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Biomedical subjects

K Takazawa

Publications and source records attributed to K Takazawa.

At least 55 records · Page 3Linked to original sources
PubMed1994

[Effect of nicardipine cardioplegia on A-V conduction system in coronary bypass surgery].

The effect of diltiazem and nicardipine cardioplegia on A-V conduction system was analyzed in 75 patients undergoing coronary bypass operation. The dose of these drugs into the crystalloid cardioplegia was 10 micrograms/kg in nicardipine group (n = 29) and 100 micrograms/kg in diltiazem group (n = 46). Among these patients, there was no operative death and no patient required IABP after surgery and there was no difference on the post operative CK-MB level, on the cardiac index and on the pulmonary pressure between two groups. The number of patients who had complete A-V block after release of aortic cross clamping was significantly smaller in nicardipine group than in diltiazem group: 45.7% in diltiazem group vs. 6.9% in nicardipine group at 30 minutes and 21.7% vs. 6.9% at 60 minutes. We conclude that the suppressive effect on A-V conduction system was significantly lower in nicardipine cardioplegia than in diltiazem cardioplegia in the patients undergoing coronary bypass operation.

Angina Pectoris↗
PubMed1994

[Reoperation and PTCA after coronary artery bypass graft].

Since 1984, 1410 patients underwent coronary bypass grafting at Juntendo University Hospital. At the primary operation 797 patients had internal thoracic artery (ITA) graft and 613 patients received only saphenous vein graft (SVG). Reoperation was done in one pt. in ITA group and 10 pts. in SVG group. There were 2 deaths (reoperative mortality 18%). Percutaneous Transluminal Coronary Angioplasty to stenotic SVG was applied to 71 lesions in CABG patients. The primary success rate was 81.7% and restenosis rate was 38.9%. Urgent reoperation was performed on 3 pts. who had PTCA to diseased LAD or stenotic SVG to LAD. Reoperation is technically demanding and is associated with high mortality. Balloon angioplasty may provide a suitable alternative. But high restenosis rate (especially acute stenosis) remains a significant problem, particularly in the pts. with diseased LAD or stenotic vein graft to LAD. Reoperation is another option to relieve the ischemic symptoms in pts. with diseased LAD or stenotic vein graft to LAD.

Adult↗
PubMed1993

Inositol 1,4,5-trisphosphate 3-kinase highest levels in the dendritic spines of cerebellar Purkinje cells and hippocampal CA1 pyramidal cells. A pre- and post-embedding immunoelectron microscopic study.

Inositol 1,4,5-trisphosphate 3-kinase (InsP3 3-kinase) plays a crucial role in calcium homeostasis by regulating InsP3 levels. We have reported the highest concentrations of InsP3 3-kinase in the dendrites of cerebellar Purkinje cells and hippocampal pyramidal cells of the CA1 sector of the Ammon's horn. We here investigate its subcellular localization by pre- and post-embedding immunoelectron microscopic study. In both populations of neurons, the major structure expressing a high level of InsP3 3-kinase is the dendritic spines.

Animals↗
PubMed1993

Interaction of calmodulin with a putative calmodulin-binding domain of inositol 1,4,5-triphosphate 3-kinase. Effects of synthetic peptides and site-directed mutagenesis of Trp165.

Recombinant rat brain inositol 1,4,5-triphosphate [Ins(1,4,5)P3] 3-kinase was expressed in Escherichia coli as a beta-galactosidase fusion product. It could be adsorbed onto calmodulin-Sepharose and eluted in Ca(2+)-free medium as a 48-kDa protein. Purification could be achieved in a single step. Molecular evidence for a calmodulin-binding domain on Ins(1,4,5)P3 3-kinase can be shown by the following approaches. (a) Inhibition of Ca2+/calmodulin stimulation by a synthetic peptide based on a candidate calmodulin-binding domain. The inhibition was mimicked by a well-characterized peptide derived from the sequence of smooth muscle myosin light-chain kinase calmodulin-binding site. (b) The construction of two mutants by site-directed mutagenesis of Trp165 to Gly or Arg. Both mutants displayed kinase activity but were no longer Ca2+/calmodulin sensitive, supporting, therefore, the role of Trp165 in calmodulin binding.

Amino Acid Sequence↗
PubMed1993

Lys-197 and Asp-414 are critical residues for binding of ATP/Mg2+ by rat brain inositol 1,4,5-trisphosphate 3-kinase.

Rat brain inositol 1,4,5-trisphosphate (InsP3) 3-kinase A was expressed in Escherichia coli in order to identify the amino acid residues involved in substrate ATP/Mg2+ binding. Two amino acid regions that are conserved in the catalytic domain of InsP3 3-kinase isoenzymes A and B had characteristics consistent with two ATP/Mg(2+)-binding motives. Site-directed mutagenesis was performed on residues Lys-197, Lys-207 and Asp-414 to generate three mutant enzymes, referred to as C5 K197I, C5 K207I and C5 D414N. Comparison of the wild-type and mutant proteins with regard to enzymic activity revealed that C5 K197I exhibited 10% of control enzyme activity, C5 D414N was totally inactive and C5 K207I was fully active. The reduced levels of enzyme activity for C5 K197I and C5 D414N were correlated with an altered ability of the mutant enzymes to bind ATP/Mg2+, as determined by ATP-agarose affinity chromatography. Neither Ca2+/calmodulin binding nor InsP3 binding appeared to be affected. Mutant C5 K207I showed the same characteristics as the wild-type enzyme. Taken together, these results strongly indicated (i) that amino acid residues Lys-197 and Asp-414 are necessary for InsP3 3-kinase activity and form part of the ATP/Mg(2+)-binding domain, and (ii) that amino acid residues Lys-197, Lys-207 and Asp-414 are not involved in either InsP3 binding or enzyme stimulation by Ca2+/calmodulin.

Adenosine Triphosphate↗
PubMed1993

Distribution of the neurons containing inositol 1,4,5-trisphosphate 3-kinase and its messenger RNA in the developing rat brain.

As a result of its interaction with a specific receptor, inositol 1,4,5-trisphosphate (InsP3) mobilizes intracellular calcium. The metabolism of InsP3 is rather complex: InsP3 3-kinase produces Inositol 1,3,4,5-tetrakisphosphate (InsP4), a putative second messenger also involved in the intraneuronal calcium homeostasis. The distribution of the messenger RNA coding for the recently cloned InsP3 3-kinase was studied in the developing rat brain by using oligonucleotides derived from the rat cDNA sequence and in situ hybridization combined with Northern blot analysis. In addition, the locations of the enzyme were determined by immunohistochemistry in combination with Western blot analysis. By Northern blot and Western blot analyses on rat brain, the kinase was not detected in the embryo, was first found slightly at birth, and reached adult levels around 2-3 postnatal weeks. These findings were confirmed in the different positive regions by in situ hybridization conducted at the macroscopic level. At the cellular level, the mRNA was found exclusively in the neuronal populations previously demonstrated in the adult. The levels of transcripts per neuron were however higher in the adult than in the neonate brain. The enzyme mRNA could be detected first at postnatal day 0, (birth, P0) in the perikarya of the cerebellar Purkinje cells, followed at P4 by the hippocampal CA1 pyramidal cells and granule cells of the dentate gyrus and finally, at P9, by a majority of the neurons in the cortical layers II-III and V, especially in the frontal cortex and cingulate cortex; claustrum; caudate, putamen, accumbens, olfactory tubercle and calleja islets; anterior olfactory nucleus; taenia tecta; piriform piriform cortex; dorsolateral septum; bed nucleus stria terminalis; amygdala; hippocampal CA2-4 sectors and subiculum. By immunohistochemistry, the enzyme was initially found in the periphery of the cell bodies of the neonatal neurons; was progressively enriched in the developing dendritic arborization during the first postnatal weeks where it remained exclusively localized in the adult. In conclusion, in the developing brain, InsP3 3-kinase was first detected at birth, and thereafter its concentrations increased to reach adult levels around 2-3 postnatal weeks. At the cellular level, the kinase was exclusively found in the neurons. The small amounts of transcripts found per neuron in the neonate increase during synaptogenesis and the protein became progressively enriched in the developing dendritic arborization, where it is localized in the adult.

Animals↗
PubMed1993

Late results of coronary artery bypass surgery with maximal follow-up of 7 years: analysis of determinants affecting late survival.

A total of 806 primary coronary artery bypass graft operations were performed between January 1984 and December 1989. Excluding eight hospital deaths (1.0%) and three patients lost in follow-up, a total of 795 patients were contracted, with a follow-up rate of 99.6%. The mean follow-up period was 53.6 months, the longest being 92 months. Of the patients 42 died in late follow-up. Malignant neoplasm was the major cause of death (n = 17, 40% of total late deaths), which far exceeded the number of cardiac deaths (n = 6, 14%). The actuarial survival, excluding the initial hospital deaths, was 95% at 5 years and 91% at 7 years by the Kaplan-Meier method. By multivariate logistic analysis, four clinical variables were identified as significant in influencing the late survival, in the following order: (1) presence or absence of diabetes mellitus (P = 0.00008); (2) age > or = 65 years or < 65 years (P = 0.002); (3) left ventricular function with ejection fraction < 45% or > or = 45% (P = 0.014); and (4) use or non-use of left internal mammary arteries to bypass the left anterior descending artery (P = 0.016). Sex (male versus female), severity of anginal symptoms (mild versus severe) and number of diseased vessels (single and double versus triple vessel and left main trunk disease) did not significantly influence the late survival of the patients.

Adult↗
PubMed1993

[Pulse wave velocity, thermography in the diagnosis of arteriosclerosis].

1. Pulse wave velocity (PWV) increased with increasing organic stiffness of the arterial wall mainly caused by arterio-sclerosis and also increasing functional stiffness of the arterial wall mainly caused by elevation of blood pressure. Age related changes in PWV have been recognized in variable countries. The PWV in the ascending aorta calculated by the characteristic impedance (378 +/- 141 cm/sec) was lower than that of conventional measurement in the descending aorta (697 +/- 144 cm/sec). 2. Thermography provide us indirect information of arteriosclerosis through reduction of skin temperature caused by disturbance of blood flow.

Aged↗
PubMed1993

[Immunocytochemical investigations of occluded saphenous vein grafts].

Occluded saphenous vein aorto-coronary bypass grafts were investigated using two types of monoclonal antibodies, specific to either the muscle actin (HHF 35) or the macrophage (HAM 56). The early post operative occlusions of saphenous vein grafts were associated with the deposition of mural thrombi with little intimal proliferation. The late occlusions of saphenous vein grafts were associated with intimal fibrous proliferation without mural thrombus formation. Proliferated smooth muscle cells were a major constituent of intimal fibrous proliferation in both early and late occluded grafts. Macrophages were not detected in both groups. The proliferation of smooth muscle cells in the intima may play a role in the development of late occlusion, rather than the organizational process of accumulated mural thrombi.

Aged↗
PubMed1992

Astrocytic localization of the messenger RNA encoding the isoenzyme B of inositol (1,4,5) 3-kinase in the human brain.

The calcium-mobilizing second messenger inositol 1,4,5-trisphosphate (InsP3) is phosphorylated to inositol 1,3,4,5-tetrakisphosphate, another putative second messenger, through the activity of the enzyme InsP3 3-kinase. The cDNAs encoding two such isozymes have been recently isolated from a human hippocampal cDNAs library. We have previously reported the neuronal localization of the A form (Mailleux et al., Neurosci. Lett., 137 (1992) 69-71) and we here demonstrate the presence of the messenger RNA for the B form in human astrocytes.

Adult↗
PubMed1992

Comparison of neuronal inositol 1,4,5-trisphosphate 3-kinase and receptor mRNA distributions in the human brain using in situ hybridization histochemistry.

The distribution of the messenger RNA coding for the recently cloned inositol 1,4,5-trisphosphate (InsP3) 3-kinase, the enzyme phosphorylating InsP3 to InsP4, was compared to the localizations of InsP3 receptor mRNA in the human brain using in situ hybridization histochemistry and oligonucleotide probes. InsP3 3-kinase and receptor mRNA levels were high in the cerebellar Purkinje cells. They were also observed, to a much lesser degree than in the cerebellum, in the hippocampal CA1 pyramidal cells and dentate gyrus granule cells, in the majority of the cortical neurons and in the striatal medium-sized neurons. Both mRNAs were not detected in the brainstem and in the glial cells.

Adult↗
PubMed1992

Comparison of neuronal inositol 1,4,5-trisphosphate 3-kinase and receptor mRNA distributions in the adult rat brain using in situ hybridization histochemistry.

As a result of its interaction with a specific receptor, inositol 1,4,5-trisphosphate mobilizes intracellular calcium. The metabolism of inositol 1,4,5-trisphosphate is rather complex: inositol 1,4,5-trisphosphate 3-kinase produces inositol 1,3,4,5-tetrakisphosphate, a putative second messenger. In order to elucidate inositol 1,3,4,5-tetrakisphosphate function, a comparative in situ hybridization study of the distributions of inositol 1,4,5-trisphosphate 3-kinase and receptor mRNAs was performed in the adult rat brain using oligonucleotides derived from their cDNA sequences. The neuronal distributions of the mRNA for the receptor were larger than for the kinase. Highest levels of both mRNAs were found in the cerebellar Purkinje cells, where they were enriched in their neuronal perikarya and to a lesser extent in their dendrites. In addition to the cerebellum, mRNAs were mainly detected in the hippocampal pyramidal cells of the CA1 sector of the Ammon's horn and in the granule cells of the dentate gyrus, and also in a majority of the neurons in the cortical layers II-III and V, especially in the frontal cortex and cingulate cortex; caudate-putamen, accumbens, olfactory tubercle and Calleja islets; claustrum; anterior olfactory nucleus; taenia tecta; piriform cortex; dorsolateral septum; bed nucleus stria terminalis; amygdala; hippocampal CA2-4 sectors and subiculum. The inositol 1,4,5-trisphosphate receptor mRNA but not kinase mRNA was found in a majority of the neurons in the thalamus, especially in the parafascicular nucleus; hypothalamus, especially the medial hypothalamus; substantia nigra pars compacta and ventral tegmental area; superior colliculus; lateral interpeduncular nucleus and central gray. Taking into account the limitation in sensitivity of the technique, both mRNAs were not detected in glial cells and in the olfactory bulb; basal nucleus of Meynert, diagonal band nuclei; medial septal nucleus; substantia innominata; globus pallidus; entopeduncular nucleus; substantia nigra pars reticulata; ventral pallidum; subthalamic nucleus; spinal cord and dorsal root ganglia. In conclusion, cerebellum and hippocampus appear to contain almost similar levels of kinase mRNA. This is in contrast to receptor mRNA levels which were at much higher levels in the cerebellum when compared with the hippocampus. For this reason, we have chosen hippocampal CA1 pyramidal cells and dentate gyrus granule cells for studying inositol 1,4,5-trisphosphate 3-kinase function.

Animals↗
PubMed1992

[Cryosurgery for left atrial myxoma with coronary artery bypass grafting].

This is the first report of cryoblasion of atrial myxoma which was performed in conjunction with coronary artery bypass grafting. A 63-year-old man was admitted for left atrial tumor and ischemic heart disease. Following coronary artery bypass grafting and resection of left atrial myxoma, cryosurgery was carried out for the residual tumor on atrial septum and left atrial posterior wall. Ultrasonic cardiogram after 1 year revealed no signs of recurrence. Cryoablasion was effective in preventing the recurrence of atrial myxoma.

Coronary Artery Bypass↗
PubMed1991

Identification of residues essential for catalysis and binding of calmodulin in rat brain inositol 1,4,5-trisphosphate 3-kinase.

In order to identify the amino acid residues involved in calmodulin (CaM) binding and catalytic activity, rat brain inositol 1,4,5-trisphosphate (InsP3) 3-kinase was expressed in Escherichia coli as a beta-galactosidase fusion protein [clone C5; Takazawa, Vandekerckhove, Dumont & Erneux (1990) Biochem. J. 272, 107-112]. Three deletion mutants in the plasmid of clone C5 were generated using convenient restriction enzymes. The results show that the removal of 34 amino acids from the C-terminal end of InsP3 3-kinase resulted in an inactive protein which still interacted with CaM-Sepharose in a Ca2(+)-dependent way. The catalytic domain is thus located at the C-terminal end of the protein. A series of 5' deletion mutants was prepared and used to produce proteins with the same C-terminal end but shortened N-termini, varying in length by over 80 amino acids. Assay of InsP3 3-kinase activity in bacterial extracts indicated that a maximum of 275 amino acids in the C-terminal region may be sufficient for the construction of a catalytically active domain. Affinity chromatography on CaM-Sepharose of 5' and 3' deletion mutants revealed that the sequence stretching from Ser-156 to Leu-189 is involved in CaM binding and enzyme stimulation.

Amino Acid Sequence↗
PubMed1991

Molecular cloning and expression of a new putative inositol 1,4,5-trisphosphate 3-kinase isoenzyme.

A human hippocampus cDNA library in lambda ZAP II was screened by hybridization with a rat brain inositol 1,4,5-trisphosphate (InsP3) 3-kinase cDNA. Two clones (hh6 and hh3) were isolated and sequenced. The insert of clone hh6 was shown to correspond to the 3' end of the coding sequence of 50,000-Mr InsP3 3-kinase (referred to as 3-kinase-A). Sequencing of the clone hh3 insert yielded an open reading frame encoding a 472-amino acid protein with a calculated Mr of 53,451 (referred to as 3-kinase-B). The C-terminal part of 3-kinase-B (residues 187-462) was 68% identical with 3-kinase-A in amino acid sequence. The cDNA of clone hh3 was rescued as a Bluescript plasmid and expressed in Escherichia coli as a beta-galactosidase fusion product. It showed InsP3 3-kinase activity that was stimulated in the presence of Ca2+/calmodulin (more than 7-fold in a crude bacterial lysate from expressed plasmid). Regeneration of InsP3 3-kinase activity after SDS/PAGE identified a major polypeptide (Mr 60,000-65,000). The Km for InsP3 of expressed 3-kinase-B was 1.6 microM. These data provide molecular evidence for the existence of InsP3 3-kinase isoenzymes.

Amino Acid Sequence↗
PubMed1991

Molecular cloning and expression of a human brain inositol 1,4,5-trisphosphate 3-kinase.

A human hippocampus cDNA library was screened by hybridization with a rat brain inositol 1,4,5-trisphosphate (InsP3) 3-kinase cDNA. Sequencing of three overlapping clones identified a 1383 bp open reading frame encoding a 461 amino acid protein with a calculated molecular weight of 50988. The coding amino acid sequence showed an overall 93% similarity with the sequence of rat brain InsP3 3-kinase. The cDNA insert of one isolated partial clone (i.e. hh 26) was in frame with the beta galactosidase fragment fused to it as a Bluescript plasmid; it displayed InsP3 3-kinase activity when expressed in Escherichia coli (E. coli). Biochemical characterization of human brain InsP3 3-kinase by SDS polyacrylamide gel electrophoresis and regeneration of enzyme activity reveals three active fractions with apparent Mr of 58,000-64,000, 45,000-50,000 and 37,000-39,000.

Amino Acid Sequence↗
PubMed1991

Inositol 1,4,5-trisphosphate 3-kinase distribution in the rat brain. High levels in the hippocampal CA1 pyramidal and cerebellar Purkinje cells suggest its involvement in some memory processes.

The distribution of inositol 1,4,5-trisphosphate (InsP3) 3-kinase was studied in the adult rat brain, using polyclonal antibodies raised against the purified 50,000-Da rat brain enzyme by immunohistochemistry and Western blot, in addition to enzymatic assay. Immunohistochemically, the enzyme was detected in neurons, where it was localized in the dendrites and at the periphery of the cell bodies. Using selective toxin lesions, the highest enzyme levels were found in the dendrites of hippocampal CA1 pyramidal cells and in neurons in the dorsal portion of the lateral septum, regions both involved in long-term potentiation; and in the dendrites of Purkinje cell subpopulations in the cerebellum, a region involved in long-term depression. High levels were found in neurons in the cortex; in the anterior olfactory nucleus; in the striatum (caudate, putamen, olfactory tubercle, Calleja islets and accumbens); in the central nucleus of the amygdala; in the hippocampal dentate gyrus and in the subiculum. The enzyme was not detected in other brain regions. By Western blot, a 50,000-Da immunoreactive band was present in the cortex, caudate-putamen and cerebellum. This band was most highly stained in the hippocampus. InsP3 3-kinase activity, stimulated by calcium/calmodulin, corresponded to 6172-2638 pmol of InsP4 produced/min/mg protein in the hippocampus followed by frontal and parietotemporal cortex and cerebellum. This activity was below 400 in the brainstem and spinal cord.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗