Use of urinary hippuric acid and o-/p-/m-methyl hippuric acid to evaluate surgical smoke exposure in operating room healthcare personnel

Circulating metabolites are associated with persistent elevations of ALT in patients with chronic hepatitis B with complete viral suppression

Hepatitis B virus (HBV) can be completely suppressed after antiviral treatment; however, some patients with chronic hepatitis B (CHB) exhibit elevated alanine aminotransferase (ALT) levels and sustained disease progression. This study provides novel insights into the mechanism and potential predictive biomarkers of persistently elevated ALT (PeALT) in patients with CHB after complete viral inhibition. Patients having CHB with undetectable HBV DNA at least 12 months after antiviral treatment were enrolled from a prospective, observational cohort. Patients with PeALT and persistently normal ALT (PnALT) were matched 1:1 using propensity score matching. Correlations between plasma metabolites and the risk of elevated ALT were examined using multivariate logistic regression. A mouse model of carbon tetrachloride-induced liver injury was established to validate the effect of key differential metabolites on liver injury. Of the 1238 patients with CHB who achieved complete viral suppression, 40 (3.23%) had PeALT levels during follow-up (median follow-up: 2.42 years). Additionally, 40 patients with PnALT levels were matched as controls. Ser-Phe-Ala, Lys-Ala-Leu-Glu, 3-methylhippuric acid, 3-methylxanthine, and 7-methylxanthine were identified as critical differential metabolites between the two groups and independently associated with PeALT risk. Ser-Phe-Ala and Lys-Ala-Leu-Glu levels could be used to discriminate patients with PeALT from those with PnALT. Furthermore, N-acetyl- l-methionine (NALM) demonstrated the strongest negative correlation with ALT levels. NALM supplementation alleviated liver injury and hepatic necrosis induced by carbon tetrachloride in mice. Changes in circulating metabolites may contribute to PeALT levels in patients with CHB who have achieved complete viral suppression after antiviral treatment.

Rapid determination of hippuric acid as an exposure biomarker of toluene using a colorimetric assay and comparison with high-performance liquid chromatography

Occupational exposure to toluene is associated with health risks that require reliable monitoring methods. Hippuric acid (HA), a urinary metabolite of toluene, serves as a valuable biomarker for such exposure. Colorimetric methods for the quantitative determination of HA have gained prominence due to their simplicity, cost-effectiveness, and suitability for field application. In the present study, a simple colorimetric technique was optimized for the determination of HA in the urine sample, and compared with a usual HPLC technique. The central composite design (CCD) was applied to examine the effective parameters on the colorimetric determination of HA. The calibration curve for HA was established within the concentration range of 6 to 100 mg L-1 with R2 = 0.97. The detection limit (LOD) and quantification limit (LOQ) were determined to be 1.8 mg L-1 and 6 mg L-1 respectively. The relative standard deviation (RSD%) was less than 5%, and the recovery% (R%) was 90.5-100.1. The overall results showed good agreement between the colorimetric and HPLC results. There was a significant relationship between the results obtained from HPLC and colorimetric methods especially for higher concentration levels of HA (≥ 500 mg/g creatinine). In conclusion, our optimized colorimetric method is a simple, cost-effective, and rapid method for determination of HA in occupational exposure, which is comparable with the HPLC technique.

Surgical smoke and its components, effects, and mitigation: a contemporary review

Energy-based surgical instruments produce surgical smoke, which contains harmful byproducts, such as polycyclic aromatic hydrocarbons, volatile organic compounds, particulate matter, and viable microorganisms. The research setting has shifted from the laboratory to the operating room. However, significant heterogeneity in the methods of detection and placement of samplers, diversity in the tissue operated on, and types of surgeries tested has resulted in variability in detected levels and composition of surgical smoke. State regulation limiting surgical smoke exposure through local evacuators is expanding but has yet to reach the national regulatory level. However, most studies have not shown levels above standard established limits but relatively short bursts of high concentrations of these harmful by-products. This review highlights the limitations of the current research and unsupported conclusions while also suggesting further areas of interest that need more focus to improve Occupational Safety and Health Administration guidelines.

Synthesis and application of quaternary amine-functionalized core-shell-shell magnetic polymers for determination of metabolites of benzene, toluene and xylene in human urine samples and study of exposure assessment

As production processes have evolved, airborne concentrations of benzene, toluene and xylene in many workplaces are already well below the occupational exposure limits. However, studies have shown that low levels of exposure to benzene, toluene and xylene can still cause health effects in people exposed occupationally. However, there is no literature on health risk assessment of internal exposure. In view of this, an analytical method based on quaternary amine-functionalized core-shell-shell magnetic polymers (QA-CSS-MPs) was developed for the determination of seven metabolites in urine by MSPE-UPLC-DAD-HRMS. Furthermore, an improved QuEChERS method for the extraction of seven metabolites from human urine samples was introduced for the first time and satisfactory extraction rates were achieved. In addition, QA-CSS-MPs microspheres with core-shell-shell structure were designed and synthesized, and the morphology, composition and magnetic properties of the materials were fully characterized to verify the rationality of the synthetic route. Subsequently, QA-CSS-MPs microspheres were used as magnetic solid-phase extraction (MSPE) adsorbents for the purification of urine extracts, and UPLC-DAD-HRMS was used for the detection of seven metabolites. As a result, this method allows the accurate determination of seven metabolites in urine samples over an ultra-wide concentration range (0.001-100 mg/L). Under optimal experimental conditions, i.e., 2% hydrochloric acid in urine for the hydrolysis and 20 mg of QA-CSS-MPs for 5 min purification, the spiked recoveries of the seven target metabolites ranged from 81.5% to 117.7% with RSDs of 1.0%-9.4%. The limits of detection (LODs, S/N≥3) for the established method were in the range of 0.2-0.3 μg/L. The developed method was applied to 254 human urine samples for the determination of seven metabolites. The results showed that the concentration distributions of three xylene metabolites in urine, 2-MHA, 3-MHA, 4-MHA and total MHA, showed statistically significant differences for occupational exposure (p<0.001). In addition, the results of the internal exposure assessment showed that there is a high potential health risk associated with occupational exposure processes.

Exposure assessment of wastewater treatment plant employees to BTEX: a biological monitoring approach

To monitor employees' work safety and exposure against air contaminants, Trans, trans-muconic acid, Hippuric acid, Methyl hippuric acid, Mandelic acid and Phenylglyoxylic acid can be used as reliable biomarkers of exposure to benzene, toluene, ethylbenzene, and xylene (BTEX) compounds. This study aims to determine the level of urinary metabolites of BTEX compounds using biological monitoring in the employees of a wastewater treatment plant (WWTP) in the south of Iran. The study was performed on 56 employees of the WWTP of one of the southern cities of Iran in 2020. Urine samples (n total = 112) consisting of 60 samples of employees working in the operation section (exposed group) and 52 samples of employees working in the administrative section (control group) in the WWTP were collected before and at the end of their shift. The mean concentration of urinary metabolites of BTEX of both groups ranged from 546.43 (μg/g cr) for trans, trans-muconic acid to 0.006 (μg/g cr) for methyl hippuric acid, which indicates that most of the evaluated metabolites showed a higher concentration than their occupational threshold limit value urine (p < 0.05). Regression analysis results showed a significant correlation (p < 0.05) between age and utilization of flame heaters with changes in the measured BTEX metabolites in the urine. The results of this study illustrate that WWTPs should be considered as one of the workplaces with potential sources of BTEX exposure for employees. Future investigations are recommended to perform itemized appraisals of BTEX intake sources, particularly in employees of the operational sections of WWTP.

Quantification of Gut Microbiota Dysbiosis-Related Organic Acids in Human Urine Using LC-MS/MS

Urine organic acid contains water-soluble metabolites and/or metabolites—derived from sugars, amino acids, lipids, vitamins, and drugs—which can reveal a human’s physiological condition. These urine organic acids—hippuric acid, benzoic acid, phenylacetic acid, phenylpropionic acid, 4-hydroxybenzoic acid, 4-hydroxyphenyl acetic acid, 3-hydroxyphenylpropionic acid, 3,4-dihydroxyphenyl propionic acid, and 3-indoleacetic acid—were the eligible candidates for the dysbiosis of gut microbiota. The aim of this proposal was to develop and to validate a liquid chromatography−tandem mass spectrometry (LC-MS/MS) bioanalysis method for the nine organic acids in human urine. Stable-labeled isotope standard (creatinine-d3) and acetonitrile were added to the urine sample. The supernatant was diluted with deionized water and injected into LC-MS/MS. This method was validated with high selectivity for the urine sample, a low limit of quantification (10−40 ng/mL), good linearity (r > 0.995), high accuracy (85.8−109.7%), and high precision (1.4−13.3%). This method simultaneously analyzed creatinine in urine, which calibrates metabolic rate between different individuals. Validation has been completed for this method; as such, it could possibly be applied to the study of gut microbiota clinically.

Rapeseed oil-based hippurate amide nanocomposite coating material for anticorrosive and antibacterial applications

Industrial crops and products have proved to be an excellent alternative to petro-based chemicals. Vegetable oils are rich in functional groups that can be transformed into monomers and polymers with applications such as biodiesel, lubricants, inks, coatings, and paints. This study describes the synthesis of rapeseed oil (RO)-based esteramide for the first time. The reaction was carried out by amidation of RO, producing diol fatty amide (N,N-bis(2-hydroxyethyl) RO fatty amide), followed by its esterification reaction with hippuric acid, resulting in RO-based hippurate amide (ROHA). Fourier-transform infrared spectroscopy and nuclear magnetic resonance confirmed the introduction of amide and ester moieties in ROHA. ROHA was further reinforced with silver nanoparticles (SNPs) to develop corrosion-protective nanocomposite coatings. ROHA/SNP coatings were scratch-resistant, impact-resistant, and flexible and showed good corrosion resistance performance toward 3.5 w/w% NaCl medium, with adequate corrosion protection efficiency, and antimicrobial behavior against Staphylococcus aureus, Chromobacterium violaceum, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans. ROHA/SNP coatings can be safely used up to 250°C.

Analytical techniques for monitoring of toluene and xylene exposure biomarkers hippuric acid and methylhippuric acid in human urine samples

Quantification of hippuric acid and methylhippuric acid in human urine matrices provides information on the toluene and xylene exposure conditions. High performance liquid chromatography coupled with UV detection is the preferable technique for hippuric acid and methylhippuric acid detection in human urine. This study was conducted to present analytical techniques developed for monitoring of hippuric acid and methylhippuric acid in human urine matrices during 2016-2021.