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Fulltext A guide in lentiviral vector production for hard-to-transfect cells, using cardiac-derived c-kit expressing cells as a model system

Kalidasan V, Ng WH, Ishola OA, Ravichantar N, Tan JJ, Das KT

Sci Rep, 2021 Sep 28;11(1):19265.
PMID: 34584147 DOI: 10.1038/s41598-021-98657-7

Gene therapy revolves around modifying genetic makeup by inserting foreign nucleic acids into targeted cells via gene delivery methods to treat a particular disease. While the genes targeted play a key role in gene therapy, the gene delivery system used is also of utmost importance as it determines the success of gene therapy. As primary cells and stem cells are often the target cells for gene therapy in clinical trials, the delivery system would need to be robust, and viral-based entries such as lentiviral vectors work best at transporting the transgene into the cells. However, even within lentiviral vectors, several parameters can affect the functionality of the delivery system. Using cardiac-derived c-kit expressing cells (CCs) as a model system, this study aims to optimize lentiviral production by investigating various experimental factors such as the generation of the lentiviral system, concentration method, and type of selection marker. Our findings showed that the 2nd generation system with pCMV-dR8.2 dvpr as the packaging plasmid produced a 7.3-fold higher yield of lentiviral production compared to psPAX2. Concentrating the virus with ultracentrifuge produced a higher viral titer at greater than 5 × 105 infectious unit values/ml (IFU/ml). And lastly, the minimum inhibitory concentration (MIC) of puromycin selection marker was 10 μg/mL and 7 μg/mL for HEK293T and CCs, demonstrating the suitability of antibiotic selection for all cell types. This encouraging data can be extrapolated and applied to other difficult-to-transfect cells, such as different types of stem cells or primary cells.
Fulltext Allergies in asthma

Zulkifli A, Ng WH, Chelvam P

Family Practitioner, 1979;3(5):32-34.

148 patients, 79 males and 60 females were seen in 1978 at Medical Unit Universiti Kebangsaan Kuala Lumpur. For majority of the patients the attacks of asthma begin at an early age. History of allergies were found in majority of the patients. Family history of asthma was noted in about 50%. Of the allergens that triggers of an attack of asthma, household dusts, rhinitis and pollen tops the list. Of the food the common allergens were shrimps, eggs and crabs. Most of the above allergens can be avoided or counteracted.
Study site: Medical Unit, Hospital Kuala Lumpur (UKM unit), Malaysia
Fulltext Enlarging the thermal coagulation volume during thermochemical ablation with alternating acid-base injection by shortening the injection interval: A computational study

Mak NL, Ng WH, Ooi EH, Lau EV, Pamidi N, Foo JJ, et al.

Comput Methods Programs Biomed, 2024 Jan;243:107866.
PMID: 37865059 DOI: 10.1016/j.cmpb.2023.107866

BACKGROUND AND OBJECTIVES: Thermochemical ablation (TCA) is a cancer treatment that utilises the heat released from the neutralisation of acid and base to raise tissue temperature to levels sufficient to induce thermal coagulation. Computational studies have demonstrated that the coagulation volume produced by sequential injection is smaller than that with simultaneous injection. By injecting the reagents in an ensuing manner, the region of contact between acid and base is limited to a thin contact layer sandwiched between the distribution of acid and base. It is hypothesised that increasing the frequency of acid-base injections into the tissue by shortening the injection interval for each reagent can increase the effective area of contact between acid and base, thereby intensifying neutralisation and the exothermic heat released into the tissue.
METHODS: To verify this hypothesis, a computational model was developed to simulate the thermochemical processes involved during TCA with sequential injection. Four major processes that take place during TCA were considered, i.e., the flow of acid and base, their neutralisation, the release of exothermic heat and the formation of thermal damage inside the tissue. Equimolar acid and base at 7.5 M was injected into the tissue intermittently. Six injection intervals, namely 3, 6, 15, 20, 30 and 60 s were investigated.
RESULTS: Shortening of the injection interval led to the enlargement of coagulation volume. If one considers only the coagulation volume as the determining factor, then a 15 s injection interval was found to be optimum. Conversely, if one places priority on safety, then a 3 s injection interval would result in the lowest amount of reagent residue inside the tissue after treatment. With a 3 s injection interval, the coagulation volume was found to be larger than that of simultaneous injection with the same treatment parameters. Not only that, the volume also surpassed that of radiofrequency ablation (RFA); a conventional thermal ablation technique commonly used for liver cancer treatment.
CONCLUSION: The numerical results verified the hypothesis that shortening the injection interval will lead to the formation of larger thermal coagulation zone during TCA with sequential injection. More importantly, a 3 s injection interval was found to be optimum for both efficacy (large coagulation volume) and safety (least amount of reagent residue).
Cardiac arrhythmias in acute myocardial infarction

Ng WH, Goh TH, Ishak E, Ahmad Z

Med J Malaysia, 1979 Dec;34(2):131-5.
PMID: 548713
Normal electrocardiogram after myocardial infarction

Ng WH, Ahmad Z

Med J Malaysia, 1978 Dec;33(2):128-32.
PMID: 755162
Analysis and functional annotation of expressed sequence tags (ESTs) from multiple tissues of oil palm (Elaeis guineensis Jacq.)

Ho CL, Kwan YY, Choi MC, Tee SS, Ng WH, Lim KA, et al.

BMC Genomics, 2007;8:381.
PMID: 17953740

Oil palm is the second largest source of edible oil which contributes to approximately 20% of the world's production of oils and fats. In order to understand the molecular biology involved in in vitro propagation, flowering, efficient utilization of nitrogen sources and root diseases, we have initiated an expressed sequence tag (EST) analysis on oil palm.