Onanong Kritpetcharat

Genetic analysis of the merozoite surface protein-1 block 2 allelic types in Plasmodium falciparum clinical isolates from Lao PDR

BackgroundMSP-1 is one of the potential malarial vaccine candidate antigens. However, extensive genetic polymorphism of this antigen in the field isolates of Plasmodium falciparum represents a major hindrance for the development of an effective vaccine. Therefore, this study aimed to establish the prevalence and genetic polymorphisms of K1, MAD20 and RO33 allelic types of msp-1 block 2 among P. falciparum clinical isolates from Lao PDR.MethodsPlasmodium falciparum isolates were collected from 230 P. falciparum-infected blood samples from three regions of Lao PDR. K1, MAD20 and RO33 were detected by nested PCR; SSCP was used for polymorphism screening. The nested PCR products of each K1, MAD20 and RO33 allelic types that had different banding patterns by SSCP, were sequenced.ResultsThe overall prevalence of K1, MAD20 and RO33 allelic types in P. falciparum isolates from Lao PDR were 66.95%, 46.52% and 31.30%, respectively, of samples under study. Single infections with K1, MAD20 and RO33 allelic types were 27.83%, 11.74% and 5.22%, respectively; the remainders were multiple clonal infections. Neither parasite density nor age was related to MOI. Sequence analysis revealed that there were 11 different types of K1, eight different types of MAD20, and 7 different types of RO33. Most of them were regional specific, except type 1 of each allelic type was common found in 3 regions under study.ConclusionsGenetic polymorphism with diverse allele types was identified in msp-1 block 2 among P. falciparum clinical isolates in Lao PDR. A rather high level of multiple clonal infections was also observed but the multiplicity of infection was rather low as not exceed 2.0. This basic data are useful for treatment and malaria control program in Lao PDR.

Comparison of Pap Smear Screening Results between Akha Hill Tribe and Urban Women in Chiang Rai Province, Thailand

Cervical cancer is an important womans health problems worldwide, especially in low socio-economic countries. The aim of this study was to compare the Pap smear screening results between Akha hill tribe and urban women who live in Chiang Rai province, Thailand. Screening was conducted for 1,100 Akha women and 1,100 urban women who came to have the Pap smear at Chiangrai Prachanukroh Hospital and 1 private cytology laboratory from January to June 2008. The demographic characteristics and factors related to abnormal Pap smears of these women were gathered using closed model questionnaires. Abnormal Rap smears were defined according to the Bethesda 2001 system. The results showed that the prevalence of abnormal Pap smears was 12.2% in Akha women and 4.5% in urban women. The highest prevalence of Pap abnormalities was found in the 41-50 years age group in both populations (4.5% in Akha and 1.7% in urban women). In both populations, abnormal Pap smears were found in <21 years age groups. From the questionnaires, the possible risk factors related to the higher prevalence of abnormal Pap smears in Akha women were early age at marriage (≤17 years), high frequency pregnacies and high parity and no/low education level. In conclusion, cervical cancer control by education and early detection by Pap smear screening is necessary for hill tribe women. More Pap smear screening service units should be set to improve the coverage for the risk group women who got married in young age, especial in ethnic groups.

A single-round multiplex PCR assay for the identification of Anopheles minimus related species infected with Plasmodium falciparum and Plasmodium vivax

This study aimed to develop a single-round multiplex PCR method for the identification of Anopheles minimus complex (An. minimus and Anopheles harrisoni) and Anopheles aconitus subgroup (An. aconitus and Anopheles varuna), and for the simultaneous detection of Plasmodium falciparum and Plasmodium vivax in these vectors. Five primers were created for a single-round multiplex PCR assay to identify four anopheline mosquitoes combined with three Plasmodium primers for the detection of P. falciparum and P. vivax in vectors. The four species of anopheline vectors and two Plasmodium species, P. falciparum and P. vivax, could be identified by the combination of eight primers in the single-round multiplex PCR assay. The amplified species-specific products were 380bp for An. minimus, 180bp for An. harrisoni, 150bp for An. aconitus, 310bp for An. varuna, 276bp for P. falciparum, and 300bp for P. vivax. The sensitivities were 0.5pg/μl (25sporozoites/μl) for P. falciparum DNA and between 0.5 and 5pg/μl (25-250sporozoites/μl) for P. vivax DNA. Furthermore, this developed method could be used to identify field caught An. minimus complex, An. aconitus subgroup from Thailand and Lao PDR. Also, it was successfully used to identify the species An. minimus, An. harrisoni, An. aconitus and An. varuna and to detect and identify P. falciparum and P. vivax in caught anopheline mosquitoes. The sensitivity of this method was high for simultaneous detection of P. falciparum and P. vivax in anopheline mosquitoes.

Chromosome Abnormalities and Absolute Telomere Lengths of Leukocytes from Silk Weavers with Emphasis on Potential Genotoxicity and Mutagenicity of Silk Dyes

Objectives: This study is aimed to assess the possible genotoxicity and mutagenicity of silk dyes on silk weavers. Methods: Peripheral blood leukocytes were obtained from 24 silk weavers and 24 age- and sex-matched controls in northeastern Thailand. After mitogen stimulation in culture, chromosome abnormalities were examined using Giemsa banding and the absolute telomere length (aTL) was measured with SYBR green qRT-PCR. To confirm genotoxic and mutagenic effects of silk dyes, leukocytes from one each of healthy male and female volunteers were cultured with various concentrations of 3 dark red silk dyes under the presence of mitogen. Chromosome abnormalities and the telomere length were determined as above. Results: The proportion of normal metaphase in the silk weaving workers was significantly lower than that in controls. The frequency of chromosome aberrations was higher in the silk weavers than in control group. Polyploidy was detected only in the silk weavers. The aTL was significantly shorter in the silk weavers than in control group (p < 0.05). When leukocytes from normal volunteers were stimulated with mitogen under the presence of various concentrations of 3 silk dyes, suppressed the mitotic index (MI) and normal metaphase, whereas the proportion of prophase and the incomplete chromosome forming increased significantly. All dyes induced polyploidy. Dye #CA5 induced structural changes in male leukocytes, whereas #30 induced the changes in female leukocytes. The #CA5 increased aTL of normal leukocytes in a dose-dependent manner. Conclusions: All dyes, especially #CA5, have high genotoxicity and mutagenicity to induce chromosome aberrations and telomeric instability. Taken all those results together, regular health checking of silk weavers who have been exposed to those dyes is critically necessary to prevent various chemical-induced carcinogenesis.