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Illyaaseen Z, Ngeow YF, Yap SF, Ng HF. 25S rDNA genotyping and multi-locus sequence typing of Candida albicans of pathogenic and commensal origins in the Klang Valley, Malaysia. Malays J Pathol 2021; 43:55-61. [PMID: 33903306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Candida albicans is an important opportunistic fungal pathogen capable of causing fatal systemic infections in humans. Presently in Malaysia, there is little information available on the genetic diversity of this organism and trends in behavioural characteristics. In this project, three genotyping methods: 25S rDNA genotyping, Alternative Lengthening of Telomerase (ALT) sequence typing and Multi-Locus Sequence Typing (MLST) were applied to study the genetic diversity of strains from infected hospital in-patients and asymptomatic individuals in the community. The results showed that, with the 25S rDNA genotyping, as in other parts of the world, the most common genotype was type A which accounted for approximately 70% of the 111 isolates tested. Further typing with the ALT sequence showed type 3 to be the most common in the isolates tested. MLST analysis revealed many possibly novel sequence types, as well as a statistically significant association between pathogenicity and a group of closely related isolates, most of which were from hospital samples. Further work on genotypes associated with enhanced virulence will help to clarify the value of genotyping for clinical and epidemiological investigations.
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Affiliation(s)
- Z Illyaaseen
- Centre for Research on Communicable Diseases, Faculty of Medicine and Health Sciences, Universiti Tunku Abdul Rahman, Jalan Sungai Long, Bandar Sungai Long, 43000 Kajang, Selangor, Malaysia
| | - Y F Ngeow
- Centre for Research on Communicable Diseases, Faculty of Medicine and Health Sciences, Universiti Tunku Abdul Rahman, Jalan Sungai Long, Bandar Sungai Long, 43000 Kajang, Selangor, Malaysia.
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Mok SF, Karuthan C, Cheah YK, Ngeow WC, Rosnah Z, Yap SF, Ong HKA. The oral microbiome community variations associated with normal, potentially malignant disorders and malignant lesions of the oral cavity. Malays J Pathol 2017; 39:1-15. [PMID: 28413200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The human oral microbiome has been known to show strong association with various oral diseases including oral cancer. This study attempts to characterize the community variations between normal, oral potentially malignant disorders (OPMD) and cancer associated microbiota using 16S rDNA sequencing. Swab samples were collected from three groups (normal, OPMD and oral cancer) with nine subjects from each group. Bacteria genomic DNA was isolated in which full length 16S rDNA were amplified and used for cloned library sequencing. 16S rDNA sequences were processed and analysed with MOTHUR. A core oral microbiome was identified consisting of Firmicutes, Proteobacteria, Fusobacteria, Bacteroidetes and Actinobacteria at the phylum level while Streptococcus, Veillonella, Gemella, Granulicatella, Neisseria, Haemophilus, Selenomonas, Fusobacterium, Leptotrichia, Prevotella, Porphyromonas and Lachnoanaerobaculum were detected at the genus level. Firmicutes and Streptococcus were the predominant phylum and genus respectively. Potential oral microbiome memberships unique to normal, OPMD and oral cancer oral cavities were also identified. Analysis of Molecular Variance (AMOVA) showed a significant difference between the normal and the cancer associated oral microbiota but not between the OPMD and the other two groups. However, 2D NMDS showed an overlapping of the OPMD associated oral microbiome between the normal and cancer groups. These findings indicated that oral microbes could be potential biomarkers to distinguish between normal, OPMD and cancer subjects.
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Affiliation(s)
- S F Mok
- Universiti Tunku Abdul Rahman, Faculty of Medicine and Health Sciences, Jalan Sungai Long, Bandar Sungai Long, 43000 Kajang, Selangor, Malaysia.
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3
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Yap SF, Ho PS, Kuo HC, Yang YH. Comparing factors affecting commencement and cessation of betel quid chewing behavior in Taiwanese adults. BMC Public Health 2008; 8:199. [PMID: 18533044 PMCID: PMC2430570 DOI: 10.1186/1471-2458-8-199] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2008] [Accepted: 06/05/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Betel quid is the fourth most common used substance in the world after tobacco, alcohol and caffeine. Although factors related to betel quid chewing or cessation of behaviors were reported previously, few studies simultaneously compared both behaviors in the same population. In addition, it is essential to consider time-to-event concept, since the chance of developing or stopping habit may vary over time. The purpose of this study was to compare the risk factors for commencement and cessation of betel quid chewing behaviors in a time-to-event setting. METHODS A stratified multi-stage cluster sampling with selection probabilities proportional to size (PPS) was designed for Taiwanese adults with aged 18 years old and above. Kaplan-Meier estimates and Cox proportional hazard regression models were used to compare and calculate the hazard rate ratios for related factors to commencement or cessation of chewing habits. RESULTS In Taiwan, men had a higher betel quid chewing rate (M: 20.9%, W: 1.2%), but woman chewers had a lower cessation rate (M: 27.5%, W: 12.7%). The hazard rate ratio (HRR) of having chewing habit changed from 4.22 (men vs women) univariately to 1.38 multivariablely, which indicated gender differences were confounded by other factors. In multivariable analysis, the risk factors of gender, education and ethnicity were significantly associated with both starting and cessation of betel quid chewing behavior. The factors of occupation, cigarette smoking and alcohol drinking were only associated with starting habit. CONCLUSION Commencement or cessation of chewing behavior involves a scenario of time, hence it is preferable to use a time-to-event approach for the comparison. The cessation rates of betel quid chewing were decreasingly associated with the daily consumption of betel quid. Hence, reducing of daily amount in betel quid cessation program may be associated with future stopping habit.
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Affiliation(s)
- Shue-Fang Yap
- Faculty of Dental Hygiene, College of Dental Medicine, Kaohsiung Medical University, Taiwan.
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Wee YC, Tan KL, Kuldip K, Tai KS, George E, Tan PC, Chia P, Subramaniam R, Yap SF, Tan JAMA. Alpha-thalassaemia in association with beta-thalassaemia patients in Malaysia: a study on the co-inheritance of both disorders. Public Health Genomics 2008; 11:129-34. [PMID: 18376108 DOI: 10.1159/000113874] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS Individuals with double heterozygosity for alpha- and beta-thalassaemia and heterozygous beta-thalassaemia show a similar haematological picture. Co-inheritance of alpha- and beta-thalassaemia in both partners may result in pregnancies with either Hb Bart's hydrops foetalis or beta-thalassaemia major, or pregnancies with both disorders. METHODS The co-inheritance of alpha-thalassaemia in 322 beta-thalassaemia carriers in Malaysia was studied. RESULTS The frequency of alpha-thalassaemia in the beta-thalassaemia carriers was 12.7% (41/322), with a carrier frequency of 7.8% for the SEA deletion, 3.7% for the -alpha(3.7) deletion, 0.9% for Hb Constant Spring and 0.3% for the -alpha(4.2) deletion. CONCLUSION Double heterozygosity for alpha- and beta-thalassaemia was confirmed in 5 out of the 41 couples and the risk of the fatal condition Hb Bart's hydrops foetalis was confirmed in two of these couples. Detection of the Southeast Asian (SEA) deletion in the Malaysian Malays in this study confirms that Hb Bart's hydrops foetalis can occur in this ethnic group. Results of this study have provided new information on the frequency and different types of alpha-thalassaemia (--(SEA), -alpha(3.7) and -alpha(4.2) deletions, Hb Constant Spring) in Malaysian beta-thalassaemia carriers.
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Affiliation(s)
- Y C Wee
- Department of Molecular Medicine, University of Malaya, Kuala Lumpur, Malaysia.
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Thong MK, Tan JAMA, Tan KL, Yap SF. Characterisation of beta-globin gene mutations in Malaysian children: a strategy for the control of beta-thalassaemia in a developing country. J Trop Pediatr 2005; 51:328-33. [PMID: 15967770 DOI: 10.1093/tropej/fmi052] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
beta-thalassaemia major, an autosomal recessive hemoglobinopathy, is one of the most common single gene disorders in multi-racial Malaysia. The control of beta-thalassaemia major requires a multi-disciplinary approach that includes population screening, genetic counselling, prenatal diagnosis and the option of termination of affected pregnancies. To achieve this objective, the molecular characterisation of the spectrum of beta-globin gene mutations in each of the affected ethnic groups is required. We studied 88 consecutive unrelated individuals and their respective families with beta-thalassaemia (74 beta-thalassaemia major, 12 HbE-beta-thalassaemia, 2 with HbE homozygotes) and four individuals with beta-thalassaemia trait that contributed a total 180 alleles for study. Using a 2-step molecular diagnostic strategy consisting of amplification refractory mutation system (ARMS) to identify the 8 most common mutations followed by other DNA-based diagnostic techniques, a total of 177 (98.3 per cent) of the 180 beta-thalassaemia alleles were characterised. One out of 91 (1 per cent) of the Chinese alleles, one out of 46 (2.2 per cent) Malay alleles and one out of two Indian alleles remained unknown. A 100 per cent success rate was achieved in studying the Kadazandusun community in this study. A strategy to identify beta-globin gene mutations in Malaysians with beta-thalassaemia is proposed based on this outcome.
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Affiliation(s)
- Meow-Keong Thong
- Department of Paediatrics, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia.
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Wee YC, Tan KL, Tan PC, Yap SF, Tan JAMA. Rapid and cost-effective antenatal diagnosis of haemoglobin Bart's hydrops foetalis syndrome using a duplex-polymerase chain reaction. Med J Malaysia 2005; 60:447-53. [PMID: 16570706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Haemoglobin Bart's hydrops foetalis syndrome (--SEA/--SEA) is not compatible with life and contributes to a majority of the hydropic foetuses in the Malaysian Chinese alpha-thalassaemia carriers who possess the 2-alpha-gene deletion in cis (--SEA/alphaalpha). A duplex-PCR which simultaneously amplifies a normal 136 bp sequence between the psialpha-alpha2-globin genes and a 730 bp Southeast Asian deletion-specific sequence (--SEA) between the psialpha2-theta1-globin genes was established. The duplex-PCR which detects the --SEA deletion in both chromosomes serves as a rapid and cost-effective confirmatory test in the antenatal diagnosis of Haemoglobin Bart's hydrops foetalis syndrome in Malaysia. In addition, the duplex-PCR is simple to perform as both the normal and deletion-specific alpha-globin gene sequences are amplified in the same PCR reaction.
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Affiliation(s)
- Y C Wee
- Department of Molecular Medicine, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur
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Tan JAMA, George E, Tan KL, Chow T, Tan PC, Hassan J, Chia P, Subramanium R, Chandran R, Yap SF. Molecular defects in the β-globin gene identified in different ethnic groups/populations during prenatal diagnosis for β-thalassemia: a Malaysian experience. Clin Exp Med 2004; 4:142-7. [PMID: 15599663 DOI: 10.1007/s10238-004-0048-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2004] [Revised: 09/20/2004] [Indexed: 10/26/2022]
Abstract
Beta-thalassemia is the most-common genetic disorder of hemoglobin synthesis in Malaysia, and about 4.5% of the population are heterozygous carriers of the disorder. Prenatal diagnosis was performed for 96 couples using the Amplification Refractory Mutation System and Gap-Polymerase Chain Reaction. We identified 17 beta-globin defects-initiation codon for translation (T-G), -29 (A-G), -28 (A-G), CAP +1 (A-C), CD 8/9 (+G), CD 15 (G-A), CD 17 (A-T), CD 19 (A-G), Hb E (G-A), IVS1-1 (G-T), IVS1-5 (G-C), CD 41/42 (-CTTT), CD 71-72 (+A), IVS2-654 (CT), poly A(A-G), 100-kb Ggamma(Agammadeltabeta) degrees and 45-kb Filipino deletions. The 192 beta-alleles studied comprised Chinese (151 patients), Malay (21), Orang Asli from East Malaysia (15), Filipino (1), Indian (1), Indonesian Chinese (2), and Thai (1). In the Chinese, 2 beta-globin defects at CD 41/42 and IVS2-654 were responsible for 74% of beta-thalassemia. beta-mutations at CD 19, IVS1-1 (G-T), IVS1-5, poly A, and hemoglobin E caused 76% of the hemoglobin disorders in the Malays. The Filipino 45-kb deletion caused 73.3% of bthalassemia in the Orang Asli. Using genomic sequencing, the rare Chinese beta-mutation at CD 43 (G-T) was confirmed in 2 Chinese, and the Mediterranean mutation IVS1-1 (G-A) was observed in a Malay beta-thalassemia carrier. The beta-globin mutations confirmed in this prenatal diagnosis study were heterogenous and 65 (68%) couples showed a different globin defect from each other. The use of specific molecular protocols has allowed rapid and successful prenatal diagnosis of beta-thalassemia in Malaysia.
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Affiliation(s)
- J A M A Tan
- Department of Molecular Medicine, University of Malaya Medical Centre (UMMC), 50603, Kuala Lumpur, Malaysia.
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Yap SF. Hepatitis B: review of development from the discovery of the "Australia Antigen" to end of the twentieth Century. Malays J Pathol 2004; 26:1-12. [PMID: 16190102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
"Parenteral" or "serum" hepatitis is known to have afflicted man for centuries. However, it was not until the mid-1960s that the causative agent of this infection, the hepatitis B virus, was discovered. Since then, the biology and the replication strategy of the virus, and the clinical features and the epidemiology of the hepatitis B infection have been determined. Knowledge about the virus and the infection it causes led to the development of firstly, a plasma-derived vaccine and later a recombinant vaccine for the prevention of the infection. Integration of the hepatitis B vaccine into newborn vaccination programmes on a worldwide basis represents a major step in the effort to eliminate this infectious disease and its complications. Laboratory tests are available for the diagnosis and monitoring of the disease. Therapies have been developed to halt the progress of the chronic infection in affected individuals. While these developments have resulted in a decrease of the frequency of infection in many countries, particularly those that have implemented universal immunization of newborns, the chronic infection remains a significant global problem. Worldwide, over 300 million individuals are infected and each year, an estimated 1 million persons die from chronic complications of the disease including hepatocellular carcinoma and hepatic failure. The therapies currently available result in elimination of the virus in only a relatively small proportion of subjects and carry with it serious side effects. Geopolitical, economic and other factors hinder the vision of elimination of the infection through immunization programmes. Nevertheless, work continues to clarify further the underlying pathological mechanism of the infection, the host and viral factors that promote elimination or persistence of the virus in the human host. It is hoped that such investigations will reveal viral targets for the design of newer and potentially more effective drugs to treat the infection.
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MESH Headings
- Carcinoma, Hepatocellular/virology
- DNA, Viral
- Female
- Hepatitis B/diagnosis
- Hepatitis B/epidemiology
- Hepatitis B/etiology
- Hepatitis B/history
- Hepatitis B/immunology
- Hepatitis B/prevention & control
- Hepatitis B Surface Antigens/immunology
- Hepatitis B Vaccines/immunology
- Hepatitis B Vaccines/therapeutic use
- Hepatitis B virus/genetics
- Hepatitis B virus/immunology
- Hepatitis B virus/ultrastructure
- Hepatitis B, Chronic/complications
- Hepatitis B, Chronic/mortality
- Hepatitis B, Chronic/prevention & control
- Hepatitis B, Chronic/therapy
- Hepatitis B, Chronic/transmission
- Hepatitis B, Chronic/virology
- History, 20th Century
- Humans
- Infant, Newborn
- Liver Neoplasms/virology
- Pregnancy
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Affiliation(s)
- S F Yap
- Department of Pathology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia
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Pavai S, Yap SF. The clinical significance of elevated levels of serum CA 19-9. Med J Malaysia 2003; 58:667-72. [PMID: 15190651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
The tumour marker CA19-9 is a sensitive marker for pancreatic, gastric and hepatobiliary malignancies. High CA 19-9 level indicates unresectable lesions and a poor prognosis. The objective of the study was to determine the significance and implications of elevated CA 19-9 levels in the serum. A one-year retrospective review of all patients who had CA19-9 measured in our Medical Centre was undertaken; 69 patients were found to have CA 19-9 level above the cut-off value (37 U/ml). Thirty-six patients had malignant and the remaining 33 had benign lesions. CA 19-9 was found to be elevated in malignancies of pancreas, colorectum, lung, liver and ovary. Benign conditions associated with elevation of CA 19-9 included disease of the hepatobiliary system, pneumonia, pleural effusion, renal failure and SLE. In two individuals, there was no obvious cause for the elevation of this marker. CA 19-9 levels were significantly lower in benign than in malignant conditions. In conclusion, elevated CA 19-9 may be found in patients with benign as well as malignant disease. Therefore, it is important (1) that elevated levels of CA 19-9 are interpreted in the light of the clinical presentation of the patient and (2) to be aware of the benign conditions that can be associated with increased levels of this marker. With these factors in mind, CA 19-9 can be used to assist in the diagnosis of pancreatic cancer and assessment of resection adequacy post-operatively.
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Affiliation(s)
- S Pavai
- Department of Pathology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur
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Yap SF, Wong PW, Chen YC, Rosmawati M. The frequency of pre-core gene mutations in chronic hepatitis B infection: a study of Malaysian subjects. Southeast Asian J Trop Med Public Health 2002; 33:102-9. [PMID: 12118437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Abstract
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.
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Affiliation(s)
- S F Yap
- Department of Pathology, Faculty of Medicine, University of Malaya, Kuala Lumpur
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11
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Tan KL, Tan JA, Wong YC, Wee YC, Thong MK, Yap SF. Combine-ARMS: a rapid and cost-effective protocol for molecular characterization of beta-thalassemia in Malaysia. Genet Test 2001; 5:17-22. [PMID: 11336396 DOI: 10.1089/109065701750168626] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Beta-thalassemia major patients have chronic anemia and are dependent on blood transfusions to sustain life. Molecular characterization and prenatal diagnosis of beta3-thalassemia is essential in Malaysia because about 4.5% of the population are heterozygous carriers for beta-thalassemia. The high percentage of compound heterozygosity (47.62%) found in beta-thalassemia major patients in the Thalassaemia Registry, University of Malaya Medical Centre (UMMC), Malaysia, also supports a need for rapid, economical, and sensitive protocols for the detection of beta-thalassemia mutations. Molecular characterization of beta-thalassemia mutations in Malaysia is currently carried out using ARMS, which detects a single beta-thalassemia mutation per PCR reaction. We developed and evaluated Combine amplification refractory mutation system (C-ARMS) techniques for efficient molecular detection of two to three beta-thalassemia mutations in a single PCR reaction. Three C-ARMS protocols were evaluated and established for molecular characterization of common beta-thalassemia mutations in the Malay and Chinese ethnic groups in Malaysia. Two C-ARMS protocols (cd 41-42/IVSII #654 and -29/cd 71-72) detected the beta-thalassemia mutations in 74.98% of the Chinese patients studied. The CARMS for cd 41-42/IVSII #654 detected beta-thalassemia mutations in 72% of the Chinese families. C-ARMS for cd 41-42/IVSI #5/cd 17 allowed detection of beta-thalassemia mutations in 36.53% of beta-thalassemia in the Malay patients. C-ARMS for cd 41-42/IVSI #5/cd 17 detected beta-thalassemia in 45.54% of the Chinese patients. We conclude that C-ARMS with the ability to detect two to three mutations in a single reaction provides more rapid and cost-effective protocols for beta-thalassemia prenatal diagnosis and molecular analysis programs in Malaysia.
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Affiliation(s)
- K L Tan
- Department of Allied Health Sciences, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
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12
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Thong MK, Rudzki Z, Hall J, Tan JA, Chan LL, Yap SF. A single, large deletion accounts for all the beta-globin gene mutations in twenty families from Sabah (North Borneo), Malaysia. Mutation in brief no. 240. Online. Hum Mutat 2000; 13:413. [PMID: 10338100 DOI: 10.1002/(sici)1098-1004(1999)13:5<413::aid-humu14>3.0.co;2-h] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Beta-thalassemia major is one of the commonest genetic disorders in South-East Asia. The spectrum of beta-thalassemia mutations in the various ethnic sub-populations on the island of Borneo is unknown. We studied 20 Dusun children from the East Malaysian state of Sabah (North Borneo) with a severe beta-thalassemia major phenotype, using a combination of Southern analysis, polymerase chain reaction analysis and direct sequencing. We found the children to be homozygous for a large deletion, which has a 5' breakpoint at position -4279 from the cap site of the beta-globin gene (HBB) with the 3' breakpoint located in a L1 family of repetitive sequences at an unknown distance from the beta-globin gene. This was similar to a recent finding of a large deletion causing beta-thalassemia first described in unrelated beta-thalassemia heterozygotes of Filipino descent. This report describes the first 20 families with homozygosity of the deletion causing a severe phenotype. It provides the first information on the molecular epidemiology of beta-thalassemia in Sabah. This finding has implications for the population genetics and preventative strategies for beta-thalassemia major for nearly 300 million individuals in South-East Asia.
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Affiliation(s)
- M K Thong
- Department of Paediatrics, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia.
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13
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Thuraisingham S, Tan KH, Chong KS, Yap SF, Pasamanikam K. A randomised comparison of simvastatin versus simvastatin and low cholesterol diet in the treatment of hypercholesterolaemia. Int J Clin Pract 2000; 54:78-84. [PMID: 10824361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/16/2023] Open
Abstract
There is little evidence to show that strict dietary modification alone confers any significant impact on cardiac events in primary and secondary prevention of coronary heart disease. Given the efficacy of the statins, the need for strict dietary modification in patients on statin therapy has been questioned. This study was performed to assess 1) the added benefit on serum lipid levels of a strict low-fat dietary regimen in patients with hypercholesterolaemia already treated with simvastatin; 2) the efficacy of simvastatin on the lipid profile of our sample Asian population; and 3) the tolerability and side-effect profile of simvastatin. This study was a prospective evaluation of 60 patients with hypercholesterolaemia treated with simvastatin who were subjected to either a normal diet or a dietitian guided low-fat diet. Assessment of the effects on serum lipid levels, side-effects, biochemical and haematological markers were performed. After 24 weeks of treatment, a strict dietitian guided low-fat diet conferred no additional benefit over and above what was achieved by simvastatin alone. Furthermore, a higher dose of simvastatin was needed in the dietitian guided diet group to achieve the target LDL-cholesterol level. Simvastatin resulted in a significant positive alteration of lipid profiles in all patients. The drug was well tolerated, with no significant change in either haematological or biochemical indices. Simvastatin is a highly effective cholesterol-lowering drug with a beneficial effect on the entire lipid spectrum in a cross-section of Asian patients, and is well tolerated. A dietitian guided dietary approach confers no additional advantage once statin therapy has been initiated.
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Affiliation(s)
- S Thuraisingham
- Department of Cardiology, University Malaya Medical Center, Kuala Lumpur, Malaysia
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14
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Abstract
GDP-dissociation inhibitors (GDIs) form one of the classes of regulatory proteins that modulate the cycling of the Ras superfamily of GTPases between active GTP-bound and inactive GDP-bound states. We report here the characterization of the Caenorhabditis elegans RhoGDI (CeRhoGDI) as part of our investigations into Rho-GTPase signalling pathways that are involved in nematode development. CeRhoGDI is a 23-kDa protein that is localized predominantly in the cytosol. CeRhoGDI interacts only with the lipid-modified forms of C. elegans Rho-GTPases, CeRhoA, CeRac1 and Cdc42Ce, in vitro and is able to solubilize the membrane-bound forms of these GTPases. CeRhoGDI recognizes the GTPases in both GTP- and GDP-bound forms; hence it inhibits both the guanine-nucleotide dissociation and GTP-hydrolysis activities. The inhibitory activity towards the GTP-bound GTPases is weak compared with that towards GDP-bound GTPases. CeRhoGDI is expressed throughout development and is highly expressed in marginal and vulval epithelial cells, in sperm cells and spicules. Taken together, our results suggest that CeRhoGDI may be involved in specific morphogenetic events mediated by the C. elegans Rho-GTPases.
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Affiliation(s)
- S F Yap
- Glaxo-IMCB Group, Institute of Molecular and Cell Biology, Singapore
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Liam CK, Chen YC, Yap SF, Srinivas P, Poi PJ. Detection of Mycobacterium tuberculosis in bronchoalveolar lavage from patients with sputum smear-negative pulmonary tuberculosis using a polymerase chain reaction assay. Respirology 1998; 3:125-9. [PMID: 9692522 DOI: 10.1111/j.1440-1843.1998.tb00110.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The objective of this study was to evaluate the utility of a polymerase chain reaction (PCR) assay in detecting Mycobacterium tuberculosis in bronchoalveolar lavage (BAL) specimens of patients suspected of having active pulmonary tuberculosis (TB) but who were sputum smear-negative. Patients undergoing investigation for suspected pulmonary TB at the University Hospital, Kuala Lumpur, and who were sputum smear-negative underwent fibreoptic bronchoscopy and BAL. One portion of each lavage specimen was submitted for smear examination for acid-fast bacilli and mycobacterial culture and the other portion assayed by PCR for the presence of a 562-base pair DNA segment belonging to the insertion sequence IS986, unique to the M. tuberculosis complex. As controls, lavage specimens from patients with other lung lesions were also similarly tested. The PCR assay gave a positivity rate of 80.9% (55 of 68) compared with 8.8% of smear examination and 7.4% of culture for detecting M. tuberculosis in BAL specimens. The assay was positive in two of 45 BAL specimens from 35 control subjects. The PCR assay was more sensitive than smear and culture in detecting M. tuberculosis in BAL specimens of patients with sputum smear-negative pulmonary TB.
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Affiliation(s)
- C K Liam
- Department of Medicine, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
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16
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Cheah PL, Looi LM, Chua CT, Yap SF, Fleming S. Enhanced major histocompatibility complex (MHC) class II antigen expression in lupus nephritis. Malays J Pathol 1997; 19:115-20. [PMID: 10879251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Thirty-eight cases of lupus nephritis, all satisfying the American Rheumatism Association criteria for diagnosis of systemic lupus erythematosus (SLE), with renal involvement and biopsy were immunohistochemically studied for the expression of HLA-DR (DAKO: HLA-DR/alpha, TAL.1B5), one of the three known families belonging to the class II major histocompatibility complex (MHC), using a standard streptavidin-biotin-peroxidase method. 20 nephrectomies performed for renal trauma and tumours constituted the normal controls. Of the lupus nephritis cases, 34 were females and 4 males. Ethnically, 20 were Chinese, 13 Malay, 4 Indian and 1 of indigenous origin. Their ages ranged from 16 to 59 years (mean of 31 years). Histologically, 23 expressed World Health Organisation (WHO) class IV (diffuse proliferative), 10 WHO class V (diffuse membranous), 4 WHO class II (pure mesangiopathy) and 1 WHO class III (segmental and focal proliferative) nephritis. Activity scores ranged between 5 to 19 (mean = 8.6) and chronicity scored between 2 to 7 (mean = 3.2) on a standard scoring system. Similar to other studies, HLA-DR was expressed in the glomerular capillaries and peritubular capillaries of all and mesangium, tubules (proximal, distal and collecting), veins and arterioles of some normal controls. Interestingly, HLA-DR expression was noted in the arteries of 25% of the normal controls, a finding hitherto not reported. The frequency of lupus nephritis cases expressing HLA-DR in the various anatomical components did not differ significantly from the normal controls except that HLA-DR expression in arteries and arterioles was seen at a significantly increased frequency (p < 0.01) in lupus nephritis. This increased expression did not correlate with the WHO class, activity or chronicity scores. It therefore appears that MHC class II shows increased expression in the arterial system of lupus nephritis kidneys. The significance of this is unclear but could be related to heightened (gamma-interferon activation which may be a de novo phenomenon or result of T cell proliferation and activation in SLE.
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Affiliation(s)
- P L Cheah
- Department of Pathology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
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17
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Looi LM, Yap SF, Cheah PL. Correlation between oestrogen receptor protein expression in infiltrating ductal carcinoma of the breast by immunohistochemistry and cytosol measurements. Ann Acad Med Singap 1997; 26:750-3. [PMID: 9522973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Fresh frozen neoplastic tissues from 70 infiltrating ductal breast carcinomas were analysed for cytosolic oestrogen receptor (ER) protein content using a solid phase enzyme immunoassay (EIA) method based on a "sandwich" principle (Abbott ER-EIA monoclonal). Formalin-fixed, paraffin-embedded sections from the same carcinomas were examined for nuclear immunoreactivity against a monoclonal antibody for ER protein (Dako) using the standard avidin-biotin complex immunoperoxidase (IP) method after microwave antigen retrieval. The degree of ER positivity by IP was also scored according to a visual estimation of the percentage of cells expressing immunopositivity and the intensity of staining. Twenty-eight (40%) of the carcinomas were ER-positive by EIA and 34 (48.6%) were positive by IP. Twenty-five (35.7%) were ER-positive and 33 (47.1%) were ER-negative by both methods. Nine (12.9%) were ER-negative by EIA but were positive by IP, this discrepancy being ascribed to sampling inadequacy for EIA. However, 3 (4.3%) tumours were ER-positive by EIA and negative by IP. This discrepancy may be variously due to inadequate antigen retrieval, faulty technique and the possibility that the two methods do not measure identical ER proteins. IP appears to have an advantage over EIA in that it has a higher pick-up rate, does not require fresh tissue and can be applied to archival material. However, to reduce false negative estimations, it may be necessary to run IP staining using more than one ER antibody. Standardisation of the IP method for ER is desirable before this method is to be widely adopted in Malaysian laboratories. Quantitation of ER positivity by IP scoring correlated poorly with actual cytosolic levels. Caution should be exercised in attaching patient management value to visual IP scoring.
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Affiliation(s)
- L M Looi
- Department of Pathology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
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18
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Looi LM, Cheah PL, Yap SF. Correlation between histological grade and c-erbB2 oncoprotein overexpression in infiltrating ductal carcinoma of breast. Malays J Pathol 1997; 19:35-9. [PMID: 10879240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
One hundred and twelve infiltrating ductal carcinoma of breast were studied by the standard avidinbiotin complex immunoperoxidase method on formalin-fixed, paraffin-embedded tissue sections, using a monoclonal antibody to c-erbB-2 oncoprotein. The same tumours were assessed and scored according to the Bloom and Richardson criteria into three histological grades. The distribution of tumours according to grade were: 8 Grade I, 34 Grade II and 70 Grade III. Forty-three (38.4%) tumours showed positive membrane staining for c-erbB-2 oncoprotein. These comprised 7 Grade II and 36 Grade III tumours with c-erbB-2 immunopositivity rates of 20.6% and 51.4% respectively. The oncoprotein was not expressed by Grade I tumours. This study shows a good correlation between c-erbB-2 expression and histological grade, a known prognostic indicator of invasive breast carcinoma. Because the c-erbB-2 oncogene has extensive structural homology to the epidermal growth factor receptor gene, its overexpression can be expected to result in more aggressive tumour behaviour. While it may be regarded as another indicator of poor prognosis breast cancers, its value in the selection of carcinomas less responsive to hormonal therapy and those more suitable for immunotherapy than chemotherapy has been mooted but remains to be clarified.
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Affiliation(s)
- L M Looi
- Department of Pathology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
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19
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Abstract
When screening a Caenorhabditis elegans genomic library using the human Rac1 cDNA as probe, a hybridizing fragment of 2.7 kb was isolated which contained four exons with high sequence similarity to CeRac1, coding for the nematode homologue of the Ras-related small GTP-binding protein Rac1. The putative translational product of 195 amino acids (aa) from the exons displayed 88% identity to the sequence of CeRac1. Interestingly, three alterations were found in the N-terminal "effector domain' (residues 22-45) which hitherto was identical among all known Rac p21s, suggesting that CeRac2 might have different targets/functions for nematode development. Additionally, an insertion of 4 aa was found in the hypervariable region at the C terminus of CeRac2.
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Affiliation(s)
- W Chen
- Glaxo-IMCB Group, National University of Singapore, Singapore
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20
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Chen W, Chen S, Yap SF, Lim L. The Caenorhabditis elegans p21-activated kinase (CePAK) colocalizes with CeRac1 and CDC42Ce at hypodermal cell boundaries during embryo elongation. J Biol Chem 1996; 271:26362-8. [PMID: 8824291 DOI: 10.1074/jbc.271.42.26362] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The p21-activated kinase (PAK) is a downstream target of Rac and CDC42, members of the Ras-related Rho subfamily, that mediates signaling pathway leading to cytoskeletal reorganization. To investigate its function in Caenorhabditis elegans development, we have isolated the cDNA coding for the p21-activated kinase homologue (CePAK) from a C. elegans embryonic cDNA library. This 2.35-kilobase pair cDNA encodes a polypeptide of 572 amino acid residues, with the highly conserved N-terminal p21-binding and the C-terminal kinase domains. Similar to its mammalian and Drosophila counterparts, the CePAK protein expressed in E. coli exhibits binding activity toward GTP-bound CeRac1 and CDC42Ce. Polyclonal antibodies raised against the recombinant CePAK recognize a specific 70-kDa protein from embryonic extracts that displays CeRac1/CDC42Ce-binding and kinase activities. Immunofluorescence analysis indicates that CePAK is specifically expressed at the hypodermal cell boundaries during embryonic body elongation, which involves dramatic cytoskeletal reorganization. Interestingly, CeRac1 and CDC42Ce are found at the same location, which might point to their common involvement in hypodermal cell fusion, a crucial morphogenetic event for nematode development.
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Affiliation(s)
- W Chen
- Glaxo-IMCB Group, Institute of Molecular & Cell Biology, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260, Republic of Singapore
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Yap SC, Choo YM, Hew NF, Yap SF, Khor HT, Ong AS, Goh SH. Oxidative susceptibility of low density lipoprotein from rabbits fed atherogenic diets containing coconut, palm, or soybean oils. Lipids 1995; 30:1145-50. [PMID: 8614305 DOI: 10.1007/bf02536616] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The oxidative susceptibilities of low density lipoproteins (LDL) isolated from rabbits fed high-fat atherogenic diets containing coconut, palm, or soybean oil were investigated. New Zealand white rabbits were fed atherogenic semisynthetic diets containing 0.5% cholesterol and either (i) 13% coconut oil and 2% corn oil (CNO), (ii) 15% refined, bleached, and deodorized palm olein (RBDPO), (iii) 15% crude palm olein (CPO), (iv) 15% soybean oil (SO), or (v) 15% refined, bleached, and deodorized palm olein without cholesterol supplementation [RBDPO(wc)], for a period of twelve weeks. Total fatty acid compositions of the plasma and LDL were found to be modulated (but not too drastically) by the nature of the dietary fats. Cholesterol supplementation significantly increased the plasma level of vitamin E and effectively altered the plasma composition of long-chain fatty acids in favor of increasing oleic acid. Oxidative susceptibilities of LDL samples were determined by Cu2(+)-catalyzed oxidation which provide the lag times and lag-phase slopes. The plasma LDL from all palm oil diets [RBDPO, CPO, and RBDPO(wc)] were shown to be equally resistant to the oxidation, and the LDL from SO-fed rabbits were most susceptible, followed by the LDL from the CNO-fed rabbits. These results reflect a relationship between the oxidative susceptibility of LDL due to a combination of the levels of polyunsaturated fatty acids and vitamin E.
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Affiliation(s)
- S C Yap
- Palm Oil Research Institute of Malaysia, Kuala Lumpur, Malaysia
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22
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Yap SF, Wong PW. Hybridisation analysis for serum hepatitis B virus DNA. Br J Biomed Sci 1994; 51:336-40. [PMID: 7756940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A study was carried out to determine optimal assay conditions for an in-house hybridisation assay for detection of hepatitis B virus (HBV) genome in serum samples. Pre-treatment of samples, blot treatment and hybridisation conditions were found to affect assay performance. The indirect serum blot procedure was more robust and reliable than direct serum blotting. In the former, viral particles were isolated from the sample, lysed and then extracted. In comparison, no approaches to the direct serum spot method performed adequately. Sensitivity studies showed that labelling of the nucleic acid probe with dCTP was more efficient than with dATP. Using probes labelled to a specific activity of > 1 x 10(8) and an autoradiography period of about 48 h we could achieve a detection limit of < 1 pg. Specificity was achieved by use of a highly purified probe and moderately stringent hybridisation and wash conditions. Background binding was minimal and there was no non-specific binding of probe to negative control samples. Factors affecting speed of the assay were studied to identify steps that could be modified to shorten assay time without sacrificing performance. A shorter centrifugation step and the use of a high specific-activity probe permitted completion of an assay within four days.
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Affiliation(s)
- S F Yap
- Department of Pathology, University of Malaya, Kuala Lumpur, Malaysia
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23
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Abstract
AIMS To determine (1) the detection rate of primary carcinoma of the lung by serological assay of CEA (carcinoembryonic antigen); and (2) whether addition of seroassay of squamous cell carcinoma related antigen before treatment improves detection sensitivity. METHODS A prospective study spanning 27 months was conducted at the University Hospital, Kuala Lumpur. Serum CEA (Abbott IMx) and serum squamous cell carcinoma antigen (Abbott IMx) from patients clinically suspected of having primary carcinoma of the lung, were assayed using the microparticle enzyme immunoassay method. RESULTS Thirty seven cases of histologically confirmed primary lung carcinoma were studied. Of these, 17 were squamous cell carcinomas, 10 adenocarcinomas, nine small cell carcinomas, and one large cell carcinoma. The patients' ages ranged from 34-82 years. The male:female ratio was 3.6:1. Squamous cell carcinoma antigen was raised above the cutoff value of 1.5 ng/ml in 94.1% of squamous cell carcinomas, 20.0% of adenocarcinomas, and 11.1% of small cell carcinomas. By comparison, CEA was raised above the cutoff value of 3.0 ng/ml in 70.6% of squamous cell carcinomas, 77.8% of small cell carcinomas, and 100% of adenocarcinomas. CEA and squamous cell carcinoma antigen were not raised in the patient with large cell carcinoma and in 14 healthy volunteers. None of 15 patients with a variety of benign lung diseases showed a rise of CEA, while two patients--a 25 year old Indian woman with pneumonia and a 64 year old Malay man with bronchial asthma--had raised squamous cell carcinoma antigen values above the cutoff. Serum CEA and squamous cell carcinoma antigen values did not seem to correlate with stage or degree of differentiation of the tumours. CONCLUSIONS The findings suggest that CEA is a good general marker for carcinoma, particularly adenocarcinoma. In contrast, squamous cell carcinoma antigen is more specific for squamous carcinoma.
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Affiliation(s)
- P L Cheah
- Department of Pathology, Faculty of Medicine, University of Malaya, Kuala Lumpur
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24
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Yap SF. Chronic hepatitis B infection in Malaysians. Malays J Pathol 1994; 16:3-6. [PMID: 16329567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Chronic hepatitis B virus (HBV) infection constitutes a major public health problem particularly in developing countries in East Asia, South-East Asia, the Pacific Basin and Africa. In Malaysia, a developing nation in the South East Asian region, the chronic HBV carrier rate varies between < 1% to about 10% depending on the ethnic group studied. The highest frequency is seen among the Chinese, followed by the Malays and lastly the Indians, with a male preponderance of between 2 : 1 and 3 : 1. Exposure to the virus among the adult population is estimated to be about 15%, 26% and 36% among the Indians, Malays and Chinese respectively. Serological study of adult chronic HBV carriers showed a frequency of HBe antigenemia of about 35%, with a significant decreasing trend with age. HBV DNA status generally correlated with the HBe status. An atypical profile of anti-HBe associated with serum HBV DNA is found in some carriers; in most instances, this is related to seroconversion from HBe antigenemia to anti-HBe. Chronic complications of HBV infection include the development of hepatocellular carcinoma (HCC), the occurrence of which closely parallel that of HBsAg carrier rate. In Malaysia, HCC is the third most common malignant neoplasm and among the 10 leading causes of death. About 80% of our HCC cases are HBV associated. All 3 ethnic groups are afflicted, the highest frequency being among the Chinese. Males show a disproportionate risk with an odds ratio of 3.93 (p < 0.0001).
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Affiliation(s)
- S F Yap
- Department of Pathology, Faculty of Medicine, University of Malaya, 59100 Kuala Lumpur, Malaysia
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25
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Yap SF, Wong NW, Goh KL. Serum hepatitis B virus DNA: relationship with the e-antigen and anti-e status in chronic carriers. Malays J Pathol 1994; 16:57-62. [PMID: 16329577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The relationship between serum Hepatitis B virus DNA (HBV-DNA) and the Hepatitis B e-antigen/ anti-Hepatitis Be (HBeAg/anti-HBe) serological status in Malaysians was studied. 212 cases of asymptomatic HBV carriers were recruited for this study. 92 cases were positive for the HBeAg at the point of recruitment. 85 (92.4%) of these patients tested positive for HBV-DNA, of whom 55 (64.7%) had levels over 100pg/ml of serum. Three of the remaining 7 HBeAg positive cases who were negative for HBV-DNA subsequently seroconverted. The other 4 cases remained negative for HBV-DNA for periods of 6-12 months. Out of 113 cases who were anti-HBe positive, 12 (10.6%) gave a positive HBV-DNA result. 2 of these 12 patients were recent seroconverters; the remaining cases had transiently increased viral replicative activity which later subsided. 7 out of the 212 carriers were in the e-window period; all 7 tested negative for HBV-DNA. Our data confirm a high frequency of HBV-DNA in HBeAg positive carriers and a negative correlation between HBV-DNA and anti-HBe. An atypical profile of anti-HBe associated with HBV-DNA was observed in 10.6% of the carriers. An inverse relationship between serum HBV-DNA levels and age was also observed.
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Affiliation(s)
- S F Yap
- Department of Pathology, Faculty of Medicine, University of Malaya, 59100 Kuala Lumpur, Malaysia
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26
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Harden N, Yap SF, Chiam MA, Lim L. A Drosophila gene encoding a protein with similarity to diacylglycerol kinase is expressed in specific neurons. Biochem J 1993; 289 ( Pt 2):439-44. [PMID: 8380995 PMCID: PMC1132187 DOI: 10.1042/bj2890439] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
A Drosophila gene encoding a protein with similarity to diacylglycerol kinase (DGK) was isolated by screening a genomic DNA library with a human DGK cDNA under low-stringency hybridization conditions. This putative Drosophila DGK gene (dDGK) maps to 43E on the right arm of chromosome 2. A dDGK cDNA with an open reading frame encoding a 517 amino acid protein was obtained in a screen of a 3-12-h embryonic cDNA library. In a 236-amino-acid overlap at their C-termini there is an identity of 52.5% between the dDGK protein and human DGK. The N-terminus of the Drosophila protein is not similar to human DGK, and contains clusters of polar amino acids. dDGK is transcribed in the embryonic, pupal and adult stages, with little expression during the larval stages. Transcripts of 1.7-2.2 kb, 3.5 kb, 3.7 kb and 6.6 kb are seen, although most of the smaller transcripts may be from genes with similarity to dDGK. In stage-16 and stage-17 embryos, dDGK transcripts are limited to the central nervous system and head. There is a particularly high level of expression in the cell bodies of the larval photoreceptor organ, and in the cell bodies of the ventral unpaired median neurons. The dDGK protein may be involved in regulating signal transduction in these specific neurons.
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Affiliation(s)
- N Harden
- Glaxo-IMCB Laboratory, National University of Singapore
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Yap SF, Peh SC, Chan L, Wong HC, How VJ, Looi LM. HTLV-I antibody study in normal individuals and unselected hospital patients in Malaysia. Southeast Asian J Trop Med Public Health 1992; 23:26-9. [PMID: 1355930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 03/25/2023]
Abstract
A serological investigation for human T cell leukemia virus I (HTLV-I) infection was carried out at the University Hospital, Kuala Lumpur. A total of 626 sera from a non-patient population and 1,038 sera from unselected in-patients were screened for HTLV-I antibodies using an enzyme-linked immunosorbent assay (ELISA). 27/1664 (1.6%) were found to be reactive. However, on Western blotting, only 2 sera were confirmed positive, both showing reactions for the major core (p19 and p24) and the envelope (gp46) proteins. Both of the serum samples were from unselected hospital patients. Most of the remaining sera which were reactive on screening showed indeterminate results on Western blotting. These were further tested by radioimmunoprecipitation assay (RIPA) and none of these sera gave a positive reaction. Therefore, only 2/1038 (0.19%) unselected patients could be confirmed to have antibodies to HTLV-I. None of the normal individuals screened showed a positive Western blot result. Our data indicate that HTLV-I infection is present in our population, but at a low prevalence rate.
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Affiliation(s)
- S F Yap
- Department of Pathology, University of Malaya, Kuala Lumpur, Malaysia
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28
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Yap SF, Peh SC. Alpha-fetoprotein in hepatocellular carcinoma: a serological and histochemical study in Malaysian patients. Malays J Pathol 1991; 13:115-8. [PMID: 1726642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Serum alpha-fetoprotein (AFP) levels and its expression in liver tissue was studied in 50 cases of histologically confirmed hepatocellular carcinoma (HCC). Serum AFP levels were elevated (greater than 20iu/ml) in 35/50 (70%) of the cases, 28 of whom had levels greater than 500 iu/ml, which is highly suggestive of HCC. These results indicate that serum AFP, by itself, is a relatively insensitive diagnostic test for HCC. Although elevated levels in high risk patients provide a specific clue, a negative result does not exclude the diagnosis of HCC. Expression of AFP by tumour cells paralleled that of serum in the majority of cases. However, tissue AFP was negative in 7 patients who had markedly elevated serum AFP. This observation may be a reflection of preferential excretion of the tumour antigen or differential expression of the antigen by the tumour cells. None of the patients with normal serum AFP demonstrated a reaction for tissue AFP. There was no correlation between AFP production and tumour differentiation.
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Affiliation(s)
- S F Yap
- Department of Pathology, Faculty of Medicine, University of Malaya, Kuala Lumpur
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29
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Jeyamalar R, Pathmanathan R, Yap SF, Kannan P. Primary cardiac amyloidosis. Ann Acad Med Singap 1991; 20:795-7. [PMID: 1803972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Cardiac amyloidosis is an uncommon and often unrecognised cause of cardiac failure. It is an infiltrative disease that may mimic either a restrictive or hypertrophic cardiomyopathy, constrictive pericarditis, coronary artery disease or valvular heart disease. The diagnosis should be suspected in a patient with cardiac failure who has low voltage complexes on the electrocardiogram, in association with increased myocardial mass and echogenicity on the echocardiogram. The definitive diagnosis, however, can only be made by endomyocardial biopsy or biopsy of any involved organ in systemic amyloidosis. Prognosis is poor and treatment ineffective.
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Affiliation(s)
- R Jeyamalar
- Department of Medicine, Faculty of Medicine, University of Malaya, Kuala Lumpur
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30
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Cheah PL, Yap SF, Looi LM, Sivanesaratnam V. Squamous cell carcinoma related antigen in uterine cervical carcinoma. Malays J Pathol 1991; 13:37-41. [PMID: 1795560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Squamous cell carcinoma-related antigen (SCC-Ag), first described by Kato and Torigoe in 1977, has been cited by various workers as a serological marker for some epithelial neoplasms. The most well-studied is its association with carcinoma of the uterine cervix. In January 1989, we embarked on a prospective, multivariate study at the University Hospital, Kuala Lumpur to assess the usefulness of serologically assaying SCC-Ag (using the Abbott RIA diagnostic kit) in our patients with carcinoma of the uterine cervix. We were also interested to ascertain whether SCC-Ag is a 'general' marker for all histological types of cervical carcinoma or specific for squamous carcinoma. From the time of commencement to June 1990, 35 newly-diagnosed and histologically-proven cases were entered into the study. Of these, 4 were keratinising squamous carcinoma, 18 large cell non-keratinising carcinoma, 3 adenosquamous carcinoma, 7 adenocarcinoma and 3 carcinoma-in-situ. Our preliminary results show that all keratinising squamous carcinoma and 1/3 each of large cell non-keratinising carcinoma, adenosquamous carcinoma and carcinoma-in-situ had positive pre-therapy serum SCC-Ag levels (i.e greater than 2 ng/ml, 2 ng/ml being an arbitrarily selected 'cut-off' value). In contrast, no adenocarcinoma was serologically positive. In addition, keratinising squamous carcinoma had the highest mean pre-therapy serum SCC-Ag level. The results imply that serum SCC-Ag is related to the (1) presence of squamous and not glandular differentiation and (2) degree of squamous differentiation.
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Affiliation(s)
- P L Cheah
- Department of Pathology, Faculty of Medicine, University of Malaya, Kuala Lumpur
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31
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Abstract
This study documents the prevalence of Hepatitis B serological markers among STD patients who have had multiple sexual partners in Kuala Lumpur, Malaysia, and compares the rates with those of a sample of the population with single or no sexual partners. A total of 336 Chinese STD patients (multiple partners group) and 234 Chinese control subjects (non-multiple partner group) were screened. Those with a history of blood transfusion or parenteral drug abuse had been excluded from the study, and all study subjects were heterosexuals. The overall carrier rate was 9.2% for the multiple partner group (MP group) and 6.8% for the non-multiple partner group (NMP group). Infection rates were 64.3% for the MP-group and 38.9% for the NMP group. After adjustments for age and sex, there was no significant difference in carrier rates between the two groups, but infection rates were significantly different with the MP group, being 3.2 times more likely to acquire infection than the NMP group. The study concludes that in heterosexuals, those with multiple sexual partners have increased chances of acquiring HBV infection.
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Affiliation(s)
- C Y Gan
- Department of Social and Preventive Medicine, University of Malaya, Kuala Lumpur
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32
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Cheah PL, Looi LM, Lin HP, Yap SF. A case of childhood hepatitis B virus infection related primary hepatocellular carcinoma with short malignant transformation time. Pathology 1991; 23:66-8. [PMID: 1648195 DOI: 10.3109/00313029109061443] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A case of primary hepatocellular carcinoma (PHC) developing in a 10 year old boy who contracted Hepatitis B virus (HBV) infection in the course of maintenance phase chemotherapy for acute lymphoblastic leukemia was seen at University Hospital, Kuala Lumpur. This case is of interest in that it (1) supports an etiological relationship between HBV infection and PHC, (2) manifested a distinctly short malignant transformation time, and (3) draws attention to the possible contributory role of chemotherapy in increasing the risk of developing PHC.
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Affiliation(s)
- P L Cheah
- Department of Pathology, Faculty of Medicine, University of Malaya, Kuala Lumpur
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Wong KT, Ng SC, Kuperan P, Yap SF, Menaka N, Bosco J. Multiple myeloma in the University Hospital: a retrospective study of biodata, clinical, laboratory and radiological profiles, 1980-1987. Med J Malaysia 1990; 45:136-43. [PMID: 2152018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
A retrospective study of 37 cases of multiple myeloma admitted from 1980 to 1987 to the University Hospital Kuala Lumpur, Malaysia, was carried out to analyse the biodata, clinical presentation, laboratory and radiological profiles. The cases were selected after they had satisfied preset diagnostic criteria. The mean age was 60 years. There was no sex or ethnic preponderance. The most common symptom was bone pain. Pallor was detected in 73% of the patients. Haemoglobin was less than 120 g/L in 95%, and ESR was greater than 100 mm/hr in 70% of cases. Bone marrow and trephine biopsies were diagnostically important. Hypercalcaemia occurred in seven cases out of which three were IgA myelomas. Either serum creatinine or blood urea was raised in nearly 50% of cases. The most common heavy chain paraprotein was IgG while Kappa light chain was the commoner light chain type. 86% of cases had osteolytic lesions. These findings are, in general, similar to those of larger studies on multiple myeloma.
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Affiliation(s)
- K T Wong
- Department of Pathology, Faculty of Medicine, University of Malaya, Kuala Lumpur
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Abstract
In the 7-year period between 1980 and 1987, six cases of childhood primary hepatocellular carcinoma (PHC) were confirmed histologically in our institution. Hepatitis B surface antigen (HBsAg) seropositivity was confirmed in five of the cases, and tissue HBsAg was shown in four of these using the Shikata's orcein stain. An associated maternal HBsAg seropositivity was shown in two of the seropositive children. The youngest seropositive patient who developed PHC was 7 years old. The mother of this patient was also seropositive. These observations support a causal relation between childhood Hepatitis B virus infection and PHC. The importance of vertical or perinatal transmission of HBV in the causation of childhood PHC and the prophylactic role of childhood vaccination is emphasized. Attention is also drawn to the relative short malignant transformation time seen in some of these patients.
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Affiliation(s)
- P L Cheah
- Department of Pathology, Faculty of Medicine, University of Malaya, Malaysia
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Yap SF, Ngan A, Zaini A. Determination of thyroid-binding inhibiting immunoglobulins using unextracted serum. Malays J Pathol 1987; 9:67-71. [PMID: 2898571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Yap SF. The immunology laboratory services in Malaysia. Malays J Pathol 1982; 5:11-3. [PMID: 7187453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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38
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Pang T, Yap SF, Ngan A, Bosco J. Prevalence of thyroid autoantibodies in an Asian population. Singapore Med J 1980; 21:483-6. [PMID: 7394546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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39
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Yap SF, Pang T. Serum complement (C3 and C4) levels in the Malaysian adult population. Asian J Infect Dis 1979; 3:85-7. [PMID: 120736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Serum C3 and C4 values were determined in 236 normal adults of three racial groups, using the single radial immunodiffusion techniques. The C3 levels varied from 47 to 119 mg/dl and C4 levels from 16 to 66 ml/dl (mean +/- 2SD). The values were found to be comparable to the normals reported in some Western series. No significant differences in the levels related to sex and race were found.
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Pang T, Parasakthi N, Yap SF. Human T- and B-lymphocyte populations in blood: local population studies. Med J Malaysia 1979; 33:243-6. [PMID: 316496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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