Biomedical subjects
A Ito
Publications and source records attributed to A Ito.
Sonic hedgehog signal peptide mutation in a patient with holoprosencephaly.
We investigated the molecular basis of holoprosencephaly in a sporadic patient and identified a novel missense mutation in the signal sequence of the sonic hedgehog (Shh) gene. Magnetic resonance imaging of the head showed a lobar type of holoprosencephaly and partial agenesis of the anterior corpus callosum. He was treated for craniosynostosis at 7 months of age. All three exons of the Shh gene were amplified by polymerase chain reaction from genomic DNA of the patient and controls. Sequencing analysis of the polymerase chain reaction fragments, screened by single-strand conformation polymorphism analysis, revealed a heterozygous mutation of a T-to-C substitution at nucleotide position 50. This mutation predicted an amino acid replacement of leucine to proline at codon 17 located in the signal peptide of SHH protein. It probably disturbs the translocation of the protein into the endoplasmic reticulum and may lead to holoprosencephaly because of haploinsufficiency of Shh.
mi-transcription factor as a regulator of mast cell differentiation.
Masts cells are progeny of the hematopoietic stem cell. For the differentiation of mast cells, a transcription factor encoded by the mouse mi locus (MITF) plays an important role. The expression of many genes encoding proteins that are essential for the function of mast cells is regulated by MITF. Because various mutant mice are available at the mi locus and because cultured mast cells are easily obtained from the spleen of these mutant mice, this system may be a good model for studying the regulation of hematopoietic cell differentiation by a transcription factor.
[Susceptibilities of bacteria isolated from patients with lower respiratory infectious diseases to antibiotics (1998)].
The bacteria isolated from the patients with lower respiratory tract infections were collected by institutions located throughout Japan, since 1981. Ikemoto et al. have been investigating susceptibilities of these isolates to various antibacterial agents and antibiotics, and analyzed some characteristics of the patients and isolates from them each year. Results obtained from these investigations are discussed. In these 18 institutions around the entire Japan, 532 strains of presumably etiological bacteria were isolated mainly from the sputa of 438 patients with lower respiratory tract infections during the period from October in 1998 to September in 1999. MICs of various antibacterial agents and antibiotics were determined against 85 strains of Staphylococcus aureus, 100 strains of Streptococcus pneumoniae, 96 strains of Haemophilus influenzae, 75 strains of Pseudomonas aeruginosa (non-mucoid strains), 6 strains of Pseudomonas aeruginosa (mucoid strains), 38 strains of Moraxella subgenus Branhamella catarrhalis, 26 strains of Klebsiella pneumoniae etc., and the susceptibilities of 517 strains were assessed except for those strains that died during transportation. S. aureus strains for which MICs of oxacillin (MPIPC) were higher than 4 micrograms/ml (methicillin-resistant S. aureus: MRSA) accounted for 60.0%. Vancomycin (VCM) and arbekacin (ABK) showed the most potent activities against MRSA. But one of MRSA showed resistance to ABK with the MIC of 64 micrograms/ml. The sensitive strains of MRSA to VCM have decreased. The frequency of penicillin (PC)-intermediate S. pneumoniae (PISP) + PC-resistant S. pneumoniae (PRSP) have increased in 46.0% for 1998 comparatively from 30.9% of 1997's. But PRSP decreased, and PISP increased into 39.0% of 1998 years from 19.8% of 1997's. Panipenem (PAPM), imipenem (IPM) and faropenem (FRPM) showed the most potent activities against S. pneumoniae with MIC80s of 0.125 microgram/ml or below. Against H. influenzae and M. (B.) catarrhalis, almost all the drugs showed good activities. The sensitive strains of them against ceftazidime (CAZ) decreased in 1997, but those have increased in 1998. Inversely, the susceptibility of them against cefotiam (CTM) had been higher in 1997, but those have been lower in 1998. Tobramycin (TOB) showed the most potent activity against P. aeruginosa (both mucoid and nonmucoid strains). All drugs except ampicillin (ABPC) were active against K. pneumoniae. A quite few of K. pneumoniae showed low susceptibilities. Also, we investigated year to year changes in the characteristics of patients, their respiratory infectious diseases, and the etiology. The examination of age distribution indicated that the proportion of patients with ages over 70 years was 48.6% of all the patients showing a slight increase in every year. About the proportion of diagnosed diseases as follows: Bacterial pneumonia was the most frequent with 40.2%. The ratio of it has increased slightly, and the increased rate was 10% in patients with ages over 70 years compared with the results in 1997. Chronic bronchitis have decreased slightly with 27.6% in 1998. Number of strains isolated from patients before administration of antibiotics were more than those after administration of them in chronic bronchitis, but these were almost same number in bacterial pneumonia. Administration of antibiotics has changed the results of the frequency of isolation of bacterial species. Bacterial isolations before administration of antibiotics were as follows: S. pneumoniae 26.7%, H. influenzae 23.8%, S. aureus 13.3% and M. (B.) catarrhalis 10.8%. The frequencies of S. aureus decreased after antibiotics administration over 15 days, but the frequencies of P. aeruginosa (both mucoid and non-mucoid) was not affected. The frequencies of P. aeruginosa was 45.5% after administration over 15 days. The frequencies of S. pneumoniae decreased upon administration of antibiotics, these were only 4.5% over 15 days. The frequencies of H. (
Substituted 3-phenylsulfonylquinazoline-2,4-dione derivatives as novel nonpeptide inhibitors of human heart chymase.
A series of 3-phenylsulfonylquinazoline-2,4-dione derivatives have been synthesized and evaluated for their ability to inhibit human heart chymase. The structure-activity relationship studies on these compounds gave the following results. The phenyl moiety of quinazoline participates in a hydrophobic interaction where an optimum size is required. In this moiety, 7-chloroquinazoline is the best moiety for inhibiting chymase, chymotrypsin and cathepsin G. A 3-phenylsulfonyl moiety substituted with hydrophobic electron-withdrawing groups at the 4-position potentiated the activity. Anthranil moiety also enhanced the activity. Pyridylmethyl and N-pyridylacetamide at the 1-position gave an IC50 in the order of 10(-8)M. Molecular modeling studies on the interaction of 7-chloro-3-(4-chlorophenylsulfonyl) quinazoline-2,4(1H, 3H)-dione (4) with the active site of human heart chymase suggested that the phenyl moiety of quinazoline interacts with the hydrophobic P1 pocket, the 3-phenylsulfonyl moiety resides in the S1'-S2' subsites, the moiety at the 1-position locates in the S2-S3 subsites and the 4-carbonyl and 3-sulfonyl group interact with the oxyanion hole and the His57 side-chain of chymase, respectively.
[Advanced gastric cancer: the findings of delayed phase dynamic CT and radiologic-histopathologic correlation].
PURPOSE: The aim of this study was to describe delayed phase dynamic CT findings of advanced (T2-T4) gastric cancer and to correlate with histopathologic findings. METHOD/MATERIALS: Quadruple phase dynamic CT including delayed imaging taken five minutes after the start of injection of contrast material was performed in 43 patients with 45 advanced gastric cancer and 20 control subjects with no gastric lesions. On delayed phase CT scans, the attenuation of the gastric wall was equal to or lower than that of the liver parenchyma in the control subjects, therefore, the presence of higher attenuation in the gastric wall was considered to be abnormal and defined as delayed enhancement. Histopathologic findings in the tumors showing delayed enhancement were compared with those in the tumors without this feature. RESULTS: Delayed enhancement was seen in 26 (57%) of the 45 tumors. Eleven of 25 differentiated-type tumors and 15 of 20 undifferentiated-type tumors showed delayed enhancement (P < .05). Delayed enhancement was seen in one of five medullary type tumors, in 11 of 25 intermediate-type tumors, and in 14 of 15 scirrhous-type tumors (P < .005). CONCLUSIONS: Delayed enhancement was frequently seen in the tumors with abundant fibrous tissue stroma. Delayed phase dynamic CT may be useful for the characterization of advanced gastric cancer.
[Sodium and potassium metabolism].
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[The exercise prescription for hyperuricemia].
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Evaluation of Viroseq-HIV version 2 for HIV drug resistance.
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Opacification of isolated rat lenses intoxicated with diethylmaleate: relation to lens membrane dysfunction.
We examined whether opacification of rat lenses treated with diethylmaleate (DEM), a depletor of reduced glutathione (GSH), is associated with membrane dysfunction. When isolated rat lenses were incubated with 2 mM DEM for 1, 6, and 24 h, a cortical opacity appeared at 6 h and was more pronounced at 24 h. This opacification was accompanied by decreases in GSH and vitamin E (Vit. E) content and Na+,K+-ATPase activity, and an increase in water content, but not by a change in the content of thiobarbituric acid reactive substances (TBARS), an index of lipid peroxidation. Vit. E co-treatment caused a partial prevention of opacification, a complete recovery of decreased Vit. E content, attenuation of decreased Na+,K+-ATPase activity, and a decrease in TBARS content in rat lenses treated with 2 mM DEM for 24 h. Neither opacity formation nor changes in Vit. E, TBARS, and water content and Na+,K+-ATPase activity occurred in rat lenses treated for 48 h with 2 mM l-buthionine-(S,R)-sulfoximine, an inhibitor of glutathione synthesis, although a marked GSH depletion was observed. These results suggest that opacification of isolated rat lenses treated with DEM could be associated with impairment of Na+,K+-ATPase rather than GSH depletion.
Neurocysticercosis and echinococcosis in Asia: recent advances in the establishment of highly reliable differential serodiagnosis for international collaboration.
Neurocysticercosis (NCC) and echinococcosis, caused by the larval stage of taeniid cestodes, are recognized as major parasitic zoonoses threatening human life worldwide. Cystic echinococcosis (CE), caused by Echinococcus granulosus, has well been known to be more widely distributing in Europe and Asia (Eurasia) than alveolar echinococcosis (AE) caused by E. multilocularis. However, it has recently been found that AE is more widely distributing or spreading in Eurasia. Furthermore, NCC caused by Taenia solium is also spreading in Eurasia. Due to the lack of reliable methodology for diagnosing these zoonotic cestodiases worldwide, prevalence rates of these diseases are extremely underestimated. Our group has been working for the establishment of differential serodiagnosis and molecular diagnosis of AE. CE and NCC as international collaboration projects sponsored by the Ministry of Education, Japan from 1994 until 2000 at least. In this paper, we introduce (1) the most recent original work on the establishment of differential serodiagnoses of NCC, AE and CE, (2) international collaboration work on epidemiology of these diseases in several countries, and discuss (3) what we can and should do for the control of such global parasitic diseases. It is stressed that international collaboration or cooperation work on the control of parasitic diseases is only successful based on the original scientific contribution of high standard.
Bystander-killing effect and cyclic induction of TNF-alpha gene under heat-inducible promoter gadd 153.
The bystander-killing effect and cyclic induction of tumor necrosis factor (TNF)-alpha gene expression under the heat-inducible promoter gadd 153 (growth arrest and DNA damage) were investigated. The plasmid harboring the TNF-alpha gene under the control of the gadd 153 promoter (pGadTNF) was introduced into cells of the human glioma cell line U251-SP. When the transfected cells were exposed to heat treatment, TNF-alpha gene expression was induced. The heated pGadTNF-transfected cells were co-cultured the nonheated pGadTNF-transfected cells as bystander cells. As a result, TNF-alpha gene expression in the bystander cells was observed. The level of TNF-alpha gene expression was further enhanced in the co-cultured cells. Due to this cyclic induction, a strong cytotoxic effect on the bystander cells was observed. Based on this bystander-killing effect, it was concluded that the transfection of the TNF-alpha gene under the control of the gadd 153 promoter into tumor cells combined with hyperthermia would be a potent tool for cancer therapy.
Furin-independent pathway of membrane type 1-matrix metalloproteinase activation in rabbit dermal fibroblasts.
We investigated the gene expression and intracellular activity of processing protease furin and its involvement in the process of membrane type 1-matrix metalloproteinase (MT1-MMP) activation in rabbit dermal fibroblasts. When the rabbit fibroblasts were treated with concanavalin A (ConA), pro-MMP-2 was converted to an active 62-kDa MMP-2 through the appearance of a 64-kDa intermediate MMP-2. The ConA-induced pro-MMP-2 activation resulted from increasing the gene expression and production of MT1-MMP in the rabbit fibroblasts. Reverse transcriptase-polymerase chain reaction demonstrated that in rabbit dermal fibroblasts furin mRNA was detected and, unlike MT1-MMP, was not increased by ConA. These findings are further supported by the fact that the intracellular furin activity also was constitutively detected and was unchanged by the ConA treatment. Very similar phenomena were also observed in human uterine cervical fibroblasts, which are known to produce MT1-MMP by ConA stimulation. These results suggest that the expression of the furin gene and the intracellular activity are not regulated by ConA. On the other hand, neither a synthetic furin inhibitor, decanoyl-RVKR-CH(2)Cl (25-100 microM) nor a furin antisense oligonucleotide (40 microM) inhibited the MT1-MMP-mediated pro-MMP-2 activation in ConA-treated rabbit dermal fibroblasts, whereas these compounds interfered with pro-MMP-2 activation in ConA-treated human uterine cervical fibroblasts. Nonetheless, the furin antisense oligonucleotide completely suppressed furin gene expression in both rabbit and human fibroblasts. These results suggest that furin does not participate in the process of MT1-MMP activation induced by ConA in rabbit dermal fibroblasts.
Possible involvement of cytochrome c release and sequential activation of caspases in ceramide-induced apoptosis in SK-N-MC cells.
Ceramide is characterized as a second messenger of apoptosis induced by various agents such as tumor necrosis factor (TNF-alpha), Fas ligand, hydrogen peroxide, heat shock and ionizing radiation. In this study, we investigated the mechanism of ceramide-induced apoptosis using a human neuroblastoma cell line, SK-N-MC. N-Acetyl-sphingosine (C2-ceramide), a cell-permeable ceramide analogue, was able to induce apoptosis in SK-N-MC cells as estimated by DNA fragmentation and chromatin condensation. C2-ceramide-induced DNA fragmentation was blocked by caspase inhibitor (Z-Asp-CH(2)-DCB). An increase in caspase-3 (CPP32)-like protease activity was evident during C2-ceramide-induced apoptosis, suggesting that caspases are involved in this apoptosis. Moreover, enzymatic cleavage of VDVAD-AFC and LEHD-AFC (specific substrates for caspase-2 and -9, respectively) was increased by treatment with C2-ceramide. To elucidate which types of caspase are activated in C2-ceramide-treated cells, we performed Western blot analysis using antibodies against each isoform. Both proforms of caspase-2 and -3 were decreased in response to C2-ceramide in a time-dependent manner. Mitochondrial cytochrome c is also time-dependently released into the cytosol in response to treatment with C2-ceramide. Addition of cytochrome c into the S-100 fractions prepared from SK-N-MC cells could activate caspase-2 in cell-free systems. These results suggest the possibility that cytochrome c released to the cytosol can activate caspases (caspase-9, -3, and -2) during C2-ceramide-induced apoptosis of SK-N-MC cells.
A new member of the GTPase superfamily that is upregulated in highly metastatic cells.
Two sublines of B16 melanoma cells, F10 and BL6, are metastatic after intravenous injection, but only BL6 cells are metastatic after subcutaneous injection. We found a new member of the GTPase superfamily, namely TIB929, which displayed an induction of expression in BL6 cells. It conserved three consensus sequences for GTP-binding site motifs and showed a significant homology to the yeast Gtr2 gene throughout the coding sequence. TIB929 was expressed ubiquitously in human tumor cells, with a marked expression in highly metastatic cells. TIB929 was mapped on mouse chromosome 4D, syntenic to human chromosome 1p. The results suggested an involvement of TIB929 in malignant progression.
Mitochondrial processing peptidase: multiple-site recognition of precursor proteins.
During or shortly after import of the precursor proteins into mitochondria, the amino-terminal extension peptides are first proteolytically removed by mitochondrial processing peptidase (MPP). The peptidase is a metalloendopeptidase, classified as a member of pitrilysin family, and forms a heterodimer consisting of structurally related alpha- and beta-subunits which are homologous to core proteins, core 2 and core 1, respectively, of mitochondrial ubiquinol-cytochrome c oxidoreductase complex. The enzyme specifically recognizes a large variety of mitochondrial precursor proteins and is cleaved at a single and specific site. In this review, I will focus on recognition mechanisms of precursor proteins by MPP. Structural characteristics of the precursor responsible for the recognition by MPP, role of each subunit, and amino acid residues of MPP involved in the recognition are discussed.
Expression of full-length NBS1 protein restores normal radiation responses in cells from Nijmegen breakage syndrome patients.
Cells from Nijmegen breakage syndrome (NBS) display multiple phenotypes, such as chromosomal instability, hypersensitivity to cell killing from ionizing radiation, and possibly abnormal cell cycle checkpoints. NBS1, a gene mutated in NBS patients, appears to encode a possible repair protein, which could form the foci of a sensor-like molecular complex capable of detecting DNA double strand breaks, however, it has no kinase domain for signaling DNA damage. Here, we report that the stable expression of NBS1 cDNA in NBS cells after transfection results in the complete restoration of foci formation in the nucleus, and in normal cell survival after irradiation. The prolonged G2 block observed after irradiation was also abolished by expression of NBS1, providing additional confirmation that the G2 checkpoint is abrogated in NBS cells. These results suggest that a defective NBS1 protein could be the sole cause of the NBS phenotype, and that NBS1 likely interacts with another protein(s) to produce the entire range of NBS phenotypic expression.
Triplet state of Würster's blue-based di(cation radical).
[reaction: see text] N,N-bis[4-(dimethylamino)phenyl]-N,N'-dimethyl-1,3-benzenediamine was prepared in order to investigate the corresponding Würster blue-based di(cation radical). The generated diradical was found to be a ground-state triplet, and moreover, the observed ESR spectrum had no definite fine structure, suggesting a mixture of some conformers.