Applied Science Private University

About: Applied Science Private University is a education organization based out in Amman, Jordan. It is known for research contribution in the topics: Population & Catalysis. The organization has 4124 authors who have published 5299 publications receiving 116167 citations.

Benzylidene derivatives of andrographolide inhibit growth of breast and colon cancer cells in vitro by inducing G1 arrest and apoptosis

Abstract: Background and purpose: Andrographolide, the major phytoconstituent of Andrographis paniculata, was previously shown by us to have activity against breast cancer. This led to synthesis of new andrographolide analogues to find compounds with better activity than the parent compound. Selected benzylidene derivatives were investigated for their mechanisms of action by studying their effects on the cell cycle progression and cell death. Experimental approach: Microculture tetrazolium, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and sulphorhodamine B (SRB) assays were utilized in assessing the in vitro growth inhibition and cytotoxicity of compounds. Flow cytometry was used to analyse the cell cycle distribution of control and treated cells. CDK1 and CDK4 levels were determined by western blotting. Apoptotic cell death was assessed by fluorescence microscopy and flow cytometry. Key results: Compounds, in nanomolar to micromolar concentrations, exhibited growth inhibition and cytotoxicity in MCF-7 (breast) and HCT-116 (colon) cancer cells. In the NCI screen, 3,19-(2-bromobenzylidene) andrographolide (SRJ09) and 3,19-(3-chloro-4-fluorobenzylidene) andrographolide (SRJ23) showed greater cytotoxic potency and selectivity than andrographolide. SRJ09 and SRJ23 induced G1 arrest and apoptosis in MCF-7 and HCT-116 cells, respectively. SRJ09 downregulated CDK4 but not CDK1 level in MCF-7 cells. Apoptosis induced by SRJ09 and SRJ23 in HCT-116 cells was confirmed by annexin V-FITC/PI flow cytometry analysis. Conclusion and implications: The new benzylidene derivatives of andrographolide are potential anticancer agents. SRJ09 emerged as the lead compound in this study, exhibiting anticancer activity by downregulating CDK4 to promote a G1 phase cell cycle arrest, coupled with induction of apoptosis. British Journal of Pharmacology (2008) 155, 641–654; doi:10.1038/bjp.2008.368; published online 22 September 2008

Closure of Boolean operations on geometric entities

Abstract: Boolean operations akin to set interaction, union, and difference play an imporatant role in CAD/CAM. Geometric entities of practical interest (e.g. polygons or polyhedra) are not algebraically closed under the conventional set operators, and therefore algorithms cannot implement conventional set operations if they are to produce results that can be used in subsequent calculations. This paper demonstrates that closure raises delicate issues, and presents a correct mathematical approach based on the topological notion of regularity.

Exploring Think-Alouds in Usability Testing: An International Survey

Abstract: Research problem: The study explored think-aloud methods usage within usability testing by examining the following questions: How, and why is the think-aloud method used? What is the gap between theory and practice? Where does this gap occur? Literature review: The review informed the survey design. Usability research based on field studies and empirical tests indicates that variations in think-aloud procedures may reduce test reliability. The guidance offered on think-aloud procedures within a number of handbooks on usability testing is also mixed. This indicates potential variability in practice, but how much and for what reasons is unknown. Methodology: An exploratory, qualitative survey was conducted using a web-based questionnaire (during November-December 2010). Usability evaluators were sought via emails (sent to personal contacts, usability companies, conference attendees, and special interest groups) to be cascaded to the international community. As a result we received 207 full responses. Descriptive statistics and thematic coding were used to analyze the data sets. Results: Respondents found the concurrent technique particularly suited usability testing as it was fast, easy for users to relate to, and requires limited resources. Divergent practice was reported in terms of think-aloud instructions, practice, interventions, and the use of demonstrations. A range of interventions was used to better understand participant actions and verbalizations, however, respondents were aware of potential threats to test reliability, and took steps to reduce this impact. Implications: The reliability considerations underpinning the classic think-aloud approach are pragmatically balanced against the need to capture useful data in the time available. A limitation of the study is the focus on the concurrent method; other methods were explored but the differences in application were not considered. Future work is needed to explore the impact of divergent use of think-aloud instructions, practice tasks, and the use of demonstrations on test reliability.