Glucose fluctuation on the progression of diabetic macroangiopathy--new findings from monocyte adhesion to endothelial cells

The aim of this study was to elucidate the effect of repetitive fluctuations in blood glucose concentrations on monocyte adhesion to the aortic endothelium. Streptozotocin induced diabetes rats were fed twice daily to induce repetitive postprandial glucose spikes. Then, we compared the number of monocytes adherent to the endothelium of thoracic aorta in these rats with that in rats fed ad libitum. In addition, we evaluated the effect of N-acetyl-L cystein and probucol which are known as antioxidants on the monocyte adhesion to endothelial cells. Streptozotocin induced diabetes rats fed twice daily showed remarkably lower HbA(1c) than the rats fed ad libitum. However, the former group showed markedly higher number of monocytes adherent to the endothelium than the latter. Both N-acetyl-L cystein and probucol could not reduce the number of adherent monocytes in streptozotocin induced diabetes rats fed twice daily. Our data demonstrated that repetitive postprandial fluctuation in glucose concentration evokes monocyte adhesion to endothelial cells that was worse than that induced by stable hyperglycemia in vivo.     

Effects of dietary fish oil and butterfat on serum lipids and monocyte and platelet interactions with aortic endothelial cells

We studied effects of dietary lipids on some of the initial events in atherogenesis. Adult swine were fed low fat/low cholesterol diets, then challenged with a high cholesterol (1%, w/w) diet supplemented with 11.5% (w/w) butterfat (BF) or MaxEPA^TM fish oil (FO). Serum lipids and monocyte and platelet adhesion to porcine aortic endothelial cells in vitro were measured during feeding of the low fat diet and at 1, 2, and 5 weeks after the dietary challenge. Total cholesterol increased significantly in animals fed the BF and FO diets, but there was no difference between the groups. Animals fed FO had total cholesterol/high-density lipoprotein cholesterol values twice those fed BF ( ). After 2 weeks on the hypercholesterolemic diet, monocyte adhesion to endothelial cells increased in swine fed FO by 123% above those fed a low fat diet, and adhesion values remained elevated (56% above baseline value) after 5 weeks. Monocytes from swine fed BF showed increased adhesion by 87, 53, and 14% above those fed the low fat diet at 1, 2, and 5 weeks respectively. Platelet adhesion to endothelial cells decreased (P < 0.05) after diet change and remained low. Adhesion of platelets from swine fed FO was significantly lower than those fed BF at 1 and 2 weeks but higher at 5 weeks. The FO diet, compared to the BF diet, produced a more atherogenic cholesterol profile and greater monocyte adhesion to endothelial cells, conditions which in vivo may promote lesion initiation.     

Lipoxygenase products increase monocyte adhesion to human aortic endothelial cells

The development of atherosclerosis is accelerated in individuals with type 2 diabetes. Adhesion of monocytes to the vascular endothelium is a key initial step in atherogenesis. We have previously shown that monocyte adhesion to human aortic endothelial cells (HAECs) cultured long-term in high-glucose medium (25 mmol/L, 2 passages) is increased compared with cells grown in normal glucose (5 mmol/L). One potential mechanism for increased monocyte adhesion to HAECs under hyperglycemic conditions is via the 12-lipoxygenase (12-LO) pathway. In this study, we demonstrated in HAECs that the major LO metabolite of arachidonic acid was the 12-LO product, 12(S)-hydroxyeicosatetraenoic acid [12(S)-HETE], which was increased severalfold in HAECs cultured under high-glucose conditions. Furthermore, treatment of HAECs with 12(S)-HETE induced monocyte, but not neutrophil, adhesion an average of 3-fold (range of 1.5- to 5-fold) compared with untreated cells (75+/-5 versus 26+/-1 monocytes per field, respectively, P<0.001). Expression of the adhesion molecules vascular cell adhesion molecule-1, E-selectin, and intercellular adhesion molecule-1 was not significantly increased. However, both glucose and 12(S)-HETE induced a 60% increase in HAEC surface expression of connecting segment-1 (ie, CS-1) fibronectin, a ligand for very late-acting antigen-4 (VLA-4). The antibodies used to block monocyte integrin VLA-4 and leukocyte function-related antigen-1, a monocytic counterreceptor for intercellular adhesion molecule-1, inhibited the ability of both 12-LO products and high glucose to induce monocyte adhesion. These results definitively demonstrate for the first time in HAECs that the 12-LO pathway can induce monocyte-endothelial cell interaction and that the effects of glucose may be mediated, at least in part, through this pathway. Thus, these results suggest that the 12-LO pathway may play a role in the increased susceptibility of diabetics to atherosclerosis.     

Role of vascular cell adhesion molecule-1 and fibronectin connecting segment-1 in monocyte rolling and adhesion on early atherosclerotic lesions

Atherosclerotic lesion development seems to be inflammatory in nature and involves the recruitment of monocytes to the vessel wall. In this study, we investigated the role of vascular cell adhesion molecule-1 (VCAM-1) and fibronectin (FN) connecting segment-1 containing the amino acid sequence ILDV as functional ligands for alpha(4)beta(1) integrin (VLA-4) in monocyte rolling and adherence to early atherosclerotic lesions. Carotid arteries of apolipoprotein E-deficient mice were isolated and perfused with monocytes or U937 cells. Cell adhesion was reduced 95+/-4% by monoclonal antibodies HP1/2 and HP2/1, which block VLA-4 binding to both VCAM-1 and FN connecting segment-1. mAb HP1/3 preferentially blocked interaction of VLA-4 with FN but not VCAM-1 and decreased adhesion by 30+/-8%. In contrast, blocking VCAM-1 by perfusing the isolated carotid artery with mAb MK-2.7 reduced adhesion by 75+/-12%. Mononuclear cell adhesion to the early atherosclerotic endothelium was inhibited by 68+/-10% in the presence of EILDVPST but not in the presence of control peptide EIDVLPST. When VLA-4 or VCAM-1 was blocked, more mononuclear cells rolled on early lesions at significantly higher (approximately doubled) rolling velocities. These data demonstrate that (1) blockade of VCAM-1 can abrogate the majority (75+/-12%) of VLA-4-dependent monocyte adhesion on early atherosclerotic endothelia and (2) ILDV peptide interferes with VLA-4 binding to both VCAM-1 and FN and may be useful in limiting monocyte adhesion to atherosclerotic lesions.     

Oxidized cholesteryl linoleates stimulate endothelial cells to bind monocytes via the extracellular signal-regulated kinase 1/2 pathway

Oxidation products of cholesteryl esters have been shown to be present in oxidized low density lipoprotein and in atherosclerotic lesions. Monocyte adhesion to the endothelium is an initiating crucial event in atherogenesis. Here, we show that in vitro oxidized cholesteryl linoleate (oxCL) stimulated human umbilical vein endothelial cells (HUVECs) to bind human peripheral blood mononuclear cells as well as monocyte-like U937 cells but not peripheral blood neutrophils or neutrophil-like HL-60 cells. Among the oxidation products contained in oxCLs, 9-oxononanoyl cholesterol (9-ONC) and cholesteryl linoleate hydroperoxides stimulated U937 cell adhesion. OxCL-induced U937 cell adhesion was inhibited by an antibody against the connecting segment-1 region of fibronectin. Neither oxCL nor 9-ONC induced activation of the classical nuclear factor-kappaB pathway. In contrast, stimulation of HUVECs with oxCL resulted in phosphorylation of the extracellular signal-regulated kinase 1/2. Moreover, U937 cell adhesion induced by 9-ONC and oxCL was blocked by a mitogen-activated protein kinase/extracellular signal-regulated kinase inhibitor and a protein kinase C inhibitor. Taken together, oxCLs stimulate HUVECs to specifically bind monocytes, involving endothelial connecting segment-1 and the activation of a protein kinase C- and mitogen-activated protein kinase-dependent pathway. Thus, oxidized cholesteryl esters may play an important role as novel mediators in the initiation and progression of atherosclerosis.     

Vitamin E supplementation suppresses macrophage accumulation and endothelial cell expression of adhesion molecules in the aorta of hypercholesterolemic rabbits

Suppression of cell adhesion molecule expression and macrophage accumulation by the endothelium is believed to play an important role in preventing the development of atherosclerosis. Earlier, we have shown that in vitro supplementation of human aortic endothelial cells with Vitamin E dose-dependently reduced expression of adhesion molecules and monocyte adhesion. Here, we report the in vivo down-regulation of endothelial cell adhesion molecules expression and macrophage accumulation in the aortas of hypercholesterolemic rabbits supplemented with Vitamin E. To this end, New Zealand White rabbits were fed a semi-purified diet containing 30 (control) or 1000 IU/kg Vitamin E. After 4 weeks, both groups' diets were switched to an atherogenic diet (0.3% cholesterol, 9% hydrogenated coconut oil, and 1% corn oil) containing the respective levels of Vitamin E and fed for 2, 4, and 6 weeks. Vitamin E supplemented rabbits had significantly higher levels of Vitamin E in their plasma and aortas. Frozen aorta sections were fixed and stained by an avidin-biotin complex method using Rb2/3 and Rb1/9 monoclonal antibodies against rabbit ICAM-1 and VCAM-1, respectively, and with RAM-11 for macrophage and von Willebrand factor for endothelial cells, followed by staining with secondary antibodies and counterstaining and evaluation under the microscope. At 6 weeks on atherogenic diet treatment, a trend (P = 0.08) toward a lower score of ICAM-1 expression by endothelial cells was observed in the aorta of Vitamin E treated rabbits compared to the control. However, a decrease in the score of VCAM-1 expression by endothelial cells in Vitamin E treated rabbits did not reach to a statistical significance. At 4 and 6 weeks on atherogenic diet, Vitamin E supplementation also significantly (P = 0.003) inhibited the accumulation of macrophages in the aorta. These results support the concept that down-regulation of adhesion molecule expression and suppression of monocyte/macrophage activation by Vitamin E in vivo is one of the potential mechanisms by which Vitamin E may suppress the development of aortic lesions in a rabbit model of atherosclerosis.     

Membrane type 1-matrix metalloproteinase is involved in migration of human monocytes and is regulated through their interaction with fibronectin or endothelium

Membrane type 1-matrix metalloproteinase (MT1-MMP) is involved in endothelial and tumor-cell migration, but its putative role in leukocyte migration has not been characterized yet. Here, we demonstrate that anti-MT1-MMP monoclonal antibody (mAb) impaired monocyte chemotactic protein-1 (MCP-1)-stimulated monocyte migration on fibronectin (FN), vascular cell adhesion molecule-1 (VCAM-1), and intercellular adhesion molecule-1 (ICAM-1). In addition, monocyte transmigration through tumor necrosis factor-alpha (TNF-alpha)-activated endothelium is also inhibited by anti-MT1-MMP mAb. Therefore, regulation of MT1-MMP in human peripheral blood monocytes was investigated. First, MT1-MMP clustering was observed at motility-associated membrane protrusions of MCP-1-stimulated monocytes migrating on FN, VCAM-1, or ICAM-1 and at the leading edge, together with profilin, of monocytes transmigrating through activated endothelial cells. In addition, up-regulation of MT1-MMP expression was induced in human monocytes upon attachment to FN in a manner dependent on alpha4beta1 and alpha5beta1 integrins. Binding of monocytes to TNF-alpha-activated human endothelial cells as well as to VCAM-1 or ICAM-1 also resulted in an increase of MT1-MMP expression. These findings correlated with an enhancement of MT1-MMP fibrinolytic activity in monocytes bound to FN, VCAM-1, or ICAM-1. Our data show that MT1-MMP is required during human monocyte migration and endothelial transmigration and that MT1-MMP localization, expression, and activity are regulated in monocytes upon contact with FN or endothelial ligands, pointing to a key role of MT1-MMP in monocyte recruitment during inflammation.     

腺相关病毒介导血管抑素对血管内皮生长因子和细胞间黏附分子1表达的影响

目的探讨腺相关病毒介导血管抑素(rAAV-AS)基因对人脐静脉内皮细胞(HUVECs)血管内皮生长因子(VEGF)和细胞间黏附分子1(ICAM-1)表达的影响,以探讨rAAV-AS抗糖尿病动脉粥样硬化作用。方法选择体外培养的HUVECs传至第5代,随机分为6组:正常组、高糖组、高糖+rAAV-010~6 v.g./cell组、高糖+rAAV-AS10~4 v.g./cell组、高糖+rAAV-AS10~5 v.g./cell组、高糖+rAAV-AS10~6 v.g./cell组。分别检测rAAV-AS干预后24、48、72 h HUVECs凋亡及VEGF、ICAM-1的表达。结果与正常组比较,高糖组和高糖+rAAV-010~6 v.g./cell组不同时间HUVECs增殖明显,VEGF和ICAM-1表达明显升高(P<0.05);与高糖组比较,高糖+rAAV-AS10~4 v.g./cell组、高糖+rAAV-AS10~ 5v.g./cell组、高糖+rAAV-AS10~6 V.g./cell组增殖明显降低,VEGF和ICAM-1表达明显降低,并呈剂量依赖性(P<0.05)。结论 rAAV-AS对糖尿病大血管病变具有保护作用,其可能机制为下调内皮细胞中VEGF和ICAM-1的表达,从而减少内皮细胞增殖,抑制炎性反应。     

一次性大剂量辅酶A对餐后高甘油三酯血症的影响

目的餐后高甘油三酯血症是冠心病和动脉粥样硬化的独立危险因素。本研究旨在观察一次性口服或静滴辅酶A 1000单位对空腹高甘油三酯血症患者的餐后甘油三酯水平的影响。方法经过饮食宣教后,20例患者和10例正常人进行基线高脂餐试验,采集餐前、餐后2、4、6 h的静脉血标本。20例患者分别随机分入辅酶A胶囊组和辅酶A针剂组,于第2天分别于餐前30 m in口服辅酶A胶囊1000单位或高脂餐后,立即用500 mL生理盐水注射液溶解1000单位辅酶A针剂后静脉滴注,1 h内滴完。再次采集餐前、餐后2、4、6 h的静脉血标本。检测血脂水平,并且计算餐后2、4、6 h各时间点甘油三酯水平升高的程度。结果正常人仅餐后2 h血清甘油三酯水平显著升高(P<0.05),患者的餐后2、4、6 h血清甘油三酯水平显著高于其空腹水平(P<0.05),餐后4 h达到顶峰。正常人和患者的餐后各时间点血清总胆固醇、高密度脂蛋白胆固醇、低密度脂蛋白胆固醇水平与各自空腹状态相比均无显著差异。将胶囊组患者与针剂组患者合并进行统计(n=20),结果发现:经辅酶A治疗后,餐后6 h血清甘油三酯水平升高程度显著低于基线(62.4%±13.1%比42.1%±9...     

Intercellular adhesion molecule-1 (ICAM-1) expression is necessary for monocyte adhesion to the placental bed endothelium and is increased in type 1 diabetic human pregnancy

BACKGROUND: That adhesion molecule expression is upregulated in endothelial cells of the placental bed in pregnancies complicated by type 1 diabetes mellitus, and that this is associated with increased adherence of peripheral blood monocytes, which can be reversed by reduction in activity or expression of relevant adhesion molecules. Specific aims were to compare the adherence of monocytes from normal pregnancies to decidual endothelial cells from both normal and diabetic pregnancies, and to examine the involvement of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) in regulation of such adhesion. METHODS: We examined adhesion of peripheral blood monocytes (isolated by density gradient centrifugation) of normal third trimester pregnant women, to cultured endothelial cells (isolated from decidual biopsies collected at elective caesarean section) from both normal women and those with type 1 diabetes. Adhesion molecule expression was determined by flow cytometry. The role of ICAM-1 was further investigated by monoclonal antibody-blocking experiments and gene-silencing methodology. RESULTS: There was a significant increase in monocyte adhesion to decidual endothelial cells from diabetic pregnancies, associated with increased endothelial cell expression of ICAM-1, but not VCAM-1. ICAM-1 expression in normal decidual endothelial cells was stimulated by pro-atherogenic and pro-inflammatory stimuli. Following ICAM-1 antibody blockade, monocyte adhesion was decreased by > 70%. ICAM-1 silencing by small interfering RNAs also inhibited monocyte adhesion and ICAM-1 expression. CONCLUSIONS: These findings implicate upregulation of ICAM-1 in decidual endothelial cells in the development of placental bed vascular pathology in diabetic pregnancy.     

Long-term consumption of Western diet contributes to endothelial dysfunction and aortic remodeling in rats: Implication of Rho-kinase signaling

Western diet (WD), rich in saturated fat and sugars, has become a risk factor for obesity and metabolic syndrome, however, its effect on endothelial function and vascular remodeling is not fully elucidated. Recent evidence suggests cross-talk between Rho kinase (ROCK) pathway and cardiovascular system. We aimed to investigate the effect of WD on aortic remodeling and the contribution of ROCK signaling. Eight week old male Sprague-Dawley rats were fed either standard chow diet (SD) or high fructose/ high-fat diet, typically as in WD. After 42 weeks, WD-fed rats showed hyperglycemia, dyslipidemia, and hypertension without marked weight gain, compared to SD-fed rats. Significant up-regulation of ROCK-1 and ?2, along with a decline in eNOS expression were found in the aortic tissue of WD-fed rats. Additionally, WD-fed rats displayed oxidative stress and fibrosis in their aortic tissues versus controls. Our findings suggest that long-term feeding of WD contributes to endothelial dysfunction and aortic remodeling in adult male rats. ROCK activation seems to be involved in WD-related vascular disorders and may represent a promising therapeutic target.     

Secretory products from human adipocytes impair endothelial function via nuclear factor kappaB

Hyperplasia and hypertrophy of fat cells can be found in obesity, and increased adiposity is associated with endothelial dysfunction as an early event of atherosclerosis. However, it is unclear whether human adipocytes directly influence endothelial function. To study the crosstalk between fat and endothelial cells, human umbilical venous endothelial cells (HUVECs), and human coronary artery endothelial cells (HCAECs) were cultured in infranatants (Adipo) of primary differentiated human adipocytes. Interestingly, incubation of HUVECs and HCAECs with Adipo significantly increased monocyte adhesion 7.3 and 2.2-fold, respectively. VCAM-1, ICAM-1, and E-selectin in HUVECs were upregulated 3.9, 3.0, and 9.5-fold, respectively, under these conditions. Furthermore, Adipo significantly stimulated NFkappaB activity 1.9-fold. The NFkappaB inhibitor MG-132 and heat inactivation significantly reversed Adipo-stimulated monocyte adhesion. TNFalpha-neutralizing antibodies partly reversed Adipo-induced monocyte adhesion. In contrast, thiazolidinedione-pretreatment of human adipocytes did not alter the effects of Adipo. Adipo did not show cytotoxic effects. Taken together, we demonstrate that endothelial dysfunction is induced by adipocyte-secreted factors via NFkappaB partly dependent on TNFalpha.     

大豆异黄酮对大鼠实验性粥样硬化动脉壁内粘附分子基因表达的影响

为研究大豆异黄酮在动脉粥样硬化发生过程中与细胞间粘附分子1和血管细胞粘附分子1基因表达之间的关系。将60只大鼠按总胆固醇含量随机分为6组，分别喂饲基础饲料、高脂饲料、高脂饲料加不同剂量大豆异黄酮和高脂饲料加设雌激素。20周后处死动脉，光学显微镜检测HE染色的主动脉壁横切面病理改变，免疫组织化学和Western-blot法检测血管壁内细胞间粘附分子1和血管细胞粘附分子1蛋白，并运行计算机图像分析系统进行组间分析比较。结果发现，大鼠主动脉粥样斑块中，细胞间粘附分子1和血管细胞粘附分子1基因表达明显增加，大豆异黄酮可以减轻高脂饲料诱导的主动脉病理变化，减弱细胞间粘附分子1和血管细胞粘附分子1基因在主动脉内的表达。此结果提示，大豆异黄酮具有抗动脉粥样硬化形成作用，此作者可能是通过减弱粘附分子在主动脉壁的表达来实现。     

3-deazaadenosine prevents adhesion molecule expression and atherosclerotic lesion formation in the aortas of C57BL/6J mice

Adhesion molecules such as vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) play an important role during the development of atherosclerosis. 3-Deazaadenosine (c(3)Ado), an adenosine analogue, inhibits endothelial-leukocyte adhesion and ICAM-1-expression in vitro. We hypothesized that c(3)Ado is able to prevent the expression of adhesion molecules and atherosclerotic lesion formation in female C57BL/6J mice. The animals were placed on an atherogenic diet with or without c(3)Ado for 9 weeks. Frozen cross sections of the proximal ascending aorta just beyond the aortic sinus were stained with oil red O, hematoxylin, and elastic van Gieson's stains and were analyzed by computer-aided planimetry for fatty plaque formation and neointimal proliferation. Monoclonal antibodies against CD11b (macrophages), VCAM-1, and ICAM-1 were used for immunohistochemistry. Mice on the atherogenic diet demonstrated multiple (5.4+/-1.6 per animal) lesions covering 3.4+/-2.8% of the endothelium and a marked neointima when compared with control mice (4501+/-775 versus 160+/-38 microm(2), P<0.001). Mice on the cholesterol-rich diet without c(3)Ado showed strong endothelial coexpression of ICAM-1 and VCAM-1. Moreover, there was a 10-fold increase in monocyte accumulation on the endothelial surface (33. 3+/-4.9 versus 3.8+/-1.2, P<0.004). In contrast, in mice treated with c(3)Ado, expression of ICAM-1 and VCAM-1 as well as monocyte adhesion and infiltration were almost completely inhibited. Furthermore, these mice did not show any fatty streak formation or neointima formation (125+/-32 microm(2)). Our results demonstrate that c(3)Ado can inhibit diet-induced fatty streak formation and the expression of endothelial ICAM-1 and VCAM-1 in C57BL/6J mice. This may provide a novel pharmacological approach in the prevention and treatment of atherosclerosis.     

High-monounsaturated fat, olive oil-rich diet has effects similar to a high-carbohydrate diet on fasting and postprandial state and metabolic profiles of patients with type 2 diabetes

Whether metabolic control in type 2 diabetes mellitus (DM) is best achieved with the traditional high-carbohydrate (CHO), low-fat diet or a low-CHO, high-fat diet is still controversial. In a randomized crossover study, we compared the effects of a low-fat (30% of daily energy) diet and a high-fat (40% of daily energy), high-monounsaturated-fat diet for 6 weeks each on fasting and postprandial glucose, insulin, and lipoprotein concentrations in 12 patients with well-controlled type 2 DM (fasting blood glucose, 176 +/- 54 mg/dL; hemoglobin A1c, 6.4% +/- 0.7%) and no overt dyslipidemia (serum total cholesterol, 235 +/- 43 mg/dL; triglycerides, 180 +/- 63 mg/dL). Home-prepared foods were used and olive oil was the main edible fat, accounting for 8% and 25% of daily energy requirements in the low-fat and high-fat diets, respectively. For postprandial studies, the same mixed meal containing 36% fat was used in both dietary periods. Body weight and fasting and 6-hour postprandial blood glucose, insulin, and lipoprotein levels were similar after the two diets. The mean incremental area under the curve of serum triglycerides 0 to 6 hours after the challenge meal, adjusted for baseline levels, did not change significantly after the high-fat diet compared with the low-fat diet (1,484 +/- 546 v 1,714 +/- 709 mg x 6 h/dL, respectively, P = .099). Mean postprandial triglyceride levels at 6 hours were increased about 2 times over fasting levels and were still greater than 300 mg/dL after either diet. A diet high in total and monounsaturated fat at the expense of olive oil is a good alternative diet to the traditional low-fat diet for patients with type 2 DM. However, ongoing postprandial hypertriglyceridemia with either diet points to the need for other therapies to decrease triglyceride-rich lipoproteins (TRL) and the inherent atherogenic risk in type 2 diabetics.     

Effects of introducing physical training in the course of a 16-week high-fat diet regimen on hepatic steatosis, adipose tissue fat accumulation, and plasma lipid profile

OBJECTIVE: We recently reported that an 8-week high-fat diet-induced hepatic steatosis was completely prevented if an exercise training programme was introduced and pursued concurrently with the diet. The purpose of the present study was to determine the extent to which introducing exercise training at mid-point in the course of a 16-week high-fat diet regimen contributes to the reversal of liver lipid infiltration and the reduction of blood lipid profile deterioration and body fat accumulation. DESIGN AND SUBJECTS: Two groups of rats were fed a high-fat diet (42% kcal) for 16 weeks, one remaining sedentary during this entire period (HF-Sed) and the other being exercise trained for the last 8 weeks (HF-Tr). A third group was fed a standard diet and remained sedentary for all 16 weeks (SD-Sed). Training (5 days/week for 8 weeks) began 8 weeks after introducing the high-fat diet and consisted of treadmill running that was progressively increased to reach 60 min at 26 m/min, 10% grade, for the last 4 weeks. MEASUREMENTS: Various parameters including liver lipid infiltration, fat depots and blood lipids. RESULTS: Unexpectedly, liver lipid infiltration was not significantly higher in HF-Sed than in SD-Sed rats (means+/-s.e.: 14.9+/-1.7 vs 12.3+/-0.4 mg/g; P>0.05). High-fat compared to age-matched standard fed rats also showed an absence of difference (P>0.05) in the weight of total visceral fat pads (13%), plasma nonesterified fatty acids (NEFA), and leptin concentrations, but depicted significantly (P<0.01) higher values for subcutaneous fat pad weight and plasma triacyglycerol. Exercise training largely decreased visceral and subcutaneous fat accumulation by 30 and 26%, respectively (P<0.01) as well as NEFA, triacylglycerol, and leptin concentrations (P<0.01). CONCLUSION: Liver lipid infiltration does not seem to progress linearly over 16 weeks of high-fat feeding in light of what has previously been observed after 8 weeks of high-fat feeding. Introducing a training programme in the course of a 16-week high-fat diet protocol reduced adiposity, plasma NEFA, and leptin concentrations below the levels observed in standard fed rats. These data indicate that, exercise training, whether conducted concurrently or introduced during the course of a high-fat diet, is an asset to reduce the deleterious effects of a high-fat diet.     

Postprandial endothelial activation in healthy subjects and in type 2 diabetic patients: role of fat and carbohydrate meals

OBJECTIVES: To compare the effect of a high-fat meal and a high-carbohydrate meal (pizza), with and without antioxidant vitamins, on endothelial activation in healthy subjects and in patients with type 2 diabetes mellitus. BACKGROUND: The postprandial state is becoming increasingly acknowledged to affect some early events of atherogenesis. METHODS: In a randomized, observer-blinded, crossover study, 20 newly diagnosed type 2 diabetic patients and 20 age- and gender-matched healthy subjects received two meals at one-week intervals: a high-fat meal (760 calories) and an isoenergetic high-carbohydrate meal (non-cheese pizza). In all subjects, the same meals were repeated immediately following ingestion of vitamin E, 800 IU, and ascorbic acid, 1,000 mg. RESULTS: In normal subjects, the high-fat meal increased the plasma levels of tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1), which were prevented by vitamins. No change in these parameters occurred after pizza ingestion or pizza ingestion with vitamins. In diabetic patients, basal concentrations of glucose, cytokines and adhesion molecules were significantly higher than in nondiabetic controls. Both meals significantly increased cytokine and adhesion molecule levels, but the increase was more sustained following the high-fat meal. There was no significant change from baseline when vitamin supplementation accompanied each meal. There was a relationship between changes in serum triglycerides and changes in TNF-alpha (r = 0.39, p < 0.01), IL-6 (r = 0.28, p < 0.05) and VCAM-1 (r = 0.25, p < 0.05), and between changes in plasma glucose and changes in IL-6 (r = 0.36, p < 0.01) and ICAM-1 (r = 0.31, p < 0.02). CONCLUSIONS: An oxidative mechanism mediates endothelial activation induced by post-meal hyperlipidemia and hyperglycemia.