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

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

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

Bortezomib is a proteasome inhibitor used for the treatment of relapsed/refractory multiple myeloma (MM). However, intrinsic and acquired resistance to bortezomib has already been observed in MM patients. In a previous report, we demonstrated that changes in the expression of mitochondrial genes lead to changes in mitochondrial activity and bortezomib susceptibility or resistance, and their combined effects contribute to the differential sensitivity or resistance of MM cells to bortezomib. Here we report that the combination treatment of bortezomib and 2-methoxyestradiol (2ME), a natural estrogen metabolite, induces mitochondria-mediated apoptotic cell death of bortezomib-resistant MM KMS20 cells via mitochondrial reactive oxygen species (ROS) overproduction. Bortezomib plus 2ME treatment induces a higher level of cell death compared with treatment with bortezomib alone and increases mitochondrial ROS and Ca2+ levels in KMS20 cells. Pretreatment with the antioxidant N-acetyl-L-cysteine scavenges mitochondrial ROS and decreases cell death after treatment with bortezomib plus 2ME in KMS20 cells. Moreover, we observed that treatment with bortezomib plus 2ME maintains the activation of c-Jun N-terminal kinase (JNK) and mitogen-activated protein kinase kinase kinase 4/7 (MKK4/7). Collectively, combination treatment with bortezomib and 2ME induces cell death via JNK-MKK4/7 activation by overproduction of mitochondrial ROS. Therefore, combination therapy with specific mitochondrial-targeting drugs may prove useful to the development of novel strategies for the treatment of bortezomib-resistant MM patients.
Acetylcysteine/pharmacology ; Apoptosis/*drug effects ; Boronic Acids/*pharmacology ; Calcium/metabolism ; Cell Line, Tumor ; *Drug Resistance, Neoplasm ; Drug Synergism ; Estradiol/*analogs & derivatives/pharmacology ; Humans ; Mitochondria/drug effects/metabolism ; Mitogen-Activated Protein Kinase Kinases/metabolism ; Pyrazines/*pharmacology ; Reactive Oxygen Species/metabolism

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

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

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

BACKGROUND AND OBJECTIVEHirsutanol A is a novel sesquiterpene compound purified from fungus chondrostereum sp in Sarcophyton tortuosum. Its pharmacologic effect has not been reported yet. This study aimed to investigate cytotoxic effect of Hirsutanol A on hepatocellular carcinoma (HCC) cells and its mechanism.

METHODSHep3B cells were treated with different concentrations of Hirsutanol A. Cell proliferation was detected by MTT assay. The protein expression of LC3 was determined by Western blot. The generation of reactive oxygen species (ROS) was monitored by flow cytometry.

RESULTSHirsutanol A significantly inhibited proliferation of Hep3B cells with 50% inhibition concentrations (IC50) of 14.54, 6.71, and 3.59 micromol/L when exposed to Hirsutanol A for 24, 48, and 72 h, respectively. Incubation of Hep3B cells with Hirsutanol A markedly increased the level of ROS and the autophagy marker MAP-LC3 conversion from type I to type II. Pre-incubation with an antioxidant N-acetyl cystein (NAC) decreased the level of ROS, and reduced MAP-LC3 I-II conversion, and suppressed cell death. Blocking autophagy with a specific autophagy inhibitor 3-methyladenine (3-MA), the cytotoxic effect of this compound was attenuated.

CONCLUSIONHirsutanol A has potent cytotoxic effect, and can induce autophagic cell death via increasing ROS production.

Acetylcysteine ; pharmacology ; Adenine ; analogs & derivatives ; pharmacology ; Agaricales ; chemistry ; Antineoplastic Agents ; administration & dosage ; isolation & purification ; pharmacology ; Autophagy ; drug effects ; Carcinoma, Hepatocellular ; metabolism ; pathology ; Cell Death ; drug effects ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Dose-Response Relationship, Drug ; Free Radical Scavengers ; pharmacology ; Humans ; Liver Neoplasms ; metabolism ; pathology ; Microtubule-Associated Proteins ; metabolism ; Reactive Oxygen Species ; metabolism ; Sesquiterpenes ; administration & dosage ; isolation & purification ; pharmacology

The inhibition of protein degradation through the ubiquitin-proteasome pathway is a recently developed approach to cancer treatment which extends the range of cellular target for chemotherapy. This therapeutic strategy is very interesting since the proteasomes carry out the regulated degradation of unnecessary or damaged cellular proteins, a process that is dysregulated in many cancer cells. Based on this hypothesis, the proteasome complex inhibitor Bortezomib was approved for use in multiple myeloma patients by FDA in 2003. Drug discovery programs in academy and the pharmaceutical industry have developed a range of synthetic and natural inhibitors of the 20S proteasome core particle that have entered human clinical trials as significant anti-cancer leads. The main results from the use of proteasome inhibition in cancer chemotherapy, the structure of several proteasome inhibitors and their synthesis is going to be reviewed in this paper.
Acetylcysteine ; analogs & derivatives ; chemical synthesis ; chemistry ; Antineoplastic Agents ; chemical synthesis ; classification ; therapeutic use ; Boronic Acids ; chemical synthesis ; chemistry ; therapeutic use ; Bortezomib ; Cysteine Proteinase Inhibitors ; chemical synthesis ; classification ; Dipeptides ; chemical synthesis ; chemistry ; Humans ; Multiple Myeloma ; drug therapy ; enzymology ; Peptides, Cyclic ; chemical synthesis ; chemistry ; Proteasome Endopeptidase Complex ; metabolism ; Proteasome Inhibitors ; Pyrazines ; chemical synthesis ; chemistry ; therapeutic use ; Ubiquitin ; antagonists & inhibitors ; metabolism

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