611 research outputs found
Antibody targeted nanoparticles for imaging and therapy of cancer
No full textThe central hypothesis for this thesis is that antibody-targeted superparamagnetic iron
oxide nanoparticles (SPIONs) can be used for diagnosis and therapy of cancer. The
hypothesis is based on the knowledge that firstly, recombinant single chain Fv antibody
fragments (scFv) are effective targeting reagents and second, SPIONs can substantially
improve the sensitivity of magnetic resonance imaging (MRI). Furthermore, SPIONs
can be induced to generate heat when subjected to an alternating magnetic field (AMF).
The aim of the thesis was to test the cancer imaging and therapeutic potential scFvfunctionalised
nanoparticles by: (1) Generating scFvs reactive with carcinoembryonic
antigen (CEA) a cell surface tumour marker. (2) Developing conjugation methods to
attach the scFv, in functional form, to SPIONs. (3) Evaluating the cellular interaction
(targeting and specificity) of functionalised SPIONs and (4) Measuring the imaging and
therapeutic heating effect of the targeted SPIONs.
ScFvs reactive to CEA were generated in Pichia pastoris and conjugation chemistries
optimised for attachment of purified scFv to SPION surface. Targeting efficacy of the
scFv functionalised SPIONs was tested by ELISA, cellular uptake, confocal microscopy
and MRI. Results demonstrated unequivocal CEA-specific cellular uptake and CEAspecific
MRI, using SPIONs conjugated with Sm3E, a high affinity humanized anti-
CEA scFv. Cellular interaction of the Sm3E-SPIONs was found to be influenced by size
and surface properties; neutrally charged Sm3E functionalised dextran SPIONs localised
preferentially to the outside of the cell membrane, whilst negatively charged Sm3E
functionalised PEGylated SPIONs showed evidence of intracellular uptake. The SPIONs
were shown to be effective generators of heat when exposed to AMF of 150V, 0.74A
and 1MHz. AMF treatment of Sm3E-SPION targeted cells was found to induce
expression of the stress protein HSP70 and lead to hyperthermic cell death in vitro.
These results indicate that scFv-SPION conjugates have potential for selective tumour
imaging and therapy
Conditions for safe and effective ADEPT treatment
No full textAntibody directed enzyme prodrug therapy (ADEPT) is a drug delivery system developed for the treatment of cancer. ADEPT uses a systemically administered antibody, tethered to an enzyme, to localize enzyme in tumour deposits. When the antibody-enzyme has cleared from the circulation, a low-toxicity prodrug is given. The prodrug is converted by the tumour-bound enzyme into an active cytotoxic drug. The system has potential to generate a highly potent cytotoxic agent at the tumour site.
A clinical ADEPT system using MFECP1, a recombinant fusion protein consisting of an anti-carcinoembryonic antigen single chain Fv antibody and the bacterial enzyme carboxypeptidase G2, in combination with a bis-iodo phenol mustard prodrug (BIP) has been developed. A previous phase I/II clinical trial established the maximum tolerated dose of a single treatment cycle of this ADEPT system.
In-vivo models with human tumour xenografts indicate that repeated ADEPT treatment with MFECP1/BIP led to greater efficacy without increased toxicity. This thesis aims to establish conditions required for safe and effective ADEPT when using MFECP1/BIP in man. This was achieved by conducting a phase I/II clinical trial of repeat-treatment ADEPT and comparing and combining the results with data from the single-treatment trial. The combined dataset provided mechanistic and clinical information on 43 patients.
Multiple parameters were investigated to examine the likely cause of toxicity and clinical risk factors for its occurrence. Efficacy was evaluated using CT, FDG-PET and serum tumour markers. The nature of the immune response to MFECP1 was investigated and possible strategies to reduce immunogenicity were developed.
Results showed that repeated therapy was feasible in man and did not increase the risk of MFECP1 infusion reactions. At the maximum tolerated total prodrug dose for 2 ADEPT treatments, one of three patients experienced tumour response on FDG-PET imaging. This MD (Res) thesis significantly increases understanding of the conditions required for safe and effective ADEPT
Chronic toxicity of pharmaceuticals to the benthic green alga Closterium ehrenbergii
No full textPharmaceuticals in the environment have emerged to a topic of global concern. Since these substances are designed to be biologically active, hazardous effects on non-target organisms are frequently reported. Here, the effects of five pharmaceuticals, one radiocontrast agent, and one degradation product on the freshwater green alga Closterium ehrenbergii were evaluated after chronic exposure of 168 h. Growth and maximum quantum yield (FV/FM) were used as endpoints and complemented by the assessment of morphology and chlorophyll fluorescence. We found that the tested antibiotics Ciprofloxacin and Ofloxacin impaired chloroplast integrity, resulting in a reduction of FV/FM from 0.1 mg/L. The disintegration of chloroplasts at higher concentrations (c = 0.3 and 0.8 mg/L, respectively) was visualized by brightfield and fluorescence microscopy. In contrast, Sulfamethoxazole interfered with cell division, leading to malformation of cells from 0.8 mg/L. Furthermore, the antibiotics exhibited a latency period of 72 h after which they started to reveal their true effects. Therefore, the importance of long-term toxicity testing is outlined in order to avoid underestimation of toxic effects of pharmaceuticals. Based on the EC10 values obtained, the antibiotics were considered to meet the criteria for classification as toxic to aquatic life with long lasting effects. The other test substances were found to exert no effects on C. ehrenbergii or only at very high concentrations and were classified as nontoxic
Numerical Investigation of the Influence of Ground Effect on the FV Aircraft: Influence of Ground Effect on the Flying V Aircraft
No full textIn order to meet the growing market demands of quieter, more aerodynamically efficient aircrafts, manufacturers constantly strive to innovate and optimize their designs. Over the years however, the extent of innovation related to the conventional 'tubular fuselage' configurations have somewhat reached a stalemate as the gains obtained have only been marginal. It is for this reason, there has off-late been a surge in research pertaining to unconventional aircraft design and configurations. The Flying V (FV) is one such alternative that was conceptualized by J. Benad at TU Berlin along with the Future Projects Office (FPO) at Airbus Operations GmbH in Hamburg. Results obtained from past studies show a 25% improvement in the lift to drag ratio of the FV as compared to the NASA Common Research Model (CRM), which was set as the basis of comparison for a fixed wing aircraft configuration. So far, aerodynamic studies have only focused on the cruise performance of the FV without any emphasis on its low speed behavior. Conventional aircrafts use high lift devices like flaps and slats to improve stability and increase the amount of lift its wings produce at lower speeds. The FV however, has no such high lift device and solely relies on the lift produced by its wing to achieve a speed that is low enough to land safely. For this reason, this thesis aims to investigate the influence of ground proximity on the lift, drag and pitching moments of the FV which in turn affect its take-off and landing characteristics. Compressible RANS equations were solved with the k-omega SST turbulence model using ANSYS Fluent on a 4.6\% scaled model of the FV. The ground was numerically realized by employing the moving ground boundary condition equal in velocity to the free stream. Results from these simulations have shown a 11% reduction in the drag polar of the FV when closest to the ground as compared to when in unbounded flow. Additionally, the proximity to the ground causes an increase in lift and this allows the FV to touch down at 19 degrees while the maximum rotation angle during take-off is predicted to be about 13 degrees for a positive climb gradient when also considering the One-Engine-Idle (OEI) scenario. This corresponds to a lift to drag ratio equal to 10 and a lift-off lift coefficient of 0.56 approximately. The effect of ride height on the longitudinal stability of the FV showed that favorable pitching moments were obtained for angles of attack between 0 degrees and 5 degrees and for angles greater than 17.5 degrees. A near wake analysis was also performed for different angles of attack and at different heights from the ground to investigate the flow phenomena over the FV and the evolution of the wake downstream. No significant span wise flow is seen when the angle of attack is 0 degrees and the flow appears to travel parallel to the stream-wise direction. Additionally, in case of very high angles of attack, the flow streamlines confirm the occurrence of a large vortex emanating from the leading edge kink of the wing. When in unbounded flow a secondary vortex located inboard is produced at 17 degrees. The diameter of the tip vortex is seen to be greater than the inboard secondary vortex for an angle of attack equal to 17 degrees. At greater angles of attack, the secondary vortex is seen to grow in diameter as the height reduces.Flying VAerospace Engineerin
FV-MgNet: Fully connected V-cycle MgNet for interpretable time series forecasting
No full textBy investigating iterative methods for a constrained linear model, we propose a new class of fully connected V-cycle MgNet for long-term time series forecasting, which is one of the most difficult tasks in forecasting. MgNet is a CNN model that was proposed for image classification based on the multigrid (MG) methods for solving discretized partial differential equations (PDEs). We replace the convolutional operations with fully connected operations in the existing MgNet and then apply them to forecasting problems. Motivated by the V-cycle structure in MG, we further propose the FV-MgNet, a V-cycle version of the fully connected MgNet, to extract features hierarchically. By evaluating the performance of FV-MgNet on popular datasets and comparing it with state-of-the-art models, we show that the FV-MgNet achieves better results with less memory usage and faster inference speed. In addition, we develop ablation experiments to demonstrate that the structure of FV-MgNet is the best choice among the many variants.The first author is supported in part by Beijing Natural Science Foundation Project (No. Z200002), the second and fourth authors are partially supported by the KAUST Baseline Research Fund, and the third author is supported by Hetao Shenzhen-Hong Kong Science and Technology Innovation Cooperation Zone Project (No. HZOSWS-KCCYB-2022046)
Assessment pedestrian crossing safety using vehicle-pedestrian interaction data through two different approaches: Fixed videography (FV) vs In-Motion Videography (IMV)
No full textA significant portion of pedestrian accidents occurs in the outskirts areas due to the high vehicle speed and lack of safety facilities for pedestrians. Behavioral study on drivers and pedestrians is the key to better understand the causes of pedestrian accidents in order to develop safety models. Despite numerous studies on pedestrian safety based on various roads, outskirt areas have not been considered. Hence, the present study focuses on evaluating the safety of pedestrian crossing in urban and outskirt areas and to determine the differences of drivers and pedestrians’ behaviors between these areas through data based on fixed videography (FV) and in-motion videography (IMV). These approaches may lead to an exact analysis of the behavioral differences of road users behaviors from the perspective of pedestrians (FV data) and drivers (IMV data) in urban and outskirts roads. Accordingly, behavioral studies were conducted at urban and outskirts sites through FV as well as IMV using the behavior of 29 participants in the same roads in Babol city, Iran. The gap acceptance model using linear regression and pedestrian crossing probability model using logistic regression for both approaches showed similarity on results in both urban and outskirts roads. Furthermore, behaviors of pedestrians crossing and drivers’ yielding on urban and outskirts roads were very similar. Vehicle speed, the distance of vehicle to pedestrian at the possible collision point, size of pedestrian groups, and waiting time before crossing were the most important behavioral differences of pedestrian for choosing a gap acceptance and probability of crossing on various sites through two different approaches. The inference of the models obtained in this study will lead to a better understanding of the behavior of road users for studies on advanced driving assistance systems (ADAS).Safety and Security Scienc
Promoting fruit and vegetable consumption during the COVID-19 pandemic – SportStudisMoveYou (SSMY): A randomized controlled trial
No full textBACKGROUND: The stay-at-home circumstances due to the global coronavirus pandemic have had some negative impacts on people's eating behavior. PURPOSE: Therefore, this study attempted to improve fruit and vegetable (FV) consumption intention and behavior through an online video intervention based on the social cognitive theory. METHODS: Participants were recruited with a promotion video posted on social media channels. After consenting and completing a pre-survey, participants were randomly assigned to either a) the intervention group addressing FV consumption or the b) attention control group addressing physical activity. After two weeks, the participants completed an online post-survey. RESULTS: The participants (N = 82) were 77% female and 50% students; 95% chose German for the survey language, and 84% were from Switzerland. The mean baseline FV consumption intention was 3.05 (standard deviation: 1.03), and FV consumption was 4.64 (standard deviation: 2.06) portions a day. The analysis showed no significant change in FV consumption intention (F = (1, 78) = 0.02, p = 0.88, ηp(2) = 0.00) or behavior (F = (1, 78) = 0.019, p = 0.89, ηp(2) = 0.03) due to the intervention. CONCLUSIONS: Plausible reasons why no significant effect was found were the brief intervention duration, the setting and insufficient tailoring. The lessons learned from this study are to plan better, tailor more to the needs of participants and carefully consider the goals before promoting an intervention
Auditors' Role in Fair Value Monitoring: Evidence from Security-Level Data
No full textI study the role of the audit firm as monitor of its clients’ fair value (FV) measurements. Specifically, using a setting in the insurance industry where I can identify fair values at the security level, I find that audit firms’ security-specific FV experience is associated with increased consistency in valuations among clients holding the same security, consistent with audit firms developing FV expertise at the security level. Moreover, FV consistency is higher when the audit office is in a more concentrated market, and when the client is economically less important to the audit office, consistent with audit office market incentives affecting FV audit quality. My study sheds light on the mechanisms that shape the role of auditors in monitoring the increasingly important yet subjective FV determination process.Ph.D
Expression of recombinant multi-coloured fluorescent antibodies in <it>gor </it><sup>-</sup>/<it>trxB</it><sup>- </sup><it>E. coli </it>cytoplasm
No full textAbstract Background Antibody-fluorophore conjugates are invaluable reagents used in contemporary molecular cell biology for imaging, cell sorting and tracking intracellular events. However they suffer in some cases from batch to batch variation, partial loss of binding and susceptibility to photo-bleaching. In theory, these issues can all be addressed by using recombinant antibody fused directly to genetically encoded fluorescent reporters. However, single-chain fragment variable domains linked by long flexible linkers are themselves prone to disassociation and aggregation, and in some cases with isoelectric points incompatible with use in physiologically relevant milieu. Here we describe a general approach that permits fully functional intracellular production of a range of coloured fluorescent recombinant antibodies with optimally orientated VH/VL interfaces and isoelectric points compatible for use in physiological solutions at pH 7.4 with a binding site to fluorophore stoichiometry of 1:1. Results Here we report the design, assembly, intracellular bacterial production and purification of a panel of novel antibody fluorescent protein fusion constructs. The insertion of monomeric fluorescent protein derived from either Discosoma or Aequorea in-between the variable regions of anti-p185HER2-ECD antibody 4D5-8 resulted in optimal VH/VL interface interactions to create soluble coloured antibodies each with a single binding site, with isoelectric points of 6.5- 6. The fluorescent antibodies used in cell staining studies with SK-BR-3 cells retained the fluorophore properties and antibody specificity functions, whereas the conventional 4D5-8 single chain antibody with a (Gly4Ser)3 linker precipitated at physiological pH 7.4. Conclusions This modular monomeric recombinant fluorescent antibody platform may be used to create a range of recombinant coloured antibody molecules for quantitative in situ, in vivo and ex vivo imaging, cell sorting and cell trafficking studies. Assembling the single chain antibody with monomeric fluorescent protein linker facilitates optimal variable domain pairing and alters the isoelectric point of the recombinant 4D5-8 protein conferring solubility at physiological pH 7.4. The efficient intracellular expression of these functional molecules opens up the possibility of developing an alternative approach for tagging intracellular targets with fluorescent proteins for a range of molecular cell biology imaging studies.</p
Test de inmersión de larvas modificado en el perfil de sensibilidad de Rhipicephalus microplus a base de amitraz
No full textEn la presente tesis se llevó a cabo la validación del test de inmersión de larvas modificado en jeringa en el perfil de sensibilidad de Rhipicephalus microplus a base de amitraz. La validación se realizó utilizando como matriz larvas de Rhipicephalus (Boophilus) microplus (cepa Mozo, susceptible) de 14 a 21 días de vida. El ensayo se realizó empleando concentraciones de amitraz en el rango de 1000 a 0.00002 ppm, por triplicado (n = 50). La inmersión se realizó durante 20 segundos y la incubación fue de 48 horas a 27°C / 90% humedad. Se contabilizaron larvas vivas y muertas, dando por muertas aquellas que no manifestaban movimiento, calculando el porcentaje de mortalidad. Los porcentajes de mortalidad de los grupos control se mantuvieron por debajo del 10 %; en todas las concentraciones de amitraz incluidas en la tesis, el porcentaje de mortalidad de larvas de Rhipicephalus microplus se mantuvo por encima de 81.3%. Se repitió la técnica con larvas de garrapatas resistentes a amitraz cedidas por DILAVE. Los porcentajes de mortalidad se mantuvieron por encima del 95.8%. Se concluye que se lograron establecer los parámetros para la realización de la técnica de inmersión de larvas de Rhipicephalus microplus en jeringas para amitraz comercial y, la técnica de inmersión en jeringas para amitraz presenta un alto grado de sensibilidad lo que impide construir curvas de dosis-respuestas
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