22 research outputs found
Synthesis of 4-aminophenyl substituted indole derivatives for the instrumental analysis and molecular docking evaluation studies
No full textCALCIUM SENSING RECEPTOR FUNCTION IN COLON: A ROBUST PROMOTER OF DIFFERENTIATION AND TUMOR SUPPRESSOR
No full textThe expression of calcium sensing receptor (CaSR) in the human colonic crypt epithelium is linked to cellular differentiation while its lack of expression is associated with undifferentiated and invasive colon carcinoma. Recent studies show that CaSR suppresses the malignant phenotype through a variety of pathways that inhibits growth and promotes differentiation. CaSR also promotes cytotoxic response to fluorouracil. These studies, taken together, have led me to formulate the following working hypotheses: (i), CaSR is a robust inducer of differentiation by virtue of its ability to activate and integrate diverse growth and differentiation control signals; (ii), loss of CaSR expression enable cellular escape from CaSR control and (iii), loss of CaSR expression is an underlying mechanism of malignant transformation, progression and drug resistance in colon cancer. Previous studies showed that there are endogenous small subpopulations that do not express CaSR in colon carcinoma cell lines. These cells are highly drug resistant. Indeed, immunocytochemical analyses of CaSR showed that the expression of CaSR in both the CBS and HCT116 colon carcinoma cell lines are heterogeneous. Human colon carcinoma cell lines contain small subpopulations (10-20%) that do not express CaSR (termed CaSR null cells). In order to further test my hypotheses, the isolation and characterization of CaSR null cells are required. Here, I report on the isolation, propagation, maintenance and characterization of CaSR null cells from the CBS and HCT116 human colon carcinoma cell lines. CaSR null cells grew as three-dimensional non-adherent spherical clusters with increased propensity for anchorage independent growth, cellular proliferation and invasion of matrigels. CaSR null cells were highly resistant to fluorouracil and expressed abundant amount of thymidylate synthase and survivin. Molecular profiling showed a high level of expression of the previously reported cancer stem cell markers CD133, CD44 and Nanog in CaSR null cells. A significant increase in the expression of epithelial-mesenchymal transitional (EMT) molecules and transcription factors was also observed. These include N-cadherin, β-catenin, vimentin, fibronectin, Snail1, Snail2, Twist and FOXC2. The expression of the tumor suppressive E-cadherin and miR145, on the other hand, was greatly reduced while the expression of oncogenic micro RNAs: miR21, miR135a and miR135b was significantly up-regulated. CaSR null cells possess a myriad of cellular and molecular features that drive and sustain the malignant phenotype. I conclude that CaSR null constitutes a highly malignant and drug resistant phenotype of colon cancer. I discovered that CaSR null cells, cultured in defined human embryonic stem cell culture medium, can be induced to differentiate and acquire CaSR expression when the medium of the null cells was changed to conventional cell culture medium containing fetal bovine serum. I hypothesize that expression of CaSR can alter the phenotype of the CaSR null cells. The objectives of this study were then three folds: (i), determine if induction of CaSR expression could circumvent the molecular phenotype of the CaSR null cells; (ii), determine if CaSR was required in altering the null phenotype and (iii), determine the underlying mechanism of CaSR induction. I hypothesize that if CaSR is a strong promoter of differentiation, then without CaSR, the constraint exerted by CaSR will not be functional and pathways normally inhibited by CaSR will be activated. I found that induction of CaSR expression led to a more indolent phenotype which includes the acquisition of epithelial morphology, down-regulated expression of cancer stem cell markers, down-regulated expression of thymidylate synthase and survivin and increased sensitivity to fluorouracil. Molecular profiling also revealed that the induction of CaSR expression was linked to a down-regulated expression of EMT molecules, EMT associated transcription factors and oncogenic miRNAs with a concurrent up-regulated expression of tumor-suppressive molecules. With the exception of the cancer stem cell markers, the reversal of molecular features, upon the induction of CaSR expression, was directly linked to the expression and function of CaSR because blocking CaSR induction by shRNA circumvented such reversal. I further report that demethylation of the CaSR gene promoter underlie CaSR induction. I conclude that induction of CaSR expression in CaSR null cells resulted in a more indolent phenotype concurrent with a variety of molecular changes and that these changes (with the exception of stem cell markers) are dependent on the expression and function of CaSR. I further conclude that methylation of the CaSR gene promoter is an underlying mechanism of maintaining the CaSR null phenotype while promoter demethylation is an underlying mechanism responsible for CaSR induction. CaSR null is a phenotype of the rapidly proliferating, undifferentiated crypt stem cells at the base of colonic crypts. Differentiation of crypt stem cells toward the apex of a crypt (in the direction of the lumen), on the other hand, is tightly linked to CaSR expression. What induces CaSR expression as the crypt stem cells migrate up the crypts is unknown. I hypothesize that as the colonic crypt stem cells migrate up the crypt, they become increasingly exposed to the colonic fluid in the lumen and components in the colonic fluid can trigger the induction of CaSR expression. Both Ca2+ and vitamin D are good candidates because either Ca2+ or vitamin D can stimulate CaSR expression in the parental CBS and HCT116 human colon carcinoma cells. Certainly, Ca2+ and vitamin D are not the only components involved in regulating CaSR expression. A variety of minerals in the colonic fluid may also serve as good candidates in the induction of CaSR. Of interest is Aquamin, a calcium-rich mineralized extract from the red marine algae, Lithothamnion calcareum, which has been shown to induce differentiation in colon carcinoma cells and possess chemopreventive properties against colon polyp formation in mice fed a high fat diet. CaSR null cells cultured in defined human embryonic stem cell culture medium were used to test this hypothesis because they offer an in vitro model in determining the triggers and the underlying mechanisms of CaSR induction that may resemble that of the colonic crypt stem cells in vivo. I found that all three agonists (Ca2+, vitamin D and Aquamin) induced CaSR mRNA and protein expression and inhibited cellular proliferation in the parental cells which express a heterogeneous mixture of cells with different level of CaSR expression. These agonists also induced CaSR mRNA and protein expression and inhibited cellular proliferation in the homogeneous isolated CaSR null cells. In both cases, Aquamin was found to be most potent in this regard. Induction of CaSR expression by these agonists in the CaSR null cells resulted in demethylation of the CaSR gene promoter with a concurrent increase in CaSR promoter reporter activity. Induction of CaSR expression resulted in a down-regulated expression of tumor inducers and up-regulated expression of tumor suppressors in the CaSR null cells. Again, Aquamin was found to be most potent in this regard. Taken together, I conclude that nutrients are good candidate in the induction of CaSR and differentiation in colonic epithelia cells. Similar to CaSR, transforming growth factor β (TGFβ) is also a robust promoter of differentiation in the colonic epithelium. The expression profile of both CaSR and TGFβ in the colonic epithelium is tightly linked to differentiation. Both CaSR and TGFβ expression progressively increases as the undifferentiated crypt stem cells migrate and differentiate toward the apex of a crypt in the direction of the lumen. Similar to the loss of CaSR in cancer cells, loss of TGFβ responsiveness has long been considered an underlying mechanism of early colon carcinogenesis. I hypothesize that there is functional linkage between CaSR and TGFβ function. Human colonic epithelial CBS cells originally developed from a differentiated human colon tumor, retain CaSR expression and function, TGFβ responsiveness and TGFβ receptor expression. Thus, these cells offer an opportunity to determine the functional linkage (if any) between CaSR and TGFβ. I found that knocking down CaSR expression in the CBS cells abrogated TGFβ-mediated cellular responses and attenuated the expression of TGFβ receptors. Ca2+ or vitamin D treatment induced CaSR expression with a concurrent up-regulation of TGFβ receptor expression. Ca2+ or vitamin D, however, did not induce CaSR in CaSR knocked down cells and without CaSR, there was no up-regulation of TGFβ receptor. I conclude that TGFβ receptor expression and TGFβ mediated responses requires CaSR expression and function. In summary, my research has revealed the important role of CaSR in controlling differentiation. CaSR also function as a robust tumor suppressor. My study clearly discerns the multifarious molecular signaling cascades involved in CaSR function and that methylation and demethylation regulates CaSR expression. My work has also established the importance of CaSR in the chemoprevention of colon cancer. My thoughts in regard to future studies and the potential role that CaSR could play in the management of colon cancer are given in the perspective section of this dissertation
Assessing robustness and identifying critical infrastructure in synchromodal transport network
No full textA synchromodal transport network is a transportation technique which aims to create more efficient and sustainable transportation plans, which utilizes different modes of transport, i.e., roadways, railways, and waterways synchronously. Synchromodal transport network is a complex network with interdependence. The aim of this thesis was to analyze the robustness and identify critical infrastructure in synchromodal transport network. In order to achieve the goal of the thesis. First, the synchromodal transport network is analyzed on the basis of its transportation characteristics and network topology. The analysis of transportation characteristics helped us to define a notion of node criticality. The node criticality quantifies the effect on the robustness of a transportation system due to the perturbation of an infrastructure. Then, a relationship is established between the node criticality and topological centrality metrics in order to quickly identify critical infrastructures in the synchromodal transport network. Lastly, a systematic framework is proposed and applied to the Dutch synchromodal transport network. The results from the case study are quite insightful. First, we observe that the distribution of node criticality exhibits a power-law distribution which implies that the Dutch synchromodal transport network tends to robustness against node perturbation. Second, we observe that the performance of the dutch synchromodal transport network is quite sensitive to the perturbation in the road network. Lastly, we identify that the weighted degree centrality, eigenvector centrality shows a high correlation with node criticality thus these centrality metrics can be used to identify critical infrastructure in the synchromodal transport network.Electrical Engineerin
Breast Health Seeking Behaviors In Countries With Varying Health Coverage
No full textabstract: There is an enormous unmet need for services, education, and outreach to improve women’s breast health. Healthcare systems and insurance systems vary widely around the world, and this may play an important role in understanding variability in women’s breast health knowledge and behavior globally. The goal of this study is to determine how varying healthcare systems in three countries (Japan, Paraguay, US) affect a woman’s likelihood of seeing a physician in regard to their breasts. For example, Japan is a clear example of a region that provides universal health insurance to its citizens. The government takes responsibility in giving accessible and equitable healthcare to its entire population (Zhang & Oyama, 2016). On the other hand, a country such as Paraguay is composed of both public and private sectors. In order for citizens to gain insurance, one would have to either be formally employed or choose to pay out-of-pocket for hospital visits (“Paraguay”, 2017). A country such as the United States does not have universal health insurance. However, it does have a mix of public and private sectors, meaning there is little to no coverage for its citizens. To accommodate for this, the United States came up with the Affordable Care Act, which extends coverage to the uninsured. Although the United States might be a country that spends more on healthcare than any other nation, there are residents that still lack healthcare (De Lew, Greenberg & Kinchen, 1992). This study, then, compares women’s breast health knowledge and behavior in Japan, Paraguay, and the US. Other variables, which are also considered in this study, that might affect this include wealth level, education, having general awareness of breast cancer, having regular health checks, and having some breast education. Using statistical analysis of breast check rates of women in Japan, Paraguay, and the United States, this research found that women sampled in Asunción, Paraguay check their breasts more often than either women sampled from Scottsdale, U.S. or Osaka, Japan. It was also found that women sampled from Paraguay were more confident in detecting changes in their breast compared to women sampled from the Japan or the US. Finally, it was noted that women sampled from Japan were least likely to partake in seeing a doctor in concern of changes in their breasts compared to women sampled from the other two research locations. These findings have relevance for the implementation of advocacy and public education about breast health
A Drop in the Ocean. On Writing Histories of Water Resources Management
No full textThis text builds on the shared focus of historians and engineers to understand how particular circumstances came to be. In their endeavours, engineers regularly turn attention to the past, many times with the explicit aim to build on the past. In this chapter, it is discussed why these water histories written by engineers are vulnerable to being less correct. Using a range of scholarship on water history and shared experiences within the International Water History Association, we discuss the core of any historical scholarship: a drive to demonstrate and understand the complexity of the past. As such, this chapter wants to warn against the engineering drive to use (water) history as a guide towards the future. Instead, we propose a perspective of history as a way of reading and understanding the complex paths we have travelled until now.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.Water Resource
Single Channel Speech Enhancement: Using Wiener Filtering with Recursive Noise Estimation
No full textAbstractThis paper discusses the problem of single channel speech enhancement in stationary environments, and proposes Wiener filtering with the recursive noise estimation algorithm. The Wiener filter is a linear estimator and minimizes the mean-squared error between the original and enhanced speech. The algorithm is implemented in the frequency domain and depends on the filter transfer function from sample to sample based on the speech signal statistics; the local mean and the local variance. For the noise estimation, the recursive noise estimation approach is used. In this approach, the noise estimation is done by past and present spectral power values, using a smoothing parameter. The value of smoothing parameter is selected in between [0 1]. For the performance evaluation of the proposed speech enhancement algorithm objective evaluations with informal listening tests are conducted for the speech sentences, pronounced by male and female speakers from the NOIZEUS corpus, degraded by White as well as Pink noise types at different SNR levels. For objective measures, signal to noise ratio, segmental signal to noise ratio, and the perceptual evaluation of speech quality are used. The measures prove that the speech enhanced by proposed algorithm is more pleasant to the human ear for both noise conditions in comparison to the conventional speech enhancement method
Development And Microstructural Characterisation Of Inconel Cladding On Stainless Steel Through Microwave Irradiation
No full textImplications of SiO2 nanoparticles for in vitro biodegradation of low-density polyethylene with potential isolates of Bacillus, Pseudomonas, and their synergistic effect on Vigna mungo growth
No full textEnhancing the Abrasive Wear Performance of Heat Treated Ni Coatings through Different Cooling Strategies
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