PON1 Status Research Articles

PON1 Status in Relation to Gulf War Illness: Evidence of Gene-Exposure Interactions from a Multisite Case-Control Study of 1990-1991 Gulf War Veterans.

Deployment-related neurotoxicant exposures are implicated in the etiology of Gulf War illness (GWI), the multisymptom condition associated with military service in the 1990-1991 Gulf War (GW). A Q/R polymorphism at position 192 of the paraoxonase (PON)-1 enzyme produce PON1192 variants with different capacities for neutralizing specific chemicals, including certain acetylcholinesterase inhibitors. We evaluated PON1192 status and GW exposures in 295 GWI cases and 103 GW veteran controls. Multivariable logistic regression determined independent associations of GWI with GW exposures overall and in PON1192 subgroups. Exact logistic regression explored effects of exposure combinations in PON1192 subgroups. Hearing chemical alarms (proxy for possible nerve agent exposure) was associated with GWI only among RR status veterans (OR = 8.60, p = 0.014). Deployment-related skin pesticide use was associated with GWI only among QQ (OR = 3.30, p = 0.010) and QR (OR = 4.22, p < 0.001) status veterans. Exploratory assessments indicated that chemical alarms were associated with GWI in the subgroup of RR status veterans who took pyridostigmine bromide (PB) (exact OR = 19.02, p = 0.009) but not RR veterans who did not take PB (exact OR = 0.97, p = 1.00). Similarly, skin pesticide use was associated with GWI among QQ status veterans who took PB (exact OR = 6.34, p = 0.001) but not QQ veterans who did not take PB (exact OR = 0.59, p = 0.782). Study results suggest a complex pattern of PON1192 exposures and exposure-exposure interactions in the development of GWI.

Longitudinal changes of oxidative stress and PON1 lactonase activity and status in older pregnant women undergoing assisted reproductive technology: a prospective nested case-control study

BackgroundChildbearing in women with advanced maternal age (AMA) has increased the need for artificial reproductive technology (ART). ART and oxidative stress are associated with many pregnancy complications. Paraoxonase (PON) 1 is one of the key components responsible for antioxidative activity in high-density lipoprotein (HDL). This study aimed to investigate the longitudinal changes of oxidative stress and PON1 lactonase activity and status in older women undergoing ART.MethodsThis prospective nested case-control study included 129 control and 64 ART women. Blood samples were obtained respectively at different stages of pregnancy. PON1 level and lactonase activity were assessed using 7-O-diethylphosphoryl-3-cyano-4-methyl-7-hydroxycoumarin (DEPCyMC) and 5-thiobutyl butyrolactone (TBBL) as a substrate, respectively. A normalized lactonase activity (NLA) was estimated based on the ratio of TBBLase to DEPCyMCase activity. Serum total oxidant status (TOS), total antioxidant capacity (TAC), malondialdehyde (MDA), homocysteine (HCY), PON1 C-108T and Q192R genetic polymorphisms, and metabolic parameters were analyzed.ResultsLactonase activity and level of PON1 gradually decreased with pregnancy progression, while glycolipid metabolism parameters and TAC levels increased with pregnancy progression or significantly raised during the 2nd and 3rd trimesters, and NLA of PON1, TOS, OSI, MDA, and HCY significantly increased before delivery in the ART and control groups. Compared with the control women, the ART women had substantially higher or relatively high lactonase activity and NLA of PON1 and TAC during pregnancy; higher triglyceride (TG), total cholesterol, low-density lipoprotein cholesterol, atherogenic index, apolipoprotein (apo) B, and apoB/apoA1 ratio in the 1st trimester; and higher fasting glucose, fasting insulin, homeostatic model assessment of insulin resistance, and TG levels before delivery. No significant differences were found in the frequencies of PON1 C-108T and Q192R genotypes and alleles between the ART and control groups.ConclusionsWomen with AMA undergoing ART had higher TAC, PON1 lactonase activity, and PON1 NLA than control women, suggesting increased compensatory antioxidant capacity in ART women, thus showing higher sensitivity to oxidative stress-related injury and diseases.

Paraoxonase 1 status is a major Janus-faced component of mild and moderate acute ischemic stroke and consequent disabilities.

This study aims to examine the associations between paraoxonase 1 (PON)1 status and acute ischemic stroke (AIS) and consequent disabilities. This study recruited 122 patients with AIS and 40 healthy controls and assessed the Q192R gene variants, arylesterase (AREase) and chloromethyl phenylacetate (CMPAase) activities, and high-density lipoprotein cholesterol (HDLc) in baseline conditions. AREase and CMPAase were measured 3 months later. The National Institutes of Health Stroke Scale (NIHSS) and the modified Rankin score (mRS) were assessed at baseline and 3 and 6 months later. Reduced CMPAase and increased AREase activities are significantly associated with AIS and mRS and NIHSS scores (baseline and 3 and 6 months later). The best predictor of AIS/disabilities was a decrease in the z-unit-based composite zCMPAase-zAREase score. Serum high density lipoprotein cholsterol (HDLc) was significantly correlated with CMPAase, but not AREase, activity and a lowered zCMPAase + zHDLc score was the second best predictor of AIS/disabilities. Regression analysis showed that 34.7% of the variance in baseline NIHSS was explained by zCMPAase-zAREase and zCMPAase + zHDLc composites, HDLc, and hypertension. Neural network analysis showed that stroke was differentiated from controls with an area under the ROC curve of 0.975 using both new composite scores, PON1 status, hypertension, dyslipidemia, previous stroke as body mass index. The PON1 Q192R genotype has many significant direct and mediated effects on AIS/disabilities, however, its overall effect was not significant. PON1 status and the CMPAase-HDLc complex play key roles in AIS and its disabilities at baseline and 3 and 6 months later.

Paraoxonase and vitamin D status in subjects with elevated LDL

Introduction and Aim: Of the various causes for atherosclerosis vitamin D deficiency/insufficiency is well-known. Low levels of vitamin D are linked to alterations in certain markers of cardiovascular disease risk. Paraoxonase (PON-1) protects against CVD by preventing the oxidation of LDL as well as HDL. Reports on the correlation of PON-1 and vitamin-D status are very few. The present study assessed the correlation of PON1 and vitamin-D status in subjects with elevated LDL levels. Materials and Methods: Serum samples of subjects with elevated LDL were assessed for lipid profile, vitamin-D and Paraoxonase. Vitamin D and lipid profile were estimated using COBAS auto-analyzer. Paraoxonase activity was assessed by the spectrophotometric method. 60 subjects with elevated LDL were taken as test and 30 with normal LDL were taken as the control group. Results: Reduction in PON1 activity coupled with low HDL cholesterol and vitamin-D levels was seen in subjects with elevated LDL. Negative correlation of basal PON-1 with LDL was seen in the test group. The control group showed a negative association of Paraoxonase with HDL and a positive association with Vitamin D. Conclusion: Elevated LDL along with vitamin-D deficiency enhances the risk of atherosclerosis. Future interventional studies (dietary supplements and drugs) leading to the enhancement of the PON-1 activity and lower LDL may give more insights on its anti-oxidant role.

A Novel Pathway Phenotype of Temporal Lobe Epilepsy and Comorbid Psychiatric Disorders: Results of Precision Nomothetic Medicine.

No precision medicine models of temporal lobe epilepsy (TLE) and associated mental comorbidities have been developed to date. This observational study aimed to develop a precision nomothetic, data-driven comorbid TLE model with endophenotype classes and pathway phenotypes that may have prognostic and therapeutical implications. We recruited forty healthy controls and 108 TLE patients for this research and assessed TLE and psychopathology (PP) features as well as oxidative stress (OSTOX, e.g., malondialdehyde or MDA, lipid hydroperoxides, and advanced oxidation protein products) and antioxidant (paraoxonase 1 or PON1 status, -SH groups, and total radical trapping potential or TRAP) biomarkers. A large part (57.2%) of the variance in a latent vector (LV) extracted from the above TLE and PP features was explained by these OSTOX and antioxidant biomarkers. The PON1 Q192R genetic variant showed indirect effects on this LV, which were completely mediated by PON1 activity and MDA. Factor analysis showed that a common core could be extracted from TLE, PP, OSTOX and antioxidant scores, indicating that these features are manifestations of a common underlying construct, i.e., a novel pathway phenotype of TLE. Based on the latter, we constructed a new phenotype class that is characterized by increased severity of TLE, PP and OSTOX features and lowered antioxidant defenses. A large part of the variance in episode frequency was explained by increased MDA, lowered antioxidant, and nitric oxide metabolite levels. In conclusion, (a) PP symptoms belong to the TLE phenome, and the signal increased severity; and (b) cumulative effects of aldehyde formation and lowered antioxidants determine epileptogenic kindling.

Increased Levels of Plasma Tumor Necrosis Factor-α Mediate Schizophrenia Symptom Dimensions and Neurocognitive Impairments and Are Inversely Associated with Natural IgM Directed to Malondialdehyde and Paraoxonase 1 Activity.

Accumulating evidence suggests that TNF-α-mediated immune-neurotoxicity contributes to cognitive impairments and the overall severity of schizophrenia (OSOS). There are no data whether peripheral IL-6 and IL-4 may affect the phenome of schizophrenia above and beyond the effects of TNF-α and whether those cytokines are regulated by lowered natural IgM to malondialdehyde (MDA) and paraoxonase 1 enzyme activity. We assessed the aforementioned biomarkers in a cross-sectional study that enrolled schizophrenia patients with (n = 40) and without (n = 40) deficit schizophrenia and 40 healthy controls. Deficit schizophrenia was best predicted by a combination of increased IL-6 and PON1 status (QQ genotype and lowered CMPAase activity) and lowered IgM to MDA. Partial least squares bootstrapping shows that 41.0% of the variance in negative symptoms, psychosis, hostility, excitation, mannerism, psychomotor retardation, and formal thought disorders was explained by increased TNF-α and PON1 status (QQ genotype and lowered CMPAase activity), which lowered IL-4 and IgM to MDA as well as male sex and lowered education. We found that 47.9% of the variance in verbal fluency, word list memory, true recall, Mini-Mental State Examination, and executive functions was predicted by increased TNF-α and lowered IL-4, IgM to MDA, and education. In addition, both TNF-α and IL-4 levels were significantly associated with lowered IgM to MDA, while TNF-α was correlated with PON1 status. These data provide evidence that the symptomatic (both the deficit subtype and OSOS) and cognitive impairments in schizophrenia are to a large extent mediated by the effects of immune-mediated neurotoxicity as well as lowered regulation by the innate immune system.

Voltammetric appraisal of PON1’s activities: a preliminary study

Introduction: The human serum paraoxonase 1 (EC. 3.1.8.1, PON1) is a high-density lipoprotein associated endogenous free-radical scavenging system with arylesterase (ARase), lactonase (LOase) and paraoxonase (POase) activities [1]. PON1 has been linked to several pathological conditions, such as atherosclerosis, cardiovascular diseases, and neurodegenerative disorders [1]. Additionally, it acts as a protective agent against xenobiotic toxicity, through its ability to hydrolyse organophosphate derivates [1]. Therefore, the monitorization of each PON1 activity is of great interest in clinical, environmental and warfare contexts. Electrochemical-based sensing methods are ideal for PON1 activity assessment since many of the involved reactants are electroactive. Furthermore, these methods are highly attractive for point-of-care testing applications and on-site analysis, due to their simplicity, low-cost, sensitivity, selectivity and a high degree of miniaturization. Previously, we reported a cyclic voltammetry assay for POase activity determination using ethyl-paraoxon as substrate [2]. We now turn to the LOase and AREase activities, using homocysteine thiolactone (HcyTl) and phenylacetate (PA) as the respective substrates [3,4], for the appraisal of PON1 status by voltammetric techniques. Materials and methods: Recombinant wild-type like PON1 (rePON1) G3C9 was expressed in E. coli BL21 and purified according to [5]. In the electrochemical assays, pyrolytic graphite, glassy carbon and screen-printed carbon electrodes were used as working electrodes in a three-electrode configuration with Ag/AgCl reference and platinum/carbon counter electrodes. Enzymatic reactions were analyzed between the potential window (−0.8; 1 V), at 50 mV s−1. Results: The hydrolysis of HcyTl in the presence of rePON1 (LOase activity) was not observed in any condition tested. In contrast, PA was found to be quickly hydrolysed, as showed by an increase in the oxidation current intensity associated to the product formation (phenol). Discussion and conclusions: These preliminary results show that in wild-type like rePON1 G3C9, the AREase activity is the one with the highest turn-over, since the hydrolysis of the PA occurred almost instantly, while the reaction with ethyl-paraoxon (POase) took a few minutes [2] to produce a measurable current signal variation, and the hydrolysis of HcyTl (LOase) was not measurable at all, over a time course of 18 hours.

Lowered plasma paraoxonase (PON)1 activity is a trait marker of major depression and PON1 Q192R gene polymorphism–smoking interactions differentially predict the odds of major depression and bipolar disorder

BackgroundMajor depression and bipolar disorder are accompanied by the activation of immune-inflammatory and Oxidative and Nitrosative Stress (O&NS) pathways and lowered levels of antioxidants. Paraoxonase (PON)1 (EC 3.1.8.1) is an antioxidant bound to High Density Lipoprotein (HDL). Polymorphisms in the PON1 Q192R coding sequence determine three functional genotypes, i.e. 192QQ, 192QR and 192RR. AimsThis study was carried out to delineate the associations of plasma PON1 activity and functional PON1 Q192R genotypes in major depression and bipolar disorder. MethodsPON1 status that is plasma PON1 abundance and three functional PON1 Q192R genotypes were assayed in 91 major depressed and 45 bipolar patients and compared to 199 normal controls. ResultsMajor depression, but not bipolar disorder, was accompanied by lowered PON1 activity. PON1 activity was decreased by smoking and a diagnosis by genotype interaction (i.e. lower PON1 in major depression with the QQ genotype). Logistic regression showed that smoking by QQ genotype significantly increased the odds of bipolar disorder and that major depression was predicted by plasma PON1 activity, serum HDL cholesterol and interactions between genotype×smoking. DiscussionThe results suggest that lowered plasma PON1 activity is a trait marker of major depression and that PONQ192R gene–environment (smoking) interactions differentially predict the odds of depression and bipolar disorder. LimitationsAssociation studies are prone to a risk of false positive findings and replication is essential. ConclusionsThe findings suggest that there are differential PON1 Q192R functional genotype×environment interactions in major depression and bipolar disorder. The effects of lowered PON1 activity may contribute to increased O&NS and immune-inflammatory burden in depression. PON1 status may contribute to the comorbidity between depression and other immune- and O&NS-related disorders, e.g. cardiovascular disorder.

OP12 Association between the rs12255372 (G/T) polymorphism of the transcription factor 7 like-2 gene and type 2 diabetes in a Cameroonian population

CIMT was higher in men than women in women (0.95 vs. 0.80 mm) and in diabetic than non-diabetic subjects (0.98 vs. 0.77 mm) both p 0.227), nor linear trend in its distribution across BMI categories. Overall, CIMT correlated negatively with all indices of antioxidant activity and positively with the measures of lipid oxidation. Sex, age, BMI and diabetes were significantly associated with, and explained 29.2% of, CIMT. None of the indices of PON1 and antioxidant status was significantly associated with CIMT in the presence of the four basic variables. Conclusion: Although indices of PON1 and oxidative status correlate with CIMT, their measurement for the purpose of CVD risk stratification has no utility in this population.

The salt stimulation property of serum paraoxonase (PON1) could be a valuable factor in evaluating the enzyme status in ischemic stroke: The role of activity-determined PON1 192Q/R phenotypes

Variability in the activity and function of serum paraoxonase (PON1) as an antioxidant enzyme involved in vascular disease has been observed. In this study, we investigated the enzyme activity parameters, based on the 192Q/R polymorphism, using the salt stimulation property of PON1 as an important although neglected property. In total, 172 participants, including 90 control subjects and 82 patients with ischemic stroke were enrolled. Paraoxonase activity (para), arylesterase activity (aryl) and salt-stimulated paraoxonase activity (para-Na) were measured by spectrophotometric assays. The distribution of the 192Q/R phenotypes was determined using the dual substrate method. We observed that the para-percent (percentage stimulation of paraoxonase activity by NaCl) was significantly lower in the patients than in the controls, in both the QR+RR group (p=0.01) and QQ phenotypes (p=0.001). More than the other parameters, para-percent and para-degree (para-Na-para) are affected by ischemic stroke (p<0.001). In R-containing phenotypes, significant correlations were observed between both aryl and para, with age (r=−0.364, p=0.016; and r=−0.333, p=0.029, respectively). The salt stimulation properties of PON1 activity, particularly the parameters para-percent and para-degree, could be considered more important than the prevalent activities of the enzyme, and could be better applied for the assessment of PON1 status in ischemic stroke rather than the common enzyme activities.

Indices of paraoxonase and oxidative status do not enhance the prediction of subclinical cardiovascular disease in mixed-ancestry South Africans.

We evaluated the association of indices of paraoxonase (PON1) and oxidative status with subclinical cardiovascular disease (CVD) in mixed-ancestry South Africans. Participants were 491 adults (126 men) who were stratified by diabetes status and body mass index (BMI). Carotid intima-media thickness (CIMT) was used as a measure of subclinical CVD. Indices of PON1 and oxidative status were determined by measuring levels and activities (paraoxonase and arylesterase) of PON1, antioxidant activity (ferric reducing antioxidant power and trolox equivalent antioxidant capacity), and lipid peroxidation markers (malondialdehyde and oxidized LDL). Diabetic subjects (28.9%) displayed a significant decrease in PON1 status and antioxidant activity as well as increase in oxidized LDL and malondialdehyde. A similar profile was apparent across increasing BMI categories. CIMT was higher in diabetic than nondiabetic subjects (P < 0.0001) but showed no variation across BMI categories. Overall, CIMT correlated negatively with indices of antioxidant activity and positively with measures of lipid oxidation. Sex, age, BMI, and diabetes altogether explained 29.2% of CIMT, with no further improvement from adding PON1 and/or antioxidant status indices. Though indices of PON1 and oxidative status correlate with CIMT, their measurements may not be useful for identifying subjects at high CVD risk in this population.

PON1 status evaluation in patients with chronic arterial occlusion of lower limbs due to atherosclerosis obliterans.

IntroductionHuman paraoxonase (PON1) is a calcium-dependent enzyme physically associated with HDL, and it is believed to contribute to the atheroprotective effect of HDL. The aim of the study was to evaluate PON1 status in patients with atherosclerosis obliterans as an effect of ischemia regarding its activity and phenotype distribution.Material and methodsThe study group consisted of patients with chronic arterial occlusion of the lower limbs due to atherosclerosis obliterans (AO). The patients were divided into two groups according to the degree of ischemia: moderate (MI), and critical (CI). The ratio of the hydrolysis of salt-stimulated PON1 activity to the hydrolysis of phenylacetate was used to assign individuals to one of three possible phenotypes (low activity – A, medium activity – AB, high activity – B). It was observed that PON1 arylesterase activity was affected by ischemia of the lower limbs depending on its degree.ResultsThe odds ratio and the relative risk analysis showed that the patients with moderate ischemia are much more often characterized by phenotype A than by phenotype B. The low activity phenotype A occurs over twice as often in patients with chronic ischemia of the lower limbs as in individuals from the control group (OR = 2.125; 1.96 to 3.776, p = 0.0143).ConclusionsThis study presents the low activity phenotype A in relation to the risk of ischemia of the lower limbs due to atherosclerosis and shows the potentially important role of PON1 in conclusion of the process leading to intensification of ischemia degree.

Increased Oxidant Stress and Inflammation in Patients with Chronic Schizophrenia

Background: Several lines of evidence, including postmortem studies, suggest increased oxidative stress and inflammation in patients with schizophrenia. Alteration of oxidative stress markers has been reported in schizoprenia studies, but with inconsistent results. Oxidized low-density lipoproteins (oxLDL) have been reported to be capable of eliciting neurocytotoxicity. On the other hand, paraoxonase (PON1), an arylesterase(ARE), plays a role in protection against oxidative modifications of LDL and is considered to be one of the antioxidant enzymes. There are no studies showing the changes in oxidative stress and inflammation together, nor the activities of PON1 and ARE in schizophrenic patients. In this study, we examined PON1, ARE activities and oxidative/anti-oxidative markers in patients with chronic schizophrenia and healthy controls. Methods: We recruited 30 male chronic schizophrenic patients and 30 male healthy control subjects and examined C-reactive protein(CRP), fibrinogen, PON1, ARE and plasma total antioxidant status (TAS) and total oxidant status (TOS), oxidative stress index(OSI) in both groups. Schizophrenia symptoms were assessed using the positive and negative syndrome scale (PANSS). The related routine lipid profile parameters including HDL were also examined. Results: Patients had significantly higher CRP, fibrinogen, TOS and OSI levels; but the patients and control subjects did not differ on activities of the antioxidant enzymes PON1 and ARE. Interestingly, there were not any group differences in the lipid profile parameters except the triglyceride levels, that increased significantly in the patient group. Conclusions: In the present study, reporting the ARE activities besides the PON1 activities in schizophrenic patients for the first time, we showed that PON1 and ARE enzyme activities were not statistically different in patients with chronic schizophrenia. This study provides additional evidence of increased oxidative stress and inflammation in chronic schizophrenia, but no alterations in the antioxidant status were observed. Our results suggest that other mechanisms than the high density lipoprotein(HDL)-disfunctionality, namely decreases in PON1 or ARE enzyme activities, are more important in oxidative or antioxidative pathophysiological processes in schizophrenia.

PHENOTYPE PATTERN OF SINGLE NUCLEOTIDE POLYMORPHISM OF PARAOXONASE GENE (Q192RPON1) IN TYPE 2 DIABETIC PATIENTS

We studied the input of genetic and metabolic factors (PON1 gene polymorphism — Q192RPON1 genotype and glucolypotoxicity, respectively) to formation of enzyme functional characteristics in Type 2 diabetic patients (n = 31). Phenotyping of 79 blood samples was done by using PON1 rates of hydrolysis is of paraoxon (POase activity) and diazoxon (DZOase activity). POase activity was generally lower in diabetics than in control subjects. It was also found that against the background of conservation a determinant role of Q192RPON1 genotype for its phenotype the modulating impact of metabolic disturbances (a namely significant decrease in POase activity) was verified only in patients with QR genotype, which have been characterized significant more higher POase activity vs QQ genotype.On the other hand, there were diagnosed more pronounced hormonal-metabolic disturbances related to insulin resistance and oxidative stress in QQ homozygotes vs QR heterozygotes (increase in circulating leptin levels and decrease in erythocyte gluthathionperoxidase concentrations). We also confirmed that diazoxonase / paraoxonase activities index provides PON1 phenotype and genotype and an accurate inference of PON1 genotype. Both are important parameters for determining an individual’s PON1 status in Ukrainian Type 2 diabetes population.

PON1 status and blood cholinesterases in a farmworker population exposed to organophosphate pesticides

PON1 status and blood cholinesterases in a farmworker population exposed to organophosphate pesticides

Betaine Protects Chronic Alcohol and ω‐3 PUFA‐Mediated Down‐Regulations of PON1 Gene, Serum PON1 and Homocysteine Thiolactonase Activities With Restoration of Liver GSH

Paraoxonase (PON1) is an antioxidant enzyme that prevents LDL oxidation as well as detoxifies homocysteine thiolactone (HCTL), both of which can cause atherosclerosis. Chronic alcohol (ETOH) and high omega-3 polyunsaturated fatty acids (omega-3 PUFA) consumption may affect PON1 status presumably via reactive oxygen species by depleting liver glutathione (GSH), whereas betaine may counter their effects. Therefore, we investigated the influence of ETOH, omega-3 PUFA, and betaine on liver GSH, PON1 expression, lipid score, as well as serum PON1 and HCTLase activities. Experimental rats belonging to various dietary groups were pair-fed with Lieber-DeCarli low (2.8% the dietary calories as omega3-fatty acids) and high (13.8% the dietary calories as omega3-fatty acids) menhaden fish alcohol-liquid diets with and without betaine (10 g/l diet) for 8 weeks after which liver PON1 mRNA, GSH, lipid score, and serum PON1, HCTLase, and ALT activities were measured. High omega-3 PUFA decreased liver PON1 mRNA expression, serum PON1, and HCTLase activity by 23% (p < 0.01), 20% (p < 0.05), and 28% (p < 0.05), respectively compared to the low omega-3 PUFA group. ETOH decreased PON1 mRNA expression by 25 and 30% (p < 0.01) with concomitant 27% (p < 0.05) and 38% (p < 0.01), decrease in liver GSH levels in low and high omega-3 PUFA groups, respectively. Correspondingly, serum PON1 activity decreased by 23% (p < 0.05) and 58% (p < 0.01) while serum HCTLase activity decreased by 25% (p < 0.05) and 59% (p < 0.01) in the low and high omega-3 PUFA ETOH groups, respectively. Betaine restored liver PON1 mRNA expressions in low and high omega-3 PUFA ETOH groups with parallel restorations of PON1 activity and liver GSH. Concomitantly, betaine reduced hepatosteatosis accompanied by alleviation of liver injury caused by chronic alcohol and high omega-3 PUFA. Based on these results, we conclude that dietary betaine not only atheroprotective by restoring liver GSH that quenches free radicals, but also may alleviate liver injury by reducing hepatosteatosis.

Paraoxonase status and plasma butyrylcholinesterase activity in chlorpyrifos manufacturing workers

Chlorpyrifos is an organophosphorus (OP) anticholinesterase insecticide. Paraoxonase (PON1) is an enzyme found in liver and plasma that hydrolyzes a number of OP compounds. PON1 polymorphisms include a glutamine (Q)/arginine (R) substitution at position 192 (PON1(Q192R)) that affects hydrolysis of OP substrates, with the PON1(192Q) allotype hydrolyzing chlorpyrifos oxon less efficiently than the PON1(192R) allotype, a variation potentially important in determining susceptibility to chlorpyrifos. We studied 53 chlorpyrifos workers and 60 referents during 1 year and estimated chlorpyrifos exposure using industrial hygiene and employment records and excretion of the chlorpyrifos metabolite 3,5,6-trichloro-2-pyridinol (TCP). Plasma butyrylcholinesterase (BuChE) activity, which may by inhibited by chlorpyrifos exposure, was measured monthly. In addition, plasma samples were assayed for paraoxonase (PONase), diazoxonase (DZOase), and chlorpyrifosoxonase (CPOase) activity to determine PON1 status (inferred genotypes and their functional activity). Linear regression analyses modeled BuChE activity as a function of chlorpyrifos exposure and covariates. We postulated that the level of CPOase activity and the inferred PON1(192) genotype (together reflecting PON1 status) would differ between groups and that PON1 status would modify the models of chlorpyrifos exposure on BuChE activity. Chlorpyrifos workers and referents had a 100-fold difference in cumulative chlorpyrifos exposure. Contrary to our hypotheses, mean CPOase activity was similar in both groups (P=0.58) and PON1(192Q) showed a slight overrepresentation, not an underrepresentation, in the chlorpyrifos group compared with referents (PON1(192QQ), 51% chlorpyrifos, 40% referent; PON(192QR), 43% chlorpyrifos, 40% referent; PON(192RR), 6% chlorpyrifos, 20% referent, P=0.08). In our models, BuChE activity was significantly inversely associated with measures of interim chlorpyrifos exposure, but the biological effects of chlorpyrifos exposure on BuChE activity were not modified by PON1 inferred genotype or CPOase activity.

Low human paraoxonase predicts cardiovascular events in Japanese patients with type 2 diabetes

Human serum paraoxonase (PON1) is associated with HDL and inhibits oxidative modification of LDL. PON1 enzymatic activity has been shown to decrease in diabetic patients; however, the effect of PON1 status on long-term outcome has not been reported. In this study, we examined the association between baseline PON1 status and the development of cardiovascular disease (CVD) during 10 years of follow-up in 88 type 2 diabetic patients whose enzymatic activities, concentrations, and genetic polymorphisms of PON1 had been determined. A total of 20 CVD events were recorded during the follow-up period. Using Kaplan-Meier survival curves, we found a significantly increased incidence of CVD in patients with a lower concentration or paraoxonase activity of PON1 than each median value (log-rank 7.460; P < 0.01, and log-rank 4.187; P < 0.05, respectively). By Cox regression analysis, both concentration and paraoxonase activity were significantly associated with the development of CVD, even after correction for gender, age, and preexisting CVD (P < 0.05). Low concentration and enzymatic activity of PON1 may be an independent predictor of cardiovascular events in diabetic patients.

Human serum paraoxonase concentration predicts cardiovascular mortality in hemodialysis patients

Human serum paraoxonase (PON1) is associated with high-density lipoprotein, and inhibits oxidative modification of low-density lipoprotein. Therefore, PON1 is supposed to contribute to the prevention of atherosclerosis. We and other investigators have shown that the enzymatic activities and concentrations of PON1 were decreased in maintenance hemodialysis (HD) patients. However, the effect of PON1 status on the long-term outcome of HD patients has not been reported. In this study, we examined the association between baseline PON 1 status and cardiovascular mortality in an observation study of an outpatient HD population. The relation between baseline cardiovascular risk factors and clinical events was investigated, during 6 years of follow-up, in 81 HD patients (50 males and 31 females) whose enzymatic activities, concentrations and genetic polymorphisms of PON1 had been determined in a previous study. During follow-up for 6 years, we recorded 42 deaths, including 24 fatal cardiovascular events. In univariate analyses, baseline PON1 concentration was associated with not only cardiovascular mortality (p < 0.005), but also all-cause mortality (p < 0.001) during the period of follow-up, as were age, preexisting cardiovascular disease (CVD) and hemoglobin concentration. In a multivariate Cox regression analysis, PON1 concentration retained significant associations with cardiovascular mortality (p < 0.05) and all-cause mortality (p < 0.005) even after correction of known risk factors for CVD or mortality in HD patients. Using Kaplan-Meier survival curves, we assessed the association between low and high concentrations of PON1 divided according to the median value (7.52 U/ml). Significantly increased cardiovascular mortality (log rank 6.125, p = 0.01) and all-cause mortality (log rank 7.113, p < 0.01) were detected in the patients with low PON1 concentrations. These data suggest that low PON 1 concentration may be an independent predictor of cardiovascular mortality in maintenance HD patients.

PON1 status of farmworker mothers and children as a predictor of organophosphate sensitivity

The objective was to determine PON1 status as a predictor for organophosphorus insecticide sensitivity in a cohort of Latina mothers and newborns from the Salinas Valley, California, an area with high levels of organophosphorus insecticide use. PON1 status was established for 130 pregnant Latina women and their newborns using a high-throughput two substrate activity/analysis method which plots rates of diazoxon (DZO) hydrolysis against rates of paraoxon (PO) hydrolysis. Arylesterase activity (AREase) was determined using phenylacetate as a substrate, allowing comparison of PON1 levels across PON1192 genotypes in mothers and children. Phenylacetate hydrolysis is not affected by the Q192R polymorphism. Among newborns, levels of PON1 (AREase) varied by 26-fold (4.3-110.7 U/ml) and among mothers by 14-fold (19.8-281.4 U/ml). On average, children's PON1 levels were four-fold lower than the mothers' PON1 levels (P<0.001). Average PON1 levels in newborns were comparable with reported hPON1 levels in transgenic mice expressing human PON1Q192 or PON1R192, allowing for prediction of relative sensitivity to chlorpyrifos oxon (CPO) and DZO. The predicted range of variability in sensitivity of mothers and children in the same Latino cohort was 65-fold for DZO and 131 to 164-fold for CPO. Overall, these findings indicate that many of the newborns and some of the mothers in this cohort would be more susceptible to the adverse effects of specific organophosphorus pesticide exposure due to their PON1 status. Of particular concern are exposures of pregnant mothers and newborns with low PON1 status.