Biomedical subjects

K Yano

Publications and source records attributed to K Yano.

At least 379 records · Page 21Linked to original sources

PubMed1994

Cardiac sarcoplasmic reticulum Ca(2+)-ATPase expression in streptozotocin-induced diabetic rat heart.

Chronic diabetes due to streptozotocin administration has been shown to induce heart dysfunction characterized by prolonged relaxation time as well as decreased Ca2+ transport and Ca(2+)-ATPase (SERCA2) activities of the cardiac sarcoplasmic reticulum (SR). Rats made diabetic with 65 mg/kg of streptozotocin for 3 and 5 weeks exhibited decreased SR Ca(2+)-pump activities; these were normalized upon treatment with insulin. Northern blot and slot blot analyses did not show statistically significant reduction in the relative level of SERCA2 mRNA expression in diabetic or insulin treated rats. Quantitation of SERCA2 protein by Western blot did not reveal any change in diabetic and insulin treated animals. These results suggest that the defect in SR Ca(2+)-pump may not be due to changes at the transcriptional or translational levels in the diabetic heart.

Animals↗

PubMed1994

Identification of the bphA and bphB genes of Pseudomonas sp. strains KKS102 involved in degradation of biphenyl and polychlorinated biphenyls.

The nucleotide sequence of the upstream region of the bphC gene from Pseudomonas sp. strain KKS102 was determined. Four genes were found in this region. Deduced amino acid sequences of the first, second, third and fourth genes showed significant homology with a large subunit of iron-sulfur protein, a small subunit of iron-sulfur protein, ferredoxin and dihydrodiol dehydrogenase, respectively, from other bacteria which degrade biphenyl/polychlorinated biphenyls, toluene and benzene. E. coli, in which the four genes, bphC and the gene for ferredoxin reductase from benzene degrading bacterium were expressed, was able to produce meta-cleavage compounds from chlorinated biphenyls. These results show that these gene products are functional in both biphenyl and polychlorinated biphenyls degradation.

Alcohol Oxidoreductases↗

PubMed1994

Amino acid sequence of spinach ferredoxin:thioredoxin reductase variable subunit.

Ferredoxin:thioredoxin reductase (FTR) is an iron-sulfur protein, which, in the presence of ferredoxin and thioredoxin, catalyses the light-dependent activation of several photosynthetic enzymes. Spinach FTR consists of two dissimilar polypeptide chains, A and B, present in equal amounts. Whereas subunit B seems to be responsible for the catalytic activity, subunit A has no known catalytic function. We found earlier that the N-terminus of subunit A, also called the variable subunit, shows terminal redundancy and that 2-3 of its serine residues are phosphorylated [Tsugita, A. Yano, K., Gardet-Salvi, L. & Schürmann, P. (1991) Protein Sequence Data Anal. 4, 9-13]. We now report the complete amino acid sequence of subunit A, determined by conventional protein sequencing methods. The polypeptide chain with a calculated molecular mass of 12,669 Da consists of 112 amino acids and has a calculated isoelectric point of 5.4. The analysis of the sequence supports the idea that this subunit has no catalytic function. The comparison with a known cyanobacterial FTR reveals about 58% similarity and the striking presence of a N-terminal extension in the spinach protein. This extension may be responsible for the reported size variability of this subunit.

Amino Acid Sequence↗

PubMed1994

Sarcoplasmic reticulum calsequestrins: structural and functional properties.

Calsequestrin is the major Ca(2+)-binding protein localized in the terminal cisternae of the sarcoplasmic reticulum (SR) of skeletal and cardiac muscle cells. Calsequestrin has been purified and cloned from both skeletal and cardiac muscle in mammalian, amphibian, and avian species. Two different calsequestrin gene products namely cardiac and fast have been identified. Fast and cardiac calsequestrin isoforms have a highly acidic amino acid composition. The amino acid composition of the cardiac form is very similar to the skeletal form except for the carboxyl terminal region of the protein which possess variable length of acidic residues and two phosphorylation sites. Circular dichroism and NMR studies have shown that calsequestrin increases its alpha-helical content and the intrinsic fluorescence upon binding of Ca2+. Calsequestrin binds Ca2+ with high-capacity and with moderate affinity and it functions as a Ca2+ storage protein in the lumen of the SR. Calsequestrin has been found to be associated with the Ca2+ release channel protein complex of the SR through protein-protein interactions. The human and rabbit fast calsequestrin genes have been cloned. The fast gene is skeletal muscle specific and transcribed at different rates in fast and slow skeletal muscle but not in cardiac muscle. We have recently cloned the rabbit cardiac calsequestrin gene. Heart expresses exclusively the cardiac calsequestrin gene. This gene is also expressed in slow skeletal muscle. No change in calsequestrin mRNA expression has been detected in animal models of cardiac hypertrophy and in failing human heart.

Amino Acid Sequence↗

PubMed1994

Structure and expression of mRNA for vitellogenin in Bombyx mori.

Vitellogenin, a precursor of major yolk protein of the silkworm, Bombyx mori is a tetramer composed of each two molecules of heavy and light subunits. We cloned mRNA sequence for the B. mori vitellogenin and analyzed its structure. Sequence alignment of several overlapping cDNA clones indicated that the vitellogenin mRNA is approx. 5.7 kb, containing an open reading frame for a peptide with 1782 amino acid residues. By comparing the deduced amino acid sequence with the amino-terminal primary structures of vitellogenin subunits, it is suggested that the heavy and light subunits of the B. mori vitellogenin are encoded by a single contiguous mRNA. The primary translation product of the vitellogenin mRNA was detected in the microsomal fraction prepared from the fat body of vitellogenic females. Northern blot analysis of the fat body RNA demonstrated that the biosynthesis of vitellogenin in B. mori is regulated in a tissue-, sex- and stage-specific manner at the level of mRNA. Possible cause for discrepancy between the present results and our previous proposal (Izumi, S. and Tomino, S. (1983) Insect Biochem. 13, 81-85) on the biosynthesis of B. mori vitellogenin is also discussed.

Amino Acid Sequence↗

PubMed1994

Micromachined electroporation system for transgenic fish.

Luciferase gene was introduced into fertilized eggs of medaka by a localized electric field between thin film electrodes formed on a glass plate. Miniaturization of the electrodes enabled us to apply a localized electric field to the animal pole of the fertilized egg. Biochemical luminescence and an electrophoresis pattern showed expression and integration of the gene, respectively. The presented system had a higher ratio of gene introduction than the conventional electroporation method.

Animals↗

PubMed1994

Hepatocyte growth factor and its variant with a deletion of five amino acids are distinguishable in their biological activity and tertiary structure.

A naturally occurring splice variant of hepatocyte growth factor (HGF) lacks a 5-amino acid sequence in the first kringle domain. Comparison of HGF and the deletion variant (dHGF) revealed that the deletion significantly altered the biological activities, solubility, and immunological property of HGF. HGF was respectively about 20-, 10-, and 2-fold more potent than dHGF in the stimulation of DNA synthesis in human umbilical vein endothelial cells, human aorta smooth muscle cells, and NSF-60 (murine myeloblastic cells). Conversely, dHGF was respectively about 3-, 2-, and 2-fold more potent than HGF in the stimulation of DNA synthesis in LLC-PK1 (pig kidney epithelial cells), OK (American opossum kidney epithelial cells), and rat hepatocytes. Moreover, HGF was over 70-fold more soluble than dHGF in PBS. Several monoclonal antibodies raised against dHGF recognized only dHGF and neither HGF nor reduced dHGF, demonstrating that the deletion caused a tertiary structural change. The structural change in HGF may be responsible for its altered biological activities and solubility.

Animals↗

PubMed1994

Oligonucleotide probe design--a new approach.

The use of oligonucleotides for gene amplification, as diagnostic probes or antisense-based drugs can be optimized by minimizing the possibility of nonspecific hybridization.

Base Sequence↗

PubMed1994

Silver stained nucleolar organizer region proteins and Helix pomatia agglutinin immunostaining in esophageal carcinoma: correlated prognostic factors.

The number of nucleolar organizer region proteins identified by silver staining (AgNORs) and alterations in cell surface glycoproteins identified by Helix pomatia agglutinin (HPA) immunostaining were studied in 96 primary esophageal carcinomas. The number of AgNORs increased with increasing depth of cancer invasion, venous involvement, lymphatic invasion, and tumor stage. Positivity of HPA staining correlated significantly with increasing depth of cancer invasion, venous invasion, and tumor stage. Forty of 42 HPA negative cases had low AgNORs numbers (< 4), while 39 of 54 HPA positive cases had high AgNORs numbers (> or = 4) (P = 0.0001). The survival rate of patients with stage III and IV disease was significantly poorer for those with a high AgNORs score and HPA positivity than in those with a low AgNORs score and HPA negativity. The present study indicates that the AgNORs score is positively correlated with positive HPA staining and that tumors having both factors represent a subgroup of esophageal carcinomas with poor prognosis.

Adult↗

PubMed1994

Spasmogenic actions of frog urotensin II on the bladder and ileum of the frog, Rana catesbeiana.

The effects of synthetic frog urotensin II on the motility of isolated smooth muscle strips of urinary bladder and ileum from the bullfrog Rana catesbeiana were investigated. The strips of bladder exhibited strong spontaneous contractions. Frog urotensin II produced a concentration-dependent increase in the frequency of contraction (EC50 = 8.1 x 10(-9) M) but had no significant effect on tension. Maximum stimulation (4 times the rate of spontaneous contractions) was produced by 10(-7) M peptide. The ileal smooth muscle strips exhibited only weak spontaneous contractions but frog urotensin II produced concentration-dependent increases in both the frequency (EC50 = 1.3 x 10(-9) M) and the strength (EC50 = 3.6 x 10(-9) M) of contraction. The peptide had no effect on the motility of strips of rat urinary bladder and ileum. In both the frog bladder and ileum preparations, the effect of urotensin II was not affected by preincubation of the strips with atropine, tetrodotoxin, and somatostatin-14 but indomethacin produced a significant (P < 0.05) decrease in the strength of the contractions of the bladder (to 21 +/- 6% of control values) and ileum (to 32 +/- 13%). Arachidonic acid produced an increase in the frequency of contraction of the bladder and an increase in both the frequency and the strength of contraction of the ileum. The data demonstrate that urotensin II exercises a spasmogenic effect on amphibian smooth muscle that is similar to that of the peptide on teleost tissues. An involvement of prostaglandin synthesis in the spasmogenic action of urotensin II on frog bladder and ileum is indicated.

Animals↗

PubMed1994

Dipyridamole inhibits early wound healing in rat skin incisions.

In an effort to investigate the significance of platelet aggregation on early wound healing, the inhibitory effects of an antiplatelet drug (dipyridamole) on tensile wound strength was assessed. The breaking strength of the dorsal incisional wounds in Donryu rats both with and without the administration of dipyridamole was measured. In experiment I, the intraperitoneal administration of dipyridamole (100 mg/kg/day, Group A; 50 mg/kg/day, Group B) and saline (3 ml/day; Group C) was performed during the periods between the day of incision and the excision of the healing wound specimen in a 2.0-cm width on the third and seventh postoperative days (POD). The wound breaking strength was 229 +/- 44, 256 +/- 39, and 352 +/- 38 g/cm2 on POD 3 and 477 +/- 67, 578 +/- 60, and 764 +/- 31.9 g/cm2 on POD 7, in Groups A, B, and C, respectively. In experiment II, we performed the intraperitoneal administration of either dipyridamole (100 mg/kg) or 3 ml of saline as a control just before incision (Group a) as well as at 4 hr (Group b), and 12 hr (Group c) after incision, and the percentages of tensile strength compared with the control were 72 +/- 8, 89 +/- 13, and 103 +/- 23% in Groups a, b, and c, respectively. The administration of dipyridamole significantly inhibited the wound healing and, therefore, platelet aggregation would appear to play an important role in the early phase of wound healing.

Animals↗

PubMed1994

Stress-induced transcriptional activation mediated by YAP1 and YAP2 genes that encode the Jun family of transcriptional activators in Saccharomyces cerevisiae.

The Saccharomyces cerevisiae YAP2 gene encoding an AP-1-like transcriptional activator protein was cloned by selection for genes that confer pleiotropic drug resistance when present in high copy number. The novel YAP2 gene encodes a protein of 45827 daltons and is homologous in part to a known transcriptional activator protein encoded by YAP1/PDR4/SNQ3/PAR1. Homology was found only in both terminal regions. The N-terminal portion contains a region rich in basic amino acids, followed by a "leucine zipper" motif. Overexpression of YAP2 led to the induction of expression of an AP-1 recognition element (ARE)-dependent promoter. The yap1 disruptant has been shown to be sensitive to H2O2. In this study, we demonstrated that the yap1 disruptant is also unable to grow in medium containing 150 microM cadmium, whereas the yap2 disruptant exhibited no significant phenotypes. However, YAP2 in high copy number did suppress cadmium sensitivity, but not H2O2 sensitivity of the yap1 disruptant. YAP1 was able to mediate both cadmium- and H2O2-induced transcriptional activation of an ARE-dependent promoter. A high-copy-number plasmid bearing YAP2 mediated cadmium-induced transcriptional activation of this promoter. The inductions were prevented by the antioxidant N-acetyl-L-cysteine.

Acetylcysteine↗

PubMed1994

Saccharomyces cerevisiae YDR1, which encodes a member of the ATP-binding cassette (ABC) superfamily, is required for multidrug resistance.

A multidrug resistance gene, YDR1, of Saccharomyces cerevisiae, which encodes a 170-kDa protein of a member of the ABC superfamily, was identified. Disruption of YDR1 resulted in hypersensitivity to cycloheximide, cerulenin, compactin, staurosporine and fluphenazine, indicating that YDR1 is an important determinant of cross resistance to apparently-unrelated drugs. The Ydr1 protein bears the highest similarity to the S. cerevisiae Snq2 protein required for resistance to the mutagen 4-NQO. The drug-specificity analysis of YDR1 and SNQ2 by gene disruption, and its phenotypic suppression by the overexpressed genes, revealed overlapping, yet distinct, specificities. YDR1 was responsible for cycloheximide, cerulenin and compactin resistance, whereas, SNQ2 was responsible for 4-NQO resistance. The two genes had overlapping specificities toward staurosporine and fluphenazine. The transcription of YDR1 and SNQ2 was induced by various drugs, both relevant and irrelevant to the resistance caused by the gene, suggesting that drug specificity can be mainly attributed to the functional difference of the putative transporters. The transcription of these genes was also increased by heat shock. The yeast drug-resistance system provides a novel model for mammalian multidrug resistance.

ATP-Binding Cassette Transporters↗

PubMed1994

Intraarterial combined immunochemotherapy for unresectable hepatocellular carcinoma: preliminary results.

An important objective for patients with unresectable hepatocellular carcinoma (HCC) is the development of effective chemotherapy. We administered a combination of biological response modifiers and anticancer agents to 24 patients with unresectable HCC. Each case had an implanted infuser port which was connected to a catheter placed in the hepatic artery for the intraarterial (i.a.) administration of chemotherapy. The following agents were administered to each patient: recombinant interleukin-2 (800,000 JRU/day infused i.a. continuously for 6 days/week); OK-432 (5 KE injected i.a. twice in 4 weeks and i.m. three times per week); Adriamycin (10 mg injected i.a. twice in 4 weeks); cyclophosphamide (300 mg injected i.a. twice in 4 weeks), and famotidine (40 mg/day administered orally). Objective response was assessed according to tumor size measured by computed tomography and angiography before and after treatment. We observed a complete response (CR) in 4, partial response (PR) in 3, minor response (MR) in 7, no change (NC) in 7, and progressive disease (PD) in 3. The response rate (CR+PR+MR) was 58.3%. The overall 2-year survival rate was 52%. The 2-year survival rate of the responders (CR+PR+MR) was 80%, while that of the non-responders (NC+PD) was 0%. There was a significant difference between the responders and non-responders in respect to survival rate (P < 0.05). The percentages of CD25+ cells, CD56+ cells, and Leu7-CD16+ cells and NK activity in the peripheral blood showed a significant increase following the regimen. Serum levels of tumor necrosis factor alpha TNF alpha rose after the initiation of OK-432. TNF alpha levels were higher in the responders than in the non-responders. Adverse effects included high fever (all patients) and severe transient hypotension (15 patients) that was controlled by conservative therapy. Combined immunochemotherapy administered intraarterially may be a new strategy for treating unresectable HCC.

Aged↗

PubMed1994

Hashimoto thyroiditis, distal renal tubular acidosis, pernicious anaemia and encephalopathy: a rare combination of auto-immune disorders in a 12-year-old girl.

A case of a 12-year-old girl with a multiple auto-immune disorder is reported. She showed Hashimoto thyroiditis which subsequently developed to hashitoxicosis and distal renal tubular acidosis at 5 years of age, pernicious anaemia at the age of 9 and severe encephalopathy at the age of 12. Laboratory studies revealed very high titres of anti-microsomal and anti-thyroglobulin antibodies and positive gastric parietal cell antibody. As to the encephalopathy, positive oligoclonal IgG bands and high values of IgG index and IgG synthesis ratio in CSF were observed with aggravation of her neurological symptoms. High-dose steroid therapy was effective toward the encephalopathy. Paediatricians should pay careful attention to patients with Hashimoto thyroiditis for association with other autoimmune disorders.

Acidosis, Renal Tubular↗

PubMed1994

Supernormal atrial conduction and its relation to atrial vulnerability and atrial fibrillation in patients with sick sinus syndrome and paroxysmal atrial fibrillation.

The purpose of this study was to evaluate prospectively the relationship between supernormal atrial conduction (SNC) and the atrial vulnerability to fibrillation in patients with sick sinus syndrome (SSS) and paroxysmal atrial fibrillation (PAF). Programmed atrial stimulation was performed in 32 age-matched control patients (group I), 26 with SSS but without tachyarrhythmias (group II), and 24 with both SSS and PAF (group III) to assess some determinants of atrial vulnerability, SNC, and atrial fibrillation inducibility. Supernormal atrial conduction was observed in 20 (63%) patients of group I, 12 (46%) patients of group II, and 5 (21%) patients of group III (group I vs group III; p < 0.002). The SNC zone was 46 +/- 44 msec in group I, 36 +/- 42 msec in group II, and 12 +/- 24 msec in group III. (group I vs group III; p < 0.001). The absence of SNC showed a specificity of 89% and a positive predictive accuracy of 79% in predicting inducibility of atrial fibrillation. The sensitivity was 33% and the negative predictive accuracy was 52%. The SNC zone showed a significant inverse correlation with P wave duration (r = -0.32; p < 0.003), intraatrial conduction time (r = -0.28; p < 0.02), and maximum conduction delay (r = -0.23; p < 0.05). The maximum decrease in conduction time during supernormal conduction showed a significant inverse correlation with P wave duration (r = -0.27; p < 0.02), intraatrial conduction time (r = -0.26; p < 0.02), and with the maximum conduction delay (r = -0.27; p < 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

Mechanism of the suppression of repetitive atrial firing by isoproterenol--comparison with disopyramide.

To investigate whether isoproterenol (Iso) could suppress the initiation of repetitive atrial firing (RAF), we investigated its effect on RAF in comparison with that of disopyramide (Diso). Extrastimuli at a basic cycle length of 500 ms were delivered from the high right atrium in 49 patients who received an intravenous infusion of Iso (0.01 microgram/kg per min) and in 39 patients given intravenous Diso (2 mg/kg per 10 min). Induction of RAF, the atrial effective refractory period (A-ERP), and the maximum conduction delay (MCD) were measured. Iso abolished the induction of RAF in 13/19 (68%) patients, while Diso did so in 13/22 (59%) patients. Thirty-four of the 41 patients with RAF in the baseline study had an A-ERP < 250 ms and an MCD > 40 ms. Iso significantly decreased the A-ERP from 205 +/- 26 to 194 +/- 23 ms (P < 0.01) and significantly decreased the MCD from 67 +/- 24 to 39 +/- 16 ms (P < 0.0001) in 19 patients with RAF. On the other hand, Diso significantly increased the A-ERP from 203 +/- 31 to 235 +/- 36 ms (P < 0.0001), and significantly diminished the MCD from 68 +/- 31 to 55 +/- 30 ms (P < 0.01) in 22 patients with RAF. In patients with new RAF (n = 7) or re-induced RAF (n = 14) during Iso or after Diso, the MCD was more than 40 ms. Our results suggest that there are two different modes of RAF suppression, i.e. shortening or lengthening of the A-ERP.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

Electrophysiologic demonstration of anterograde fast and slow pathways within the His bundle in patients with normal intraventricular conduction.

Electrophysiological evidence of functional longitudinal dissociation has been shown in different structures of the normal conduction system of the heart and in anomalous atrioventricular (AV) pathways. The typical sudden fast-to-slow jump phenomenon, which is commonly observed in patients with dual AV nodal pathways, has not been demonstrated so far within the normal His bundle. Herein we report unusual electrophysiological properties of the His bundle in two patients with normal intraventricular conduction. Of 86 patients with discontinuous anterograde AV function curves, programmed atrial stimulation revealed dual anterograde His bundle pathways in only 2 (2.3%) patients. Extrastimuli introduced at critically timed coupling intervals produced a sudden marked increase in H2-V2 interval suggesting failure of fast pathway with conduction proceeding through a slower pathway with shorter refractory period. With further decreasing coupling intervals, the second H2-V2 curve showed decremental conduction which allowed a type II gap phenomenon in the right bundle branch to occur in one of the patients. No echo beats were observed. These results provide the first electrophysiological demonstration, in patients with normal intraventricular conduction, of anterograde failure of a fast His bundle pathway with subsequent conduction through a slow His bundle pathway. His bundle duality was manifested by dual conduction times and refractory periods. These observations further expand our knowledge on the electrophysiologic properties of the His bundle.

Atrial Fibrillation↗