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Reconstruction of Qualitative Gene Regulatory Networks

Thesis Info

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Author

Khalid, Mehrosh

Program

PhD

Institute

National University of Sciences & Technology

City

Islamabad

Province

Islamabad

Country

Pakistan

Thesis Completing Year

2019

Thesis Completion Status

Completed

Subject

Computer Science

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/10364/1/Mehrosh%20Khalid-SEECS-NUST.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676727820231

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Genes provide instructions for the synthesis of functional products, such as, proteins. Gene expression develops the functional products using the instructions encoded in the genes. Gene regulation controls the process of gene expression in a way that it can regulate the increase or decrease of the gene expression resulting in the synthesis of specific functional products. It also controls when or when not to express a particular gene to produce a particular protein. Collection of regulatory elements, such as, genes and their interconnections showing the gene expression levels, are visualized as a Gene Regulatory Network (GRN). GRNs act as a tool for understanding the causation relationships between the genes and proteins representing complex cellular functionalities. Computational biology has laid its main focus nowadays on the reverse engineering or reconstruction of GRNs from gene expression data to decode the complex mechanism of the cellular functionalities. These efforts have resulted in improved and more precise diagnostics and therapeutics. Microarray technology of analyzing gene expressions calculates expression of thousands of genes simultaneously under different conditions, like, control or disease conditions. It helps in identifying over-expressed genes likely to be associated with the disease. Multiple approaches to reconstruct GRNs from gene expression data, apply various techniques, such as, distance measures, correlations, mutual information algorithms, dynamic and quantitative probabilities. These approaches result in identifying symmetric and diagonal gene pair interactions. Symmetric gene pair interactions cannot be modeled as direct activation and inhibition interactions. Moreover, diagonal nature shows that a gene cannot self-regulates itself, which is also contradictory with the true nature of gene pair regulatory interactions. Compromising the true asymmetric and non-diagonal nature of the actual gene pair regulatory interactions, can lead to incomplete and inferior predictions. To our knowledge, no such complete model exists to generate GRN representing all possible network motifs between gene pairs, such as, activation, inhibition and self-regulations. The proposed approach, named as, Multivariate Covariance Network (MCNet), aims at reconstructing GRN applies multivariate co-variance analysis and Principal Component Analysis (PCA) to identify asymmetric and non-diagonal gene interactions. The GRN developed using the MCNet approach holds all the possible network motifs, representing all kinds of gene-pair regulatory interactions (i.e., positive and negative feedback loops as well as self-loops). The asymmetry is achieved by computing the distance measure of the genes with respect to the eigen values of the related genes showing variable behaviors under different conditions. PCA in the MCNet approach selects gene-pair interactions showing maximum variances in gene regulatory expressions. Asymmetric gene regulatory interactions help in identifying the controlling regulatory agents, thus, lowering the false positive rate of interacting genes by minimizing the connections between previously unlinked network components. The performance of the proposed approach, MCNet, has been evaluated using a real data set as well as three synthetic and gold standard data sets. The MCNet approach predicts the regulatory vi interactions with higher precision and accuracy as compared to some currently state-of-the-art approaches. The results of the MCNet approach using the real time-series RTX therapy data set identified self-regulatory interactions of the differentially expressed (DE) genes with 80.6% accuracy. The MCNet approach predicted the gene regulatory interactions of the time-series synthetic Arabidopsis Thaliana circadian clock data set with 90.3% accuracy. The self-regulatory interactions identified in the RTX therapy and synthetic Arabidopsis Thaliana data sets are further verified from the literature because gold standards are not available for these data sets. Gold standard DREAM-3 and DREAM-8 in silico data sets, are also used to evaluate the performance of the proposed approach, while comparing with some existing approaches. The DREAM-3 in silico E-coli gold standard data set does not contain any self-regulations, while the DREAM-8 in silico phosphoproteins gold standard data set hold self-regulations. The results demonstrate the enhanced performance of the MCNet approach for predicting self-regulations only in the DREAM-8 in silico phosphoproteins data set with 75.8% accuracy. The MCNet approach for reconstructing GRN identifies direct activation and inhibition interactions as well as self-regulatory interactions from microarray gene expression data sets. The generated GRN can constitute positive and negative feedback loops as well as self-loops to demonstrate true nature of the gene-pair regulatory interactions. In future, it is aimed to enhance the functionality of the MCNet approach by modeling the dynamics of the GRNs, such as, oscillations and bifurcations towards steady state
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۴۵۔ دروازہ

دروازہ

دہلیز پہ بیٹھی ایک بڑھیا چہرے کی جھریاں سہلا رہی تھی

اس کی دھندلائی آنکھیں بیتے دنوں پہ نوحہ کناں تھیں

جیسے یادوں کی آگ آنسوئوں سے بجھا رہی ہو

نحیف ہاتھوں میں وقت کا تحفہ تھامے

ڈھلکتے آنچل سے بے خبر نجانے کن دنیائوں میں گم تھی

اپنی صدا سے دور کئی صدائوں میں گم

دھندلی آنکھوں سے ماضی میں جھانک رہی تھی

وہ دل کش چہرے اور حسین منظر

کچی دیواریںاور کھلے در

Murabaha Financing in Pakistan: A Practical Islamic Banking Aspect

Modes of financing in Islamic banking system are generally categorized as Sharaiah based financing like Musharakah, Mudarabah and Shariah compliant financing like Murabaha, Ijarah etc. Islamic banks should have adopted and promoted Sharaiah based financial instruments but instead they have been predominantly using Sharaiah compliant modes especially Murabaha due to some valid reasons. The aim of this paper is to highlight and know the level of satisfaction of the clients, businessmen, entrepreneurs, professionals, academicians and Islamic banking experts of the prevalent structure and use of Murabaha by the Islamic banks in Pakistan.

Extraction and Evaluation of Secondary Metabolites As Green Antiotensin Converting Enzyme Ace Inhibitor.

Secondary metabolites, substantially available in the medicinal plants, have divulged their pharmacological properties and can be used in its isolated form or as integral component of the plant‟s part, to cure a variety of disorders. High blood pressure is considered as silent killer as it sneaks up in the body and may leads to serious cardiovascular disorders. Many allopathic antihypertensive medicines are presently available but these are taking their toll in the form of serious side effects. Therefore, the present study was designed for extraction and evaluation of plant‟s secondary metabolites as green Angiotensin Converting Enzyme (ACE) inhibitors for management of hypertension. In the first phase of this research, aqueous and ethanol extracts of 22 plants were initially screened as green ACE inhibitors. Among them four plants Coriandrum sativum, Amomum subulatum, Rauvolfia serpentina and Curcuma longa showed highest ACE inhibition potential. Secondary metabolites were extracted from these four medicinal plants and evaluated for ACE inhibition potential. The highest ACE inhibition potential was observed with flavonoid (81.4±0.48%) of Coriandrum sativum, tannin (77.9±0.24%) of Amomum subulatum, flavonoid (79.9±0.42%) and tannin (88.3±0.26%) of Rauvolfia serpentina and alkaloid (44.4±1.32%) of Curcuma longa. Plants are traditionally recognized for their synergic therapeutic effects, therefore, combinations of plants and their secondary metabolites were evaluated for synergistic ACE inhibition potential. The results revealed that the combination No.1 comprising of Rauvolfia serpentina and Curcuma longa (RS+CL) exhibited significant ACE inhibitory activity (65.08±0.33%) with IC50 value of 73.67μg/mL. The combination No. 13 of secondary metabolite comprising of tannins and flavonoids of Rauvolfia serpentina and alkaloids of Curcuma longa (TRS+FRS+ACL) showed highest ACE inhibition potential (69.64±0.80%) with IC50 value of 39.67μg/mL. Secondary metabolites present in combination No. 13 were further fractionated through column chromatography. Different fractions of flavonoids, tannins and alkaloids were collected, but among them only F3 fraction of flavonoids, T3 fraction of tannins of Rauvolfia serpentina and A6 fraction of alkaloids of Curcuma longa showed ACE inhibition potential. In 2nd phase of the study, characterization of five secondary metabolites fractions extracted from four selected medicinal plants and secondary metabolites present in combination No. 13 were performed by LC-ESI-MS/MS technique to find out the actual bioactive compounds responsible for ACE inhibition potential. The ACE inhibitors identified from flavonoids fraction were included pinocembrin, apigenin, pseudobaptigenin, quercetin, myricetin-3-O-glucoside, quercetin- dimethyl ether-O-glucuronide, quercetagetin, Luteolin-7-O-glycoronyl and quercetin-3-O-hexose-pentoside. Tannins fraction contained ellagic acid, megiferin gallate, prodelphinidin B4, tri galloyl glucose and geraniin as ACE inhibitors. Pyrazolo[1,5-a]pyridine,3,3a,4,7-tetrahydro-3,3-dimethyl;(3aS) and 2-(2‟-methyl-1‟-propyl)-4, 6-dimethyl-7-hydroxyquinoline were identified as alkaloidal ACE inhibitors. In the 3rd phase of this study, the combination No. 1 of plant (RS+CL) and combination No. 13 of secondary metabolites (TRS+FRS+ACL) were investigated for in vivo antihypertensive potential through spontaneous induction of hypertension by two kidney one clip (2K1C) renal artery ligation method. In vivo trial revealed that the combination No. 13 of secondary metabolites showed comparatively better antihypertensive potential as compared to the combination No.1 of whole plants. It is pertinent to mention that the antihypertensive potential of the isolated secondary metabolites was better even than the standard drug (Captopril) which was used as reference.