Pusat Pengajian Sains Perubatan - Tesis
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- PublicationAnti-diabetic and anti-lethargic effects of stichopus horrens extract in type 2 diabetes-induced sprague dawley male rats(2025-01)Vixuan, EngDiabetes mellitus is a chronic metabolic disorder, that is attributed to either insufficient insulin production by the pancreas or impaired response of body cells to insulin. Present medication like metformin has brought significant therapeutic effects in treating this disease but the side effects prompt the researchers to explore other alternative treatments especially natural products. This study aimed to investigate the potential of different sea cucumber samples of Stichopus horrens, differentiated by extraction methods, in reducing fasting blood glucose level, minimising fatigue condition, and restoring structure and function in organs of diabetic type 2-induced rats. Two extraction methods were utilised in this study, which are hydrolysis and high-pressure processing (HPP). The first extract of sea cucumber was subjected to hydrolysis only, while the second extract was exposed to HPP only. The last extract of sea cucumber was subjected to both hydrolysis and HPP. In the in-vitro assay, human umbilical vein endothelial cells (HUVECs) were exposed to three Stichopus horrens body wall samples, and a positive control, metformin with concentrations ranging from 6.25 to 4000 µg/mL in MTT assay to obtain starting dosage of treatments for animal study. The in-vivo study involved Sprague Dawley (SD) rats, which included the induction of high fat diet for five weeks, 110 mg/kg of nicotinamide injection, followed by 55 mg/kg of streptozotocin (STZ) into creating Type 2 diabetes mellitus (T2DM) rat model. Rats were randomly grouped into six groups; normal control (n=3), diabetic control (n=3), metformin-treated group (n=3), sea cucumber extract (hydrolysis only) (n=3), sea cucumber extract (HPP only) (n=3), and sea cucumber extract (HPP and hydrolysis) (n=4). The findings displayed a decreasing trend in cell viability with increasing sea cucumber concentration with ICS0 values of 3.771 ± 0.152 µg/mL in sea cucumber extract (hydrolysis only), 3.783 ± 0.063 µg/mL in sea cucumber extract (HPP only), and 4.006 ± 0.054 µg/mL in sea cucumber extract (HPP and hydrolysis) while metformin depicted an increasing trend of cell viability with ECS0 value of 4.931 ± 4.044 µg/mL. As a result, the starting dosage for animal study pertaining to different treatments is 150 mg/kg each. The findings depicted decreasing trend of blood glucose level after four weeks of treatments with 150 mg/kg sea cucumber samples and increased exercise tolerance in sea cucumber extract (HPP and hydrolysis) group with 150 mg/kg. Apart from that, sea cucumbers exhibited mild restoration in histological changes of liver, kidney, and pancreas. The short treatment duration of sea cucumber on diabetic rats might prove that sea cucumber is a promising candidate for the development of novel product in the future.
- PublicationEvaluation of the toxicity and antibacterial effects of plant essential oils against bacterial-contaminated tomatoes and lettuce(2025-01)Soosay, Kian SedrickPlant essential oils (EOs) can be used as natural preservatives to replace synthetic or artificial food preservatives. Some studies have examined the antimicrobial activity of vaporized EOs in treating bacterial-contaminated food. This study aimed to evaluate the toxicity and antibacterial effects of three plant EOs which include lemongrass EO (LEO), clove EO (CLEO) and cinnamon EO (CNEO) against bacterial-contaminated tomatoes and lettuce. The plant EO (LEO, CLEO and CNEO) were screened for their toxicities against Artemia salina by using the brine shrimp lethality test (BSLT). The antibacterial activity screening was determined by measuring Bacillus cereus growth inhibition on nutrient agar (NA) after being exposed to EO vapors at serial concentrations ranging from 0.38% v/v to 100% v/v. Subsequently, the least toxic and most potent EO was selected for the treatment of B. cereus-inoculated tomato and lettuce at cold (4°C) and room temperatures. Optical density (OD) readings were taken for each sample on the 1st, 3rd, and 7th day of treatment to measure the bacterial growth. LEO, CLEO, and CNEO showed no toxicity based on Clarkson and Meyer classification with LC50 values above 10000 ppm. LEO vapors showed lesser toxicity with the highest LC50 value of 122700 ppm and an inhibitory effect of more than 50% at 6.25% v/v concentration. B. cereus-contaminated tomato and lettuce treated with 6.25% v/v LEO vapor recorded lower OD readings of bacterial growth than those of untreated samples, particularly at room temperature within 7 days of incubation. This study suggests the potential of LEO as a safer and more effective natural food preservative, but further investigations are needed to examine if it can be used as an alternative preservative for foods at room temperature
- PublicationEnhancing in-house plasmid dna extraction using customized glass fiber membrane(2025)Jamel, Jazmi AimanPlasmid DNA extraction and purification from bacterial cells are the foundations of many biotechnological processes. The extracted plasmid can be used for a variety of purposes, including genetic research, forensic analysis, and medical diagnosis. In-house extraction kits that are more cost effective and can produce comparable results to the commercial ones are still being pursue by many researchers. In this study we aimed to develop an in-house glass fiber membrane based plasmid extraction kit and compare its yield and purity with commercial kit. The commercial reference kits used in this study will be the Qiagen plasmid extraction kit. The in-house columns with different pore sizes (0.22 μm, 0.45 μm, and 0.80 μm) and number of membrane layers (1, 2 and 6 layers) were self-assembled. The membrane pore size of 0.80 μm yield the highest DNA concentration. the column assembled with 2 layers of GF-0.80 membrane produced highest DNA yield during DNA extraction. The final optimized in-house glass fiber membrane method showed comparable yield and purity (P>0.05) results to the commercial Qiagen plamid DNA extraction kits
- PublicationDetection of synovial fluid-derived exosomes internalization by thp-1 cells(2025-01)Faizal, Hanina SofeaExosomes are small vesicles involved in intercellular communication, carrying bioactive molecules that influence immune responses and inflammation. Synovial fluid-derived exosomes have garnered attention for their potential roles in joint diseases like osteoarthritis and rheumatoid arthritis. Despite the growing interest in synovial fluidderived exosomes and their potential role in immune modulation and joint diseases, there is limited understanding of how these exosomes are internalized by immune cells, particularly monocytes, which this study aims to address by examining the internalization process in a human monocytic cell line (THP-1 cells). This study explores the internalization of these exosomes by THP-1 cells to understand their impact on immune modulation. DAPI-labelled THP-1 cells were cultured with PKH67-labelled synovial fluid-derived exosomes, and their interactions were observed using fluorescence microscopy. The uptake was analysed at two incubation times (24 and 48 hours) and cellto- exosome ratios (1:10, 1:20, and 1:40) using ImageJ software. Flow cytometry confirmed CD14 expression on THP-1 cells. Results showed significant exosome internalization, with the cell-to-exosome ratio being the key factor affecting uptake, while no significant difference was observed between the two incubation periods. This study emphasizes the role of exosome-to-cell ratio in the internalization process, contributing to the understanding of understanding of how these exosomes interact with immune cells
- PublicationQuestionnaire translation, validation and relationship determinants of marital quality with clinical attributes of functional dyspepsia, irritable bowel syndrome and its overlap syndrome in Malay women(2024-09)Hamid, NurhazwaniFunctional Dyspepsia (FD), Irritable Bowel Syndrome (IBS), and FD-IBS overlap are common and bothersome disorders affecting people of diverse backgrounds, predominantly women. Research is limited in measurement tools available for marital quality, and the association of marital quality with psychological distress, symptom severity, and quality of life (QoL) of Malay women with FD, IBS, and FD-IBS overlap. Phase I, to develop valid measurement tools for marital quality in the Malay language. Secondly (Phase II), to compare mean differences, correlation between study variables, and to examine path relationships between marital quality with clinical attributes including psychological distress, symptom severity, and QoL among Malay women with FD, IBS, and FD-IBS overlap. Phases I and II were conducted using cross-sectional design and by convenience sampling. Phase I consisted of translation into the Malay language and validation of questionnaires including Revised Dyadic Adjustment Scale (RDAS), Relationship Dynamic Scale (RDS), Short Version Psychological Maltreatment of Women Inventory (PMWI-F), Multidimensional Pain Inventory (MPI), and Coping Strategies Questionnaire-Catastrophizing Scale (CSQ-CAT). All questionnaires were examined for content validity index (CVI), face validity index (FVI), exploratory factor analysis (EFA), and reliability (Cronbach’s alpha). For phase II, first, multivariate analysis of variance (MANOVA) would be used to determine mean differences between variables, second, correlation analysis of all variables and third, path analysis (PA) model to map inter-relationships between variables. All the newly translated Malay questionnaires were found to have CVIs and FVIs > 0.80. There were 150 participants (mean age 34.1 years old, standard deviation (SD)=9.5 years) and 513 participants (mean age 37.2 years old, SD=9.3 years) who have participated in phase I and II respectively. For phase I, all factor loadings were found satisfactory with EFA and the Cronbach’s alpha of RDAS-M, RDSM, PMWI-F-M, MPI-M, and CSQ-CAT-M was ranged between 0.7 and 0.9. For phase II, with MANOVA, the most significant mean differences were seen between groups of FD versus IBS, and FD versus FD-IBS overlap, and the marital quality most significantly affected included consensus, conflict management, negative responses, and solicitous responses. With Pearson correlation analysis, FD demonstrated the most significant correlations with all clinical attributes (r > 0.5). With PA of overall model, the fit indices for FD, IBS, and FD-IBS overlap were found to be acceptable. FD-IBS overlap had the most number of paths (n=30), followed by FD (n=26), and IBS the least (n=24). With PA, the most supported hypothesis for the domains marital quality and symptom severity was demonstrated with FD-IBS overlap. Whereas, for the domain psychological distress, the most supported hypothesis using PA was demonstrated for FD. First, the tools to measure marital quality have been translated into the Malay language, and are validated. Second, there is significant inter-relationships of marital quality with clinical attributes of FD, IBS, and FD-IBS overlap in the Malay women.