Co-infection with Opisthorchis viverrini and Haplorchis taichui detected by human fecal examination in Chomtong district, Chiang Mai Province, Thailand

Diseases caused by the liver fluke, Opisthorchis viverrini and the minute intestinal fluke, Haplorchis taichui, are clinically important, especially in the Northeast and North regions of Thailand. It is often difficult to distinguish between these trematode species using morphological methods due to the similarity of their eggs and larval stages both in mixed and co-infections. A sensitive, accurate, and specific detection method of these flukes is required for an effective epidemiological control program. This study aimed to determine the prevalence of O. viverrini and H. taichui infections in human feces by using formalin-ether sedimentation and high annealing temperature random amplified polymorphic DNA (HAT-RAPD) PCR methods. Fecal specimens of people living along the Mae Ping River, Chomtong district were examined seasonally for trematode eggs using a compound microscope. Positive cases were analyzed in HAT-RAPD, DNA profiles were compared with adult stages to determine the actual species infected, and specific DNA markers of each fluke were also screened. Our results showed that out of 316 specimens, 62 were positive for fluke eggs which were pre-identified as O. viverrini and H. taichui. In addition, co-infection among these two fluke species was observed from only two specimens. The prevalence of H. taichui infections peaked in the hot-dry (19.62%), gradually decreased in the rainy (18.18%), and cool-dry seasons (14.54%), respectively. O. viverrini was found only in the hot-dry season (6.54%). For molecular studies, 5 arbitrary primers (Operon Technologies, USA) were individually performed in HAT-RAPD-PCR for the generation of polymorphic DNA profiles. The DNA profiles in all 62 positives cases were the same as those of the adult stage which confirmed our identifications. This study demonstrates the mixed infection of O. viverrini and H. taichui and confirms the extended distribution of O. viverrini in Northern Thailand.     

Molecular modeling of nitrosamines adsorbed on H-ZSM-5 zeolite: An ONIOM study

Binding energies of nitrosamine compounds, N-nitrosamine (NA), N-methyl-N-nitrososamine (NMA), N-ethyl-N-nitrososamine (NEA), N,N-dimethyl-N-nitrosoamine (NDMA), N-ethyl-N-methyl-N-nitrosoamine (NEMA) and N,N-diethyl-N-nitrosoamine (NDEA) on the H-ZSM-5 zeolite were obtained using the ONIOM(B3LYP/6–31G(d):AM1) approach. Based on amino and imino isomers of nitrosamines, there are two adsorption configurations on the H-ZSM-5 for NA (as NA_a and NA_i), NMA (as NMA_a and NMA_i) and NEA (as NEA_a and NEA_i). The relative binding energies of nitrosamines are in order: NA_a > NMA_a ~ NEA_a > NA_i > NMA_i ~ NEA_i > NEMA ~ NDEA > NDMA. The order of adsorption selectivity for nitrosamines of the H-ZSM-5 is NA_a ~ NA_i >> NMA_a ~ NEA_a > NDMA ~ NMA_i ~ NEMA > NDEA ~ NEA_i. The selective recognition of the NA by the H-ZSM-5 was obviously found. Figure The optimized structures of adsorption complexes with the most stable conformers of the N-methyl-N-nitrososamine (NMA), N-ethyl-N-nitrososamine (NEA), N,N-dimethyl-N-nitrososamine (NDMA), N-ethyl-N-methyl-N-nitrososamine (NEMA) and N,N-diethyl-N-nitrososamine (NDEA) on the H-ZSM-5 zeolite     

Experimental Life History and Biological Characteristics of Fasciola gigantica (Digenea: Fasciolidae)

This study was conducted to investigate the life history, morphology, and maturation of larval stages and adult worms of Fasciola gigantica in experimental mice. Lymnaea auricularia rubiginosa was used as the intermediate host, and Oryza sativa was used for encystment of the metacercariae, while Mus musculus was used as the definitive host for maturation study. Fresh eggs from the gall bladder of water buffaloes fully developed into embryonated ones and hatched out at days 11-12 after incubation at about 29ºC. Free-swimming miracidia rapidly penetrated into the snail host, and gradually developed into the next larval stages; sporocyst, redia, and daughter redia with cercariae. Fully-developed cercariae were separated from the redia and shed from the snails on day 39 post-infection (PI). Free-swimming cercariae were immediately allowed to adhere to rice plants, and capsules were constructed to protect metacercariae on rice plants. Juvenile worms were detected in intestines of mice at days 3 and 6 PI, but they were found in the bile duct from day 9 PI. Juvenile and adult flukes were recovered from 16 mice experimentally infected with metacercariae, with the average recovery rate of 35.8%. Sexually mature adult flukes were recovered from day 42 PI. It could be confirmed that experimentally encysted metacercariae could infect and develop to maturity in the experimental host. The present study reports for the first time the complete life history of F. gigantica by an experimental study in Thailand. The obtained information can be used as a guide for prevention, elimination, and treatment of F. gigantica at environment and in other hosts.     

Complete Amino Acid Sequence of Globin Chains and Biological Activity of Fragmented Crocodile Hemoglobin (Crocodylus siamensis)

Hemoglobin, ??-chain, ??-chain and fragmented hemoglobin of Crocodylus siamensis demonstrated both antibacterial and antioxidant activities. Antibacterial and antioxidant properties of the hemoglobin did not depend on the heme structure but could result from the compositions of amino acid residues and structures present in their primary structure. Furthermore, thirteen purified active peptides were obtained by RP-HPLC analyses, corresponding to fragments in the ??-globin chain and the ??-globin chain which are mostly located at the N-terminal and C-terminal parts. These active peptides operate on the bacterial cell membrane. The globin chains of Crocodylus siamensis showed similar amino acids to the sequences of Crocodylus niloticus. The novel amino acid substitutions of ??-chain and ??-chain are not associated with the heme binding site or the bicarbonate ion binding site, but could be important through their interactions with membranes of bacteria.