111,968 research outputs found
Helicobacter pylori Pathogenic Factors
No full textFrom 1994, Helicobacter pylori was classified by WHO (World Health Organization) as a class I carcinogen and its infection has been associated to gastroduodenal disease. It colonizes more than half of worldwide population, with a prevalent infection rate in developed countries. In spite of the majority of infected people are asymptomatic, around 20% develop severe pathologies like peptic ulcers and the 1% lymphoma of the mucosa-associated lymphoid tissue (MALT) and stomach cancer. This significant epidemiological study both of the unique characteristics of H. pylori inspired many scientists, as bacteriologist, gastroenterologists, cancer and pharmaceutical scientists to understand physio-pathological aspects of this bacterium, and also microbiologist, taxonomist, microbial ecologist and molecular biologist, for a more detailed molecular approach.
H. pylori, a Gram negative, microaerophilic bacteria that colonize human gastric mucosa. It is not an acidophilus bacterium and even if the stomach lumen presents inhospitable condition for most microbes, it is able to survive for a short period, sufficient to enter in the highly viscous mucosa, reach gastric epithelium, and colonize the gastro-enteric tract. H. pylori colonization is mediated by a predominant virulence factor, the flagellar motility associated to chemotaxis. To avoid its discharge in the intestinal tract by peristalsis, the bacteria establish a persistent infection inside the viscous gastric mucus film that covers the gastric epithelium. A nickel containing enzyme, the urease, hydrolyzes the urea present in the stomach to ammonia and CO2, buffering the pH of the periplasm. The most severe clinical outcomes are always associated to cag+ strains. cag-PAI is defined as the “Cytotoxic Associated Genes Pathogenicity Island” and it consists of a characteristic chromosome, flanked by transposable elements. Another important virulent factor is the vacuolating cytotoxin A, known as VacA, which induces the formation of large cytoplasmic vacuoles in gastric cultured cell lines. Moreover the iron and nickel acquisition is essential grow factors and a large number of genes are responsible of this mechanism.
While the development of an efficient vaccine against H. pylori is now the aim of many researchers, the search for new specific antibiotics as a new pharmaceutical target is required for the complete eradication of H. pylori.
In this thesis has been investigate the structural and function role of different pathogenic proteins involved in the H. pylori colonization of human gastric mucosa. These potential drug targets have been cloned, 8 out of 11 were expressed in a heterologous expression system, after purification, 2 of them generate protein crystals and only one was possible to characterize the molecular structure. In particular it has been elucidated a possible physiological role of CeuE (HP1561), a Class III SPB (Substrate Binding Protein), crystalized with Ni(His)2 complex and it was determined its affinity to the complex by an in vitro approach. The H. pylori flagella play a key role during infection allowing the bacterium to move through the mucous layer. The H. pylori hook scaffolding protein FlgD were cloned, expressed, purified and crystalized. A study of other purified pathogenic H. pylori factors belonging to flagellar component apparatus and transcriptional factors involved in cellular stress response has been reported.
To obtain these results, different experimental approaches has been used. Bioinformatics analysis of target proteins has been performed to predict the best candidates for a crystallographic study and for genetic construction design. Molecular cloning in plasmid vectors has been performed from PCR amplification. The expression conditions were optimized and performed in E. coli, a heterologous system. The solubility of recombinant proteins were checked and obtained also with protein refolding methods. Different purification techniques were used in order to obtain pure protein. Target characterization was performed due analytical gel filtration, UV spectroscopy, DLS (Dynamic Light Scattering) and CD (Circular Dichroism). The proteins were concentrated to crystallization trials. The protein crystals obtained were analyzed at ESRF synchrotron (Grenoble, France). Functional in vitro approaches were performed using fluorescence spectroscopy, SPR (Surface Plasmon Resonance) and Mass spectroscopy.
In the second chapter is described the three dimensional structure of a H. pylori pathogenic protein crystalized in presence with its possible physiological substrate. HP1561 (CeuE) is a H. pylori protein predicted to be an ABC transporter component, periplasmic iron-bind transporter. Recently it was published that CeuE and fecDE genes of H. mustelae encode for a nickel and cobalt acquisition system. In Gram-negative bacteria, nickel uptake is guaranteed by multiple and complex systems that operate at the membrane and periplasmic level. H. pylori employs other yet uncharacterized systems to import the nickel required for the maturation of key enzymes, such as urease and hydrogenase. To understand this contradiction of the data about Ni2+ acquisition system in H. pylori CeuE was cloned, expressed, purified, crystallized and its structure determined. Identity between the sequences of the two Helicobacter is 44%. The two Histidine residues (H103 and H197), potentially involved in Siderophores/Ni2+ binding coordination in H. pylori CeuE, are partially conserved. The His corresponding to H. pylori position 103 is conserved, whilst His197 is replaced by a Leucine. In order to check, if this substitution influence the binding of siderophores/Ni2+, the mutant of H. pylori CeuE H197L was than produced and purified. The crystal structure of H. pylori CeuE has been determined at 1.65Å resolution using the SAD method, in Apo-form and in complex with Ni(His)2. It comprises two structurally similar globular domains, each consisting of a central five-stranded β-sheet surrounded by α-helices, an arrangement commonly classified as a Rossmann-like fold. Structurally, H. pylori CeuE belongs to the class III periplasmic substrate-binding protein. Crystallographic data, fluorescence binding assays and SPR analysis allow to exclude a role of the protein in the transport of VitB12, heme, enterobactin and isolated Ni2+ ions. On the contrary, the crystal structure of the protein/Ni(L-His)2 complex and dissociation constant obtained by SPR technique suggests that H. pylori CeuE binds and transport nickel in vivo thanks to the formation of a Ni2+/histidine complex or to some ligand that mimics it.
In the third chapter is presented the study of FlgD, a flagellar component involved in the formation the extracellular complex, the flagellar hook. The motility of H. pylori is considered a colonization factor, due the fact that less motile strains are less able to colonize or survive in the host than full motile strains. In the flagellum machinery are involved more than 50 genomic genes for regulation and assembly. The three major components are the filament, the hook and the basal body. FlgD is not present when the flagellum is completed, but plays a key role during the assembly. Therefore, it has been classified as the hook-scaffolding protein, considering it also as the hook capping protein, interacting with FlgL and FlgK and the basal body rod – modification protein. In H. pylori G27 strain FlgD correspond to the gene hp0858 that was amplified from purified genomic DNA and cloned in an expression plasmid vector. The protein was produced in E. coli BL21 in reach medium ad it resulted to a soluble protein. DLS and analytical gel filtration confirm the oligomeric state of FlgD that resulted to be a tetramer in solution. The protein was concentrated to 30g/l and crystalized after a couple of month of incubation. The crystals had diffracted at 2.7Å of maximum resolution. For molecular replacement approach was used homology modeling. Different molecular models were built to fit experimental diffraction data. The secondary structure of the generated models was fitted with experimental CD spectra, where FlgD resulted to have around 12% of helices and 45% of β-sheets (190-260nm). Crystallographic statistics do not properly converged to a positive molecular refinement with the tested models. To solve FlgD structure are necessary crystals of recombinant Selenomethionine FlgD that was expressed, purified and crystalized.
In the fourth chapter are reported H. pylori pathogenic proteins that had been characterized. These proteins could be divided in two groups, the first one of flagellar proteins and the second of cellular stress response factors, in collaboration with Professor V. Scarlato of the department of Biology of Bologna University.
FliN is a cytosolic protein, localized in the C ring of the flagellar basal body. It interacts with the other two components FliM and FliG. Missense or mutation of fliN had been associated to non-motile strains. It has been reported that regulates the clockwise/counterclockwise switching of flagella. H. pylori FliN was cloned, expressed and purified from the inclusion body after refolding. Oligomerization after refolding was tested by DLS and analytical gel filtration. The protein resulted to be poly-disperse in solution and no protein crystals have been obtained.
FliD is the filament capping protein and it was observed that interact with FliT that is not only a flagellar type III substrate specific export chaperone but also inhibits the expression of fliD thought its specific interaction with the master regulator FlhD4C2 complex. In order to analyze possible structure of the co-crystalized FliD-FliT, it was plan to co-express these proteins. Both were cloned with a different affinity purification system, but only FliT was possible to express and purify from inclusion bodies. The CD spectra presented a strong β-sheet component in the secondary structure. DLS and analytical gel filtration revealed that this protein is poly-disperse in solution and no protein crystals were be obtained.
FlgN is a type III secretion chaperone and it has been reported to interact with the two hook junction protein FlgK and FlgL preventing the protein proteolysis when the flagellum is not assembled. These proteins have been cloned in different type of plasmid vectors for a co-expression experiment, but only FlgN was properly expressed in E. coli. Recombinant FlgN was purified by Ni-IMAC and resulted to be soluble in solution. The protein was characterized by analytical gel filtration, DLS and CD. The protein resulted to be a monomer in solution with a 30% of not defined secondary structure (190-260nm). FlgN was concentrated and different crystallization conditions were tested.
In the latter group there are three proteins related to Heat shock response, produced when bacteria encounter stress such as the elevated temperatures, ethanol, H2O2 and acid. It was demonstrated that H. pylori Hsps play an important role during the host infection. HrcA and HspR are negative repressor of groESL and dnaK machinery. HrcA activity depends by the presence of HspR, because it is demonstrated that HrcA is not able to bind DNA in absence of HspR. These two proteins were expressed in E. coli and purified by Ni-IMAC affinity. During the concentration step, these proteins present a solubility limit influenced by the concentration. Mutagenesis of a Cys in HspR and detergent solubility screening with HrcA has been performed, but no suitable protein for crystallization trials has been obtained.
Hp1026 is a gene present in the same operon of HspR (hp1025). The function of this gene has not been reported. From sequence homology was possible to identify a helicase domain and ATP-binding domain. This protein, ORF, has been expressed in E. coli and purified by Ni-IMAC affinity. Analytical gel filtration and CD has been performed to characterize this protein. The protein was a dimer in solution with a 35% of α-helices component. Crystallization trials have been performed at different protein concentrations and also in presence of its possible cofactor, ATPγS. No crystals have been obtained in tested condition.
Appendix:
Structural and functional study on a human protease S1P/ SKI1
The study of human S1P/SKI1 protease was performed in collaboration with Professor S. Kunz of the Institute of Microbiology, University Hospital Center and university of Lausanne, Switzerland. S1P/SKI-1 is a serine protease that belongs to the mammalian family of Proprotein Convertases (PC). The aim of this family member is to mediate the activation of different important substrates for cell live. Among these proteases, S1P has been shown to have unique substrate specificity, preferring cleavage after non-basic amino acids. Known S1P cellular targets are SREBP-2, involved in the biosynthesis and uptake of lipids and cholesterol, BDNF, ATF-6 and the surface glycoprotein of viruses belonging to the family of Arenaviridae. S1P is 118 kDa multi-domain protein; two regions of S1P have been investigated, the "Prodomain", involved in the regulation of S1P catalytic activity, and the so called "catalytic domain", which include the residues responsible for the cleavage reaction itself. Moreover it was analyzed an inactive mutant of cS1P: H249A. Also for ProD was chosen one constructs (ProD_AB and ProD_AC) involved in the affinity of the protease substrate. Hence, the sequences corresponding to the domains were synthesized as optimized genes for the expression in E. coli and sub-cloned in expression plasmids in order to obtain C-term His-tagged fusion proteins. These constructs have been expressed in E. coli, purified by Ni-IMAC and positive fractions have been collected and concentrated in order to perform crystallization trials. Unfortunately no protein crystals have been obtained in tested condition. To elucidate the role of a mutated variant of the cleavage site “C” of Pro Domain, it was performed a mass spectrometry analysis. Secreted S1P/SKI1 mutant C was purified from culture medium of HEK293 cell line was isolated by IMAC-Co. The sample, loaded in RP-HPLC, was denatured in 6 M Guanidine-HCl. The chromatographic fractions corresponding to the major HPLC peaks were dried out in a speed-vac concentrator and directly injected in the ESI source. Mass measurements were performed with a quadrupole-TOF spectrometer. Analysis of mass spectra, compared with wild-type form of S1P, allows generating a preliminary Pro Domain auto-processing profile.Dal 1994 il batterio Helicobacter pylori è stato classificato come organismo cancerogeneno di prima classe e la sua infezione è associata a patologie gastroduodenali. Più di metà della popolazione mondiale ne è infettata con una maggiore prevalenza nei paesi sviluppati. Nonostante la maggior parte dei casi le infezioni sono asintomatiche, il 20% sviluppa gravi patologie come ulcere peptiche e nell’1% dei casi genera linfomi e gastro carcinomi. L’incidenza e le caratteristiche di questo batterio hanno ispirato batteriologi, gastroenterologi, oncologi e farmacologi per indagare gli aspetti fisiopatologici legati all’infezione, così come microbiologi, ecologi, biologi molecolari hanno cercato i fattori di virulenza coinvolti in nell’infezione.
H. pylori è un batterio microaerofilico Gram negativo che colonizza la mucosa gastrica. Non è un batterio acidofilo, anche se è in grado di sopravvivere nel lume dello stomaco per un breve periodo necessario per raggiungere le cellule epiteliali spostandosi attraverso la mucosa gastrica. La colonizzazione è mediata da fattori di virulenza predominanti come la motilità flagellare associata alla chemiotassi. Per evitare che sia espulso dal tratto intestinale dalla peristalsi, il batterio H. pylori stabilisce un’infezione cronica. L’ureasi, che è un enzima nickel dipendente, che idrolizza l’urea presente in ammoniaca e CO2 tamponando il pH acido dello stomaco. I casi più gravi sono associati ai ceppi che esprimono l’isola di patogenicità cag-PAI, che consiste in un cromosoma delimitato da elementi trasponibili. Un altro importante fattore di virulenza è la tossina vacuolizzante VacA, che induce la formazione di vacuoli citoplasmatici. Anche il meccanismo di acquisizione di ferro e nickel è fondamentale per la colonizzazione batterica e dunque finemente regolata da un gran numero di geni.
Lo sviluppo di un vaccino e nuovi antibiotici nutrono una costante ricerca di nuovi possibili bersagli farmacologici, necessari per completa ed efficiente eradicazione del batterio H. pylori.
In questa tesi sono stati analizzati il ruolo e la struttura di alcune proteine patogenetiche del H. pylori. Questi potenziali target farmacologici sono stati clonati, otto su undici sono stati espressi in un sistema eterologo, due proteine di quelle purificate hanno generato cristalli e di una sola ne è stata definita la struttura molecolare. In particolare è stato definito un possibile ruolo della proteina CeuE (HP1561), appartenete alla famiglia delle proteine che legano un substrato, cristallizzata in presenza del complesso Ni(His)2 e definita l’affinità con lo stesso in vitro.
Del flagello, che svolge un ruolo chiave durante l’infezione, ne è stata studiata la proteina coinvolta nella formazione dell’uncino FlgD che è stata clonata, espressa, purificata e cristallizzata.
Inoltre è stato riportato anche uno studio di altri fattori del flagello e di alcune proteine coinvolte nella risposta allo stress cellulare.
Per ottenere tali risultati sono stati utilizzati approcci differenti. Per individuare le migliori proteine candidate per uno studio cristallografico e progettare costrutti funzionali sono state effettuate predizioni bioinformatiche. Gli amplificati di PCR sono stati clonati in vettori plasmidici. Le condizioni di espressione sono state ottimizzate e fatte in E. coli, un sistema di espressione eterologo. La solubilità delle proteine ricombinanti è stata analizzata e ottenuta anche mediante refolding. Sono stati usati diversi sistemi di purificazione per ottenere un buon grado di purezza. Per la caratterizzazione proteica sono state usate come tecniche la gel filtrazione analitica, spettroscopia UV, DLS (Dynamic Light Scattering) e dicroismo circolare. Le proteine sono state concentrate e sottoposte a esperimenti di cristallizzazione. I cristalli sono stati analizzati al sincrotrone ESRF (Grenoble, France). Spettroscopia di fluorescenza, SPR (surface plasmon resonance) e spettroscopia di massa sono le tecniche utilizzate per la caratterizzazione In Vitro.
Nel secondo capitolo viene decritta la struttura tridimensionale di una proteina patogenetica di H. pylori, cristallizzata in presenza del suo possibile substrato fisiologico. HP1561 (CeuE) è una proteina di H. pylori annotata come componente periplasmatico di un trasportatore ABC che lega e trasporta il ferro. Recentemente è stato pubblicato chele ceuE e fecDE di H. mustelae codificano per proteine coinvolte nel acquisizione del nickel e cobalto. Nei Gram negativi, l’acquisizione del nickel è garantita da sistemi di proteine che operano a livello di membrana e periplasmatico. Per l’acquisizione del nickel, l’ H. pylori integra diversi sistemi non ancora caratterizzati, necessari per la maturazione di enzimi chiave come l’ureasi e l’idrogenasi. Per chiarire tale contraddizione nel sistema di acquisizione del nickel nell’H. pylori, CeuE è stata clonata, espressa, purificata, cristallizzata e la sua struttura è stata risolta. L’identità di sequenza tra i due Helicobacter (pylori e mustelae) è del 44%. Le due Istidine (H103 e H197), potenzialmente coinvolte nel legame di coordinazione del sistema sideroforo/Ni2+ nel H. pylori CeuE, risultano essere parzialmente conservate. L’His corrispondente alla His103 di H. pylori è conservata, mentre His197 è sostituita da una Leucina. Al fine d’identificare se tale mutazione possa influenzare il legame sideroforo/Ni2+, è stato prodotto e purificato il mutante H. pylori CeuE H197L. La struttura molecolare di H. pylori CeuE è stata determinata con una risoluzione di 1.65 Å mediante metodo SAD, sia nella forma apo, che in complesso col Ni(His)2. Essa è costituita da due domini globulari simili, ognuno costituito da cinque foglietti-β circondati da α-eliche, comunemente classificato come Rossman fold. Strutturalmente H. pylori CeuE appartiene alla Classe III della famiglia di proteine che legano un substrato specifico (SBPs). Dati cristallografici, saggi di fluorescenza e analisi all’SPR ci permettono di escludere il coinvolgimento della proteina nel trasporto della VitB12, eme, entrobactina, e ioni Ni2+ isolati. Al contrario la struttura della proteina/complesso Ni(His)2 e le costanti di dissociazione ottenute mediante SPR suggeriscono che H. pylori CeuE lega e trasporta il nickel in vivo mediante il complesso Ni2+/His o altro ligando che lo mima.
Nel terzo capitolo viene presentato lo studio su FlgD, una proteina flagellare fondamentale nella formazione di un complesso extracellulare, l’uncino del flagello. La motilità dell’H. pylori è considerata un fattore di colonizzazione, attraverso il quale ceppi meno motili hanno minori possibilità di colonizzare e sopravvivere nell’ospite di ceppi più motili. Per la formazione del flagello sono coinvolti più di 50 geni per la regolazione e l’assemblaggio delle varie componenti. Le tre componenti principali sono il filamento, l’uncino e il corpo basale. FlgD non è presente quando il flagello è maturo, ma ha un ruolo chiave durante l’assemblaggio. Perciò, è stato classificato come proteina necessaria per l’impalcatura dell’uncino (hook scaffolding protein), consi
Os usos da métis: Odisseu (VIII a.C.) e a Batalha de Salamina (V a.C.)
Get PDFO presente artigo tem como recorte temporal os séculos VIII e V a.C., e nele buscamos apresentar a noção métis (astúcia/ardil) nos casos de Odisseu e da Batalha de Salamina. Para tanto, faremos uso do conceito de “representações sociais” para compreender os valores na documentação textual e imagética acerca dos navegantes, uma vez que as habilidades astuciosas (métis) eram fundamentais no cotidiano desses
Salamina e Psittalia : teatro e storia a confronto
No full textIl legame tra teatro e politica nell’Atene del V secolo a.C. viene indagato alla luce della storia. Si propone una rilettura dei Persiani, analizzando il rapporto tra Eschilo e Temistocle sulla base delle altre testimonianze storiche e letterarie rimaste. Secondo l’interpretazione tradizionale, la descrizione della vittoria di Salamina rifletterebbe una presa di posizione da parte di Eschilo verso Temistocle. Il problema non può prescindere dalla complessa questione sulla data dell’ostracismo di Temistocle. Nei Persiani di Eschilo, all’episodio di Salamina si affianca Psittalia. Un episodio apparentemente secondario delle guerre persiane assume un rilievo particolare. Eschilo vuole esaltare Aristide diminuendo la gloria di Temistocle? Si corre il rischio di ridurre la storia a binomi, con la tradizionale opposizione di Aristide a Temistocle, di Cimone a Pericle. Piuttosto, Salamina e Psittalea, per mare e per terra, si possono pensare in un’altra prospettiva. Al di là della simpatia di Eschilo per Temistocle o per Aristide, nei Persiani si celebra la concordia nell’Atene democratica: Salamina e Psittalea consacrano la libertà della Grecia. Ad una lettura storica di due passi tragici si unisce una lettura tragica di un avvenimento storico: l’episodio di Psittalea nella tragedia di Eschilo richiama la dinamica di Sfacteria, descritta da Tucidide e Diodoro, riassunta in uno scolio ad Aristofane. Là tutto andò a rovescio, con lo stesso stravolgimento delle intenzioni proprio della tragedia, e, in particolare, dell’episodio di Psittalea. Nell’esposizione dei fatti, Tucidide prende in prestito dalla tragedia categorie interpretative, come l’ironia tragica di fronte alle false aspettative. La sproporzione tra attese e realtà è tanto più tragica: le azioni si fondano su una confidenza illusoria, e i vantaggi si devono innanzitutto alle circostanze. Sempre sotteso è pure il concetto tragico secondo cui dalla prosperità alla rovina il passo è breve, se si trascende la misura: è un monito alla clemenza, perché tutti gli uomini sperimentano l’alternarsi della fortuna. Il caso diventa un principio nell’interpretazione dei fatti storici
author-bios-SRD-19-0063.R1 – Supplemental material for The Network Structure of Police Misconduct
No full textSupplemental material, author-bios-SRD-19-0063.R1 for The Network Structure of Police Misconduct by George Wood, Daria Roithmayr and Andrew V. Papachristos in Socius</p
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Strain energy density approach as fatigue assessment of Ti6Al4V specimens machined by WEDM single step technology
Get PDFThe present paper summarizes the results from force-controlled fatigue tests performed on Ti6Al4V specimens machined by wire electrical discharge machining (WEDM) single step technology. For this aim, blunt V-notched specimens with various notch root radii and un-notched “dog bone” specimens are considered. The fatigue behaviour of this alloy machined by WEDM single step technology is an extremely important issue but, despite this, the literature on this topic is very poor and the effect of geometrical discontinuities on the fatigue life of has still to be investigated. Fatigue data, generated by testing a total number of 62 specimen, are re-analysed by means of the Strain Energy Density (SED) method, investigating the possibility to use this method following a numerical approach. Estimation of the critical radius is performed on the basis of finite element analysis to overcome the lack of knowledge of the material properties often related to the machining process. Thanks to the SED method, it is possible to summarize in a single scatter-band all the collected fatigue data, independently of the specimen geometry. The proposed numerical approach is capable to reduce the scatter index compared to the actual procedure with modest extra effort, also solving the issue related to the geometry selection for the critical radius identification. The method is successfully validated by assessing the fatigue life of specimens with two notch geometries not considered during the critical radius identification. © 2022 The Author(s
Two-year population-based molecular epidemiological study of tuberculosis transmission in the metropolitan area of Milan, Italy
No full textA 2-year, population-based, molecular epidemiological study was conducted in Milan, Italy, to determine the proportion of tuberculosis (TB) cases attributable to recent transmission. All strains were typed by restriction fragment length polymorphism (RFLP) analysis; clustering was considered indicative of recent transmission. Of the 581 cases, 239 (41.1%) belonged to clusters that consisted of 2 to I I patients, 28.1% were attributable to recent transmission (number of clustered patients minus 1). Clustering was associated with multidrug-resistant Mycobacterium tuberculosis strains (74.2% of cases), AIDS (60.2%), and a history of incarceration (67.4%). The frequency of multidrug-resistant Mycobacterium tuberculosis was 5.3% overall (15.4% among AIDS patients). Among AIDS patients, infection with a resistant strain was independently associated with clustering (odds ratio, 1.32, 95% confidence interval, 1.07-1.163), while among non-AIDS patients, three factors were associated with clustering: history of incarceration (odds ratio, 2.03: 95% confidence interval, 1.41-2-92), age <30 years (odds ratio, 1.43; 95% confidence interval, 1.05-1.94), and native-born Italian nationality (odds ratio, 1.44; 95% confidence interval, 1.08-1.92). Of the 118 patients who belonged to either the smallest or the largest cluster, 19 (16.1%) reported an epidemiological link with another study patient. The results of this study highlight the need for control programs that focus on selected high-risk groups consisting primarily of HIV-infected individuals and persons with social and lifestyle risks for TB. These programs should be aimed at reducing the probability of transmission of drug-resistant TB through early identification of cases and provision of effective treatment until the individual is cured
Aprendizajes de los maestros de Salamina Caldas sobre su quehacer en tiempos de pandemia
Get PDFEl trabajo investigativo que se presenta tuvo como objetivo comprender los aprendizajes de los maestros de Salamina sobre su quehacer en tiempos de pandemia. Es así como se recurrió a un enfoque de investigación cualitativo de tipo estudio de caso colectivo. Se aplicó un formulario electrónico de única pregunta abierta a 90 maestros de Salamina, Caldas de 4 instituciones educativas: 2 rurales y 2 urbanas. El análisis de la información se efectuó a partir del método de análisis de material cualitativo. Los principales resultados encontrados evidencian la emergencia de 3 categorías: entrega-donación, reflexión práctica y actitudes de aprendizaje. Se concluye que el quehacer del maestro está marcado por las dinámicas sociales del momento. Es decir,
en las circunstancias de emergencia sanitaria actuales los maestros de Salamina, a partir de la incertidumbre, tuvieron que adaptarse a las nuevas realidades problematizando elementos cotidianos como su oficio, sus prácticas, y sus habilidades
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Orthodoxy and heresy according to saint epiphanius of salamis
Get PDFHeresy and Orthodoxy have been much discussed terms in theological studies from ancient times to the present day and various opinions and beliefs have been expressed on them. In this thesis, we have tried to gather the thought of Epiphanius on these terms on the basis of his works Panarion and Angyrotos. We have tried to let the texts of our author lead us to clear conclusions and this has meant that we made extensive use of the writings under examination. In this effort we are conscious that we have stood closer to Epiphanius' own methodology, namely his use of relevant texts, whereby the historical continuity of the faith of the Church, which lies at the root of her experience, is more adequately exposed. The thesis comprises three parts, dealing consecutively with a) Epiphanius' life and work, b) Epiphanius' views of Heresy and c) Epiphanius' views of Orthodoxy. In part a) we provide a brief account of Epiphanius' person and historical context, as well as his perception concerning his heresiology. In part b) we explore Epiphanius' sources for his account of heresy, his methodology, as well as his views on such central topics as the beginnings and development of heresy, the difference between schism and heresy, truth and heresy, church and heresy. Scripture and heresy, the devil and heresy and, finally the meaning of heresy suggested by the appelations which Epiphanius uses in his descriptions of it. In part c) we provide a general introduction on Epiphanius' understanding of orthodoxy, an account of the presuppositions of orthodoxy and the main contents of the orthodox faith as Epiphanius expounds them which comprise the topics of Theology/Triadology, Christology and Ecclesiology. In our conclusion we stress that, according to St. Epiphanius, Orthodoxy is the divinely provided and regulated truth which precedes the ecclesiastical life of the community and is expressed via all the manifestations of this life. By the same token. Heresy is any deviation from this divine and primordial truth as appropriated through and manifested in ecclesiastical life. As far as priority goes in respect to Orthodoxy and Heresy Epiphanius' view is contrary to that of Walter Bauer. For Epiphanius Orthodoxy precedes Heresy. The difference between these two views seems to lie in their choice of context. Bauer explores his topic in the context of historical and 'scientific' methods to which he subordinates his ecclesiastical data. Epiphanius develops his topic in the context of ecclesiastical tradition and life without neglecting the historical and scientific data. In Epiphanius' view ecclesiastical life and history do not constitute a field of fuction and confrontation between diverse ideologies and interpretations. Rather they constitute a living and unbreakable foundation of orthodoxy, which is expressed in the theory and practice of the Church
- …
