Utilizing Liquid Chromatography Tandem Mass Research Articles

Evaluating a novel method for vitamin A analysis in an observational study of the UAE's obese population

Vitamin A plays a critical role in various biological functions, including vision, cellular differentiation, and immune regulation. However, accurately assessing its status, particularly in obese individuals, presents challenges due to potential alterations in metabolism and distribution. This study utilized Liquid Chromatography–Tandem Mass Spectrometry (LC–MS/MS) methodology to precisely measure serum vitamin A concentrations in population of UAE. The methodology's reliability and precision, as demonstrated through validation procedures, underscore its potential utility in clinical settings. Employing the Multiple Reaction Monitoring mode of positive ion electrospray ionization, the LC–MS/MS system achieves a limit of detection (LOD) of 0.48 ng/mL in serum, while adhering to FDA-US regulations for accuracy and compliance. A key aspect of this study was the application of LC–MS/MS to assess vitamin A status in an obese population within UAE. By employing a diverse cohort of 452 Emirati participants, including 277 individuals from a randomized controlled trial who were assessed at baseline and at 6th month, and 175 healthy individuals aged 18–82 assessed at baseline, this study explores the relationship between obesity and vitamin A levels, shedding light on potential implications for health and well-being. It was an observational study based on a new vitamin A method and participants were asked to eat vitamin A rich foods. The robust performance of the LC–MS/MS methodology positions it as a valuable tool for clinical research. By accurately quantifying vitamin A levels in human serum, this methodology opens avenues for advancing our understanding of vitamin A physiology and its implications for health, particularly in obese populations. In summary, this LC–MS/MS methodology presents a potent tool for clinical studies, providing reliable, specific, and robust detection of vitamin A in human serum, thus, opening a new frontier for advancing our understanding of vitamin A related physiology and health in the obese population.

Bio-synthesis, purification and structural analysis of Cyclosporine-A produced by Tolypocladium inflatum with valorization of agro-industrial wastes

Cyclosporine A (CyA) holds significant importance as a strategic immunosuppressive drug for organ transplant patients. In this study, we aimed to produce pure and cost-effective Cyclosporine A (CyA) by fermenting a culture medium containing dairy sludge, using Tolypocladium inflatum PTCC 5253. Following the fermentation stage, ethyl acetate extraction and fast protein liquid chromatography were employed for sample purification. The initial evaluation of the effectiveness of CyA obtained from these processes was performed through bioassay, wherein the antimicrobial clear zone diameter was found to be larger compared to the sample obtained from the fermentation culture. The concentration of CyA was determined using high-performance liquid chromatography, yielding values of 334 mg/L, 456 mg/L, and 578 mg/L for the fermented, extracted, and purified samples, respectively. Further analysis utilizing liquid chromatography tandem mass spectrometry (LC/MS/MS) confirmed a purity of 91.9% and proper agreement with the standard sample based on the ion intensity of Z/m 1205. To validate the structure of CyA, nuclear magnetic resonance spectroscopy, Fourier-transform infrared (FT-IR), and Raman spectroscopy were employed. X-ray diffraction and differential scanning calorimetry analyses demonstrated that the purified CyA exhibited a crystal structure similar to the standard sample, characterized by two broad peaks at 2θ = 9° and 20°, and comparable glass transition temperatures (57–68 °C for the purified sample; 53–64 °C for the standard sample). Dynamic light scattering analysis confirmed a uniform particle size distribution in both the purified and standard samples. The zeta potentials of the purified and standard samples were determined to be − 25.8 ± 0.16 and − 23.63 ± 0.12 mV, respectively. Our results demonstrate that dairy sludge can serve as a suitable culture medium for the production of (CyA).

A quantitative LC-MS/MS analysis of Xylazine, p-Fluorofentanyl, Fentanyl and Fentanyl-Related compounds in postmortem blood

The purpose of this study was to develop and validate a method to quantitate the veterinary sedative xylazine as well as 4-anilino-N-phenethylpiperidine (4-ANPP), acetyl fentanyl, fentanyl, norfentanyl, and p-fluorofentanyl in blood utilizing liquid chromatography tandem mass spectrometry. This method also qualitatively monitors for the presence of o-fluorofentanyl and m-fluorofentanyl isomers. UCT Clean Screen® DAU extraction columns were utilized to isolate the analytes in postmortem blood samples. The extracts were eluted, evaporated, reconstituted, and then analyzed using a Waters Acquity™ UPLC coupled a triple quadrupole mass spectrometer. The lower limit of quantitation was determined to be 0.1 ng/mL for all analytes, except for xylazine (0.2 ng/mL). The upper limit of quantitation for all analytes was 100 ng/mL. No interferences from matrix, internal standard, or common drug analytes were observed. Bias (-13.1–4.6 %) and precision (-13.14–10.3 %) fell within the acceptable ± 20 % criteria range. Dilution integrity at x2, x10, and x100 was evaluated and all results were within ± 20 % of the target concentration. Processed extract stability was evaluated after 72 h and all results were within ± 20 % of the analyte initial concentration. Matrix effects were the most prominent with xylazine, but deemed acceptable as the deuterated internal standard also observed comparable enhancement. Analysis of 89 postmortem blood samples by this method resulted in positive results for fentanyl (0.27–66 ng/mL, n = 82), xylazine (0.24–958 ng/mL, n = 21), 4-ANPP (0.10–38 ng/mL, n = 72), acetyl fentanyl (0.18–1.5 ng/mL, n = 3), p-fluorofentanyl (0.11–33 ng/mL, n = 30), and norfentanyl (0.10–98 ng/mL, n = 73).

Influence of carbon side chain length on the in vivo pharmacokinetic and pharmacodynamic characteristics of illicitly manufactured fentanyls.

Since 2016, illicitly manufactured fentanyls and fentanyl analogs (referred to as IMFs) have contributed to an increase in drug overdoses. Although fentanyl has been characterized and evaluated extensively in animals and humans, many of the clandestinely synthesized analogs of fentanyl have not and users may unknowingly ingest these IMFs leading to overdose and potentially death. The pharmacodynamic (PD) and pharmacokinetic (PK) properties of four IMFs and fentanyl were evaluated in Sprague-Dawley rats. A 300-μg/kg subcutaneous dose of each compound (fentanyl, acetylfentanyl, cyclopropylfentanyl, butyrylfentanyl, and valerylfentanyl) was given. PD parameters were measured using a tail flick meter and core body temperature. Blood was drawn to evaluate PK parameters utilizing liquid chromatography tandem mass spectrometry (LC-MS/MS). Fentanyl displayed the greatest and longest lasting analgesia with a tail flick response of 10s (the maximum cutoff). Additionally, fentanyl produced an average -4.9°C in core body temperature resulting in the greatest decrease in core body temperature. Acetylfentanyl, with the shortest carbon side chain, displayed the shortest T½, and lowest AUC and Cmax and resulted in an increase in body temperature. There were no other PK differences among the IMFs assessed. As IMFs are commonly seen on the streets and can pose significant risks to users (although these risks do depend on other factors such as dose and route of administration), there is a benefit to having the pharmacological properties of these compounds characterized to better understand the potential harm to humans.

Isobutyric acid promotes colorectal cancer metastasis through activating RACK1.

Colorectal cancer (CRC) metastasis plays a crucial role in disease progression, yet the regulatory mechanisms underlying metastasis remain incompletely understood. Isobutyric acid (IBA), a short-chain fatty acid found at high levels in serum of CRC patients, has been shown to be a critical metabolite influencing CRC proliferation. However, its role in tumor metastasis remains unknown. Here, utilizing liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis, we found that levels of IBA were significantly higher in patients with distant organ metastasis of CRC than in those without. Furthermore, IBA promoted CRC metastasis both in vitro and in vivo. Mass spectrometry, immunofluorescence, and cellular thermal shift assay revealed that IBA interacts with RACK1. Mechanistically, IBA binding to and activating RACK1 promotes regulation of downstream Akt and FAK signaling and CRC metastasis. Collectively, our study highlights the critical interplay between IBA and RACK1 and its impact on tumor metastasis. This study suggests that targeting the IBA-RACK1 signaling axis may be an effective therapeutic strategy for controlling CRC metastasis.

Type IV collagen-derived angiogenesis inhibitor: canstatin low expressing in brain-invasive meningiomas using liquid chromatography–mass spectrometry (LC-MS/MS)

PurposeBrain invasion in meningiomas is considered an indicator of more aggressive behavior and worse prognosis. But the precise definition and the prognostic role of brain invasion remains unsolved duo to lacking a standardized workflow of surgical sampling and the histopathological detection. Searching for molecular biomarker expression correlating with brain invasion, could contribute to establish a molecular pathological diagnosis without problems of subjective interobserver variation and deeply understand the mechanism of brain invasion and develop innovative therapeutic strategies.MethodsWe utilized liquid chromatography tandem mass spectrometry to quantify protein abundances between non-invasive meningiomas (n = 21) and brain-invasive meningiomas (n = 21) spanning World Health Organization grades I and III. After proteomic discrepancies were analyzed, the 14 most up-regulated or down-regulated proteins were recorded. Immunohistochemical staining for glial fibrillary acidic protein and most likely brain invasion-related proteins was performed in both groups.ResultsA total of 6498 unique proteins were identified in non-invasive and brain-invasive meningiomas. Canstatin expression in the non-invasive group was 2.1-fold that of the brain-invasive group. The immunohistochemical staining showed canstatin expressed in both groups, and the non-invasive group showed stronger staining for canstatin in the tumor mass (p = 0.0132) than the brain-invasive group, which showed moderate intensity.ConclusionThis study demonstrated the low expression of canstatin in meningiomas with brain invasion, a finding that provide a basis for understanding the mechanism of brain invasion of meningiomas and may contribute to establish molecular pathological diagnosis and identify novel therapeutic targets for personalized care.

Effect of serum sample storage temperature on metabolomic and proteomic biomarkers

Prospective biomarker studies can be used to identify biomarkers predictive of disease onset. However, if serum biomarkers are measured years after their collection, the storage conditions might affect analyte concentrations. Few data exists concerning which metabolites and proteins are affected by storage at − 20 °C vs − 80 °C. Our objectives were to document analytes affected by storage of serum samples at − 20 °C vs − 80 °C, and to identify those indicative of the storage temperature. We utilized liquid chromatography tandem mass spectrometry and Luminex to quantify 300 analytes from serum samples of 16 Finnish individuals with type 1 diabetes, with split-aliquot samples stored at − 80 °C and − 20 °C for a median of 4.2 years. Results were validated in 315 Finnish and 916 Scottish individuals with type 1 diabetes, stored at − 20 °C and at − 80 °C, respectively. After quality control, we analysed 193 metabolites and proteins of which 120 were apparently unaffected and 15 clearly susceptible to storage at − 20 °C vs − 80 °C. Further, we identified serum glutamate/glutamine ratio greater than 0.20 as a biomarker of storage at − 20 °C vs − 80 °C. The results provide a catalogue of analytes unaffected and affected by storage at − 20 °C vs − 80 °C and biomarkers indicative of sub-optimal storage.

Hair cortisol levels in schizophrenia and metabolic syndrome.

Individuals with schizophrenia demonstrate higher rates of metabolic syndrome (MetS) than the general population. Hair cortisol concentrations (HCC) reflect longer-term cortisol secretion and can provide additional insights into the role of the hypothalamic pituitary adrenal (HPA) axis in schizophrenia and co-occurring MetS. In a case-control study of 16 patients with schizophrenia (11 first episode psychosis [FEP] and 5 chronic) and 21 controls hair samples, representing a 3-month retrospective window of cortisol, were collected and analysed utilizing liquid chromatography tandem mass spectrometry. We investigated whether schizophrenia and MetS co-occurrence were associated with HCC utilizing multivariate regression models. We also explored the longitudinal trajectory of HCC in FEP patients by conducting a mixed models analysis. At baseline HCC were significantly lower (Cohen's d=0.88) in patients with schizophrenia than in controls (p= .014). HCC increased from baseline to month-12 in FEP patients compared to controls, demonstrating a trend towards significance (p= .097). MetS was not associated with HCC at baseline, but HCC increased significantly from baseline to month-12 in relation to MetS (p= .037). In a subgroup of schizophrenia patients, psychosis may be associated with a blunted HPA axis with lower long-term cortisol output. MetS was associated with an increase in HCC and elevated cortisol levels observed in schizophrenia may be related to increased rates of MetS in schizophrenia patients.

Serotonin modulates Campylobacter jejuni physiology and invitro interaction with the gut epithelium

Microbial endocrinology, which is the study of neurochemical-based host–microbe interaction, has demonstrated that neurochemicals affect bacterial pathogenicity. A variety of neurochemicals, including norepinephrine, were shown to enhance intestinal epithelial colonization by Campylobacter jejuni. Yet, little is known whether serotonin, an abundant neurochemical produced in the gut, affects the physiology of C. jejuni and its interaction with the host gut epithelium. Considering the avian gut produces serotonin and serves as a major reservoir of C. jejuni, we sought to investigate whether serotonin can affect C. jejuni physiology and gut epithelial colonization in vitro. We first determined the biogeographical distribution of serotonin concentrations in the serosa, mucosa, as well as the luminal contents of the broiler chicken ileum, cecum, and colon. Serotonin concentrations were greater (P < 0.05) in the mucosa and serosa compared to the luminal content in each gut region examined. Among the ileum, colon, and cecum, the colon was found to contain the greatest concentrations of serotonin. We then investigated whether serotonin may effect changes in C. jejuni growth and motility in vitro. The C. jejuni used in this study was previously isolated from the broiler chicken ceca. Serotonin at concentrations of 1mM or below did not elicit changes in growth (P > 0.05) or motility (P > 0.05) of C. jejuni. Next, we utilized liquid chromatography tandem mass spectrometry to investigate whether serotonin affected the proteome of C. jejuni. Serotonin caused (P < 0.05) the downregulation of a protein (CJJ81176_1037) previously identified to be essential in C. jejuni colonization. Based on our findings, we evaluated whether serotonin would cause a functional change in C. jejuni adhesion and invasion of the HT29MTX-E12 colonic epithelial cell line. Serotonin was found to cause a reduction in adhesion (P < 0.05) but not invasion (P > 0.05). Together, we have identified a potential role for serotonin in modulating C. jejuni colonization in the gut in vitro. Further studies are required to understand the practical implications of these findings for the control of C. jejuni enteric colonization in vivo.

Hair glucocorticoid levels in Parkinson’s disease

BackgroundParkinson’s disease (PD) and metabolic syndrome (MetS) share certain pathophysiological pathways, including hypothalamic pituitary adrenal (HPA) axis dysfunction. Hair glucocorticoid (GC) levels reflect longer-term HPA-axis function and can provide additional insights into the role of a dysregulated HPA-axis in PD and co-occurring cardiovascular disease (CVD) risk. ObjectivesIn a case-control study we examined the association of PD diagnosis, clinical features and PD-CVD risk (as defined by the MetS) co-occurrence with hair GC (cortisol and cortisone) levels. MethodsHair samples, representing a three-month retrospective window of GC levels, were collected and analysed utilizing liquid chromatography tandem mass spectrometry in 56 females (25 PD patients and 31 controls) of mixed ancestry, aged between 45 and 78 years (PD patients, M = 64.5, SD = 8.4; controls, M = 55.7, SD = 6.9). Multivariate regression models were constructed with PD diagnostic status, clinical features and MetS comorbidity regressed on hair GC levels, adjusting for potential confounders. ResultsThe prevalence of MetS was 56.0 % in PD patients and 25.8 % in controls. Hair cortisone (adj B = 5.44, 95 % CI 2.05; 8.83, p = 0.002), but not hair cortisol levels (adj B = 0.05, 95 % CI -0.12; 0.22, p = 0.539), were significantly higher (Cohen’s d = 0.87) in PD patients than in controls. Non-motor symptoms of PD (e.g., mood and anxiety) were significantly associated with hair cortisone levels (adj B = 0.29, 95 % CI 0.07; 0.51, p = 0.014). MetS was not associated with hair GC levels and there were no significant interactions between PD and MetS on hair GC levels. ConclusionsThis study is the first study reporting on hair GC levels in PD. We found chronically increased cortisone, but not cortisol, levels in PD patients compared to controls. Furthermore, hair cortisone levels were significantly positively associated with PD symptoms related to mood, anhedonia, and anxiety. Hair GC levels were not associated with PD-MetS comorbidity in this sample. Hair cortisone levels may provide additional insights into HPA-axis dysfunction in PD.

Development and Validation of a UHPLC-ESI-MS/MS Method for Quantification of Oleandrin and Other Cardiac Glycosides and Evaluation of Their Levels in Herbs and Spices from the Belgian Market.

Cardiac glycosides (CGs) are naturally occurring plant secondary metabolites that can be toxic to humans and animals. The aim of this work was to develop a targeted analytical method utilizing liquid chromatography—tandem mass spectrometry (LC-MS/MS) for quantification of these plant toxins in a herbal-based food and human urine. The method included oleandrin, digoxin, digitoxin, convallatoxin, and ouabain. Samples of culinary herbs were extracted with acetonitrile and cleaned using Oasis® MAX solid-phase extraction (SPE), while samples of urine were diluted with acidified water and purified on Oasis® HLB SPE cartridges. Limits of quantification were in the range of 1.5–15 ng/g for herbs and 0.025–1 ng/mL for urine. The mean recovery of the method complied with the acceptable range of 70–120% for most CGs, and relative standard deviations were at maximum 14% and 19% for repeatability and reproducibility, respectively. Method linearity was good with calculated R² values above 0.997. The expanded measurement uncertainty was estimated to be in the range of 7–37%. The LC-MS/MS method was used to examine 65 samples of culinary herbs and herb and spice mixtures collected in Belgium, from supermarkets and local stores. The samples were found to be free from the analyzed CGs.

Proteome and Phosphoproteome Changes Associated with Prognosis in Acute Myeloid Leukemia.

Acute myeloid leukemia (AML) is a hematological cancer that mainly affects the elderly. Although complete remission (CR) is achieved for the majority of the patients after induction and consolidation therapies, nearly two-thirds relapse within a short interval. Understanding biological factors that determine relapse has become of major clinical interest in AML. We utilized liquid chromatography tandem mass spectrometry (LC-MS/MS) to identify the protein changes and protein phosphorylation events associated with AML relapse in primary cells from 41 AML patients at time of diagnosis. Patients were defined as relapse-free if they had not relapsed within a five-year clinical follow-up after AML diagnosis. Relapse was associated with increased expression of RNA processing proteins and decreased expression of V-ATPase proteins. We also observed an increase in phosphorylation events catalyzed by cyclin-dependent kinases (CDKs) and casein kinase 2 (CSK2). The biological relevance of the proteome findings was supported by cell proliferation assays using inhibitors of V-ATPase (bafilomycin), CSK2 (CX-4945), CDK4/6 (abemaciclib) and CDK2/7/9 (SNS-032). While bafilomycin preferentially inhibited the cells from relapse patients, the kinase inhibitors were less efficient in these cells. This suggests that therapy against the upregulated kinases could also target the factors inducing their upregulation rather than their activity. This study, therefore, presents markers that could help predict AML relapse and direct therapeutic strategies.

Evaluation of 4-fluoroisobutyrylfentanyl in blood samples from 247 authentic cases submitted to the New York City Office of Chief Medical Examiner in 2017–2018

4-Fluoroisobutyrylfentanyl (FIBF) was first identified at the New York City Office of Chief Medical Examiner (OCME) in May 2017 and was reported qualitatively due to the constant changes in “fentalogs” (analogs of fentanyl) identified. However, by the year’s end, FIBF was the fifth most common non-methadone synthetic opioid detected and a quantitative method was developed to better understand the significance of this compound. A full quantitative validation was performed utilizing liquid chromatography–tandem mass spectrometry (LC–MS/MS). All cases submitted between May 2017 and December 2018 that tested positive for FIBF qualitatively were chosen for quantitation. In addition to compiling FIBF concentrations, user demographics and concurrent drug use were also investigated. There were 247 FIBF-positive cases that were tested with blood concentrations ranging from < 0.1 to 331 ng/mL. The most commonly detected drugs in conjunction with FIBF were other opioids, benzodiazepines, cocaine, cannabinoids and ethanol. The most frequent users were male, White, and between 35 and 54 years of age. The concentrations of FIBF varied widely and showed no clear distinction when considering various case types. Although most often used in tandem with other drugs of abuse, the danger of this compound was demonstrated by the fact that FIBF was also reported as the sole intoxicant responsible for death. The development of a quantitative method for FIBF has been beneficial at the OCME due to the significant number of positive cases reported and the current lack of sufficient published information on this analog. To our knowledge, there are only two papers that include FIBF concentrations in four cases; this article gives the largest number (247 cases) of FIBF levels in blood samples of its users to aid in the interpretation and analysis of significance of this compound.

Molecularly imprinted polymer-sol-gel tablet toward micro-solid phase extraction: I. Determination of methadone in human plasma utilizing liquid chromatography–tandem mass spectrometry

In the present work molecularly imprinted sol-gel tablet (MIP-Tablet) was prepared. The MIP-sol-gel was prepared as a thin layer on polyethylene material in a tablet form. Methadone-d9 was selected as the template and 3-(propylmethacrylate)-trimethoxysilane was used as precursor. MIP-Tablet was applied for micro-solid phase extraction (μ-SPE). The MIP-Tablet was used for the determination of methadone in human plasma samples utilizing liquid chromatography-tandem mass spectrometry; and each tablet could be used twenty times. The extraction time was 10 min while desorption time was 6 min. Factors affecting the extraction efficiency such as desorption solvents, sample pH, salt addition, extraction time, desorption time and adsorption capacity were investigated. The calibration curves were obtained within the range of 5–5000 ng/mL using methadone in human plasma samples. The coefficients of determination (r2) values were ≥0.999 for all runs and the extraction recovery was >80%. The accuracy values for quality control samples varied from +3.6 to +9.7% and the inter-day precision (RSD %) values were ranged from 5.0 to 8.0%. The limit of detection was 1.0 ng/mL and the lower limit of quantification was 5 ng/mL utilizing methadone in human plasma samples.

Quantitative analysis of 11-nor-9-carboxy-tetrahydrocannbinol (THC–COOH) in urine by LC–MS/MS following a simple filtration

Quantification methods utilizing liquid chromatography tandem mass spectrometry (LC-MS/MS) are common in clinical and forensic toxicology laboratories and the efficiency and rapidity of such methods continues to evolve. In most cases, urine drug confirmation does not require a drug extraction and can quickly and easily be accomplished with a dilution followed by sample filtration. The report describes the validation of a simple confirmation method for 11-nor-9-carboxy-tetrahydrocannabinol (THC-COOH) and compared two types of filter extraction columns for sample clean-up. The method achieved a linear range of 10-3000ng/mL, acceptable bias (-4.7-2.6%) and precision (0.9-6.9%) and autosampler stability up to 72h. Universal filter columns offered less variable recovery over the linear range and fewer matrix interferences compared to THC-COOH specific filter columns. Authentic specimens testing positive for THC-COOH by LC-MS/MS were in good agreement with typically used GC-MS methods.

Method validation and reconnaissance of pharmaceuticals, personal care products, and alkylphenols in surface waters, sediments, and mussels in an urban estuary

Novel methods utilizing liquid chromatography–tandem mass spectrometry and gas chromatography–mass spectrometry were validated for low-level detection of 104 pharmaceuticals and personal care products ingredients (PPCPs) and four alkylphenols (APs) in environmental samples. The methods were applied to surface water, sediment, and mussel tissue samples collected from San Francisco Bay, CA, USA, an urban estuary that receives direct discharge from over forty municipal and industrial wastewater outfalls. Among the target PPCPs, 35% were detected in at least one sample, with 31, 10, and 17 compounds detected in water, sediment, and mussels, respectively. Maximum concentrations were 92ng/L in water (valsartan), 33ng/g dry weight (dw) in sediments (triclocarban), and 14ng/g wet weight (ww) in mussels (N,N-diethyl-m-toluamide). Nonylphenol was detected in water (<2–73ng/L), sediments (22–86ng/g dw), and mussels (<0.04–95ng/g ww), and nonylphenol mono- and diethoxylates were detected in sediments (<1–40ng/g dw) and mussels (<5–192ng/g ww). The concentrations of PPCPs and APs detected in the San Francisco Bay samples were generally at least an order of magnitude below concentrations expected to elicit toxic effects in aquatic organisms. This study represents the first reconnaissance of PPCPs in mussels living in an urban estuary and provides the first field-derived bioaccumulation factors (BAFs) for select compounds in aquatic organisms.

Dried Blood Spot Analysis of Donepezil in Support of a GLP 3-month Dose-Range Finding Study in Rats

Donepezil hydrochloride is a reversible acetyl cholinesterase inhibitor approved for Alzheimer disease treatment. As an alternate therapy, a donepezil hydrochloride transdermal patch is in development. Recommended nonclinical safety studies include a 3-month Good Laboratory Practice (GLP) dose-range finding (DRF) study prior to conducting the 2-year dermal carcinogenicity study in rats. Demonstration of systemic exposure is necessary to interpret the in vivo data. Previous nonclinical reports supporting oral dosing have utilized liquid chromatography tandem mass spectrometry (LC/MS/MS) to quantify donepezil concentrations in plasma. Smaller species with limited blood volumes do not allow serial sampling to derive the full pharmacokinetic profile from a single animal. Therefore, the option of another analytical method requiring decreased sample volumes is desirable as it would decrease the required number of animals while obtaining the complete profile. The dried blood spot (DBS) technique allows drug level measurement from a few microliters; however, the method is still not widely utilized in GLP studies. Because donepezil plasma levels are known by the oral route, DBS was used to bridge the previous oral data and to support a 13-week GLP DRF study for repeated topical application in rats, comparing oral administration with 4 topical formulations. The DBS method was validated and demonstrated robustness and reproducibility for application to the DRF study. The assay results were comparable to a previously reported plasma LC/MS/MS assay-derived pharmacokinetic profile and provided justification for selection of the topical formulation and dose levels for the subsequent dermal carcinogenicity study.

Abstract 1249: Metabolomic analysis of a genetically defined model of oncogenesis reveals that common oncogenic mutations result in synergistic deregulation of multiple metabolic pathways

Abstract Oncogenesis induces profound changes to the cellular metabolic network. A number of these cancer-cell metabolic phenotypes have been found to be important for in vivo tumorigenesis. We have utilized liquid chromatography tandem mass spectrometry (LC-MS/MS) to globally profile the metabolic network of a genetically-defined experimental model of oncogenesis in an attempt to identify novel metabolic activities induced by transformation. Furthermore, we sought to delineate how common oncogenic mutations contribute to specific metabolic phenotypes. We have analyzed how dominant negative p53 and constitutively active Ras expression, either independently or in concert, impacts the metabolic activity of non-transformed parental colon crypt epithelial cells. In addition to measuring steady-state metabolite concentrations, we have employed isotope tracer analysis to measure the impact of oncogenic mutation on metabolic pathway kinetics. We find that combined p53 and Ras oncogenic mutation synergistically activates numerous aspects of central carbon metabolism including glycolysis, glutamine catabolism, and pyrimidine and purine biosynthesis. Our data indicate that many well-defined oncogenic metabolic phenotypes are the result of a cooperative effect of combinatorial mutation highlighting the importance of identifying the interaction between oncogenic signal transduction and metabolic regulation for understanding the etiology of the cancer-cell metabolic state. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1249. doi:10.1158/1538-7445.AM2011-1249

Rapid determination and pharmacokinetics study of lignans in rat plasma after oral administration of Schisandra chinensis extract and pure deoxyschisandrin

A simple, sensitive and rapid method for analysis of six lignans in rat plasma after oral administration of Schisandra chinensis extracts, utilizing liquid chromatography tandem mass spectrometry (LC-MS), was established and validated. Plasma samples were prepared by one-step protein precipitation using acetonitrile and the analytes were separated on an SB-C₁₈ column (100 mm × 3.0 mm, 3.5 µm) with the mobile phase of acetonitrile-water at a flow-rate of 0.8 mL/min. Analytes were determined in a single-quadrupole mass spectrometer in the selected ion monitoring (SIM) mode using electrospray source with positive mode. The method was proved to be rapid, sensitive and reproducible, and it was successfully applied to the pharmacokinetic studies of six lignans in rat plasma after oral administration of Schisandra chinensis extracts. In this research, the pharmacokinetics of deoxyschisandrin was also studied following oral administration of the pure deoxyschisandrin. It was found that most of the pharmacokinetic parameters of deoxyschisandrin in the extract were changed significantly compared with those in monomer. The content assay also revealed that the concentrations of the lignan in the extract increased in vivo compared with the pure monomer. Some ingredients in the extract may increase the dissolution of deoxyschisandrin, delay its elimination and enhance its bioavailability in rat.

Determination of olprinone in human plasma utilizing liquid chromatography tandem mass spectrometry

A sensitive and rapid method was developed for quantification of olprinone in human plasma utilizing liquid chromatography tandem mass spectrometry (LC–MS/MS). An aliquot of 1 mL plasma sample was extracted with ethyl acetate–dichloromethane. Separation of olprinone and the milrinone (internal standard, IS) from the interferences was achieved on a C 18 column followed by MS/MS detection. The analytes were monitored in the positive ionization mode. Multiple reaction monitoring using the transition of m/ z 251 → m/ z 155 and m/ z 212 → m/ z 140 was performed to quantify olprinone and IS, respectively. The method had a total chromatographic run time of 3 min and linear calibration curves over the concentration range of 0.5–60 ng/mL. The lower limit of quantification (LLOQ) was 0.5 ng/mL. The intra- and inter-day precisions were less than 16.3% for low QC level, and 7.1% for other QC levels, respectively. The intra- and inter-day relative errors were ranged between −12.2% and 3.7% for three QC concentration levels. The validated method was successfully applied to the quantification of olprinone concentration in human plasma after intravenous (i.v.) administration of olprinone at a constant rate of infusion of 2 μg/(kg min) for 5 min in order to evaluate the pharmacokinetics.