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Biomedical subjects

I Kubota

Publications and source records attributed to I Kubota.

At least 91 records · Page 5Linked to original sources
PubMed1991

Signal-averaged body surface mapping for the assessment of low-amplitude potentials. Relation between ventricular depolarization and repolarization in normal subjects.

To examine the relation between ventricular depolarization and repolarization, body surface isopotential maps at the end of the QRS complex were studied in 32 normal subjects using a signal-averaged body surface mapping system. The number of beats averaged was 96-154 (mean 126.2). In this study, there were 8 types of isopotential map patterns at the end of the QRS complex. Mean +/- SD of QRS duration, appearance time of repolarization, and disappearance time of depolarization were 82.0 +/- 8.7 msec, 71.8 +/- 10.5 msec, and 79.7 +/- 9.4 msec, respectively. Time duration of overlapping depolarization and repolarization was 8.6 +/- 6.4 msec. The early repolarization was widely distributed on the left anterior chest and the upper sternal region. These results demonstrated the difference between the appearance time of repolarization and the disappearance time of depolarization for each lead. We concluded that it is difficult to evaluate ECG waves in the terminal portion of the QRS complex with the dipolar theory only.

Adolescent↗
PubMed1991

Relation between the incidence of arrhythmias and ischemic ST-segment depression during dipyridamole electrocardiography test in patients with coronary artery disease.

To examine the incidence of arrhythmias in dipyridamole infusion and the relation between dipyridamole-induced arrhythmias and ST-segment depression, dipyridamole electrocardiography tests were performed on 100 patients with coronary artery disease. Dipyridamole was infused at a rate of 0.568 mg/kg for 4 min, and 87-lead body surface mapping was performed to determine ischemic ST-segment depression. Positive ischemic response was defined as greater than or equal to 0.10 mV horizontal or downsloping ST-segment depression below the baseline, lasting 80 msec after the J point. Arrhythmias were observed by continuous electrocardiographic monitoring using a CM-5 lead electrocardiography. With respect to ventricular premature contractions (VPC), a group of patients with previous myocardial infarction (MI group) had a significantly higher incidence than a group of patients without previous myocardial infarction (non-MI group) before (16.7% vs. 1.7%, p less than 0.01) and after (38.1% vs. 3.4%, p less than 0.005) the dipyridamole infusion. The incidence of supraventricular premature contractions (SVPC), however, was not significantly different between the MI and non-MI groups. A group of patients with positive ischemic response had a significantly higher incidence of SVPC after the dipyridamole infusion than a group of patients with negative ischemic response (p less than 0.005). However, there was no significant difference in the incidence of VPC between the negative and positive ischemic response groups. These results suggest that dipyridamole-induced VPC is not always associated with ischemic ST-segment depression, but dipyridamole-induced SVPC is associated with dipyridamole-induced ischemic ST-segment depression in patients with coronary artery disease.

Adult↗
PubMed1991

A variety of Mytilus inhibitory peptides in the ABRM of Mytilus edulis: isolation and characterization.

1. Five species of Mytilus inhibitory peptides, MIP1-5, were isolated from acetone extracts of the anterior byssus retractor muscle (ABRM) of Mytilus edulis. MIP1 and MIP2 were shown to be S2-MIP and A2-MIP, respectively, first isolated from the pedal ganglia of the animal. 2. All the five peptides had a common C-terminal structure of -Pro-Xaa-Phe-Val-NH2, which was shown to be important for their biological activity. 3. The five MIPs showed similar inhibitory effects on contractions of the ABRM but did not affect catch tension and its relaxation. 4. In addition to the MIPs, catch-relaxing peptide (CARP) was also found in the ABRM.

Amino Acid Sequence↗
PubMed1990

65-kilodalton protein phosphorylated by interleukin 2 stimulation bears two putative actin-binding sites and two calcium-binding sites.

We have previously characterized a 65-kilodalton protein (p65) as an interleukin 2 stimulated phosphoprotein in human T cells and showed that three endopeptide sequences of p65 are present in the sequence of l-plastin [Zu et al. (1990) Biochemistry 29, 1055-1062]. In this paper, we present the complete primary structure of p65 based on the cDNA isolated from a human T lymphocyte (KUT-2) cDNA library. Analysis of p65 sequences and the amino acid composition of cleaved p65 N-terminal peptide indicated that the deduced p65 amino acid sequence exactly coincides with that of l-plastin over the C-terminal 580 residues [Lin et al. (1988) Mol. Cell. Biol. 8, 4659-4668] and has a 57-residue extension at the N-terminus to l-plastin. Computer-assisted structural analysis revealed that p65 is a multidomain molecule involving at least three intriguing functional domains: two putative calcium-binding sites along the N-terminal 80 amino acid residues; a putative calmodulin-binding site following the calcium-binding region; and two tandem repeats of putative actin-binding domains in its middle and C-terminal parts, each containing approximately 240 amino acid residues. These results suggest that p65 belongs to actin-binding proteins.

Actins↗
PubMed1990

A novel peroxisomal nonspecific lipid-transfer protein from Candida tropicalis. Gene structure, purification and possible role in beta-oxidation.

We have sequenced the nucleotides of the gene POX18 that encodes PXP-18, a major peroxisomal polypeptide inducible by oleic acid in the yeast Candida tropicalis. POX18 had a single open reading frame of 127 amino acids. Some 33% of the amino acid sequence of the predicted basic polypeptide (13,805 Da), was identical to that of the nonspecific lipid-transfer protein (sterol carrier protein 2) from rat liver. PXP-18, purified to near homogeneity from isolated peroxisomes, had an amino-terminal sequence identical to that of the predicted polypeptide except for the initiator methionine, and had nonspecific lipid-transfer activity comparable to that of its mammalian equivalents. Unexpectedly, PXP-18 lacked the cysteine residue thought to be essential for the activity of this protein in mammals. RNA blot analysis showed that the POX18 gene was expressed exclusively in cells grown on oleic acid, suggesting that PXP-18 has a role in the beta-oxidation of long-chain fatty acids. PXP-18 modulated acyl-coenzyme A oxidase activity at low pH.

Amino Acid Sequence↗
PubMed1990

A novel cardio-excitatory peptide isolated from the atria of the African giant snail, Achatina fulica.

An undecapeptide which potentiates the beat of the ventricle in the African giant snail, Achatina fulica Ferussac, was purified from the atria of the snail. Its primary structure was determined to be H-Ser-Gly-Gln-Ser-Trp-Arg-Pro-Gln-Gly-Arg-Phe-NH2. This peptide was found to have excitatory actions not only on the ventricle but also on the penis retractor muscle, the buccal muscle and the identified neurons controlling the buccal muscle movement of Achatina.

Amino Acid Sequence↗
PubMed1990

Primary structure of human microsomal dipeptidase deduced from molecular cloning.

Two cDNA clones corresponding to human microsomal dipeptidase (MDP, formerly referred to as dehydropeptidase-I or renal dipeptidase (EC 3.4.13.11] were isolated from human placental and renal cDNA libraries employing rapid amplification of cDNA ends strategy. The complete amino acid sequence deduced from the cDNAs contains 411 residues, beginning with a signal peptide of 16 residues. A highly hydrophobic sequence of 16 amino acids is located at the carboxyl terminus, supporting the previous observation which suggested that mature MDP is anchored to the membrane by covalently attached phosphatidylinositol. MDP has four potential N-glycosylation sites and has no apparent sequence similarity to other metallopeptidases. Expression of immunologically cross-reactive and enzymatically active MDP was attained in COS cells transfected with the cDNA. DNA and RNA blot analyses indicated the existence of a single gene and a substantial amount of 1.8-kilobase mRNA in kidney.

Amino Acid Sequence↗
PubMed1990

A molluscan neuropeptide related to the crustacean hormone, RPCH.

A peptide that potentiates twitch contraction of the radula retractor muscle of the prosobranch mollusc Fusinus ferrugineus was isolated from the ganglia of the animal. Its primary structure is H-Ala-Pro-Gly-Trp-NH2 (APGWamide) closely related to the C-terminal tetrapeptide of the crustacean red-pigment-concentrating hormone. APGWamide showed modulatory actions on contractions in various molluscan muscles.

Amino Acid Sequence↗
PubMed1990

Characterization of interleukin 2 stimulated 65-kilodalton phosphoprotein in human T cells.

We have characterized the cellular proteins which are rapidly phosphorylated by interleukin 2 (IL 2) in a human IL 2 dependent cell line. When treated with IL 2, the phosphorylation of five proteins, 65, 50, 37, 24, and 21 kDa, was found in IL 2 dependent cell lines by two-dimensional gel electrophoretic analysis. After cell conversion from an IL 2 dependent state to an IL 2 independent state, one of the five phosphoproteins, the 65-kDa protein, became constitutively phosphorylated even without addition of IL 2. Also, in other IL 2 independent cell lines, such as KUT-2 and HUT-102, constitutive phosphorylation of the 65-kDa protein occurred without IL 2-stimulation. So our researchers were focused on biochemical characterization of the 65-kDa protein. It was found that the 65-kDa protein was one of the major cellular proteins by comparing the results of two-dimensional gel electrophoretic analysis of [32P]Pi-labeled and [3H]leucine-labeled cellular proteins and peptide mapping analysis. Subcellular fractionation studies indicated that the 65-kDa protein is a cytosol protein. The 65-kDa protein was purified from cytosol of a human T cell line, and its amino acid composition and amino acid sequences of its three oligopeptides were determined. It was found that the 65-kDa protein is identical with 1-plastin.

Amino Acid Sequence↗
PubMed1990

Clinical implications of exercise-induced chest pain: comparison of patients with and without pathologic Q waves in coronary artery disease.

We attempted to determine whether exercise-induced silent myocardial ischemia has different clinical implications in patients with and without pathologic Q waves. We studied 152 patients (121 men and 31 women) who had ischemic ST depression (greater than or equal to 0.05 mV) during exercise tests and greater than or equal to 70% narrowing in the three major coronary arteries. According to the presence or absence of chest pain during exercise, they were divided into symptomatic patients and asymptomatic patients: 104 patients without pathologic Q waves (Q(-) group) and 48 patients with pathologic Q waves (Q(+) group). In the Q(-) group, symptomatic patients (n = 56) had a significantly greater number of leads showing ST depression (p less than 0.0002), a greater maximum voltage of ST depression (p less than 0.005), a higher incidence of negative U waves (p less than 0.001), and a poorer blood pressure response (p less than 0.005) than asymptomatic patients (n = 48). However, in the Q(+) group, there were no significant differences between symptomatic (n = 24) and asymptomatic patients (n = 24) with regard to these parameters. We concluded that symptomatic patients without pathologic Q waves had more severe ischemia. On the other hand, in patients with pathologic Q waves, the severity of myocardial ischemia in asymptomatic patients might be equal to that in symptomatic patients. Chest pain during exercise testing is not a good predictor of myocardial ischemia in patients with pathologic Q waves. The presence or absence of pathologic Q waves is an important factor in the analysis of exercise-induced myocardial ischemia.

Chest Pain↗
PubMed1990

Abnormalities of early depolarization in patients with remote anterior myocardial infarction and ventricular septal hypoperfusion. Diagnosis of septal MI by BSM.

The authors conducted this study to find the difference in body surface isopotential maps in 46 patients with previous anterior infarction with and without septal involvement. Thallium-201 myocardial-perfusion imaging identified 25 patients with septal infarction (group P) and 21 without (group N). In contrast to group N, group P had a prominent minimum on the anterior chest during the early phases of the QRS. According to the results obtained, the following criteria for identifying patients with septal infarction (group P) were proposed (1). Criterion 1: The absolute value of the voltage of the minimum is equal to or greater than that of the maximum at 5 ms after the onset of the QRS; (2) Criterion 2: During the early portion of the QRS the voltage of the minimum reaches -0.10 mV at the same time or earlier than the maximum reaches 0.10 mV. Both criteria had higher sensitivities (100% and 100%), specificities (71.4% and 90.5%), and predictive accuracies (87.0% and 95.7%) than either Franklead vectorcardiograms or standard 12-lead electrocardiograms in the study population. Thus, body surface isopotential mapping is considered to be useful for the diagnosis of septal involvement in patients with previous anterior myocardial infarction.

Algorithms↗
PubMed1990

Use of body surface electrocardiographic mapping to localize the asynergic site in previous myocardial infarction.

Body surface electrocardiographic (ECG) maps of myocardial infarction were analyzed using the departure mapping technique, which represents the abnormal potential distribution out of normal ranges. Body surface ECG mapping using 87 leads was performed on 65 patients with previous myocardial infarction and on 40 normal volunteers. Potential departure maps at 10, 20, 30, 40, and 50 msec after the onset of QRS were constructed; each map indicated, if present, the area of abnormal decreased potential that is more than 2 standard deviations from the normal range (-2 SD area). In patients with myocardial infarction, the appearance time and the location of the -2 SD area were specific for the sites of left ventricular asynergy; the sensitivity and specificity were 86% and 100% for the asynergy of segment 2 (20 msec, on the upper left anterior chest), 87% and 97% for segment 3 (30 msec, on the middle anterior chest), 86% and 80% for segment 4 (20 or 30 msec, on the lower right anterior chest), and 88% and 90% for segment 5 (30, 40, or 50 msec, on the middle back), respectively. The sensitivity of these criteria was better than that of 12-lead ECG, while the specificity was comparable. In the analysis of body surface ECG mapping data, departure maps aid in depicting abnormalities and in making an accurate assessment. Body surface ECG mapping can be used to improve the diagnostic ability of ECG to detect myocardial infarction.

Adult↗
PubMed1990

Permeability of small coronary arteries and myocardial injury in hypertensive diabetic rats.

Damage to the coronary artery and myocardium is known to be more marked when hypertension is complicated by diabetes than when either is present alone. The reason is not clear, but one possible factor is vascular permeability. Therefore, we investigated vascular permeability using sodium fluorescein of 70 mg/kg body weight, in 12-week-old streptozotocin-induced diabetic spontaneously hypertensive rats. Non-diabetic spontaneously hypertensive rats, diabetic rats with normal blood pressure, and non-diabetic rats with normal blood pressure of the same age were used as controls and treated similarly. H-E and Azan staining were used to examine vascular abnormality and mycoardial damage. The diabetic spontaneously hypertensive rats showed marked sodium fluorescein in the coronary artery wall and surrounding area, demonstrating greater vascular permeability than non-diabetic spontaneously hypertensive rats, diabetic and non-diabetic normotensive rats. Heart weights and diameters of myocytes were smaller in the diabetic than in the non-diabetic spontaneously hypertensive rats. Diabetic spontaneously hypertensive rats also exhibited marked perivascular fibrosis and focal necrosis. Thus, increased vascular permeability may play a role in vascular and myocardial changes in diabetic spontaneously hypertensive rats.

Animals↗
PubMed1990

Purification and characterization of two forms of cytochrome P-450 with omega-hydroxylase activities toward prostaglandin A and fatty acids from rabbit liver microsomes.

Two forms of cytochrome P-450 (P-450), designated as P-450LPGA omega 1 and P-450LPGA omega 2, have been purified to specific contents of 17.9 and 11.1 nmol P-450/mg protein, respectively, from liver microsomes of rabbits treated with di(2-ethylhexyl)phthalate (DEHP), a peroxisomal proliferator. The purified P-450LPGA omega 1 and P-450LPGA omega 2 were found to have apparent molecular weights of 52,500 and 53,000, respectively. They showed absorption maxima at 451 and 450 nm in the carbon monoxide-difference spectra for their reduced forms, respectively. The two P-450s both efficiently catalyzed the omega-hydroxylation of prostaglandins A1 (PGA1) and A2 (PGA2), as well as the omega- and (omega-1)-hydroxylation of fatty acids such as laurate, myristate, and palmitate. In a reconstituted system, various metal ions such as Na+ and Mg2+ stimulated these reactions. The P-450s exhibited no detectable activity toward several xenobiotics tested. The two P-450s showed different peptide map patterns following limited proteolysis with Staphylococcus aureus V8 protease or papain. The NH2-terminal amino acid sequences (ALNPTRLPGSLSGLLQVAGL and ALSLTRLPGSFSGFLQAxGLLGLLL) of P-450LPGA omega 1 and P-450LPGA omega 2 were identical at 18/20 and 19/24 positions with that of the lung prostaglandin omega-hydroxylase from pregnant rabbits, respectively. An antibody against P-450LPGA omega 2 recognized a 52,000-53,000 molecular weight protein(s) in rabbit liver microsomes. The intensity of the immunoblot was significantly increased in liver microsomes from rabbits treated with DEHP, but not with phenobarbital or 3-methylcholanthrene.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1990

Site-directedly mutated human cytochrome c which retains heme c via only one thioether bond.

Although Cys-14 (human numbering) of cytochrome c was conserved during its molecular evolution and it is supposed to be essential for most cytochromes c to retain heme c via two thioether bonds, a site-directedly mutated human cytochrome c which has an alanine residue at this position and only one thioether bond through Cys-17 turns out to be functional. This shows that Cys-14 is not essential. The absorption spectrum of the atypical cytochrome c is red shifted, and similar to those of Euglena and Crithidia cytochromes c, which also have only one thioether bond [Pettigrew, G.W., Leaver, J.L., Meyer, T.E., & Ryle, A.P. (1975) Biochem. J. 147, 291-302].

Amino Acid Sequence↗
PubMed1990

Purification and characterization of two forms of fatty acid omega-hydroxylase cytochrome P-450 from rabbit kidney cortex microsomes.

We have previously reported the isolation of two forms of cytochrome P-450 (P-450) with omega-hydroxylase activities toward prostaglandin A (PGA) and fatty acids, designated as P-450ka-1 and P-450ka-2, from kidney cortex microsomes of rabbits treated with di(2-ethylhexyl)phthalate [Kusunose, E. et al. (1989) J. Biochem. 106, 194-196]. In the present work, we have purified and characterized two additional forms of rabbit kidney fatty acid omega-hydroxylase, designated as P-450kc and P-450kd. The purified P-450kc and P-450kd had specific contents of 13 and 16 nmol of P-450/mg of protein, with apparent molecular weights of 52,000 and 55,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), respectively. Both the forms showed absorption maxima at 450 nm in the carbon monoxide-difference spectra for their reduced forms. These P-450s efficiently catalyzed the omega- and (omega-1)-hydroxylation of fatty acids such as caprate, laurate, myristate, and palmitate, in a reconstituted system containing P-450, NADPH-P-450 reductase, and phosphatidylcholine. Cytochrome b5 stimulated the reactions to only a slight extent. They had no detectable activity toward PGA and several xenobiotics tested. The two P-450s showed different peptide map patterns after limited proteolysis with papain or Staphylococcus aureus V8 protease.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗