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Biomedical subjects

Clement E Furlong

Publications and source records attributed to Clement E Furlong.

At least 19 recordsLinked to original sources
PubMed2007

Portable 24-analyte surface plasmon resonance instruments for rapid, versatile biodetection.

Field use of surface plasmon resonance (SPR) biosensors for environmental and defense applications such as detection and identification of biological warfare agents has been hampered by lack of rugged, portable, high-performance instrumentation. To meet this need, we have developed compact multi-analyte SPR instruments based on Texas Instruments' Spreeta sensing chips. The instruments weigh 3 kg and are built into clamshell enclosures measuring 28 cm x 22 cm x 13 cm. Functions are divided between an electronics unit in the base of the box and a fluidics assembly in the lid. Automated valves and pumps implement an injection loop flow system that allows sensors to be exposed to sample, rinsed, and treated with additional reagents (such as secondary antibodies) under computer control. Injected samples flow over the surfaces of eight sensor chips fastened into a temperature-controlled silicone flowcell. Each chip has 3 sensing regions, for a total detection of 24 areas that can be simultaneously monitored by SPR. Coating these areas with appropriate antibodies or other receptors allows a sample to be screened for up to 24 different substances simultaneously. The instruments report refractive index (RI) values every second, with a typical noise level of 1-3 x 10(-6) RI units. The design of the device is described, and performance is illustrated with detection of six distinct analytes ranging from small molecules to whole microbes during the course of a single experiment.

Biological Warfare↗
PubMed2006

Inflammatory response after influenza vaccination in men with and without carotid artery disease.

OBJECTIVE: Inflammatory markers are associated with vascular disease; however, variation in the acute phase response (APR) has not been evaluated. We evaluated whether the APR magnitude in men with severe carotid artery disease (CAAD) (>80% stenosis) differed from that of men without stenosis (<15% stenosis). METHODS AND RESULTS: White males with (n=43) and without (n=61) severe CAAD receiving clinical influenza vaccinations were recruited. Their baseline and 24-hour after -vaccination blood samples were assayed for C-reactive protein (CRP), IL-6, and serum amyloid-a (SAA). In vivo APR to vaccination was measurable and varied among subjects. Adjusted for age, smoking, oral hypoglycemics, aspirin, and stain use, the relative 24-hour changes in levels of ln(CRP), ln(IL-6), and ln(SAA) were higher in men with CAAD than in men without, but only the SAA response was significant (P=0.02); the relative SAA response was 1.6 (95% confidence interval, 1.1 to 2.5) times higher in men with than without CAAD. The APR for all markers appeared to be independent of baseline levels. CONCLUSIONS: Influenza vaccination results in a mild, but measurable, APR in men with and without CAAD. SAA APR variability may be a predictor of severe vascular disease that is independent of basal SAA level.

Acute-Phase Reaction↗
PubMed2006

TagSNP analyses of the PON gene cluster: effects on PON1 activity, LDL oxidative susceptibility, and vascular disease.

Paraoxonase 1 (PON1) activity is consistently predictive of vascular disease, although the genotype at four functional PON1 polymorphisms is not. To address this inconsistency, we investigated the role of all common PON1 genetic variability, as measured by tagging single-nucleotide polymorphisms (tagSNPs), in predicting PON1 activity for phenylacetate hydrolysis, LDL susceptibility to oxidation ex vivo, plasma homocysteine (Hcy) levels, and carotid artery disease (CAAD) status. The biological goal was to establish whether additional common genetic variation beyond consideration of the four known functional SNPs improves prediction of these phenotypes. PON2 and PON3 tagSNPs were secondarily evaluated. Expanded analysis of an additional 26 tagSNPs found evidence of previously undescribed common PON1 polymorphisms that affect PON1 activity independently of the four known functional SNPs. PON1 activity was not significantly correlated with LDL oxidative susceptibility, but genotypes at the PON1(-108) promoter polymorphism and several other PON1 SNPs were. Neither PON1 activity nor PON1 genotype was significantly correlated with plasma Hcy levels. This study revealed previously undetected common functional PON1 polymorphisms that explain 4% of PON1 activity and a high rate of recombination in PON1, but the sum of the common PON1 locus variation does not explain the relationship between PON1 activity and CAAD.

Adult↗
PubMed2006

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.

Agriculture↗
PubMed2005

A portable surface plasmon resonance sensor system for real-time monitoring of small to large analytes.

Many environmental applications exist for biosensors capable of providing real-time analyses. One pressing current need is monitoring for agents of chemical- and bio-terrorism. These applications require systems that can rapidly detect small organics including nerve agents, toxic proteins, viruses, spores and whole microbes. A second area of application is monitoring for environmental pollutants. Processing of grab samples through chemical laboratories requires significant time delays in the analyses, preventing the rapid mapping and cleanup of chemical spills. The current state of development of miniaturized, integrated surface plasmon resonance (SPR) sensor elements has allowed for the development of inexpensive, portable biosensor systems capable of the simultaneous analysis of multiple analytes. Most of the detection protocols make use of antibodies immobilized on the sensor surface. The Spreeta 2000 SPR biosensor elements manufactured by Texas Instruments provide three channels for each sensor element in the system. A temperature-controlled two-element system that monitors for six analytes is currently in use, and development of an eight element sensor system capable of monitoring up to 24 different analytes will be completed in the near future. Protein toxins can be directly detected and quantified in the low picomolar range. Elimination of false positives and increased sensitivity is provided by secondary antibodies with specificity for different target epitopes, and by sensor element redundancy. Inclusion of more than a single amplification step can push the sensitivity of toxic protein detection to femtomolar levels. The same types of direct detection and amplification protocols are used to monitor for viruses and whole bacteria or spores. Special protocols are required for the detection of small molecules. Either a competition type assay where the presence of analyte inhibits the binding of antibodies to surface-immobilized analyte, or a displacement assay, where antibodies bound to analyte on the sensor surface are displaced by free analyte, can be used. The small molecule detection assays vary in sensitivity from the low micromolar range to the high picomolar.

Biosensing Techniques↗
PubMed2005

The correlation of paraoxonase (PON1) activity with lipid and lipoprotein levels differs with vascular disease status.

Paraoxonase (PON1) is an HDL-associated enzyme. Low PON1 activity predicts vascular disease status and is a more reliable predictor of vascular disease than are functional PON1 genotypes. There is evidence that the relationship of PON1 to vascular disease is, in part, due to its antioxidant activity. However, the physical relationship of PON1 with HDL and the existence of cholesterol pathway regulatory elements at the PON1 locus suggest a further relationship of PON1 with lipoproteins, which may contribute to its role in vascular disease. We investigated the relationship of PON1 activity and genotype to lipid-related traits in 91 Caucasian men with severe carotid artery disease and 184 without vascular disease who were not on lipid-lowering medications. Prior studies of PON1 relationship to lipids have not stratified by disease status.. We found that PON1 activity was correlated with HDL traits in controls and with LDL- and VLDL-related traits in cases. We hypothesize differences in the joint regulation of PON1 and lipoproteins in cases and controls.

Adult↗
PubMed2005

Modulation of paraoxonase (PON1) activity.

Paraoxonase 1 (PON1) is a serum enzyme closely associated with high density lipoprotein (HDL). PON1 hydrolyzes several organophosphorus compounds used as insecticides, as well as nerve agents; it metabolizes toxic oxidized lipids associated with both low density lipoprotein (LDL) and HDL; and it can hydrolyze a number of lactone-containing pharmaceutical compounds, inactivating some, while activating others. Serum PON1 activity in a given population can vary by 40-fold. Though most of this variation can be explained by polymorphisms in the coding region (Q192R) and the 5' regulatory region (T-108C), modulation of PON1 by a variety of other factors should be taken into account, including other polymorphisms recently discovered but not yet characterized. This paper examines the major factors (environmental chemicals, drugs, smoking, alcohol, diet, age, disease conditions) that have been shown to modulate PON1 activity in either direction. As PON1 plays a protective role in organophosphate toxicity, and, because of its antioxidant capacity, in cardiovascular disease, a better understanding of how PON1 can be modulated by environmental factors has potential toxicological and clinical consequences.

Aging↗
PubMed2005

Measurement of paraoxonase (PON1) status as a potential biomarker of susceptibility to organophosphate toxicity.

Organophosphorus (OP) compounds are still among the most widely used insecticides, and their main mechanism of acute toxicity is associated with inhibition of acetylcholinesterase. Measurements of urine metabolites and of blood cholinesterase activity are established biomarkers of exposure to OPs and of early biological effects. In recent years, increasing attention has been given to biomarkers of susceptibility to OP toxicity. Here we discuss the polymorphisms of paraoxonase (PON1), a liver and serum enzyme that hydrolyzes a number of OP compounds, and its role in modulating the toxicity of OPs. We stress the importance of determining PON1 status, which encompasses the PON1192Q/R polymorphism (that affects catalytic ability toward different substrates) and PON1 levels (which are modulated in part by a C-108T polymorphism) over straight genotyping. Epidemiological studies on OP-exposed workers that include assessment of PON1 status to validate in human populations the role of PON1 as a determinant of susceptibility to OPs, as indicated by animal studies, are needed. Documentation of exposure and of early health effects would be most relevant to increase the predictive value of the test.

Animals↗
PubMed2005

Role of paraoxonase (PON1) status in pesticide sensitivity: genetic and temporal determinants.

Individual differences in detoxication capacities for specific organophosphorous (OP) compounds are due largely to differences in catalytic efficiency or abundance of the HDL-associated enzyme, paraoxonase (PON1). First, we provide evidence that children less than 2 years of age represent a particularly susceptible population for OP exposure due to low abundance of PON1 and variable onset of plasma PON1 activity. Second, we describe studies examining the neurotoxic effects of chronic, low-level OP pesticide exposure in mice. PON1 knockout (PON1(-/-)) and wild-type mice were exposed chronically (PN4 to PN21) to low levels of chlorpyrifos oxon (CPO). Endpoints included cholinesterase activity, histopathology, gene expression, and behavior. Even at PN4, when PON1 levels were low in wild-type mice, PON1(-/-) mice were more sensitive to inhibition of brain cholinesterase by CPO. At PN22, and persisting as long as 4 months, chronic developmental exposure to 0.18 mg/kg/d or 0.25 mg/kg/d CPO resulted in perinuclear vacuolization of cells in a discrete area of the neocortex and irregular distribution of neurons in the cortical plate, with an increase in the number of affected cells at 0.25mg/kg/d. Third, we describe a transgenic mouse model in which human transgenes encoding either hPON1Q192 or hPON1R192 were expressed at equal levels in place of mouse PON1. The developmental onset of expression followed the mouse time course and was identical for the two transgenes, allowing these mice to be used to assess the importance of the Q192R polymorphism during development. Adult mice expressing hPON1R192 were significantly more resistant than hPON1Q192 mice to CPO toxicity. Our studies indicate that children less than 2 years old, especially those homozygous for PON1Q192, would be predicted to be particularly susceptible to CPO toxicity.

Animals↗
PubMed2005

Association between in utero organophosphate pesticide exposure and abnormal reflexes in neonates.

The detrimental effects of organophosphate pesticide (OP) exposure on neurodevelopment have been shown in animals. The present study aimed to assess the relationship between in utero and early postnatal OP exposure and neonatal neurobehavior in humans, as measured by seven clusters (habituation, orientation, motor performance, range of state, regulation of state, autonomic stability, and reflex) on the Brazelton Neonatal Behavioral Assessment Scale (BNBAS). We assessed 381 infants < or = 2 months old and born to women participating in the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) study, a longitudinal, birth cohort study of low-income, Latina women living in the agricultural community of the Salinas Valley, California. Exposure to OP pesticides was determined by urinary levels of dialkylphosphate (DAP) metabolites, including dimethyl and diethylphosphate metabolites, measured twice during pregnancy (M = 14 and 26 weeks gestation) and once post-delivery (M = 7 days postpartum). The relationship between exposure and BNBAS performance was examined for the entire sample and stratified by the median age at assessment, 3 days. We observed a significant association between exposure and the reflex cluster for the entire sample and for infants >3 days old (n = 184). Among the >3 day old infants, increasing average prenatal urinary metabolite levels were associated with both an increase in number of abnormal reflexes (total DAP: adjusted beta = 0.53, 95% CI = 0.23, 0.82; dimethyls: adjusted beta = 0.41, 95% CI = 0.12, 0.69; diethyls: adjusted beta = 0.37, 95% CI = 0.09, 0.64), and the proportion of infants with more than three abnormal reflexes (total DAP: adjusted OR = 4.9, 95% CI = 1.5, 16.1; dimethyls: adjusted OR = 3.2, 95% CI = 1.1, 9.8; diethyls: adjusted OR = 3.4, 95% CI = 1.2, 9.9). No detrimental associations were found between postnatal urinary metabolite levels and any of the BNBAS clusters for infants < or = 3 or >3 days old at assessment. Whether neonatal reflex functioning is predictive of neuropsychological functioning as the child matures will continue to be evaluated in this birth cohort.

Adult↗
PubMed2005

Toxicity of chlorpyrifos and chlorpyrifos oxon in a transgenic mouse model of the human paraoxonase (PON1) Q192R polymorphism.

OBJECTIVES: The Q192R polymorphism of paraoxonase (PON1) has been shown to affect hydrolysis of organophosphorus compounds. The Q192 and R192 alloforms exhibit equivalent catalytic efficiencies of hydrolysis for diazoxon, the oxon form of the pesticide (DZ). However, the R192 alloform has a higher catalytic efficiency of hydrolysis than does the Q192 alloform for chlorpyrifos oxon (CPO), the oxon form of the pesticide chlorpyrifos (CPS). The current study examined the relevance of these observations for in-vivo exposures to chlorpyrifos and chlorpyrifos oxon. METHODS: Using a transgenic mouse model we examined the relevance of the Q192R polymorphism for exposure to CPS and CPO in vivo. Transgenic mice were generated that expressed either human PON1Q192 or PON1R192 at equivalent levels, in the absence of endogenous mouse PON1. Dose-response and time course experiments were performed on adult mice exposed dermally to CPS or CPO. Morbidity and acetylcholinesterase (AChE) activity in the brain and diaphragm were determined in the first 24 h following exposure. RESULTS: Mice expressing PON1Q192 were significantly more sensitive to CPO, and to a lesser extent CPS, than were mice expressing PON1R192. The time course of inhibition following exposure to 1.2 mg/kg CPO revealed maximum inhibition of brain AChE at 6-12 h, with PON1R192, PON1Q192, and PON1 mice exhibiting 40, 70 and 85% inhibition, respectively, relative to control mice. The effect of PON1 removal on the dose-response curve for CPS exposure was remarkably consistent with a PBPK/PD model of CPS exposure. CONCLUSION: These results indicate that individuals expressing only the PON1Q192 allele would be more sensitive to the adverse effects of CPO or CPS exposure, especially if they are expressing a low level of plasma PON1Q192.

Acetylcholinesterase↗
PubMed2005

Paraoxonase (PON1): from toxicology to cardiovascular medicine.

Paraoxonase (PON1) is a liver and plasma enzyme most studied because of its ability to hydrolyze the active metabolites of several organophosphorus insecticides. The discovery that PON1 can also metabolize oxidized phospholipids has spurred research on its possible role in coronary heart disease and atherosclerosis. Additionally, its potential roles in metabolizing pharmaceutical drugs and microbial quorum sensing factors are also being explored. PON1 displays several polymorphisms that influence both its level of expression and its catalytic activity, thus determining the rates at which a given individual will detoxify a specific insecticide, metabolize harmful oxidized lipids, and activate or inactivate specific drugs and quorum sensing factors.

Animals↗
PubMed2004

Association of in utero organophosphate pesticide exposure and fetal growth and length of gestation in an agricultural population.

Although pesticide use is widespread, little is known about potential adverse health effects of in utero exposure. We investigated the effects of organophosphate pesticide exposure during pregnancy on fetal growth and gestational duration in a cohort of low-income, Latina women living in an agricultural community in the Salinas Valley, California. We measured nonspecific metabolites of organophosphate pesticides (dimethyl and diethyl phosphates) and metabolites specific to malathion (malathion dicarboxylic acid), chlorpyrifos [O,O-diethyl O-(3,5,6-trichloro-2-pyridinyl) phosphoro-thioate], and parathion (4-nitrophenol) in maternal urine collected twice during pregnancy. We also measured levels of cholinesterase in whole blood and butyryl cholinesterase in plasma in maternal and umbilical cord blood. We failed to demonstrate an adverse relationship between fetal growth and any measure of in utero organophosphate pesticide exposure. In fact, we found increases in body length and head circumference associated with some exposure measures. However, we did find decreases in gestational duration associated with two measures of in utero pesticide exposure: urinary dimethyl phosphate metabolites [beta(adjusted) = -0.41 weeks per log10 unit increase; 95% confidence interval (CI), -0.75 -- -0.02; p = 0.02], which reflect exposure to dimethyl organophosphate compounds such as malathion, and umbilical cord cholinesterase (beta(adjusted) = 0.34 weeks per unit increase; 95% CI, 0.13-0.55; p = 0.001). Shortened gestational duration was most clearly related to increasing exposure levels in the latter part of pregnancy. These associations with gestational age may be biologically plausible given that organophosphate pesticides depress cholinesterase and acetylcholine stimulates contraction of the uterus. However, despite these observed associations, the rate of preterm delivery in this population (6.4%) was lower than in a U.S. reference population.

Adolescent↗
PubMed2003

Paraoxonase activity, but not haplotype utilizing the linkage disequilibrium structure, predicts vascular disease.

OBJECTIVE: The effects of paraoxonase (PON1) activity and of genetic variation in the PON1 promoter and coding region on carotid artery disease (CAAD) were investigated. METHODS AND RESULTS: We identified functional promoter polymorphisms and examined their effects in a cohort with and without CAAD. We used the full sequences in 23 white subjects to determine the linkage disequilibrium (LD) structure of the PON1 region and to direct the grouping of haplotypes for disease association testing. There are several discrete regions of the PON1 gene with strong local LD, but the useful levels of LD do not extend across the entire gene. Indeed, PON1-162/-108/55/192 haplotype did not predict additional variation in PON1 activities compared with the 4 genotypes separately. PON1 hydrolysis activity predicted CAAD status, but this was not attributable to the promoter or coding region polymorphisms or haplotype or to the effects of smoking or statin use on PON1 activity. CONCLUSIONS: PON1 does not have LD across the gene, and use of haplotypes in association studies should consider the LD structure. PON1 activity predicts CAAD, yet 4 functional polymorphisms do not. Additional investigations of genetic and environmental factors that influence PON1 activity as a risk factor for vascular disease are warranted.

Adult↗
PubMed2003

Polymorphisms of paraoxonase (PON1) and their significance in clinical toxicology of organophosphates.

Paraoxonase (PON1) is an HDL-associated enzyme capable of hydrolyzing multiple substrates, including several organophosphorous insecticides and nerve agents, oxidized lipids, and a number of drugs or pro-drugs. Several polymorphisms in the paraoxonase (PON1) gene have been described, which have been shown to affect either the catalytic efficiency of hydrolysis or the expression level of PON1. This review discusses the relevance of these polymorphisms for modulating sensitivity to organophosphorous compounds. Animal studies characterizing the PON1 polymorphisms have demonstrated the relevance of PON1 in modulating OP toxicity and have indicated the importance of an individual's PON1 status (i.e., genotype and phenotype taken together) rather than genotyping alone. Nevertheless, direct confirmation in humans of the relevance of PON1 status in conferring susceptibility to OP toxicity is still elusive. Recent studies examining the involvement of PON1 status in determining OP susceptibility of Gulf War veterans, sheep dippers, and individuals poisoned with chemical warfare agents represent a step in the right direction, but more studies are needed, with better documentation of both the level of exposure and the consequences of exposure.

Aryldialkylphosphatase↗
PubMed2003

Novel paraoxonase (PON1) nonsense and missense mutations predicted by functional genomic assay of PON1 status.

Paraoxonase (PON1) has been termed an environmental response enzyme for its function in the detoxification of organophosphate pesticides, nerve agents and pharmaceuticals such as glucocorticoids and statins, as well as its cardioprotective role in breaking down oxidized LDL. PON1(192) genotype can be predicted with high accuracy from an examination of the two-dimensional plot of paraoxon and diazoxon hydrolysis rates [ 1]. Individuals for whom this functional genomic assay failed to predict PON1(192) genotype, or who had a low PON activity relative to others with the same genotype, were predicted to have genetic alterations that explained the inconsistency. Sequencing of the PON1 region of 23 Caucasian individuals detected a nonsense mutation changing amino acid 194 from a Trp to a stop codon (PON1(Trp194stop)). It was predicted that subjects who genotyped as PON1(192QR) but phenotyped as PON1(192QQ) or PON1(192RR) might carry the protein truncation mutation for which the defective product failed to be detected by the phenotyping assay. Screening of the five discordant subjects resulted in the detection of a single Caucasian carrying the stop codon, and determined its phasing on the PON1(192R) allele. Sequencing confirmed the change and revealed an additional subject with a likely deletion of the 5' end of the PON1 gene. Additional sequencing of 25 subjects with low PON1 activities identified two additional previously undescribed PON1 mutations, which may affect PON1 function: PON1(Pro90Leu) associated with the PON1(192Q) allele and PON1(Asp124missplice) associated with the PON1(192R) allele.

Aryldialkylphosphatase↗