Displaying publications 81 - 100 of 276 in total

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  1. An in-vitro method for buccal adhesion studies: importance of instrument variables
    Wong CF, Yuen KH, Peh KK
    Int J Pharm, 1999 Mar 25;180(1):47-57.
    PMID: 10089291
    A method using a texture analyzer equipment and chicken pouch as the biological tissue was investigated for measuring the bioadhesive properties of polymers under simulated buccal conditions. The method was evaluated using two polymers, namely Carbopol 974P and Methocel K4M while the instrument variables studied included the contact force, contact time and speed of withdrawal of the probe from the tissue. The parameters measured were the work of adhesion and peak detachment force. Longer contact time and faster probe speed not only gave better reproducibility of results, but also better sensitivities for both parameters measured. On the other hand, a certain level of contact force was found essential for achieving good bioadhesion, above which there was no further contribution to the bioadhesion process. When the method was applied to determine the bioadhesiveness of several polymers, the values obtained for the work of adhesion and peak detachment force were quite consistent in the ranking of the polymers. The Carbopols were found to have the highest values, followed by gelatin, sodium carboxymethyl celluloses and hydroxypropylmethyl celluloses. On the other hand, Alginic acid, Eudragit RLPO and RSPO, and Chitosan appeared to have low bioadhesive values.
  2. Formulation and evaluation of controlled release Eudragit buccal patches
    Wong CF, Yuen KH, Peh KK
    Int J Pharm, 1999 Feb 01;178(1):11-22.
    PMID: 10205621
    Controlled release buccal patches were fabricated using Eudragit NE40D and studied. Various bioadhesive polymers, namely hydroxypropylmethyl cellulose, sodium carboxymethyl cellulose and Carbopol of different grades, were incorporated into the patches, to modify their bioadhesive properties as well as the rate of drug release, using metoprolol tartrate as the model drug. The in-vitro drug release was determined using the USP 23 dissolution test apparatus 5 with slight modification, while the bioadhesive properties were evaluated using texture analyzer equipment with chicken pouch as the model tissue. The incorporation of hydrophilic polymers was found to affect the drug release as well as enhance the bioadhesiveness. Although high viscosity polymers can enhance the bioadhesiveness of the patches, they also tend to cause non-homogeneous distribution of the polymers and drug, resulting in non-predictable drug-release rates. Of the various bioadhesive polymers studied, Cekol 700 appeared to be most satisfactory in terms of modifying the drug release and enhancement of the bioadhesive properties.
  3. IL-23/IL-17 axis in the pathogenesis and treatment of systemic lupus erythematosus and rheumatoid arthritis
    Farah Izati A, Wong KK, Che Maraina CH
    Malays J Pathol, 2020 Dec;42(3):333-347.
    PMID: 33361714
    Interleukin-23 (IL-23) and IL-17 are the gatekeepers of CD4+ T helper 17 (Th17) cells where IL-23 is required for the development and expansion of Th17 cells that subsequently produce IL-17 to promote inflammation. Owing to such pro-inflammatory properties, the IL-23/IL-17 axis has emerged as an important mechanism in the pathogenesis of autoimmune diseases including systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). In recent years, therapeutic antibodies targeting IL-23 (e.g. ustekinumab, tildrakizumab, guselkumab) or IL-17 (e.g. brodalumab, secukinumab, ixekizumab) have been approved for the treatment of various autoimmune diseases. In this review, we describe the pathogenic mechanisms of IL-23/IL-17 axis in SLE and RA, as well as summarising the findings from phase II and III clinical trials of anti-IL-23/IL-17 therapeutic antibodies in SLE and RA patients. In particular, phase II study has demonstrated that the anti-IL-23 antibody (ustekinumab) confers enhanced treatment outcomes in SLE patients, while anti-IL-17 antibodies (secukinumab and ixekizumab) have shown improved clinical benefits for RA patients in phase II/III studies. Our review highlights the emerging importance of targeting the IL-23/IL-17 axis in SLE and RA patients.
  4. The empty sella syndrome
    Anuar M, Ng KK, Chong KF
    Med J Malaysia, 1977 Mar;31(3):244-6.
    PMID: 904521
  5. Right hydronephrosis and vesicocolic fistula complicating sigmoid colonic diverticulitis: report of a case
    Ng KK, Tan KM, Lim KT
    Dis Colon Rectum, 1975 Oct;18(7):623-5.
    PMID: 1181168
  6. Fulltext Synthesis of nanopartical-based binary oxide electrode tio2-zro2 with carrot-derived natural dye extract for dye sensitized solar cell (DSSC) application
    Win, S. Y., Win, T. T., Maung, Y. M., Soe, K. K. K., Kyaw, T. T., Tan, C. K., et al.
    Pertanika Journal of Science & Technology, 2015;23(1):119-125.
    MyJurnal
    Dye-sensitized solar cell (DSSC) is the third generation of thin film solar cell. In this work, carrot fruit dye was prepared and used in DSSC as a sensitizer. TiO2–ZrO2 fine binary oxide was mechanochemically prepared and made paste. TiO2–ZrO2 paste (colloidal) was deposited onto FTO/glass in two ways, i.e. as single and double coatings by rolling method. It was immersed in the carrot solution to get dyed cell. The dyed TiO2-ZrO2-FTO/glass cell was offset with the FTO/glass cell coated with adhesive carbon paste. Photovoltaic properties of prepared TiO2–ZrO2 DSSC cell were measured. Results showed that the efficiency of double coating cell was greater than that of the single coating cell. According to the fill factor from the experiments, both the DSSC cells were acceptable for industrial requirement. Hence, it can be concluded that the results obtained were acceptable in the use of cost-effective and eco-favourable dye-sensitized solar cell.
  7. Autochthonous spread of DENV-3 genotype III in Malaysia mitigated by pre-existing homotypic and heterotypic immunity
    Tan KK, Nellis S, Zulkifle NI, Sulaiman S, AbuBakar S
    Epidemiol Infect, 2018 10;146(13):1635-1641.
    PMID: 29860959 DOI: 10.1017/S0950268818001425
    Dengue virus type 3 genotype III (DENV-3/III) is widely distributed in most dengue-endemic regions. It emerged in Malaysia in 2008 and autochthonously spread in the midst of endemic DENV-3/I circulation. The spread, however, was limited and the virus did not cause any major outbreak. Spatiotemporal distribution study of DENV-3 over the period between 2005 and 2011 revealed that dengue cases involving DENV-3/III occurred mostly in areas without pre-existing circulating DENV-3. Neutralisation assays performed using sera of patients with the respective infection showed that the DENV-3/III viruses can be effectively neutralised by sera of patients with DENV-3 infection (50% foci reduction neutralisation titres (FRNT50) > 1300). Sera of patients with DENV-1 infection (FRNT50 ⩾ 190), but not sera of patients with DENV-2 infection (FRNT50 ⩽ 50), were also able to neutralise the virus. These findings highlight the possibility that the pre-existing homotypic DENV-3 and the cross-reacting heterotypic DENV-1 antibody responses could play a role in mitigating a major outbreak involving DENV-3/III in the Klang Valley, Malaysia.
  8. Fulltext Vibration of symmetrically layered angle-ply cylindrical shells filled with fluid
    Mat Daud NI, Viswanathan KK
    PLoS One, 2019;14(7):e0219089.
    PMID: 31269073 DOI: 10.1371/journal.pone.0219089
    Vibrational behaviour of symmetric angle-ply layered circular cylindrical shell filled with quiescent fluid is presented. The equations of motion of cylindrical shell in terms of stress and moment resultants are derived from the first order shear deformation theory. Irrotational of inviscid fluid are expressed as the wave equation. These two equations are coupled. Strain-displacement relations and stress-strain relations are adopted into the equations of motion to obtain the differential equations with displacements and rotational functions. A system of ordinary differential equation is obtained in one variable by assuming the functions in separable form. Spline of order three is applied to approximate the displacement and rotational functions, together with boundary conditions, to get a generalised eigenvalue problem. The eigenvalue problem is solved for eigen frequency parameter and associate eigenvectors of spline coefficients. The study of frequency parameters are analysed using the parameters the thickness ratio, length ratio, angle-ply, properties of material and number of layers under different boundary conditions.
  9. Thermal and thermal damage responses during switching bipolar radiofrequency ablation employing bipolar needles: A computational study on the effects of different electrode configuration, input voltage and ablation duration
    Cheong JKK, Ooi EH, Ooi ET
    Int J Numer Method Biomed Eng, 2020 09;36(9):e3374.
    PMID: 32519516 DOI: 10.1002/cnm.3374
    Recent studies have demonstrated the effectiveness of switching bipolar radiofrequency ablation (bRFA) in treating liver cancer. Nevertheless, the clinical use of the treatment remains less common than conventional monopolar RFA - likely due to the lack of understanding of how the tissues respond thermally to the switching effect. The problem is exacerbated by the numerous possible switching combinations when bRFA is performed using bipolar needles, thus making theoretical deduction and experimental studies difficult. This article addresses this issue via computational modelling by examining if significant variation in the treatment outcome exists amongst six different electrode configurations defined by the X-, C-, U-, N-, Z- and O-models. Results indicated that the tissue thermal and thermal damage responses varied depending on the electrode configuration and the operating conditions (input voltage and ablation duration). For a spherical tumour, 30 mm in diameter, complete ablation could not be attained in all configurations with 70 V input voltage and 5 minutes ablation duration. Increasing the input voltage to 90 V enlarged the coagulation zone in the X-model only. With the other configurations, extending the ablation duration to 10 minutes was found to be the better at enlarging the coagulation zone.
  10. Prevalence of Helicobacter pylori infection in endoscopy and non-endoscopy personnel: results of field survey with serology and 14C-urea breath test
    Goh KL, Parasakthi N, Ong KK
    Am J Gastroenterol, 1996 Feb;91(2):268-70.
    PMID: 8607491
    OBJECTIVES:
    The aims of the study were, first, to determine the prevalence of Helicobacter pylori (HP) among endoscopy personnel and a group of non-endoscopy volunteers and, second, to evaluate the usefulness of two noninvasive tests of diagnosis: serology and the urea breath test.

    METHODS:
    The two noninvasive methods of HP diagnosis, serology and 14C-urea breath test (UBT), were used in a cross-sectional survey of endoscopists, nurse-assistants, and non-endoscopy personnel.

    RESULTS:
    One hundred and thirty-five volunteers were recruited for the study. In 116, results of the two tests were in agreement (kappa = 0.645). Further analysis was based on the results of the UBT. Endoscopy personnel (endoscopists and nurse-assistants) as a group had a significantly higher incidence of HP than did controls (32.9% vs. 11.3%; p = 0.004). The two groups were comparable with regard to mean age, sex, ethnic distribution, and social class.

    CONCLUSIONS:
    HP infection is more prevalent among endoscopy personnel. Both diagnostic tests (serology and UBT) were convenient and relatively simple to perform, and results gave a high level of agreement.
  11. Diclofenac release from eudragit-containing matrices and effects of thermal treatment
    Billa N, Yuen KH, Peh KK
    Drug Dev Ind Pharm, 1998 Jan;24(1):45-50.
    PMID: 15605596
    Ethyl acrylate-methyl methacrylate copolymer (Eudragit NE40D) was evaluated as matrix material for preparing controlled-release tablets of diclofenac sodium. Drug release could be modified in a predictable manner by varying the Eudragit NE40D content, but was pH dependent, being markedly reduced at lower pH. This could be attributed to the low solubility of the drug at these pH values. Thermal treatment of the tablets at 60 degrees C was also found to affect the rate of drug release, which was found to decrease with an increase in the treatment duration, but could be stabilized after 96 hr of treatment. This was also associated with a corresponding increase in the tablet tensile strength. However, treatment of the granules for 5 hr prior to compaction into tablets could shorten the stabilizing time of the drug release to 48 hr and that of the tensile strength to 24 hr. The effect of thermal treatment may be ascribed to better coalescence of the Eudragit particles to form a fine network, resulting in matrix of higher tortuosity and lower porosity.
  12. Possible mechanism for drug retardation from glyceryl monostearate matrix system
    Peh KK, Wong CF, Yuen KH
    Drug Dev Ind Pharm, 2000 Apr;26(4):447-50.
    PMID: 10769787
    Lipophilicity was evaluated as a possible mechanism for drug retardation from a glyceryl monostearate matrix system. Lipophilicity of the glyceryl monostearate matrix system was studied using contact angle measurement of water droplets on the surface of compressed disks, extrudate ascension of water, and movement of water through a powder mixture packed in a high-performance liquid chromatographic (HPLC) column. Increase in glyceryl monostearate content resulted in an increase in water droplet contact angle, decrease in the rate of water ascending the extrudate, and increase in the pressure values as a function of flow rate of water moving through the powder mixture. These could be due to the increase in lipophilicity of the matrix, rendering the matrix less wettable. As a result, the rate of water penetration into the matrix decreased, and the drug release could be sustained.
  13. Relating in vitro/in vivo data of two controlled-release metformin formulations
    Yuen KH, Peh KK, Tan BL
    Drug Dev Ind Pharm, 1999 May;25(5):613-8.
    PMID: 10219530
    This study was conducted to compare the bioavailability of two controlled-release metformin preparations (Diabetmin Retard and Glucophage Retard) and also to correlate the in vitro and in vivo data obtained with the two preparations. Twelve healthy volunteers participated in the study, conducted according to a completely randomized, two-way crossover design. The preparations were compared using area under the plasma concentration-time curve AUC0-infinity, time to reach peak plasma concentration Tmax, and peak plasma concentration Cmax, while correlation was determined between in vitro release and in vivo absorption. Diabetmin Retard demonstrated a slower rate of in vitro release, but a faster rate of in vivo absorption than Glucophage Retard. However, the in vivo absorption of both products was found to be slower than that of drug released in vitro. A satisfactory relationship could be established between the in vitro and in vivo results, but there was no rank order correlation. No statistically significant difference was observed between the two preparations in the parameters AUC0-infinity and Cmax. However, a slight but statistically significant difference was observed between the Tmax values, but it may not be therapeutically significant. Moreover, the 90% confidence interval for the ratio of the logarithmic transformed AUC0-infinity values, as well as the logarithmic transformed Cmax values, of Diabetmin Retard over those of Glucophage Retard was within the acceptance criteria of 0.80-1.25.
  14. Comparative bioavailability study of a generic naltrexone tablet preparation
    Yuen KH, Peh KK, Billa N
    Drug Dev Ind Pharm, 1999 Mar;25(3):353-6.
    PMID: 10071829
    The bioavailability of a generic preparation of naltrexone (Narpan) was compared with the innovator product, Trexan. Twelve healthy volunteers participated in the study, conducted according to a completely randomized, two-way crossover design. The preparations were compared using the parameters area under the plasma concentration-time curve AUC0-infinity, peak plasma concentration Cmax, and time to reach peak plasma concentration Tmax. No statistically significant difference was observed between the logarithmic transformed AUC0-infinity and the logarithmically transformed Cmax values of the two preparations. Also, no statistically significant difference was observed between the untransformed Tmax values. In addition, the 90% confidence interval for the ratio of the logarithmic transformed AUC0-infinity values of Narpan over those of Trexan was found to lie between 0.87 and 1.01, while that of the logarithmic transformed Cmax values was between 0.94 and 1.23, both being within the bioequivalence limit of 0.80-1.25. The numerical values of the elimination half-life (t1/2) obtained with the two preparations were also not significantly different and were comparable to those reported in the literature.
  15. Comparison between FEV1/FEV6 and FEV1/FVC as screening of chronic obstructive pulmonary disease
    Ng SC, Abu Samah F, Helmy K, Sia KK
    Med J Malaysia, 2017 10;72(5):286-290.
    PMID: 29197884 MyJurnal
    OBJECTIVE: To compare FEV1/FEV6 to the standard spirometry (FEV1/FVC) as a screening tool for COPD.

    METHODS: This cross-sectional study was conducted at Hospital Tuanku Fauziah, Perlis, Malaysia from August 2015 to April 2016. FEV1/FEV6 and FEV1/FVC results of 117 subjects were analysed. Demographic data and spirometric variables were tabulated. A scatter plot graph with Spearman's correlation was constructed for the correlation between FEV1/FEV6 and FEV1/FVC. The sensitivity, specificity, positive and negative predictive values of FEV1/FEV6 were determined with reference to the gold standard of FEV1/FVC ratio <0.70. Receiver-operator characteristic (ROC) curve analysis and Kappa statistics were used to determine the FEV1/FEV6 ratio in predicting an FEV1/FVC ratio <0.70.

    RESULTS: Spearman's correlation with r = 0.636 (P<0.001) was demonstrated. The area under the ROC curve was 0.862 (95% confidence interval [CI]: 0.779 - 0.944, P<0.001). The FEV1/FEV6 cut-off with the greatest sum of sensitivity and specificity was 0.75. FEV1/FEV6 sensitivity, specificity, positive and negative predictive values were 93.02%, 67.74%, 88.89% and 77.78% respectively. There was substantial agreement between the two diagnostic cut-offs (κ = 0.634; 95% CI: 0.471 - 0.797, P<0.001) CONCLUSIONS: The FEV1/FEV6 ratio can be considered to be a good alternative to the FEV1/FVC ratio for screening of COPD. Larger multicentre study and better education on spirometric techniques can validate similar study outcome and establish reference values appropriate to the population being studied.

  16. The secretory phenotypes of envenomed cells: Insights into venom cytotoxicity
    Yong Y, Hiu JJ, Yap MKK
    Adv Protein Chem Struct Biol, 2023;133:193-230.
    PMID: 36707202 DOI: 10.1016/bs.apcsb.2022.08.001
    Snake envenomation is listed as Category A Neglected Tropical Diseases (NTD) by World Health Organization, indicates a severe public health problem. The global figures for envenomation cases are estimated to be more than 1.8 million annually. Even if the affected victims survive the envenomation, they might suffer from permanent morbidity due to local envenomation. One of the most prominent local envenomation is dermonecrosis. Dermonecrosis is a pathophysiological outcome of envenomation that often causes disability in the victims due to surgical amputations, deformities, contracture, and chronic ulceration. The key venom toxins associated with this local symptom are mainly attributed to substantial levels of enzymatic and non-enzymatic toxins as well as their possible synergistic actions. Despite so, the severity of the local tissue damage is based on macroscopic observation of the bite areas. Furthermore, limited knowledge is known about the key biomarkers involved in the pathogenesis of dermonecrosis. The current immunotherapy with antivenom is also ineffective against dermonecrosis. These local effects eventually end up as sequelae. There is also a global shortage of toxins-targeted therapeutics attributed to inadequate knowledge of the actual molecular mechanisms of cytotoxicity. This chapter discusses the characterization of secretory phenotypes of dermonecrosis as an advanced tool to indicate its severity and pathogenesis in envenomation. Altogether, the secretory phenotypes of envenomed cells and tissues represent the precise characteristics of dermonecrosis caused by venom toxins.
  17. Fulltext Mumps encephalomyelitis
    Tan KK, Manickam WD, Cardosa MJ
    Singapore Med J, 1992 Oct;33(5):525-6.
    PMID: 1455285
    A 7-year-old Indian girl developed complete paralysis of her lower limbs and acute urinary retention 10 days after suffering from mumps. Encephalomyelitis due to mumps was not suspected initially since it is a rare complication of mumps, although relatively well-documented. However, the preceding history of parotitis and the presence of mumps-specific IgM in both blood and cerebrospinal fluid led to the diagnosis. The initially severe acute neurological deficits resolved completely three months after onset of her illness. Serological investigations were helpful in diagnosing neurological complications of mumps in this case, and especially where there is no preceding parotitis.
    Keywords: Mumps, encephalomyelitis, infection, Pulau Pinang, general hospital, Malaysia
  18. Fulltext Morphological and molecular evidence support the intertidal barnacle Octomeris intermedia Nilsson-Cantell, 1921 (Thoracica, Chthamalidae) as a valid species in Indo-Pacific waters
    Chan BKK, Tsao YF, Ganmanee M
    Zookeys, 2020;914:1-31.
    PMID: 32132853 DOI: 10.3897/zookeys.914.49328
    Octomeris is a chthamalid intertidal barnacle with eight shell plates. There are currently two species of such barnacles: O. brunnea Darwin, 1854 (type locality in the Philippines), common in the Indo-Pacific region, and O. angulosa Sowerby, 1825, only recorded in South Africa. Octomeris intermedia Nilsson-Cantell, 1921, identified from the Mergui Archipelago in Myanmar, was considered to be conspecific with O. brunnea by Hiro (1939) based on samples collected in Taiwan. The morphological differences in shell and opercular plates between O. brunnea and O. intermedia are believed to be intra-specific variations due to different degrees of shell erosion. In the present study, the genetic and morphological differentiations of Octomeris in the Indo-Pacific region were examined. This study found two molecular clades (with inter-specific differences) based on the divergence in the COI genes, and the species also have distinct geographical distributions. The Octomeris brunnea clade covers samples collected from the Philippines and Taiwan waters and the other clade, which we argue is O. intermedia, is distributed in Phuket and Krabi, Thailand and Langkawi, Malaysia. Phuket and Krabi are located approximately 300 km south of the Mergui Archipelago, the type locality of O. intermedia. The morphology of samples collected from Thailand fits the type description of O. intermedia in Nilsson-Cantell (1921). Our study concludes that O. intermedia is a valid species based on morphological and molecular evidence.
  19. Effect of Gibberellin and Heat Shock on the Lipid Composition of Endoplasmic Reticulum in Barley Aleurone Layers
    Grindstaff KK, Fielding LA, Brodl MR
    Plant Physiol, 1996 Feb;110(2):571-581.
    PMID: 12226205
    The heat-shock responses of barley (Hordeum vulgare L. cv Hi- malaya) aleurone layers incubated with or without gibberellic acid (GA3) were compared. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that heat shock blocked the synthesis and secretion of secretory proteins from GA3-treated layers but not untreated layers. This suppression of secretory protein synthesis has been correlated with changes in endoplasmic reticulum (ER) membranes (F.C. Belanger, M. R. Brodl, T.-h.D. Ho [1986] Proc Natl Acad Sci USA 83: 1354-1358; L. Sticher, A.K. Biswas, D.S. Bush, R.L. Jones [1990] Plant Physiol 92: 506-513). Our secretion data suggested that the ER membranes of aleurone layers incubated without GA3 may be more heat shock tolerant. To investigate this, the lipid profiles of membrane extracts in aleurone layers labeled with [14C]glycerol were examined. Heat shock markedly increased [14C]glycerol incorporation into phosphatidylcholine (PC), and gas chromatography revealed an increase in the amount of saturated fatty acids associated with thin layer chromatography-purified PC in GA3-treated layers. In contrast, aleurone layers incubated without GA3 at normal temperature contained PC-associated fatty acids with a greater degree of saturation than GA3-treated layers. Heat shock modestly increased the degree of fatty acid saturation in untreated aleurone layers. This same trend was noted in fatty acids isolated from ER membranes purified by continuous sucrose density centrifugation. We propose that increased fatty acid saturation may help sustain ER membrane function in heat-shocked aleurone layers incubated in the absence of GA3.
  20. Vaginal dryness: a review of current understanding and management strategies
    Mark JKK, Samsudin S, Looi I, Yuen KH
    Climacteric, 2024 Jun;27(3):236-244.
    PMID: 38318859 DOI: 10.1080/13697137.2024.2306892
    The issue of vaginal dryness in genitourinary syndrome of menopause (GSM) and its pervasive impact on women's quality of life is often overlooked. Extensive surveys conducted worldwide reveal limited understanding of vaginal dryness among public and health-care providers. Physician knowledge on menopause medicine varies globally, highlighting the need for standardized training. Effective communication between physicians and patients plays a crucial role in diagnosing and treating GSM symptoms. There are multiple treatment options to improve vaginal lubrication, including hormonal and non-hormonal therapies, along with lifestyle modifications. Tailoring treatments to individual patient preferences is crucial for compliance. Overall, GSM is multifaceted, from the prevalence of vaginal dryness to the nuances of treatment preferences. The urgency of widespread education and awareness of this matter must be underscored to meet the aim of enhancing the well-being and quality of life for women.
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