Displaying publications 1 - 20 of 36 in total

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  1. A comparative study of two methods for the isolation of human leucocytes for DNA extraction
    Lim LH, Ton SH, Cheong SK
    Malays J Pathol, 1990 Jun;12(1):39-41.
    PMID: 2090888
    The 'Dextran' and the 'Buffy-coat' methods for isolation of human leucocytes for DNA extraction were compared on the basis of DNA yield from the same amounts (10 ml) of blood. Human leucocytes from a total of 11 samples were isolated using both methods for each sample after which DNA was extracted. Extracted DNA samples were treated with ribonucleases and proteinase K after which the yields were quantitated by measuring absorbance at 260 nm. The 'Buffy-coat' method yielded a mean concentration of DNA of 476.7 micrograms/ml (range: 212 to 700 micrograms/ml) while the 'Dextran' method yielded 188.4 micrograms/ml (range: 64 to 340 micrograms/ml). The difference was confirmed by subjecting the extracted DNA samples to agarose gel electrophoresis.
  2. Fulltext A preliminary report on the relationship between serum anti-thrombin III concentration in pre- and post-operative patients and in women on oral contraceptives
    Ton SH, Lopez CG, Thiruselvam A, Lyou YT
    Med J Malaysia, 1981 Dec;36(4):212-4.
    PMID: 7334955
    A T III values in patients undergoing surgery were found to be lower post-operatively but the fall in value was not significant while women on oral contraceptives were found to have similar AT III values as that of women not on oral contraceptives. The observed values are discussed.
  3. Amelioration of glucose homeostasis by glycyrrhizic acid through gluconeogenesis rate-limiting enzymes
    Chia YY, Liong SY, Ton SH, Kadir KB
    Eur J Pharmacol, 2012 Feb 29;677(1-3):197-202.
    PMID: 22227336 DOI: 10.1016/j.ejphar.2011.12.037
    The activities of phosphoenolpyruvate carboxykinase (PEPCK) are influenced by active glucocorticoids which are activated by 11-β-hydroxysteroid dehydrogenase 1 (11β-HSD1) while hexose-6-phosphate dehydrogenase (H6PDH) influences the activities of 11-βHSD1 in a cofactor manner. Dysregulation of PEPCK and H6PDH has been associated with the pathogenesis of metabolic syndrome. Sixteen male Sprague Dawley rats, fed ad libitum, were assigned to two groups, control and treated, with the treated group being given GA at 100mg/kg for one week. Blood and subcutaneous and visceral adipose tissue, abdominal and quadriceps femoris muscle, liver and kidney were examined. GA treatment led to an overall significant decrease in blood glucose while HOMA-IR. PEPCK activities decreased in the liver but increased in the visceral adipose tissue. H6PDH activities also decreased significantly in the liver while 11β-HSD1 activities decreased significantly in all studied tissues except for subcutaneous adipose tissue. Adipocytes in the subcutaneous and visceral depots showed a reduction in size. Though increased glycogen storage was seen in the liver, no changes were observed in the kidneys and muscles. Results from this study may imply that GA could counteract the development of type 2 diabetes mellitus by improving insulin sensitivity and probably by reduction of H6PDH, 11β-HSD1 and a selective decrease in PEPCK activities.
  4. An in-house ELISA method for measuring surfactant protein A
    Cheong KB, Cheong SK, Boo NY, Jemilah M, Ton SH
    Malays J Pathol, 1995 Dec;17(2):91-6.
    PMID: 8935133
    An in-house enzyme-linked immunoabsorbant assay (ELISA) for SP-A was successfully developed using in-house polyclonal anti SP-A and a commercial polyclonal anti-rabbit immunoglobulin horseradish peroxidase conjugate system. The standard curve, generated by using 50 ng of SP-A to coat the plate and 1:500 dilution of polyclonal anti SP-A as a primary antibody, was linear for concentrations of SP-A ranging from 4 micrograms/l to 4000 micrograms/l and reproducible. Results of recovery study of SP-A from a known sample of tracheal aspirate ranged from 94%-114%. Intra- and inter-assay coefficients of variations were 2.7% and 5.6% respectively for a known sample of tracheal aspirate. Interference study showed that tracheal aspirate did not interfere with the assay. The assay developed was intended to be used for SP-A measurement in tracheal aspirates obtained from neonates with and without respiratory distress syndrome.
  5. An in-house assay for serum deoxythymidine kinase
    Seah LH, Ton SH, Cheong SK, Hamidah NH
    Malays J Pathol, 1991 Dec;13(2):109-13.
    PMID: 1823092
    An in-house method which utilizes 14C-thymidine as a substrate was used to assay deoxythymidine kinase in serum. The method is sensitive enough to detect normal levels of serum deoxythymidine kinase and the assay procedure also enables rapid handling of multiple samples. With a total reaction volume of 60 ul, the enzyme reaction was found to be linear with concentrations for up to 650 U/L of TK activity. On studying serum deoxythymidine kinase (s-TK) activity with incubation time, there was a proportional increase in activity with the length of incubation time. "Within-batch" precision showed a coefficient of variation (CV) of 4.7% for serum with extremely high s-TK levels and a CV of 8.8% for serum with normal s-TK levels. S-TK showed a CV of less than 16.0% in its activity when stored at -8 degrees C and at -20 degrees C. The normal reference range obtained for s-TK activity was 8.6 +/- 7.5 U/L.
  6. Fulltext Comparison of PCR-based genotyping methods for hepatitis B virus
    Lim CK, Tan JT, Ravichandran A, Chan YC, Ton SH
    Malays J Pathol, 2007 Dec;29(2):79-90.
    PMID: 19108399 MyJurnal
    Hepatitis B virus (HBV) is classified into eight genotypes (A to H). In this study, three genotyping methods were compared for their sensitivity and accuracy, namely PCR-RFLP on the S region, PCR-RFLP on the pre-S region and nested PCR with type specific primers. Sixty HBV samples from infected sera were genotyped. The nested PCR with type specific primers was found to be the most sensitive and produced substantial numbers of co-infections by genotypes B and C. The sensitivities for both PCR-RFLP methods were lower and did not reveal co-infections. Generally, the three methods produced consistent genotyping results in samples infected by single genotypes but for co-infections by genotypes B and C, the two PCR-RFLP methods yielded only single genotypic results. For the cases of single genotypic infections, genotypes ascertained by sequencing were in concordance across all three methods. However, when co-infections occurred, PCR analysis on clones revealed only single genotypic infections.
  7. Correlations of HBV genotypes, mutations affecting HBeAg expression and HBeAg/ anti-HBe status in HBV carriers
    Lim CK, Tan JT, Khoo JB, Ravichandran A, Low HM, Chan YC, et al.
    Int J Med Sci, 2006;3(1):14-20.
    PMID: 16421626
    This study was carried out to determine the effects of hepatitis B virus genotypes, core promoter mutations (A1762G1764-->T1762A1764) as well as precore stop codon mutations (TGG-->TAG) on HBeAg expression and HBeAg/ anti-HBe status. Study was also performed on the effects of codon 15 variants (C1858/ T1858) on the predisposition of precore stop codon mutations (TGG-->TAG). A total of 77 sera samples were analyzed. Fifty one samples were successfully genotyped of which the predominant genotype was genotype B (29/ 51, 56.9 %), followed by genotype C (16/ 51, 31.4 %). Co-infections by genotypes B and C were observed in four samples (7.8 %). To a lesser degree, genotypes D and E (2.0 % each) were also observed. For core promoter mutations, the prevalence was 68.8 % (53/ 77) for A1762G1764 wild-type and 14.3 % (11/ 77) for T1762A1764 mutant while 9.1 % (7/ 77) was co-infected by both strains. The prevalence of codon 15 variants was found to be 42.9 % (33/ 77) for T1858 variant and 16.9 % (13/ 77) for C1858 variant. No TAG mutation was found. In our study, no associations were found between genotypes (B and C) and core promoter mutations as well as codon 15 variants. Also no correlation was observed between HBeAg/ anti-HBe status with genotypes (B and C) and core promoter mutations.
  8. Effect of age, weight, race and sex on blood pressure and erythrocyte sodium pump characteristics
    Adeeb N, Ton SH, Muslim N
    Clin Exp Hypertens A, 1990;12(6):1115-34.
    PMID: 2173984
    In order to examine whether erythrocyte membrane handling of sodium is influenced by factors other than hypertension, measurements of red cell sodium transport were studied in one hundred normotensive volunteers. Erythrocyte sodium content was found to increase with increasing age, body weight and mean arterial pressure (MAP). It is also significantly correlated with age, body weight and MAP. Total sodium efflux was found to be reduced and negatively correlated with age and body weight. A reduction in ouabain-sensitive sodium efflux was also observed with increasing age and body weight. In males, the rate of ouabain-sensitive sodium efflux is higher than in females. Race was found to have no effect on erythrocyte electrolyte content and cationic flux rates of subjects. These data suggest that when studies in hypertension are going to be carried out, control subjects carefully matched for age, body weight and sex should be used if confounding results are not to be obtained.
  9. Effects of glycyrrhizic acid on 11 β-hydroxysteroid dehydrogenase (11 βHSD1 and 2) activities and HOMA-IR in rats at different treatment periods
    Chia YY, Yin YY, Ton SH, Kadir KB
    Exp. Clin. Endocrinol. Diabetes, 2010 Oct;118(9):617-24.
    PMID: 19998240 DOI: 10.1055/s-0029-1237703
    Glycyrrhizic acid (GA) has been reported to inhibit postprandial blood glucose rise and 11 β-hydroxysteroid dehydrogenase 1 (11 βHSD1) activity. As not much work has been done on GA effects on 11 βHSD1 and 2 and HOMA-IR at different treatment periods, this work was conducted. 60 male Sprague Dawley rats fed AD LIBITUM were assigned into six groups of control and treated that were given GA at different duration namely 12, 24 and 48 h. Treated and control groups were intraperitoneally administered with GA (50 mgkg (-1)) and saline respectively. Blood and subcutaneous (ATS) and visceral adipose tissue (ATV), abdominal (MA) and quadriceps femoris muscle (MT), liver (L) and kidney (K) were examined. HOMA-IR in GA-treated rats decreased in all groups (P<0.05). In the 12-h and 24-h treated rats, 11 βHSD1 activities decreased in all tissues (P<0.05) except MA and MT (P>0.05) in the former and ATV (P>0.05) in the latter. However, 11 βHSD1 activities decreased significantly in all tissues ( P<0.05) in the 48-h treated rats. Significant decrease in 11 βHSD2 (P>0.05) activities were observed in the L of all treatment groups and K in the 24-h and 48-h treated rats (P<0.05). Histological analysis on ATS showed increase in the number of small-size adipocytes while ATV adipocytes showed shrinkage after GA administration. Increased glycogen deposition in the L was observed in the GA-administered rats in all the treatment periods. In conclusion, GA treatment showed a decrease in the HOMA-IR and both 11 βHSD1 and 2 activities in all tissues, with more profound decrease in the 48-h treated rats.
  10. Fulltext Glycyrrhizic acid can attenuate metabolic deviations caused by a high-sucrose diet without causing water retention in male Sprague-Dawley rats
    Fernando HA, Chandramouli C, Rosli D, Lam YL, Yong ST, Yaw HP, et al.
    Nutrients, 2014 Nov 04;6(11):4856-71.
    PMID: 25375630 DOI: 10.3390/nu6114856
    Glycyrrhizic acid (GA) ameliorates many components of the metabolic syndrome, but its potential therapeutic use is marred by edema caused by inhibition of renal 11β-hydroxysteroid dehydrogenase 2 (11β-HSD2). We assessed whether 100 mg/kg per day GA administered orally could promote metabolic benefits without causing edema in rats fed on a high-sucrose diet. Groups of eight male rats were fed on one of three diets for 28 days: normal diet, a high-sucrose diet, or a high-sucrose diet supplemented with GA. Rats were then culled and renal 11β-HSD2 activity, as well as serum sodium, potassium, angiotensin II and leptin levels were determined. Histological analyses were performed to assess changes in adipocyte size in visceral and subcutaneous depots, as well as hepatic and renal tissue morphology. This dosing paradigm of GA attenuated the increases in serum leptin levels and visceral, but not subcutaneous adipocyte size caused by the high-sucrose diet. Although GA decreased renal 11β-HSD2 activity, it did not affect serum electrolyte or angiotensin II levels, indicating no onset of edema. Furthermore, there were no apparent morphological changes in the liver or kidney, indicating no toxicity. In conclusion, it is possible to reap metabolic benefits of GA without edema using the current dosage and treatment time.
  11. Fulltext Glycyrrhizic acid improved lipoprotein lipase expression, insulin sensitivity, serum lipid and lipid deposition in high-fat diet-induced obese rats
    Eu CH, Lim WY, Ton SH, bin Abdul Kadir K
    Lipids Health Dis, 2010;9:81.
    PMID: 20670429 DOI: 10.1186/1476-511X-9-81
    The metabolic syndrome, known also as the insulin resistance syndrome, refers to the clustering of several risk factors for atherosclerotic cardiovascular disease. Dyslipidaemia is a hallmark of the syndrome and is associated with a whole body reduction in the activity of lipoprotein lipase (LPL), an enzyme under the regulation of the class of nuclear receptors known as peroxisome proliferator-activated receptor (PPAR). Glycyrrhizic acid (GA), a triterpenoid saponin, is the primary bioactive constituent of the roots of the shrub Glycyrrhiza glabra. Studies have indicated that triterpenoids could act as PPAR agonists and GA is therefore postulated to restore LPL expression in the insulin resistant state.
  12. Glycyrrhizic acid prevents high calorie diet-induced metabolic aberrations despite the suppression of peroxisome proliferator-activated receptor γ expression
    Cheng HS, Yaw HP, Ton SH, Choy SM, Kong JM, Abdul Kadir K
    Nutrition, 2016 Sep;32(9):995-1001.
    PMID: 27130470 DOI: 10.1016/j.nut.2016.02.002
    OBJECTIVE: To investigate the effects of glycyrrhizic acid supplementation on glucose and lipid metabolism in rodents consuming a high-fat, high-sucrose diet.

    METHODS: Twenty-four male, 8-week old Sprague Dawley rats with an initial weight of 160 to 200 g were randomised into three groups (n = 6 for each group): groups A (standard rat chow), B (high-fat, high-sucrose diet), and C (high-fat, high-sucrose diet + 100 mg/kg/d of glycyrrhizic acid via oral administration). The rats were treated accordingly for 4 wk. Glycaemic parameters, lipid profile, stress hormones, and adiponectin levels were measured after the treatment. Relative gene expressions of peroxisome proliferator-activated receptor α and γ, lipoprotein lipase as well as gluconeogenic enzymatic activities in different tissues were also determined.

    RESULTS: Consumption of high-fat, high-sucrose diet triggered hyperglycaemia, insulin resistance, and dyslipidemia, which were effectively attenuated by supplementation with glycyrrhizic acid. Glycyrrhizic acid supplementation also effectively reduced circulating adrenaline, alleviated gluconeogenic enzymes overactivity, and promoted the upregulation of lipoprotein lipase expression in the cardiomyocytes and skeletal muscles. A high calorie diet also triggered hypoadiponectinaemia and suppression of peroxisome proliferator-activated receptor γ expression, which did not improve with glycyrrhizic acid treatment.

    CONCLUSION: Supplementation with glycyrrhizic acid could alleviate high calorie diet-induced glucose and lipid metabolic dysregulations by reducing circulatory stress hormones, normalizing gluconeogenic enzyme activities, and elevating muscular lipid uptake. The beneficial effects of these bioactivities outweighed the adverse effects caused by diet-induced repression of peroxisome proliferator-activated receptor γ expression, resulting in the maintenance of lipid and glucose homeostasis.

  13. HBeAG and anti-HBe in the Malaysian population and in Malaysian prisoners
    Ton SH, Lopez CG, Noriah R
    Southeast Asian J. Trop. Med. Public Health, 1983 Jun;14(2):252-4.
    PMID: 6635764
    The incidence of HBsAg in random blood donors was found to be twice that of the prisoner population. The anti-HBe however, was about twice that in the prisoners when compared with the random blood donors. Both the random blood donors and the prisoners had similar incidence of HBeAg. The percentage frequency of HBsAg positivity with anti-HBe positivity was also similar in both groups. The 18 normal non-blood donors did not have HBsAg, HBeAg or anti-HBe.
  14. Fulltext Hepatitis B markers in heterosexuals involved in promiscuous sexual activity
    Rajakumar MK, Ton SH, Lim KF, Oorloff KH
    Med J Malaysia, 1984 Mar;39(1):65-8.
    PMID: 6513842
    179 heterosexuals, selected for VDRL testing on the basis of a history of involvement in promiscuous sexual activity, mainly prostitution, had their serum also tested for hepatitis B infection markers, HBsAg, HBeAg and anti-HBe. 51 samples (29%) were found to be positive for at least one of the three markers, at levels higher than the already high levels in voluntary random blood donors in Malaysia.
  15. Immunogenicity of hepatitis B vaccine in healthy Malaysian adults
    Ton SH, Noriah R, Duraisamy G
    Indian J Med Res, 1988 Jun;87:542-4.
    PMID: 3240935
  16. Increased susceptibility of post-weaning rats on high-fat diet to metabolic syndrome
    Cheng HS, Ton SH, Phang SCW, Tan JBL, Abdul Kadir K
    J Adv Res, 2017 Nov;8(6):743-752.
    PMID: 29062573 DOI: 10.1016/j.jare.2017.10.002
    The present study aimed to examine the effects of the types of high-calorie diets (high-fat and high-fat-high-sucrose diets) and two different developmental stages (post-weaning and young adult) on the induction of metabolic syndrome. Male, post-weaning and adult (3- and 8-week old, respectively) Sprague Dawley rats were given control, high-fat (60% kcal), and high-fat-high-sucrose (60% kcal fat + 30% sucrose water) diets for eight weeks (n = 6 to 7 per group). Physical, biochemical, and transcriptional changes as well as liver histology were noted. Post-weaning rats had higher weight gain, abdominal fat mass, fasting glucose, high density lipoprotein cholesterol, faster hypertension onset, but lower circulating advanced glycation end products compared to adult rats. This is accompanied by upregulation of peroxisome proliferator-activated receptor (PPAR) α and γ in the liver and receptor for advanced glycation end products (RAGE) in the visceral adipose tissue. Post-weaning rats on high-fat diet manifested all phenotypes of metabolic syndrome and increased hepatic steatosis, which are linked to increased hepatic and adipocyte PPARγ expression. Adult rats on high-fat-high-sucrose diet merely became obese and hypertensive within the same treatment duration. Thus, it is more effective and less time-consuming to induce metabolic syndrome in male post-weaning rats with high-fat diet compared to young adult rats. As male rats were selectively included into the study, the results may not be generalisable to all post-weaning rats and further investigation on female rats is required.
  17. Infectiousness of HBsAg carriers in Malaysia
    Ton SH, Yeoh KS, Lim WC, Noriah R, Cheong SK, Thanaletchimy N
    J Trop Med Hyg, 1995 Aug;98(4):277-80.
    PMID: 7636926
    HBV-DNA were analysed in 330 HBsAg-positive carriers in Malaysia by dot-blot hybridization and polymerase chain reaction. Seventy-three (22.12%) were positive for the virus. Of these, 65 (89%) were males and 8 (11%) were females. Statistically, there was no significant difference (P = 0.13). No significant decline in HBV-DNA with age in the Malay and Chinese males was observed (P = 0.2). Prevalence of HBV-DNA was higher in the Chinese carriers than in the Malay carriers for most age groups in both sexes. Sixty-one HBV-DNA-positive carriers were also positive for HBeAg. However, three individuals were positive only for anti-HBe, one was positive for both HBeAg and anti-HBe, and eight were negative for both HBeAg and anti-HBe. Fifty-seven were positive for HBeAg but negative for HBV-DNA. No relation was observed between raised alanine aminotransaminase and aspartate aminotransaminase levels and the presence of HBV-DNA (P = 0.4).
  18. Fulltext Infectiousness with respect to HBV of medical staff and patients in the General Hospital, Kuala Lumpur
    Ton SH, Lopez CG, Cheong KS, Noriah R
    Singapore Med J, 1984 Aug;25(4):244-6.
    PMID: 6505725
    The infectiousness with regard to HBV Infection of staff and patients in various units of the General Hospital, Kuala Lumpur
    was assessed. It was found that all units, with the exception of the obstetric unit, were equally high risk areas. At least 50% of the patients in all these units had one or more of the markers. Among the medical staff, the anaesthetists had the highest
    incidence of HBV markers (100%) while medical officers who had worked for three years or more were more likely to have to
    have the HBV markers. The degree of infectiousness of the nurses In HDU and ICU/OT was found to be similar.
  19. Influence of race, age and sex on the lymphocyte subsets in peripheral blood of healthy Malaysian adults
    Choong ML, Ton SH, Cheong SK
    Ann. Clin. Biochem., 1995 Nov;32 ( Pt 6):532-9.
    PMID: 8579284
    The lymphocyte subsets in the peripheral blood of healthy Malaysian adults (212 subjects, age 18-71 years) were analysed using a flow cytometer FACScan in an effort to establish a reference range for the lymphocyte subsets. The lymphocyte subsets studied were T cells (CD3), B cells (CD19), natural killer (NK) cells (CD3- CD16+/CD56+), helper/inducer cells (CD4), cytotoxic/suppressor cells (CD8) and the helper/suppressor ratio (CD4/CD8). The distributions of T cells, CD4 cells and CD8 cells were symmetric about their means while B cells, NK cells and CD4/CD8 ratio followed a skewed distribution. Differences in race were observed for T cells, NK cells, CD4 cells and CD4/CD8 ratio where the Indians were significantly different from the Malays and the Chinese (higher T cells, CD4 cells and CD4/CD8 ratio and lower NK cells). The B cells were significantly lower in the Chinese than the Malays and the Indians. Age differences were seen only in the Chinese where increased CD4 cells and CD4/CD8 ratio, and decreased CD8 cells were observed. A sex difference was observed only in the Chinese where the CD4/CD8 ratio was significantly higher in females than males.
  20. Irregularities in glucose metabolism induced by stress and high-calorie diet can be attenuated by glycyrrhizic acid
    Yaw HP, Ton SH, Amanda S, Kong IG, Cheng HS, Fernando HA, et al.
    Int J Physiol Pathophysiol Pharmacol, 2014;6(4):172-84.
    PMID: 25755839
    Stress and high-calorie diet increase the risk of developing metabolic syndrome. Glycyrrhizic acid (GA) has been shown to improve hyperglycaemia and dyslipidaemia under various physiological conditions. This study was aimed at examining the effects of stress and GA on glucose metabolism under short- or long-term stress. Forty-eight Sprague Dawley rats were divided into two groups with constant stress induced by light (300-400 lux) for either 14 days (short-term stress) or 28 days (long-term stress). Within each group, the rats were subdivided into three treatment groups i.e. Group A (control group): high-calorie diet (HCD) only; Group B: HCD + stress (14 or 28 days) and Group C: HCD + stress (14 or 28 days) + GA (100 mg/kg). The blood glucose concentrations of the rats exposed to 14-day stress were elevated significantly and GA lowered blood glucose concentration significantly in the 14-day exposure group. The 28-day exposure group adapted to stress as shown by the lower adrenaline level and gluconeogenic enzymes activities in most of the tissues than the 14-day exposure group. With regards to adrenaline and corticosterone, GA was found to increased adrenaline significantly in the short-term exposure group while lowering corticosterone in the long-term exposure group. GA-treated short- and long-term exposure groups had significant reduction in hexose-6-phosphate dehydrogenase activities in the visceral adipose tissues and quadriceps femoris respectively. The results may indicate the role of GA in improving blood glucose concentration in individuals exposed to short-term stress who are already on a high-calorie diet via selective action on gluconeogenic enzymes in different tissues.
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