Syncope without prodromes is associated with excessive plasma release of adenosine at the time of syncope during head-up tilt table test.

Background: In syncopal patients without underlying structural disease, we sought to investigate the association of Adenosine Plasma Levels (ADP) with the clinical presentation of neurally mediated syncope (NMS) and the outcomes of Head-Up Tilt Table Test (HUTT) and Adenosine test (ADT).

Methods: We studied 124 patients with different clinical types of NMS, i.e.

Application of a hybrid zwitterionic hydrophilic interaction liquid chromatography column in metabolic profiling studies.

Metabolic phenotyping studies using mouse liver extracts as a model, performed on a novel zwitterionic HILIC UHPLC column, which is based on ethylene-bridged hybrid organic/inorganic particles bonded with sulfobetaine groups and packed into column hardware modified with hybrid surface technology are reported. Initially the chromatographic performance was evaluated under different mobile phase conditions using selected metabolite standards. Following optimization of the chromatographic conditions for 88 hydrophilic metabolites both targeted and untargeted profiling analyses were performed on tissue extracts using LC-MS/MS and LC-TOF/MS, respectively.

Detection and determination of C12-, C14-, C16-alkyldimethylamines in human blood using gas chromatography-mass spectrometry.

Rationale: N,N-Dimethyldodecylamine is produced from lauryl alcohol and dimethylamine. C12-C16 alkyldimethylamines are used as intermediates for the manufacture of amineoxides and quaternary amino compounds. In the present study a gas chromatography-mass spectrometry (GC/MS) method for the determination of C12-C16 alkyldimethylamines in blood was developed and validated.

Headspace gas chromatography-mass spectrometry in the analysis of lavender's essential oil: Optimization by response surface methodology.

A static headspace gas chromatography - mass spectrometry (HS-GC/MS) method was developed and optimized with the aim to be applied in the analysis of lavender essential oil. To obtain a comprehensive profile of the essential oil, the optimum HS-GC/MS method parameters were selected based on a Design of Experiments (DοE) process. Plackett-Burman experimental design was applied by utilizing seven parameters of the HS injection system.

Liquid chromatography tandem mass spectrometry for the determination of nine insecticides and fungicides in human postmortem blood and urine.

Pesticide poisoning is a common occurrence due to their widespread use, easy access and high toxicity even in small concentrations. The most common poisoning fatalities have been observed due to exposure to organophosphates, carbamates and neonicotinoids, thus development of a method for the rapid determination of these compounds in blood and urine is of great importance for clinical and toxicology laboratories. A simple, fast and reliable method was developed for the determination of 9 pesticides in blood and urine using HPLC-MS/MS instrumentation.

Development and validation of a RPLC-MS/MS method for the quantification of ceramides in human serum.

Ceramides are key-role lipids involved in numerous central cellular processes. A plethora of studies have demonstrated that the levels of ceramides in blood circulation are related to different disease states, such as type 2 diabetes, cardiovascular diseases, ovarian cancer, multiple sclerosis and others. Herein, a RPLC-MS/MS method for the rapid quantification of ceramides Cer(d18:1/16:0), Cer(d18:1/18:0), Cer(d18:1/24:0) and Cer(d18:1/24:1) in human blood serum was developed and validated.

Quantification of endogenous aminoacids and aminoacid derivatives in urine by hydrophilic interaction liquid chromatography tandem mass spectrometry.

Aminoacids and their derivatives are key biologically important metabolites and reliable, rapid and accurate, quantification for these analytes in urine remains an important analytical challenge. Here a fast and reliable HILIC-tandem MS method is presented for application in clinical or nutritional studies. The developed method was validated according to existing guidelines adapted for endogenous analytes.

GC-MS analysis of underivatised new psychoactive substances in whole blood and urine.

Herein a method was develop and validated for the detection and quantification of five new psychoactive substances (NPS) belonging to three categories: synthetic cathinones (mephedrone, 3,4-MDPV), opioids (AH-7921) and cannabinoids (JWH-018, AM-2201) by EI GC-MS. Target analytes were quantified in whole blood; in urine the same compounds plus methylone were detected. Liquid-liquid extraction by MTBE - butyl acetate (1:1, v/v) in blood and butyl acetate in urine was applied for the recovery of analytes, while no derivatization was necessary for their sensitive detection and quantification.

Metabolic Phenotyping Study of Mouse Brains Following Acute or Chronic Exposures to Ethanol.

The chronic and acute effect of ethanol administration on the metabolic phenotype of mouse brain was studied in a C57BL/6 mouse model of ethanol abuse using both untargeted and targeted ultra performance liquid chromatography-tandem mass spectrometry. Two experiments based on either chronic (8 week) exposure to ethanol of both male and female mice or acute exposure of male mice for 11 days, plus 2 oral gavage doses of 25% ethanol, were undertaken. Marked differences were found in amino acids, nucleotides, nucleosides, and related metabolites as well as a number of different lipids.

Risk factors for fatal drowning in a Greek region: a retrospective case-control study.

Background: Fatal drowning is one of the leading causes of unintentional injury mortality worldwide and a persistent public health concern in Greece. While several pathologic and sociodemographic contributing factors have been previously identified, these have not been extensively investigated in conjunction with the effects of psychoactive substances.

Methods: A retrospective case-control study of drowning deaths was conducted in the Greek regions of Northern Greece and Thessaly during a 10-year period.

A UHPLC-MS-MS Method for the Determination of 84 Drugs of Abuse and Pharmaceuticals in Blood.

The analysis of blood samples for forensic or clinical intoxication cases is a daily routine in an analytical laboratory. The list of 'suspect' drugs of abuse and pharmaceuticals that should be ideally screened is large, so multi-targeted methods for comprehensive detection and quantification are a useful tool in the hands of a toxicologist. In this study, the development of an ultra-high performance liquid chromatography (LC)-tandem mass spectrometry (MS-MS) method is described for the detection and quantification of 84 drugs and pharmaceuticals in postmortem blood.

Study of Fecal and Urinary Metabolite Perturbations Induced by Chronic Ethanol Treatment in Mice by UHPLC-MS/MS Targeted Profiling.

Alcoholic liver disease (ALD) as a consequence of ethanol chronic consumption could lead to hepatic cirrhosis that is linked to high morbidity and mortality. Disease diagnosis is still very challenging and usually clear findings are obtained in the later stage of ALD. The profound effect of ethanol on metabolism can be depicted using metabolomics; thus, the discovery of novel biomarkers could shed light on the initiation and the progression of the ALD, serving diagnostic purposes.

Rat Fecal Metabolomics-Based Analysis.

Fecal metabolomics-based analysis indisputably constitutes a very useful tool for elucidating the biochemistry of digestion and absorption of the gastrointestinal system. Fecal samples represent the most suitable, non-invasive, specimen for the study of the symbiotic relationship between the host and the intestinal microbiota.It is well established that the balance of the intestinal microbiota changes in response to some stimuli, physiological such as gender, age, diet, exercise and pathological such as gastrointestinal and hepatic disease.

HILIC-MS/MS Multi-Targeted Method for Metabolomics Applications.

Metabolomics aims at the identification and quantification of key-end point metabolites, basically polar, in order to study changes in biochemical activities in response to pathophysiological stimuli or genetic modifications. Targeted profiling assays have enjoyed a growing popularity during the last years with LC-MS/MS as a powerful tool for development of such (semi-) quantitative methods for a large number of metabolites. Here we describe a method for absolute quantification of ca.

Quality Control and Validation Issues in LC-MS Metabolomics.

Global metabolic profiling (untargeted metabolomics) of different and complex biological matrices aims to implement an holistic, hypothesis-free analysis of (potentially) all the metabolites present in the analyzed sample. However, such an approach, although it has been the focus of great interest over the past few years, still faces many limitations and challenges, particularly with regard to the validation and the quality of the obtained results. The present protocol describes a quality control (QC) procedure for monitoring the precision of the analytical process involving untargeted metabolic phenotyping of urine and plasma/serum.

Metabolic Profiling: Status, Challenges, and Perspective.

Metabolic profiling has advanced greatly in the past decade and evolved from the status of a research topic of a small number of highly specialized laboratories to the status of a major field applied by several hundreds of laboratories, numerous national centers, and core facilities. The present chapter provides our view on the status of the remaining challenges and a perspective of this fascinating research area.

Sample Preparation Strategies for the Effective Quantitation of Hydrophilic Metabolites in Serum by Multi-Targeted HILIC-MS/MS.

The effect of endogenous interferences of serum in multi-targeted metabolite profiling HILIC-MS/MS analysis was investigated by studying different sample preparation procedures. A modified QuEChERS dispersive SPE protocol, a HybridSPE protocol, and a combination of liquid extraction with protein precipitation were compared to a simple protein precipitation. Evaluation of extraction efficiency and sample clean-up was performed for all methods.

Impact of Exercise and Aging on Rat Urine and Blood Metabolome. An LC-MS Based Metabolomics Longitudinal Study.

Aging is an inevitable condition leading to health deterioration and death. Regular physical exercise can moderate the metabolic phenotype changes of aging. However, only a small number of metabolomics-based studies provide data on the effect of exercise along with aging.

QSRR Modeling for Metabolite Standards Analyzed by Two Different Chromatographic Columns Using Multiple Linear Regression.

Modified quantitative structure retention relationships (QSRRs) are proposed and applied to describe two retention data sets: A set of 94 metabolites studied by a hydrophilic interaction chromatography system under organic content gradient conditions and a set of tryptophan and its major metabolites analyzed by a reversed-phase chromatographic system under isocratic as well as pH and/or simultaneous pH and organic content gradient conditions. According to the proposed modification, an additional descriptor is added to a conventional QSRR expression, which is the analyte retention time, tR(R), measured under the same elution conditions, but in a second chromatographic column considered as a reference one. The 94 metabolites were studied on an Amide column using a Bare Silica column as a reference.

Amniotic Fluid and Maternal Serum Metabolic Signatures in the Second Trimester Associated with Preterm Delivery.

Preterm delivery (PTD) represents a major health problem that occurs in 1 in 10 births. The hypothesis of the present study was that the metabolic profile of different biological fluids, obtained from pregnant women during the second trimester of gestation, could allow useful correlations with pregnancy outcome. Holistic and targeted metabolomics approaches were applied for the complementary assessment of the metabolic content of prospectively collected amniotic fluid (AF) and paired maternal blood serum samples from 35 women who delivered preterm (between 29 weeks + 0 days and 36 weeks +5 days gestation) and 35 women delivered at term.

Analytical Methodologies for the Assessment of Phthalate Exposure in Humans.

Screening and quantification of phthalate metabolites in biological matrices provide information on the phthalate exposure. The preferred tool for the determination of phthalate metabolites is liquid chromatography-mass spectrometry, typically preceded by a sample extraction step. Method development for the determination of phthalate metabolites by hyphenated techniques faces challenges due to the widespread occurrence of phthalates in the laboratory and sample collection materials that impairs their accurate quantification.

Investigation of the derivatization conditions for GC-MS metabolomics of biological samples.

Aim: Metabolomics applications represent an emerging field where significant efforts are directed. Derivatization consists prerequisite for GC-MS metabolomics analysis.

Methods: Common silylation agents were tested for the derivatization of blood plasma.

Sample preparation optimization in fecal metabolic profiling.

Metabolomic analysis of feces can provide useful insight on the metabolic status, the health/disease state of the human/animal and the symbiosis with the gut microbiome. As a result, recently there is increased interest on the application of holistic analysis of feces for biomarker discovery. For metabolomics applications, the sample preparation process used prior to the analysis of fecal samples is of high importance, as it greatly affects the obtained metabolic profile, especially since feces, as matrix are diversifying in their physicochemical characteristics and molecular content.

A hydrophilic interaction chromatography-tandem mass spectrometry method for amino acid profiling in mussels.

A UHPLC-HILIC-tandem MS method has been developed and validated for the quantification of 21 amino acids (20 protein amino acids and cystine) in their free form (FAA) and as protein constituents (total amino acids, TAA) in a rich protein food matrix such as lyophilized mussels (Mytilus galloprovincialis) samples. FAA were analyzed after suspending the samples in the presence of trichloroacetic acid in order to prevent dissolving the proteins, while TAA were determined after acid hydrolysis with 6M HCl in the presence of 4% v/v thioglycolic acid as a reducing agent. In hydrolysed samples 17 amino acids could be determined since tryptophan, cysteine, cystine and asparagine were degraded during acid hydrolysis.