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Biomedical subjects

D Chandanayingyong

Publications and source records attributed to D Chandanayingyong.

At least 19 recordsLinked to original sources
PubMed1998

Predominance of HLA-restricted cytotoxic T-lymphocyte responses to serotype-cross-reactive epitopes on nonstructural proteins following natural secondary dengue virus infection.

We examined the memory cytotoxic T-lymphocytic (CTL) responses of peripheral blood mononuclear cells (PBMC) obtained from patients in Thailand 12 months after natural symptomatic secondary dengue virus infection. In all four patients analyzed, CTLs were detected in bulk culture PBMC against nonstructural dengue virus proteins. Numerous CD4+ and CD8+ CTL lines were generated from the bulk cultures of two patients, KPP94-037 and KPP94-024, which were specific for NS1.2a (NS1 and NS2a collectively) and NS3 proteins, respectively. All CTL lines derived from both patients were cross-reactive with other serotypes of dengue virus. The CD8+ NS1.2a-specific lines from patient KPP94-037 were HLA B57 restricted, and the CD8+ NS3-specific lines from patient KPP94-024 were HLA B7 restricted. The CD4+ CTL lines from patient KPP94-037 were HLA DR7 restricted. A majority of the CD8+ CTLs isolated from patient KPP94-024 were found to recognize amino acids 221 to 232 on NS3. These results demonstrate that in Thai patients after symptomatic secondary natural dengue infections, CTLs are mainly directed against nonstructural proteins and are broadly cross-reactive.

CD4-Positive T-Lymphocytes↗
PubMed1997

HLA-A, -B, -DRB1, -DQA1, and -DQB1 polymorphism in Thais.

In this study we examined HLA-A, -B, -DRB1, -DQA1, and -DQB1, gene allele, and haplotype frequencies in two ethnic Thai populations. We compared these frequencies to the known HLA class I and II allele profiles of non-Thai mainland and insular Southeast (SE) Asians. HLA-A locus gene and allele frequencies, are comparatively homogeneous in both Thai and non-Thai SE Asians. In contrast, HLA-B; -DRB1, -DQA1, and -DQB1 gene and allele frequencies, show more ethnic and geographic variation in SE Asians. Conserved haplotypes, or combinations of linked HLA class I and II alleles were detected in Thais, but at relatively low frequencies. It would appear that ethnic Thais, reflect an admixture of peoples from both the northern mainland and southern island groups of SE Asia.

China↗
PubMed1997

HLA class I typing by one-dimensional isoelectric focusing and identification of the new variants in Thai population.

One-dimensional isoelectric focusing (1D-IEF) is the technique to define HLA class I antigens based on difference in isoelectric point of HLA molecules. Different IEF subtypes are shown in different populations. In this study, 1D-IEF was employed to study HLA-A and -B subtypes in Thai population. A panel of 117 samples including all serologically defined HLA-A and -B antigens in Thai population were typed by 1D-IEF. Serological specificities and subtypes correlated well with IEF results and some antigens with unclear serological specificities could be confirmed by IEF. In addition, more subtypes could be obtained by IEF than by serology. A total of 17 IEF subtypes from HLA-A and 31 IEF subtypes from HLA-B could be identified. The subtypes predominantly found in Thai population were A2.3, A24.2, A11.1, A33.2, B15.2, B7.1 and B13.1. In addition, new IEF variants were identified in HLA-B35, B5, B56 and B48. The band positions of these variants were different from those previously described. These IEF subtypes are HLA gene products which may be important in transplantation. The combination of IEF and serology for HLA typing can provide a better definition of each allelic product of HLA-A and -B.

Histocompatibility Antigens Class I↗
PubMed1997

HLA class II allele frequencies in northern Thais (Kamphaeng Phet).

The polymorphism of HLA class II genes (HLA-DRB1, -DQA1, -DQB1 and -DPB1) was investigated in 97 normal Northern Thais (NT) from Kamphaeng Phet province using PCR-SSO typing. Allele frequencies (AF) have been determined. DRB1*1202 (17.5%), DRB1*1502 (16.5%), DQA1*0101 (25.8%), DQA1*0102 (21.7%), DQB1*0502 (22.7%), DPB1*0501 (23.2%) and DPB1*1301 (22.7%) showed the highest frequencies in each locus. These results were more similar to those observed in Present-day Thais (PDT) and Central Thais (CT) than Northern Thais from Chiang Mai (CM) and Dai Lue (DL). However, the data presented in this population study should be useful in many fields, such as anthropology, organ transplantation, disease susceptibility and evolutionary genetics.

Alleles↗
PubMed1996

The Dai minority population of southwest China: heterogeneity of DR2-associated HLA-DRB1,DRB5,DQA1, and DQB1 haplotypes.

HLA-DR2 is the most common DR specificity (60.3%) identified in the Dai minority population of Xishuangbanna, Yunna Province, China. We characterized the DRB1, DRB5, DQA1, and DQB1 alleles of 44 unrelated DR2-positive individuals, 11 of whom (15%) were DR2 homozygous. Four DRB1 and four DRB5 alleles encoding DR2 were identified in this population. The most frequent DR2-associated DRB1 alleles were *1602 (gf = 0.164) and *1502 (gf = 0.151). DRB1*1501 (gf = 0.048) and a new allele designated DRB1*1504 (gf = 0.014) were also detected, but *1601 and *1503 were absent. The most frequent DR2-associated DRB5 alleles were *0101 (gf = 0.233) and *0102 (gf = 0.110). Nine different DR2-associated DR/DQ haplotypes were identified. The two most common DR2 haplotypes were DRB1*1602, DRB5*0101, DQA1*0102, DQB1*0502 (hf = 0.142) and DRB1*1502, DRB5*0102, DQA1*0101, DQB1*0501 (hf = 0.075). The new DRB1*1504 allele was found on a single haplotype: DRB1*1504, DRB5*0101, DQA1*0102, DQB1*0502 (hf = 0.017). The Dw2, Dw12, Dw21, and Dw22 haplotypes, present in many other Asian and Mongoloid populations, were not identified in this unique group. However, the Dai minority population is characterized by a relatively large number of diverse DR2 haplotypes and a new DRB1 allele encoding DR2.

China↗
PubMed1996

Structural definition of the A*74 group: implications for matching in bone marrow transplantation with alternative donors.

We have identified two new A*74 alleles (A*7402 and 7403) in two unrelated individuals. A*7402 differs from A*7401 by a single amino acid substitution in the signal peptide and may be the result of a gene conversion event at the 3' end of exon 1. A*7403 differs from A*7401 by a single amino acid exchange in the alpha 1 domain and is most likely due to a point mutation in exon 2, since no HLA class I donor allele has been found. Since A*7402 appears to be the ancestor of the other two A*74 alleles, it is possible that A*7401 and 7403 have been created by successive point mutations. The sequences of the expressed proteins of A*7401 and 7402 are identical. The heavy chain sequence of A*7403 differs from these alleles at the crucial residue 79 which is located in the sequence stretch of the alpha 1 alpha-Helix where the Bw4/Bw6 determinants have been identified and which probably affects TCR interaction. This variation can therefore be expected to stimulate alloreactive T cells, graft rejection and graft versus host disease emphasizing the relevance for matching in bone marrow transplantation with alternative donors.

Alleles↗
PubMed1996

Estimated rate of HIV-1-infectious but seronegative blood donations in Bangkok, Thailand.

OBJECTIVES: To determine HIV seroprevalence and incidence among various blood donor types, and to estimate the rate of window-period blood donations. DESIGN: Retrospective cohort from computerized donor records. METHODS: Records were analysed from all 60,483 donors (contributing 97,464 donor units) at a public university teaching hospital blood bank in Bangkok, Thailand, from 1 January 1990 to 30 June 1993. Annual HIV incidence among 14,482 repeat donors who were HIV-seronegative on their first donation was calculated assuming equal probability of seroconversion between last seronegative and first seropositive donations. To estimate the probability of window-period donations, we assumed that the time from HIV infectivity to onset of detectable antibody was 45 days. RESULTS: In 1990, HIV incidence calculated for all repeat donors was 307 per 100,000 person-years; the probability of a window-period donation was 38 in 100,000 donations or one in 2644 donations. During 1991-1993, this probability decreased by one-half. However, one-time donors were more than twice as likely as repeat donors to be HIV-1-seropositive. CONCLUSIONS: The rate of HIV window-period blood donations among Thai repeat donors was relatively high compared with that in developed countries and was probably even higher among one-time donors. Improved donor deferral criteria are needed in Thailand.

Blood Donors↗
PubMed1995

The presence of the HLA class II allele DPB1*0501 in ethnic Thais correlates with an enhanced vaccine-induced antibody response to a malaria sporozoite antigen.

In this study, we examined the correlation between the frequency of allelic variants of the class II human leukocyte antigen (HLA) DR, DQ and DP gene loci and the quantitative humoral immune response observed in 71 Thai volunteers, subsequent to vaccination with a conjugated subunit vaccine. This vaccine was designed to induce antibodies directed against the immunodominant repeat region of the Plasmodium falciparum circumsporozoite (CS) protein. The presence of the DPB1*0501, a relatively common allele in Asian populations, was found to be associated with high vaccine-induced CS repeat-specific antibody responses in the volunteers. Given the increasing focus on the use of subunit vaccines in the control of infectious diseases, consideration of the influence of class II allele frequencies in ethnically diverse recipient populations may be important.

Adult↗
PubMed1995

Collection of cord blood stem cells for transplantation in thalassemic patients.

Thalassemia is widely distributed throughout the world and is one of the major public health problems. The use of bone marrow transplantation, the only curative therapy for thalassemia, is limited because less than 30% of the patients have unaffected and HLA-identical siblings as donors. Cord blood stem cells, an alternative source of stem cells for transplantation, have been successfully transplanted into patients with several diseases after myeloablative therapy. Twenty cord blood samples from unaffected neonates whose siblings had severe thalassemia were collected. The median volume was 80 ml. The median number of cells and colony forming units-granulocyte-macrophage in cord blood was 9.2 x 10(8) and 3.4 x 10(5), respectively. Four of 20 cord blood samples had HLA-matched to the affected siblings. One patient underwent cord blood transplantation with success; one patient is waiting for transplantation.

Blood Specimen Collection↗
PubMed1994

HLA-DPB1 polymorphism in the Thais of Southeast Asia.

In this study we examined DPB1 allele frequencies in five ethnic Thai populations resident in different regions of Thailand and neighboring countries. In contrast to other Asian and Pacific populations such as the Japanese, Chinese, Korean, and Papua New Guineans, where DPB1*0501 has consistently been shown to be the most frequent allele, NE Thais and Thai-Khmers demonstrate a prevalence of DPB1*1301. Comparison of DPB1 allele frequencies in the Thais of SE Asia, with known frequencies in the Chinese and Japanese populations of E Asia, would appear to confirm previous calculations of genetic divergence between these Oriental populations.

Alleles↗
PubMed1994

Potential deferral criteria predictive of human immunodeficiency virus positivity among blood donors in Thailand.

BACKGROUND: To develop deferral criteria to prevent human immunodeficiency virus (HIV) transmission by recently infected blood donors in the seronegative "window" phase, routine data on donors at a university hospital were examined for factors predicting seropositivity. STUDY DESIGN AND METHODS: Records of all 281 HIV-positive blood donors from August 1987 through September 1991 were retrospectively compared with those of 1076 randomly selected control donors matched only by year of donation. Four controls were selected for each HIV-positive donor. RESULTS: The prevalence of HIV in 102,684 donor units during the period rose from 0.02 percent in 1987 to 0.52 percent in 1991. Multivariable analysis revealed that male sex (odds ratio [OR] = 26.4), VDRL test positivity (OR = 3.0), age 21 to 30 years (OR = 2.2; referent: 16-20-year-old group), and replacement donorship (OR = 1.4; referent: voluntary donors) were independent factors significantly associated with HIV positivity among these donors (p < 0.05). Since replacement donorship cannot be avoided, only male sex, age 21 to 30 years, and VDRL test positivity were considered as potential criteria. When these findings were extrapolated to all donors in 1990 and 1991, those with all three or only two (excluding VDRL test, because the results are known only after donation) of these high-risk factors had HIV positivity probabilities of 2.2 and 1.0 percent, respectively. These probabilities were, respectively, 4.9 times (95% CI: 2.9 8.3) and 4.1 times (3.1, 5.4) the risk among other donors. However, applying such criteria would have eliminated 1.5 and 31.2 percent, respectively, of all HIV-negative donors in 1990 and 1991. The latter deferral proportion is too high to be acceptable. CONCLUSION: In Thailand, improved donor deferral criteria addressing sexual risk factors could lead to decreased probability of window-period donation, with an acceptable rate of deferral. Additional p24 antigen testing may be indicated for donors at increased risk for HIV infection, specifically, men aged 21 to 30.

Adolescent↗
PubMed1993

Factor VIII, factor IX and fibrinogen content in cryoprecipitate, fresh plasma and cryoprecipitate-removed plasma.

In order to provide accurate information for physicians, factor VIII, factor IX and fibrinogen content were determined in 40 bags of cryoprecipitate, fresh plasma and cryoprecipitate-removed plasma. A cryoprecipitate bag with a volume of 21.8 +/- 5.3 ml contained 139.5 +/- 42.9 units of factor VIII and 200.0 +/- 80.0 mg of fibrinogen. Fresh plasma with a volume of 208.0 +/- 22.5 ml contained 180.9 +/- 45.3 of factor IX, significantly higher than in cryoprecipitate-removed plasma. It was also found in this study that group O blood showed a significantly lower level of factor VIII.

ABO Blood-Group System↗
PubMed1993

Preoperative autologous blood collection and haemodilution with gelatin solution (gelifundol).

Autologous blood collection and haemodilution with gelatin solution had an effect on the decrease in red blood cells, haemoglobin, haemotocrit, fibrinogen and platelets; however, this technique had no effect on coagulograms, platelet function and haemostasis. In conclusion, this technique is suitable and possibly practical in obtaining sufficient blood for elective surgical patients and is without any undesirable side effects.

Adolescent↗