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1.
J Am Chem Soc ; 146(2): 1388-1395, 2024 01 17.
Artigo em Inglês | MEDLINE | ID: mdl-38176024

RESUMO

Site-specific covalent conjugation offers a powerful tool to identify and understand protein-protein interactions. In this study, we discover that sulfur fluoride exchange (SuFEx) warheads effectively crosslink the Escherichia coli acyl carrier protein (AcpP) with its partner BioF, a key pyridoxal 5'-phosphate (PLP)-dependent enzyme in the early steps of biotin biosynthesis by targeting a tyrosine residue proximal to the active site. We identify the site of crosslink by MS/MS analysis of the peptide originating from both partners. We further evaluate the BioF-AcpP interface through protein crystallography and mutational studies. Among the AcpP-interacting BioF surface residues, three critical arginine residues appear to be involved in AcpP recognition so that pimeloyl-AcpP can serve as the acyl donor for PLP-mediated catalysis. These findings validate an evolutionary gain-of-function for BioF, allowing the organism to build biotin directly from fatty acid biosynthesis through surface modifications selective for salt bridge formation with acidic AcpP residues.


Assuntos
Biotina , Fluoretos , Compostos de Enxofre , Espectrometria de Massas em Tandem , Biotina/metabolismo , Escherichia coli/metabolismo , Ácidos Graxos/metabolismo
2.
Ann Bot ; 133(4): 547-558, 2024 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-38180460

RESUMO

BACKGROUND AND AIMS: The softening of ripening fruit involves partial depolymerization of cell-wall pectin by three types of reaction: enzymic hydrolysis, enzymic elimination (lyase-catalysed) and non-enzymic oxidative scission. Two known lyase activities are pectate lyase and rhamnogalacturonan lyase (RGL), potentially causing mid-chain cleavage of homogalacturonan and rhamnogalacturonan-I (RG-I) domains of pectin respectively. However, the important biological question of whether RGL exhibits action in vivo had not been tested. METHODS: We developed a method for specifically and sensitively detecting in-vivo RGL products, based on Driselase digestion of cell walls and detection of a characteristic unsaturated 'fingerprint' product (tetrasaccharide) of RGL action. KEY RESULTS: In model experiments, potato RG-I that had been partially cleaved in vitro by commercial RGL was digested by Driselase, releasing an unsaturated tetrasaccharide ('ΔUA-Rha-GalA-Rha'), taken as diagnostic of RGL action. This highly acidic fingerprint compound was separated from monosaccharides (galacturonate, galactose, rhamnose, etc.) by electrophoresis at pH 2, then separated from ΔUA-GalA (the fingerprint of pectate lyase action) by thin-layer chromatography. The 'ΔUA-Rha-GalA-Rha' was confirmed as 4-deoxy-ß-l-threo-hex-4-enopyranuronosyl-(1→2)-l-rhamnosyl-(1→4)-d-galacturonosyl-(1→2)-l-rhamnose by mass spectrometry and acid hydrolysis. Driselase digestion of cell walls from diverse ripe fruits [date, sea buckthorn, cranberry, yew (arils), mango, plum, blackberry, apple, pear and strawberry] yielded the same fingerprint compound, demonstrating that RGL had been acting in vivo in these fruits prior to harvest. The 'fingerprint' : (galacturonate + rhamnose) ratio in digests from ripe dates was approximately 1 : 72 (mol/mol), indicating that ~1.4 % of the backbone Rha→GalA bonds in endogenous RG-I had been cleaved by in-vivo RGL action. CONCLUSIONS: The results provide the first demonstration that RGL, previously known from studies of fruit gene expression, proteomic studies and in-vitro enzyme activity, exhibits enzyme action in the walls of soft fruits and may thus be proposed to contribute to fruit softening.


Assuntos
Parede Celular , Frutas , Pectinas , Polissacarídeo-Liases , Polissacarídeo-Liases/metabolismo , Frutas/enzimologia , Parede Celular/metabolismo , Pectinas/metabolismo
3.
Analyst ; 149(8): 2399-2411, 2024 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-38477231

RESUMO

Lignin is a complex heteroaromatic polymer which is one of the most abundant and diverse biopolymers on the planet. It comprises approximately one third of all woody plant matter, making it an attractive candidate as an alternative, renewable feedstock to petrochemicals to produce fine chemicals. However, the inherent complexity of lignin makes it difficult to analyse and characterise using common analytical techniques, proving a hindrance to the utilisation of lignin as a green chemical feedstock. Herein we outline the tracking of lignin degradation by an alkaliphilic laccase in a semi-quantitative manner using a combined chemical analysis approach using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to characterise shifts in chemical diversity and relative abundance of ions, and NMR to highlight changes in the structure of lignin. Specifically, an alkaliphilic laccase was used to degrade an industrially relevant lignin, with compounds such as syringaresinol being almost wholly removed (95%) after 24 hours of treatment. Structural analyses reinforced these findings, indicating a >50% loss of NMR signal relating to ß-ß linkages, of which syringaresinol is representative. Ultimately, this work underlines a combined analytical approach that can be used to gain a broader semi-quantitative understanding of the enzymatic activity of laccases within a complex, non-model mixture.


Assuntos
Furanos , Lacase , Lignanas , Lignina , Lacase/metabolismo , Lignina/química , Lignina/metabolismo , Análise de Fourier , Ciclotrons , Cromatografia Gasosa-Espectrometria de Massas , Espectrometria de Massas/métodos
4.
Anal Chem ; 95(11): 4846-4854, 2023 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-36857539

RESUMO

A desorption electrospray ionization (DESI) source was built and attached to a Bruker 7T SolariX FT-ICR-MS for the in situ analysis of 14 early synthetic dyestuffs. Optimization using silk and wool cloths dyed with rhodamine B concluded that when using a commercial electrospray emitter (part number: 0601815, Bruker Daltonik), a nebulizing gas (N2) pressure of 3.9 bar and a sprayer voltage of 4.5 kV (positive ionization mode) or 4.2 kV (negative ionization mode), a solvent system of 3:1 v/v ACN:H2O, and a sprayer incident angle, α, of 35° gave the highest signal-to-noise ratios on both silk and wool for the samples investigated. The system was applied to modern early synthetic dye references on silk and wool as well as historical samples from the 1893 edition of Adolf Lehne's Tabellarische Übersicht über die künstliche organischen Farbstoffe und ihre Anwendung in Färberei und Zeugdruck [Tabular overview of the synthetic organic dyestuffs and their use in dyeing and printing]. The successful analysis of six chemically different dye families in both negative and positive modes showed the presence of known degradation products and byproducts arising from the original synthetic processes in the historical samples. This study demonstrates the applicability and potential of DESI-MS to the field of historical dye analysis.

5.
Mass Spectrom Rev ; 41(5): 662-694, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-33433028

RESUMO

Mass spectrometry imaging (MSI) combines molecular and spatial information in a valuable tool for a wide range of applications. Matrix-assisted laser desorption/ionization (MALDI) is at the forefront of MSI ionization due to its wide availability and increasing improvement in spatial resolution and analysis speed. However, ionization suppression, low concentrations, and endogenous and methodological interferences cause visualization problems for certain molecules. Chemical derivatization (CD) has proven a viable solution to these issues when applied in mass spectrometry platforms. Chemical tagging of target analytes with larger, precharged moieties aids ionization efficiency and removes analytes from areas of potential isobaric interferences. Here, we address the application of CD on tissue samples for MSI analysis, termed on-tissue chemical derivatization (OTCD). MALDI MSI will remain the focus platform due to its popularity, however, alternative ionization techniques such as liquid extraction surface analysis and desorption electrospray ionization will also be recognized. OTCD reagent selection, application, and optimization methods will be discussed in detail. MSI with OTCD is a powerful tool to study the spatial distribution of poorly ionizable molecules within tissues. Most importantly, the use of OTCD-MSI facilitates the analysis of previously inaccessible biologically relevant molecules through the adaptation of existing CD methods. Though further experimental optimization steps are necessary, the benefits of this technique are extensive.


Assuntos
Processamento de Imagem Assistida por Computador , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos
6.
Chembiochem ; 23(21): e202200322, 2022 11 04.
Artigo em Inglês | MEDLINE | ID: mdl-36017658

RESUMO

Contemporary medicinal chemistry considers fragment-based drug discovery (FBDD) and inhibition of protein-protein interactions (PPI) as important means of expanding the volume of druggable chemical space. However, the ability to robustly identify valid fragments and PPI inhibitors is an enormous challenge, requiring the application of sensitive biophysical methodology. Accordingly, in this study, we exploited the speed and sensitivity of nanoelectrospray (nano-ESI) native mass spectrometry to identify a small collection of fragments which bind to the TPR2AB domain of HOP. Follow-up biophysical assessment of a small selection of binding fragments confirmed binding to the single TPR2A domain, and that this binding translated into PPI inhibitory activity between TPR2A and the HSP90 C-terminal domain. An in-silico assessment of binding fragments at the PPI interfacial region, provided valuable structural insight for future fragment elaboration strategies, including the identification of losartan as a weak, albeit dose-dependent inhibitor of the target PPI.


Assuntos
Proteínas de Choque Térmico HSP70 , Proteínas de Choque Térmico HSP90 , Proteínas de Choque Térmico HSP70/química , Ligação Proteica , Proteínas de Choque Térmico HSP90/química , Descoberta de Drogas , Espectrometria de Massas
7.
Anal Bioanal Chem ; 414(22): 6657-6670, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35881173

RESUMO

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease. Limitations in current diagnosis and screening methods have sparked a search for more specific and conclusive biomarkers. Hyperglycemic conditions generate a plethora of harmful molecules in circulation and within tissues. Oxidative stress generates reactive α-dicarbonyls and ß-unsaturated hydroxyhexenals, which react with proteins to form advanced glycation end products. Mass spectrometry imaging (MSI) enables the detection and spatial localization of molecules in biological tissue sections. Here, for the first time, the localization and semiquantitative analysis of "reactive aldehydes" (RAs) 4-hydroxyhexenal (4-HHE), 4-hydroxynonenal (4-HNE), and 4-oxo-2-nonenal (4-ONE) in the kidney tissues of a diabetic mouse model is presented. Ionization efficiency was enhanced through on-tissue chemical derivatization (OTCD) using Girard's reagent T (GT), forming positively charged hydrazone derivatives. MSI analysis was performed using matrix-assisted laser desorption ionization (MALDI) coupled with Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR). RA levels were elevated in diabetic kidney tissues compared to lean controls and localized throughout the kidney sections at a spatial resolution of 100 µm. This was confirmed by liquid extraction surface analysis-MSI (LESA-MSI) and liquid chromatography-mass spectrometry (LC-MS). This method identified ß-unsaturated aldehydes as "potential" biomarkers of DN and demonstrated the capability of OTCD-MSI for detection and localization of poorly ionizable molecules by adapting existing chemical derivatization methods. Untargeted exploratory distribution analysis of some precursor lipids was also assessed using MALDI-FT-ICR-MSI.


Assuntos
Diabetes Mellitus , Nefropatias Diabéticas , Aldeídos , Animais , Biomarcadores , Camundongos , Camundongos Endogâmicos ICR , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos
8.
J Biol Chem ; 295(46): 15511-15526, 2020 11 13.
Artigo em Inglês | MEDLINE | ID: mdl-32878987

RESUMO

Encapsulated ferritins belong to the universally distributed ferritin superfamily, whose members function as iron detoxification and storage systems. Encapsulated ferritins have a distinct annular structure and must associate with an encapsulin nanocage to form a competent iron store that is capable of holding significantly more iron than classical ferritins. The catalytic mechanism of iron oxidation in the ferritin family is still an open question because of the differences in organization of the ferroxidase catalytic site and neighboring secondary metal-binding sites. We have previously identified a putative metal-binding site on the inner surface of the Rhodospirillum rubrum encapsulated ferritin at the interface between the two-helix subunits and proximal to the ferroxidase center. Here we present a comprehensive structural and functional study to investigate the functional relevance of this putative iron-entry site by means of enzymatic assays, MS, and X-ray crystallography. We show that catalysis occurs in the ferroxidase center and suggest a dual role for the secondary site, which both serves to attract metal ions to the ferroxidase center and acts as a flow-restricting valve to limit the activity of the ferroxidase center. Moreover, confinement of encapsulated ferritins within the encapsulin nanocage, although enhancing the ability of the encapsulated ferritin to undergo catalysis, does not influence the function of the secondary site. Our study demonstrates a novel molecular mechanism by which substrate flux to the ferroxidase center is controlled, potentially to ensure that iron oxidation is productively coupled to mineralization.


Assuntos
Proteínas de Bactérias/metabolismo , Ceruloplasmina/metabolismo , Metais/metabolismo , Rhodospirillum rubrum/metabolismo , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Domínio Catalítico , Ceruloplasmina/química , Ceruloplasmina/genética , Cristalografia por Raios X , Ferro/química , Ferro/metabolismo , Metais/química , Mutagênese Sítio-Dirigida , Oxirredução , Conformação Proteica , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/química , Proteínas Recombinantes/isolamento & purificação , Zinco/química , Zinco/metabolismo
9.
Neuroimage ; 234: 117999, 2021 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-33789133

RESUMO

Dopamine has direct and complex vasoactive effects on cerebral circulation. Catechol-O-methyltransferase (COMT) regulates cortical dopamine, and its activity can be influenced both genetically and pharmacologically. COMT activity influences the functional connectivity of the PFC at rest, as well as its activity during task performance, determined using blood oxygen level-dependent (BOLD) fMRI. However, its effects on cerebral perfusion have been relatively unexplored. Here, 76 healthy males, homozygous for the functional COMT Val158Met polymorphism, were administered either the COMT inhibitor tolcapone or placebo in a double-blind, randomised design. We then assessed regional cerebral blood flow at rest using pulsed arterial spin labelling. Perfusion was affected by both genotype and drug. COMT genotype affected frontal regions (Val158 > Met158), whilst tolcapone influenced parietal and temporal regions (placebo > tolcapone). There was no genotype by drug interaction. Our data demonstrate that lower COMT activity is associated with lower cerebral blood flow, although the regions affected differ between those affected by genotype compared with those altered by acute pharmacological inhibition. The results extend the evidence for dopaminergic modulation of cerebral blood flow. Our findings also highlight the importance of considering vascular effects in functional neuroimaging studies, and of exercising caution in ascribing group differences in BOLD signal solely to altered neuronal activity if information about regional perfusion is not available.


Assuntos
Inibidores de Catecol O-Metiltransferase/farmacologia , Catecol O-Metiltransferase/metabolismo , Circulação Cerebrovascular/fisiologia , Imageamento por Ressonância Magnética/métodos , Imagem de Perfusão/métodos , Marcadores de Spin , Adolescente , Adulto , Circulação Cerebrovascular/efeitos dos fármacos , Dopamina/metabolismo , Humanos , Masculino , Tolcapona/farmacologia , Adulto Jovem
10.
Ann Bot ; 128(5): 511-525, 2021 09 07.
Artigo em Inglês | MEDLINE | ID: mdl-34111288

RESUMO

BACKGROUND AND AIMS: The programmed softening occurring during fruit development requires scission of cell wall polysaccharides, especially pectin. Proposed mechanisms include the action of wall enzymes or hydroxyl radicals. Enzyme activities found in fruit extracts include pectate lyase (PL) and endo-polygalacturonase (EPG), which, in vitro, cleave de-esterified homogalacturonan in mid-chain by ß-elimination and hydrolysis, respectively. However, the important biological question of whether PL exhibits action in vivo had not been tested. METHODS: We developed a method for specifically and sensitively detecting in-vivo PL products, based on Driselase digestion of cell wall polysaccharides and detection of the characteristic unsaturated product of PL action. KEY RESULTS: In model in-vitro experiments, pectic homogalacturonan that had been partially cleaved by commercial PL was digested to completion with Driselase, releasing an unsaturated disaccharide ('ΔUA-GalA'), taken as diagnostic of PL action. ΔUA-GalA was separated from saturated oligogalacturonides (EPG products) by electrophoresis, then subjected to thin-layer chromatography (TLC), resolving ΔUA-GalA from higher homologues. The ΔUA-GalA was confirmed as 4-deoxy-ß-l-threo-hex-4-enopyranuronosyl-(1→4)-d-galacturonic acid by NMR spectroscopy. Driselase digestion of cell walls from ripe fruits of date (Phoenix dactylifera), pear (Pyrus communis), rowan (Sorbus aucuparia) and apple (Malus pumila) yielded ΔUA-GalA, demonstrating that PL had been acting in vivo in these fruits prior to harvest. Date-derived ΔUA-GalA was verified by negative-mode mass spectrometry, including collision-induced dissociation (CID) fragmentation. The ΔUA-GalA:GalA ratio from ripe dates was roughly 1:20 (mol mol-1), indicating that approx. 5 % of the bonds in endogenous homogalacturonan had been cleaved by in-vivo PL action. CONCLUSIONS: The results provide the first demonstration that PL, previously known from studies of fruit gene expression, proteomic studies and in-vitro enzyme activity, exhibits enzyme action in the walls of soft fruits and may thus be proposed to contribute to fruit softening.


Assuntos
Frutas , Phoeniceae , Parede Celular , Pectinas , Polissacarídeo-Liases , Proteômica
11.
Arch Biochem Biophys ; 681: 108240, 2020 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-31883928

RESUMO

Although l-ascorbate (vitamin C) is an important biological antioxidant, its degradation pathways in vivo remain incompletely characterised. Ascorbate is oxidised to dehydroascorbic acid, which can be either hydrolysed to diketogulonate (DKG) or further oxidised. DKG can be further degraded, oxidatively or non-oxidatively. Here we characterise DKG products formed non-enzymically and non-oxidatively at 20 °C and at a slightly acidic pH typical of the plant apoplast. High-voltage electrophoresis revealed at least five products, including two novel CPLs (epimers of 2-carboxy-l-threo-pentonolactone), which slowly interconverted with CPA (2-carboxy-l-threo-pentonate). One of the two CPLs has an exceptionally low pKa. The CPL structures were supported by MS [(C6H7O7)-] and by 1H and 13C NMR spectroscopy. Xylonate and its lactone also appeared. Experiments with [1-14C]DKG showed that all five products (including the 5-carbon xylonate and its lactone) retained DKG's carbon-1; therefore, most xylonate arose by decarboxylation of CPLs or CPA, one of whose -COOH groups originates from C-2 or C-3 of DKG after a 'benzilic acid rearrangement'. Since CPLs appeared before CPA, a DKG lactone is probably the main species undergoing this rearrangement. CPA and CPL also form non-enzymically in vivo, where they may be useful to researchers as 'fingerprints', or to organisms as 'signals', indicating a non-oxidative, slightly acidic biological compartment.


Assuntos
Ácido Desidroascórbico/metabolismo , Ácido 2,3-Dicetogulônico/metabolismo , Ácido Ascórbico/metabolismo , Isomerismo , Lactonas/metabolismo , Oxirredução , Água/metabolismo
12.
Rapid Commun Mass Spectrom ; 34(2): e8570, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31479545

RESUMO

RATIONALE: A key element of studies that utilise ion mobility mass spectrometry (IM-MS) under native electrospray conditions for the analysis of protein-ligand binding is the maintenance of the native conformation of a protein during the removal of bulk solvent. Ruotolo and co-workers have demonstrated that the binding and subsequent dissociation of the anionic component of inorganic salts stabilise native protein conformations in the gas phase. In this study, we investigated the effect that organic acid fragments identified from a fragment-based drug discovery (FBDD) campaign might have on the gas-phase stability of carbonic anhydrase II (CA II). METHODS: We utilised native IM-MS to monitor changes in the conformation of CA II in the absence and presence of four acidic fragments. By performing a series of collision-induced unfolding (CIU) experiments we determined the effect of fragment binding on the gas-phase stability of CA II. RESULTS: Binding and dissociation of acidic fragments result in increased gas-phase stability of CA II. CFU experiments revealed that the native-like compact gas-phase conformation of the protein is stable with higher degree of pre-activation when bound to a series of acidic fragments. Importantly, although acetate was present in high concentrations, the stabilising effect was not observed without the addition of the acidic fragments. CONCLUSIONS: Binding and subsequent dissociation of acidic fragments from CA II significantly delayed CIU in a manner which is probably analogous to the effect of inorganic anions. Furthermore, we saw a slightly altered stabilising effect between the different fragments investigated in this study. This suggests that the prevention of CIU by organic acids may be tuneable to specific properties of a bound ligand. These observations may open avenues to exploit IM-MS as a screening platform in FBDD.


Assuntos
Ácidos/química , Anidrase Carbônica II/química , Humanos , Espectrometria de Mobilidade Iônica , Ligantes , Conformação Proteica
13.
Biochem J ; 476(6): 975-989, 2019 03 22.
Artigo em Inglês | MEDLINE | ID: mdl-30837306

RESUMO

Ferritins are a large family of intracellular proteins that protect the cell from oxidative stress by catalytically converting Fe(II) into less toxic Fe(III) and storing iron minerals within their core. Encapsulated ferritins (EncFtn) are a sub-family of ferritin-like proteins, which are widely distributed in all bacterial and archaeal phyla. The recently characterized Rhodospirillum rubrum EncFtn displays an unusual structure when compared with classical ferritins, with an open decameric structure that is enzymatically active, but unable to store iron. This EncFtn must be associated with an encapsulin nanocage in order to act as an iron store. Given the wide distribution of the EncFtn family in organisms with diverse environmental niches, a question arises as to whether this unusual structure is conserved across the family. Here, we characterize EncFtn proteins from the halophile Haliangium ochraceum and the thermophile Pyrococcus furiosus, which show the conserved annular pentamer of dimers topology. Key structural differences are apparent between the homologues, particularly in the centre of the ring and the secondary metal-binding site, which is not conserved across the homologues. Solution and native mass spectrometry analyses highlight that the stability of the protein quaternary structure differs between EncFtn proteins from different species. The ferroxidase activity of EncFtn proteins was confirmed, and we show that while the quaternary structure around the ferroxidase centre is distinct from classical ferritins, the ferroxidase activity is still inhibited by Zn(II). Our results highlight the common structural organization and activity of EncFtn proteins, despite diverse host environments and contexts within encapsulins.


Assuntos
Proteínas Arqueais/química , Proteínas de Bactérias/química , Ferritinas/química , Myxococcales/química , Pyrococcus furiosus/química , Rhodospirillum rubrum/química , Domínios Proteicos , Homologia Estrutural de Proteína , Relação Estrutura-Atividade
14.
Surgeon ; 18(6): 354-359, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32184069

RESUMO

INTRODUCTION: Approximately 17% of the Scottish population lives in a remote or rural location. Current research is contradictory as to whether living a rural location leads to poorer outcomes or affects survival from colorectal cancer (CRC). We aimed to assess if living in a rural location influences outcome of CRC patients in 21st century UK medicine. METHODS: A prospective single-centre observational study was conducted. All patients who underwent resection for colorectal cancer 2005-2016 in NHS Grampian were included. Patients were split into two groups for comparison (urban post-code vs rural) using the Scottish government two-tier classification system. Tumour location, one-year survival, lymph node involvement and extra-mural vascular invasion was recorded and compared between the groups. RESULTS: Of 2463 patients, 843 (34.2%) lived in a rural area. Rural patients were more likely to be detected through screening (17.4% versus 14.6%, p = 0.04). There were no differences in pathology between rural and urban groups if detected through screening. However, rural patients detected through symptomatic pathways were more likely to be node positive p = 0.015. On multivariable analysis, rurality did not independently predict for node positive presentation. Furthermore, there were no differences in cumulative survival between the two groups. CONCLUSION: Although there were some differences in pathological characteristics between rural and urban patients, place of residence did not independently predict for outcome in this cohort. Rurality had previously been shown to impact on outcome up to 20 years ago. Improvements in infrastructure and rural healthcare may have influenced this change.


Assuntos
Neoplasias Colorretais/diagnóstico , Neoplasias Colorretais/epidemiologia , Saúde da População Rural/estatística & dados numéricos , Saúde da População Urbana/estatística & dados numéricos , Adulto , Idoso , Neoplasias Colorretais/terapia , Feminino , Seguimentos , Acessibilidade aos Serviços de Saúde , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Escócia , Taxa de Sobrevida
15.
Anal Chem ; 91(15): 9522-9529, 2019 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-31265253

RESUMO

Multicellular tumor spheroids (MTS) are a well-established model system for drug development and are a valuable in vitro research tool for use prior to employing animal models. These 3D-cell cultures are thought to display chemical gradients of oxygen and nutrients throughout their structure, giving rise to distinct microenvironments in radial layers, thus, mimicking the pathophysiological environment of a tumor. Little is known about the localized distributions of metabolites within these microenvironments. To address this, here we utilize high spectral resolution Fourier-transform ion cyclotron resonance (FT-ICR), MALDI mass spectrometry imaging (MSI) to image the distribution of endogenous metabolites in breast cancer MCF-7 spheroids. We show that known specific metabolite markers (adenosine phosphates and glutathione) indicate that the central region of these cell culture models experiences increased hypoxic and oxidative stress. By using discriminatory analysis, we have identified which m/z values localize toward the outer proliferative or central hypoxic regions of an MTS. Elemental formulae were assigned with sub-ppm mass accuracy, allowing metabolite assignment. Using this information, we have mapped these metabolites back to distinct pathways to improve our understanding of the molecular environment and biochemistry of these tumor models.


Assuntos
Esferoides Celulares/metabolismo , Microambiente Tumoral , Biomarcadores Tumorais , Ciclotrons , Análise de Fourier , Humanos , Células MCF-7 , Metabolômica
16.
Osteoarthritis Cartilage ; 27(10): 1408-1419, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31096046

RESUMO

OBJECTIVE: To systematically review the minimal clinically important difference (MCID) and patient acceptable symptom state (PASS) estimates in pain and function measured using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) in patients who underwent primary total knee replacement (TKR) and primary total hip replacement (THR). DESIGN: The study was carried out following PRISMA recommendations. We searched five electronic databases. Two reviewers independently screened titles, abstracts and full-text papers using a priori inclusion/exclusion criteria. Data were extracted by two independent reviewers. Data were synthesized, with WOMAC values converted to 0-100 scores (0 = best, 100 = worst). RESULTS: Thirteen studies were included. Research methods used to calculate MCIDs and PASS varied across studies (e.g., using anchor-based or distribution methods, wording of anchor questions within anchor-based methods). Baseline WOMAC scores also varied across studies. Across studies and methods, MCIDs for the WOMAC in patients undergoing TKR ranged from 13.3 to 36.0 for pain and 1.8-33.0 for function; values for WOMAC in THR ranged from 8.3 to 41.0 for pain and from 9.7 to 34.0 for function. PASS cut-offs for TKR ranged from 25.0 to 28.6 for pain and 32.3-36.7 for function, and cut-offs for THR from 15.0 to 30.6 for pain and 28.0-42.0 for function. CONCLUSION: Although the WOMAC is a commonly used measure for a single condition, the variability in methods used to calculate MCID and PASS estimates results in a range of values across studies making it unclear whether values reported in the literature can be applied with confidence. Future research is needed to refine methods used to calculate MCIDs and PASS.


Assuntos
Artroplastia de Quadril , Artroplastia do Joelho , Diferença Mínima Clinicamente Importante , Osteoartrite do Quadril/cirurgia , Osteoartrite do Joelho/cirurgia , Humanos , Ontário , Osteoartrite do Quadril/diagnóstico , Osteoartrite do Joelho/diagnóstico , Medição da Dor , Avaliação de Sintomas
17.
Osteoarthritis Cartilage ; 27(5): 788-804, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30668988

RESUMO

OBJECTIVE: Consistent evidence-practice gaps in osteoarthritis (OA) care are observed in primary care settings globally. Building workforce capacity to deliver high-value care requires a contemporary understanding of barriers to care delivery. We aimed to explore barriers to OA care delivery among clinicians and students. DESIGN: A cross-sectional, multinational study sampling clinicians (physiotherapists, primary care nurses, general practitioners (GPs), GP registrars; total possible denominator: n = 119,735) and final-year physiotherapy and medical students (denominator: n = 2,215) across Australia, New Zealand and Canada. Respondents answered a survey, aligned to contemporary implementation science domains, which measured barriers to OA care using categorical and free-text responses. RESULTS: 1886 clinicians and 1611 students responded. Items within the domains 'health system' and 'patient-related factors' represented the most applicable barriers experienced by clinicians (25-42% and 20-36%, respectively), whereas for students, 'knowledge and skills' and 'patient-related factors' (16-24% and 19-28%, respectively) were the most applicable domains. Meta-synthesis of qualitative data highlighted skills gaps in specific components of OA care (tailoring exercise, nutritional/overweight management and supporting positive behaviour change); assessment, measurement and monitoring; tailoring care; managing case complexity; and translating knowledge to practice (especially among students). Other barriers included general infrastructure limitations (particularly related to community facilities); patient-related factors (e.g., beliefs and compliance); workforce-related factors such as inconsistent care and a general knowledge gap in high-value care; and system and service-level factors relating to financing and time pressures, respectively. CONCLUSIONS: Clinicians and students encounter barriers to delivery of high-value OA care in clinical practice/training (micro-level); within service environments (meso-level); and within the health system (macro-level).


Assuntos
Atitude do Pessoal de Saúde , Atenção à Saúde/normas , Pessoal de Saúde/psicologia , Osteoartrite/terapia , Estudantes/psicologia , Adulto , Competência Clínica , Estudos Transversais , Atenção à Saúde/organização & administração , Escolaridade , Feminino , Pesquisas sobre Atenção à Saúde , Acessibilidade aos Serviços de Saúde , Humanos , Masculino , Pessoa de Meia-Idade
18.
Environ Manage ; 64(1): 27-39, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31127315

RESUMO

Coastal environments face mounting pressures from development and resource use, and appropriate coastal management supports long-term ecosystem functionality, viability and delivery of goods and services. Integrated coastal management (ICM) is advocated as a best practice approach to achieving this, but comes with its own challenges. Given the diverse nature of the coastal environment and the goods and services it offers, its management is complex. In South Africa, this is exacerbated by the legislative framework which delegates numerous responsibilities to local government without providing financial or human capacity to meet these requirements. These challenges have resulted in the development of a number of guidelines in support of achieving ICM objectives. This paper focuses on one coastal region in South Africa, KwaZulu-Natal, which is grappling with coastal management issues, including the implementation thereof for a 580 km coast with 76 estuaries. It considers the progressive, iterative development of an innovative Decision Support info-portal to assist local coastal managers in the absence of human capacity support and tools. Stakeholders were asked to complete a survey to provide feedback on their impression of the tool, its functions and usability. This facilitated stakeholder input into the info-portal development, which was essential in ensuring that the end product is useable, relevant and supportive of coastal management and decision making. Since its public release, the Decision Support info-portal has been implemented and utilised by government officials for both ongoing management and emergency response within the KZN province.


Assuntos
Ecossistema , Estuários , Tomada de Decisões , Meio Ambiente , Humanos , África do Sul
19.
Gut ; 67(2): 299-306, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-27789658

RESUMO

OBJECTIVES: Colorectal polyp cancers present clinicians with a treatment dilemma. Decisions regarding whether to offer segmental resection or endoscopic surveillance are often taken without reference to good quality evidence. The aim of this study was to develop a treatment algorithm for patients with screen-detected polyp cancers. DESIGN: This national cohort study included all patients with a polyp cancer identified through the Scottish Bowel Screening Programme between 2000 and 2012. Multivariate regression analysis was used to assess the impact of clinical, endoscopic and pathological variables on the rate of adverse events (residual tumour in patients undergoing segmental resection or cancer-related death or disease recurrence in any patient). These data were used to develop a clinically relevant treatment algorithm. RESULTS: 485 patients with polyp cancers were included. 186/485 (38%) underwent segmental resection and residual tumour was identified in 41/186 (22%). The only factor associated with an increased risk of residual tumour in the bowel wall was incomplete excision of the original polyp (OR 5.61, p=0.001), while only lymphovascular invasion was associated with an increased risk of lymph node metastases (OR 5.95, p=0.002). When patients undergoing segmental resection or endoscopic surveillance were considered together, the risk of adverse events was significantly higher in patients with incomplete excision (OR 10.23, p<0.001) or lymphovascular invasion (OR 2.65, p=0.023). CONCLUSION: A policy of surveillance is adequate for the majority of patients with screen-detected colorectal polyp cancers. Consideration of segmental resection should be reserved for those with incomplete excision or evidence of lymphovascular invasion.


Assuntos
Algoritmos , Pólipos do Colo/patologia , Pólipos do Colo/cirurgia , Neoplasias Colorretais/patologia , Neoplasias Colorretais/cirurgia , Recidiva Local de Neoplasia/diagnóstico , Conduta Expectante , Idoso , Vasos Sanguíneos/patologia , Colectomia , Colonoscopia , Intervalo Livre de Doença , Detecção Precoce de Câncer , Medicina Baseada em Evidências , Feminino , Humanos , Metástase Linfática , Vasos Linfáticos/patologia , Masculino , Invasividade Neoplásica , Neoplasia Residual , Fatores de Risco , Escócia , Taxa de Sobrevida
20.
Anal Chem ; 90(19): 11265-11272, 2018 10 02.
Artigo em Inglês | MEDLINE | ID: mdl-30188688

RESUMO

Fourier transform mass spectrometry (FTMS) is widely used to characterize the chemical complexity of mixtures, such as natural organic matter (NOM), petroleum, and agri-food products (including Scotch whisky). Although electrospray ionization (ESI) is by far the most widely used ionization source in these studies, other ionization techniques are available and may offer complementary information. In a recent study, we found matrix free laser desorption/ionization (LDI) to be effective for the analysis of Suwannee river fulvic acid (SRFA), and to provide complementary chemical insights. In this study, LDI along with atmospheric pressure photoionization (APPI) and atmospheric pressure chemical ionization (APCI) were compared to ESI for the analysis of Scotch whisky. High mass accuracy (54 ppb, mean) allowed for the assignment of 86% of peaks, with 3993 unique molecular formulas identified from four representative samples analyzed. All four ionization techniques, performed in negative mode, identified thousands of formulas. Many were unique to each ionization source, while 699 formulas were common to all techniques. Ions were identified in both deprotonated and radical anion forms. Our study highlights the importance of a multi-ionization source approach; we recommend that analysis of complex mixtures, especially novel ones, should not be limited solely to ESI.

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