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Biomedical subjects

J S Tay

Publications and source records attributed to J S Tay.

At least 19 recordsLinked to original sources
PubMed1992

Origin of the Koreans: a population genetic study.

A population genetic study was undertaken to investigate the origin of Koreans. Thirteen polymorphic and 7 monomorphic blood genetic markers (serum proteins and red cell enzymes) were studied in a group of 437 Koreans. Genetic distance analyses by both cluster and principal components models were performed between Koreans and eight other populations (Koreans in China, Japanese, Han Chinese, Mongolians, Zhuangs, Malays, Javanese, and Soviet Asians) on the basis of 47 alleles controlled by 15 polymorphic loci. A more detailed analysis using 65 alleles at 19 polymorphic loci was performed on six populations. Both analyses demonstrated genetic evidence of the origin of Koreans from the central Asian Mongolians. Further, the Koreans are more closely related to the Japanese and quite distant from the Chinese. The above evidence of the origin of Koreans fits well with the ethnohistoric account of the origin of Koreans and the Korean language. The minority Koreans in China also maintained their genetic identity.

Alleles↗
PubMed1992

Apolipoprotein B-gene DNA polymorphisms (XbaI and EcoRI), serum lipids, and apolipoproteins in healthy Chinese.

The frequency of restriction fragment length polymorphisms (RFLPs) of the apolipoprotein B (apo B) gene, detected by XbaI and EcoRI, and their influence on serum lipids and apolipoproteins were studied in healthy Chinese of both sexes in Singapore. A total of 221 subjects (150 males, 71 females) were investigated for the XbaI and 159 subjects for the EcoRI polymorphisms, while serum lipids and apolipoprotein levels were available for 196 subjects. The frequency of the X2 allele was found to be significantly lower in the Chinese than that reported in Caucasians from the United Kingdom (0.09 vs. 0.51, P less than 0.001). The haplotype frequencies were also significantly different between the Chinese and Caucasians with a higher frequency of X1R1 in the former compared to the latter (0.85 vs. 0.34, P less than 0.0001). The distribution of RFLP genotypes at both of the restriction sites was at Hardy-Weinberg equilibrium in all groups. The influence of the apo B RFLPs on serum lipids and apolipoprotein levels (apo AI, AII, and B) was studied by both residual and multiple regression analyses considering age, sex, body mass index (BMI), and genotypes as independent variables in all possible combinations. No association was observed between the apo B genotypes and serum lipids or apolipoprotein levels except for high density lipoprotein cholesterol (HDLC), apo AI and AII, with the X2 being associated with significantly lower levels of HDLC as well as apo AI and AII, the effect being stronger in males. These data raise the possibility that the mechanism of reported association between apo B polymorphism and coronary artery disease may be through effects on HDLC.

Adult↗
PubMed1992

Deletion analysis of DMD/BMD children in Singapore using multiplex polymerase chain reaction (PCR) technique.

Twenty-three children suffering from Duchenne/Becker muscular dystrophy (DMD/BMD) in Singapore were analysed using the multiplex polymerase chain reaction (PCR) technique. Deletions were found in 14 cases. One rare case of total deletion of all nine exons was observed. This is the first DMD/BMD deletion analysis on South East Asian children. This technique for screening deletions was informative in 61 per cent of the local cases and would be useful for rapid diagnosis of deletion cases of DMD/BMD.

Adolescent↗
PubMed1992

Association of haptoglobin types with serum lipids and apolipoproteins in a Chinese population.

Association of haptoglobin types with serum lipids and apolipoprotein levels was investigated in a healthy Chinese population of both sexes (n = 679) in Singapore. The frequency of Hp1 and Hp2 was found to be 0.30 and 0.70, respectively. The distribution of haptoglobin phenotypes was at Hardy-Weinberg equilibrium in this population. There was an excess of Hp2 in individuals with the upper two quartiles of serum total cholesterol levels compared to those with the lower two quartiles in both sexes (X1(2): 11.84; P less than 0.001). Subjects with Hp 2-2 had significantly higher serum total and LDL cholesterol levels (243.8 +/- 2.83 and 165.9 +/- 2.48 mg/dl) compared to those in other haptoglobin types (230.7 +/- 2.58 and 154.9 +/- 2.49 mg/dl), respectively (P less than 0.001 and 0.002) after adjustments for age, sex and BMI. No other lipid (HDL cholesterol and triglyceride) and apolipoprotein (apo A-I, A-II and B) traits were associated with haptoglobin types. ANOVA statistics using age, sex and BMI as covariates showed that 1.8% of total variability of serum total cholesterol and 2.1% of serum LDL cholesterol could be explained by haptoglobin types (P 0.008 and 0.003, respectively). It is concluded that haptoglobin polymorphism is significantly associated with serum total and LDL cholesterol levels in this Chinese population.

Adolescent↗
PubMed1992

DNA polymorphisms of the apolipoprotein B gene in Chinese coronary artery disease patients.

Five restriction fragment length polymorphisms (RFLP) of the apo B gene and their association with serum lipids and apolipoprotein levels have been studied in 139 Chinese patients with angiographically confirmed CAD (mean age 56.2 +/- 0.8 years) and 154 healthy Chinese subjects (mean 44.0 +/- 1.0 years) of both sexes. The patient group had significantly higher levels of serum total and LDL cholesterol; and apo B (P < 0.001) and lower HDL cholesterol and apo A-I (P < 0.001 and < 0.01, respectively). The frequencies of the rarer alleles of the ins/del, XbaI and EcoRI (but not the PvuII and MspI) polymorphisms were significantly lower in the Chinese compared to those reported in Caucasians. There was no significant difference in allelic frequencies of the signal peptide region (Ins/Del), XbaI, MspI and EcoRI sites of the apo B gene between the patient and control groups. The frequency of the rarer allele of the PvuII RFLP was significantly lower in the CAD patients (P < 0.05) compared to that in the control group (0.05 vs 0.10). None of the DNA polymorphisms was associated with a significant influence on serum lipid and apolipoprotein levels in the patients with coronary artery disease.

Alleles↗
PubMed1992

Influence of apolipoprotein B signal peptide insertion/deletion polymorphism on serum lipids and apolipoproteins in a Chinese population.

Insertion/deletion polymorphism of the apo B gene encoding signal peptide and its influence on serum lipids and apolipoproteins was studied in 269 Chinese of both sexes in Singapore. The frequency of the Del allele was found to be 0.20, which is significantly lower than that in Caucasians (France) (0.34). The distribution of genotypes of ins/del polymorphism was at Hardy-Weinberg equilibrium in this population. There was an excess of individuals with the deletion allele in hypercholesterolemic subjects compared to those with normal cholesterol levels (P less than 0.05). All the lipid and apolipoprotein values were regressed for age, sex and BMI by multiple regression analysis. Individuals with one or two del alleles had significantly higher levels of serum total cholesterol (248.8 +/- 13.0 and 255.4 +/- 20.4 mg/dl, respectively) compared to those in individuals with only the Ins allele (218.4 +/- 7.8 mg/dl) (P less than 0.05). Serum LDL cholesterol level was also significantly higher in individuals with del allele (173.4 +/- 11.7 mg/dl) compared to that in those without the del allele (141.1 +/- 7.4 mg/dl) (P = 0.02). The percentages of sample variance of different lipid traits explained by apo B signal peptide polymorphism were estimated by analysis of variance (ANOVA) with sex, age and BMI as covariates. 2.3% of variability of serum total cholesterol (F = 3.27, P = 0.040) and 2.8% of LDL cholesterol (F = 3.87, P = 0.023) could be explained by the ins/del polymorphism of the apo B signal peptide gene.

Adolescent↗
PubMed1992

Pathogenesis of Duchenne muscular dystrophy: the calcium hypothesis revisited.

Rapid advances in the molecular genetics of Duchenne muscular dystrophy (DMD) and the discovery and localization of the gene product dystrophin has brought new hope that successful treatment for this disease may not be too far away. Dystrophin has been postulated to have a mechanical function, helping to resist stress associated with muscle contraction. The presence of dystrophin in low concentrations in muscle cells, its expression in nervous tissue and the observation that hypercontraction of the sarcomeres precedes membrane rupture make the hypothesis unlikely. On the basis of an analogy with a cytoskeletal protein ankyrin, which is associated with the sodium/potassium adenosine triphosphatase (ATPase) in the kidney, it is possible that dystrophin deficiency leads initially to an increased but inefficient calcium-ATPase activity, which pumps calcium out of the cell. Partial failure of the pump would result in intracellular accumulation of calcium, hypercontractions of the sarcomeres, rupture of the cell membrane, massive influx of calcium and cell necrosis.

Calcium↗
PubMed1992

Deletional types of alpha-thalassaemia in central Java.

The frequency of deletional alpha-thalassaemia in a Javanese population sample (n = 103) was investigated at three restriction sites of the alpha-globin gene (BamHI, BglII and RsaI). The overall gene frequency of alpha+ deletional thalassaemia was found to be very low (0.03). Leftward (-alpha 4.2) and rightward (-alpha 3.7) deletions and triplicated genes were present in equal frequency (0.015 and 0.005, respectively).

Adult↗
PubMed1992

MspI polymorphism of the apolipoprotein A-II gene, serum lipids and apolipoproteins in Chinese from Singapore.

The effect of a DNA polymorphism (MspI) of the apolipoprotein (apo) A-II gene on serum lipid and apo levels was studied in a group of 125 healthy Chinese of both sexes. The frequency of the 3.7-kb rarer allele (M2) was found to be significantly higher in the Chinese (0.30) than in Caucasians (0.16; p < 0.025). The distribution of apo A-II genotypes was in Hardy-Weinberg equilibrium in the Chinese population. The presence of a polymorphic site (MspI) within an Alu sequence at the 3' end of the gene, the 3.0 kb (M1) allele, was associated with significantly higher levels of serum apo A-I and A-II (p < 0.05 and < 0.01, respectively). Serum high-density Lipoprotein cholesterol levels were also correspondingly higher in individuals with M1, but did not reach a significant level. Male heterozygotes of the apo A-II polymorphism had significantly higher levels of serum triglycerides compared to homozygotes (p < 0.05). Thus the MspI polymorphism of the apo A-II gene appears to be associated with altered levels of lipids and apos in the Chinese population.

Adult↗
PubMed1992

Polymorphisms of alpha-1-acid (orosomucoid), alpha-2-HS-glycoproteins and alpha-1-B among the Parsis of India.

Genetic polymorphisms of plasma alpha 1-acid glycoprotein (oro-somucoid, ORM), alpha 2-HS-glycoprotein (A2HS) and alpha 1-B-glycoprotein (alpha 1B) were studied in a group of Parsis in Bombay, India. The frequencies of ORM1*1, ORM1*2 and ORM1*3 were found to be 0.636, 0.356 and 0.008, respectively. A2HS*1, A2HS*2 and A2HS*3 frequencies were 0.855, 0.135 and 0.010, while the frequencies of A1B*1 and A1B*2 were 0.881 and 0.119, respectively. The phenotype distribution at all three loci was at Hardy-Weinberg equilibrium. The ORM2 locus was monomorphic in the Parsis.

Alleles↗
PubMed1992

Growth and pubertal assessment after treatment in acute leukemia.

To evaluate the effect of leukaemia and its treatment on growth and puberty, we studied retrospectively the serial heights and pubertal development of 37 children with acute leukaemia. The age of diagnosis ranged from 10 months to 13 years, with a duration of follow-up varying from 2 years to 14 years. The SDS (Z score) which reflects the deviation of height measurements from the population mean was used to assess height change at yearly intervals. Pubertal assessment was also made using the Tanner standards. 25 (69%) children showed a falling trend in mean Z scores over a 5 year follow-up period. The difference between the mean Z scores at 0 and 5 years was statistically significant (p < 0.035). However, there was no significant correlation between age of onset of disease and duration of survival with the deviation in the Z score. 11 children did not demonstrate a fall in the Z scores. There were, however, no defined factors such as age of onset, duration of follow-up, and sex distribution which could predict growth failure. Pubertal assessment showed normal development in all children with the pubertal age group (n = 11), except for 3 boys, two of whom had received testicular irradiation.

Acute Disease↗
PubMed1992

Detection and molecular analysis of alpha and beta thalassaemia genes--recent developments in screening protocols.

Molecular and non-molecular techniques have been utilized for the detection and characterisation of alpha- and beta-thalassaemia genes. Non-molecular techniques example, haematological indices and haemoglobin electrophoresis allow samples to be screened rapidly without the use of radionuclides but these techniques are unable to detect mutations at the gene level. Molecular analysis of alpha- and beta-globin genes either by Southern Blotting and radionuclides or DNA amplification using the polymerase chain reaction (PCR) allows detection of specific mutations and have enabled prenatal diagnosis of the thalassaemias.

Female↗
PubMed1992

The genetic basis of cancer.

The genetic basis of human cancer is well established, although much work remains to be done to unravel the mechanisms of carcinogenesis. Multiple genetic alterations appear to the hallmark in the adult cancers. Molecular cloning and characterization of the amplified proto-oncogenes and mutated recessive oncogenes would shed light on the mechanisms involved in the initiation and progression of human cancer. New tests are likely to be available in the near future (for specific oncogenes) for the diagnosis and management of various forms of human cancer.

Animals↗
PubMed1992

Genetic study of five populations of Bihar, India.

Four-hundred fifty-nine people, including 106 Santals, 43 Bhuiyas, 107 Sakaldipi Brahmins, 108 Chamars, and 95 Ansari Muslims, of the Giridhi district of Bihar have been tested for transferrin, group-specific component, phosphoglucomutase subtypes, and glyoxalase-I, 6-phosphogluconate dehydrogenase, and adenylate kinase types. Genetic distance estimates by both dendrogram and principal component methods for these 5 populations and the Oraons on the basis of 19 alleles at 6 polymorphic loci indicate 2 major clusters: Brahmins and Muslims, the latter of which is composed of two subclusters (Santals and Bhuiyas, and Oraons and Chamars). The Santal and Bhuiya tribes both speak Mundari, whereas the Oraons speak a Dravidian language. The Chamars, although low-caste Hindus, seem to have a non-Europoid origin, as do the Oraons.

Adenylate Kinase↗
PubMed1992

Apolipoprotein H (beta-2-glycoprotein I) polymorphism in Asians.

Apolipoprotein H (APOH) (beta-2-glycoprotein I) polymorphism has been studied in 1159 Asians. The sample included 872 Chinese, 179 Asiatic Indians (Dravidian), 91 Filipinos, and 17 Malays. APOH polymorphism was determined by isoelectric focusing of sera in thin-layer polyacrylamide gels containing 3 M urea followed by immunoblotting. The frequencies of the three alleles--APOH*1, APOH*2, and APOH*3--were found to be 0.031, 0.900, and 0.069 in the Chinese; 0.061, 0.866, and 0.073 in the Dravidian Indians; 0.055, 0.923, and 0.022 in the Filipinos; and 0.088, 0.882, and 0.029 in the Malays. The phenotypic distribution was at Hardy-Weinberg equilibrium in all the populations.

Adult↗
PubMed1991

Biochemical characteristics of glucose-6-phosphate dehydrogenase variants among the Malays of Singapore with report of a new non-deficient (GdSingapore) and three deficient variants.

Biochemical characteristics of one non-deficient fast G6PD variant (GdSingapore) and six different deficient variants (three new, two Mahidol, one each of Indonesian and Mediterranean) were studied among the Malays of Singapore. The GdSingapore variant had normal enzyme activity (82%) and fast electrophoretic mobilities (140% in TEB buffer, 160% in phosphate and 140% in Tris-HCl buffer systems respectively). This variant is further characterized by normal Km for G6P; utilization of analogues (Gal6P, 2dG6P; dAmNADP), heat stability and pH optimum. The other six deficient G6PD variants had normal electrophoretic mobility in TEB buffer with enzyme activities ranging from 1 to 12% of GdB+. The biochemical characteristics identity them to be 2 Mahidol, 1 Indonesian and 1 Mediterranean variants and three new deficient variants.

Electrophoresis↗
PubMed1991

Influence of serum paraoxonase polymorphism on serum lipids and apolipoproteins.

One hundred and sixty-three healthy Chinese subjects of both sexes were studied for serum paraoxonase (PON) polymorphism, and levels of lipids and apolipoproteins in order to examine effects of PON alleles on these parameters. The level of serum triglyceride was significantly higher in high activity allele (PON*B) compared with that in low activity allele (PON*A) in both sexes (P less than 0.01). The subjects with PON A had significantly higher LDL cholesterol (P less than 0.05) and lower Apo A-II and ApoB levels. The influence of serum paraoxonase on serum lipids was estimated further by Spearman's rank correlation. In the males, there was a significant negative correlation of serum paraoxonase activity with total (P less than 0.05) and LDL (P less than 0.01) cholesterol levels, and positive correlation with HDL cholesterol and Apo A-II levels (P less than 0.05). Serum paraoxonase activity had a high positive correlation with serum triglyceride levels in both sexes (P less than 0.001). Serum ApoB level had a positive correlation with the enzyme activity only in females (P less than 0.01). The allelic effect of PON on these parameters was studied by multiple regression analysis. The high activity allele (PON*B) was associated with higher serum triglyceride level (P less than 0.001) and ApoB (P less than 0.001), while it had lowering influence on total cholesterol (P less than 0.05) and LDL cholesterol (P less than 0.005) in men. The average allelic effect of PON was found to be about 22% for serum triglycerides, 11% for LDL cholesterol, 14% for Apo A-II and 19% for Apo B in the present study. This study suggests a possible significant role of serum paraoxonase alleles in the metabolism of serum lipids and apolipoproteins.

Adult↗