Biology subjects

Ismail, A.

Publications and source records attributed to Ismail, A..

24 records · Page 2Linked to original sources

bioRxiv2020

Three-Dimensional (3D) Fibronectin Nano-Array Presented on Fibrin Matrix Accelerates Mice Skin Wound Healing

Plasma fibrinogen (F1) and fibronectin (pFN) polymerize to form a fibrin clot that is both a hemostatic and provisional matrix for wound healing. About 90% of plasma F1 has a homodimeric pair of {gamma} chains ({gamma}{gamma}F1) and 10% has a heterodimeric pair of {gamma} and more acidic {gamma} chains ({gamma}{gamma}F1). We have synthesized a novel fibrin matrix exclusively from a 1:1 (molar ratio) complex of {gamma}{gamma}F1 and pFN in the presence of highly active thrombin and recombinant Factor XIII (rFXIIIa). In this matrix, the fibrin nanofibers were wrapped with periodic 200-300 nm wide pFN nanobands (termed {gamma}{gamma}F1:pFN fibrin). In contrast, fibrin made from 1:1 mixture of {gamma}{gamma}F1 and pFN formed a sporadic distribution of "pFN droplets" (termed {gamma}{gamma}F1 +pFN fibrin). The {gamma}{gamma}F1:pFN fibrin enhanced the adhesion of primary human umbilical vein endothelium cells (HUVECs) relative to the {gamma}{gamma}F1+FN fibrin. Three dimensional (3D) culturing showed that the {gamma}{gamma}F1:pFN complex fibrin matrix enhanced the proliferation of both HUVECs and primary human fibroblasts. HUVECs in the 3D {gamma}{gamma}F1:pFN fibrin exhibited a starkly enhanced vascular morphogenesis while an apoptotic growth profile was observed in the {gamma}{gamma}F1 +pFN fibrin. Relative to {gamma}{gamma}F1 +pFN fibrin, mouse dermal wounds that were sealed by {gamma}{gamma}F1:pFN fibrin exhibited accelerated and enhanced healing. This study suggests that a 3D pFN nano-array presented on a fibrin matrix can promote wound healing.

bioengineering↗

bioRxiv2019

JARID2 facilitates transcriptional reprogramming in glioblastoma in response to standard treatment

BackgroundGlioblastoma (GBM) is a fatal and incurable brain cancer with a dismal prognosis. In order to impact on this disease, we need to understand how infiltrating, non resectable tumour cells resist chemoradiation and facilitate disease recurrence. To this end, we generated or acquired bulk tumour RNA sequencing data from 45 paired primary and locally recurrent GBM tumours (split into original and validation cohorts) from patients that received standard treatment. We also generated DNA methylation profiles for 9 pairs and sequenced RNA from single cells isolated from a patient derived GBM spheroid model at different timepoints following in vitro chemoradiation.\n\nResultsWe have identified a set of genes with Jumonji and AT-Rich Interacting Domain 2 (JARID2) binding sites in their promoters that are universally dysregulated in post-standard treatment recurrent GBMs compared to the primary tumour. The direction of dysregulation is patient-dependent and not associated with differential promoter DNA methylation. Our in vitro experiments suggest that this dysregulation occurs dynamically following treatment as opposed to resulting from selection of cells with specific expression profiles.\n\nConclusionJARID2 is an accessory protein to a chromatin remodeling complex, responsible for histone modifications observed during cell state transitions in both normal brain and GBM. We propose that JARID2 facilitates GBM recurrence following treatment by indirect transcriptional reprogramming of surviving cells in whichever manner is needed to reproduce the phenotypic heterogeneity required for tumour regrowth in vivo. The mechanism of this reprogramming may present a therapeutic vulnerability for more effective treatment of GBM.

cancer biology↗

bioRxiv2019

Economic Burden of Hypoglycaemia among Type II Diabetes Mellitus Patients in Malaysia.

ObjectiveThe main aim of this study is to identify the direct cost and economic burden of hypoglycaemia among patients with Type II diabetes mellitus in Malaysia.\n\nMethodsThe incurred cost for hypoglycaemia among patients admitted to University Kebangsaan Malaysia Medical Centre (UKMMC) was explored from a cross sectional study. 20-79 year patients discharged between Jan 2010 to Sept 2015 and having an ICD-10 code of hypoglycaemia as a primary diagnosis in the casemix database were included in the study. Costing analysis from the perspective of health providers was completed using step-down approach. Data related to hospital cost were collected using hospital-costing template, based on three levels of cost centres. The costing data from UKMMC was used to estimate the national burden of hypoglycaemia among type II diabetics for the whole country.\n\nResultsOf 244 diabetes patients admitted primarily for hypoglycaemia to UKMMC, 52% were female and 88% were over 50 years old. The cost increased with severity. Managing a hypoglycaemic case requires 5 days (median) of inpatient stay with a range of 2-26 days; and costs RM 9,083 (USD 2,323). 30% of the cost came from the ward services cost (final cost centre), 16% of the cost came from ICU services and 15% from pharmacy services(secondarylevel cost centres). Based on the prevalence of hypoglycaemia-related admissions of 3.2%, the total cost of care for hypoglycaemia among adult diabetes in Malaysia is estimated to be RM 117.4 (USD 30.0) million, which is translated as 0.5% of Ministry of Health budget.\n\nConclusionHypoglycaemia imposes substantial economic impact even without the direct and indirect cost incurred by patients and other cost of complications. Proper diabetic care and health education is needed in diabetic management to reduce episodes of hypoglycaemia.

scientific communication and education↗

bioRxiv2018

A revisit to a low-cost method for the isolation of microsatellite markers: the case of the endangered Malayan tapir (Tapirus indicus)

There are many approaches to develop microsatellite markers. We revisited an easy and rapid Polymerase Chain Reaction (PCR)-cloning-sequencing method to design microsatellite markers for Tapirus indicus. Using six random amplified microsatellite (RAM) markers, this study had rapidly generated 45 unique genomic sequences containing microsatellites. After screening 15 terminal and seven intermediate microsatellite loci, we shortlisted five and seven which were amplified either by single- or multiplex PCR using the economical three-primer PCR method. Genotyping attempts were made with ten Tapirus indicus individuals using three of the terminal microsatellite loci and all seven intermediate loci. However, none of the terminal microsatellite loci were considered useful for population genotyping studies, while the seven intermediate loci showed good amplification but were monomorphic in the ten samples. Despite successful detection of amplified loci, we would like to highlight that, researchers who are interested in this alternative method for isolation of microsatellite loci to be cautious and be aware of the limitations and downfalls reported herein that could render these loci unsuitable for population genotyping.

genetics↗

bioRxiv2018

Selective auxin agonists induce specific AUX/IAA protein degradation to modulate plant development

Auxin phytohormones control most aspects of plant development through a complex and interconnected signaling network. In the presence of auxin, AUXIN/INDOLE-3-ACETIC ACID (AUX/IAA) transcriptional repressors are targeted for degradation by the SKP1-CULLIN1-F-BOX (SCF) ubiquitin-protein ligases containing TRANSPORT INHIBITOR RESISTANT 1/AUXIN SIGNALING F-BOX (TIR1/AFB). CULLIN1-neddylation is required for SCFTIR1/AFB functionality as exemplified by mutants deficient in the NEDD8-activating enzyme subunit AUXIN-RESISTANT 1 (AXR1). Here, we report a chemical biology screen that identifies small molecules requiring AXR1 to modulate plant development. We selected four molecules of interest, RubNeddin1 to 4 (RN1 to 4), among which RN3 and RN4 trigger selective auxin responses at transcriptional, biochemical and morphological levels. This selective activity is explained by their ability to promote the interaction between TIR1 and a specific subset of AUX/IAA proteins, stimulating the degradation of particular AUX/IAA combinations. Finally, via a genetic screen using RN4, we revealed that the chromatin remodeling ATPase BRAHMA is implicated in auxin-mediated apical hook development. These results demonstrate the power of selective auxin agonists to dissect auxin perception for plant developmental functions.

plant biology↗

bioRxiv2018

A thermo-responsive plasmid for biconditional protein expression

Here we develop a temperature sensitive expression vector that allows the selective production of distinct proteins over different temperature ranges with a single plasmid. We use the E. coli cold shock translational control system (the cspA 5Untranslated Transcribed Region - UTR) to drive the expression of a desired protein below a certain temperature threshold, and the lambda phage pL/cI857 transcriptional repressor system to drive the expression of a different protein above a certain temperature threshold. In this developmental work we use the chromogenic reporter proteins amilCP (blue chromoprotein) and monomeric red fluorescent protein (mRFP) to assess the function of the thermo-sensitive regulatory sequences over the desired temperature ranges. Our results show temperature dependent response of the cold shock regulatory sequence. However, our sequence design for the heat shock regulatory sequence did not give the intended result. The integration of these two temperature sensitive elements into a single plasmid awaits the re-design of the heat shock sequence.

synthetic biology↗