are the strengths and weaknesses of experimental models used to study the contribution of mitochondria to cardiac injury. Finally, the involvement of mitochondria in the pathogenesis of specific cardiac disease states (ischemia, reperfusion, aging, ischemic preconditioning, and cardiomyopathy) is addressed.

Aging↗
PubMed2001

Myocardial ischemia selectively depletes cardiolipin in rabbit heart subsarcolemmal mitochondria.

Mitochondria contribute to myocyte injury during ischemia. After 30 and 45 min of ischemia in the isolated perfused rabbit heart, subsarcolemmal mitochondria (SSM), located beneath the plasma membrane, sustain a decrease in oxidative phosphorylation through cytochrome oxidase. In contrast, oxidation through cytochrome oxidase in interfibrillar mitochondria (IFM), located between the myofibrils, remains unaffected. Cytochrome oxidase activity in the intact membrane requires an inner mitochondrial membrane lipid environment enriched in cardiolipin. During ischemia, the content of cardiolipin decreased only in SSM, whereas the content of other phospholipids was preserved. Ischemia did not alter the composition of the cardiolipin that remained in SSM. Cardiolipin content was preserved in IFM during ischemia. Thus cardiolipin is a relatively early target of ischemic mitochondrial damage, leading to loss of oxidative phosphorylation through cytochrome oxidase in SSM.

Animals↗
PubMed2000

Separation and quantitation of phospholipids and lysophospholipids by high-performance liquid chromatography.

We describe a comprehensive approach to the separation, quantitation, and characterization of phospholipids and lysophospholipids present in complex biological samples. The central feature is a normal-phase HPLC separation of individual phospholipid and lysophospholipid classes. In this single chromatographic step, phospholipids and lysophospholipids are separated and recovered for quantitation by organic phosphate assay and characterization by acyl-group composition. Recovery of phospholipids and lysophospholipids from HPLC averages 80-90%. Isolated phospholipid and lysophospholipid fractions are available for separation of individual molecular species by second-dimension reverse-phase HPLC and characterization of individual molecular species by mass spectrometry.

Animals↗
PubMed1999

Aging selectively decreases oxidative capacity in rat heart interfibrillar mitochondria.

Mitochondrial-derived oxidative injury contributes to cellular aging as well as to reperfusion-induced tissue damage. While the aging-heart suffers greater tissue damage following ischemia and reperfusion than the adult heart, the occurrence of aging-related alterations in mitochondrial oxidative metabolism in the elderly heart has remained uncertain. We determined if aging altered oxidative metabolism in either of the two populations of cardiac mitochondria, subsarcolemmal mitochondria (SSM) that reside beneath the plasma membrane or interfibrillar mitochondria (IFM) located between the myofibrils. SSM and IFM were isolated from 6-month adult and 24- and 28-month elderly Fischer 344 rat hearts. Aging-related alterations were limited to IFM, while SSM remained unaffected. Aging decreased the rate of oxidative phosphorylation in IFM, including when stimulated by electron donors specific for cytochrome oxidase. Cytochrome oxidase enzyme activity was decreased in IFM from aging hearts, while activity in SSM remained similar to adult controls. These findings allow future studies of aging-related decrements in oxidative function to focus upon IFM, while SSM provide an inherent control group of mitochondria that are free of aging-related alterations in oxidative function. The selective alteration of IFM during aging raises the possibility that the consequences of aging-induced mitochondrial dysfunction will be enhanced in specific subcellular regions of the senescent myocyte.

Adenosine Diphosphate↗
PubMed1997

Sensitivity of protein sulfhydryl repair enzymes to oxidative stress.

According to their demonstrated activities, the thiol-disulfide oxidoreductase (TDOR) enzyme systems [thioltransferase (glutaredoxin) and GSSG reductase; and thioredoxin and thioredoxin reductase] are expected to provide the primary cellular mechanism for protection and repair of sulfhydryl proteins under oxidative stress. Since all four enzymes have active site dithiol moieties, they may be vulnerable to oxidative damage themselves. Therefore, an hydroxyl radical generating system (chelated ferrous iron in combination with hydrogen peroxide) was used to document the relative sensitivity of each of the enzymes to oxidative stress in vitro. At particular concentrations of enzymes and oxidant system, all of the enzymes were deactivated nearly completely, but different patterns of susceptibility were observed. At the approximate physiological concentration of each enzyme thioredoxin and thiol-transferase were largely deactivated with 1 mM Fe2+-ADP, 1 mM H2O2; whereas thioredoxin reductase and GSSG reductase were much less sensitive: 10 microM thioredoxin (88% deactivated), 1 microM thioltransferase (72%), 2 microM thioredoxin reductase (5%), and 0.1 microM GSSG reductase (17%). As the concentration of the oxidant system was decreased stepwise from 1 mM to 1 microM to mimic conditions that may be associated with oxidative tissue injury in situ, deactivation of thioredoxin was decreased proportionately, whereas thioltransferase remained much more susceptible. As expected GSH and other radical scavengers protected thioltransferase from deactivation by Fe(ADP)-H2O2. To test the susceptibility of the TDOR enzymes to oxidative stress in a physiological-like setting, isolated perfused rabbit hearts were subjected to 30 min ischemia and 30 min reperfusion. The GSH/GSSG ratio and total dethiolase activity (thioltransferase and thioredoxin systems) remained unchanged relative to control hearts, indicating that overall redox status and sulfhydryl repair activity are maintained during moderate oxidative stress in situ.

Animals↗
PubMed1997

Myocardial ischemia decreases oxidative phosphorylation through cytochrome oxidase in subsarcolemmal mitochondria.

The effect of myocardial ischemia on mitochondrial oxidative phosphorylation was investigated using isolated, buffer-perfused rabbit hearts. After 45 min of global ischemia, oxidative phosphorylation was decreased only in the subsarcolemmal population of mitochondria with all substrates tested. The oxidation of N,N,N',N' tetramethyl p-phenylenediamine-ascorbate, an electron donor to cytochrome oxidase via cytochrome c, was decreased in subsarcolemmal mitochondria [ischemia (n = 6): 76 +/- 3 vs. control (n = 5): 105 +/- 6 nanoatoms O.min-1.mg-1, P < 0.01] but not in interfibrillar mitochondria. Only minor morphological changes were observed by electron microscopy in the isolated mitochondria after ischemia. Neither cytochrome oxidase activity measured under conditions for maximal activity nor the apparent Michaelis constant and maximum velocity values of the two cytochrome c binding sites were different in subsarcolemmal mitochondria isolated from ischemic and control hearts. The cytochrome c content was decreased in subsarcolemmal mitochondria after ischemia (ischemia: 0.111 +/- 0.013 vs. control: 0.156 +/- 0.007 nmol/mg protein, P < 0.05). Thus ischemia decreased the rate of oxidative phosphorylation through cytochrome oxidase selectively in intact subsarcolemmal mitochondria. Ischemic damage to the terminal segment of the electron transport chain involves a decrease in the content of cytochrome c, whereas the expressible catalytic activity of cytochrome oxidase remains unchanged.

Adenosine Diphosphate↗
PubMed1996

ATP catabolism and adenosine generation during ischemia in the aging heart.

Myocardial injury following ischemia and reperfusion is increased in the aging heart. The mechanisms underlying the increased susceptibility of the aging heart to ischemic injury remain unknown. We investigated whether decreased glycogen utilization with a more rapid depletion of ATP occurred during ischemia in the aging heart. Isolated buffer-perfused hearts from adult (6 months old) and aging (24 months old) Fischer 344 rats were subjected to 0, 2, 5, 10, 15 or 25 min of global stop-flow ischemia following a 15 min equilibration period (n = 5-6 for each ischemic time at each age). ATP level were decreased at preischemic baseline in aging hearts. ATP levels remained lower in the aging heart throughout ischemia (P < 0.001) with a similar pattern of decrease in both age groups. The decrease in tissue glycogen and increase in lactate contents was similar during ischemia in both age groups, suggesting that comparable glycogen utilization occurred during ischemia in adult and aging hearts. ATP catabolism leads to ADP, AMP and then adenosine. Tissue levels of adenosine, an important cardioprotective metabolite, were measured during ischemia. Tissue adenosine levels were decreased by 50% in the aging heart at 5 and 10 min, and remained depressed at 15 min and 25 min of ischemia compared to adult controls. Thus, increased ischemic injury in the aging heart is not related to differences in glycogen consumption. Lower tissue ATP levels and decreased adenosine levels were observed during ischemia. The differences in ATP content between adult and aging hearts occurred only during early ischemia and are unlikely to provide a mechanism for the increased damage observed following more prolonged periods of ischemia in the aging heart. The potential contribution of these decreases in tissue adenosine content to the increased injury observed in the aging heart will require further study.

Adenosine↗
PubMed1996

Increased left ventricular dysfunction in elderly patients despite successful thrombolysis: the GUSTO-I angiographic experience.

OBJECTIVE: This study sought to determine whether the recovery of regional and global left ventricular function is reduced in elderly patients despite successful thrombolytic therapy for acute myocardial infarction. Comparisons were made between elderly (> or = 75 years old, n = 47) and adult (< 75 years old, n = 434) patients enrolled in the Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries (GUSTO) angiographic trial who underwent catheterization at 90 min and 5 to 7 days after thrombolysis and who had an open infarct-related artery with Thrombolysis in Myocardial Infarction (TIMI) grade 2 to 3 flow at both times. BACKGROUND: The morbidity and mortality of acute myocardial infarction is increased in elderly patients, presumably because of multiple adverse coexistent baseline variables. However, functional recovery after thrombolysis has not been characterized in the elderly. METHODS: Ejection fraction, end-systolic volume index, infarct and noninfarct zone contractile function (SD/chord) and infarct extent (number of chords) were determined. RESULTS: At 90 min, elderly patients with an open infarct-related artery had decreased infarct zone contractile function (-2.8 +/- 0.2 vs. -2.3 +/- 0.1 SD/chord in adults, p < or = 0.05) and a greater extent of injury (26.0 +/- 2.6 vs. 20.7 +/- 0.8 chords in adults, p < or = 0.05). At 5- to 7-day follow-up ventriculography, ejection fraction was reduced, and end-systolic volume index was significantly increased in elderly patients compared with adults. The severity of regional wall motion dysfunction in the infarct zone was also greater in the elderly than in adults at 5- to 7-day follow-up (-2.6 +/- 0.2 vs. -1.9 +/- 0.1 SD/chord, respectively, p < or = 0.005). Non-infarct zone contractile function at 90-min ventriculography was similar in both groups. Despite a patent infarct-related artery at 90-min, the 30-day mortality rate in the elderly remained elevated (17.8%) compared with that of adults (4%) (p < or = 0.0001). Elderly patients were predominantly female and had a higher prevalence of hypertension, multivessel coronary disease, previous infarction, anterior infarctions and later time to treatment (between 3 and 6 h) than adults. However, age > or = 75 years remained an independent determinant by multivariable regression analysis of 1-week postinfarction end-systolic volume index, regional left ventricular dysfunction (p = 0.02 and p < or = 0.008, respectively) and 30-day mortality (p < or = 0.0001). CONCLUSIONS: Elderly patients had increased damage in the infarct zone and had persistently increased mortality despite sustained infarct-related artery patency after successful thrombolysis. Although the causes are probably multifactorial, a more rapid progression of ischemic injury or a blunted postreperfusion recovery appears to contribute to the poorer outcomes in elderly patients.

Adult↗
PubMed1996

Incremental iron overload during reperfusion progressively augments oxidative injury.

OBJECTIVE: To determine if a relationship exists between the extent of iron-catalyzed injury and the degree of tissue iron overload during reperfusion. METHODS: To selectively increase tissue iron only during early reperfusion, isolated, buffer perfused rabbit hearts were exposed to 20 microM Fe(2+)-100 microM ADP during the last 3 minutes of ischemia and the initial 4 minutes of reperfusion. Control groups were exposed to ADP and iron-ADP regimens that did not increase intracellular iron. All the hearts received 30 minutes of normothermic global ischemia and 30 minutes of reperfusion. Heart function was monitored continuously throughout each experiment. Tissue iron and biochemical markers were analyzed at the end of experiments. RESULTS: Hemodynamic recovery was decreased and tissue lipid peroxide levels were increased in the 20 microM Fe(2+)-100 microM ADP group compared to controls. The recoveries of developed pressure and positive/negative dP/dT at 30 minutes of reperfusion were negatively correlated with tissue iron levels, while cytosol and membrane lipid peroxide levels correlated positively with the iron levels during reperfusion. CONCLUSION: The extent of oxidative injury during reperfusion was directly related to the tissue iron burden present during reperfusion. Increased lipid peroxidation was the principal chemical marker of iron-catalyzed injury.

Animals↗
PubMed1994

Tissue iron overload and mechanisms of iron-catalyzed oxidative injury.

Tissue iron overload causes clinical syndromes that involve the heart, liver, and pancreas. While tissue iron uptake occurs by both transferrin-dependent and independent processes, tissue uptake in the iron overload syndromes occurs predominantly via transferrin-independent mechanisms. Increased redox-active iron present in hemeproteins and the cytosolic iron pool can catalyze oxidative damage to lipids, proteins, and nucleic acids, either by oxyradical dependent or independent mechanisms. Iron-catalyzed injury results in damage to cell constituents, including mitochondria, lysosomes, and the sarcolemmal membrane. These mechanisms of iron-mediated damage are involved in the pathogenesis of organ dysfunction in primary hemochromatosis, transfusion-related iron overload, ischemia-reperfusion injury, and cardiac anthracycline toxicity.

Animals↗
PubMed1994

Exogenous intracellular, but not extracellular, iron augments myocardial reperfusion injury.

Although previous studies using iron chelators suggest that iron-catalyzed reactions exacerbate myocardial injury, a direct demonstration of the timing, sites, and mechanisms of iron-mediated damage during reperfusion has been lacking. Catalytic doses of redox-active iron react with exogenously administered oxygen radical-generating systems to exacerbate myocardial injury. In an analogous manner, catalytic doses (5 microM) of excess iron present during early reperfusion should augment oxidative injury, if the redox-active iron is present in the same compartment as both the oxygen radicals generated during reperfusion as well as the critical biochemical targets of oxidative injury. We determined whether catalytic doses of iron given during early reperfusion could exacerbate myocardial injury and whether iron-catalyzed injury required intra- or extracellular iron. Buffer-perfused rabbit hearts underwent 30 min of 37 degrees C global ischemia and 30 min of reperfusion. Iron (5 microM), attached to ligands that either restrict iron to the extracellular space (ADP) or facilitate the entry of iron into myocytes (omadine, tropolone), was infused during the last 3 min of ischemia and the first 4 min of reperfusion. Recovery of developed pressure was decreased (P < 0.05) in omadine-iron and tropolone-iron compared with ADP-iron and noniron hearts treated with ligands alone. Tissue lipid peroxide levels, an index of oxidative injury, were increased (P < 0.05) by omadine-iron and tropolone-iron, but not ADP-iron. The oxidative damage caused by omadine-iron was blocked by pretreatment with dimethylthiourea, a cell-permeable scavenger of the hydroxyl radical.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Diphosphate↗
PubMed1994

Prevention of lipid peroxidation does not prevent oxidant-induced myocardial contractile dysfunction.

We tested whether, with exposure to an extraneous iron-catalyzed free radical-generating system, prevention of lipid peroxidation with U74006F, a 21-aminosteroid, could also prevent myocardial contractile dysfunction. Rabbits received either U74006F (10 mg/kg iv) or vehicle (V). Thirty minutes later the hearts were excised and perfused by a non-recirculating Langendorff technique. Six U74006F- and six V-treated hearts were exposed for 7.5 min to a .OH-generating system (H2O2 and Fe(2+)-ADP chelate). Myocardial lipid peroxides were measured by glutathione peroxidase-catalyzed oxidation of exogenous glutathione. With exposure to .OH, cytosolic lipid peroxide levels were increased threefold in V-treated hearts, but there was no increase in U74006F-treated hearts. After 30 min of recovery, developed pressure and maximum first derivative of left ventricular pressure were greater in U74006F-treated hearts than in V-treated hearts but were still 50 and 44% of levels in saline hearts, respectively. Coronary flow was markedly reduced after exposure to free radicals and was only slightly less depressed when U74006F was administered. When coronary flow following oxidant exposure was increased by nitroglycerin, U74006F again only modestly improved systolic function. Thus, although U74006F blocked lipid peroxidation, it only slightly improved the ventricular dysfunction caused by .OH. Therefore, factors other than lipid peroxidation play a major role in oxidant-induced myocardial stunning.

Adenosine Diphosphate↗
PubMed1994

Aging increases ischemia-reperfusion injury in the isolated, buffer-perfused heart.

Survival after acute myocardial infarction is decreased in elderly patients as compared with the overall adult population. Although several cardiac and noncardiac causes could contribute to the increased mortality rate, little is known regarding the relative susceptibility of aging myocardium to injury during ischemia and reperfusion. We hypothesized that the elderly heart is intrinsically more susceptible to damage than the adult heart. The recovery of isolated, buffer-perfused rat hearts from elderly animals (Fischer 344 rats, 24 months of age) was compared with that of adult hearts (6 months of age) obtained from the same strain. Hearts underwent 25 minutes of ischemia followed by 30 minutes of reperfusion. Hemodynamic recovery was decreased in elderly (n = 5) as compared with adult (n = 5) hearts, including developed pressure (% of preischemic baseline: elderly 31% +/- 4% vs adult 57% +/- 4%, p < 0.01). Elderly hearts also sustained greater tissue damage, with a markedly increased release of creatine kinase (elderly 2950 +/- 500 U vs adult 860 +/- 345 U, p < 0.01) during the 30-minute reperfusion period. The release of total protein and lactate dehydrogenase, other markers of myocyte injury, was also increased. Thus the elderly rat heart is more susceptible than the adult rat heart to ischemia-reperfusion injury. Greater injury during ischemia and reperfusion in an experimental model of aged myocardium raises the possibility of a more rapid progression of ischemic damage in elderly patients suffering acute myocardial infarction.

Aging↗
PubMed1993

Safety of cardiac catheterization via peripheral vascular grafts.

There are few data concerning the complications and technical difficulties encountered when cardiac catheterization is performed using peripheral bypass grafts for vascular access. All cardiac catheterizations performed at our institution from January 1, 1984 to April 1, 1991 were retrospectively reviewed to assess the in-hospital clinical outcomes in patients who had arterial access for catheterization achieved via prosthetic graft puncture. Seventeen procedures had percutaneous puncture of a vascular graft from a total of 2,929 arterial catheterizations performed. The interval from graft placement to catheterization was 7.5 +/- 1.1 years. Arterial sheaths were employed in all cases and corresponded to the catheter size, with 5F systems used in 53% and 7F or larger systems used in the remaining patients. No intraprocedural or postprocedural complications were recognized. Technical difficulties were limited to the inability to selectively cannulate a nondominant right coronary artery in 1 patient. We conclude that percutaneous introduction of an arterial sheath and left heart catheterization via remotely implanted vascular bypass grafts is not associated with an increased risk of procedural complications or technical difficulties.

Angioplasty, Balloon, Coronary↗
PubMed1993

Intracoronary ultrasound imaging: correlation of plaque morphology with angiography, clinical syndrome and procedural results in patients undergoing coronary angioplasty.

OBJECTIVES: This study was designed to establish the relation between ultrasound-derived atheroma morphology and the clinical, procedural and angiographic features of patients presenting for coronary angioplasty. BACKGROUND: Intracoronary ultrasound imaging provides accurate dimensional information regarding arterial lumen and wall structures. Atheroma composition may also be assessed by ultrasound; however, only limited studies have been performed in patients. METHODS: In 65 patients a diagnostic ultrasound imaging catheter or a combination imaging-angioplasty balloon catheter was used during coronary angioplasty to image both the lesion and the vessel segment just proximal to it (reference segment). Ultrasound images were analyzed for lumen, total vessel and plaque areas and were classified into five morphologic subtypes (soft, fibrous, calcific, mixed plaque and concentric subintimal thickening). These data were compared with angiographic morphologic features, procedural results and clinical angina pattern (stable vs. unstable). RESULTS: Morphologic analysis of the ultrasound images obtained from the lesion correlated well with the clinical angina syndrome. Compared with patients with stable angina, patients with unstable angina had more soft lesions (74% vs. 41%), fewer calcified and mixed plaques (fibrotic, soft or calcific components in one or more combinations [25% vs. 59%]) and fewer intralesional calcium deposits (16% vs. 45%) (all p < 0.01). There was no correlation between ultrasound and angiographic lesion morphologic characteristics for either the reference segment or the lesion. Ultrasound demonstrated greater sensitivity than angiography for identifying unstable lesions (74% vs. 40%). Dimensional analysis demonstrated a large plaque burden in the reference segments (45 +/- 15% of total vessel area). Postangioplasty plaque burden was also high (62 +/- 9%). There was a significant, but only fair correlation between lumen area determined by angiography and ultrasound for both the reference segment (r = 0.70, p < 0.001) and the postangioplasty lesion (r = 0.63, p < 0.05). CONCLUSIONS: Morphologic plaque classification by ultrasound is closely correlated to clinical angina but has little relation to established angiographic morphologic characteristics. Intracoronary ultrasound imaging during angioplasty identifies a large residual plaque burden in both the reference segment and the lesion. In the future, determination of plaque composition by intracoronary ultrasound may be important in selecting or modifying interventional therapeutic options.

Aged↗