Repository@USM
Welcome to closed access digital repository of Universiti Sains Malaysia (USM).
This repository contains multiple types of scholarly materials, especially USM theses and exam papers.
To access the full text, please log in with your USM email account.
Research outputs
6003
Projects
0
People
0
Recent Additions
- PublicationExpression of sars-cov-2 k51a/s54a nsp7 protein in escherichia coli c41(de3) and escherichia coli bl21(de3)(2025-01)Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) relies on the RNA-dependent RNA polymerase (RdRp) complex, comprising NSP7, NSP8, and NSP12, for replication and transcription. Mutations in NSP7, such as K51A and S54A, disrupt interactions with NSP8 and NSP12, impairing polymerase activity and structural integrity. These mutations offer insights into the development of antiviral therapeutics targeting the RdRp complex. This study aimed to express the mutant K51A/S54A NSP7 protein in Escherichia coli C41(DE3) and BL21(DE3) using the pET-15(b) vector. The methodologies included the preparation of the pET-15(b)-mutant NSP7 plasmid construct, transformation of the plasmid into E. coli, and optimization of protein expression. Parameters such as IPTG concentrations (0–1.0 mM) and different host strains were systematically optimized. The mutant NSP7 (K51A/S54A) protein was successfully expressed in both E. coli strains, with SDS-PAGE revealing distinct bands at the expected molecular weight. Optimal protein expression was achieved at 0.5 mM IPTG concentration. The findings highlighted differences in expression efficiency between E. coli C41(DE3) and E. coli BL21(DE3), with E. coli BL21(DE3) yielding higher expression levels. This research contributes to the understanding of SARS-CoV-2 replication by providing optimized conditions for expressing K51A/S54A NSP7 protein, enabling functional and structural studies. The findings offer a foundation for exploring NSP7 mutations as therapeutic targets and demonstrate the utility of bacterial systems for producing viral proteins in high yield, potentially accelerating antiviral drug discovery
- PublicationEvaluation of phytochemicals, antioxidant & antimicrobial properties of cinnamomum verum extracts(2025-01)Traditional medicine has long relied on plant-based remedies to address various health issues, with cinnamon bark being widely recognized for its therapeutic properties. This study aims to investigate the phytochemical, antioxidant and antimicrobial properties of cinnamon extracts, emphasizing its potential as a natural therapeutic agent. Aqueous extract of C. verum (AECV) and ethanolic extract of C. verum (EECV) were analyzed for their bioactive compounds, revealing the presence of alkaloids, phenols, flavonoids, tannins, glycosides, and terpenoids, while saponins were detected only in AECV. Antioxidant activity was assessed using DPPH radical scavenging and total phenolic content (TPC) assays. AECV demonstrated higher antioxidant potential (IC50 = 0.233 mg/mL) than EECV (IC50 = 0.418 mg/mL), although both exhibited lower activity compared to ascorbic acid (AA) (IC50 = 0.00673 mg/mL). TPC analysis revealed that EECV (0.1001 [0.236] mg GAE/g) showed higher phenolic content than AECV (0.0227 [0.036] mg GAE/g), indicating ethanol's effectiveness in extracting phenolics. Antimicrobial activity against S. aureus and E. coli was evaluated using minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays, where AECV demonstrated limited antibacterial activity against S. aureus (MIC = 20 mg/mL), while EECV exhibited no significant effects. Neither extract inhibited E. coli, likely due to insufficient extract concentrations. These findings indicate that cinnamon bark showed potential as a natural source of antioxidant, while further investigation is needed to explore its antimicrobial potential
- PublicationChanges in ph of digestive vacuole of plasmodium falciparum treated with pipecolisporin and analogue ii peptide(2025-01)Malaria is a severe and fatal disease caused by Plasmodium spp. and remains one of the leading global causes of morbidity and mortality. The emergence of drug-resistant P. falciparum in various countries has necessitated an effort to discover new antimalarial drugs targeting different pathways. Research on the potential of pipecolisporin and analogue II as an antimalarial agent has remained limited. Therefore, this study aimed to fill this knowledge gap by investigating the antimalarial activity of pipecolisporin and analogue II peptides. The antimalarial potential of pipecolisporin and analogue II against the chloroquine-sensitive strain (3D7) of P. falciparum was assessed based on the calculation of parasitaemia using Giemsa stained-blood smears. The pipecolisporin and analogue II exhibited highly active antimalarial activity with an IC50 value of 0.4770 and 0.1170 μM, respectively. A further investigation focused on the effect of pipecolisporin and analogue II towards the pH of the mid trophozoite stage parasite’s digestive vacuole, employing a flow cytometry-based technique with fluorescein isothiocyanate-dextran (FITC-dextran) as a pH ratiometric probe. The results revealed no increase in pH following pipecolisporin and analogue II treatment. Suggests that pipecolisporin and analogue II might not have the mechanism to alter the digestive vacuole’s pH through the inhibition of V-type H+-ATPase that regulates the acidification of the vacuole. Overall, this study provides crucial evidence of pipecolisporin and analogue II capability as a promising antimalarial candidate
- PublicationPolyvinylidene fluoride/calcium carbonate membranes with the nonwetted and wetted surface for dual-phase separation(2024-09)Dual-phase separation using membranes involves the permeation of target compounds between gas-liquid and liquid-liquid phases. However, the permeation can be restricted by surface wetting important. In this work, poly(vinylidene fluoride) (PVDF) membranes with switchable surface wetting were developed through nanoparticle incorporation and 3D-imprinting, followed by drying or wetting after phase inversion. In order to achieve the nanoroughness, low cost and biocompatible calcium carbonate (CaCO3) nanoparticles were introduced into PVDF dope solution. A micro-roughness was imprinted on the membrane by phase inversion in a water bath after casting on a woven support. For nanotemplating, the nanoparticles were premodified using stearic acid to reduce surface energy or removed using ethylenediaminetetraacetic acid. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to observe the presence of CaCO3 nanoparticles. As a result of the addition of CaCO3 and stearic acid-modified CaCO3 (SA-CaCO3), the membrane pore size and porosity were significantly improved due to demixing during phase inversion. Removing CaCO3 nanoparticles using ethylenediaminetetraacetic acid enlarged the pore size greatly. PVDF/CaCO3 and PVDF/SA- CaCO3 membranes attained superhydrophobic surface after drying. Working as the membrane gas contactor, the PVDF membrane incorporated with SA-CaCO3 reached a high CO2 permeation flux of 1.86 ±0.05×10-2 mol m-2 s-1 and slight changes in surface hydrophobicity after 50 h of being immersed in amine solution. On the other hand, the hydrophobic PVDF and PVDF/SA-CaCO3 membranes developed in this work were rinsed with absolute ethanol and immersed in distilled water to attain a wetted surface. The non-wetted and wetted membranes were then tested in the separation of oil in water (O/W) and water in oil emulsion (W/O), respectively. A dead-end filtration setup was used to examine their separation efficiency for the liquid-liquid phase under the operating pressure of 0.2 bar (O/W) or 1 bar (W/O). The oil (O/W) could be separated effectively without significant fouling due to the formation of an underwater oleophobic surface. However, the removal of water (W/O) was considerably inefficient slow due to the large pore size.
- PublicationPerformance characterization of bag-valve-mask (BVM) compression using machine learning(2024-02)Medical staff face issues when ventilating patients manually using the Bag-Valve-Mask (BVM) for long periods to resuscitate patients unable to breathe properly on their own. As for ICU mechanical ventilators in hospitals, medical specialists must check on patients frequently and adjust settings manually. Currently, there are portable ventilators available in the market that aid in supplying oxygen to patients, however the usage of ML is rare, and they do not take into account various variables which are deemed important in patient recovery. In this research, the BVM was used to perform ventilation using manual and automated methods, after which machine learning (ML) study was done. The first objective was to predict the average tidal volume using artificial neural network (ANN) and boosted decision tree regression algorithms. The R2 value obtained from manual ventilation using ANN was 0.738861, whereas the boosted decision tree model scored 0.600049. Thus, ANN was used on the automated ventilation system to compare its performance with the manual, where an R2 value of 0.978604 was obtained after removing unwanted features. When compared with the manual model, a 32% increase in R2 was obtained. K-fold cross validation was carried out to test the manual and automated models in a bigger data space, where the standard deviation of the automated model was significantly lower, indicating lower variability within its dataset. The outcome of the study suggests that the automated system predicts the experiment data better than the manual system when utilizing ANN. Another objective of this research included conducting ML study using data collected from an ICU mechanical ventilator to provide a setting recommendation for a particular patient using linear and Poisson regression, where linear regression scored a R2 value of 0.936, whereas the Poisson model scored 0.836 when tested on tidal volume (TV) setting. Thus, linear regression was used to perform ML on the TV setting, fraction of inspired oxygen (FiO2) setting, and positive end-expiratory pressure (PEEP) setting, where TV setting scored the highest R2 values overall. To validate the TV setting formula obtained through Microsoft (MS) Azure, three experiments were conducted using a ventilator prototype on an artificial test lung for validation. The experiments yielded error results ranging from 53% to 79%, indicating that the TV setting values obtained from the prototype were incomparable to mechanical ventilator data. Extensive research is needed to compare the results between BVM ventilators and ICU mechanical ventilators.
Most viewed
- PublicationCharacterisation And Formulation Of Topical Methyl Salicylate Patches: Effect Of Solvents On Adhesion And Drug Permeation(2023-01)Topical methyl salicylate (MS) patch is popular for pain management. The skin permeation profile of MS is important for formulation design but limited studies were conducted. This project aims to investigate the effect of solvents on the characteristics of patches, drug release and permeation of MS. In this project, suitable solvents were first selected for the patch formulation. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy was utilised to scan the stratum corneum (SC) sheets treated with solvents and MS. Next, in vitro permeation studies were carried out with 10%v/v of MS in solvents. After that, patches containing 5%w/w of solvents and/or 10%w/w of MS were prepared with Durabond PC 1879A (8%w/w), Nikasol TS-620 (7%w/w), carboxymethyl cellulose (3.5%w/w) and polyvinyl pyrrolidone (3%w/w). Next, the patches formed were subjected to physiochemical characterisation tests, including ATR-FTIR spectroscopy, tackiness test using stainless-steel probe, peel strength test with porcine ear skin, swelling test, in vitro drug release and skin permeation studies. In in vitro permeation studies, MS in propylene glycol (PG) in drug solution displayed the highest skin permeation of MS and followed by Plurol® oleique (PLU), Labrasol® (LA), Transcutol® (TRC), Maisine® (MAI) and isopropyl myristate (IPM) at 24 h.
- ItemORAL BIOA V AILABILITY ENHANCEMENT OF POORLY SOLUBLE AND POORLY PERMEABLE DRUGS USING SELF-MICROEMULSIFYING DRUG DELIVERY SYSTEMS AND THE EFFECT OF PIPERINE(2010-01)There are approximately 40% of new drug molecules discovered and some drug molecules that are available in the market, having poor bioavailability due to poor solubility and/or poor permeability. The present study aimed at formulating a selfmicroemulsifying drug delivery system (SMEDDS) using two BCS class IV drugs, namely sulpiride and norfloxacin. Sulpiride is a P-gp substrate and norfloxacin is a substrate of MRP2, BCRP and an unknown efflux pump. From the solubility studies of drugs in various oils, surfactants and co-surfactants, oleic acid, Tween 80 and propylene glycol were chosen to prepare SMEDDS formulations. Two formulations were chosen for further study based on droplet size and solubility. The first formulation consisted of 4.76% w/w of oleic acid, 63.49% w/w of Tween 80 and 31.7 5% w/w of propylene glycol, with a mean droplet diameter of 9.27 nrn and drug solubility of 22 mg/1000 mg for sulpiride, 9.57 nrn and 17.33 mg/1000 mg for norfloxacin respectively. The other formulation consisted of 17.71% w/w of oleic acid, 55.14% w/w of Tween 80 and 27.15% w/w ofpropylene glycol, with a mean droplet diameter of 85 nrn and drug solubility of 32 mg/1 000 mg for sulpiride, 92 nrn and 27.53 mg/1000 mg for norfloxacin. !socratic HPLC- fluorescence methods were developed and validated for the determination of sulpiride and norfloxacin in rat intestinal perfusates and rabbit plasma separately. The in situ permeability experiment was performed on three intestinal segments, duodenum, jejunum and ileum in rats using single-pass perfusion technique. The SMEDDS formulation and micellar solution exhibited significant increase in the effective permeability XXXIX coefficient of the drug across all the three intestinal segments compared with drug solution for the two drugs. There was no significant difference in the effective permeability coefficients values between SMEDDS formulation and micellar solution for both drugs. When the effect of droplet sizes on jejunum permeability was studied, it was found that there was no significant difference in permeability coefficients with droplet sizes of less than 100 nm. From the in vivo bioavailability study performed in rabbits, it was found that there was a significant decrease in the T max and significant increase in the Cmax and AUC of the SMEDDS formulations when compared with Dogmatil®/Norfloxin® respectively. On the other hand, the rate and extent of absorption of sulpiride/norfloxacin were not significantly affected, when the droplet sizes of less than 100 nm were compared. When the effect of dietary spice piperine on the oral bioavailability of sulpiride/norfloxacin suspension and SMEDDS formulations was evaluated, it was found that concomitant administration of both the drugs with piperine in suspension and SMEDDS formulations significantly enhanced the oral bioavailability of these two drugs. Concomitant administration of piperine with SMEDDS formulation further increased the bioavailability of the drugs. Hence, SMEDDS can be used to increase the bioavailability of poorly soluble and poorly permeable drugs.
- ItemPENGHASILAN SEBATIAN AKTIF BERSIFAT ANTIBIOTIK DARIP ADA BAKTERIA MARIN PSEUDOMONAS DOUDOROFFI ABK37-MM(2003-07)A total of 450 bacterial and 7 fungal isolates were obtained from seawater, marine mud, l:· ~beach sand, floating material and marine macroorganisms collected from 11 sampling F sites around the Penang Island. These marine microorganisms isolates were screened for ·the production of antimicrobially active compound. From 450 bacterial isolates, 71.1% . were pigmented and sample from marine mud produced the highest marine bacterial isolates by 55.6% compared to other samples. Screening for the production of antimicrobial active compound from these bacterial isolates was performed by streaking and submerged culture fermentation techniques using yeast extract medium with half strength artificial seawater produced 3.3% and 47.1% positive isolates respectively, with various strength of antimicrobial activities. From these 47.1% marine bacterial isolates, sample from marine mud and yellow or yellowish pigmented isolates produced the highest potential isolates by 73.6% and 66.0%, respectively. Of the 47.1%, 87.3% isolates produced antibacterial compound, 19.3% isolates produced antifungal compound and 6.1% isolates produced antiyeast compound. Despite this, only 1.9% marine bacterial isolates showed antimicrobial activities against all the 8 test microorganisms. One potential marine bacterial isolate which produced the highest antibiotically active compound was chosen for the optimization of medium and cultural conditions in a shake XX!l nask system and was then identified as Pseudomonas duodoroffi ABK37-MM. The optimized medium for the production of antibiotically active compound against the test bacteria, Staphylococcus aureus was 1/8 diluted yeast extract medium ~~th half strength artificial seawater. The optimized medium compositions (%; w/v) were 0.06 maltose, . 0.06 yeast ext-act, 0.145 malt extract and 0.4 L-histidine. The optimized artificial ,. seawater compositions (%; w/v) were 1.8 NaCl , 0.5 MgCb.6H20, 0.1 CaCb,2H20, 0.1 r,KCI, 0.1 KBr, 0.2 Na2S04 and 0.05 NaHC03. The optimized cultural conditions for the ·production of antibiotically active compound were at an initial medium pH of 7.4, agitation rate of 140 rpm, incubation at room temperature (30±2°C), inoculum size of 6% and the volume of medium to the volume of flask ratio at 0.5. The production of antibiotically active compound increased by 37.0% with 14.3% faster than before optimization in a shake flask system .. Medium compositions, buffer concentration and a few physical parameters were reoptimized in the tubular air lift fermenter. The optimized medium (%; w/v) were 0.08 maltose, 0.08 yeast extract, 0.145 malt extract and 0.4 Lhistidine with 0.1 NaHC03. The optimized physical parameters were 1.5 vvm rate of aeration, inoculum size of 8% and the volume of medium to the volume of fermenter ratio of 0.75. Optimization at the fermenter level increased the production of antibiotically active compound by 26.0% at the same production time after optimization at the shake flask level, that was at 144 hours of cultivation. In general, there was an increase of about 72.6% in the production of antibiotically compound after optimization at a fermenter level compared to shake flask system. XX Ill Partial purification of the antibiotically active compound with sephadex G-1 00 gel filtration chromatography produced 9.2 folds of purity with specific antibiotically active compound of 1148.2 U/mg protein. Determination of molecular weigh!_ was done using SDS-PAGE and was estimated about 39 kD compared to known low molecular weight protein. Determination of protein compound and reducing sugar in the compound were 4.9 mg/ml and 0.02 mg/ml, respectively. The antibiotically active compound was found stable at and below of room temperature (30±2°C) and was fully deactivated at the temperature of 40°C. This compound was also found stable at pH range of 6 to 8 and fully deactivated by proteolytic enzyme suggesting that the major part of the compound was protein or protein moiety. TEM studies on the effects of the antibacterial compound on the test bacterial cell, Staphylococcus aureus revealed a chain reaction that occurred at the cell wall and cell membrane leading to cell lysis compared to untreated cell. The frequency and magnitude of the cell wall and cell membrane bleb bing and fragmentation of the test bacterial cell increased with the prolonged of exposure time to antibacterial compound, and it seems to produced pores in the bilayer cell wall leading to cell lysis.
- ItemEnhanced Image Processing Techniques Based On Technical Challenges Of Mammogram Image Characteristics(Universiti Sains Malaysia, 2010-04)Breast cancer is the leading type of cancer in Malaysia. More than 30% of total cancer case reported among women in Malaysia is made up of breast cancer. At the moment, one of the best known techniques used for breast cancer detection is mammography. Unfortunately, the image produced through mammography is normally noisy and low in contrast making detection of early signs of breast cancer (i.e. microcalcification and mass) difficult. Therefore, a lot of studies have been conducted to develop image processing techniques which would help in the detection of these early signs. However, most of these techniques were developed without a thorough study upon the mammogram image technical characteristics. Hence, an image which has been enhanced from one aspect may end up worst from another aspect. In this study, new image processing techniques have been developed based on findings which have been gathered from characterization of mammogram images. The characterization process covered the analysis of grey level distribution, noise, edge and texture. Detailed understanding of these characteristics, provide a solid basis for the development of new image processing techniques in this study. The new techniques brought forth through this study include contrast enhancement (i.e. Moving Contrast Sweep), noise suppression (i.e. Mean Approximation Adaptive Wiener Filter) and segmentation algorithm (i.e. Mean Median Crossing Segmentation). In addition to that, a new edge detection algorithm (i.e. Delta Variance Edge Detection) has also been developed to assist in microcalcification detection. Furthermore, a new classification system which is based on texture characteristic has also been developed for mass detection. Based on the analysis, it has been found that the Mean Approximation Adaptive Wiener Filter and Delta Variance Edge Detection techniques perform better than their predecessor. The performance of Mean Median Crossing Segmentation and Moving Contrast Sweep techniques is equivalent to existing techniques but they can be implemented through a more practical approach. The mass detection technique through statistical texture analysis demonstrates a lot of potential but still has room for improvement. It is hoped that, the new image processing techniques developed through solid understanding of mammogram image characteristic in this study could provide a strong foundation for the development of medical imaging applications in the future.
- ItemThe Sigficance of spatial factors in influencing the price of heritage properties in George Town, Penang.(2010)The aim of this research is to determine the significance of selected spatial factors and the influence of these spatial factors on heritage property prices in George Town 1. Spatial factors related to location, neighbourhood ·and local amenities such as transportation points, highway, shopping centre and school are tested in this research. Hedonic regression analysis is used to study the relationship between spatial factors and heritage property price in George Town 1. A total of 231 heritage property transaction records from year 1998 to 2004 are used in this analysis. The empirical result shows that spatial factor has significant influence on heritage property prices. 'Ferry route', 'shopping centre' and 'primary and secondary school' are three significant factors influencing heritage property prices in George Town 1. To further verify the significance of the above spatial factors, a spatial autocorrelation analysis is used for the second test. The analysis result indicates that property prices in George Town 1 are positive spatial autocorrelated. The positive spatial autocorrelated transaction prices in George Town reflect that property prices in George Town tend to depend on its neighbour. A geo-statistical method called Kriging is then used to verify the dependency of heritage property prices on its neighbours. A comparison between the predicted prices obtained from the Kriging map with actual transaction prices found that the predicted prices are reasonably close to the actual prices. As the Kriging method uses neighbouring properties prices to predict prices, the findings indicate that spatial factors especially neighbourhood has an influence on heritage property prices in George Town.