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K Ohyama

Publications and source records attributed to K Ohyama.

At least 127 records · Page 7Linked to original sources
PubMed1993

[Experimental analysis of cytotoxicity mediated by activated macrophages against glioma cells in mice].

Macrophage (M phi) has a very important role in host natural defence and tumor cell killing. Activated M phi with tumor cytotoxicity can be induced by various lymphokines, such as interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, interleukin (IL)-2, IL-4, granulocyte macrophage-colony stimulating factor (GM-CSF), and macrophage-colony stimulating factor (M-CSF), but also by various bacterial products, such as lipopolysaccharide (LPS), Bacillus Calmette Guérin (BCG), corynebacterium parvum (C.p.), and muramyl-dipeptide (MDP). Although the brain is considered as an "immunologically privileged site", it has been demonstrated that in malignant brain tumors infiltration of lymphocytes or M phi can be seen in tissue samples. This may suggest that immune surveillance exists in the brain. But the biological significance of infiltrative M phi is unclear. The purpose of this study is to confirm the significant generation of activated M phi with cytotoxicity to glial tumor cells and to elucidate the cytotoxic mechanism associated with cellular interaction between effector M phi and target cells. This is the first report on experimental analysis of cytotoxicity mediated by activated M phi against glioma cells in mice. The cytotoxicity mediated by murine peritoneal activated M phi was examined against 3 kinds of murine glioma cell lines; VM-Glioma (spontaneously occurring astrocytoma of the VM mouse origin, H-2b), RSV-M (Schmitt-Ruppin Rous sarcoma virus-induced malignant glioma of the C3H/He mouse origin, H-2k), and 203-Glioma (methylcholanthrene-induced ependymoblastoma of the C57BL/6 mouse origin, H-2b). Activated M phi were obtained from peritoneal exudate cells of 4 strains of mice, C57BL/6 (H-2b), C3H/He (H-2k), DBA/2 (H-2d), and BALB/c (H-2d), following intraperitoneal injection of (1) LPS 200 micrograms, (2) BCG 200 micrograms, (3) C.p. 200 micrograms, (4) MDP 350 micrograms, and (5) IFN-gamma 10(3) units, 7 days prior to 20 hr 51Cr release-cytotoxicity assay. Of the various combination of mouse strains and activating agents tested, that of activated M phi of the C3H/He mouse with induction by LPS had the most tumoricidal effect against the glioma cells, which was not MHC restricted. Although LPS-activated M phi underwent marked loss of cytotoxicity within 24 hr following initiation of in vitro culture, this 20 hr pretreatment with IFN-gamma or TNF-alpha inhibited this reduction in tumoricidal effects in a dose dependent fashion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Allele-specific activation of the c-myc gene in an atypical Burkitt's lymphoma carrying the t(2;8) chromosomal translocation 250 kb downstream from c-myc.

The genetic structure and regulation of the c-myc gene was comprehensively studied for the first time in Burkitt's lymphoma with t(2;8) translocation. In a Burkitt's lymphoma cell line, KOBK101, the immunoglobulin kappa-encoding gene on chromosome 2, accompanied by its enhancer, was translocated to the pvt-1 locus located about 250 kb downstream from c-myc on chromosome 8. Only the c-myc allele on the translocated chromosome carried aberrant SalI and KpnI sites in the first intron, so the two c-myc alleles and their transcripts were analyzed separately. The c-myc allele on the untranslocated chromosome conserved the normal c-myc sequence and was transcriptionally silent. In contrast, the c-myc allele on the translocated chromosome was actively transcribed at three- to fivefold higher levels, as compared with non-malignant B-cell lines. Additionally, it carried predominant multiple mutations consisting of 64 nucleotide substitutions, three short deletions, and a one-base insertion, most of which clustered in the first exon and intron. The 24-base deletion in the first intron completely overlapped the binding site of a putative negative transcriptional factor of the 138-kDa phosphoprotein, MIF. Thus, the multiple mutations and the deregulated, allele-specific expression of c-myc were associated with the chromosomal translocation in cis. Together activation by the long-distance immunoglobulin kappa enhancer, and the alleviation of negative regulation by the mutations, seemed to cause the allele-specific activation of c-myc.

Alleles↗
PubMed1993

Weak N activity of En(a-) human erythrocyte membranes.

The propositus's erythrocytes with phenotype En(a-), which was found for the first time in a Japanese family, reacted more weakly with anti-N serum than the ordinary phenotype N erythrocytes. The En(a-) erythrocytes lack the major membrane sialoglycoprotein (glycophorin A) as demonstrated by Bio-Gel 1.5m gel filtration from active sialoglycoproteins, which were isolated from En(a-) erythrocyte membranes by the method of lithium diiodosalicylate (LIS)-phenol extraction. It is suggested from observation via enzyme-linked immunosorbent assay (ELISA) that N activity is derived from the glycophorin B molecule on En(a-) erythrocyte membranes.

Antigens↗
PubMed1993

Cotranscriptional expression of mitochondrial genes for subunits of NADH dehydrogenase, nad5, nad4, nad2, in Marchantia polymorpha.

Three genes for the subunits of the NADH dehydrogenase (nad5, nad4, and nad2) are tandemly clustered on the liverwort mitochondrial genome. Their gene products showed high levels of amino acid sequence identity with the corresponding subunits from higher plant mitochondria (82.8-84.4%), and significant levels of identity with those from liverwort chloroplast (32.0-33.5%). Podospora anserina mitochondria (21.4-45.9%), and human mitochondria (18.4-27.9%). In addition, these three subunits from liverwort mitochondria have conserved amino acid residues in their central regions. The gene nad5 is interrupted by a 672 bp group I intron, while genes nad4 and nad2 are interrupted by group II introns of 899 bp and 1418 bp, respectively. Northern blot analysis using exon-intron specific probes indicated that these three genes are transcribed as a single precursor mRNA of 9.6 kb in length and are processed into mature mRNA molecules in liverwort mitochondria. Several regions of this nad gene cluster are repeated in the liverwort mitochondrial genome.

Amino Acid Sequence↗
PubMed1993

Presence of the factor that inhibits collagen synthesis and stimulates cell proliferation in developing embryonic chick skin extracts.

The effects were studied of the extracts prepared from 10- and 18-day developing chick skins on collagen synthesis and proliferation of the monolayered fibroblasts established from 10-day skin. Cell proliferation was stimulated by both 10- and 18-day skin extracts at the concentration of 3.5 micrograms/ml. Collagen synthesis was suppressed by the treatment of extracts prepared from both 10- and 18-day skins at the concentration of 3.5 micrograms/ml, to a greater extent in 18-day extract. The results indicate that skin extracts possess factors exhibiting both a stimulating effect on cell proliferation and an inhibitory effect on collagen synthesis.

Animals↗
PubMed1993

Accumulation of potassium in scala vestibuli perilymph of the mammalian cochlea.

Movements of potassium (K+) were monitored during perfusion of either the scala tympani (ST) or the scala vestibuli (SV) of the guinea pig cochlea with a solution containing 15 mmol/LK+. A highly asymmetric clearance of K+ was observed, with K+ rapidly being taken up from the ST and allowed to accumulate in the SV. Under some conditions the SV K+ concentration could exceed that in the perfused ST. These observations are believed to result from the distortion of passive K+ diffusion by the high circulating current of K+ that is part of the transduction process. Calculations are presented to demonstrate that circulating fluxes are of sufficient magnitude to generate the results observed. The high rate of circulating K+ current is probably also responsible for the difference in physiologic K+ concentration between the ST and SV, in which the ST perilymph K+ concentration is typically found to be half that of the SV. A clearance of K+ from the ST and its eventual accumulation in the SV could play a role in how the ear responds to abnormal ion concentrations, such as may occur in Meniere's disease. It is proposed that an accumulation of K+ in the SV would result in vestibular dysfunction that might contribute to the vestibular symptoms of the disease.

Animals↗
PubMed1993

Pharmacokinetics of a micronized, poorly water-soluble drug, HO-221, in experimental animals.

N-[[[4-(5-Bromo-2-pyrimidinyloxy)-3-chlorophenyl]amino]carbonyl] - 2-nitrobenzamide (HO-221) is presently under development as an oral anticancer agent with a novel mode of action. However, HO-221 exhibits extremely poor bioavailability after oral administration because it is only slightly soluble in water (0.055 micrograms/ml at 37 degrees C). Our previous study revealed that the micronization of HO-221 to the submicron region improved this oral bioavailability. In this study, the oral pharmacokinetics of this micronized HO-221 was investigated in rats, dogs and monkeys. After oral administration, the agent was moderately absorbed with the Tmax of 6.5-8.0, 17.3-20.0 and 12.0 h, and eliminated with the terminal half-lives of 11.9-15.0, 66.8-78.3 and 42.3 h in rats, dogs and monkeys, respectively. The bioavailability was incomplete (3.7-21.4%). In rats, the plasma concentration did not increase proportionally with increasing oral doses. In dogs, food enhanced the bioavailability 2.2-fold with a standard meal and 3.6-fold with a high fatty meal as compared with fasting conditions.

Administration, Oral↗
PubMed1993

[Separation of glycoproteins from cyst fluids of human ovarian cystomas in benign and their some chemical and serological properties].

Perchloric acid-soluble fractions (PASFs 1-3) which were obtained from cyst fluids of two patients [(Nos. 1 (blood group B) and 2 (blood group A))] with ovarian mucinous cystadenoma and one patient (No. 3 (blood group A)) with ovarian dermoid cyst in benign, were identified as glycoproteins by their chemical composition analyses, respectively. Reactivities of PASFs 1-3 against blood group anti-sera and lectins suggest that these PASFs did not contain MN blood group substances, Vgu glycoproteins and T-active glycoproteins. PASF 1 was separated into 11 fractions by Sephacryl S-500 gel filtration. From chemical composition, SDS-PAGE and serological property of the main fraction (Fr. 5), other one fraction (Fr. 7) and mild acid hydrolysates of these two fractions, it is possible to presume that PASF 1 consisted of a large number of AB-active and fucose-rich glycoproteins with high molecular weights and some of these glycoproteins bear either NeuNAc alpha 2-->6GalNAc (sialyl Tn) group or both sialyl Tn and sialylated T groups.

Adult↗
PubMed1993

[Serological property of perchloric acid-soluble glycoprotein fractions of human meconium].

Perchloric acid-soluble fractions (PASFs) were separated, in yields of 87.0-151.9 mg per 1.0 g of wet meconium sample, from six samples of human meconium, and identified as glycoproteins having 41.2-74.1% carbohydrate by chemical composition analysis. Six PASFs reacted with anti-A, -B, -Lea and -Leb sera, but did not react with anti-M and -N sera. These PASFs alos reacted with many lectins such as DBA, UEA-I, Vicia graminea lectin (VGA), Vicia unijuga lectin (VUA), Con A, WGA, RCA-I, PHA-E, SBA, SJA, and influenza A and B viruses. The serological results show that six PASFs contained VGA or VUA-binding (Vgu) glycoproteins as new oncofetal substances, but did not contain M and N blood group substances.

Amino Acids↗
PubMed1993

Inner ear injury caused by air intrusion to the scala vestibuli of the cochlea.

In a previous communication, we demonstrated that the introduction of air into the scala tympani of the cochlea causes a decrease of cochlear potentials; however, the change in endocochlear dc potential (EP) was mild and the decreased cochlear microphonics (CM) and compound action potentials (CAP) were, at least partially, reversible. In contrast, we have now found that air perfusion (3-60 microliters/min) in the scala vestibuli decreased cochlear potentials more drastically than that in the scala tympani. The change in the EP after air perfusion in the scala vestibuli was characterized by a decrease of the negative EP in response to anoxia. The CM drastically decreased upon the initiation of air perfusion and no recovery was observed after refilling of the perilymph. Histological examination showed collapse of Reissner's membrane in 12 out of 17 cochleas examined. The extent and frequency of the collapse increased with an increase in the amount of air perfused in the scala vestibuli. As the minimal amount of air needed to cause inner ear damage by air perfusion in the scala vestibuli is as small as 3 microliters, it is possible that the prognosis is worse in cases with fistula of the oval window compared to that of the round window area, if the pneumolabyrinth is involved in the pathophysiology of perilymphatic fistula. It is also indicated that air inflation of the middle ear is dangerous in cases with fistula in the oval window.

Air↗
PubMed1993

[Effects of interferon-gamma on cytotoxicity of murine activated macrophages against murine glioma cells].

We studied the effects of mouse IFN-gamma on the cytotoxic activity of murine activated macrophages (M phi) against mouse VM-Glioma cells (H-2b). Activated M phi were obtained from peritoneal exudate cells of mice from four strains, C57BL/6 (H-2b), C3H/He(H-2k), DBA/2 (H-2d), and BALB/c (H-2d), following intraperitoneal injection of (1) LPS 200 micrograms, (2) BCG 200 micrograms, (3) C. parvum 200 micrograms, or (4) MDP 350 micrograms 7 days prior to 20-hr 51Cr release-assay. Of the various combination of mouse strains and activating agents tested, that of activated M phi of the C3H/He mouse with induction by LPS had the most tumoricidal effect against the glioma cells, which was not MHC restricted. Although LPS-activated M phi underwent marked loss of cytotoxicity following initiation of in vitro culture, this 24 hr pretreatment with IFN-gamma inhibited this reduction in tumoricidal effects in a dose-dependent fashion. On the other hand, 24 hr pretreatment of target cells with IFN-gamma did not increase their susceptibility to lysis by activated M phi. These findings suggest that IFN-gamma augments the in vitro tumoricidal activation of M phi; This effect appears to be unrelated to any influence of IFN-gamma on target sensitivity to lysis by macrophages.

Animals↗
PubMed1992

Domains for G-protein coupling in angiotensin II receptor type I: studies by site-directed mutagenesis.

To delineate domains essential for G-protein coupling in angiotensin II type 1 receptor (AT1), we mutated the receptor cDNA in the putative cytosolic regions and determined consequent changes in the effect of GTP analogs on angiotensin II (Ang II) binding and in inositol trisphosphate production in response to Ang II. Polar residues in targeted areas were replaced by small neutral residues. Mutations in the second cytosolic loop, carboxy terminal region of the third cytosolic loop or deletional mutation in the carboxyl terminal tail simultaneously abolished both the GTP-induced shift to the low affinity form and Ang II-induced stimulation of inositol trisphosphate production. These results suggest that polar residues in the second cytosolic loop, the carboxy terminal region of the third cytosolic loop, and the carboxy terminal cytosolic tail are important for G-protein coupling of AT1 receptor.

Angiotensin II↗
PubMed1992

Identification of amino acid residues of rat angiotensin II receptor for ligand binding by site directed mutagenesis.

To determine the specific mechanism of ligand binding to angiotensin (Ang II) receptor AT1, mutagenized rat receptor cDNAs were expressed transiently in COS-7 cells and the effect of the mutations on the binding to peptidic and non-peptidic ligands was analyzed by Scatchard plots. Mutation of Lys199 to Gln in the intramembrane domain strongly reduced the affinity to both [125I] Ang II and [125I]-1Sar, 8Ile-Ang II whereas mutation of two other Lys had little effect, indicating involvement of Lys199 in binding ligands. Replacement of each of four Cys in the extracellular domain markedly reduced binding affinity, indicating the importance of two putative disulfide bridges in the formation of active receptor conformation. Substitution of Asp for Asn in N-glycosylation had no effect on ligand binding or expression of the receptor. These studies indicate mutated receptors are expressed in the plasma membrane and are amenable for further detailed studies.

Angiotensin II↗
PubMed1992

Transfer RNA genes in the mitochondrial genome from a liverwort, Marchantia polymorpha: the absence of chloroplast-like tRNAs.

Twenty-nine genes for 27 species of tRNAs were deduced from the complete nucleotide sequence of the mitochondrial genome from a liverwort, Marchantia polymorpha. One to three species of tRNA genes corresponded to each of 20 amino acids including three species for leucine and arginine, two species for serine and glycine, and one for the rest of the amino acids. Interestingly, all tRNA genes were located in the semicircle of the liverwort mitochondrial genome except for the trnY and trnR genes. The region containing these tRNA genes was originally duplicated, and two trnR genes have diverged from each other. On the other hand, trnY and trnfM are present as two identical copies. The G:U and U:N wobbling between the first nucleotide of the anticodon and the third nucleotide of the codon permit the 27 tRNA identified species to translate almost all codons. However, at least two additional tRNA genes, trnl-GAU for AUY codon and trnT-UGU for ACR codon, are required to read all codons used in the liverwort mitochondrial genome. All of the identified tRNA genes are 'native' in liverwort mitochondria, not 'chloroplast-like' tRNAs as are found in the mitochondria of higher plants. This result implies that the tRNA gene transfer from chloroplast to mitochondrial genome in higher plants has occurred after the divergence from bryophytes.

Base Sequence↗
PubMed1992

Gene clusters for ribosomal proteins in the mitochondrial genome of a liverwort, Marchantia polymorpha.

We detected 16 genes for ribosomal proteins in the complete sequence of the mitochondrial DNA from a liverwort, Marchantia polymorpha. The genes formed two major clusters, rps12-rps7 and rps10-rpl2-rps19-rps3-rpl16-rpl5- rps14-rps8- rpl6-rps13-rps11-rps1, very similar in organization to Escherichia coli ribosomal protein operons (str and S10-spc-alpha operons, respectively). In contrast, rps2 and rps4 genes were located separately in the liverwort mitochondrial genome (the latter was part of the alpha operon in E. coli). Furthermore, several ribosomal proteins encoded by the liverwort mitochondrial genome differed substantially in size from their counterparts in E. coli and liverwort chloroplast.

Amino Acid Sequence↗
PubMed1992

Mechanism of interferon gamma-induced protection of human gliosarcoma cells from lymphokine-activated killer lysis: division of lymphokine-activated killer cells into natural killer- and T-like cells.

The mechanism by which interferon gamma (IFN-gamma) decreases the susceptibility of the established cultured gliosarcoma line Gl-1 to lymphokine-activated killer (LAK) lysis was analyzed. The results of monolayer depletion and lectin-dependent cellular cytotoxicity assays by LAK cells revealed that the resistance to LAK lysis of IFN-gamma-treated Gl-1 cells is manifested at the stage of LAK cell target recognition alone. We have also divided LAK cells into populations of phenotypically natural killer (NK)- and T-like cells with monoclonal antibodies and complement, respectively. We have used these cells to examine the mechanism of IFN-gamma-induced protection of Gl-1 cells from LAK lysis in cold target inhibition, monolayer depletion, and direct binding assays. The results revealed that NK-like cells do not recognize IFN-gamma-treated Gl-1 cells as efficiently as they do untreated targets, whereas T-like cells show the opposite tendency. In conclusion, we have demonstrated that the IFN-gamma induced protection of tumor cells from LAK lysis is predominantly regulated by the target recognition of NK-like cells. On the other hand, IFN-gamma-treated tumor cells may bind to T-like cells but fail to trigger them to initiate further stages for lysis as effectively as NK-like cells.

Cell Division↗
PubMed1992

Mitochondrial DNA of Marchantia polymorpha as a single circular form with no incorporation of foreign DNA.

A cosmid library and physical maps of mitochondrial DNA (mtDNA) from a liverwort, Marchantia polymorpha, were constructed using the cosmid clones. Electrophoresis profile and the physical maps indicated that the liverwort mtDNA was approximately 183 kb long, the smallest among plant mtDNAs, and that it consisted of a single circular molecule. Southern hybridization analysis showed that genes typical to the mitochondrial genome existed in a single copy, and also that there was no incorporation of chloroplast DNA fragments into the mitochondrial genome.

Base Sequence↗