Biomedical subjects

Somei Kojima

Publications and source records attributed to Somei Kojima.

13 recordsLinked to original sources

PubMed2005

The current situation regarding the establishment of national ethical guidelines for biomedical research in Thailand and its neighboring countries.

This study discusses the establishment of ethical guidelines for ethical review for biomedical research performed in Thailand, and to some extent, in neighboring countries. There are differences, from country to country, at national and institutional levels regarding guidelines for ethical review committees. Only a handbook issued by Mahidol University describes guidelines for human genetic research and on research dealing with reproductive technology. Both these areas require special consideration to avoid violating human dignity, rights, and confidentiality. This indicates that further efforts should be made to establish research guidelines and/or principles dealing with the human genome.

Biomedical Research↗

PubMed2004

A potential role of interleukin 18 in severe falciparum malaria.

Interleukin-18 (IL-18) is a potent proinflammatory cytokine that induces interferon-gamma (IFN-gamma) production from Th1 cells, NK cells and activated macrophages, particularly in the presence of IL-12. However, it is also shown that without help from IL-12, IL-18 is capable of inducing IL-4 and IL-13 production in T cells, NK cells, mast cells and basophils, and that administration of IL-18 in conjunction with an allergen increases serum IgE levels. In order to clarify the role of IL-18 in disease severity of falciparum malaria, we have examined serum levels of IL-18, IFN-gamma, and IgE for 96 patients with falciparum malaria [Trans. R. Soc. Trop. Med. Hyg. 97, 236-241]. Results suggested that IL-18 plays a key role in inducing severe malaria through a pathway of elevating IFN-gamma, rather than its IgE inducing activity. Based on these results, the role of IL-18 in severe falciparum malaria will be discussed in this review.

Adolescent↗

PubMed2004

Overview: from the horse experimentation by Prof. Akira Fujinami to paramyosin.

Professor Akira Fujinami demonstrated for the first time in the world that acquired immunity might be induced against macroparasites such as schistosomes. Since then, vaccination models have been developed using various species of animals, among which the attenuated vaccine model in the mouse has been utilized mostly to clarify immune effector mechanisms and define candidate vaccine molecules. However, further studies are necessary on immune responses to defined parasite molecules in humans, because some discrepancies in immune responses still exist between animals and humans, and apparently genetic influence should be taken into consideration in such studies on defined molecules. Despite of some limitations, vaccine trials in livestock against Schistosoma japonicum may provide useful information for development of vaccines against the other human infections caused by S. mansoni or S. haematobium. In this overview, studies carried out mainly by Japanese investigators towards vaccine development will be described.

Animals↗

PubMed2004

Applicability of a monoclonal antibody-based dipstick in diagnosis of urinary schistosomiasis in the Central Region of Ghana.

Summary We tested a rapid visually read monoclonal antibody (MoAb) based dipstick assay for specific diagnosis of urinary schistosomiasis against microscopy and the use of haematuria and proteinuria in a schistosomiasis haematobia endemic area in the Central Region of Ghana. The study group consisted of 141 school children (83 males, 58 females) aged 8-19 years. A total of 129 of 141 (91.5%) submitted stool samples, and 7.8% had Schistosoma mansoni, 55% had hookworms and 6.2% had tapeworms. The presence of S. mansoni and intestinal parasites did not appear to influence the results of the MoAb-dipstick assay. The urinary schistosomiasis prevalence by MoAb-dipstick (78%) was higher (P < 0.05) than the estimate by microscopy (60.3%), microhaematuria (27%) and proteinuria (30.5%). The MoAb-dipstick correctly identified 98.8% of microscopically confirmed cases and missed one (1.3%). The dipstick was also positive for 26 of 56 (46.4%) egg-negative individuals, thereby giving a sensitivity of 98.8% and a specificity of 53.6%. On the other hand, microhaematuria and proteinuria were 38.8% and 30.6% sensitive, and 91.1% and 69.6% specific, respectively. Microhaematuria and proteinuria were less sensitive (P < 0.05) than both microscopy and MoAb-dipstick.

Adolescent↗

PubMed2004

The use of flow cytometry as a diagnostic test for malaria parasites.

A total of 453 clinical blood samples were determined for malaria parasites by flow cytometric assay (FCM) and reagents from Sysmex Corporation, Japan. In this study, the FCM greatly simplified and accelerated parasite detection, with sensitivity of 91.26%, specificity 86.28% and accuracy 87.42%. Overall, the parasite counts by flow cytometric measurement correlated well with the parasitemia measured by microscopic assay (regression coefficient = 0.9409). The detection limit was 0.05-0.1% parasitemia. No evidence of malaria parasites in either blood donor volunteers or other disease patients groups was determined by FCM. However, 48 samples who had been treated with antimalarial drugs and whose parasite microscopic counts were negative, showed false-positive results. When the data of these 48 samples were analyzed, they were found to have high levels of reticulocytes, ranging from 2.0-18.9%. This finding suggested that a high reticulocyte concentration in the blood may interfere with the performance of the FCM. Further improvement, by eliminating this interference, will make the FCM one of the most promising tests for malaria diagnosis.

Animals↗

PubMed2003

Isolation and characterization of the stage-specific cytochrome b small subunit (CybS) of Ascaris suum complex II from the aerobic respiratory chain of larval mitochondria.

We recently reported that Ascaris suum mitochondria express stage-specific isoforms of complex II: the flavoprotein subunit and the small subunit of cytochrome b (CybS) of the larval complex II differ from those of adult enzyme, while two complex IIs share a common iron-sulfur cluster subunit (Ip). In the present study, A. suum larval complex II was highly purified to characterize the larval cytochrome b subunits in more detail. Peptide mass fingerprinting and N-terminal amino acid sequencing showed that the larval and adult cytochrome b (CybL) proteins are identical. In contrast, cDNA sequences revealed that the small subunit of larval cytochrome b (CybS(L)) is distinct from the adult CybS (CybS(A)). Furthermore, Northern analysis and immunoblotting showed stage-specific expression of CybS(L) and CybS(A) in larval and adult mitochondria, respectively. Enzymatic assays revealed that the ratio of rhodoquinol-fumarate reductase (RQFR) to succinate-ubiquinone reductase (SQR) activities and the K(m) values for quinones are almost identical for the adult and larval complex IIs, but that the fumarate reductase (FRD) activity is higher for the adult form than for the larval form. These results indicate that the adult and larval A. suum complex IIs have different properties than the complex II of the mammalian host and that the larval complex II is able to function as a RQFR. Such RQFR activity of the larval complex II would be essential for rapid adaptation to the dramatic change of oxygen availability during infection of the host.

Aerobiosis↗

PubMed2003

Complex II from phototrophic purple bacterium Rhodoferax fermentans displays rhodoquinol-fumarate reductase activity.

It has long been accepted that bacterial quinol-fumarate reductase (QFR) generally uses a low-redox-potential naphthoquinone, menaquinone (MK), as the electron donor, whereas mitochondrial QFR from facultative and anaerobic eukaryotes uses a low-redox-potential benzoquinone, rhodoquinone (RQ), as the substrate. In the present study, we purified novel complex II from the RQ-containing phototrophic purple bacterium, Rhodoferax fermentans that exhibited high rhodoquinol-fumarate reductase activity in addition to succinate-ubiquinone reductase activity. SDS/PAGE indicated that the purified R. fermentans complex II comprises four subunits of 64.0, 28.6, 18.7 and 17.5 kDa and contains 1.3 nmol heme per mg protein. Phylogenetic analysis and comparison of the deduced amino acid sequences of R. fermentans complex II with pro/eukaryotic complex II indicate that the structure and the evolutional origins of R. fermentans complex II are closer to bacterial SQR than to mitochondrial rhodoquinol-fumarate reductase. The results strongly indicate that R. fermentans complex II and mitochondrial QFR might have evolved independently, although they both utilize RQ for fumarate reduction.

Amino Acid Sequence↗

PubMed2003

Cytokine and chemokine responses in a cerebral malaria-susceptible or -resistant strain of mice to Plasmodium berghei ANKA infection: early chemokine expression in the brain.

A comparative study was carried out on cytokine and chemokine responses in a cerebral malaria (CM)-susceptible or -resistant strain of mice (C57BL/6 or BALB/c respectively) in Plasmodium berghei ANKA infection. C57BL/6 mice died by 10 days after infection when parasitemia was approximately 15-20% with cerebral symptoms, while BALB/c mice survived until week 3 after infection. Although both strains showed T(h)1-skewed responses on day 4 after infection, significantly higher levels of IFN-gamma, tumor necrosis factor (TNF)-alpha and NO were observed during the course of the infection in BALB/c, suggesting that T(h)1 responses are involved in the resistance. Interestingly, in the brain, both strains expressed IFN-inducible protein of 10 kDa (IP-10) and monocyte chemotactic protein (MCP)-1 genes as early as at 24 h post-infection, whereas some differences were observed between both strains thereafter, i.e. enhanced expression of RANTES in C57BL/6, and of IFN-gamma and TNF-alpha in BALB/c respectively. Moreover, the expression of IP-10 and MCP-1 genes in KT-5, an astrocyte cell line, was induced in vitro upon stimulation with a crude antigen of malaria parasites. These results suggest that the direct involvement of brain parenchymal cells takes place in response to plasmodial infection, providing a new aspect to analyze possible mechanisms of CM. This is the first report on the chemokine expression in neuroglial cells in response to malaria infection.

Animals↗

PubMed2003

Risk factors of helminthiases among schoolchildren in southern Thailand.

School-age children are particularly at risk of soil-transmitted helminthiasis (STH), which affects their growth and development. Hence, school-based helminthiasis control has been discussed and conducted as one of cost-effective ways in developing countries. A parasite control program is to be planned and conducted in an evidence based way as one of practical medical fields. However, a prevalence is likely to be influenced by various factors such as local environment and residents' behavior and so on. As few reports mentioning the relation of the prevalence and children's behavior and practice have been published, we conducted a survey to investigate such relation by asking children directly. Two hundred and eighty pupils in grade 3 to grade 5 were enrolled, who were in the two schools in Nakhon Si Thammarat Province, southern Thailand. A cross-sectional study was conducted in February and in November 2001, on the relationship between helminthiasis and children's knowledge and practice by using Kato-Katz method and a questionnaire, respectively. Hookworm (Hw) was the most predominant helminth followed by Trichuris. Boys had more intensive Hw infection than girls (p = 0.022), and wore shoes less frequently than girls (p < 0.001). The pupils who nearly acquired Hw infection after the first stool examination had lower levels of the knowledge of STH comparing to those who did not (p = 0.011). This study suggests that a prior survey can identify unique local factors as a part of diagnostic process, the results of which are useful for teachers to understand some points of health education at schools and can be applied as indicators for monitoring and evaluation.

Child↗

PubMed2002

Involvement of IL-2/IL-2R system activation by parasite antigen in polyclonal expansion of CD4(+)25(+) HTLV-1-infected T-cells in human carriers of both HTLV-1 and S. stercoralis.

The intermediate state of HTLV-1 infection, often found in individuals dually infected with Strongyloides stercoralis (S. stercoralis) and HTLV-1, is assumed to be a preleukemic state of adult T-cell leukemia (ATL). To investigate the effects of S. stercoralis superinfection on the natural history of HTLV-1 infection, we characterized peripheral blood samples of these individuals in Okinawa, Japan, an endemic area for both HTLV-1 and S. stercoralis and we studied effects of the parasite antigen on T-cells. The dually infected individuals showed a significantly higher provirus load and an increase in CD4(+)25(+) T cell population, with a significant, positive correlation. This increase was attributable to polyclonal expansion of HTLV-1-infected cells, as demonstrated by inverse-long PCR analysis of the integration sites. S. stercoralis antigen activated the IL-2 promoter in reporter gene assays, induced production of IL-2 by PBMC in vitro, and supported growth of IL-2 dependent cell lines immortalized by HTLV-1 infection or the transduction of Tax. Taken collectively, these results indicate that S. stercoralis infection induces polyclonal expansion of HTLV-1-infected cells by activating the IL-2/IL-2R system in dually infected carriers, an event which may be a precipitating factor for ATL and inflammatory diseases.

Animals↗

PubMed2002

School-based helminthiases control: I. A baseline study of soil-transmitted helminthiases in Nakhon Si Thammarat Province, Thailand.

A baseline study of soil-transmitted helminthiases was carried out in Nakhon Si Thammarat Province, southern Thailand. The study sites were Wat Krou Chou Primary School and nearby villages in Sichon district, and Wat Thang Phoon Primary School and nearby villages in Chalerm Phrakiat District. Surveys of the schoolchildren's stools were conducted by the Kato-Katz technique. The results showed that 23.7% of schoolchildren in Wat Krou Chou and 24.7% of those in Wat Thang Phoon were infected with soil-transmitted helminths, with a 24.1% overall infection rate. The major infection was hookworm (22.2% and 19.6%) and the minor one was trichuriasis, (2.9% and 8.7% respectively). The intensity of infection was similar in both schools, 85.7% and 90.2% respectively for light intensity hookworm. Schoolchildren with hookworm infection were not anemic. The hemoglobin value of children with hookworm infection was not significantly different from that of uninfected children. Data regarding the health behavior of children's parents in both schools were reported.

Female↗

PubMedDate not supplied

Involvement of interleukin-18 in severe Plasmodium falciparum malaria.

Serum levels of interleukin-18 (IL-18), interferon-gamma (IFN-gamma), and immunoglobulin E (IgE) were determined for 96 patients with Plasmodium falciparum malaria admitted to hospital, Bangkok, Thailand in the period 1998-2000. The patients were divided into 3 groups, i.e. uncomplicated, severe and cerebral malaria according to WHO criteria (2000). Elevation of IL-18 levels was observed in all 3 groups, with a tendency for higher levels in cases with severe malaria throughout the course of the disease. Moreover, there was a significant correlation between IL-18 levels and the extent of parasitaemia among patients with severe malaria. However, IL-18 levels decreased more significantly in patients with cerebral malaria compared with the other groups in the late stage of the disease. Elevated levels of IFN-gamma were also observed in all groups of patients, especially in those with severe or cerebral malaria, and the levels in patients with cerebral malaria remained significantly higher than in those with uncomplicated malaria during days 4-7 post-treatment, suggesting the involvement of IFN-gamma in disease severity. Meanwhile, no significant difference was observed in IgE levels between the severe and uncomplicated groups of patients with helminth infection, although IgE levels were significantly higher in helminth-infected patients than uninfected patients. These results suggest that IL-18 plays a key role in inducing severe malaria through another pathway, such as elevation of IFN-gamma, rather than its IgE inducing activity.

Adolescent↗

PubMedDate not supplied

Beyond deworming.

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Anthelmintics↗