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Biomedical subjects

T Yamada

Publications and source records attributed to T Yamada.

At least 361 records · Page 20Linked to original sources
PubMed2000

Differential expression of the LAMB3 and LAMC2 genes between small cell and non-small cell lung carcinomas.

To identify genes differentially expressed between small cell lung carcinoma (SCLC) cells and non-SCLC cells, mRNA differential display was applied to 3 SCLC cell lines and 6 non-SCLC cell lines. The LAMB3 gene was identified as being expressed only in non-SCLC cells and not in SCLC cells. The LAMB3 gene encodes the laminin beta3 chain, which is a unique component of laminin-5. Laminin-5 is a heterotrimer protein consisting of the alpha3, beta3, and gamma2 chains, and another unique component of laminin-5 is the gamma2 chain encoded by the LAMC2 gene. RT-PCR analysis of the LAMB3 and LAMC2 genes in 45 lung cancer cell lines revealed that both the LAMB3 and LAMC2 genes were co-expressed in 21 of 32 non-SCLC cell lines (66%) but only in one of 13 SCLC cell lines (8%). Coexpression of the LAMB3 and LAMC2 genes was also observed in all 4 cases of primary non-SCLC cells examined but not in the corresponding non-cancerous lung cells. Since alpha6beta4 integrin, the specific laminin-5 binding receptor, is known to be expressed only in non-SCLC cells and not in SCLC cells, it was indicated that laminin-5 is a critical microenvironmental factor for the growth of non-SCLC cells but not of SCLC cells. The differences in the expression of integrins and laminins would be critical factors to distinguish SCLC and non-SCLC cells, and such differences might be associated with the unique biological properties of SCLC cells, including metastatic potential and drug sensitivity.

Carcinoma, Non-Small-Cell Lung↗
PubMed2000

Primary LAMP-2 deficiency causes X-linked vacuolar cardiomyopathy and myopathy (Danon disease).

"Lysosomal glycogen storage disease with normal acid maltase" which was originally described by Danon et al., is characterized clinically by cardiomyopathy, myopathy and variable mental retardation. The pathological hallmark of the disease is intracytoplasmic vacuoles containing autophagic material and glycogen in skeletal and cardiac muscle cells. Sarcolemmal proteins and basal lamina are associated with the vacuolar membranes. Here we report ten unrelated patients, including one of the patients from the original case report, who have primary deficiencies of LAMP-2, a principal lysosomal membrane protein. From these results and the finding that LAMP-2-deficient mice manifest a similar vacuolar cardioskeletal myopathy, we conclude that primary LAMP-2 deficiency is the cause of Danon disease. To our knowledge this is the first example of human cardiopathy-myopathy that is caused by mutations in a lysosomal structural protein rather than an enzymatic protein.

Antigens, CD↗
PubMed2000

Recognition of formamidopyrimidine by Escherichia coli and mammalian thymine glycol glycosylases. Distinctive paired base effects and biological and mechanistic implications.

The activity of prokaryotic and mammalian thymine glycol (Tg) glycosylases including Escherichia coli endonuclease III (Endo III) and endonuclease VIII (Endo VIII) and mouse Endo III homologue (mNth1) for formamidopyrimidine (Fapy) has been investigated using defined oligonucleotide substrates. 2, 6-Diamino-4-hydroxy-5-N-methylformamidopyrimidine, a methylated Fapy derived from guanine, was site specifically incorporated in the oligonucleotide. The substrates containing Fapy:N pairs (N = A, G, C, T) as well as a Tg:A pair, a physiological substrate of Endo III, Endo VIII, and mNth1, were treated by the enzymes and nicked products were quantified by gel electrophoresis. The activity of Endo III and Endo VIII for Fapy varied markedly depending on the paired base, being the highest with G (activity relative to Tg = 0. 55 (Endo III) and 0.41 (Endo VIII)) and the lowest with C (0.05 (Endo III) and 0.06 (Endo VIII)). In contrast, mNth1 recognized all Fapy pairs equally well and the activity was comparable to Tg. The results obtained in the nicking assay were further substantiated by the analysis of the Schiff base intermediate using NaBH(4) trapping assays. These results indicate that Escherichia coli and mammalian Tg glycosylases have a potential activity to recognize Fapy. However, as demonstrated for Fapy:C pairs, their distinctive activities implicate unequal participation in the repair of Fapy lesions in cells.

Animals↗
PubMed2000

Flow cytometric differentiation of Asian and Western types of multiple sclerosis, HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and hyperIgEaemic myelitis by analyses of memory CD4 positive T cell subsets and NK cell subsets.

We examined the alterations of memory CD4(+) T cell subsets bearing surface receptors linked to either Th1 or Th2 cytokine production as well as natural killer (NK) cell subsets by three color flow cytometry in the peripheral blood from 36 patients with clinically definite multiple sclerosis (MS), 27 patients with HAM/TSP, 13 patients with hyperIgEaemic myelitis who had mite antigen-specific IgE and 25 healthy controls (HC). The patients with MS were clinically classified into an optico-spinal form of MS (Asian type, MS-A) and the conventional form of MS (Western type, MS-W). MS-A showed a significant increase of CD4(+)CD45RA(-)CCR5(+) cells (Th1 cells) through the relapse and remission phases in comparison to HC, while MS-W showed a significant increase of CD4(+)CD45RO(+)CD62L(-) cells (Th1 cells) only at the relapse phase. HAM/TSP showed a significant increase of CCR5(+) and CD62L(-) memory CD4(+) T cells as well as CD30(+) memory CD4(+) T cells (Th2 cells) in comparison to HC. On the other hand, a selective increase of CD4(+)CD45RO(+)CD30(+) cells was found in hyperIgEaemic myelitis. The percentage of mature NK cells (CD3(-)CD16(+)CD56(+) cells) as well as double negative T cells (CD3(+)CD4(-)CD8(-) cells) decreased significantly in HAM/TSP in comparison to HC. Our findings therefore suggest a flow cytometric analysis of Th1/Th2-associated markers on memory CD4(+) T cells as well as NK cell subsets to be useful for differentiating various inflammatory neurologic conditions.

Adult↗
PubMed2000

Biochemical evidence for the involvement of tyrosine in epoxide activation during the catalytic cycle of epoxide hydrolase.

Epoxide hydrolases (EH) catalyze the hydrolysis of epoxides and arene oxides to their corresponding diols. The crystal structure of murine soluble EH suggests that Tyr(465) and Tyr(381) act as acid catalysts, activating the epoxide ring and facilitating the formation of a covalent intermediate between the epoxide and the enzyme. To explore the role of these two residues, mutant enzymes were produced and the mechanism of action was analyzed. Enzyme assays on a series of substrates confirm that both Tyr(465) and Tyr(381) are required for full catalytic activity. The kinetics of chalcone oxide hydrolysis show that mutation of Tyr(465) and Tyr(381) decreases the rate of binding and the formation of an intermediate, suggesting that both tyrosines polarize the epoxide moiety to facilitate ring opening. These two tyrosines are, however, not implicated in the hydrolysis of the covalent intermediate. Sequence comparisons showed that Tyr(465) is conserved in microsomal EHs. The substitution of analogous Tyr(374) with phenylalanine in the human microsomal EH dramatically decreases the rate of hydrolysis of cis-stilbene oxide. These results suggest that these tyrosines perform a significant mechanistic role in the substrate activation by EHs.

Animals↗
PubMed2000

Abnormal immune function of hemopoietic cells from alymphoplasia (aly) mice, a natural strain with mutant NF-kappa B-inducing kinase.

Alymphoplasia (aly) mice, a natural strain with a mutant NF-kappa B-inducing kinase (NIK) gene, manifest a unique phenotype; they lack lymph nodes and Peyer's patches, have a disturbed spleen architecture, and exhibit defects in both Ab and cellular immune responses. Although a stromal defect caused by impaired lymphotoxin-beta receptor signaling accounts for their abnormal lymphoid organogenesis, the exact mechanisms underlying the development of immunodeficiency in aly mice are poorly understood. We therefore investigated the contribution of hemopoietic cells with the aly NIK mutation to the development of immunodeficiency. Transfer of aly/aly bone marrow cells into aly/+ mice resulted in poorly developed B cell follicles and lack of support for the development of germinal centers and isotype switching, indicating that the hemopoietic cells of aly mice contain an autonomous defect. However, follicular dendritic cell clusters were maintained in the spleens of these bone marrow chimeras, suggesting that the lack of follicular dendritic cell clusters in aly mice is probably due to the stromal defect. The aly mice lacked marginal zone B cells in their spleens, and aly/aly B cells showed an impaired proliferative response after in vitro stimulation. IL-2 production by activated T cells was also impaired. By contrast, the dendritic cells of aly mice exhibited grossly normal development and function. Supporting the concept of an autonomous cell defect, Rel protein expression was altered in aly/aly spleens. Thus, the aly NIK mutation affects hemopoietic cell function in an intrinsic fashion and, together with the stromal defect, may contribute to the development of immunodeficiency in aly mice.

Animals↗
PubMed2000

Supramolecular complex of cytochrome c with lariat ether: solubilization, redox behavior and catalytic activity of cytochrome c in methanol.

A variety of lariat ethers were employed to solubilize water-soluble cytochrome c in methanol, in which alcohol, ether, ester, amine, and amide functionalities were attached as cation-ligating side arms to 18-crown-6, 15-crown-5, and 12-crown-4 rings. Among these lariat ethers, the alcohol-armed 18-crown-6 derivative offered the highest solubilization efficiency for cytochrome c via supramolecular complexation. The resulting cytochrome c-lariat ether complexes were electrochemically and spectroscopically characterized and confirmed to have redox-active heme structures of 6-coordinate low-spin population in methanol. Some of them catalyzed the oxidation of pinacyanol chloride with hydrogen peroxide in methanol and exhibited higher activities than unmodified cytochrome c and its poly(ethylene glycolated) derivative. Since the supramolecular complexation between lariat ether and cytochrome c includes extremely simple procedures, it provides a facile preparation method of effective biocatalysts working in organic solvents from metalloproteins.

Carbocyanines↗
PubMed2000

LambdaN spin-orbit splittings in (9)(Lambda)Be and (13)(Lambda)C studied with one-boson-exchange LambdaN interactions

Movitated by the on-going gamma-ray experiments at the Alternating Gradient Synchrotron at Brookhaven National Laboratory, we discuss the energy splittings of the 5/2(+)(1)-3/2(+)(1) doublet in (9)(Lambda)Be and the 3/2(-)(1)-1/2(-)(1) doublet in (13)(Lambda)C for which the LambdaN spin-orbit ( LS) and antisymmetric spin-orbit ( ALS) forces are relevant. In the microscopic 2alpha+Lambda ( 3alpha+Lambda) model for (9)(Lambda)Be ( (13)(Lambda)C), all the available Nijmegen one-boson-exchange (OBE) model LambdaN interactions lead to a wide range of splittings of 0.08-0.20 MeV in (9)(Lambda)Be and 0.39-0.96 MeV in (13)(Lambda)C. On the other hand, if we use information from quark-model LambdaN interactions which have generally large ALS force, the splittings become about half of the smallest OBE model prediction.

Journal Article↗
PubMed2000

Frequent chromosome 8q gains in human small cell lung carcinoma detected by arbitrarily primed-PCR genomic fingerprinting.

The arbitrarily primed-polymerase chain reaction (AP-PCR) genomic fingerprinting method was applied to detect chromosomal numerical imbalances in 13 small cell lung carcinomas (SCLC). Increases and decreases in the intensity of the AP-PCR bands from several chromosomes, representing gains of chromosomes 1, 7, 16, and X, and losses of chromosomes 2, 10, and 22, were recurrent events in independent tumors. In addition, the most common alterations detected were increases in signal intensity of three AP-PCR bands derived from genomic sequences on chromosome 8q (eight of 13 tumors: 62%). To define whether the 8q gains observed in the AP-PCR analysis include the C-MYC gene at chromosome 8q24 or not, we performed targeted AP-PCR analysis of the C-MYC gene. The C-MYC gene was amplified in five of the eight tumors with gains of 8q, but in none of the remaining five tumors in which 8q gains were not detected. These results indicate that chromosome 8q gain occurs frequently in SCLC and gained regions often, but do not always, include the C-MYC gene. Moderate increases in copy number of the C-MYC gene and additional gene(s) in the 8q region appear to be under positive selection during SCLC progression.

Carcinoma, Small Cell↗
PubMed2000

A novel isoform of a kallikrein-like protease, TLSP/hippostasin, (PRSS20), is expressed in the human brain and prostate.

cDNAs encoding two splicing variants of a serine protease, termed hippostasin, were isolated by a PCR-based cloning strategy. The difference of 5' nucleotide sequence resulted in the variation in the amino terminal ends of the two, brain and prostate, types of human hippostasin. The longest ORF of the brain-type was 250 amino acids with a putative signal peptide, while that of the prostate-type was 282 amino acids. Homology search using the amino acid sequence revealed that prostate-type hippostasin was identical to TLSP (PRSS20), which is expressed in human primary keratinocytes (1). Transient expression analysis showed that both brain- and prostate-type TLSP/hippostasin were secreted into the conditioned medium as about 40 kDa proteins. Human TLSP/hippostasin showed 47% and 45% identity to trypsinogen II and kallikrein, respectively. In fact, the recombinant human TLSP/hippostasin efficiently cleaved Bz-Phe-Arg-4-methylcoumaryl-7-amide, a kallikrein substrate, and weakly cleaved other substrates for kallikrein and trypsin. Northern blot analysis detected a 1.3 kb band in the whole brain and a 1.4 kb band in the prostate and the lung. In situ hybridization revealed that it was expressed preferentially by the pyramidal neurons in the human hippocampus and secretory epithelial cells in the prostate. These results indicated that TLSP/hippostasin is involved in the functions of the human central nervous system and prostate and that it is a multifunctional protease present in various organs.

Alternative Splicing↗
PubMed2000

Antigen dose defines T helper 1 and T helper 2 responses in the lungs of C57BL/6 and BALB/c mice independently of splenic responses.

To investigate the effect of antigen dose on immune response, C57BL/6 and BALB/c mice were sensitized with aluminum hydroxide gel (alum)-precipitated ovalbumin (OVA) then challenged with aerosolized OVA. Low-dose sensitization (less than 8 microg of OVA) elicited T helper 2 (Th2)-type immunoglobulins (Igs) secretion from C57BL/6 mice, including high levels of serum IgE, IgG1 and low levels of IgG2a, while BALB/c mice secreted T helper 1 (Th1)-type Igs, including low levels of IgE, IgG1 and high levels of IgG2a. In contrast, high-dose sensitization (more than 50 microgram) elicited Th1-type Igs secretion in C57BL/6mice, while BALB/c mice exhibited Th2-type Igs secretion. Furthermore, the number of eosinophils infiltrating into the lungs of low-dose OVA-sensitized C57BL/6 mice was significantly greater than in BALB/c mice sensitized with the same amount of OVA. Only a very high dose of OVA (1 mg) could induce greater eosinophil infiltration into the lungs of BALB/c mice compared with C57BL/6 mice. Additionally, low-dose sensitization generated Th2-type cytokines, including high levels of interleukin (IL) -4, IL-5 and a low level of interferon-gamma (IFN-gamma) in the lungs of C57BL/6 mice, while BALB/c mice generated Th1-type cytokines in their lungs, including low levels of IL-4, IL-5 and a high level of IFN-gamma. In contrast, high-dose sensitization elicited Th1-type cytokines production in the lungs of C57BL/6 mice, while BALB/c mice generated Th2-type cytokines in their lungs. Interestingly, splenocyte cultures from C57BL/6 mice produced Th1-type cytokines, while cultures from BALB/c mice produced Th2-type cytokines regardless of OVA sensitization dose (100 ng-1 mg). These results indicate that C57BL/6 and BALB/c mice have different susceptibilities to OVA-sensitization and OVA-induced pulmonary eosinophilia regulated by Th1- and Th2-type cytokines, independent of splenic Th1- and Th2-type cytokines production.

Animals↗
PubMed2000

The domains of human fibronectin mediating the binding of alpha antigen, the most immunopotent antigen of mycobacteria that induces protective immunity against mycobacterial infection.

We have recently shown that alpha antigen (alpha-Ag), the immunodominant antigen of mycobacteria, has a novel fibronectin (FN)-binding motif that is unique among mycobacteria [Naito, Ohara, Matsumoto and Yamada (1998) J. Biol. Chem. 273, 2905-2909]. In this study, we examined the domains of human FN that interacted with alpha-Ag. Fragments of FN generated by either proteolysis or recombinant DNA techniques were compared for their ability to bind to alpha-Ag. Fragments containing either the C-terminal heparin-binding domain or the central cell-binding domain consistently bound to alpha-Ag. The fragment of the C-terminal heparin-binding domain, upon mutation that resulted in the loss of its heparin-binding activity, could not bind with alpha-Ag. These findings suggested that the mutated site, i.e. the main heparin-binding site of FN, was also the principal site for binding to alpha-Ag. The alpha-Ag-binding domains of FN could bind whole mycobacterial bacilli, suggesting that these two domains are important contributors to mycobacterial infection.

Antigens, Bacterial↗
PubMed2000

Prevention of halothane-induced hepatotoxicity by hemin pretreatment: protective role of heme oxygenase-1 induction.

Reductive metabolism of halothane in phenobarbital-pretreated rats is known to increase free radical formation that results in hepatotoxicity. It also is associated with a marked induction of microsomal heme oxygenase-1 (HO-1), suggesting that there is an alteration in heme metabolism. In this study, we examined heme metabolism in rats pretreated with phenobarbital, followed by exposure to halothane-hypoxia. In this model, there was a significant decrease in microsomal cytochrome P450 content in the liver, followed by a rapid increase in free heme concentration and a decrease in the level of mRNA for the nonspecific delta-aminolevulinate synthase. A transient but dramatic induction of HO-1 mRNA and a prolonged induction of heat shock protein 70 mRNA also occurred. The HO-1 protein was detected principally in the hepatocytes around the central vein. Serum alanine transaminase (ALT) activity, an indicator of hepatic dysfunction, increased continuously throughout the experiment. Hemin pretreatment induced hepatic HO-1 with abrogation of the halothane-induced hepatotoxicity in this model, as judged by ALT activity and normal histology. Our findings in this study thus indicate that halothane-induced hepatotoxicity is due not only to its reductive metabolite formation, but also to an increase in hepatic free heme concentration, which is a potent prooxidant; HO-1 induction is an important protective response against such changes. This is also the first study to demonstrate that hemin pretreatment, which induces HO-1 prior to exposure to halothane, effectively prevents halothane-induced hepatotoxicity.

5-Aminolevulinate Synthetase↗
PubMed2000

Synthesis and biological evaluation of novel 9-functional heterocyclic coupled 7-deoxy-9-dihydropaclitaxel analogue.

Novel 9-functional heterocyclic coupled 7-deoxy-9-dihydropaclitaxel analogues 17 and 22-24 synthesized from a natural taxoid 5-cinnamoyltriacetyltaxicin-I (3) and their biological evaluation in tubulin assembly activity and cytotoxicity in vitro against several human tumor cell lines are first presented. The biologically tested results show that 17, 22 and 23 are inactive in tubulin assembly assay and have no more remarkable cytotoxicities against human tumor cell lines SK-OV3, WIDR and MCF-7, though 22 and 23 exhibit more potent cytotoxicity against human liver cancer and human esophagus cancer cell lines (BEL-7402 and ECa-109) than paclitaxel.

Antineoplastic Agents, Phytogenic↗
PubMed2000

The HMG box transcription factor gene Sox14 marks a novel subset of ventral interneurons and is regulated by sonic hedgehog.

Cell-type diversity along the dorsoventral axis of the developing neural tube is influenced by factors secreted by groups of cells at the dorsal and ventral midline. Upon reception of these signals, precursor cells express specific sets of transcription factors which, in turn, play critical roles in cell-type specification. Here we report the cloning and characterization of Sox14, a novel and highly conserved member of the Sry-related Sox transcription factor gene family, in mouse and chick. Sox14 expression is restricted to a limited population of neurons in the developing brain and spinal cord of both species. Sox14 marks a subset of interneurons at a defined dorsoventral position adjacent to ventral motor neurons in the spinal cord. In vivo grafting of chick notochord tissue to ectopic positions adjacent to the developing spinal cord altered the expression domain of Sox14. Furthermore, expression of Sox14 in spinal cord explants was found to be regulated by Sonic hedgehog in a dose-dependent manner. These data implicate a novel class of transcription factors in dorsoventral cell-type specification in the spinal cord.

Amino Acid Sequence↗
PubMed2000

Distinct repair activities of human 7,8-dihydro-8-oxoguanine DNA glycosylase and formamidopyrimidine DNA glycosylase for formamidopyrimidine and 7,8-dihydro-8-oxoguanine.

7,8-dihydro-8-oxoguanine (8-oxoG) and 2,6-diamino-4-hydroxyformamidopyrimidine (Fapy) are major DNA lesions formed by reactive oxygen species and are involved in mutagenic and/or lethal events in cells. Both lesions are repaired by human 7, 8-dihydro-8-oxoguanine DNA glycosylase (hOGG1) and formamidopyrimidine DNA glycosylase (Fpg) in human and Escherichia coli cells, respectively. In the present study, the repair activities of hOGG1 and Fpg were compared using defined oligonucleotides containing 8-oxoG and a methylated analog of Fapy (me-Fapy) at the same site. The k(cat)/K(m) values of hOGG1 for 8-oxoG and me-Fapy were comparable, and this was also the case for Fpg. However, the k(cat)/K(m) values of hOGG1 for both lesions were approximately 80-fold lower than those of Fpg. Analysis of the Schiff base intermediate by NaBH(4) trapping implied that lower substrate affinity and slower hydrolysis of the intermediate for hOGG1 than Fpg accounted for the difference. hOGG1 and Fpg showed distinct preferences of the base opposite 8-oxoG, with the activity differences being 19.8- (hOGG1) and 12-fold (Fpg) between the most and least preferred bases. Surprisingly, such preferences were almost abolished and less than 2-fold for both enzymes when me-Fapy was a substrate, suggesting that, unlike 8-oxoG, me-Fapy is not subjected to paired base-dependent repair. The repair efficiency of me-Fapy randomly incorporated in M13 DNA varied at the sequence level, but orders of preferred and unpreferred repair sites were quite different for hOGG1 and Fpg. The distinctive activities of hOGG1 and Fpg including enzymatic parameters (k(cat)/K(m)), paired base, and sequence context effects may originate from the differences in the inherent architecture of the DNA binding domain and catalytic mechanism of the enzymes.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2000

Vergence disorders in patients with spinocerebellar ataxia 3/Machado-Joseph disease: a synoptophore study.

Diplopia, a common symptom in spinocerebellar ataxia 3/Machado-Joseph disease (SCA3/MJD) cases, is not always due to asymmetric ophthalmoplegia. We found a Japanese SCA3/MJD family, in which three patients clearly had an impairment of divergence eye movement. We thus quantitatively examined the vergence ranges in eight Japanese SCA3/MJD cases using the synoptophore test. An impairment of the vergence eye movements was found in all patients, and the vergence impairment pattern, but not the ophthalmoplegia pattern, was found to be compatible with the diplopia pattern. The diplopia in SCA3/MJD cases is, therefore, attributed, at least in part, to the impairment of the vergence eye movements.

Abducens Nerve↗