Yutaka Tachikawa

Increased advanced glycation end products in atherosclerotic lesions of patients with end-stage renal disease

Although advanced glycation end products (AGEs) are increased in the serum and tissues of patients with end-stage renal disease, little is known about the role of AGEs in atherogenesis. We therefore carried out an immunohistochemical study on the accumulation of AGEs and apolipoprotein B in the human aortas of diabetic and nondiabetic subjects with end-stage renal disease. The atherosclerotic lesions included diffuse intimal thickening, fatty streaks and atherosclerotic plaque. We used antibodies against two different epitopes of AGE structures, i.e. an Nepsilon-(carboxymethyl)lysine-protein adduct (CML) and a structure(s) other than CML (nonCML). The area that was positive for an antigen as a percentage of the total area (%Ar) was determined morphometrically, using an NIH-image program. In diffuse intimal thickening, atherosclerotic plaque and tunica media, the %Ar of CML and nonCML was significantly greater in diabetic or nondiabetic subjects with end-stage renal disease than in control subjects without end-stage renal disease. In fatty streaks, the %Ar of nonCML was significantly greater in nondiabetic subjects with end-stage renal disease than in control subjects, while no difference in the %Ar of CML was found between the subjects with or without end-stage renal disease. Nondiabetic subjects with end-stage renal disease showed a significantly increased %Ar of apolipoprotein B in fatty streaks and atherosclerotic plaque than the control subjects. The %Ar of CML and nonCML significantly correlated with the duration of hemodialysis in diffuse intimal thickening and atherosclerotic plaque of subjects with end-stage renal disease, but not in fatty streaks. On the other hand, the %Ar was not related to the duration of diabetes in any of the lesions in the diabetic subjects with end-stage renal disease. In diffuse intimal thickening and atherosclerotic plaque, subjects with end-stage renal disease showed a significant correlation between the %Ar of apolipoprotein B and AGEs (CML and nonCML), as well as their immunohistochemical colocalization. These results suggest that impaired AGE clearance may cause the increased accumulation of AGEs in the aortic wall of subjects with end-stage renal disease, thus resulting in the rapid progression of atherosclerosis. The accumulation of AGEs may be related to an enhanced LDL deposition in atherosclerotic lesions of subjects with end-stage renal disease.

Immunohistochemical localization of different epitopes of advanced glycation end products in human atherosclerotic lesions

To better understand the role of advanced glycation end products (AGEs) in atherogenesis, we developed specific antibodies against different immunological epitopes of AGE structures, including Nepsilon-(carboxymethyl)lysine-protein adduct (CML) and a structure(s) other than CML (nonCML), and demonstrated the immunohistochemical localization of CML- and nonCML-epitopes in atherosclerotic lesions of human aorta, which were obtained at autopsy from 20 nondiabetic patients (12 males and eight females; mean age, 60.8+/-16.7 years). Monoclonal anti-CML antibody (6D12) recognized not only AGE-modified proteins, but also CML-modified proteins. On the other hand, polyclonal anti-nonCML antibody reacted to AGE-modified proteins, but not to CML-modified proteins. Both antibodies were unreactive to the early-stage products of glycation, including fructose-modified butyloxycarbonyl-lysine and fructose-epsilon-aminocaproic acid. Atherosclerotic lesions included diffuse intimal thickening (DIT), fatty streaks (FS), atherosclerotic plaques (AP) and complicated lesions. An immunohistochemical analysis showed both CML- and nonCML-epitopes to be found along the collagen fibers in DIT in subjects more than 40 years old, but not in subjects less than 40 years old. CML-epitopes accumulated mainly in the cytoplasm of macrophage/foam cells, while nonCML-epitopes accumulated exclusively in the extracellular spaces in FS. APs showed the CML-epitope stored macrophage/foam cells, and the accumulation of both CML- and nonCML-epitopes in the lipid-rich fibrous area. An immunohistochemical analysis with a monoclonal antibody against oxidized low density lipoprotein (FOH1a/DLH3) showed the presence of this antigen within the cytoplasm of the macrophage/foam cells in atherosclerotic lesions, which were also positive for the CML-epitopes. These findings thus suggest that the heterogeneous localization of AGEs in atherosclerotic lesions depends on their different epitopes, and that a close link, therefore, exists between the peroxidation of LDL and the formation of AGEs in atherosclerotic lesions.

Off‐Pump Coronary Artery Bypass Grafting in Patients with End‐Stage Renal Disease on Hemodialysis

Abstract  Background: Coronary artery bypass grafting (CABG) for hemodialysis patients is high risk compared with other patient groups. The aim of this study was to analyze the potential benefits of off‐pump CABG for hemodialysis patients. Methods: From April 1994 through December 2000, 26 hemodialysis patients underwent CABG. The off‐pump group consisted of 15 patients operated on without a pump and the on‐pump group consisted of 11 patients operated on with a pump. Results: There was no difference between the two groups with regard to mean age, mean number of diseased vessels and mean number of anastomoses per patient. No patient died in either group during hospitalization. The postoperative complication rate was low in both groups. The postoperative ventilation time was shorter in the off‐pump group (8.5 vs 26.1 hours, p < 0.001, respectively [off‐pump group vs on‐pump group]). The length of ICU stay was shorter in the off‐pump group (1.7 vs 3.5 days, p # 0.01, respectively [off‐pump group vs on‐pump group]). The medial cost was lower in the off‐pump group (

Calcification of the Medial Layer of the Internal Thoracic Artery in Diabetic Patients: Relevance of Glycoxidation

26,200.80 versus

Coronary artery bypass grafting without cardiopulmonary bypass for high-risk patients☆

44,024.10 p # 0.0001 respectively [off‐pump group vs on‐pump group]). Conclusions: Off‐pump CABG provided excellent less‐invasive cardiac surgical results for dialysis patients.

Oxidative damage of vascular smooth muscle cells by the glycated protein–cupric ion system

Objective: The aim of this study was to evaluate the role of glycoxidation in the calcification of the internal thoracic artery (ITA) in diabetes mellitus (DM). Methods: ITA samples were obtained from 17 patients with type 2 DM (age 62.9 ± 10.5 years) and 12 age-matched, nondiabetic patients (age 62.5 ± 10.2 years) who underwent coronary artery bypass grafting. These samples were analyzed histopathologically and assessed for calcification by von Kossa staining and for glycoxidation by immunohistochemistry using anti-NΕ-(carboxymethyl)lysine (CML) antibody. Morphometric evaluation of calcification of the medial layer, intimal thickness and intima-to-media ratio was performed using NIH image software. To evaluate the mechanism of the interaction between calcification and glycoxidation, we developed an in vitro model of calcification of collagen that was chemically modified by glucose, glutaraldehyde or epoxy compound. The calcium-binding activity of these collagens was determined in hydrolysates using atomic absorption spectrophotometry. Results: ITAs of both diabetic and nondiabetic patients were free of atherosclerosis, and no differences were found between the two groups with regard to intimal thickness and intima-to-media ratio. Areas of calcification were noticed in both groups in the tunica media, but not in the tunica intima. Calcium deposits were localized within the extracellular matrix, which was immunohistochemically positive for CML. The extent of medial layer calcification was significantly greater in diabetic patients than nondiabetic subjects, but was independent of known risk factors such as hypertension, hyperlipidemia, obesity and history of old myocardial infarction. The binding activity of collagen was time-dependently increased with in vitro incubation of glucose. A significant increase in the calcium-binding ability was observed in glucose- and glutaraldehyde-modified collagens, but not in epoxy compound-modified collagen. Conclusion: Our results suggest that glycoxidative modification of the extracellular matrix, in particular collagen, of the vascular wall may enhance the development of ITA calcification in diabetic patients.

Commissural dehiscence and pannus formation of porcine heart valve bioprostheses.

Between January 1991 and June 1993, coronary artery bypass grafting was performed without either cardiopulmonary bypass or cardiac arrest in 23 patients. Most patients had several surgical risk factors, including age > or = 70 years, poor left ventricular function, left main coronary artery stenosis, chronic renal failure, and aortic aneurysm. Distal anastomoses were made under temporary interruption of coronary flow. A total of 37 distal anastomoses to the left anterior descending coronary artery and/or right coronary artery (mean 1.6 per patient) were made, 24 of which were internal thoracic arteries. The coronary occlusion time ranged from 7-14 min (mean 9.8 min). Combined cardiac or vascular operations were carried out in six patients (abdominal aortic aneurysm repair, thoracic aortic aneurysm repair, carotid endarterectomy, and coronary endarterectomy). There was one hospital death. Postoperative angiography was performed in 22 patients and showed a patency rate of 89%. In summary, coronary artery bypass grafting without cardiopulmonary bypass may improve the postoperative outcome of high-risk patients.