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In patients with drug-resistant epilepsy, difficulties in identifying the epileptogenic zone are well known to correlate with poorer clinical outcomes post-surgery. The integration of PET and MRI in the presurgical assessment of pediatric patients likely improves diagnostic precision by confirming or widening treatment targets. PET and MRI together offer superior insights compared to either modality alone. For instance, PET highlights abnormal glucose metabolism, while MRI precisely localizes structural anomalies, providing a comprehensive understanding of the epileptogenic zone. Furthermore, both methodologies, whether utilized through simultaneous PET/MRI scanning or the co-registration of separately acquired PET and MRI data, present unique advantages, having complementary roles in lesional and non-lesional cases. Simultaneous FDG-PET/MRI provides precise co-registration of functional (PET) and structural (MR) imaging in a convenient one-stop-shop approach, which minimizes sedation time and reduces radiation exposure in children. Commercially available fusion software that allows retrospective co-registration of separately acquired PET and MRI images is a commonly used alternative. This review provides an overview and illustrative cases that highlight the role of combining 18F-FDG-PET and MRI imaging and shares the authors' decade-long experience utilizing simultaneous PET/MRI in the presurgical evaluation of pediatric epilepsy.
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Currently, there is a lack of racial/ethnic heterogeneity in research databases, exposing a systematic issue in studies exploring inflammation-mediated diseases, such as hidradenitis suppurativa (HS). HS is a chronic inflammatory skin condition that disrupts normal structure and functioning of terminal hair follicles, resulting in the formation of recurrent abscesses, nodules, and sinus tracts within intertriginous regions. Studies have described higher serum levels of inflammation-mediated C-reactive protein (CRP) in patients with HS, a disease that predominantly affects skin of color (SOC) populations. Herein, we explore the role of CRP levels in the context of HS disease presentation, management, and psychosocial implications in SOC patients to determine existing disparities in research studies.
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Hidradenitis Supurativa , Proteína C-Reactiva/metabolismo , Etnicidad , Folículo Piloso/metabolismo , Humanos , InflamaciónRESUMEN
RATIONALE: Analyte quantitation by mass spectrometry underpins a diverse range of scientific endeavors. The fast-growing field of mass spectrometer development has resulted in several targeted and untargeted acquisition modes suitable for these applications. By characterizing the acquisition methods available on an ion mobility (IM)-enabled orthogonal acceleration time-of-flight (oa-ToF) instrument, the optimum modes for analyte semi-quantitation can be deduced. METHODS: Serial dilutions of commercial metabolite, peptide, or cross-linked peptide analytes were prepared in matrices of human urine or Escherichia coli digest. Each analyte dilution was introduced into an IM separation-enabled oa-ToF mass spectrometer by reversed-phase liquid chromatography and electrospray ionization. Data were acquired for each sample in duplicate using nine different acquisition modes, including four IM-enabled acquisitions modes, available on the mass spectrometer. RESULTS: Five (metabolite) or seven (peptide/cross-linked peptide) point calibration curves were prepared for analytes across each of the acquisition modes. A nonlinear response was observed at high concentrations for some modes, attributed to saturation effects. Two correction methods, one MS1 isotope-correction and one MS2 ion intensity-correction, were applied to address this observation, resulting in an up to twofold increase in dynamic range. By averaging the semi-quantitative results across analyte classes, two parameters, linear dynamic range (LDR) and lower limit of quantification (LLOQ), were determined to evaluate each mode. CONCLUSION: A comparison of the acquisition modes revealed that data-independent acquisition and parallel reaction monitoring methods are most robust for semi-quantitation when considering achievable LDR and LLOQ. IM-enabled modes exhibited sensitivity increases, but a simultaneous reduction in dynamic range required correction methods to recover. These findings will assist users in identifying the optimum acquisition mode for their analyte quantitation needs, supporting a diverse range of applications and providing guidance for future acquisition mode developments.
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Escherichia coli , Péptidos , Calibración , Humanos , Espectrometría de Masas/métodosRESUMEN
Electron-based fragmentation methods have revolutionized biomolecular mass spectrometry, in particular native and top-down protein analysis. Here, we report the use of a new electromagnetostatic cell to perform electron capture dissociation (ECD) within a quadrupole/ion mobility/time-of-flight mass spectrometer. This cell was installed between the ion mobility and time-of-flight regions of the instrument, and fragmentation was fast enough to be compatible with mobility separation. The instrument was already fitted with electron transfer dissociation (ETD) between the quadrupole and mobility regions prior to modification. We show excellent fragmentation efficiency for denatured peptides and proteins without the need to trap ions in the gas phase. Additionally, we demonstrate native top-down backbone fragmentation of noncovalent protein complexes, leading to comparable sequence coverage to what was achieved using the instrument's existing ETD capabilities. Limited collisional ion activation of the hemoglobin tetramer before ECD was reflected in the observed fragmentation pattern, and complementary ion mobility measurements prior to ECD provided orthogonal evidence of monomer unfolding within this complex. The approach demonstrated here provides a powerful platform for both top-down proteomics and mass spectrometry-based structural biology studies.
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Espectrometría de Masas/métodos , Desnaturalización Proteica , Proteínas/química , Secuencia de Aminoácidos , Animales , Bovinos , Humanos , Modelos Moleculares , Multimerización de Proteína , Estructura Cuaternaria de ProteínaRESUMEN
A comprehensive Collision Cross Section (CCS) library was obtained via Travelling Wave Ion Guide mobility measurements through direct infusion (DI). The library consists of CCS and Mass Spectral (MS) data in negative and positive ElectroSpray Ionisation (ESI) mode for 463 and 479 endogenous metabolites, respectively. For both ionisation modes combined, TWCCSN2 data were obtained for 542 non-redundant metabolites. These data were acquired on two different ion mobility enabled orthogonal acceleration QToF MS systems in two different laboratories, with the majority of the resulting TWCCSN2 values (from detected compounds) found to be within 1% of one another. Validation of these results against two independent, external TWCCSN2 data sources and predicted TWCCSN2 values indicated to be within 1-2% of these other values. The same metabolites were then analysed using a rapid reversed-phase ultra (high) performance liquid chromatographic (U(H)PLC) separation combined with IM and MS (IM-MS) thus providing retention time (tr), m/z and TWCCSN2 values (with the latter compared with the DI-IM-MS data). Analytes for which TWCCSN2 values were obtained by U(H)PLC-IM-MS showed good agreement with the results obtained from DI-IM-MS. The repeatability of the TWCCSN2 values obtained for these metabolites on the different ion mobility QToF systems, using either DI or LC, encouraged the further evaluation of the U(H)PLC-IM-MS approach via the analysis of samples of rat urine, from control and methotrexate-treated animals, in order to assess the potential of the approach for metabolite identification and profiling in metabolic phenotyping studies. Based on the database derived from the standards 63 metabolites were identified in rat urine, using positive ESI, based on the combination of tr, TWCCSN2 and MS data.
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Cromatografía Líquida de Alta Presión/métodos , Espectrometría de Movilidad Iónica/métodos , Espectrometría de Masas/métodos , Metaboloma , Orina/química , Aminas/análisis , Animales , Calibración , Aprendizaje Automático , Ratas , Estándares de ReferenciaRESUMEN
OBJECTIVE: Diagnostic criteria from 2002 classify transverse myelitis (TM) as idiopathic or disease associated but predate the discovery of aquaporin-4 (AQP4)-immunoglobulin G (IgG) and myelin oligodendrocyte glycoprotein (MOG)-IgG, which associate with TM. Prior incidence estimates of idiopathic TM (ITM) range from 1 to 6.2 per 1 million. We sought to determine whether the population-based incidence and prevalence of ITM were reduced by testing patients with ITM for AQP4/MOG-IgG and reclassifying seropositive cases as having disease-associated TM. METHODS: For this observational study, we retrospectively identified all cases of incident (January 1, 2003-December 31, 2016) and prevalent (December 31, 2016) ITM in Olmsted County (85% white) by using the Rochester Epidemiology Project medical records linkage system. ITM was defined by the 2002 Transverse MyelitisConsortium Working Group diagnostic criteria. Available sera were tested for AQP4-IgG and MOG-IgG. RESULTS: Twenty-four patients (incident 22, prevalent 17) initially met 2002 ITM criteria (longitudinally extensive TM [LETM] 6). Sera were tested for AQP4-IgG in 22 of 24 (92%) and MOG-IgG in 21 of 24 (88%). Three seropositive cases (AQP4-IgG 2, MOG-IgG 1) were identified and reclassified as having disease-associated TM, accounting for 14% of total incident and 12% of total prevalent cases. AQP4-IgG and MOG-IgG seropositive cases represented 50% (3 of 6) of idiopathic LETM. After reclassification of seropositive patients, the final ITM incidence was 8.6 per 1,000,000 and prevalence was 7.9 per 100,000. Three cases of ITM (14%) subsequently fulfilled multiple sclerosis criteria within the study period. CONCLUSIONS: The availability of AQP4-IgG and MOG-IgG modestly reduced ITM incidence and prevalence, which remained higher than previously reported in this predominantly white population. Incorporation of these biomarkers into future revisions of TM diagnostic criteria should be considered.
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Acuaporina 4/inmunología , Autoanticuerpos/inmunología , Glicoproteína Mielina-Oligodendrócito/inmunología , Mielitis Transversa/epidemiología , Adulto , Anciano , Femenino , Humanos , Inmunoglobulina G/inmunología , Incidencia , Masculino , Persona de Mediana Edad , Mielitis Transversa/clasificación , Mielitis Transversa/inmunología , Prevalencia , Estudios Retrospectivos , Adulto JovenRESUMEN
Tandem mass spectrometry has long been established as a corner stone of analytical and structural chemistry. Fast radical-directed dissociation, produced by electron-transfer and electron-capture dissociation (ETD and ECD) has been shown to provide important complementary information to collision-induced dissociation (CID). We report the first application of extreme-ultraviolet (XUV) lamps to tandem mass spectrometry. These discharge lamps are versatile, robust, and low-cost sources of energetic photons (40-80 nm). The coupling of the discharge lamp with a Waters Synapt G2-Si Q-ToF mass spectrometer is achieved through a specific trapping scheme in the TriWave region of the instrument, allowing efficient irradiation of the precursor ions. Rich radical-directed dissociation was produced for a number of model compounds, providing unique, complementary information to existing dissociation techniques.
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Size, growth, and density have been studied for North American Pacific coast sea urchins Strongylocentrotus purpuratus, S. droebachiensis, S. polyacanthus, Mesocentrotus (Strongylocentrotus) franciscanus, Lytechinus pictus, Centrostephanus coronatus, and Arbacia stellata by various workers at diverse sites and for varying lengths of time from 1956 to present. Numerous peer-reviewed publications have used some of these data but some data have appeared only in graduate theses or the gray literature. There also are data that have never appeared outside original data sheets. Motivation for studies has included fisheries management and environmental monitoring of sewer and power plant outfalls as well as changes associated with disease epidemics. Studies also have focused on kelp restoration, community effects of sea otters, basic sea urchin biology, and monitoring. The data sets presented here are a historical record of size, density, and growth for a common group of marine invertebrates in intertidal and nearshore environments that can be used to test hypotheses concerning future changes associated with fisheries practices, shifts of predator distributions, climate and ecosystem changes, and ocean acidification along the Pacific Coast of North America and islands of the north Pacific. No copyright restrictions apply. Please credit this paper when using the data.
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PURPOSE: The development of a pharmacy resident rotation to expand decentralized clinical pharmacy services is described. SUMMARY: In an effort to align with the initiatives proposed within the ASHP Practice Advancement Initiative, the department of pharmacy at Cleveland Clinic, a 1,400-bed academic, tertiary acute care medical center in Cleveland, Ohio, established a goal to provide decentralized clinical pharmacy services for 100% of patient care units within the hospital. Patient care units that previously had no decentralized pharmacy services were evaluated to identify opportunities for expansion. Metrics analyzed included number of medication orders verified per hour, number of pharmacy dosing consultations, and number of patient discharge counseling sessions. A pilot study was conducted to assess the feasibility of this service and potential resident learning opportunities. A learning experience description was drafted, and feedback was solicited regarding the development of educational components utilized throughout the rotation. Pharmacists who were providing services to similar patient populations were identified to serve as preceptors. Staff pharmacists were deployed to previously uncovered patient care units, with pharmacy residents providing decentralized services on previously covered areas. A rotating preceptor schedule was developed based on geographic proximity and clinical expertise. An initial postimplementation assessment of this resident-driven service revealed that pharmacy residents provided a comparable level of pharmacy services to that of staff pharmacists. Feedback collected from nurses, physicians, and pharmacy staff also supported residents' ability to operate sufficiently in this role to optimize patient care. CONCLUSION: A learning experience developed for pharmacy residents in a large medical center enabled the expansion of decentralized clinical services without requiring additional pharmacist full-time equivalents.
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Hospitales Comunitarios/métodos , Farmacéuticos , Residencias en Farmacia/métodos , Servicio de Farmacia en Hospital/métodos , Desarrollo de Programa/métodos , Prestación Integrada de Atención de Salud/métodos , Prestación Integrada de Atención de Salud/tendencias , Hospitales Comunitarios/tendencias , Humanos , Farmacéuticos/tendencias , Residencias en Farmacia/tendencias , Servicio de Farmacia en Hospital/tendencias , Proyectos PilotoRESUMEN
A snow-line is the region of a protoplanetary disk at which a major volatile, such as water or carbon monoxide, reaches its condensation temperature. Snow-lines play a crucial role in disk evolution by promoting the rapid growth of ice-covered grains. Signatures of the carbon monoxide snow-line (at temperatures of around 20 kelvin) have recently been imaged in the disks surrounding the pre-main-sequence stars TW Hydra and HD163296 (refs 3, 10), at distances of about 30 astronomical units (au) from the star. But the water snow-line of a protoplanetary disk (at temperatures of more than 100 kelvin) has not hitherto been seen, as it generally lies very close to the star (less than 5 au away for solar-type stars). Water-ice is important because it regulates the efficiency of dust and planetesimal coagulation, and the formation of comets, ice giants and the cores of gas giants. Here we report images at 0.03-arcsec resolution (12 au) of the protoplanetary disk around V883 Ori, a protostar of 1.3 solar masses that is undergoing an outburst in luminosity arising from a temporary increase in the accretion rate. We find an intensity break corresponding to an abrupt change in the optical depth at about 42 au, where the elevated disk temperature approaches the condensation point of water, from which we conclude that the outburst has moved the water snow-line. The spectral behaviour across the snow-line confirms recent model predictions: dust fragmentation and the inhibition of grain growth at higher temperatures results in soaring grain number densities and optical depths. As most planetary systems are expected to experience outbursts caused by accretion during their formation, our results imply that highly dynamical water snow-lines must be considered when developing models of disk evolution and planet formation.
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Electrospray ion mobility-mass spectrometry (IM-MS) data show that for some small molecules, two (or even more) ions with identical sum formula and mass, but distinct drift times are observed. In spite of showing their own unique and characteristic fragmentation spectra in MS/MS, no configurational or constitutional isomers are found to be present in solution. Instead the observation and separation of such ions appears to be inherent to their gas-phase behaviour during ion mobility experiments. The origin of multiple drift times is thought to be the result of protonation site isomers ('protomers'). Although some important properties of protomers have been highlighted by other studies, correlating the experimental collision cross-sections (CCSs) with calculated values has proven to be a major difficulty. As a model, this study uses the pharmaceutical compound melphalan and a number of related molecules with alternative (gas-phase) protonation sites. Our study combines density functional theory (DFT) calculations with modified MobCal methods (e.g. nitrogen-based Trajectory Method algorithm) for the calculation of theoretical CCS values. Calculated structures can be linked to experimentally observed signals, and a strong correlation is found between the difference of the calculated dipole moments of the protomer pairs and their experimental CCS separation.
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Top-down sequencing methods are becoming increasingly relevant for protein characterization, in particular electron capture (ECD) and electron transfer dissociation (ETD) which allow for extensive backbone cleavage with minimal side reactions. The ability to obtain sequence-specific fragments while maintaining aspects of the higher-order structure, as well as the position of deuterium labels in H/D exchange, has attracted interest from scientists in the field of structural proteomics. Recently, ETD has also been combined with ion mobility on commercially available quadrupole/time-of-flight instruments, and this implementation paves the way to novel structural studies and investigation of the ETD process itself. In the current work, we investigate the use of ETD for fragmentation of standard peptides and proteins and provide a detailed description of the effect of the parameters controlling the time and efficiency of the reaction. We also highlight how the combination with ion mobility separation after electron transfer provides extended analytical benefits, such as assignment of fragments to a specific charge-reduced state of the precursor.
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Flavoproteínas Transportadoras de Electrones/análisis , Electrones , Espectrometría de Masas/métodos , Animales , Bovinos , Flavoproteínas Transportadoras de Electrones/química , Caballos , Mioglobina/análisis , Mioglobina/química , Sustancia P/análisis , Sustancia P/química , Ubiquitina/análisis , Ubiquitina/químicaRESUMEN
Non-dissociative charge reduction, typically considered to be an unwanted side reaction in electron transfer dissociation (ETD) experiments, can be enhanced significantly in order to reduce the charge state of intact protein complexes to as low as 1+ on a commercially available Q-IM-TOF instrument. This allows for the detection of large complexes beyond 100,000 m/z, while at the same time generating top-down ETD fragments, which provide sequence information from surface-exposed parts of the folded structure. Optimization of the supplemental activation has proven to be crucial in these experiments and the charge-reduced species are most likely the product of both proton transfer (PTR) and non-dissociative electron transfer (ETnoD) reactions that occur prior to the ion mobility cell. Applications of this approach range from deconvolution of complex spectra to the manipulation of charge states of gas-phase ions.
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Proteínas/química , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción/métodos , Electrones , Iones/químicaRESUMEN
Despite recent advances in analytical and computational chemistry, lipid identification remains a significant challenge in lipidomics. Ion-mobility spectrometry provides an accurate measure of the molecules' rotationally averaged collision cross-section (CCS) in the gas phase and is thus related to ionic shape. Here, we investigate the use of CCS as a highly specific molecular descriptor for identifying lipids in biological samples. Using traveling wave ion mobility mass spectrometry (MS), we measured the CCS values of over 200 lipids within multiple chemical classes. CCS values derived from ion mobility were not affected by instrument settings or chromatographic conditions, and they were highly reproducible on instruments located in independent laboratories (interlaboratory RSD < 3% for 98% of molecules). CCS values were used as additional molecular descriptors to identify brain lipids using a variety of traditional lipidomic approaches. The addition of CCS improved the reproducibility of analysis in a liquid chromatography-MS workflow and maximized the separation of isobaric species and the signal-to-noise ratio in direct-MS analyses (e.g., "shotgun" lipidomics and MS imaging). These results indicate that adding CCS to databases and lipidomics workflows increases the specificity and selectivity of analysis, thus improving the confidence in lipid identification compared to traditional analytical approaches. The CCS/accurate-mass database described here is made publicly available.
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Encéfalo/metabolismo , Lípidos/análisis , Espectrometría de Masa de Ion Secundario/métodos , Anciano , Cromatografía Liquida , Humanos , Relación Señal-RuidoRESUMEN
Secondary (i.e., heterotrophic or animal) production is a main pathway of energy flow through an ecosystem as it makes energy available to consumers, including humans. Its estimation can play a valuable role in the examination of linkages between ecosystem functions and services. We found that oil and gas platforms off the coast of California have the highest secondary fish production per unit area of seafloor of any marine habitat that has been studied, about an order of magnitude higher than fish communities from other marine ecosystems. Most previous estimates have come from estuarine environments, generally regarded as one of the most productive ecosystems globally. High rates of fish production on these platforms ultimately result from high levels of recruitment and the subsequent growth of primarily rockfish (genus Sebastes) larvae and pelagic juveniles to the substantial amount of complex hardscape habitat created by the platform structure distributed throughout the water column. The platforms have a high ratio of structural surface area to seafloor surface area, resulting in large amounts of habitat for juvenile and adult demersal fishes over a relatively small footprint of seafloor. Understanding the biological implications of these structures will inform policy related to the decommissioning of existing (e.g., oil and gas platforms) and implementation of emerging (e.g., wind, marine hydrokinetic) energy technologies.
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Ecosistema , Peces/crecimiento & desarrollo , Internacionalidad , Yacimiento de Petróleo y Gas , Animales , California , Geografía , Agua de MarRESUMEN
Metabolomics is a rapidly evolving analytical approach in life and health sciences. The structural elucidation of the metabolites of interest remains a major analytical challenge in the metabolomics workflow. Here, we investigate the use of ion mobility as a tool to aid metabolite identification. Ion mobility allows for the measurement of the rotationally averaged collision cross-section (CCS), which gives information about the ionic shape of a molecule in the gas phase. We measured the CCSs of 125 common metabolites using traveling-wave ion mobility-mass spectrometry (TW-IM-MS). CCS measurements were highly reproducible on instruments located in three independent laboratories (RSD < 5% for 99%). We also determined the reproducibility of CCS measurements in various biological matrixes including urine, plasma, platelets, and red blood cells using ultra performance liquid chromatography (UPLC) coupled with TW-IM-MS. The mean RSD was < 2% for 97% of the CCS values, compared to 80% of retention times. Finally, as proof of concept, we used UPLC-TW-IM-MS to compare the cellular metabolome of epithelial and mesenchymal cells, an in vitro model used to study cancer development. Experimentally determined and computationally derived CCS values were used as orthogonal analytical parameters in combination with retention time and accurate mass information to confirm the identity of key metabolites potentially involved in cancer. Thus, our results indicate that adding CCS data to searchable databases and to routine metabolomics workflows will increase the identification confidence compared to traditional analytical approaches.
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Iones/química , Metabolómica/métodos , Antineoplásicos/metabolismo , Análisis Químico de la Sangre/métodos , Línea Celular Tumoral , Cromatografía Líquida de Alta Presión , Bases de Datos de Compuestos Químicos , Transición Epitelial-Mesenquimal , Gases , Humanos , Espectrometría de Masas , Metaboloma , Reproducibilidad de los Resultados , Urinálisis/métodosRESUMEN
Top-down approaches for the characterization of intact proteins and macromolecular complexes are becoming increasingly popular, since they potentially simplify and speed up the assignment process. Here we demonstrate how, on a commercially available Q-TWIMS-TOF instrument, we performed top-down ETD of the native form of tetrameric alcohol dehydrogenase. We achieved good sequence coverage throughout the first 81 N-terminal amino acids of ADH, with the exception of a loop located on the inside of the protein. This is in agreement with the exposed parts of the natively folded protein according to the crystal structure. Choosing the right precursor charge state and applying supplemental activation were found to be key to obtaining a high ETD fragmentation efficiency. Finally, we briefly discuss opportunities to further increase the performance of ETD based on our results.
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Espectrometría de Masas/métodos , Modelos Moleculares , Subunidades de Proteína/química , Análisis de Secuencia de Proteína/métodos , Alcohol Deshidrogenasa/análisis , Alcohol Deshidrogenasa/química , Secuencia de Aminoácidos , Diseño de Equipo , Proteínas Fúngicas/análisis , Proteínas Fúngicas/química , Datos de Secuencia Molecular , Subunidades de Proteína/análisisRESUMEN
Etanercept is a highly glycosylated therapeutic Fc-fusion protein that contains multiple N- and O-glycosylation sites. An in-depth characterization of the glycosylation of etanercept was carried out using liquid chromatography/mass spectrometry (LC/MS) methods in a systematic approach in which we analyzed the N- and O-linked glycans and located the occupied O-glycosylation sites. Etanercept was first treated with peptide N-glycosidase F to release the N-glycans. The N-glycan pool was labeled with a 2-aminobenzamide (2-AB) fluorescence tag and separated using ultraperformance liquid chromatography-hydrophilic interaction liquid chromatography (UPLC-HILIC). Preliminary structures were assigned using Glycobase. These assignments, which included monosaccharide sequence and linkage information, were confirmed by exoglycosidase array digestions of aliquots of the N-glycan pool. The removal of the N-glycans from etanercept facilitated the selective characterization of O-glycopeptides and enabled the O-glycans to be identified. These were predominantly of the core 1 subtype (HexHexNAc O-structure) attached to Ser/Thr residues. α2â3,6,8,9 sialidase was used to remove the sialic acid residues on the O-glycans allowing the use of an automated LC/MS(E) protocol to identify the O-glycopeptides. Electron-transfer dissociation (ETD) was then used to pinpoint the 12 occupied O-glycosylation sites. The determination of N- and O-glycans and O-glycosylation sites in etanercept provides a basis for future studies addressing the biological importance of specific protein glycosylations in the production of safe and efficacious biotherapeutics.
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Transporte de Electrón/genética , Glicosilación , Inmunoglobulina G/análisis , Inmunoglobulina G/genética , Receptores del Factor de Necrosis Tumoral/análisis , Receptores del Factor de Necrosis Tumoral/genética , Espectrometría de Masas en Tándem/métodos , Secuencia de Aminoácidos , Cromatografía Liquida/métodos , Etanercept , Datos de Secuencia MolecularRESUMEN
RATIONALE: Electron transfer dissociation (ETD) within ion trapping mass spectrometers has proven to be a useful tool for the characterisation of post-translational modifications. In this study, we describe the implementation of ETD upon a modified quadrupole time-of-flight (Q-ToF) system and methods for the analysis of glycoproteins. METHODS: Liquid chromatography electrospray ionisation mass spectrometry (LC/ESI-MS) was performed using a hybrid quadrupole/ion mobility/oa-ToF mass spectrometer equipped with ETD functionality. 1,4-Dicyanobenzene reagent anions necessary for the ETD reaction were generated from a glow discharge region located within the ESI source block. ETD reactions occurred in the stacked ring travelling wave ion guide (located after the quadrupole mass filter and prior to the oa-ToF mass analyser). LC/ETD was performed upon 'super-charged' tryptic glycopeptide ions produced from the recombinant monoclonal antibody trastuzumab. LC/ETD was also performed on ions from the smaller glycopeptides obtained from erythropoietin. RESULTS: ETD performed upon the quadruply 'super-charged' N-linked glycopeptide ions of trastuzumab and the triply charged O-linked glycopeptide ions of erythropoietin provided both glycosylation site assignments and full sequence information, respectively. Tandem mass (MS/MS) spectra employing collision-induced dissociation (CID) were dominated by oxonium product ions hampering full peptide sequence characterisation. CONCLUSIONS: LC/ETD on the Q-ToF system proved effective at characterising a number of different N-linked glyco-forms of the tryptic peptide, EEQYNSTYR, from trastuzumab as well as glyco-forms from the O-linked tryptic peptide, EASIPPDAASAAPLR, from erythropoietin. The data demonstrates that the glycopeptide site heterogeneity of trastuzumab and erythropoietin can be accurately characterised. In addition, the post-column mixing of the super-charging reagent, m-NBA, is an effective method to increase the precursor ion charge state and to improve ETD reaction efficiency.
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Anticuerpos Monoclonales Humanizados/química , Glicoproteínas/química , Espectrometría de Masa por Ionización de Electrospray/métodos , Secuencia de Aminoácidos , Cromatografía Liquida/instrumentación , Cromatografía Liquida/métodos , Electrones , Diseño de Equipo , Glicopéptidos/química , Datos de Secuencia Molecular , Espectrometría de Masa por Ionización de Electrospray/instrumentación , TrastuzumabRESUMEN
PURPOSE: Pharmacy workflow efficiencies achieved through the use of an electronic medication-tracking system are described. METHODS: Medication dispensing turnaround times at the inpatient pharmacy of a large hospital were evaluated before and after transition from manual medication tracking to a Web-based tracking process involving sequential bar-code scanning and real-time monitoring of medication status. The transition was carried out in three phases: (1) a workflow analysis, including the identification of optimal points for medication scanning with hand-held wireless devices, (2) the phased implementation of an automated solution and associated hardware at a central dispensing pharmacy and three satellite locations, and (3) postimplementation data collection to evaluate the impact of the new tracking system and areas for improvement. RESULTS: Relative to the manual tracking method, electronic medication tracking allowed the capture of far more data points, enabling the pharmacy team to delineate the time required for each step of the medication dispensing process and to identify the steps most likely to involve delays. A comparison of baseline and postimplementation data showed substantial reductions in overall medication turnaround times with the use of the Web-based tracking system (time reductions of 45% and 22% at the central and satellite sites, respectively). In addition to more accurate projections and documentation of turnaround times, the Web-based tracking system has facilitated quality-improvement initiatives. CONCLUSION: Implementation of an electronic tracking system for monitoring the delivery of medications provided a comprehensive mechanism for calculating turnaround times and allowed the pharmacy to identify bottlenecks within the medication distribution system. Altering processes removed these bottlenecks and decreased delivery turnaround times.