51 research outputs found

    Reductive Decomposition of A Diazonium Intermediate by Dithiothreitol Affects The Determination of NOS Turnover Rates

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    Accurate determination of nitrite either as such or as the breakdown product of nitric oxide (NO) is critical in a host of enzymatic reactions in various settings addressing structure–function relationships, as well as mechanisms and kinetics of molecular operation of enzymes. The most common way to quantify nitrite, for instance in nitric oxide synthase (NOS) mechanistic investigations, is the spectrophotometric assay based on the Griess reaction through external standard calibration. This assay is based on a two-step diazotization reaction, in which a cationic diazonium derivative of sulfanilamide is formed as intermediate before the final absorbing azo-product. We show that this intermediate is very sensitive to reducing agents that may be transferred from the reaction media under investigation. The interaction of this vital intermediate with the reducing agent, dithiothreitol (DTT), which is widely used in NOS reactions, is characterized by both electrochemical and spectroscopic means. The effect of DTT on the performance of external calibration, both in sample recovery studies and in actual NOS reactions, is presented. Finally an alternative method of standard additions, which partially compensates for the accuracy and sensitivity problems of external calibration, is proposed and discussed

    Cholesterol Levels and Activity of Membrane Bound Proteins: Characterization by Thermal and Electrochemical Methods

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    The long-term goal of this investigation is to study the effects of increased cholesterol levels on the molecular activity of membrane-bound enzymes such as nitric oxide synthase, that are critical in the functioning of the cardiovascular system. In this particular investigation, we used differential scanning calorimetry (DSC) and dielectric thermal analysis (DETA) to study the effect of added cholesterol on melting/recrystallization and dielectric behavior, respectively, of phosphatidylcholine (PC) bilayered thin films. We also used electrochemical methods to investigate the effect of added cholesterol on the redox behavior of the oxygenase domain of nitric oxide synthase as a probe embedded in the PC films. The results show that added cholesterol in the PC films seems to depress the molecular dynamics as indicated by lowered current responses in the presence of cholesterol as well as a slight increase of the transition temperature in the overall two-phase regime behavior observed in PC–cholesterol films. These results are rationalized in the context of the general DSC and DETA behaviors of the PC–chol films

    Comunità cristiane nell’islam arabo. La sfida del futuro

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    Preesistenti all'islamizzazione del Medio Oriente, le comunità cristiane costituiscono tuttora un importante elemento di pluralismo, sebbene oggi a rischio di sopravvivenza, nelle società arabe a maggioranza musulmana. Il volume presenta il ruolo storico delle comunità cristiane orientali nelle rispettive società arabe, la loro funzione di intermediazione culturale tra Oriente e Occidente e la discriminazione giuridica e sociale subìta con l'avvento dell'islam.- Indice #4- Introduzione, Andrea Pacini #10- Gli arabi cristiani: dalla questione d’Oriente alla recente geopolitica delle minoranze, Joseph Maïla #38- I cristiani arabi dell’Oriente: una prospettiva demografica, Philippe Fargues #64- Le comunità cristiane, soggetti attivi della società araba nel corso della storia, Samir Khalil Samir #84- Le chiese del Medio Oriente: origini e identità, tra radicamento nel passato e apertura al presente, Jean Corbon #110- Il diritto dello stato/nazione e lo status dei non musulmani in Egitto e in Siria, Bernard Botiveau #130- L’emigrazione degli arabi cristiani: dimensioni e cause dell’esodo, Bernard Sabella #148- La produzione culturale dei cristiani arabi oggi: espressione di identità nella società a maggioranza musulmana, Camille Hechaïmé #178- Le dinamiche politiche dei copti: rendere la comunità un protagonista atti, Dina El Khawaga #196- La posizione e il ruolo attuale dei copti nell’economia egiziana: tradizioni e specializzazioni, Adel A. Beshai #216- Le dinamiche dei cristiani libanesi: tra il paradigma delle ‘āmmiyyāt e il paradigma Hwayyek, Elizabeth Picard #226- Le comunità cristiane e la situazione economica e sociale in Libano, Boutros Labaki #250- Dinamiche comunitarie e sociopolitiche dei cristiani arabi in Giordania, in Israele e nei territori palestinesi autonomi, Andrea Pacini #290- I cristiani di Siria, Habib Moussalli #320- I cristiani in Iraq, Yūsuf Habbi #330- Il contributo delle comunità arabo-cristiane al futuro delle società arabe del Medio Oriente: alcune prospettive, Maurice Borrmans #342- I riti delle chiese orientali #356- Glossario #376- Riferimenti bibliografici #40

    Crystal Structure of Diedel, a Marker of the Immune Response of Drosophila melanogaster

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    Background: The Drosophila melanogaster gene CG11501 is up regulated after a septic injury and was proposed to act as a negative regulator of the JAK/STAT signaling pathway. Diedel, the CG11501 gene product, is a small protein of 115 residues with 10 cysteines. Methodology/Principal Findings: We have produced Diedel in Drosophila S2 cells as an extra cellular protein thanks to its own signal peptide and solved its crystal structure at 1.15 A ˚ resolution by SIRAS using an iodo derivative. Diedel is composed of two sub domains SD1 and SD2. SD1 is made of an antiparallel b-sheet covered by an a-helix and displays a ferredoxin-like fold. SD2 reveals a new protein fold made of loops connected by four disulfide bridges. Further structural analysis identified conserved hydrophobic residues on the surface of Diedel that may constitute a potential binding site. The existence of two conformations, cis and trans, for the proline 52 may be of interest as prolyl peptidyl isomerisation has been shown to play a role in several physiological mechanisms. The genome of D. melanogaster contains two other genes coding for proteins homologous to Diedel, namely CG43228 and CG34329. Strikingly, apart from Drosophila and the pea aphid Acyrthosiphon pisum, Diedel-related sequences were exclusively identified in a few insect DNA viruses of the Baculoviridae and Ascoviridae families. Conclusion/Significance: Diedel, a marker of the Drosophila antimicrobial/antiviral response, is a member of a small famil

    Nephrolithiasis related to inborn metabolic diseases

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    Nephrolithiasis associated with inborn metabolic diseases is a very rare condition with some common characteristics: early onset of symptoms, family history, associated tubular impairment, bilateral, multiple and recurrent stones, and association with nephrocalcinosis. The prognosis of such diseases may lead to life threatening conditions, not only because of unabated kidney damage but also because of progressive extra-renal involvement, either in a systemic form (e.g. primary hyperoxaluria type 1, requiring combined liver and kidney transplantation), or in a neurological form (Lesch–Nyhan syndrome leading to auto-mutilation and disability, phosphoribosyl pyrophosphate synthetase superactivity, which is associated with mental retardation). Patients with other inborn metabolic diseases present only with recurrent stone formation, such as cystinuria, adenine phosphoribosyl-transferase deficiency, xanthine deficiency. Finally, nephrolithiasis may be secondarily part of some other metabolic diseases, such as glycogen storage disease type 1 or inborn errors of metabolism leading to Fanconi syndrome (nephropathic cystinosis, tyrosinaemia type 1, fructose intolerance, Wilson disease, respiratory chain disorders, etc.). The diagnosis is based on highly specific investigations, including crystal identification, biochemical analyses and DNA study. The treatment of nephrolithiasis requires hydration as well as specific measures. Compliance is a major issue regarding the progression of renal damage, but the overall outcome mainly depends on extra-renal involvement in relation to the metabolic defect

    Pan-cancer analysis of whole genomes identifies driver rearrangements promoted by LINE-1 retrotransposition

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    About half of all cancers have somatic integrations of retrotransposons. Here, to characterize their role in oncogenesis, we analyzed the patterns and mechanisms of somatic retrotransposition in 2,954 cancer genomes from 38 histological cancer subtypes within the framework of the Pan-Cancer Analysis of Whole Genomes (PCAWG) project. We identified 19,166 somatically acquired retrotransposition events, which affected 35% of samples and spanned a range of event types. Long interspersed nuclear element (LINE-1; L1 hereafter) insertions emerged as the first most frequent type of somatic structural variation in esophageal adenocarcinoma, and the second most frequent in head-and-neck and colorectal cancers. Aberrant L1 integrations can delete megabase-scale regions of a chromosome, which sometimes leads to the removal of tumor-suppressor genes, and can induce complex translocations and large-scale duplications. Somatic retrotranspositions can also initiate breakage–fusion–bridge cycles, leading to high-level amplification of oncogenes. These observations illuminate a relevant role of L1 retrotransposition in remodeling the cancer genome, with potential implications for the development of human tumors

    Use of anticoagulants and antiplatelet agents in stable outpatients with coronary artery disease and atrial fibrillation. International CLARIFY registry

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    Retrospective evaluation of whole exome and genome mutation calls in 746 cancer samples