Displaying publications 1 - 20 of 29 in total

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  1. Taufiq-Yap, Y. H., Ong, P. S., Zainal, Z.
    MyJurnal
    In this work, 10 mol% yttrium-doped ceria powders, Ce0.9Y0.1O1.95, were synthesised using a new mechanical technique, mechanochemical reaction, in which both impact action and shearing forces were applied for efficient fine grinding, subsequently leading to higher homogeneity of the resultant powders. Ce0.9Y0.1O1.95 prepared using this new technique was systematically compared with a sample of the same prepared using conventional solid-state methodology. X-ray diffraction analysis showed all prepared samples were single phase with a cubic fluorite structure. Generally, Y2O3-doped CeO2 electrolytes prepared by mechanochemical reactions were stable at a lower temperature (1100 °C) compared with a sample of the same synthesised using the conventional solid-state method. Characterisations using differential thermal analysis (DTA) and thermogravimetric analysis (TGA) showed no thermal changes and phase transitions, indicating all materials were thermally stable. The electrical properties of the samples investigated by AC impedance spectroscopy in the temperature range 200–800 ˚C are presented and discussed. Scanning electron microscopy (SEM) was used to study the morphology of the materials. Fine-grained powders with uniform grain-size distribution were obtained from the mechanochemical reaction.
  2. Yap YF, Puthucheary SD
    Singapore Med J, 1998 Jun;39(6):260-2.
    PMID: 9803814
    Typhoid fever, which is endemic in Malaysia, affects all age groups and it has been stated that classical features described in textbooks were absent in children. The aim of this study was to find out whether this was true in the local setting and hence a retrospective study was undertaken.
  3. Ee GC, Daud S, Taufiq-Yap YH, Ismail NH, Rahmani M
    Nat Prod Res, 2006 Oct;20(12):1067-73.
    PMID: 17127660
    Studies on the stem of Garcinia mangostana have led to the isolation of one new xanthone mangosharin (1) (2,6-dihydroxy-8-methoxy-5-(3-methylbut-2-enyl)-xanthone) and six other prenylated xanthones, alpha-mangostin (2), beta-mangostin (3), garcinone D (4), 1,6-dihydroxy-3,7-dimethoxy-2-(3-methylbut-2-enyl)-xanthone (5), mangostanol (6) and 5,9-dihydroxy-8- methoxy-2,2-dimethyl-7-(3-methylbut-2-enyl)-2H,6H-pyrano-[3,2-b]-xanthene-6-one (7). The structures of these compounds were determined by spectroscopic methods such as 1H NMR, 13C NMR, mass spectrometry (MS) and by comparison with previous studies. All the crude extracts when screened for their larvicidal activities indicated very good toxicity against the larvae of Aedes aegypti. This article reports the isolation and identification of the above compounds as well as bioassay data for the crude extracts. These bioassay data have not been reported before.
  4. Khoo JJ, Pee S, Thevarajah B, Yap YC, Chin CK
    J Paediatr Child Health, 2005 Jan-Feb;41(1-2):31-5.
    PMID: 15670221 DOI: 10.1111/j.1440-1754.2005.00532.x
    OBJECTIVES: To determine the pattern of renal histology, clinical outcome of children with lupus nephritis and to identify any associated risk factors predicting renal failure in these children.
    METHODS: Retrospectively, 27 children under 16 years of age with lupus nephritis who had renal biopsies done at Sultanah Aminah Hospital Johor, Malaysia from 1994 to 2002 were studied. The renal histology was graded according to WHO classification system (1982). The medical records, laboratory data and the clinical outcome of the patients were studied.
    RESULTS: There were 24 cases of WHO Class IV, two cases of WHO Class II and a case of WHO Class V. Twenty children were in the good renal outcome group while six children progressed into the poor renal outcome group and required renal replacement. One child was lost to follow-up. All six children in the poor renal outcome group had WHO Class IV histology. The 5-year patient and renal survival rates were 84% and 75%, respectively. Age, sex, activity and chronicity indices in the renal histology, anaemia, elevated serum creatinine, depressed levels of C3 and C4, heavy proteinuria or presence of urinary active sediments were not associated with progression to renal failure.
    CONCLUSIONS: Presently, children with lupus nephritis appeared to have better patient and renal survival rates. Assessment of renal histology in these children was important for diagnosis, treatment and probably prognosis. In this study, there was a 25% incidence of loss of renal function over 5 years in children with WHO Class IV renal histology.
  5. Khoo JJ, Pee S, Thevarajah B, Yap YC, Chin CK
    Med J Malaysia, 2004 Jun;59(2):218-25.
    PMID: 15559173 MyJurnal
    Background: There has been no published study of biopsy proven childhood glomerulonephritis in Malaysia.
    Objectives: To determine the pattern of childhood glomerulonephritis in Johor, Malaysia from a histopathological perspective and the various indications used for renal biopsy in children.
    Materials and methods: Retrospective study was done of all renal biopsies from children under 16 years of age, received in Sultanah Aminah Hospital, Johor between 1994 and 2001. The histopathological findings were reviewed to determine the pattern of biopsy proven glomerulonephritis. The indications of biopsy, mode of therapy given after biopsy and the clinical outcome were studied.
    Results: 123 adequate biopsies were received, 9 children had repeated biopsies. Of the 113 biopsies, minimal change disease formed the most common histopathological diagnosis (40.7%) while lupus nephritis formed the most common secondary glomerulonephritis (23.0%). The main indications for biopsy were nephrotic syndrome (50.8%), lupus nephritis (25.4%) and renal impairment (13.1%). The mode of therapy was changed in 59.8% of the children. Of 106 patients followed up, 84 children were found to have normal renal function in remission or on treatment. 4 patients developed chronic renal impairment and 16 reached end stage renal disease. Five of the 16 children with end stage disease had since died while 11 were on renal replacement therapy. another 2 patients died of other complications.
    Conclusions: The pattern of childhood GN in our study tended to reflect the more severe renal parenchymal diseases in children and those requiring more aggressive treatment. This was because of our criteria of selection (indication) for renal biopsy. Renal biopsy where performed appropriately in selected children may not only be a useful investigative tool for histological diagnosis and prognosis but may help clinicians plan the optimal therapy for these children.
  6. Lim CT, Wong KK, Yap YF, Sivanesaratnam V
    Asia Oceania J Obstet Gynaecol, 1992 Mar;18(1):19-22.
    PMID: 1627057
    Large ovarian cysts in the fetus are uncommon. Ultrasonography has helped in the detection of these cysts antenatally and in the newborn female infant. A case of bilateral ovarian cysts in a newborn is presented. The choice of management between conservative measures and surgical approaches remains controversial.
  7. Karmila AB, Yap YC, Appadurai M, Oh L, Fazarina M, Abd Ghani F, et al.
    Fetal Pediatr Pathol, 2021 Apr;40(2):113-120.
    PMID: 31707902 DOI: 10.1080/15513815.2019.1686788
    Introduction: Denys-Drash Syndrome (DDS) consists of a triad of pseudohermaphroditism, Wilms'tumor and nephropathy. This condition may manifest as a complete triad or in an incomplete form; with either one or a combination of the above features. The characteristic glomerular abnormality in DDS is diffuse mesangial sclerosis (DMS).Case report: We report two cases of DDS with focal membranoproliferative glomerulonephritis (MPGN). Both of our cases were males with ambiguous genitalia. They had a similar heterozygous germline mutation in exon 9 of WT1, c.1180C>T, p.R394W; a known mutation hotspot for DDS. Case 1 had nephropathy at the age of 4 years and Case 2 at 2.5 years with different rates of progression to end-stage renal failure. Conclusion: Our findings, in combination with other reports, illustrate the clinicopathological heterogeneity of DDS. There are no universal recommendations for optimal management of patients with DDS due to the inability to accurately predict affected individuals' progress.
  8. Chin YH, Yap YL, Chin HH, Lau BK
    Med J Malaysia, 2021 07;76(4):606-609.
    PMID: 34305132
    Madam LPS, a 69 years old lady complained of left eye blurring of vision since January 2017. It was associated with left orbital swelling with chemosis, eye redness, epiphora, several episodes of self-limiting epistaxis and bilateral ophthalmoplegia. Other neurological examinations and cerebellar systems were intact. Magnetic Resonance Imaging (MRI) Brain and Orbit were performed, depicting a sellar mass with suprasellar extension with blood investigations results showed panhypopituitarism. She underwent bilateral orbital decompression. Trans-nasal endoscopic biopsy showed suppurative granulomatous lesion, which cultured Candida Albicans and Candida Galbrata. She was started on antifungal and hormonal replacement therapy for panhypopituitarism. Unfortunately, she did not respond well to treatment as repeated MRI Brain on December 2018 showed increase in size of sellar mass causing obstructive hydrocephalus and increasing size of left orbital lesion. She was counselled for another debulking surgery with a ventriculoperitoneal (VP) shunt. HPE taken were reported as chronic inflammatory process in favour to fungal infection. Pituitary infections may mimic pituitary mass. Some may exhibit symptoms of panhypopituitarism as well. Thus, physical examination, MRI brain imaging as well as HPE of biopsy are important aids to achieve diagnosis. Optimal treatment of fungal pituitary abscess includes transsphenoidal surgery combined with antifungal therapy.
  9. Chin YH, Yap YL, Chin HH, Sarina S
    Med J Malaysia, 2021 07;76(4):600-602.
    PMID: 34305130
    The thyroid gland and its hormones play important roles in organ development and in the homeostatic control of physiological mechanisms in human beings. As a result of embryogenic descent of thyroid gland, it commonly resides along the midline - from tongue to mediastinum (90%). Ectopic thyroid gland is a rare occurrence, with extra-lingual ectopic thyroid gland being even rarer. Thus, there is a concern for malignant metastasis. Madam H, a 56-year-old healthy woman presented to the Hospital Sultanah Nora Ismail, Johor, Malaysia in April 2020 with an increasing size of right axilla mass and history of weight loss. She was having right axilla mass for the previous 7 years but only noticed the increase in size about 1 year ago. She has no other constitutional symptoms. A tru-cut biopsy performed demonstrated a benign ectopic thyroid tissue. Thyroid function test showed primary hypothyroidism. Serum Chromogranin A and other thyroid antibodies were within the normal value. Further radiological imaging showed the normal thyroid gland at neck, with no signs of distant malignancy. There was no other axillary, mediastinal or hilar lymph node enlargement. She was started on regular T. L Thyroxine 100mcg daily and given regular follow-up in endocrine clinic. Benign ectopic thyroid gland is an unusual finding. As such, follow up is needed with possibility of carcinomatous transformation such as papillary carcinoma should be considered.
  10. Habsah M, Ali A, Lajis N, Sukari M, Yap Y, Kikuzaki H, et al.
    Malays J Med Sci, 2005 Jan;12(1):6-12.
    PMID: 22605941
    Phytochemical studies on rhizome of Etlingera elatior have resulted in the isolation of 1,7-bis(4-hydroxyphenyl)-2,4,6-heptatrienone (1), demethoxycurcumin (2), 1,7-bis(4-hydroxyphenyl)-1,4,6-heptatrien-3-one (3), 16-hydroxylabda-8(17),11,13-trien-16,15-olide (4), stigmast-4-en-3-one (5), stigmast-4-ene-3,6-dione (6), stigmast-4-en-6b-ol-3-one (7), 5α,8α-epidioxyergosta-6,22-dien-3β-ol (8). 1 and 4 were new compounds. Compounds 5 and 7 displayed high antitumour-promoting activity. Ethyl acetate extract showed a very significant cytotoxic activity against CEM-SS and MCF-7 cell lines (4 μg/ml and 6.25 μg/ml respectively). The antitumour-promoting activity was determined by EBV-EA assay and cytotoxic activity was determined by MTT assay.
  11. Lee Chin K, Ling Yap Y, Leng Lee W, Chang Soh Y
    Am J Pharm Educ, 2014 Oct 15;78(8):153.
    PMID: 25386018 DOI: 10.5688/ajpe788153
    To determine whether human patient simulation (HPS) is superior to case-based learning (CBL) in teaching diabetic ketoacidosis (DKA) and thyroid storm (TS) to pharmacy students.
  12. Tham YJ, Latif PA, Abdullah AM, Shamala-Devi A, Taufiq-Yap YH
    Bioresour Technol, 2011 Jan;102(2):724-8.
    PMID: 20884200 DOI: 10.1016/j.biortech.2010.08.068
    In the effort to find alternative low cost adsorbent for volatile organic vapors has prompted this research in assessing the effectiveness of activated carbon produced from durian shell in removing toluene vapors. Durian shells were impregnated with different concentrations of H3PO4 followed by carbonization at 500 °C for 20 min under nitrogen atmosphere. The prepared durian shell activated carbon (DSAC) was characterized for its physical and chemical properties. The removal efficiency of toluene by DSAC was performed using different toluene concentrations. Results showed that the highest BET surface area of the produced DSAC was 1404 m2/g. Highest removal efficiency of toluene vapors was achieved by using DSAC impregnated with 30% of acid concentration heated at 500 °C for 20 min heating duration. However, there is insignificant difference between removal efficiency of toluene by DSAC and different toluene concentrations. The toluene adsorption by DSAC was better fitted into Freundlich model.
  13. Pua KC, Khoo AS, Yap YY, Subramaniam SK, Ong CA, Gopala Krishnan G, et al.
    Med J Malaysia, 2008 Sep;63 Suppl C:59-62.
    PMID: 19230249
    Nasopharyngeal carcinoma (NPC) is a cancer which is common in Asia. We report the establishment and early results of a multi-institutional prospective study of nasopharyngeal carcinoma, which seeks to systematically collect data as well as blood and tumour tissue samples from patients diagnosed with nasopharyngeal cancer at six centres in Malaysia. A total of 484 confirmed NPC cases were reported from the six participating centres between 1st July 2007 and 29th February 2008. Of these, 225 were newly diagnosed cases, 53 were recurrent cases and 206 were in remission at the time of reporting. Amongst the newly diagnosed cases, the most common presenting symptom was the presence of neck lumps (42%). Ophthalmo-neurologic symptoms were the presenting symptoms of 11% of the new cases. The majority of cases (75%) presented at stage III/IV.
  14. Yahya R, Bavanandan S, Yap YC, Jazilah W, Shaariah W, Wong HS, et al.
    Med J Malaysia, 2008 Sep;63 Suppl C:18-9.
    PMID: 19230242
  15. Taufiq-Yap YH, Peh TH, Ee GC, Rahmani M, Sukari MA, Ali AM, et al.
    Nat Prod Res, 2007 Jul 20;21(9):810-3.
    PMID: 17654285
    A new carbazole alkaloid, 3-carbomethoxy-2-hydroxy-7-methoxycarbazole, Clausine-TY (1), together with two known carbazole alkaloid, Clausine-H (2) and Clausine-B (3), were isolated from the ethyl acetate extract of the stem bark of the Malaysian Clausena excavata. The structures of these compounds were elucidated by spectroscopic analyses. The new carbazole alkaloid shows significant cytotoxicity against CEM-SS cell line.
  16. Chong WY, Lim WH, Yap YK, Lai CK, De La Rue RM, Ahmad H
    Sci Rep, 2016 Apr 01;6:23813.
    PMID: 27034015 DOI: 10.1038/srep23813
    Increased absorption of transverse-magnetic (TM)-polarised light by a graphene-oxide (GO) coated polymer waveguide has been observed in the presence of transverse-electric (TE)-polarised light. The GO-coated waveguide exhibits very strong photo-absorption of TE-polarised light--and acts as a TM-pass waveguide polariser. The absorbed TE-polarised light causes a significant temperature increase in the GO film and induces thermal reduction of the GO, resulting in an increase in optical-frequency conductivity and consequently increased optical propagation loss. This behaviour in a GO-coated waveguide gives the action of an inverted optical switch/modulator. By varying the incident TE-polarised light power, a maximum modulation efficiency of 72% was measured, with application of an incident optical power level of 57 mW. The GO-coated waveguide was able to respond clearly to modulated TE-polarised light with a pulse duration of as little as 100 μs. In addition, no wavelength dependence was observed in the response of either the modulation (TE-polarised light) or the signal (TM-polarised light).
  17. Chow KW, Ting HC, Yap YP, Yee KC, Purushotaman A, Subramanian S, et al.
    Int J Dermatol, 1998 Jun;37(6):446-8.
    PMID: 9646134
  18. Sinniah D, Sinniah R, Yap YF, Singh M, George R, Lim NL, et al.
    Acta Paediatr Jpn, 1990 Aug;32(4):385-90.
    PMID: 2288220
    A pilot epidemiologic study of all cases of Reye and Reye-like syndromes was undertaken at 8 representative major hospitals in Peninsular Malaya from January 1st to December 31st 1986. The cases were classified as definitive Reye's syndrome, clinical Reye's syndrome and encephalo-hepatopathies. Less than 50% of cases reviewed fulfilled the National Center for Disease Control criteria for clinical Reye's syndrome. Causes of Reye-like syndromes/encephalo-hepatopathies included fulminant hepatitis, Japanese B encephalitis, dengue, septicaemia, and complex febrile fits. It was not possible to differentiate clinical Reye's syndrome from the other encephalo-hepatopathies by either the clinical features (except for jaundice) or biochemical parameters. Liver biopsy is necessary for a definitive diagnosis of Reye's syndrome in Malaysia, because of the high prevalence of Reye-like diseases. The mortality rate in the 2 groups of patients is similar. Ingestion of salicylates was not found to be significantly associated with Reye and Reye-like syndromes in this study.
  19. Ee GC, Ng KN, Taufiq-Yap YH, Rahmani M, Ali AM, Muse R
    Nat Prod Res, 2004 Apr;18(2):123-8.
    PMID: 14984084
    Our recent studies on the stem bark of Calophyllum mucigerum (Guttiferae) have yielded a new coumarin mucigerin, a prenylated xanthone cudraxanthone C and the common steroidal triterpenes friedelin and stigmasterol. Structural elucidations of these compounds were achieved using 1H NMR, 13C NMR, DEPT, COSY, HETCOR and HMBC experiments while MS gave the molecular masses. Cytotoxic assays using CEM-SS cell line (T-lymphoblastic leukemia) on the crude extracts of the stem bark indicated some activity. The crude extracts were also found to be moderately toxic against the larvae of Aedes aegypti. This article reports the isolation and identification of mucigerin as well as bioassay data.
  20. Tiong TJ, Chu JK, Lim LY, Tan KW, Hong Yap Y, Asli UA
    Ultrason Sonochem, 2019 Sep;56:46-54.
    PMID: 31101285 DOI: 10.1016/j.ultsonch.2019.03.026
    In the field of ultrasonic emulsification, the formation and cavitation collapse is one major factor contributing to the formation of micro- and nano-sized emulsion droplets. In this work, a series of experiments were conducted to examine the effects of varying the ultrasonic horn's position to the sizes of emulsion droplets formed, in an attempt to compare the influence of the simulated acoustic pressure fields to the experimental results. Results showed that the intensity of the acoustic pressure played a vital role in the formation of smaller emulsion droplets. Larger areas with acoustic pressure above the cavitation threshold in the water phase have resulted in the formation of smaller emulsion droplets ca. 250 nm and with polydispersity index of 0.2-0.3. Placing the ultrasonic horn at the oil-water interface has hindered the formation of small emulsion droplets, due to the transfer of energy to overcome the interfacial surface tension of oil and water, resulting in a slight reduction in the maximum acoustic pressure, as well as the total area with acoustic pressures above the cavitation threshold. This work has demonstrated the influence of the position of the ultrasonic horn in the oil and water system on the final emulsion droplets formed and can conclude the importance of generating acoustic pressure above the cavitation threshold to achieve small and stable oil-in-water emulsion.
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