Proposal and confirmation of N-(2-carboxyethyl)proline as a human endogenous metabolite.

RATIONALE: Malondialdehyde, one of the peroxidation products of polyunsaturated fatty acids, has been widely reported as an oxidative stress biomarker in many diseases. However, malondialdehyde is inherently unstable in biological matrices, which renders its measurement unreliable with all the reported analytical methods. To find an alternative oxidative stress biomarker, we envisioned that N-(2-carboxyethyl)proline, a modified conjugate of malondialdehyde and proline, could be a stable candidate for this purpose. METHODS: The proposed compound was chemically synthesized, and liquid chromatography-mass spectrometry methods were developed and used to search for the compound in human biological samples. RESULTS: An endogenous metabolite in human feces and urine samples was found to match the synthetic N-(2-carboxyethyl)proline by chromatographic retention and the fragmentation pattern of its molecular ion. CONCLUSION: The results confirmed that N-(2-carboxyethyl)proline was a new metabolite in human feces and urine samples. In addition, our results demonstrated a case of successful identification of true unknown metabolite by knowledge-based hypothesis of possible metabolites followed by experimental confirmation with a synthetic standard.

Racial and ethnic disparities in biomarkers of exposure and potential harm among U.S. adult exclusive e-cigarette users: 2013-2019.

OBJECTIVE: Provide evidence on racial and ethnic differences in biomarkers of exposure from rising e-cigarette use among U.S. adults. METHODS: Data were drawn from Waves 1-5 of the Population Assessment of Tobacco and Health study (September 2013-November 2019). Differences in biomarkers of exposure and potential harm (BOE/BoPH) across non-Hispanic (NH)-Whites, NH Blacks, Hispanic/Latinos, and NH others were examined using generalized estimation equations. RESULTS: Among exclusive e-cigarette users, mean concentrations of BOEs/BoPHs were not significantly different across NH Blacks (n=97), NH others (n=122), and NH Whites (n=1062), after adjustment by wave, age, sex, education, exposure to the secondhand smoke, and the number of recent puffs. Compared to NH Whites, Hispanics (n=151) had lower concentrations of nicotine equivalents (0.5[0.2-1.7] vs. 15.5 [12.5-19.1] nmol/mg creatinine, p<.0001), cotinine (33.4[9.7-114.7] vs. 1008.3 [808.3-1257.9] ng/mg creatinine, p<.0001), and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) (2.6[1.5-4.4] vs. 5.7 [4.9-6.6] pg/mg creatinine, p=.004), but similar concentrations of BOEs for heavy metals, polycyclic aromatic hydrocarbons, volatile organic compounds, and oxidative stress. Differences between Hispanics and NH Whites are expected, given different e-cigarette use profiles. Specifically, Hispanics were less likely to be daily vapers (49.4[35.1-63.8]% vs 81.3[77.7-84.5]%, p<.0001) and nicotine e-cigarette users (72.7 [64.0-79.9]% vs. 89.2 [86.4-91.5]%, p=.0002] and reported a lower number of recent puffs (mean[standard error]=16.7[3.6] vs. 28.6[2.0], p=.02] than their NH-White counterparts. Hispanic vapers were also less likely than NH Whites to have previously smoked cigarettes (49.7 [37.2-62.3]% vs. 88.5 [84.7-91.5]%, p<.0001]). CONCLUSIONS: Hispanic vapers exhibited lower exposure to nicotine metabolites and carcinogens than their non-Hispanic White counterparts. The harm reduction potential from e-cigarette use are likely to be realized across diverse racial and ethnic groups.

The Detection of Anthrax Biomarker DPA by Ratiometric Fluorescence Probe of Carbon Quantum Dots and Europium Hybrid Material Based on Poly(ionic)- Liquid.

Bacillus anthracis has gained international attention as a deadly bacterium and a potentially deadly biological warfare agent. Dipicolinic acid (DPA) is the main component of the protective layer of anthracis spores, and is also an anthrax biomarker. Therefore, it is of great significance to explore an efficient and sensitive DPA detection method. Herein, a novel ratio hybrid probe (CQDs-PIL-Eu3+) was prepared by a simple one-step hydrothermal method using carbon quantum dots (CQDs) as an internal reference fluorescence and a covalent bond between CQDs and Eu3+ by using a polyionic liquid (PIL) as a bridge molecule. The ratiometric fluorescence probe was found to have the characteristics of sensitive fluorescence visual sensing in detecting DPA. The structure and the sensing properties of CQDs-PIL-Eu3+ were investigated in detail. In particular, the fluorescence intensity ratio of Eu3+ to CQDs (I616/I440) was linear with the concentration of DPA in the range of 0-50 µM, so the detection limit of the probe was as low as 32 nm, which was far lower than the DPA dose released by the number of anthrax spores in human body (60 µM) and, thus, can achieve sensitive detection. Therefore, the ratiometric fluorescence probe in this work has the characteristics of strong anti-interference, visual sensing, and high sensitivity, which provides a very promising scheme for the realization of anthrax biomarker DPA detection.

A self-designed device integrated with a Fermat spiral microfluidic chip for ratiometric and automated point-of-care testing of anthrax biomarker in real samples.

A desirable lanthanide-based ratiometric fluorescent probe was designed and integrated into a self-designed Fermat spiral microfluidic chip (FS-MC) for the automated determination of a unique bacterial endospore biomarker, dipicolinic acid (DPA), with high selectivity and sensitivity. Here, a blue emission wavelength at 425 nm was generated in the Fermat spiral structure by mixing the europium (Eu3+) and luminol to form the Eu3+/Luminol sensing probe. DPA in the reservoir can be used to specifically bind to Eu3+ under the negative pressure and transfer energy from DPA to Eu3+ sequentially via an antenna effect, thus resulting in a significant increase in the red fluorescence emission peak at 615 nm. According to the fluorescence intensity ratio (F615/F425), a good linearity can be obtained with increasing the concentration of DPA from 0 to 200 µM with a limit of detection as low as 10.11 nM. Interestingly, the designed FS-MC can achieve rapid detection of DPA in only 1 min, reducing detection time and improving sensitivity. Furthermore, a self-designed device integrated with the FS-MC and a smartphone color picker APP was employed for the rapid automatic point-of-care testing (POCT) of DPA in the field, simplifying complex processes and reducing testing times, thus confirming the great promise of this ready-to-use measurement platform for in situ inspection.

Analysis of Immunobiochemical Parameters in Overweight People in Assessing the Risk of Cardiovascular Diseases.

A comparative analysis of specific immunobiochemical parameters, including natural antibodies (NAb) to endogenous regulators of the cardiovascular system, adrenal and gastrointestinal hormones, was performed in students aged 18-22 years with normal and increased body weight (the body mass index from 18.5 to 24.9 kg/m2 and from 25 to 29.9 kg/m2, respectively). The serum content of NAb and hormones was determined by ELISA. The level of the studied indicators depended on the body mass index value. In overweight subjects, the main immune indicators of the biogenic amine system, renin-angiotensin system, and kinin system exceeded the normal. The cortisol level was higher than in subjects with normal body weight. Aldosterone secretion was less dependent on the ACTH content and was lower than in students with normal body weight. The content of cholecystokinin and gastrin corresponded to the values for overweight. These trends in hormone contents are a predisposing factor for further weight gain. Practical significance of the combined assessment of disturbances in the immunological and biochemical homeostasis has been established. Analysis of the adrenal and gastrointestinal hormones can predict the risk of weight gain, but at the same time, changes in the level of immunological indicators in subjects with increased body weight characterizes the possibility of developing cardiovascular pathologies.

Calprotectin as new potential clinical marker for multiple myeloma.

Increased levels of inflammatory cytokines in multiple myeloma (MM) patients and the role of inflammation in disease pathogenesis, have recently been considered. The aim of this study was to quantitatively evaluation of fecal calprotectin (CP) as a non-invasive biomarker for the evaluation of inflammation in patients with multiple myeloma. This study is a hospital-based case control study. MM patients referred to patients referred to medical centers of Tehran province, Iran, were identified and classified into two groups of new MM patients (n = 40) and patients undergoing treatment (n = 28). Healthy individuals were included in the study as healthy control (n = 25). Morning stool samples were collected and CP was extracted immediately. After collecting the samples, CP was measured according to ELISA method and was determined in µg/g of feces. Values ​​above 50 µg/g of feces are positive and indicate inflammation. The results revealed that there is a significant difference between groups in terms if CP mean (p = 0.001). The mean of CP among new cases, under treatment and control groups were 301.3 (SD: 141.0), 165.1 (SD: 153.9) and 36.9 (SD: 13.5), respectively. Then the groups were compared in pairs, the results showed that the new case group was significantly different from the under-treatment group (p = 0.001), and also the control group showed a significant difference with the new case group (p = 0.001) and the under-treatment group (p = 0.001) that the amount of CP in the control group was significantly lower than the other two groups. In addition, the results of the study showed a significant correlation between age and plasma cells with CP value, so that with increasing age and plasma cells, CP value also showed a significant increase. The results indicate that quantitative evaluation of CP as a non-invasive laboratory biomarker has a high potential as a clinical marker in patients with multiple myeloma and inflammation should considered as a hallmark of cancer. Further diagnostic studies are recommended.

Investigation of Biomolecule Interactions: Optical-, Electrochemical-, and Acoustic-Based Biosensors.

Today, optical, electrochemical, and acoustic affinity biosensors; immunosensors; and immunoanalytical systems play an important role in the detection and characterization of a number of biological substances, including viral antigens, specific antibodies, and clinically important biomarkers [...].

Ultrassonografia morfológica de primeiro trimestre: importante ferramenta para rastreio de aneuploidias e pré-eclâmpsia / First-trimester morphological ultrasound: important tool for aneuploidy and pre-eclampsia screening

No início do século 20, as altas taxas de mortalidade materna e infantil estimularam o desenvolvimento de um modelo de atendimento pré-natal que mantivesse características parecidas até os dias atuais. Nesse modelo, haveria maior concentração de visitas durante o final do terceiro trimestre de gestação, devido às maiores taxas de complicações nas fases finais da gestação e à dificuldade de prever a ocorrência de resultados adversos durante o primeiro trimestre. Atualmente, a avaliação clínica durante o primeiro trimestre, com auxílio da ultrassonografia e marcadores bioquímicos, pode prever uma série de complicações que acometem a gestação, incluindo cromossomopatias, pré-eclâmpsia, restrição de crescimento fetal, anomalias fetais e trabalho de parto pré-termo.

At the beginning of the 20th century, the high rates of maternal and infant mortality stimulated the development of a model of prenatal care that maintained similar characteristics until the present day. In this model, there would be a greater concentration of visits during the end of the third trimester of pregnancy, due to the higher rates of complications in the final stages of pregnancy and the difficulty in predicting the occurrence of adverse outcomes during the first trimester. Currently, clinical evaluation during the first trimester, with the aid of ultrasound and biochemical markers, can predict a series of complications that affect pregnancy, including chromosomal disorders, preeclampsia, fetal growth restriction, fetal anomalies and preterm labor.

Development of an Efficient Extraction Methodology to Analyse Potential Inflammatory Biomarkers from Sebum.

INTRODUCTION: Proteins, such as cytokines and chemokines, are present in varying concentrations in a range of biofluids, with an important signalling role in maintaining homeostasis. Commercial tapes have been employed to non-invasively collect these potential biomarkers in sebum from the skin surface to examine their concentrations in conditions including acne, atopic dermatitis, and pressure ulcers. However, the identification of robust biomarker candidates is limited by the low abundance of specific proteins extracted by current methodologies. Therefore, this study was designed to develop an optimized extraction method for potential inflammatory biomarkers in sebum collected with Sebutapes. METHODS: Commercial tapes (Sebutapes) coated with synthetic sebum were used to systematically evaluate the effects of chemical and mechanical stimuli on extraction efficiency. Varying concentrations of high- and low-abundance biomarkers (IL-1α, IL-6, IL-8, INF-γ, TNF-α, and IL-1RA) were used to spike the synthetic sebum samples. Methodological variables included different surfactants, mechanical stimuli, and buffer volume. Extraction efficiency was estimated using immunoassay kits from the extracted buffer. RESULTS: The results revealed that the use of a surfactant, i.e., ß-dodecyl maltoside, in addition to the mechanical stimuli, namely, sonication and centrifugation, resulted in an increased recovery of cytokines, ranging from 80% for high-abundant cytokines, such as IL-1α and IL-1RA, and up to 50% for low-abundance cytokines, including TNF-α, IL-6 and IL-8. Compared to previous methods, the new extraction protocol resulted in between a 1.5-2.0-fold increase in extraction efficiency. CONCLUSION: The study revealed that there was a high degree of variability in the extraction efficiency of different cytokines. However, improved efficiency was achieved across all cytokines with selective surfactants and mechanical stimuli. The optimised protocol will provide means to detect low levels of potential biomarkers from skin surface, enabling the evaluation of local changes in pro- and anti-inflammatory cytokines present in different skin conditions.

Lipid Biogeochemistry and Modern Lipidomic Techniques.

Lipids are structurally diverse biomolecules that serve multiple roles in cells. As such, they are used as biomarkers in the modern ocean and as paleoproxies to explore the geological past. Here, I review lipid geochemistry, biosynthesis, and compartmentalization; the varied uses of lipids as biomarkers; and the evolution of analytical techniques used to measure and characterize lipids. Advancements in high-resolution accurate-mass mass spectrometry have revolutionized the lipidomic and metabolomic fields, both of which are quickly being integrated into marine meta-omic studies. Lipidomics allows us to analyze tens of thousands of features, providing an open analytical window and the ability to quantify unknown compounds that can be structurally elucidated later. However, lipidome annotation is not a trivial matter and represents one of the biggest challenges for oceanographers, owing in part to the lack of marine lipids in current in silico databases and data repositories. A case study reveals the gaps in our knowledge and open opportunities to answer fundamental questions about molecular-level control of chemical reactions and global-scale patterns in the lipidscape.

The Inflammation Biomarker GlycA Reflects Plasma N-Glycan Branching.

BACKGROUND: GlycA is a nuclear magnetic resonance (NMR) signal in plasma that correlates with inflammation and cardiovascular outcomes in large data sets. The signal is thought to originate from N-acetylglucosamine (GlcNAc) residues of branched plasma N-glycans, though direct experimental evidence is limited. Trace element concentrations affect plasma glycosylation patterns and may thereby also influence GlycA. METHODS: NMR GlycA signal was measured in plasma samples from 87 individuals and correlated with MALDI-MS N-glycomics and trace element analysis. We further evaluated the genetic association with GlycA at rs13107325, a single nucleotide polymorphism resulting in a missense variant within SLC39A8, a manganese transporter that influences N-glycan branching, both in our samples and existing genome-wide association studies data from 22 835 participants in the Women's Health Study (WHS). RESULTS: GlycA signal was correlated with both N-glycan branching (r2 ranging from 0.125-0.265; all P < 0.001) and copper concentration (r2 = 0.348, P < 0.0001). In addition, GlycA levels were associated with rs13107325 genotype in the WHS (ß [standard error of the mean] = -4.66 [1.2674], P = 0.0002). CONCLUSIONS: These results provide the first direct experimental evidence linking the GlycA NMR signal to N-glycan branching commonly associated with acute phase reactive proteins involved in inflammation.

Biomimetic Radical Chemistry and Applications.

Some of the most interesting aspects of free radical chemistry that emerged in the last two decades are radical enzyme mechanisms, cell signaling cascades, antioxidant activities, and free radical-induced damage of biomolecules. In addition, identification of modified biomolecules opened the way for the evaluation of in vivo damage through biomarkers. When studying free radical-based chemical mechanisms, it is very important to establish biomimetic models, which allow the experiments to be performed in a simplified environment, but suitably designed to be in strict connection with cellular conditions. The 28 papers (11 reviews and 17 articles) published in the two Special Issues of Molecules on "Biomimetic Radical Chemistry and Applications (2019 and 2021)" show a remarkable range of research in this area. The biomimetic approach is presented with new insights and reviews of the current knowledge in the field of radical-based processes relevant to health, such as biomolecular damages and repair, signaling and biomarkers, biotechnological applications, and novel synthetic approaches.

Peptidylglycine α-amidating monooxygenase as a therapeutic target or biomarker for human diseases.

Peptides play a key role in controlling many physiological and neurobiological pathways. Many bioactive peptides require a C-terminal α-amide for full activity. The bifunctional enzyme catalysing α-amidation, peptidylglycine α-amidating monooxygenase (PAM), is the sole enzyme responsible for amidated peptide biosynthesis, from Chlamydomonas reinhardtii to Homo sapiens. Many neuronal and endocrine functions are dependent upon amidated peptides; additional amidated peptides are growth promoters in tumours. The amidation reaction occurs in two steps, glycine α-hydroxylation followed by dealkylation to generate the α-amide product. Currently, most potentially useful inhibitors target the first reaction, which is rate-limiting. PAM is a membrane-bound enzyme that visits the cell surface during peptide secretion. PAM is then used again in the biosynthetic pathway, meaning that cell-impermeable inhibitors or inactivators could have therapeutic value for the treatment of cancer or psychiatric abnormalities. To date, inhibitor design has not fully exploited the structures and mechanistic details of PAM.

Assessment of salivary alpha-amylase and cortisol as a pain related stress biomarker in dogs pre-and post-operation.

BACKGROUND: The use of salivary biomarkers has garnered attention because the composition of saliva reflects the body's physiological state. Saliva contains a wide range of components, including peptides, nucleic acids, electrolytes, enzymes, and hormones. It has been reported that salivary alpha-amylase and cortisol are biomarkers of stress related biomarker in diseased dogs; however, evaluation of salivary alpha-amylase and cortisol pre- and post- operation has not been studied yet. The aim of this study was to evaluate salivary alpha-amylase and cortisol levels in dogs before and after they underwent surgery and investigate the association between the salivary alpha-amylase and cortisol activity and pain intensity. For this purpose, a total of 35 dogs with disease-related pain undergoing orthopedic and soft tissue surgeries were recruited. Alpha-amylase and cortisol levels in the dogs' saliva and serum were measured for each using a commercially available canine-specific enzyme-linked immunosorbent assay kit, and physical examinations (measurement of heart rate and blood pressure) were performed. In addition, the dogs' pre- and post-operative pain scores determined using the short form of the Glasgow Composite Measure Pain Scale (CMPS-SF) were evaluated. RESULTS: After surgery, there was a significant decrease in the dogs' pain scores (0.4-fold for the CMPS-SF, p < 0.001) and serum cortisol levels (0.73-fold, p < 0.01). Based on their pre-operative CMPS-SF scores, the dogs were included in either a high-pain-score group or a low-pain-score group. After the dogs in the high-pain-score group underwent surgical intervention, there was a significant decrease in their CMPS-SF scores and levels of salivary alpha-amylase, serum alpha-amylase, and serum cortisol. Additionally, there was a positive correlation between salivary alpha-amylase levels and CMPS-SF scores in both the high- and low-pain-score groups. CONCLUSIONS: The measurement of salivary alpha amylase can be considered an important non-invasive tool for the evaluation of pain-related stress in dogs.

Coupling immuno-magnetic capture with LC-MS/MS(MRM) as a sensitive, reliable, and specific assay for SARS-CoV-2 identification from clinical samples.

Recently, numerous diagnostic approaches from different disciplines have been developed for SARS-CoV-2 diagnosis to monitor and control the COVID-19 pandemic. These include MS-based assays, which provide analytical information on viral proteins. However, their sensitivity is limited, estimated to be 5 × 104 PFU/ml in clinical samples. Here, we present a reliable, specific, and rapid method for the identification of SARS-CoV-2 from nasopharyngeal (NP) specimens, which combines virus capture followed by LC-MS/MS(MRM) analysis of unique peptide markers. The capture of SARS-CoV-2 from the challenging matrix, prior to its tryptic digestion, was accomplished by magnetic beads coated with polyclonal IgG-α-SARS-CoV-2 antibodies, enabling sample concentration while significantly reducing background noise interrupting with LC-MS analysis. A sensitive and specific LC-MS/MS(MRM) analysis method was developed for the identification of selected tryptic peptide markers. The combined assay, which resulted in S/N ratio enhancement, achieved an improved sensitivity of more than 10-fold compared with previously described MS methods. The assay was validated in 29 naive NP specimens, 19 samples were spiked with SARS-CoV-2 and 10 were used as negative controls. Finally, the assay was successfully applied to clinical NP samples (n = 26) pre-determined as either positive or negative by RT-qPCR. This work describes for the first time a combined approach for immuno-magnetic viral isolation coupled with MS analysis. This method is highly reliable, specific, and sensitive; thus, it may potentially serve as a complementary assay to RT-qPCR, the gold standard test. This methodology can be applied to other viruses as well.

Characterization of Anopheles gambiae D7 salivary proteins as markers of human-mosquito bite contact.

BACKGROUND: Malaria is transmitted when infected Anopheles mosquitoes take a blood meal. During this process, the mosquitoes inject a cocktail of bioactive proteins that elicit antibody responses in humans and could be used as biomarkers of exposure to mosquito bites. This study evaluated the utility of IgG responses to members of the Anopheles gambiae D7 protein family as serological markers of human-vector contact. METHODS: The D7L2, D7r1, D7r2, D7r3, D7r4 and SG6 salivary proteins from An. gambiae were expressed as recombinant antigens in Escherichia coli. Antibody responses to the salivary proteins were compared in Europeans with no prior exposure to malaria and lifelong residents of Junju in Kenya and Kitgum in Uganda where the intensity of malaria transmission is moderate and high, respectively. In addition, to evaluate the feasibility of using anti-D7 IgG responses as a tool to evaluate the impact of vector control interventions, we compared responses between individuals using insecticide-treated bednets to those who did not in Junju, Kenya where bednet data were available. RESULTS: We show that both the long and short forms of the D7 salivary gland antigens elicit a strong antibody response in humans. IgG responses against the D7 antigens reflected the transmission intensities of the three study areas, with the highest to lowest responses observed in Kitgum (northern Uganda), Junju (Kenya) and malaria-naïve Europeans, respectively. Specifically, the long form D7L2 induced an IgG antibody response that increased with age and that was lower in individuals who slept under a bednet, indicating its potential as a serological tool for estimating human-vector contact and monitoring the effectiveness of vector control interventions. CONCLUSIONS: This study reveals that D7L2 salivary antigen has great potential as a biomarker of exposure to mosquito bites and as a tool for assessing the efficacy of vector control strategies such as bednet use.

The metabolite profiling of 3,4-dicaffeoylquinic acid in Sprague-Dawley rats using ultra-high performance liquid chromatography equipped with linear ion trap-Orbitrap MS.

3,4-Dicaffeoylquinic acid (3,4-DiCQA) is a dicaffeoylquinic acid that possesses antioxidant, anti-inflammatory, antibacterial, antiviral, anticancer, hypoglycemic, hypotensive, and hepatoprotective activities. This study developed a rapid and reliable method using ultra-high performance liquid chromatography equipped with linear ion trap-Orbitrap MS to identify the metabolites of 3,4-DiCQA in rat plasma, urine, feces, and tissues. The metabolic profile of 3,4-DiCQA was determined after an oral administration of 200 mg/kg to rats. A strategy of full scan-parent ions list acquisition coupled to diagnostic product ion analysis for screening and identification of target metabolites was used. A total of 67 metabolites, combined with accurate mass measurement, diagnostic ions, neutral losses, and reference standards, were observed and characterized for the first time. The results indicated that hydrolysis, methylation, hydrogenation, hydration, dehydroxylation, dehydrogenation, sulfate conjugation, and glucuronide conjugation were the major metabolic reactions of 3,4-DiCQA in vivo.

Advances in multiplex electrical and optical detection of biomarkers using microfluidic devices.

Microfluidic devices can provide a versatile, cost-effective platform for disease diagnostics and risk assessment by quantifying biomarkers. In particular, simultaneous testing of several biomarkers can be powerful. Here, we critically review work from the previous 4 years up to February 2021 on developing microfluidic devices for multiplexed detection of biomarkers from samples. We focus on two principal approaches: electrical and optical detection methods that can distinguish and quantify biomarkers. Both electrical and spectroscopic multiplexed detection strategies are being employed to reach limits of detection below clinical sample levels. Some of the most promising strategies for point-of-care assays involve inexpensive materials such as paper-based microfluidic devices, or portable and accessible detectors such as smartphones. This review does not comprehensively cover all multiplexed microfluidic biomarker studies, but rather provides a critical evaluation of key work and suggests promising prospects for future advancement in this field. Electrical and optical multiplexing are powerful approaches for microfluidic biomarker analysis.

Signal amplification strategies for clinical biomarker quantification using elemental mass spectrometry.

The current trends in modern medicine towards early diagnosis, or even prognosis, of different diseases have brought about the need for the corresponding biomarker detection at ever lower levels in really complex matrices. To do so, it is necessary to use proper extremely sensitive detection techniques such as elemental mass spectrometry. However, target labelling with metals for subsequent sensitive ICP-MS detection falls short nowadays even if resorting to inorganic nanoparticles containing a high number of detectable elements. Thus, new amplification strategies are being proposed to face this analytical challenge that will be critically discussed in this paper. Fundamentals of different novel strategies developed to achieve signal amplification and sensitive elemental mass spectrometry detection are here discussed. Some representative examples of relevant clinical applications are highlighted, along with future prospects and challenges.

Biomarkers of Mycoplasma pneumoniae pneumonia in children by urine metabolomics based on Q Exactive liquid chromatography/tandem mass spectrometry.

RATIONALE: Mycoplasma pneumoniae has become one of the common pathogens causing pediatric respiratory infections. In clinical diagnosis, throat swabs are very difficult to obtain from children, and there is a possibility of false positive results; hence, there are few clinically available diagnostic methods. METHODS: In this study, Q Exactive liquid chromatography/tandem mass spectrometry was used to analyze the metabolites in the urine of healthy children (HC) and M. pneumoniae pneumonia in children (MPPC) patients. A multivariate statistical analysis was performed to screen the differential metabolites. Based on the HMDB and KEGG, the possible metabolic pathways subject to biological alteration were identified. RESULTS: Compared with HC, 73 different metabolites in MPPC patients disrupted nine metabolic pathways through different change trends; after integrating various parameters, 20 significantly different metabolites were identified as MPPC potential biomarkers. Through the above two analysis modes, acetylphosphate and 2,5-dioxopentanoate were both screened out and used as potential biomarkers for the early diagnosis of MPPC for the first time. CONCLUSIONS: The characterization of 20 potential biomarkers provides a scientific basis for predicting and diagnosing MPPC. This article further indicates that urine metabolic profiling has great potential in diagnosing MPPC and can effectively prevent the disease from causing further deterioration.