Type 2 diabetes is a redox disease. Oxidative stress and chronic inflammation induce a switch of metabolic homeostatic set points, leading to glucose intolerance. Several diabetes-specific mechanisms contribute to prominent oxidative distress in the heart, resulting in the development of diabetic cardiomyopathy. Mitochondrial overproduction of reactive oxygen species in diabetic subjects is not only caused by intracellular hyperglycemia in the microvasculature but is also the result of increased fatty oxidation and lipotoxicity in cardiomyocytes. Mitochondrial overproduction of superoxide anion radicals induces, via inhibition of glyceraldehyde 3-phosphate dehydrogenase, an increased polyol pathway flux, increased formation of advanced glycation end-products (AGE) and activation of the receptor for AGE (RAGE), activation of protein kinase C isoforms, and an increased hexosamine pathway flux. These pathways not only directly contribute to diabetic cardiomyopathy but are themselves a source of additional reactive oxygen species. Reactive oxygen species and oxidative distress lead to cell dysfunction and cellular injury not only via protein oxidation, lipid peroxidation, DNA damage, and oxidative changes in microRNAs but also via activation of stress-sensitive pathways and redox regulation. Investigations in animal models of diabetic cardiomyopathy have consistently demonstrated that increased expression of the primary antioxidant enzymes attenuates myocardial pathology and improves cardiac function.

Background —Atherosclerosis is characterized by an early inflammatory response involving proinflammatory mediators such as platelet-activating factor (PAF)-like phospholipids, which are inactivated by PAF-acetylhydrolase (PAF-AH). The effect of adenovirus-mediated expression of PAF-AH on injury-induced neointima formation and spontaneous atherosclerosis was studied in apolipoprotein E–deficient mice. Methods and Results —Intravenous administration of an adenovirus (5×10 ⁸ plaque-forming units) directing liver-specific expression of human PAF-AH resulted in a 3.5-fold increase of plasma PAF-AH activity at day 7 ( P <0.001); this was associated with a 2.4- and 2.3-fold decrease in malondialdehyde-modified LDL autoantibodies and the lysophosphatidylcholine/phosphatidylcholine ratio, respectively ( P <0.001 for both). Non-HDL and HDL cholesterol levels in PAF-AH –treated mice were similar to those of control virus-treated mice. Seven days after virus injection, endothelial denudation of the common left carotid artery was induced with a guidewire. Neointima formation was assessed 18 days later. PAF-AH gene transfer reduced oxidized lipoproteins by 82% ( P <0.001), macrophages by 69% ( P =0.006), and smooth muscle cells by 84% ( P =0.002) in the arterial wall. This resulted in a 77% reduction ( P <0.001) of neointimal area. Six weeks after adenovirus-mediated gene transfer, spontaneous atherosclerotic lesions in the aortic root were analyzed. PAF-AH gene transfer reduced atherosclerotic lesions by 42% ( P =0.02) in male mice, whereas a nonsignificant 14% reduction was observed in female mice. Basal and PAF-AH activity after gene transfer were higher in male mice than in female mice ( P =0.01 and P =0.04, respectively). Conclusions —Gene transfer of PAF-AH inhibited injury-induced neointima formation and spontaneous atherosclerosis in apolipoprotein E–deficient mice. Our data indicate that PAF-AH, by reducing oxidized lipoprotein accumulation, is a potent protective enzyme against atherosclerosis.

Macrophage infiltration into the subendothelial space at lesion prone sites is the primary event in atherogenesis. Inhibition of macrophage homing might therefore prevent atherosclerosis. Since HDL levels are inversely correlated with cardiovascular risk, their effect on macrophage homing was assessed in apoE‐deficient (apoE ^−/− ) mice. Overexpression of human apolipoprotein AI in apoE ^−/− mice increased HDL levels 3‐fold and reduced macrophage accumulation in an established assay of leukocyte homing to aortic root endothelium 3.2‐fold ( P < 0.005). This was due to reduced in vivo βVLDL oxidation, reduced βVLDL triggered endothelial cytosolic Ca ²⁺ signaling through PAF‐like bioactivity, lower ICAM‐1 and VCAM‐1 expression, and diminished ex vivo leukocyte adhesion. Adenoviral gene transfer of human PAF‐acetylhydrolase (PAF‐AH) in apoE ^−/− mice increased PAF‐AH activity 1.5‐fold ( P <0.001), reduced β VLDL‐induced ex vivo macrophage adhesion 3.5‐fold ( P <0.01), and reduced in vivo macrophage homing 2.6‐fold ( P <0.02). These inhibitory effects were observed in the absence of increased HDL cholesterol levels. In conclusion, HDL reduces macrophage homing to endothelium by reducing oxidative stress via its associated PAF‐AH activity. This protective mechanism is independent of the function of HDL as cholesterol acceptor. Modulation of lipoprotein oxidation by PAF‐AH may prevent leukocyte recruitment to the vessel wall, a key feature in atherogenesis.—Theilmeier, G., De Geest, B., Van Veldhoven, P. P., Stengel, D., Michiels, C., Lox, M., Landeloos, M., Chapman, M. J., Ninio, E., Collen, D., Himpens, B., Holvoet, P. HDL‐associated PAF‐AH reduces endothelial adhesiveness in apoE ^−/− mice. FASEB J. 14, 2032–2039 (2000)

For an electron microscopic study of the liver, expertise and complicated, time-consuming processing of hepatic tissues and cells is needed. The interpretation of electron microscopy (EM) images requires knowledge of the liver fine structure and experience with the numerous artifacts in fixation, embedding, sectioning, contrast staining and microscopic imaging. Hence, the aim of this paper is to present a detailed summary of different methods for the preparation of hepatic cells and tissue, for the purpose of preserving long-standing expertise and to encourage new investigators and clinicians to include EM studies of liver cells and tissue in their projects.