177,690 research outputs found
Localization of cyanine dye binding to brush-border membranes by quenching of n-(9-anthroyloxy) fatty acid probes
No full textThe location and orientation of 3,3′-dipropylthiodicarbocyanine (diS-C3-(5)) binding sites in renal brush-border membrane vesicles was examined from the quenching of n-(9-anthroyloxy) fatty acid (n-AS) fluorescence. Based on previous kinetic studies (Cabrini, G. and Verkman, A.S. (1986) J. Membrane Biol. 90, 163-175) monomeric aqueous diS-C3-(5) binds to brush-border membrane vesicles (BBMV) by an initial 6 ms association to form bound monomer, a 30-40 ms equilibrium between bound monomer (M) and bound dimer (D), and a 1-1.3 s translocation of D from the outer to inner membrane leaflet. Based on Stern-Volmer and lifetime analyses, M and D quench the fluorescence of the n-AS probes by a collisional mechanism. At low [diS-C3-(5)]/[BBMV] (R), where M predominates, the n-AS quenching efficiencies (Q) are similar (n = 2-16); at high R, where D predominates, Q increases with n (16 > 12 ⋙ 6 > 2), suggesting that M is oriented parallel, and D perpendicular, to the phospholipid chains deep within the membrane. Mixture of diS-C3-(5) with brush-border membrane vesicles containing n-AS in a stopped-flow apparatus gave a biexponential fluorescence decrease (excitation 390 nm, emission above 450 nm) with time constants 30-40 ms and 1-1.5 s; there was no 6 ms quenching process. These findings are incorporated into a model in which diS-C3-(5) adheres loosely to the outer membrane surface in 6 ms, binds parallel to the membrane phospholipid in 30-40 ms, dimerizes and rotates by 90° in much less than 30 ms, and translocates to the opposite half of the bilayer in 1-1.5 s. © 1986
Nonsense mutation R1162X of the cystic fibrosis transmembrane conductance regulator gene does not reduce messenger RNA expression in nasal epithelial tissue.
No full textCystic fibrosis (CF) patients bearing the premature translation termination mutation (nonsense mutation) W1282X present severe pulmonary and pancreatic disease, whereas patients carrying other nonsense mutations such as G542X, R553X, S1255X, R1162X, and W1316X show a severe pancreatic but mild pulmonary illness. CF gene expression was found absent in respiratory tissues with mutations R553X and W1316X, which led to the hypothesis that the absence of the gene product in the lung is more favorable than the presence of an altered one. We asked whether or not all the nonsense mutations characterized by mild pulmonary disease phenotypes do present the absence of CF gene expression. We therefore investigated gene expression at the mRNA level in respiratory cells obtained from nasal polyps from a patient homozygous for the R1162X mutation. Gene expression was studied by amplification with polymerase chain reaction of segments of the CF transmembrane conductance regulator cDNA that was obtained by reverse transcription of RNA. Semiquantitative analysis was performed by Northern analysis. By comparing the data obtained from polyps deriving from non-CF subjects and a CF patient homozygous for dF508 mutation, it is shown that no reduction of CF gene expression is evident in R1162X respiratory tissue. We conclude that CF nonsense mutations have heterogeneous mechanisms of gene expression
Les îles sans abord : roman / Gabrielle Cabrini
No full textContient une table des matièresAvec mode text
Mechanism of interaction of the cyanine dye DiS-C3-(5) with renal brush-border vesicles
No full textThe equilibrium binding mechanism and kinetics of binding of diS-C3-(5) (3,3′-dipropylthiodicarbocyanine iodide) to rabbit renal brush-border membrane vesicles (BBMV) were examined using steady-state and time-resolved fluorescence, and fluorescence stopped-flow methods. In aqueous solution, diS-C3-(5) exists as a monomer at concentrations <5 μm with fluorescence emission peak at 670 nm (excitation 622 nm), anisotropy r=0.102, and lifetime τ=1.2 nsec (23°C). Upon addition of increasing BBMV (voltage clamped to 0 mV using K+/valinomycin), the 670 nm emission peak decreases, corresponding to formation of a nonfluorescent membrane dimer, and subsequently a new emission peak at 695 nm increases, corresponding to membrane monomer. Dynamic depolarization studies show that aqueous diS-C3-(5) rotation is unhindered with a rotational rate R=0.57 nsec-1 while membrane monomer is hindered with steady-state anisotropy r=0.190, lifetime τ=2.1 nsec, R=0.58 nsec-1 and limiting anisotropy r∝=0.11. Based on equilibrium fluorescence titrations, the membrane monomer-dimer (M-D) dissociation constant, Kd=[M]2/[D][BBMV], is 0.0013, where BBMV is expressed as membrane phospholipid concentration. Three distinct kinetic processes are identified by stopped-flow experiments in which BBMV are mixed with diS-C3-(5). There is rapid binding of diS-C3-(5) to the membrane to form bound monomer with a 6-msec exponential time constant. The membrane monomer at the membrane outer surface then aggregates to form bound dimer at the outer surface with a concentration independent time constant of 30 msec. The overall dimerization reaction probably consists of a rate-limiting reorientation process (30 msec) followed by a rapid dimerization which occurs on a nanosecond time scale. Finally, there is a 0.8 to 1 sec translocation of membrane dimer between symmetric sites at the inner and outer membrane surfaces. The translocation reaction is the step which is probably sensitive to changes in transmembrane electrical potential. © 1986 Springer-Verlag New York Inc
Leon Battista Alberti umanista e scrittore. Filologia, esegesi, tradizione, a cura di R. Cardini e M. Regoliosi, Firenze, Polistampa, 2007
No full textPresentazione e analisi critica dei risultati degli studi albertiani pubblicati negli Atti del Convegno di Arezzo del giugno 2004
TRIMETHYLANGELICIN AS CFTR CORRECTOR IN BRONCHIAL EPITHELIAL CELLS.
No full textThe present invention relates to the use of an angular psoralen, trimethylangelicin (4,6,4 '-trime thy langelicin - TMA), a molecule able to correct the intracellular localisation of the membrane protein called CFTR (Cystic Fibrosis Transmembrane conductance Regulator) carrying the F508del CFTR mutation, which is altered in a sub-group of patients suffering from cystic fibrosis. Said molecule is proposed for the preparation of a medicament for the treatment of cystic fibrosis (CF) in the sub-group of patients characterised by the F508del mutation of the CFTR gene
On-Line Calibration of Offset and Gain Mismatch in Time-Interleaved ADC Using a Sampled-Data Chaotic Bit-Stream
No full textThe offset and gain error of ADCs represent two important limits for time-interleaved ADC architectures. The proposed method enables a precise measurement of the offset and the gain during system operation introducing a minimum disturb at the output. The method exploits the modulation of the input signal with a random sequence of +1 and -1. The random bit-stream is generated by using the wide-band output of a time-discrete non-linear circuit. The resulting spread spectrum signal can be easily distinguished by the DC offset and the use of a digital accumulator extracts the offset and the gain of each ADC. The input signal is finally reconstructed, in the digital domain, with a synchronous demodulation. The accumulation time can be as many clock periods (like 106) thus permitting an excellent accuracy in the offset and gain measurement. Simulations of the proposed approach at the behavioral level confirm the effectiveness of the method. It is shown that the offset of a 12-bit ADC can be measured with a 0.1 LSB accuracy
Detection of cystic fibrosis mutations by reverse dot-blot hybridization
No full textBackground. More than 800 mutations of the cystic fibrosis gene have been discovered until now. The frequency of these mutations varies widely among cystic fibrosis chromosome of patients from different geographical areas. Both the large number and the heterogeneity of distribution of these mutations require tailoring of specific diagnostic assays. Methods. A diagnostic assay has been designed to allow the simultaneous detection of the 15 most frequent mutations in North-eastern Italy by applying the reverse dot-blot (RDB) hybridization technique after co-amplification in a single tube of 11 PCR products. The RDB assay has been rendered suitable for the analysis of purified DNA and dried blood spots punched from filter paper (Guthrie cards). Results. The RDB assay applied to routine diagnostic testing in 403 cystic fibrosis patients allowed the detection of mutations in 82% of the chromosomes. In a sample of the general population, the assay identified 15 healthy carriers over 443 subjects (1/29.5). Finally, 24 cystic fibrosis patients and 33 healthy carriers were found among 459 newborn babies who have been screened because of elevated blood immunoreactive trypsinogen concentration. Conclusions: The RDB assay proposed for cystic fibrosis mutation detection in our area offers advantages in respect to both detection rate and costs in comparison to the commercially available diagnostic kits. The application of the RDB technique reported here for cystic fibrosis gene suggests the advantages of this relatively inexpensive technology when flexibility and rapid application of research findings to diagnostic protocols is crucial
Modelos experimentales de ortodoncia en la rata
No full textSe presentan los diferentes dispositivos diseñados en nuestro laboratorio para inducir movimientos ortodóncicos experimentales en la rata. Se detallan los principios básicos de su confección y las metodologías de evaluación macroscópica, histológica y radiológica que proporcionan datos cuantitativos.\nSe hace un breve comentario sobre los hallazgos más salientes obtenidos en nuestro laboratorio por la utilización de estos modelos experimentales.\nFil: Cabrini, R. L. Universidad de Buenos Aires. Facultad de Odontología. Cátedra de Anatomía Patológica. Buenos Aires, Argentina.Fil: Ubios, A. M. Universidad de Buenos Aires. Facultad de Odontología. Cátedra de Histología y Embriología. Buenos Aires, Argentina
Die wirkung von totalbestrahlung auf durch orthodontische bewegungen bedingte knochenresorption
No full textFil: Ubios, A. M. Universidad Nacional de Córdoba. Facultad de Odontología. Cátedra de Anatomía Patológica; Argentina.Fil: Parodi, R. J. Universidad Nacional de Córdoba. Facultad de Odontología; Argentina.Fil: Cabrini, R. L. Comisión Nacional de Energía Atómica. Departamento de Radiología; Argentina.Fil: López Otero, R. Universidad de Buenos Aires. Facultad de Odontología. Cátedra de Anatomía Patológica; Argentina.En este tipo de diseño la irradiación actúa como un factor sistémico que modifica la respuesta local por un complejo mecanismo con múltiples alteraciones generales. La irritación gingival demostró que el mecanismo de reabsorción ósea frente a estas respuestas, no estaba determinado y aun podría ser mayor que lo habitual. El objetivo de este trabajo es completar el estudio del comportamiento que crean o perturban reabsorciones frente a un sistema de irradiación similar pero con factores locales del tipo observable en los movimientos ortodóncicos.info:eu-repo/semantics/publishedVersionFil: Ubios, A. M. Universidad Nacional de Córdoba. Facultad de Odontología. Cátedra de Anatomía Patológica; Argentina.Fil: Parodi, R. J. Universidad Nacional de Córdoba. Facultad de Odontología; Argentina.Fil: Cabrini, R. L. Comisión Nacional de Energía Atómica. Departamento de Radiología; Argentina.Fil: López Otero, R. Universidad de Buenos Aires. Facultad de Odontología. Cátedra de Anatomía Patológica; Argentina
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