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Biomedical subjects

Y Fukumoto

Publications and source records attributed to Y Fukumoto.

At least 109 records · Page 6Linked to original sources
PubMed1991

Electrocardiographically and symptomatically silent myocardial ischemia during exercise testing.

Certain patients with coronary artery disease (CAD) may have neither ST depression nor chest pain during exercise despite the presence of myocardial ischemia. The frequency and characteristics of such electrocardiographically and symptomatically silent ischemia were studied in 171 patients with both angiographically documented CAD and scintigraphically documented ischemia. Fifty-six (33%) of 171 patients had neither ST depression nor chest pain (Group N), and 115 (67%) had ST depression and/or chest pain (Group P). The two groups were similar with respect to age, gender, the prevalence of prior infarction, and peak systolic blood pressure. Group N patients, however, had a higher mean peak heart rate and rate-pressure product, less severe scintigraphic ischemia, a lower lung thallium-201 uptake, and a smaller number of diseased vessels. Stepwise discriminant analysis showed a history of effort angina, lung thallium-201 uptake, and scintigraphic severity of ischemia to be significant discriminators between Groups N and P. In conclusion, electrocardiographically and symptomatically silent ischemia may be common during exercise in patients with CAD, and less severe ischemia may be one of important determinants.

Coronary Angiography↗
PubMed1990

Comparison of the mode of action of ras p21 with those of protein kinases A and C in the stimulation of gene expression in NIH/3T3 cells.

To compare the mode of action of ras p21 with those of protein kinases A and C in the regulation of gene expression in NIH/3T3 cells, we investigated the transcriptional activity of various enhancer/promoters and enhancer motifs in the cells transfected with the c-Ha-rasva112 complementary DNA (cDNA). The results indicate that the c-Ha-rasva112 protein stimulates the enhancer/promoters of the c-fos gene, the metallothionein IIA gene, the simian virus 40 (SV40) virus genome and the Rous sarcoma (RS) virus genome, and the serum-response element and the 12-O-tetradecanoylphorbol-13-acetate (TPA)-response element in a manner independent of protein kinases A and C in NIH/3T3 cells.

Animals↗
PubMed1990

Activation of the c-fos serum-response element by the activated c-Ha-ras protein in a manner independent of protein kinase C and cAMP-dependent protein kinase.

12-O-Tetradecanoylphorbol-13-acetate (TPA) activated the c-fos gene enhancer linked to the chloramphenicol acetyltransferase or luciferase reporter gene in the wild type PC-12 cells but not in the variant PC-12 cells that originated from the wild type cells. Transfection of the c-Ha-rasval12 complementary DNA (cDNA) or addition of dibutyryl cAMP to the wild type PC-12 cells as well as to the variant PC-12 cells activated the c-fos gene enhancer. Prolonged treatment of the wild type PC-12 cells with phorbol-12,13-dibutyrate caused down-regulation of protein kinase C. In these cells, TPA did not stimulate the c-fos gene enhancer any more, but transfection of the c-Ha-rasval12 cDNA still stimulated the c-fos gene enhancer to the same extent as induced in the control cells. Transfection of the c-Ha-rasval12 cDNA or addition of TPA to the wild type PC-12 cells stimulated the serum-response element but not the cAMP-response element. Dibutyryl cAMP stimulated both the serum-response element and the cAMP-response element in the wild type PC-12 cells. These results indicate that the c-Ha-rasval12 protein activates the serum-response element, but not the cAMP-response element in the c-fos gene enhancer, and that the signal pathway from the c-Ha-rasval12 protein to the c-fos serum-response element is independent of protein kinase C and cAMP-dependent protein kinase.

Blotting, Western↗
PubMed1990

SPECT imaging with Tl-201 and Ga-67 in myocardial sarcoidosis.

Two patients with myocardial sarcoidosis are presented, both of whom underwent SPECT imaging with Tl-201 and Ga-67. The first had Ga-67 myocardial uptake with a Tl-201 defect, which disappeared with corticosteroid therapy. The second had multiple Tl-201 defects without Ga-67 uptake, which persisted despite corticosteroid therapy. Therefore, the combination of Tl-201 and Ga-67 imaging may be useful for recognizing myocardial sarcoidosis and for predicting the response to corticosteroid therapy.

Adrenal Cortex Hormones↗
PubMed1990

Activation of the serum-response and TPA-response elements by expression of the v-abl protein: comparison of the mode of action of the v-abl protein with those of protein kinase C, cyclic AMP-dependent protein kinase, and the activated c-raf protein.

In the present study, we have compared the mode of action of the v-abl protein in the regulation of gene expression with those of serine/threonine protein kinases such as protein kinase C, cyclic AMP-dependent protein kinase, and the activated c-raf protein, by measuring the transcriptional activity of the serum-response element, the 12-O-tetradecanoylphorbol-13-acetate (TPA)-response element, and the cyclic AMP-response element in NIH3T3 cells transfected with the v-abl gene. The results indicate that the v-abl protein stimulates the serum-response element and the TPA-response element, but not the cyclic AMP-response element, in a manner similar to that of the activated c-raf protein, but different from those of protein kinase C and cyclic AMP-dependent protein kinase.

Blood Physiological Phenomena↗
PubMed1990

Molecular cloning and characterization of a novel type of regulatory protein (GDI) for the rho proteins, ras p21-like small GTP-binding proteins.

We have recently purified to near homogeneity a novel type of regulatory protein for the rho proteins, ras p21-like small GTP-binding proteins, from bovine brain cytosol. This regulatory protein, named GDP dissociation inhibitor for the rho proteins (rho GDI), regulates the GDP/GTP exchange reaction of the rho proteins by inhibiting the dissociation of GDP from them, and the subsequent binding of GTP to them. In the present studies, we have isolated the cDNA of rho GDI from a bovine brain cDNA library using oligonucleotide probes designed from the partial amino acid sequences of the purified rho GDI and determined its complete nucleotide and deduced amino acid sequences. The cDNA contains an open reading frame encoding a protein of 204 amino acids with a calculated Mr value of 23,421. This Mr value is similar to those of the purified rho GDI estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and sucrose density gradient ultra-centrifugation, both of which are about 27,000. The rho GDI cDNA is expressed in Escherichia coli and COS7 cells and the encoded protein exhibits rho GDI activity. The 1.9-kilobase rho GDI mRNA corresponding to the isolated cDNA is detected in various rat tissues by Northern blot analysis. Hydropathy analysis indicates that rho GDI is overall hydrophilic except for one hydrophobic region. Computer homology search has revealed that rho GDI is a novel protein that does not share a high amino acid sequence homology with any known protein.

Amino Acid Sequence↗
PubMed1989

Activation of the serum response element and 12-O-tetradecanoylphorbol-13-acetate response element by the activated c-raf-1 protein in a manner independent of protein kinase C.

Transfection of the cDNA encoding the activated c-raf-1 protein or addition of 12-O-tetradecanoylphorbol-13-acetate (TPA) or dibutyryl cAMP to NIH/3T3 cells activated the c-fos gene enhancer linked to the chloramphenicol acetyltransferase or luciferase reporter gene. Prolonged treatment of NIH/3T3 cells with phorbol 12,13-dibutyrate caused down-regulation of protein kinase C. In these cells, addition of TPA did not stimulate the c-fos gene enhancer any more, but transfection of the c-raf-1 cDNA or addition of dibutyryl cAMP still stimulated the c-fos gene enhancer to the same extent as those induced in the control cells. Transfection of the c-raf-1 cDNA or addition of TPA to NIH/3T3 cells stimulated the serum response element and TPA response element but not the cAMP response element. In contrast, addition of dibutyryl cAMP to NIH/3T3 cells stimulated the cAMP response element but not the serum response element or TPA response element. These results indicate that the activated c-raf-1 protein stimulates the serum response element and TPA response element in a manner independent of protein kinase C and cAMP-dependent protein kinase. Since the c-fos gene enhancer has been shown to contain the serum response element and cAMP response element, it is most likely that the c-raf-1 protein is involved in the regulation of c-fos gene expression through the serum response element.

Animals↗
PubMed1989

Molecular genetic analysis of the regulatory and catalytic domains of protein kinase C.

We have constructed the expression plasmids harboring protein kinase C (PKC) mutant cDNAs with a series of deletions in the PKC coding region. These plasmids were transfected into COS7 cells to characterize the PKC mutants. Immunoblot analysis using the anti-PKC antibody identified proteins with the Mr values expected from the PKC mutant cDNAs in the extracts from COS7 cells. The wild-type PKC, when expressed in COS7 cells, conferred increased phorbol ester binding activity on intact cells; but the PKC mutants with the deletion around the C1 region did not show this activity. The wild-type PKC showed protein kinase activity dependent on phospholipid, Ca2+, and phorbol ester, whereas these PKC mutants exhibited protein kinase activity independent of the activators in a cell-free system. A PKC mutant cDNA with the deletion in the C2 region gave increased phorbol ester binding activity. Protein kinase activity of this mutant was much less dependent on Ca2+ compared with the wild-type PKC. A PKC mutant cDNA with the deletion in the C3 region conferred increased phorbol ester binding activity, but neither activator-dependent nor -independent protein kinase activity. These results indicate that elimination of the C1 region of PKC gives rise to constitutively active PKC independent of phospholipid, Ca2+, and phorbol ester and that the C1-C3 regions play distinct roles in the regulatory and catalytic function of PKC. In another series of experiments, transfection of some PKC mutant cDNAs with the deletions around the C1 region into Chinese hamster ovary and Jurkat cells activated the activator protein-1-binding element or the c-fos gene enhancer linked to the chloramphenicol acetyltransferase reporter gene in the absence of phorbol ester. Microinjection of these constructs into Xenopus oocytes induced initiation of germinal vesicle breakdown, indicating that they stimulated the PKC pathway in vivo. Thus, the phorbol ester-independent PKC mutant cDNAs could be a powerful tool to investigate the transmembrane signaling pathway mediated by PKC.

Amino Acid Sequence↗
PubMed1989

Two types of protein kinase C with different functions in cultured rabbit aortic smooth muscle cells.

Incubation of cultured rabbit aortic smooth muscle cells (SMC) with phorbol-12, 13-dibutyrate (PDBu) for 48 h caused the down-regulation of protein kinase C (PKC) to the level of 30-40% of that in the control cells. The proliferative and antiproliferative actions of PKC were abolished in parallel with the loss of the down-regulation-sensitive component of PKC, but the inhibitory actions in the whole blood serum (WBS)-induced phospholipase C (PLC) reactions and intracellular Ca2+ mobilization were not affected. Immunoblot analysis with specific monoclonal antibodies against three PKC isozymes (type I, II and III) revealed that only the type III isozyme was detected in rabbit aortic SMC and that this isozyme completely disappeared after the incubation with PDBu. These results indicate that the type III isozyme is responsible for the proliferative and antiproliferative actions and suggest that the unidentified isozyme(s) is involved in the inhibitory actions in the WBS-induced PLC reactions and intracellular Ca2+ mobilization in rabbit aortic SMC.

Animals↗
PubMed1989

Import and processing of precursor to mitochondrial aspartate aminotransferase. Structure-function relationships of the presequence.

The precursor protein of pig mitochondrial aspartate aminotransferase (pre-mAspAT) contains a 29-residue presequence (Joh, T., Nomiyama, H., Maeda, S., Shimada, K., and Morino, Y. (1985) Proc. Natl. Acad. Sci. U. S. A. 82, 1-5). Pre-mAspAT produced in an in vitro transcription and translation system was avidly imported into pig and rat liver mitochondria to be processed to the mature form of the enzyme. The pre-mAspAT was also processed to the mature form upon incubation with mitochondrial extracts. We synthesized precursor proteins with alterations within the presequence and compared quantitatively the effects of these mutations on the rates of both import and processing. Single and multiple substitutions of four basic residues with neutral amino acids at positions 5, 8, 18, and 28 showed that each residue contributes differentially to import and processing. Substitutions of His5 and Arg8 with glycines abolished the import activity but did not appreciably affect the rate of processing. Substitution of Arg28 with leucine at the position adjacent to the cleavage site seriously impaired the processing without appreciably affecting the rate of import. Analysis of deletions revealed that the amino-terminal region from position 2 to 8 was essential for both the import and processing. Thus the positive charges in the amino-terminal region are critical for import while the amino-terminal peptide segment and the cleavage site region appear to be requisite for recognition by a processing protease.

Amino Acid Sequence↗
PubMed1989

cDNA cloning and expression of pig cytosolic aspartate aminotransferase in Escherichia coli: amino-terminal heterogeneity of expressed products and lack of its correlation with enzyme function.

A full-length cDNA encoding the pig cytosolic aspartate aminotransferase (EC 2.6.1.1) (cAspAT) was constructed from two overlapping cDNA clones. One clone (Lm pcAAT-8) isolated from a lambda gt10 pig heart cDNA library contained a 3' untranslated sequence, a poly(A) segment, and a part of the coding region for amino acid positions 127-412. Another clone (Lm pcAAT-107) isolated from a lambda gt10 primer extension library contained the coding region for amino acid positions 1-148 and a 5' untranslated sequence. Rejoining of the cDNA inserts of the two clones and recloning into pUC18 gave rise to a cDNA covering an entire coding sequence for pig cAspAT mRNA. Insertion into pKK223-3 yielded an expression plasmid, ppcAAT200. Escherichia coli JM105 cells transfected with ppcAAT200 overproduced pig cAspAT to an extent of about 3% of the total cellular soluble proteins. The expressed product was indistinguishable from the alpha subform of cAspAT isolated from pig heart in terms of specific activity, absorption spectra, molecular size, crystalline form, and immunological reactivity with anti pig cAspAT antibody. Compared with the amino-terminal sequence (Ala-Pro-Pro-) reported for pig heart cAspAT, the recombinant pig cAspAT showed heterogeneity in the amino-terminal sequence: Ala 1 (26%), Pro2 (54%), and Pro3 (19%). Construction of a mutant cAspAT with deletion of residues 1-3 and its comparison with the wild-type enzyme revealed that loss of the three amino-terminal residues does not affect the catalytic activity and structural integrity of the enzyme.

Amino Acid Sequence↗
PubMed1989

A new therapeutic trial of secretin in the treatment of intrahepatic cholestasis.

Many animal experiments have been studied on the choleretic effects of secretin. We intended to estimate secretin choleresis in human (15 patients) who had received PTCD or T-tube insertion into the common bile duct. Based upon these data of secretin and choleresis, secretin was administered to 11 patients with prolonged jaundice due to intrahepatic cholestasis in order to evaluate this as a new therapy for intrahepatic jaundice. As controls, eleven patients with intrahepatic cholestasis treated with steroid hormones and/or phenobarbital were used. In all cases with biliary drainage, secretin produced a remarkable choleretic effect with a high concentration of bicarbonate. In 9 out of 11 patients with intrahepatic cholestasis who were treated with secretin, levels of serum bilirubin decreased linearly and other liver function tests returned to the normal range. The mean values of T1/2 (number of days required for reduction by half) of serum bilirubin in 9 effective cases to secretin was 10.8 days. On the other hand, that in 11 effective cases treated with steroid hormones and/or phenobarbital was 23.2 days. These results suggest that secretin therapy may be an effective treatment for intrahepatic cholestasis.

Adult↗
PubMed1989

Patent ductus arteriosus with Eisenmenger's syndrome detected by first-pass study.

The case of a 20-year-old man with patent ductus arteriosus complicated with Eisenmenger's syndrome is described. Radionuclide angiocardiography characterized the abnormal pattern of blood flow through the central circulation to establish a diagnosis of patent ductus arteriosus with a significant right-to-left shunt, which had not been indicated by other clinical findings.

Adult↗
PubMed1988

Independent inhibition of DNA synthesis by protein kinase C, cyclic AMP and interferon alpha/beta in rabbit aortic smooth muscle cells.

In quiescent cultures of rabbit aortic smooth muscle cells, whole blood serum-induced DNA synthesis was inhibited markedly by protein kinase C-activating 12-O-tetradecanoyl-phorbol-13-acetate (TPA) and phorbol-12, 13-dibutyrate (PDBu), cyclic AMP-derivatives, such as dibutyryl cyclic AMP (Bt2cAMP) and 8-bromo-cyclic AMP, and interferon alpha/beta. Neither TPA nor interferon alpha/beta elevated the cellular cyclic AMP level. Neither Bt2cAMP nor interferon alpha/beta induced the phospholipase C-mediated hydrolysis of phosphoinositides. The down-regulation of protein kinase C by prolonged treatment with PDBu abolished the antiproliferative action of TPA but did not affect that of Bt2cAMP or interferon alpha/beta. TPA and Bt2cAMP inhibited the serum-induced DNA synthesis when added within 12 h after the addition of the serum, while interferon alpha/beta was active only when added within 6 h. These results suggest that there are at least three independent signaling systems, protein kinase C- and cyclic AMP-mediated systems and an unidentified system for interferon alpha/beta, which are involved in the antiproliferative mechanisms in rabbit aortic smooth muscle cells.

Alprostadil↗