OBJECTIVETo establish the method of high-performance liquid chromatography HPLC for the determination of N-acetyl-S-(2-carbamoylethyl)-cysteine (AAMA) in urine.

METHODSAfter acid hydrolysis, AAMA in urine was converted into S-2-carboxyethyl cysteine (CEC). CEC reacted with the derivative reagent ophthalaldehyde and formed the derivative with strong fluorescence absorption. The HPLC-fluorescence detector was applied, with an excitation wavelength of 340 nm and an emission wavelength of 450 nm.

RESULTSUrinary AAMA demonstrated an excellent linearity in the range of 5.3~123.5 μmol/L, with a correlation coefficient of 0.9994. The minimum detectable concentration was 0.1 μmol/L (the volume of urine sample was 1.0 ml), the recovery of standard addition was 97.4%~104.2%, and the between-run precision was 2.3%~4.3%. The sample could be stored in the refrigerator for at least 7 days at a temperature of 4℃.

CONCLUSIONThe method is simple, with a low cost, a high sensitivity, and good precision and accuracy, and the instrument and equipment commonly seen in laboratories are applied. Therefore, this method is worthy of wide application.

Acetylcysteine ; analogs & derivatives ; urine ; Chromatography, High Pressure Liquid ; Humans

Acetylcysteine ; analogs & derivatives ; urine ; Biomarkers ; urine ; Humans ; Hydrocarbons, Brominated ; adverse effects ; Occupational Exposure

OBJECTIVETo study the effect of epigallocatechin gallate (EGCG) against lactacystin induced PC12 cell injury.

METHODSThe inoculated rat PC12 cells were cultured for 24 h, followed by intervention. The cells were divided into 5 groups, i.e., the normal control group, 10 micromol/L lactacystin injury group, and the EGCG pretreated groups (at the final concentration of 5, 10, and 50 micromol/L, respectively). The cytoactive was detected by MTT colorimetry. Morphological changes of the cell nucleus were observed by Hoechst 33,258 staining, and the apoptosis ratio was detected by flow cytometry (FCM).

RESULTSEGCG at different doses showed protective effect on lactacystin-induced PC12 cell injury. Compared with the lactacystin injury group [(61.22 +/- 1.02)%], the cytoactive in EGCG pretreated groups at the final concentration of 5, 10, and 50 micromol/L, respectively increased obviously to (66.99 +/- 1.30)%, (66.67 +/- 0.65)%, and (73.4 +/- 0.67)%, respectively. Hoechst 33 258 staining found that more nuclear pyknosis and aggregation occurred in the lactacystin injury group, but less occurred in EGCG pretreated groups. FCM indicated that the apoptosis ratio was reduced by EGCG pretreatment. It was 3.0%, 60.4%, 59.8%, 57.5%, and 38.6%, respectively in the normal control group, the lactacystin injury group, and EGCG pretreated groups (at the final concentration of 5, 10, and 50 micromol/L, respectively).

CONCLUSIONEGCG could attenuate lactacystin induced PC 12 cell injury.

Acetylcysteine ; adverse effects ; analogs & derivatives ; Animals ; Apoptosis ; drug effects ; Catechin ; analogs & derivatives ; pharmacology ; Flow Cytometry ; PC12 Cells ; Rats

OBJECTIVETo establish a method for simultaneously determining the urinary concentrations of 8-hydroxy-2'-deoxyguanosine (8-OHdG), trans, trans-muconic acid (tt-MA), and S-phenylmercapturic acid (S-PMA) in subjects exposed to benzene.

METHODSAfter being purified by a solid-phase extraction column, the urine samples were transferred to a liquid chromatography-mass spectrometry system, and the concentrations of 8-OHdG, tt-MA, and S-PMA were determined by external standard method. A C18 reversed-phase column was used as the chromatographic column, and methanol/acidic ammonium formate solution was used as the mobile phase for gradient elution. The mass spectrometer was operated in a multi-reaction monitoring mode.

RESULTSFor tt-MA, the calibration curves were linear in the range of 10-1000 µg/L, and the recovery rates were over 90% (relative standard deviation (RSD) < 3%) at spiked levels of 50 µg/L and 500 µg/L. For S-PMA and 8-OHdG, the calibration curves were linear in the range of 1-100 µg/L, and the recovery rates were over 85% (RSD < 5%) at spiked levels of 5 µg/L and 50 µg/L.

CONCLUSIONThis determination method meets the requirement of Biological materials-

METHODSof monitoring-Guide of development (WS/T 68-1996) and can be used for simultaneous determination of 8-OHdG, tt-MA, and S-PMA in urine.

Acetylcysteine ; analogs & derivatives ; urine ; Benzene ; poisoning ; Chromatography, Liquid ; methods ; Deoxyguanosine ; analogs & derivatives ; urine ; Humans ; Mass Spectrometry ; Occupational Exposure ; prevention & control ; Sorbic Acid ; analogs & derivatives ; metabolism

Acetylcysteine ; analogs & derivatives ; urine ; Adolescent ; Adult ; Deoxyguanosine ; analogs & derivatives ; urine ; Female ; Furans ; urine ; Humans ; Hydrocarbons, Aromatic ; analysis ; Male ; Occupational Exposure ; analysis ; Young Adult

C-terminal farnesyl cysteine carboxyl methylation has been known to be the last step in the post-translational modification processes of several important signal transduction proteins in eukaryotes including ras related GTP binding proteins and the gamma-subunit of heterotrimeric G proteins. Protein farnesyl cysteine carboxyl methyltransferase (PFCCMT; EC, 2.1.1.100) catalyzing the reaction is well characterized as being stimulated by guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) and suppressed by N-acetyl-S-farnesyl-L-cysteine (AFC). As an initial step to understand the physiological significance of the process, we attempted to purify the enzyme, which was partially purified 130-fold (specific activity, 143 pmol of methyl group transferred/min/mg of protein) with yield of 1.8% after purification by fast protein liquid chromatography (FPLC) on a Superdex 75 column. The enzyme was further purified with non denaturing polyacrylamide gel electrophoresis (ND-PAGE) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The molecular weight of PFCCMT was determined to be about 30 kDa based on Superdex 75 FPLC as well as photoaffinity labelling with S-adenosyl-L-[methyl-3H] methionine ([methyl-3H]SAM). The partially purified enzyme (Superdex 75 eluate) was found to be characteristically affected by GTP gamma S, being activated about 40-fold in 2 mM, in contrast to ATP which did not show any effect on enzyme activity. Meanwhile, the enzyme was found to be markedly inhibited by AFC, reaching 0 activity in 2 mM. These observations strongly suggested that the partially purified enzyme was PFCCMT.
Acetylcysteine/pharmacology ; Acetylcysteine/analogs & derivatives ; Animal ; Brain/enzymology* ; Cattle ; Chromatography, Liquid ; Guanosine 5'-O-(3-Thiotriphosphate)/pharmacology ; Molecular Weight ; Protein Methyltransferases/isolation & purification* ; Protein Methyltransferases/chemistry ; Protein Processing, Post-Translational

OBJECTIVETo observe the urinary S-phenylmercapturic acid (S-PMA) variation in the benzene dynamic exposed rat models and benzene exposed workers, and study the feasibility of use of urinary S-PMA as the biomarker in benzene exposed.

METHODSIn an animal model study, forty-eight adult Wistar rats were randomly divided into 4 groups: the control group, low-dose group, middle-dose group and high-dose group. The exposed groups were dynamically exposed for 28 days (4 periods) by benzene and the concentration was monitored. The urine was immediately collected after every exposure period and detected by the liquid chromatographic/mass spectrometry methods. In a cohort study, eighty benzene exposed workers in a ship-yard in Guangzhou were selected as the exposed subjects while forty healthy officers in the same shipyard who were not occupationally exposed to benzene were treated as the control. The urine was collected after work shift. The urinary S-PMA and the benzene in the workplace was treated as the rat model.

RESULTSIn the animal model study, the urinary S-PMA increased along with the environment benzene in every period and had significantly difference in the different exposed groups (P < 0.01 or P < 0.05), but did not change along with the exposed time course (P > 0.05). In the cohort study, the urinary S-PMA in the high-dose group [(27.2 +/- 7.9)microg/L] was significantly higher than the low-dose group [(13.6 +/- 3.4)microg/L] (P < 0.01). Otherwise, the background of urinary S-PMA was lower than 5microg/L in both workers and rat models.

CONCLUSIONThe urinary S-PMA can be proposed as a sensitive biomarker of occupational benzene exposure.

Acetylcysteine ; analogs & derivatives ; urine ; Adult ; Animals ; Benzene ; administration & dosage ; toxicity ; Environmental Exposure ; adverse effects ; Female ; Humans ; Male ; Middle Aged ; Rats ; Rats, Wistar ; Young Adult

OBJECTIVETo establish the biological exposure limit values of urinary S-phenylmercapturic acid (SPMA) for assessing occupational exposure to benzene.

METHODSStudy participants were selected from 55 workers of benzene exposures below 32.5 mg/m(3). The concentration of personal exposure to benzene was measured by gas chromatography and sampled with personal sampler. The urine samples were collected at the end of work shift and individual internal exposure level was evaluated by determination of SPMA in urine by HPLC/MS method. Comparison of external and internal exposure was assessed by the relative internal exposure (RIE) index.

RESULTSThe benzene exposure level ranged from 0.71 to 32.17 mg/m(3) (geometric mean 6.98 mg/m(3), median 7.50 mg/m(3)). The urinary SPMA at the end of the work shift were significantly correlated with benzene exposure, (microg/g Cr) = -8.625 + 18.367X (mg/m(3)), r = 0.8035, (P < 0.01). According to the occupational exposure limit for benzene in China and calculation of regression equation, the expected value of urinary SPMA was 101.58 microg/g Cr. Mean level of biotransformation of per mg/m(3) benzene to urinary SPMA was 18.23 microg/g Cr and the metabolic efficiencies of benzene transformation to urinary SPMA decreased with benzene exposure increased.

CONCLUSIONBased on abroad documents and data, biological limit value for occupational exposure to benzene in China is recommended as follows: 100 microg/g Cr (47 micromol/mol Cr) for SPMA in the urine at the end of shift.

Acetylcysteine ; analogs & derivatives ; urine ; Adult ; Benzene ; adverse effects ; analysis ; Benzene Derivatives ; urine ; China ; Humans ; Middle Aged ; Occupational Exposure ; adverse effects ; analysis ; Threshold Limit Values ; Young Adult

OBJECTIVE: To observe the effects of N-acetyl-L-cysteine (L-NAC) protect hair cells in the rat cochlea from injury of exposure to styrene. METHOD: Seventeen adult Long Evans rats were used in present study. The animals were randomly assigned into test group (n=9) and control group (n=8). The animals were exposed to styrene by gavage at 400 mg/kg (2 g styrene was mixed with 1 ml olive oil). Test group animals received styrene exposure plus L-NAC 325 mg/kg (L-NAC was dissolved in physiological saline solution) by intraperitoneal injection. Treatment was performed once a day, 5 days per week for 3 weeks. Control group animals received the same volume of saline injection on an identical time schedule used for the test group. The auditory brainstem response (ABR) thresholds of both ears elicited with clicks were measured before and at the end of the 3-week styrene or styrene plus L-NAC treatment. After hearing was re-assessed, animals were sacrificed and cochleae were quickly removed from the skull. Following fixation, whole specimens comprising the basilar membrane with Corti's organ were separated from the modiolus. The organs of Corti were stained with propidium iodide (PI) and the TUNEL assay to visualize the morphologic viability of hair cell nuclei, FITC-labeled phalloidin, a F-actin intercalating fluorescent probe used to visualize the morphologic viability of cuticular plate and the stereocilia in the hair cells. Each organ of Corti was thoroughly examined using fluorescence microscopy. The numbers of damaged OHCs (apoptotic, necrotic and missing OHCs) were documented. RESULT: There was a statistically significant decrease in ABR threshold shift (P<0.05) in the styrene-plus-L-NAC treated animals. The average percentage of damaged OHCs in the styrene-treated animals was 28.3%. In contrast, the average percentage of OHC damage in the styrene-plus-L-NAC treated group was only 10.6% (P<0.01). The percentage of reduction in the number of apoptotic cells in styrene-plus-L-NAC treated group was 78% (P<0.01). However, the mean reduction of necrotic cells was only 23% (P>0.05). CONCLUSION The results indicate that the treatment with L-NAC may effectively protect against the styrene-induced hair cells damage and preferably reduce the number of apoptotic OHCs.
Acetylcysteine ; analogs & derivatives ; pharmacology ; Animals ; Antioxidants ; pharmacology ; Cochlea ; cytology ; drug effects ; Evoked Potentials, Auditory, Brain Stem ; Hair Cells, Auditory ; drug effects ; pathology ; Lysine ; analogs & derivatives ; pharmacology ; Rats ; Rats, Long-Evans ; Styrene ; adverse effects

Reactive oxygen species (ROS) play an important role in the pathogenesis of airway inflammation and hyperresponsiveness. Recent studies have demonstrated that antioxidants are able to reduce airway inflammation and hyperreactivity in animal models of allergic airway disease. A newly developed antioxidant, small molecular weight thiol compound, N-acetylcysteine amide (AD4) has been shown to increase cellular levels of glutathione and to attenuate oxidative stress related disorders such as Alzheimer's disease, Parkinson's disease, and multiple sclerosis. However, the effects of AD4 on allergic airway disease such as asthma are unknown. We used ovalbumin (OVA)-inhaled mice to evaluate the role of AD4 in allergic airway disease. In this study with OVA-inhaled mice, the increased ROS generation, the increased levels of Th2 cytokines and VEGF, the increased vascular permeability, the increased mucus production, and the increased airway resistance in the lungs were significantly reduced by the administration of AD4. We also found that the administration of AD4 decreased the increases of the NF-kappaB and hypoxia-inducible factor-1alpha (HIF-1alpha) levels in nuclear protein extracts of lung tissues after OVA inhalation. These results suggest that AD4 attenuates airway inflammation and hyperresponsiveness by regulating activation of NF-kappaB and HIF-1alpha as well as reducing ROS generation in allergic airway disease.
Acetylcysteine/*analogs & derivatives/therapeutic use ; Animals ; Asthma/drug therapy/*immunology/pathology ; Bronchial Hyperreactivity/*drug therapy/metabolism ; Hypoxia-Inducible Factor 1, alpha Subunit/*metabolism ; Mice ; NF-kappa B/*metabolism ; Ovalbumin/immunology ; Reactive Oxygen Species/*metabolism ; Vascular Endothelial Growth Factor A/metabolism