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Jonathan Leor

Publications and source records attributed to Jonathan Leor.

At least 37 records · Page 2Linked to original sources
PubMed2004

Is hypoglycaemia a marker for increased long-term mortality risk in patients with coronary artery disease? An 8-year follow-up.

BACKGROUND: No information is available regarding the association between low plasma glucose levels and cause-specific and all-cause mortality in patients with coronary artery disease (CAD). We aimed to investigate the relationship between hypoglycaemia and all-cause, cardiovascular and cancer mortality in a large population of patients with CAD. DESIGN: Patients were recruited from the BIP (Bezafibrate Infarction Prevention) registry, a secondary prevention prospective multicentre randomized, placebo-controlled, double-blind trial aimed to assess the efficacy of bezafibrate in reduction of coronary events. METHODS: The study included 14,670 CAD patients aged 45-74, divided into six groups: (1) hypoglycaemic (up to 69 mg/dl); (2) low normal (70-79 mg/dl); (3) euglycaemic (80-109 mg/dl); (4) impaired fasting glucose (IFG) (110-125 mg/dl); (5) borderline diabetics (126-139 mg/dl); (6) diabetics (> or 140 mg/dl). RESULTS: Patients comprised 131 with hypoglycaemia (0.9%), 731 with low normal glucose (5%), 9308 euglycaemic (63.4%), 1577 with IFG (10.7%), 617 borderline diabetics (4.2%) and 2306 diabetics (15.7%). Over a mean 8-year follow-up, crude all-cause mortality was higher in both diabetic (31.8%) and hypoglycaemic groups (25.2%) as compared with euglycaemics (14.9%; P<0.0001); CAD mortality was higher in diabetic and borderline groups (17.8 and 13.3%, respectively, versus 7.9% in euglycaemics; P<0.0001). The highest prevalence of cancer mortality was documented in the hypoglycaemic group (6.1 versus 2.9% in euglycaemics; P<0.02). Actuarial survival curves showed the lowest mortality in euglycaemic and low normal groups; the highest was seen in diabetic and hypoglycaemic patients. Intermediate values were found in borderline and IFG patients. After adjustment for variables, a significantly higher mortality rate was seen in hypoglycaemics when compared with euglycaemics (P<0.0001). Hypoglycaemia was identified as a predictor of increased all-cause and cancer mortality with a hazard ratio (HR) of 1.84 [95% confidence interval (CI) 1.29-2.61] and 2.26 (95% CI 1.12-4.57), respectively, but not of increased CAD mortality, with HR 1.30 (95% CI 0.73-2.29). CONCLUSIONS: Over a mean 8-year follow-up, hypoglycaemia emerges as a marker for substantially increased all-cause and cancer mortality among patients with CAD presenting with low fasting glucose levels.

Aged↗
PubMed2004

Myocardial tissue engineering: creating a muscle patch for a wounded heart.

Cardiac tissue engineering promises to revolutionize the treatment of patients with end-stage heart failure and provide new solutions to the serious problem of heart donor shortage. By its broad definition, tissue engineering involves the construction of tissue equivalents from donor cells seeded within three-dimensional polymeric scaffolds, then culturing and implanting of the cell-seeded scaffolds to induce and direct the growth of new, healthy tissue. Here, we present an up-to-date summary of research studies in cardiac tissue engineering, with an emphasis on the critical design principles.

Cardiomyopathies↗
PubMed2003

Comparison of effectiveness of angiotensin-converting enzyme inhibitors after acute myocardial infarction in diabetic versus nondiabetic patients.

Mortality and morbidity after acute myocardial infarction (AMI) is higher in diabetic than in nondiabetic patients. Angiotensin-converting enzyme (ACE) inhibitors have been shown to exert a beneficial effect after AMI. We sought to evaluate the association between treatment with ACE inhibitors and 1-year outcome after AMI in diabetic and nondiabetic patients in a national survey. The study population was drawn from a national survey conducted in all coronary care units operating in Israel during a 5-month period in 1996, and included 2,179 patients with AMI: 533 diabetics (24%), 322 of whom received ACE inhibitors (60%) and 211 who did not; and 1,646 nondiabetics, 805 of whom received ACE inhibitors and 841 who did not. In both groups of patients, those treated with ACE inhibitors were older, included more women, more had a history of AMI, anterior wall AMI, or hypertension, and more had worse Killip class on admission. Diabetic patients treated with ACE inhibitors experienced lower 1-year mortality rates than diabetics not treated with ACE inhibitors (16.2% vs 18.8%, respectively; covariate adjusted hazard ratio 0.47, 95% confidence interval 0.30 to 0.74). In nondiabetic patients, however, ACE inhibitor treatment was not associated with a better outcome (10.2% vs 7.3%, respectively; covariate adjusted hazard ratio 0.80; 95% confidence interval 0.56 to 1.15). Thus, treatment with ACE inhibitors after AMI appears to be particularly beneficial in diabetic patients. The beneficial effect observed supports the widespread use of ACE inhibitors in diabetic patients after AMI.

Aged↗
PubMed2003

Association of elevated homocysteine levels with a higher risk of recurrent coronary events and mortality in patients with acute myocardial infarction.

BACKGROUND: Despite the prothrombotic and proinflammatory effects associated with elevated homocysteine levels, only limited data exist regarding the effect of homocysteine levels on outcome of patients with acute myocardial infarction. METHODS: Homocysteine levels were determined within 24 hours of presentation in 157 consecutive patients with acute myocardial infarction. Patients were allocated to 2 groups: those with homocysteine levels of 2.7 mg/L (20 micro mol/L) or more (n = 22 [14%]) and those with homocysteine levels of less than 2.7 mg/L (n = 135 [86%]). RESULTS: Female and diabetic patients had significantly lower homocysteine levels than males (P<.01) and nondiabetic patients (P =.005), respectively, with no significant correlation with age (r = 0.07, P =.42) or other risk factors. Patients with homocysteine levels greater than or equal to 2.7 mg/L and less than 2.7 mg/L did not differ significantly regarding extent of coronary artery disease as reflected by prevalence of multivessel disease (54% vs 61%; P =.87), and their in-hospital course. However, in a mean +/-SD follow-up of 30 +/- 10 months, patients with homocysteine levels greater than or equal to 2.7 mg/L had a higher incidence of recurrent coronary events (36% vs 17%; P =.04) and death (18% vs 5%; P<.05). Homocysteine levels greater than or equal to 2.7 mg/L remain a significant determinant of recurrent coronary event and/or death after controlling for potential cofounders by multivariate analysis (odds ratio, 3.8; 95% confidence interval, 1.3-11.0). CONCLUSIONS: In patients with acute myocardial infarction, elevated homocysteine levels are associated with a higher risk of recurrent coronary events and death, independent of other risk factors and the extent of coronary artery disease.

Aged↗
PubMed2003

Systemic delivery of bone marrow-derived mesenchymal stem cells to the infarcted myocardium: feasibility, cell migration, and body distribution.

BACKGROUND: Systemic delivery of bone marrow-derived mesenchymal stem cells (BM-MSCs) is an attractive approach for myocardial repair. We aimed to test this strategy in a rat model after myocardial infarction (MI). METHODS AND RESULTS: BM-MSCs were obtained from rat bone marrow, expanded in vitro to a purity of >50%, and labeled with 99mTc exametazime, fluorescent dye, LacZ marker gene, or bromodeoxyuridine. Rats were subjected to MI by transient coronary artery occlusion or to sham MI. 99mTc-labeled cells (4x10(6)) were transfused into the left ventricular cavity of MI rats either at 2 or 10 to 14 days after MI and were compared with sham-MI rats or MI rats treated with intravenous infusion. Gamma camera imaging and isolated organ counting 4 hours after intravenous infusion revealed uptake of the 99mTc-labeled cells mainly in the lungs, with significantly smaller amounts in the liver, heart, and spleen. Delivery by left ventricular cavity infusion resulted in drastically lower lung uptake, better uptake in the heart, and specifically higher uptake in infarcted compared with sham-MI hearts. Histological examination at 1 week after infusion identified labeled cells either in the infarcted or border zone but not in remote viable myocardium or sham-MI hearts. Labeled cells were also identified in the lung, liver, spleen, and bone marrow. CONCLUSIONS: Systemic intravenous delivery of BM-MSCs to rats after MI, although feasible, is limited by entrapment of the donor cells in the lungs. Direct left ventricular cavity infusion enhances migration and colonization of the cells preferentially to the ischemic myocardium.

Animals↗
PubMed2003

Functional class in patients with heart failure is associated with the development of diabetes.

PURPOSE: Recent reports suggest that decreased functional capacity in patients with heart failure may be associated with abnormalities in glucose metabolism. We followed patients with coronary artery disease who participated in the Bezafibrate Infarction Prevention study to determine the incidence of diabetes by baseline functional status during a 7.7-year follow-up. METHODS: The sample comprised 2616 nondiabetic patients aged 45 to 74 years with a fasting blood glucose level <7 mmol/L (126 mg/dL). They were divided into three groups by New York Heart Association (NYHA) criteria: class I (n = 1986 patients), class II (n = 518), and class III (n = 112). The detection of a fasting blood glucose level > or =7 mmol/L during follow-up was defined as the criterion for the development of diabetes. RESULTS: The study groups had similar demographic and clinical characteristics, except that patients with symptomatic heart failure (NYHA class II or III) were more likely to have angina. During follow-up, diabetes developed in 259 patients (13%) in NYHA class I, 76 (15%) in class II, and 22 (20%) in class III (P for trend = 0.05). At the last visit, patients in NYHA class III were twice as likely (17% [n = 19]) to have fasting blood glucose levels > or =7 mmol/L as those in NYHA class I (7.8% [n = 154]) or class II (8.7% [n = 45]) (P = 0.005). In a multivariate analysis, NYHA class III was associated with a 1.7-fold (95% confidence interval [CI]: 1.1 to 2.6) increase in the rate of development of diabetes, but NYHA class II was not (hazard ratio = 1.0; 95% CI: 0.8 to 1.3). CONCLUSION: Among patients with coronary artery disease, advanced heart failure (NYHA class III) is associated with a significantly increased risk of developing diabetes during a 6- to 9-year follow-up.

Age Distribution↗
PubMed2003

Reprogramming cells for transplantation.

The field of tissue engineering, involving the reprogramming of stem cells or rejuvenation of specific differentiated cells, is emerging as a promising strategy to repair the damaged myocardium. The eventual goal is to be able to take a patient's own cells, expand them ex vivo, genetically engineer them to enhance specific properties, and then reintroduce them into the patient's heart to create a replacement tissue. Our review paper describes data that supports the potential of this strategy. This clinically relevant, combined strategy of genetic and tissue engineering could be of importance in treating elderly patients with massive myocardial damage, patients whose normal myogenic or angiogenic cells have been depleted or are inadequate in their growth potential, to prevent LV deterioration and heart failure.

Animals↗
PubMed2003

Cardiomyocyte transplantation into the failing heart-new therapeutic approach for heart failure?

Heart failure, frequently the consequence of irreversible myocardial damage with subsequent formation of akinetic scar tissue, is a highly prevalent disease, and in its advanced stages associated with high mortality. The transplantation of exogenous cells with the inherent ability to contract has been put forward as one potential treatment strategy to increase contractility and cardiac performance. Besides skeletal myoblasts or stem cells from various sources, immature cardiomyocytes, such as fetal or neonatal cardiomyocytes, have been transplanted into normal, cryoinjured, infarcted myocardium, as well as into models of global heart failure. Survival of transplanted immature cardiomyocytes has been demonstrated up to 6-7 months, accompanied by vascularization of the grafted tissue. Transplants developed sarcomeric structures and other morphological features of differentiation. The principal possibility of cell-to-cell coupling between graft and host cells was demonstrated after cardiomyocyte transplantation into normal hearts and in some studies in damaged myocardium. But most long-term follow-up investigations in models of myocardial infarction reported that optimal integration of the engrafted cells appeared to be hindered by scar tissue, separating the transplant from the host. Nonetheless, in several studies, improved parameters of cardiac performance were demonstrated ex-vivo and in vivo. Potential mechanisms might involve beneficial effects on the remodeling process. In this review, we critically evaluate the potential value of cardiomyocyte transplantation as a new approach in the treatment of the syndrome of "heart failure".

Animals↗
PubMed2003

Refractoriness and conduction interaction during modulation of non-ischemic ventricular fibrillation by flecainide.

PURPOSE: To study refractoriness and conduction interaction during modulation of non-ischemic ventricular fibrillation (VF) by flecainide. METHODS: Isolated feline and rabbit hearts were used. (a) In the feline hearts (n = 8), electrophysiological parameters were measured before and after flecainide administration (0.6, 1.2 x 10(-6) M). During pacing the parameters were: epicardial conduction time, refractoriness and 1:1 pacing/response capture. During 8 min of electrically-induced tachyarrhythmias they included heart rate and normalized entropy reflecting the degree of organization. (b) In rabbit hearts (n = 4), three-dimensional mapping was performed before and after flecainide administration (2 x 10(-6) M). To follow changes in organization, local RR-intervals and differences in activation time between adjacent epicardial electrodes were measured immediately and 80 sec after VF induction. RESULTS: In feline hearts with flecainide, fibrillation was more difficult to induce, more frequently terminated spontaneously and was slower and more organized; conduction time was markedly lengthened, and refractoriness less than 1:1 capture, was moderately prolonged. An inverse correlation was observed between arrhythmia properties, rate and organization, and changes in refractoriness and conduction time. In rabbit, the number of wave fronts was reduced, RR-intervals were prolonged but at the same time activation time differences between adjacent electrodes were smaller following flecainide administration. CONCLUSIONS: It is suggested that flecainide modulation of VF properties is associated with conduction suppression and refractoriness prolongation, which act in a synergistic, additive way.

Animals↗
PubMed2003

Modulation of ventricular fibrillation in isolated perfused heart by dofetilide.

The authors studied the involvement of IKr potassium current in ventricular fibrillation during perfusion. Electrophysiologic parameters were measured before and after dofetilide administration (2.5, 7.5, and 12.5 x 10-7 M, n = 8) in isolated perfused feline hearts. During pacing, these parameters included epicardial conduction time, refractoriness, and the fastest rate for 1:1 pacing/response capture. During 8 minutes of electrically induced tachyarrhythmias, they included heart rate and normalized entropy reflecting the degree of organization. In all groups, arrhythmia rate was slower in the right ventricle than in the left ventricle. Dofetilide decreased the arrhythmia rate more than it increased organization, reduced its maintenance, or increased difficulty in initiation. Refractoriness was prolonged in a reverse use-dependent way which was less than 1:1 pacing/response capture. Unexpectedly, a moderate prolongation of conduction time was observed. Inverse correlation was found between the arrhythmia rate and changes in refractoriness and conduction time and between the degree of organization and refractoriness (both ventricles) and conduction time (right ventricle). Dofetilide, which intensively blocks IKr current and unexpectedly suppressed conduction, has different quantitative effects on fibrillation features. These changes in fibrillation suggest that these effects are mainly associated with refractoriness prolongation and do not seem to be attenuated by conduction suppression.

Animals↗
PubMed2003

Characteristics, management and outcome of patients with prior coronary bypass surgery presenting with acute myocardial infarction.

We compared the characteristics, management and outcome of patients with or without prior coronary artery bypass graft surgery (CABG) presenting with AMI to any coronary care unit in Israel, from four national surveys performed during 1992-1998. Of 5,396 patients, 171 (3.2%) had prior CABG, 39 of whom received thrombolysis. Thrombolysis was administered less often in patients with prior CABG, but the utilization of coronary angiography was similar. Mortality rates were higher in patients with prior CABG, particularly among those given thrombolysis. The use of coronary angiography was a strong independent predictor of survival, but its utilization was similar in patients with or without prior CABG. Patients with prior CABG constitute a small minority among current AMI patients. They are sicker and their mortality is higher compared to patients without prior surgery, especially among those given thrombolysis. Coronary angiography is associated with improved outcome in these patients but is currently used to the same extent as in patients without prior surgery.

Angioplasty, Balloon, Coronary↗
PubMed2003

Functional capacity impairment in patients with coronary artery disease: prevalence, risk factors and prognosis.

BACKGROUND: Some patients developing heart failure and functional capacity impairment have no history of myocardial infarction (MI), and stable angina pectoris is their principal clinical manifestation of coronary artery disease (CAD). The present study was aimed to evaluate the outcome of CAD-related functional capacity impairment in patients with and without a history of MI over a 7.7-year follow-up. METHODS: The study sample comprised 14,283 coronary patients aged 45-74 years, screened for participation in the Bezafibrate Infarction Prevention study. The presence of NYHA functional class II was defined as mild functional capacity impairment and the presence of NYHA functional class III-IV was defined as advanced functional capacity impairment. RESULTS: The patients were divided in two groups: (1) those with a history of MI, 10,307 patients, who formed three subgroups: NYHA I 7,551 patients (73.3%); NYHA II 2,176 patients (21.1%); NYHA III + IV 580 patients (5.6%), and (2) those without a history of MI, 3,976 patients, who also formed three subgroups: NYHA I 2,744 patients (69.0%); NYHA 981 patients (24.7%); NYHA III + IV 251 patients (6.3%). Multivariate analysis identified a history of MI as a consistent predictor of increased all-cause and cardiac mortality for patients with NYHA I, II and III + IV subgroups with escalating significance for patients with advanced functional capacity impairment: hazard ratios of 1.55 (95% CI 1.36-1.75), 1.56 (95% CI 1.30-1.86) and 1.72 (95% CI 1.24-2.40) for all-cause and 1.93 (95% CI 1.60-2.33), 1.73 (95% 1.35-2.20) and 3.22 (95% CI 1.87-5.54) for cardiac mortality, respectively. CONCLUSIONS: The prevalence of low functional capacity is similar among coronary patients with and without a history of MI, but their long-term survival differs substantially in favor of the latter. Therefore, two different types of CAD-related advanced functional capacity impairments (post-MI and non-post-MI) can be distinguished.

Aged↗
PubMed2003

Cell transplantation and genetic engineering: new approaches to cardiac pathology.

The remarkable progress in experimental cell transplantation, stem cell biology and genetic engineering promise new therapy and hopefully a cure for patients with end stage heart failure. Engineering of viable cardiac grafts with the potential to grow and remodel will provide new solutions to the serious problems of heart donor shortage. The ability to replace the injured heart muscle will have a dramatic influence on medicine, especially with the increasing number of patients with heart failure. This innovative research, now tested in human patients, still faces significant problems that need to be solved before it can be considered as an established therapeutic tool. The present review will focus on selected topics related to the promise and obstacles associated with cell transplantation, with and without genetic manipulation, for myocardial repair.

Animals↗
PubMed2003

A prospective national survey of management and clinical outcome of acute myocardial infarction in Israel, 2000.

BACKGROUND: Little information is available on the clinical practice and implementation of guidelines for treating acute myocardial infarction patients in Israel. OBJECTIVE: To assess patient characteristics, hospital course, management, and 30 day clinical outcome of all AMI patients hospitalized in Israel during a 2 month period in 2000. METHOD: We conducted a prospective 2 month survey of consecutive AMI patients admitted to 82 of 96 internal medicine departments and all 26 cardiac departments operating in Israel in 2000. Data were collected uniformly by means of a hospital and 30 day follow-up form. RESULTS: During the survey 1,683 consecutive patients with a discharge diagnosis of AMI were included. Their mean age was 66 years; 73% were male. The electrocardiographic pattern on admission revealed ST elevation, non-ST elevation and an undetermined ECG in 63%, 34% and 4% of patients respectively. Aspirin and heparin were given to 95% of patients. Beta-blockers and angiotensin-converting enzyme inhibitors were given to 76% and 65% of patients respectively. Among hospital survivors, 45% received lipid-lowering drugs. Thrombolytic therapy was administered in 28% of patients, coronary angiography was used in 45%, and 7% of patients underwent primary percutaneous coronary intervention. The 7 and 30 day mortality rates were 7% and 11% respectively. CONCLUSIONS: This nationwide survey shows that one-third of the AMI patients in Israel are elderly (> or = 75 years). The survey suggests that clinical guidelines for the management of patients with AMI are partially implemented in the community. Data from large surveys representing the "real world" practice are of utmost importance for the evaluation of clinical guidelines, research and educational purposes.

Aged↗
PubMed2002

Optimization of cardiac cell seeding and distribution in 3D porous alginate scaffolds.

Cardiac tissue engineering has evolved as a potential therapeutic approach to assist in cardiac regeneration. We have recently shown that tissue-engineered cardiac graft, constructed from cardiomyocytes seeded within an alginate scaffold, is capable of preventing the deterioration in cardiac function after myocardial infarction in rats. The present article addresses cell seeding within porous alginate scaffolds in an attempt to achieve 3D high-density cardiac constructs with a uniform cell distribution. Due to the hydrophilic nature of the alginate scaffold, its >90% porosity and interconnected pore structure, cell seeding onto the scaffold was efficient and short, up to 30 min. Application of a moderate centrifugal force during cell seeding resulted in a uniform cell distribution throughout the alginate scaffolds, consequently enabling the loading of a large number of cells onto the 3D scaffolds. The percent cell yield in the alginate scaffolds ranged between 60-90%, depending on cell density at seeding; it was 90% at seeding densities of up to 1 x 10(8) cells/cm(3) scaffold and decreased to 60% at higher densities. The highly dense cardiac constructs maintained high metabolic activity in culture. Scanning electron microscopy revealed that the cells aggregated within the scaffold pores. Some of the aggregates were contracting spontaneously within the matrix pores. Throughout the culture there was no indication of cardiomyocyte proliferation within the scaffolds, nor was it found in 3D cultures of cardiofibroblasts. This may enable the development of cardiac cocultures, without domination of cardiofibroblasts with time.

Alginates↗
PubMed2002

Cellular cardiomyoplasty of cardiac fibroblasts by adenoviral delivery of MyoD ex vivo: an unlimited source of cells for myocardial repair.

BACKGROUND: The muscle-specific MyoD family of transcription factors function as master genes that are able to prompt myogenesis in a variety of cells. The purpose of our study was to determine whether MyoD could induce primary cardiac fibroblasts, isolated from infarcted myocardium or pericardium, to undergo myogenic conversion in a clinically relevant approach. METHODS AND RESULTS: Primary rat fibroblasts from 7-day-old infarcted myocardium or normal pericardium were transfected by an E1/E3-deleted adenoviral vector carrying both a human MyoD cDNA driven by a CMV promoter and a green fluorescent protein (GFP) reporter gene driven by a second CMV promoter. Expression of MyoD caused myogenic differentiation of cultured fibroblasts, as defined by elongation and fusion into multinucleated myotubes, typical cross striation as identified by electron microscopy, and positive immunostaining for sarcomeric actin, fast myosin heavy chain (MHC), and actinin. The myogenic cells (1.5x10(6)) were transplanted into the infarcted myocardium 7 days after coronary artery occlusion. By 1 month after transplantation, the converted fibroblasts gave rise to a cluster of myogenic cells that in a few hearts occupied a large part of the scar with positive immunostaining for the myogenic proteins fast-MHC and sarcomeric actin. A few cells expressed the gap junction protein connexin 43 in a disorganized manner. There was no positive staining in the control hearts treated with injections of untreated fibroblasts or culture medium. CONCLUSIONS: Our work shows that it is possible to exploit the unique capacity of MyoD to activate myogenesis in fibroblasts ex vivo and to create a vast source of autologous myogenic cells for transplantation.

Adenoviridae↗