Electroanatomical mapping improves procedural outcomes of cryoballoon pulmonary vein isolation (the Achieve Plus study).

BACKGROUND: Validation of pulmonary vein (PV) isolation (PVI) using only the Achieve catheter following cryoballoon ablation (CBA) is imperfect since pulmonary vein potentials (PVP) can be recorded in only 50-85% of the veins and residual PVP are found in up to 4.3-7.6% of the isolated veins in remapping studies. OBJECTIVE: To study if addition of electroanatomical mapping to Achieve catheter-guided CBA is superior for PVI. METHODS: One hundred patients were randomized between Achieve catheter-guided CBA (control group; N = 50) and Achieve catheter-guided CBA with additional EnSite voltage maps performed pre- and post-CBA (Achieve Plus group; N = 50). Confirmation of PVI was done by circular mapping catheter (CMC) and EnSite mapping by a second blinded operator. RESULTS: Despite apparent PVI in all PVs after CBA, incomplete PVI was present in 0 out of 50 patients (0%) and 0 out of 204 PVs in the Achieve Plus group versus 6 patients out of 50 (12%; P = 0.012) and 6 out of 203 PVs (3%; P = 0.013) in the control group. All 6 non-isolated PVs could be successfully isolated by additional cryoapplications. Procedure time was longer in the Achieve Plus group (75.76 ± 21.65 vs 66.06 ± 16.83 min; P = 0.014) with equal fluoroscopy times (14.85 ± 6.41 vs 14.33 ± 8.55; P = 0.732). CONCLUSION: The addition of electroanatomical EnSite mapping to the Achieve catheter improves the PVI rate of CBA and could be considered for future use. Design and Results of the Achieve Plus study. The Achieve Plus study shows that the addition of electro-anatomical EnSite mapping to the Achieve catheter improves PVI rate of CBA and could be considered for future use. See text for further explanation. ABBREVIATIONS: CBA: cryoballoon ablation; PVI: pulmonary vein isolation.

Creatinine adjustment of biological monitoring results.

BACKGROUND: Biological monitoring (BM) aids exposure assessment but where this is based on incomplete collections of single urine voiding measurement of creatinine is often used to adjust analyte concentrations for the effects of fluid balance. AIMS: To provide reference data on creatinine concentrations in urine samples from a population of UK workers. METHODS: Urine samples sent to the Health and Safety Laboratory were analysed for creatinine by an automated kinetic Jaffe technique using alkaline picric acid and the results stored in a database. Statistical analysis of the data used linear mixed effects models on the natural log-transformed data. RESULTS: Between 1996 and 2007, the laboratory analysed 49 506 urine samples from 20 433 UK adult workers. In the 42 817 samples where gender was known, 93% were from men and 7% were from women. The overall mean and median creatinine concentrations were both 12 mmol/l corresponding to 1.36 g/l. The mean (13 mmol/l) and median (12 mmol/l) creatinine concentrations for men were higher than those (9 and 10 mmol/l, respectively) for women. CONCLUSIONS: Gender differences in creatinine concentrations and the range of 0.3-3.0 g/l (2.653 and 26.53 mmol/l) traditionally used for confirming acceptability of urine samples mean that 2.5% of samples from male and 9% from female workers were flagged as 'low creatinine' and required a repeat sample. In addition, care should be taken interpreting any apparent gender differences in BM results to ensure that they are due to exposure and not an artefact of creatinine adjustment.

A survey of occupational exposure to 4,4'-methylene-bis (2-chloroaniline) (MbOCA) in the UK.

OBJECTIVES: The main objective of the study was to gather information about the current controls and levels of exposure to 4,4'-methylene-bis (2-chloroaniline) (MbOCA) in a representative cross section of workplaces that use it to manufacture polyurethane elastomers. The study also aimed to investigate whether controls and guidance could be improved and to investigate exposure to isocyanates in these workplaces using biological monitoring. METHODS: An occupational hygienist and a field scientist visited the two UK suppliers and 20 out of the 25 workplaces known to be using MbOCA in the UK during 2005 and 2006. They collected air samples, surface wipes, gloves, and urine samples and made observations to assess exposure and the adequacy of controls. All samples were analysed for MbOCA and urine samples were additionally analysed for isocyanate metabolites. A statistical analysis was made of the results. RESULTS: Only 2.5% of the 80 personal inhalation exposures to MbOCA exceeded the workplace exposure limit of 5 microg m(-3) 8-h time-weighted average and 84% were below the limit of detection (LOD). Surface samples (n = 334) were collected from MbOCA users and suppliers and 60% had detectable levels of MbOCA ranging from 0.019 to 400 microg cm(-2). The highest levels were around a hopper, ovens, and the weighing and pouring areas. MbOCA was also detected in 8 of the 75 samples collected from areas not likely to be in contact with MbOCA. At the two suppliers, samples (n = 28) were collected from the outside surfaces of recently imported kegs, pallets, and the floor around kegs. Six samples had detectable levels and four of these (0.2, 0.8, 1, and 6 microg cm(-2)) were from the floor and pallets in both suppliers. The other two positive results were found on the outside rim (18 microg cm(-2)) and side (23 microg cm(-2)) of a keg at one supplier indicating contamination by the manufacturer. Urine samples (n = 79) were collected and 49% were below the LOD for MbOCA and only three samples had levels of MbOCA that exceeded the biological monitoring guidance value (BMGV) of 15 micromol mol(-1) creatinine. The highest urinary MbOCA concentrations were in samples from workers casting and moulding. The 90th percentile of the urine MbOCA results was 8.6 micromol MbOCA per mol creatinine. Urine samples were also analysed for the diamine metabolites of toluene diisocyanate and hexamethylene diisocyanate and 33% had detectable levels with 22 and 13% of results, respectively, above the BMGV for isocyanates (1 micromol isocyanate-derived diamine per mol creatinine). The maximum urinary concentration of toluene diamine and hexane diamine were 15.6 and 10.1 micromol mol(-1) creatinine, respectively. CONCLUSIONS: The survey found that the measures used to control exposure to MbOCA could be improved. Although air levels of MbOCA were generally low, there was evidence of spread of surface contamination and poor maintenance of controls such as local exhaust ventilation. A BMGV based on the 90th percentile of data from workplaces with good control would be less than the 90% value of 8.6 micromol mol(-1) creatinine found in this study and suggests that the current BMGV of 15 micromol mol(-1) creatinine is no longer acting as a stimulus to reduce exposure. The metabolites of isocyanates found in urine samples in this study could arise from inhalation exposure to isocyanates or from dermal exposure to either isocyanates or their diamine breakdown product and need further investigation.

Biomonitoring at the UK Health and Safety Laboratory.

The UK Health and Safety Laboratory (HSL) provides research and analytical support to the Health and Safety Executive, other Government Departments and employers. In the area of biomonitoring HSL conducts research studies and provides an analytical service for regular surveillance of worker exposure to hazardous substances. This paper gives brief examples of how data from such studies can be used to develop biological monitoring guidance values for isocyanates, polycyclic aromatic hydrocarbons and hexavalent chromium. In addition, a study of occupational exposure to copper chrome arsenic wood preservatives is briefly described to show how biological monitoring can be used for post-approval surveillance of a biocide.

Background levels of key biomarkers of chemical exposure within the UK general population--pilot study.

The use of biomarkers is now an accepted measure of chemical uptake (possibly exposure) in risk assessment. However, information on background exposures and biomarker concentrations of many environmental chemicals in the general UK population is limited. This study aims to determine reference ranges for eleven biomarkers of chemical exposure, measurable in urine, within the general adult UK population. The study will involve 400 volunteers throughout the UK and is currently underway. Described here is a pilot study, carried out during August and September 2005 to test the study methodology. The initial results of the postal survey and urinary concentrations for cadmium (UCd) and mercury (UHg) are reported. A total of 78 individuals were recruited by post from the UK Electoral Register, to take part in the pilot study. Participants were asked to complete a questionnaire and provide a urine sample. The overall response rate was 16%, of which 60.3% were female and 39.7% male. Those living in suburban areas accounted for 60% of respondents, current smokers 12.8% and vegetarians 1.3%. Levels of UCd were higher in females compared to males and smoking status influenced levels; smokers displayed higher levels of UCd than individuals who had previously smoked or who had never smoked. The mean, median and range of UHg was 1.12, 0.55 (

Physiologically based pharmacokinetic modelling of human exposure to 2-butoxyethanol.

A physiologically based pharmacokinetic (PBPK) model describing the disposition of 2-butoxyethanol (2-BE) was developed in order to predict the urinary concentration of its major metabolite, butoxyacetic acid (BAA) under a range of exposure scenarios. Based on Corley et al. [Corley, R.A., Bormett, G.A., Ghanayem, B.I., 1994. Physiologically based pharmacokinetics of 2-butoxyethanol and its major metabolite, 2-butoxyacetic acid, in rats and humans. Toxicol. Appl. Pharmacol. 129, 61-79], the model included such features as multiple entry routes into the body, varying workload conditions, metabolism in the liver and elimination of free BAA in urine by glomerular filtration and acid transport. A bladder compartment simulating the fluctuations in metabolite concentration in urine caused by micturition formed a novel aspect of the model. Good agreement between model predictions and existing experimental data of total BAA levels in the blood and urine over various exposure conditions were observed. The mechanistically based PBPK model allowed comparison of disparate studies and also enabled the prediction of urinary concentrations of BAA post-shift. By calculating the total amount of BAA, any inter-individual variability in conjugation is taken into account. This led us to conclude that a biological monitoring guidance value should be proposed for total rather than free BAA with a value of 250 mmol/mol of creatinine (post-shift), based on an 8h exposure to 25 ppm 2-BE at resting working conditions.

Towards a biological monitoring guidance value for acrylamide.

Acrylamide is classified as a potential human carcinogen and neurotoxicant. Biological monitoring is a useful tool for monitoring worker exposure. However, other sources of exposure to acrylamide (including cigarette smoke and diet) also need to be considered. This study has performed repeat measurements of the urinary mercapturic acids of acrylamide (AAMA) and its metabolite glycidamide (GAMA) and determined globin adducts in 20 production-plant workers at a UK acrylamide production facility. The relationship between biomarker levels and environmental monitoring data (air levels and hand washes) was investigated. Good correlations were found between all of the biomarkers (r(2)=0.86-0.91) and moderate correlations were found between the biomarkers and air levels (r(2) = 0.56-0.65). Our data show that urinary AAMA is a reliable biomarker of acrylamide exposure. Occupational hygiene data showed that acrylamide exposure at the company was well within the current UK Workplace Exposure Limit. The 90th percentile of urinary AAMA in non-smoking production-plant workers (537 µmol/mol creatinine (n = 59 samples)) is proposed as a possible biological monitoring guidance value. This 90th percentile increased to 798 µmol/mol if smokers were included (n = 72 samples). These values would be expected following an airborne exposure of less than 0.07 mg/m(3), well below the current UK workplace exposure limit of 0.3mg/m(3). Comparison of biomarker levels in non-occupationally exposed individuals suggests regional variations (between UK and Germany), possibly due to differences in diet.

Correlation between high-molecular-weight Fc gamma-receptor-blocking factors in serum and renal allograft survival.

In this study, we have demonstrated the occurrence of IgG class noncytotoxic, lymphocyte Fc gamma-receptor-blocking antibodies in a proportion of sera obtained from transfused uremic patients. The presence of these antibodies was not found to correlate with subsequent renal allograft survival. Serum fractionation studies did however reveal a striking correlation between graft survival and Fc gamma-receptor blocking mediated by a serum factor(s) with a sedimentation coefficient of greater than 19S. The precise nature of this factor remains to be clarified.

Consistency in the histological diagnosis of epithelial abnormalities of the cervix uteri.

A group of pathologists, all working in the same laboratory and all applying the same diagnostic criteria to the diagnosis of epithelial abnormalities in the uterine cervix, have studied the consistency with which they have applied these criteria. Epithelial abnormalities were ranked, and a series of sections were diagnosed separately by each pathologist at various times over a number of years. Both consistency and trend were studied by a graphed statistical method and it was shown that not only were there serious inconsistencies in diagnosis between the various pathologists but also between the diagnoses made by individual pathologists studying the same section at various times. It is suggested that this inconsistency in the application of agreed diagnostic criteria is of importance when considering discrepancies between reported series of cervical epithelial abnormalities and that the type of study described is of value in assessing both variations in diagnostic criteria between different laboratories and the consistency of pathologists in training. Any slight change in the application of diagnostic criteria for any individual pathologist with the passage of time may also be detected by this technique.

Estimation of the dermal absorption of m-xylene vapor in humans using breath sampling and physiologically based pharmacokinetic analysis.

A physiologically-based pharmacokinetic model, containing a skin compartment, was derived and used to simulate experimentally determined exposure to m-xylene, using human volunteers exposed under controlled conditions. Biological monitoring was conducted by sampling, in exhaled alveolar air and blood, m-xylene and urinary methyl hippuric acid concentrations. The dermal absorption of m-xylene vapor was successfully and conveniently studied using a breath sampling technique, and the contribution to m-xylene body burden from the dermal route of exposure was estimated to be 1.8%. The model was used to investigate the protection afforded by an air-fed, half-face mask. By iteratively changing the dermal exposure concentration, it was possible to predict the ambient concentration that was required to deliver the observed urinary excretion of methylhippuric acid, during and following inhalation exposure to 50 ppm m-xylene vapor. This latter extrapolation demonstrates how physiologically-based pharmacokinetic modeling can be applied in a practical and occupationally relevant way, and permitted a further step not possible with biological monitoring alone. The ability of the model to extrapolate an ambient exposure concentration was dependent upon human metabolism data, thereby demonstrating the mechanistic toxicological basis of model output. The methyl hydroxylation of m-xylene is catalyzed by the hepatic mixed function oxidase enzyme, cytochrome P450 2E1 and is active in the occupationally relevant, (<100 ppm) exposure range of m-xylene. The use of a scaled-up in vitro maximum rate of metabolism (Vmaxc) in the model also demonstrates the increasingly valuable potential utility of biokinetic data determined using alternative, non-animal methods in human chemical-risk assessment.

Biological monitoring of exposure to organophosphate pesticides.

Organophosphates (OPs) are readily absorbed through the skin and biological monitoring is an essential component of any comprehensive assessment of exposure. This paper presents a summary of our experience in a wide range of occupational studies. Additionally, we have conducted studies of non-occupational exposure and human volunteer studies looking at the kinetics of chlorpyrifos, propetamphos, diazinon and malathion. In non-occupationally exposed people, 95% of urinary alkyl phosphates do not exceed 72 micromol/mol creatinine. In occupationally exposed people, the corresponding 95th percentile of total urinary alkyl phosphates is 122 micromol/mol creatinine. In volunteer studies with 1 mg oral doses of chlorpyifos, diazinon and propetamphos the mean peak values were 160, 750 and 404 micromol/mol creatinine, respectively, and were not associated with any reduction in blood cholinesterase activity. The levels of OP metabolites seen in urine from workers potentially exposed to OPs are generally low and unlikely to cause significant reduction in blood cholinesterase activity.

Exposure to the organophosphate diazinon: data from a human volunteer study with oral and dermal doses.

Biological monitoring of occupational exposure to diazinon is possible by the determination of blood cholinesterase activity and by the measurement of metabolites in urine. However, there is little data to aid in the interpretation of results. This study gave oral (11 microg kg(-1) (36 nmol kg(-1)) body weight) and occluded dermal (100 mg (329 micromol)) doses of diazinon to five volunteers and analysed blood and urine samples for plasma and erythrocyte cholinesterase and urinary dialkyl phosphate (DAP) metabolites of diazinon: diethyl phosphate (DEP) and diethyl thiophosphate (DETP). Following oral and dermal exposure, peak urinary DAP levels occurred at 2 and 12 h, respectively. The apparent urinary elimination half-lives of DAP metabolites following oral and dermal exposure were approximately 2 and 9 h, respectively. Approximately 60% of the oral dose and 1% of the dermal dose was excreted as urinary DAP metabolites, with 90% of the dermal dose being recovered from the skin surface. On a group basis, there was no statistically significant mean depression in plasma or erythrocyte cholinesterase when compared with pre-exposure levels for either dosing experiment. The observed elimination kinetics of diazinon metabolites suggest a biological monitoring strategy for occupational exposure to diazinon based on urine samples collected at the end of shift.

Oral and dermal exposure to propetamphos: a human volunteer study.

Propetamphos ((E)-O-2-isopropylcarbonyl-1-methylvinyl-O-methylethyl phosphoramidothioate) is an organophosphate pesticide (OP) and has been used as an active ingredient in sheep dip where there is the potential for significant dermal exposure during dipping. Biological monitoring of exposure to propetamphos has until recently relied on the measurement of cholinesterase activity in plasma. Following the development of a novel method for the determination of propetamphos metabolites in urine, it is now possible to biologically monitor exposure using urine samples. This paper describes a human volunteer study involving oral and dermal exposure to propetamphos.

Dermal route in systemic exposure.

To evaluate risk from dermal exposure, the amount of material on the skin must first be measured. The potential for dermal uptake must then be assessed for the potential health effects from systemic exposure. No standard methods exist for studying these processes, and published data are not comparable because of the different techniques used. Future validated methodology should provide a sound scientific basis for risk assessment. Methods for measuring skin and surface contamination will require development of reference contaminated surfaces and skin as part of quality control procedures. Biological monitoring is a valuable tool in the assessment of dermal absorption, in contributing to the validation of in vitro techniques, and in risk assessment and management. It will be necessary to conduct detailed investigations to support risk assessment for dermal exposure. Ultimately, predictive models will be established for exposure and for dermal absorption to support a generic approach and allow risk assessment strategies appropriate to actual workplace situations.

A novel device for capturing breath samples for solvent analysis.

We have developed a novel breath sampling device suitable for capturing a portion of end-tidal air. This breath sample is then transferred onto a Perkin Elmer automated thermal desorption (ATD) sampling tube which is subsequently analysed by ATD-gas chromatography-mass spectrometry (GCMS). The breath sampler has been evaluated in the laboratory, in brief field trials and in human volunteer studies. The method is sensitive with a typical detection limit of 1 nmol/l and reproducible with an overall coefficient of variation between 5% and 15% for collection and analysis of breath samples from volunteers. The field trials used the sampler to assess exposure to solvents in several industries including the shoe manufacturing industry, the inks and coatings industry and at dry cleaning establishments. The sampler was found easy to use and reliable. Solvents detected include ethyl acetate (6.4-25.5 nmol/l), propan-2-ol (3.4-39.3 nmol/l), 2-butanone (0-6.6 nmol/l) and tetrachloroethene (0-557 nmol/l). The breath sampler was also used to monitor the elimination of solvents in breath from human volunteers after exposure chamber studies. More than 500 breath samples have been analysed from 24 volunteers in exposures to 10 different solvents (toluene, trimethyl benzene, tetrachloroethene, tetrahydrofuran, acetone, propan-2-ol, xylene, 2-butanone, 1-methoxy-2-propanol and n-hexane). The breath sampler allowed the rapid and non-invasive collection of data on elimination of solvents.

A biological monitoring study of 1-methoxy-2-propanol: analytical method development and a human volunteer study.

1-Methoxy-2-propanol (M2P) is finding increasing industrial use as a less toxic alternative to the short-chained ethylene glycol ethers. Like most glycol ethers, M2P is readily absorbed through the skin and biological monitoring is therefore appropriate in assessing occupational exposure. An analytical method, suitable for routine monitoring, was developed for the determination of free M2P in urine. The method involves solvent extraction, gas chromatography-mass spectrometry and is sensitive (detection limit 1 mumol/l), specific and reproducible (intra- and inter-assay coefficients of variation 5% and 9%, respectively). A human volunteer study, involving six volunteers, was also conducted. Volunteers were exposed to 100 ppm M2P for 8 h (the occupational exposure standard in the UK) including a 30-min break. Post-exposure levels of free M2P in urine were found to reach up to 110 mumol/l). Levels of M2P were also monitored in blood (maximum 103 mumol/l) and exhaled air samples (up to 252 nmol/l). The volunteer study showed that M2P is rapidly excreted in urine with a half-life of less than 2.6 h.

A GC/MS method for the determination of 4,4'-diaminodiphenylmethane and substituted analogues in urine.

A sensitive and specific gas chromatography/mass spectrometry (GC/MS) method has been developed for the analysis of 4,4'-diaminodiphenylmethane (DDM), 3-ethyl DDM (EDDM), and 3,3'-diethyl DDM (DEDDM) in urine. The method has been applied to the analysis of urine samples from workers exposed to a mixture of all three compounds, and the analysis has shown that EDDM and DEDDM are excreted in urine. We have also shown that there are two classes of conjugates present in urine. EDDM and DEDDM are excreted as heat labile conjugates, while DDM and EDDM are excreted, at least in part, as heat stable but alkaline hydrolyzable conjugates. It is proposed that the method described here could be used for biological monitoring of workers exposed to mixtures of DDM, EDDM, and DEDDM.

The effects of alcohol and diallyl sulphide on CYP2E1 activity in humans: a phenotyping study using chlorzoxazone.

The effects of acute administration of dietary levels of ethanol and the garlic oil extract, diallyl sulphide (DAS), on cytochrome P450 2E1 (CYP2E1) activity in volunteers were studied using the selective probe substrate, chlorzoxazone (CZX). The ratio of the CZX metabolite 6- hydroxychlorzoxazone (6-OHCZX) to CZX was taken to indicate CYP2E1 activity. The mean differences between the baseline and DAS-treated (0.2 mg/kg) CYP2E1 activities were significantly different (two-tailed p value = 0.0242, n = 8). Likewise, the mean differences between the baseline and ethanol-treated (0.8 g/kg) CYP2E1 activities were also significantly different (two-tailed p value = 0.0005, n = 7). The reduction in in vivo CYP2E1 activity by DAS is consistent with reported inhibition observed in vitro. The marked reduction in CYP2E1 activity following acute ingestion of ethanol is consistent with a competitive inhibition mechanism of CZX metabolism. The inhibitory effect of DAS maybe additive with daily consumption of Allium vegetables in particular. This may explain the lower 6-OHCZX/CZX metabolic ratios measured in various European and Mexican cohorts and is consistent with the lower incidence of stomach, liver and colon cancers observed in southern Europeans.

The in vitro percutaneous penetration of chlorpyrifos.

Chlorpyrifos is a widely used organophosphate pesticide. In order to study the pharmacokinetics of the penetration of chlorpyrifos through human skin we measured the percutaneous penetration of chlorpyrifos through human skin using an in vitro flow through apparatus. The chlorpyrifos was applied to the skin as a commercial concentrate or as a reference standard dissolved in ethanol. There was a significant difference (P=0.03) between the rate of penetration from the commercial concentrate (9.0 nmoles cm(-2) h(-1)) and that from the reference standard (4.9 nmoles cm(-2) h(-1)). Each experiment was run for 24 h. The recoveries from experiments where chlorpyrifos was applied to the skin as a commercial concentrate and as a reference standard dissolved in ethanol were, respectively, in total 91 and 87% of the applied dose of which 15 and 10% was recovered from the skin, 56 and 66% was recovered from the surface of the skin and 20 and 11% was recovered from the receptor fluid. There was a significant difference in the recoveries from the skin but there was no significant difference in the recoveries from the surface of the skin. We concluded that the majority of a dermal dose of chlorpyrifos was still present at or in the surface of the skin 24 h after application of a dermal dose. Because chlorpyrifos was recovered from the skin after 24 h, it is possible that the skin could act as a reservoir and release chlorpyrifos over a longer period. We also conclude that the solvent vehicle for chlorpyrifos can affect the rate of penetration of the pesticide.