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M Ohta

Publications and source records attributed to M Ohta.

At least 541 records · Page 30Linked to original sources
PubMed1994

The role of cellular transcription factor E2F in the regulation of cdc2 mRNA expression and cell cycle control of human hematopoietic cells.

cdc2 mRNA transcripts were detected in immature bone marrow cells and became undetectable along with differentiation. Peripheral blood resting cells did not express cdc2 mRNA, but it was induced in T-lymphocytes when the cells reentered the cell cycle in response to specific mitogens. In contrast, cdc2 mRNA could not be induced in granulocytes and monocytes even after the culture with the appropriate stimulants. In order to investigate the mechanism of the regulation of cdc2 mRNA expression in hematopoietic cells, we isolated the 5'-flanking sequence of the cdc2 gene and found the putative E2F binding site at the position of nucleotides -124 to -117. The binding of E2F at this region was detected by a gel-retardation assay and DNaseI footprinting in phytohemagglutinin-stimulated T-lymphocytes, which was coincident with the expression of cdc2 mRNA. E2F binding was not observed in both granulocytes and monocytes. Transient chloramphenicol acetyltransferase assay revealed that the region containing E2F binding site had a strong promoter activity, and introduction of the mutation at the E2F binding site resulted in a significant loss of the activity. E2F-1 and DP-1 mRNAs were not detectable in granulocytes, monocytes and resting T-lymphocytes but were induced after the mitogenic stimulation of T-lymphocytes. The induction of E2F activity preceded the appearance of cdc2 mRNA, which is consistent with the role of E2F in the regulation of cdc2 mRNA expression. These results suggest that cdc2 mRNA expression is related to the cell cycling of normal human hematopoietic cells and that E2F plays some roles in the regulation of its expression.

Base Sequence↗
PubMed1994

Rarity of somatic and germline mutations of the cyclin-dependent kinase 4 inhibitor gene, CDK4I, in melanoma.

Evidence from cytogenetics, multipoint linkage analyses of familial melanoma, and loss of heterozygosity studies of familial and sporadic melanomas support localization of a melanoma susceptibility or tumor suppressor gene at chromosomal region 9p21-23. Recently, the inhibitor of cyclin-dependent kinase 4 (CDK4I; also known as p16INK4, multiple tumor suppressor 1, or CDKN2 gene) has been mapped to 9p21 and shown to be mutated or deleted in a large fraction of cell lines derived from many tumor types, including melanoma, suggesting that this gene could be a melanoma suppressor gene. In order to test for somatic mutations in the CDK4I gene in tumors, DNAs from 30 surgically resected melanomas of both cutaneous and uveal origins were sequenced. No mutations were detected in the coding region of the CDK4I gene, while mutations or deletions were detected in 60% (9 of 15) of the cultured melanoma cell line DNAs. Among presumptive familial cases, nine of which were members of families with one or two other documented melanoma cases, no germline mutations were detected by sequence analysis. A deletion in the second exon of the CDK4I gene was found in one germline allele of a familial melanoma patient from a family with eight affected first degree relatives. These results not only support the suggestion that the CDK4I gene is a familial malignant melanoma gene, they also suggest the presence of another suppressor gene locus within 9p21 which is the target of loss of heterozygosity in sporadic melanomas.

Base Sequence↗
PubMed1994

Ciliary neurotrophic factor induced-increase in beta-amyloid precursor protein mRNA in rat C6 glioma cells.

The effect of ciliary neurotrophic factor (CNTF) on beta-amyloid precursor protein (APP) gene expression was investigated in cultured rat C6 glioma cells and human SH-SY5Y neuroblastoma cells. CNTF increased APP mRNA abundance in C6 glioma cells in a dose-dependent manner, with an approximately 3-fold increase in maximum observed after 24 h with a concentration of 1 ng/ml. However, no significant differences in the splicing pattern of the three major isoforms of APP mRNA were apparent between control and CNTF-treated C6 glioma cells. CNTF had no effect on APP mRNA abundance in SH-SY5Y neuroblastoma cells. These findings suggest that CNTF can modulate APP mRNA expression and might affect amyloidogenesis in Alzheimer's disease.

Amyloid beta-Protein Precursor↗
PubMed1994

Cloning and sequencing of the L1 gene of canine oral papillomavirus.

Canine oral papillomavirus (COPV) DNA was isolated from two different sources. One of these DNAs was molecularly cloned and its physical map was determined. Hybridization analyses using subgenomic fragments of bovine papillomavirus type 1 (BPV-1) and human papillomavirus type 16 (HPV16) as probes revealed that the cloned COPV shared moderate homology within the E1 and L1 regions of BPV-1 and HPV16, whereas homology in other regions of BPV-1 and HPV16 was low. The putative L1 gene of COPV was sequenced and several conserved regions, including antigenic epitopes which are common in other known papillomaviruses, were analyzed.

Amino Acid Sequence↗
PubMed1994

A novel dodecadepsipeptide, cereulide, isolated from Bacillus cereus causes vacuole formation in HEp-2 cells.

A HEp-2 cell-vacuolation factor was extracted and purified from the culture supernatant of a Bacillus cereus strain which caused emetic-syndrome food poisoning. The final preparation was chemically pure, and the toxin was named as cereulide. Mass spectrometry, NMR studies and chemical degradation revealed that the cereulide is a cyclic dodecadepsipeptide, (D-O-Leu-D-Ala-L-O-Val-L-Val)3, which is closely related to the potassium ionophore, valinomycin.

Amino Acid Sequence↗
PubMed1994

Leukemic meningitis in a patient with splenic lymphoma with villous lymphocytes (SLVL). Meningitis as a possible initial manifestation of SLVL.

BACKGROUND: Splenic lymphoma with villous lymphocytes (SLVL) is a low grade, non-Hodgkin's lymphoma with a stable or slowly progressive clinical course. To the authors' knowledge, central nervous system involvement has not been described previously in patients with SLVL. METHODS: Morphologic, immunocytochemical, and immunohistochemical analyses were conducted to determine the nature of villous lymphocytes in the peripheral blood, spleen, and cerebrospinal fluid (CSF) of a patient with massive splenomegaly. RESULTS: A diagnosis of SLVL was made, based on tartrate-resistant acid phosphatase-negative peripheral villous lymphocytosis with CD19+, CD20+, HLA-DR+ phenotypes, and the involvement of spleen white pulp with these cells. Mononuclear cells in the CSF showed the same morphologic and immunocytochemical features seen in the villous lymphocytes in the peripheral blood and spleen. Splenectomy and intrathecal chemotherapy were successful in clearing leukemic cells from the CSF. CONCLUSION: In this patient with SLVL in whom leukemic meningitis developed, meningitis was found to be a possible initial manifestation of SLVL.

B-Lymphocytes↗
PubMed1994

Novel retinoic acid, 9-cis retinoic acid, in combination with all-trans retinoic acid is an effective inducer of differentiation of retinoic acid-resistant HL-60 cells.

Recent studies have shown that a high proportion of patients with acute promyelocytic leukemia (APL) achieve complete remission after treatment with all-trans retinoic acid (RA). Nevertheless, despite an initial good response, most patients that received continuous treatment with all-trans RA relapse and develop RA-resistant disease. The 9-cis RA is a high-affinity ligand for retinoid X receptors (RXRs) and also binds efficiently to retinoic acid receptors (RARs); all-trans RA is a ligand for RARs. Both alone are able to induce differentiation of wild-type HL-60 cells. We found that neither all-trans RA nor 9-cis RA (< 2 x 10(-6) mol/L) induced differentiation of RA-resistant HL-60 cells into either mature granulocytes or monocytes. However, morphologic differentiation of the RA-resistant HL-60 cells was induced by 10(-6) mol/L all-trans RA combined with various concentrations (10(-12) to 10(-6) mol/L) of 9-cis RA. Electron microscopic examination also confirmed that the combination of both retinoids induced RA-resistant HL-60 cells to differentiate to mature granulocytes. Functional analysis of differentiation (NBT reduction activity) confirmed the necessity of both analogs to induce differentiation. Also, expression of myeloid-specific differentiation antigens (CD11b and CD14) as well as migration inhibitory factor-related protein (MRP)-8/14 mRNAs were upregulated only in the presence of both retinoids in a dose-dependent manner. In these conditions 3H-thymidine incorporation was inhibited and numbers of viable cells were decreased, suggesting that all-trans RA with 9-cis RA may inhibit cell growth and induce differentiation of RA-resistant HL-60 cells into mature granulocytes. These studies suggest that 9-cis RA in combination with all-trans RA is an effective inducer of RA-resistant HL-60 cells and may have implications for both the biology of retinoids and clinical treatment of RA-resistant acute myelogenous leukemia, including APL patients.

Antigens, Differentiation↗
PubMed1994

C-terminal topology of gastric H+,K(+)-ATPase.

An antibody was prepared against a peptide corresponding to residues 1024-1034 (the putative C-terminus) of the alpha-subunit of hog gastric H+,K(+)-ATPase. The antibody bound to a 95 kDa band of H+,K(+)-ATPase that was solubilized in SDS, but not to that of Na+,K(+)-ATPase. It also bound to products of tryptic digestion that included C-terminal fragments of the H+,K(+)-ATPase alpha-subunit. The same amount of the antibody bound to both intact (tight) and lyophilized (leaky) inside-out gastric vesicles, indicating that its epitope is present on the cytosolic side of the vesicles. This finding was further confirmed by using fluorescence-immunolocalization techniques and streptolysin-O to permeabilize newt oxyntic cells. Stimulation of isolated newt oxyntic cells with dibutyryl cyclic AMP induces fusion of tubulovesicles with the apical membrane, so that the luminal domains of the H+,K(+)-ATPase alpha-subunit directly face the cell-suspension medium. The antibody did not bind to the stimulated intact cell, but bound to cells permeabilized with streptolysin-O, indicating that it binds from the cytoplasmic side to the C-terminus of the H+,K(+)-ATPase alpha-subunit in apical and tubulovesicular membrane, and also that the H+,K(+)-ATPase alpha-subunit has an even number of transmembrane domains.

Amino Acid Sequence↗
PubMed1994

Differential expression patterns of mRNAs for members of the fibroblast growth factor receptor family, FGFR-1-FGFR-4, in rat brain.

We have examined the region-specific expression of mRNAs for four members of rat FGF receptor family, FGFR-1, FGFR-2 FGFR-3, and FGFR-4, in rat brain by in situ hybridization. The FGFR-1, FGFR-2, and FGFR-3 mRNAs were expressed widely but differentially in the brain. However, the FGFR-4 mRNA was not expressed in the brain. The FGFR-1 mRNA was strongly expressed in several regions including the hippocampus, cerebellum, and pedunculopotine tegmental nucleus. The FGFR-2 mRNA expression was high in the choroid plexus, and moderate in the fiber-rich regions (the corpus callosum, external capsule, and internal capsule) and the olfactory bulb. The FGFR-3 mRNA was expressed diffusely in the brain. We have also examined the cellular localization of these mRNAs in the brain. Although the FGFR-1 mRNA was expressed preferentially in neurons, the FGFR-2 and FGFR-3 mRNAs were expressed preferentially in glial cells. The present findings that the FGFR-1, FGFR-2, and FGFR-3 mRNAs were expressed widely but with region- and cell-specificity in the brain indicate that these receptors have different roles in the brain.

Amino Acid Sequence↗
PubMed1994

Characterization of a plasmid-borne and constitutively expressed blaMOX-1 gene encoding AmpC-type beta-lactamase.

A 1954-bp DNA fragment containing the blaMOX-1 gene, identified on a large resident plasmid (pRMOX-1) of Klebsiella pneumoniae NU2936, was sequenced and an open reading frame (ORF) coding for a 390-amino-acid (aa) MOX-1 was found. The total deduced aa sequence of MOX-1 shared considerable homology with that of AmpC-type class C beta-lactamases of Gram- bacteria, especially of Pseudomonas aeruginosa PAO1 [51.3%; 63.8% at the nucleotide (nt) level]. However, the regulatory gene ampR and a 38-bp AmpR-binding region were not present upstream from blaMOX-1, although the expression of P. aeruginosa ampC is directly regulated by AmpR. Possible -35 and -10 regions, a Shine-Dalgarno (SD) sequence and terminators were identified which are peculiar to blaMOX-1. On the other hand, a sequence highly homologous (91.6%) to the region upstream from dhfrX in the In7 integron carried by plasmid pDGO100 was found upstream from blaMOX-1 at nt 1 to 488. No significant difference was detected between the promoter activities of blaMOX-1 in ampD- and ampD+ strains of Enterobacter cloacae, as measured by the chloramphenicol acetyltransferase (CAT) assay. These results clearly show that blaMOX-1 belongs to the group of ampC-related bla genes and that it is expressed constitutively, independently of transcriptional regulators such as AmpR, AmpG and AmpD. Homology analysis among AmpC enzymes or ampC genes implied that integration of the chromosomal ampC gene into a large resident plasmid, followed by transconjugation, was involved in the evolution of blaMOX-1.

Amino Acid Sequence↗
PubMed1994

The capacity of the malate-aspartate shuttle differs between periportal and perivenous hepatocytes from rats.

The capacity of the malate-aspartate shuttle was evaluated in periportal (PP-H) and perivenous subfraction of rat hepatocytes (PV-H). The rate of glutamine production from alanine was 34-fold higher in PV-H than in PP-H. Statistically significant differences between PP-H and PV-H were found for the activities of lactate dehydrogenase and pyruvate kinase but not for the activities of NAD(+)-malate dehydrogenase, aspartate aminotransferase, and mitochondrial alanine aminotransferase. The rate of glucose production from sorbitol and the rate of ethanol utilization were higher in PP-H than in PV-H. In the presence of phenazine methosulfate (PMS), the increments in these rates were significantly greater in PV-H than in PP-H. The capacity of malate-aspartate shuttle in the presence of alanine was significantly higher in PP-H than in PV-H but in the presence of asparagine was similar in PP-H and PV-H. The results suggest that the capacity of malate-aspartate shuttle distributes heterogeneously along liver lobules with the dominance in periportal zone and that the difference of the capacity may result from the difference in the transport of aspartate across the mitochondrial membrane.

Alanine↗
PubMed1994

Immunohistochemical evidence of neurons with GHRH or LHRH in the arcuate nucleus of male mice and their possible role in the postnatal development of adenohypophysial cells.

BACKGROUND: The neonatal administration of monosodium L-glutamate (MSG) has been used in investigations of the possible role of the arcuate nucleus in neuroendocrine regulation during postnatal development. We used this method to examine whether the mouse arcuate contained cell bodies immunoreactive with antisera to growth hormone releasing hormone (GHRH) or luteinizing hormone releasing hormone (LHRH), and whether these hypothalamic peptides affect synthesis and secretion of growth hormone and gonadotropin and the testis. METHODS: The hypothalamus, pituitary, and testes of adult male mice treated with MSG during the neonatal period were fixed in Bouin's fluid or 10% neutral formalin. The hypothalamus was used in immune staining, the pituitary was used in both morphometry and immune staining, and the testis was stained with hematoxylin and eosin. RESULTS: Body weights in control and treated mice were not different. The treated mice had more subcutaneous adipose tissue and a shorter body than the control mice. The testes were heavier in the controls. Many perikarya immunoreactive with antisera to GHRH or LHRH were found in the arcuate nucleus in control mice, but few such perikarya were found in this nucleus in treated mice. The size of the anterior lobe and the number and size of GH cells, follicle stimulating hormone (FSH) cells, and prolactin (PRL) cells in treated mice were less than those of control mice. CONCLUSIONS: GHRH and LHRH neurons in the arcuate nucleus in male mice may cause body and testis weight to increase via GH and LH cells, respectively, in the adenohypophysis during postnatal development. There are some differences in the hypothalamo-pituitary-testis axis of mice and rats.

Adipose Tissue↗
PubMed1994

Portal and gastric mucosal hemodynamics in cirrhotic patients with portal-hypertensive gastropathy.

Controversy exists as to the nature of gastric perfusion in portal-hypertensive gastropathy. To investigate portal hemodynamics and gastric mucosal perfusion in cirrhotic patients with and without portal-hypertensive gastropathy, we subjected 56 cirrhotic patients with portal hypertension to portal vein catheterization, pneumatic pressure sensor technique, duplex sonography and laser Doppler flowmetry. Thirteen patients had portal-hypertensive gastropathy: In 10 it was mild, and in 3 it was severe. The presence of portal-hypertensive gastropathy seemed to be independent of age, sex, cause of cirrhosis or grade of esophageal varices. Portal venous pressure, esophageal variceal pressure, portal venous flow and congestion index in patients with portal-hypertensive gastropathy were not significantly different from the values in those without portal-hypertensive gastropathy. However, portal-variceal pressure gradient (subtracting esophageal variceal pressure from portal venous pressure) (p < 0.01) and the incidence of palisading-type esophageal varices on portography (p < 0.05) was increased in patients with portal-hypertensive gastropathy significantly more than in those without portal-hypertensive gastropathy. In the fundus, gastric mucosal blood flow was significantly higher in patients with portal-hypertensive gastropathy than in those without portal-hypertensive gastropathy, whereas in the corpus and the antrum the values were not significantly different. We suggest that the mucosa of the upper stomach in patients with portal-hypertensive gastropathy is congestive and highly perfused. The pathogenesis of portal-hypertensive gastropathy may be related to both congestion and hyperemia in the upper stomach.

Adult↗
PubMed1994

Tenascin induction in tenascin nonproducing carcinoma cell lines in vivo and by TGF-beta 1 in vitro.

Tenascin, a novel six-armed extracellular-matrix glycoprotein, is expressed in a temporally and spatially restricted pattern during carcinogenesis in association with stromal-epithelial interactions. In this study, we have tested the hypothesis that tenascin expression depends upon the change of the cellular environment from in vitro to in vivo. The distribution and alterations in the expression of tenascin were compared between in vitro and in vivo studies in a variety of human epithelial- and nonepithelial-derived cell lines. When cell lines were transplanted into nude mice, all xenografts induced host-mouse-stroma-derived tenascin. Four carcinoma-derived cell lines and all sarcoma-derived lines, which secreted tenascin in vitro, were found to produce human tenascin after transplantation. Furthermore, three carcinoma-derived cell lines, A431, HEp-2, and MCF7, which did not synthesize tenascin in vitro, did synthesize human tenascin after transplantation. These tenascin nonproducing carcinoma cell lines did not express tenascin mRNA in vitro. The addition of TGF-beta 1 to the culture medium induced the synthesis and secretion of tenascin, but TGF-beta 2 and bFGF were less effective. TGF-beta 1 also induced other extracellular-matrix components, fibronectin and laminin. TGF-beta 1 did not induce tenascin in tenascin nonproducing carcinoma cell lines, such as WiDr and A549, in which human tenascin was not induced after transplantation. We have established an in vitro system in which tenascin is induced by the diffusible factor TGF-beta 1. This system could shed light on the mechanism of induction of human tenascin observed in vivo in tenascin nonproducing carcinoma cell lines.

Animals↗
PubMed1994

A complete culture system for avian transgenesis, supporting quail embryos from the single-cell stage to hatching.

We report here a method to produce quail hatchlings by culture in vitro from the single-cell stage. The culture is composed of three steps. In the first step, the fertilized ovum surrounded by thick albumen obtained from the magnum is cultured for 24 hr at 41.5 degrees C in a tightly sealed 20-ml plastic cup with chicken thin albumen added to the equator level of the ovum (System Q1). In the second step, a quail egg shell, cut horizontally and emptied, is used as a bed shell. After the thick albumen is removed, the embryo with egg yolk is transferred to the bed shell and thin albumen from chicken eggs is added to fill the shell. Then, the embryo is cultured for an additional 52 hr at 37.5 degrees C while being rocked at an angle of 90 degrees at 30-min intervals (System Q2). The embryo is transferred again to a chicken bed shell and cultured at 37.5 degrees C with rocking at a 30-degree angle (System Q3). Just before hatching, the rocking of embryos is stopped. The procedure yielded a hatchability of 25%. For transgenesis, a plasmid construct containing a beta-actin-lacZ hybrid gene (pMiwZ) is microinjected into the ovum at the single-cell stage, which is cultured in vitro for 85-90 hr using Systems Q1 and Q2 consecutively. Seven out of 17 surviving embryos exhibited lacZ gene expression in embryonic tissues as detected by histochemistry. The procedure described here should be highly applicable for the production of transgenic birds.

Actins↗
PubMed1994

n-hexane-induced synthesis of hepatic metallothionein is mediated by IL-6 in mouse.

The mechanism of metallothionein (MT) synthesis in the liver by n-hexane (HX) was examined. The increased synthesis of MT in the liver by HX was inhibited by dexamethasone pretreatment. Serum IL-6 was increased soon after HX injection, reaching a maximum at 8-16 hr, and then decreased, but neither IL-1 nor TNF was increased. The hepatic MT concentration reached a maximum later than did the serum IL-6 concentration, at 2 days after administration. When the MT synthesis induced by HX was inhibited by dexamethasone pretreatment, the concentration of IL-6 in the serum was suppressed to a very low level. Furthermore, the increase in concentration of hepatic MT and plasma fibrinogen was significantly decreased by the anti-mouse IL-6 monoclonal antibody. The concentration of hepatic MT was higher when the concentration of HX in the olive oil of the solution for injection was higher, even when the amount of HX administered was the same. It is suggested that the cytokine(s) is produced by the macrophage and fibroblast through injury and inflammation at the site of administration. These findings suggest that MT synthesis resulting from HX is induced indirectly through cytokine(s) production, especially IL-6.

Animals↗
PubMed1994

Complement-dependent cytotoxic activity of serum mannan-binding protein towards mammalian cells with surface-exposed high-mannose type glycans.

Serum mannan-binding protein (S-MBP), a lectin specific for mannose and N-acetylglucosamine, activates complement through the classical pathway. With the help of complement, S-MBP lyses red blood cells which have been coated with yeast mannan and kills bacteria which have N-acetylglucosamine and/or L-glycero-D-manno-heptose on their core oligosaccharide. In this study, we examined whether mammalian cells, on which S-MBP could bound, are killed by a complement-dependent mechanism. When baby hamster kidney (BHK) cells were treated with an alpha-mannosidase inhibitor, 1-deoxymannojirimycin (dMM), most of the cellular oligosaccharides were transformed from the complex-type to the high mannose-type. S-MBP bound to the dMM-treated BHK cells in the presence of Ca2+, and this binding was eliminated by mannose. When dMM-treated cells, labelled with 51Cr, were incubated with complement, radioactivity was released in a dose-dependent manner by S-MBP and complement. This release was not observed with heat-inactivated complement. These observations suggest that S-MBP is able, with the help of complement, to kill not only exogenous microorganisms but also mammalian cells which have high mannose-type oligosaccharides exposed on their surfaces.

1-Deoxynojirimycin↗