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H Kanbara

Publications and source records attributed to H Kanbara.

At least 37 records · Page 2Linked to original sources
PubMed1998

Field study on the distribution of Entamoeba histolytica and Entamoeba dispar in the northern Philippines as detected by the polymerase chain reaction.

We used the polymerase chain reaction (PCR) to study the distribution of Entamoeba histolytica and E. dispar in 1,872 individuals in 14 communities in the northern Philippines. Here we report a field study using a DNA extraction protocol from formalin-fixed stool specimens as previously reported. This assay detected 137 stools (7.318%) containing E. dispar and 18 stools (0.961%) containing E. histolytica. The most affected age group for E. histolytica/E. dispar infections were those 5-14 years of age. There was no significant difference in the sex distribution of E. histolytica, while in the case of E. dispar, a higher prevalence was observed in females (9.186%) than in males (5.731%) (P < 0.01). An apparent clustering of stool-positive cases of E. histolytica and E. dispar was also observed in the northern part of the study area. The results of this survey demonstrate that E. dispar is highly prevalent in the communities studied. Moreover, it offers promise for the PCR using DNA extracted from formalin-fixed stools as a sensitive epidemiologic tool for detecting E. histolytica and E. dispar infections.

Adolescent↗
PubMed1998

Tenascin takes part in the progress of pathological severity in cerebral falciparum infection.

We examined plasma level of circulating form of tenascin (TC) in falciparum malaria patients, cerebral malaria and non cerebral malaria, and compared them to uninfected healthy persons. Plasma level of TC examined were significantly higher in malaria patients than in control persons (p< 0.01). The results also show that among malaria patients, TC level was higher in the cerebral malaria patients compare to non cerebral malaria patients (p<0.10). Kinetics of TC level in plasma were related to kinetics of TNF-alpha level. Moreover, patients with higher level of TC showed higher level of parasitized erythrocytes binding ratio. Immunohistochemical study showed that TC was found in the cerebral microvessels of postmortem cerebral tissues from nine cerebral malaria cases. These results provide evidence that plasma level of TC correlates with the severity in cerebral malaria patients.

Brain↗
PubMed1998

Application of the polymerase chain reaction (PCR) in the epidemiology of Entamoeba histolytica and Entamoeba dispar infections.

In this paper, we briefly summarize the latest information on the polymerase chain reaction (PCR) as an epidemiologic tool for Entamoeba histolytica and Entamoeba dispar infections. This method which employs DNA template directly extracted from formalin fixed stool specimens offers a good promise for an accurate and reliable epidemiology of the two species. The assay is, sensitive enough to detect as few as five cysts in the stool sample, rapid and selectively differentiates E. histolytica from E. dispar DNA from stool specimens without the need for prior cultivation.

Animals↗
PubMed1997

Genetic structure of Trypanosoma cruzi in Central America and its comparison with South American strains.

Genetic characterization by isozyme analysis was performed on 68 isolates of Trypanosoma cruzi; 57 from Guatemala in Central America and 11 from South American countries. Ten zymodemes (isozyme patterns) were identified by examining zymograms of 12 enzymes (13 loci). These zymodemes were classified to 3 major distinctive groups: (1) major Guatemalan, (2) minor Guatemalan and (3) unique South American, by the genetic distances and the phylogenetic dendrogram drawn by UPGMA. Based on the results obtained, genetic structures and phylogenetic relations of T. cruzi in Guatemala and South America are discussed. Clonal reproduction seemed to be consistent with the observation of deviation from Hardy-Weinberg equilibrium in several loci.

Animals↗
PubMed1997

Short communication: cultivation of bloodstream forms of Trypanosoma brucei and T. evansi in a serum-free medium.

Bloodstream forms of Trypanosoma brucei and T. evansi have been cultivated in an axenic culture system by using Iscove's modified DMEM-based HMI-9 medium supplemental with bathocuproinedisulphonic acid, L-cysteine, hypoxanthine, 2-mercaptoethanol, pyruvate, thymidine and 10% fetal bovine or adult horse serum. We developed a serum-free medium (HMI-244) in which serum in HMI-9 was replaced by fatty acid-free bovine serum albumin, bovine alpha 2-macroglobulin, bovine beta-lipoprotein, d-biotin, retinol, beta-alanine, L-anserine nitrate salt, L-ornithine hydrochloride, O-phosphorylethanolamine, sarcosine, taurine, adenosine-5'-triphosphate, 2'-deoxycytidine-5'-monophosphate, 2'-deoxyguanosine-5'-monophosphate, and 5-methyltetrahydrofolic acid. Maximum cell densities and population doubling times were 2.6 x 10(6) cells/ml; 10.6 hours and 2.2 x 10(6) cells/ml; 10.9 hours for T. brucei and T. evansi, respectively. Bloodstream forms continued to proliferate in the serum-free cultures for more than 90 days and the trypomastigotes retained their morphological characteristics and infectivity to mice. If validated, this serum-free medium may help reduce future interlaboratory variability in biochemical, immunological, molecular biological and drug sensitivity studies on these parasites.

Animals↗
PubMed1997

Two antigens on zygotes and ookinetes of Plasmodium yoelii and Plasmodium berghei that are distinct targets of transmission-blocking immunity.

We have developed transmission-blocking monoclonal antibodies (MAbs) against Plasmodium yoelii 21-kDa (Pys21) and 28-kDa (Pys25) ookinete surface proteins. These MAbs block infectivity of P. yoelii to Anopheles stephensi. One MAb, 14, cross-reacted by Western blotting with a 28-kDa surface protein (Pbs25) of P. berghei ookinetes and blocked oocyst development, as assayed by direct mosquito feeds on passively immunized P. berghei-infected mice. In total, we have identified two ookinete surface proteins in P. yoelii, one of which is also present in P. berghei. The transmission-blocking activity of the anti-Pys25 MAb 4 was complete and more potent than that of the anti-Pys21 MAb 2. Moreover, Fab fragments of MAb 4 had transmission-blocking activity in mice. In comparison, Fab fragments of MAb 2 did not have detectable transmission-blocking effect, although F(ab')2 did. Furthermore, MAb 2 and MAb 4 appeared to block the in vitro formation and development of zygotes as well.

Animals↗
PubMed1997

Rapid uptake and phosphorylation of D-mannose, and limited D-mannose 6-phosphate isomerization in the glycolytic pathway of bloodstream forms of Trypanosoma brucei gambiense.

Bloodstream forms of the parasitic protozoa Trypanosoma brucei gambiense derive all of needed energy through an unusual glycolysis. In an earlier study, we showed that D-mannose specifically inhibited the growth of bloodstream forms of T. b. gambiense. We investigated D-mannose transport into the T. b. gambiense bloodstream forms and its metabolism in the initial phase of the glycolytic pathway. D-Mannose was transported rapidly into the bloodstream forms of T. b. gambiense (K(m) = 378 microM), and D-glucose competitively inhibited D-mannose uptake. D-Mannose and D-glucose are transported into bloodstream trypanosomes by the same carrier. Hexokinase from the bloodstream trypanosomes could convert D-mannose to D-mannose 6-phosphate (K(m) = 155.8 microM; Vmax = 0.93 mumol/min/mg protein); with kinetic properties very similar to D-glucose phosphorylation (K(m) = 199.4 microM; Vmax = 1.15 mumol/min/mg protein). D-Mannose 6-phosphate could be further metabolized in the glycolytic pathway. However, the metabolic rate was extremely slow, and D-mannose 6-phosphate accumulated in the glycosomes. D-Mannose may cause growth inhibition of bloodstream trypanosomes through an extremely high concentration of D-mannose 6-phosphate in the glycosomes.

Animals↗
PubMed1997

[Typical normal cases and normal cases with abnormal image pattern in every myocardial SPECT radiopharmaceutical].

Working group of cardiac nuclear medicine was made as a Japanese part of society of international cardiac nuclear medicine under the cooperation between Japanese society of nuclear medicine and Japanese society of cardiology. We investigated typical normal cases and normal cases with abnormal image pattern in every myocardial SPECT radiopharmaceutical as one of the research activity of working group. From 11 faculties, 16 T1 cases, 14 BMIPP cases, 8 MIBG cases, 8 MIBI cases and 14 tetrofosmin cases were submitted as typical normal cases, and 12 T1 cases, 5 BMIPP cases, 12 MIBG cases, 10 MIBI cases and 5 tetrofosmin cases were submitted as normal cases with abnormal image pattern. We summarized the condition of SPECT data acquisition of each faculties. And we added the discussion from literature about how to discriminate normal cases with abnormal image pattern from abnormal cases. In MIBG, patterns of typical normal cases and normal cases with abnormal image pattern were slightly different from other 4 pharmaceuticals. In other 4 pharmaceuticals, diaphragmatic attenuation, breast attenuation, apical thinning and others were presented as normal cases with abnormal image pattern.

3-Iodobenzylguanidine↗
PubMed1997

Granulocyte-macrophage colony-stimulating factor production by T lymphocytes in Plasmodium berghei-infected mice.

The production of granulocyte-macrophage colony-stimulating factor (GM-CSF) by lymphocytes was examined in murine malaria. When spleen cells or lymph node cells from P. berghei-infected mice were cultured in vitro with malaria antigen, the GM-CSF production correlated with the incubation time up to 72 hours. When lymphocytes obtained at various days after infection were cultured with the antigen, GM-CSF became detectable as early as 2 days after infection, reached a peak at day 9 and then rapidly decreased. Production of GM-CSF was antigen-specific, and related to the dose of antigen. Treatment of lymphocytes with anti-Thy-1.2 antibody and complement resulted in almost complete loss of GM-CSF-producing activity, while treatment with either anti-CD4 or anti-CD8 antibody and complement resulted in partial loss of GM-CSF-producing activity, indicating that both CD4+ and CD8+ T cells are involved in GM-CSF production in malaria. GM-CSF exhibits glycoprotein nature, and has an apparent molecular weight of 36,000. The molecular properties of this T-cell derived GM-CSF were compared with those of known lymphokine GM-CSF.

Animals↗
PubMed1996

Differentiation of Entamoeba histolytica and E. dispar DNA from cysts present in stool specimens by polymerase chain reaction: its field application in the Philippines.

It has been established that two distinct species exist within what was originally known as Entamoeba histolytica. These are E. dispar and E. histolytica, for the nonpathogenic and pathogenic forms, respectively. Differentiation of these two organisms is of great clinical importance since they are morphologically indistinguishable and both forms can infect the human intestinal cavity to different degrees. A simple and rapid DNA-extraction method that can be used directly on formalin-fixed stool specimens has been developed. The extracted DNA was used for the identification of the species existing in the stools by polymerase chain reaction (PCR). A total of 72 randomly collected stool samples from the Philippines were analyzed. In all, 19 samples reacted with E. dispar primers, resulting in the expected 101-bp PCR products; however, none reacted with E. histolytica primers. Furthermore, sensitivity assay suggests that genomic DNA from as few as five cysts can be used as a template for PCR. These observations imply that the use of genomic DNA directly extracted from formalin-fixed stool specimens for PCR amplification is a useful tool for obtaining a sensitive and accurate diagnosis that can be applied even in epidemiology studies.

Animals↗
PubMed1996

Stable expression and secretion of the B-cell epitope of rodent malaria from Mycobacterium bovis BCG and induction of long-lasting humoral response in mouse.

The live bacterial vaccine Mycobacterium bovis BCG (BCG) is a vehicle worth noticing for various protective antigens. The gene encoding the B-cell epitope of the oligopeptide repeating in the circumsporozoite protein (C.S. protein) of the rodent malaria parasite, Plasmodium yoelii, was inserted into the plasmid vector under the control of an expression cassette carrying the promoter and signal sequence of the a antigen derived from Mycobacterium kansasii (k-a). The B-cell epitope was successfully expressed and secreted from BCG as a fusion protein with k-a. This recombinant BCG was administered subcutaneously into BALB/c mice and the antibody production was measured by the enzyme-linked immunosorbent assay (ELISA). Long lasting humoral response was found in one of seven mice.

Animals↗
PubMed1996

Loss of tumor necrosis factor production by human monocytes in falciparum malaria after their maturation in vitro.

In Plasmodium-infected mammals, phagocytosis and production of tumor necrosis factor (TNF) by monocytes and macrophages are prominent features. The present work aimed at clarifying the relationship between the maturation of human monocytes to macrophages and their TNF productivity and phagocytic ability in the presence of Plasmodium falciparum-infected erythrocytes. Fresh monocytes produced a significantly higher quantity of TNF in the presence of schizont-infected erythrocytes than macrophages obtained by in vitro monocyte maturation on autologous serum, whereas phagocytic activity of macrophages was much higher than that of fresh monocytes. This indicated that the TNF-inducing factors from P. falciparum-infected erythrocytes could stimulate fresh monocytes, but not macrophages, to release TNF, regardless of their development of phagocytosis. Activation of macrophages by interferon-gamma could not recover their TNF productivity in the presence of P. falciparum-infected erythrocytes, but it enhanced their TNF productivity in the presence of lipopolysaccharide(s). The TNF-inducing factors were contained mainly in erythrocytes infected with mature schizonts but not in erythrocytes infected with the younger stages of the parasites. Fractionation of infected erythrocytes revealed that both soluble and insoluble components almost equally contained those factors.

Animals↗
PubMed1995

Plasmodium falciparum: recrudescence of parasites in culture.

The basis of recrudescence, the reappearance of malaria parasites after chemotherapy or after failure of immune suppressions of the parasites, was studied in cultures of Plasmodium falciparum. When the cultured parasites were exposed eight times over a 4-day period to 5% D-sorbitol, which destroyed infected RBCs containing trophozoites or schizonts, they showed recrudescence several days after cessation of treatment. Pyrimethamine-sensitive parasites were cleared by 10(-6) M pyrimethamine; pyrimethamine-resistant parasites also were cleared by 10(-4) M pyrimethamine. Both groups of parasites underwent recrudescence in the same manner as those exposed to 5% D-sorbitol. These recrudescent parasites were found to be as susceptible to these treatments as were the parasites before treatment. Therefore, our results strongly suggest that a subpopulation of the parasites escapes the effect of drugs by a mechanism other than drug resistance.

Animals↗
PubMed1995

Murine complement reduces infectivity of Plasmodium yoelii to mosquitoes.

The alternative pathway of complement in the mouse serum significantly reduced, but did not eliminate, the infectivity of Plasmodium yoelii to Anopheles stephensi. The reduction of the infectivity is mainly due to the inability of the zygote to transform into the ookinete in the mosquito midgut.

Animals↗
PubMed1994

Allelic variation in the circumsporozoite protein of Plasmodium falciparum from Thai field isolates.

Allelic variation in the Plasmodium falciparum circumsporozoite (CS) protein gene has been examined by sequencing the entire gene in 15 isolates from an endemic area of Thailand. The isolates contain a total of six new allelic forms of the tetrapeptide repeats and eight variants of the T cell epitope (TCE) region of the CS gene. All nucleotide substitutions in the TCE are nonsynonymous. There is no apparent association between the sequence patterns in the repeats and in the TCE. Comparison of the TCE with published sequences has shown that most variants of our isolates are not identical to those found in different geographic areas, suggesting geographic variation in genetic diversity of the CS protein. In a phylogenetic tree, the new Thai alleles did not cluster together, suggesting a considerable heterogeneity within some geographic areas. Furthermore, analyses of tetrapeptide repeats from a number of isolates and strains showed evidence of three genetic mechanisms for the generation of variation in the repeats of the CS gene: point mutation, duplication of one or more repeat units, and intragenic recombination.

Alleles↗
PubMed1993

Sequence conservation in the C-terminal part of the precursor to the major merozoite surface proteins (MSP1) of Plasmodium falciparum from field isolates.

The C-terminal part of the precursor to the major merozoite surface proteins (MSP1) of Plasmodium falciparum contains potential protective epitopes and two cleavage sites for processing which take place prior to erythrocyte invasion by the merozoite. Since sequences available to date are limited and derived from cultured parasites, we have examined the extent of variations of this important part of the MSP1 gene from natural populations. Our sequence analyses of 1.6-1.7 kb from blocks 13-17 of the gene obtained from 19 Thai wild isolates have identified a deletion of a codon and 18 nucleotide substitutions, all of which are dimorphic substitutions and all but one create amino acid exchanges. However, residues at two cleavage sites for the C-terminus 42 kDa polypeptide and the 19-kDa polypeptide, a subfragment of the former, are conserved. Furthermore, all 12 cysteine residues at the C-terminal 19-kDa polypeptide are perfectly conserved, allowing the formation of 2 epidermal growth factor-like structures. These results indicate that in contrast to extensive variations at the N-terminal part of MSP1, limited variations occur at the C-terminal part.

Amino Acid Sequence↗