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M Tada

Publications and source records attributed to M Tada.

At least 397 records · Page 22Linked to original sources
PubMed1991

Association of increased tumor cell responsiveness to prostaglandin E2 with more aggressive tumor behavior.

Secretion of prostaglandin E2 (PGE2) by cloned variants of QR fibrosarcoma or of Lewis lung carcinoma (LLC) did not correspond with their in vivo aggressive behavior. However, aggressiveness may be influenced by tumor responsiveness to PGE2. Each of the metastatic LLC or progressor QRpP variants was more motile in an in vitro migration model than were either the nonmetastatic LLC or regressor QR variants. One of the two tested progressor QR variants and all of the metastatic LLC variants were also more responsive to PGE2 in their in vitro migration through a membrane than were either regressor QR or nonmetastatic LLC variants. Thus, responsiveness to PGE2 by tumors may regulate the degree of tumor aggressiveness in vivo.

Animals↗
PubMed1990

Co-expression of slow-twitch/cardiac muscle Ca2(+)-ATPase (SERCA2) and phospholamban.

Full length cDNAs encoding both slow-twitch/cardiac (SERCA2) and fast-twitch skeletal muscle (SERCA1) Ca2(+)-ATPases were expressed by transient transfection of COS-1 cells. Studies of the Ca2(+)-dependency of Ca2(+)-transport in microsomes isolated from these cells showed that both isoforms had an affinity for Ca2+ of about 0.2 microM. The Ca2(+)-affinity of SERCA2 was lowered when phospholamban was co-expressed with it, demonstrating that the two proteins interact in this expression system. These studies support the view that phospholamban inhibition accounts for the low Ca2(+)-affinity and low activity of SERCA2 in cardiac muscle sarcoplasmic reticulum.

Adenosine Triphosphatases↗
PubMed1990

Protein-protein interaction of detergent-solubilized Ca2(+)-ATPase during ATP hydrolysis analyzed by low-angle laser light scattering photometry coupled with high-performance gel chromatography.

Protein-protein interaction of detergent-solubilized Ca2(+)-ATPase was examined, employing low-angle laser light scattering photometry coupled with high-performance gel chromatography. When solubilized with octa(ethylene glycol) mono-n-dodecyl ether (C12E8) and chromatographed in the presence of 0.3 mg/ml C12E8, the Ca2(+)-ATPase emerged as a single peak with an intermediate molecular weight between the monomer and the dimer, showing a dissociation-association equilibrium of the two components. In the presence of 50 micrograms/ml phosphatidylcholine and 0.3 mg/ml C12E8 at 0 degrees C, the Ca2(+)-ATPase (0.8 mg) emerged as the two distinct components with molecular weights of 125,000 +/- 2100 (n = 3) and 211 300 +/- 7300 (n = 3), indicating that there was no rapid interconversion between the monomer and the dimer. Under the latter conditions, addition of ATP induced fusion of two components. The apparent molecular weight of the fused peak shifted from the monomer to the dimer as the amount of protein increased. Addition of ADP or adenosine 5'-(beta, gamma-methylene triphosphate), however, did not induce such fusion of the peaks. The ATP-induced fusion of the peaks was not observed either in 5 mM CaCl2, the conditions in which the rate of ATP hydrolysis was extremely slow. Thus, the solubilized Ca2(+)-ATPase underwent a rapid interconversion between the monomer and the dimer during ATP hydrolysis. These results suggest that the protein-protein interaction during ATP hydrolysis is an intrinsic nature of Ca2(+)-ATPase and that such interaction may be important for Ca2+ transport by Ca2(+)-ATPase in the sarcoplasmic reticulum membranes.

Adenosine Triphosphate↗
PubMed1990

Analysis of ras gene mutations in biliary and pancreatic tumors by polymerase chain reaction and direct sequencing.

Ras gene is one of the oncogenes most commonly detected in human cancers and consists of three families (H-ras, K-ras, N-ras) that are converted to active oncogenes by point mutations occurring in codon 12, 13, or 61. The authors analyzed mutations of these codons in 12 extrahepatic bile duct carcinomas, nine gallbladder carcinomas, and 20 pancreatic tumors (18 pancreatic adenocarcinomas and two islet cell tumors) by a method to directly sequence nucleotides, using polymerase chain reaction and a direct sequencing method. Point mutations at K-ras codon 12 were found in all of 18 pancreatic adenocarcinomas and in one bile duct carcinoma, but there were no mutations in the remaining 11 bile duct carcinomas, in all of 9 gallbladder carcinomas, or in two islet cell tumors. A very high incidence of ras gene mutations may be used clinically for the diagnosis of debatable cases of pancreatic adenocarcinoma.

Adenoma, Islet Cell↗
PubMed1990

Cloning and expression of a cDNA encoding mouse kidney D-amino acid oxidase.

A cDNA encoding D-amino acid oxidase (DAO;EC1.4.3.3) has been isolated from a BALB/c mouse kidney cDNA library by hybridization with the cDNA for the porcine enzyme. Analysis of the nucleotide (nt) sequence of the clone revealed that it has a 1647-nt sequence with a 5'-terminal untranslated region of 68 nt, an open reading frame of 1035 nt that encodes 345 amino acids (aa), and a 3'-terminal untranslated region of 544 nt that contains the polyadenylation signal sequence, ATTAAA. The deduced aa sequence showed 77 and 78% aa identity with the porcine and human enzymes, respectively. Two catalytically important aa residues, Tyr228 and His307, of the porcine enzyme, were both conserved in these three species. RNA blot hybridization analysis indicated that a DAO mRNA, of 2 kb, exists in mouse kidney and brain, but not liver. Synthesis of a functional mouse enzyme in Escherichia coli was achieved through the use of a vector constructed to insert the coding sequence of the mouse DAO cDNA downstream from the tac promoter of plasmid pKK223-3, which was designed so as to contain the lac repressor gene inducible by isopropyl-beta-D-thiogalactopyranoside. Immunoblot analysis confirmed the synthesis and induction of the mouse DAO protein, and the molecular size of the recombinant mouse DAO was found to be identical to that of the mouse kidney enzyme. Moreover, the maximum activity of the mouse recombinant DAO was estimated to be comparable with that of the porcine DAO synthesized in E. coli cells.

Amino Acid Sequence↗
PubMed1990

Interaction of RecA protein with pBR322 DNA modified by N-hydroxy-2-acetylaminofluorene and 4-hydroxyaminoquinoline 1-oxide.

Interaction of RecA protein of Escherichia coli with pBR322 DNA modified by N-hydroxy-2-acetylaminofluorene (N-OH-AAF) and 4-hydroxyaminoquinoline 1-oxide (4HAQO) was investigated. RecA protein bound more efficiently to modified DNA than to unmodified DNA as judged by filter-binding and gel electrophoresis assay. The binding of RecA protein with modified DNA resulted in the stimulation of ATPase activity and the activation for RecA protein to stimulate the repressor cleavage. These abilities of RecA protein were increased proportionally to the number of adducts in the plasmid DNA (0-5 adducts). Apurinic and alkylated DNA did not activate RecA protein. We suggest that modification of DNA by N-OH-AAF and 4HAQO provides binding sites for RecA protein and may act as an activation signal for SOS response.

4-Hydroxyaminoquinoline-1-oxide↗
PubMed1990

Structure and expression of the human angiotensinogen gene. Identification of a unique and highly active promoter.

We have isolated the human angiotensinogen gene from a genomic library and determined the exon-intron junction sequences. The gene is 12 kilobases long and consists of five exons interrupted by four introns, as a single copy in the human genome. Of particular interest are the positions of the introns in the human angiotensinogen gene which are identical to those in the highly homologous human alpha 1-antitrypsin and alpha 1-antichymotrypsin genes, as well as rat and mouse angiotensinogen genes. Northern blot analysis showed that human hepatoma cells (HepG2) produce a large amount of angiotensinogen mRNA but not human glioma cells (T98G). To assay the promoter activity, the 1.3-kilobase genomic fragment containing the 5'-flanking region, first exon, and a part of first intron at positions -1222 to +44 was fused upstream to the chloramphenicol acetyltransferase gene, then transfected into HepG2 and T98G cells. The gene sequence was active only in HepG2 cells, suggesting the presence of a functional promoter. Analysis of deletion mutants demonstrated that the 76-base pairs region from -32 to +44 containing the TATA box and first exon is the minimal promoter, whose activity is as high as that of the SV40 enhancer-promoter. Since the basal expression of the human angiotensinogen gene is much higher in HepG2 than T98G cells, these results may reflect cell-specific differences in the gene transcription.

Amino Acid Sequence↗
PubMed1990

Analysis of ras gene mutations in human hepatic malignant tumors by polymerase chain reaction and direct sequencing.

The ras gene is one of the oncogenes most commonly detected in human cancers, and it consists of three families (H-ras, K-ras, N-ras). These genes are converted to active oncogenes by point mutations occurring in either codon 12, 13, or 61. We analyzed mutations of these codons in 23 primary hepatic malignant tumors (12 hepatocellular carcinomas, nine cholangiocarcinomas, and two hepatoblastomas) by a method to directly sequence nucleotides, using polymerase chain reaction and a direct sequencing method. Of 23 hepatic malignant tumors, point mutations at K-ras codon 12 or K-ras codon 61 were found in six of nine cholangiocarcinomas. In contrast, there were no point mutations in any of 12 hepatocellular carcinomas or two hepatoblastomas around codon 12, 13, or 61 of the ras genes. These observations suggest that ras gene mutations are not related to pathogenesis of hepatocellular carcinoma, but play an important role in pathogenesis of cholangiocarcinoma.

Adenoma, Bile Duct↗
PubMed1990

High temperature enhances cytotoxicity of mercury (HgCl2) on HeLa S3 cells.

The combined effect of mercury (HgCl2) and high temperature on the growth and synthesis of nucleic acid and protein, and on the cell cycle of HeLa S3 cells was investigated. The subsequent growth of the cells was dose-dependently inhibited by mercury at 37.2 degrees and 41.2 degrees C. The inhibitory effect of mercury on subsequent growth was enhanced at the higher temperature. IC50 values for DNA and RNA synthesis but not protein synthesis, at 41.2 degrees C, were significantly lower than those at 37.2 degrees C (P less than 0.05, P less than 0.01, respectively). Flow cytometric analysis using synchronous cells indicated the possibility of blocking of cell cycle progression in the early part of S phase by the combined treatment. These results suggest that the cytotoxicity of mercury to cell growth was enhanced at the higher temperature and that this enhancement is related to the increased inhibitory effect of mercury on DNA and RNA synthesis and on the cell cycle at high temperatures.

Cell Cycle↗
PubMed1990

Combined effect of cadmium (CdCl2) and high temperature on HeLa S3 cells.

The combined effect of cadmium (CdCl2) and high temperature on the subsequent growth, the synthesis of nucleic acids and protein, and the cell cycle in HeLa S3 cells was investigated. The subsequent growth rate was depressed by cadmium at 37.1 degrees C. This suppression effect was enhanced at 40.4 degrees C compared with the effect at 37.1 degrees C. The synthesis of DNA, RNA and protein was inhibited at higher temperatures in cultivation without cadmium, and depressed at each temperature in a concentration-dependent manner by the addition of cadmium. The DNA, RNA and protein-IC50 values at 40.4 degrees C decreased compared with the values at 37.1 degrees C. The DNA and RNA-IC50 values were significantly decreased (p less than 0.01, p less than 0.005, respectively) depending on the temperature. After treating the cells with cadmium at 40.4 degrees C, the DNA/BrdUrd distribution showed that the rate of dead cells increased and the rate of the G1/G0 phase decreased. These results indicate that the inhibitory effect of cadmium on the subsequent growth of HeLa S3 cells is enhanced at high temperature and this enhancement is related to the increased inhibitory effect of cadmium on DNA and RNA synthesis at high temperature.

Cadmium↗
PubMed1990

c-myb gene analysis in T-cell malignancies with del(6q).

Three T-cell malignancies with del(6q) were analyzed for karyotypes and alteration of the oncogene c-myb that is assigned to 6q22-q24. Patients were diagnosed as having non-Hodgkin T-cell lymphoblastic lymphoma, adult T-cell leukemia, and acute T-cell lymphoblastic leukemia, and the deletions of chromosome 6 were del(6)(q21q25), del(6)(q21q23), and del(6)(q21) or del(6)(q21q27), respectively. Tumor cell DNAs were obtained from cultured pleural fluid or from fresh peripheral blood and marrow samples and were analyzed by Southern blot hybridization, using c-myb oncogene probes. Rearrangements, deletions, or amplifications were absent in these tumor DNAs, thereby indicating that the del(6q) breakpoint in these T-cell malignancies was located outside of the c-myb gene. Northern blot analysis revealed the elevated expression of c-myb in the non-Hodgkin lymphoma patient, in accord with lineage characteristics.

Adolescent↗
PubMed1990

Clinical assessment of therapeutic effects on cancer using 18F-2-fluoro-2-deoxy-D-glucose and positron emission tomography: preliminary study of lung cancer.

Using positron emission tomography, we studied the tumor uptake of 18F-2-fluoro-2-deoxy-D-glucose (18FDG) in five lung cancer patients before and after anti-cancer therapy (radiotherapy and/or chemotherapy). The tumor uptake of 18FDG was classified as positive and negative; the former, by increasing the uptake of 18FDG with time, and the latter, by decreasing or the constant uptake of 18FDG. Before therapy, all cases tested positive. After therapy, three cases were negative and two cases remained positive. All negative cases corresponded to complete second 18FDG study. Our findings in the 18FDG study correlate with the clinical results. 18FDG is a promising method for assessing therapeutic effects on cancer clinically.

Adult↗
PubMed1990

Use of endoscopic ultrasonography for the diagnosis of colorectal tumors.

Ultrasonographic evaluation of colorectal diseases has been realized by the development of echocolonoscopes. Endoscopic ultrasonography was performed in 90 cases of colorectal tumor, and the diagnostic yields were assessed; the cases included 72 with cancer, 13 with polyp, and 5 with submucosal tumor. With respect to cancer extent, EUS correctly estimated the depth of cancer invasion in 84.9% of 53 cases in which the lesion was appropriately visualized. Paraintestinal lymph node metastasis was detected in 38.1%. EUS was not so successful in the evaluation of polyps, since the histological types could not be differentiated, nor could the focus of cancer in adenoma be demonstrated. EUS was effective in the differential diagnosis of submucosal tumors, since the ultrasonographic features varied by histological types.

Carcinoid Tumor↗
PubMed1990

Immunohistochemical demonstration of carcinogen-DNA adducts in target and non-target tissues of rats given a prostate carcinogen, 3,2'-dimethyl-4-aminobiphenyl.

An immunohistochemical procedure was applied which allows accurate localization of DNA lesions within organs and tissues of rats given 3,2'-dimethyl-4-aminobiphenyl (DMAB) using polyclonal antibodies against DMAB-DNA adducts. Dose-related nuclear staining was observed in organs regardless of DMAB-carcinogenic organotropism. In the male accessory sex organs, the lateral lobe of the prostate, a non-target site, demonstrated a similar staining intensity to that found for the ventral prostate and seminal vesicle, target sites. Orchiectomy and pretreatment with ethinyl estradiol resulted in a moderate to slight decrease in binding in the accessory sex organs. No observable decrease in staining intensity was evident in most organs 168 h after the administration of DMAB. These findings suggest that DNA adduct formation itself is not necessarily sufficient for tumor induction.

Aminobiphenyl Compounds↗
PubMed1990

Different carcinogenic responses in a variety of organs, including the prostate, of five different rat strains given 3,2'-dimethyl-4-aminobiphenyl.

Tumorigenic response in the prostate of F344, ACI, Lewis, CD and Wistar rat strains to 3,2'-dimethyl-4-aminobiphenyl (DMAB) was examined in relation to development of other types of tumors. Rats of each strain aged 6 weeks were divided into two groups receiving DMAB s.c. at a dose of 50 mg/kg body wt once every other week for 10 times, with or without 1 week dietary ethynyl estradiol (EE) pretreatment. The experiment was terminated at week 60, carcinomas of the ventral prostate, all of microscopic size, being respectively found in 50, 17, 21, 15 and 0% of F344, ACI, Lewis, CD and Wistar strain animals treated with EE plus DMAB. The tumor yield correlated well with DMAB-DNA adduct formation. One invasive adenocarcinoma also developed in the periurethral part (occupying both of lateral and dorsal areas) of the prostate. The final survival rates were 46, 24, 65, 4 and 0% in F344, ACI, Lewis, CD and Wistar rats respectively. DMAB administration without EE pretreatment resulted in similar incidences of prostate tumors and mortalities. Tumors arose in greater than 14 different sites with strain dependency, lesions predominating in the skin/subcutis of ACI and F344, preputial gland of F344, urinary bladder of ACI, and mammary glands of CD rats respectively. Consideration of mortality and the relative incidence of prostate cancer and other types of tumors indicates the F344 rat strain to be the most appropriate for investigation of DMAB prostate carcinogenesis.

Aminobiphenyl Compounds↗
PubMed1990

Gene expression of D-amino acid oxidase in rabbit kidney.

Although D-amino acid oxidase (DAO) [EC 1.4.3.3] activity in rabbit kidney extract was undetectable, protein immunoreactive toward rabbit anti-pig kidney DAO antiserum and RNAs that hybridized with fragments of human and pig DAO cDNAs were detected distinctly in the rabbit kidney. A cDNA clone, RD22, was isolated from the rabbit kidney cDNA library by hybridization with a fragment of human DAO cDNA. Analysis of the nucleotide sequence revealed a 2,018 nucleotide sequence encoding a protein consisted of 347 amino acids. The number of amino acid residues was identical with those of human and pig DAOs, and the amino acid sequence showed 80 and 83% identity with pig and human DAOs, respectively. RNAs that hybridized with RD22 DNA fragment also existed in rabbit kidney, and their sizes were the same as those of the RNAs detected with the human and pig DAO cDNA fragments. RD22-derived protein was hardly synthesized by an in vitro expression system. However, a cDNA fragment lacking most of the 5'-untranslated region and its mutants containing base changes around the initiation codon did direct protein synthesis. Moreover, the protein derived from the partial cDNA fragment containing a large part of the coding region sequence showed immunoreactivity toward anti-pig DAO antiserum. The results suggest that one of the causes of the very poor synthesis of DAO protein in rabbit kidney is translational suppression in the synthetic process.

Amino Acid Sequence↗
PubMed1990

Polymorphonuclear leukocytes induced vasoconstriction in isolated canine coronary arteries.

To assess how polymorphonuclear leukocytes (PMNs) act on coronary vasoactivity, we measured the changes in isometric tension of isolated rings of canine coronary arteries upon addition of autologous PMNs to organ chambers in which the rings were suspended. When PMNs isolated by the colloidal polyvinylpyrrolidone-coated silica (Percoll) gradient method were added to the chambers, ring preparations of left circumflex coronary arteries developed isometric tension. The increase in tension was dependent on the amount of PMNs (1 X 10(4) to 5 X 10(6) cells/ml). Maximal tension obtained by an optimal amount of PMNs (5 X 10(5) cells/ml) was almost comparable to that produced by prostaglandin F2 alpha (5 microM). Integrity of endothelial cells was not disrupted after the addition of PMNs because the developed tension could be reversed by the addition of acetylcholine in an endothelium-dependent manner. Mechanical rubbing of endothelium abolished the PMN-induced vasoconstriction, which was regained by placing an endothelium-unrubbed ring inside a rubbed ring ("sandwich preparation"). When PMN suspensions were pretreated with 5-lipoxygenase inhibitors of arachidonate, PMN-induced vasoconstriction was greatly suppressed, although the pretreatment of vascular preparations did not alter the development of isometric tension. These findings indicate that PMNs induce the contraction of coronary arterial rings in the presence of intact endothelial cells. The mechanism by which PMNs induce the contraction is the release of vasoconstrictive substances by metabolic interaction between PMNs and endothelial cells. Vasoconstrictive substances produced by the PMN-endothelial system, such as 5-lipoxygenase metabolites through a "leukotriene A4 steal" mechanism, may contribute to the contraction of vascular smooth muscle.

Animals↗