Elevated plasma lipid hydroperoxides in patients with coronary artery disease

Separation and characterization of oxidized isomeric lipid-peptide adducts by ion mobility mass spectrometry

Phospholipids are major components of cell membranes and lipoprotein complexes. They are prone to oxidation by endogenous and exogenous reactive oxygen species yielding a large variety of modified lipids including small aliphatic and phospholipid bound aldehydes and ketones. These carbonyls are strong electrophiles that can modify proteins and, thereby, alter their structures and functions triggering various pathophysiological conditions. The analysis of lipid-protein adducts by liquid chromatography-MS is challenged by their mixed chemical nature (polar peptide and hydrophobic lipid), low abundance in biological samples, and formation of multiple isomers. Thus, we investigated traveling wave ion mobility mass spectrometry (TWIMS) to analyze lipid-peptide adducts generated by incubating model peptides corresponding to the amphipathic β1 sheet sequence of apolipoprotein B-100 with 1-palmitoyl-2-(oxo-nonanoyl)-sn-glycerophosphatidylcholine (PONPC). The complex mixture of peptides, lipids, and peptide-lipid adducts was separated by TWIMS, which was especially important for the identification of two mono-PONPC-peptide isomers containing Schiff bases at different lysine residues. Moreover, TWIMS separated structural conformers of one peptide-lipid adduct possessing most likely different orientations of the hydrophobic sn-1 fatty acyl residue and head group of PONPC, relative to the peptide backbone.

Prenatal exposure to cigarette smoke induces diet- and sex-dependent dyslipidemia and weight gain in adult murine offspring

BACKGROUND

Cardiovascular disease (CVD) affects 71 million American adults and remains the leading cause of death in the United States and Europe. Despite studies that suggest that the development of CVD may be linked to intrauterine growth or early events in childhood, little direct experimental evidence supports the notion.

OBJECTIVE

We investigated whether exposure to cigarette smoke in utero alters the risk of developing CVD later in life.

METHODS

We exposed B(6)C(3)F(1) mice (via whole-body inhalation) to either filtered air or mainstream cigarette smoke (MCS, at a particle concentration of 15 mg/m(3)) from gestational day 4 to parturition. Adult offspring were fed a normal chow diet or switched to a high-fat diet 2 weeks before sacrifice. We measured dam and offspring body weight, plasma lipid parameters, lipoprotein subclass particle numbers and sizes, and total antioxidant capacities.

RESULTS

Adult female mice prenatally exposed to MCS demonstrated significantly higher body weight and levels of plasma high-density lipoprotein (HDL) and low-density lipoprotein than did their air-exposed counterparts. When fed a high-fat diet for 2 weeks, males, but not females, exposed prenatally to MCS gained substantially more weight and exhibited dramatic alterations in total cholesterol and HDL levels compared with their air-exposed counterparts.

CONCLUSIONS

These data provide, for the first time, direct experimental evidence supporting the notion that prenatal exposure to cigarette smoke affects offspring weight gain and induces a lipid profile that could alter the offspring's risk of developing CVD later in life.

Effects of oral contraception with ethinylestradiol and drospirenone on oxidative stress in women 18-35 years old

BACKGROUND

Oral contraceptives (OCs) with estrogens and progestins may affect oxidative stress (OS) status.

STUDY DESIGN

A group of 32 women using oral contraceptives (OCU) containing 0.03 mg ethinylestradiol and 3 mg drospirenone have been compared to a matched control group of 30 noncontraception users (NCU). Blood levels of antioxidants, trace elements and markers of lipid peroxidation were assessed by biochemical methods. A microarray analysis of whole blood mRNA levels of 200 genes involved in OS-dependant pathway was also performed.

RESULTS

Levels of zinc, vitamin E and antibodies to oxidized low-density lipoproteins (LDLs) were not significantly different between the two groups. On the other hand, significant increases in the mean levels of lipid peroxides (+176%, p<.001), oxidized LDLs (+145%, p<.002), copper (+103%, p<.001), Cu/Zn ratio (+100%, p<.001) and a significant decrease in the mean level of beta-carotene (-41%, p<.01) were observed in the OCU compared to NCU. There was a highly significant positive correlation between the lipid peroxide levels and the copper-to-zinc ratio. From the 200 genes tested by microarray, one coding for HSP70 was significantly up-regulated (log(2) fold change=+ 0.45, p<.02) and one coding for inducible nitric oxide synthase significantly down-regulated (log(2) fold change=-0.24, p<.05) in the OCU compared to the NCU.

CONCLUSIONS

The recently introduced combination of ethinylestradiol and drospirenone induced the heightening of lipid peroxidation correlated with high levels of copper, a situation that could be associated with increased cardiovascular risk.

Correlation between rises in Chlamydia pneumoniae-specific antibodies, platelet activation and lipid peroxidation after percutaneous coronary intervention

We recently showed that Chlamydia pneumoniae activates platelets in vitro, with an associated oxidation of low-density lipoproteins. The aim of this study was to investigate whether C. pneumoniae is released during percutaneous coronary intervention (PCI) and, thereby, causes platelet activation and lipid peroxidation. Seventy-three patients undergoing coronary angiography and following PCI or coronary artery bypass graft (CABG) and 57 controls were included in the study. C. pneumoniae antibodies, serotonin and lipid peroxidation were measured before and 24 h, 1 month and 6 months after angiography. The results show that serum C. pneumoniae IgA concentrations were significantly higher in patients than in the controls. Furthermore, in 38% of the C. pneumoniae IgG positive patients, the C. pneumoniae IgG concentration increased 1 month after PCI. The levels of C. pneumoniae IgG antibodies 1 month after PCI correlated with plasma-lipid peroxidation (r = 0.91, P < 0.0001) and platelet-derived serotonin (r = 0.62, P = 0.02). There was no elevation in the total serum IgG 1 month after PCI. In conclusion, the present results suggest that PCI treatment of coronary stenosis releases C. pneumoniae from the atherosclerotic lesions, which leads to platelet activation and lipid peroxidation.

Oxidative stress in young subjects with acute myocardial infarction: evaluation at the initial stage and after 12 months

In 105 subjects (97 men and 8 women) aged <46 years (mean age 39.6 +/- 5.5 years), with recent acute myocardial infarction (T1), thiobarbituric acid reactive substances and total antioxidant status were determined; NO production was evaluated by measuring the nitrite and nitrate (NOx) concentration. The patients with acute myocardial infarction were subdivided according to the main risk factors, number of risk factors, and extent of coronary lesions. The evaluation was repeated after 12 months (T2). In these subjects, thiobarbituric acid reactive substances and NOx were significantly increased and total antioxidant status was significantly decreased at T1. In single risk factor, only NO metabolites were significantly lower in acute myocardial infarction subjects who smoke than in subjects who do not. Subdividing the subjects according to the number of risk factors and number of stenosed coronary vessels, there were no significant differences between the subgroups. At T2, thiobarbituric acid reactive substances and NOx were decreased and total antioxidant status was increased, but all parameters were still altered.

Paraoxonase and arylesterase activities in patients with cardiac syndrome X, and their relationship with oxidative stress markers

OBJECTIVES

Paraoxonase-1 is a high-density lipoprotein-associated enzyme with three activities, which are paraoxonase, arylesterase and dyazoxonase. Paraoxonase-1 was shown to decrease in patients with cardiovascular diseases. We aimed to examine serum paraoxonase and arylesterase activities, and their relation with oxidative stress markers such as lipid hydroperoxide and total antioxidant status in patients with cardiac syndrome X.

METHODS

Forty-one consecutive patients with cardiac syndrome X (CSX group), 33 consecutive patients without cardiac syndrome X (non-cardiac syndrome X group) and 20 healthy volunteers as control group were taken into the study. Serum paraoxonase and arylesterase activities were measured spectrophotometrically. Lipid hydroperoxide levels were measured by ferrous oxidation with xylenol orange assay. Total antioxidant status was determined using an automated measurement method.

RESULTS

Basal paraoxonase, salt-stimulated paraoxonase and arylesterase activities were significantly lower in patients with cardiac syndrome X than those of the non-cardiac syndrome X and control groups (P<0.001, for both). Moreover, lipid hydroperoxide was found at high level, and total antioxidant status was found at low level in patients with cardiac syndrome X than control and non-cardiac syndrome X groups (P<0.001, for all). In patients with cardiac syndrome X, in multiple linear regression analysis, both paraoxonase and arylesterase activities were independently correlated with lipid hydroperoxide levels (P=0.001, P=0.003, respectively), and also arylesterase activity was independently correlated with magnitude of ST depression (P=0.002).

CONCLUSION

Reduced paraoxonase and arylesterase activities and total antioxidant status levels and enhanced lipid hydroperoxide levels in patients with cardiac syndrome X might indicate increased oxidative stress that can play a role in pathogenesis of cardiac syndrome X.

Lymphocyte DNA damage is associated with increased aortic intima-media thickness

OBJECTIVES

To investigate whether there is an association between lymphocyte DNA damage and aortic intima-media thickness (IMT).

METHODS

We studied 70 patients (mean age: 41.6+/-10 years) who underwent transesophageal echocardiography for various indications. Four different grades were determined according to intima-media thickness (IMT) of thoracic aorta measured by transesophageal echocardiography. DNA damage was assessed by alkaline single cell electrophoresis (comet) assay in peripheral lymphocytes. Plasma level of total antioxidant status (TAS) was determined by using automated measurement method. High sensitive C-reactive protein and other biochemical markers were studied in all subjects.

RESULTS

The major increase in lymphocyte DNA damage was observed in patients with grade 4 IMT when compared with other groups (p<0.001, for all). Lymphocyte DNA damage of patients with grade 1 IMT was also lower than patients with grade 2 IMT (p=0.013) and patients with grade 3 IMT (p<0.001). Lymphocyte DNA damage of patients with grade 2 IMT was found at low level compared with patients with grade 3 IMT (p=0.012) as well. In multiple linear regression analysis, IMT was independently correlated with lymphocyte DNA damage (beta=0.515, p<0.001), TAS level (beta=-420, p<0.001), total cholesterol (beta=0.407, p<0.001) and LDL cholesterol level (beta=287, p=0.020).

CONCLUSION

Lymphocyte DNA damage may be an independent predictor for the grade of thoracic IMT, and may play a role in pathogenesis of thoracic atherosclerosis besides TAS and cholesterol levels.

Divergent cyclooxygenase responses to fatty acid structure and peroxide level in fish and mammalian prostaglandin H synthases

Prostanoid synthesis in mammalian tissues is regulated at the level of prostaglandin H synthase (PGHS) cyclooxygenase catalysis by the availability and structure of substrate fatty acid and the availability of peroxide activator. Two major PGHS isoforms, with distinct pathophysiological functions and catalytic regulation, have been characterized in mammals; a functionally homologous PGHS isoform pair has been cloned from an evolutionarily distant vertebrate, brook trout. The cyclooxygenase activities of recombinant brook trout PGHS-1 and -2 were characterized to test the generality of mammalian regulatory paradigms for substrate specificity, peroxide activation, and product shifting by aspirin. Both trout cyclooxygenases had much more restrictive substrate specificities than their mammalian counterparts, with pronounced discrimination toward arachidonate (20:4n-6) and against eicosapentaenoate (20:5n-3) and docosahexaenoate (22:6n-3), the latter two prominent in trout tissue lipids. Aspirin treatment did not increase lipoxygenase-type catalysis by either trout enzyme. Both trout enzymes had higher requirements for peroxide activator than their mammalian counterparts, though the preferential peroxide activation of PGHS-2 over PGHS-1 seen in mammals was conserved in the fish enzymes. The divergence in cyclooxygenase characteristics between the trout and mammalian PGHS proteins may reflect accomodations to differences among vertebrates in tissue lipid composition and general redox state.

Increased plasma malondialdehyde and protein carbonyl levels and lymphocyte DNA damage in patients with angiographically defined coronary artery disease

We investigated the oxidative modifications of lipids, proteins and DNA, three potential molecular targets of oxidative stress, in 30 patients with angiographically defined coronary artery disease (CAD) and 30 healthy control subjects. In addition, we examined relationships between these oxidative modifications and the severity of vascular lesions in patients with CAD. Malondialdehyde (MDA) and protein carbonyl (PC) levels, as well as ferric reducing antioxidant power (FRAP), were measured in the plasma. DNA damage was evaluated as single strand breaks (SSBs), formamidopyrimidine glycosylase (Fpg) and endonuclease III (E-III)-sensitive sites by the comet assay in DNA isolated from lymphocytes. MDA and PC levels increased, but FRAP values decreased, in patients as compared to controls. However, these values did not vary with the number of affected coronary vessels and were not correlated with Duke score, a parameter of the severity of vascular lesions in patients with CAD. We also found that lymphocyte DNA damage (SSBs, Fpg and E-III sites) were increased in patients. Although there were no significant differences in SSBs values in patients grouped according to affected vessel number, Fpg and E-III sites increased. We also detected significant correlations between Duke scores and SSBs and Fpg sites. Serum cholesterol, triglyceride and LDL-cholesterol levels were found to increase, but HDL-cholesterol levels decreased in CAD patients, but these lipids were not correlated with Duke scores. The results of this study reinforce the presence of increased combined oxidative modifications in lipid, protein and DNA in patients with CAD. However, lymphocyte DNA damage seems to be a more reliable assay than MDA and PC determinations to detect the severity of vascular lesions in patients.

Chemical modification of proteins during peroxidation of phospholipids

Chemical modification of proteins by advanced glycation and lipoxidation end products is implicated in the pathogenesis of macrovascular disease in aging and diabetes. To identify biomarkers of the lipoxidative modification of protein, we studied the oxidation of phospholipids in the presence of the model protein RNase A and compared protein-bound products formed in these reactions with those formed during oxidation of plasma proteins. Metal-catalyzed oxidation of 1-palmitoyl-2-arachidonoyl-phosphatidylcholine or 1-palmitoyl-2-linoleoyl-phosphatidylcholine in the presence of RNase led to the loss of amino groups in RNase and the incorporation of phosphate, hexanoate, pentanedioate, nonanedioate, and palmitate into protein. Protein-bound palmitate and phosphate correlated strongly with one another, and protein-bound pentanedioate and nonanedioate, derived from arachidonate and linoleate, respectively, accounted for approximately 20% of the cross-linking of lipid phosphorus to protein. Similar results were obtained on oxidation of total plasma or isolated LDL. We conclude that alkanedioic acids are quantitatively important linkers of oxidized phospholipids to proteins and that measurement of protein-bound phosphate and long-chain fatty acids may be useful for assessing long-term lipid peroxidative damage to proteins in vivo. Analyses of plasma proteins from control and diabetic patients indicated significant increases in lipoxidative modification of protein in diabetic compared with control subjects.

Elevated plasma lipid peroxide levels in angina pectoris and myocardial infarction

BACKGROUND

The concept that oxidised low-density lipoprotein (LDL), not native LDL, plays a major role in atherogenesis is gaining support. Lipid hydroperoxides in plasma are carried almost exclusively in LDL and reflect oxidised LDL. Previously, elevated plasma lipid hydroperoxides were reported in coronary artery disease (CAD) patients following bypass surgery. To determine whether the increased lipid hydroperoxide was related to bypass or reflected ongoing atherosclerosis, plasma lipid hydroperoxide was measured in acute myocardial infarction (AMI) and stable angina.

METHODS

Patients with AMI (n=39) and stable angina (n=40) were compared with matched controls. Lipids and lipoproteins were selectively removed from plasma by absorption to Liposorb gel. Lipid hydroperoxide concentration in the gel was measured by a sensitive triiodide spectrophotometric technique.

RESULTS

Lipid hydroperoxide levels in AMI and stable angina were elevated (3.47+/-0.21 micromol/l, P<.001 and 3.76+/-0.24 micromol/l, P<.001) compared to controls (2.18+/-0.13 micromol/l). Previously, a concentration >3 mol/l was considered pathological. Using this criterion, we detected pathological lipid hydroperoxide concentrations in 10.3% of controls, 57.5% of AMI and 61.5% of angina patients.

CONCLUSION

Plasma lipid hydroperoxide levels are significantly elevated in AMI and angina. This is not attributable to previous cardiopulmonary bypass but to the presence of atherosclerotic disease and is likely to play a role in atherogenesis.

Effects of preventive group education on the resistance of LDL against oxidation and risk factors for coronary heart disease in bypass surgery patients

BACKGROUND

Comprehensive preventive education for heart patients is effective in reducing cardiac events. However, very demanding counselling protocols cannot easily be implemented as an integral part of clinical practice in hospitals.

AIM

To evaluate whether recurrent preventive group education for coronary artery bypass grafting patients affects the resistance of LDL against oxidation and the classical risk factors for coronary heart disease.

METHODS

A prospective, controlled study with one-year follow-up was carried out in Southern Finland. Coronary artery bypass patients were allocated late (> or = 18 months) after the operation in the intervention and control groups.

RESULTS

Seventy two patients (65 men and 7 women) completed the study. Twelve-hour group education on healthy life-style had a significant (25%, P = 0.01) but transient positive effect on the resistance of LDL against oxidation. There was a trend towards increased physical activity in the intervention group. The impact of education on patients' weight was also more consistent (1.2 kg at 12 months, P < 0.05), whereas long-term effects on fibrinogen and serum lipids were small.

CONCLUSIONS

Repeated group education applied as an economically feasible part of specialist care had only small positive effects on patients' risk factors. There was a significant, but transient, increase in the resistance of LDL against oxidation. However, effective lipid lowering drug treatment is indicated for most coronary artery bypass patients rather than repeated health education alone.

Lipid peroxidation may predict restenosis after coronary balloon angioplasty

The present study assessed whether lipid peroxidation in plasma might predict restenosis after coronary balloon angioplasty. A total of 87 patients, who had undergone successful coronary balloon angioplasty using standard techniques, were enrolled. Fasting blood samples before the intervention were measured for plasma levels of thiobarbituric acid reactive substances (TBARS, an indicator of lipid peroxidation). Angiography was carried out before and 15 min after angioplasty, and at follow-up (4 months after angioplasty), and evaluated using a quantitative approach. There were 23 patients with restenosis (group R) and 64 patients without restenosis (group N) after coronary balloon angioplasty. The plasma TBARS level (mean+/-SEM) of 4.3+/-0.1 micromol/L in group R was significantly higher than that of 3.2+/-0.1 micromol/L in group N (p<0.01). There were no significant differences in other parameters, including plasma lipid levels, between the 2 groups. The plasma level of TBARS positively correlated with lumen loss of the coronary artery at the time of follow-up angiography (r=0.57, p<0.01). Our results suggest that oxidative stress contributes to restenosis and indicate that an elevated plasma level of TBARS may be a reliable predictor of restenosis.

Fibrinogen is an efficient antioxidant

Fibrinogen has been included among the risk factors for vascular disease. Fibrinogen belongs with albumin, ceruloplasmin and transferrin to an acute phase protein group in the plasma. Albumin, ceruloplasmin and transferrin are already recognized as natural antioxidants. In the present study we used three different oxygen generating systems in order to test whether fibrinogen is able to act as an antioxidant in an in vitro system. We used 1) pyrogallol auto-oxidation, 2) the reaction catalysed by xanthine oxidase coupled with the reduction of ferricytochrome c and 3) chemiluminescence. We found that in a dose-dependent manner fibrinogen inhibited superoxide generation (pyrogallol and xanthine-xanthine oxidase reactions), ferrous ion oxidation and hydroxyl radical dependent degradation (of deoxyribose). Fibrinogen also inhibited LDL oxidation (copper and azo compound-induced), hydrogen peroxide oxidation and chemiluminescence produced by polymorphonuclear leukocytes. Fibrinogen, albumin, ceruloplasmin and transferrin act as a supplementary antioxidant defense mechanism against oxidative stress arising from inflammatory conditions.

An excess concentration of oxysterols in the plasma is cytotoxic to cultured endothelial cells

To test if there is an excess concentration of oxysterols in the plasma of the patients with cardiovascular disease, we analyzed the oxysterol content in the plasma from 105 cardiac catheterized patients with angina and 80+/-8% stenosis in their coronary arteries. The result showed that the plasma contained a significantly higher concentration of oxysterols than did plasma from 105 age- and sex-matched, non-catheterized and angina-free controls (P<0.05). We used endothelial cells (ECs) cultured in medium containing either [3H]thymidine, [3H]mevalonolactone or 45Ca(2+) to determine how the plasma from the patients influences cell growth and function. We found that less [3H]thymidine (P<0.05), less [3H]mevalonolactone (P<0.05) and more 45Ca(2+) (P<0.001) was incorporated into ECs cultured in the plasma from 36 patients with 83+/-4% stenosis than from the 36 controls. When synthetic 7beta-hydroxycholesterol, cholesterol 5beta,6beta-epoxide, cholesterol 5alpha,6alpha-epoxide and 7-ketocholesterol were added to the plasma from the controls, the influx of 45Ca(2+) into ECs then equaled that in the plasma of patients. The enhanced incorporation of 45Ca(2+) into the ECs cultured in the plasma both from the patients and from controls with added synthetic oxysterols substantiates in vitro the hypothesis that oxysterols increase the influx of calcium into cells. These data indicated that an excess of oxysterols in the plasma of the patients was cytotoxic to the cultured cells.

Large, sustained cardiac lipid peroxidation and reduced antioxidant capacity in the coronary circulation after brief episodes of myocardial ischemia

OBJECTIVES

We sought to investigate whether a brief episode of myocardial ischemia produces a detectable cardiac oxidative stress in patients undergoing elective coronary angioplasty (PTCA).

BACKGROUND

Although cardiac oxidative stress has been clearly demonstrated in experimental models of ischemia-reperfusion, its presence in patients after transient myocardial ischemia is still unclear.

METHODS

In order to evaluate oxidative stress in ischemic cardiac regions, plasma conjugated dienes (CD), lipid hydroperoxides (ROOHs) and total antioxidant capacity (TRAP), independent indexes of oxidative stress, were measured in the aorta and great cardiac vein (GCV) before (t0), 1, (t1), 5 (t5) and 15 min (t15) after first balloon inflation in 15 patients undergoing PTCA on left anterior descending coronary artery (Group 1); six patients with right coronary artery stenosis (Group 2), which is not drained by the GCV, were studied as controls.

RESULTS

In Group 1 at baseline, CD and ROOHs levels were higher in GCV than in aorta (p < 0.01 for both), and TRAP levels were lower (p < 0.01). Aortic levels of CD, ROOHs and TRAP did not change at any time after to; venous levels of CD and ROOHs levels markedly increased at t1, at t5 and remained elevated at t15 (p < 0.01 for all comparisons vs. to); venous levels of TRAP decreased at t1 and t5 (p < 0.01 vs. t0) and returned to normal at t15. In Group 2, CD, ROOHs and TRAP levels were similar in the aorta and GCV and did not change throughout the study.

CONCLUSIONS

Short episodes of myocardial ischemia during PTCA induce a sustained oxidative stress, which is detectable in the venous effluent of reperfused myocardium.

The relationship of oxidized lipids to coronary artery stenosis

A total of 1200 patients with angina were cardiac catheterized establishing that 63% had 70-100% stenosis, 12% had 10-69% stenosis of one or more of their coronary arteries and 25% had microvascular angina listed as 0% stenosis. Prior to catheterization 10 ml of blood was drawn and the plasma subjected to analysis for the concentration of cholesterol, lipid peroxides (LPX), total antioxidant capacity (TAOC), fibrinogen (FB), ceruloplasmin (CP) and activation of polymorphonuclear leukocytes (PMNLs). Comparisons were made to non-smoking controls without angina. Significant differences in LPX were found between the patients with 0 and 10-69% stenosis (P<0.001), with 10-69 and 70-100% stenosis (P<0.001), and with 0 and 70-100% stenosis (P<0.001). Under 70 years of age there was a significant difference in LPX between patients with all levels of stenosis and age and sex matched controls (P<0.001). Differences in the mean plasma cholesterol concentration for different levels in the degree of stenosis were not significant, indicating that LPX provided consistent data on the severity of stenosis while the plasma cholesterol concentration did not. Compared with controls an increase in activation of PMNLs (P<0.01), an increase in concentration of both FB and CP (P<0.01) and a decrease in total antioxidant capacity were noted in the plasma of catheterized patients. In summary the concentration of oxidation products rather than the concentration of cholesterol in the plasma identified stenosis in cardiac catheterized patients.

Studies of renal injury III: lipid-induced nephropathy in type II diabetes

Studies of renal injury III: Lipid-induced nephropathy in type II diabetes.

BACKGROUND

Nephrotoxicity from elevated circulating lipids occurs in experimental and clinical situations. We tested the hypothesis that lipid-induced nephropathy causes advanced renal failure in rats with type II diabetes and dyslipidemia.

METHODS

First generation (F1) hybrid rats derived from the spontaneous hypertensive heart failure rat (SHHF/Gmi-fa) and the LA/NIH-corpulent rat (LA/N-fa) were studied for 41 weeks while being on specific diets. Group 1 (14 rats) ingested 11.5% protein, 47.9% fat, and 40.6% carbohydrate. Group 2 (8 rats) ingested 26.9% protein, 16.7% animal fat, and 56.4% carbohydrate, and group 3 (20 rats) ingested 20.2% protein, 40.4% soy and coconut oil, and 39.4% carbohydrate.

RESULTS

Hyperglycemia was more severe in rat groups 1 and 2 than in group 3. In contrast, circulating cholesterol and hydroperoxide levels were highest in group 3, intermediate in group 2, and lowest in group 1. Group 3 had severe renal failure secondary to glomerulosclerosis and tubulointerstitial disease, with striking deposition of the lipid peroxidation stress biomarker 4-hydroxynonenal in glomeruli and renal microvessels. Moreover, in group 3, increased arterial wall thickness also connoted vascular injury. In contrast, the glycoxidation stress biomarkers pentosidine and carboxymethyl-lysine were preferentially localized to renal tubules of hyperglycemic rats in groups 1 and 2 and did not segregate with the most severe renal injury. Glomerular and interstitial fibrosis was accompanied by proportional increases in renal transforming growth factor-beta1 levels, which were threefold higher in the hypercholesterolemic rats of group 3 than in the hyperglycemic rats of group 1.

CONCLUSIONS

Acquisition of non-nodular glomerular sclerosis and tubulointerstitial disease is dependent on lipoxidation stress in rats with type II diabetes. On the other hand, in the absence of hypercholesterolemia, prolonged glycoxidation stress does not appear to be uniquely nephrotoxic.

Coronary artery surgery is associated with different forms of atherogenic lipoprotein modifications

BACKGROUND

Increasing evidence shows that thrombogenicity and atherogenicity of lipoproteins are related to modifications involving oxidative, enzymatic, or physical alterations of these molecules. Findings on lipid peroxidation associated with cardiopulmonary bypass are conflicting, and the possible other forms of atherogenic lipid modification are unknown. The various forms of lipoprotein modifications including lipid peroxidation, desialylation, and leukocytic elastase activity after coronary artery bypass graft operations are examined.

METHODS

In patients undergoing coronary artery bypass graft operations, plasma total lipid hydroperoxides (n = 102), plasma leukocytic elastase activity (n = 125), free radical formation (n = 30), low-density lipoprotein oxidation, and sialic acid content before operation and at 2, 24, 48, and 72 hours after cardiopulmonary bypass and 3 months after operation were measured.

RESULTS

Preoperative plasma lipid peroxide concentration (2.2 micromol/L) increased after cardiopulmonary bypass (peak, 7.5 micromol/L; p<0.001) and remained significantly elevated at 3 months after surgery (4.2 micromol/L; p<0.01). There was a significant correlation between increased free radical generation and lipid peroxide levels in blood at all postoperative intervals. Low-density lipoprotein separated from plasma samples showed increased oxidation 48 hours after bypass. Sialic acid content of low-density lipoprotein was significantly reduced 48 hours after bypass. Plasma elastase activity increased significantly at all postoperative intervals.

CONCLUSIONS

Coronary artery bypass graft operation is associated with generation of sustained blood levels of modified lipoproteins. These thrombogenic and atherogenic particles may play an important role in hemostatic and arteriosclerotic complications of coronary artery bypass graft operations.