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  • 1
    Electronic Resource
    Electronic Resource
    Controlled spontaneous emission of a tri(8-hydroxyquinoline) aluminum layer in a microcavity (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 3032-3037 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the fabrication of all-dielectric microcavities with a tri(8-hydroxyquinoline) aluminum (Alq3) organic layer as the emitting layer. In a first step, we characterized the materials used in the structures by ellipsometry, and ensured nondegradation of the organic material in the fabrication process. Then, by angular-resolved photoluminescence, we investigated changes in the angular emission pattern caused by the cavities and observed a sharply directed emission. We also investigated the influence of the position of the radiative layer in the cavity on normal spontaneous emission. We observed enhancements in spontaneous emission over 20 times higher than that of a single Alq3 layer. These are the highest reported for organic material based microcavities. They are mainly explained by the very small thickness of the Alq3 layer (20 nm≡0.06λ, λ being the resonant wavelength), by high-quality low-loss dielectric mirrors as well as by the narrow collecting angle of our experiment (±3°). This study corroborates analogous works and demonstrates the possibility of controlling the spontaneous emission of an emitter by a microcavity. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.369639
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  • 2
    Electronic Resource
    Electronic Resource
    Low temperature deposition of nanocrystalline silicon carbide thin films (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 2373-2375 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Silicon carbide thin films have been deposited by reactive magnetron sputtering in a pure hydrogen plasma at substrate temperatures, Ts, ranging between 100 and 600 °C. The infrared (IR) absorption spectra and the transmission electron microscopy observations reveal an onset of crystallization at Ts as low as 300 °C. The crystalline fraction increases with Ts and reaches a value of about 60% for Ts=600 °C. Both refractive index n and room temperature dark conductivity σd(RT) show quite consistent behaviors with the structural evolution of the layers. Thus n increases from 1.9 to 2.4 and σd(RT) improves by six orders of magnitude when Ts is raised from 100 to 600 °C. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.126350
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  • 3
    Electronic Resource
    Electronic Resource
    Positive co-regulation of the Escherichia coli carnitine pathway cai and fix operons by CRP and the CaiF activator (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 34 (1999), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Activation of the two divergent Escherichia coli cai and fix operons involved in anaerobic carnitine metabolism is co-dependent on the cyclic AMP receptor protein (CRP) and on CaiF, the specific carnitine-sensitive transcriptional regulator. CaiF was overproduced using a phage T7 system, purified on a heparin column and ran as a 15 kDa protein on SDS–PAGE. DNase I footprinting and interference experiments identified two sites, F1 and F2, with apparently comparable affinities for the binding of CaiF in the cai–fix regulatory region. These sites share a common perfect inverted repeat comprising two 11 bp half-sites separated by 13 bp, and centred at −70 and −127 from the fix transcription start site. They were found to overlap the two low-affinity binding sites, CRP2 and CRP3, determined previously for CRP. Gel shift assays and footprinting experiments suggest that CaiF and CRP bind co-operatively to the F1/CRP2 and F2/CRP3 sites of the intergenic cai–fix region. Moreover, they appeared to serve the simultaneous binding of each other, giving rise to an original multiprotein CRP–CaiF complex enabling RNA polymerase recruitment and local DNA untwisting, at least at the fix promoter. Using random mutagenesis, two CaiF mutants impaired in transcription activation were isolated. The N-terminal A27V mutation affected the structural organization of the activator, whereas the central I62N mutation was suggested to interfere with DNA binding.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01622.x
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  • 4
    Electronic Resource
    Electronic Resource
    Dynamics and processivity of 40S ribosome scanning on mRNA in yeast (2004)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 51 (2004), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The eukaryotic 40S ribosomal subunit locates the translation initiation codon on an mRNA via the so-called scanning process that follows 40S binding to the capped 5′ end. This key step in translation is required for the expression of almost all eukaryotic genes, yet the mechanism and dynamics of scanning are unknown. We have performed quantitative studies in vivo and in vitro of the movement of yeast 40S ribosomes along 5′ untranslated regions (UTRs) of different lengths. 40S subunits perform cap-dependent scanning with high processivity for more than 1700 nucleotides in cells of Saccharomyces cerevisiae. Moreover, the observed rates of expression indicate that scanning is performed by an untethered 40S subunit that has been released from the 5′ cap complex. Unexpectedly, the capability to maintain scanning competence on a long 5′ UTR is more dependent on the Ded1/Dbp1 type of helicase than on eIF4A or eIF4B. In a yeast cell-free extract, scanning shows reduced processivity, with an estimated net 5′→3′ rate of approximately 10 nucleotides per second at 26°C. We have developed a biased bidirectional walking model of ribosomal scanning that provides a framework for understanding the above observations as well as other known quantitative and qualitative features of this process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2003.03898.x
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  • 5
    Electronic Resource
    Electronic Resource
    Tetracycline-aptamer-mediated translational regulation in yeast (2003)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 49 (2003), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: We describe post-transcriptional gene regulation in yeast based on direct RNA–ligand interaction. Tetracycline-dependent translational regulation could be imposed via specific aptamers inserted at two different positions in the 5′ untranslated region (5′UTR). Translation in vivo was suppressed up to ninefold upon addition of tetracycline. Repression via an aptamer located near the start codon (cap-distal) in the 5′UTR was more effective than repression via a cap-proximal position. On the other hand, suppression in a cell-free system reached maximally 50-fold and was most effective via a cap-proximal aptamer. Examination of the kinetics of tetracycline-dependent translational inhibition in vitro revealed that preincubation of tetracycline and mRNA before starting translation led not only to the fastest onset of inhibition but also the most effective repression. The differences between the behaviour of the regulatory system in vivo and in vitro are likely to be related to distinct properties of mRNP structure and mRNA accessibility in intact cells as opposed to cell-extracts. Tetracycline-dependent regulation was also observed after insertion of an uORF sequence upstream of the aptamer, indicating that our system also targets reinitiating ribosomes. Polysomal gradient analyses provided insight into the mechanism of regulation. Cap-proximal insertion inhibits binding of the 43S complex to the cap structure whereas start-codon-proximal aptamers interfere with formation of the 80S ribosome, probably by blocking the scanning preinitiation complex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2003.03656.x
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  • 6
    Electronic Resource
    Electronic Resource
    Characterization of the roles of NikR, a nickel-responsive pleiotropic autoregulator of Helicobacter pylori (2003)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 49 (2003), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The Helicobacter pylori genome contains a gene (hp1338 or nikR) that encodes a nickel-dependent regulator that is homologous to the Escherichia coli nickel-responsive regulator, NikR. The H. pylori nikR product acts as a pleiotropic metal-dependent regulator. We constructed a non-polar isogenic mutant deleted for the nikR gene. NikR was essential for the survival of H. pylori in the presence of high nickel and cobalt ion concentrations in vitro. We screened a DNA macroarray for genes that were differentially expressed in parental and nikR-deficient H. pylori strains grown in the presence of excess nickel. We found that H. pylori NikR mediates the expression of nickel-activated and -repressed genes. In the presence of excess nickel, NikR activated the transcription of ureA-ureB (hp72–73), nixA (hp1077 ), copA2 (hp1072), hpn (hp1427 ) and hpn-like (hp1432) genes and repressed the expression of genes encoding proteins involved in ferric iron uptake and storage [pfr (hp0653), fur (hp1027 ), frpB4 (hp1512), exbB/exbD (hp1339–1340), ceuE (hp1561)], motility [cheV (hp616), flaA (hp0601), flaB (hp0115 )], stress responses [hrcA-grpE-dnaK (hp111–110–109)] and encoding outer-membrane proteins [omp11(hp0472), omp31 (hp1469), omp32 (hp1501)]. Slot blot DNA/RNA hybridization experiments using RNA from three independent bacterial cultures confirmed the transcriptome data for 10 selected genes. The results of gel shift experiments using purified native NikR, β-galactosidase assays with the region between nikR and the exbB/exbD divergent operon, and the study of exbB gene expression using a gentamicin/apramycin reporter gene in H. pylori indicated that NikR is an autorepressor that binds to this intergenic region and also controls the expression of the exbB/exbD/tonB operon, which provides energy for ferric iron uptake. Thus, as previously suggested for Fur in H. pylori, NikR appears to be a global regulator of the metabolism of some divalent cations within a highly complex regulated network.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2003.03621.x
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  • 7
    Electronic Resource
    Electronic Resource
    A nuclear protein in Schizosaccharomyces pombe with homology to the human tumour suppressor Fhit has decapping activity (2002)
    Oxford, UK : Blackwell Science, Ltd
    Molecular microbiology 46 (2002), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: A number of eukaryotic proteins are already known to orchestrate key steps of mRNA metabolism and translation via interactions with the 5′ m7GpppN cap. We have characterized a new type of histidine triad (HIT) motif protein (Nhm1) that co-purifies with the cap-binding complex eIF4F of Schizosaccharomyces pombe. Nhm1 is an RNA-binding protein that binds to m7GTP-Sepharose, albeit with lower specificity and affinity for methylated GTP than is typical for the cap-binding protein known as eukaryotic initiation factor 4E. Sequence searches have revealed that proteins with strong sequence similarity over all regions of the new protein exist in a wide range of eukaryotes, yet none has been characterized up to now. However, other proteins that share specific motifs with Nhm1 include the human Fhit tumour suppressor protein and the diadenosine 5′, 5′′′-P1, P4-tetraphosphate asymmetrical hydrolase of S. pombe. Our experimental work also reveals that Nhm1 inhibits translation in a cell-free extract prepared from S. pombe, and that it is therefore a putative translational modulator. On the other hand, purified Nhm1 manifests mRNA decapping activity, yet is physically distinct from the Saccharomyces cerevisiae decapping enzyme Dcp1. Moreover, fluorescence and immunofluorescence microscopy show that Nhm1 is predominantly, although not exclusively, nuclear. We conclude that Nhm1 has evolved as a special branch of the HIT motif superfamily that has the potential to influence both the metabolism and the translation of mRNA, and that its presence in S. pombe suggests the utilization of a novel decapping pathway.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2002.03151.x
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  • 8
    Electronic Resource
    Electronic Resource
    EFFECT OF MAGNESIUM ON MECHANICAL PROPERTIES OF PRESSURIZED MESENTERIC SMALL ARTERIES FROM OLD AND ADULT RATS (2004)
    Oxford, UK : Blackwell Science Pty
    Clinical and experimental pharmacology and physiology 31 (2004), S. 0 
    Details
    ISSN: 1440-1681
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: 1. The purpose of the present study was to determine the effects of magnesium (Mg) on the mechanical properties of resistance arteries in adult and old rats.2. Studies were performed in adult (17 weeks) and old (104 weeks) male Wistar rats. The vasodilatory response and the passive mechanical properties of the wall of isolated perfused and pressurized arterial segments of mesenteric small arteries were investigated after Mg and verapamil application, both known for their calcium antagonistic properties.3. Mesenteric resistance arteries from old rats exhibited an outward hypertrophic remodelling, with enlargment of the lumen, thickening of the media and enlarged media cross-sectional area.4. The vasodilatory response induced by the application of increasing extracellular concentrations of Mg and verapamil was significantly smaller in preconstricted mesenteric arteries of old rats than in those of adult rats.5. Incremental distensibility in response to increasing intravascular pressures did not change. However, the stress–strain curve was shifted to the left in pressurized mesenteric arteries from old rats, indicating arterial wall stiffness. Verapamil (3 µmol/L) did not modify the stress–strain curves in either adult or aged rats. However, Mg (4.8 mmol/L) significantly shifted the curve to the right in mesenteric arteries from adult rats and, to a greater degree, in those from old rats.6. Although Mg-induced vasodilatation is impaired in aged rats, increased Mg concentration improved the mechanics of pressurized mesenteric resistance arteries. The fact that Mg decreases arterial stiffness in arteries from old rats suggests that Mg has a beneficial effect on age-related changes to the vascular wall.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1440-1681.2004.03992.x
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  • 9
    Electronic Resource
    Electronic Resource
    Echocardiographic Assessment of the Interventricular Delay of Activation and Correlation to the QRS Width in Dilated Cardiomyopathy (2001)
    Oxford, UK : Blackwell Futura Publishing, Inc.
    Pacing and clinical electrophysiology 24 (2001), S. 0 
    Details
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: ROULEAU, F., et al.: Echocardiographic Assessment of the Interventricular Delay of Activation and Correlation to the QRS Width in Dilated Cardiomyopathy. The aim of the study was to define criteria for left ventricular pacing in dilated cardiomyopathy (DCM) using an echocardiographic evaluation of interventricular electromechanical delay (IMD) and a correlation of IMD to QRS duration. Standard 12-lead ECG and echocardiography with pulsed Doppler tissue imaging (DTI) were recorded in 35 DCM patients (mean age 58 ± 11 years) with QRS duration from narrow (80 ms) to broad (222 ms) patterns. The time for left ventricular activation was evaluated from the onset of QRS to the onset of aortic flow (Q-Ao) by standard pulsed Doppler (SP) or to the onset of mitral annulus systolic wave (Q-Mit) (DTI). The time for right ventricular activation was determined from the onset of QRS to the onset of pulmonary flow (Q-Pulm) (SP) or to the onset of tricuspid annulus systolic wave (Q-Tri) (DTI). (Q-Ao)–(Q-Pulm) and (Q-Mit)–(Q-Tri) determined IMD for each method, respectively. QRS width and IMD showed correlation coefficients of r = 0.86 ([Q-Ao]-[Q-Pulm]) and r = 0.82 ([Q-Mit]-[Q-Tri]) (P ≤ 0.001). Mean IMD of 77 ± 15 ms (SP) and 88 ± 26 ms (DTI) were noted for QRS width above 150 ms. Left ventricle delayed activation was positively correlated to QRS widening with both methods, (r = 0.90, [Q-Ao]), (r = 0.83, [Q-Mit]) (P ≤ 0.001). In conclusion, QRS duration is a good marker of an interventricular mechanical asynchrony. According to IMD correction, left ventricular pacing may be mainly proposed to symptomatic DCM patients with QRS duration 〉 150 ms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-9592.2001.01500.x
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  • 10
    Electronic Resource
    Electronic Resource
    Coelioscopic cholecystectomy: Experience with 2006 cases (1995)
    Springer
    World journal of surgery 19 (1995), S. 748-752 
    Details
    ISSN: 1432-2323
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Cette étude rétrospective porte sur 2006 cholécystectomies laparoscopiques (CL) réalisées par trois chirurgiens «seniors» entre Avril 1988 et Décembre 1992, en utilisant la technique dite «Française» et une cholangiographique peropératoire (CPO) sélective. Trois cent dix huit patients (15.8%) étaient obèses, 75 (3.7%) avaient une insuffisance respiratoire, 251 (12.6%) une inflammation, et 83 (4.1%), une lithiase de la voie biliaire principale (VBP). Ces trois dernières conditions ne sont plus des contre-indications de la CL. Une conversion a été nécessaire chez 43 patients (2.14%). Le taux de complications a été de 2%, 25 (1.25%) non biliaires et 15 (0.7%) biliaires alors qu'il y a eu un décès. La CPO ne prévient pas les complications biliaires puisqu'aucune complication dans cette série n'a été reconnue ou évitées par la CPO. Dans notre expérience, la CPO n'est indiquée que pour localiser des calculs chez le patient présentant des facteurs de risque de lithiase. Le traitement de lithiase de la VBP sous laparoscopie reste controversé.
    Abstract: Resumen Este es un estudio retrospectivo de 2.006 colecistectomías laparoscópicas (CL) con colangiografía intraoperatoria selectiva (CIS) practicadas entre abril de 1988 y diciembre de 1992 por los mismos tres cirujanos senior, utilizando la técnica francesa. Se registró obesidad en 318 pacientes (15.8%), insuficiencia respiratoria en 75 (3.7%), inflamación en 251 (12.6%), y coledocolitiasis en 83 (4.1%). En la actualidad tales alteraciones representan buena indicación para CL. La conversión a laparotomía fue necesaria en 43 casos (2.14%). La tasa de complicaciones fue 2%, de las cuales 25 (1.25%) fueron complicaciones no biliares y 15 (0.7%) estuvieron fueron relacionadas con la vía biliar; se registró una muerte. La CIS no resulta eficaz en cuanto a prevenir complicaciones biliares, puesto que no habría reconocido o evitado a aquellas observadas en esta experiencia. La CIS se practica en forma selectiva solamente con el propósito de identificar cálculos no sospechados en aquellos pacientes de alto riesgo de coledocolitiasis. El tratamiento laparoscópico de la coledocolitiasis continúa siendo motivo de controversia.
    Notes: Abstract 2006 laparoscopic cholecystectomies (LC) were performed from April 1988 to December 1992 by three senior surgeons using the French technique and selective intraoperative cholangiography (IOC). Obesity was present in 318 patients (15.8%), respiratory insufficiency in 75 (3.7%), inflammation in 251 (12.5%), and common bile duct (CBD) stones in 83 (4.1%). The presence of these additional ailments is a good indication for L.C. Conversion to laparotomy occurred in 43 cases (2.1%). The rate of complications was 2%; 25 (1.25%) were nonbiliary complications and 15 (0.7%) were biliary-related; there was one death. IOC is not effective in preventing biliary complications, as those observed in this study would not have been recognized or avoided by it. IOC is carried out only selectively to locate unsuspected stones in patients with risk factors of CBD lithiasis. Laparoscopic treatment of CBD stones is still controversial.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00295921
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