Simultaneous determination of tyrosine, phenylalanine and deoxyguanosine oxidation products by liquid chromatography–tandem mass spectrometry as non-invasive biomarkers for oxidative damage

Multi-Omics Profiling of Candida albicans Grown on Solid Versus Liquid Media

Candida albicans is a common pathogenic fungus that presents a challenge to healthcare facilities. It can switch between a yeast cell form that diffuses through the bloodstream to colonize internal organs and a filamentous form that penetrates host mucosa. Understanding the pathogen's strategies for environmental adaptation and, ultimately, survival, is crucial. As a complementary study, herein, a multi-omics analysis was performed using high-resolution timsTOF MS to compare the proteomes and metabolomes of Wild Type (WT) Candida albicans (strain DK318) grown on agar plates versus liquid media. Proteomic analysis revealed a total of 1793 proteins and 15,013 peptides. Out of the 1403 identified proteins, 313 proteins were significantly differentially abundant with a p-value < 0.05. Of these, 156 and 157 proteins were significantly increased in liquid and solid media, respectively. Metabolomics analysis identified 192 metabolites in total. The majority (42/48) of the significantly altered metabolites (p-value 0.05 FDR, FC 1.5), mainly amino acids, were significantly higher in solid media, while only 2 metabolites were significantly higher in liquid media. The combined multi-omics analysis provides insight into adaptative morphological changes supporting Candida albicans' life cycle and identifies crucial virulence factors during biofilm formation and bloodstream infection.

Metabolomic Profile, Plasmatic Levels of Losartan and EXP3174, Blood Pressure Control in Hypertensive Patients and Their Correlation with COVID-19

Systemic arterial hypertension (SAH) is one of the most prevalent chronic diseases worldwide and is related to serious health complications. It has been pointed out as a major risk factor for COVID-19. This study aimed to determine the impact of COVID-19 on the metabolomic profile, the correlation with the plasmatic levels of losartan and its active metabolite (EXP3174), biochemical markers, and blood pressure (BP) control in hypertensive patients. 1H NMR metabolomic profiles of hypertensive and normotensive patients with and without previous COVID-19 diagnosis were identified. Plasmatic levels of LOS and EXP3174 were correlated with BP, biochemical markers, and the metabolomic fingerprint of the groups. Biomarkers linked to important aspects of SAH and COVID-19 were identified, such as glucose, glutamine, arginine, creatinine, alanine, choline, erythritol, homogentisate, 0-tyrosine, and 2-hydroxybutyrate. Those metabolites are indicative of metabolic alterations, kidney damage, pulmonary dysfunction, and persistent inflammation, which can be found in both diseases. Some hypertensive patients did not reach the therapeutic levels of LOS and EXP3174, while the BP control was also limited among the normotensive patients with previous COVID-19 diagnoses. Metabolomics proved to be an important tool for assessing the effectiveness of losartan pharmacotherapy and the damage caused by SAH and COVID-19 in hypertensive patients.

A high-performance SERS imprinted membrane based on Ag/CNTs for selective detection of spiramycin

In this test, the eggshell membrane (ESM) is selected as the support membrane for the biocompatibility and anchors CNTs on the surface to increase the mechanical properties. Then Ag NPs are decorated on CNTs-ESM substrate as SERS substrate by twice in-situ reduction. Finally, a layer of imprinted polymers is coated on the surface of the substrate to synthesize the imprinted membrane for selective detection of spiramycin. It is exhibited from the characteristic results that the CNTs significantly increase the mechanical properties and the detection sensitivity, simultaneously. When the concentration of SP changes between 10^-6 ∼ 10^-11 M, there is a linear relationship between SERS intensity and SP concentration. The detection limit is 10^-11 M, and the correlation coefficient R² is 0.9864. The SERS imprinted membrane can be applied into the detection of antibiotics in practical sample, which broadens the research field of antibiotics detection.

An amino acid fertilizer improves the emergent accumulator plant Nasturtium officinale R. Br. phytoremediation capability for cadmium-contaminated paddy soils

Cadmium (Cd) contamination of paddy soil affects safe crop production. This study aimed to evaluate the effects of plant biostimulant amino acid fertilizer on the phytoremediation capability of an emergent accumulator plant Nasturtium officinale R. Br. for Cd-contaminated paddy soils. A pot study was carried out to study the effects of different concentrations of amino acid fertilizer on the Cd accumulation of N. officinale grown in Cd-contaminated paddy soil. The amino acid fertilizer increased the biomass of N. officinale. The amino acid fertilizer concentration exhibited a quadratic polynomial regression relationship with the root and shoot biomass. The fertilizer also increased the photosynthetic pigment (chlorophyll and carotenoid) contents, peroxidase (POD; EC 1.11.1.7) activity, and catalase (CAT; EC 1.11.1.6) activity of N. officinale, but decreased the soluble protein content and had no significant effect on the superoxide dismutase (SOD; EC 1.15.1.1) activity. Furthermore, the amino acid fertilizer increased the Cd content and Cd extraction of N. officinale. The shoot Cd extraction increased by 29.06%, 63.05%, 77.22%, and 17.40% at 1500-, 1200-, 900-, and 600-fold dilutions of the amino acid fertilizer, respectively, compared with the control. Moreover, the amino acid fertilizer promoted the Cd transport from the roots to shoots of N. officinale. The amino acid fertilizer concentration also exhibited a quadratic polynomial regression relationship with the root Cd content, shoot Cd content, root Cd extraction, and shoot Cd extraction, respectively. The correlation, grey relational, and path analyses revealed that the root biomass, shoot biomass, chlorophyll content, catalase activity, shoot Cd content, and root Cd extraction were closely associated with the shoot Cd extraction. Therefore, the amino acid fertilizer can promote Cd uptake and improve the phytoremediation capability of N. officinale to remediate Cd-contaminated paddy soils, and 900-fold dilution is the most suitable concentration.

A Review of Sensors and Biosensors Modified with Conducting Polymers and Molecularly Imprinted Polymers Used in Electrochemical Detection of Amino Acids: Phenylalanine, Tyrosine, and Tryptophan

Recently, the studies on developing sensors and biosensors-with an obvious interdisciplinary character-have drawn the attention of many researchers specializing in various fundamental, but also complex domains such as chemistry, biochemistry, physics, biophysics, biology, bio-pharma-medicine, and bioengineering. Along these lines, the present paper is structured into three parts, and is aimed at synthesizing the most relevant studies on the construction and functioning of versatile devices, of electrochemical sensors and biosensors, respectively. The first part presents examples of the most representative scientific research focusing on the role and the importance of the phenylalanine, tyrosine, and tryptophan amino acids, selected depending on their chemical structure and their impact on the central nervous system. The second part is dedicated to presenting and exemplifying conductor polymers and molecularly imprinted polymers used as sensitive materials in achieving electrochemical sensors and biosensors. The last part of the review analyzes the sensors and biosensors developed so far to detect amino acids with the aid of conductor polymers and molecularly imprinted polymers from the point of view of the performances obtained, with emphasis on the detection methods, on the electrochemical reactions that take place upon detection, and on the electroanalytical performances. The present study was carried out with a view to highlighting, for the benefit of specialists in medicine and pharmacy, the possibility of achieving and purchasing efficient devices that might be used in the quality control of medicines, as well as in studying and monitoring diseases associated with these amino acids.

The preliminary investigation of potential response biomarkers to PAHs exposure on childhood asthma

BACKGROUND

Exposure to polycyclic aromatic hydrocarbons (PAHs) is a potential risk factor for asthma prevalence. This study aims to explore whether PAHs exposure is associated with childhood asthma by altering microbial diversity and metabolic profiles.

METHODS

Thirty children with asthma and 30 children as control in Nanjing, China were recruited. Urinary 1-hydroxypyrene (1-OHPyr) level was determined by UPLC-Orbitrap-MS as a PAHs exposure biomarker. Logistic regression was conducted to investigate the association between 1-OHPyr and childhood asthma. Microbial diversity was analyzed by 16S rRNA gene sequencing. Metabolic profiles were obtained by UPLC-Orbitrap-MS methods. Differential microbiota and metabolites were screened and selected as response biomarkers or intermediates. Mediation analysis was conducted to assess the association between PAHs and asthma mediated by intermediates.

RESULTS

Participating children with and without asthma aged 6.43 ± 2.23 years. The urinary 1-OHPyr level ranged from 0.10 to 1.51 μmol/mol (creatinine corrected) in the participants. The urinary 1-OHPyr level was associated with childhood asthma (OR = 7.21, 95% CI: 1.03-50.42 per 1 μmol/mol unit). Microbial diversity was decreased in the group with asthma and there was a significant shift in the abundance of Proteobacteria (at the phylum level), Veillonella and Prevotella (at the genus level). The enrichment pathway analysis showed that differentially expressed metabolites were involved in purine metabolism, amino acid metabolism, and lipid and fatty acid metabolism. The urinary 1-OHPyr level was associated with the abundance of Actinomyces sp. oral clone IO076 and 7-methylguanine that showed a mediation effect on the association between urinary 1-OHPyr levels and childhood asthma by mediation analysis.

CONCLUSIONS

Urinary 1-OHPyr exposure was associated with childhood asthma, microbial diversity, and metabolic profiles. Microbial diversity and metabolic profiles may be intermediates as response biomarkers to PAHs exposure in childhood asthma. Further research is needed to confirm these study results and determine the underlying mechanism.

Photo-Oxidation of Therapeutic Protein Formulations: From Radical Formation to Analytical Techniques

UV and ambient light-induced modifications and related degradation of therapeutic proteins are observed during manufacturing and storage. Therefore, to ensure product quality, protein formulations need to be analyzed with respect to photo-degradation processes and eventually protected from light exposure. This task usually demands the application and combination of various analytical methods. This review addresses analytical aspects of investigating photo-oxidation products and related mediators such as reactive oxygen species generated via UV and ambient light with well-established and novel techniques.

Differences in clinical and laboratory biomarkers for short and long-term respiratory outcomes in preterm neonates

BACKGROUND

Pulmonary outcome of premature neonates has focused more on short-term than long-term respiratory morbidities.

OBJECTIVE

Describe risk factors/biomarkers associated with short-term (bronchopulmonary dysplasia [BPD]) (supplemental oxygen use at 36 weeks postmenstrual age [PMA]) and longer-term (chronic respiratory morbidity [CRM]) (respiratory related symptoms, medications, medical/emergency visits, hospitalizations at 6-12 months corrected gestational age [CGA]) respiratory outcomes in a longitudinal cohort.

DESIGN/METHODS

Neonates born at 24-29-week gestation were prospectively followed to 6-12-month CGA. Associations between clinical and laboratory risk factors/biomarkers of BPD and CRM were explored.

RESULTS

Of 86 subjects, 94% survived. Outcomes were available for 89% at 36-week PMA (BPD present in 42% of infants) and 72% at 6-12-month CGA (CRM present in 47% of infants). For the 54 infants with known outcomes for both BPD and CRM, diagnoses were discordant in 41%. BPD was associated with lower birthweight and birthweight Z-score for GA, lower Apgar scores, more surfactant doses, higher SNAPPE-II scores, highest Day 1 inspired oxygen concentration, Day 7 oxygen use, prolonged ventilatory support, bacteremia, necrotizing enterocolitis, and treated patent ductus arteriosus. CRM was associated with lower Apgar scores, Day 7 oxygen use and higher urine vascular endothelial growth factor. Patterns of plasma and urine lipid oxidation products differed in the two outcomes.

CONCLUSION

In this hypothesis generating and exploratory study, BPD and CRM were associated with different risk factors/biomarker patterns. Concordance between these two outcomes was weak. Strategies for reducing CRM should be studied in cohorts identified by appropriate early risk factors/biomarkers.

Metabolomics-Based Clinical Efficacy of Compound Shenlu Granule, a Chinese Patent Medicine, in the Supportive Management of Aplastic Anemia Patients: A Randomized Controlled Pilot Trial

Objective

To explore the clinical efficacy and mechanism of compound Shenlu granule (SLG) treatment in patients with aplastic anemia (AA).

Methods

A total of 89 AA patients were randomly divided into an SLG supportive group (group A, n = 44) and a control group (group B, n = 45) while continuing Western medical management. After 6 months, hemograms, traditional Chinese medicine (TCM) syndrome scores, and overall clinical efficacy rate were assessed. Serum metabolomics characteristics were observed using ultraperformance liquid chromatography-mass spectrometry after SLG intervention.

Results

The levels of red blood cell (RBC), hemoglobin (Hb), and platelet (PLT) were increased in both groups after treatment for 6 months (P < 0.05), and in group A, the elevation of PLT became much more significant (P < 0.01). The TCM syndrome score was lower in group A than in group B after treatment (P < 0.05). Metabolomics data showed a significant difference in the patients using SLG after 6 months, and 14 biomarkers were identified.

Conclusion

SLG supportive treatment showed positive results in patients with AA, and metabolomics data indicated that SLG influenced aminoacyl-tRNA biosynthesis and glycerophospholipid metabolism to gradually return to normal.

Development of Polypyrrole Modified Screen-Printed Carbon Electrode Based Sensors for Determination of L-Tyrosine in Pharmaceutical Products

Good health, of vital importance in order to carry out our daily routine, consists of both physical and mental health. Tyrosine (Tyr) deficiency as well as its excess are issues that can affect mental health and can generate disorders such as depression, anxiety, or stress. Tyr is the amino acid (AA) responsible for maintaining good mental health, and for this reason, the present research presents the development of new electrochemical sensors modified with polypyrrole (PPy) doped with different doping agents such as potassium hexacyanoferrate (II) (FeCN), sodium nitroprusside (NP), and sodium dodecyl sulfate (SDS) for a selective and sensitive detection of Tyr. The development of the sensors was carried out by chronoamperometry (CA) and the electrochemical characterization was carried out by cyclic voltammetry (CV). The detection limits (LOD) obtained with each modified sensor were 8.2 × 10-8 M in the case of PPy /FeCN-SPCE, 4.3 × 10-7 M in the case of PPy/NP-SPCE, and of 3.51 × 10-7 M in the case of PPy/SDS-SPCE, thus demonstrating a good sensitivity of these sensors detecting L-Tyr. The validation of sensors was carried out through quantification of L-Tyr from three pharmaceutical products by the standard addition method with recoveries in the range 99.92-103.97%. Thus, the sensors present adequate selectivity and can be used in the pharmaceutical and medical fields.

Synthesis of green fluorescent carbon quantum dots from the latex of Ficus benghalensis for the detection of tyrosine and fabrication of Schottky barrier diode

Green fluorescent CQDs have been synthesized from the latex of ficus benghalensis and polyethyleneimine and utilized for the detection of tyrosine. Further, fabricated a Schottky barrier diode.

Ratiometric fluorescence nanoprobe for monitoring of intracellular temperature and tyrosine based on a dual emissive carbon dots/gold nanohybrid

A novel dual-emission nitrogen doped carbon dots/gold nanohybrid (NCDs-Au) was designed for specific and sensitive ratiometric detection of intracellular temperature and tyrosine. In this probe, a reductive NCDs was successfully prepared with the use of natural biomass Dendrobium officinale as precursor. The new prepared NCDs acted as both reducers and stabilizers to synthesize a novel NCDs-Au nanohybrid by a facile one-step procedure along with a quantum yield of 14.3%. The prepared nanoprobe showed characteristic fluorescence emissions of NCDs and Au NCs with single-wavelength excitation. Notably, the nanoprobe shows an interesting wavelength-dependent dual response to temperature (448 nm) and tyrosine (660 nm), enabling the two targets to be detected proportionally. As an effective temperature sensor, the nanoprobe exhibited good temperature-dependent fluorescence with a sensational linear response from 5 to 75 °C. In addition, the sensor has a linear response toward tyrosine in the range of 0.5-175 μM with a detection limit of 0.19 μM. Moreover, the fluorescent nanoprobe was successfully applied to ratiometricly monitor the variation of temperature or tyrosine level in cells because of the low cytotoxicity, chemical stability and excellent fluorescence properties. These results suggested that the nanoprobe here has provided the possibility for rapidly biosensing with the acceptable selectivity and sensitivity.

Do food and stress biomarkers work for wastewater-based epidemiology? A critical evaluation

Dietary characteristics and oxidative stress are closely linked to the wellbeing of individuals. In recent years, various urinary biomarkers of food and oxidative stress have been proposed for use in wastewater-based epidemiology (WBE), in efforts to objectively monitor the food consumed and the oxidative stress experienced by individuals in a wastewater catchment. However, it is not clear whether such biomarkers are suitable for wastewater-based epidemiology. This study presents a suite of 30 urinary food and oxidative stress biomarkers and evaluates their applicability for WBE studies. This includes 22 biomarkers which were not previously considered for WBE studies. Daily per capita loads of biomarkers were measured from 57 wastewater influent samples from nine Australian catchments. Stability of biomarkers were assessed using laboratory scale sewer reactors. Biomarkers of consumption of vitamin B2, vitamin B3 and fibre, as well as a component of citrus had per capita loads in line with reported literature values despite susceptibility of degradation in sewer reactors. Consumption biomarkers of red meat, fish, fruit, other vitamins and biomarkers of stress had per capita values inconsistent with literature findings, and/or degraded rapidly in sewer reactors, indicating that they are unsuitable for use as WBE biomarkers in the traditional quantitative sense. This study serves to communicate the suitability of food and oxidative stress biomarkers for future WBE research.

Genotypic variation for cadmium tolerance in common bean (Phaseolus vulgaris L.)

Given the limitation of crop production in Cd-polluted areas, the identification and selection of plant genotypes tolerant to Cd stress are of great significance. In the present work, we show the existence of genotypic variation for Cd tolerance in common bean. The laboratory screening of 25 bean genotypes indicated a significant positive correlation of the mean productivity (MP) and the geometric mean productivity (GMP) with plant fresh weight both in control and Cd-treated plants. A principal component analysis further confirmed this variation and, together with other analyses, led to the selection of genotypes G-11867, Taylor, Emerson, and D-81083 as tolerant genotypes. A total of six bean genotypes with different degrees of Cd tolerance were selected, and their long-term physiological responses to Cd (0, 45, and 90 mg/kg soil) were evaluated. Increasing Cd concentrations led to higher Cd accumulation both in roots and shoots, and to significant rises in the levels of the oxidative stress biomarkers malondialdehyde (MDA), dityrosine (D-T), and 8-hydroxy-2'-deoxyguanosine (8-OH-2'-dG). Remarkable reductions in plant hormone levels and chlorophyll contents, as well as in dry and fresh weight, were observed in Cd-treated plants. Among the examined genotypes, Emerson, Taylor, and G-11867 were found to be more tolerant to Cd owing to lower Cd accumulation and lower oxidative stress levels, as well as higher chlorophyll and hormone contents. Our results contribute to the understanding of the physiological and biochemical basis of Cd tolerance in bean plants and may therefore, be useful for breeding programs directed towards obtaining bean varieties showing low Cd accumulation.

Plasma metabolites mediate the effect of HbA1c on incident cardiovascular disease

Background

We aim to discover whether HbA1c affects incident cardiovascular disease (CVD) through regulating endogenous metabolites.

Methods and Results

Totally, 2019 plasma samples were analyzed by liquid chromatography‐quadrupole time‐of‐flight mass spectrometry. Logistic regression and linear regression were used to screen metabolites which were associated with both CVD and HbA1c. The VanderWeele's mediation approach was performed to assess the direct effect and indirect effect (IE) in the counterfactual model. Forty‐eight metabolites showed an association with both HbA1c and CVD risk. Forty‐four of the 48 metabolites worked as mediators mediated in HbA1c's effect on CVD (odds ratio [OR]_IE from 0.997 to 6.098, false discovery rate q < 0.05, mediated proportion from 0.4% to 85.4%). Pathway enrichment analysis indicated that different metabolic pathway showed significant IE (butanoate metabolism OR_IE = 1.058, mediated proportion = 16.0%; alanine, aspartate and glutamate metabolism OR_IE = 1.082, mediated proportion = 21.8%; TCA (citric acid) cycle metabolism OR_IE = 1.048, mediated proportion = 13.8%; phenylalanine metabolism OR_IE = 1.067, mediated proportion = 18.4%; glycerophospholipid metabolism OR_IE = 3.007, mediated proportion = 82.2%; all the P < .01).

Conclusions

Our findings suggest that metabolites mediate the effect of HbA1c on incident CVD and provide a new study sight into pathogenesis of CVD.

Design of novel Surfactant Modified Carbon Nanotube Paste Electrochemical Sensor for the Sensitive Investigation of Tyrosine as a Pharmaceutical Drug

Purpose: The novel sodium dodecyl sulfate modified carbon nanotube paste electrode (SDS/ CNTPE) was used as a sensitive sensor for the electrochemical investigation of L-tyrosine (TY). Methods: The electrochemical analysis of TY was displayed through cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The surface morphology of SDS/CNTPE and bare carbon nanotube past electrode (BCNTPE) was reviewed trough field emission scanning electron microscopy (FESEM). Results: The functioning SDS/CNTPE shows a voltammetric response with superior sensitivity towards TY. This study was conducted using a phosphate buffer solution having neutral pH (pH=7.0). The correlation between the oxidation peak current of TY and concentration of TY was achieved linearly in CV method, in the range 2.0×10^-6 to 5 ×10^-5 M with the detection limit 729 nM and limit of quantification 2.43 μM. The investigated voltammetric study at SDS/CNTPE was also adopted in the examination of TY concentration in a pharmaceutical medicine as a real sample with the recovery of 97% to 98% . Conclusion: The modified electrode demonstrates optimum sensitivity, constancy, reproducibility, and repeatability during the electrocatalytic activity of TY.

Copper toxicity and date palm (Phoenix dactylifera) seedling tolerance: Monitoring of related biomarkers

Date palm (Phoenix dactylifera) seeds were exposed to different copper (Cu) solutions to examine plant stress responses. Low Cu concentrations (0.02 and 0.2 mM) caused an increase of seed germination, whereas higher Cu amounts (2 mM) significantly inhibited seed germination, delayed hypocotyl elongation, increased seedling mortality, and reduced the germination index by more than 90%. Metal-related toxicity symptoms appeared after 15 d of 2 mM of Cu exposure. Biochemical activities such as amylase activity and redox balance elements were examined to study the relationship between external Cu amount and internal plant response. The present study showed that amylolytic activity was dose- and time-dependent. Likewise, H₂ O₂ production increased after exposure to Cu, which was correlated with thiobarbituric acid reactive substance (TBARS) accumulation. Furthermore at low Cu concentrations, superoxide dismutase (SOD) and catalase (CAT) activities increased, suggesting that date palm seed stimulated its metal homeostasis networks. However, the highest cupric ion amounts increased cell oxidant accumulation and reduced enzyme production. Gene expression level measures of P. dactylifera phytochelatin synthase (Pdpcs) and P. dactylifera metallothionein (Pdmt) encoding genes have been carried out to investigate the implication of PdPCS and PdMT proteins in Cu homeostasis and/or its sequestration. Phoenix dactylifera metallothionein induction reached a peak after 30 d of exposure to 0.2 mM of Cu. However, it was down-regulated in plants exposed to higher Cu concentrations. In the same conditions, Pdpcs was overexpressed during 1 mo of exposure before it decreased thereafter. These observations provide a new insight into date palm cell response to Cu, a metal that can be toxic but that is also an essential element. Environ Toxicol Chem 2018;37:797-806. © 2017 SETAC.

Integration of Miniaturized Solid Phase Extraction and LC-MS/MS Detection of 3-Nitrotyrosine in Human Urine for Clinical Applications

Free 3-nitrotyrosine (3-NT) has been extensively used as a possible biomarker for oxidative stress. Increased levels of 3-NT have been reported in a wide variety of pathological conditions. However, existing methods lack the sufficient sensitivity and/or specificity necessary to measure the low endogenous level of 3-NT reliably and are too cumbersome for clinical applications. Hence, analytical improvement is urgently needed to accurately quantify the levels of 3-NT and verify the role of 3-NT in pathological conditions. This protocol presents the development of a novel liquid chromatography tandem mass spectrometry (LC-MS/MS) detection combined with a miniaturized solid phase extraction (SPE) for the rapid and accurate measurement of 3-NT in human urine as a non-invasive biomarker for oxidative stress. SPE using a 96-well plate markedly simplified the process by combining sample cleanup and analyte enrichment without tedious derivatization and evaporation steps, reducing solvent consumption, waste disposal, risk of contamination and overall processing time. The employment of 25 mM ammonium acetate (NH4OAc) at pH 9 as the SPE elution solution substantially enhanced the selectivity. Mass spectrometry signal response was improved through adjustment of the multiple reaction monitoring (MRM) transitions. Use of 0.01% HCOOH as additive on a pentafluorophenyl (PFP) column (150 mm x 2.1 mm, 3 µm) improved signal response another 2.5-fold and shortened the overall run time to 7 min. A lower limit of quantitation (LLOQ) of 10 pg/mL (0.044 nM) was achieved, representing a significant sensitivity improvement over the reported assays. This simplified, rapid, selective and sensitive method allows two plates of urine samples (n = 192) to be processed in a 24 h time-period. Considering the markedly improved analytical performance, and non-invasive and inexpensive urine sampling, the proposed assay is beneficial for pre-clinical and clinical studies.

Linking sources to early effects by profiling urine metabolome of residents living near oil refineries and coal-fired power plants

BACKGROUND

This study aims at identifying metabolic changes linking external exposure to industrial air toxics with oxidative stress biomarkers.

METHODS

We classified 252 study subjects as 111 high vs. 141 low exposure subjects by the distance from their homes to the two main emission sources, oil refineries and coal-fired power plants. We estimated individual's external exposure to heavy metals and polycyclic aromatic hydrocarbons (PAHs) by dispersion and kriging models, respectively. We measured urinary levels of heavy metals and 1-hydroxypyrene (1-OHP) as biomarkers of internal exposure, and 8-OHdG, HNE-MA, 8-isoPGF_2α, and 8-NO₂Gua as biomarkers of early health effects. We used two-dimensional gas chromatography time-of-flight mass spectrometry to identify urine metabolomics. We applied "meet-in-the-middle" approach to identify potential metabolites as putative intermediate biomarkers linking multiple air toxics exposures to oxidative stress with plausible exposures-related pathways.

RESULTS

High exposure subjects showed elevated ambient concentrations of vanadium and PAHs, increased urine concentrations of 1-OHP, vanadium, nickel, copper, arsenic, strontium, cadmium, mercury, and thallium, and higher urine concentrations of all four urine oxidative stress biomarkers compared to low exposure subjects. We identified a profile of putative intermediate biomarkers that were associated with both exposures and oxidative stress biomarkers in participants. Urine metabolomics identified age-dependent biological pathways, including tryptophan metabolism and phenylalanine metabolism in children subjects (aged 9-11), and glycine, serine, and threonine metabolism in elderly subjects (aged>55), that could associate multiple exposures with oxidative stress.

CONCLUSION

By profiling urine biomarkers and metabolomics in children and elderly residents living near a petrochemical complex, we can link their internal exposure to oxidative stress biomarkers through biological pathways associated with common complex chronic diseases and allergic respiratory diseases. The internal exposure may possibly be traced to multiple air toxics emitted from specific sources of oil refineries and coal-fired power plants.

Tyrosine-Nitrated Proteins: Proteomic and Bioanalytical Aspects

SIGNIFICANCE

"Nitroproteomic" is under active development, as 3-nitrotyrosine in proteins constitutes a footprint left by the reactions of nitric oxide-derived oxidants that are usually associated to oxidative stress conditions. Moreover, protein tyrosine nitration can cause structural and functional changes, which may be of pathophysiological relevance for human disease conditions. Biological protein tyrosine nitration is a free radical process involving the intermediacy of tyrosyl radicals; in spite of being a nonenzymatic process, nitration is selectively directed toward a limited subset of tyrosine residues. Precise identification and quantitation of 3-nitrotyrosine in proteins has represented a "tour de force" for researchers. Recent Advances: A small number of proteins are preferential targets of nitration (usually less than 100 proteins per proteome), contrasting with the large number of proteins modified by other post-translational modifications such as phosphorylation, acetylation, and, notably, S-nitrosation. Proteomic approaches have revealed key features of tyrosine nitration both in vivo and in vitro, including selectivity, site specificity, and effects in protein structure and function.

CRITICAL ISSUES

Identification of 3-nitrotyrosine-containing proteins and mapping nitrated residues is challenging, due to low abundance of this oxidative modification in biological samples and its unfriendly behavior in mass spectrometry (MS)-based technologies, that is, MALDI, electrospray ionization, and collision-induced dissociation.

FUTURE DIRECTIONS

The use of (i) classical two-dimensional electrophoresis with immunochemical detection of nitrated proteins followed by protein ID by regular MS/MS in combination with (ii) immuno-enrichment of tyrosine-nitrated peptides and (iii) identification of nitrated peptides by a MIDAS™ experiment is arising as a potent methodology to unambiguously map and quantitate tyrosine-nitrated proteins in vivo. Antioxid. Redox Signal. 26, 313-328.

Protein-bound tyrosine oxidation, nitration and chlorination by-products assessed by ultraperformance liquid chromatography coupled to tandem mass spectrometry

BACKGROUND

Free radicals cause alterations in cellular protein structure and function. Oxidized, nitrated, and chlorinated modifications of aromatic amino acids including phenylalanine and tyrosine are reliable biomarkers of oxidative stress and inflammation in clinical conditions.

OBJECTIVE

To develop, validate and apply a rapid method for the quantification of known hallmarks of tyrosine oxidation, nitration and chlorination in plasma and tissue proteins providing a snapshot of the oxidative stress and inflammatory status of the organism and of target organs respectively.

MATERIAL AND METHODS

The extraction and clean up procedure entailed protein precipitation, followed by protein re-suspension and enzymatic digestion with pronase. An Ultra Performance Liquid Chromatography-tandem Mass Spectrometry (UPLC-MS/MS) method was developed to quantify protein released ortho-tyrosine (o-Tyr), meta-tyrosine (m-Tyr), 3-nitrotyrosine (3NO2-Tyr) and 3-chlorotyrosine (3Cl-Tyr) as well as native phenylalanine (Phe) and tyrosine (p-Tyr) in plasma and tissue from a validated hypoxic newborn piglet experimental model.

RESULTS

In plasma there was a significant increase in the 3NO2-Tyr/p-Tyr ratio. On the other hand m-Tyr/Phe and 3Cl-Tyr/p-Tyr ratios were significantly increased in liver of hypoxic compared with normoxic animals. Although no significant differences were found in brain tissue, a clear tendency to increased ratios was observed under hypoxic conditions.

CONCLUSIONS

UPLC-MS/MS has proven suitable for the analysis of plasma and tissue samples from newborn piglets. The analysis of biomarkers of protein oxidation, nitration and chlorination will be applied in future studies aiming to provide a deeper insight into the mechanisms of oxidation-derived protein modification caused during neonatal asphyxia and resuscitation.

Novel method for tyrosine assessment in vitro using luminescence quenching of the nano optical sensor Eu–ciprofloxacin doped in a sol–gel matrix

A low cost and very sensitive method for the assessment of tyrosine in blood serum, urine and hair samples was developed. The method was based upon the luminescence intensity of a Eu–ciprofloxacin complex nano optical sensor.

New findings on the in vivo antioxidant activity of Curcuma longa extract by an integrated (1)H NMR and HPLC-MS metabolomic approach

Curcuminoids possess powerful antioxidant activity as demonstrated in many chemical in vitro tests and in several in vivo trials. Nevertheless, the mechanism of this activity is not completely elucidated and studies on the in vivo antioxidant effects are still needed. Metabolomics may be used as an attractive approach for such studies and in this paper, we describe the effects of oral administration of a Curcuma longa L. extract (150 mg/kg of total curcuminoids) to 12 healthy rats with particular attention to urinary markers of oxidative stress. The experiment was carried out over 33 days and changes in the 24-h urine samples metabolome were evaluated by (1)H NMR and HPLC-MS. Both techniques produced similar representations for the collected samples confirming our previous study. Modifications of the urinary metabolome lead to the observation of different variables proving the complementarity of (1)H NMR and HPLC-MS for metabolomic purposes. The urinary levels of allantoin, m-tyrosine, 8-hydroxy-2'-deoxyguanosine, and nitrotyrosine were decreased in the treated group thus supporting an in vivo antioxidant effect of the oral administration of Curcuma extract to healthy rats. On the other hand, urinary TMAO levels were higher in the treated compared to the control group suggesting a role of curcumin supplementation on microbiota or on TMAO urinary excretion. Furthermore, the urinary levels of the sulphur containing compounds taurine and cystine were also changed suggesting a role for such constituents in the biochemical pathways involved in Curcuma extract bioactivity and indicating the need for further investigation on the complex role of antioxidant curcumin effects.

Lipids and proteins--major targets of oxidative modifications in abiotic stressed plants

Stress factors provoke enhanced production of reactive oxygen species (ROS) in plants. ROS that escape antioxidant-mediated scavenging/detoxification react with biomolecules such as cellular lipids and proteins and cause irreversible damage to the structure of these molecules, initiate their oxidation, and subsequently inactivate key cellular functions. The lipid- and protein-oxidation products are considered as the significant oxidative stress biomarkers in stressed plants. Also, there exists an abundance of information on the abiotic stress-mediated elevations in the generation of ROS, and the modulation of lipid and protein oxidation in abiotic stressed plants. However, the available literature reflects a wide information gap on the mechanisms underlying lipid- and protein-oxidation processes, major techniques for the determination of lipid- and protein-oxidation products, and on critical cross-talks among these aspects. Based on recent reports, this article (a) introduces ROS and highlights their relationship with abiotic stress-caused consequences in crop plants, (b) examines critically the various physiological/biochemical aspects of oxidative damage to lipids (membrane lipids) and proteins in stressed crop plants, (c) summarizes the principles of current technologies used to evaluate the extent of lipid and protein oxidation, (d) synthesizes major outcomes of studies on lipid and protein oxidation in plants under abiotic stress, and finally, (e) considers a brief cross-talk on the ROS-accrued lipid and protein oxidation, pointing to the aspects unexplored so far.

A multi-walled carbon nanotube/poly-2,6-dichlorophenolindophenol film modified carbon paste electrode for the amperometric determination of l-tyrosine

An electrochemically induced oxa-Michael addition reaction for electro-polymerization of 2,6-dichlorophenolindophenol at CPE/MWCNT for the electro-catalytic oxidation of tyrosine.

Multimarker screening of oxidative stress in aging

Aging is a complex process of organism decline in physiological functions. There is no clear theory explaining this phenomenon, but the most accepted one is the oxidative stress theory of aging. Biomarkers of oxidative stress, substances, which are formed during oxidative damage of phospholipids, proteins, and nucleic acids, are present in body fluids of diseased people as well as the healthy ones (in a physiological concentration). 8-iso prostaglandin F_2α is the most prominent biomarker of phospholipid oxidative damage, o-tyrosine, 3-chlorotyrosine, and 3-nitrotyrosine are biomarkers of protein oxidative damage, and 8-hydroxy-2^′-deoxyguanosine and 8-hydroxyguanosine are biomarkers of oxidative damage of nucleic acids. It is thought that the concentration of biomarkers increases as the age of people increases. However, the concentration of biomarkers in body fluids is very low and, therefore, it is necessary to use a sensitive analytical method. A combination of HPLC and MS was chosen to determine biomarker concentration in three groups of healthy people of a different age (twenty, forty, and sixty years) in order to find a difference among the groups.

Mass spectrometry and 3-nitrotyrosine: strategies, controversies, and our current perspective

Reactive-nitrogen species (RNS) such as peroxynitrite (ONOO(-)), that is, the reaction product of nitric oxide ((•)NO) and superoxide (O2(-•)), nitryl chloride (NO2Cl) and (•)NO2 react with the activated aromatic ring of tyrosine to form 3-nitrotyrosine. This modification, which has been known for more than a century, occurs to both the free form of the amino acid (i.e., soluble/free tyrosine) and to tyrosine residues covalently bound within the backbone of peptides and proteins. Nitration of tyrosine is thought to be of biological significance and has been linked to health and disease, but determining its role has proved challenging. Several key questions have been the focus of much of the research activity: (a) to what extent is free/soluble tyrosine nitrated in biological tissues and fluids, and (b) are there specific site(s) of nitration within peptides/proteins and to what extent (i.e., stoichiometry) does this modification occur? These issues have been addressed in a wide range of sample types (e.g., blood, urine, CSF, exhaled breath condensate and various tissues) and a diverse array of physiological/pathophysiological scenarios. The accurate determination of nitrated tyrosine is, however, a stumbling block. Despite extensive study, the extent to which nitration occurs in vivo, the specificity of the nitration reaction, and its importance in health and disease, remain unclear. In this review, we highlight the analytical challenges and discuss the approaches adopted to address them. Mass spectrometry, in combination with either gas chromatography (GC-MS, GC-MS/MS) or liquid chromatography (LC-MS/MS), has played the central role in the analysis of 3-nitrotyrosine and tyrosine-nitrated biological macromolecules. We discuss its unique attributes and highlight the role of stable-isotope labeled 3-nitrotyrosine analogs in both accurate quantification, and in helping to define the biological relevance of tyrosine nitration. We show that the application of sophisticated mass spectrometric techniques is advantageous if not essential, but that this alone is by no means a guarantee of accurate findings. We discuss the important analytical challenges in quantifying 3-nitrotyrosine, possible workarounds, and we attempt to make sense of the disparate findings that have been reported so far.

Resuscitation of preterm infants with different inspired oxygen fractions

OBJECTIVE

To test the hypothesis that an initial fraction of inspired oxygen (FiO2) of 30% during resuscitation of preterm infants results in less oxidative stress and is associated with improved clinical outcomes compared with an FiO2 of 65%.

STUDY DESIGN

Preterm infants of gestational age <32 weeks (n = 193) were randomized to start resuscitation with either 30% oxygen (low-oxygen group) or 65% oxygen (high-oxygen group), after which the FiO2 was adjusted based on oxygen saturation values. The primary outcome was bronchopulmonary dysplasia (BPD) assessed at 36 weeks postmenstrual age. Secondary outcomes included major neonatal illnesses and markers of oxidative stress.

RESULTS

The median gestational age of included infants was 28(6)/7 weeks (IQR, 26(5)/7-30(3)/7 weeks). The incidence of BPD was not significantly different between the low-oxygen and high-oxygen groups (24% vs. 17%; P = .15). The FiO2 in both groups was adjusted to a mean of 40% by 7 minutes in the low-oxygen group and by 11 minutes in the high-oxygen group. No differences in markers of oxidative stress were noted between groups.

CONCLUSION

Initial supplementation of preterm infants with 30% oxygen during the fetal-to-neonatal transition is as safe as 65% oxygen, with no differences in oxidative stress markers or BPD.

Assessment of oxidative damage to proteins and DNA in urine of newborn infants by a validated UPLC-MS/MS approach

The assessment of oxidative stress is highly relevant in clinical Perinatology as it is associated to adverse outcomes in newborn infants. This study summarizes results from the validation of an Ultra Performance Liquid Chromatography–tandem Mass Spectrometry (UPLC-MS/MS) method for the simultaneous quantification of the urinary concentrations of a set of endogenous biomarkers, capable to provide a valid snapshot of the oxidative stress status applicable in human clinical trials, especially in the field of Perinatology. The set of analytes included are phenylalanine (Phe), para-tyrosine (p-Tyr), ortho-tyrosine (o-Tyr), meta-tyrosine (m-Tyr), 3-NO₂-tyrosine (3NO₂-Tyr), 3-Cl-tyrosine (3Cl-Tyr), 2′-deoxyguanosine (2dG) and 8-hydroxy-2′-deoxyguanosine (8OHdG). Following the FDA-based guidelines, appropriate levels of accuracy and precision, as well as adequate levels of sensitivity with limits of detection (LODs) in the low nanomolar (nmol/L) range were confirmed after method validation. The validity of the proposed UPLC-MS/MS method was assessed by analysing urine samples from a clinical trial in extremely low birth weight (ELBW) infants randomized to be resuscitated with two different initial inspiratory fractions of oxygen.

A magnetic nanoparticles-zinc oxide/zinc hexacyanoferrate hybrid film for amperometric determination of tyrosine

A method is described for the construction of a highly sensitive amperometric sensor for the detection of tyrosine, employing a magnetic nanoparticles-zinc oxide/zinc hexacyanoferrate (Fe3O4NP-ZnO/ZnHCF) hybrid film electrodeposited on the surface of a Pt electrode as working electrode. The sensor is based on electrocatalytic mechanism initiated by electrochemical oxidation of the reduced form of the hybrid film at +0.2 V vs. Ag/AgCl followed by completion of chemical oxidation of tyrosine. The sensor showed optimum response within 2 s at pH 2. The working/linear range of the sensor was 0.02-2.76 mM with a detection limit of 4 μM. The sensor measured tyrosine level in serum, a potential biomarker of phenylketonuria. The working electrode lost only 5 % of its initial activity, when stored at 4 °C, after its regular use over a period of 100 days.

Electrochemical determination of tyrosine in the presence of uric acid at a carbon paste electrode modified with multi-walled carbon nanotubes enhanced by sodium dodecyl sulfate

Tyrosine (Tyr) was quantitated with high sensitivity and selectivity in the presence of uric acid (UA) using a carbon paste electrode modified with multi-walled carbon nanotubes. Tyr and UA were catalytically oxidized with diffusion-controlled characteristics. They were determined simultaneously by differential pulse voltammetry with a potential difference of 350 mV. The electrocatalytic currents increase linearly with Tyr and UA concentrations 4×10−7−1×10−4 M and 3×10−7−2×10−4 M. Their detection limits were 1×10−7 and 5.1×10−8 M respectively. In the presence of sodium dodecyl sulfate the Tyr detection limit improved from 1×10−7 to 6.9×10−8 M. The electrode was successfully used to quantitate Tyr and UA in serum.

Cardiovascular redox and ox stress proteomics

SIGNIFICANCE

Oxidative post-translational modifications (OPTMs) have been demonstrated as contributing to cardiovascular physiology and pathophysiology. These modifications have been identified using antibodies as well as advanced proteomic methods, and the functional importance of each is beginning to be understood using transgenic and gene deletion animal models. Given that OPTMs are involved in cardiovascular pathology, the use of these modifications as biomarkers and predictors of disease has significant therapeutic potential. Adequate understanding of the chemistry of the OPTMs is necessary to determine what may occur in vivo and which modifications would best serve as biomarkers.

RECENT ADVANCES

By using mass spectrometry, advanced labeling techniques, and antibody identification, OPTMs have become accessible to a larger proportion of the scientific community. Advancements in instrumentation, database search algorithms, and processing speed have allowed MS to fully expand on the proteome of OPTMs. In addition, the role of enzymatically reversible OPTMs has been further clarified in preclinical models.

CRITICAL ISSUES

The identification of OPTMs suffers from limitations in analytic detection based on the methodology, instrumentation, sample complexity, and bioinformatics. Currently, each type of OPTM requires a specific strategy for identification, and generalized approaches result in an incomplete assessment.

FUTURE DIRECTIONS

Novel types of highly sensitive MS instrumentation that allow for improved separation and detection of modified proteins and peptides have been crucial in the discovery of OPTMs and biomarkers. To further advance the identification of relevant OPTMs in advanced search algorithms, standardized methods for sample processing and depository of MS data will be required.

Urinary lipid and protein oxidation products upon halothane, isoflurane, or sevoflurane anesthesia in humans: potential biomarkers for a subclinical nephrotoxicity

OBJECTIVE

To investigate whether lipid and protein oxidation products are elevated and correlated with routine clinical markers of hepatic and renal function in patients anesthetized with halothane, isoflurane, or sevoflurane.

METHODS

Urine and blood samples were collected from patient groups. Excretion of aldehydes, acetone, and o,o'-dityrosine was measured before and after anesthesia. Blood samples were analysed for clinical markers.

RESULTS

Urinary concentrations of aldehydes, acetone, o,o'-dityrosine and glucose were significantly increased after anesthesia in halothane and sevoflurane groups earlier than clinical markers. Significant correlations were found in sevoflurane group.

CONCLUSION

Lipid and protein oxidation contributes to subclinical sevoflurane nephrotoxicity. Oxidation products may serve as early biomarkers.