169,743 research outputs found
Treatment of cerebral arteriovenous malformations
No full textEven today, arteriovenous malformations (AVM) are one of the most complex conditions encountered in neurosurgical practice. The difficulty in treatment is not confined to surgical resection of the AVM, but also affects the indications for treatment and the type of appropriate therapy. Each treatment aims at complete exclusion of the AVM. Partial resection has no significant effect on the risk of bleeding. Despite ongoing attempts to devise treatment protocols, each patient presenting an AVM is different and each individual case needs to be assessed by a team familiar with this type of lesion and aware of the percentage risk to the patient in proposing a treatment. A recent evaluation of numerous surgical series demonstrated an operative mortality for AVMs of different sizes at 3.3%. Post-operative angiography only displays complete exclusion of the AVM in 97% of cases. The aim of endovascular treatment is to exclude the nidus. If this is not achieved, the AVM will revascularize sooner or later. Endovascular treatment alone seldom results in complete occlusion of the AVM. Some literature reports describe a high mortality rate linked with endovascular treatment with percentages of around 1.6% with a 12.8% morbidity. In our experience, the morbidity linked to endovascular treatment is below 4%. Complications linked to radiosurgery are extremely rare. The main problem of radiosurgery with LINAC or gamma knife is the possibility of treating only small AVM successfully. From November 1991 to August 2001, AVM were found in 115 cases out of 1137 patients admitted for vascular malformations (10%). Of these, 93 (81%) had supratentorial AVM whereas 22 (19%) had subtentorial lesions. Treatment (surgery, embolisation, radiosurgery or a combination) was carried out in 94 cases (82%). Of the nine patients with non-bleeding AVM who did not receive treatment for various reasons, none experienced haemorrhage in the follow-up period of one to ten years. Of the 94 patients who had had a haemorrhage, 12 presented rebleeding of the AVM (13%). In an overall analysis of our results irrespective of the type of treatment and including untreated patients, 67 out of 115 (59%) were discharged without neurological deficit (good outcome). Overall morbidity was 29%; 14 patients died, giving a mortality rate of 12%. The decision how to treat each individual patients is taken after discussion with neuroradiologists and radiosurgeons. In general, in the cases referred to us, we acted as follows: - In superficial AVM less than 25-30 cm3 in non-eloquent brain areas, the lesion was treated surgically. - In AVM on the mesial face of the hemisphere or involving the cingulate or corpus callosum regions, direct obliteration was performed in six cases whereas three were treated by radiosurgery. - Deep para or intraventricular AVM or caudate nucleus or striocapsulothalamic lesions were usually treated by radiosurgery preceded by partial embolisation. - Small AVM in eloquent areas were treated by radiosurgery whereas large lesions were first treated by embolisation followed by radiosurgery. - AVM close to eloquent areas were usually treated surgically, possibly after endovascular therapy
Finite Element Modeling Application in Forensic Practice: A Periprosthetic Femoral Fracture Case Study
No full textThe incidence of periprosthetic fractures has rapidly increased in the last two decades and has been the cause of a large number of revision surgeries and permanent physical disability for many patients, as well as a significant socioeconomic burden for many nations. This research deals with a periprosthetic femur fracture real event, occurred following a total hip arthroplasty and treated with one of the most widespread internal fixation methods: the implant of a periprosthetic femur plate system. A Finite Element analysis was performed to investigate the implanted femur plate break after a short follow-up and to understand the plate break causes. Such events are currently object of forensic debate as more and more often hospitals, surgeons, and medical device manufacturers are denounced by patients to whom similar events occur. In this work, different load situations acting on the femur during daily and incidental activities were simulated, in order to validate the correct behavior of the plate, according to the intended use recommended by the manufacturer. The analysis demonstrates that the plate failure can occur in situations of unconventional loading such as that caused by stumbling and in presence of incomplete bone healing
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
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
A ±25A Versatile Shunt-Based Current Sensor with 10kHz Bandwidth and ±0.25% Gain Error from -40°C to 85°C Using 2-Current Calibration
No full textAccurate current sensing is critical in many industrial applications, such as battery management and motor control. Precise shunt-based current sensors have been reported with gain errors of less than 1% over the industrial temperature range (-40°C to 85°C) [1]–[4]. However, since they are intended for coulomb counting, their bandwidth is limited to a few tens of Hz, making them unsuitable for battery impedance or motor-current sensing. This paper presents a current sensor with a wide (10kHz) bandwidth and a tunable temperature compensation scheme (TCS), which allows it to be flexibly used with different types of shunts while maintaining high accuracy. A low-cost room-temperature calibration scheme is proposed to optimize gain flatness over temperature by exploiting the shunt's self-heating at large currents. Over the industrial temperature range and a ±25A current range, it achieves state-of-the-art gain error (±0.25%) with both low-cost PCB and stable metal-alloy shunts.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
An Article About Albertus C. Van Raalte, Author Unknown, Except for Parts Taken from an Article by Anna C. Post
No full textAn article about Albertus C. Van Raalte, author unknown, except for parts taken from an article by Anna C. Post. The author knew first generation persons in the Holland settlement and therefore, the article has some value.https://digitalcommons.hope.edu/vrp_1890s/1012/thumbnail.jp
Novel HDAC inhibitors with a phenylcinnamic scaffold: synthesis and evaluation of antitumor activity
No full textInappropriate epigenetic modifications of gene expression are associated with malignant phenotype and tumor progression. Regulation of gene expression is mediated by several mechanisms such as DNA methylation, ATP-dependent chromatin remodeling, and post-translational modifications of histones. Enzymes responsible for the reversible acetylation/deacetylation processes are histone acetyltransferases (HATs) and histone deacetylases (HDACs), respectively. Inhibitors of histone deacetylase (HDAC) enzymes have gained prominence as an emerging class of anticancer agents.
We synthesized a series of hydroxamic acid-based HDAC inhibitors, characterized by a biphenyl-4-yl-acrylohydroxamic acid skeleton. The compounds were designed based on the hypothesis that the phenyl ring, extended from the hydroxamic acid via a double bond, could be suitable to occupy the narrow tube-like pocket of the HDAC active site. On the contrary, the cap structure appeared to accommodate in a large cavity, without a significant steric clash. Thus, a modification of the cap group appeared the most promising strategy to optimize drug-target interaction. Molecular docking was used to predict the optimal conformation of different molecules in the active site of a representative isoform from class I (HDAC2, sharing 85% sequence identity and 93% of sequence homology with HDAC1) and class II (HDAC6). From the results of docking studies three potential candidates with increased drug-target interactions were selected. All of them showed an activity towards HDAC1, 2 and 6 in the low μM range, estimated through a fluorimetric activity assay [2]. One of the compounds was further tested in vitro and in vivo in a colon carcinoma model and showed significant proapoptotic and antitumor activities
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