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Biomedical subjects

T Tsukada

Publications and source records attributed to T Tsukada.

At least 199 records · Page 11Linked to original sources
PubMed1988

Antitumor effect of methylglyoxal bis(3-aminopropylamidinohydrazone), a new inhibitor of S-adenosylmethionine and ornithine decarboxylases, on human erythroid leukemia K562 cells.

Methylglyoxal bis(3-aminopropylamidinohydrazone (MGBA) inhibited S-adenosylmethionine decarboxylase (AdoMetDC) activity competitively with S-adenosylmethionine (AdoMet), showing a Ki value of 2.60 x 10(-5) M. It also inhibited ornithine decarboxylase competitively with ornithine, showing a Ki value of 3.80 x 10(-5) M. MGBA inhibited the growth of human erythroid leukemia K562 cells. Putrescine, spermidine, and spermine concentrations in MGBA-treated cells were depressed to 19%, 36%, and 66% of the values of control cells, respectively.

Adenosylmethionine Decarboxylase↗
PubMed1988

Immunocytochemical investigation of atherosclerotic changes observed in aortocoronary bypass vein grafts using monoclonal antibodies.

The authors have performed immunocytochemical surveys on atherosclerotic changes observed in saphenous vein aortocoronary bypass grafts, comparing the changes occurring in coronary and aortic lesions. The two monoclonal antibodies used in this study were obtained by T. Tsukada. One of them, named HHF35, exhibited specificity to smooth muscle cells; the other, named HAM56, was specific to macrophages. These immunocytochemical studies clearly demonstrated that cells encountered within the fibrous intimal thickening in the vein graft were inevitably smooth muscle cell in origin. Macrophages were seldom seen in the grafts examined. In contrast to vein grafts, macrophages were noted within the intima of all specimens from arterial atherosclerotic lesions obtained from the same patients. These studies suggest a difference in the progression of intimal thickening between the venous graft and the arterial atherosclerotic lesions.

Antibodies, Monoclonal↗
PubMed1988

Purification by affinity chromatography and characterization of porcine liver cytoplasmic polyamine oxidase.

1. Polyamine oxidase was purified from the soluble fraction of porcine liver by more than 70,000-fold to electrophoretic homogeneity using N8-acetylspermidine-Sepharose 4B affinity chromatography. 2. The molecular weight and isoelectric point of this enzyme were 62,000 and pH 4.5, respectively. 3. Optimal pH for the catalytic activity was close to 10.0. 4. The enzyme activity was enhanced by 5 mM dithiothreitol or 5 mM benzaldehyde. 5. Preferential substrates for this cytoplasmic PAO were N1-acetylspermine, N1-acetylspermidine and spermine. 6. Spermidine was not virtually the substrate for this enzyme. 7. The present results suggested the physiological roles of cytoplasmic PAO, being coupled with the reaction of spermidine/spermine N1-acetyltransferase, in recycling the cellular polyamines to putrescine.

Animals↗
PubMed1988

The CGTCA sequence motif is essential for biological activity of the vasoactive intestinal peptide gene cAMP-regulated enhancer.

cAMP-regulated transcription of the human vasoactive intestinal peptide gene is dependent upon a 17-base-pair DNA element located 70 base pairs upstream from the transcriptional initiation site. This element is similar to sequences in other genes known to be regulated by cAMP and to sequences in several viral enhancers. We have demonstrated that the vasoactive intestinal peptide regulatory element is an enhancer that depends upon the integrity of two CGTCA sequence motifs for biological activity. Mutations in either of the CGTCA motifs diminish the ability of the element to respond to cAMP. Enhancers containing the CGTCA motif from the somatostatin and adenovirus genes compete for binding of nuclear proteins from C6 glioma and PC12 cells to the vasoactive intestinal peptide enhancer, suggesting that CGTCA-containing enhancers interact with similar transacting factors.

Base Sequence↗
PubMed1988

Inhibition of mouse skin tumor promotion and of promoter-induced epidermal polyamine biosynthesis by methylglyoxal bis(butylamidinohydrazone).

Effects of methylglyoxal bis(butylamidinohydrazone) (MGBB), a reversible inhibitor of ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (AdoMetDC), on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced increases of ODC and AdoMetDC activities, ODC and mRNA level and polyamine contents in mouse skin were investigated in connection with tumor formation. Formation of papillomas by applications of TPA to 7,12-dimethylbenz[a]anthracene (DMBA)-initiated mouse skin was effectively inhibited by simultaneous topical applications of MGBB, MGBB also dose-dependently inhibited the ability of TPA to induce increases of ODC activity, ODC mRNA level and the accumulation of putrescine and spermidine in mouse skin. Induction of AdoMetDC activity was not affected by the drug. These inhibitory effects of MGBB on ODC induction and tumor promotion were more evident in multiple application experiments than with a single application of the drug.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1988

Expression of adrenocorticotropin-releasing hormone precursor gene in placenta and other nonhypothalamic tissues in man.

Adrenocorticotropin-releasing hormone (CRH) is a peptide originally isolated from the hypothalamus. Immunocytochemical and RIA studies have revealed that CRH-like peptide is also localized in human nonhypothalamic tissues and some tumors. To see if CRH is synthesized in these nonhypothalamic tissues and tumors, we examined preproCRH mRNA in these tissues by Northern blot analysis using a cloned human preproCRH gene as a probe. PreproCRH mRNA was detected in human hypothalamus, cerebral cortex, adrenal gland, placenta, pheochromocytoma, and thymic carcinoid. The content of preproCRH mRNA in placenta was apparently greater than that in the whole hypothalamus.

Cloning, Molecular↗
PubMed1988

Effect of number of elements and size of stimulus field on recordability of pattern reversal visual evoked response.

The interrelationships among amplitude of the pattern reversal visual evoked response (VER), check size (spatial frequency) of the stimulus pattern elements, size of the stimulus field, and number of elements in the stimulus field were investigated. When the stimulus field was smaller than 4.0 degrees X 4.0 degrees, the VER amplitude-check size curve had a high-pass filter shape. When the stimulus field was larger than 5.0 degrees X 5.0 degrees, the curve showed the inverted-U shape. At the largest stimulus field, 12.0 degrees X 12.0 degrees, the curve retained the inverted-U shape, but its peak moved to a larger check size. With smaller check sizes (10 and 20 min), the VER amplitude increased up to a certain stimulus field size and then showed either saturation or a decrease. When the number of elements in the stimulus field was less than 40, the VER amplitude did not increase significantly in all check sizes. Above this number of elements in the field, the amplitude increased linearly until saturation was observed at an element number of 300-400. We concluded that the amplitude of the pattern reversal VER depended strongly on the interrelationship among check size, stimulus field size, and number of elements in the field.

Adult↗
PubMed1988

[Clinical effect of terodiline hydrochloride (TD-758) in patients with urinary disturbances].

We evaluated the efficacy of terodiline hydrochloride (TD-758) in 23 patients with psychosomatic bladder, chronic prostatitis and chronic cystitis. The drug was administered at a dose of 24 mg once a day for 4 weeks. In 78% of the patients the symptoms such as urinary frequency and sense of residual urine improved. Only mild side effects such as thirst were noted. We concluded that terodiline hydrochloride was effective in this trial.

Aged↗
PubMed1987

Identification of a region in the human vasoactive intestinal polypeptide gene responsible for regulation by cyclic AMP.

Transcription of the vasoactive intestinal polypeptide (VIP) gene is regulated by cAMP. To identify the nucleotide sequences in the human VIP gene responsible for this regulation, we constructed chimeric genes containing different portions of the 5'-flanking region of the human VIP gene fused to the structural sequence encoding the bacterial reporter enzyme chloramphenicol acetyltransferase (CAT). The transcriptional activities of the fusion genes introduced into the rat pheochromocytoma cell line PC12 were assayed by measuring CAT activity in the cell lysates. Forskolin, an adenylate cyclase-activating agent, stimulated the expression of VIP-CAT fusion genes. Deletional analysis demonstrated that a region between -86 and -70 nucleotides upstream from the transcriptional origin of the human VIP gene was responsible for stimulation by forskolin. This region was able to confer cAMP-responsiveness to a gene that is not normally regulated by cAMP. Two copies of a 5 base pair motif, 5'-CGTCA-3', are required for activity of the VIP cAMP regulatory region. This motif is also present in the cAMP regulatory region of several other eukaryotic genes.

Acetyltransferases↗