Central Thais Research Articles

Magnesium status of patients with renal stones and its effect on urinary citrate excretion.

To assess the magnesium status and its effect on urinary citrate excretion in patients with renal stones, as they have a low muscular magnesium content. Using a magnesium-tolerance test (0.1 mmol/L MgSO4/kg body weight, delivered intravenously), the magnesium status was assessed in 17 patients with renal stones from rural North-east Thailand, and in three groups of normal subjects from different environments (i.e. 17 from rural Central Thailand, 16 from urban and 14 from rural North-east Thailand). Participants with magnesium deficiency (magnesium retention > 50%) were supplemented with 300 mg chelated magnesium daily for 1 month and reassessed. Their urinary citrate excretion was also measured before and after supplementation. Nine of the patients with renal stones were magnesium deficient, as were six normal subjects from the same area, whereas only one and two of the rural Central and urban North-east Thais had magnesium deficiency. The magnesium status of the 13 deficient subjects significantly improved (P = 0.003) after supplementation with chelated magnesium. The supplement also caused a significant increase in mean (sd) urinary citrate excretion, from 237.7 (173.1) to 361.3 (284.1) mg/day (P= 0.012). These results indicate that magnesium deficiency is common among patients with renal stones in rural North-east Thailand, and that the probable cause is environmental. The increase in urinary citrate excretion after magnesium supplementation suggests that magnesium is important in renal stone formation, through its effect on citrate metabolism.

A comparison of molecular HLA-DR and DQ allele profiles forming DR51-, DR52-, and DR53-related haplotypes in five ethnic Thai populations from Mainland Southeast Asia

Using PCR-SSOP typing we have deduced the composition and frequency of HLA-DRB1, -DRB3, -DRB4, -DRB5, -DQA1, and -DQB1 alleles present in DR51-, DR52-, and DR53-related haplotypes, in 519 individuals representative of five ethnic Thai populations recruited in central, northeastern and northern Thailand. In total, we have unequivocally detected at varying frequencies, 17 DR51-related haplotypes, 24 DR52 haplotypes, and 12 DR53 haplotypes in the study groups. We document evidence of north-south gradients of DR51-related haplotypes, whereby the overall frequency of DR51-containing haplotypes is relatively more common in the northern Thai groups. Similarly, within DR53-related haplotypes the frequency of DRB1∗0901-containing haplotypes increases in the more northerly groups, and an inverse effect was observed with DRB1∗0701-containing haplotypes that were relatively more common in the northeastern and central Thais. We have also compared the class II haplotype profiles of the Thais with the equivalent profiles reported in other non-Thai ethnic groups from mainland and insular SE Asia. One DR51-related haplotype DRB1∗1502x, DRB5∗0102x, DQA1∗0101/4, DQB1∗0501, would appear to be characteristic of Thai populations, as it was the most common DR2 haplotype in all five study groups and is also prevalent in other mainland southeast Asians, but is much less evident in the more northern populations of eastern Asia or China.

Distributions of HLA‐DRB1/DQB1 alleles and haplotypes in the North‐eastern Thai population: indicative of a distinct Thai population with Chinese admixtures in the Central Thais

The phenotype and gene frequencies of HLA class II alleles were studied in the North‐eastern Thai population. Blood samples were collected from 100 unrelated healthy North‐eastern Thais. The HLA‐DRB1 and DQB1 genes were typed using the polymerase chain reaction – sequence specific primer (PCR‐SSP) and polymerase chain reaction – sequence specific oligonucleotide probe (PCR‐SSO) techniques. Twenty‐six HLA‐DRB1 and 11 DQB1 alleles were found in this population. DRB1*1202, 1502, 0405 and DQB1*0502/0504, 0301/0304 alleles were commonly found. Linkage disequilibrium analysis suggested the existence of 13 DR‐DQ haplotypes. The DRB1*1502‐DQB1*0501 haplotype was the most common. The DRB1*1106‐DQB1*0301/0304 haplotype was found only in North‐eastern Thais and not in other Thai populations. Comparative analysis of the HLA‐DR/DQ alleles revealed differences in the distributions of these alleles amongst different ethnic groups. Interestingly, the distributions of HLA class II alleles in Central Thai, North‐eastern Thai and Southern Chinese populations are similar. However, it appears that the distribution in the Central Thais is a mixture of those in Southern Chinese and North‐eastern Thais, suggesting the existence of Thai–Chinese admixtures in the Central Thai population. This study provides basic information for further studies of the MHC in anthropology, organ transplantation and disease susceptibility in the North‐eastern Thai population.

Distributions of HLA‐DRB1/DQB1 alleles and haplotypes in the North‐eastern Thai population: indicative of a distinct Thai population with Chinese admixtures in the Central Thais

The phenotype and gene frequencies of HLA class II alleles were studied in the North‐eastern Thai population. Blood samples were collected from 100 unrelated healthy North‐eastern Thais. The HLA‐DRB1 and DQB1 genes were typed using the polymerase chain reaction – sequence specific primer (PCR‐SSP) and polymerase chain reaction – sequence specific oligonucleotide probe (PCR‐SSO) techniques. Twenty‐six HLA‐DRB1 and 11 DQB1 alleles were found in this population. DRB1*1202, 1502, 0405 and DQB1*0502/0504, 0301/0304 alleles were commonly found. Linkage disequilibrium analysis suggested the existence of 13 DR‐DQ haplotypes. The DRB1*1502‐DQB1*0501 haplotype was the most common. The DRB1*1106‐DQB1*0301/0304 haplotype was found only in North‐eastern Thais and not in other Thai populations. Comparative analysis of the HLA‐DR/DQ alleles revealed differences in the distributions of these alleles amongst different ethnic groups. Interestingly, the distributions of HLA class II alleles in Central Thai, North‐eastern Thai and Southern Chinese populations are similar. However, it appears that the distribution in the Central Thais is a mixture of those in Southern Chinese and North‐eastern Thais, suggesting the existence of Thai–Chinese admixtures in the Central Thai population. This study provides basic information for further studies of the MHC in anthropology, organ transplantation and disease susceptibility in the North‐eastern Thai population.

Distributions of HLA-DRB1/DQB1 alleles and haplotypes in the north-eastern Thai population: indicative of a distinct Thai population with Chinese admixtures in the central Thais.

The phenotype and gene frequencies of HLA class II alleles were studied in the North-eastern Thai population. Blood samples were collected from 100 unrelated healthy North-eastern Thais. The HLA-DRB1 and DQB1 genes were typed using the polymerase chain reaction--sequence specific primer (PCR-SSP) and polymerase chain reaction--sequence specific oligonucleotide probe (PCR-SSO) techniques. Twenty-six HLA-DRB1 and 11 DQB1 alleles were found in this population. DRB1*1202, 1502, 0405 and DQB1*0502/0504, 0301/0304 alleles were commonly found. Linkage disequilibrium analysis suggested the existence of 13 DR-DQ haplotypes. The DRB1*1502-DQB1*0501 haplotype was the most common. The DRB1*1106-DQB1*0301/0304 haplotype was found only in North-eastern Thais and not in other Thai populations. Comparative analysis of the HLA-DR/DQ alleles revealed differences in the distributions of these alleles amongst different ethnic groups. Interestingly, the distributions of HLA class II alleles in Central Thai, North-eastern Thai and Southern Chinese populations are similar. However, it appears that the distribution in the Central Thais is a mixture of those in Southern Chinese and North-eastern Thais, suggesting the existence of Thai-Chinese admixtures in the Central Thai population. This study provides basic information for further studies of the MHC in anthropology, organ transplantation and disease susceptibility in the North-eastern Thai population.

Low erythrocyte Na/K-pump activity and number in Northeast Thailand adults: Evidence suggesting an acquired disorder

Healthy northeastern Thais have a higher erythrocyte sodium concentration and a lower erythrocyte membrane Na,K-adenosine triphosphatase (ATPase) activity than central Thais. To elucidate whether the defect is hereditary or acquired, we studied plasma sodium and potassium and erythrocyte sodium, potassium, Na,K-ATPase activity, and ouabain-binding sites (OBS) in the following groups: healthy newborns of ethnic central Thais (group 1), healthy newborns of ethnic northeast Thais (group 2), healthy adults of central Thailand ethnicity who lived in the rural central region (group 3) or in Bangkok (group 4), healthy adults of northeast Thailand ethnicity who lived in the rural northeast region (group 5) or who migrated to work in Bangkok for at least 1 year (group 6). Erythrocyte Na was higher in group 2 than in group 1. Group 3 had lower erythrocyte Na,K-ATPase activity than group 4, and it was lower in group 5 than in group 6. Among all groups, group 5 had the highest erythrocyte Na (11.6 mmol/L, F < 0.0001) and the lowest Na,K-ATPase activity (63 mmol Pi/mg · h, F < 0.0001) and erythrocyte OBS (397 sites per cell, F < 0.05) than the other adult groups. There was a positive correlation between erythrocyte Na,K-ATPase and erythrocyte OBS ( r = .416, P < .0001). Multiple regression analysis demonstrated a correlation between erythrocyte Na as a dependent variable and erythrocyte OBS, plasma potassium, erythrocyte potassium, and erythrocyte Na,K-ATPase ( r = .517, P < .0001). The erythrocyte Na,K-ATPase/OBS ratio, an expression of Na,K-ATPase activity equalized for the number of Na,K-pump units, was lowest among rural adults of the central region (group 3) and the northeast region (group 5) (F < 0.0002). Our data suggest that rural dwellers in Thailand tend to have lower erythrocyte Na,K-ATPase activity than urban dwellers and that this is probably acquired after birth. It was more severe among those from the northeast versus the central region, and was less severe among those who migrated to an urban area. This defect in northeast rural dwellers was probably associated with low numbers of Na,K-pump units and a defect of the pump to express activity, whereas in central rural dwellers it was probably associated with the latter condition. We postulate that there might be circulating Na,K-pump inhibitors and metabolic disturbances that cause attenuation of Na,K-ATPase function and synthesis in the northeast Thailand rural population, and that such substances may have an environmental origin. There may be a relationship between these abnormalities and sudden unexpected deaths.