Bioengineered Platforms to Study Carcinoma Cell Response to Drug Treatment

The tumor extracellular matrix (ECM) plays an important role in facilitating tumor growth and mediating tumor cells\u27 resistance to drugs. However, during drug development, potential chemotherapeutics are screened in plastic plates, which lack relevant ECM physicochemical cues. In order to improve drug development process, this dissertation includes the development of relevant 2D and 3D biomaterial systems that can be used to study carcinoma cell response to drug treatment. A novel poly(ethylene glycol)-phosphorylcholine (PEG-PC) high-throughput biomaterial platform was developed to study how the ECM mechanochemical properties affect cancer cells\u27 response to drug. The PEG-PC biomaterial is optically transparent, has a mechanical range from 1 to 10,000 kPa in Young\u27s modulus, and allows easy coupling of cell adhesive proteins. When testing several breast and liver cancer cell lines on PEG-PC gels that had different stiffnesses and integrin-binding sites, there was a significant increase in drug resistance with increasing substrate stiffness. It was found that this stiffness-induced drug resistance was independent of Rho-ROCK and EGFR signaling, but co-administration of a β1 integrin antibody, or an inhibitor to JNK, with sorafenib effectively eliminated the stiffness-mediated sorafenib resistance. Finally, 3D hydrogel systems, poly(N-isopropylacrylamide)-PEG (PNIPAAm-PEG) and PEG-Maleimide, were utilized to create multi-cellular spheroids to study drug resistance in 3D. Both SkBr3s and MDA-MB-231s were tested with sorafenib, lapatinib, temsirolimus, and doxorubicin across varying moduli and geometry (plastic, 2D and 3D hydrogels, spheroid) in different medium conditions. For some drugs, the change in platform or medium was found to have the largest effect on the variation of the IC-50 than the change in modulus. Specifically, the IC-50s varied the most when SkBr3s were treated with sorafenib and temsirolimus and when MDA-MB-231s were treated with sorafenib and lapatinib. However, when treated with doxrorubicin, the IC-50s of both cell types were similar across all platforms. These results demonstrate the utility of tailored biomaterial systems to address basic questions related to tumor microenvironment and drug resistance in cancer, and highlight the importance of incorporating relevant ECM factors into drug testing

Effect of thickness of polyethylene packaging and temperature on quality of solar-dried oyster mushroom (Pleurotus sajor-caju)

Pleurotus sajor-caju is evaluated as an edible fungi with high nutritional and medicinal value, but fresh mushrooms are easily damaged after harvest due to many reasons. Drying methods can be taken to maintain mushroom quality, reduce losses and prolong postharvest storage time. The objective of this study was to evaluate the effects of polyethylene (PE) packaging thickness (91.70 µm; 81.30 µm and 53.50 µm), temperature (28 oC-30 oC and 3 oC-5 oC) (with air humidity of 60-62% and 76-78% respectively), to the quality of oyster mushrooms dried by solar energy, during storage. During the storage period, the total sugar and protein contents of all treatments decreased. Besides, the colour (through the difference in lightness and darkness (?L) value) and firmness of the solar-dried oyster mushrooms also decreased, so, oyster mushrooms were darkened and softened. After 6 months, the lowest protein, total sugar and lipid loss was found in PE packaging of 91.70 µm thickness at storage temperature of 3 oC-5 oC. In addition, the water activity of dried mushrooms was lower (less than 0.7), so it ensures microbiological safety

A profiling analysis of contributions of cigarette smoking, dietary calcium intakes, and physical activity to fragility fracture in the elderly

Fragility fracture and bone mineral density (BMD) are influenced by common and modifiable lifestyle factors. In this study, we sought to define the contribution of lifestyle factors to fracture risk by using a profiling approach. The study involved 1683 women and 1010 men (50+ years old, followed up for up to 20 years). The incidence of new fractures was ascertained by X-ray reports. A “lifestyle risk score” (LRS) was derived as the weighted sum of effects of dietary calcium intake, physical activity index, and cigarette smoking. Each individual had a unique LRS, with higher scores being associated with a healthier lifestyle. Baseline values of lifestyle factors were assessed. In either men or women, individuals with a fracture had a significantly lower age-adjusted LRS than those without a fracture. In men, each unit lower in LRS was associated with a 66% increase in the risk of total fracture (non-adjusted hazard ratio [HR] 1.66; 95% CI, 1.26 to 2.20) and still significant after adjusting for age, weight or BMD. However, in women, the association was uncertain (HR 1.30; 95% CI, 1.11 to 1.53). These data suggest that unhealthy lifestyle habits are associated with an increased risk of fracture in men, but not in women, and that the association is mediated by BMD

Political Corruption and Mergers and Acquisitions

This research examines the relation between political corruption and mergers and acquisitions (M&As). We find that local corruption increases firm acquisitiveness but decreases firm targetiveness. The levels of corruption in acquirer areas relate positively to the bid premiums and negatively to the likelihood of deal completion. Corruption motivates acquiring firms to use excess cash for payment, which mitigates the negative effect of corruption on acquirer shareholder value. The evidence indicates that acquisitions help acquiring firms convert cash into hard-to-extract assets and relocate assets from the high to low corruption areas, thereby shielding their liquid assets from expropriation by local officials

High Order Modulation Protograph Codes

Digital communication coding methods for designing protograph-based bit-interleaved code modulation that is general and applies to any modulation. The general coding framework can support not only multiple rates but also adaptive modulation. The method is a two stage lifting approach. In the first stage, an original protograph is lifted to a slightly larger intermediate protograph. The intermediate protograph is then lifted via a circulant matrix to the expected codeword length to form a protograph-based low-density parity-check code

Heat Stress Affects Seed Set and Grain Quality of Vietnamese Rice Cultivars during Heading and Grain Filling Period

Environmental stress trigger a variety of rice plant response, ranging from alters seed set, grain yield and grain quality during flowering and grain filling stage.  Efforts are required to improve our understanding of the impact of heat stress on rice production, which are essential strategies in rice cultivation. This article investigated the seed set, yield components and grain yield of Vietnamese rice cultivars (Indica germplasm) under high temperature environment during the flowering and grain filling stage. Six rice cultivars, including popular cultivars and new cultivars of Cuu Long Delta Rice Research Institute, and one popular extraneous cultivar with differences in maturing time, were grown in pots at high temperature (HT) and natural temperature condition as control (CT). All rice cultivars were subjected to the high temperature starting from the heading stage to the harvest maturity, applied by greenhouse effect. The greenhouse has about 25 cm window opening on 3 sides for air ventilation. The seed set rate of the heat-sensitive rice genotypes decreased significantly under HT, leading to a significant reduction in grain yield. The lowest seed set was recorded in “OM4900” (44.3%) and “OM18” (39.9%) under high temperature environment. The lower yield in all rice cultivars at an elevated temperature resulted in a dramatic decrease of filled grains and contributed to a loss of 1000-grain weight. ‘“OM892” is a potential rice cultivar for heat tolerant breeding program due to the seed set percentage was above 80% in both HT and CT conditions. High temperature during the grain filling stage resulted in a decreased amylose and increased chalkiness for all OM cultivars