130 research outputs found
Compositional and structural variabilities of MG-rich iron oxide spinels from tuffite.
A maghemita (yFe2O3) de tufito e, excepcionalmente, rica em magnesio, se comparada as comumente encontradas em outros litossistemas maficos. Na tentativa de investigar em detalhes a variabilidade composicional e estrutural desses oxidos naturais de ferro, alguns conjuntos de cristais foram separados de amostras coletadas a diferentes posicoes de um manto de intemperismo de tufito. Esses conjuntos de cristais foram, individualmente, estudados por difracao de raios-X, espectroscopia Mossbauer, medidas de magnetizacao e analise quimica. Da difratometria de raios-X, observou-se que o parametro da celula cubica (ao) varia de 0,834(1) a 0,8412(1) nm. Os valores mais baixos de ao sao caracteristicos de maghemita; os mais altos sao atribuidos a magnetita, mineral magnetico precursor. Os teores de Fe0 alcancam 17 mass % e os valaores de magnetizacao espontanea variam de 8 a 32 J T1 kg1. Os espectros Mossbauer, obtidos com a amostra mantida a temperatura do ambiente, na ausencia de campo magnetico aplicado, sao bastante complexos, om indicacoes de ocorrencia de superposicao de distribuicoes de campo hiperfino, devidas ao Fe3+ e ao ion de valencia mista Fe3+12+. A variabilidade estrutural dos oxidos de ferro, isoestruturais ao espinelio e ricos em Mg e Ti, e, essencialmente, relacionada com os graus variaveis de oxidacao do mineral precursor, a magnetita rica em Mg e Ti
Attenuated total reflection Fourierâtransform infrared ( ATR â FTIR ) spectroscopy to diagnose osteoarthritis in equine serum
Background
Reliable and validated biomarkers for osteoarthritis (OA) are currently lacking.
Objective
To develop an accurate and minimally invasive method to assess OAâaffected horses and provide potential spectral markers indicative of disease.
Study design
Observational, crossâsectional study.
Methods
Our cohort consisted of 15 horses with OA and 48 without clinical signs of the disease, which were used as controls. Attenuated total reflection Fourierâtransform infrared (ATRâFTIR) spectroscopy was used to investigate serum samples (50 ÎŒL) collected from these horses. Spectral processing and multivariate analysis revealed differences and similarities, allowing for detection of spectral biomarkers that discriminated between the two cohorts. A supervised classification algorithm, namely principal component analysis coupled with quadratic discriminant analysis (PCAâQDA), was applied to evaluate the diagnostic accuracy.
Results
Segregation between the two different cohorts, OAâaffected and controls, was achieved with 100% sensitivity and specificity. The six most discriminatory peaks were attributed to proteins and lipids. Four of the spectral peaks were elevated in OA horses, which could be potentially due to an increase in lipids, protein expression levels and collagen, all of which have been previously reported in OA. Two peaks were found decreased and were tentatively assigned to the reduction of proteoglycan content that is observed during OA.
Main limitations
The control group had a wide range of ages and breeds. Preâsymptomatic OA cases were not included. Therefore, it remains unknown whether this test could be also used as an early diagnostic tool.
Conclusions
This spectrochemical approach could provide an accurate and costâeffective blood test, facilitating pointâofâcare diagnosis of equine OA
Distinguishing active from quiescent disease in ANCA-associated vasculitis using attenuated total reflection Fourier-transform infrared spectroscopy
Abstract: The current lack of a reliable biomarker of disease activity in anti-neutrophil cytoplasmic autoantibody (ANCA) associated vasculitis poses a significant clinical unmet need when determining relapsing or persisting disease. In this study, we demonstrate for the first time that attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy offers a novel and functional candidate biomarker, distinguishing active from quiescent disease with a high degree of accuracy. Paired blood and urine samples were collected within a single UK centre from patients with active disease, disease remission, disease controls and healthy controls. Three key biofluids were evaluated; plasma, serum and urine, with subsequent chemometric analysis and blind predictive model validation. Spectrochemical interrogation proved plasma to be the most conducive biofluid, with excellent separation between the two categories on PC2 direction (AUC 0.901) and 100% sensitivity (F-score 92.3%) for disease remission and 85.7% specificity (F-score 92.3%) for active disease on blind predictive modelling. This was independent of organ system involvement and current ANCA status, with similar findings observed on comparative analysis following successful remission-induction therapy (AUC > 0.9, 100% sensitivity for disease remission, F-score 75%). This promising technique is clinically translatable and warrants future larger study with longitudinal data, potentially aiding earlier intervention and individualisation of treatment
ExpressĂŁo de genes relacionados ao metabolismo do nitrogĂȘnio em mudas de CafĂ© arĂĄbica submetidas a dĂ©ficit hĂdrico.
O estresse hĂdrico afeta o metabolismo celular vegetal, incluindo a assimilação do nitrogĂȘnio, com consequĂȘncias drĂĄsticas no crescimento e desenvolvimento da planta. Dessa forma, nesse trabalho foi avaliado a influĂȘncia do dĂ©ficit hĂdrico na transcrição diferencial de genes relacionados ao metabolismo do nitrogĂȘnio. O experimento foi montado em um esquema fatorial 2 x 2, compostos de 2 cultivares de cafĂ© (CatuaĂ Amarelo IAC62 e Mundo Novo IAC379-19) e dois tratamentos (sem dĂ©ficit hĂdrico e com dĂ©ficit hĂdrico), no delineamento em blocos casualizados com trĂȘs repetiçÔes, onde cada parcela era constituĂda por duas plantas. Folhas foram coletadas Ă s 8 e 96 h apĂłs aplicação dos tratamentos e tiveram o RNA extraĂdo. Avaliou-se o perfil transcricional dos genes NIA2 (Nitrate Reductase [NADH] 2), GLN1.3 (Glutamine Synthetase Cytosolic Isozyme 1.3) e GLT1 (Glutamate Synthase 1 [NADH]). Esses genes foram identificados em outras espĂ©cies de plantas como sendo envolvidos na assimilação do nitrogĂȘnio. Observou-se que os trĂȘs genes estudados aumentaram rapidamente a sua expressĂŁo em plantas submetidas ao dĂ©ficit hĂdrico. A cultivar CatuaĂ Amarelo apres entou maior indução do gene NIA2, enquanto que a cultivar Mundo Novo apresentou maior transcrição diferencial dos genes GLN1.3 e GLT1. A maior indução dos genes pode indicar medida adaptativa nessas condiçÔes de estresse. Esses dados sugerem que em condiçÔes de dĂ©ficit hĂdrico o ciclo de assimilação do nitrogĂȘnio na cultura do cafĂ© Ă© rapidamente remodulado
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