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BACKGROUND: Quality smoking data is crucial for assessing smoking-related health risk and eligibility for interventions related to that risk. Smoking information collected in primary care practices (PCPs) is a major data source; however, little is known about the PCP smoking data quality. This project compared PCP smoking data to that collected in the Maori and Pacific Abdominal Aortic Aneurysm (AAA) screening programme. METHODS: A two stage review was conducted. In Stage 1, data quality was assessed by comparing the PCP smoking data recorded close to AAA screening episodes with the data collected from participants at the AAA screening session. Inter-rater reliability was analysed using Cohen's kappa scores. In Stage 2, an audit of longitudinal smoking status was conducted, of a subset of participants potentially misclassified in Stage 1. Data were compared in three groups: current smoker (smoke at least monthly), ex-smoker (stopped > 1 month ago) and never smoker (smoked < 100 cigarettes in lifetime). RESULTS: Of the 1841 people who underwent AAA screening, 1716 (93%) had PCP smoking information. Stage 1 PCP smoking data showed 82% concordance with the AAA data (adjusted kappa 0.76). Fewer current or ex-smokers were recorded in PCP data. In the Stage 2 analysis of discordant and missing data (N = 313), 212 were enrolled in the 29 participating PCPs, and of these 13% were deceased and 41% had changed PCP. Of the 93 participants still enrolled in the participating PCPs, smoking status had been updated for 43%. Data on quantity, duration, or quit date of smoking were largely missing in PCP records. The AAA data of ex-smokers who were classified as never smokers in the Stage 2 PCP data (N = 27) showed a median smoking cessation duration of 32 years (range 0-50 years), with 85% (N = 23) having quit more than 15 years ago. CONCLUSIONS: PCP smoking data quality compared with the AAA data is consistent with international findings. PCP data captured fewer current and ex-smokers, suggesting ongoing improvement is important. Intervention programmes based on smoking status should consider complementary mechanisms to ensure eligible individuals are not missed from programme invitation.
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Aneurisma de la Aorta Abdominal , Atención Primaria de Salud , Fumar , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Aneurisma de la Aorta Abdominal/diagnóstico , Exactitud de los Datos , Pueblo Maorí , Tamizaje Masivo , Nueva Zelanda/epidemiología , Fumar/epidemiologíaRESUMEN
BACKGROUND: Atrial fibrillation (AF) screening was incorporated into an abdominal aortic aneurysm screening (AAA) program for New Zealand (NZ) Maori. METHODS: AF screening was performed as an adjunct to AAA screening of Maori men aged 60-74 years and women aged 65-74 years registered with primary health care practices in Auckland, NZ. Pre-existing AF was determined through coded diagnoses or medications in the participant's primary care record. Subsequent audit of the record assessed accuracy of pre-screening coding, medication use and clinical follow-up. RESULTS: Among 1,933 people successfully screened, the prevalence of AF was 144 (7.4%), of which 46 (2.4% of the cohort) were patients without AF coded in the medical record. More than half of these were revealed to be known AF but that was not coded. Thus, the true prevalence of newly detected AF was 1.1% (n=21). An additional 48 (2.5%) of the cohort had been coded as AF but were not in AF at the time of screening. Among the 19 at-risk screen-detected people with AF, 10 started appropriate anticoagulation therapy within 6 months. Of the nine patients who did not commence anticoagulation therapy, five had a subsequent adverse clinical outcome in the follow-up period, including one with ischaemic stroke; two had contraindications to anticoagulants. Among those with previously diagnosed AF, the proportion receiving anticoagulation therapy rose from 57% pre-screening to 83% at 6 months post-screening (p<0.0001); among newly diagnosed AF the proportion rose from 0% to 53% (p<0.01). CONCLUSIONS: AF screening is a feasible low-cost adjunct to AAA screening with potential to reduce ethnic inequities in stroke incidence. However, effective measures are needed to ensure that high-risk newly diagnosed AF is managed according to best practice guidelines.
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Aneurisma de la Aorta Abdominal , Fibrilación Atrial , Isquemia Encefálica , Accidente Cerebrovascular , Femenino , Humanos , Masculino , Anticoagulantes/uso terapéutico , Aneurisma de la Aorta Abdominal/diagnóstico , Aneurisma de la Aorta Abdominal/epidemiología , Aneurisma de la Aorta Abdominal/inducido químicamente , Fibrilación Atrial/diagnóstico , Fibrilación Atrial/epidemiología , Fibrilación Atrial/tratamiento farmacológico , Pueblo Maorí , Tamizaje Masivo , Nueva Zelanda/epidemiología , Prevalencia , Accidente Cerebrovascular/etiología , Persona de Mediana Edad , AncianoRESUMEN
PURPOSE: Bolus electron conformal therapy (BECT) is a clinically useful, well-documented, and available technology. The addition of intensity modulation (IM) to BECT reduces volumes of high dose and dose spread in the planning target volume (PTV). This paper demonstrates new techniques for a process that should be suitable for planning and delivering IM-BECT using passive radiotherapy intensity modulation for electrons (PRIME) devices. METHODS: The IM-BECT planning and delivery process is an addition to the BECT process that includes intensity modulator design, fabrication, and quality assurance. The intensity modulator (PRIME device) is a hexagonal matrix of small island blocks (tungsten pins of varying diameter) placed inside the patient beam-defining collimator (cutout). Its design process determines a desirable intensity-modulated electron beam during the planning process, then determines the island block configuration to deliver that intensity distribution (segmentation). The intensity modulator is fabricated and quality assurance performed at the factory (.decimal, LLC, Sanford, FL). Clinical quality assurance consists of measuring a fluence distribution in a plane perpendicular to the beam in a water or water-equivalent phantom. This IM-BECT process is described and demonstrated for two sites, postmastectomy chest wall and temple. Dose plans, intensity distributions, fabricated intensity modulators, and quality assurance results are presented. RESULTS: IM-BECT plans showed improved D90-10 over BECT plans, 6.4% versus 7.3% and 8.4% versus 11.0% for the postmastectomy chest wall and temple, respectively. Their intensity modulators utilized 61 (single diameter) and 246 (five diameters) tungsten pins, respectively. Dose comparisons for clinical quality assurance showed that for doses greater than 10%, measured agreed with calculated dose within 3% or 0.3 cm distance-to-agreement (DTA) for 99.9% and 100% of points, respectively. CONCLUSION: These results demonstrated the feasibility of translating IM-BECT to the clinic using the techniques presented for treatment planning, intensity modulator design and fabrication, and quality assurance processes.
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Neoplasias de la Mama , Radioterapia Conformacional , Electrones , Femenino , Humanos , Mastectomía , Fantasmas de ImagenRESUMEN
PURPOSE: This project determined the range of island block geometric configurations useful for the clinical utilization of intensity-modulated bolus electron conformal therapy (IM-BECT). METHODS: Multiple half-beam island block geometries were studied for seven electron energies 7-20 MeV at 100 and 103 cm source-to-surface distance (SSD). We studied relative fluence distributions at 0.5 cm and 2.0 cm depths in water, resulting in 28 unique beam conditions. For each beam condition, we studied intensity reduction factor (IRF) values of 0.70, 0.75, 0.80, 0.85, 0.90, and 0.95, and hexagonal packing separations for the island blocks of 0.50, 0.75, 1.00, 1.25, and 1.50 cm, that is, 30 unique IM configurations and 840 unique beam-IM combinations. A combination was deemed acceptable if the average intensity downstream of the intensity modulator agreed within 2% of that intended and the variation in fluence was less than ±2%. RESULTS: For 100 cm SSD, and for 0.5 cm depth, results showed that beam energies above 13 MeV did not exhibit sufficient scatter to produce clinically acceptable fluence (intensity) distributions for all IRF values (0.70-0.95). In particular, 20 MeV fluence distributions were unacceptable for any values, and acceptable 16 MeV fluence distributions were limited to a minimum IRF of 0.85. For the 2.0 cm depth, beam energies up to and including 20 MeV had acceptable fluence distributions. For 103 cm SSD and for 0.5 cm and 2.0 cm depths, results showed that all beam energies (7-20 MeV) had clinically acceptable fluence distributions for all IRF values (0.70-0.95). In general, the more clinically likely 103 cm SSD had acceptable fluence distributions with larger separations (r), which allow larger block diameters. CONCLUSION: The geometric operating range of island block separations and IRF values (block diameters) producing clinically appropriate IM electron beams has been determined.
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Electrones , Radioterapia Conformacional , Humanos , Dosificación Radioterapéutica , Planificación de la Radioterapia Asistida por ComputadorRESUMEN
INTRODUCTION: Reference materials based on human cerebrospinal fluid were certified for the mass concentration of amyloid beta (Aß)1-42 (Aß42 ). They are intended to be used to calibrate diagnostic assays for Aß42 . METHODS: The three certified reference materials (CRMs), ERM-DA480/IFCC, ERM-DA481/IFCC and ERM-DA482/IFCC, were prepared at three concentration levels and characterized using isotope dilution mass spectrometry methods. Roche, EUROIMMUN, and Fujirebio used the three CRMs to re-calibrate their immunoassays. RESULTS: The certified Aß42 mass concentrations in ERM-DA480/IFCC, ERM-DA481/IFCC, and ERM-DA482/IFCC are 0.45, 0.72, and 1.22 µg/L, respectively, with expanded uncertainties (k = 2) of 0.07, 0.11, and 0.18 µg/L, respectively. Before re-calibration, a good correlation (Pearson's r > 0.97), yet large biases, were observed between results from different commercial assays. After re-calibration the between-assay bias was reduced to < 5%. DISCUSSION: The Aß42 CRMs can ensure the equivalence of results between methods and across platforms for the measurement of Aß42 .
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Péptidos beta-Amiloides/líquido cefalorraquídeo , Inmunoensayo/normas , Calibración , Humanos , Inmunoensayo/métodos , Estándares de ReferenciaRESUMEN
This work introduces a new technology for electron intensity modulation, which uses small area island blocks within the collimating aperture and small area island apertures in the collimating insert. Due to multiple Coulomb scattering, electrons contribute dose under island blocks and lateral to island apertures. By selecting appropriate lateral positions and diameters of a set of island blocks and island apertures, for example, a hexagonal grid with variable diameter circular island blocks, intensity modulated beams can be produced for appropriate air gaps between the intensity modulator (position of collimating insert) and the patient. Such a passive radiotherapy intensity modulator for electrons (PRIME) is analogous to using physical attenuators (metal compensators) for intensity modulated x-ray therapy (IMXT). For hexagonal spacing, the relationship between block (aperture) separation (r) and diameter (d) and the local intensity reduction factor (IRF) is discussed. The PRIME principle is illustrated using pencil beam calculations for select beam geometries in water with half beams modulated by 70%-95% and for one head and neck field of a patient treated with bolus electron conformal therapy. Proof of principle is further illustrated by showing agreement between measurement and calculation for a prototype PRIME. Potential utilization of PRIME for bolus electron conformal therapy, segmented-field electron conformal therapy, modulated electron radiation therapy, and variable surface geometries is discussed. Further research and development of technology for the various applications is discussed. In summary, this paper introduces a practical, new technology for electron intensity modulation in the clinic, demonstrates proof of principle, discusses potential clinical applications, and suggests areas of further research and development.
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Electrones/uso terapéutico , Radioterapia de Intensidad Modulada/métodos , HumanosRESUMEN
INTRODUCTION: Cerebrospinal fluid (CSF) amyloid-ß 1-42 (Aß42) is an important biomarker for Alzheimer's disease, both in diagnostics and to monitor disease-modifying therapies. However, there is a great need for standardization of methods used for quantification. To overcome problems associated with immunoassays, liquid chromatography-tandem mass spectrometry (LC-MS/MS) has emerged as a critical orthogonal alternative. METHODS: We compared results for CSF Aß42 quantification in a round robin study performed in four laboratories using similar sample preparation methods and LC-MS instrumentation. RESULTS: The LC-MS results showed excellent correlation between laboratories (r(2) >0.98), high analytical precision, and good correlation with enzyme-linked immunosorbent assay (r(2) >0.85). The use of a common reference sample further decreased interlaboratory variation. DISCUSSION: Our results indicate that LC-MS is suitable for absolute quantification of Aß42 in CSF and highlight the importance of developing a certified reference material.
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Péptidos beta-Amiloides/líquido cefalorraquídeo , Biomarcadores/líquido cefalorraquídeo , Cromatografía Liquida/métodos , Fragmentos de Péptidos/líquido cefalorraquídeo , Espectrometría de Masas en Tándem/métodos , Enfermedad de Alzheimer/líquido cefalorraquídeo , Calibración , Ensayo de Inmunoadsorción Enzimática/normas , Humanos , Estándares de ReferenciaRESUMEN
This work provides a multidimensional method for the simultaneous, direct quantification of intact human insulin and five insulin analogs in human plasma. This investigation solves both the selectivity and sensitivity problems encountered for accurate quantification of insulins in plasma since the former is not possible with conventional assays and the latter with conventional LC-MS/MS. The method uses a mixed-mode SPE and a multidimensional LC method including a solid-core particle column containing an anion exchange stationary phase. Matrix factors for all analogs were calculated in 6 sources of human plasma and CVs of the matrix factors were <15% in all cases supporting the selectivity of the method, while achieving LLOQs of 50-200 pg/mL (1.4-5.6 µIU/mL) for each insulin from 250 µL of human plasma. The average accuracy for the standard curve points in extracted human plasma was 99-100%. Average inter- and intraday accuracies for QC samples were 98% and 94%, respectively. Average inter- and intraday precisions for QC samples were 7.5 and 5.3%, respectively. Patient samples were analyzed in a blind study and results concurred with their diabetes multidosing regimes. The study also demonstrated that the presence of high levels of human insulin and bovine insulin does not interfere with quantification of any of the analyzed analogs. We propose this method for the accurate pharmacokinetic monitoring of diabetic patients, for sport antidoping and forensic toxicology analysis.
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Insulina/análogos & derivados , Insulina/sangre , Espectrometría de Masas en Tándem/métodos , Secuencia de Aminoácidos , Animales , Bovinos , Cromatografía Liquida/métodos , Humanos , Insulina/genética , Espectrometría de Masas/métodos , Datos de Secuencia MolecularRESUMEN
AIMS: To examine wahine Maori experiences of colposcopy services in New Zealand based on surveys conducted in 2016 and 2021. METHODS: The surveys included a total of 201 wahine Maori who had attended one of the three colposcopy clinics in the Waitemata and Auckland districts. Participants were retrospectively surveyed about their experience via telephone using a pre-tested questionnaire. Pre-defined responses were analysed quantitatively, and narrative comments were analysed thematically. RESULTS: Response rates were 27.6% in 2016 and 34.2% in 2021. Prior to their appointment, most women reported receiving the information leaflet and a reminder. At the clinic visit, overall interaction with staff, comfort, listening and explanation of the procedure all scored highly, with maintenance or improvements from 2016 to 2021. Wahine reported feeling culturally safe. Areas for improvement included content of information, access to Maori community liaison, appointment waiting time and delivery of colposcopy results. CONCLUSIONS: The findings indicated that wahine Maori had overall excellent experiences of colposcopy services, maintained over a five-year period with some suggested improvements to context of information and communication. This provides reassurance for wahine Maori in the diagnostic and treatment part of the cervical screening pathway ahead of the upcoming change to HPV primary screening.
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Colposcopía , Detección Precoz del Cáncer , Pueblo Maorí , Neoplasias del Cuello Uterino , Femenino , Humanos , Nueva Zelanda , Estudios Retrospectivos , Encuestas y Cuestionarios , Neoplasias del Cuello Uterino/diagnóstico , Neoplasias del Cuello Uterino/prevención & controlRESUMEN
Cycle threshold (CT) refers to the number of cycles in a reverse transcriptase polymerase chain reaction (RT-PCR) assay needed to amplify viral RNA and can be used to indicate viral load. CT is inversely related to viral load, where lower CT values indicate higher viral levels. Data suggest lower CT scores are associated with worse outcomes in COVID; however, quantitative CT scores are not typically reported to patients. This retrospective analysis examined the use of CT scores in patient counseling for positive COVID results and suggests that higher viral loads were associated with greater need for prescription drug therapy in the outpatient setting. Patient perception of CT score was found to influence masking and quarantine behavior. We hypothesize that a quantitative threshold for viral load such as CT can be useful in patient counseling, estimating need for drug therapy, and influencing behavior toward public health concerns.
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Critical events in Alzheimer's disease (AD) involve an imbalance between the production and clearance of amyloid beta (Aß) peptides from the brain. Current methods for Aß quantitation rely heavily on immuno-based techniques. However, these assays require highly specific antibodies and reagents that are time-consuming and expensive to develop. Immuno-based assays are also characterized by poor dynamic ranges, cross-reactivity, matrix interferences, and dilution linearity problems. In particular, noncommercial immunoassays are especially subject to high intra- and interassay variability because they are not subject to more stringent manufacturing controls. Combinations of these factors make immunoassays more labor-intensive and often challenging to validate in support of clinical studies. Here we describe a mixed-mode solid-phase extraction method and an ultra-performance liquid chromatography tandem mass spectrometry (SPE UPLC-MS/MS) assay for the simultaneous quantitation of Aß(1-38), Aß(1-40), and Aß(1-42) from human cerebrospinal fluid (CSF). Negative ion versus positive ion species were compared using their corresponding multiple reaction monitoring (MRM) transitions, and negative ions were approximately 1.6-fold greater in intensity but lacked selectivity in matrix. The positive ion MRM assay was more than sufficient to quantify endogenous Aß peptides. Aß standards were prepared in artificial CSF containing 5% rat plasma, and quality control samples were prepared in three pooled CSF sources. Extraction efficiency was greater than 80% for all three peptides, and the coefficient of variation during analysis was less than 15% for all species. Mean basal levels of Aß species from three CSF pools were 1.64, 2.17, and 1.26 ng/ml for Aß(1-38); 3.24, 3.63, and 2.55 ng/ml for Aß(1-40); and 0.50, 0.63, and 0.46 ng/ml for Aß(1-42).
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Péptidos beta-Amiloides/líquido cefalorraquídeo , Cromatografía Líquida de Alta Presión/métodos , Espectrometría de Masas en Tándem/métodos , Secuencia de Aminoácidos , Péptidos beta-Amiloides/química , Humanos , Datos de Secuencia Molecular , Fragmentos de Péptidos/líquido cefalorraquídeo , Fragmentos de Péptidos/química , Control de Calidad , Estándares de Referencia , Extracción en Fase SólidaRESUMEN
BACKGROUND: 3D imaging, such as X-ray CT and MRI, has been widely deployed to study plant root structures. Many computational tools exist to extract coarse-grained features from 3D root images, such as total volume, root number and total root length. However, methods that can accurately and efficiently compute fine-grained root traits, such as root number and geometry at each hierarchy level, are still lacking. These traits would allow biologists to gain deeper insights into the root system architecture. RESULTS: We present TopoRoot, a high-throughput computational method that computes fine-grained architectural traits from 3D images of maize root crowns or root systems. These traits include the number, length, thickness, angle, tortuosity, and number of children for the roots at each level of the hierarchy. TopoRoot combines state-of-the-art algorithms in computer graphics, such as topological simplification and geometric skeletonization, with customized heuristics for robustly obtaining the branching structure and hierarchical information. TopoRoot is validated on both CT scans of excavated field-grown root crowns and simulated images of root systems, and in both cases, it was shown to improve the accuracy of traits over existing methods. TopoRoot runs within a few minutes on a desktop workstation for images at the resolution range of 400^3, with minimal need for human intervention in the form of setting three intensity thresholds per image. CONCLUSIONS: TopoRoot improves the state-of-the-art methods in obtaining more accurate and comprehensive fine-grained traits of maize roots from 3D imaging. The automation and efficiency make TopoRoot suitable for batch processing on large numbers of root images. Our method is thus useful for phenomic studies aimed at finding the genetic basis behind root system architecture and the subsequent development of more productive crops.
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A systematic, comprehensive strategy that optimizes sample preparation and chromatography to minimize matrix effects in bioanalytical LC/MS/MS assays was developed. Comparisons were made among several sample preparation methods, including protein precipitation (PPT), liquid-liquid extraction (LLE), pure cation exchange solid-phase extraction (SPE), reversed-phase SPE and mixed-mode SPE. The influence of mobile phase pH and gradient duration on the selectivity and sensitivity for both matrix components and basic analytes was investigated. Matrix effects and overall sensitivity and resolution between UPLC technology and HPLC were compared. The amount of specific matrix components, or class of matrix components, was measured in the sample preparation extracts by LC/MS/MS with electrospray ionization (ESI) using both precursor ion scanning mode and multiple reaction monitoring (MRM). PPT is the least effective sample preparation technique, often resulting in significant matrix effects due to the presence of many residual matrix components. Reversed-phase and pure cation exchange SPE methods resulted in cleaner extracts and reduced matrix effects compared to PPT. The cleanest extracts, however, were produced with polymeric mixed-mode SPE (both reversed-phase and ion exchange retention mechanisms). These mixed-mode sorbents dramatically reduced the levels of residual matrix components from biological samples, leading to significant reduction in matrix effects. LLE also provided clean final extracts. However, analyte recovery, particularly for polar analytes, was very low. Mobile phase pH was manipulated to alter the retention of basic compounds relative to phospholipids, whose retention tends to be relatively independent of pH. In addition to the expected resolution, speed and sensitivity benefits of UPLC technology, a paired t-test demonstrated a statistically significant improvement with respect to matrix effects when this technology was chosen over traditional HPLC. The combination of polymeric mixed-mode SPE, the appropriate mobile phase pH and UPLC technology provides significant advantages for reducing matrix effects resulting from plasma matrix components and in improving the ruggedness and sensitivity of bioanalytical methods.
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Cromatografía Líquida de Alta Presión/métodos , Cromatografía por Intercambio Iónico/métodos , Espectrometría de Masa por Ionización de Electrospray/métodos , Espectrometría de Masas en Tándem/métodos , Concentración de Iones de Hidrógeno , Fosfolípidos/análisis , Sensibilidad y EspecificidadRESUMEN
Just over 10 years ago, we conducted a culture study of the Computer Science Department at the flagship University of Illinois at Urbana-Champaign, one of the top five computing departments in the country. The study found that while the department placed an emphasis on research, it did so in a way that, in conjunction with a lack of communication and transparency, devalued teaching and mentoring, and negatively impacted the professional development, education, and sense of belonging of the students. As one part of a multi-phase case study spanning over a decade, this manuscript presents preliminary findings from our latest work at the university. We detail early comparisons between data gathered at the Department of Computer Science at the University of Illinois at Urbana-Champaign in 2005 and our most recent pilot case study, a follow-up research project completed in 2016. Though we have not yet completed the full data collection, we find it worthwhile to reflect on the pilot case study data we have collected thus far. Our data reveals improvements in the perceptions of undergraduate teaching quality and undergraduate peer mentoring networks. However, we also found evidence of continuing feelings of isolation, incidents of bias, policy opacity, and uneven policy implementation that are areas of concern, particularly with respect to historically underrepresented groups. We discuss these preliminary follow-up findings, offer research and methodological reflections, and share next steps for applied research that aims to create positive cultural change in computing.
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BACKGROUND: Increased pressure to obtain more, higher sensitivity data from less sample is especially critical for large peptides, whose already optimized LC-MS methods are heavily challenged by traditional ligand-binding assays. RESULTS: Critical bioanalytical assays were adapted to integrated microscale LC to reduce sample volumes while increasing sensitivity. Assays for teriparatide, glucagon and human insulin and five analogs were transferred from 2.1 mm analytical scale LC to a 150 µm scale system. This resulted in a 15-30 fold overall improvement in sensitivity derived from increased signal to noise, three to six fold reduction in injection volumes, and a two to five fold reduction in sample consumption. CONCLUSION: Integrated microscale LC reduces sample consumption while enabling single picomolar quantification for therapeutic and endogenous peptides.
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Análisis Químico de la Sangre/métodos , Dispositivos Laboratorio en un Chip , Péptidos/sangre , Integración de Sistemas , Análisis Químico de la Sangre/instrumentación , Cromatografía Liquida , Humanos , Inyecciones , Modelos Lineales , Espectrometría de Masas , Factores de TiempoRESUMEN
AIM: An ultrasensitive nano UHPLC-ESI-MS/MS method is developed to simultaneously monitor three low-concentration neuromedin-like peptides in microdialysates. RESULTS: Peptide preconcentration and sample desalting is performed online on a trap column. A shallow gradient slope at 300 nl/min on the analytical column maintained at 35°C, followed by two saw-tooth column wash cycles, results in the highest sensitivity and the lowest carryover. The validated method allows the accurate and precise quantification of 0.5 pM neurotensin and neuromedin N (2.5 amol on column), and of 3.0 pM neuromedin B (15.0 amol on column) in in vivo microdialysates without the use of internal standards. CONCLUSION: The assay is an important tool for elucidating the role of these neuromedin-like peptides in the pathophysiology of neurological disorders.
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Cromatografía Liquida/métodos , Microdiálisis/métodos , Neurotensina/metabolismo , Fragmentos de Péptidos/metabolismo , Péptidos/metabolismo , Espectrometría de Masas en Tándem/métodosRESUMEN
Experts Erin Chambers (Waters Corporation), John Kagel (University of North Carolina) and David Bell (Sigma-Aldrich) took part in a recent live panel discussion on overcoming matrix effects as part of the Bioanalysis Zone spotlight on the topic. Here they answer questions from our readers, which were submitted during the discussion and as part of our survey on the topic.
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Técnicas Biosensibles/métodos , Cromatografía Liquida/métodos , Extracción en Fase Sólida/métodos , Técnicas Biosensibles/instrumentación , Cromatografía Liquida/instrumentación , Extracción en Fase Sólida/instrumentaciónRESUMEN
BACKGROUND: This Research article investigates the impact of phospholipid removal and high-performance liquid chromatography column particle size on the accuracy of determining the relative abundance of human metabolites using mass spectrometry peak areas in the context of assessing metabolite abundance for Metabolites in Safety Testing assessment. RESULTS/METHODOLOGY: Plasma samples spiked with 20 compounds, representing ten pairs of drugs and metabolites, were prepared using phospholipid removal plates (Ostro™) or standard protein precipitation techniques and analyzed by liquid chromatography-tandem mass spectrometry using high-performance liquid chromatography columns containing either 2.5 or 3.5 µm particles. Removal of phospholipids significantly reduced matrix effects for samples analyzed on the larger particle size columns while preventing phospholipid build up on the analytical columns. In addition, quantitative accuracy and linearity were not affected by phospholipid removal. CONCLUSION: Both sample preparation strategies and column particle sizes should be considered in order to reduce the inaccuracy as a result of matrix effects in assessing metabolite abundance using mass spectrometry peak areas.
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Cromatografía Líquida de Alta Presión/métodos , Espectrometría de Masas/métodos , Fosfolípidos/metabolismo , Biomarcadores de Tumor , Humanos , Fosfolípidos/análisisRESUMEN
Tricyclic antidepressants have been prescribed for the treatment of depression and other disorders since their discovery in the 1950s but have been replaced in recent decades by newer drugs with more favorable side effect profiles. However, for some patients and conditions, tricyclic antidepressants remain the drug of choice. A fast, sensitive, and robust UPLC-MS/MS method for the monitoring of amitriptyline, nortriptyline, imipramine, doxepin, and desipramine in human urine has been developed using a pre-defined and systematic method development approach. The method was developed using sub-2-µm particle technology, providing a state-of-the-art alternative to older methods. Total cycle time was 2.5min. Human urine samples (200µL) were prepared using an Oasis(®) WCX µElution solid-phase extraction plate, which provided good recovery for all analytes (>92%) and low matrix effects (absolute matrix effects <10%). Standard curves were linear over the range 0.02-250ng/mL with r(2) values>0.994. The method was evaluated against current FDA guidelines and was applied to the analysis of patient samples, including an assessment of incurred sample reanalysis (ISR).
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Antidepresivos Tricíclicos/análisis , Antidepresivos Tricíclicos/orina , Depresión/tratamiento farmacológico , Depresión/orina , Monitoreo de Drogas/métodos , Calibración , Cromatografía Líquida de Alta Presión , Humanos , Estándares de Referencia , Reproducibilidad de los Resultados , Extracción en Fase Sólida , Espectrometría de Masas en TándemRESUMEN
Obtaining maximal sensitivity of nano UHPLC-MS/MS methods is primordial to quantify picomolar concentrations of neuropeptides in microdialysis samples. Since aspecific adsorption of peptides to Eppendorf tubes, pipette tips and UHPLC vials is detrimental for method sensitivity, a strategy is presented to reduce adsorption of these peptides during standard preparation. Within this respect, all procedural steps from dissolution of the lyophilized powder until the injection of the sample onto the system are investigated. Two peptides of the neuromedin family, i.e. neuromedin B and neuromedin N, and a neuromedin N-related neuropeptide, neurotensin, are evaluated. The first part of this study outlines a number of parameters which are known to affect peptide solubility. The main focus of the second part involves the optimization of the sample composition in the UHPLC vial by using design of experiments. Contradictory findings are observed concerning the influence of acetonitrile, salts and matrix components. They are found important for injection of the peptides into the system, but crucially need to be excluded from the dilution solvent. Furthermore, the type of surface material, temperature and the pipetting protocol considerably affect the adsorption phenomenon. Statistical analysis on the results of the central composite design reveals that the highest peptide responses are obtained with the injection solvent consisting of 13.1% V/V ACN and 4.4% V/V FA. This aspect of the optimization strategy can be identified as the main contributor to the gain in method sensitivity. Since the reduction of peptide adsorption and the optimization of the injection solvent resulted in a clear and quantifiable signal of the three peptides, optimization of both issues should be considered in the early stage of method development, in particular when the analysis of low-concentration peptide solutions is envisaged.