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1.
J Sleep Res ; : e14213, 2024 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-38773705

RESUMO

To assess the effectiveness of culturally and linguistically tailored, peer-delivered obstructive sleep apnea education and of social support to increase adherence to physician-recommended obstructive sleep apnea evaluation among blacks. In a two-arm randomised controlled trial, we ascertained the effectiveness of peer-delivered obstructive sleep apnea education in increasing obstructive sleep apnea evaluation among 319 blacks at risk of obstructive sleep apnea (intervention = 159 and control = 160); their average age was 47 ± 12.9 years, and 41% were male. Obstructive sleep apnea risk was assessed with the Apnea Risk Evaluation System questionnaire, administered in community venues. Participants in the intervention arm received tailored obstructive sleep apnea education during a 6 month period; those in the control arm received standard sleep and healthy lifestyle information. Analysis focussed on the effectiveness of peer-delivered obstructive sleep apnea education on adherence to obstructive sleep apnea evaluation, but also considered the role of psychosocial factors. The results showed no significant differences in baseline demographic and clinical measures when contrasting participants in the study arms. The adherence rates for home-based obstructive sleep apnea evaluation in the intervention and control arms were 45.9% and 45.6%, respectively. Overall, participants in both study arms (adherers) who underwent obstructive sleep apnea evaluations were likely to experience a greater level of social support (8.2 ± 2.4 vs. 7.3 ± 2.4; p = 0.06). Moreover, adherers showed greater psychosocial scores (i.e., Dysfunctional Beliefs and Attitudes about Sleep scale, Apnea Beliefs Scale (ABS) (and Apnea Knowledge) compared with non-adherers (6.0 ± 1.8 vs. 4.9 ± 2.2; p = 0.02; 77.0 ± 7.1 vs. 73.2 ± 7.4; p = 0.04, and 6.4 ± 3.1 vs. 7.6 ± 2.4; p = 0.06, respectively). The results of the present randomised controlled trial favoured a potential role of peer-based social support and psychosocial factors, associated with obstructive sleep apnea adherence behaviour.

3.
Eur Ann Otorhinolaryngol Head Neck Dis ; 141(2): 81-85, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38135563

RESUMO

Evaluation of the results of laryngeal transplantation (LT) in humans. Analysis of 3 bibliographic databases with the keywords "larynx, transplantation, autograft". In total, 626 abstracts were read and 25 articles selected. The main objective was to analyze the characteristics of laryngeal transplant patients. The accessory objectives comprised analysis of operative technique, immunosuppressive treatment and results. Four articles were selected for analysis. Two patients were transplanted after total laryngectomy for laryngeal carcinoma and 2 after laryngeal trauma. Three of the 4 patients had true transplantation with arterial, venous and neural microanastomosis. Two patients were decannulated and the tracheostomy tube was maintained in the other 2. Three of the 4 patients had good-quality phonation and could feed without a gastric tube. One patient died of carcinoma progression and 1 patient had to be explanted 14 years after transplantation. The number of LTs reported is too small for scientific determination of the place of this intervention in laryngology. The published results could, at first sight, suggest that the future of LT is uncertain. However, several elements, also suggest that otolaryngologists should continue to take an interest in this technique.


Assuntos
Carcinoma , Neoplasias Laríngeas , Laringe , Humanos , Laringectomia/métodos , Laringe/cirurgia , Laringe/patologia , Neoplasias Laríngeas/cirurgia , Neoplasias Laríngeas/patologia , Fonação , Carcinoma/patologia
4.
Mar Pollut Bull ; 195: 115544, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37717494

RESUMO

The objective of this work was to discover a biochemical pathway to explain the transfer of cadmium, a toxic element, from seawater to cultured mussels. Understanding the intricacies of this transfer is crucial for global mussel crops, as it has the potential to mitigate risks to human health and prevent economic losses in the industry. We focused our investigation on Yal Bay, a typical area with intense mussel aquaculture activity (16,000 t y-1) in the inland sea of southern Chile. Seasonal samples of blue mussels (Mytilus chilensis) were collected and analyzed from September 2014 to December 2015 at two integrated depths (0-5 m and 5-10 m). Diurnal and nocturnal seston, seawater, benthic sediments and decanted suspensions from the water column were recorded. Our findings indicate that nocturnal seston satisfactorily explains the presence of cadmium in Mytilus chilensis aquaculture throughout its annual temporal distribution (Spearman rs = 0.63, p = 0.002).


Assuntos
Mytilus edulis , Mytilus , Animais , Humanos , Mytilus/metabolismo , Cádmio/metabolismo , Aquicultura , Água do Mar
5.
J Am Soc Mass Spectrom ; 34(10): 2107-2116, 2023 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-37650584

RESUMO

Capillary electrophoresis (CE) combined with mass spectrometry (MS) is a powerful analytical technique that utilizes the resolving power of CE and the mass-detection capabilities of MS. In many cases, CE is coupled to MS via a sheath-flow interface (SFI). This interface has a simple design and can be easily constructed; however, it often suffers from issues such as MS signal suppression, interference of MS and CE electrical circuits, and the inability to set an optical point of detection close to the capillary end due to the specific design of the coupling union. In this paper, we describe a novel coupling of CE and MS based upon the open port interface (OPI). The OPI differs from classical sheath flow interfaces by operating at flow rates at least 1 order of magnitude higher. In addition to the flow rate difference, the OPI provides more efficient mixing of the capillary eluates with the transport fluid and thus minimizes MS signal suppression. In this work, we compared the performance of OPI and SFI in a series of capillary isoelectric focusing (cIEF) experiments with 5 pI markers, carbonic anhydrase II and NIST antibody. The evaluation criteria for the comparison of the OPI and SFI were analytical sensitivity, reproducibility, and pI marker linearity. Given the extent of sample dilution in the OPI, we also compared the peak resolution determined using an upstream UV detector to those determined by the downstream mass spectrometer. The results suggested that the OPI configuration reduced signal suppression, with no adverse effect on peak resolution. In addition, the OPI provided better decoupling of the CE and MS potentials as well as reduced signal dependence upon the sheath liquid composition. While these results are preliminary, they suggest that the OPI is a viable approach for CE-MS coupling.

6.
Appetite ; 185: 106509, 2023 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-36871602

RESUMO

The presence of a physical or mental health issue, such as an eating disorder (ED), impacts daily activities, also known as occupations. For example, an overinvestment in body shape and weight undoubtedly can lead to an underinvestment in other, more meaningful occupations. To address ED-related perceptual disturbances, a detailed log of daily time use can pinpoint food-related occupational imbalances. This study aims to characterize the daily occupations associated with EDs. The first specific objective (SO.1) is to categorize and quantify the temporal organization of a typical day's occupations as self-reported by individuals with an ED. The second specific objective (SO.2) is to compare daily occupational time use among people with different ED types. This retrospective study based on time-use research principles was conducted by analyzing data from an anonymized secondary dataset (Loricorps's Databank). Data were collected between 2016 and 2020, from 106 participants, with descriptive analysis completed to determine the average daily time use for each occupation. A series of one-way analyses of variance (ANOVAs) were performed to compare perceived time use in each occupation for participants with different types of EDs. The outcomes show a marked underinvestment in leisure categories compared to the general population. In addition, personal care and productivity can represent the blind dysfunctional occupations (SO.1). Moreover, compared to those with binge eating disorder (BED), individuals with anorexia nervosa (AN) are significantly more invested in occupations that focus explicitly on perceptual disturbances, such as personal care (SO.2). The highlight of this study is the distinction between marked versus blind dysfunctional occupation, which offers specific avenues for clinical intervention.


Assuntos
Anorexia Nervosa , Transtorno da Compulsão Alimentar , Bulimia Nervosa , Transtornos da Alimentação e da Ingestão de Alimentos , Humanos , Estudos Retrospectivos , Transtorno da Compulsão Alimentar/psicologia , Anorexia Nervosa/psicologia , Alimentos , Bulimia Nervosa/psicologia
7.
Anal Chem ; 2023 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-36634199

RESUMO

Mass spectrometry imaging (MSI) has been widely used to discover natural products (NPs) from underexplored microbiological sources. However, the technique is limited by incompatibility with complicated/uneven surface topography and labor-intensive sample preparation, as well as lengthy compound profiling procedures. Here, liquid micro-junction surface sampling probe (LMJ-SSP)-based MSI is used for rapid profiling of natural products from Gram-negative marine bacteria Pseudoalteromonas on nutrient agar media without any sample preparation. A conductance-based autosampling platform with 1 mm spatial resolution and an innovative multivariant analysis-driven method was used to create one hyperspectral image for the sampling area. NP discovery requires general spatial correlation between m/z and colony location but not highly precise spatial resolution. The hyperspectral image was used to annotate different m/z by straightforward color differences without the need to directly interrogate the spectra. To demonstrate the utility of our approach, the rapid analysis of Pseudoalteromonas rubra DSM6842, Pseudoalteromonas tunicata DSM14096, Pseudoalteromonas piscicida JCM20779, and Pseudoalteromonas elyakovii ATCC700519 cultures was directly performed on Agar. Various natural products, including prodiginine and tambjamine analogues, were quickly identified from the hyperspectral image, and the dynamic extracellular environment was shown with compound heatmaps. Hyperspectral visualization-based MSI is an efficient and sensitive strategy for direct and rapid natural product profiling from different Pseudoalteromonas strains.

8.
J Am Soc Mass Spectrom ; 34(1): 75-81, 2023 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-36507839

RESUMO

We developed a structural identification method for eicosanoids with various ring structures using mass spectrometry. We discovered that an electron beam with a kinetic energy of 10 eV, which is in the Electron Impact Excitation of Ions from Organics (EIEIO) regime, cleaved the fatty acids enough to distinguish constitutional and cis/trans isomers. In addition to EIEIO, a comparison to authentic standards using differential mobility spectrometry (DMS) can identify diastereomers, which was difficult by EIEIO. The combination of EIEIO and DMS can provide a high-throughput method to identify complete structures of eicosanoids in mixed samples, which is not allowed with conventional analytical methods though eicosanoids are important signaling molecules in biosystems.


Assuntos
Eicosanoides , Elétrons , Espectrometria de Massas/métodos , Análise Espectral , Íons/química
9.
Anal Chem ; 94(44): 15415-15422, 2022 11 08.
Artigo em Inglês | MEDLINE | ID: mdl-36301587

RESUMO

Large molecules can be generically separated from small ones, though partially and temporarily, in a pressure-driven flow inside a capillary. This transient incomplete separation has been only applied to species with diffusion coefficients different by at least an order of magnitude. Here, we demonstrate, for the first time, the analytical utility of transient incomplete separation for species with close diffusion coefficients. First, we prove in silico that even a small difference in diffusivity can lead to detectable transient incomplete separation of species. Second, we use computer simulation to prove that such a separation can be used for the reliable determination of equilibrium dissociation constant (Kd) of complexes composed of similar-sized molecules. Finally, we demonstrate experimentally the use of this separation for the accurate determination of Kd value for a protein-aptamer complex. We conclude that "accurate constant via transient incomplete separation" (ACTIS) can serve as a reference method for affinity characterization of protein-aptamer binding in solution.


Assuntos
Eletroforese Capilar , Oligonucleotídeos , Eletroforese Capilar/métodos , Simulação por Computador , Ligação Proteica , Oligonucleotídeos/química , Entropia
10.
Artigo em Inglês | BIGG | ID: biblio-1415025

RESUMO

To provide recommendations on the management of urgent obstetrical emergencies outside the maternity ward. A group of 24 experts from the French Society of Emergency Medicine (SFMU), the French Society of Anaesthesia and Intensive Care Medicine (SFAR) and the French College of Gynaecologists and Obstetricians (CNGOF) was convened. Potential conflicts of interest were formally declared at the outset of the guideline development process, which was conducted independently of industry funding. The authors followed the GRADE (Grading of Recommendations Assessment, Development and Evaluation) method to assess the level of evidence in the literature. The potential drawbacks of strong recommendations in the presence of low-level evidence were highlighted. Some recommendations with an insufficient level of evidence were not graded. Eight areas were defined: imminent delivery, postpartum haemorrhage (prevention and management), threat of premature delivery, hypertensive disorders in pregnancy, trauma, imaging, cardiopulmonary arrest, and emergency obstetric training. For each field, the expert panel formulated questions according to the PICO model (population, intervention, comparison, outcomes) and an extensive literature search was conducted. Analysis of the literature and formulation of recommendations were conducted according to the GRADE method. Fifteen recommendations on the management of obstetrical emergencies were issued by the SFMU/SFAR/CNGOF panel of experts, and 4 recommendations from formalised expert recommendations (RFE) established by the same societies were taken up to answer 4 PICO questions dealing with the pre-hospital context. After two rounds of voting and several amendments, strong agreement was reached for all the recommendations. For two questions (cardiopulmonary arrest and inter-hospital transfer), no recommendation could be made. There was significant agreement among the experts on strong recommendations to improve practice in the management of urgent obstetric complications in emergency medicine.


Assuntos
Humanos , Feminino , Gravidez , Complicações na Gravidez/prevenção & controle , Administração dos Cuidados ao Paciente , Medicina de Emergência/normas
11.
J Proteome Res ; 21(10): 2462-2471, 2022 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-36074808

RESUMO

We describe a method to obtain a comprehensive profile of multiple glycosylations in glycopeptide isoforms. We detected a wide range of abundances of various O-glycoforms in isomeric glycopeptides using hot electron capture dissociation (hot ECD) in liquid chromatography-tandem mass spectrometry. To capture low abundant glycosylated species, a prototype of a ZenoTOF 7600 system incorporating an efficient electron-activated dissociation device to perform hot ECD was operated in targeted or scheduled high-resolution multiple reaction monitoring workflows. In addition, Zeno trap pulsing was activated to enhance the sensitivity of the time-of-flight mass spectrometer. Sixty-nine O-glycopeptides of the long O-glycopeptides in tryptic bovine fetuin digest were obtained with a relative abundance range from 100 to 0.2%, which included sialylated glycans with Neu5Ac and Neu5Gc.


Assuntos
Glicopeptídeos , Espectrometria de Massas em Tandem , Animais , Bovinos , Elétrons , Fetuínas , Glicopeptídeos/análise , Polissacarídeos/química , Isoformas de Proteínas , Espectrometria de Massas em Tandem/métodos
12.
J Am Soc Mass Spectrom ; 33(9): 1723-1732, 2022 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-35948044

RESUMO

We report on the dissociation of singly protonated peptides by electrons using electron-activated dissociation (EAD), which comprises electron impact excitation of ions from organics (EIEIO), electronic-excitation dissociation (EED), and electron ionization dissociation (EIoD). Various singly protonated peptides were dissociated using a recently reported fast EAD device. The dissociation can be induced through two pathways: (i) vibrational dissociation similar to collision-activated dissociation (CAD, or collision-induced dissociation, CID) by relaxation from a molecular electronic excited state to high vibrational states; and (ii) radical-induced dissociation where molecular electronic excitation is followed by homolytic cleavage. EAD is complementary to CAD as additional molecular information can be obtained; e.g., fragile PTM moieties, such as glycosylation and sulfation, can be localized. Simultaneously, the energetic production of radical z• fragments enables Leu and Ile discrimination, like in a hot ECD process. Using the fast EAD device, LC-EIEIO-time-of-flight mass spectrometry was applied to a tryptic monoclonal antibody digest containing short singly protonated peptides.


Assuntos
Elétrons , Peptídeos , Íons/química , Espectrometria de Massas/métodos , Peptídeos/química , Processamento de Proteína Pós-Traducional
13.
Gynecol Obstet Fertil Senol ; 50(10): 666-674, 2022 10.
Artigo em Francês | MEDLINE | ID: mdl-35820588

RESUMO

INTRODUCTION: Psycho-social vulnerabilities are a medical risk factor for both fetus and mother. Association between socioeconomic status and prenatal follow-up has been well established and inadequate follow-up is associated with higher morbidity and mortality in women in unfavorable situations. OBJECTIVE: The objective is to identify screening strategies and to describe existing systems for pregnant women in psycho-social vulnerability in French maternity hospitals. MATERIAL AND METHODES: This is a national survey conducted by questionnaire in all French maternities. RESULTS: Screening by means of targeted questions is carried out by 96.7% of maternity units. Early prenatal interviews are offered systematically by 64% of maternity units and access to them is still difficult for women in vulnerable situations. In order to organize care pathways, 28.7% of maternities have a structured unit within their establishment and 81% state that they have mobilizable caregivers. Multidisciplinary meetings for the coordination of the various stakeholders are held by 85.8% of maternity units. Collaboration with networks and associations is emphasized. CONCLUSION: A large proportion of maternities seek to identify women in situation of psycho-social vulnerabilities and to organize care paths. However, the resources implemented still appear insufficient for many maternity units. Each maternity hospital has resources and is developing initiatives to deal with the difficulties of care.


Assuntos
Gestantes , Vulnerabilidade Social , Atenção à Saúde , Feminino , Maternidades , Humanos , Programas de Rastreamento , Gravidez
14.
Anal Chem ; 94(27): 9519-9524, 2022 07 12.
Artigo em Inglês | MEDLINE | ID: mdl-35767324

RESUMO

Molecular stream separation (MSS) is a promising complement for continuous-flow synthesis. MSS is driven by forces exerted on molecules by a field applied at an angle to the stream-carrying flow. MSS has only been performed with a 90° field-to-flow angle because of a rectangular geometry of canonic MSS; the second-order rotational symmetry of a rectangle prevents any other angle. Here, we propose a noncanonic circular geometry for MSS, which better aligns with the polar nature of MSS and allows changing the field-to-flow. We conducted in silico and experimental studies of circular geometry for continuous-flow electrophoresis (CFE, an MSS method). We proved two advantages of circular CFE over its rectangular counterpart. First, circular CFE can support better flow and electric-field uniformity than rectangular CFE. Second, the nonorthogonal field-to-flow orientation, achievable in circular CFE, can result in a higher stream resolution than the orthogonal one. Considering that circular CFE devices are not more complex in fabrication than rectangular ones, we foresee that circular CFE will serve as a new standard and a testbed for the investigation and creation of new CFE modalities.


Assuntos
Eletricidade , Rios , Eletroforese/métodos , Matemática
15.
Anal Chem ; 94(20): 7219-7228, 2022 05 24.
Artigo em Inglês | MEDLINE | ID: mdl-35537093

RESUMO

We describe a new liquid tissue stamping method called poly-synchronous surface extraction (PSSE) that utilizes an omniphobic substrate patterned with hydrophilic surface energy traps (SETs), which when wet with a solvent form a dense microdroplet array. When contacted with a tissue sample, each droplet locally extracts analytes from the tissue surface, which subsequentially can be analyzed by matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-IMS) or ambient ionization-MS techniques. Optimization of the patterned surface with six different solvents was carried out to increase the droplet density, height, and reproducibility of volume deposition. Once optimized, sister slices of a strawberry (Fragaria × ananassa) were spatially extracted using the PSSE technique and the chemical distribution of selected compounds was analyzed with both MALDI-IMS and a lower resolution but faster ambient liquid microjunction surface sampling probe (LMJ-SSP) approach. Heat maps for target analytes for the PSSE approach are compared to those produced using traditional MALDI-IMS analysis. The PSSE method aligned well with direct analysis and demonstrated the potential to increase the speed of ambient MS tissue imaging techniques by decreasing the number of steps required for sample preparation.


Assuntos
Diagnóstico por Imagem , Interações Hidrofóbicas e Hidrofílicas , Reprodutibilidade dos Testes , Solventes , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos
16.
Int J Obstet Anesth ; 50: 103251, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35074676

RESUMO

BACKGROUND: Spinal anesthesia for cesarean delivery is accompanied by hypotension in up to 70% of cases. To date, there is no gold standard for predicting hypotension after spinal anesthesia for cesarean delivery. The Clearsight™ device is a non-invasive system that uses a digital cuff to calculate stroke volume. We hypothesized that stroke volume variation induced with passive leg raising before spinal anesthesia for elective cesarean delivery could predict the occurrence of hypotension. METHODS: We conducted a prospective observational study, including third trimester parturients undergoing elective cesarean delivery with spinal anesthesia. We analyzed the stroke volume variation performance for predicting hypotension. Stroke volume was collected in the semi-recumbent position (baseline) and during passive leg raising before spinal anesthesia. Systolic arterial blood pressure measurement was followed for 15 min after spinal anesthesia. Hypotension was defined as a ≥20% decrease from the baseline measurement. All parturients received appropriate hypotension prophylaxis. RESULTS: Data from 42 parturients were analyzed. Hypotension occurred in 45%. The area-under-the curve for predicting hypotension using the stroke volume variation was 0.83 (95% CI 0.68 to 0.98; P=0.001). The best cut-off value for predicting hypotension was 7%, having a sensitivity of 87% (95% CI 0.70 to 0.99) and a specificity of 83% (95% CI 0.69 to 0.97). CONCLUSION: In our study of third trimester parturients undergoing cesarean delivery and receiving appropriate hypotension prophylaxis, a digital non-invasive monitoring device of stroke volume variation analysis was useful for predicting the occurrence of hypotension after spinal anesthesia.


Assuntos
Anestesia Obstétrica , Raquianestesia , Hipotensão , Anestesia Obstétrica/efeitos adversos , Raquianestesia/efeitos adversos , Estudos de Coortes , Feminino , Humanos , Hipotensão/epidemiologia , Hipotensão/etiologia , Perna (Membro) , Gravidez , Volume Sistólico
17.
Angew Chem Int Ed Engl ; 61(9): e202116794, 2022 02 21.
Artigo em Inglês | MEDLINE | ID: mdl-34963024

RESUMO

Upon development of a workflow to analyze (±)-Verapamil and its metabolites using differential mobility spectrometry (DMS), we noticed that the ionogram of protonated Verapamil consisted of two peaks. This was inconsistent with its metabolites, as each exhibited only a single peak in the respective ionograms. The unique behaviour of Verapamil was attributed to protonation at its tertiary amino moiety, which generated a stereogenic quaternary amine. The introduction of additional chirality upon N-protonation of Verapamil renders four possible stereochemical configurations for the protonated ion: (R,R), (S,S), (R,S), or (S,R). The (R,R)/(S,S) and (R,S)/(S,R) enantiomeric pairs are diastereomeric and thus exhibit unique conformations that are resolvable by linear and differential ion mobility techniques. Protonation-induced chirality appears to be a general phenomenon, as N-protonation of 12 additional chiral amines generated diastereomers that were readily resolved by DMS.


Assuntos
Prótons , Verapamil/análise , Espectrometria de Mobilidade Iônica , Verapamil/metabolismo
18.
Phys Chem Chem Phys ; 23(36): 20607-20614, 2021 Sep 22.
Artigo em Inglês | MEDLINE | ID: mdl-34505849

RESUMO

para-Aminobenzoic acid (PABA) was electrosprayed from mixtures of protic and aprotic solvents, leading to formation of two prototropic isomers in the gas phase whose relative populations depended on the composition of the electrospray solvent. The two ion populations were separated in the gas phase using differential mobility spectrometry (DMS) within a nitrogen-only environment at atmospheric pressure. Under high-field conditions, the two prototropic isomers eluted with baseline signal separation with the N-protonated isomer having a more negative CV shift than the O-protonated isomer, in accord with previous DMS studies. The conditions most favorable for formation and separation of each tautomer were used to trap each prototropic isomer in a quadrupole ion trap for photodissociation action spectroscopy experiments. Spectral interrogation of each prototropic isomer in the UV region (3-6 eV) showed good agreement with previously recorded spectra, although a previously reported band (4.8-5.4 eV) was less intense for the O-protonated isomer in our measured spectrum. Without DMS selection, the measured spectra contained features corresponding to both protonated isomers even when solvent conditions were optimised for formation of a single isomer. Interconversion between protonated isomers within the ion trap was observed when protic ESI solvents were employed, leading to spectral cross contamination even with mobility selection. CCSD vertical excitation energies and vertical gradient (VG) Franck-Condon simulations are presented and reproduce the measured spectral features with near-quantitative agreement, providing supporting evidence for spectral assignments.

19.
Phys Chem Chem Phys ; 23(35): 19892-19900, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34525152

RESUMO

Two prototropic isomers of adenine are formed in an electrospray ion source and are resolved spatially in a differential mobility spectrometer before detection in a triple quadrupole mass spectrometer. Each isomer is gated in CV space before being trapped in the linear ion trap of the modified mass spectrometer, where they are irradiated by the tuneable output of an optical parametric oscillator and undergo photodissociation to form charged fragments with m/z 119, 109, and 94. The photon-normalised intensity of each fragmentation channel is measured and the action spectra for each DMS-gated tautomer are obtained. Our analysis of the action spectra, aided by calculated vibronic spectra and thermochemical data, allow us to assign the two signals in our measured ionograms to specific tautomers of protonated adenine.


Assuntos
Adenina/química , Espectrofotometria Infravermelho , Isomerismo , Fotólise , Prótons , Termodinâmica , Raios Ultravioleta
20.
Anal Chem ; 93(34): 11654-11659, 2021 08 31.
Artigo em Inglês | MEDLINE | ID: mdl-34410698

RESUMO

Accurate Constant via Transient Incomplete Separation (ACTIS) is a new method for finding the equilibrium dissociation constant Kd of a protein-small molecule complex based on transient incomplete separation of the complex from the unbound small molecule in a capillary. This separation is caused by differential transverse diffusion of the complex and the small molecule in a pressure-driven flow. The advection-diffusion processes underlying ACTIS can be described by a system of partial differential equations allowing for a virtual ACTIS instrument to be built and ACTIS to be studied in silico. The previous in silico studies show that large variations in the fluidic system geometry do not affect the accuracy of Kd determination, thus, proving that ACTIS is conceptually accurate. The conceptual accuracy does not preclude, however, instrumental inaccuracy caused by run-to-run signal drifts. Here we report on assembling a physical ACTIS instrument with a fluidic system that mimics the virtual one and proving the absence of signal drifts. Furthermore, we confirmed method ruggedness by assembling a second ACTIS instrument and comparing the results of experiments performed with both instruments in parallel. Despite some unintentional differences between the instruments (caused by tolerances in sizes, positions, etc.) and noticeable differences in their respective separagrams, we found that the Kd values determined for identical samples with these instruments were equal. Conclusively, the fluidic system presented here can serve as a template for reliable ACTIS instrumentation.


Assuntos
Entropia
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