Serum total 8-iso-prostaglandin F2α: A new and independent predictor of peripheral arterial disease

Oxidative damage in the gastrocnemius predicts long-term survival in patients with peripheral artery disease

Patients with peripheral artery disease (PAD) have increased mortality rates and a myopathy in their affected legs which is characterized by increased oxidative damage, reduced antioxidant enzymatic activity and defective mitochondrial bioenergetics. This study evaluated the hypothesis that increased levels of oxidative damage in gastrocnemius biopsies from patients with PAD predict long-term mortality rates. Oxidative damage was quantified as carbonyl adducts in myofibers of the gastrocnemius of PAD patients. The oxidative stress data were grouped into tertiles and the 5-year, all-cause mortality for each tertile was determined by Kaplan-Meier curves and compared by the Modified Peto test. A Cox-regression model was used to control the effects of clinical characteristics. Results were adjusted for age, sex, race, body mass index, ankle-brachial index, smoking, physical activity, and comorbidities. Of the 240 study participants, 99 died during a mean follow up of 37.8 months. Patients in the highest tertile of oxidative damage demonstrated the highest 5-year mortality rate. The mortality hazard ratios (HR) from the Cox analysis were statistically significant for oxidative damage (lowest vs middle tertile; HR = 6.33; p = 0.0001 and lowest vs highest; HR = 8.37; p < 0.0001). Survival analysis of a contemporaneous population of PAD patients identifies abundance of carbonyl adducts in myofibers of their gastrocnemius as a predictor of mortality rate independently of ankle-brachial index, disease stage and other clinical and myopathy-related covariates.

The Effect of a Six-Week Nordic Walking Training Cycle on Oxidative Damage of Macromolecules and Iron Metabolism in Older Patients with Multiple Myeloma in Remission-Randomized Clinical Trial

Multiple myeloma (MM) is an incurable hematologic malignancy originating from clonal plasma cell proliferation within the bone marrow, predominantly affecting older individuals. While anemia serves as a diagnostic criterion for MM, it often ameliorates upon achieving disease remission. Iron metabolism parameters have emerged as potential prognostic indicators in MM. Notably, physical exercise has been established to influence iron metabolism. This study aimed to assess alterations in serum iron, ferritin, and transferrin concentrations, as well as leukocyte gene expression, in MM patients undergoing a six-week cycle of Nordic walking training. Thirty patients divided into an exercise group (NW, n = 15, mean age 63.1 ± 8.4 years) and a control group (CG, n = 15, mean age: 63.5 ± 3.6 years) completed the study protocol. Blood samples were collected at baseline, after three and six weeks of training, and after nine weeks. Serum ferritin, transferrin, and iron concentrations were measured, along with the leukocyte expression of genes. Additionally, serum oxidative damage marker levels were determined. Following the Nordic walking training cycle, a declining trend in serum ferritin concentrations was observed. Intracellular mRNA levels of genes associated with iron metabolism were positively influenced by the training regimen, indicating the potential impact of this physical activity on gene expression and ferritin concentrations. Although positive trends were noted, extended training periods might be requisite for significant changes. To conclude, moderate-intensity exercise induces favorable shifts in the analyzed parameters among MM patients, potentially influencing disease progression. Consequently, Nordic walking training is a safe recommendation for MM patients, though sustained training beyond six weeks could be necessary for notable effects on iron metabolism factors.

Validating fatty acid binding protein 3 as a diagnostic and prognostic biomarker for peripheral arterial disease: A three-year prospective follow-up study

BACKGROUND

Patients with peripheral arterial disease (PAD) often remain undiagnosed and therefore suboptimally managed. Here, we investigated the diagnostic and prognostic potential of fatty acid binding protein 3 (FABP3) in patients with PAD.

METHODS

In the discovery phase, 374 PAD and 184 non-PAD patients were recruited from vascular surgery ambulatory clinics at St. Michael's Hospital (Toronto, Ontario, Canada) between October 4, 2017 to October 29, 2018. The diagnostic ability of baseline FABP3 level was investigated through receiver operator characteristic (ROC) curves to determine two cutoff points: 1) an exclusionary "rule out" cutoff point, and 2) a confirmatory "rule in" cutoff point. Next, these cutoff points were confirmed in the external validation phase using a separate cohort of 312 patients (180 PAD and 132 non-PAD) recruited from ambulatory vascular surgery clinics at St. Michael's Hospital (Canada) between November 6, 2018-July 30, 2019. Cox regression analyses were used to explore the independent association between FABP3 and major adverse limb events (MALE - defined as need for arterial revascularization or major amputation) and decrease in ankle-brachial index (ABI -defined as drop ≥0.15) during 3 years of follow-up.

FINDINGS

In the discovery phase, FABP3 levels were significantly elevated in patients with PAD compared to non-PAD patients. ROC analysis demonstrated that FABP3 had an AUC of 0.83 (95% CI: 0.81-0.86, p-value < 0.001). FABP3 exclusionary cutoff was <1.55 ng/ml (sensitivity = 96%; specificity = 40%), whereas FABP3 confirmatory cutoff was >3.55 ng/ml (sensitivity = 43%; specificity = 95%) - values that were confirmed in the external validation phase. Cox regression analysis demonstrated FABP3 to be an independent predictor of increase in MALE [HR = 1.14 (1.03-1.29); p-value = 0.010] and worsening PAD status (drop in ABI >0.15 [HR = 1.11 (1.02-1.19); p-value = 0.009]).

INTERPRETATION

Our findings suggested that FABP3 levels can be used as both a diagnostic and prognostic biomarker for PAD, and may facilitate risk stratification in select individuals for purposes of vascular evaluation or intensive medical management.

FUNDING

Funding for this study was provided by the Bill and Vicky Blair Foundation.

Oxidative balance score reflects vascular endothelial function of Chinese community dwellers

Background: The oxidative balance score (OBS) is a composite estimate of the overall pro- and antioxidant risk status in an individual. The aim of this study is to explore the association between the OBS and vascular endothelial function in Chinese community dwellers. Methods: In total, 339 community dwelling adults (aged 20-75 years) were recruited in this study. The overall OBS was calculated on the basis of 16 pro- and antioxidant factors related to diet (measured by fasting blood samples) and lifestyle (evaluated by questionnaires). The dietary OBS and lifestyle OBS were calculated on the basis of the corresponding components. Serum iso-prostaglandin F2α (FIP) was measured to evaluate the oxidative stress degree, and brachial artery blood flow-mediated dilation (FMD) was measured for vascular endothelial function. The FIP and FMD levels were dichotomized as "low" or "high" using the corresponding median values (low FIP, n = 159; high FIP, n = 180; low FMD, n = 192; and high FMD, n = 147). The components of the OBS were compared between the stratified FIP and FMD groups. Logistic regression was used to analyze the OBS associations with FIP and FMD. Results: The higher overall OBS and dietary OBS were associated with lower FIP (p < 0.001), whereas the higher overall OBS (p < 0.01) and dietary OBS (p < 0.05) were associated with higher FMD. The lifestyle OBS was not associated with FIP and FMD (p > 0.05). Except for the body mass index (BMI) and low physical activity, all other OBS components were significantly different between the low FIP and high FIP groups (p < 0.05). Four diet-related antioxidants (α-carotene, zeaxanthin, α-tocopherol, and γ-tocopherol) showed significant differences between the high and low FMD groups (p < 0.05). Conclusion: The decreasing OBS level was associated with low endothelial function and high oxidative stress. The dietary OBS, rather than the lifestyle OBS, was more closely associated with endothelial function.

Relationship between serum homocysteine, fibrinogen, lipoprotein-a level, and peripheral arterial disease: a dose-response meta-analysis

AIM

At present, the relationship between serum homocysteine (Hcy), fibrinogen (FIB), lipoprotein-a (LPa), and PAD is uncertain, and there has been no meta-analysis to establish the dose-response relationship between their exposure levels and PAD.

METHODS AND RESULTS

Relevant literature published in PubMed, Embase, and Web of Science was retrieved. The robust error meta-regression method was used to assess the linear and non-linear dose-response relationship between exposure level and PAD risk. A total of 68 articles, involving 565,209 participants, were included. Combined with continuous variables, the serum Hcy, FIB, and LPa levels of PAD patients were significantly higher than those of healthy individuals. The odds ratios (ORs) of PAD for individuals with high Hcy, FIB, and LPa levels compared with those with low levels were 1.47, 1.14, and 1.76, respectively. The study also showed that circulating Hcy, FIB, and LPa were significantly elevated in patients with PAD compared with controls. The level of Hcy and the risk of PAD presented a U-shaped distribution. The nonlinear dose-response model showed that each 1 μmol/L increase in serum Hcy increased the risk of PAD by 7%. Similarly, for each 10 mg/dL FIB and 10 mg/dL LPa increases, the risk of PAD increased by 3% and 6%, respectively.

CONCLUSIONS

This meta-analysis provided evidence that elevated Hcy, PIB, and LPa levels may increase the risk of PAD, and the risk of PAD increases with the increase in serum exposure within a certain range. By controlling Hcy level, the incidence of PAD may be reduced to control the PAD growing epidemic.

TRIAL REGISTRATION NUMBER

PROSPERO (CRD42021250501), https://www.crd.york.ac.uk/prospero/.

Antiphospholipid antibodies and lower extremity peripheral artery disease: A systematic review and meta-analysis

AIM

To evaluate the clinical relevance of antiphospholipid antibodies (aPL) in patients with lower extremity peripheral artery disease (PAD).

DATA SOURCES

EMBASE and MEDLINE databases were searched from inception to March 2020 for clinical studies reporting on the association between of aPL [IgG/IgM anticardiolipin (aCL) and lupus anticoagulant (LA)] and PAD.

METHODS

We determined the pooled prevalence (PP) of patients positive for aPL in PAD or the PP of PAD in patients positive for aPL; we employed Peto's odds ratio with random effect for the meta-analysis.

RESULTS

Twenty-one studies comprising 6,057 patients were evaluated: in patients with PAD, the PP of IgG aCL was 12% vs 4.1% in those without, IgM aCL was 13.2% vs 2.1%, and LA 13.3% vs 3.3%, respectively. The PP of patients with LA was greater in critical limb ischemia than in the control group (19.3% vs 4.2%). Also, the PP of patients with LA was greater in the failed than in the successful revascularisation group (35.8% vs 15.8%). The PP of post-procedural revascularisation failures was similar in the groups given or not given oral anticoagulation (59.2% vs 61.9%).

CONCLUSION

All the aPL related to PAD regardless of diagnostic definition used, whereas LA related also to critical limb ischaemia and failed revascularisation. Data expressed as percentage of participants positive for aPL limit the interpretation of these relationships.

Evaluation of oxidative stress and the microenvironment in oral submucous fibrosis

BACKGROUND

Oral Submucous fibrosis (OSF) is a chronic inflammatory mucosal disease of unknown etiology. Statistics show cases of OSF which has a high rate of overall prevalence and increase the chance of malignant transformation. As we know malignant cells is situated in a very complex microenvironment with altered metabolic pathway including intermediates which participate in oxidative stress process which enhances metabolic rewiring and promotes tumor progression. This study aims to evaluate the tumor microenvironment and their role in metabolic reprogramming.

METHODS

This study was conducted on the serum sample of OSF (n = 20) compared to the healthy group (n = 20) using ELISA. The serum levels of intermediate by-products of metabolic pathway and oxidative stress induced biomolecular damage products were determined. The sensitivity of results was analyzed by correlating it with markers of metabolic status (Glucose, Total cholesterol, Total protein).

RESULTS

Metabolic pathway intermediates molecules like Fatty Acids (FAA), Ascorbic acid, Citrate, Oxaloacetate (OAA), levels were significantly high in the serum of OSF cases. This indicated that intermediates act as a metabolic switch that drives cells to adapt malignant transformation pathway. Markers related to oxidative DNA damage (8-hydroxy-2' -deoxyguanosine), Oxidative lipid peroxidation (8-epi-Prostaglandin F2α), and Protein carbonyl were significantly up-regulated. This significant increase in oxidative stress marker revealed the reprogramming of the metabolic pathway for fulfilling the nutritional requirement of cancer cells. A further significant correlation was observed with metabolic products confirmed altered metabolic status.

CONCLUSION

Our findings could identify the differentiating intermediate pathway metabolites and oxidative damage to biomolecules that are leading to rewiring of metabolism in the OSF group. Findings described in the study can be helpful to explain further the molecular aspects that lead to the progression of OSF towards carcinogenesis.

Biomarkers and Genetics in Peripheral Artery Disease

BACKGROUND

Peripheral artery disease (PAD) is highly prevalent and there is considerable diversity in the initial clinical manifestation and disease progression among individuals. Currently, there is no ideal biomarker to screen for PAD, to risk stratify patients with PAD, or to monitor therapeutic response to revascularization procedures. Advances in human genetics have markedly enhanced the ability to develop novel diagnostic and therapeutic approaches across a host of human diseases, but such developments in the field of PAD are lagging.

CONTENT

In this article, we will discuss the epidemiology, traditional risk factors for, and clinical presentations of PAD. We will discuss the possible role of genetic factors and gene-environment interactions in the development and/or progression of PAD. We will further explore future avenues through which genetic advances can be used to better our understanding of the pathophysiology of PAD and potentially find newer therapeutic targets. We will discuss the potential role of biomarkers in identifying patients at risk for PAD and for risk stratifying patients with PAD, and novel approaches to identification of reliable biomarkers in PAD.

SUMMARY

The exponential growth of genetic tools and newer technologies provides opportunities to investigate and identify newer pathways in the development and progression of PAD, and thereby in the identification of newer biomarkers and therapies.

Biochemical indices of oxidative stress and inflammation in the evaluation of peripheral artery disease

BACKGROUND

The aims of this study were: (1) to investigate changes in indices of oxidative stress and inflammation in the evaluation of peripheral artery disease (PAD); (2) to compare the diagnostic efficacy of these parameters with that of classical clinical laboratory routine parameters.

DESIGN AND METHODS

We studied 115 patients with PAD and 300 healthy volunteers.

RESULTS

PAD patients had significantly increased circulating concentrations of F2-isoprostanes, protein carbonyls, chemokine (C-C motif) ligand 2 (CCL2), high-sensitivity C-reactive protein (hs-CRP), β-2-microglobulin (B2M), and decreased paraoxonase-1 (PON1) levels. When patients were classified according to the Fontaine score, we observed important increases in plasma F2-isoprostanes and CCL2 that appeared in milder stages of the disease, and remained so at similar levels in more advanced stages; almost no overlapping with the control group was noted. Receiver operating characteristics analysis comparing patients and controls revealed that the areas under the curve for F2-isoprostanes and CCL2 approached unity [0.999 (0.998-1.000) and 0.993 (0.985-1.000)], respectively, and significantly higher to those of the other measured parameters.

CONCLUSION

Our data suggest that F2-isoprostanes and CCL2 measurements may be useful tools for the diagnosis of PAD.

Oxidative Stress and IgG Antibody Modify Periodontitis-CRP Association

In a previous report, we demonstrated the inverse association of high serum 8-isoprostane levels, a marker for oxidative stress, with decreased serum IgG antibodies to oral bacteria. The association between increased serum IgG with increased plaque and periodontitis (increased probing depths) was attenuated by high systemic oxidative stress. Other investigations have reported a role for systemic oxidative stress as a stimulus of hepatic C-reactive protein (CRP) response. These observations led us to hypothesize that the reported relationship of periodontitis to elevated serum CRP, a systemic inflammatory marker, may be modified by oxidative stress and that the levels of serum antibodies to oral bacteria might be an intermediary explanatory variable linking the association of systemic oxidative stress, periodontal disease, and levels of CRP. This hypothesis was explored as a secondary analysis of the Dental ARIC (Atherosclerosis Risk in Communities) study using serum levels of CRP, serum IgG levels to 16 oral organisms, serum levels of 8-isoprostane, and periodontal status. The findings indicate periodontitis is associated with high CRP in the presence of elevated oxidative stress that serves to suppress the IgG response. Only within the highest 8-isoprostane quartile was periodontitis (pocket depth) associated with increased serum CRP levels (P = 0.0003). Increased serum IgG antibody levels to oral bacteria were associated with lowered serum CRP levels. Thus, systemic oxidative stress, which has been demonstrated to be associated with increased levels of CRP in other studies, appears to be associated with the suppression of bacterial-specific IgG levels, which in the presence of periodontal disease can result in an enhanced systemic CRP response. Conversely, individuals with increased serum IgG antibodies to plaque bacteria exhibit lowered serum CRP levels. These 2 factors, oxidative stress and the serum IgG response, appear to function in opposing directions to modify serum levels of CRP and the association with periodontitis.

Renal vasoconstriction is augmented during exercise in patients with peripheral arterial disease

Peripheral arterial disease (PAD) patients have augmented blood pressure increases during exercise, heightening their cardiovascular risk. However, it is unknown whether patients have exaggerated renal vasoconstriction during exercise and if oxidative stress contributes to this response. Eleven PAD patients and 10 controls (CON) performed 4-min mild, rhythmic, plantar flexion exercise of increasing intensity (0.5-2 kg) with each leg (most and least affected in PAD). Eight patients also exercised with their most affected leg during ascorbic acid (AA) infusion. Renal blood flow velocity (RBFV; Doppler ultrasound), mean arterial blood pressure (MAP; Finometer), and heart rate (HR; electrocardiogram [ECG]) were measured. Renal vascular resistance (RVR), an index of renal vasoconstriction, was calculated as MAP/RBFV. Baseline RVR and MAP were similar while HR was higher in PAD than CON (2.08 ± 0.23 vs. 1.87 ± 0.20 au, 94 ± 3 vs. 93 ± 3 mmHg, and 72 ± 3 vs. 59 ± 3 bpm [P < 0.05] for PAD and CON, respectively). PAD had greater RVR increases during exercise than CON, specifically during the first minute (PAD most: 26 ± 5% and PAD least: 17 ± 5% vs. CON: 3 ± 3%; P < 0.05). AA did not alter baseline RVR, MAP, or HR. AA attenuated the augmented RVR increase in PAD during the first minute of exercise (PAD most: 33 ± 4% vs. PAD most with AA: 21 ± 4%; P < 0.05). In conclusion, these findings suggest that PAD patients have augmented renal vasoconstriction during exercise, with oxidative stress contributing to this response.

Systematic review on the association between F2-isoprostanes and cardiovascular disease

Background

Oxidative stress may play an aetiological role in the development and progression of cardiovascular disease (CVD). However, evidence on its biochemical markers has been controversial. This article aimed to assess the role of F2-isoprostanes, a marker for measuring in vivo lipid oxidation, as a biomarker for CVD, including coronary artery disease, stroke and peripheral artery disease.

Methods

A literature search was performed using PubMed and EMBASE (from 1966 to February 2012). Studies that investigated the association between F2-isoprostanes and CVD were eligible.

Results

Of the 22 eligible studies retrieved, 20 studies showed a significant association between F2-isoprostanes and CVD. However, to date, there have been only four population-based studies, with one study reporting null association. Although data from prospective studies are ideal to examine a role of such biomarkers in predicting future CVD events, only two studies were prospective. In addition, differences in population characteristics, sample handling/storage and assays, coupled with a lack of confounding adjustment, may all contribute to the enormous variation in previous studies.

Conclusions

High levels of F2-isoprostanes in urine or blood may be a non-specific indicator of CVD. However, further population-based studies are needed. In addition, multivariable analyses are required for future studies to control confounding and improve classification accuracy.

Oxidative stress biomarkers as predictors of cardiovascular disease

Evidence for the role of oxidative stress in the pathogenesis of cardiovascular disease (CVD) is primarily based on experimental and observational human studies. The aim of this review is to examine the observational longitudinal studies that have investigated the relationship between oxidative stress biomarkers and CVD. Fifty-one studies were identified with twenty-six of these measuring oxidized (Ox)-LDL, fifteen assessing myeloperoxidase, seven using lipid peroxidation measures and three quantifying protein oxidation. Results of studies using Ox-LDL have been equivocal with sixteen of the twenty-six studies reporting that this measure is predictive of cardiovascular events. These inconsistent results are not explained by differences in the study populations (primary or secondary CVD) or the type of assay used (auto or monoclonal antibodies). Six of the seven lipid peroxidation, and two of three protein oxidation studies found associations. Twelve of fifteen studies assessing the role of myeloperoxidase reported it to be predictive of CVD. However, issues surrounding the specificity of myeloperoxidase as a marker of oxidative stress and the small number of research groups reporting these results, limit this finding. In summary, the ability of oxidative stress biomarkers to predict CVD has yet to be established. Furthermore, it is important to note that the methods used to assess oxidative stress in these studies are indirect, and the evidence that the various methods actually reflect oxidative stress in vivo is limited.

Biomarkers of peripheral arterial disease

Atherosclerotic arterial occlusive disease affecting the lower extremities is also known as peripheral artery disease (PAD). This disorder affects 8 to 12 million individuals in the U.S. and is increasingly prevalent in Europe and Asia. Unfortunately, most patients are not diagnosed and are not optimally treated. A blood test for PAD, if sufficiently sensitive and specific, would be expected to improve recognition and treatment of these individuals. Even a biomarker panel of moderate sensitivity and specificity for PAD could refine risk stratification to select individuals for diagnostic vascular examination. Alternatively, biomarkers for PAD may be useful in determining prognosis, the risk for progression, or the response to therapy. Finally, the discovery of biomarkers associated with PAD may provide novel insights into the pathophysiology of PAD and new therapeutic avenues to pursue. Biomarkers may be derived from studies of the genome, transcriptome, proteome, or metabolome. The focus of this review is on proteomic biomarkers associated with PAD.

Inflammation and oxidative stress are associated differently with endothelial function and arterial stiffness in healthy subjects and in patients with atherosclerosis

Inflammation and oxidative stress (OxS) play key roles in atherogenesis; however, their causal relationship is not yet completely understood. Much attention has been given to the possibility that inflammation is a primary process of atherosclerosis and that OxS may be a by-product of the inflammatory process. We hypothesized, accordingly, that chronic systemic inflammation affects endothelial vasomotor function in the subclinical condition, whereas oxidative modifications are more involved in the structural stiffening of the arteries in atherosclerosis. The aim of our study was to test this hypothesis. Endothelial function and arterial stiffness were assessed non-invasively by pulse wave analysis, and blood/urinary samples were taken in 39 patients with peripheral arterial disease as well as in 34 controls. The patients showed significantly reduced endothelial function index (EFI) and increased augmentation index (AIx), as well as higher estimated aortic pulse wave velocity (PWV) and elevated values of the intercellular adhesion molecule-1 (ICAM-1), high sensitivity C-reactive protein, myeloperoxidase and urinary 8-iso-prostaglandin F2a (F2-IsoPs). There was an inverse association between EFI and ICAM-1 (R = -0.44, p = 0.009) in the controls, but not in the patients. Augmentation index and estimated aortic PWV correlated with F2-IsoPs only in the patients (R = 0.5, p = 0.001; R = -0.43, p = 0.006, respectively). After controlling for potential confounders, these associations remained significant. The study demonstrates that impairment of endothelial vasomotor capacity is affected by degree of inflammation in the subclinical condition, whereas arterial stiffening is determined by level of oxidative modifications in atherosclerosis.

Experimental Exposure to Wood-Smoke Particles in Healthy Humans: Effects on Markers of Inflammation, Coagulation, and Lipid Peroxidation

Particulate air pollution is known to increase cardiovascular morbidity and mortality. Proposed mechanisms underlying this increase include effects on inflammation, coagulation factors, and oxidative stress, which could increase the risk of coronary events and atherosclerosis. The aim of this study was to examine whether short-term exposure to wood smoke affects markers of inflammation, blood hemostasis, and lipid peroxidation in healthy humans. Thirteen subjects were exposed to wood smoke and clean air in a chamber during two 4-h sessions, 1 wk apart. The mass concentrations of fine particles at wood smoke exposure were 240-280 mug/m3, and number concentrations were 95,000-180,000/cm3. About half of the particles were ultrafine (< 100 nm). Blood and urine samples were taken before and after the experiment. Exposure to wood smoke increased the levels of serum amyloid A, a cardiovascular risk factor, as well as factor VIII in plasma and the factor VIII/von Willebrand factor ratio, indicating a slight effect on the balance of coagulation factors. Moreover, there was an increased urinary excretion of free 8-iso-prostaglandin2alpha, a major F2-isoprostane, though this was based on nine subjects only, indicating a temporary increase in free radical-mediated lipid peroxidation. Thus, wood-smoke particles at levels that can be found in smoky indoor environments seem to affect inflammation, coagulation, and possibly lipid peroxidation. These factors may be involved in the mechanisms whereby particulate air pollution affects cardiovascular morbidity and mortality. The exposure setup could be used to establish which particle characteristics are critical for the effects.

The myopathy of peripheral arterial occlusive disease: Part 2. Oxidative stress, neuropathy, and shift in muscle fiber type

In recent years, an increasing number of studies have demonstrated that a myopathy is present, contributes, and, to a certain extent, determines the pathogenesis of peripheral arterial occlusive disease. These works provide evidence that a state of repetitive cycles of exercise-induced ischemia followed by reperfusion at rest operates in patients with peripheral arterial occlusive disease and mediates a large number of structural and metabolic changes in the muscle, resulting in reduced strength and function. The key players in this process appear to be defective mitochondria that, through multilevel failure in their roles as energy, oxygen radical species, and apoptosis regulators, produce and sustain a progressive decline in muscle performance. In this 2-part review, the currently available evidence that characterizes the nature and mechanisms responsible for this myopathy is highlighted. In part 1, the functional and histomorphological characteristics of the myopathy were reviewed, and the main focus was on the biochemistry and bioenergetics of its mitochondriopathy. In part 2, accumulating evidence that oxidative stress related to ischemia reperfusion is probably the major operating mechanism of peripheral arterial occlusive disease myopathy is reviewed. Important new findings of a possible neuropathy and a shift in muscle fiber type are also reviewed. Learning more about these mechanisms will enhance our understanding of the degree to which they are preventable and treatable.

Macadamia nut consumption modulates favourably risk factors for coronary artery disease in hypercholesterolemic subjects

Macadamia nuts are rich source of monounsaturated fats (oleic and palmitoleic acids) and contain polyphenol compounds, therefore, their consumption can be expected to impart health benefits to humans. This study was conducted to examine the effects of consuming macadamia nuts in hypercholesterolemic male individuals on plasma biomarkers of oxidative stress, coagulation and inflammation. Seventeen hypercholesterolemic male subjects were given macadamia nuts (40-90 g/day), equivalent to 15% energy intake, for a period of 4 weeks. As expected, monounsaturated fatty acids (16:1n-7, 18:1n-9 and 20:1n-9) were elevated in the plasma lipids of all volunteers following intervention with macadamia nuts. Plasma markers of inflammation (leukotriene, LTB(4)) and oxidative stress (8-isoprostane) were significantly lower (1,353 +/- 225 vs. 1,030 +/- 129 pg/mL and 876 +/- 97 vs. 679 +/- 116 pg/mL, respectively) within 4 weeks following macadamia nut intervention. There was a non-significant (23.6%) reduction in the plasma TXB(2)/PGI(2) ratio following macadamia nut consumption. This study demonstrates, for the first time, that short-term macadamia nut consumption modifies favourably the biomarkers of oxidative stress, thrombosis and inflammation, the risk factors for coronary artery disease, despite an increase in dietary fat intake. These data, combined with our previous results on cholesterol-lowering effects of macadamia nuts, suggest that regular consumption of macadamia nuts may play a role in the prevention of coronary artery disease.

Combination therapy of statin with flavonoids rich extract from chokeberry fruits enhanced reduction in cardiovascular risk markers in patients after myocardial infraction (MI)

Recent studies have shown, that chronic flavonoids treatment improves vascular function and cardiovascular remodeling by decreasing superoxide anion production as well as by increasing NO realize from endothelial cells. A progressive decrease in systolic blood pressure and reduction of low-density lipoprotein oxidation (Ox-LDL) has also been reported. However, none of these studies were done in patient with coronary artery disease treated with statins. This was a double-blind, placebo-controlled, parallel trial. Forty-four patients (11 women and 33 men, mean age 66 years) who survived myocardial infraction and have received statin therapy for at least 6 months (80% dose of 40 mg/day simvastatin) were included in the study. The subjects were randomised to receive either 3 x 85 mg/day of chokeberry flavonoid extract (Aronia melanocarpa E) or placebo for a period of 6 weeks. The study extract was a commercially-available (OTC) product of the following declared composition: anthocyans (about 25%), polymeric procyanidines (about 50%) and phenolic acids (about 9%). Compared to placebo (ANOVA and Tukey's test), flavonoids significantly reduced serum 8-isoprostans (p<0.000) and Ox-LDL levels (p<0.000) (by 38 and 29%, respectively), as well as hsCRP (p<0.007) and MCP-1 (p<0.001) levels (by 23 and 29%, respectively). In addition, significant increase in adiponectin (p<0.03) levels and reduction in systolic and diastolic blood pressure by a mean average of 11 and 7.2 mmHg, respectively were found.

CONCLUSION

In view of the fact that chokeberry flavonoids reduce the severity of inflammation, regardless of statins, they can be used clinically for secondary prevention of ischaemic heart disease.

Obesity and Thrombosis

OBJECTIVES

To describe the pathophysiological mechanisms by which obesity increases the propensity to thrombosis, the leading cause of death in the Western World, with particular emphasis on the role of inflammation, oxidative stress, dyslipidaemia, insulin resistance and the coagulation cascade.

DESIGN

Review article.

MATERIALS AND METHODS

Medline (1966-2005) and Cochrane library review of literature examining the relationship between obesity and thrombosis. Search terms included obesity, overweight, body mass index, thrombosis, cardiovascular disease, venous thromboembolism, peripheral arterial disease, and coronary heart disease.

RESULTS

Obesity is an important and growing public health issue that is estimated to affect more than half of the UK adult population. Obesity, in particular central (visceral) obesity, is associated with significant, and largely preventable, morbidity and mortality including an increased incidence and prevalence of arterial and venous thrombotic events. The various mechanisms by which obesity may cause thrombosis include: the actions of so-called adipocytokines from adipose tissue, e.g. leptin and adiponectin; increased activity of the coagulation cascade and decreased activity of the fibrinolytic cascade; increased inflammation; increased oxidative stress and endothelial dysfunction; and disturbances of lipids and glucose tolerance in association with the metabolic syndrome.

CONCLUSIONS

Obesity appears to be associated with thrombosis via several mechanisms. These pro-thrombotic factors are all improved by weight loss.

Association of gliclazide and left ventricular mass in type 2 diabetic patients

Diabetes is a state of increased oxidant stress and there is evidence that oxidation may play a role in the genesis of higher left ventricular mass. Gliclazide has been shown to possess free radical scavenging properties. We assessed whether gliclazide may have a beneficial effect on left ventricular mass via reducing 8-iso-prostaglandin F(2alpha) concentrations, a reliable marker of oxidant injury. A total of 41 patients were randomized into two groups. All patients had been taking glibenclamide for more than 3 months before being randomized to switch either an equipotent dose of gliclazide (n=21) or to continue on glibenclamide (n=20). Baseline characteristics were similar in both groups. At 6 months, gliclazide-treated patients showed a significant regression in left ventricular mass index compared with the glibenclamide-treated group (-16% versus 3%, P=0.003). Gliclazide patients had significantly lower plasma 8-iso-prostaglandin F(2alpha) compared with baseline (299+/-101 pg/ml versus 400+/-112 pg/ml, P=0.001) and the glibenclamide-treated patients (299+/-101 pg/ml versus 388+/-114 pg/ml, P=0.01) after 6-month therapy. The magnitude of left ventricular mass index regression correlated univariately with the magnitude of inhibition of 8-iso-prostaglandin F(2alpha) formation (r=0.74, P<0.0001). Multivariate analysis revealed that regression of left ventricular mass index significantly correlated with the changes of 8-iso-prostaglandin F(2alpha) (P<0.0001, adjusted R(2)=0.55). Our findings demonstrated for the first time that in addition to its primary hypoglycemia, gliclazide may have an additional effect on reducing left ventricular mass, possibly through attenuation of free radical formation.

Imbalance between nitric oxide generation and oxidative stress in patients with peripheral arterial disease: effect of an antioxidant treatment

BACKGROUND

Nitric oxide (NO), a potent vasodilator produced by endothelial cells, is reduced in patients with peripheral arterial disease (PAD), but the mechanism has not been fully elucidated. Because NO is rapidly inactivated by superoxide anion, we speculated that enhanced oxidative stress could lower NO generation. The aim of our study was to investigate if an imbalance between oxidative stress and NO does exist in patients with PAD and if an increase of NO formation could be achieved by an antioxidant treatment.

METHODS

In a first study, serum levels of nitrite and nitrate (NOx), markers of NO generation, and 8-hydroxy-2-deoxyguanosine (8-OHdG), a marker of oxidative stress and maximal walking distance (MWD), were measured in 40 PAD patients and 40 controls. In a second study, 10 PAD patients were randomly allocated in a crossover design to intravenous propionyl-L-carnitine (6 g/day) or placebo for 7 days, with a washout of 30 days between the two phases of the trial. Serum levels of NOx and 8-OHdG were measured before and after the study.

RESULTS

Compared with controls, serum levels of 8-OHdG (mean +/- SD) were significantly increased in PAD patients (4.4 +/- 3.1 ng/mL vs 2.4 +/- 1.2 ng/mL; P < .001), and serum levels of NOx were significantly decreased (11.6 +/- 6 microM vs 17 +/- 6.1 microM; P < .001). Levels of 8-OHdG and NOx were inversely correlated (r = -0.879; P < .001). Serum levels 8-OHdG were inversely correlated with MWD (r = -0.48, P = .002). The interventional trial showed no changes in the patients given placebo. Patients treated with propionyl-L-carnitine showed a significant increase of MWD from 101 +/- 31 meters to 129 +/- 35 meters (P = .007) and in NOx from 14.5 +/- 4.5 microM to 17.1 +/- 3.8 microM (P = .007). A significant decrease of 8-OHdG from 3.6 +/- 1.1 ng/mL to 2.6 +/- 1 ng/mL was also found (P = .005.)

CONCLUSIONS

This study suggests that in PAD patients, the reduction of NO generation could be dependent upon enhanced oxidative stress.

Nicotinamide adenine dinucleotide phosphate oxidase: a promiscuous therapeutic target for cardiovascular drugs?

The increased expression and activity of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase complex has emerged as a major common factor in the etiology of all forms of cardiovascular diseases since the upregulation of intravascular NADPH oxidase results in the formation of superoxide (O(2)(-)), which in turn promotes vasculopathy. An ever-increasing number of drugs commonly used in cardiovascular medicine have been shown to influence NADPH oxidase expression and activity. These include nitric oxide donors, nitroaspirin, eicosanoids, phosphodiesterase inhibitors, corticosteroids, antioxidants, and specific inhibitors. The objective of this review is to discuss these drugs in relation to the mechanisms underlying their effects on NADPH oxidase activity and the expression and therapeutic implications of these effects.

Associations of plasma 8-isoprostane levels with the presence and extent of coronary stenosis in patients with coronary artery disease

Oxidative stress may play a role in the development of atherosclerosis. The purpose of the present study was to explore the relationship between 8-isoprostaglandin F(2alpha) (8-iso-PGF(2alpha)) levels and the presence of coronary artery disease (CAD) and to also clarify whether 8-iso-PGF(2alpha) might add independently to measures of CAD extent. The study group consisted of 241 consecutive patients who were undergoing coronary angiography for suspected CAD. 8-iso-PGF(2alpha) levels were recorded for all participants. The analysis revealed a significant difference in 8-iso-PGF(2alpha) levels in patients with and without hypertension (P<0.001), in patients with diabetes relative to nondiabetic patients (P<0.05), and in males respect to females (P<0.001). A significant positive correlation was found between age and 8-iso-PGF(2alpha) levels (P<0.001). 8-iso-PGF(2alpha) levels correlated with the number of cardiovascular risk factors (P<0.001). 8-iso-PGF(2alpha) levels were higher in the CAD(+) respect to the CAD(-) groups (337.7+/-80.2 and 263.8+/-74.2 pg/ml and P<0.001). A stepwise elevation in the 8-iso-PGF(2alpha) levels was found depending on the number of affected vessels (P<0.001). The 8-iso-PGF(2alpha) levels showed a significant positive correlation with the numbers of >50 and >25% stenotic segments (P<0.001) and the extent score of coronary stenosis (P<0.001). The multivariate logistic regression analysis indicated 8-iso-PGF(2alpha) as an independent factor associated with CAD (odds ratio, 2.47 and P=0.001). The results suggested that 8-iso-PGF(2alpha) is associated with the presence of CAD in patients undergoing coronary angiography and is also related to the extent of coronary stenosis in Chinese population.

Increased prevalence of peripheral arterial disease in osteoporotic postmenopausal women

The aim of this study was to investigate the prevalence and correlates of peripheral arterial disease (PAD) in a population of osteoporotic postmenopausal women. The presence of PAD was assessed by ankle brachial index (ABI) in 345 ambulatory osteoporotic postmenopausal women, and in 360 community-based, age- and race-matched postmenopausal women with normal bone mineral density (BMD) (control group). PAD was detected in 63/345 (18.2%) osteoporotic women and in 14/360 (3.8%) control subjects (P < 0.0001). The mean ABI values were significantly lower in the osteoporosis group than in the control group (0.98 +/- 0.09 vs. 1.04 +/- 0.06, P < 0.0001). No difference in cardiovascular risk factors was observed between osteoporotic patients and controls, or between osteoporotic patients with and without PAD. Osteoporotic patients with PAD had lower femoral neck BMD T scores than those without PAD (-4.2 +/- 0.7 vs. -2.3 +/- 0.7, P < 0.0001). Only 4 PAD patients (5.1%) had intermittent claudication. In multivariate logistic regression analysis, factors independently associated with PAD within osteoporotic patients were lower femoral neck BMD T score (odds ratio (OR) = 0.20, 95% confidence interval (CI), 0.05-0.70, P = 0.01) and systolic blood pressure (OR = 1.02, 95% CI, 1.00-1.03, P = 0.01). This study shows for the first time an increased prevalence of PAD among osteoporotic postmenopausal women, with a lower femoral neck BMD T score being a significant independent predictor. The findings suggest that vascular status evaluation should be done in osteoporotic postmenopausal women in order to identify candidate patients for preventive and therapeutic cardiovascular interventions.

Intermittent claudication: an overview

Intermittent claudication (IC) is defined by leg muscle pain, cramping and fatigue brought on by ambulation/exercise; relieved on rest; and caused by inadequate blood supply and is the primary symptom of peripheral arterial disease (PAD). PAD has a detrimental effect on the quality of life. PAD is a debilitating atherosclerotic disease of the lower limbs and is associated with an increased risk of cardiovascular morbidity and mortality. IC is an extremely important marker of atheroma. Up to 60% patients with IC have significant underlying coronary and/or carotid disease and 40% of all patients suffering from IC die or suffer a stroke within 5 years of presentation. The therapeutic intervention of IC essentially aims at providing symptomatic relief and reducing the systemic cardiovascular complications. Although exercise therapy is one of the most efficacious conservative treatments for claudication, the pharmacotherapeutic goals can be best achieved through an increase in the walking capacity to improve quality of life and a decrease in rates of amputation. In the development of treatment for IC, an aggressive non-pharmacological intervention and pharmacological treatment of the risk factors associated with IC are considered. In the next 2 years, the results of major trials of drugs that stabilize and regress atherosclerosis such as statins and angiotensin converting enzyme inhibitors, and anti-platelet agents, recombinant growth factors and immune modulators will be available for IC. Levocarnitine (l-carnitine) and a derivative, propionyl levocarnitine, are emerging agents that increase the pain-free walking and improve the quality of life in IC patients by working at the metabolism and exercise performance of ischemic muscles. This article provides a comprehensive review of the pathophysiology involved, diagnosis of IC and existing and emerging pharmacotherapies with rationale for their use in its treatment.

Factor V Leiden, prothrombin G20210A, and methylenetetrahydrofolate reductase C677T mutations are not associated with chronic limb ischemia: the Linz Peripheral Arterial Disease (LIPAD) study

OBJECTIVE

Factor V G1691A (Leiden), prothrombin G20210A, and methylenetetrahydrofolate reductase (MTHFR) C677T mutations are considered risk factors for venous thromboembolism. It remains to be characterized whether the presence of these relatively common mutations poses a risk for peripheral arterial disease (PAD). Therefore, we intended to test, by conducting a case-control study, the hypothesis that PAD was associated with an increased prevalence of factor V G1691A, prothrombin G20210A, and MTHFR C677T mutations.

METHODS

The study comprised 433 patients admitted for inpatient diagnostics and treatment of PAD in patients with chronic limb ischemia. Patients with acute ischemia or malignancy were excluded. A total of 433 control subjects matched to the patients with PAD in a 1:1 design by sex, age (+/-2 years), and diabetes mellitus status were recruited. Factor V G1691A, prothrombin G20210A, and MTHFR C677T genotypes were assessed by polymerase chain reaction.

RESULTS

For the factor V G1691A polymorphism, the genotype frequencies in PAD patients were 92.8% GG (normal homozygotes = wild type) and 7.2% GA (mutant heterozygotes), and in control subjects they were 94.0% GG and 6.0% GA (chi 2 test; P = .493). The distribution of the prothrombin G20210A genotypes was 96.3% GG (normal homozygotes = wild type) and 3.7% GA (mutant heterozygotes) in PAD patients and was 97.2% GG and 2.8% GA in control subjects (chi 2 test; P = .442). Genotype frequencies for the MTHFR C677T polymorphism were 47.8% CC (normal homozygotes = wild type), 43.4% CT (mutant heterozygotes), and 8.8% TT (mutant homozygotes) in PAD patients, compared with 47.1% CC, 44.1% CT, and 8.8% TT in control subjects (chi 2 test; P = .977). Accordingly, as determined by logistic regression analysis, no significant odds ratios for heterozygous or homozygous genotypes of the three polymorphisms could be observed.

CONCLUSIONS

PAD was not associated with an increased prevalence of factor V G1691A, prothrombin G20210A, and MTHFR C677T mutations in the population studied. Thus, there is no indication that of one of these mutations may be a risk factor for chronic limb ischemia. However, the role of these mutations in acute limb ischemia remains to be clarified.