Biomedical subjects

Tohru Suzuki

Publications and source records attributed to Tohru Suzuki.

At least 19 recordsLinked to original sources

PubMed2007

In Vivo antimalarial activity of aqueous extracts from Kenyan medicinal plants and their chloroquine (CQ) potentiation effects against a blood-induced CQ-resistant rodent parasite in mice.

Hot water extracts from eight medicinal plants representing five families, used for malaria treatment in Kenya were screened for their in vivo antimalarial activity in mice against a chloroquine (CQ) resistant Plasmodium berghei NK65, either alone or in combination with CQ. Extracts of three plants, Toddalia asiatica (root bark), Rhamnus prinoides (leaves and root bark) and Vernonia lasiopus (root bark) showed high chemosuppression in the range 51%-75%. Maytenus acuminata, M. heterophylla, M. senegalensis and Rhamnus staddo had moderate activities of 33%-49% parasitaemia suppression in the root bark and/or leaf extracts, while Withania somnifera (root bark) had a non-significant suppression (21%). In combination with CQ, extracts of V. lasiopus (all parts), leaf extracts of M. senegalensis, R. prinoides and T. asiatica as well as root barks of M. heterophylla, R. staddo and T. asiatica had improved parasitaemia suppression in the range 38%-66%, indicating synergistic interactions. Remarkable parasitaemia suppression by the extracts, either alone or in combination with CQ resulted into longer survival of mice relative to the controls, in some cases by more than 2 weeks. Plants, which showed significant antimalarial activity including V. lasiopus, T. asiatica and R. prinoides, should further be evaluated in the search for novel agents against drug-resistant malaria.

Animals↗

PubMed2006

Analysis of the exon-intron structures of fish, amphibian, bird and mammalian hatching enzyme genes, with special reference to the intron loss evolution of hatching enzyme genes in Teleostei.

Using gene cloning and in silico cloning, we analyzed the structures of hatching enzyme gene orthologs of vertebrates. Comparison led to a hypothesis that hatching enzyme genes of Japanese eel conserve an ancestral structure of the genes of fishes, amphibians, birds and mammals. However, the exon-intron structure of the genes was different from species to species in Teleostei: Japanese eel hatching enzyme genes were 9-exon-8-intron genes, and zebrafish genes were 5-exon-4-intron genes. In the present study, we further analyzed the gene structures of fishes belonging to Acanthopterygii. In the species of Teleostei we examined, diversification of hatching enzyme gene into two paralogous genes for HCE (high choriolytic enzyme) and LCE (low choriolytic enzyme) was found only in the acanthopterygian fishes such as medaka Oryzias latipes, Fundulus heteroclitus, Takifugu rubripes and Tetraodon nigroviridis. In addition, the HCE gene had no intron, while the LCE gene consisted of 8 exons and 7 introns. Phylogenetic analysis revealed that HCE and LCE genes were paralogous to each other, and diverged during the evolutionary lineage to Acanthopterygii. Analysis of gene synteny and cluster structure showed that the syntenic genes around the HCE and LCE genes were highly conserved between medaka and Teraodon, but such synteny was not found around the zebrafish hatching enzyme genes. We hypothesize that the zebrafish hatching enzyme genes were translocated from chromosome to chromosome, and lost some of their introns during evolution.

Amino Acid Sequence↗

PubMed2006

Antimalarial activity of methanolic extracts from plants used in Kenyan ethnomedicine and their interactions with chloroquine (CQ) against a CQ-tolerant rodent parasite, in mice.

Methanolic extracts from 15 medicinal plants representing 11 families, used traditionally for malaria treatment in Kenya were screened for their in vivo antimalarial activity in mice against a chloroquine (CQ)-tolerant Plasmodium berghei NK65, either alone or in combination with CQ. The plant parts used ranged from leaves (L), stem bark (SB), root bark (RB), seeds (S) and whole plant (W). When used alone, extracts from seven plants, Clerodendrum myricoides (RB), Ficus sur (L/SB/RB), Maytenus acuminata (L/RB), Rhamnus prinoides (L/RB), Rhamnus staddo (RB), Toddalia asiatica (RB) and Vernonia lasiopus (RB) had statistically significant parasitaemia suppressions of 31.7-59.3%. In combination with CQ, methanolic extracts of Albizia gummifera (SB), Ficus sur (RB), Rhamnus prinoides and Rhamnus staddo (L/RB), Caesalpinia volkensii (L), Maytenus senegalensis (L/RB), Withania somnifera (RB), Ekebergia capensis (L/SB), Toddalia asiatica (L/RB) and Vernonia lasiopus (L/SB/RB) gave statistically significant and improved suppressions which ranged from 45.5 to 85.1%. The fact that these activities were up to five-fold higher than that of extract alone may suggest synergistic interactions. Remarkable parasitaemia suppression by the extracts, either alone or in combination with CQ mostly resulted into longer mouse survival relative to the controls, in some cases by a further 2 weeks. Plants, which showed significant antimalarial activity including Vernonia lasiopus, Toddalia asiatica, Ficus sur, Rhamnus prinoides and Rhamnus staddo warrant further evaluation in the search for novel antimalarial agents against drug-resistant malaria.

Animals↗

PubMed2006

Why does avian influenza A virus hemagglutinin bind to avian receptor stronger than to human receptor? Ab initio fragment molecular orbital studies.

Influenza A viruses attach to alpha-sialosides on the target cell surface by their hemagglutinins, which strictly recognize the difference in sialic acid-galactose linkage. Why does avian virus H3 subtype bind to avian receptor Neu5Ac(alpha2-3)Gal stronger than to human receptor Neu5Ac(alpha2-6)Gal? Why does avian H3 mutated Gln226 to Leu preferentially bind to human receptor? In this paper, we theoretically answer the questions by molecular mechanics and ab initio fragment molecular orbital (FMO) calculations. The binding energy between avian H3 and avian receptor is 8.2kcal/mol larger than that of the avian H3-human receptor complex estimated at the FMO-HF/STO-3G level, which is a reason that avian H3 binds to avian receptor stronger than to human receptor. Avian Leu226 H3 clashes to Gal unit on the avian receptor to quite decrease its binding affinity. In contrast, Gal unit on the human receptor forms intermolecular hydrophobic interaction with avian Leu226 H3 to afford moderate binding affinity.

Animals↗

PubMed2006

Flounder and fugu have a single lefty gene that covers the functions of lefty1 and lefty2 of zebrafish during L-R patterning.

The lefty gene encodes a member of the TGF-beta superfamily that regulates L-R axis formation during embryogenesis via antagonistic activity against Nodal, another TGF-beta superfamily member. Both mouse and zebrafish have two lefty genes, lefty1 and lefty2. Interestingly, the expression domains of mouse and zebrafish lefty are different from one another. At present, the orthology and functional diversity of the mouse and zebrafish lefty genes are not clear. Here, we report that flounder and two fugu species, Takifugu and Tetraodon, have a single lefty gene in their genomes. In addition, we provide evidence that the mouse lefty genes were duplicated on a single chromosome but the zebrafish lefty genes arose from a whole-genome duplication that occurred early in the divergence of ray-finned fishes. These independent origins likely explain the difference in the expression domains of the mouse and zebrafish lefty gene pairs. Furthermore, we found that the duplication corresponding to the zebrafish lefty2 gene was lost from the fugu genome, suggesting that loss of lefty2 in the fugu/flounder lineage occurred after its divergence from the zebrafish lineage. During L-R patterning, the single lefty gene of flounder covers two expression domains, the left side of the dorsal diencephalon and the left LPM, which are regulated separately by lefty1 and lefty2 in zebrafish. We infer that the lefty genes of the ray-finned fishes and mammals underwent independent gene duplication events that resulted in independent regulation of lefty expression.

Amino Acid Sequence↗

PubMed2006

Geographical distribution of Metagonimus yokogawai and M. miyatai in Shizuoka Prefecture, Japan, and their site preferences in the sweetfish, Plecoglossus altivelis, and hamsters.

Sweetfish, Plecoglossus altivelis, obtained from 18 rivers in Shizuoka Prefecture were examined for metacercarial infection of 2 flukes, Metagonimus yokogawai and Metagonimus miyatai. The infection rate and density of metacercariae in the fish were higher in eastern and western regions than in central region of the prefecture. After infection of hamsters with metacercariae derived from the scale, 98.7% of the adult worms obtained from the intestine was found to be M. miyatai. Conversely, from infection with metacercariae from the flesh, 90.0% of the worms was M. yokogawai. Since the worms had no exclusivity in the tissues, we conclude that the flukes have location preference with the former primarily preferring the scale, and the latter the flesh. Fish from two rivers located in adjacent areas in the western region had relatively a higher ratio of M. yokogawai in the scale relative to other rivers, suggesting an intraspecific genetic variation due to geographical isolation. On examination of adult worms in the hamster's intestine, M. yokogawai was mainly located towards the anterior part of the intestine, unlike M. miyatai, suggesting that in mammalian host too, the parasites have site preference.

Animals↗

PubMed2006

A novel hypothyroid dwarfism due to the missense mutation Arg479Cys of the thyroid peroxidase gene in the mouse.

Recently, we found a novel dwarf mutation in an ICR closed colony. This mutation was governed by a single autosomal recessive gene. In novel dwarf mice, plasma levels of the thyroid hormones, T3 and T4, were reduced; however, TSH was elevated. Their thyroid glands showed a diffuse goiter exhibiting colloid deficiency and abnormal follicle epithelium. The dwarfism was improved by adding thyroid hormone in the diet. Gene mapping revealed that the dwarf mutation was closely linked to the thyroid peroxidase (Tpo) gene on chromosome 12. Sequencing of the Tpo gene of the dwarf mice demonstrated a C to T substitution at position 1508 causing an amino acid change from arginine (Arg) to cysteine (Cys) at codon 479 (Arg479Cys). Western blotting revealed that TPO protein of the dwarf mice was detected in a microsomal fraction of thyroid tissue, but peroxidase activity was not detected. These findings suggested that the dwarf mutation caused a primary congenital hypothyroidism by TPO deficiency, resulting in a defect of thyroid hormone synthesis.

Animals↗

PubMed2006

Expression of fugu TIMP-3 and -4 genes in adult tissues and embryos.

The tissue inhibitors of metalloproteinases (TIMPs) are involved in various processes of extra-cellular matrix (ECM) metabolism by inhibiting matrix metalloproteinases (MMPs). However, the fundamental information for these genes is little known in fish. Previously, we report cDNA cloning and gene expressions of two fugu (Takifugu rubripes) TIMP-2s. Here, we cloned cDNA of fugu TIMP-3 and performed an expression analysis of TIMP-3 and -4 mRNA in fugu adult tissues using a quantitative real-time PCR. The expression level of TIMP-3 mRNA was constitutive in all tissues, while TIMP-4 was significantly higher in the brain (P=0.05). Further, we performed a whole mount in situ hybridization in fugu embryos at different stages. In early stages, TIMP-3 mRNA was abundant in the somites and the caudal end of the notochord. At hatching larvae, the TIMP-3 mRNA was abundant in the pectoral fin, dorsal and ventral fin fold along the entire antero-posterior axis. TIMP-3 may be involved in axis elongation and somitogenesis. TIMP-4 mRNA was expressed in the tail bud, at the midbrain-hindbrain boundary and in the diencephalon from 72 to 104 hpf. This indicates TIMP-4 is highly expressed in the brain matrix in vivo.

Amino Acid Sequence↗

PubMed2006

Chromosomal mapping of host resistance loci to Trichinella spiralis nematode infection in rats.

The differences in host response among strains of rats to intestinal nematode parasite Trichinella spiralis infection could provide a powerful benefit for further elucidation of molecular interactions between the host and the parasite. Using several strains of rats, we previously observed that DA strain is a strong responder and F344 strain is a weak responder with respect to expulsion of the adult worm. To identify the host resistance loci, quantitative trait loci (QTLs) analysis in F2 population from crosses between DA and F344 strains was performed. One significant QTL (designated as Tspe) was mapped to the middle region of chromosome 9. In addition, the effect of DA allele at Tspe locus could act recessively and lead to the rejection of more adult worms from the gut. The results from the present study provide more insights on host-parasite interactions, which may be useful in facilitating the development of novel approaches for treatment and control of intestinal parasites in human and domestic livestock.

Animals↗

PubMed2006

Homology modeling of human sialidase enzymes NEU1, NEU3 and NEU4 based on the crystal structure of NEU2: hints for the design of selective NEU3 inhibitors.

Four types of human sialidases have been cloned and characterized at the molecular level. They are classified according to their major intracellular location as intralysomal (NEU1), cytosolic (NEU2), plasma membrane (NEU3) and lysosomal or mitochondrial membrane (NEU4) associated sialidases. These human isoforms are distinct from each other in their enzymatic properties as well as their substrate specificity. Altered expression of sialidases has been correlated with malignant transformation of cells and different sialidases have been known to behave differently during carcinogenesis. Particularly, increased expression of NEU3 has been implicated in the survival of various cancer cells and also in the development of insulin resistance. In the present study, we have modeled three-dimensional structures of NEU1, NEU3 and NEU4 based on the crystal structure of NEU2 using the homology modeling program MODELER. The best model in each enzyme case was chosen on the basis of various standard protein analysis programs. Predicted structures and the experimental protein-ligand complex of NEU2 were compared to identify similarities and differences among the active sites. The molecular electrostatic potential (MEP) was calculated for the predicted models to identify the differences in charge distribution around the active site and its vicinity. The primary objective of the present work is to identify the structural differences between the different isoforms of human sialidases, namely NEU1, NEU2, NEU3 and NEU4, thus providing a better insight into the differences in the active sites of these enzymes. This can in turn guide us in the better understanding and rationale of the differential substrate recognition and activity, thereby aiding in the structure-based design of selective NEU3 inhibitors.

Amino Acid Sequence↗

PubMed2006

A comparative study of protein profiling by proteomic analysis in camptothecin-resistant PC3 and camptothecin-sensitive LNCaP human prostate cancer cells.

INTRODUCTION: Drug resistance is a major obstacle for the therapy of prostate cancer, but its underlying mechanisms are not clarified. To detect some candidate marker proteins which may confer resistance to the anticancer drug camptothecin (CPT; DNA topoisomerase 1 inhibitor), the current study deals with the comparative proteomic profiling of CPT-resistant PC3 and CPT-sensitive LNCaP human prostate cancer cell lines which have been widely employed as a useful model to investigate prostate cancer cells. MATERIALS AND METHODS: The global profiling of the protein expression was investigated in CPT-resistant PC3 and CPT-sensitive LNCaP prostate cancer cells using 2-dimensional polyacrylamide gel electrophoresis/matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. RESULTS: 144 proteins were identified and their expression levels were compared between the two cell lines. Four proteins - annexin A1, glutathione-S-transferase (GST) pi, galectin (Gal) 3 and glucose-regulated protein 78/Bip - that are suggested to contribute to the development of drug resistance were found to be preferentially or highly expressed in PC3 cells, whereas LNCaP cells did not show detectable expression of annexin A1, GST-pi and Gal-3. CONCLUSION: The expression level of these proteins and/or mRNAs could be a useful parameter to evaluate the chemotherapy resistance in clinical specimens of prostate cancer.

Antineoplastic Agents, Phytogenic↗

PubMed2006

Cloning and pattern of expression of the shiro-uo vasa gene during embryogenesis and its roles in PGC development.

The vasa genes are expressed in the germ cell lineage in many organisms, but their expression patterns show large variations. Recent studies suggest that vasa transcripts are involved in germ cell lineage development. In this paper, we isolated the vasa cDNA clone from a teleost, shiro-uo, Leucopsarion petersii and examined its expression pattern during embryogenesis. Then, we examined the functional significance of vasa mRNA during the formation of primordial germ cells (PGCs). The amino acid sequence of shiro-uo VASA is 61.1% identical to that of zebrafish. In whole-mount in situ hybridization, vasa transcripts appeared at the 4- and 8-cell stages as four spots at both ends of two cleavage planes between the lower tier of blastomeres and the yolk cell mass. At the 16-cell stage, eight spots were observed. After the blastula stage, shiro-uo vasa transcripts showed similar localization as in the zebrafish. Ultrastructural analysis of 4-cell stage embryos revealed the presence of a subcellular organelle that resembled 'nuage' in the germ cell lineage observed in the embryos of various organisms. We carried out micromanipulation of 4- or 8-cell stage embryos to remove the vasa mRNA-containing spots and then measured the number of the vasa-expressing PGCs in the genital ridge of the manipulated embryos. The numbers decreased when all of the four spots were removed, indicating that the vasa-containing spots at early cleavage stages have important functions in the development of PGCs.

Amino Acid Motifs↗

PubMed2006

Chloroquine efficacy in Plasmodium berghei NK65-infected ICR mice, with reference to the influence of initial parasite load and starting day of drug administration on the outcome of treatment.

We examined whether the initial number of parasites inoculated and the starting day of medication post-infection influenced the antimalarial efficacy of chloroquine (CQ) against Plasmodium berghei NK65 infection in ICR mice. Male ICR mice were inoculated intraperitoneally with 1 x 10(5), 1x10(6), 1 x 10(7), 1 x 10(8) P. berghei NK65-parasitized erythrocytes (pRBC). In the treated group, all mice received an oral dose of 20 mg/kg of CQ base for 4 days starting on day 0 after infection. From day 3, Giemsa-stained thin blood smears from tail vein blood were used to assess parasitemia. Mice in the untreated control in each group showed a progressive increase in parasitemia leading to death. Treatment of mice, inoculated with 1 x 10(5), 1 x 10(6) and 1 x 10(7) pRBC, with CQ showed a marked effect. All the mice survived during the experiment. During the observation period, malaria parasites could not be detected on microscopic examination. Conversely, mice inoculated with 1 x 10(8) pRBC showed little response to CQ treatment, and all mice showed a progressive increase in parasitemia and ultimately died. In another experiment, mice infected with 1 x 10(3) and 1x 10(5) pRBC were treated with an oral four-day dosage of 20 mg/kg of CQ base from days 2, 3 or 4 post-infection. Treatment of mice, inoculated with 1 x 10(3) pRBC, with CQ from days 2 and 3 showed a marked effect. All mice survived during the experiment. However, treatment from day 4 showed a limited derease in parasitemia and all the mice ultimately died. On the other hand, treatment from day 2 showed a marked effect against 1 x 10(5) P. berghei NK65-infected mice, but treatment from days 3 or 4 was only slightly effective and all the mice died with an increasing parasitemia. The present results indicate that in in vivo antimalarial drug-assay systems, several factors, sush as initial parasite load and starting time of treatment may influence the drug response in the host.

Animals↗

PubMed2005

Phenogenetic drift in evolution: the changing genetic basis of vertebrate teeth.

Vertebrate mineralized tissues are vital to the adaptive evolution of various traits. Among these traits is the tooth, which consists of two characteristic mineralized tissues, a highly mineralized surface layer (enamel in tetrapods and enameloid in fish) and a softer body (dentin), both supported by basal bone. However, enamel and enameloid are significantly different in development, and dentin shows many histological variations; hence their evolution has been intensively studied. Nevertheless, their genetic basis has been revealed only in tetrapods. We previously reported that many genes involved in tetrapod tissue mineralization arose from a common ancestor and constitute the secretory calcium-binding phosphoprotein (SCPP) gene family. Now we show that teleost fish also use many SCPPs for enameloid and dentin mineralization, but none of these directly corresponds to tetrapod SCPPs. This finding suggests that teleost and tetrapod SCPP genes have experienced independent parallel duplication histories. Thus, through phenogenetic drift, the tooth has remained a stable trait in jawed vertebrates, while evolving distinct genetic bases in teleosts and tetrapods. The characteristics of teleost SCPP genes and their expression domains in tooth development suggest the possibility that enameloid arose from dentin and enamel from enameloid more than once in vertebrate evolution. In fugu (puffer fish), expression of SCPP genes is also detected in an unusual beak-like structure that shelters numerous teeth. Their expression pattern suggests that the jaw consists of the dentin beak and supportive bone. These findings illustrate the complexity of the homology concept in understanding evolution, particularly the evolution of mineralized tissues.

Animals↗

PubMed2005

Degradation of polychlorinated dibenzo-p-dioxins in aqueous solution by Fe(II)/H2O2/UV system.

The photodegradation of polychlorinated dibenzo-p-dioxins (PCDDs), which include tetra- to octa-CDDs (TeCDD, PeCDD, HxCDD, HpCDD and OCDD), was carried out in the presence of Fe(II) and H2O2 mixed reagent. The degradation efficiency was strongly influenced by UV irradiation, and the initial concentrations of H2O2 and Fe(II). An initial TeCDD concentration of 10 ng l(-1) was completely degraded within 20 min under the optimum conditions. All PCDDs tested were successfully degraded by Fe(II)/H2O2/UV treatment and complete degradation of TeCDD, PeCDD and HxCDD was achieved within 120 min. PCDD photodegradation rates decreased with the number of chlorine atoms. The degradation process of TeCDD by this system seems to be initiated by an oxidative reaction (OH* radical attack) because less chlorinated DDs as intermediate products were not detected. From the Frontier electron density calculation, the first OH* radical attack positions on TeCDD were found to be four C atoms neighboring two O atoms. The decomposition of TeCDD gave 4,5-dichlorocatechol as an intermediate product. A TeCDD degradation scheme was proposed based on the identified intermediate and the values of Frontier electron density. Based on these results, Fe(II)/H2O2/UV system could be useful technology for the treatment of wastewater containing persistent pollutants such as dioxins and polychlorinated biphenyls.

Gas Chromatography-Mass Spectrometry↗

PubMed2005

Developmental genetic basis for the evolution of pelvic fin loss in the pufferfish Takifugu rubripes.

Paired appendages were a key developmental innovation among vertebrates and they eventually evolved into limbs. Ancient developmental control systems for paired fins and limbs are broadly conserved among gnathostome vertebrates. Some lineages including whales, some salamanders, snakes, and many ray-fin fish, independently lost the pectoral, pelvic, or both appendages over evolutionary time. When different taxa independently evolve similar developmental morphologies, do they use the same molecular genetic mechanisms? To determine the developmental genetic basis for the evolution of pelvis loss in the pufferfish Takifugu rubripes (fugu), we isolated fugu orthologs of genes thought to be essential for limb development in tetrapods, including limb positioning (Hoxc6, Hoxd9), limb bud initiation (Pitx1, Tbx4, Tbx5), and limb bud outgrowth (Shh, Fgf10), and studied their expression patterns during fugu development. Results showed that bud outgrowth and initiation fail to occur in fugu, and that pelvis loss is associated with altered expression of Hoxd9a, which we show to be a marker for pelvic fin position in three-spine stickleback Gasterosteus aculeatus. These results rule out changes in appendage outgrowth and initiation genes as the earliest developmental defect in pufferfish pelvic fin loss and suggest that altered Hoxd9a expression in the lateral mesoderm may account for pelvis loss in fugu. This mechanism appears to be different from the mechanism for pelvic loss in stickleback, showing that different taxa can evolve similar phenotypes by different mechanisms.

Animals↗

PubMed2005

Crystallization and preliminary X-ray crystallographic studies of XynX, a family 10 xylanase from Aeromonas punctata ME-1.

Xylanases catalyze the hydrolysis of beta-1,4-glycosidic linkages within the xylan backbone. XynX is a xylanase from Aeromonas punctata ME-1 and belongs to glycoside hydrolase family 10. While most xylanases show endo-type catalytic activities, XynX shows exo-like catalytic activities, selectively producing xylobiose from birchwood xylan. In this study, XynX was crystallized by the hanging-drop vapour-diffusion method. The crystals belonged to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 79.0, b = 88.6, c = 93.2 A, and diffracted to beyond 1.8 A resolution.

Aeromonas↗

PubMed2005

Slurry sampling techniques for the determination of lead in Bangladeshi fish samples by electrothermal atomic absorption spectrometry with a metal tube atomizer.

Ultrasonic slurry sampling electrothermal atomic absorption spectrometry with a metal tube atomizer has been applied to the determination of lead in Bangladeshi fish samples. The slurry sampling conditions, such as slurry stabilizing agent, slurry concentration, pyrolysis temperature for the slurried fish samples, particle size and ultrasonic agitation time, were optimized for electrothermal atomic absorption spectrometry with the Mo tube atomizer. Thiourea was used as the chemical modifier for the interference of matrix elements. The detection limit was 53 fg (3S/N). The determined amount of lead in Bangladeshi fish samples was consistent with those measured in the dissolved acid-digested samples. The advantages of the proposed methods are easy calibration, simplicity, low cost and rapid analysis.

Animals↗