Effect of N-acetyltransferase 2 genetic polymorphism on 4,4'-methylenebis(2-chloroaniline)-induced genotoxicity and oxidative stress.

4,4'-Methylenebis(2-chloroaniline) or MOCA is an aromatic amine used primarily in polyurethane and rubber industry. MOCA has been linked to hepatomas in animal studies while limited epidemiologic studies reported the association of exposure to MOCA and urinary bladder and breast cancer. We investigated MOCA-induced genotoxicity and oxidative stress in DNA repair-deficient Chinese hamster ovary (CHO) cells stably transfected with human metabolizing enzymes CYP1A2 and N-acetyltransferase 2 (NAT2) variants as well as in rapid, intermediate, and slow NAT2 acetylator cryopreserved human hepatocytes. N-acetylation of MOCA was highest in UV5/1A2/NAT2*4 followed by UV5/1A2/NAT2*7B and UV5/1A2/NAT2*5B CHO cells. Human hepatocytes showed a NAT2 genotype-dependent response with highest N-acetylation in rapid acetylators followed by intermediate and slow acetylators. MOCA induced higher levels of mutagenesis and DNA damage in UV5/1A2/NAT2*7B compared to UV5/1A2/NAT2*4 and UV5/1A2/NAT2*5B cells (p < 0.0001). MOCA also induced higher levels of oxidative stress in UV5/1A2/NAT2*7B cells. MOCA caused concentration-dependent increase in DNA damage in cryopreserved human hepatocytes (linear trend p < 0.001) which was NAT2 genotype dependent i.e., highest in rapid acetylators, lower in intermediate acetylators, and lowest in slow acetylators (p < 0.0001). Our findings show that N-acetylation and genotoxicity of MOCA is NAT2 genotype dependent and suggest that individuals possessing NAT2*7B are at higher risk to MOCA-induced mutagenicity. DNA damage, and oxidative stress. They confirm significant differences in genotoxicity between the NAT2*5B and NAT2*7B alleles, both of which are associated with slow acetylator phenotype.

Determining the Neurocognitive Status and the Functional Ability of Patients to Screen for HIV-Associated Neurocognitive Disorder (HAND)

BACKGROUND AND PURPOSE: To adequately evaluate the extent of neurocognitive impairment in patient living with human immunodeficiency virus (PLHIV), a battery of neuropsychological tests is typically administered which are neither cost effective nor time efficient in the outpatient clinical setting. The aim of the study was to assess neurocognitive status and functional ability of people living with HIV and find a brief screening tool to identify those who would benefit from a full diagnostic evaluation.METHODS: The study enrolled 160 PLHIV (80 pre-antiretroviral therapy [ART] and 80 on ART) fulfilling the inclusion and exclusion criteria. Neurocognitive assessment and an assessment of Functional ability was done by using the Montreal Cognitive Assessment (MoCA) and Lawton and Brody Instrumental Activities of Daily Living Scale scale, respectively.RESULTS: The study population consisted of 75.6% males and 24.4% females with mean age of 44±10 years. The overall prevalence of HIV associated neurocognitive disorder (HAND) in the study subjects was 52.5%. Of these, 47.5% had asymptomatic neurocognitive impairment and 5% had minor neurocognitive disorder. In MoCA, the most frequently affected domains were Language (97.6%), visuospatial ability (92.9%) and memory (71.4%).CONCLUSIONS: The prevalence of HAND in both groups were similar suggesting that neurocognitive impairment starts early in HIV infection. Memory and Visuospatial function impairment had the most predictive potential for detecting the presence of HAND. HAND screening is recommended in all PLHIV at enrolment into care. Simple tools like MoCA can be used in busy outpatient settings by healthcare workers to screen for HAND.

Validation Study of the Chinese Version of Addenbrooke's Cognitive Examination III for Diagnosing Mild Cognitive Impairment and Mild Dementia

BACKGROUND AND PURPOSE: There are only a few cognitive screening tests for the Chinese-speaking population, and so this study aimed to validate the Chinese version of Addenbrooke's Cognitive Examination III (ACE-III) for detecting mild cognitive impairment (MCI) and mild dementia. Its diagnostic accuracy was compared with the Chinese versions of the Mini Mental State Examination (MMSE) and the Montreal Cognitive Assessment (MoCA). METHODS: The 176 included individuals were divided into 3 groups: mild dementia group, MCI group, and normal control group. MMSE, MoCA, and ACE-III were administered to all participants by researchers who were blinded to the clinical grouping. The receiver operating characteristic (ROC) curves were analyzed. RESULTS: ACE-III exhibited good internal consistency and convergent validity. Age and education level significantly influenced the total ACE-III scores. When screening MCI, the area under the ROC curve (AUC) was significantly larger for ACE-III than for MMSE (0.88 vs. 0.72, p<0.05) and MoCA (0.88 vs. 0.76, p<0.05). ACE-III showed higher sensitivity (0.75) and specificity (0.89) than MMSE (0.64 and 0.63, respectively) and MoCA (0.67 and 0.77) at the optimal cutoff score of 88/89. For detecting mild dementia, ACE-III yielded satisfactory sensitivity (0.94) and specificity (0.83) at the optimal cutoff score of 74/75. The AUC of ACE-III was 0.95, which was comparable to those of MMSE (0.95) and MoCA (0.91). In participants with ≥12 years of education, the AUC was significantly larger for ACE-III than for MMSE when detecting MCI (0.90 vs. 0.68, p<0.05) and mild dementia (0.97 vs. 0.90, p<0.05). CONCLUSIONS: The present study has verified that ACE-III is a reliable and accurate tool for screening MCI and mild dementia in the Chinese-speaking population, and is significantly superior to MMSE and MoCA for detecting MCI.

The Effect of Daily Low Dose Tadalafil on Cerebral Perfusion and Cognition in Patients with Erectile Dysfunction and Mild Cognitive Impairment

OBJECTIVE: The aims of this study were to investigate the effects of daily low-dose tadalafil on cognitive function and to examine whether there was a change in cerebral blood flow (CBF) in patients with erectile dysfunction (ED) and mild cognitive impairment. METHODS: Male patients aged 50 to 75 years with at least three months of ED (International Index of Erectile Function [IIEF]-5 score ≤ 21) and mild cognitive impairment (Montreal Cognitive Assessment [MoCA] score ≤ 22) were included in the study. The subjects were prescribed a low-dose PDE5 inhibitor (tadalafil 5 mg) to be taken once daily for eight weeks. Changes in MoCA score and single-photon emission computed tomography (SPECT) study between the two time-points were assessed by paired t tests. RESULTS: Overall, 30 male patients were assigned to the treatment group in this study and 25 patients completed the eight-week treatment course. Five patients were withdrawn due to adverse events such as myalgia and dizziness. Mean baseline IIEF and MoCA scores were 7.52 ± 4.84 and 18.92 ± 1.78. After the eight-week treatment, mean IIEF and MoCA scores were increased to 12.92 ± 7.27 (p < 0.05) and 21.8 ± 1.71 (p < 0.05), respectively. Patients showed increased relative regional CBF in the postcentral gyrus, precuneus, and brainstem after tadalafil administration versus at baseline (p < 0.001). CONCLUSION: The results of this prospective clinical study suggest that daily use of tadalafil 5 mg increases some regional CBF and improves cognitive function in patients with ED and mild cognitive impairment.

Combined Measures of Psychomotor and Cognitive Alterations as a Potential Hallmark for Bipolar Depression

OBJECTIVE: The current study aimed to examine whether specific features of psychomotor retardation (PMR) and cognitive functioning established different profiles in unipolar (UD) and bipolar depression (BD).METHODS: Two groups of age-matched patients with UD (n=54) and BD (n=20) completed the Montgomery-Asberg Depression Rating Scale (MADRS/60), the Montreal Cognitive Assessment (MoCA/30), and the Salpêtrière Retardation Rating Scale (SRRS/60). We analyzed the group effect and then performed intra-group analyses.RESULTS: The BD patients have higher SRRS score, and lower MoCA score than UD despite no difference on the level of depression between UD and BD. Our results show that PMR can be predicted by the level of depression in UD and by the cognitive alteration and onset of disease in BD.CONCLUSION: PMR is a relevant marker of depression. Our results highlight the importance of concomitant evaluation of psychomotor and cognitive functions in the distinction of UD and BD symptoms.

Role of N-acetyltransferase 2 acetylation polymorphism in 4, 4'-methylene bis (2-chloroaniline) biotransformation.

Arylamine N-acetyltransferase 1 (NAT1) and 2 (NAT2) catalyze the acetylation of arylamine carcinogens. Single nucleotide polymorphisms in the NAT2 coding exon present in NAT2 haplotypes encode allozymes with reduced N-acetyltransferase activity towards the N-acetylation of arylamine carcinogens and the O-acetylation of their N-hydroxylated metabolites. NAT2 acetylator phenotype modifies urinary bladder cancer risk following exposures to arylamine carcinogens such as 4-aminobiphenyl. 4, 4'-methylene bis (2-chloroaniline) (MOCA) is a Group 1 carcinogen for which a role of the NAT2 acetylation polymorphism on cancer risk is unknown. We investigated the role of NAT2 and the genetic acetylation polymorphism on both MOCA N-acetylation and N-hydroxy-MOCA O-acetylation. MOCA N-acetylation exhibited a robust gene dose response in rabbit liver cytosol and in cryopreserved human hepatocytes derived from individuals of rapid, intermediate and slow acetylator NAT2 genotype. MOCA exhibited about 4-fold higher affinity for recombinant human NAT2 than NAT1. Recombinant human NAT2*4 (reference) and 15 variant recombinant human NAT2 allozymes catalyzed both the N-acetylation of MOCA and the O-acetylation of N-hydroxy-MOCA. Human NAT2 5, NAT2 6, NAT2 7 and NAT2 14 allozymes catalyzed MOCA N-acetylation and N-hydroxy-O-acetylation at rates much lower than the reference NAT2 4 allozyme. In conclusion, our results show that NAT2 acetylator genotype has an important role in MOCA metabolism and suggest that risk assessments related to MOCA exposures consider accounting for NAT2 acetylator phenotype in the analysis.

Validation of the Conversion between the Mini-Mental State Examination and Montreal Cognitive assessment in Korean Patients with Parkinson's Disease

OBJECTIVE: Two conversion tables between the Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) have recently been established for Parkinson’s disease (PD). This study aimed to validate them in Korean patients with PD and to evaluate whether they could be influenced by educational level. METHODS: A total of 391 patients with PD who undertook both the Korean MMSE and the Korean MoCA during the same session were retrospectively assessed. The mean, median, and root mean squared error (RMSE) of the difference between the true and converted MMSE scores and the intraclass correlation coefficient (ICC) were calculated according to educational level (6 or fewer years, 7–12 years, or 13 or more years). RESULTS: Both conversions had a median value of 0, with a small mean and RMSE of differences, and a high correlation between the true and converted MMSE scores. In the classification according to educational level, all groups had roughly similar values of the median, mean, RMSE, and ICC both within and between the conversions. CONCLUSION: Our findings suggest that both MMSE-MoCA conversion tables are useful instruments for transforming MoCA scores into converted MMSE scores in Korean patients with PD, regardless of educational level. These will greatly enhance the utility of the existing cognitive data from the Korean PD population in clinical and research settings.

Validation of MoCA-MMSE Conversion Scales in Korean Patients with Cognitive Impairments

BACKGROUND AND PURPOSE: Two conversion scales between the Mini-Mental State Examination (MMSE) and the Montreal Cognitive Assessment (MoCA) have been validated for Korean patients with Parkinson's disease. The aim of the present study was to validate these conversion scales for all patients with cognitive impairments regardless of dementia subtype. METHODS: Medical records of 323 subjects who completed both MMSE and MoCA on the same day were retrospectively reviewed. Mean, median, and root mean squared error (RMSE) of the difference between true and equivalent MMSE scores were calculated. Intraclass correlation coefficients (ICCs) between true and equivalent MMSE scores were also calculated. The validity of MoCA-MMSE conversion scales was evaluated according to educational level (low educated: ≤6 years; high educated: ≥7 years) and subtypes of cognitive impairment. RESULTS: The difference between true and equivalent MMSE scores had a median value of 0, a mean value of 0.19 according to the van Steenoven scale, a mean value of 0.57 according to the Lawton scale, RMSE value of 2.2 according to the van Steenoven scale, and RMSE value of 0.42 according to the Lawton scale. Additionally, ICCs between true and equivalent MMSE scores were 0.92 and 0.90 on van Steenovan and Lawton conversion scales, respectively. These results were maintained in subgroup analyses. CONCLUSIONS: Findings of the present study suggest that both van Steenovan and Lawton MoCA-MMSE conversion scales are applicable to transforming MoCA scores into MMSE scores in patients with cognitive impairments regardless of dementia subtype or educational level.

An 8-Week Low-Intensity Progressive Cycling Training Improves Motor Functions in Patients with Early-Stage Parkinson's Disease

BACKGROUND AND PURPOSE: The effects of high-intensity cycling as an adjuvant therapy for early-stage Parkinson's disease (PD) were highlighted recently. However, patients experience difficulties in maintaining these cycling training programs. The present study investigated the efficacy of cycling at a mild-to-moderate intensity in early-stage PD. METHODS: Thirteen PD patients were enrolled for 16 serial cycling sessions over a 2-month period. Motor function was assessed using the Unified Parkinson's Disease Rating Scale part III (UPDRS III) and Timed Up and Go (TUG) test as primary outcomes. The Montreal Cognitive Assessment (MoCA), modified Hoehn and Yahr Stage (mHYS), total UPDRS, Falls Efficacy Scale, New Freezing of Gait Questionnaire, Schwab and England Activities of Daily Living, 39-item Parkinson's Disease Questionnaire, Patient Global Impression of Change, and gait performance were assessed as secondary outcomes. RESULTS: The age and the age at onset were 59.67±7.24 and 53.23±10.26 years (mean±SD), respectively. The cycling cadence was 53.27±8.92 revolutions per minute. The UPDRS III score improved significantly after 8 training sessions (p=0.011) and 16 training sessions (T2) (p=0.001) in the off-state, and at T2 (p=0.004) in the on-state compared to pretraining (T0). The TUG duration was significantly shorter at T2 than at T0 (p < 0.05). The findings of MoCA, total UPDRS, double limb support time, and mHYS (in both the off- and on-states) also improved significantly at T2. CONCLUSIONS: Our pioneer study has demonstrated that a low-intensity progressive cycling exercise can improve motor function in PD, especially akinesia. The beneficial effects were similar to those of high-intensity rehabilitation programs.

Effect of CYP3A4 genetic polymorphisms on the genotoxicity of 4,4'-methylene-bis(2-chloroaniline)-exposed workers.

OBJECTIVES: We investigated the relationship between 4,4'-methylene-bis(2-chloroaniline) (MBOCA) exposure and micronucleus (MN) frequency, and how this association was affected by genetic polymorphism of the cytochrome P450 enzyme (CYP3A4). METHODS: We divided the study population into an exposed group (n=44 with total urine MBOCA ≥20 µg/g creatinine) and a control group (n=47 with total urine MBOCA <20 µg/g creatinine). Lymphocyte MN frequency (MNF) and micronucleated cell (MNC) frequency were measured by the cytokinesis-block MN assay method. MNF reported as the number of micronuclei in binucleated cells per 1000 cells, and MNC reported as the number of binucleated cells with the presence of MN per 1000 cells. CYP3A4 alleles were measured by PCR-based restriction fragment length polymorphism (PCR-RFLP). RESULTS: The mean MNF (6.11 vs 4.46 MN/1000 cells, p<0.001) and MNC (5.75 vs 4.15 MN/1000 cells, p<0.001) in the exposed workers was significantly higher than that in the controls. The CYP3A4 polymorphism A/A+A/G influenced the difference in the mean MNF (5.97 vs 4.38 MN/1000 cells, p<0.001) and MNC (5.60 vs 4.15 MN/1000 cells, p<0.001) between the MBOCA-exposed and control groups. After adjusting risk factors, the MNF level in the MBOCA-exposed workers was 0.520 MN cells/1000 cells (p<0.001) higher than the control group among the CYP3A4 A/A+A/G genotype. Similarly, the MNC level in the MBOCA-exposed workers was 0.593 MN/1000 cells (p<0.001) higher than the control group among the CYP3A4 A/A+A/G genotype. However, the difference in adjusted MNF and MNC between the exposed and control groups was not significant for the CYP3A4 polymorphism with the G/G genotype. CONCLUSIONS: We recommend that lymphocytes MNF and MNC are good indicators to evaluate MBOCA genotoxicity. Individuals with the CYP3A4 polymorphism A/A and A/G genotypes appear to be more susceptible to MBOCA genotoxicity.

The MMSE and MoCA for Screening Cognitive Impairment in Less Educated Patients with Parkinson's Disease

OBJECTIVE: To explore whether the Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) can be used to screen for dementia or mild cognitive impairment (MCI) in less educated patients with Parkinson's disease (PD). METHODS: We reviewed the medical records of PD patients who had taken the Korean MMSE (K-MMSE), Korean MoCA (K-MoCA), and comprehensive neuropsychological tests. Predictive values of the K-MMSE and K-MoCA for dementia or MCI were analyzed in groups divided by educational level. RESULTS: The discriminative powers of the K-MMSE and K-MoCA were excellent [area under the curve (AUC) 0.86–0.97] for detecting dementia but not for detecting MCI (AUC 0.64–0.85). The optimal screening cutoff values of both tests increased with educational level for dementia (K-MMSE < 15 for illiterate, < 20 for 0.5–3 years of education, < 23 for 4–6 years, < 25 for 7–9 years, and < 26 for 10 years or more; K-MoCA < 7 for illiterate, < 13 for 0.5–3 years, < 16 for 4–6 years, < 19 for 7–9 years, < 20 for 10 years or more) and MCI (K-MMSE < 19 for illiterate, < 26 for 0.5–3 years, < 27 for 4–6 years, < 28 for 7–9 years, and < 29 for 10 years or more; K-MoCA < 13 for illiterate, < 21 for 0.5–3 years, < 23 for 4–6 years, < 25 for 7–9 years, < 26 for 10 years or more). CONCLUSION: Both MMSE and MoCA can be used to screen for dementia in patients with PD, regardless of educational level; however, neither test is sufficient to discriminate MCI from normal cognition without additional information.

The Association between Frailty and Cognition in Elderly Women / 가정의학회지

BACKGROUND: Frailty refers to the loss of physiologic complexity and the associated decline in ability to withstand stressors as one gets older. It is defined as unintentional weight loss, exhaustion, weakness, slow walking speed, and low physical activity. According to several western studies, frailty is associated with cognitive impairment, but there have been few studies about the relationship between frailty and cognitive impairment in Korea. Thus, the purpose of this study is to analyze the relationship between cognition and factors related to frailty such as grip strength, walking speed, physical activity, and depression, among female patients older than 65 in Korea. METHODS: A total of 121 subjects among the outpatients of the department of family medicine at Kangbuk Samsung Hospital who did not meet the exclusion criteria were included in this study. We divided the participants into 2 groups, according to the Korean version of the Montreal Cognitive Assessment (MoCA) score: 1 group with subjects that had normal cognition and the other group with patients that had impaired cognition. A comparison was made between the 2 groups in regards to the factors related to frailty, and we completed equation that predicting cognition from the frailty related factors. RESULTS: Compared with the impaired cognition group, the subjects in the normal cognition group had higher hand strength, and walked faster (P<0.001). There was no statistically significant difference in physical activity between the 2 groups (P=0.19). When multiple linear regression analysis was performed using age, grip strength, and walking speed as the predictor variables and MoCA score as the dependent variable, the regression coefficients were calculated to be: -0.2015, 0.2294, 1.2372, and -0.1436, respectively (P<0.05). CONCLUSION: In Korean female patients who are older than 65 years of age, cognition tends to decline as grip strength decreases, walking speed gets slower, depression becomes more severe, and as age increases.

Study on Cognitive Reserve in Korea Using Korean Version of Cognitive Reserve Index Questionnaire / 신경정신의학

OBJECTIVES: To evaluate cognitive reserve in Korea using Korean version of Cognitive Reserve Index questionnaire (K-CRIq) and to investigate the effects of gender and age on cognitive reserve. METHODS: Three hundred and fifty-eight healthy subjects aged 25–85 years old in one community participated in the study. K-CRIq was developed and administered to all subjects to assess the effects of gender and age on cognitive reserve. Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) were administered to subjects over 65 years old to test concurrent validity. RESULTS: Age and gender as well as their interaction significantly affected Cognitive Reserve Index (CRI) score. Men had higher cognitive reserve than women over 45 years old, but at younger ages there was no gender difference in cognitive reserve. CRI score and sub-scores were strongly associated with the MMSE and MoCA. CONCLUSION: The results indicate that the gender effect on cognitive reserve is disappearing in the young generation in Korea. Scores in neuropsychological tests are predicted well by the CRI score.

A method for routine analysis of urinary 4,4'-methylenebis (2-chloroaniline) by gas chromatography-electron capture detection.

OBJECTIVES: The purpose of this study was to develop a simple and cost-effective method for the determination of urinary 4,4'-methylenebis (2-chloroaniline) (MBOCA) by gas chromatography-electron capture detection (GC-ECD) for biological monitoring of occupational exposure to MBOCA. METHODS: MBOCA was prepared by liquid-liquid extraction after alkaline hydrolysis, derivatized with N-methyl-bis (trifluoroacetamide) and then analyzed using GC-ECD. The proposed method was validated in accordance with the US Food and Drug Administration guidance. RESULTS: The calibration curve showed linearity in the range 1-100 µg/l, with a correlation coefficient of >0.999. The limits of detection and quantification were 0.3 µg/l and 1 µg/l, respectively. The recovery was 94-99%. Intraday accuracy, expressed as the deviation from the nominal value, was 90.5-100.3%, and intraday precision, expressed as the relative standard deviation, was 0.3-2.4%. Interday accuracy and precision were 87.8-100.2% and 0.3-4.1%, respectively. CONCLUSIONS: The proposed method is a simple and cost-effective method suitable for routine analyses and could be useful for biological monitoring of occupational exposure to MBOCA.

A Comparison of the Performances on the MMSE, HDS-R, and MoCA According to the CDR Sum of Boxes in Amnestic Mild Cognitive Impairment and Vascular Mild Cognitive Impairment

BACKGROUND: O'Bryant et al. (2008) argued that the CDR Sum of Boxes (CDR-SB) can be used to distinguish MCI from very early dementia in patients with CDR-GS of 0.5. They reported that the optimal CDR-SB cut-off score was 2.5. The present study was conducted to examine whether the subgroups classified with CDR-SB scores showed the corresponding group differences on the cognitive tests. METHODS: The subjects were 45 amnestic multi-domain MCI (amMCI) and 53 vascular MCI (VaMCI) with CDR-GS of 0.5. Each patient group was classified into "mild (0.5-2.0)" and "severe (2.5-4.0)" subgroups based on the CDR-SB. As the result, 4 groups were formed such as mild amMCI (n=23), severe amMCI (n=22), mild VaMCI (n=29), and severe VaMCI (n=24). The subjects were given the MMSE, HDS-R, and MoCA. The MANCOVA was conducted separately for each test with a Bonferroni correction for multiple comparisons. RESULTS: Severe groups of both amMCI and VaMCI showed significantly lower performances than two mild groups in MMSE, HDS-R, and MoCA. It was found that "serial 100-7" was a good item to discriminate between the mild and severe groups in both amMCI and VaMCI. Items measuring "orientation" or "naming" showed significant subgroup differences in the amMCI, whereas items related to "memory," "visuospatial construction," or "frontal/executive function" showed significant subgroup differences in the VaMCI. CONCLUSION: These results showed that there were significant differences in cognitive functions between the two subgroups with CDR-GS of 0.5. The results about the items discriminating between subgroups in amMCI and VaMCI were consistent with the previous findings about the progression of cognitive impairments in AD and VaD. Therefore, these results support the use of CDR-SB as a guideline for distinguishing MCI from early dementia.

Rapid and intermediate N-acetylators are less susceptible to oxidative damage among 4,4'-methylenebis(2-chloroaniline) (MBOCA)-exposed workers.

OBJECTIVES: In this study, we explored the association between a marker of oxidative stress, 8-hydroxydeoxyguanosine (8-OHdG), and genetic polymorphism of the carcinogen-metabolizing enzyme N-acetyltransferase 2 (NAT2) among 4,4'-methylenebis(2-chloroaniline) (MBOCA)-exposed workers. METHODS: The study population was recruited from four MBOCA-producing factories, and included 57 MBOCA-exposed workers and 101 unexposed control workers. Personal characteristics were collected by questionnaire. Plasma 8-OHdG levels were measured by LC/MS/MS. NAT2 alleles were measured by polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP). RESULTS: NAT2 polymorphism influenced the plasma 8-OHdG levels of MBOCA-exposed workers, but not of non-exposed workers. No difference between exposed and control groups was found for the crude 8-OHdG levels among rapid, intermediate, and slow acetylators. After adjusting for gender, age, smoking, and alcohol consumption habit, the 8-OHdG concentration in the MBOCA-exposed workers was 0.18pg/ml (95% CI -1.80 to -0.12) lower than the control group among rapid and intermediate acetylators. However, the difference between exposed and control groups was not significant for slow acetylators. CONCLUSION: Gene-environment interactions could play a role in the carcinogenesis of occupational MBOCA exposure. We suggest that the impact of the NAT2 acetylator status is low, if at all, on the generation of the oxidative stress marker 8-OHdG in the investigated exposed group.

New approaches to extraction techniques in determination of 4,4'-methylenebis(2-chloroaniline) in air and water solutions.

Extraction techniques for 4,4'-methylenebis(2-chloroaniline) (MOCA) in air samples and water solutions were developed and compared. Classic techniques for air sampling of MOCA were enhanced by incorporating a derivatization step (3,5-dinitrobenzoyl chloride solution in toluene), thus increasing the limit of detection and limit of quantification. Sampling of MOCA from water solution was performed using novel nanoporous polymeric (polypyrrole and polythiophene) fiber coatings and solid phase microextraction. Samples were analyzed by high-performance liquid chromatography coupled with a UV detector. Using the modified method for air sampling of MOCA, we found that the limit of detection was 7.90 ng m(-3) and the limit of quantification was 23.8 ng m(-3). In contrast, the limit of detection for MOCA in water samples was 11.26 ng mL(-1) (polypyrrole) and 84.62 ng mL(-1) (polythiophene) and the limit of quantification for MOCA was from 33.78 (polypyrrole) and 253.86 ng mL(-1) (polythiophene). Correlation coefficients were 0.9997 for air and 0.8790-0.9852 for water samples, respectively. The techniques presented provide alternative methods for the determination of MOCA in air samples and in water solutions that are more sensitive, quicker and less expensive than previously established procedures.

A follow up study of occupational exposure to 4,4'-methylene-bis(2-chloroaniline) (MbOCA) and isocyanates in polyurethane manufacture in the UK.

This is a follow up survey of exposure to 4,4'-methylene-bis(2-chloroaniline) (MbOCA) and isocyanates in the UK polyurethane industry. Urine samples (n=446) were collected from 90 different workers. MbOCA levels were below the limit of detection in 170 samples and 26 were above the UK Biological Monitoring Guidance Value (BMGV) of 15 µmol MbOCA/mol creatinine. Detailed advice and guidance was given to each workplace at the end of the survey in 2008 and the 90% value reduced from 10 to 3 µmol MbOCA/mol creatinine in samples collected since. There was a positive correlation between glove contamination and urinary MbOCA and levels were dependent upon individual working practices especially how gloves were used. Of the 446 samples analysed for urinary metabolites of toluene diisocyanate 280 were below the detection limit and 126 were above the BMGV (1 µmol/mol creatinine). Of the 326 urine samples that were analysed for metabolites of methylenediphenyl diisocyanate, 270 were below the detection limit and 13 were above the BMGV for isocyanates. There was no correlation between urinary levels of isocyanates and MbOCA suggesting different routes of absorption, most likely inhalation and dermal respectively.