Association of paraoxonase activity and coronary blood flow

The association of paraoxonase I gene polymorphisms Q192R (rs662) and L55M (rs854560) and its activity with metabolic syndrome components in fars ethnic group

OBJECTIVES

Metabolic syndrome (MetS) may cause premature development of some diseases. PON1 genes may be involved in the pathogenesis of MetS. The aim of study was to evaluate the association between Q192R and L55M gene polymorphisms and its enzyme activity with the MetS components in subjects with and without MetS.

METHODS

Polymerase Chain Reaction and Restriction Fragment Length Polymorphism analysis were performed to determine polymorphisms of the paraoxonase1 gene in subjects with and without metabolic syndrome. Biochemical parameters were measured by spectrophotometer.

RESULTS

The MM, LM, and LL genotype frequencies of the PON1 L55M polymorphism were 10.5, 43.4, and 46.1%, and 22.4, 46.6, and 31% and; the QQ, QR, and RR genotype frequencies of the PON1 Q192R polymorphism were 55.4, 38.6 and 6%; and 56.5, 34.8 and 8.7% in subjects with and without MetS, respectively. The L and M allele frequencies were 68 and 53%; and 32 and 47% for PON1 L55M in subjects with and without MetS, respectively. The Q and R allele frequencies for PON1 Q192R were 74 and 26% in both groups. There were significant differences in HDL-cholesterol level and PON1 activity in the genotypes QQ, QR, and RR of the PON1 Q192R polymorphism in subjects with MetS.

CONCLUSIONS

The PON1 Q192R genotypes had only effected on PON1 activity and HDL-cholesterol level in subjects with MetS. Different genotypes of the PON1 Q192R seem to be important candidates to make the subjects susceptible to MetS in the Fars ethnic group.

Reduced paraoxonase 1 activities may explain the comorbidities between temporal lobe epilepsy and depression, anxiety and psychosis

BACKGROUND

Temporal lobe epilepsy (TLE) is the most common focal epilepsy subtype in adults and is frequently accompanied by depression, anxiety and psychosis. Aberrations in total paraoxonase 1 (PON1) status may occur in TLE and these psychiatric conditions.

AIM

To examine PON1 status, namely Q192R PON1 genotypes and PON1 enzymatic activities, in TLE.

METHODS

We recruited 40 normal controls and 104 TLE patients, 27 without comorbidities and 77 with comorbidities including mood disorders (n = 25), anxiety disorders (n = 27) and psychosis (n = 25).

RESULTS

Four-(chloromethyl)phenyl acetate hydrolysis (CMPAase) and arylesterase activities were significantly lower in TLE and mesial temporal sclerosis (MTS) with and without psychiatric comorbidities than those in normal controls. The areas under the receiver operating characteristic curve of CMPAase were 0.893 (0.037) for TLE and 0.895 (± 0.037) for MTS. Partial least squares path analysis showed that there were specific indirect effects of PON1 genotype on TLE severity (P < 0.0001) and psychopathology (P < 0.0001), which were both mediated by lowered CMPAase activity, while arylesterase activity was not significant. The severity of TLE was significantly associated with psychopathology scores. Furthermore, PON1 CMPAase activity was inversely associated with Mini Mental State Examination score.

CONCLUSION

The severity of TLE and comorbidities are to a large extent explained by reduced PON1 enzyme activities and by effects of the Q192R genotype, which are mediated by reduced CMPAase activity. Total PON1 status plays a key role in the pathophysiology of TLE, MTS and psychiatric comorbidities by increasing the risk of oxidative toxicity. PON1 enzyme activities are new drug targets in TLE to treat seizure frequency and psychiatric comorbidities.

Echocardiographic Evaluation of Left and Right Ventricular Function in Patients with Coronary Slow Flow Syndrome: A Comparative Study

The Coronary Slow Flow Phenomenon is a syndrome of normal coronary anatomy and delayed progression of contrast medium through the coronary vessels. This research attempts to analyze and compare the systolic and diastolic function of the left and right ventricle in primary Slow Flow and Normal Coronary Flow.Two groups of primary Slow Coronary Flow (33 people) and Normal Coronary Flow (11 people) were included and the systolic and diastolic function of the ventricles was analyzed and compared between them.In the control group 18% of patients had mild and in the case group 24.2% mild, and 3.1% had moderate left ventricular diastolic dysfunction (P >0.05). The frequency distribution of the left and right ventricular systolic dysfunction was similar in the two groups.There was no statistically significant difference between two groups and in the association of cardiac dysfunction, it may be reasonable to investigate other causes.

Slow Coronary Flow: Pathophysiology, Clinical Implications, and Therapeutic Management

Coronary slow flow (CSF) is an angiographic phenomenon with specific epidemiologic characteristics, associated clinical presentation, and prognosis. Although patients with CSF are diagnosed as having "normal coronary arteries," it seems appropriate to consider CSF as a distinct disease entity requiring specific treatment. The patient with CSF is usually male, smoker, obese, with a constellation of risk factors suggestive of metabolic syndrome. Unstable angina is the most common clinical presentation, with recurrent episodes of chest pain at rest associated with electrocardiographic changes often requiring readmission and reevaluation. Regarding definition and diagnosis, interventionists should first exclude possible "secondary" causes of CSF, use objective means for definition and then differentiate from other similar conditions such as microvascular angina. Although the phenomenon is generally benign, patients with CSF are severely symptomatic with recurrent episodes of chest pain and poor quality of life. Furthermore, acute presentation of the phenomenon is commonly life-threatening with ventricular tachyarrhythmias, conduction abnormalities, or cardiogenic shock. Acute treatment of CSF includes, but is not restricted to, intracoronary infusion of dipyridamole, adenosine, or atropine. Chronic management of patients with CSF encompasses dipyridamole, diltiazem, nebivolol, telmisartan, and/or atorvastatin associated with amelioration of angina symptoms, improved quality of life, and good prognosis.

The Relevance of Noncoding DNA Variations of Paraoxonase Gene Cluster in Atherosclerosis-Related Diseases

The human paraoxonase (PON) gene cluster is comprised of three contiguous genes (PON1, PON2 and PON3) of presumably common origin coding three lactonases of highly similar structure and substrate specificity. The catalytic activity of PON proteins is directed toward artificial organophosphates and in physiological conditions toward thiolactones and oxidized phospholipids. Consequently, PON enzymes are regarded as an effective defense against oxidative stress and, as a result, against atherosclerosis development. Additionally, both PON's serum activity and its concentration are influenced by several polymorphic variations in coding and noncoding DNA regions of the PON gene cluster remaining in linkage disequilibrium. Hence, the genetic polymorphism of the PON gene cluster may contribute to atherosclerotic process progression or deceleration. In this review the authors analyzed the relevance of noncoding DNA polymorphic variations of PON genes in atherosclerosis-related diseases involving coronary and peripheral artery disease, stroke, diabetes mellitus, dementia and renal disease and concluded that the effect of PON gene cluster' polymorphism has a considerable impact on the course and outcome in these conditions. The following PON genetic variations may serve as additional predictors of the risk of atherosclerosis in selected populations and individuals.

Paraoxonase 1 Activity, Polymorphism and Atherosclerosis Risk Factors in Patients Undergoing Coronary Artery Surgery

Background: Paraoxonase1 (PON1), an enzyme connected to high density lipoproteins (HDL) particles, plays an important role in protecting arteries against atherosclerosis. The serum activity and concentration of PON1 depends on several genetic polymorphisms as well as environmental factors. Materials and methods: Investigated population consisted of 71 patients aged 43–76 years with confirmed coronary heart disease (CHD). Established risk factors of CHD such as hypertension, elevated total cholesterol and LDL cholesterol (LDL-C), low HDL cholesterol (HDL-C), diabetes mellitus, obesity, smoking and premature CHD in family history were assessed. PON1 genotype for −108C/T promotor region was determined by polymerase chain reaction-restriction fragments length polymorphism (PCR–RFLP) method. Paraoxonase activity towards paraoxon and arylesterase activity towards phenyl acetate were measured spectrophotometrically. Results: Significant correlations between diabetes mellitus and paraoxonase activity (R = −0.264, p = 0.026) and between the premature coronary heart disease in family history and PON1 activity (R = −0.293, p = 0.013) were found. In multivariate analysis, PON1 paraoxonase activity was independently of confounding factors associated with diabetes (OR = 0.985; p = 0.024) and premature CHD in family history (OR = 0.983; p = 0.027). PON1 activity towards aryl acetate positively correlated with HDL-C level (R = 0.255, p = 0.032). In patients treated with statins, PON1 paraoxonase activity was significantly (p = 0.033) higher than in patients without treatment. Conclusions: In diabetic patients with CHD, paraoxonase activity is lower than in normoglycemic patients despite similar lipid profiles. Diabetes and positive family history in patients with overt CHD are associated with the serum PON1 activity, which might be an additional factor helpful in evaluating cardiovascular risk in this group of patients.

Effects of Daily Consumption of Cashews on Oxidative Stress and Atherogenic Indices in Patients with Type 2 Diabetes: A Randomized, Controlled-Feeding Trial

BACKGROUND

Cashews, as the main source of monounsaturated (MUFAs) and polyunsaturated (PUFAs) fatty acids, are associated with reduced risk of cardiovascular diseases. Despite evidence for beneficial effects of nuts on lipid profile and glycemic control, to the authors' best knowledge, little is known about cashews.

METHODS

An eight-week, randomized, isocaloric, controlled-feeding study was conducted on 50 patients with type 2 diabetes mellitus (T2DM) randomly assigned to either the control or intervention group (10% of total calorie from cashews). Weight, fasting plasma glucose (FPG), serum insulin concentration and sensitivity, lipid profile ratio, high-sensitive C-reactive protein (hs-CRP), total antioxidant capacity (TAC), and paraoxonase-1 (PON-1) were measured at baseline and after eight weeks of intervention adjusted for age, gender, baseline values of FPG, insulin, HOMA-IR (homeostatic model assessment of insulin resistance), fiber, and both baseline and post-intervention vitamin C levels as covariates.

RESULTS

Weight, body mass index (BMI), and waist circumference (WC) were not significantly different in the groups after eight weeks of intervention, as well as between the two groups, compared with the baseline measures. At the end of the study, serum insulin and low-density lipoprotein-cholesterol-to-high-density lipoprotein-cholesterol (LDL-C/HDL-C) ratio significantly decreased in the cashews group compared with those of the controls (P = 0.01 and P = 0.04, respectively). Although, HOMA-IR decreased significantly in the cashews group (P = 0.03), changes were not significant compared with the baseline measures (P = 0.056). Despite more increase in PON-1 activity in the cashews group, the changes were not statistically significant.

CONCLUSIONS

Daily consumption of cashews reduced serum insulin and LDL-C/HDL-C ratio in patients with T2DM. However, further studies with larger sample sizes and more duration are needed to confirm the current study results.

Oxidant-Antioxidant balance in patients with coronary slow flow

OBJECTIVE

Recent studies have focused on the probable role of oxidative stress in cardiovascular diseases. We aimed to assess the oxidant/antioxidant biomarkers in coronary slow flow (CSF).

METHODS

The study included 51 subjects with CSF and age and sex matched 32 controls. Detailed anamnesis of the patients in the study was taken and routine physical examinations were performed. Routine biochemical blood tests were analyzed. Total oxidative status (TOS), oxidative stress index (OSI) and lipid hydroxyperoxide (LOOH) levels as oxidant biomarkers; paraoxonase (PON1), ceruloplasmin (CP), free sulphydryl (SH) groups, and total antioxidant capacity (TAS) levels as antioxidant biomarkers were studied.

RESULTS

Baseline demographic characteristics of the study population did not differ significantly between groups.TOS, OSI and LOOH concentrations were higher in study group than in control group. However, there was no significant difference detected in levels of TAS, PON1, SH and CP. Multivariate logistic regression analysis revealed that TOS, hsCRP and smoking were indepedent risk factors of CSF.

CONCLUSIONS

Although there was not any significant difference in antioxidant biomarkers (TAS, PON1, SH and CP) in CSF patients, we detected increased TOS, OSI and LOOH levels which have oxidant properties. These data supported the possible involvement of oxidative stress in pathogenesis of CSF as previous studies reported.

Effects of propolis, caffeic acid phenethyl ester, and pollen on renal injury in hypertensive rat: An experimental and theoretical approach

The objective of this study was to evaluate the antioxidant effects of propolis, caffeic acid phenethyl ester (CAPE; active compound in propolis), and pollen on biochemical oxidative stress biomarkers in rat kidney tissue inhibited by N^ω -nitro-L-arginine methyl ester (L-NAME). The biomarkers evaluated were paraoxonase (PON1), oxidative stress index (OSI), total antioxidant status (TAS), total oxidant status (TOS), asymmetric dimethylarginine (ADMA), and nuclear factor kappa B (NF-κB). TAS levels and PON1 activity were significantly decreased in kidney tissue samples in the L-NAME-treated group (P < 0.05). The levels of TAS and PONI were higher in the L-NAME plus propolis, CAPE, and pollen groups compared with the L-NAME-treated group. TOS, ADMA, and NF-κB levels were significantly increased in the kidney tissue samples of the L-NAME-treated group (P < 0.05). However, these parameters were significantly lower in the L-NAME plus propolis, CAPE, and pollen groups (P < 0.05) compared with rats administered L-NAME alone (P < 0.05). Furthermore, the binding energy of CAPE within catalytic domain of glutathione reductase (GR) enzyme as well as its inhibitory mechanism was determined using molecular modeling approaches. In conclusion, experimental and theoretical data suggested that oxidative alterations occurring in the kidney tissue of chronic hypertensive rats may be prevented via active compound of propolis, CAPE administration.

The role of urotensin II and atherosclerotic risk factors in patients with slow coronary flow

BACKGROUND

Slow coronary flow (SCF) is an angiographic finding characterized with delayed opacification of epicardial coronary arteries without obstructive coronary disease. Urotensin II (UII) is an important vascular peptide, which has an important role in hypertension, coronary artery disease, and vascular remodeling in addition to potent vasoconstrictor effect.

OBJECTIVES

We investigated UII levels, hypertension, and other atherosclerotic risk factors in patients with SCF, a variety of coronary artery disease.

METHODS

We enrolled 14 patients with SCF and 29 subjects with normal coronary arteries without SCF. We compared the UII levels and the atherosclerotic risk factors between patients with SCF and control subjects with normal coronary flow.

RESULTS

UII concentrations were significantly higher in patients with SCF compared to controls (711.0 ± 19.4 vs. 701.5 ± 27.2 ng/mL, p = 0.006). We detected a positive correlation between SCF and age (r = 0.476, p = 0.001), BMI (r = 0.404, p = .002), UII concentrations (r = 0.422, p = 0.006), and hypertension (r = 0.594, p = 0.001).

CONCLUSION

We identified increased UII levels in patients with SCF. We think that UII concentrations may be informative on SCF pathogenesis due to relationship with inflammation, atherosclerosis, and vascular remodeling.

Paraoxonase 1 (PON1) Q192R genotypes and their interaction with smoking strongly increase atherogenicity and the Framingham risk score

OBJECTIVE

Paraoxonase 1 (PON1) polymorphisms are associated with an increased susceptibility to cardiovascular disease. PON1 Q192R polymorphism (rs662) partially determine PON1 hydrolytic activity and protect against oxidation of LDL and HDL. This study aimed to delineate the association of PON1 status (functional 192 genotype and plasma activity levels) and atherogenicity in urbans residents aged 40 years or more.

MATERIALS AND METHODS

Anthropometric data, lipid profiles, the atherogenic index of the plasma (AIP) and Framingham score risk were measured. Three kinetic assays were conducted to assay PON1 status using phenylacetate and 4-(chloromethyl)phenyl acetate as substrates.

RESULTS

Smoking per se did not significantly impact the AIP but the interaction PON1 genotype by smoking significantly increased the AIP. In subjects with the RR genotype smoking increased the AIP index from (estimated mean ± SEM) -0.038 ± 0.039 to 0.224 ± 0.094. The QR genotype increased the Framingham risk index by around 1.3 points. Smoking by RR genotype carriers significantly increased the Framingham risk score (17.23 ± 2.04) as compared to smoking (13.00 ± 1.06) and non-smoking (7.79 ± 0.70) by QQ+QR genotype carriers. The interaction RR genotype by smoking was a more important predictor (odds ratio = 7.90) of an increased Framingham risk score (> 20) than smoking per se (odds ratio = 2.73). The interaction smoking by RR genotype carriers significantly increased triglycerides and lowered HDL cholesterol.

CONCLUSION

Smoking per se has no (AIP) or a mild (Framingham risk score) effect on atherogenicity, while the interaction smoking by PON1 RR genotype has a clinically highly significant impact on atherogenicity.

Exploring the role of paraoxonases in the pathogenesis of coronary artery disease: a systematic review

Paraoxonases (PON) are three enzymes (PON1, PON2 and PON3) that play a role in the organism’s antioxidant system; alterations in which are associated with diseases involving oxidative stress. In this review, we summarize the evidence of PON related to the pathogenesis of coronary artery disease (CAD) and atherosclerosis. We searched three electronic databases (PubMed, Scopus and Cochrane Database) with no date limit. All of the articles selected investigated PON enzymatic activity and/or PON gene polymorphisms. The selection focused on PON in relation to atherosclerosis, CAD and myocardial infarction. The exclusion criteria were a sample size <100 patients, non-human studies, editorials and systematic reviews without restrictions on the country of origin. With these criteria, we identified thirty-five prospective studies published between 1986 and 2014 with a total of 28,164 participants. The relationship between PON gene polymorphisms and CAD was not conclusive, but most studies support the concept that alterations in PON1 enzymatic activity levels do influence atheroma formation. Conversely, relationships between PON2 and PON3 vs. CAD have not been extensively investigated. Our review of the current data concludes that the bases of paraoxonases involvement in atherosclerosis are poorly understood and that this issue requires future comprehensive, multi-centered studies.

Association of Meteorological Variables and Coronary Blood Flow

We aimed to assess the impact of meteorological variables on coronary blood flow (CBF). Coronary blood flow was evaluated using the thrombolysis in myocardial infarction frame count (TFC). The association of CBF with meteorological parameters such as temperature, relative humidity, total solar radiation, atmospheric pressure, wind velocity, and total sunshine duration were investigated as well as demographic, clinical, and laboratory characteristics. Assessment of 1206 patients (median age = 53 years, 723 females) revealed the presence of slow coronary flow (SCF) in 196 patients. Daily maximum temperature [odds ratio = 0.951, 95% confidence interval = 0.916-0.986, P = .007] was the only independent predictor of the presence of SCF, whereas systolic blood pressure (β = -0.139, P = .026), hematocrit level (β = 0.128, P = .044), and daily maximum temperature (β = -1.479, P = .049) were independent predictors of log10 (mean TFC). Findings of the present study suggest a role of meteorological parameters in CBF regulation.

Mean platelet volume is not associated with coronary slow flow: a retrospective cohort study

Objective:

To investigate mean platelet volume (MPV) levels in patients with coronary slow flow (CSF).

Methods:

465 stable angina pectoris cases with angiographically normal coronary arteries were recruited [coronary slow flow group (n=76), control group (n=389)] in the observational retrospective cohort study. Clinical, biochemical and demographic variables including MPV were noted and coronary blood flow was assessed with TIMI frame count (TFC).

Results:

Gender, smoking, height, serum creatinine, uric acid levels, hemoglobin, waist/hip ratio, systolic blood pressure but not MPV were significantly different among groups. Independent predictors of CSF were height (p=.029) and serum uric acid level (p=.045). Gender, height, weight, hip circumference, systolic blood pressure, fasting blood glucose, serum urea, creatinine, uric acid levels, hemoglobin and platelet count were associated with mean TFC whereas independent predictors of mean TIMI frame count were height (p=.010) and serum uric acid level (p=.041).

Conclusion:

Height and serum uric acid level but not MPV were independent predictors of both CSF and mean TFC.

Oxidative Stress and Spontaneous Reperfusion of Infarct-Related Artery in Patients With ST-Segment Elevation Myocardial Infarction

In the pathogenesis of atherosclerosis, oxidative stress plays a major role in plaque instability, rupture, and erosion, which subsequently leads to thrombus formation and causes total infarct-related artery (IRA) occlusion. We investigated the relationship between spontaneous reperfusion (SR) of IRA and oxidative stress in patients with anterior ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention. A total of 341 consecutive patients with anterior STEMI were prospectively included in the present study. Patients were divided into 2 groups according to their thrombolysis in myocardial infarction (TIMI) flow grade: SR group (66 patients, TIMI flow 3) and non-SR group (275 patients, TIMI flow 0-2). On multivariate logistic regression analysis, oxidative stress index (β = 0.868, 95% confidence interval [CI] = 0.806-0.934, P < .001), neutrophil to lymphocyte ratio, uric acid, mean platelet volume, Killip 2 to 4 class, and initial SYNTAX score were independently associated with SR. Oxidative stress as well as inflammation may play a pivotal role in the pathogenesis of SR in patients with STEMI.

Plasma lipoprotein(a) levels in patients with slow coronary flow

Introduction

Slow coronary flow (SCF) is a microvascular disorder characterized by delayed opacification of coronary vessels with normal coronary angiogram. It may be due to endothelial dysfunction and diffuse atherosclerosis. Lipoprotein(a) [Lp(a)] is related to cardiovascular events. Plasma Lp(a) levels have not been studied previously in SCF patients.

Aim

We investigated plasma Lp(a) and fibrinogen levels, and their relation to coronary flow rate in patients with SCF.

Material and methods

This cross-sectional study included 50 patients with SCF and 30 age- and sex-matched controls who had normal coronary arteries and normal flow. Coronary flow rates of patients and controls were counted with the thrombolysis in myocardial infarction (TIMI) frame count. Plasma Lp(a) and fibrinogen levels were measured in SCF patients and controls, with routine biochemical tests.

Results

There were no significant differences between the two groups with respect to plasma Lp(a) (21 mg/dl vs. 14 mg/dl, p = 0.11) and fibrinogen (278 mg/dl vs. 291 mg/dl, p = 0.48) levels. The TIMI frame count was not correlated with plasma Lp(a) (r = 0.13, p = 0.25) or fibrinogen (r = –0.14, p = 0.28) levels.

Conclusions

Our results show that there is no significant association between SCF and Lp(a) and fibrinogen levels.

Association of glomerular filtration rate with slow coronary flow in patients with normal to mildly impaired renal function

We evaluated the association between estimated glomerular filtration rate (eGFR) and slow coronary flow (SCF) in patients with normal to mildly impaired renal function; 211 patients with angiographically proven SCF and 219 controls were studied. Patients were categorized based on the angiographic findings as with or without SCF. We used the Modification of Diet in Renal Disease equation to calculate eGFR. The frequency of mildly decreased eGFR, serum uric acid levels, and eGFR was higher in the SCF group. Patients with mildly impaired renal function had higher thrombolysis in myocardial infarction frame counts in 3 major coronary arteries. In logistic regression analysis, uric acid (odds ratio [OR] = 1.323, 95% confidence interval [CI] = 1.109-1.572, P = .002) and eGFR (OR = 0.972, 95% CI = 0.957-0.987, P < .001) were independent correlates of SCF. In conclusion, eGFR was significantly correlated with SCF in patients with normal to mildly impaired renal function.

The coronary slow flow phenomenon: characteristics, mechanisms and implications

The coronary slow flow phenomenon (CSFP) is an important, angiographic entity characterized by delayed progression of the injected contrast medium through the coronary tree. It is a frequent finding, typically observed in patients presenting with acute coronary syndromes. Although it is well known to interventional cardiologists for approximately four decades, the pathogenic mechanisms remain unclear. The clinical implications are significant, with over 80% of patients experiencing recurrent chest pain, resulting in considerable impairment in quality of life. This article will address in detail the characteristics, possible mechanisms, and clinical implications of this entity to provide further insight into its clinical significance and management strategies.

The effect of age on the paraoxonase and arylesterase activity of pregnant mothers and their infants

AIM

The study aimed to research the effect of maternal age at pregnancy on the paraoxonase (PON) and arylesterase activity levels of mothers and infants.

METHOD

The study comprised 30 mothers aged more than 35 years and their infants, and 30 mothers aged under 25 years and their infants. All pregnancies had been of 38-42 weeks with normal spontaneous vaginal birth. PON and arylesterase activities were measured using paraoxon and phenylacetate substrates.

RESULTS

When the PON and arylesterase enzyme activities were compared, the PON and arylesterase activity of the mothers aged more than 35 years was found to be statistically significantly lower compared to that of the mothers aged under 25 years (P = 0.006 and P = 0.03, respectively), while there was no statistically significant difference in PON and arylesterase enzyme activity between the two groups of infants (P > 0.05).

CONCLUSION

While the PON and arylesterase enzyme activity of the mothers aged more than 35 years was found to be significantly lower compared to that of the mothers aged under 25 years, there was no statistical significance between the infants. This can be explained by the reduced PON and arylesterase enzyme activity during pregnancies at an older age, although this did not affect the PON and arylesterase enzyme activity of the infants.

Paraoxonase 1, atherosclerosis and arterial stiffness in renal patients

Atherosclerosis is an important contributor to increased cardiovascular burden in populations with and without renal disease. Paraoxonases (PON) are a group of enzymes that hydrolyse organophosphates. Recent evidence indicates a protective role for PON in patients with coronary artery disease and atherosclerosis. Although data are limited, the low enzyme activity found in patients with chronic kidney disease and renal transplants has been linked to atherosclerosis and arterial stiffness. In this paper, we review the emerging role of PON1 in the pathophysiology of atherosclerosis and arterial stiffness in patients with chronic kidney disease.

Effects of paraoxonase activity and gene polymorphism on coronary vasomotion

Background

Paraoxonase 1 [PON1] is recognized as a protective enzyme against LDL oxidation, and PON1 polymorphism has been described as a factor influencing coronary heart disease [CHD] free survival. As coronary vasoreactivity is a surrogate of future cardiovascular events, we aimed at assessing the respective effect of the PON1 genotype and activity on coronary vasoreactivity in a population of type 2 diabetic patients.

Methods

Nineteen patients with type 2 diabetes mellitus underwent ⁸²Rb cardiac PET/CT to quantify myocardial blood flow [MBF] at rest, during cold pressor testing [CPT], and during adenosine-induced hyperaemia to compute myocardial flow reserve [MFR]. They were allocated according to Q192R and L55M polymorphisms into three groups (wild-type and LM/QR heterozygotes, MM homozygotes, and RR homozygotes) and underwent a measurement of plasmatic PON1 activity. Relations between rest-MBF, stress-MBF, MFR, and MBF response to CPT and PON1 genotypes and PON1 activity were assessed using Spearman's correlation and multivariate linear regression analysis.

Results

Although PON1 activity was significantly associated with PON1 polymorphism (p < 0.0001), there was no significant relation between the PON1 genotypes and the rest-MBF, stress-MBF, or MBF response to CPT (p ≥ 0.33). The PON1 activity significantly correlated with the HDL plasma level (ρ = 0.63, p = 0.005), age (ρ = -0.52, p = 0.027), and MFR (ρ = 0.48, p = 0.044). Moreover, on multivariate analysis, PON1 activity was independently associated with MFR (p = 0.037).

Conclusion

Our study supports an independent association between PON1 activity and MFR. Whether PON1 contributes to promote coronary vasoreactivity through its antioxidant activity remains to be elucidated. This putative mechanism could be the basis of the increased risk of CHD in patients with low PON1 activity.

Serum paraoxonase activity is associated with variants in the PON gene cluster and risk of Alzheimer disease

Previous studies have shown association of single nucleotide polymorphisms (SNPs) in 3 contiguous genes (PON1, PON2, and PON3) encoding paraoxonase with risk of Alzheimer disease (AD). We evaluated the association of serum paraoxonase activity measured by phenyl acetate (PA) and thiobutyl butyrolactone (TBBL) with risk of AD and with 26 SNPs spanning the PON gene cluster in 266 AD cases and 306 sibling controls from the MIRAGE study. The odds of AD (adjusted for age, gender, and ethnicity) increased 20% for each standard deviation decrease in PA or TBBL activity. There were association signals with activity in all 3 genes. Haplotypes including SNPs spanning the PON genes were generally more significant than haplotypes comprising SNPs from 1 gene. Significant interactions were observed between SNP pairs located across the PON cluster with either serum activity measure as the outcome, and between several PON SNPs and PA activity with AD status as the outcome. Our results suggest that low serum paraoxonase activity is a risk factor for AD. Furthermore, multiple variants in PON influence serum paraoxonase activity and their effects may be synergistic.

Coronary slow flow phenomenon: a local or systemic disease?

Coronary slow flow phenomenon (CSFP) is an important, angiographic entity characterized by delayed progression of the contrast medium injected into the coronary tree. Since definition of this phenomenon in 1972, there has not been any clear-cut etiology. Original data often focused on histological or pathological changes in coronary artery itself. It was confirmed that small vessel structural defect as well as an underlying residual microvascular resistance abnormality coexists in the coronary microcirculation. Early atherosclerosis was also detected in epicardial coronary arteries by intravascular ultrasound (IVUS). Taken together, it can be suggested that a combination of morphological and functional abnormalities in small vessels and epicardial coronary arteries contributes to the pathogenesis of CSFP. CSFP may be defined as a local disease confined to coronary arteries. However, another feature of CSFP is its frequent occurrence in association with more widespread vascular abnormalities. Reduced endothelial function is implicated in CSFP as measured by flow-mediated dilatation (FMD) of the brachial artery, suggesting that endothelial dysfunction appears to be a generalized process affecting both coronary and peripheral vasculature. In addition, several studies have now demonstrated that carotid intima-media thickness (IMT) is significantly increased in patients with CSFP and there was a significant correlation between coronary intima-media thickness and carotid IMT. Therefore, we hypothesize that CSFP is not an isolated finding but may be part of a systemic vascular disturbance. CSFP is not an infrequently detected finding typically observed in patients presenting with an acute coronary syndrome, usually unstable angina. The subsequent clinical course is characterized by high frequency of relapsing chest pain resulting in considerable impairment in quality of life. Accordingly, further experimental investigations and clinical studies are warranted to shed light into the pathogenesis as well as therapeutics of CSFP.

Paraoxonase variants relate to 10-year risk in coronary artery disease: impact of a high-density lipoprotein-bound antioxidant in secondary prevention

OBJECTIVES

We investigated the effects of paraoxonase (PON)-1 variants on long-term clinical outcome in patients with coronary artery disease (CAD).

BACKGROUND

PON-1 is a potential therapeutic target to further reduce cardiovascular risk because it is a detoxifying esterase with antioxidant properties. The PON-1 knockout models result in higher susceptibility to atherosclerosis, and PON activity contributes to cardiovascular risk in humans. Human gene variants determine PON activity; however, the impact of these variants on recurrent cardiovascular events in vascular disease is as of yet unknown.

METHODS

We conducted a 10-year follow-up study of 793 CAD patients in the REGRESS (REgression GRowth Evaluation Statin Study) trial cohort, using nationwide registries. Genotypes were obtained of 2 PON-1 isotypes (L55M, rs854560, and Q192R, rs662), which were previously associated with PON activity. Absolute and relative risks by genotype were estimated using Kaplan-Meier and proportional hazards analyses.

RESULTS

Carriership of the PON-1 glutamine isotype at codon 192 and methionine at codon 55 was associated with a higher risk of death due to ischemic heart disease. Hazard ratios per allele copy were 1.71 (95% confidence interval: 1.0 to 2.8, p=0.03) for the glutamine isotype at codon 192 and 1.56 (95% confidence interval: 1.1 to 2.3, p=0.03) for methionine at codon 55. Both isotypes had previously been related to lower PON activity. No effect was observed on all-cause mortality.

CONCLUSIONS

PON-1 gene variants influence the 10-year risk of fatal complications from CAD in male patients, despite no effect on all-cause mortality. These long-term findings confirm functional data on PON-1 activity, emphasize the relevance of this pathway in vascular disease, and enforce its putative role as a target to modify and estimate cardiovascular risk.

Decreased paraoxonase and arylesterase activities in the pathogenesis of future atherosclerotic heart disease in women with gestational diabetes mellitus

OBJECTIVE

The aim of this study was to investigate serum paraoxonase, arlyesterase activities, and lipid hydroperoxide (LOOH) levels in patients with gestational diabetes mellitus (GDM).

METHODS

Paraoxonase and arylesterase activities, and LOOH levels were assessed for GDM cases (n = 55) and controls (n = 59). Serum basal and salt-stimulated paraoxonase and arylesterase activities were measured spectrophotometrically. LOOH levels were measured by ferrous oxidation with a xylenol orange assay.

RESULTS

Basal and salt-stimulated paraoxonase and arylesterase activities were significantly lower (p = 0.002, p = 0.004; and p = 0.013, respectively) in patients with GDM compared to controls, while LOOH levels were significantly higher (p < 0.001). Among gestational diabetes patients, serum paraoxonase and arylesterase activities were inversely correlated with LOOH levels (r = - 0.390, p = 0.003; and r = - 0.287, p = 0.034, respectively).

CONCLUSIONS

Findings of the present study have shown that serum paraoxonase and arylesterase activities are significantly reduced in women with GDM. Decreased serum paraoxonase and arylesterase activities might play a role in the potential early pathogenesis for atherosclerotic heart disease in GDM beyond their antioxidant properties.

Vitamin C attenuates hypochlorite-mediated loss of paraoxonase-1 activity from human plasma

Paraoxonase 1 (PON1) is a cardioprotective enzyme associated with high-density lipoprotein (HDL). We tested the hypothesis that vitamin C protects HDL and PON1 from deleterious effects of hypochlorous acid, a proinflammatory oxidant. In our experiments, HDL (from human plasma) or diluted human plasma was incubated with hypochlorite in either the absence (control) or presence of vitamin C before measuring chemical modification and PON1 activities. Vitamin C minimized chemical modification of HDL, as assessed by lysine modification and accumulation of chloramines. In the absence of vitamin C, chloramines accumulated to 114 +/- 4 micromol/L in HDL incubated with a 200-fold molar excess of hypochlorite; but addition of vitamin C (200 micromol/L) limited formation to 36 +/- 6 micromol/L (P < .001). In plasma exposed to hypochlorite, IC(50) values of 1.2 +/- 0.1, 9.5 +/- 1.0, and 5.0 +/- 0.6 mmol/L were determined for PON1's phosphotriesterase, arylesterase, and (physiologic) lactonase activities, respectively. Vitamin C lessened this inhibitory effect of hypochlorite on PON1 activities. In plasma supplemented with vitamin C (400 micromol/L), PON1 phosphotriesterase activity was 72% +/- 17% of normal after incubation with hypochlorite (2 mmol/L), compared with 42% +/- 6% for unsupplemented plasma (P < .05). Similar effects were seen for other PON1 activities. In some experiments, vitamin C also appeared to reverse hypochlorite-mediated loss of PON1 phosphotriesterase activity; but this effect was not observed for the other PON1 activities. In conclusion, vitamin C attenuated hypochlorite-mediated loss of PON1 activity in vitro and may, therefore, preserve cardioprotective properties of HDL during inflammation.

Association of paraoxonase activity and coronary collateral flow

OBJECTIVES

Paraoxonase is a high-density lipoprotein-bound antioxidant enzyme that inhibits atherosclerosis and endothelial dysfunction. Coronary collateral flow is a crucial clinical entity with significant impact on the cardiovascular morbidity and mortality. This study sought to determine the relationship between the degree of angiographically visible coronary collateral circulation and serum paraoxonase activity.

METHODS

The study population included 98 patients (mean age=57.9+/-10.1 years, 65 men) with angiographically documented total occlusion in one of the major coronary arteries. Development of collaterals was classified by Rentrop's method. Patients were defined as having poorly developed collaterals for Rentrop grades 0 and 1 or well-developed collaterals for Rentrop grades 2 and 3. Serum paraoxonase and arylesterase activities were measured spectrophotometrically.

RESULTS

Statistically significant differences between well and poorly developed collateral groups in respect to serum low-density lipoprotein cholesterol level (P=0.046), and serum paraoxonase (P=0.001), and arylesterase (P=0.014) activities were present. Serum low-density lipoprotein cholesterol level (chi=4.15, beta=-0.347, P=0.032) and serum paraoxonase activity (chi=10.43, beta=0.008, P=0.022) were independent predictors of well-developed coronary collateral flow. Serum paraoxonase activity gradually increased from collateral grade 0 to collateral grade 3 (analysis of variance P=0.003). Serum paraoxonase (r=0.362 and P<0.001) and arylesterase (r=0.245 and P=0.015) activities were both correlated with collateral flow grade.

CONCLUSION

Findings of this study suggest that serum paraoxonase activity is independently associated with the degree of coronary collateral flow and reduced serum paraoxonase activity might represent a biochemical marker of impaired coronary collateral flow.