Determination of monobromobimane derivatives of phenylmercapturic and benzylmercapturic acids in urine by high-performance liquid chromatography and fluorimetry

A method was developed for the determination in human urine of S-phenylmercapturic (PMA) and S-benzylmercapturic (BMA) acids, metabolites respectively of benzene and toluene. PMA and BMA were determined, after alkaline hydrolysis, to give respectively thiophenol and benzylmercaptan, and coupling of the thiol-containing compounds with monobromobimane (MB), by reversed-phase HPLC on a diphenyl-silica bonded cartridge (100×4.6 mm I.D., 5 μm particle size) with fluorimetric detection. Wavelengths for excitation and emission were 375 and 480 nm, respectively. The recovery of PMA and BMA from spiked urines was >90% in the 10–500 μg/l range; the quantification limits were respectively 1 and 0.5 μg/l; day-to-day precision at 42 μg/l was C.V. <7%. The suitability of the proposed procedure for the biological monitoring of exposure to low-level airborne concentrations of benzene and toluene, was evaluated by analyzing the urinary excretion of PMA and BMA in subjects exposed to different sources of aromatic hydrocarbons, namely occupationally-unexposed referents (non-smokers, n=15; moderate smokers, n=8; mean number of cigarettes smoked PER-DAY=17 cig/day) and non-smoker workers occupationally exposed to toluene in maintenance operations of rotogravure machines (non-smokers, n=17). Among referents, non-smokers showed values of PMA ranging from <1 to 4.6 μg/l and BMA from 1.0 to 10.4 μg/l; in smokers, PMA values ranging from 1.2 to 6.7 μg/l and BMA from 9.3 to 39.9 μg/l, were observed. In occupationally exposed non-smoker subjects, BMA median excretion value (23.6 μg/l) was higher than in non-smoker referents (3.5 μg/l) (P<0.001) and individual BMA values (y, μg/l) were associated and increased with airborne toluene concentration (x, mg/m³) according to the equation y=6.5+0.65x (r=0.69, P<0.01, n=17). The proposed analytical method appears to be a sensitive and specific tool for biological monitoring of low-level exposure to benzene and toluene mixtures in occupational and environmental toxicology laboratory.     

Cotinine levels and self-reported smoking status in patients attending a bronchoscopy clinic

The reliability of self-reported smoking behaviour can vary and may result in bias if errors in misclassification vary with outcome. We examined whether self-report was an accurate measure of current smoking status in patients with malignant or non-malignant respiratory disease. Smoking behaviour was assessed by self-report and by analysis of whole blood for cotinine, a biomarker of exposure to cigarette smoke, in 166 patients attending a bronchoscopy clinic. Cotinine levels ranged from 2.5 to &gt;400 ng ml^?1 blood and were higher in self-reported current smokers (173±123 ng ml^?1) than in never smokers (3.7±8.7 ng ml^?1) or ex-smokers (20.5±49.0 ng ml^?1). Cotinine levels in self-reported current smokers increased with the numbers of cigarettes smoked (p=0.06), and levels in smokers and ex-smokers decreased with the reported length of time since the last cigarette (p=0.001). Using a cotinine level of 20 ng ml^?1 and self-report as the gold standard, the sensitivity and specificity for defining current smoking status were 90.2% and 82.4%, respectively. Out of a total of 125 self-reported current non-smokers, 23 (18.4%) had cotinine levels greater than 20 ng ml^?1. Smoking prevalence was significantly underestimated by self-report (24.7%) when compared with that defined using blood cotinine levels (36.1%: p&lt;0.001). Misclassification of current smoking status was particularly high in ex-smokers, in patients without malignant respiratory disease, in men, and in those below the median age. Such differential misclassification may result in bias in studies examining associations between current smoking habits and disease risk.     

Biomonitoring of environmental tobacco smoke (ETS)-related exposure to 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)

The exposure of non-smokers to the tobacco-specific N-nitrosamine 4-(N-methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), a rodent lung carcinogen, was determined in the air of various indoor environments as well as by biomonitoring of non-smokers exposed to environmental tobacco smoke (ETS) under real-life conditions using the urinary NNK metabolites 4-(N-methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) and [4-(N-methylnitrosamino)-1-(3-pyridyl)but-1-yl]-beta-O-D-glucosiduronic acid (NNAL-Gluc). NNK was not detectable (&lt;0.5 ng m^-3) in 11 rooms in which smoking did not occur. The mean NNK concentration in 19 rooms in which smoking took place was 17.5 (2.4-50.0) ng m^-3. The NNK levels significantly correlated with the nicotine levels (r=0.856; p&lt; 0.0001). Of the 29 non-smokers investigated, 12 exhibited no detectable NNAL and NNAL-Gluc excretion (&lt;3 pmol day) in their urine. The mean urinary excretion of NNAL and NNAL-Gluc of the 17 remaining non-smokers was 20.3 (&lt;3-63.2) and 22.9 (&lt;3-90.0) pmol day^-1, respectively. Total NNAL excretion (NNAL+NNAL-Gluc) in all non-smokers investigated significantly correlated with the amount of nicotine on personal samplers worn during the week prior to urine collection (r=0.88; &lt;0.0001) and with the urinary cotinine levels (r=0.40; p=0.038). No correlation was found between NNAL excretion and the reported extent of ETS exposure. Average total NNAL excretion in the non-smokers with detectable NNAL levels was 74 times less than in 20 smokers who were also investigated. The cotinine/total NNAL ratios in urine of smokers (9900) and non-smokers (9300) were similar. This appears to be at variance with the ratios of the corresponding precursors (nicotine/NNK) in mainstream smoke (16400) and ETS (1000). Possible reasons for this discrepancy are discussed. The possible role of NNK as a lung carcinogen in non-smokers is unclear, especially since NNK exposure in non-smokers is several orders of magnitude lower than the ordinary exposure to exogenous and endogenous N-nitrosamines and the role of NNK as a human lung carcinogen is not fully understood.     

S100B and brain natriuretic peptide predict functional neurological outcome after intracerebral haemorrhage

Colorimetric test strip assays are a convenient and inexpensive means for the determination of cotinine in human urine because they can be performed in a nonlaboratory environment using a trained technician. Four hundred human urine samples were separated into four categories: (1) heavy smokers (>20 cigarettes smoked per day), (2) light smokers (<20 cigarettes smoked per day), (3) non-smokers, and (4) vegetarian non-smokers. Samples were evaluated by a gas chromatography/mass selective detector (GC/MSD) method as a reference and using NicCheck I? (DynaGen, Inc.). Colour intensity can range from 0 (no colour) to 14 (deep pink). Qualitative values were assigned as negative (0), low (1-6) and high (7-14). Comparison of the test strip and GC/MSD results showed: (1) 43 (10.75%) false negatives using the criterion of a GC/MSD cotinine level above 200 ng ml^-1 and test strip reading of 0, (2) 31 (7.75%) false positives using the criterion of a GC/MSD cotinine level below 1 ng ml^-1 and a test strip reading of 1 or greater, and (3) no correlation between the test strip and GC/MSD results (r = 0.597, p < 0.05). The fact that the colorimetric reaction is sensitive to many nicotine metabolites and/or heterocyclic amine structures whereas the GC/MSD method measures nicotine and cotinine selectively might explain the false positive results. False negative results were likely to be due to a lack of sensitivity of the test strip.     

Urinary 1-hydroxypyrene as a biomarker of exposure to polycyclic aromatic hydrocarbons: biological monitoring strategies and methodology for determining biological exposure indices for various work environments

This article reviews the published studies on urinary 1-hydroxypyrene (1-OHP) as a biomarker of exposure to polycyclic aromatic hydrocarbons (PAHs) in work environments. Sampling and analysis strategies as well as a methodology for determining biological exposure indices (BEIs) of 1-OHP in urine for different work environments are proposed for the biological monitoring of occupational exposure to PAHs. Owing to the kinetics of absorption of pyrene by different exposure routes and excretion of 1-OHP in urine, in general, 1-OHP urinary excretion levels increase during the course of a workday, reaching maximum values 3-9 h after the end of work. When the contribution of dermal exposure is important, post-shift 1-OHP excretion can however be lower than pre-shift levels in the case where a worker has been exposed occupationally to PAHs on the day prior to sampling. In addition, 1-OHP excretion levels in either pre-shift, post-shift or evening samples increase during the course of a work-week, levelling off after three consecutive days of work. Consequently, ideally, for a first characterization of a work environment and for an indication of the major exposure route, considering a 5-day work-week (Monday to Friday), the best sampling strategy would be to collect all micturitions over 24 h starting on Monday morning. Alternatively, collection of pre-shift, post-shift and evening urine samples on the first day of the work-week and at the end of the work-week is recommended. For routine monitoring, pre-shift samples on Monday and post-shift samples on Friday should be collected when pulmonary exposure is the main route of exposure. On the other hand, pre-shift samples on Monday and Friday should be collected when the contribution of skin uptake is important. The difference between beginning and end of work-week excretion will give an indication of the average exposure over the workweek. Pre-shift samples on the first day of the work-week will indicate background values, and, hence, reflect general environment exposure and body burden of pyrene and/or its metabolites. On the other hand, since PAH profile can vary substantially in different work sites, a single BEI cannot apply to all workplaces. A simple equation was therefore developed to establish BEIs for workers exposed to PAHs in different work environments by using a BEI already established for a given work environment and by introducing a correction factor corresponding to the ratio of the airborne concentration of the sum of benzo(a)pyrene (BaP) equivalent to that of pyrene. The sum of BaP equivalent concentrations represents the sum of carcinogenic PAH concentrations expressed as BaP using toxic equivalent factors. Based on a previously estimated BEI of 2.3 μmol 1-OHP mol^-1 creatinine for coke-oven workers, BEIs of 4.4, 8.0 and 9.8 μmol 1-OHP mol^-1 creatinine were respectively calculated for vertical pin Söderberg workers, anode workers and pre-bake workers of aluminium plants and a BEI of 1.2 μmol 1-OHP mol^-1 creatinine was estimated for iron foundry workers. This approach will allow the potential risk of cancer in individuals occupationally exposed to PAHs to be assessed better.     

Smoking-related DNA adducts in anal epithelium

Several studies have identified tobacco smoking as a risk factor for anal cancer in both women and men. Samples of anal epithelium from haemorrhoidectomy specimens from current smokers (n=20) and age-matched life-long non-smokers (n=16) were analysed for DNA adducts by the nuclease P₁ digestion enhancement procedure of ³²P-postlabelling analysis. The study included 14 men and 22 women. Both qualitative and quantitative differences in the adduct profiles were observed between the smokers and non-smokers. The mean adduct level was significantly higher in the smokers than in the non-smokers (1.88±0.71 (S.D.) versus 1.36±0.60 adducts per 10⁸ nucleotides, P=0.02, two-tailed unpaired t-test with Welch’s correction); furthermore, the adduct pattern seen in two-dimensional chromatograms revealed the smoking-related diagonal radioactive zone in 17/20 smokers, but not in any of the non-smokers (P<0.00001, Fisher’s exact test). These results indicate that components of tobacco smoke inflict genotoxic damage in the anal epithelium of smokers and provide a plausible mechanism for a causal association between smoking and anal cancer.     

Determination of tobacco-specific N-nitrosamines in urine of smokers and non-smokers

Tobacco-specific N-nitrosamines (TSNA) include 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), N′-nitrosonornicotine (NNN), N′-nitrosoanabasine (NAB) and N′-nitrosoanatabine (NAT) and are found in tobacco and tobacco smoke. TSNA are of interest for biomonitoring of tobacco-smoke exposure as they are associated with carcinogenesis. Both NNK and NNN are classified by IARC as Group 1 carcinogens. Samples of 24?h urine collections (n?=?108) were analysed from smokers and non-smokers, using a newly developed and validated LC-MS/MS method for determining total 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL, the major metabolite of NNK), and total NNN, NAB and NAT. TSNA levels in smokers’ urine were significantly higher than in non-smokers. In smokers, urinary excretion of total TSNA correlated significantly (r?>?0.5) with markers of smoking dose, such as daily cigarette consumption, salivary cotinine and urinary nicotine equivalents and increased with the ISO tar yield of cigarettes smoked. The correlation between urinary total NNN and the smoking dose was weaker (r?=?0.4–0.5). In conclusion, this new method is suitable for assessing tobacco use-related exposure to NNK, NNN, NAB and NAT.     

Serum Clara cell protein (CC16) in healthy young smokers

The CC16 microprotein is the main secretory product of Clara cells, which are epithelial cells lining lung airways. In crossing through the bronchoalveolar/blood barrier, CC16 diffuses passively into plasma. Serum CC16 (sCC16) has recently been proposed as a biomarker for detecting Clara cell impairments. The aim of this study was to assess if sCC16 concentrations are reduced in a group of healthy young smokers. A group of 118 healthy young males volunteered to take part in the study. Each subject answered a questionnaire, and provided blood and urine samples. Serum CC16, urinary cotinine and creatinine were measured. Median serum CC16 concentrations were lower in smokers than in non-smokers (11.3 mug l^-1 vs 14.6 mug l^-1; p = 0.005; N = 89 and 29, respectively) but did not correlate with either the daily or the life-time cigarette consumption, or with urinary cotinine concentrations. sCC16 did not correlate with age or body mass index in the whole study population or in the groups of smokers and non-smokers. These results suggest the reduction in sCC16 concentrations in a group of healthy young smokers may be an early effect of cigarette smoking.     

l-Arginine Effects on Na+ Transport in M-1 Mouse Cortical Collecting Duct Cells—A Cationic Amino Acid Absorbing Epithelium

The effect of l-arginine on transepithelial ion transport was examined in cultured M-1 mouse renal cortical collecting duct (CCD) cells using continuous short circuit current (I _SC ) measurements in HCO₃ ⁻/CO₂ buffered solution. Steady state I _SC averaged 73.8 ± 3.2 μA/cm² (n= 126) and was reduced by 94 ± 0.6% (n= 16) by the apical addition of 100 μm amiloride. This confirms that the predominant electrogenic ion transport in M-1 cells is Na⁺ absorption via the epithelial sodium channel (ENaC). Experiments using the cationic amino acid l-lysine (radiolabeled) as a stable arginine analogue show that the combined activity of an apical system y⁺ and a basal amino acid transport system y⁺L are responsible for most cationic amino acid transport across M-1 cells. Together they generate net absorptive cationic amino acid flux. Application of l-arginine (10 mm) either apically or basolaterally induced a transient peak increase in I _SC averaging 36.6 ± 5.4 μA/cm² (n= 19) and 32.0 ± 7.2 μA/cm² (n= 8), respectively. The response was preserved in the absence of bath Cl⁻ (n= 4), but was abolished either in the absence of apical Na⁺ (n= 4) or by apical addition of 100 μm amiloride (n= 6). l-lysine, which cannot serve as a precursor of NO, caused a response similar to that of l-arginine (n= 4); neither L-NMMA (100 μm; n= 3) nor L-NAME (1 mm; n= 4) (both NO-synthase inhibitors) affected the I _SC response to l-arginine. The effects of arginine or lysine were replicated by alkalinization that mimicked the transient alkalinization of the bath solution upon addition of these amino acids. We conclude that in M-1 cells l-arginine stimulates Na⁺ absorption via a pH-dependent, but NO-independent mechanism. The observed net cationic amino acid absorption will counteract passive cationic amino acid leak into the CCD in the presence of electrogenic Na⁺ transport, consistent with reports of stimulated expression of Na⁺ and cationic amino acid transporters by aldosterone. Received: 11 September 2000/Revised: 6 December 2000     

Evaluation of urinary 1-hydroxypyrene,S-phenylmercapturic acid,trans,trans-muconic acid, 3-methyladenine, 3-ethyladenine, 8-hydroxy-2′-deoxyguanosine and thioethers as biomarkers of exposure to cigarette smoke

The objective was to evaluate the utility of urinary 1-hydroxypyrene (1-OHP), S-phenylmercapturic acid (S-PMA), trans,trans-muconic acid (t,t-MA), 3-methyladenine (3-MeAd), 3-ethyladenine (3-EtAd), 8-hydroxy-2′-deoxyguanosine (8-OHdG) and thioethers as biomarkers for assessing the exposure in adult smokers who switched from smoking conventional cigarettes to candidate potential reduced exposure products (PREP) or who stopped smoking. Two electrically heated smoking systems (EHCSS) were used as prototype cigarettes that have significant reductions in a number of mainstream smoke constituents as measured by smoking machines relative to those from conventional cigarettes. Urine samples were collected from a randomized, controlled, forced-switching study in which 110 adult smokers of a conventional cigarette brand (CC1) were randomly assigned to five study groups. The groups included the CC1 smoking group, a lower-tar conventional cigarette (CC2) smoking group, EHCSS1 group, EHCSS2 group and a no smoking group that were monitored for 8 days. Biomarkers were measured at baseline and day 8. The daily excretion levels of these biomarkers were compared among the groups before and after switching, and the relationships between the daily excretion levels of these biomarkers and cigarette smoking-related exposure were investigated using Pearson product-moment correlation and multiple regression analyses. It was concluded that under controlled study conditions: (1) 1-OHP, S-PMA and t,t-MA are useful biomarkers that could differentiate exposure between smoking conventional and EHCSS cigarettes or between smoking conventional cigarettes and no smoking; between S-PMA and t,t-MA, the former appeared to be more sensitive; (2) 3-MeAd could only differentiate between smoking conventional cigarettes and no smoking; the results for 3-EtAd were not conclusive because contradictory results were observed; (3) 8-OHdG had a questionable association with smoking and therefore the utility of this biomarker for smoking-related exposure could not be established; and (4) urinary excretion of thioethers as a biomarker lacked sensitivity to demonstrate a clear dose–response relationship in conventional cigarette smokers, although it could differentiate the excretion levels between those subjects who smoked a conventional cigarette and those who stopped smoking.     

Isolation and measurement of urinary 8-iso-prostaglandin F2α by high-performance liquid chromatography and gas chromatography–mass spectrometry

8-iso-Prostaglandin F_2α (8-iso-PGF_2α) is a product of free radical-catalyzed peroxidation of arachidonic acid. Measurement of its urinary excretion has been proposed as an index of oxidative status in vivo. A stable isotope dilution method for its quantification by gas chromatography–electron capture chemical ionization mass spectrometry is described. Sample cleanup required the combined use of high-performance liquid chromatography and thin-layer chromatography. The inter-assay R.S.D. in two separate determinations was 1.6 (n=4) and 2.3% (n=4). The accuracy of the assay was evaluated through recovery experiments. The equation of the regression plot correlating the amounts added and recovered was y=0.91x−0.31, r=0.9916 (n=12). The pair of fragment ions ([M−181]⁻) at m/z 569 and m/z 573 was monitored for quantification. The mean 8-iso-PGF_2α excretion rate was 528±127 (S.D.) ng per day in five male volunteers and 730±305 ng per day in six females. Intake of 80 mg of lycopene per day by eleven volunteers for four weeks resulted in a non-significant reduction of 8-iso-PGF_2α excretion.     

Simultaneous determination of urinary 1- and 2-naphthols, 3- and 9-phenanthrols,and 1-pyrenol in coke oven workers

A method was developed for simultaneous quantification of urinary 1- and 2-naphthols, 3- and 9-phenanthrols and 1-pyrenol using gas chromatography with mass spectrometry (GC-MS). This method was applied to urine samples from coke oven workers (n =28) and controls (n =22) from Northern China. Geometric mean levels of urinary 1-naphthol (58.8 μg l^?1), 2-naphthol (34.1 μg l^?1), 3-phenanthrol (7.35 μg l^?1), 9-phenanthrol (1.28 μg l^?1) and 1-pyrenol (25.4 μg l^?1) were significantly higher among coke oven workers than controls. All the substances tested were highest among top-of-oven workers, who had 15-fold higher 1-naphthol, eight-fold higher 2-naphthol and 20-fold higher 1-pyrenol levels compared with controls. Using multiple linear regression models, 72.5% of the variation in 1- and 2-naphthol and 82.8% of the variation in 1-pyrenol were explained by the concentration of naphthalene or pyrene in the urine, the work category and the smoking intensity. Cigarette consumption significantly contributed to levels of urinary 1-pyrenol and naphthols, particularly 2-naphthol. A negative relationship between work category and the ratio of naphthols/1-pyrenol was observed among smokers. Our results suggest that urinary naphthols and phenanthrols reflect polycyclic aromatic hydrocarbon (PAH) exposure as well as the widely used 1-pyrenol, and that interactions between cigarette smoking and PAH exposure result in different patterns of metabolism for individual PAHs.     

圈养林麝粪样类固醇激素水平与麝香分泌的关系

基于非损伤取样和放射免疫法（RIA）,于2018年9月1日-10月15日期间对四川马尔康林麝繁育场的36头雄性圈养林麝（Moschus berezovskii）的粪样类固醇激素水平进行了检测,结合麝香分泌数据采集,探究了林麝的粪样睾酮和皮质醇水平与其麝香分泌的关系,结果表明：四川马尔康圈养林麝的麝香分泌（12.53±0.76）g（n=36）与粪样睾酮水平（106.03±12.34）ng/g（n=36）呈显著正相关（r=0.436,P < 0.01）,泌香较多雄麝（16.50±0.61）g（n=17）的睾酮水平（141.51±21.86）ng/g（n=17）显著地高于泌香较少（8.98±0.59）g（n=19）雄麝（74.27±7.93）ng/g（n=19）（t=-3.252,df=34, P < 0.01）,方程y=0.021x+10.270（R²=0.120,P < 0.05）可较好地拟合二者间关系。麝香分泌与皮质醇浓度（47.49±1.53）ng/g（n=36）相关不显著（r=0.078,P > 0.05）,泌香较多雄麝的皮质醇浓度（48.98±2.28）ng/g（n=17）略高于泌香较少雄麝（46.17±2.14）ng/g（n=19）,差异不显著（P > 0.05）,方程y=0.038x+10.730（R²=0.023,P > 0.05）可近似拟合皮质醇与泌香量间的关系。此外,雄麝睾酮水平对泌香量有显著影响（P < 0.05）,睾酮水平较高林麝泌香量（14.97±1.17）g（n=12）显著高于睾酮水平较低个体的泌香量（11.32±0.90）g（n=24）（F=4.79,P < 0.05）,而睾酮、皮质醇和年龄对麝香分泌的综合效应及变量间的交互作用均不显著（P > 0.05）。研究确定了圈养林麝粪样睾酮和皮质醇水平与麝香分泌量间的关系,可用于麝类驯养实践的麝香产量预测及品系选育。     

The effect of water depth on bacterial numbers,thymidine incorporation rates and C:N ratios in northeast Atlantic surficial sediments

The effect of water depth on bacterial biomass and their ability to synthesise DNA, by measuring their rate of [³H]-thymidine incorporation, was investigated in the northeast Atlantic at three sites of varying water depth (1100–3580 m) and sediment characteristics. Thymidine incorporation rates (y) in surficial sediments varied between 0.028 and 1.44 pmol h^–1 g^–1 and showed an exponential relationship with depth (x) according to the equation y= 2.05e^–0.0011x (r=0.9830 for n=7, P<0.001). However, this relationship failed when a layer of phytodetritus was found overlying the surface sediment and [³H]-thymidine incorporation rates increased by 80–339%. In contrast, bacterial numbers varied between 1.09 and 11.96 × 10⁸ cells g^–1 (dry weight) and showed no significant relationships with water depth or sediment POC/TN content. Significant exponential relationships were also found between water depth (x) and the POC (y ₁) and total nitrogen (TN, y ₂) content of surficial sediments according to the following equations: where y ₁ = 719e^–0.0003x (r=0.8700 for n=9, P<0.01) and y ₂ = 76e^–0.0002x(r=0.7582 for n=9 P<0.02). These relationships were irrespective of the presence or absence of an overlying layer of phytodetritus. This suggests that the POC and TN content of these surficial deep sea sediments is directly related to the flux of material through the water column, which significantly impacts bacterial production.     

Calibration of FST-hemispheres against bottom shear stress in a laboratory flume*

SUMMARY.

• 1 Fliesswasserstammtisch (FST)-hemispheres of identical size but different densities were exposed on a horizontal plane on the pebble-covered bottom of a laboratory flume at streaming to shooting, turbulent and fully developed flow. The heaviest hemisphere moved was used as an indicator of shear stress, a flow force acting on the flume bottom.
• 2 The relationship between shear stress and hemisphere density was practically the same for three different sets of hemispheres, namely one prototype set newly prepared for the calibrations, one prototype set intensively used in the field prior to calibrations, and one randomly selected new set bought commercially.
• 3 Shear stress (y, dyn cm^?2) was related to hemisphere density (x, g cm^?3) by y= x^2.85 (n= 69; r²= 0.993). For lighter hemispheres this relationship was better explained by the linear model y= 7.32x– 6.60 (n= 35; r²=0.983).

     

Haploid plantlets derived by anther culture of Cucurbita pepo

This work was conducted to study the effect of sucrose and 2,4-D combinations on induction of haploid plants of a summer squash cultivar through anther culture; therefore, sucrose was used at 30, 60, 90, 120 and 150 g l⁻¹and 2, 4-D was used at 0.1, 1.0, 2.5 and 5.0 mg l⁻¹on solid MS anther culture medium. Anthers at the mid or late uninucleate microspore stage without filament were excised from sterilized buds and plated on 20 different induction media. The most plantlets resulted from the induction medium supplemented with 150 g l⁻¹sucrose and 5 mg l⁻¹2, 4-D. Root tips from 20 plantlets were cytologically examined under a light microscope. The results revealed ten diploid (2n>= 2x= 40) and ten haploid (2n= x= 20) plants. This revised version was published online in June 2006 with corrections to the Cover Date.     

Pneumoproteins and inflammatory biomarkers in asphalt pavers

Pneumoproteins, biomarkers of systemic inflammation and endothelial activation were studied across a season in 72 asphalt pavers, 32 asphalt plant operators and 19 asphalt engineers. Smokers had lower concentrations of Clara cell protein (CC-16) and surfactant protein A, but higher concentrations of surfactant protein D, interleukin 6, C-reactive protein, fibrinogen and intercellular adhesion molecule (ICAM)-1 than non-smokers. Smokers reporting wheezing had lower mean CC-16 concentration than smokers not reporting wheezing (5.7 vs 8.6 µg l^?1; p?=?0.05). Cholesterol, P-selectin and ICAM-1 were lower in pavers and operators at the end compared with the start of the season. This may be related to increased physical activity during the season.     

Association between Self-Reported Smoking and Hemoglobin A1c in a Korean Population without Diabetes: The 2011–2012 Korean National Health and Nutrition Examination Survey

BackgroundSeveral Western studies have revealed that among non-diabetics, glycosylated hemoglobin A1c (HbA1c) levels are higher in smokers than non-smokers. While studies conducted in Western populations consistently support this association, a recent meta-analysis reported that studies carried out in non-Western populations, including studies of Chinese, Egyptian, and Japanese-Americans, did not detect any significant differences in HbA1c levels between smokers and non-smokers.ObjectivesWe assessed the association between smoking habits and HbA1c levels in the general Korean adult population using data from the Korean National Health and Nutrition Examination Survey (KNHANES) performed in 2011–2012.MethodsA total of 10,241 participants (weighted n=33,946,561 including 16,769,320 men and 17,177,241 women) without diabetes were divided into four categories according to their smoking habits: never smokers (unweighted n/ weighted n= 6,349/19,105,564), ex-smokers (unweighted n/ weighted n= 1,912/6,207,144), current light smokers (<15 cigarettes per day, unweighted n/ weighted n=1,205/5,130,073), and current heavy smokers (≥15 cigarettes per day, unweighted n/ weighted n=775/3,503,781).ResultsIn age- and gender-adjusted comparisons, the HbA1c levels of each group were 5.52 ± 0.01% in non-smokers, 5.49 ± 0.01% in ex-smokers, 5.53 ± 0.01% in light smokers, and 5.61 ± 0.02% in heavy smokers. HbA1c levels were significantly higher in light smokers than in ex-smokers (p = 0.033), and in heavy smokers compared with light smokers (p < 0.001). The significant differences remained after adjusting for age, gender, fasting plasma glucose, heavy alcohol drinking, hematocrit, college graduation, and waist circumference. Linear regression analyses for HbA1c using the above-mentioned variables as covariates revealed that a significant association between current smoking and HbA1c (coefficient 0.021, 95% CI 0.003–0.039, p = 0.019).ConclusionsCurrent smoking was independently associated with higher HbA1c levels in a cigarette exposure-dependent manner in a representative population of Korean non-diabetic adults. In this study, we have observed an association between smoking status and HbA1c levels in non-diabetics drawn from a non-Western population, consistent with previous findings in Western populations.     

Multisubstrate kinetics of PAH mixture biodegradation: analysis in the double-logarithmic plot

The proposed method of kinetic analysis of aqueous-phase biodegradation of polycyclic aromatic hydrocarbons (PAH) mixture presupposes representation of kinetic curves for each pair of mixture components, S _x and S _y , in double-logarithmic coordinates (ln S _x ; ln S _y ). If PAH mixture conversion corresponds to the multisubstrate model with a common active site, then the graphs in double-logarithmic coordinates are straight lines with the angular coefficients equal to the ratio of respective first-order rate constants k_x^y = \fracV_y K_x K_y V_x k_{x}^{y} = {\frac{{V_{y} K_{x} }}{{K_{y} V_{x} }}} , where K _x and K _y are half-saturation constants, V _x and V _y are the maximum conversion rates for substrates S _x and S _y ; the graph slope does not depend on any concentrations and remains constant during the change of reaction rates as a result of inhibition, induction/inactivation of enzymes or biomass growth. The formulated method has been used to analyze PAH mixture conversion by the culture of Sphingomonas sp. VKM B-2434. It has been shown that this process does not satisfy the multisubstrate model with a single active site. The results suggest that the strain VKM B-2434 contains at least two dioxygenases of different substrate specificity: one enzyme converts phenanthrene and fluoranthene and the other converts acenaphthene and acenaphthylene. The ratios of first-order rate constants have been obtained for these pairs of substrates.     

Different susceptibility to polycyclic aromatic hydrocarbons (PAH)-induced DNA damage in lung tissue in male and female non-smokers

The levels of benzo(a)pyrene diol-epoxide (BPDE)-DNA adducts and polycyclic aromatic hydrocarbons (PAH) were analysed in a limited number of samples of autoptic lung tissue obtained from non-professionally exposed male (n= 13) and female (n= 12) non-smokers in an attempt to evaluate the relationship between gender, lung PAH levels (n= 25) and susceptibility to BPDE-DNA adduct formation (n= 18). Lung concentrations of chrysene, benzo(g,h,i)perylene and benzo(a)pyrene were significantly higher in males than in females (P