204 research outputs found
Identification of thioredoxin reductase 1-regulated genes using small interference RNA and cDNA microarray
No full textThioredoxin reductase 1 (TrxR1) is a cytosolic enzyme that plays a central role in controlling cellular redox homeostasis. TrxR1 can transduce regulatory redox signals through NADPH-dependent reduction of thioredoxin (Trx), which is able to reduce a broad spectrum of target enzymes and regulate the activity of several transcription factors (e.g., p53 and NF-kappaB). The TrxR1/Trx system is involved in every step of cancer biology, ranging from transformation and progression to invasion, metastasis and resistance to therapy. TrxR1 was also recently identified as one key enzyme involved in cell death induced by interferon-beta (IFN-beta)/all-trans retinoic acid (ATRA) anti-cancer treatment. Our study employed small interference RNA (siRNA) and microarray techniques to investigate the effect of TrxR1 silencing on gene expression in HepG2 cells. We also investigated TrxR1-mediated cell response to IFN-beta/ATRA treatment. We identified TrxR1-dependent genes with functions related to several cellular processes such as apoptosis (SOX4), ubiquitination (Ubiquitin D, F-box protein 25), organization of cytoskeletal/extracellular matrix (Keratin 19, Fibronectin 1) and transport (Cystine/Glutamate transporter). We also investigated the effect of TrxR1 siRNA on the protein profile using surface enhanced laser desorption ionization time-of-flight (SELDI-TOF) technology. Profiles confirmed significant involvement of TrxR1 in cell response to IFN-beta/ATRA
Evaluation of systems for measuring employee exposure to ultrasonic sound at Company XYZ
No full textIncludes bibliographical references
Radiolocation using amplitude modulation broadcast signals
No full textThesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.Includes bibliographical references (p. 293-294).This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.(cont.) Previous attempts at signal-of-opportunity navigation using carrier phase sidestepped the ambiguity problem by requiring that the initial position of the rover be known and that phase variations be tracked without interruption. I designed and implemented an ambiguity-function method that enables the phase ambiguity to be resolved instantaneously without position initialization or signal-tracking continuity. I encountered several impediments to AM-broadcast-based radiolocation that, if not dealt with appropriately, reduce positioning accuracy, reduce ambiguity-resolution robustness, or both. AM transmitter position uncertainty directly causes receiver position-determination uncertainty. Since the error in published antenna positions sometimes exceeds 100 meters, I conducted sub-meter-accuracy geodetic surveys of 29 Boston-area AM-broadcast antennas. The directional radiation patterns of the array antennas of many AM broadcast radio stations have phases that vary with azimuth angle. I developed and implemented a model for the phase of a directional antenna that nearly eliminated theerrors caused by this effect. AM broadcast signals travel primarily as groundwaves, which propagate with phase velocities that depend on the electrical properties of the ground. Using simulations and empirical data, I designed and implemented a model for groundwave propagation that greatly reduced the errors caused by this effect over a broad geographic area ...by Timothy Douglas Hall.Ph.D
A blood-perfusion flowmeter
No full textIncludes bibliographical references.A variety of methods have been used for measuring blood flow in large vessels. However, almost all of these methods are unsuitable for measuring perfusion flow in tissue. Basically all attempts at perfusion flow measurement have used either a tracer method (radio-active dyes, microspheres) or a thermal method where the rate of heat clearance from a heated probe is used as a measure of local flow. Tracer methods suffer from the fact that they give essentially a single measurement of flow and this only after tissue has been removed and analysed. Thermal methods on the other hand can give continuous measurement. What is actually being measured in the thermal method is the apparent thermal conductivity of the tissue in the immediate vicinity of the probe. The apparent thermal conductivity increases with flow as heat from the probe is not only conducted away by the surrounding tissue but is also carried away by the perfusing fluid. The way in which local perfusion is related to thermal conductivity and the methods used to measure thermal conductivity have led to criticisms of thermal methods. This work deals with instrumentation to eliminate some sources of error in thermal methods and automate the whole measurement procedure. It also includes a critical review of thermal methods in general and previous work in the field in particular
Weight Estimation of Superyachts
No full textSuperyachts are expected to be perfect since the owner pays millions for them, and the worst that could happen is tilting the ship once it floats. The lightweight, including the center of gravity, is essential to know with a high degree of certainty to prevent this. However, the lightweight is already expected in an early design phase, when still a lot is uncertain. When the weight deviates from the initial estimations, it would predominantly lead to unwanted changes in speed and stability.The objective is to research a standardized way of estimating the weight of a superyacht in different stages of the project, including validating the current, improved, and new methods and combining this in a single tool. In the design phase, at the beginning of the project, most weight items or groups are based on comparisons with another yacht. Currently, this is done based on a single ship similar to the new design. Still, a significant improvement will be to compare the new design with multiple yachts, with the possibility for the designer to choose the comparison vessels.The margins can also be researched. Currently, only the starting margin and the production margin at the end are set, but not in between. A guideline should be provided to indicate what margin is expected during each project stage. Also, the complexity level can influence the expected margin, which can all be placed in a table for a clear overview.The center of gravity estimation of the items is done similarly to the weights. The weight distribution of the yacht is currently not included in the weight estimations, but it will be included in the new weight estimation tool. To achieve this, besides the CoG, the length of the items also needs to be noted for the longitudinal weight distribution. With this information, distribution along the ship in the length direction can be calculated per meter. The model can be validated by comparing these early design stage estimation methods with the more detailed estimates at the end of the engineering stage.Finally, the research question can be answered, concluding the research. The weights and centers of mass of a superyacht can be predicted in the design phase by comparing the new ship to a database of existing yachts. These estimations can indicate the calculations’ completeness and accuracy at the engineering phase. The weight list includes margins based on the project’s stage and complexity. This way, the estimations and calculation accuracy are transparent and explainable. Also, the longitudinal weight distribution is added to complete and track the center of gravity estimations. Both the design and engineering department can present their findings and estimations next to each other, resulting in a clear overview of development during the project.Marine Technology | Marine Engineerin
Cetuximab for the treatment of colorectal cancer
No full textBackgroundCetuximab, an IgG1 chimeric monoclonal antibody against epidermal growth factor receptor (EGFR), has activity against colorectal cancers that express EGFR.MethodsFrom December 2003 to August 2005, 572 patients who had colorectal cancer expressing immunohistochemically detectable EGFR and who had been previously treated with a fluoropyrimidine, irinotecan, and oxaliplatin or had contraindications to treatment with these drugs underwent randomization to an initial dose of 400 mg of cetuximab per square meter of body-surface area followed by a weekly infusion of 250 mg per square meter plus best supportive care (287 patients) or best supportive care alone (285 patients). The primary end point was overall survival.ResultsIn comparison with best supportive care alone, cetuximab treatment was associated with a significant improvement in overall survival (hazard ratio for death, 0.77; 95% confidence interval [CI], 0.64 to 0.92; P=0.005) and in progression-free survival (hazard ratio for disease progression or death, 0.68; 95% CI, 0.57 to 0.80; PConclusionsCetuximab improves overall survival and progression-free survival and preserves quality-of-life measures in patients with colorectal cancer in whom other treatments have failed. (ClinicalTrials.gov number, NCT00079066 [ClinicalTrials.gov].).Derek J. Jonker, Chris J. O'Callaghan, Christos S. Karapetis, John R. Zalcberg, Dongsheng Tu, Heather-Jane Au, Scott R. Berry, Marianne Krahn, Timothy Price, R. John Simes, Niall C. Tebbutt, Guy van Hazel, Rafal Wierzbicki, Christiane Langer and Malcolm J. Moor
Aberrant myst4/brpf1 Signaling Misdirects Regional Neurogenesis Programs, Sustaining Expression of Self-Renewal Genes in Pediatric Brain Cancers
No full textNeuroscienc
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