OBJECTIVETo develop a method for determination of mandelic acid (MA) and phenylglyoxylic acid (PGA) in urine by reagent-free ion chromatography.

METHODSIon chromatography was performed on an AS19 column with a gradient elution solution containing 10-35 mmoL/L KOH at a flow rate of 1.00 ml/min, and MA and PGA were detected at ultraviolet wavelengths of 225 nm and 254 nm, respectively. The samples were diluted 10 times with purified water, then purified on a silver column to remove high concentrations of chloride ion, and injected after being filtered through a 0.2-µm m filter membrane.

RESULTSThe recoveries of standard addition of MA and PGA were 96.5% and 99.3%, respectively, with both relative standard deviations less than 5.0%. Good linear relationships were noted in the range of 1.0-100.0 mg/L for both MA and PGA (r >0.9995). The detection limits of MA and PGA were 0.02 mg/L and 0.05 mg/L, respectively; the minimum detectable concentrations of MA and PGA were 0.2 mg/L and 0.5 mg/L (when the sampling amount was 5.0 ml and diluted to 50.0 ml with water, and the injection volume was 300 µL).

CONCLUSIONSThis method is fast, convenient, and highly sensitive and selective. It can be used for the analysis of MA and PGA in the urine of styrene-exposed workers.

Chromatography, Ion Exchange ; Glyoxylates ; urine ; Humans ; Mandelic Acids ; urine ; Styrene

OBJECTIVETo establish a GC/MS method for analysis of cotinine (COT), phenylglyoxylic acid (PA) and mandelic acid (MA) in human urine.

METHODSHuman urine samples were extracted by CCl(3) and derivatized with MSTFA after dried completely. The contents of COT, PA and MA were measured by GC/MS method with DB-5MS capillary column and EI ion-source.

RESULTThe calibration curves for COT in urine samples were linear over the concentration ranges of 0.0002 approximately 3.5 microg ml(-1), while PA and MA were both of 1.25 approximately 160 microg ml(-1). The limits of quantification were 0.0002 microg ml(-1), 1.25 microg ml(-1) and 1.25 microg ml(-1) for COT, PA and MA, respectively. The assay recoveries for COT, PA and MA ranged from 89.53% approximately 102.4%, 84.88% approximately 91.46% and 83.46% approximately 13.6%, respectively.

CONCLUSIONThe established method can detect cotinine, phenylglyoxylic acid and mandelic acid simultaneously, which would be used in routine assessment and monitoring of the internal exposure to nicotine and styrene in human body.

Cotinine ; urine ; Environmental Pollutants ; urine ; Gas Chromatography-Mass Spectrometry ; Glyoxylates ; urine ; Humans ; Mandelic Acids ; urine

Primary hyperoxaluria is a rare disorder of glyoxylate metabolism in which hepatic enzyme deficiencies result in overproduction of oxalate. The resulting elevation of urinary oxalate excretion leads to recurrent urolithiasis and progressive nephrocalcinosis. End-stage renal disease frequently occurs and is accompanied by systemic oxalate deposition along with its harmful effects. With the rarity and various clinical heterogeneity of the disease, the high proportion of patients in whom diagnosis is made after advanced renal failure have developed it. On account of its high rate of graft loss associated with primary hyperoxaluria, isolated kidney transplantation has been replaced by combined liver/kidney transplantation. In this report, we describe a case of primary hyperoxaluria with kidney graft failure who had a history of recurrent renal stones.
Glyoxylates ; Humans ; Hyperoxaluria, Primary ; Kidney ; Kidney Failure, Chronic ; Kidney Transplantation ; Nephrocalcinosis ; Population Characteristics ; Renal Insufficiency ; Transplantation, Homologous ; Transplants ; Urolithiasis

Ethylene glycol (EG) is a sweet-tasting, odorless organic solvent found in many agents, such as anti-freeze. EG is composed of four organic acids: glycoaldehyde, glycolic acid, glyoxylic acid and oxalic acid in vivo. These metabolites are cellular toxins that can cause cardio-pulmonary failure, life-threatening metabolic acidosis, central nervous system depression, and kidney injury. Oxalic acid is the end product of EG, which can precipitate to crystals of calcium oxalate monohydrate in the tubular lumen and has been linked to acute kidney injury. We report a case of EG-induced oxalate nephropathy, with the diagnosis confirmed by kidney biopsy, which showed acute tubular injury of the kidneys with extensive intracellular and intraluminal calcium oxalate monohydrate crystal depositions.
Acidosis ; Acute Kidney Injury ; Biopsy ; Calcium Oxalate ; Central Nervous System ; Depression ; Ethylene Glycol ; Ethylenes ; Glycolates ; Glyoxylates ; Kidney ; Oxalic Acid

OBJECTIVETo explore the adduct characteristics of styrene and DNA.

METHODSThe adduct reactions between styrene, urinary mandalic acid(MA), phenylglyoxalic acid(PGA), mercapturic acid of styrene (UMA) and DNA were studied by ultraviolet spectral analysis. The SO-DNA adducts by 32P-post labeled method, the chemical structures of SO-DNA adducts by GC-MS and NMR were also studied.

RESULTSSO combined with DNA at O6, N2 positions of dGMP to form six adducts, but styrene, urinary mandalic acid, phenylglyoxalic acid and mercapturic acid of styrene did not react with DNA to form adduct.

CONCLUSIONSStyrene formed adduct with DNA through its active center metabolite--SO after entering the body. SO combined with DNA at O6, N2 positions of dGMP to form adducts. If these DNA adducts are not repaired or are mis-repaired before cell duplication, the gene mutation and chemical damage would happen. No adduct reactions are seen among other metabolites of styrene.

Acetylcysteine ; metabolism ; DNA ; metabolism ; DNA Adducts ; metabolism ; DNA Repair ; Glyoxylates ; metabolism ; Humans ; Mandelic Acids ; metabolism ; Styrene ; metabolism

The glyoxylate cycle was hypothesed to be indispensable for glutamate overproduction in coryneform bacteria, for it was thought to fulfill anaplerotic functions and to supply energy during the growth phase. During glutamate overproduction phase, however, it has been noted that the high level of the cycle is detrimental to the glutamate production. In order to clarify the relationship between the glutamate production and the glyoxylate cycle, a chromosomal aceA-disrupted mutant of wild-type C. glutamicum ATCC 13032 was constructed. The isocitrate lyase (ICL) activity of the parental strain was 0.011 u/mg of protein and reached 1.980 u/mg of protein after acetate induction; the mutant strain WTdeltaA, however, had no detectable ICL activity and was no longer able to grow on minimal medium with acetate as the sole carbon source. Compared with the wild-type C. glutamicum WT, the mutant strain WTdeltaA, exhibited the same growth rate with glucose as the sole carbon source, indicating glyoxylate cycle is not required for its growth on glucose. On the contrary, the glutamate production in WTdeltaA was severely impaired and more residual glucose was found in the fermentation broth at the end of fermentation with the mutant strain than with the wild-type strain. Further investigations into the relationship between the glutamate production and the glyoxylate cycle are under the way, which may help to elucidate the mechanism of glutamate overproduction.
Corynebacterium glutamicum ; genetics ; growth & development ; metabolism ; Culture Media ; Fermentation ; Glucose ; metabolism ; Glutamic Acid ; biosynthesis ; Glyoxylates ; metabolism ; Isocitrate Lyase ; metabolism

OBJECTIVETo investigate the role of genetic polymorphisms of epoxide hydrolase 1 (EPHX1) in the metabolism of styrene in vivo.

METHODSFifty-six styrene-exposed workers, who worked in the painting workshop of an enterprise for manufacturing glass fiber-reinforced plastic yachts in Shandong Province, China for over one year and were protected in approximately the same way, were selected as study subjects. The 8-hour time-weighted average concentration (8 h-TWA) of styrene and the concentrations of mandelic acid (MA) and phenyl glyoxylic acid (PGA) as urinary metabolites were measured. The genetic polymorphisms of EPHX1 were detected by polymerase chain reaction-restriction fragment length polymorphism analysis.

RESULTSThe urinary concentrations of MA and PGA were 177.25±82.36 mg/g Cr and 145.91±69.73 mg/g Cr, respectively, and the 8 h-TWA of styrene was 133.28±95.81 mg/m3. Urinary concentrations of MA and PGA were positively correlated with 8 h-TWA of styrene (R=0.861, P < 0.05; R=0.868, P < 0.05). The subjects were divided into high-exposure group (8 h-TWA >50 mg/m(3)) and low-exposure group (8 h-TWA ≤ 50 mg/m(3), and in the two groups, the urinary concentrations of MA and PGA were significantly higher in the individuals carrying high-activity genotypes of EPHX1 than in those carrying low-activity genotypes of EPHX1 (P < 0.05).

CONCLUSIONGenetic polymorphisms of EPHX1 play an important role in the metabolic process of styrene in vivo.

Adult ; Air Pollutants, Occupational ; pharmacokinetics ; China ; Epoxide Hydrolases ; genetics ; Glyoxylates ; urine ; Humans ; Male ; Mandelic Acids ; urine ; Occupational Exposure ; Polymorphism, Genetic ; Styrene ; pharmacokinetics

OBJECTIVETo study the biomarkers of styrene and to provide theoretical basis for bio-monitoring of styrene.

METHODSUrinary mandalic acid (MA), phenylglyoxalic acid (PGA) and mercapturic acid (MUA) of styrene were examined by high performance liquid chromatography (HPLC).

RESULTSThe correlation regression equations between exposure dose and MA, PGA and MUA level in morning urinary samples were: ŷ = 2.58x + 70.82; ŷ = 1.66x + 37.42; ŷ = 0.05x + 0.55 respectively. The correlation regression equations between exposure dose and MA, PGA and MUA level in post-shift urinary samples were: ŷ = 1.85x + 89.02; ŷ = 1.33x + 4.32; ŷ = 0.04x + 0.68 respectively. All showed close dose-response relationship.

CONCLUSIONSThe level of MA, PGA and MUA in morning or post-shift urinary samples may be used as bio-monitoring indexes of styrene.

Acetylcysteine ; urine ; Adult ; Biomarkers ; Chromatography, High Pressure Liquid ; Environmental Monitoring ; Glyoxylates ; urine ; Humans ; Male ; Mandelic Acids ; urine ; Regression Analysis ; Styrene ; metabolism

OBJECTIVES: In this study, we summarized the External Quality Assessment Scheme (EQAS) for the biological monitoring of occupational exposure to toxic chemicals which started in 1995 and continued until a 31st round robin in the spring of 2010. The program was performed twice per year until 2009, and this was changed to once a year since 2010. The objective of the program is to ensure the reliability of the data related to biological monitoring from analytical laboratories. METHODS: One hundred and eighteen laboratories participated in the 31st round robin. The program offers 5 items for inorganic analysis: lead in blood, cadmium in blood, manganese in blood, cadmium in urine, and mercury in urine. It also offers 10 items for organic analysis, including hippuric acid, methylhippuric acid, mandelic acid, phenylglyoxylic acid, N-methylformamide, N-methylacetamide, trichloroacetic acid, total trichloro-compounds, trans,trans-muconic acid, and 2,5-hexanedione in urine. Target values were determined by statistical analysis using consensus values. All the data, such as chromatograms and calibration curves, were reviewed by the committee. RESULTS: The proficiency rate was below 70% prior to the first round robin and improved to over 90% for common items, such as PbB and HA, while those for other items still remained in the range of 60-90% and need to be improved up to 90%. CONCLUSION: The EQAS has taken a primary role in improving the reliability of analytical data. A total quality assurance scheme is suggested, including the validation of technical documentation for the whole analytical procedure.
Acetamides ; Cadmium ; Calibration ; Consensus ; Dietary Sucrose ; Environmental Monitoring ; Formamides ; Glyoxylates ; Hexanones ; Hippurates ; Mandelic Acids ; Manganese ; Occupational Exposure ; Songbirds ; Sorbic Acid ; Trichloroacetic Acid

OBJECTIVES: This study was designed to investigate whether long-term, low-level exposure to monocyclic aromatic hydrocarbons (MAHs) induced insulin resistance. METHODS: The subjects were 110 male workers who were occupationally exposed to styrene, toluene, and xylene. One hundred and ten age-matched male workers who had never been occupationally exposed to organic solvents were selected as a control group. Cytokines, which have played a key role in the pathogenesis of insulin resistance, and oxidative stress indices were measured. Assessment of exposure to MAHs was performed by measuring their ambient levels and their urinary metabolites in exposed workers, and the resulting parameters between the exposed group and non-exposed control groups were compared. RESULTS: There was no significant difference in general characteristics and anthropometric parameters between the two groups; however, total cholesterol, fasting glucose, fasting insulin, and homeostasis model assessment of insulin resistance levels were significantly higher in the exposed group. Phenylglyoxylic acid levels showed significant association with tumor necrosis factor-alpha, total oxidative status, and oxidative stress index via multiple linear regression analysis. Further, there was a negative correlation between methylhippuric acid levels and total anti-oxidative capacity, and there was a significant relationship between MAHs exposure and fasting glucose levels, as found by multiple logistic regression analysis (odds ratio = 3.95, 95% confidence interval = 1.074-14.530). CONCLUSION: This study indicated that MAHs increase fasting glucose level and insulin resistance. Furthermore, these results suggested that absorbing the organic solvent itself and active metabolic intermediates can increase oxidative stress and cytokine levels, resulting in the changes in glucose metabolism and the induction of insulin resistance.
Cholesterol ; Cytokines ; Fasting ; Glucose ; Glyoxylates ; Homeostasis ; Humans ; Hydrocarbons, Aromatic ; Insulin ; Insulin Resistance ; Linear Models ; Logistic Models ; Male ; Mandelic Acids ; Occupations ; Oxidative Stress ; Solvents ; Styrene ; Toluene ; Tumor Necrosis Factor-alpha ; Xylenes