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Biomedical subjects

T Andoh

Publications and source records attributed to T Andoh.

At least 235 records · Page 13Linked to original sources
PubMed1987

Characterization of a mammalian mutant with a camptothecin-resistant DNA topoisomerase I.

DNA topoisomerase I was purified to near homogeneity from a clonal line of human lymphoblastic leukemia cells, RPMI 8402, that is resistant to camptothecin, a cytotoxic alkaloid from Camptotheca acuminata, and compared with that of the parent wild-type cells. As assayed by relaxation of the supercoiled plasmid DNA and by formation of enzyme-linked DNA breaks, the purified enzyme from the resistant cells was shown to be greater than 125-fold as resistant to camptothecin as the wild-type enzyme, comparable to a cellular resistance index of about 300. Therefore, the cellular resistance appears to be due to the resistance of the enzyme. The amount of the immunoreactive enzyme protein in whole extract appeared to be reduced to less than half that of the wild-type enzyme. These results establish that DNA topoisomerase I is the cellular target of camptothecin and that DNA topoisomerase I is essential for the survival of mammalian cells.

Camptothecin↗
PubMed1987

Membrane phospholipid composition and membrane fluidity of human brain tumour: a spin label study.

Membrane fluidity in membrane phospholipids of brain tumours was investigated and compared with those of white and grey matter. Fifteen brain tumours including 5 gliomas, 5 meningiomas and 5 metastatic cancers were examined. These samples were frozen immediately after extirpation in liquid nitrogen. After extraction of total lipids from the tumour tissues, membrane phospholipids were separated and analysed by thin-layer and gas-liquid chromatography. The fluidity of the phospholipid membrane was studied by electron spin resonance (ESR) spectroscopy, using a stearate spin probe. The fatty acid composition of total phospholipid of brain tumours was characterized by an increase in linoleic and arachidonic acids when compared to the control brain. The percentage of palmitoleic acid was higher in gliomas and metastatic tumours than in meningiomas. Furthermore, in the brain tumour tissues, the decreases of phosphatidylethanolamine and phosphatidylserine and the increase of phosphatidylcholine were observed when compared with grey or white matter with the exception of meningioma. There was some difference in phospholipid membrane fluidity between brain tumour and control brain tissue. The order parameter calculated from ESR spectra became higher in the following order: metastatic brain tumour, less than meningioma, less than grey matter, less than glioma, less than white matter. These results suggest that the phospholipid metabolism in the brain tumour is different from that of the normal brain, and this difference may affect the alteration of membrane physical properties which exhibit in part the character of the transformation.

Brain Chemistry↗
PubMed1986

Ultrastructural studies of experimental endotoxin shock in the liver and spleen: therapeutic effects of low-dose heparin on reticuloendothelial disturbances.

To determine the effects of low-dose heparin on the reticuloendothelial system in shock, rats were subjected to intraperitoneal administration of E coli endotoxin. Alterations such as degeneration and necrosis of the Kupffer cells and sinusoidal endothelial cells were observed in the livers of the non-heparin-treated animals 4 hours after the administration of the endotoxin. These changes progressed with time. Kupffer cells in the heparin-treated rats appeared undisturbed up to 8-12 hours post endotoxin challenge. Phagocytosis of cell remained slight in the heparin-treated rats. The mortality rate of the heparin-treated group was 10% with LD50 endotoxin (7.6 mg/kg). The mortality rate of the untreated control group 24 hours after administration was 50%. However, when endotoxin was administered in a dosage of 30 mg/kg (MLD), the mortality rate of the heparin-treated rats was 60%--10% greater than that of controls (P less than 0.05).

Animals↗
PubMed1985

Detection of a countertranscript in promyelocytic leukemia cells HL60 during early differentiation by TPA.

We have isolated several cDNA clones corresponding to the mRNAs expressed during early phase of differentiation of promyelocytic leukemia cells HL60 by TPA. Two interrelated clones were examined, one pHH81 and the other pHH58 possessing inserts of 180 and 730 base pairs, respectively. Northern blot analyses of poly(A) RNAs from induced cells revealed that the clone pHH81 hybridized with 4.3kb RNA, while the clone pHH58 hybridized with 4.3kb and, in addition 0.7kb RNA. Sequence determination of those cDNA clones and extensive Northern blot analyses revealed that the inserts of these clones were derived from 4.3kb mRNAs. 0.7kb RNA was hybridized with only 5' upstream region of the clone pHH58, especially with the strand designed to detect anti-sense RNA. Thus we concluded that 0.7kb RNA is a countertranscript of 4.3kb RNA expressed during early differentiation of HL60 cells.

Base Sequence↗
PubMed1985

Reconstruction of cervical oesophagus with free double-folded intestinal graft.

Reconstruction of cervical oesophagus with free revascularised small intestine is a reliable and effective technique but a common complication is dysphagia. This paper presents a method of splitting the wall of the intestine longitudinally, folding it and suturing it to double the size of the lumen of the reconstructed conduit and to abolish effective peristalsis. The method has proved to be useful in three clinical cases.

Aged↗
PubMed1985

Structural analysis of a developmentally regulated 25-kDa protein gene of Sarcophaga peregrina.

In the previous paper, we described the identification of two abundant mRNAs of Sarcophaga peregrina (flesh-fly) which are selectively expressed in the fat body of middle third instar larvae. One of these mRNAs was found to encode a protein with a molecular mass of about 25,000 (25-kDa protein) when translated in vitro (Tamura, H., et al. (1983) Dev. Biol. 99, 145-151). Present paper reports the nucleotide sequence of a 2.3 kb DNA containing the entire gene for the 25-kDa protein. This gene consisted of four exons and contained an open reading frame for 184 amino acids. A CAT box and a TATA box were found in the 5'-flanking sequence. A poly A addition signal of AATAAA was assigned to the non-coding region in the fourth exon. A sequence having 75% homology with SV40 enhancer core sequence was identified in the non-coding region of the first exon.

Adipose Tissue↗
PubMed1985

Indications for and limitations of coronary thrombolysis.

Experimental studies in dogs with coronary thrombi induced by copper wire confirmed the optimal method of intracoronary thrombolysis, and showed that a high-dose, brief intravenous infusion of urokinase can lead to recanalization. The thrombolytic effects of intracoronary thrombolysin at a rate of 50 IU/kg over 10 minutes are similar to the effects of intracoronary urokinase at a rate 500 IU/kg over 20 minutes. Overall reperfusion rates of 83-86% have been achieved. These results indicate that the thrombolytic effect of thrombolysin is 20 times stronger than that of urokinase. The effect of a brief intravenous infusion of urokinase was less than that of intracoronary urokinase. The reperfusion rate in the same experimental model was 40%. Later, a clinical trial of intracoronary urokinase was performed in 47 patients with acute myocardial infarction who were admitted within 12 hours of the onset of symptoms. In 25 of 33 (75.8%) patients with complete occlusion, selective or ostial infusion of urokinase 500 IU/kg over 20 minutes was successful. When given intravenously, recanalization was achieved in 11 of 15 (73%) patients with complete occlusion who were admitted within 6 hours. Both reperfusion rates were similar except for dosage and the duration of infusion.

Aged↗
PubMed1984

Nucleotide sequence of a cloned cDNA for proopiomelanocortin precursor of chum salmon, Onchorynchus keta.

We have isolated a cDNA clone encoding salmon proopiomelanocortin precursor. Polyadenylated RNA was isolated from pituitary neurointermediate lobes and used to construct a cDNA library. The library was screened with 17 mer of oligodeoxyribonucleotides specific for the hexapeptide sequence in salmon beta-endorphin I, Phe-Met-Lys-Pro-Tyr-Thr at positions 4-9 excluding the third nucleotide. One positive clone, pSSM17 containing an insert of 1303 base pairs (bp) was characterized. Sequence determination revealed that it possessed sequences covering the entire regions encoding ACTH and beta-lipotropin and that the mRNA had the same overall organization as those of other mammalian species, i.e., the following peptide hormones were arranged in order from 5' upstream, ACTH including alpha-melanotropin and corticotropin-like intermediate lobe peptide, beta-lipotropin including gamma-lipotropin, beta-melanotropin and beta-endorphin. Amino acid sequences for putative salmon ACTH, beta-, and gamma-lipotropin were predicted. Comparison of the salmon mRNA sequence with those of mammals showed that the regions of alpha- and beta-MSH are relatively homologous, but other regions are much less so, especially in the 3' nontranslated region where it is much longer and completely heterologous.

Amino Acid Sequence↗
PubMed1984

Molecular cloning and characterization of a cDNA clone for a protein specifically expressed in embryo as well as in a chemically induced pancreatic B cell tumor of rat.

cDNAs were molecularly cloned for proteins specifically expressed in embryo as well as in a chemically induced rat pancreatic B cell tumor in which virally related oncogenes such as v-myc, v-src, v-yes, v-mos and v-kis were previously demonstrated not to be expressed. A plasmid cDNA library consisting of 48,000 independent colonies was constructed from poly(A) containing cytoplasmic RNA isolated from 12 day rat embryo. The library was screened by hybridization with 32p-labelled cDNA synthesized from poly(A) containing RNA of rat pancreatic B cell tumor or normal islet B cells. Two clones were obtained which showed a clearly positive reaction only with tumor probe. Nucleotide sequence of one of them harboring insert of 615 nucleotides was determined and its amino acid sequence of 119 residues was deduced, which showed that the protein encoded by this mRNA is highly basic, basic residues/acidic residues being 1.63.

Adenoma, Islet Cell↗
PubMed1984

Heterogeneity of 3' nontranslated regions in proopiomelanocortin (POMC) precursor mRNA of chum salmon Onchorynchus keta: polymorphism of the gene.

Heterogeneity of salmon pituitary proopiomelanocortin (POMC) mRNA was shown by comparison of the nucleotide sequence of independently isolated cDNA clones encoding POMC, pSSM90, pSSM53 and pSSM17, the last of which was previously characterized. Newly isolated clones pSSM90 and pSSM53 contained inserts of 1228 and 666 base pairs, respectively (excluding poly(A)). Sequence analysis revealed that the former contained sequences coding for the carboxy half of putative corticotropin (ACTH), the whole region of beta-lipotropin (beta-LPH), and the entire 3' nontranslated region, while the latter contained only the 3' nontranslated region. Sequence comparison of the three clones revealed that there are some definite nucleotide changes in the 3' nontranslated regions, i.e., base replacements and base additions at multiple sites, whereas no single change was observed in the coding regions, thus demonstrating heterogeneity and hence polymorphism of the gene in the salmon genome.

Adrenocorticotropic Hormone↗