169,763 research outputs found
A single polymerase (L) mutation in avian metapneumovirus increased virulence and partially maintained virus viability at an elevated temperature
No full textPreviously a virulent avian metapneumovirus (AMPV) farm isolate Italy 309/04 was shown to have derived from a live vaccine. Virulence due to the five nucleotide mutations associated with the reversion to virulence, was investigated by their addition to the vaccine using reverse genetics. Virulence of these recombinant viruses was determined by infection of one-day-old turkeys. Disease levels resulting from the combined two matrix (M) mutations was indistinguishable from that produced by the recombinant vaccine, whereas the combined three L gene mutations increased disease to a level (p<0.0001) which was indistinguishable from that caused by the revertant Italy 309/04 virus. Testing of the L mutations individually showed that two did not increase virulence while the third, corresponding to an asparagine to aspartic acid substitution, produced virulence indistinguishable from that caused by Italy 309/04. In contrast to the vaccine, the virulent mutant also showed increased viability at temperatures typical of turkey core tissues. The notion that increased viral virulence resulted from enhanced ability to replicate in tissues away from the cool respiratory tract, cannot be discounted
Avian Metapneumoviruses in Italy: Evidence of attachment protein evolution coincident with mass live vaccine introduction
No full textAvian metapneumoviruses (AMPV) of subtype B dominate over other subtypes on
Italian poultry farms in northern Italy. AMPVs from the Veneto region of Italy between
1987 and 2007 were sequenced in their attachment (G) and fusion (F) protein genes,
together with other subtype B AMPVs from other parts of Western Europe, collected
prior to 1994. All viruses in the survey had very similar predicted F sequences
whereas the predicted G protein sequences found in Italy from 2001 were distinctly
different from those found in pre 1994 viruses. Nonetheless pre 1994 Italian AMPVs
were more similar to post 2000 AMPVs than other pre 1994 viruses from other parts
of Europe, thereby showing that the later viruses had probably evolved from early
Italian viruses. The occurrence of the later variants followed introduction of the mass
administration with a single subtype B vaccine and its G protein sequence placed it
clearly in the pre 1994 cluster. The possibility of the vaccine having driven field virus
evolution in order to evade immune pressure cannot be excluded
Avian metapneumovirus (AMPV) attachment protein involvement in probable virus evolution concurrent with mass live vaccine introduction
No full textAvian metapneumoviruses detected in Northern Italy between 1987 and 2007 were sequenced in their fusion (F) and attachment (G) genes together with the same genes from isolates collected throughout western European prior to 1994. Fusion protein genes sequences were highly conserved while G protein sequences showed much greater heterogeneity. Phylogenetic studies based on both genes clearly showed that later Italian viruses were significantly different to all earlier virus detections, including early detections from Italy. Furthermore a serine residue in the G proteins and lysine residue in the fusion protein were exclusive to Italian viruses, indicating that later viruses probably arose within the country and the notion that these later viruses evolved from earlier Italian progenitors cannot be discounted. Biocomputing analysis applied to F and G proteins of later Italian viruses predicted that only G contained altered T cell epitopes. It appears likely that Italian field viruses evolved in response to selection pressure from vaccine induced immunity
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Mitomycin C in highly myopic eyes - Author reply
No full textOphthalmology. 2005 Feb;112(2):208-18; discussion 219.
Mitomycin C modulation of corneal wound healing after photorefractive keratectomy in highly myopic eyes.
Gambato C, Ghirlando A, Moretto E, Busato F, Midena E.
SourceRefractive Surgery Service and Antimetabolite Therapy Research Unit, Department of Ophthalmology, University of Padova, Padova, Italy.
Abstract
PURPOSE: To evaluate the role of topical mitomycin C in corneal wound healing (CWH) after photorefractive keratectomy (PRK) in highly myopic eyes.
DESIGN: Prospective, double-masked, randomized clinical trial.
PARTICIPANTS: Seventy-two eyes of 36 patients affected by high (>7 diopters) myopia.
METHODS: In each patient, one eye was randomly assigned to PRK with intraoperative topical 0.02% mitomycin C application, and the fellow eye was treated with a placebo. Postoperatively, mitomycin C-treated eyes received artificial tears (3 times daily, tapered in 3 months), whereas the fellow eye was treated with fluorometholone sodium 2% and artificial tears (3 times daily, tapered in 3 months).
MAIN OUTCOME MEASURES: Uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA), contrast sensitivity, manifest refraction, and biomicroscopy. Contrast sensitivity was determined using the Pelli-Robson chart. Corneal confocal microscopy documented CWH.
RESULTS: Mean follow-up was 18 months (range, 12-36). No side effects or toxic effects were documented. At 12-month follow-up examination, UCVAs (logarithm of the minimum angle of resolution) were 0.4+/-0.48 and 0.5+/-0.53 (P = .03) in mitomycin C-treated eyes and corticosteroid-treated eyes, respectively. At 1 year, corneal haze developed in 20% of corticosteroid-treated eyes, versus 0% of mitomycin C-treated eyes. At 12, 24, and 36 months, corneal confocal microscopy showed activated keratocytes and extracellular matrix significantly more evident in untreated eyes (Ps = 0.004, 0.024, and 0.046, respectively).
CONCLUSION: Topical intraoperative application of 0.02% mitomycin C can reduce haze formation in highly myopic eyes undergoing PRK.
Comment in
Ophthalmology. 2006 Feb;113(2):357; author reply 357-8
The development of a subtype B AMPV reverse genetics system
No full textA reverse genetics system is the only available method to introduce specific mutations into the AMPV genome. To date no system for the AMPV subtype B had been reported. In the system described, plasmids for N, P, M2, the polymerase and the full genome were constructed under the control of the T7 promoter. Producing intact clones containing the virus polymerase gene proved highly technically demanding due to the issue of them containing sequences toxic to bacteria, thus
leading to sections of the gene being spontaneously deleted. Nonetheless, once all clones had been generated and transfected into Vero cells previously infected with a fowlpox recombinant
virus expressing T polymerase, AMPV was recovered
Evidence of AMPV attachment protein evolution coincident with mass live vaccine introduction in Italy
No full textAvian metapneumoviruses (AMPV) of subtype B dominate over other subtypes on Italian poultry farms in northern Italy. AMPVs from the Veneto region of Italy between 1987 and 2007 were sequenced in their attachment (G) and fusion (F) protein genes,
together with other subtype B AMPVs from other parts of Western Europe, collected prior to 1994. All viruses in the survey had very similar predicted F sequences whereas the predicted G protein sequences found in Italy from 2001 were distinctly different from those found in pre 1994 viruses. Nonetheless pre 1994 Italian AMPVs were more similar to post 2000 AMPVs than other pre 1994 viruses from other parts of Europe, thereby showing that the later viruses had probably evolved from early Italian viruses. The occurrence of the later variants followed introduction of the mass
administration with a single subtype B vaccine and its G protein sequence placed it clearly in the pre 1994 cluster. The possibility of the vaccine having driven field virus evolution in order to evade immune pressure cannot be excluded
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
A Multi-Language Comparison of Influences on Author Verification using Character N-Grams
No full textWe create a new multi-language corpus for author verification based on Wikipedia talkpages, and evaluate the influence that differences in topic and time have on character n-gram author profiles. Topic alignment between two texts is found to increase author verification precision, and an authors writing style is found to change over time, but not more significantly after 3 years than after 1 year.Information ArchitectureWISElectrical Engineering, Mathematics and Computer Scienc
A 0.12mm<sup>2</sup> Wien-Bridge Temperature Sensor with 0.1°C (3σ) Inaccuracy from -40°C to 180°C
No full text Resistor-based temperature sensors can achieve much higher resolution and energy efficiency than conventional BJT-based sensors [1], but they typically occupy more area (> 0.25 mm 2 ) and have lower operating temperatures (le 125 {circ} {C}) [2]-[4]. This work describes a 0.12mm 2 resistor-based sensor that uses a Wien-bridge (WB) filter to achieve 0.1 {circ} {C} (3 sigma) inaccuracy from - 40 {circ} {C} to 180 {circ} {C}. Compared to a state-of-the-art WB sensor [4], it occupies 6 × less area and achieves comparable relative accuracy over a 76% wider operating range. Session 10.3 Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic InstrumentationMicroelectronic
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