Early detection of acrolein precursors in vegetable oils by using proton transfer reaction - mass spectrometry

Acrolein is a toxic volatile compound derived from oxidative processes, that can be formed in foods during storage and cooking. This study employs proton transfer reaction mass spectrometry (PTR-MS) to detect acrolein precursors in vegetable oils by focusing on the m/z (mass-to-charge ratio) 57. To this purpose, hempseed, sesame, walnut, olive and linseed oils were stored for 168 h at 60 °C in presence of 2,2'-azobis(2-metilpropionitrile) (3 mM) radicals initiator. The evolution of m/z 57 by PTR-MS was also compared with traditional lipid oxidation indicators such as peroxide value, conjugated diene, oxygen consumption and, isothermal calorimetry. The obtained results were explained by the fatty acid composition and antioxidant capacity of the oils. Hempseed fresh oil presented a very low total volatile organic compounds (VOCs) intensity (5.6 kncps). Nonetheless, after storage the intensity increased ∼70 times. A principal component analysis (PCA) confirmed the potential of m/z 57 to differentiate fresh versus rancid hempseed oil sample. During an autoxidation experiment oils high in linolenic and linoleic acids showed higher m/z 57 emissions and shorter induction times: linseed oil (38 h) > walnut oil (47 h) > hempseed oil (80 h). The m/z 57 emission presented a high correlation coefficient with the total VOC signal (r > 0.95), conjugated dienes and headspace oxygen consumption. A PCA analysis showed a complete separation of the fresh oils on the first component (most significant) with the exception of olive oil. Walnut, hempseed and linseed oil were placed on the extreme right nearby total VOCs and m/z 57. The results obtained highlight the potential of PTR-MS for the early detection of oil autoxidation, serving as a quality control tool for potential acrolein precursor emissions, thereby enhancing food safety in the industry.

Optical characterization of stratified-premixed natural gas direct-injection combustion regimes

Gaseous fuels for heavy-duty internal combustion engines provide inherent advantages for reducing CO₂, particulate matter (PM), and NO_X emissions. Pilot-ignited direct-injected NG (PIDING) combustion uses a small pilot injection of diesel to ignite a late-cycle main direct injection of NG, resulting in significant reduction of unburned CH₄ emissions relative to port-injected NG. Previous works have identified NG premixing as a critical parameter establishing indicated efficiency and emissions performance. To this end, a recent experimental investigation using a metal engine identified six general regimes of PIDING heat release and emissions behavior arising from variation of NG stratification through control of relative injection timing (RIT) of the NG with respect to the pilot diesel. The objective of the current work is to provide comprehensive description of in-cylinder fuel mixing of direct injected gaseous fuel and its impacts on combustion and pollutant formation processes for stratified PIDING combustion. In-cylinder imaging of OH*-chemiluminescence (OH*-CL) and PM (700 nm), and measurement of local concentration of fuel is considered for 11 different RIT , representing 5 regimes of stratified PIDING combustion (performed with P inj = 22 . 0 MPa and ϕ = 0 . 63 ). The magnitude and cyclic variability of premixed fuel concentration near the bowl wall provides direct experimental validation of thermodynamic metrics ( RI T premix , SO I NG , trans , RI T * ) that describe the fuel-air mixture state of all 5 regimes of PIDING combustion. The local fuel concentration develops non-monotonically and is a function of RIT. High indicated efficiency and low CH₄ emissions previously observed for stratified-premixed PIDING combustion in previous (non-optical) investigations are due to: (i) very rapid reaction zone growth ( > 45 m/s) and (ii) more distributed early reaction zones when overlapping pilot and NG injections cause partial pilot quenching. These results connect and extend the findings of previous investigations and guide the future strategic implementation of NG stratification for improved combustion and emissions performance.

AAV-Mediated Gene Delivery to Mouse Brown Adipose Tissue

Recombinant adeno-associated virus (AAV) vectors are attractive vehicles for gene therapy. Yet targeting adipose tissue is still a challenging task. We recently showed that a novel engineered hybrid serotype Rec2 displays high efficacy of gene transfer to both brown and white fat. Furthermore, the administration route influences the tropism and efficacy of Rec2 vector with oral administration transducing interscapular brown fat, while intraperitoneal injection preferentially targets visceral fat and liver. To restrict off-target transgene expression in the liver, we further develop a single rAAV vector harboring two expression cassettes: one using CBA promoter driving a transgene and another using a liver-specific albumin promoter driving a microRNA targeting the woodchuck posttranscriptional regulatory element (WPRE) sequence in this rAAV vector. In vivo studies by our lab and others have shown that the Rec2/dual-cassette vector system provides a powerful tool for gain-of-function and loss-of-function studies. Here we offer an updated protocol for AAV packaging and delivery to brown fat.

Optimal concentration of mesenchymal stem cells for fracture healing in a rat model with long bone fracture

BACKGROUND

There is still no consensus on which concentration of mesenchymal stem cells (MSCs) to use for promoting fracture healing in a rat model of long bone fracture.

AIM

To assess the optimal concentration of MSCs for promoting fracture healing in a rat model.

METHODS

Wistar rats were divided into four groups according to MSC concentrations: Normal saline (C), 2.5 × 10⁶ (L), 5.0 × 10⁶ (M), and 10.0 × 10⁶ (H) groups. The MSCs were injected directly into the fracture site. The rats were sacrificed at 2 and 6 wk post-fracture. New bone formation [bone volume (BV) and percentage BV (PBV)] was evaluated using micro-computed tomography (CT). Histological analysis was performed to evaluate fracture healing score. The protein expression of factors related to MSC migration [stromal cell-derived factor 1 (SDF-1), transforming growth factor-beta 1 (TGF-β1)] and angiogenesis [vascular endothelial growth factor (VEGF)] was evaluated using western blot analysis. The expression of cytokines associated with osteogenesis [bone morphogenetic protein-2 (BMP-2), TGF-β1 and VEGF] was evaluated using real-time polymerase chain reaction.

RESULTS

Micro-CT showed that BV and PBV was significantly increased in groups M and H compared to that in group C at 6 wk post-fracture (P = 0.040, P = 0.009; P = 0.004, P = 0.001, respectively). Significantly more cartilaginous tissue and immature bone were formed in groups M and H than in group C at 2 and 6 wk post-fracture (P = 0.018, P = 0.010; P = 0.032, P = 0.050, respectively). At 2 wk post-fracture, SDF-1, TGF-β1 and VEGF expression were significantly higher in groups M and H than in group L (P = 0.031, P = 0.014; P < 0.001, P < 0.001; P = 0.025, P < 0.001, respectively). BMP-2 and VEGF expression were significantly higher in groups M and H than in group C at 6 wk post-fracture (P = 0.037, P = 0.038; P = 0.021, P = 0.010). Compared to group L, TGF-β1 expression was significantly higher in groups H (P = 0.016). There were no significant differences in expression levels of chemokines related to MSC migration, angiogenesis and cytokines associated with osteogenesis between M and H groups at 2 and 6 wk post-fracture.

CONCLUSION

The administration of at least 5.0 × 10⁶ MSCs was optimal to promote fracture healing in a rat model of long bone fractures.

Direct injection of Amblyomma americanum ticks with Cytauxzoon felis

Cytauxzoon felis is a tick-borne hemoprotozoan parasite that causes life-threatening disease in domestic cats in the United States. Currently, the platforms for C. felis research are limited to natural or experimental infection of domestic cats. This study aims to develop an alternative model by infecting Amblyomma americanum ticks with C. felis via direct injection. Amblyomma americanum adults were injected with C. felis-infected feline erythrocytes through two routes: directly into the digestive tract through the anal pore (IA injection), or percutaneously into the tick hemocoel (IH injection). RNAscope® in situ hybridization (ISH) was used to visualize the parasites within the ticks at different time points after injection. Four months after injection, ticks were divided into 3 infestation groups based on injection methods and inoculum type and fed on 3 naïve cats to assess the ticks' ability to transmit C. felis. Prior to the transmission challenge, selected ticks from each infestation group were tested for C. felis RNA via reverse transcription-PCR (RT-PCR). In both IA- and IH-injected ticks, ISH signals were observed in ticks up to 3 weeks after injection. The number of hybridization signals notably decreased over time, and no signals were detected by 4 months after injection. Prior to the transmission challenge, 37-57% of the sampled ticks were positive for C. felis RNA via RT-PCR. While the majority of injected ticks successfully attached and fed to repletion on all 3 cats during the transmission challenge, none of the cats became infected with C. felis. These results suggest that injected C. felis remained alive in ticks but was unable to progress to infective sporozoites after injection. It is unclear why this infection technique had been successful for other closely related tick-borne hemoprotozoa and not for C. felis. This outcome may be associated with uncharacterized differences in the C. felis life cycle, the lack of the feeding or molting in our model or absence of gametocytes in the inoculum. Nonetheless, our study demonstrated the potential of using ticks as an alternative model to study C. felis. Future improvement of a tick model for C. felis should consider other tick species for the injection model or utilize infection methods that more closely emulate the natural infection process.

Approaches to liquid chromatography tandem mass spectrometry assessment of glyphosate residues in wine

The performance of two different analytical methodologies to investigate the presence of glyphosate (GLY) and aminomethylphosphonic acid (AMPA) residues in wine samples was evaluated. Transformation of compounds in their fluorene-9-methyloxycarbonyl derivatives permitted their separation under reversed-phase liquid chromatography with tandem mass spectrometry (LC-MS/MS) determination. Although the wine matrix severely impaired the efficiency of GLY derivatization, this drawback was solved using a molecularly imprinted sorbent for the previous, selective extraction of GLY and AMPA from wine. Alternatively, the use of a strong anionic exchange, polyvinyl alcohol-based LC column, turned to be the most effective alternative for direct determination of both compounds in diluted wine samples. The chromatographic behavior of this column and the magnitude of matrix effects observed during analysis of diluted wine samples were significantly affected by the composition of the mobile phase. Under final working conditions, this column permitted the separation of AMPA and the fungicide fosetyl (which shows common transitions in tandem MS/MS methods), it improved significantly the sample throughput versus extraction-derivatization-purification method, and it allowed the use of solvent-based calibration standards. Both analytical procedures provided similar limits of quantification (LOQs) for GLY (0.5-1.0 ng mL-1), while the multistep method was 8 times more sensitive to AMPA than the direct procedure. GLY residues stayed above method LOQs in 70% of the processed wines; however, concentrations measured in 95% of positive samples remained 100 times below the maximum residue limit (MRL) set for GLY in vinification grapes.

Rapid and sensitive analytical method for the determination of amoxicillin and related compounds in water meeting the requirements of the European union watch list

The presence of antibiotics in the aquatic environment is becoming one of the main research focus of scientists and policy makers. Proof of that is the inclusion of four antibiotics, amongst which is amoxicillin, in the EU Watch List (WL) (Decision 2020/1161/EU)) of substances for water monitoring. The accurate quantification of amoxicillin in water at the sub-ppb levels required by the WL is troublesome due to its physicochemical properties. In this work, the analytical challenges related to the determination of amoxicillin, and six related penicillins (ampicillin, cloxacillin, dicloxacillin, penicillin G, penicillin V and oxacillin), have been carefully addressed, including sample treatment, sample stability, chromatographic analysis and mass spectrometric detection by triple quadrupole. Given the low recoveries obtained using different solid-phase extraction cartridges, we applied the direct injection of water samples using a reversed-phase chromatographic column that allowed working with 100% aqueous mobile phase. Matrix effects were evaluated and corrected using the isotopically labelled internal standard or correction factors based on signal suppression observed in the analysis of spiked samples. The methodology developed was satisfactorily validated at 50 and 500 ng L ^- 1 for the seven penicillins studied, and it was applied to different types of water matrices, revealing the presence of ampicillin in one surface water sample and cloxacillin in three effluent wastewater samples.

High throughput and low bias DNA methylation and hydroxymethylation analysis by direct injection mass spectrometry

We present a direct injection mass spectrometry (DI-MS) platform that accurately, precisely, and quickly quantitates global levels of DNA cytidine methylation (5 mC) and hydroxymethylation (5hmC). Our platform combines an Advion TriVersa NanoMate coupled online to a Thermo Scientific Orbitrap Fusion Lumos. Following digestion to nucleosides, the DNA samples are analyzed at the rate of <1 min per injection with comparable detection limits of 0.63 ng/μL and 0.31 ng/μL, respectively. In contrast, the detection limits for 5 mC and 5hmC in state-of-art nano liquid chromatography (LC) coupled to online mass spectrometry (nLC-MS) are notably different (0.04 ng/μL and 2.5 ng/μL, respectively). The high sensitivity of DI-MS is achieved by optimizing sample buffer composition, the source fragmentation energy, and the radio frequency of the instrument ion funnel. DI-MS accurately reports the relative abundance of 5 mC and 5hmC over a range of 1%-7% (R² > 0.98) and 0.13%-1.75% (R² > 0.99), respectively. Accurate measurement of C, 5 mC and 5hmC is achieved by optimizing in-source fragmentation to obtain a population of up to 93% of just the nucleoside base. This protocol minimizes base dimer formation and partial base-deoxyribose dissociation in gas phase and greatly improves modified base quantitation. We also demonstrate that DI-MS overcomes biases in differential chromatographic retention and issues of sample degradation in the autosampler due to its high throughput. Finally, we present an application of our workflow to quantify DNA modifications on a batch of 81 samples in about 1.5 h.

Combining direct urinary injection with automated filtration and nanoflow LC-MS for the confirmatory analysis of doping-relevant small peptide hormones

Nano-liquid chromatography (nanoLC) has proven itself as a powerful tool and its scope entails various applications in (bio)analytical fields. Operation at low (nL/min) flow rates in combination with reduced inner dimensions (ID < 100 µm), leads to significantly enhanced sensitivity when coupled with electrospray ionization-mass spectrometry (ESI-MS). Challenges that remain for the routine implementation of such miniaturized setups are related to clogging of the system and robustness in general, and thus the application of tedious sample preparation steps. To improve ruggedness, a filter placed upstream in the LC prevents particles from entering and clogging the system. This so-called online automatic filtration and filter back-flush (AFFL) system was combined with nanoLC and the direct injection principle for the sensitive confirmatory analysis of fifty different doping-relevant peptides in urine. The presented assay was fully validated for routine purposes according to selectivity and matrix interference, limit of identification (LOI), carryover, matrix effect, sample extract stability, analysis of educational external quality assessment (EQAS) samples, robustness of the online AFFL-setup and retention time stability. It was also fully compliant with the most recent minimum required performance levels (MRPL) and chromatographic/mass spectrometric identification criteria (IDCR), as imposed by the World Anti-Doping Agency (WADA). In the absence of labor-intensive sample preparation, the application of AFFL allowed for the injection of diluted urine samples without any noticeable pressure buildup in the nanoLC system. Contrary to earlier observations by our group and others, the addition of dimethylsulfoxide (DMSO) to the mobile phase did not enhance sensitivity in the presented nanoflow setup, yet was beneficial to reduce carry over. Although the robustness of the presented setup was evaluated only for the analysis of diluted urine samples, it is entirely conceivable that routine applications employing other matrices and currently running on analytical scale LC instruments could be transferred to micro/nanoLC scale systems to reach lower detection limits.

Direct injection analysis of per and polyfluoroalkyl substances in surface and drinking water by sample filtration and liquid chromatography-tandem mass spectrometry

We developed and validated a method for direct determination of per- and polyfluoroalkylated substances (PFASs) in environmental water samples without prior sample concentration. Samples are centrifuged and supernatants passed through an Acrodisc Filter (GXF/GHP 0.2  um, 25  mm diameter). After addition of ammonium acetate, samples are analyzed by UPLC-MS/MS using an AB Sciex 6500 plus Q-Trap mass spectrometer operated in negative multiple reaction-monitoring (MRM) mode. The instrument system incorporates a delay column between the pumps and autosampler to mitigate interference from background PFAS. The method monitors eight short-/long-chain PFAS which are identified by monitoring specific precursor product ion pairs and by their retention times and quantified using isotope mass-labeled internal standard based calibration plots. Average spiked recoveries (n = 8) of target analytes ranged from 84 to 110% with 4-9% relative standard deviation (RSD). The mean spiked recoveries (n = 8) of four surrogates were 94-106% with 3-8% RSD. For continuous calibration verification (CCV), average spiked recoveries (n = 8) for target analytes ranged from 88 to 114% with 4-11% RSD and for surrogates ranged from 104-112% with 3-11% RSD. The recoveries (n = 6) of matrix spike (MX), matrix spike duplicate (MXD), and field reagent blank (FRB) met our acceptance criteria. The limit of detection for the target analytes was between 0.007 and 0.04 ng/mL. The method was used to measure PFAS in tap water and surface water.

Mitochondrial Transplantation for Ischemia Reperfusion Injury

Mitochondrial transplantation is a novel therapeutic intervention to treat ischemia-reperfusion-related disorders. This approach uses replacement of native mitochondria with viable, respiration-competent mitochondria isolated from non-ischemic tissue obtained from the patient's own body, to overcome the many deleterious effects of ischemia-reperfusion injury on native mitochondria. The safety and efficacy of this methodology has been demonstrated in cell culture, animal models and has been shown to be safe and efficacious in a phase I clinical trial in pediatric cardiac patients with ischemia-reperfusion injury. These studies have demonstrated that mitochondrial transplantation rescues myocardial cellular viability and significantly enhances postischemic myocardial function following ischemia-reperfusion injury. Herein, we describe methodologies for the delivery of isolated mitochondria.

Detection of nanoparticles by single-particle ICP-MS with complete transport efficiency through direct nebulization at few-microlitres-per-minute uptake rates

Measurement of nanoparticle (NP) concentration and size by single-particle inductively coupled plasma mass spectrometry (spICP-MS) usually requires the use of a NP reference material to determine the loss of NPs and/or ions during their transport from the sample solution to the detection system. The determination of this loss, qualified as nebulization efficiency (η_Nebulization) and/or transport efficiency (η_Transport), is time-consuming, costly and lacks reliability. Nebulization of the NPs directly into the plasma (without a spray chamber) results in η_Nebulization = 100% and is thus a promising strategy to avoid these calibration steps. In this work, we used the μ-dDIHEN introduction system: a demountable direct injection high-efficiency nebulizer (dDIHEN) hyphenated to a flow-injection valve and a gas displacement pump. For the first time with a continuous flow nebulizer, complete transport efficiency was reached (i.e. η_Transport = 100%). Operated at a very low uptake rate (as low as 8 μL min^-1), the μ-dDIHEN accurately and reproducibly determined average diameters of Au-, Ag- and Pt-NPs, in full agreement with their reference values. It was also successfully tested for Au-NPs in complex matrices, such as surface waters. spICP-MS analyses with the μ-dDIHEN sample introduction system only require a dissolved standard calibration to determine NP average diameter (d_NPs in nm) and number concentration (N_NPs) from the simplified set of equations: [Formula: see text] and [Formula: see text]Graphical abstract.

Determination of anabasine, anatabine, and nicotine biomarkers in wastewater by enhanced direct injection LC-MS/MS and evaluation of their in-sewer stability

Wastewater-based epidemiology (WBE) has been used to estimate tobacco use in the population. However, the increased use of nicotine replacement therapies and e-cigarettes contributes to the load of nicotine metabolites in wastewater, causing over-estimation of tobacco use if nicotine metabolites were used in WBE back-estimation. This study aims to develop a rapid method for determining the tobacco-specific biomarkers, anabasine and anatabine, in wastewater and to evaluate their in-sewer stability for better estimation of tobacco use by WBE. An enhanced direct injection LC-MS/MS was developed to quantify anabasine and anatabine as well as nicotine biomarkers (nicotine, cotinine and hydroxycotinine). The method was optimal when wastewater was filtered through 0.2 μm RC syringe filters and a pre-conditioned SPE cartridge (Oasis HLB 1 cc, 30 mg) before 50 μL was injected into the LC-MS/MS system. Limits of quantification varied between 2.7 and 54.9 ng/L with recoveries from 76% to 103% for all five compounds. In sewer reactors, anabasine and anatabine were less stable than cotinine and hydroxycotinine. They were more stable in the gravity sewer reactor with <20% loss in 12 h than in the rising main sewer reactor with ~30% loss in the same period. We then applied the new method to 42 daily wastewater influent samples collected from an Australian wastewater treatment plant. The five biomarkers were detected in all samples with concentrations ranging from 9.2 to 7430 ng/L. All five compounds were positively correlated with one another. Our results suggested a high throughput analytical method for feasible application in anabasine and anatabine as biomarkers of tobacco use in routine wastewater monitoring.

Identification of biomarkers for early diagnosis of diabetic nephropathy disease using direct flow through mass spectrometry

BACKGROUND AND AIMS

Albuminuria is not an effective marker for early diagnosis of diabetic renal complication with several subjects progressing to chronic kidney disease without any albuminuria. A biomarker that can predict early changes of the diabetic kidney will be useful in effective management of type 2 diabetes. Mass spectrometry based metabolomics approach offers tremendous promise for the identification of novel metabolite biomarkers.

METHODS

A case-control approach was carried out to identify renal biomarkers among Asian Indian subjects in a hospital setting. A total of 29 subjects were included in the study that included groups of diabetic controls, diabetic subjects with eGFR >90 ml/min/1.72 m² and diabetic subjects with eGFR between 60 and 89 ml/min/1.72 m² and eGFR between 15 and 30 ml/min/1.72 m². We employed an un-targeted mass spectrometry method for the identification of plasma metabolites.

RESULTS

A total of 1414 and 975 metabolites were identified in the positive and negative ion mode respectively. 19 metabolites were up regulated and 18 metabolites were down regulated in CKD2 and CKD4 groups when compared to control. Correlation analysis of the differential metabolites revealed Pregnenolone sulfate, creatinine and ganglioside GA1 to be negatively correlated and hexyl glucoside, all-trans-carophyll yellow and PG to be positively correlated with eGFR.

CONCLUSION

We have identified Pregnenolone sulfate, GA1, PG and all-trans-Carophyll yellow as biomarkers for early identification of diabetic nephropathy. These markers could aid in better management of diabetic nephropathy that may result delaying the progression of the disease.

Occurrence and risk assessment of fluoroquinolone antibiotics in reclaimed water and receiving groundwater with different replenishment pathways

Artificial recharge to groundwater with reclaimed water is considered a promising method to alleviate groundwater depletion and over-exploitation. However, the occurrence of fluoroquinolone antibiotics (FQs) was ubiquitous in wastewater, surface water, groundwater and even drinking water threating human health and ecology. In this study, the occurrence of six selected FQs in reclaimed water effluent and their removal by tertiary treatment units were investigated. The overall removal efficiencies in average of the tertiary treatment processes in Beijing and Changzhou were ranging from 21.2% to 55.2%. Activated carbon exhibited better performance for FQs removal than ozone and biological treatment such as membrane bioreactor, anaerobic-anoxic-oxic and biofilter. The results of two pilot study showed that the impact of reclaimed water to groundwater quality in terms of FQs concentration by direct injection in GBD was stronger than surface spreading in Changzhou, which might be due to the recharge strategy and the physical and chemical characteristics of sediment and aquifer soil. The hazard quotient (HQ) values of ofloxacin (OFL) in reclaimed water was up to 12.54, indicating the extreme eco-toxicological risk, while enrofloxacin (ENR) exhibited medium risk. After recharge with reclaimed water, the HQ values of OFL and ENR in groundwater ranged from low to medium ecological risk to the environment. Thus, the FQs in reclaimed water need to be paid more attention during their reuse for groundwater recharge, especially by direct injection. It is suggested that FQs should be considered in the priority substances lists in standards and guidelines of reclaimed water reuse for groundwater recharge to ensure the safety of groundwater.

A Workflow for Ultra-rapid Analysis of Histone Post-translational Modifications with Direct-injection Mass Spectrometry

Chromatin modifications, like histone post translational modifications (PTMs), are critical for tuning gene expression and many other aspects of cell phenotype. Liquid chromatography coupled to mass spectrometry (LC-MS) has become the most suitable method to analyze histones and histone PTMs in a large-scale manner. Selected histone PTMs have known functions, and their aberrant regulation is linked to a wide variety of diseases, including cancer. However, histone analysis is scarcely used in diagnostics, partially due to the limited throughput and not ideal reproducibility of LC-MS based analysis. We describe a workflow that allows for high-throughput sample preparation is less than a day using 96-well plates. Following preparation, samples are sprayed into MS without LC, using an automated direct injection (DI-MS) method. Each analysis provides accurate quantification for 29 peptide sequences with 45 PTMs (methylations, acetylations and phosphorylations) for a total of 151 histone marks plus 16 unmodified histone peptides for relative quantification of histone variants. This workflow allows for < 1 min MS runs and higher reproducibility and robustness due to the absence of carryover or LC-based batch effects. Finally, we describe an engineered peptide sequence used to accurately monitor the efficiency of sample preparation, which can be detected during the DI-MS run.

Direct injection Fourier transform ion cyclotron resonance mass spectrometric method for high throughput quantification of quinolones in poultry

Many recent studies have shown high detection frequencies of quinolone antibiotics in poultry, as well as an increasing incidence of antimicrobial resistance. The main purpose of this project was to develop a fast and reliable analytical method for the detection of quinolones in poultry meat. In order to develop a rapid quantitative confirmation method, ion cyclotron resonance mass spectrometer was used. First, the sample preparation procedure was simplified by reducing the procedure to extraction and freezing out steps. Second, the chromatographic separation step was excluded and mass spectrometric parameters were optimised. Third, the method was validated by fortifying a blank matrix at four levels (0.5, 1, 1.5, and 2 times the maximum residue limit (MRL) or level of interest in those cases when no MRL was established). As a result, the overall analysis time was reduced to less than an hour. The validation study revealed that the method is capable of detection and confirmation of ten quinolone compounds in poultry above the detection capability (CCβ) of the procedure. Finally, the developed method was applied to 19 commercially available chicken meat samples. None of the samples contained quinolones above the limit of quantification (LOQ) of the method. Analysis of treated chickens revealed that the developed method is suitable for the determination of ciprofloxacin and enrofloxacin. The developed method could be one of the fastest quantitative confirmatory methods for the analysis of quinolones available so far.

A serial PFASs sorption technique coupled with adapted high volume direct aqueous injection LCMS method

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous global environmental contaminants, environmentally persistent, mobile, can bioaccumulate and are toxic. Increasing emphasis is placed on the immobilisation and removal of PFAS from contaminated environmental matrices such as: potable water, surface water, groundwater, wastewater, sediments and soils (Dauchy et al., 2017; Cao et al., 2019; Hepburn et al., 2019). To achieve this, development of PFAS sorbents is increasingly undertaken (Du et al., 2014). Sorption studies are used to observe the interaction of sorbent and sorbate, but have two key limitations when undertaking sorption experiments for PFAS (1) the experimental protocol and (2) analytical techniques. The current batch sorption methods approached recommended by OECD Guideline 106 (OECD, 2000) are problematic, firstly, due to large sample numbers and PFAS specific laboratory difficulties, including near ubiquitous background PFAS contamination. Secondly, PFAS analytical techniques currently require solid-phase extraction (SPE) to be employed, which is slow and expensive, prior to instrumental analysis with liquid chromatography-mass spectrometry (LC-MS). A suitable alternative approach is needed to mitigate the drawbacks of current methodologies whilst catering for the high sample throughput required by benchtop trials characterising the sorption behaviour of PFAS - sorbent pairings.•

A suitable method for PFAS measurement, overcoming shortcomings of current batch sorption methodologies is presented

•

The method can be applied to a wide range of sorbents and sorption environment conditions associated with PFAS immobilisation or removal in the environment

•

The presented method is novel through its high sample throughput, simple approach and minimisation of cross contamination sources

A direct injection liquid chromatography tandem mass spectrometry method for the kinetic study on iodinated contrast media (ICMs) removal in natural water

Iodinated contrast media (ICMs) are a class of X-ray contrast media worldwide utilized for radiographic procedures. Since they cannot be removed efficiently during water treatment, they can be found in surface and groundwater. In this work, a rapid and sensitive direct injection liquid chromatography-tandem (LC-MS/MS) method for the simultaneous analysis of seven ICMs media (iopamidol, ioxitalamic acid, diatrizoic acid, iothalamic acid, iohexol, iomeprol and iopromide) in complex aqueous matrices has been developed and validated. The MDLs for the analytes ranged from 0.7 to 21 ng L^-1 in ultrapure water, and recoveries ranged from 86 to 100% in drinking water, 85-103% in groundwater and 84-105% in WWTP effluent. A stereo-isomer for iopromide was separated. This analytic method was applied to investigate the removal of target ICMs by low pressure ultra violet light (LPUV) advanced oxidation processes with three oxidants, hydrogen peroxide, free chlorine and monochloramine in groundwater. Results showed that the addition of oxidants did not enhance attenuation of ICMs, since fluence-based decay apparent rate constants were similar (K_UV = 3.2 × 10^-3, K_UV-Cl2 = 3.6 × 10^-3 and K_UV-NH2 = 3.4 × 10^-3 10^-3 cm² mJ^-1). This yielded direct photolysis is the main mechanism to attenuate target ICMs.

Micellar liquid chromatography determination of rivaroxaban in plasma and urine. Validation and theoretical aspects

A Micellar Chromatographic method to determine rivaroxaban in plasma and urine has been developed. The samples were dissolved in the mobile phase (SDS 0.05 M - 1-propanol 12.5%, phosphate buffered at pH 7) and 20 μL directly injected, avoiding the extraction and purification steps. Using a C18 column and running under isocratic mode at 1 mL/min, analyte was eluted without interference from the matrix in <6.0 min. The detection absorbance wavelength was set to 250 nm. The procedure was validated by Food and Drug Administration guidelines in terms of: system suitability, calibration range (0.05-5 mg/L), linearity, sensitivity, robustness, carry-over effect, specificity, accuracy (-11.1 to 4.2%), precision (<19.9%), stability and analysis of incurred samples. The method was found reliable, practical, easy-to-conduct, rapid, relatively eco-friendly, safe, inexpensive, widely available and with a high sample throughput. The method was applied to the analysis of incurred samples, including incurred sample reanalysis, to verify that the instrumentation works correctly. In addition, the constants of the different partition equilibria occurring in the column were elucidated in order to have a better comprehension of the theoretical aspects of the retention mechanism. A moderately strong association between rivaroxaban and the stationary phase and the micelles was found, weakened by short chain alcohol.

Direct injection high performance liquid chromatography coupled to data independent acquisition mass spectrometry for the screening of antibiotics in honey

The targeted analysis of veterinary drug residues in honey traditionally involves a series of extraction and purification steps prior to quantification with high performance liquid chromatography coupled to high resolution or tandem mass spectrometry. These steps, designed to separate the target analytes from interferences, are generally time-consuming and costly. In addition, traditional cleanup steps are likely to eliminate other compounds whose analysis could prove decisive in current or future assessment of the honey sample. Alternatively, direct injection without complex sample preparation steps has been introduced for the fast analysis of trace compounds in environmental and food matrices. The aim of this study was to develop a rapid method for the targeted analysis of 7 key veterinary drug residues in honey based on direct injection high performance liquid chromatography coupled to quadrupole time-of-flight, while simultaneously recording data-independent MS/MS (e.g. All Ions MS/MS data) for future re-examination of the data for other purposes. The new method allowed for the detection of the target residues at levels approximately 20-100 times lower than current regulatory limits, for a total analysis time of about 45 min. The recoveries (103-119%), the linearity (R ≥ 0.996) and the repeatability (RSD ≤ 7%) were satisfactory. The method was then applied to 35 honey samples from the Canadian market. Residues of tylosin A, tylosin B, sulfamethazine and sulfadimethoxine were detected in 6, 9, 6 and 23% of the samples respectively, at levels below the regulatory limits in Canada. The possibility of adding a hydrolysis step to study sulfonamides in honey was tested, which provided good results for this family of compounds but lead to degradation of some of the other analytes. Finally, the non-targeted identification of several compounds was demonstrated as a proof of concept of future re-examination of All Ions MS/MS data. This paper illustrates the capacity of this novel method to combine targeted and non-targeted screening of chemical residues in honey.

rAAV-Mediated Gene Delivery to Adipose Tissue

Recombinant adeno-associated virus (rAAV) vectors are attractive vehicles for gene therapy. Yet, it is challenging to genetically manipulate adipose tissue in adults due to the low transduction efficiency of naturally occurring AAV serotypes. We recently demonstrated that a novel engineered hybrid serotype Rec2 achieves high transduction of adipose tissue that is superior to naturally occurring serotypes via direct injection to adipose depots. Furthermore, the administration route influences the tropism and efficacy of Rec2 vector: oral administration transduces interscapular brown fat, while intraperitoneal injection preferentially targets visceral fat. Multiple in vivo studies by our lab and others have demonstrated that Rec2 vector provides a powerful tool to genetically manipulate adipose tissue for basic research and potential gene therapies of genetic and acquired diseases. Here we provide detailed protocols for AAV production and delivery to adipose tissue by direct injection, oral administration, and intraperitoneal injection.

A novel gas sampling introduction interface for fast analysis of volatile organic compounds using radiofrequency pulsed glow discharge time of flight mass spectrometry

An improved gas sample introduction interface is developed and characterized for gas chromatography coupling and for direct injection of volatile organic compounds (VOCs), in a pulsed glow discharge (pulsed-GD) ion source coupled to a time of flight mass spectrometer (TOFMS) that is typically used for direct solid analysis. The novel interface allows the introduction of the analytes in the flowing afterglow region of the GD (a few mm away from the negative glow region) to reduce plasma quenching effects. Analyte ion signals are acquired in the temporal afterglow region, where low fragmentation of the molecular species is produced, providing useful qualitative and quantitative molecular information (e.g. molecular ion). Analytical capabilities of the pulsed-GD ion source with the novel gas sampling interface provides improved performance compared to previous designs. In particular, limits of detection for the analysis of VOCs in air were below (better) that legally established limits according to Directive 2008/50/EC of the European Parliament.

A simple and rapid direct injection method for the determination of glyphosate and AMPA in environmental water samples

Glyphosate is currently the most widely used herbicide in the world, yet screening of environmental waters for this chemical is limited by the need for specialized derivatization and measurement methods that can be tedious and time-consuming. In this work, we present a novel method for the detection and quantification at trace levels of glyphosate and aminomethylphosphonic acid (AMPA) in environmental water samples. The detection and quantification of the analytes was performed by liquid chromatography (LC) coupled with tandem mass spectrometry (MS/MS). Chromatographic separation was achieved with an ion-exchange column and a pH-gradient elution of a solution of ammonium hydroxide and ammonium acetate. The limit of detection for glyphosate and AMPA was 0.25 μg L^-1 and the limit of quantification was 0.5 μg L^-1with a 20-μL injection. The method was used to investigate the levels of glyphosate and AMPA in surface water samples from the Yarra River catchment area and urban constructed stormwater wetlands. The results indicate that at the time of sampling, no glyphosate or AMPA was present in the samples from the Yarra River catchment area (n = 10). However, glyphosate was detected above the limit of quantification in 33% of the wetland samples (n = 12), with concentrations ranging from 1.95 to 2.96 μg L^-1. Similarly, AMPA was quantified in 83% of the wetland samples, with concentrations ranging from 0.55 to 2.42 μg L^-1. To our knowledge, this is the first report of a pH-gradient LC-MS/MS method for glyphosate and AMPA analysis at ultratrace levels, with minimal sample processing, avoiding costly, time-consuming derivatization and preconcentration steps. Graphical abstract ᅟ.

Local strategies and delivery systems for the treatment of malignant gliomas

Glioma is one of the most common type of malignant tumours with high morbidity and mortality rates. Due to the particular features of the brain, such as blood-brain barrier or blood-tumour barrier, therapeutic agents are ineffective by systemic administration. The tumour inevitably recurs and devitalises patients. Herein, an overview of the localised gliomas treatment strategies is provided, including direct intratumoural/intracerebral injection, convection-enhanced delivery, and the implant of biodegradable polymer systems. The advantages and disadvantages of each therapy are discussed. Subsequently, we have reviewed the recent developments of therapeutic delivery systems aimed at transporting sufficient amounts of antineoplastic drugs into the brain tumour sites while minimising the potential side effects. To treat gliomas, localised and controlled delivery of drugs at their desired site of action is preferred as it reduces toxicity and increases treatment efficiency. Simultaneously, various drug delivery systems (DDS) have been used to enhance drug delivery to the brain. Use of non-conventional DDS for localised therapy has greatly expanded the spectrum of drugs available for the treatment of malignant tumours. Use smart DDS via localised delivery strategies, in combination with radiotherapy and multiple drug loading would serve as a promising approach to treat gliomas.

Direct injection analysis of polar micropollutants in natural drinking water sources with biphenyl liquid chromatography coupled to high-resolution time-of-flight mass spectrometry

A method for the trace analysis of polar micropollutants (MPs) by direct injection of surface water and groundwater was validated with ultrahigh-performance liquid chromatography using a core-shell biphenyl stationary phase coupled to time-of-flight high-resolution mass spectrometry. The validation was successfully conducted with 33 polar MPs representative for several classes of emerging contaminants. Identification and quantification were achieved by semi-automated processing of full-scan and data-independent acquisition MS/MS spectra. In most cases good linearity (R² ≥ 0.99), recovery (75% to 125%) and intra-day (RSD < 20%) and inter-day precision (RSD < 10%) values were observed. Detection limits of 9 to 83 ng/L and 9 to 93 ng/L could be achieved in riverbank filtrate and surface water, respectively. A solid-phase extraction was additionally validated to screen samples from full-scale reverse osmosis drinking water treatment at sub-ng/L levels and overall satisfactory analytical performance parameters were observed for RBF and reverse osmosis permeate. Applicability of the direct injection method is shown for surface water and riverbank filtrate samples from an actual drinking water source. Several targets linkable to incomplete removal in wastewater treatment and farming activities were detected and quantified in concentrations between 28 ng/L for saccharine in riverbank filtrate and up to 1 μg/L for acesulfame in surface water. The solid phase extraction method applied to samples from full-scale reverse osmosis drinking water treatment plant led to quantification of 8 targets between 6 and 57 ng/L in the feed water, whereas only diglyme was detected and quantified in reverse osmosis permeate. Our study shows that combining the chromatographic resolution of biphenyl stationary phase with the performance of time-of-flight high-resolution tandem mass spectrometry resulted in a fast, accurate and robust method to monitor polar MPs in source waters by direct injection with high efficiency.

Rapid characterization of chemical markers for discrimination of Moutan Cortex and its processed products by direct injection-based mass spectrometry profiling and metabolomic method

BACKGROUND

Processing of herbal medicines is a characteristic pharmaceutical technique in Traditional Chinese Medicine, which can reduce toxicity and side effect, improve the flavor and efficacy, and even change the pharmacological action entirely. It is significant and crucial to perform a method to find chemical markers for differentiating herbal medicines in different processed degrees.

PURPOSE

The aim of this study was to perform a rapid and reasonable method to discriminate Moutan Cortex and its processed products, and to reveal the characteristics of chemical components depend on chemical markers.

METHODS

Thirty batches of Moutan Cortex and its processed products, including 11 batches of Raw Moutan Cortex (RMC), 9 batches of Moutan Cortex Tostus (MCT) and 10 batches of Moutan Cortex Carbonisatus (MCC), were directly injected in electrospray ionization quadrupole time-of-flight mass spectrometry (ESI-QTOF MS) for rapid analysis in positive and negative mode. Without chromatographic separation, each run was completed within 3 min. The raw MS data were automatically extracted by background deduction and molecular feature (MF) extraction algorithm. In negative mode, a total of 452 MFs were obtained and then pretreated by data filtration and differential analysis. After that, the filtered 85 MFs were treated by principal component analysis (PCA) to reduce the dimensions. Subsequently, a partial least squares discrimination analysis (PLS-DA) model was constructed for differentiation and chemical markers detection of Moutan Cortex in different processed degrees. The positive mode data were treated as same as those in negative mode.

RESULTS

RMC, MCT and MCC were successfully classified. Moreover, 14 and 3 chemical markers from negative and positive mode respectively, were screened by the combination of their relative peak areas and the parameter variable importance in the projection (VIP) values in PLS-DA model. The content changes of these chemical markers were employed in order to illustrate chemical changes of Moutan Cortex after processed.

CONCLUSION

These results showed that the proposed method which combined non-targeted metabolomics analysis with multivariate statistics analysis is reasonable and effective. It could not only be applied to discriminate herbal medicines and their processing products, but also to reveal the characteristics of chemical components during processing.

A non-targeted high-resolution mass spectrometry data analysis of dissolved organic matter in wastewater treatment

The dissolved organic matter (DOM) in wastewater is typically described by a limited number of concentration measurements of select DOM fractions or micro-contaminants, which determine the removal efficiency in a wastewater treatment. Current methods do not necessarily reflect the true performance of the treatment with regard to environmental and public health risk. Herein we describe the development and application of a non-targeted liquid chromatography-high resolution mass spectrometry (LC-HRMS) data analysis for the evaluation of wastewater treatment processes. Our data analysis approach was applied to a real wastewater system with secondary biological treatment and tertiary treatment consisting of sand filtration, UV-treatment, and chlorination. We identified significant changes in DOM during wastewater treatment. The secondary treatment removed 1617 of 2409 (67%) detected molecular features (grouped isotopologues belonging to the same molecule) from the influent while 255 of 1047 (24%) new molecular features appeared in the secondary effluent. A reduction in the number of large molecules (>450 Da) and an increase in unsaturated molecular features of the effluent organic matter was observed. Van Krevelen plots revealed the distribution of unsaturation and heteroatoms and Kendrick mass defect plots uncovered CH₂ homologous series implying a removal of heavy constituents in that fraction. The demonstrated approach is a step towards a more comprehensive monitoring of DOM in wastewater and contributes to the understanding of current treatment technologies.

Development of a method to determine axitinib, lapatinib and afatinib in plasma by micellar liquid chromatography and validation by the European Medicines Agency guidelines

A method based on micellar liquid chromatography to quantify the tyrosine kinase inhibitors axitinib, lapatinib and afatinib in plasma is reported. The sample pretreatment was a simple 1/5-dilution in a pure micellar solution, filtration and direct injection, without requiring extraction or purification steps. The three drugs were resolved from the matrix in 17min, using an aqueous solution of 0.07M sodium dodecyl sulfate - 6.0% 1-pentanol, buffered at pH7 with 0.01M phosphate salt as mobile phase, running under isocratic mode at 1mL/min through a C18 column. The detection was performed by absorbance at 260nm. An accurate mathematical relationship was established between the retention factor of each drug and the surfactant/organic solvent concentration in the mobile phase, achieved with a limited number of experiments, in order to optimize these factors. A binding behavior of the analytes face to the micelles was found out. The method was successfully validated by the guidelines of the European Medicines Agency in terms of: selectivity, linearity (r²>0.9995), calibration range (0.5 to 10mg/L), limit of detection (0.2mg/L), carry-over effect, accuracy (-8.1 to +6.9%), precision (<13.8%), dilution integrity, matrix effect, stability and robustness. The procedure was found reliable, practical, economic, accessible, short-time, easy-to-handle, inexpensive, environmental-friendly, safe, useful for the analysis of many samples per day. Finally, the method was applied to the analysis of incurred, using quality control samples in the same analytical run, with adequate results. Therefore, it can be implementable for routine analysis in clinical laboratories.

Determination of genotoxic epoxide at trace level in drug substance by direct injection GC/MS

A novel direct injection gas chromatography method coupled with selective ion monitoring mass spectrometry (GC/SIM-MS) was developed for quantitation of trace levels of high boiling point (HBP) epoxide genotoxic impurity (GTI) in drug substance. The injector temperature was optimized with the aims to minimize matrix effects and enhance SIM signal response. The final injector temperature 160°C was selected after balancing between these two factors. The column screening was conducted as well and MN OPTIMA delta-3 silica capillary column was selected since it showed good peak symmetry without column bleeding. The good linearity was established for the concentration in the range from 0.0045μg/mL to 0.5μg/mL with a R²=0.9999. The limit of detection (LOD) and the limit of quantitation (LOQ) were 0.0014μg/mL and 0.0045μg/mL, respectively. The recovery which ranged from 95.0% to 112.5% could meet the ICH acceptance criteria. The validation results demonstrated the good linearity, precision and accuracy of the method which can be further adopted as an adequate quality control tool for quantitation of epoxide impurity at trace levels in drug substance and drug product.

Quantification of more than 150 micropollutants including transformation products in aqueous samples by liquid chromatography-tandem mass spectrometry using scheduled multiple reaction monitoring

A direct injection, multi residue analytical method separated in two chromatographic runs was developed utilizing scheduled analysis to simultaneously quantify 154 compounds, 84 precursors and 70 transformation products (TPs)/metabolites. Improvements in the chromatographic data quality, sensitivity and reproducibility were achieved by scheduling the analysis of each analyte into pre-determined retention time windows. This study shows the influence of the scan time on the dwell time and the number of data points per peak as well as the effect on the precision of analysis. Lowering the scan time decreased dwell time to a minimal value, however, this had no negative effects on the precision. Increasing the number of data points per peak by decreasing the scan time led to more accurate peak shapes. A final set of parameters was chosen to obtain a minimum of 10 data points per peak to guarantee accurate peak shapes and thus reproducibility of analysis. A validation of the method was performed for different water matrices yielding very good linearity for all substances, with limits of quantification mainly in the lower to mid ng/L-range and recoveries mainly between 70 and 125% for surface water, bank filtrate as well as influents and effluents of wastewater treatment plants. The analysis of environmental samples and wastewater revealed the occurrence of selected precursors and TPs in all analyzed matrices: 95% of the compounds in the target list could be quantified in at least one sample. The relevance of TPs and metabolites such as valsartan acid and clopidogrel acid was also confirmed by their detection in all aqueous matrices. Wastewater indicators such as acesulfame and diclofenac were detected at elevated concentrations as well as substances such as oxipurinol which so far were not in the focus of monitoring programs. The developed method can be used for rapid analysis of various water matrices without any sample enrichment and can aid the assessment of water quality and water treatment processes.

Fast determination of pesticides and other contaminants of emerging concern in treated wastewater using direct injection coupled to highly sensitive ultra-high performance liquid chromatography-tandem mass spectrometry

It is well known that wastewater treatment plant (WWTP) effluents usually contain micropollutants such as pharmaceuticals (or their transformation products, TPs) or pesticides, which is a major issue when evaluating their possible reuse (e.g. for irrigation in agriculture). In search for an improved accuracy and simplicity, methods based on the direct injection of the sample (DI) represent a recent trend taking advantage of the increasing sensitivity of new mass spectrometry (MS) instruments. Thus, the present study shows the development and validation of a DI-based method by ultra-high-performance liquid chromatography quadrupole-linear ion trap analyser (UHPLC-QqLIT-MS/MS). The proposed method was applied to the monitoring of 115 organic microcontaminants (including pharmaceuticals, TPs and pesticides) at the ngL^-1/μgL^-1 level in wastewater effluents from urban WWTPs. Sample pre-treatment was reduced to acetonitrile addition and filtration of the mixture previous to LC-MS analysis. Total analysis time was <15min. A subsequent validation protocol was carried out in treated WW (TWW), following indications of SANTE and Eurachem Guidelines. Linearity and matrix effect were evaluated in the range of 10-1000ngL^-1. 70% of the analytes showed a moderate matrix effect (≤25%). Trueness (expressed as recovery) and precision (calculated as relative standard deviation, RSD) were evaluated at four concentration levels (20, 50, 500 and 1000ngL^-1) in TWW samples. The LODs ranged from 1 to 357ngL^-1 and the LOQs from 10 to 500ngL^-1. 92% of the compounds showed limits of quantification ≤100ngL^-1. In most cases, mean recoveries were in the range 70-120%, and RSD values were ≤20%. The validated method was successfully applied to the analysis of 10 TWW samples, demonstrating the occurrence of 67 target compounds at concentration levels from 26705ngL^-1 (4-aminoantipyrine) to 10ngL^-1 (tebuconazole and bezafibrate).

Metabolomic Analysis of Campylobacter jejuni by Direct-Injection Electrospray Ionization Mass Spectrometry

Direct-injection mass spectrometry (DIMS) is a means of rapidly obtaining metabolomic phenotype data in both prokaryotes and eukaryotes. Given our generally poor understanding of Campylobacter metabolism, the high-throughput and relatively simple sample preparation of DIMS has made this an attractive technique for metabolism-related studies and hypothesis generation, especially when attempting to analyze metabolic mutants with no clear phenotype. Here we describe a metabolomic fingerprinting approach with sampling and extraction methodologies optimized for direct-injection electrospray ionization mass spectrometry (ESI-MS), which we have used as a means of comparing wild-type and isogenic mutant strains of C. jejuni with various metabolic blocks.

Non-invasive real time monitoring of yeast volatilome by PTR-ToF-MS

INTRODUCTION

Producing a wide range of volatile secondary metabolites Saccharomyces cerevisiae influences wine, beer, and bread sensory quality and hence selection of strains based on their volatilome becomes pivotal. A rapid on-line method for volatilome assessing of strains growing on standard solid media is still missing.

OBJECTIVES

Methodologically, the aim of this study was to demonstrate the automatic, real-time, direct, and non-invasive monitoring of yeast volatilome in order to rapidly produce a robust large data set encompassing measurements relative to many strains, replicates and time points. The fundamental scope was to differentiate volatilomes of genetically similar strains of oenological relevance during the whole growing process.

METHOD

Six different S. cerevisiae strains (four meiotic segregants of a natural strain and two laboratory strains) inoculated onto a solid medium have been monitored on-line by Proton Transfer Reaction-Time-of-Flight-Mass Spectrometry for 11 days every 4 h (3540 time points). FastGC PTR-ToF-MS was performed during the stationary phase on the 5th day.

RESULTS

More than 300 peaks have been extracted from the average spectra associated to each time point, 70 have been tentatively identified. Univariate and multivariate analyses have been performed on the data matrix (3640 measurements × 70 peaks) highlighting the volatilome evolution and strain-specific features. Laboratory strains with opposite mating type, and meiotic segregants of the same natural strain showed significantly different profiles.

CONCLUSIONS

The described set-up allows the on-line high-throughput screening of yeast volatilome of S. cerevisiae strains and the identification of strain specific features and new metabolic pathways, discriminating also genetically similar strains, thus revealing a novel method for strain phenotyping, identification, and quality control.

A Review of Stem Cell Therapy for Spinal Cord Injury: Large Animal Models and the Frontier in Humans

OBJECTIVE

To review the literature of spinal cord injury and stem cell therapy for large animal models and incorporate those results into an understanding of stem cell therapy for human cord injury.

METHODS

Review of the literature.

RESULTS

Eleven canine studies were identified and 3 sub-human primate studies were identified showing variable results.

CONCLUSIONS

Stem cell therapy is a promising therapeutic option for patients with spinal cord injury; however, the technology has many un-answered questions and further research is needed.

Direct injection of HILIC fractions on the reversed-phase trap column improves protein identification rates for salivary proteins

Online combination of hydrophilic interaction chromatography (HILIC) and RP chromatography for separation of tryptic peptides is a challenging approach due to the incompatibility of direct loading HILIC fractions on the RP trapping column. High amounts of organic modifiers in loading solvents decrease the binding efficiency of tryptic peptides on C18 phases and lower the number of identifications. A 500 μL loop upfront of the trapping column filled with aqueous mobile phase was employed as a mixing chamber and enabled direct injections and improved saliva protein identification rates of HILIC fractions.

Use of micellar liquid chromatography for rapid monitoring of fungicides post harvest applied to citrus wastewater

A method based on micellar liquid chromatography has been developed to simultaneously monitor four pesticides largely post-harvest applied to citrus: thiabendazole, pyrimethanil, o-phenylphenol and imazalil. Water samples were filtered and directly injected without other treatment, thus avoiding extraction steps. The composition of the mobile phase was optimized using a chemometrical approach to achieve and excellent resolution to 0.07 mol/L SDS/5%, V/V 1-pentanol buffered at pH3. Mobile phase run through a C18 column at 1 mL/min at room temperature. The detection was performing by UV-Visible absorbance using a wavelength program: 0-10 min, 305 nm (for thiabendazole); 10-12; 265 nm (for pyrimethanil) and 12-18, 220 nm (o-phenylphenol and imazalil). The developed method was validated following the guidelines of the US Environmental Protection Agency in terms of: quantitation range, (0.5-4 to 15 μg/mL), linearity (r(2)>0.9995), sensitivity (LOD, 0.18-1.4 μg/mL), precision (<9.2%), trueness (93.9%-103.7%), and ruggedness (<9.9%). It was found that the fungicides remain up to eight days in surface water at outdoor conditions. The method was used to screen the presence of the analytes in several waste water samples, and was proved to be useful in routine analysis.

Gene Therapy of the Peripheral Nervous System: Celiac Ganglia

Gene therapy has played an integral role in advancing our understanding of the central nervous system. However, gene therapy techniques have yet to be widely utilized in the peripheral nervous system. Critical targets for gene therapy within the PNS are the neurons in sympathetic ganglia, which are the final pathway to end organs. Thus they are the most specific targets for organ-specific neuron modification. This presents challenges because neurons are not viscerotopically organized within the ganglia and therefore cannot be targeted by their location. However, organ-specific neurons have been identified in sympathetic ganglia of some species and this offers an opportunity for targeting and transducing neurons by way of their target. In fact, alterations in sympathetic neurons have had pathological effects, and transducing organ-specific sympathetic neurons offer an exciting opportunity to selectively modify sympathetic pathology. In this chapter, we describe a method to virally transduce the celiac ganglion (CG), a prevertebral sympathetic ganglion that innervates abdominal organs, with AAV serotypes 1 and 6; thereby, providing a potential avenue to modulate specific subsets of neurons within the celiac ganglion.

Effect of the direct injection of bone marrow mesenchymal stem cells in hyaluronic acid and bone marrow stimulation to treat chondral defects in the canine model

Introduction

The purpose of this study was to assess the direct injection of bone marrow-derived mesenchymal stem cells (BMSCs) suspended in hyaluronic acid (HA) combined with drilling as a treatment for chondral defects in a canine model.

Methods

Tibial bone marrow was aspirated, and BMSCs were isolated and cultured. One 8.0-mm diameter chondral defect was created in the femoral groove, and nine 0.9-mm diameter holes were drilled into the defect. BMSCs (2.14 × 10⁷ cells) suspended in HA were injected into the defect. HA alone was injected into a similar defect on the contralateral knee as a control. Animals were sacrificed at 3 and 6 months.

Results

Although the percentage of coverage assessed macroscopically was significantly better at 6 months than at 3 months in both the BMSC (p = 0.02) and control (p = 0.001) groups, there were no significant differences in the International Cartilage Repair Society grades. The Wakitani histological score was significantly better at 6 months than at 3 months in the BMSC and control groups. While the control defects were mostly filled with fibrocartilage, several of the defects in the BMSC group contained hyaline-like cartilage. The mean Wakitani scores of the BMSC group improved from 7.0 ± 1.0 at 3 months to 4.6 ± 0.9 at 6 months, and those of the control group improved from 9.4 ± 1.2 to 6.0 ± 0.6. The BMSC group showed significantly better regeneration than the control group at 3 months (p = 0.04), but the difference at 6 months was not significant (p = 0.06).

Conclusions

The direct injection of BMSCs in HA combined with drilling enhanced cartilage regeneration.

Development and validation of a generic nontarget method based on liquid chromatography - high resolution mass spectrometry analysis for the evaluation of different wastewater treatment options

A comprehensive workflow for using nontarget approaches as process evaluation tools was implemented, including data acquisition based on a LC-HRMS (QTOF) system using direct injection and data post-processing for the peak recognition in "full scan" data. Both parts of the approach were not only developed and validated in a conventional way using the suspected analysis of a set of spiked known micropollutants but also the nontarget analysis of a wastewater treatment plant (WWTP) effluent itself was utilized to consider a more environmental relevant range of analytes. Hereby, special focus was laid on the minimization of false positive results (FPs) during the peak recognition. The optimized data post-processing procedure reduced the percentage of FPs from 42% to 10-15%. Furthermore, the choice of a suitable chromatography for biological treated wastewater systems was also discussed during the method development. The workflow paid also attention to differences in the performance levels of the LC-HRMS system by implementation of an adaption system for intensity variations comparing different measurements dates or different instruments. The application of this workflow on wastewater samples from a municipal WWTP revealed that more than 91% compounds were eliminated by the biological treatment step and that the received effluent contained 55% newly formed potential transformation products.

Direct electrokinetic injection of inorganic cations from whole fruits and vegetables for capillary electrophoresis analysis

A novel approach for the direct injection from plant tissues without any sample pre-treatment has been developed by simply placing a small piece of the tissue into a capillary electrophoresis vial followed by application of a voltage for electrokinetic injection. Separations of sodium, potassium, calcium and magnesium were achieved using a BGE comprising 10mM imidazole and 2.5mM 18-crown-6-ether at pH 4.5. The addition of 2% (m/v) hydroxypropylmethyl cellulose to the separation buffer allowed for precise and accurate electrokinetic injection of ions from the plant material by halting the movement of tissue fluid into the capillary. This method provides both qualitative and quantitative data of inorganic cations, with quantitation in zucchini, mushroom and apple samples in agreement with Sector Field Inductively Coupled Plasma Mass Spectrometric analysis (r(2)=0.98, n=9). This method provides a new way for rapid, quantitative analysis by eliminating sample preparation procedures, and has great potential for a range of applications in plant science and food chemistry.

Characterization of Pharmaceuticals and Personal Care products in hospital effluent and waste water influent/effluent by direct-injection LC-MS-MS

Two USEPA Regional Laboratories developed direct-injection LC/MS/MS methods to measure Pharmaceuticals and Personal Care Products (PPCPs) in water matrices. Combined, the laboratories were prepared to analyze 185 PPCPs (with 74 overlapping) belonging to more than 20 therapeutical categories with reporting limits at low part-per-trillion. In partnership with Suffolk County in NY, the laboratories conducted PPCP analysis on 72 samples belonging to 4 Water Systems (WS). Samples were collected at different stages of the WS (hospital effluents, WWTP influents/effluents) to assess PPCP relevance in hospital discharges, impact on WWTP performance and potential ecological risk posed by analytes not eliminated during treatment. Major findings include: a) acceptable accuracy between the two laboratories for most overlapping PPCPs with better agreement for higher concentrations; b) the measurement of PPCPs throughout all investigated WS with total PPCP concentrations ranging between 324 and 965 μg L(-1) for hospital effluent, 259 and 573 μg L(-1) for WWTP influent and 19 and 118 μg L(-1) for WWTP effluent; c) the variable contribution of hospital effluents to the PPCP loads into the WWTP influents (contribution ranging between 1% (WS-2) and 59% (WS-3); d) the PPCP load reduction after treatment for all WS reaching more than 95% for WS using activated sludge processes (WS-2 and WS-4), with inflow above 6500 m(3) d(-1), and having a lower percentage of hospital effluent in the WWTP influent; e) the relevance of four therapeutical categories for the PPCP load in WWTP effluents (analgesics, antidiabetics, antiepileptics and psychoanaleptics); and f) the risk quotients calculated using screening-level Predicted Non Effect Concentration indicate that WWTP effluents contain 33 PPCPs with potential medium to high ecological risk. To our knowledge no other monitoring investigation published in the scientific literature uses direct-injection methods to cover as many PPCPs and therapeutical categories in different types of WS.

Applying a new method for direct collection, volume quantification and determination of N2 emission from water

The emission of N2 is important to remove excess N from lakes, ponds, and wetlands. To investigate the gas emission from water, Gao et al. (2013) developed a new method using a bubble trap device to collect gas samples from waters. However, the determination accuracy of sampling volume and gas component concentration was still debatable. In this study, the method was optimized for in situ sampling, accurate volume measurement and direct injection to a gas chromatograph for the analysis of N2 and other gases. By the optimized new method, the recovery rate for N2 was 100.28% on average; the mean coefficient of determination (R(2)) was 0.9997; the limit of detection was 0.02%. We further assessed the effects of the new method, bottle full of water, vs. vacuum bag and vacuum vial methods, on variations of N2 concentration as influenced by sample storage times of 1, 2, 3, 5, and 7 days at constant temperature of 15°C, using indices of averaged relative peak area (%) in comparison with the averaged relative peak area of each method at 0 day. The indices of the bottle full of water method were the lowest (99.5%-108.5%) compared to the indices of vacuum bag and vacuum vial methods (119%-217%). Meanwhile, the gas chromatograph determination of other gas components (O2, CH4, and N2O) was also accurate. The new method was an alternative way to investigate N2 released from various kinds of aquatic ecosystems.

Determination of amphetamine and methadone in human urine by microextraction by packed sorbent coupled directly to mass spectrometry: an alternative for rapid clinical and forensic analysis

Speed and low cost, together with regulatory approval, are the most important requirements of clinical assays. Therefore, a fast and automated on-line sample preparation method is essential for the routine analysis of biological samples. Microextraction by packed sorbent is an option for optimal sample preparation due to its easy automation, minimal requirements for the sample and elution solvent volumes, elimination of evaporation and reconstitution steps, and ability to integrate sample preparation and injection into one step. The use of effective sample preparation steps circumvents the need for chromatographic separation and therefore allows more rapid and less expensive sample analysis in clinical and forensic practice. Two biologically active compounds, amphetamine and methadone, were chosen as representative drugs of abuse for the application of microextraction by packed sorbent coupled directly to mass spectrometry. The developed method was validated, with the results confirming the suitability of the combination of these techniques for the analysis of biological samples. The approach was confirmed to be appropriate for use in clinical and forensic practice with regard to cost and time requirements for analysis.

Direct in vivo injection of 131I-GMS and its distribution and excretion in rabbit

AIM: To explore the distribution and metabolism of ¹³¹I-gelatin microspheres (¹³¹I-GMSs) in rabbits after direct injection into rabbits’ livers.

METHODS: Twenty-eight healthy New Zealand rabbits were divided into seven groups, with four rabbits per group. Each rabbit’s hepatic lobes were directly injected with 41.336 ± 5.106 MBq ¹³¹I-GMSs. Each day after ¹³¹I-GMSs administration, 4 rabbits were randomly selected, and 250 μL of serum was collected for γ count. Hepatic and thyroid functions were tested on days 1, 4, 8, 16, 24, 32, 48 and 64 after ¹³¹I-GMSs administration. Single-photon emission computed tomography (SPECT) was taken for each group on days 0, 1, 4, 8, 16, 24, 32, 48, 64 after ¹³¹I-GMSs administration. A group of rabbits were sacrificed respectively on days 1, 4, 16, 24, 32, 48, 64 after ¹³¹I-GMSs administration. Their livers were taken out for histological examination.

RESULTS: After ¹³¹I-GMSs administration, the nuclide was collected in the hepatic area with microspheres. The radiation could be detected on day 48 after ¹³¹I-GMSs administration, and radiography could be seen in thyroid areas in SPECT on days 4, 8, 16 and 24. One day after ¹³¹I-GMSs administration, the liver function was damaged but recovered 4 d later. Eight days after ¹³¹I-GMSs administration, the levels of free triiodothyronine and free thyroxin were reduced, which restored to normal levels on day 16. Histological examination showed that the microspheres were degraded to different degrees at 24, 32 and 48 d after ¹³¹I-GMSs administration. The surrounding parts of injection points were in fibrous sheathing. No microspheres were detected in histological examination on day 64 after ¹³¹I-GMSs administration.

CONCLUSION: Direct in vivo injection of ¹³¹I-GMSs is safe in rabbits. It may be a promising method for treatment of malignant tumors.