Littérature scientifique sur le sujet « Fattor permeabilità »
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Articles de revues sur le sujet "Fattor permeabilità"
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Moriconi, Luigi. « Terapia della sindrome nefrosica idiopatica : ruolo delle tecniche aferetiche ». Giornale di Clinica Nefrologica e Dialisi 25, no 4_suppl (23 juillet 2013) : S41—S45. http://dx.doi.org/10.33393/gcnd.2013.1090.
Texte intégralRésumé :
La Sindrome Nefrosica Idiopatica (Idiopathic Nephrotic Syndrome, INS) ricorre essenzialmente in presenza di due glomerulopatie: la MCN (Minimal Change Nephropathy) e la FSGS (Focal Segmental Glomerular Sclerosis). La prima ha un decorso più benigno ed è più frequente nei bambini, mentre la seconda ha un decorso più severo, può portare a Insufficienza Renale Cronica Terminale e può re-cidivare nel trapianto. Soprattutto per la FSGS sono state identificate possibili eziologie virali o genetiche, oltre a forme secondarie in corso di altre malattie, per cui non è semplice classificare queste glomerulopatie. Le forme ricorrenti nel rene trapiantato costituiscono un gruppo più omogeneo. I fattori che sembrano essere comuni alla MCN e alla FSGS, anche se maggiormente espressi e studiati nella seconda, sono la lesione glomerulare caratterizzante a carico dei podociti, e il frequente riscontro di sostanze circolanti, definite fattori di permeabilità (PFs), capaci di indurre proteinuria. Corticosteroidi e Immunosoppressori sono la terapia standard della INS. Tuttavia, la presenza di casi farmaco-resistenti e l'identificazione di alcuni PFs circolanti hanno consentito di utilizzare nuove terapie dirette a bloccare la sintesi o l'azione di queste molecole e hanno fornito un ulteriore razionale alla loro rimozione mediante plasmaferesi convenzionale (PEX) o aferesi selettiva.
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Chen, Gang, Shiguang Xu, Chunxue Liu, Lei Lu et Liang Guo. « Groundwater flow simulation and its application in GaoSong ore field, China ». Journal of Water and Climate Change 10, no 2 (14 septembre 2018) : 276–84. http://dx.doi.org/10.2166/wcc.2018.182.
Texte intégralRésumé :
Abstract Mine water inrush is one of the important factors threatening safe production in mines. The accurate understanding of the mine groundwater flow field can effectively reduce the hazards of mine water inrush. Numerical simulation is an important method to study the groundwater flow field. This paper numerically simulates the groundwater seepage field in the GaoSong ore field. In order to ensure the accuracy of the numerical model, the research team completed 3,724 field fissure measurements in the study area. The fracture measurement results were analyzed using the GEOFRAC method and the whole-area fracture network data were generated. On this basis, the rock mass permeability coefficient tensor of the aquifer in the study area was calculated. The tensor calculation results are used in the numerical model of groundwater flow. After calculation, the obtained numerical model can better represent the groundwater seepage field in the study area. In addition, we designed three different numerical models for calculation, mainly to explore the influence of the tensor assignment of permeability coefficient on the calculation results of water yield of the mine. The results showed that irrational fathom tensor assignment would cause a significant deviation in calculation results.
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Ruthes, Juliane Mônica, Júlio Caetano Tomazoni, Elisete Guimarães et Tayoná Cristina Gomes. « Propriedades do Solo da Bacia Hidrográfica do Rio Catorze que Intensificam a Erosão Laminar (Soil Properties of Catorze River Watershed that Enhance Erosion Laminar) ». Revista Brasileira de Geografia Física 5, no 1 (18 juin 2012) : 160. http://dx.doi.org/10.26848/rbgf.v5i1.232801.
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Este estudo foi desenvolvido tendo como objetivo estimar a suscetibilidade à erosão dos solos da bacia hidrográfica do rio Catorze, no município de Francisco Beltrão – PR. Coletaram-se amostras ao longo da Bacia, em horizonte superficial, e posteriormente, desenvolveu-se análise granulométrica. Partindo dos resultados da análise, utilizou-se da equação desenvolvida por Denardin (1990), que considera os teores óxido de alumínio, areia, matéria orgânica, e permeabilidade do solo, para estimar os valores do fator K (erodibilidade). Através do software Spring 5.1.8, classificaram-se os solos da Bacia, e utilizando programa LEGAL, atribuiu-se os valores de K para os solos classificados, resultando em uma grade retangular com os valores do fator erodibilidade de toda a Bacia. Produziram-se cartas de classificação do solo e do fator erodibilidade, com o auxílio do software Scarta 5.1.8. As equações para estimar os valores do fator erodibilidade, dependem das características físicas, químicas e biológicas dos solos e são desenvolvidas na tentativa de minimizar erros e se aproximar de um valor real do fator K. Os valores encontrados para o fator erodibilidade na bacia do rio Catorze, variam entre 0,0611 e 0,1238 t.ha-1.h.mm-1.ha.MJ-1, mostrando uma erodibilidade elevada, principalmente para os neossolos, que são solos menos desenvolvidos. Esses valores encontrados para o fator K mostram a necessidade de uma adequação no uso e nas práticas conservacionistas ao longo da Bacia, utilizando para isso, o mapa da erodibilidade desenvolvido através de geoprocessamento, onde é possível visualizar as áreas mais suscetíveis à erosão, podendo aplicar o controle e prevenção dos processos erosivos. Palavras-chave: Erodibilidade, fator K, bacia hidrográfica Soil Properties of Catorze River Watershed that Enhance Erosion Laminar ABSTRACT This study was developed aiming to estimate the susceptibility to soil erosion of Catorze River watershed, in the municipality of Francisco Beltrão - PR. Samples were collected throughout the basin in the surface horizon, and subsequently developed particle size analysis. Based on the results of the analysis, we used the equation developed by Denardin (1990), which considers the levels of aluminum oxide, sand and organic matter, and the permeability of the soil, and found values of the K factor (erodibility). Through the Spring software 5.1.8, the soils were classified Basin, and using LEGAL program was given the values of K for soils classified, resulting in a rectangular grid with the values of the erodibility factor of the entire basin. Was produced letters soil classification and erodibility of the factor with the aid of software Scarta 5.1.8. The equations for estimating erodibility factor values depend on the physical, chemical and biological properties of soils and are developed in order to minimize mistakes and get closer to an actual value of the factor K. The values found for the factor in erodibility Catorze River watershed range between 0.0611 and 0.1238 t ha-1.h.mm-1.ha.MJ-1, showing a high erodibility, especially for neossolos, soils that are less developed. These values for the K-factor shows the need for an adjustment in the use and conservation practices throughout the basin, using for this, the map of erodibility developed through GIS, where you can view the areas most susceptible to erosion and may apply control and prevention of erosion.Key Words: Erodibility, K factor, watershed
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Sushmita et Anjali. « Akshi Tarpana:An Eye Rejuvenation ». International Research Journal of Ayurveda & ; Yoga 05, no 06 (2022) : 105–11. http://dx.doi.org/10.47223/irjay.2022.5616.
Texte intégralRésumé :
Akshiis the most important Gyan Indriya. It is the site of Alochaka Pitta.SushrutaThe Father of Surgery has recommended “Kriyakalpa”for the management of Akshi Roga. The term Kriyakalparefers to the treatment, which can be applied for almost all types of Akshi Roga.Kriyakalpacomprises ofTarpana, Putpaka, Seka, Aschyotana and Anjana. Akshi Tarpana is a procedure to ensure that the healthy status of the eye is maintained in a normal condition as well as diseased states. In this procedure medicated oil or ghee is retained in the eyes for fixed time in a specific formed frame. According to modern pharmacology, drug penetration depends upon permeability of layers. The epithelium & endothelium of cornea is highly permeable for lipid content, while stroma is permeable to only water content. Thus, fat soluble and water-soluble drugs readilypenetrate these layers. In this article there is a review on Akshi TarpanaKarma, their indications, contraindications and possible mode of action is discussed.
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Soares, José Agnelo, Paula Rayane Lopes de Andrade et Juliana Trajino Batista. « CONTRIBUTIONS OF DIGITAL IMAGE ANALYSIS TO SEDIMENTARY ROCK CHARACTERIZATION ». Revista Brasileira de Geofísica 36, no 4 (21 décembre 2018) : 1. http://dx.doi.org/10.22564/rbgf.v36i4.1966.
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ABSTRACT. This article presents results achieved by a series of studies aiming to evaluate petrophysical properties from digital images of sedimentary rocks. This characterization from digital images occur in the pores and grain scale, but it is confronted with the same properties as they are conventionally measured on the centimeter scale of laboratory rock samples. The properties evaluated were the porosity of macro and micro pores, mineral composition, the size distribution of grains and pores, sphericity and roundness of the mineral grains, permeability, the quality of grain-grain contacts, elastic wave velocities and electrical properties of the rocks. Predictive models for permeability and elastic velocities of carbonate rocks are presented for the estimation of these properties from the extracted parameters of rocks´ digital images. Beyond of elastic properties (e.g. VP and VS), important parameters for estimation of hydrocarbon reserves, such as tortuosity factor and saturation and cementation coefficients, are evaluated through the digital models of rock.Keywords: X-ray microtomography, rock characterization, petrophysics, carbonate, sandstone, shale.RESUMO. Este artigo apresenta resultados alcançados por uma série de estudos realizados com o objetivo de avaliar propriedades petrofísicas de rochas sedimentares a partir de imagens digitais dessas rochas. Essa caracterização a partir de imagens digitais ocorre na escala de poros e grãos, mas ela é confrontada com as mesmas propriedades medidas de forma convencional na escala de amostras de rochas com dimensões centimétricas. As propriedades avaliadas foram a porosidade de macro e de micro poros, a composição mineral, a distribuição de tamanhos de grãos e de poros, a esfericidade e o grau de arredondamento dos grãos minerais, a permeabilidade, a qualidade dos contatos intergrãos, as velocidades das ondas elásticas e as propriedades elétricas das rochas. Modelos preditivos para a permeabilidade e as velocidades elásticas de rochas carbonáticas são apresentados para a estimativa dessas propriedades a partir de parâmetros extraídos de imagens digitais de rochas. Além de propriedades elásticas (como VP e VS), parâmetros importantes para a estimativa de reservas de hidrocarbonetos, tais como o fator de tortuosidade e os coeficientes de saturação e de cimentação, são avaliados criteriosamente através dos modelos digitais de rocha.Palavras-chave: Microtomografia de raios x, caracterização de rochas, petrofísica, carbonato, arenito, folhelho.
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Nojosa, J. S., T. A. D. Mendes, M. V. S. Lemos, V. P. Feitosa, S. L. Santiago, L. Wang, L. F. F. Brianezzi et J. S. Mendonça. « Avaliação in vitro do Uso de Fitocomplexos no Tratamento da Hipersensibilidade Dentária ». Journal of Health Sciences 19, no 5 (23 février 2018) : 285. http://dx.doi.org/10.17921/2447-8938.2017v19n5p285.
Texte intégralRésumé :
Objetivou-se avaliar fitocomplexos, como agentes de oclusão de dentina tubular, para o tratamento da hipersensibilidade dentinária. Dezesseis terceiros molares foram cortados transversalmente para obtenção de discos de dentina com espessura de 1 mm. Os espécimes foram divididos em 4 grupos (n4), de acordo com o tratamento: oxa-gel (Kota) (controle), extrato seco liofilizado de manjericão, hortelã e espinafre, na concentração de 5%. No teste de permeabilidade dentinária, os discos foram submetidos ao condicionamento com ácido fosfórico 37%, para medição da condutância hidráulica (Pmax). Após aplicação dos tratamentos por 5 minutos, mediu-se a condutância hidraúlica (Pmin). A resistência dos tratamentos ao desafio ácido foi avaliada após aplicação do ácido cítrico 7%, por 1 min. Para verificar a formação de oxalato de cálcio no FTIR, os discos foram tratados, conforme seu respectivo grupo, por 5 min. Na análise estatística, realizou-se o teste ANOVA um fator, seguido do pós-teste de Tukey (p≤0,05) para analisar a permeabilidade. Entre os tratamentos não houve diferença significante na permeabilidade dentinária (p0,683), porém quando todos tratamentos foram comparados, mostraram-se resistentes ao desafio ácido (p0,01). No FTIR realizou-se uma análise qualitativa, onde apenas o grupo hortelã não apresentou uma precipitação de oxalato considerável. Conclui-se que os fitocomplexos foram capazes de ocluir os túbulos dentinários e permitiram a deposição de oxalato de cálcio, sendo bastante promissores no tratamento da hipersensibilidade dentinária.Palavras-chave: Dentin Sensitivity. Dentin Permeability. Calcium Oxalate.
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Ilkova, P., Z. Stoyneva et N. Dimitrova. « Current aspects in the differential diagnosis of angioneurotic edema ». Trakia Journal of Sciences 19, no 1 (2021) : 97–107. http://dx.doi.org/10.15547/tjs.2021.01.015.
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Angioedema is a disease characterized by various triggers and an increasing prevalence. The great Greek physician Hippocrates (377-460 BC), considered one of the most outstanding figures in the history of medicine and "Father of the Western Medicine," already used the term oídēma to describe „swelling of organs“. It took many centuries later until the first description of angioedema as a distinct medical entity was minted by Quinсke in 1882. The contemporary perception, defines аngioedema as a transient swelling of the skin or submucosal surface due to increased vascular permeability of small venules. The overlying skin may be normal or mildly erythematous. Over time, many causes and factors that cause or trigger angioedema have been discussed. There are two main types of angioedema without urticarial (histaminergic and nonhistaminergic) as the role of histamine in the pathogenesis of the disease is crucial. Angioedema is a frequent clinical condition that sometimes can be life-threatening. Different types of angioedema can be challenging to distinguish clinically. However, establishing a correct diagnosis is critical as different forms of angioedema require distinct treatment approaches. Implementation of contemporary differential diagnostic approaches could be a prerequisite for an accurate diagnosis, which secures appropriate management strategies are possible.
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Ingrassia, Raimondo. « Il whistle-blowing come strumento di controllo interno delle organizzazioni ». STUDI ORGANIZZATIVI, no 2 (décembre 2009) : 40–70. http://dx.doi.org/10.3280/so2009-002003.
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- Uno di problemi che si pongono quando si parla di abusi dei colletti bianchi nel mondo del lavoro č quello di sottoporre al giudizio della collettivitŕ condotte discutibili sul piano etico, manageriale, professionale e giuridico delle quali perň č difficile avere conoscenza in quanto esse vengono consumate al riparo di organizzazioni legali e, spesso, poco permeabili alla societŕ. Una forma di controllo privilegiata per la qualitŕ delle informazioni che č in grado di fornire č la denuncia pubblica degli abusi del prestatore di lavoro legato all'organizzazione da un rapporto di dipendenza. La cultura anglosassone ha metaforicamente etichettato tale pratica con il termine di "whistleblowing", letteralmente "soffiare il fischietto", cioč dare un segnale di allarme per gli abusi osservati nel luogo di lavoro. Questo articolo intende offrire una rassegna sistematica dei principali temi esistenti in materia. Sono pertanto oggetto di trattazione i seguenti argomenti: le relazioni fra gli abusi dei colletti bianchi e le organizzazioni legali; le tipologie di abusi piů comuni; il profilo identitario di coloro che denunciano; i fattori oggettivi che influenzano le decisioni di denuncia; i rischi legati alle attivitŕ di denuncia; l'efficacia, la tutela giuridica e le policy del whistle blowing. La tesi conclusiva č che la denuncia pubblica degli abusi deve fare leva sulla responsabilitŕ personale e che il contesto organizzativo e istituzionale nei quali i prestatori di lavoro operano devono svolgere una funzione di incentivo e protezione dell'iniziativa individuale.
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Bornikova, Larissa, Gary Brodsky, Keith B. Neeves, Rita Marchi, Donald S. Backos, Philip Reigan, Alisa S. Wolberg, Marilyn J. Manco-Johnson et Jorge A. Di Paola. « A Novel Missense Mutation in FGG (c.944C>A) Encodes for An Amino Acid Change (p.Ala315Asp) in the Gamma Chain of Fibrinogen Causing Hypofibrinogenemia and a Thrombotic Phenotype ». Blood 118, no 21 (18 novembre 2011) : 856. http://dx.doi.org/10.1182/blood.v118.21.856.856.
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Abstract Abstract 856 Fibrinogen plays a central role in maintaining hemostasis. Disruption of its normal function may lead to hemorrhagic or thrombotic events. Fibrinogen is encoded by three genes, FGA, FGB, and FGG, clustered on chromosome 4q28-q31. Hereditary defects of fibrinogen, although uncommon, can affect the quantity (hypofibrinogenemia and afibrinogenemia) or the quality (dysfibrinogenemia) of the circulating protein. We report a family with two affected individuals (father and daughter) that presented with a mild bleeding predisposition, but also exhibited thrombotic events, i.e. unprovoked deep vein thrombosis in a father and an in utero middle cerebral artery stroke in a daughter. The Clauss fibrinogen levels for the father and daughter were 105 and 98 mg/dL (normal 150–400 mg/dL) and fibrinogen antigen levels were 138 and 152 mg/dL (normal 170–400 mg/dL), respectively. Thrombin times were prolonged in both patients. All other coagulation factors were within normal range and the patients did not carry either the prothrombin G20210A or factor V Leiden mutation. All exons and intron-exon junctions of the three fibrinogen genes were sequenced. The father and daughter were found to be heterozygous for a novel missense mutation in the gamma chain (Ala315Asp) while this mutation was not observed in an unaffected family member (mother of the daughter). Transient transfection experiments using CHO-K1 cells showed that gamma chain with p.Ala315Asp mutation was detected in both cell lysates and supernatant, although in reduced amount as compared with cells transfected with wild-type (WT) FGG cDNA. Structurally, there was no significant difference in fibrin fiber diameter, as measured manually by scanning electron microscopy, between the affected (father and daughter), and the daughter's unaffected mother. Similarly, there was no difference in thrombus height between the three individuals. As expected, hydraulic permeability of platelet rich plasma clots correlated with the fibrinogen levels in each person. Clotting kinetics in plasma of affected family members was consistent with hypofibrinogenemia, but did not suggest abnormal fibrin polymerization. Clot structure and fibrin deposition was further characterized with a microfluidics flow assay, an experimental technique in which platelet and fibrin accumulation is observed in real-time using fluorescent probes in whole blood under shear stress on a collagen/tissue factor micropatterned surface. Interestingly, fibrin density and platelet accumulation, as measured by platelet and fibrin surface area coverage, was highest in the father and daughter, the two individuals with hypofibrinogenemia and thrombotic phenotype. In order to evaluate the possible changes resulting from the Ala315Asp mutation we examined predicted alterations in protein structure, energy, and protein-protein interaction between two fibrinogen molecules via in silico molecular modeling using published protein crystal structure. The molecular modeling showed that alanine for aspartic acid substitution predicted to result in substantial changes in overall conformation of the interaction interface (distal D-domain) between the two fibrinogen molecules due to introduction of a bulkier side chain. Potential energy (energy of minimization) for Ala315Asp mutant homodimer, and for WT-mutant heterodimer were lower than the WT homodimer, predicting a more stable structure from an energetic standpoint. Overall interaction energy (measurement of the energy of association between the two molecules) was lower for Ala315Asp mutant homodimer as compared with WT homodimer or WT-mutant heterodimer, suggesting more favorable interaction for Ala315Asp mutant dimers. Overall, the in silico modeling studies predicted that Ala315Asp mutation may lead to more rapid or stronger interaction between fibrinogen molecules. These data suggest that a novel FGG mutation, c.944C>A, that predicts pAla315Asp change, if expressed and incorporated into fibrinogen molecule in vivo, may result in a more stable or more resistant to lysis clot. Characterizing the association between a specific genetic defect and its phenotypic expression will advance the current understanding of the molecular and biochemical mechanisms of the inherited disorders of fibrinogen, and may contribute to the development of safer therapeutic interventions for the patients with fibrinogen disorders. Disclosures: No relevant conflicts of interest to declare.
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Sunjoto, S. « Groundwater Engineering Computation Methods Based on Forchheimer’s Equation ». Applied Mechanics and Materials 881 (mai 2018) : 23–33. http://dx.doi.org/10.4028/www.scientific.net/amm.881.23.
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Darcy was known as a very generous engineer. He is undoubtedly the father of the science of fluid flow in soils for his experiment on the flow of water through a sand column which was published in his book ‘Les fontainespubliques de la ville de Dijon in 1856, named after him as Darcy’s law. For the practical computation, this equation was developed by Dupuit & Thiem, and then it called Dupuit-Thiem equation. This equation was redeveloped by many researchers in many variations with different parameters especially for radial flow in pumping and recharging systems. Their basic pumping system equations for a confined and unconfined aquifer as well as for full penetration well with a fully perforated casing. In the practical implementation, this condition rarely occurs especially for thick aquifer; therefore many researchers developed a correction for those formulas from full penetration to be partial penetration wells. Partial penetration well is a well which its depth or tip of its casing does not reach an impermeable stratum beneath the aquifer. Despite the correction, those formulas still have difficulty in computing the design of pumping system due to its need for hydraulic gradient data which can only be defined by two real time data of piezometric head before and after pumping related to the horizontal distance of both points. So in this paper will be presented some inventions of computation methods for instance: recharge systems, the drawdown of pumping, pumping on the aquifer, water losses on the lake, permeability test, pumping test analysis and partial penetration well equation.
Thèses sur le sujet "Fattor permeabilità"
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MORELLO, WILLIAM. « Underlying mechanisms of Idiopathic Nephrotic Syndrome in children : evidence of a circulating permeability factor ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2020. http://hdl.handle.net/10281/263395.
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La sindrome nefrosica idiopatica (INS) in età pediatrica è caratterizzata da proteinuria massiva, secondaria alla alterazione della struttura della membrana basale glomerulare (GBM). I pazienti pediatrici affetti da sindrome nefrosica cortico-resistente (SRNS) sono ad elevato rischio di insufficienza renale terminale (ESRD). Sebbene evidenze suggeriscano la presenza di un fattore circolante di permeabilità correlato al sistema immunitario, tutti i precedenti tentativi di comprensione degli esatti meccanismi alla base della patologia sono stati inconclusivi. L'identificazione dei meccanismi alla base della INS e della cortico-resistenza potrebbe favorire lo sviluppo di terapie mirate, in grado di arrestare la progressione verso del danno renale in pazienti con SRNS, nei quali l'ESRD è un evento comune ed in cui è necessario ricorrere a dialisi o trapianto di rene, con elevato rischio di recidiva su rene trapiantato.
Questo progetto mira a identificare i meccanismi responsabili della INS in età pediatrica. Durante i 3 anni di progetto, abbiamo a tal fine applicato un approccio clinico e di laboratorio.
Abbiamo effettuato uno studio retrospettivo, multicentrico di corte nazionale per identificare la prognosi renale, i fattori di rischio per la recidiva e quelli predittivi di risposta alla terapia post-recidiva, in tutti i pazienti pediatrici sottoposti a trapianto di rene per SRNS in Italia dal 2005 al 2017. Sono stati identificati 101 pazienti. In base ai risultati ottenuti, l'assenza di mutazioni causative per SRNS rappresenta il più importante fattore di rischio per la recidiva nei bambini con SRNS. Il trapianto è invece curativo per le SRNS genetiche. Prolungare il tempo di dialisi prima del trapianto non ha un effetto protettivo sul rischio di recidiva ed è una strategia da non incoraggiare. Il ritrapianto è possibile dopo la perdita di un primo rene trapiantato.
Contemporaneamente è stato eseguito uno studio di laboratorio identificando pazienti con differenti forme di SRNS, raccogliendone i sieri e testandoli su un nuovo modello di laboratorio in grado di determinare la permeabilità della albumina sierica bovina (BSA) attraverso un sistema a 3 strati (3LD). I 3 strati comprendono: 1. Podociti umani immortalizzati (HCiPodo), 2. una membrana rivestita di collagene tipo IV e 3. cellule endoteliali glomerulari umane (HCiGEnC).
I sieri di 7 pazienti con SRNS recidivata su trapianto (rSRNS), 5 SRNS non recidivate (nrSRNS), e 5 SRNS genetiche (gSRNS) sono stati testati sul sistema. E' stato possibile dimostrare che i sieri di tutte i pazienti con rSRNS aumentano la permeabilità all'albumina nel modello, mentre i sieri dei pazienti con nrSRNS e gSRNS non ne determinano alterazioni significative. Inoltre, la plasmaferesi elimina la capacita dei sieri di incrementare la permeabilità all'albumina nei pazienti rSRNS.
Questi risultati confermano l'ipotesi di un fattore circolante di permeabilità responsabile della SRNS nei pazienti recidivati dopo trapianto, senza mutazioni genetiche causative.
Se questi risultati verranno confermati su casistiche più ampie, il modello di GBM potrà essere utilizzato per predire la probabilità di recidiva su trapianto, monitorare la terapia ed escludere la presenza di mutazioni genetiche alla diagnosi di INS.
Una analisi preliminare di proteomica dei sieri ha evidenziato differenti profili proteici nelle diverse forme con differente attività sul modello di GBM.Idiopathic Nephrotic Syndrome (INS) in children is characterized by protein loss in urine, related to the disruption of the integrity of glomerular filtration barrier (GBM). Children with steroid-resistant INS (SRNS) have a great risk of end-stage renal disease (ESRD). Although evidence suggests the presence of an immune-related circulating factor responsible for glomerular barrier dysfunction, any previous attempt to unravel these mechanisms has been inconclusive. The ability to identify the underlying mechanisms of the disease and/or steroid-resistance would lay the foundations for a potential, much-needed target therapy, since 50% of drug-resistant cases progress to ESRD, requiring renal replacement therapy and may suffer from relapse after renal transplantation. This project aim is to clarify the mechanisms responsible of INS in children. During the 3 years of this PhD project we have applied both a clinical and laboratory approach. We performed a retrospective, multicentre, national cohort study to address the long-term prognosis of renal graft, the risk factors for recurrence and the predictors for response to therapy following recurrence in paediatric patients undergoing renal transplantation because of a SRNS. We identified all children with SRNS who underwent renal transplantation in Italy, between 2005 and 2017. 101 patients were identified. According to our results, the absence of a causative mutation represents the major risk factor for post-transplant recurrence in children with SRNS, while transplant can be curative in genetic SRNS. A prolonged time spent on dialysis before transplantation has no protective effect on the risk of relapse and should not be encouraged. Retransplantation represents a second chance after graft loss for recurrence. At the bench side, we identify patients with different forms of SRNS, collected their sera and tested the samples by means of a novel method which assess the permeability to bovine serum albumin (BSA) through a three-layer device (3LD). The 3 layers comprise: 1. conditionally immortalized human podocytes (HCiPodo), 2. collagen type IV coated porous membrane and 3. human glomerular endothelial cells (HCiGEnC). Seven recurrent SRNS (rSRNS), 5 non-recurrent SRNS (nrSRNS), and 5 genetic SRNS (gSRNS) were collected. Using this model, we were able to demonstrate that sera from all rSRNS patients recurred after transplantation increased albumin permeability, while sera from nrSRNS and gSRNS did not. Furthermore, we also found that the plasmapheresis eliminated the increasing BSA permeability effect in sera from rSRNS patients. These preliminary results confirm the hypothesis that a circulating permeability factors is responsible for SRNS in patients recurring after renal transplantation, without underlying causative gene mutations. If these results will be confirmed on larger cohorts, this GBM model could be a useful tool to predict the probability of disease relapse on transplantation, monitor the therapy or exclude a genetic diagnosis at the INS onset. A preliminary proteomic analysis of sera tested on the GBM model showed different profiles for each category.
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Walker, Michael. « Influence of long chain fatty acids on the epidermal permeability barrier ». Thesis, Cardiff Metropolitan University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288513.
Texte intégral
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AHMED, SADEK. « Valutazione di alcuni fattori che influenzano la fermentazione ruminale e le conseguenze dell’acidosi ruminale sulla permeabilità gastrointestinale e sull’infiammazione ». Doctoral thesis, Università Cattolica del Sacro Cuore, 2013. http://hdl.handle.net/10280/1734.
Texte intégralRésumé :
Quattro diversi esperimenti sono stati eseguiti per investigare i fattori che influenzano la fermentazione ruminale delle diete altamente fermentescibili e per sviluppare un modello per studiare la permeabilità gastro-intestinale nei ruminanti. Nello studio 1, quattro ibridi di mais sono stati valutati per la digeribilità ruminale delle loro frazioni. I risultati suggeriscono che i genotipi e le fasi di maturità influenzano fortemente la digeribilità della sostanza secca e dell’amido nel rumine. Nello studio 2, i risultati della fermentazione in vitro di diversi zuccheri ha rivelato che il lattulosio può essere uno zucchero indicatore per studiare la permeabilità intestinale nei ruminanti, grazie alla sua bassa fermentescibilità ruminale. Nello studio 3, per la prima volta un modello di enteropatia indotta da indometacina è stato utilizzato per valutare nei ruminanti la permeabilità dell’intestino tenue attraverso il test del lattulosio. I risultati mostrano che il lattulosio è passato dall'intestino al sangue modificando alcuni parametri metabolici e dell'infiammazione. Nello studio 4, una acidosi acuta è stata indotta in pecore per testare la permeabilità gastro-intestinale con il test del lattulosio. I risultati hanno dimostrato che l'acidosi acuta compromette il funzionamento della barriera gastro-intestinale consentendo l'assorbimento e la traslocazione di LPS e altre sostanze nocive e incrementa l'infiammazione.Four different experiments were performed for the better understanding of the factors that affect rumen fermentation of highly fermentable diets and to develop a model to study GI permeability in ruminants. In study 1, four corn hybrids recommended for corn silage were evaluated for ruminal starch digestibility of their grain fractions. Results suggest that the genotypes and maturity stages greatly influenced the DM and starch digestibility in rumen. In study 2, the results of the in vitro rumen fermentation of different naturally occurring and synthetic sugars revealed that lactulose can be a good probe sugar to study GI tract permeability in ruminants due to its low and slow fermentation rate in rumen. In study 3, for the first time an indomethacin-induced enteropathy model was used in ruminants to assess small intestinal permeability by the lactulose test. The results established that lactulose passed from the intestine to blood with perturbation of some metabolic parameters and inflammation. In study 4, acute acidosis was induced in sheep to test GI permeability during acidosis condition by lactulose test. The results demonstrated that acute acidosis impair the GI barrier function which allow absorption and translocation of LPS and other harmful substances and increase inflammation.
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Crepaldi, Eduardo Antônio. « Influência do fator de cobertura nas propriedades de permeabilidade de tecidos planos ». Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/100/100133/tde-06122018-161422/.
Texte intégralRésumé :
Este projeto, \"Influência do fator de cobertura nas propriedades de permeabilidade de tecidos planos\", descreve um breve histórico sobre a Tecelagem e seu crescimento na indústria Têxtil mundial, sendo muito importante o seu desenvolvimento para a indústria. Será apresentado também o conceito sobre Fator de cobertura de tecidos planos. Com o objetivo de avaliar a correlação entre o fator de cobertura e a permeabilidade dos tecidos planos, foram desenvolvidas 18 amostras de tecido com fio 60/2 Ne 100% agodão no urdume e na trama, em ligamento tela, sarja e cetim com densidades de trama 16tramas/cm, 24tramas/cm e 32tramas/cm, e com densidade de urdume 16fios/cm e 32fios/cm . Foi calculado o fator de cobertura para todas as amostras e foram realisados ensaios de gramatura, permeabilidade ao ar, permeabilidade ao vapor de água e permeabilidade a água, com a observação do indice OMMC (Capacidade de gestão global de umidade) do aparelho MMT (Moisture Management Tester). Este estudo se mostra como um caminho na Utilização do fator de cobertura, como item a ser considerado no desenvolvimento de novos artigos. Os resultados mostram para cada ligamento e fator de cobertura o comportamento com relação à permeabilidade dos TecidosThis project, \"Influence of the coverage factor on the properties of permeability of woven\", describes a brief history on Weaving and its growth in the world textile industry, being very important its development for the industry. The concept of woven coverage factor, will also be presented. In order to evaluate the co-relation between the coverage factor and the permeability of woven, 18 wovens samples were developed with 60/2 Ne 100% cotton thread in the warp and the weft, inwoven twill and satin weave with warp weights 16 yarn/cm, 24 yarn/cm and 32 yarn/cm and with warp density 16 yarn/cm and 32yarn/cm. The coverage factor was calculated for all samples and weight, air permeability, water vapor permeability and water permeability tests were performed with the observation of the OMMC (Global Moisture ManagementCapacity) index of the MMT (Moisture Management Tester).This study shows as a path in the use of the coverage factor, as an item to be considered in the development of new articles. The results show for each ligament and cover factor the behavior regarding the permeability of the wovens
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Filho, Manoel de Arcisio Miranda. « Efeitos elétricos de ácidos graxos livres em bicamadas lipídicas planas ». Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/42/42137/tde-19102007-092737/.
Texte intégralRésumé :
Ácidos graxos livres (FFA) são importantes mediadores do transporte de prótons através de membranas. Porém, pouco se sabe sobre a influência estrutural tanto dos FFA como do ambiente lipídico na translocação de prótons através de membranas. Tanto os efeitos do comprimento da cadeia e número de insaturações dos FFA como a composição da membrana foram analisados por medidas elétricas em bicamadas lipídicas planas. Condutância a prótons (GH+) e condutância de vazamento (Gleak) foram calculadas a partir de medidas de voltagem em circuito aberto e de corrente de curto-circuito obtidas através de um eletrômetro ou um amplificador de patch-clamp (modo de voltage-clamp). Nossos resultados mostram que FFA com cis-insaturações causam um efeito mais pronunciado no transporte de próton quando comparados com FFA saturados ou trans-insaturação. Colesterol e cardiolipina diminuem Gleak de membranas. Cardiolipina também diminui GH+. Esses efeitos indicam uma dupla modulação do transporte de prótons: pelo mecanismo de flip-flop dos FFA e por uma via difusional simples adicional.Free fatty acids (FFA) are important mediatiors of proton transport across membranes. However, little is known about the structural influence of both FFA and the membrane environment have in proton translocation across phospholipid membranes and by which means this influence is brought about. Both the effects of FFA chain length and insaturation and membrane composition on proton transport have been addressed in this study by electrical measurements in planar lipid bilayers. Proton conductance (GH+) and leak conductance (Gleak) were calculated from open-circuit voltage and short-circuit current measurements obtained using either an electrometer or a patch-clamp amplifier (voltage-clamp mode). We found that cis-unsaturated FFA caused a more pronounced effect on proton transport as compared to saturated or trans-unsaturated FFA. Cholesterol and cardiolipin decreased Gleak. Cardiolipin also decreased GH+. These effects indicate a dual modulation of protein-independent proton transport by FFA through flip-flop and by an additional simple diffusional pathway.
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Benoit, Bérengère. « Effet des acides gras alimentaires à chaîne longue sur la barrière épithéliale colique ». Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10239.
Texte intégralRésumé :
Les cellules à mucus intestinales sécrètent des mucines, principalement MUC2, qui forment un gel protecteur. Malgré la place importante des acides gras à chaîne longue (AGCL) dans l'alimentation et leurs liens avec des pathologies où les cellules à mucus sont altérées il n'existe pas d'étude sur leurs impacts sur ces cellules. Mes travaux ont consisté à mettre en lumière ces interactions et à étudier leurs conséquences. In vitro, nous montrons que les AGCL saturés augmentent l'expression de MUC2 et son relarguage alors que les AGCL insaturés les inhibent et que l'acide palmitique favorise la différenciation cellulaire. In vivo, chez des ratons gavés avec de l'huile de palme, la production de MUC2 est augmentée et la perméabilité paracellulaire colique diminuée. Les huiles de colza ou de tournesol ne modifient pas la production de MUC2 et la perméabilité est identique aux contrôles malgré l'augmentation de l'expression de l'occludine. Dans un modèle de syndrome de l'intestin irritable, nous montrons que le gavage avec l'huile de palme, malgré la diminution de l'occludine, restaure la perméabilité et augmente le nombre de cellules à mucus. L'huile de colza et l'huile de tournesol ne corrigent pas le défaut de perméabilité. Parallèlement, deux études chez la souris ont mis en évidence l'impact de certains régimes sur le nombre des cellules à mucus. Ce travail a permis d'identifier les AGCL comme des nutriments capables de moduler les cellules à mucus, de faire émerger une nouvelle piste thérapeutique pour restaurer les populations de cellules à mucus et la perméabilité et d'ouvrir la réflexion sur les impacts de l'augmentation des populations de cellules à mucus chez l'individu sainIntestinal goblet cells secrete mucins, mainly MUC2, which form a protective mucus gel. Despite the important place of long chain fatty acids (LCFA) in the diet and their links with pathologies where goblet cells are altered, there is no study dealing with their impact on goblet cells. The aim of my work was to highlight these interactions and to study their consequences. In vitro, we show that saturated LCFA increase MUC2 expression and release whereas unsaturated LCFA inhibit these process and that palmitic acid promotes cellular differentiation. In vivo, rat pups receiving oral administration of palm oil show a decrease of colonic paracellular permeability and an increase of MUC2 production. On the opposite, rapeseed and sunflower oils do not change MUC2 production and, intestinal permeability is the same as controls despite the increase of occludin expression. In an animal model of irritable bowel syndrome, palm oil effects are found again. When subjected rat pups to a maternal deprivation stress a few days after birth, they develop an intestinal hyperpermeability and a goblet cell depletion. We show that oral administration of palm oil concomitantly to the stress is able to, despite a decrease of occludin expression, restore the permeability at the level of non-stressed animals and to increase goblet cell number. Rapeseed oil and sunflower oil are not able to correct the increase of intestinal permeability. In parallel, studies in mice show that some types of diets can be associated with an increase of the number of proximal and distal goblet cells. To conclude, this work (i) helped to identify LCFA as nutrients able to modulate intestinal goblet cell number and physiology, (ii) put forward a new therapeutic track, via palmitic acid use, to restore goblet cell populations and intestinal permeability in pathologies associated with these kind of alterations and finally (iii) offered new tracks of reasoning about physiological and pathophysiological impacts of the increase of intestinal goblet cell number in a healthy subject
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Maciel, Hugo Emerich. « Avaliação de modelos de permeabilidade em meios porosos não consolidados ». Universidade do Estado do Rio de Janeiro, 2015. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=9498.
Texte intégralRésumé :
Conselho Nacional de Desenvolvimento Científico e TecnológicoAs simulações computacionais tem sido amplamente empregadas no estudo do escoamento darciano e não-darciano em meios porosos consolidados e não-consolidados. Neste trabalho, através de uma nova formulação para a equação de Forchheimer, foram identificadas duas novas propriedades denominados fator de comportamento do fluido, que atua paralelamente a permeabilidade, e permeabilidade equivalente global, resultado da relação anterior. Este comportamento foi estudado e validado através da implementação de um aparato experimental e um código computacional baseado no modelo de regressão-linear que, além disso, demonstrou que o escoamento, ainda que em regime não darciano, comporta-se linearmente como a equação de Darcy, ainda que o coeficiente angular desta diminuiu de acordo com a faixa do número de Reynolds atingida, sendo esta dependente do tipo de leito empregado. Ainda neste trabalho, foi implementado o método de otimização R2W para estimar os parâmetros da equação de Kozeny-Carman a partir de dados experimentais obtidos por Dias et al, a fim de simular o escoamento darciano em meios porosos. Por fim, foi alcançada excelente concordância entre os dados simulados pelo método R2W / equação de Kozeny-Carman e os dados reais.
Computer simulations have been widely used in the study of Darcys flow and non-Darcy porous media in consolidated and non-consolidated. In this work, through a new formulation for the Forchheimer equation, we have been identified two new called Fluid Factor Behavior properties, which acts parallel to permeability, and overall equivalent permeability result of the previous relationship. This behavior has been studied and validated through implementation of an experimental apparatus and a computer code based on the linear regression model, moreover, it demonstrated that flow, even in non darciano system behaves linearly as the Darcy, however, the slope of this decreased according to the range of Reynolds numbers reached, this being dependent on the type of bed used. Although this work was implemented R2W optimization method to estimate the parameters of Kozeny-Carman equation from experimental data provided in the literature in order to simulate the darciano flow in porous media. Finally, it achieved excellent agreement between the data simulated by R2W method / Kozeny-Carman equation and actual data.
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Figueira, Estela Regina Ramos. « Efeito da solução salina hipertônica nas lesões resultantes da isquemia/reperfusão hepática : estudo experimental em ratos ». Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/5/5132/tde-07052009-164556/.
Texte intégralRésumé :
Introdução: A lesão de isquemia/reperfusão do fígado é caracterizada pelo agravamento da lesão isquêmica hepatocelular quando o órgão é revascularizado, podendo originar, nos casos mais graves, uma reação inflamatória sistêmica com lesão de órgãos à distância. O controle desse fenômeno é importante no transplante de fígado, nas cirurgias de ressecção hepática e no choque hemorrágico. A administração de soluções salinas hipertônicas têm se mostrado eficaz no tratamento do choque hemorrágico, pois melhora as alterações hemodinâmicas e, possivelmente, apresenta uma ação antiinflamatória. Neste trabalho foram avaliados os efeitos locais e sistêmicos da administração da solução salina hipertônica na lesão de isquemia/reperfusão hepática em ratos. Métodos: Enquanto 14 ratos Wistar machos, dos 56 utilizados no estudo, compuseram o grupo controle, grupo C; os demais, que foram submetidos à uma hora de isquemia hepática e 4 horas de reperfusão, compuseram outros grupos de 14 animais: o grupo ST, animais que não receberam tratamento; o grupo SSF, animais que receberam 34 mL/kg de NaCl 0,9%, por via endovenosa, 15 minutos antes da reperfusão; o grupo SSH, animais que receberam 4 mL/kg de NaCl 7,5%, 15 minutos antes da reperfusão. Após 4 horas de reperfusão, os materiais foram coletados para análise. Foram realizadas as dosagens das transaminases AST e ALT, a avaliação das funções oxidativas e fosforilativas mitocondriais, a dosagem das interleucinas IL-6 e IL-10, as análises teciduais pulmonares e a análise histológica do fígado isquêmico e não isquêmico. Resultados: Quando comparado aos grupos ST e SSF, o grupo SSH apresentou elevação dos níveis de AST e ALT significantemente menores; preservação da função mitocondrial tanto dos lobos isquêmicos, como dos não isquêmicos, significantemente melhor; elevação dos níveis de IL-6 e IL-10 sem significância estatística; aumento da permeabilidade vascular pulmonar significantemente menor; e elevação da atividade da mieloperoxidase pulmonar sem significância estatística. Em relação à análise histológica da lesão de isquemia/reperfusão hepática, o escore da lesão do grupo SSH foi significantemente menor que o da lesão do grupo C; entretanto, quando comparados os três grupos submetidos à isquemia hepática ST, SSH e SSF não se observaram diferenças significantes estatisticamente. Conclusão: A administração da solução salina hipertônica a 7,5% na isquemia/reperfusão hepática normotérmica melhorou as lesões hepáticas locais e as lesões à distância, principalmente pulmonaresIntroduction: During liver ischemia, the drop in mitochondrial energy production leads to cellular damage, which is aggravated during restoration of blood supply. Besides local hepatic injury, the ischemia/reperfusion process can trigger a systemic inflammatory syndrome producing remote organ damage. To control these alterations in clinical conditions like liver transplantation, liver resections and hypovolemic shock, is crucial to achieve proper patient management. Aim: To evaluate the effect of the sodium chloride hypertonic solution on prevention of local and systemic injury during partial liver ischemia/reperfusion. Methods: Animals underwent partial warm liver ischemia/reperfusion. Fity six Wistar male rats were randomly allocated into four groups. Fourteen animals were submitted to sham operation and allocated to C group; 42, submitted to one hour of liver ischemia followed by 4 hours of reperfusion, were allocated in three additional groups: ST group, 14 animals that received no treatment; SSF group, 14 animals that received NaCl 0.9%, 34 mL/kg, intravenously; SSH group, animals that received NaCl 7.5%, 4 mL/kg, intravenously. Blood and tissue samples were collected four hours after reperfusion, when animals were killed. Blood samples were collected to determinate AST, ALT, IL-6 and IL-10 levels. Liver and pulmonary tissues were assembled for liver histology and for liver mitochondrial phosphorylation, pulmonary vascular permeability and myeloperoxidase analyzes. Results: Hypertonic saline solution showed beneficial effects in the treatment of liver ischemia/reperfusion injury. SSH group presented elevation of AST and ALT plasma levels significantly lower than ST and SSF groups. A significant reduction on mitochondrial dysfunction was observed in SSH group compared with ST and SSH groups. Elevation in serum IL-6 and IL-10 was similar among ST, SSF and SSH groups. Pulmonary vascular permeability was significantly lower in group SSH compared with ST and SSF groups. No differences in myeloperoxidase activity were observed among these three groups. Histological score for liver ischemia/reperfusion injury was significantly lower in SSH group compared to ST group, however no differences were observed between SSH and SSF groups. Conclusion: Administration of hypertonic saline solution in an experimental rat model of liver ischemia-reperfusion ameliorated local and systemic injuries
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Dalvi, Siddhartha. « Regulation of permeability of human brain microvessel endothelial cells by polyunsaturated fatty acids ». 2013. http://hdl.handle.net/1993/21704.
Texte intégralRésumé :
The blood-brain barrier, formed by brain microvessel endothelial cells, is the restrictive barrier between the brain parenchyma and the circulating blood. It was previously demonstrated in our laboratory that knock down of fatty acid transport proteins FATP-1 and CD36 attenuated apical to basolateral monounsaturated fatty acid transport across human brain microvessel endothelial cells (HBMEC). Arachidonic acid (AA; 5,8,11,14 - cis-eicosatetraenoic acid) is a conditionally essential, polyunsaturated fatty acid [20:4(n-6)] and a major constituent of brain lipids. We examined transport of AA across confluent monolayers of HBMEC. Control cells or HBMEC with knock down of FATP-1 or CD36 were cultured on Transwell® plates and incubated apically with [3H]AA and incorporation of [3H]AA into the basolateral medium was determined temporally. [3H]AA was rapidly incorporated into the basolateral medium with time in control cells. Surprisingly, knock down of FATP-1 or CD36 did not alter [3H]AA movement into the basolateral medium. The increased permeability mediated by AA was likely caused by a metabolite of AA produced de novo and was confirmed by an increased movement of fluorescent dextran from apical to basolateral medium. HBMECs expressed PGE2 synthase, cyclooxygenase-1 and -2, PGE2 receptors, tight junction proteins and prostaglandin transporters. The AA-mediated increase in membrane permeability was not attenuated by cyclooxygenase inhibitor drugs (NSAIDs). Incubation of the HBMEC monolayers with exogenous PGE2 resulted in attenuation of the AA-mediated permeability increases. The results indicate that AA increases the permeability of the HBMEC monolayer likely via increased production of metabolites or by-products of the lipoxygenase or epoxygenase pathways. These observations may explain the rapid influx of AA into the brain previously observed upon plasma infusion with AA.
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YAN, DONG. « Characterization of a Newly Synthesized Cysteinyl Leukotriene 2 Receptor Selective Antagonist Using Cell Based β-arrestin and Vascular Ear Permeability Assays in Mice ». Thesis, 2011. http://hdl.handle.net/1974/6597.
Texte intégralRésumé :
(hCysLT2R) based on a β-galactosidase complementation
system. The EC50 values for LTC4 and LTD4 are consistent with previous literature
values determined based on radio-labelling affinity assays for hCysLT2R. Activity of a
synthetic analogue of LTC4, N-Methyl LTC4 (NMLTC4), gave an EC50 value of 8.5 nM.
Also described in this thesis, is the synthesis of a cysLT2R selective antagonist, 3-{[(3-
carboxycyclohexyl)amino]carbonyl}-4-{3-{4-(4-phenoxybutoxy)phenyl}-
propoxy}benzoic acid. Through the in vitro assay system, this selective antagonist
showed a dose-dependent inhibition (IC50 value of 86 nM) when CysLT2R was
stimulated with 30 nM of LTD4. Both the selective agonist (NMLTC4) as well as the
selective cysLT2R antagonist were also tested in vivo in a localized vascular ear
inflammation assay. Results show NMLTC4 is able to promote vascular leakage through
stimulation of cysLT2R, and this extravasation can be significantly attenuated by the cysLT2R antagonist.Thesis (Master, Biochemistry) -- Queen's University, 2011-06-29 22:31:03.11
Chapitres de livres sur le sujet "Fattor permeabilità"
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Banks, William A., Abba J. Kastin et Stanley I. Rapoport. « Permeability of the Blood-Brain Barrier to Circulating Free Fatty Acids ». Dans Handbook of Essential Fatty Acid Biology, 3–14. Totowa, NJ : Humana Press, 1997. http://dx.doi.org/10.1007/978-1-4757-2582-7_1.
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Kleinfeld, Alan M. « Fatty Acid Transport Across Membranes ». Dans Permeability and Stability of Lipid Bilayers, 241–58. CRC Press, 2017. http://dx.doi.org/10.1201/9780203743805-11.
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« DHA as a Mediocre Permeability Barrier against Cations ». Dans Omega-3 Fatty Acids and the DHA Principle. CRC Press, 2009. http://dx.doi.org/10.1201/9781439813003-c8.
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Attia-Ismail, Salah Abdelaty. « Lipids in Halophytes ». Dans Halophytic Plants for Animal Feed : Associated Botanical and Nutritional Characteristics, 83–97. BENTHAM SCIENCE PUBLISHERS, 2022. http://dx.doi.org/10.2174/9789815050387122010011.
Texte intégralRésumé :
Some halophytes are good sources of oil production for human consumption. However, lipids in halophytes have vital functions with respect to their adaptation to conditions of high salinity. They play an active role in cell membrane selective permeability to toxic ions. During the process of plant adaptation, the fatty acid compositions of halophytic lipids change to play a unique role. Fatty acid composition, as well as makeup, varies considerably from one organ to another in halophytes. This chapter discusses the lipid and fatty acid contents of halophytes, the effect of salinity on lipid contents and compositions of halophytes, the utilization of halophytic lipids by animals, and the interrelations between dietary fat and animal metabolism.
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Pérez-Cabeza De Vaca, Rebeca, Balasubramaniyan Vairappan, Tomás Cortés Espinoza, Juan Antonio Suárez Cuenca, Cuauhtemoc Licona Cassani, Brenda Maldonado Arriaga, Chrisitan Navarro Gerrard, Diana Selene Morgan Penagos, Paul Mondragón Terán et Victoria Chagoya De Sanchez. « Spontaneous Bacterial Peritonitis : Physiopathological Mechanism and Clinical Manifestations ». Dans Advances in Hepatology. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.96910.
Texte intégralRésumé :
Changes in intestinal permeability have been determined to influence secondary inflammatory reactions and clinical manifestations such as spontaneous bacterial peritonitis (SBP) secondary to cirrhosis. As of yet, no in-depth exploration of the changes in the microbiota and how this influences cirrhosis to differ from clinically more severe cases than others has not begun. However, at the level of pathophysiological mechanism, it must be taken into account that due to the abuse of substances such as alcohol and chronic fatty liver disease, changes in the bacterial composition and intestinal permeability are induced. This set of changes in the bacterial composition (microbiome) and modification of the intestinal permeability could be related to the presence of ascites and spontaneous peritonitis secondary to cirrhosis, being of relevance the knowledge of the mechanisms underlying this phenomenon, as well as clinical manifestation. Prophylaxis and antibiotic treatment of SBP requires clinical knowledge for the treatment decisions based mainly on the presence of ascitic fluid, accompanied of risk factors, laboratory indexes such as PMN count and culture results, in order to determine the kind of molecule that will help to the SBP recovery or to amelioration symptoms, always taking care of not exceed the antibiotic consumption and restoring the microbiome imbalance.
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Camilleri, Michael. « Irritable Bowel Syndrome : Peripheral Mechanisms, Biomarkers, and Management ». Dans Mayo Clinic Illustrated Textbook of Neurogastroenterology, 249–76. Oxford University Press, 2021. http://dx.doi.org/10.1093/med/9780197512104.003.0011.
Texte intégralRésumé :
Several peripheral mechanisms result in symptoms of irritable bowel syndrome. They include abnormal colonic transit and rectal stool evacuation; intraluminal irritants such as short-chain fatty acids, bile acids, or gluten; microbiome changes; enteroendocrine cell products; and genetic susceptibility. Irritants can increase mucosal permeability, cause immune activation, activate local reflexes to alter intestinal motility or secretion, and induce visceral hypersensitivity and pain. IBS management is based on predominant symptom relief rather than targeting specific mechanisms. However, biomarkers are being identified and introduced into practice, such as colonic transit and fecal BA excretion and should lead to individualized, specific treatments of IBS.
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M. Heshmati, Hassan. « Treatment of Nonalcoholic Fatty Liver Disease through Changes in Gut Microbiome and Intestinal Epithelial Barrier ». Dans Advances in Hepatology. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.97568.
Texte intégralRésumé :
Nonalcoholic fatty liver disease (NAFLD) is a leading liver disease worldwide with a prevalence of approximately 25% among adult population. The highest prevalence is observed in Middle East and the lowest prevalence in Africa. NAFLD is a spectrum of liver disorders ranging from simple steatosis to nonalcoholic steatohepatitis (NASH). Pro-inflammatory diet, overweight/obesity, inflammation, insulin resistance, prediabetes, type 2 diabetes, dyslipidemia, disrupted gut microbiome, and impaired intestinal barrier function are important risk factors associated with and/or contributing to NAFLD. Gut microbiome is a complex and diverse microbial ecosystem essential for the maintenance of human health. It is influenced by several factors including diet and medications. Gut microbiome can be disrupted in NAFLD. Intestinal epithelial barrier is the largest and most important barrier against the external environment and plays an important role in health and disease. Several factors including diet and gut microbiome impact intestinal barrier function. NAFLD can be associated with impaired intestinal barrier function (increased intestinal permeability). There are no specific drugs that directly treat NAFLD. The first-line therapy of NAFLD is currently lifestyle intervention. Weight loss is an important component in the treatment of NAFLD subjects who have excess body weight. Gut microbiome and intestinal epithelial barrier are becoming promising targets for the treatment of several diseases including NAFLD. In the absence of approved pharmacotherapy for the treatment of NAFLD/NASH, in addition to lifestyle intervention and weight loss (in case of excess body weight), focus should also be on correcting gut microbiome and intestinal permeability (directly and/or through gut microbiome modulation) using diet (e.g., low-fat diet, high-fiber diet, and Mediterranean diet), prebiotics (nondigestible food ingredients), probiotics (nonpathogenic living microorganisms), synbiotics (combination of prebiotics and probiotics), and fecal microbiota transplantation (transfer of healthy stool).
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Auguet, Teresa, Laia Bertran et Jessica Binetti. « Intestinal Dysbiosis and Non-Alcoholic Fatty Liver Disease ». Dans Human Microbiome. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.92972.
Texte intégralRésumé :
Non-alcoholic fatty liver disease (NAFLD) affects 20–30% of the population, with an increased prevalence in industrialized regions. Some patients with NAFLD develop an inflammatory condition termed non-alcoholic steatohepatitis (NASH) that is characterized by hepatocellular injury, innate immune cell-mediated inflammation, and progressive liver fibrosis. In clinical practice, abdominal imaging, which reveals hepatic steatosis, is sufficient for NAFLD diagnosis if other diseases have been rejected. However, a liver biopsy is needed to differentiate NASH from simple steatosis. Therapeutic strategies used to treat obesity and metabolic syndrome improve NAFLD, but there is no specific treatment effective for NASH. The gut microbiota (GM) is composed of millions of microorganisms. Changes in the GM have a significant impact on host health. Intestinal dysbiosis is an imbalance in the GM that can induce increased permeability of the epithelial barrier, with migration of GM-derived mediators through portal vein to the liver. These mediators, such as lipopolysaccharides, short-chain fatty acids, bile acids (BAs), choline, and endogenous ethanol, seem to be involved in NAFLD pathogenesis. Given this evidence, it would be interesting to consider GM-derived mediator determination through omics techniques as a noninvasive diagnostic tool for NASH and to focus research on microbiota modulation as a possible treatment for NASH.
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« Water Vapor Permeability, Water Solubility, and Microstructure of Emulsified Starch–Alginate–Fatty Acid Composite Films ». Dans Transport Phenomena in Food Processing, 257–68. CRC Press, 2016. http://dx.doi.org/10.1201/9781420006261-20.
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Li, Sinian, Yiming Shao, Kanglan Li, Changmei HuangFu, Wenjie Wang, Zhou Liu, Zhiyou Cai et Bin Zhao. « Vascular Cognitive Impairment and the Gut Microbiota ». Dans Advances in Alzheimer’s Disease. IOS Press, 2022. http://dx.doi.org/10.3233/aiad220026.
Texte intégralRésumé :
Vascular cognitive impairment (VCI), the second most common cause of dementia in elderly people, is a term that refers to all forms of cognitive disorders that can be attributed to cerebrovascular disease such as manifestations of discrete infarctions, brain hemorrhages, and white matter lesions. The gut microbiota (GM) has emerged recently as an essential player in the development of VCI. The GM may affect the brain’s physiological, behavioral, and cognitive functions through the brain-gut axis via neural, immune, endocrine, and metabolic pathways. Therefore, microbiota dysbiosis may mediate or affect atherosclerosis, cerebrovascular disease, and endothelial dysfunction, which are the predominant risk factors for VCI. Moreover, the composition of the GM includes the bacterial component lipopolysaccharides and their metabolic products including trimethylamine-N-oxide and short-chain fatty acids. These products may increase the permeability of the intestinal epithelium, leading to systemic immune responses, low-grade inflammation, and altered signaling pathways that are associated with the pathogenesis of VCI. In this review, we discuss the proposed mechanisms of the GM in the maintenance of VCI and how it is implicated in acquired metabolic diseases, particularly in VCI regulation.
Actes de conférences sur le sujet "Fattor permeabilità"
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Ting, Lucas, Jessica Jahn et Nathan Sniadecki. « Endothelial Cell Permeability and Alignment Quantification Under Shear Flow ». Dans ASME 2010 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2010. http://dx.doi.org/10.1115/sbc2010-19705.
Texte intégralRésumé :
Atherosclerosis develops when a breach in the protective endothelium allows macrophages and fatty lipids to enter into the intima. Atherosclerotic plaque material can harden the vessel or constrict blood flow through the vessel. In some cases, the plaque can detach and initiate a cardiac event (1). Hemodynamic shear can act as a mechanical factor that regulates the endothelial barrier by initiating a cellular mechanotransduction response that remodels the structure of individual endothelial cells (2).
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Lucarini, Simone. « Lactose-based Fatty Acid Monoesters : Synthesis, antimicrobial activity and permeability enhancement studies ». Dans 5th International Electronic Conference on Medicinal Chemistry. Basel, Switzerland : MDPI, 2019. http://dx.doi.org/10.3390/ecmc2019-06340.
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Patella, Francesca, Zachary T. Schug, Erez Persi, Lisa J. Neilson, Zahra Erami, Daniele Avanzato, Federica Maione et al. « Abstract B17 : In-depth proteomics unveils fatty acid oxidation role in controlling vascular permeability ». Dans Abstracts : AACR Special Conference : Tumor Angiogenesis and Vascular Normalization : Bench to Bedside to Biomarkers ; March 5-8, 2015 ; Orlando, FL. American Association for Cancer Research, 2015. http://dx.doi.org/10.1158/1538-8514.tumang15-b17.
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Leyva Gutierrez, Francisco, et Tong Wang. « Crystallography and Functionality of Natural Waxes : Insights for the Development of Tailored Lipid Materials ». Dans 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/nyok4571.
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Natural waxes are valuable industrial products consisting of complex chemical mixtures. To probe the structure−function role of select constituents, model n-alkanes, alcohols, aldehydes, and fatty acids of C18−19, C22−23, and C26−27 carbon chain lengths were synthesized and analyzed via calorimetry and X-ray powder diffraction. Pure compounds and binary mixtures crystallized into monoclinic (M), triclinic (T), and orthorhombic (O) lattices or combinations thereof. The C26 aldehyde formed an O lattice and exhibited one solid−solid phase transition similar to n-alkanes. The water vapor permeability (WVP) of model systems cast as films was determined. For pure compounds, WVP decreased in the following order: fatty acid > even n-alkane > odd n-alkane > alcohol > aldehyde. Increasing carbon chain length, which translates to increasing unit cell volume, decreased WVP. Binary mixtures generally exhibited a more complex relationship with WVP. These findings may be applicable to the agricultural postharvest, pharmaceutical, and paperboard coating industries.
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Murphy, S. « STORAGE OF PLATELETS FOR TRANSFUSION - CURRENT METHODS AND PROBLEMS TO BE SOLVED ». Dans XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643999.
Texte intégralRésumé :
In the 1970's, when platelet concentrates (PC) were stored in "first generation" plastic containers at 22°C, many showed a fall in pH.In vivo viability was well maintained as pH fell from the starting level, 7.1, to 6.2 but was progressively lost below thatlevel. pH after a storage interval correlated with the platelet count in the PC, the higher the count, the lower the pH after storage. Since 30-50% of PC might have pH below 6.2 after 3 days of storage, shelflife was severely limited.We now have "second generation" containers which allow storage for 7 days without significant fall in pH.Superior pH maintenance results from increased oxygen transport through the walls of the container thuspreventing platelet hypoxia within. Under all circumstances which we have examined, PC, pH correlates inversely with lactate concentration. The superiority of the "second generation" containers results from the lower rate of glycolysis within them due to the Pasteur effect. Like many cells, the platelet has a baseline rate of lactate production which is increased up to 8 times if oxidative metabolism is interrupted by hypoxia. For any container, there is an inverse relationship between PC pCL and platelet count since each platejlet |as a fixed oxygen demand. In "first generation" containers, the pO2 approached zero with platelet counts, 1.0-1.5 × 106 /mm3 , a range commonly seen in practice. At platelet counts above thatlevel, the platelets would have an increasing oxygendebt. The greater the oxygen debt is, the greater will be the rate of lactate production per platelet and, therefore, the rate of pH fall. An ideal "second generation" container will have oxygen permeability twice thgt 05 a "first generation" container such that platelets will begin to have an oxygen debt at platelet count, 2.4 × 106/mm3 , a level rarely seen in practice. In "second generation" containers, there is a continuing, linear production of lactate in spite of adequate oxygen supply. The major buffer in plasma for the hydrogen ion accompanying lactate production is bicarbonate. As lactate is produced, bicarbonate is consumed and pH remains stable until bicarbonate is completely depleted.Thereafter, pH falls precipitously.However, there is adequate bicarbonate in the 50 ml of plasma used as medium for the PC to buffer the baseline production of lactate for seven days.This is the major reason why storage for sevendays is now satisfactory.With knowledge of the oxygen transport capability of a container and measurement of pO2 within the container, we can calculate the rate of oxygen consumptionduring storage, 1.1 nmol/min/109 platelets. Knowing the rates of oxygen consumption and lactate production and the predicted rate of ATP synthesis from ADP for each type of metabolism we calculated that 85% ofATP regeneration is from oxidative metabolism. When we contrasted the rate of glucose consumption with the rate of lactate production, we were surprised that the slope of the regression line was exactly 0.5 suggesting that two moles of lactate were produced for each mole of glucose utilized and that there must be a prominent substrate for oxidative metabolism other than glucose. Recent work in our laboratory suggests fatty acid as such a substrate.There is much to be learned about storage in "secondgeneration" containers. At the onset of storage 70% of the platelets have a discoid appearance whereas after seven days only 30% do with most of the rest being spheres. Furthermore, 5-10% of cells are "leaf-shaped", elongated tubules, or ring forms. In addition, many studies have described reduced platelet function in vitro after storage. There is a 20-50% reduction in the maximal extent of aggregation with high ADP concentrations and the concentrations of single agonists which produce 50% of maximal response are increased after storage. However, we have been encouraged to find that the response to these agents was reduced much less when they were used a pairs. Finally, there is concern that trace bacterial contamination at the time of phlebotomy might allow enough proliferation to produce sepsis in recipients. Further research should improve our understanding inthese areas and the safety and efficacy of platelets after storage.
Rapports d'organisations sur le sujet "Fattor permeabilità"
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Fallik, Elazar, Robert Joly, Ilan Paran et Matthew A. Jenks. Study of the Physiological, Molecular and Genetic Factors Associated with Postharvest Water Loss in Pepper Fruit. United States Department of Agriculture, décembre 2012. http://dx.doi.org/10.32747/2012.7593392.bard.
Texte intégralRésumé :
The fruit of pepper (Capsicum annuum) commonly wilts (or shrivels) during postharvest storage due to rapid water loss, a condition that greatly reduces its shelf life and market value. The fact that pepper fruit are hollow, and thus have limited water content, only exacerbates this problem in pepper. The collaborators on this project completed research whose findings provided new insight into the genetic, physiological, and biochemical basis for water loss from the fruits of pepper (Capsicum annuum and related Capsicum species). Well-defined genetic populations of pepper were used in this study, the first being a series of backcross F₁ and segregating F₂, F₃, and F₄ populations derived from two original parents selected for having dramatic differences in fruit water loss rate (very high and very low water loss). The secondly population utilized in these studies was a collection of 50 accessions representing world diversity in both species and cultivar types. We found that an unexpectedly large amount of variation was present in both fruit wax and cutin composition in these collections. In addition, our studies revealed significant correlations between the chemical composition of both the fruit cuticular waxes and cutin monomers with fruit water loss rate. Among the most significant were that high alkane content in fruit waxes conferred low fruit water loss rates and low permeability in fruit cuticles. In contrast, high amounts of terpenoids (plus steroidal compounds) were associated with very high fruit water loss and cuticle permeability. These results are consistent with our models that the simple straight chain alkanes pack closely together in the cuticle membrane and obstruct water diffusion, whereas lipids with more complex 3-dimensional structure (such as terpenoids) do not pack so closely, and thus increase the diffusion pathways. The backcross segregating populations were used to map quantitative trait loci (QTLs) associated with water loss (using DART markers, Diversity Arrays Technology LTD). These studies resulted in identification of two linked QTLs on pepper’s chromosome 10. Although the exact genetic or physiological basis for these QTLs function in water loss is unknown, the genotypic contribution in studies of near-isogenic lines selected from these backcross populations reveals a strong association between certain wax compounds, the free fatty acids and iso-alkanes. There was also a lesser association between the water loss QTLs with both fruit firmness and total soluble sugars. Results of these analyses have revealed especially strong genetic linkages between fruit water loss, cuticle composition, and two QTLs on chromosome 10. These findings lead us to further speculate that genes located at or near these QTLs have a strong influence on cuticle lipids that impact water loss rate (and possibly, whether directly or indirectly, other traits like fruit firmness and sugar content). The QTL markers identified in these studies will be valuable in the breeding programs of scientists seeking to select for low water loss, long lasting fruits, of pepper, and likely the fruits of related commodities. Further work with these newly developed genetic resources should ultimately lead to the discovery of the genes controlling these fruit characteristics, allowing for the use of transgenic breeding approaches toward the improvement of fruit postharvest shelf life.