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  1. Fulltext Oil palm (Elaeis guineensis Jacq.) tissue culture ESTs: identifying genes associated with callogenesis and embryogenesis
    Low ET, Alias H, Boon SH, Shariff EM, Tan CY, Ooi LC, et al.
    BMC Plant Biol, 2008 May 29;8:62.
    PMID: 18507865 DOI: 10.1186/1471-2229-8-62
    BACKGROUND: Oil palm (Elaeis guineensis Jacq.) is one of the most important oil bearing crops in the world. However, genetic improvement of oil palm through conventional breeding is extremely slow and costly, as the breeding cycle can take up to 10 years. This has brought about interest in vegetative propagation of oil palm. Since the introduction of oil palm tissue culture in the 1970s, clonal propagation has proven to be useful, not only in producing uniform planting materials, but also in the development of the genetic engineering programme. Despite considerable progress in improving the tissue culture techniques, the callusing and embryogenesis rates from proliferating callus cultures remain very low. Thus, understanding the gene diversity and expression profiles in oil palm tissue culture is critical in increasing the efficiency of these processes.

    RESULTS: A total of 12 standard cDNA libraries, representing three main developmental stages in oil palm tissue culture, were generated in this study. Random sequencing of clones from these cDNA libraries generated 17,599 expressed sequence tags (ESTs). The ESTs were analysed, annotated and assembled to generate 9,584 putative unigenes distributed in 3,268 consensi and 6,316 singletons. These unigenes were assigned putative functions based on similarity and gene ontology annotations. Cluster analysis, which surveyed the relatedness of each library based on the abundance of ESTs in each consensus, revealed that lipid transfer proteins were highly expressed in embryogenic tissues. A glutathione S-transferase was found to be highly expressed in non-embryogenic callus. Further analysis of the unigenes identified 648 non-redundant simple sequence repeats and 211 putative full-length open reading frames.

    CONCLUSION: This study has provided an overview of genes expressed during oil palm tissue culture. Candidate genes with expression that are modulated during tissue culture were identified. However, in order to confirm whether these genes are suitable as early markers for embryogenesis, the genes need to be tested on earlier stages of tissue culture and a wider range of genotypes. This collection of ESTs is an important resource for genetic and genome analyses of the oil palm, particularly during tissue culture development.

  2. Sintering behaviour of hydroxyapatite bioceramics
    Ramesh S, Tan CY, Aw KL, Yeo WH, Hamdi M, Sopyan I, et al.
    Med J Malaysia, 2008 Jul;63 Suppl A:89-90.
    PMID: 19024998
    The sintering behaviour of a commercial HA and synthesized HA was investigated over the temperature range of 700 degrees C to 1400 degrees C in terms of phase stability, bulk density, Young's modulus and Vickers hardness. In the present research, a wet chemical precipitation reaction was successfully employed to synthesize a submicron, highly crystalline, high purity and single phase stoichiometric HA powder that is highly sinteractive particularly at low temperature regimes below 1100 degrees C. It has been revealed that the sinterability of the synthesized HA was significantly greater than that of the commercial HA. The temperature for the onset of sintering and the temperature required to achieve densities above 98% of theoretical value were approximately 150 degrees C lower for the synthesized HA than the equivalent commercial HA. Nevertheless, decomposition of HA phase upon sintering was not observed in the present work for both powders.
  3. Effect of powder calcination on the sintering of hydroxyapatite
    Tan CY, Ramesh S, Aw KL, Yeo WH, Hamdi M, Sopyan I
    Med J Malaysia, 2008 Jul;63 Suppl A:87-8.
    PMID: 19024997
    The sintering behaviour of synthesized HA powder that was calcined at various temperatures ranging from 700 degrees C to 1000 degrees C was investigated in terms of phase stability, bulk density, Young's modulus and Vickers hardness. The calcination treatment resulted in higher crystallinity of the starting HA powder. Decomposition of HA phase to form secondary phases was not observed in all the calcined powders. The results also indicated that powder calcination (up to 900 degrees C) prior to sintering has negligible effect on the sinterability of the HA compacts. However, powder calcined at 1000 degrees C was found to be detrimental to the properties of sintered hydroxyapatite bioceramics.
  4. Conformational destabilization of Bacillus licheniformis α-amylase induced by lysine modification and calcium depletion
    Tan CY, Rahman RN, Kadir HA, Tayyab S
    Acta Biochim. Pol., 2011;58(3):405-12.
    PMID: 21887412
    Bacillus licheniformis α-amylase (BLA) was chemically modified using 100-fold molar excess of succinic anhydride over protein or 0.66 M potassium cyanate to obtain 42 % succinylated and 81 % carbamylated BLAs. Size and charge homogeneity of modified preparations was established by Sephacryl S-200 HR gel chromatography and polyacrylamide gel electrophoresis. Conformational alteration in these preparations was evident by the larger Stokes radii (3.40 nm for carbamylated and 3.34 nm for succinylated BLAs) compared to 2.43 nm obtained for native BLA. Urea denaturation results using mean residue ellipticity (MRE) as a probe also showed conformational destabilization based on the early start of transition as well as ΔG(D)(H(2)O) values obtained for both modified derivatives and Ca-depleted BLA. Decrease in ΔG(D)(H(2)O) value from 5,930 cal/mol (for native BLA) to 3,957 cal/mol (for succinylated BLA), 3,336 cal/mol (for carbamylated BLA) and 3,430 cal/mol for Ca-depleted BLA suggested reduced conformational stability upon modification of amino groups of BLA or depletion of calcium. Since both succinylation and carbamylation reactions abolish the positive charge on amino groups (both α- and ε- amino), the decrease in conformational stability can be ascribed to the disruption of salt bridges present in the protein which might have released the intrinsic calcium from its binding site.
  5. Sensory nerves are frequently involved in the spectrum of fisher syndrome
    Shahrizaila N, Goh KJ, Kokubun N, Tan AH, Tan CY, Yuki N
    Muscle Nerve, 2014 Apr;49(4):558-63.
    PMID: 23893512 DOI: 10.1002/mus.23973
    Differing patterns of neurophysiological abnormalities have been reported in patients with Fisher syndrome. Fisher syndrome is rare, and few series have incorporated prospective serial studies to define the natural history of nerve conduction studies in Guillain-Barré syndrome.
  6. Short homologies efficiently generate detectable homologous recombination events
    Osahor AN, Tan CY, Sim EU, Lee CW, Narayanan K
    Anal Biochem, 2014 Oct 1;462:26-8.
    PMID: 24929088 DOI: 10.1016/j.ab.2014.05.030
    When recombineering bacterial artificial chromosomes (BACs), it is common practice to design the ends of the donor molecule with 50 bp of homology specifying its insertion site. We demonstrate that desired recombinants can be produced using intermolecular homologies as short as 15 bp. Although the use of shorter donor end regions decreases total recombinants by several fold, the frequency of recombinants with correctly inserted donor molecules was high enough for easy detection by simple polymerase chain reaction (PCR) screening. This observation may have important implications for the design of oligonucleotides for recombineering, including significant cost savings, especially for high-throughput projects that use large quantities of primers.
  7. Delayed facial palsy in Miller Fisher syndrome
    Tan CY, Yuki N, Shahrizaila N
    J Neurol Sci, 2015 Nov 15;358(1-2):409-12.
    PMID: 26277343 DOI: 10.1016/j.jns.2015.08.009
    Miller Fisher syndrome is characterised by the triad of ophthalmoplegia, ataxia and areflexia. However, facial palsy can occur during the course of the illness although development of facial palsy when other cardinal signs of Miller Fisher syndrome have reached nadir or improving, is unusual. This delayed appearance of facial palsy can be easily overlooked by the treating clinician. Here, we report four patients with Miller Fisher syndrome and delayed-onset facial palsy. We discuss the possible underlying reasons behind the delay in facial palsy.
  8. Fulltext Evaluation of locomotor function and microscopic structure of the spinal cord in a mouse model of experimental autoimmune encephalomyelitis following treatment with syngeneic mesenchymal stem cells
    Mitra NK, Bindal U, Eng Hwa W, Chua CL, Tan CY
    Int J Clin Exp Pathol, 2015;8(10):12041-52.
    PMID: 26722389
    Out of the minor myelin proteins, most significant one is myelin oligodendrocyte glycoprotein (MOG). Mesenchymal stem cells (MSCs) have proven immunoregulatory capacity. The objective of this study was to investigate the effects of syngeneic MSCs on mouse model of experimental autoimmune encephalomyelitis (EAE) through observation of locomotion by footprint analysis, histological analysis of spinal cord and estimation IL-17. C57BL/6 mice (10 weeks, n = 16) were immunized with 300 µg of MOG35-55 and 200 µL of complete Freund's adjuvant (CFA) to produce EAE model. Sham-treated control (n = 8) were injected with CFA. Half of immunized mice were given 100 µL of PBS (n = 8) and next half (n = 8) received 1 × 10(5) MSCs on day 11 through the tail veins. Clinical scoring showed development of EAE (loss of tonicity of tail and weakness of hind limb) on day 10. Following MSC treatment, clinical scores and hindlimb stride length showed significant improvement on day 15 onwards, compared to day 10 (P < 0.05). Under LFB staining, while PBS-treated group of EAE mice showed pale and degenerated axons in anterolateral white column of lumbar spinal cord, MSC-treated group showed numerous normal-looking axons. H&E staining showed normal axons in anterolateral white column and reduction of macrophages in MSC-treated EAE mice group. A lower level of IL-17 was observed in MSC treated EAE mice, compared to PBS-treated EAE mice. Our results suggest that Intravenous MSC has the potential to improve the locomotion and regeneration of axons in spinal cord in MOG-induced EAE model.
  9. "Ictal catatonia": Rare but not to be missed!
    Tan AH, Low SC, Tan CY, Lim KS, Tan CT, Lim SY
    Parkinsonism Relat Disord, 2016 11;32:137-139.
    PMID: 27688197 DOI: 10.1016/j.parkreldis.2016.09.019
  10. Influence of Buffer Composition and Calcium Chloride on GdnHCl Denaturation of Bacillus licheniformis α-Amylase
    Kandandapani S, Tan CY, Shuib AS, Tayyab S
    Protein Pept Lett, 2016;23(6):537-43.
    PMID: 26936029
    The influence of buffer composition on the conformational stability of native and calciumdepleted Bacillus licheniformis α-amylase (BLA) was investigated against guanidine hydrochloride (GdnHCl) denaturation using circular dichroism, fluorescence and UV-difference spectroscopy. Differential effect of buffer composition on GdnHCl denaturation of BLA was evident from the magnitude of these spectral signals, which followed the order: sodium phosphate > Tris-HCl > HEPES > MOPS. These effects became more pronounced with calcium-depleted BLA. Sephacryl S-200 gel chromatographic results showed significant BLA aggregation in the presence of 6 M GdnHCl.
  11. Prevalence and associations of neuropathic pain in a cohort of multi-ethnic Asian low back pain patients
    Kew Y, Tan CY, Ng CJ, Thang SS, Tan LH, Khoo YK, et al.
    Rheumatol Int, 2017 Apr;37(4):633-639.
    PMID: 28013358 DOI: 10.1007/s00296-016-3633-x
    The prevalence of neuropathic low back pain differs in different ethnic populations. The aims of the study are to determine its frequency and associations in a multi-ethnic cohort of Asian low back pain patients. This was a cross-sectional study of low back patients seen at the University of Malaya Medical Centre, Kuala Lumpur, Malaysia. Neuropathic low back pain patients were identified using the painDETECT questionnaire and compared with non-neuropathic (unclear or nociceptive) low back pain patients, in terms of socio-demographic and clinical factors, pain severity (numerical pain rating scale, NPRS), disability (Roland Morris Disability Questionnaire, RMDQ), as well as anxiety and depression (Hospital Anxiety and Depression Scale, HADS). Of 210 patients, 26 (12.4%) have neuropathic low back pain. Neuropathic pain is associated with non-Chinese ethnicity, higher body mass index and pain radiation below the knee. Patients with neuropathic pain have significantly higher NPRS and RMDQ scores, and there are more subjects with anxiety on HADS. However, there are no differences between the groups in age, gender, pain duration or underlying diagnosis of low back pain. The prevalence of neuropathic low back pain in a multi-ethnic Malaysian cohort is lower than previously reported in other populations with possible differences between ethnic groups. It is associated with greater pain severity, disability and anxiety.
    Study site: Spine Clinic, University of Malaya Medical Centre (UMMC), Kuala Lumpur, Malaysia
  12. Clinical Characteristics, Pain, and Quality of Life Experiences of Trigeminal Neuralgia in a Multi-Ethnic Asian Cohort
    Tan CY, Shahrizaila N, Goh KJ
    J Oral Facial Pain Headache, 2017 10 27;31(4):e15-e20.
    PMID: 29073667 DOI: 10.11607/ofph.1793
    AIMS: To describe the clinical characteristics of trigeminal neuralgia (TN) in a multi-ethnic Malaysian population and to relate them to standardized measures of pain severity, anxiety, depression, and quality of life (QoL).

    METHODS: Patients fulfilling the International Headache Society (IHS) criteria for TN were prospectively interviewed for their demographic and clinical data. Pain intensity was rated with a visual analog scale (VAS), anxiety and depression were determined by the Hospital Anxiety and Depression Scale (HADS), and QoL was assessed by the Short-Form 36 (SF-36) questionnaire. Chi-square, Mann-Whitney U, and Spearman correlation tests were used to test for differences considering a significance level of P < .05.

    RESULTS: Of the 75 included patients, 52 (69.3%) were women with a mean ± standard deviation (SD) onset age of 52.0 ± 12.7 years, and 57.3% were Chinese, 24.0% Malay, and 18.7% Indian. Pain was more common on the right side (69.3%) and in the maxillary and mandibular divisions. VAS scores for pain at its worst were higher in anxious/borderline anxious patients compared to non-anxious patients (89.5 ± 15.9 vs 80.9 ± 17.2, respectively; P < .05), and VAS scores for pain at its least were higher in depressed/borderline depressed subjects compared to non-depressed subjects (38.4 ± 25.8 vs 23.0 ± 19.2, respectively; P < .05). Chinese patients had lower VAS scores for pain at its least compared to Indian patients (19.7 ± 16.1 vs 39.9 ± 24.7; P < .01). TN patients scored lower in all eight domains of the SF-36 compared to the general population. Indian patients had lower scores in role limitations due to physical health (8.9 ± 23.2 vs 49.4 ± 43.8; P < .01) and social function (56.3 ± 13.6 vs 76.5 ± 23.6; P < .01) than Chinese patients, and Malay patients had lower mental health scores compared to Chinese patients (59.1 ± 19.5 vs 73.0 ± 21.0; P < .01).

    CONCLUSION: Clinical characteristics of TN patients were similar to those of other populations. There were differences in pain ratings and QoL between TN patients of different ethnicities, as well as between those with anxiety and depression.

  13. Fulltext Overlap of Bickerstaff brainstem encephalitis/Guillain-Barré syndrome simulating brain death
    Tan CY, Ahmad SB, Goh KJ, Latif LA, Shahrizaila N
    Neurol India, 2018 9 21;66(5):1475-1480.
    PMID: 30233023 DOI: 10.4103/0028-3886.241342
  14. Nerve ultrasound can distinguish chronic inflammatory demyelinating polyneuropathy from demyelinating diabetic sensorimotor polyneuropathy
    Tan CY, Arumugam T, Razali SNO, Yahya MA, Goh KJ, Shahrizaila N
    J Clin Neurosci, 2018 Nov;57:198-201.
    PMID: 30145079 DOI: 10.1016/j.jocn.2018.08.031
    Diabetic patients with poor glycaemic control can demonstrate demyelinating distal sensorimotor polyneuropathy (D-DSP) on electrophysiology. Distinguishing D-DSP from chronic inflammatory demyelinating polyneuropathy (CIDP) can be challenging. In this study, we investigated the role of nerve ultrasound in differentiating the two neuropathies. Nerve ultrasound findings of D-DSP patients (fulfilling the electrophysiological but not clinical criteria for CIDP) were compared with non-diabetic CIDP patients (fulfilling both criteria). We studied 108 and 95 nerves from 9 D-DSP and 10 CIDP patients respectively. CIDP patients had significantly larger cross-sectional areas of the median nerve at the mid-arm (17.0 ± 12.5 vs 8.7 ± 2.6; p = 0.005), ulnar nerve at the wrist (7.3 ± 3.1 vs 4.1 ± 1.0; p = 0.001), mid forearm (8.8 ± 5.3 vs 5.5 ± 1.5; p = 0.002) and mid-arm (14.5 ± 14.1 vs 7.5 ± 1.9; p = 0.013), and radial nerve at mid forearm (4.1 ± 2.4 vs 1.2 ± 0.4; p 
  15. Heart rate variability and baroreflex sensitivity abnormalities in Guillain-Barré syndrome: a pilot study
    Tan CY, Shahrizaila N, Yeoh KY, Goh KJ, Tan MP
    Clin Auton Res, 2019 06;29(3):339-348.
    PMID: 29654380 DOI: 10.1007/s10286-018-0525-z
    OBJECTIVE: The current study aimed to investigate autonomic dysfunction in Guillain-Barré syndrome (GBS) patients and describe the results of computational heart rate variability (HRV)/baroreflex sensitivity (BRS) and autonomic challenge tests.

    METHODS: GBS patients were consecutively recruited and the results were compared to age- and gender-matched healthy controls. A series of autonomic function tests including computation-dependent tests (power spectrum analysis of HRV and BRS at rest) and challenge maneuvers (deep breathing, eyeball compression, active standing, the Valsalva maneuver, sustained handgrip, and the cold pressor test) were performed.

    RESULTS: Ten GBS patients (six men; mean age = 40.1 ± 13.9 years) and ten gender- and age-matched healthy controls were recruited. The mean GBS functional grading scale at disease plateau was 3.4 ± 1.0. No patients required intensive care unit admission or mechanical ventilation. Low-frequency HRV (p = 0.027), high-frequency HRV (p = 0.008), and the total power spectral density of HRV (p = 0.015) were significantly reduced in patients compared to controls. The mean up slope (p = 0.034), down slope (p = 0.011), and total slope (p = 0.024) BRS were significantly lower in GBS patients. The diastolic rise in blood pressure in the cold pressor test was significantly lower in GBS patients compared to controls (p = 0.008).

    INTERPRETATION: Computation-dependent tests (HRV and BRS) were more useful for detecting autonomic dysfunction in GBS patients, whereas the cold pressor test was the only reliable challenge test, making it useful as a bedside measure of autonomic function in GBS patients.

  16. The utility of Guillain-Barré syndrome prognostic models in Malaysian patients
    Tan CY, Razali SNO, Goh KJ, Shahrizaila N
    J Peripher Nerv Syst, 2019 06;24(2):168-173.
    PMID: 31001904 DOI: 10.1111/jns.12320
    Guillain-Barré syndrome (GBS) is an acute immune-mediated neuropathy that has variable disease course and outcome. The Erasmus GBS outcome score (EGOS), modified EGOS (mEGOS), and Erasmus GBS respiratory insufficiency score (EGRIS) are prognostic models designed to predict the functional outcome of GBS patients at 6 months (EGOS and mEGOS) and the need for mechanical ventilation within a week of admission (EGRIS). The models were primarily developed in the Dutch GBS population, and thus the usefulness of these models in other GBS cohorts is less clear. In the current study, we aimed to validate mEGOS, EGOS, and EGRIS in Malaysian GBS patients. A total of 107 patients with GBS and its variants were consecutively recruited. Patients with GBS and Miller Fisher syndrome (MFS) were analysed separately. In the GBS cohort, high mEGOS and EGOS scores were significantly correlated with poor outcome at 6 months (mEGOS on admission: r = .381, P = .005; mEGOS at day 7 of admission: r = .507, P 
  17. Ala97Ser mutation is common among ethnic Chinese Malaysians with transthyretin familial amyloid polyneuropathy
    Low SC, Tan CY, Md Sari NA, Ahmad-Annuar A, Wong KT, Lin KP, et al.
    Amyloid, 2019 7 26;26(sup1):7-8.
    PMID: 31343308 DOI: 10.1080/13506129.2019.1582479
  18. Rapid Nucleation of Reduced Graphene Oxide-Supported Palladium Electrocatalysts for Methanol Oxidation Reaction
    Ng JC, Tan CY, Ong BH, Matsuda A, Basirun WJ, Tan WK, et al.
    J Nanosci Nanotechnol, 2019 Nov 01;19(11):7236-7243.
    PMID: 31039881 DOI: 10.1166/jnn.2019.16717
    Small sized electrocatalysts, which can be obtained by rapid nucleation and high supersaturation are imperative for outstanding methanol oxidation reaction (MOR). Conventional microwave synthesis processes of electrocatalysts include ultrasonication, stirring, pH adjustment, and microwave irradiation of the precursor mixture. Ethylene glycol (EG), which serves as a reductant and solvent was added during the ultrasonication or stirring stage. However, this step and pH adjustment resulted in unintended multi-stage gradual nucleation. In this study, the microwave reduction approach was used to induce rapid nucleation and high supersaturation in order to fabricate small-sized reduced graphene oxide-supported palladium (Pd/rGO) electrocatalysts via the delayed addition of EG, elimination of the pH adjustment step, addition of sodium carbonate (Na₂CO₃), prior microwave irradiation of the EG mixed with Na₂CO₃, and addition of room temperature precursor mixture. Besides its role as a second reducing agent, the addition of Na₂CO₃ was primarily intended to generate an alkaline condition, which is essential for the high-performance of electrocatalysts. Moreover, the microwave irradiation of the EG and Na₂CO₃ mixture generated highly reactive free radicals that facilitate rapid nucleation. Meanwhile, the room temperature precursor mixture increased supersaturation. Results showed improved electrochemically active surface area (78.97 m² g-1, 23.79% larger), MOR (434.49 mA mg-1, 37.96% higher) and stability.
  19. Association of dengue infection and Guillain-Barré syndrome in Malaysia
    Tan CY, Razali SNO, Goh KJ, Sam IC, Shahrizaila N
    J Neurol Neurosurg Psychiatry, 2019 11;90(11):1298-1300.
    PMID: 31085583 DOI: 10.1136/jnnp-2019-320756
  20. Fulltext A Severe Form of M - protein Negative Distal Acquired Demyelinating Symmetric Neuropathy
    Ong TL, Goh KJ, Shahrizaila N, Wong KT, Tan CY
    Neurol India, 2019 12 21;67(6):1532-1535.
    PMID: 31857554 DOI: 10.4103/0028-3886.273621
    Distal acquired demyelinating symmetric neuropathy (DADS) is a variant of chronic inflammatory demyelinating polyneuropathy (CIDP) characterized by symmetrical, distal, sensory or sensorimotor involvement. DADS with M-protein (DADS-M) is less responsive to immunotherapy compared to those without M-protein (DADS-I). We report a case of DADS-I with severe clinical presentation viz. early hand involvement with marked wasting, inexcitable peripheral nerves on neurophysiology and poor response to immunotherapy. Despite the unusual presentation, ancillary tests including cerebrospinal fluid analysis, nerve biopsy and nerve ultrasound were supportive of an inflammatory demyelinating polyneuropathy. This case demonstrated the heterogeneity of the disorder and expands the clinical spectrum of DADS neuropathy.
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