Displaying publications 41 - 60 of 991 in total

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  1. Association of p53 tumor suppressor gene with paraclinical and clinical modalities of gliomas patients in Malaysia
    Yusoff AA, Abdullah J, Abdullah MR, Mohd Ariff AR, Isa MN
    Acta Neurochir (Wien), 2004 Jun;146(6):595-601.
    PMID: 15168228
    Alteration of the tumor suppressor gene p53 is considered to be a critical step in the development of human cancer. Changes in this gene have been detected in a wide range of human tumours, including gliomas. In glioma, the presence of p53 gene alterations has been associated with worse prognosis.
    Matched MeSH terms: Frameshift Mutation/genetics; Point Mutation/genetics
  2. Mutagenicity Assessment of Homologous Series of Methyl Ester Sulphonates (MES) Using the Bacterial Reverse Mutation (Ames) Test
    Yusof YA, Azizul Hasan ZA, Abd Maurad Z
    Int J Toxicol, 2024;43(2):157-164.
    PMID: 38048784 DOI: 10.1177/10915818231217041
    Methyl ester sulphonate (MES) is an anionic surfactant that is suitable to be used as an active ingredient in household products. Four palm-based MES compounds with various carbon chains, namely C12, C14, C16 and C16/18 MES, were assayed by the in vitro bacterial reverse mutation (Ames) test in the Salmonella typhimurium strains TA98, TA100, TA1535, and TA1537 and the Escherichia coli strain WP2 uvrA, with the aim of establishing the safety data of the compounds, specifically their mutagenicity. The test was also carried out on linear alkylbenzene sulphonate (LAS) for comparison. The plate incorporation method was conducted according to the Organization for Economic Cooperation and Development (OECD) Test Guideline 471. All compounds were tested at five analysable non-cytotoxic concentrations, varying from .001 mg/plate to 5 mg/plate, with and without S-9 metabolic activation. All tested concentrations showed no significant increase in the number of revertant colonies compared to revertant colonies of the negative control. The Ames test indicated that each concentration of C12, C14, C16, C16/18 MES, and LAS used in this study induced neither base-pair substitutions nor frame-shift mutations in the S. typhimurium strains TA98, TA100, TA1535, and TA1537 and the E. coli strain WP2 uvrA. The results showed that C12, C14, C16 and C16/18 MES have no potential mutagenic properties in the presence and absence of S-9 metabolic activation, similarly to LAS. Therefore, the MES is safe to be used as an alternative to petroleum-based surfactants for household cleaning products.
    Matched MeSH terms: Mutation
  3. Mutations in mitochondrial NADH dehydrogenase subunit 1 (mtND1) gene in colorectal carcinoma
    Yusnita Y, Norsiah MD, Rahman AJ
    Malays J Pathol, 2010 Dec;32(2):103-10.
    PMID: 21329181 MyJurnal
    Mitochondrial Subunit ND1 (mtND1) gene is involved in the first step of the electron transport chain of oxidative phosphorylation (OXPHOS). Alteration of the electron transport components by mutations in mtDNA may compromise the normal electron flow. This could lead to an increase of bifurcation and generation of superoxidase radicals and increase oxidative stress in various types of cancer cells. Genomic DNA was extracted from thirty matched primary colorectal tumour tissues and matching non-tumour tissues. Blood samples were obtained from twenty-five normal people. The mtNDI coding region was amplified by step-down PCR. The purified products were then subjected to direct sequencing and subsequently, the DNA sequences obtained were compared with the revised Cambridge Reference Sequence (rCRS) and MITOMAP. From the analysis, the mtND1 gene showed 11 (45.8%) different mutations and also 13 (54.2%) polymorphisms. The heteroplasmic mutation A4123A/G (I273I/V) might have a pathogenic significance as it fulfills various pathogenic criteria. Three mutations, T3394C (Y30H), A3434G (Y43C) and C3497T (A64V) which occur in a highly conserved region were likely to alter the structure and function of the ND1 protein. We suggest that these mutations, and in combination with the polymorphic variance in mtDNA, may cause slight changes that generate subtly higher levels of toxic reactive oxygen species (ROS).
    Matched MeSH terms: DNA Mutational Analysis; Mutation*
  4. Characterisation and Clinical Significance of FLT3-ITD and non-ITD in Acute Myeloid Leukaemia Patients in Kelantan, Northeast Peninsular Malaysia
    Yunus NM, Johan MF, Ali Nagi Al-Jamal H, Husin A, Hussein AR, Hassan R
    Asian Pac J Cancer Prev, 2015;16(12):4869-72.
    PMID: 26163606
    BACKGROUND: Mutations of the FMS-like tyrosine kinase-3 (FLT3) receptor gene may promote proliferation via activation of multiple signaling pathways. FLT3-internal tandem duplication (FLT3-ITD) is the most common gene alteration found in patients diagnosed with acute myeloid leukaemia (AML) and has been associated with poor prognosis.

    MATERIALS AND METHODS: We performed mutational analysis of exons 14-15 and 20 of the FLT3 gene in 54 AML patients using PCR-CSGE (conformational sensitive gel electrophoresis) followed by sequencing analysis to characterise FLT3 mutations in adult patients diagnosed with AML at Hospital USM, Kelantan, Northeast Peninsular Malaysia.

    RESULTS: FLT3 exon 14-15 mutations were identified in 7 of 54 patients (13%) whereas no mutation was found in FLT3 exon 20. Six ITDs and one non-ITD mutation were found in exon 14 of the juxtamembrane (JM) domain of FLT3. FLT3-ITD mutations were associated with a significantly higher blast percentage (p-value=0.008) and white blood cell count (p-value=0.023) but there was no significant difference in median overall survival time for FLT3-ITD+/FLT3-ITD- within 2 years (p-value=0.374).

    CONCLUSIONS: The incidence of FLT3-ITD in AML patients in this particular region of Malaysia is low compared to the Western world and has a significant association with WBC and blast percentage.

    Matched MeSH terms: DNA Mutational Analysis; Mutation/genetics*
  5. Fulltext Clinical manifestation and genetic analysis of familial rare disease genodermatosis xeroderma pigmentosum
    Yuniati R, Sihombing NRB, Nauphar D, Tiawarman B, Kartikasari DS, Dewi M, et al.
    Intractable Rare Dis Res, 2021 May;10(2):114-121.
    PMID: 33996357 DOI: 10.5582/irdr.2020.03143
    Xeroderma pigmentosum (XP) is a rare autosomal recessive disease characterized by hypersensitivity of the skin to ultraviolet radiation and other carcinogenic agents. This ailment is characterized by increased photosensitivity, skin xerosis, early skin aging, actinic keratosis, erythematous lesions, and hyperpigmentation macules. In this serial case report, we presented four cases with XP from two families in Indonesia. Both families were referred from rural referral health centers, and each family has two affected siblings. They had freckle-like pigmentation on the face, trunk, and extremities, which progressed since childhood. One patient of family 2 died because of an infectious disease. Histopathological examination using cytokeratine (CK), CD10, and Ber-EP4 staining from available tissue biopsy of one affected case of family 1 identified basal cell carcinoma (BCC) on the cheek and melanoma on the right eye. Mutation analysis found ERCC2, c2047C>T and XPC, c1941T>A in the first and second families, respectively. We suppose that this is the first case report of XP in Indonesia that incorporates clinical examination, genetic analysis, and extensive histopathological examination, including immunohistochemistry staining, and a novel pathogenic variant of XPC was found in the second family.
    Matched MeSH terms: DNA Mutational Analysis; Mutation
  6. Fulltext MicroRNA expression profile of a Malaysian Bajau family with familial mitochondrial neurogastrointestinal encephalomyopathy
    Yong FL, Wang CW, Tan KS
    Genet. Mol. Res., 2015;14(4):13172-83.
    PMID: 26535630 DOI: 10.4238/2015.October.26.13
    Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a rare, autosomal recessive disorder associated with mutations in the thymidine phosphorylase (TYMP) gene. The main objective of this study was to characterize the genetic profiles of the deceased proband's family members (N = 4) using DNA sequencing and to determine miRNA deregulation in MNGIE using miRNA microarray profiling and bioinformatic analysis. We found that the genetic profile of the younger sister showed similar TYMP gene mutations as that of the proband with the exception of a heterozygous mutation in exon 10. The miRNA microarray revealed 55 significantly up-regulated and 65 significantly down-regulated miRNAs. These miRNAs have been implicated in various mitochondrial dynamics such as energy metabolism, Krebs cycle, mitochondria-associated apoptosis, and mitophagy. In conclusion, we demonstrate that blood miRNAs are deregulated in the pathogenesis of MNGIE and these changes may have therapeutic implications. Further experimental studies will be required to elucidate the functional miRNA-mRNA interactions in MNGIE.
    Matched MeSH terms: Mutation
  7. Fulltext Cost-effectiveness analysis of olaparib maintenance therapy for BRCA mutation ovarian cancer in the public sector in Malaysia
    Yong CM, Yehgambaram PAP, Lee SWH
    PLoS One, 2024;19(2):e0298130.
    PMID: 38300930 DOI: 10.1371/journal.pone.0298130
    INTRODUCTION: Ovarian cancer is one of the most common cancer among women in Malaysia. Patients with ovarian cancer are often diagnosed at an advanced stage. Despite initial response to surgery and chemotherapy, most patients will experience a relapse. Olaparib has been reported have promising effects among BRCA mutated ovarian cancer patients. This study aimed to evaluate the cost-effectiveness of olaparib as a maintenance therapy for BRCA ovarian cancer in Malaysia.

    METHODS: We developed a four-state partitioned survival model which compared treatment with olaparib versus routine surveillance (RS) from a Malaysian healthcare perspective. Mature overall survival (OS) data from the SOLO-1 study were used and extrapolated using parametric models. Medication costs and healthcare resource usage costs were derived from local inputs and publications. Deterministic and probabilistic sensitivity analyses (PSA) were performed to explore uncertainties.

    RESULTS: In Malaysia, treating patients with olaparib was found to be more costly compared to RS, with an incremental cost of RM149,858 (USD 33,213). Patients treated with olaparib increased life years by 3.05 years and increased quality adjusted life years (QALY) by 2.76 (9.45 years vs 6.40 years; 7.62 vs 4.86 QALY). This translated to an incremental cost-effectiveness ratio (ICER) of RM 49,159 (USD10,895) per life year gained and RM54,357 (USD 12,047) per QALY gained, respectively. ICERs were most sensitive to time horizon of treatment, discount rate for outcomes, cost of treatment and health state costs, but was above the RM53,770/QALY threshold.

    CONCLUSION: The use of olaparib is currently not a cost-effective strategy compared to routine surveillance based upon the current price in Malaysia for people with ovarian cancer with BRCA mutation, despite the improvement in overall survival.

    Matched MeSH terms: Mutation
  8. Fulltext Possible Roles of New Mutations Shared by Asian and American Zika Viruses
    Yokoyama S, Starmer WT
    Mol Biol Evol, 2017 03 01;34(3):525-534.
    PMID: 28087772 DOI: 10.1093/molbev/msw270
    Originating in Africa, the Zika virus (ZIKV) has spread to Asia, Pacific Islands and now to the Americas and beyond. Since the first isolation in 1947, ZIKV strains have been sampled at various times in the last 69 years, but this history has not been reflected in studying the patterns of mutation accumulation in their genomes. Implementing the viral history, we show that the ZIKV ancestor appeared sometime in 1930-1945 and, at that point, its mutation rate was probably less than 0.2 × 10-3/nucleotide site/year and subsequently increased significantly in most of its descendants. Sustaining a high mutation rate of 4 × 10-3/site/year throughout its evolution, the Ancestral Asian strain, which was sampled from a mosquito in Malaysia, accumulated 13 mutations in the 3'-untranslated region of RNA stem-loops prior to 1963, seven of which generate more stable stem-loop structures and are likely to inhibit cellular antiviral activities, including immune and RNA interference (RNAi) pathways. The seven mutations have been maintained in all Asian and American strains and may be responsible for serious medical problems we are facing today and offer testable hypotheses to examine their roles in molecular interactions during brain development.
    Matched MeSH terms: Mutation*; Mutation Rate
  9. Molecular alterations of Ras-Raf-mitogen-activated protein kinase and phosphatidylinositol 3-kinase-Akt signaling pathways in colorectal cancers from a tertiary hospital at Kuala Lumpur, Malaysia
    Yip WK, Choo CW, Leong VC, Leong PP, Jabar MF, Seow HF
    APMIS, 2013 Oct;121(10):954-66.
    PMID: 23992303 DOI: 10.1111/apm.12152
    Molecular alterations in KRAS, BRAF, PIK3CA, and PTEN have been implicated in designing targeted therapy for colorectal cancer (CRC). The present study aimed to determine the status of these molecular alterations in Malaysian CRCs as such data are not available in the literature. We investigated the mutations of KRAS, BRAF, and PTEN, the gene amplification of PIK3CA, and the protein expression of PTEN and phosphatidylinositol 3-kinase (PI3K) catalytic subunit (p110α) by direct DNA sequencing, quantitative real-time PCR, and immunohistochemistry, respectively, in 49 CRC samples. The frequency of KRAS (codons 12, 13, and 61), BRAF (V600E), and PTEN mutations, and PIK3CA amplification was 25.0% (11/44), 2.3% (1/43), 0.0% (0/43), and 76.7% (33/43), respectively. Immunohistochemical staining demonstrated loss of PTEN protein in 54.5% (24/44) of CRCs and no significant difference in PI3K p110α expression between CRCs and the adjacent normal colonic mucosa (p = 0.380). PIK3CA amplification was not associated with PI3K p110α expression level, but associated with male cases (100% of male cases vs 56% of female cases harbored amplified PIK3CA, p = 0.002). PI3K p110α expression was significantly higher (p = 0.041) in poorly/moderately differentiated carcinoma compared with well-differentiated carcinoma. KRAS mutation, PIK3CA amplification, PTEN loss, and PI3K p110α expression did not correlate with Akt phosphorylation or Ki-67 expression. KRAS mutation, PIK3CA amplification, and PTEN loss were not mutually exclusive. This is the first report on CRC in Malaysia showing comparable frequency of KRAS mutation and PTEN loss, lower BRAF mutation rate, higher PIK3CA amplification frequency, and rare PTEN mutation, as compared with published reports.
    Matched MeSH terms: Mutation
  10. Overexpression of phospho-Akt correlates with phosphorylation of EGF receptor, FKHR and BAD in nasopharyngeal carcinoma
    Yip WK, Leong VC, Abdullah MA, Yusoff S, Seow HF
    Oncol Rep, 2008 Feb;19(2):319-28.
    PMID: 18202777
    The Akt pathway is one of the most common molecular alterations in various human malignancies. However, its involvement in nasopharyngeal carcinoma (NPC) tumorigenesis has not been well established. In this study, the status of Akt activation and expression of its upstream and downstream molecules was investigated in 64 NPC and 38 non-malignant nasopharyngeal tissues by immunohistochemistry. The hotspot mutations of PIK3CA, encoding the p110alpha catalytic subunit of phosphatidylinositol 3-kinase (PI3K), were also determined in 25 of these NPC tissues. No hotspot mutations were found in any of the samples tested. Akt was activated in 27 (42.2%) and 23 (35.9%) NPCs, as indicated by p-Akt (Thr308) and p-Akt (Ser473) immunoreactivity, respectively. PTEN loss did not correlate statistically with activated Akt. However, a positive correlation was observed between activated Akt and phospho-epidermal growth factor receptor (p-EGFR), suggesting that the EGFR signaling might be one of the upstream regulators of the Akt pathway. The phosphorylation of forkhead (FKHR) and Bcl-2 associated death domain (BAD), but not mammalian target of rapamycin and glycogen synthase kinase-3beta, was significantly correlated with Akt activation. This implies that Akt promotes cell proliferation (as estimated by Ki-67) and survival, at least, through the inactivation of FKHR and BAD in NPC. Our data revealed that the EGFR/PI3K/Akt signaling pathway is important in NPC pathogenesis and that PIK3CA hotspot mutations are rare in NPC.
    Matched MeSH terms: Mutation
  11. Global Disparities in Breast Cancer Genetics Testing, Counselling and Management
    Yip CH, Evans DG, Agarwal G, Buccimazza I, Kwong A, Morant R, et al.
    World J Surg, 2019 05;43(5):1264-1270.
    PMID: 30610270 DOI: 10.1007/s00268-018-04897-6
    Hereditary breast cancers, mainly due to BRCA1 and BRCA2 mutations, account for only 5-10% of this disease. The threshold for genetic testing is a 10% likelihood of detecting a mutation, as determined by validated models such as BOADICEA and Manchester Scoring System. A 90-95% reduction in breast cancer risk can be achieved with bilateral risk-reducing mastectomy in unaffected BRCA mutation carriers. In patients with BRCA-associated breast cancer, there is a 40% risk of contralateral breast cancer and hence risk-reducing contralateral mastectomy is recommended, which can be performed simultaneously with surgery for unilateral breast cancer. Other options for risk management include surveillance by mammogram and breast magnetic resonance imaging, and chemoprevention with hormonal agents. With the advent of next-generation sequencing and development of multigene panel testing, the cost and time taken for genetic testing have reduced, making it possible for treatment-focused genetic testing. There are also drugs such as the PARP inhibitors that specifically target the BRCA mutation. Risk management multidisciplinary clinics are designed to quantify risk, and offer advice on preventative strategies. However, such services are only possible in high-income settings. In low-resource settings, the prohibitive cost of testing and the lack of genetic counsellors are major barriers to setting up a breast cancer genetics service. Family history is often not well documented because of the stigma associated with cancer. Breast cancer genetics services remain an unmet need in low- and middle-income countries, where the priority is to optimise access to quality treatment.
    Matched MeSH terms: Mutation
  12. International evaluation of unrecognizably uglifying human faces in late and severe secondary hyperparathyroidism in chronic kidney disease. Sagliker syndrome. A unique catastrophic entity, cytogenetic studies for chromosomal abnormalities, calcium-sensing receptor gene and GNAS1 mutations. Striking and promising missense mutations on the GNAS1 gene exons 1, 4, 10, 4
    Yildiz I, Sagliker Y, Demirhan O, Tunc E, Inandiklioglu N, Tasdemir D, et al.
    J Ren Nutr, 2012 Jan;22(1):157-61.
    PMID: 22200434 DOI: 10.1053/j.jrn.2011.10.030
    Hypotheses explaining pathogenesis of secondary hyperparathyroidism (SH) in late and severe CKD as a unique entity called Sagliker syndrome (SS) are still unclear. This international study contains 60 patients from Turkey, India, Malaysia, China, Romania, Egypt, Tunisia, Taiwan, Mexico, Algeria, Poland, Russia, and Iran. We examined patients and first degree relatives for cytogenetic chromosomal abnormalities, calcium sensing receptor (Ca SR) genes in exons 2 and 3 abnormalities and GNAS1 genes mutations in exons 1, 4, 5, 7, 10, 13. Our syndrome could be a new syndrome in between SH, CKD, and hereditary bone dystrophies. We could not find chromosomal abnormalities in cytogenetics and on Ca SR gene exons 2 and 3. Interestingly, we did find promising missense mutations on the GNAS1 gene exons 1, 4, 10, 4. We finally thought that those catastrophic bone diseases were severe SH and its late treatments due to monetary deficiencies and iatrogenic mistreatments not started as early as possible. This was a sine qua non humanity task. Those brand new striking GNAS1 genes missense mutations have to be considered from now on for the genesis of SS.
    Matched MeSH terms: Mutation, Missense/genetics*
  13. Fulltext Vitamin D Deficiency and Janus kinase 2 V617F Mutation Status in Essential Thrombocythemia and Polycythemia Vera
    Yikilmaz AŞ, Akinci S, Bakanay ŞM, Dilek İ
    Malays J Med Sci, 2020 Feb;27(1):70-77.
    PMID: 32158346 DOI: 10.21315/mjms2020.27.1.7
    Introduction: Vitamin D, which is known for its effects on calcium and bone metabolism, has recently been associated with haematological malignancies. We aimed to investigate the relationship between disease findings and vitamin D deficiency in essential thrombocythemia (ET) and polycythemia vera (PV).

    Material and Methods: This retrospective cohort study conducted in Turkey included 73 patients diagnosed with PV or ET according to WHO criteria between 2012 and 2018. Vitamin D deficiency was defined as 25-OH vitamin D < 20 ng/mL. Polymerase chain reaction (PCR) was used to detect the Janus kinase 2 (JAK2) V617F mutation.

    Results: Vitamin D deficiency was found in 66.7% of PV and 74.2% of ET patients. The median follow-up time of ET and PV patients was 48 months and 47 months, respectively. Patients with the JAK2 mutation had a higher prevalence of a history of thrombosis and age older than 65 years. There was a significant relationship between JAK2 positivity and vitamin D deficiency.

    Conclusion: There was a remarkably higher prevalence of vitamin D deficiency in JAK2 mutation-positive ET and PV patients. These patients should be carefully evaluated for vitamin D deficiency. More studies are required to further investigate the association between JAK2 and vitamin D.

    Matched MeSH terms: Mutation
  14. Anion exchanger 1 mutations associated with distal renal tubular acidosis in the Thai population
    Yenchitsomanus PT, Sawasdee N, Paemanee A, Keskanokwong T, Vasuvattakul S, Bejrachandra S, et al.
    J Hum Genet, 2003;48(9):451-456.
    PMID: 12938018 DOI: 10.1007/s10038-003-0059-6
    We have previously demonstrated that compound heterozygous (SAO/G701D) and homozygous (G701D/G701D) mutations of the anion exchanger 1 (AE1) gene, encoding erythroid and kidney AE1 proteins, cause autosomal recessive distal renal tubular acidosis (AR dRTA) in Thai patients. It is thus of interest to examine the prevalence of these mutations in the Thai population. The SAO and G701D mutations were examined in 844 individuals from north, northeast, central, and south Thailand. Other reported mutations including R602H, DeltaV850, and A858D were also examined in some groups of subjects. The SAO mutation was common in the southern Thai population; its heterozygote frequency was 7/206 and estimated allele frequency 1.70%. However, this mutation was not observed in populations of three other regions of Thailand. In contrast, the G701D mutation was not found in the southern population but was observed in the northern, northeastern, and central populations, with heterozygote frequencies of 1/216, 3/205, and 1/217, and estimated allele frequencies of 0.23%, 0.73%, and 0.23%, respectively. The higher allele frequency of the G701D mutation in the northeastern Thai population corresponds to our previous finding that all Thai patients with AR dRTA attributable to homozygous G701D mutation originate from this population. This suggests that the G701D allele that is observed in this region might arise in northeastern Thailand. The presence of patients with compound heterozygous SAO/G701D in southern Thailand and Malaysia and their apparently absence in northeastern Thailand indicate that the G701D allele may have migrated to the southern peninsular region where SAO is common, resulting in pathogenic allelic interaction.
    Matched MeSH terms: DNA Mutational Analysis; Mutation/genetics*
  15. Fulltext Development of live attenuated Enterovirus 71 vaccine strains that confer protection against lethal challenge in mice
    Yee PTI, Tan SH, Ong KC, Tan KO, Wong KT, Hassan SS, et al.
    Sci Rep, 2019 03 18;9(1):4805.
    PMID: 30886246 DOI: 10.1038/s41598-019-41285-z
    Besides causing mild hand, foot and mouth infections, Enterovirus A71 (EV-A71) is associated with neurological complications and fatality. With concerns about rising EV-A71 virulence, there is an urgency for more effective vaccines. The live attenuated vaccine (LAV) is a more valuable vaccine as it can elicit both humoral and cellular immune responses. A miRNA-based vaccine strain (pIY) carrying let-7a and miR-124a target genes in the EV-A71 genome which has a partial deletion in the 5'NTR (∆11 bp) and G64R mutation (3Dp°l) was designed. The viral RNA copy number and viral titers of the pIY strain were significantly lower in SHSY-5Y cells that expressed both let-7a and miR-124a. Inhibition of the cognate miRNAs expressed in RD and SHSY-5Y cells demonstrated de-repression of viral mRNA translation. A previously constructed multiply mutated strain, MMS and the pIY vaccine strain were assessed in their ability to protect 4-week old mice from hind limb paralysis. The MMS showed higher amounts of IFN-γ ex vivo than the pIY vaccine strain. There was absence of EV-A71 antigen in the skeletal muscles and spinal cord micrographs of mice vaccinated with the MMS and pIY strains. The MMS and pIY strains are promising LAV candidates developed against severe EV-A71 infections.
    Matched MeSH terms: Mutation
  16. Dissection of synechococcus rubisco large subunit sections involved in holoenzyme formation in escherichia coli by combinatorial section swapping and sequence analyses
    Yee Hung Yeap, Teng Wei Koay, Boon Hoe Lim
    Sains Malaysiana, 2018;47:2269-2289.
    Engineering the CO2
    -fixing enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) to improve photosynthesis
    has long been sought. Rubisco large subunits (RbcL) are highly-conserved but because of certain undefined sequence
    differences, plant Rubisco research cannot fully utilise the robust heterologous Escherichia coli expression system and its
    GroEL folding machinery. Previously, a series of chimeric cyanobacteria Synechococcus elongatus Rubisco, incorporated
    with sequences from the green alga Chlamydomonas reinhardtii, were expressed in E. coli; differences in RbcL sections
    essential for holoenzyme formation were pinpointed. In this study, the remaining sections, presumably not crucial for
    holoenzyme formation and also the small subunit (RbcS), are substituted to further ascertain the possible destabilising
    effects of multiple section mutations. To that end, combinations of Synechococcus RbcL Sections 1 (residues 1-47), 2
    (residues 48-97), 5 (residues 198-247) and 10 (residues 448-472), and RbcS, were swapped with collinear Chlamydomonas
    sections and expressed in E. coli. Interestingly, only the chimera with Sections 1 and 2 together produces holoenzyme and
    an interaction network of complementing amino acid changes is delineated by crystal structure analysis. Furthermore,
    sequence-based analysis also highlighted possible GroEL binding site differences between the two RbcLs.
    Matched MeSH terms: Mutation
  17. Fulltext EGFR mutation testing practices within the Asia Pacific region: results of a multicenter diagnostic survey
    Yatabe Y, Kerr KM, Utomo A, Rajadurai P, Tran VK, Du X, et al.
    J Thorac Oncol, 2015 Mar;10(3):438-45.
    PMID: 25376513 DOI: 10.1097/JTO.0000000000000422
    The efficacy of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors in EGFR mutation-positive non-small-cell lung cancer (NSCLC) patients necessitates accurate, timely testing. Although EGFR mutation testing has been adopted by many laboratories in Asia, data are lacking on the proportion of NSCLC patients tested in each country, and the most commonly used testing methods.
    Matched MeSH terms: DNA Mutational Analysis/methods*; Mutation/genetics*
  18. Co-existence of Marfan syndrome and systemic sclerosis: A case report and a hypothesis suggesting a common link
    Yap WF, Chong HC
    Int J Rheum Dis, 2020 Nov;23(11):1568-1573.
    PMID: 32969582 DOI: 10.1111/1756-185X.13965
    FBN1 gene encodes for the connective tissue protein fibrillin-1 which can also regulate the profibrotic cytokine transforming growth factor (TGF)-ß1. Mutations in the FBN1 gene cause Marfan syndrome (MFS), a genetic condition with defective connective tissues. FBN1 haplotypes and single nucleotide polymorphisms have also been reported to be associated with systemic sclerosis (SSc), a connective tissue disease characterized by fibrosis of multiple organs. Furthermore, the duplication of the Fbn1 gene causes a SSc-like disease in the TsK1 mouse model. To the best of our knowledge, there are no reports of MFS and SSc co-existing in a patient. Here, we describe a 46-year-old woman who presented with cardiac failure. She had a family history of MFS. Physical examination revealed marfanoid habitus and scleroderma features. Echocardiography demonstrated dilated cardiomyopathy with aortic root dilatation, aortic regurgitation and mitral regurgitation. Cardiac magnetic resonance imaging was consistent with dilated cardiomyopathy, mid-wall fibrosis at basal septal wall and dilated aortic root. Extractable nuclear antigen panel detected anti-Scl 70. She fulfilled Ghent criteria for MFS and satisfied American College of Rheumatology/ European League Against Rheumatism classification criteria for SSc. Although we do not have the FBN1 sequence in our patient, the co-existence of MFS and SSc in this patient raises the possibility of co-existence of distinct mutations in the FBN1 gene that could affect TGF-β signaling differently, resulting in divergent pathologic consequences - loss of structural integrity in MFS versus increased extracellular matrix deposition in SSc, and different clinical manifestations.
    Matched MeSH terms: Mutation*
  19. The frequency of pre-core gene mutations in chronic hepatitis B infection: a study of Malaysian subjects
    Yap SF, Wong PW, Chen YC, Rosmawati M
    Southeast Asian J. Trop. Med. Public Health, 2002 Mar;33(1):102-9.
    PMID: 12118437
    A retrospective study was carried out to determine the frequency of the pre-core stop codon mutant virus in a group of chronic hepatitis B carriers: 81 cases were considered [33 hepatits B e antigen (HBe) positive and 48 HBe negative]. All of the HBe positive cases had detectable viral DNA by hybridization analysis; in the case of the HBe negative cases, one third had detectable viral DNA by hybridization analysis and two thirds had HBV DNA detectable by polymerase chain reaction (PCR) amplification. Pre-core stop codon mutant detection was carried out on all specimens using allele-specific oligonucleotide hybridization following PCR amplification of the target sequence. The pre-core mutant was detected in 13/33 (39.4%) of HBe positive cases and in 32/48 (66.7%) of HBe negative cases. Sequence analysis was carried out on 8 of the 16 HBe negative specimens that did not carry the pre-core mutant virus to determine the molecular basis for the HBe minus phenotype in these cases: the 1762/1764 TA paired mutation in the second AT rich region of the core promoter was detected in five cases; a start codon mutation was detected in one case. The predominant mutation resulting in the HBe minus phenotype in our isolates was the 1896A pre-core ("pre-core stop codon") mutation; other mutations responsible for the phenotype included the core promoter paired mutation and pre-core start codon mutation. In view of the high frequency of the pre-core mutant virus, sequence analysis was performed to determine the virus genotype on the basis of the nucleotide sequence of codon 15. The sequences of 21 wild type virus (14 HBe positive and 7 HBe negative cases) were examined: 15 were found to be codon 15 CCT variants (71.4%); the frequency in the HBe positive group was 12/14 (85.7%), while that in the HBe negative group was 3/7 (42.9%). The high frequency of the codon 15 CCT variant in association with the frequent occurrence of the pre-core mutant in our isolates concurs with the results of other studies.
    Matched MeSH terms: Mutation*
  20. Fulltext An Overview of the Genetic Variations of the SARS-CoV-2 Genomes Isolated in Southeast Asian Countries
    Yap PSX, Tan TS, Chan YF, Tee KK, Kamarulzaman A, Teh CSJ
    J Microbiol Biotechnol, 2020 Jul 28;30(7):962-966.
    PMID: 32627759 DOI: 10.4014/jmb.2006.06009
    Monitoring the mutation dynamics of human severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is critical in understanding its infectivity, virulence and pathogenicity for development of a vaccine. In an "age of mobility," the pandemic highlights the importance and vulnerability of regionalization and labor market interdependence in Southeast Asia. We intend to characterize the genetic variability of viral populations within the region to provide preliminary information for regional surveillance in the future. By analyzing 142 complete genomes from South East Asian (SEA) countries, we identified three central variants distinguished by nucleotide and amino acid changes.
    Matched MeSH terms: Mutation*
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