Biomedical subjects

H Ohno

Publications and source records attributed to H Ohno.

At least 199 records · Page 11Linked to original sources

PubMed1998

Effect of running training on brown adipose tissue activity in rats: a reevaluation.

The effect was investigated of running training on the thermogenic activity of brown adipose tissue (BAT) in rats. The exercised rats were trained on a rodent treadmill for 5 days per week and a total of 9 weeks. After the training, a significantly lower rate of increase in body weight was found, suggesting some training effect, whereas the training failed to induce a decrease in BAT mass. As previously reported (Yamashita, Yamamoto et al., 1993), there was also a markedly lower expression of uncoupling protein (UCP) mRNA in BAT from trained rats; nevertheless, no definite effect of the running training was noted on either UCP content or guanosine 5'-diphosphate binding in the mitochondria recovered from BAT. The results obtained suggest that running training has no overt effect on the thermogenic activity of BAT in rats.

Adipose Tissue, Brown↗

PubMed1998

[Successful treatment with donor leukocyte transfusion followed by interferon-alpha in a patient with relapsed chronic myelogenous leukemia after allogeneic bone marrow transplantation].

A 44-year-old man with CML in chronic phase was admitted for BMT from an HLA-identical sibling. Ph positive cells were undetectable at 3 and 7 months after BMT but became detectable by cytogenetic analysis of bone marrow aspirates at 12 months after BMT. He was treated with IFN-alpha (6 million units/day, 3 times a week) without apparent effect. Donor leukocyte transfusion (DLT) was performed four times between 20 months and 23 months after BMT, transfusing 3.4 x 10(8) mononuclear cells/kg. However, leukocytosis appeared and the NAP score declined at 25 months after BMT. FISH analysis revealed an increase in bcr-abl positive cells. IFN-alpha was restarted using the same schedule at 26 months after BMT. Three months after restarting IFN-alpha, the leukocyte count fell to the normal range, NAP score increased to a normal level, and bcr-abl positive cells decreased markedly. He has remained in hematological and cytogenetic remission for 20 months, and bcr-abl chimeric mRNA remained undetectable by PCR. These results suggest that CML which does not respond to DLT may be cured by subsequent IFN-alpha therapy, possibly by inducing anti-leukemia immune responses.

Adult↗

PubMed1998

Effects of dietary calcium restriction on vascular constriction and relaxation of the rat isolated aorta.

The blood pressure of the rat is influenced by the dietary restriction of calcium. Since the vasomotor activities may be affected by calcium restriction, we measured vasoconstriction as well as endothelium-dependent and endothelium-independent relaxation responses in isolated aortic rings of the Wistar rat. Compared with the control rat fed a normal diet (1.04% calcium), the femur mineral density was significantly reduced in the rat fed the low-calcium (< 0.01%) diet for one month (LC1M) or for three months (LC3M). Although neither LC1M nor LC3M changed Cmax (the maximum constriction induced by phenylephrine) in aortic rings without endothelium, LC3M, but not LC1M, significantly increased CD50 (the dose of phenylephrine inducing 50% of Cmax). On the other hand, the low-calcium diet did not change Cmax and CD50 in rings with intact endothelium. Thel low-calcium diet showed no significant change in the vasorelaxation responses to acetylcholine (Ach) or sodium nitroprusside (SNP). Cyclic GMP production stimulated by Ach or SNP was not affected by calcium restriction. These results suggest that an insufficient calcium supply for three months, attenuates alpha-adrenoceptor-mediated vasoconstriction in the normotensive rat but vasorelaxation responses to Ach or SNP are not affected.

Acetylcholine↗

PubMed1998

[Multidrug-resistant tuberculosis. 2. Mechanisms of drug-resistance in Mycobacterium tuberculosis--genetic mechanisms of drug-resistance].

Multidrug-resistant Mycobacterium tuberculosis infection is now world wide health problem. However, according to the recent advances of molecular biological technics, some of the genetic mechanisms of drug-resistance of M. tuberculosis has been uncovered. Generally, drug-resistance of M. tuberculosis was caused by point mutations in chromosomal gene. In isoniazid (INH) resistant M. tuberculosis, mutations and genetic deletions in catalase-peroxidase gene (katG), inhA gene, or alkyl hydroperoxide reductase gene were reported. We also found that about 15% of INH-resistant M. tuberculosis isolates lacked katG gene, and these isolates showed highly resistance to INH with MIC > or = 64 micrograms/ml. On the other hand, mutations and other genetic alterations in RNA polymerase beta subunit gene (rpoB) were the major mechanisms of resistance to rifampicin (RFP) with high frequencies of 90% or more. Our evaluation of the relationship between RFP susceptibility and genetic alteration in rpoB gene also showed that 95% of RFP-resistant M. tuberculosis isolates involved genetic alterations in 69 bp core region of rpoB gene. Moreover, these genetic alterations in rpoB gene were suspected as the resistant mechanism to other rifamycin antituberculosis drugs, such as rifabutin and KRM-1648. In addition, it was reported that point mutations in 16S rRNA gene (rrs) and ribosomal protein S12 gene (rpsL) induced M. tuberculosis as streptomycin (SM) resistant phenotype. We analyzed genetic alternations in rpsL gene of clinically isolates of M. tuberculosis, about 60% of SM resistant isolates were shown point mutation in this gene ant they were all high SM-resistant with MIC > or = 256 micrograms/ml. Furthermore, nicotinamidase (pncA) gene, DNA gyrase A subunit (gyrA) gene, and embB gene were reported as the responsible gene to pyrazinamide-, quinolone- and ethambutol-resistance, respectively. Although all mechanisms of drug-resistance were still unclear, these informations are very useful and helpful for development of rapid diagnosis system of drug-resistant M. tuberculosis.

Drug Resistance, Microbial↗

PubMed1998

[Mechanisms of drug-resistance in mycobacteria].

According to the recent advances of molecular biological technics, some of the genetic mechanisms of drug-resistance of Mycobacteria has been uncovered. Generally, drug-resistance of Mycobacterium tuberculosis was caused by point mutations in chromosomal gene. In isoniazid (INH) resistant M. tuberculosis, mutations and genetic deletions in catalase-peroxidase gene (katG), inhA gene, or alkyl hydroperoxide reductase gene were reported. On the other hand, mutations and other genetic alterations in RNA polymerase beta subunit gene (rpoB) were the major mechanisms of resistance to rifampicin (RFP) with high frequencies of 90% or more. Moreover, these genetic alterations in rpoB gene were suspected as the resistant mechanism to other rifamycin antituberculosis drugs, such as rifabutin. In addition, it was reported that point mutations in 16S rRNA gene (rrs) and ribosomal protein S12 gene (rpsL) induced M. tuberculosis as streptomycin (SM) resistant phenotype. Furthermore, nicotinamidase (pncA) gene, DNA gyrase A subunit (gyrA) gene, and embB gene were reported as the responsible gene to pyrazinamide-, quinolone- and ethambutol-resistance, respectively. Although all mechanisms of drug-resistance were still unclear, these information are very useful and helpful for development of rapid diagnosis system of drug-resistant M. tuberculosis.

Drug Resistance, Microbial↗

PubMed1998

[Biopsy for diagnosis of tuberculosis].

Recent advances of molecular techniques make diagnosis of pulmonary tuberculosis rapid and easier comparing to conventional techniques. However, diagnosis for tuberculosis, especially tuberculous pleuritis, tuberculous lymphadenitis and non-pulmonary tuberculosis, is not easy. Transbroncheal lung biopsy (TBLB) is a helpful examination for not only pulmonary tuberculosis but also malignant diseases. The pleural biopsy using Cope needle was commonly used as a method for diagnosis of tuberculous pleuritis, and the sensitivity of pleural biopsy is about 50% or more. Furthermore, the pleural biopsy using thoracoscopy was reported to show a higher sensitivity for the diagnosis of tuberculous pleuritis. A lymph node biopsy is also a useful method for diagnosis of tuberculous lymphadenitis. Thus, a biopsy method is the reliable tool for diagnosis of not only pulmonary tuberculosis, but also other organ tuberculosis.

Biopsy↗

PubMed1997

Association with FcRgamma is essential for activation signal through NKR-P1 (CD161) in natural killer (NK) cells and NK1.1+ T cells.

Natural killer (NK) cells exhibit cytotoxicity against variety of tumor cells and virus-infected cells without prior sensitization and represent unique lymphocytes involved in primary host defense. NKR-P1 is thought to be one of NK receptors mediating activation signals because cross-linking of NKR-P1 activates NK cells to exhibit cytotoxicity and IFN-gamma production. However, molecular mechanism of NK cell activation via NKR-P1 is not well elucidated. In this study, we analyzed the cell surface complex associated with NKR-P1 on NK cells and found that NKR-P1 associates with the FcRgamma chain which is an essential component of Fc receptors for IgG and IgE. The association between FcRgamma and NKR-P1 is independent of Fc receptor complexes. Furthermore, NK cells from FcRgamma-deficient mice did not show cytotoxicity or IFN-gamma production upon NKR-P1 cross-linking. Similarly, NK1.1+ T cells from FcRgamma-deficient mice did not produce IFN-gamma upon NKR-P1 crosslinking. These findings demonstrate that the FcRgamma chain plays an important role in activation of NK cells via the NKR-P1 molecule.

Animals↗

PubMed1997

Interaction of endocytic signals from the HIV-1 envelope glycoprotein complex with members of the adaptor medium chain family.

The envelope glycoprotein (Env) complex of HIV-1 undergoes rapid internalization from the plasma membrane of human cells by virtue of a tyrosine-based endocytic signal (RQGYSPL, residues 704-710) in the cytosolic tail of the protein (J. F. Rowell et al., J. Immunol. 155, 473-488, 1995). Here we demonstrate that this tyrosine-based signal interacts with the mu 2 (medium) chain of the AP-2 clathrin-associated adaptor, a protein complex involved in endocytosis of cell surface receptors. The same signal is also capable of interacting with two other members of the adaptor medium chain family, mu 1 and mu 3A, which are components of the AP-1 and AP-3 adaptor complexes, respectively. Interactions with mu 1 and mu 3A might be responsible for the targeting of the internalized envelope glycoprotein to lysosomes or to the basolateral plasma membrane of polarized epithelial cells. A second potential tyrosine-based signal (LFSYHRL, residues 760-766) also interacts with mu 1, mu 2, and mu 3A, although it is less important for internalization in vivo probably due to its position within the cytosolic tail. Overexpression of chimeric proteins having the HIV-1 Env cytosolic tail increases expression of the transferrin receptor on the cell surface, probably due to saturation of the cellular pool of mu 2 by the overexpressed proteins. These observations suggest that HIV-1 Env utilizes the protein sorting machinery of the host cells for internalization and sorting at various steps of the endocytic and biosynthetic pathways.

Adaptor Proteins, Vesicular Transport↗

PubMed1997

Functional domain mapping of the clathrin-associated adaptor medium chains mu1 and mu2.

The clathrin-associated adaptors AP-1 and AP-2 are heterotetrameric complexes involved in the recognition of sorting signals present within the cytosolic domain of integral membrane proteins. The medium chains of these complexes, mu1 and mu2, have been implicated in two types of interaction: assembly with the beta1 and beta2 chains of the corresponding complexes and recognition of tyrosine-based sorting signals. In this study, we report the results of a structure-function analysis of the mu1 and mu2 chains aimed at identifying regions of the molecules that are responsible for each of the two interactions. Analyses using the yeast two-hybrid system and proteolytic digestion experiments suggest that mu1 and mu2 have a bipartite structure, with the amino-terminal one-third (residues 1-145 of mu1 and mu2) being involved in assembly with the beta chains and the carboxyl-terminal two-thirds (residues 147-423 of mu1 and 164-435 of mu2) binding tyrosine-based sorting signals. These observations support a model in which the amino-terminal one-third of mu2 is embedded within the core of the AP-2 complex, while the carboxyl-terminal two-thirds of the protein are exposed to the medium, placing this region in a position to interact with tyrosine-based sorting signals.

Adaptor Protein Complex 1↗

PubMed1997

Purification and characterization of an Aspergillus oryzae-produced carboxylesterase that catalyzes O-deacetylation of a fully acetylated O-glucoside of N-phenylacetohydroxamic acid.

A carboxylesterase [2,3,4,6-tetra-O-acetyl-1-[(N-acetyl-N-phenylamino)oxy]-1-deoxy-beta-D-g lucopyranoside (GPA) O-deacetylase] from a culture product of Aspergillus oryzae (Taka diastase) was purified 8500-fold with a yield of 3%. The molecular mass of the purified enzyme was shown to be 35 +/- 1 kDa by SDS/PAGE. The enzyme shows a selective O-deacetylation activity of GPA to give the fully O-deacetylated glucoside. Among the substrates tested, the enzyme did not hydrolyze benzoyl and phenylacetyl esters and acetamides. In the hydrolysis of p-nitrophenyl esters, the acyl preference is acetyl > propionyl > butyryl, judging from the Vmax/Km values. A good correlation between log(Vmax/Km) and the Taft's Es constant of the alkyl group of the acyl moiety was obtained. The optimum pH was around 7.3 at 37 degrees C, and the enzyme was inhibited by mercuric chloride, p-chloromercuribenzoate and diisopropyl fluorophosphate. This enzyme should be useful for the selective removal of acetyl groups that serve to protect hydroxyl groups during carbohydrate synthesis.

Acetylation↗

PubMed1997

Purification and subunit structure of extracellular superoxide dismutase from mouse lung tissue.

The first purification of mouse extracellular superoxide dismutase (EC-SOD) and the analysis of the native enzyme are described. Mouse EC-SOD was purified from lung tissues with a high recovery (41%) and a specific polyclonal antibody against the purified enzyme was obtained. The purified enzyme had a strong affinity for, heparin and a molecular mass of 150 kDa (estimated by a gel filtration chromatography). The native mouse EC-SOD was composed of two different sizes of subunits, a M(r) of 33 and 35 kDa (determined by SDS-PAGE). The 35-kDa subunit had an interchain disulfide bond at the C-terminus and existed as a covalent dimer in the molecule, whereas the 33-kDa subunit resulted from the 35-kDa subunit by truncating its C-terminus as a posttranslational modification, with resultant loss of the interchain disulfide bond. These results suggest that the native mouse EC-SOD is a heterotetramer composed of two different dimers, with or without a covalent bond.

Animals↗

PubMed1997

AP-3: an adaptor-like protein complex with ubiquitous expression.

We have identified two closely related human proteins (sigma3A and sigma3B) that are homologous to the small chains, sigma1 and sigma2, of clathrin-associated adaptor complexes. Northern and Western blot analyses demonstrate that the products of both the sigma3A and sigma3B genes are expressed in a wide variety of tissues and cell lines. sigma3A and sigma3B are components of a large complex, named AP-3, that also contains proteins of apparent molecular masses of 47, 140 and 160 kDa. In non-neuronal cells, the 47 kDa protein most likely corresponds to the medium chain homolog p47A, and the 140 kDa protein is a homolog of the neuron-specific protein beta-NAP. Like other members of the medium-chain family, the p47A chain is capable of interacting with the tyrosine-based sorting signal YQRL from TGN38. Immunofluorescence microscopy analyses show that the sigma3-containing complex is present both in the area of the TGN and in peripheral structures, some of which contain the transferrin receptor. These results suggest that the sigma3 chains are components of a novel, ubiquitous adaptor-like complex involved in the recognition of tyrosine-based sorting signals.

Adaptor Protein Complex 1↗

PubMed1997

A shift from negative to positive selection of autoreactive T cells by the reduced level of TCR signal in TCR-transgenic CD3 zeta-deficient mice.

T cell selection is thought to be determined through the interaction between TCR and Ag/MHC. However, the contribution of the level of TCR signal to thymic selection remains unclear. To address this issue, we analyzed T cell selection of male Ag (HY)-specific TCR transgenic (HYTg) mice crossed with CD3 zeta-deficient (zeta KO) mice (HYTg/zeta KO), which have impaired signaling through TCR. In male HYTg/zeta KO mice, the number of thymocytes was comparable to that in normal mice, and almost all the peripheral T cells were HY specific, although these positively selected cells were anergic to male Ag. From these observations, the decrease in TCR signaling by CD3 zeta deficiency resulted in both the avoidance of negative selection and the acquisition of positive selection of autoreactive T cells in male HYTg/zeta KO mice. There was a shift of T cell selection from positive to no selection of HY-specific T cells in female HYTg/zeta KO mice also. Collectively, these findings suggest that the level of TCR signal directly regulates T cell selection; furthermore, the findings have integrated the models of T cell selection into a concept based on the quantity of TCR signal.

Animals↗

PubMed1997

A recurring translocation, t(3;6)(q27;p21), in non-Hodgkin's lymphoma results in replacement of the 5' regulatory region of BCL6 with a novel H4 histone gene.

3q27 translocations affecting the BCL6 gene can involve not only immunoglobulin genes (IG) but also other as yet uncharacterized chromosomal loci as partners. Here, we describe cloning of the junctional area of a recurring translocation, t(3;6)(q27;p21), in non-Hodgkin's lymphoma of B-cell type and isolation of clones from 6p21; high resolution fluorescence in situ hybridization mapped the clones to sub-band 6p21.3. Nucleotide sequence analysis of a fragment from the junctional area of 6p21 revealed the presence of a novel H4 histone gene that was included in the histone gene cluster on this particular region, and the same fragment detected approximately 380-bp transcripts in hematological tumor cells. Breakpoints on 3q27 of two cases carrying t(3;6) were immediately 3' of the BCL6 exon 1, and the H4 histone gene was substituted for the 5' regulatory elements of BCL6. Because H4 gene expression is tightly coupled to DNA replication, this study suggested an immediate mechanism for deregulated expression of BCL6, leading to the development of non-Hodgkin's lymphoma.

Base Sequence↗

PubMed1997

Human hepatitis B virus enhancer 1 is responsive to human interleukin-6.

Serum levels of interleukin-6 (IL-6) are elevated in acute and chronic hepatitis B patients. The effect of IL-6 and its transcription factor of NF-IL6 (a nuclear factor for IL-6) on hepatitis B virus (HBV) enhancer 1 (Enh1), which controls HBV X expression, were investigated in HepG2 cells. Twenty ng/ml of IL-6 increased 4-fold the enhancer activity of Enh1 according to the CAT assay. The IL-6 stimulation was abolished by introducing a mutation either in an AP-1-related site or a C-stretch sequence in the Enh1 sequence, demonstrating that the cis-elements are necessary for the IL-6 response. Co-transfection of NF-IL6 expression plasmid similarly increased the enhancer activity of Enh1 through both binding sites. Further, a specific complex formation of the Enh1 was detected using HepG2 nuclear lysates by electromobility shift assays, and the complex formation was increased in the lysates of cells treated with IL-6 and NF-IL6-transfection. In competition assays, one half of the complex formed was found to remain in the presence of 500-times excess competitor DNA fragment harboring NF-IL2 binding site, suggesting indirect binding of NF-IL6 to the Enh1 sequence. These results indicate that IL-6 increased the enhancer activity of HBV Enh1 through signal transduction pathways, indirectly involving NF-IL6, and may control HBV X expression and viral replication in HBV infected liver.

Base Sequence↗

PubMed1997

Neural reflex-mediated tracheal response during bronchoconstriction induced by ovalbumin antigen in guinea pigs.

1. The biphasic reflex tracheal response (constriction followed by dilatation) occurred during bronchoconstriction induced by inhalation of ovalbumin antigen (OA) in sensitized guinea pigs. 2. The reflex tracheal constriction was largely reduced by atropine, and the dilatation was inhibited by propranolol and N omega-nitro-L-arginine methyl ester (L-NAME). The noradrenaline, adrenaline, cyclic AMP, and cyclic GMP contents in the tracheal segment were significantly higher during reflex tracheal dilatation. 3. These findings suggest that cholinergic nerves may mediate reflex tracheal constriction and that adrenergic and NOergic nerves may mediate the ensuing reflex tracheal dilatation.

Allergens↗

PubMed1997

High altitude training increases reactive carbonyl derivatives but not lipid peroxidation in skeletal muscle of rats.

The oxidative stress related consequences of physical training at high altitude are not known. The hypothesis was tested that physical training and exposure to high altitude have adverse effects on free radical generation and activities of antioxidant enzymes. The present results showed that 4 weeks of exercise at an altitude of 4000 m increased the activity of Mn-SOD in both white and red types of skeletal muscle. The activities of Cu,Zn-SOD, catalase, and glutathione peroxidase, as well as the level of lipid peroxidation measured by TBARS and lipid hydroperoxides, did not change significantly. In contrast, the level of reactive carbonyl derivatives measured by anti-2,4-dinitrophenylhydrazone antibodies and spectrophotometry showed an increase in both types of muscle of altitude trained rats compared with sea level trained and control groups. It was suggested that the oxidative modification of certain amino acids is due to the increasing gap between activity of SOD and peroxide scavenging enzymes, which results in increases in the number of hydrogen peroxide molecules. Thus, since the mechanism of generation and/or the mode of action of radicals resulting in lipid peroxidation and protein oxidation appears to be different in vivo, both processes should be studied during oxidative stress.

Altitude↗

PubMed1997

Tyrosine phosphorylation controls internalization of CTLA-4 by regulating its interaction with clathrin-associated adaptor complex AP-2.

CTLA-4 is a costimulation receptor that binds to the same ligands, CD80 and CD86, as CD28 with high affinity and is transiently expressed on the cell surface of activated T cells. CTLA-4 delivers an inhibitory signal through association of a phosphotyrosine-containing motif in the cytoplasmic domain with Syp tyrosine phosphatase. We now demonstrate that CTLA-4 interacts with the mu2 subunit of the plasma membrane-associated adaptor complex, AP-2, through the same motif involved in the interaction with Syp, except that the interaction with mu2 requires unphosphorylated tyrosine. The interaction with mu2 likely induces rapid internalization of CTLA-4 from the cell surface. Our results suggest that the phosphorylation state of a single tyrosine residue determines whether CTLA-4 delivers a negative signal or is internalized.

Abatacept↗