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Biomedical subjects

Y Mitani

Publications and source records attributed to Y Mitani.

At least 55 records · Page 3Linked to original sources
PubMed1997

Inhaled low-dose nitric oxide for postoperative care in patients with congenital heart defects.

Postoperative pulmonary hypertensive crisis is a major problem that may account for a substantial part of the postoperative mortality and morbidity. We, therefore, evaluated the effect of inhalation of low-dose nitric oxide (NO) on postoperative care in pediatric patients with pulmonary hypertension. We studied 10 infants and children ages 1-108 months (median age, 11 months) with congenital heart disease associated with pulmonary hypertension. The NO and N2 gas mixture was then mixed with varied quantities of air and oxygen and delivered into a respirator instead of an inspiratory tube. Patients were treated with inhaled NO for 38.6 +/- 19.6 h (range 1-200 h). All patients were eventually weaned from high level sedation and respirator. The NO concentration ranged from 2 to 5 parts per million. During NO inhalation patients demonstrated a statistically significant reduction in systolic pulmonary arterial pressure by approximately 26%; from 55 +/- 10 to 41 +/- 20 mm Hg. Inhalation of NO resulted in a significant increase of Pao2 from 110 +/- 16 to 149 +/- 29 mm Hg. A-aDo2 significantly decreased from 284 +/- 27 to 247 +/- 31 mm Hg. In conclusion, we have shown that a low-dose NO inhalation acted as pulmonary vasodilator in patients with preexisting pulmonary hypertension.

Administration, Inhalation↗
PubMed1997

Continuous low-dose NO inhalation does not prevent monocrotaline-induced pulmonary hypertension in rats.

We determined whether vasodilator doses of inhaled nitric oxide (NO) prevented the progression of pulmonary hypertension (PH) and vascular changes in monocrotaline-induced PH. Short-term NO inhalation in rats 3 wk after the injection of monocrotaline reduced mean pulmonary artery pressure (PAP) from 30.7 +/- 2.2 (SE) to 26.4 +/- 1.4 mmHg at 10 parts per million (ppm) and from 30.2 +/- 1.3 to 25.8 +/- 1.4 mmHg at 40 ppm. There were no differences among rats exposed to air only and rats exposed to 10 ppm of NO for 19 days after a single subcutaneous injection of monocrotaline, in mean PAP (34.3 +/- 1.9 mmHg air vs. 32.8 +/- 1.4 mmHg NO), right ventricular hypertrophy (RVH), medial wall thickness (MWT) of muscular arteries, and the percentage of muscularized arteries at alveolar wall (%AW) and duct (%AD) level. Additional groups exposed to air only and 40 ppm of NO for 19 days again showed no difference in mean PAP, RVH, MWT, and %AD, except that this dose slightly reduced %AW (60.6 +/- 3.4% air vs. 46.9 +/- 5.2% NO, P = 0.04). Urine nitrate (NO3) level was higher in rats that had inhaled NO. In contrast to chronic hypoxic PH, vasodilator doses of NO inhalation did not prevent the development of PH in this malignant form of experimental PH.

Administration, Inhalation↗
PubMed1996

Amitriptyline inhibits the G protein and K+ channel in the cloned thyroid cell line.

We have reported that thyroid K+ channel is activated by extracellular application of the thyroid-stimulating hormone (TSH) using single channel recording method performed on cloned normal rat thyroid cell (FRTL-5) membrane. Treatment of dibutyryladenosine cyclic monophosphate (Bt2 cAMP) also activated the TSH-dependent K+ channel. These findings indicate that the thyroid K+ channel is activated through the TSH-adenosine cyclic monophosphate (cAMP)-protein kinase A system. We examined the effects of amitriptyline on TSH-guanosine triphosphate binding protein (G protein)-adenylate cyclase-cAMP-K+ channel system in the cloned normal rat thyroid cell line FRTL-5. Amitriptyline inhibited the cAMP production induced by TSH. Amitriptyline also inhibited the cAMP production induced by cholera toxin, indicating that amitriptyline inhibited the thyroid G protein. Amitriptyline had no effect on TSH-receptor binding and cAMP production by forskolin (adenylate cyclase stimulator). Amitriptyline inhibited the K+ channel activation by cAMP, indicating that the suppressing mechanism is not the inhibition of TSH receptor or G protein but the direct suppression of K+ channel. It was concluded that amitriptyline inhibited the thyroid G protein and K+ channel.

Amitriptyline↗
PubMed1996

Roles of insulin, guanosine 5'-[gamma-thio]triphosphate and phorbol 12-myristate 13-acetate in signalling pathways of GLUT4 translocation.

Insulin, guanosine 5'-[gamma-thio]triphosphate (GTP[S] and phorbol 12-myristate 13-acetate (PMA) trigger the translocation of Gl UT4 (type 4 glucose transporter; insulin-sensitive glucose transporter) from an intracellular pool to the cell surface. We have developed a highly sensitive and quantitative method to detect GLUT4 immunologically on the surface of intact 3T3-L1 adipocytes and Chinese hamster ovary (CHO) cells, using c-myc epitope-tagged GLUT4 (GLUT4myc). We examined the roles of insulin, GTP[S] and PMA in the signalling pathways of GLUT4 translocation in the CHO cell system. Among small molecular GTP-binding proteins, ras, rab3D, rad and rho seem to be candidates as signal transmitters of insulin-stimulated GLUT4 translocation. Overexpression of wild-type H-ras and the dominant negative mutant H-rass17N in our cell system respectively enhanced and blocked insulin-stimulated activation of mitogen-activated protein kinase, but did not affect insulin-stimulated GLUT4 translocation. Overexpression of rab3D or rad in the cells did not affect GLUT4 translocation triggered by insulin, GTP[S] or PMA. Treatment with Botulinum C3 exoenzyme, a specific inhibitor of rho, had no effect on GLUT4 translocation induced by insulin, GTP[S] or PMA. Therefore these small molecular GTP-binding proteins are not likely to be involved in GLUT4 translocation. In addition, insulin, GTP[S] and PMA apparently stimulate GLUT4 translocation through independent pathways.

3T3 Cells↗
PubMed1996

Induction of GLUT-1 mRNA in response to inhibition of oxidative phosphorylation: role of increased [Ca2+]i.

Exposure of Clone 9 cells (a rat liver cell line expressing only the GLUT-1 isoform) to 5 mM azide or to 3 microM ionomycin for 12 h results in 3.7 +/- 0.3- and 4.9 +/- 0.4-fold increases in GLUT-1 mRNA content, respectively, suggesting the hypothesis that a rise in cytosolic free calcium concentration ([Ca2+]i) mediates the induction of GLUT-1 mRNA by azide. Five lines of evidence were employed to test this hypothesis. 1) Exposure of cells to 0-3 microM of ionomycin increased [Ca2+]i from 83 +/- 9 to 504 +/- 20 nM (half-maximal effect at 0.1 microM ionomycin), whereas half-maximal increase in GLUT-1 mRNA occurred at 1 microM ionomycin, with the increase in the mRNA being negligible at [Ca2+]i below 400 nM. Exposure of cells to 5 mM azide, however, increased [Ca2+]i to maximal value of 174 +/- 22 nM at 15 s, suggesting that the magnitude of the increase in [Ca2+]i by azide may not be adequate for the response. 2) The increase in GLUT-1 mRNA content by azide was fully preserved in cells preloaded with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA). 3) GLUT-1 mRNA content increased within 30 min of exposure to ionomycin, whereas the mRNA increased after a "delay" period of 2 h in cells exposed to 5 mM azide. 4) A brief (2-min) rise in [Ca2+]i by ionomycin was sufficient to increase GLUT-1 mRNA content, whereas continuous exposure to azide for > 1 h was necessary for a subsequent induction of the mRNA. 5) Treatment with ionomycin, A-23187, and thapsigargin caused larger increases in glucose-regulated protein 78 and 94 and in 70-kDa heat shock protein mRNAs than in GLUT-1 mRNA, whereas treatment with azide resulted in greater induction of GLUT-1 mRNA. These results strongly suggest that, whereas increased [Ca2+]i enhances GLUT-1 mRNA expression and azide increases [Ca2+]i, the rise in [Ca2+]i does not mediate the induction of GLUT-1 mRNA in response to inhibition of oxidative phosphorylation.

Adenosine Triphosphate↗
PubMed1996

A new type of familial central diabetes insipidus caused by a single base substitution in the neurophysin II coding region of the vasopressin gene.

We studied the genetic basis of familial neurohypophyseal diabetes insipidus in a Japanese family. The members had polyuria and a deficiency of plasma vasopressin (AVP). Polymerase chain reaction (PCR) amplified exons of the AVP-neurophysin-II gene were subcloned and sequenced. Exons 1 and 3 were normal, but nucleotide 1884 Guanine (G) in exon 2 was substituted with Thymine (T), which induced a substitution of glycine (Gly) for valine (Val). To examine the presence of this mutation in the affected subjects, we designed two mutated primers. One of them induced a new endonuclease restriction site in the PCR fragments from normal, and the other induced a new endonuclease restriction site from patients with the mutation. DNA fragments from two affected members of this family were amplified with this primer, and the PCR products were digested by endonuclease and resolved by electrophoresis. The results indicated that these subjects had both normal and mutant alleles, indicating that the mutation was heterozygous. We concluded that this mutation caused neurohypophyseal diabetes insipidus in this family.

Arginine Vasopressin↗
PubMed1996

Rhabdomyolysis following administration of cyclophosphamide: a case report in a BMT recipient.

Massive rhabdomyolysis followed by myocardial necrosis was observed in a 14-year-old patient undergoing allogeneic bone marrow transplantation for severe aplastic anemia. Rhabdomyolysis was preceded by the administration of cyclophosphamide as part of a preparative regimen for transplantation Although the specific etiology of this rhabdomyolysis is still unknown, an association with high-dose cyclophosphamide should be noted.

Bone Marrow Transplantation↗
PubMed1995

Cloning of a cDNA encoding a 190-kDa insulin receptor substrate-1-like protein of simian COS cells.

Major insulin signals such as stimulation of glucose uptake and DNA synthesis and modification of hexose metabolism are mediated by the tyrosine-phosphorylated insulin receptor substrate-1 (IRS-1; pp180) in many species of cells. We cloned cDNA encoding a 190-kDa IRS-1-like protein (pp190) in simian COS cells and which is slightly larger than IRS-1 (pp180) of human, rat, and mouse cells. The deduced amino acid sequence of COS pp190 consisted of 1251 amino acids and was 96.4%, 87.9% and 88.7% identical to human, mouse and rat IRS-1. The COS pp190 bound to SH2 (src-homology 2) domains of p85, Grb2/Ash, and SH-PTP2, as did IRS-1. In IRS-1-knockout mice, insulin signals are thought to be mediated by IRS-2 (pp190), which is an alternative signaling molecule and is slightly larger than IRS-1. However, the COS pp190 may be a simian homologue of IRS-1, but not of IRS-2. The results of Southern blotting suggested the possibility that Chinese hamster ovary (CHO) cells have not only the IRS-1 gene but also a gene related to the COS pp190.

Amino Acid Sequence↗
PubMed1995

Female reproductive properties and prenatal development of a senescence-accelerated mouse strain.

Female reproductive properties, early embryonic development, and serum estradiol and progesterone levels of the senescence-accelerated mouse (SAM)-prone (SAM-P) strain were compared with those of a SAM-resistant (SAM-R) strain. The reproductive life span of SAM-P (from 11.4 to 25.0 weeks old) was shorter than that of SAM-R (11.1 to 41.6 weeks old), and the total number of SAM-P pups was 41.7% less than from SAM-R. The reproductive senescence of SAM-P is more accelerated than that of SAM-R. At 15 weeks old, the maximum litter size of SAM-P was noted and was 33.7% smaller than that of SAM-R. Although no differences in the numbers of ovulated and fertilized ova were observed between two strains, the number of implants in SAM-P was 21.6% less than in SAM-R. Cell cleavage was delayed in embryos of SAM-P (8% morula, at day 2 of pregnancy) compared to SAM-R (48%). At day 3 of pregnancy, 9% and 33% of the embryos were blastocysts in SAM-P and SAM-R, respectively. At day 1 of pregnancy, serum estradiol level in SAM-P was 18.2% higher than in SAM-R, whereas the serum progesterone level in SAM-P was 46.2% lower than in SAM-R. The unbalance of estradiol and progesterone levels in SAM-P was considered to be the cause of the delay in early embryonic development, and then the decrease of implantation and a smaller litter size.

Aging↗
PubMed1995

Family with nonmedullary thyroid neoplasms.

This report concerns a family in which papillary thyroid carcinoma appeared in the father and two daughters and follicular adenoma in a granddaughter. The father died of systemic metastasis of papillary thyroid carcinoma. The two daughters and granddaughter felt well postoperatively. We speculate that some gene-related factors might play an important role in familial occurrence of papillary thyroid carcinoma and follicular thyroid adenoma in the family.

Adenoma↗
PubMed1995

Stimulation of GLUT-1 glucose transporter expression in response to exposure to calcium ionophore A-23187.

We tested the hypothesis that an increase in cytosolic calcium concentration stimulates glucose transporter isoform (GLUT-1) gene expression. Exposure of a rat liver cell line (Clone 9) to 3 microM A-23187 for 12 h resulted in 3-, 5-, and 10-fold increases in cytochalasin B-inhibitable 3-O-methyl-D-glucose transport, GLUT-1 protein, and GLUT-1 mRNA content, respectively. The induction of GLUT-1 mRNA in response to A-23187 is not preceded by a significant decrease in cell ATP content. This induction is prevented by 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid in conjunction with ethylene glycol-bis(beta-aminoethyl ether)-N,N, N',N'-tetraacetic acid. To investigate the mechanism of GLUT-1 mRNA induction, we found that exposure to A-23187 stabilized GLUT-1 mRNA: with the employment of actinomycin D, GLUT-1 mRNA had a half-life of 1.5 and 5.5 h in control and A-23187-treated cells, respectively. In nuclear run-on assays, the rate of GLUT-1 gene transcription was stimulated 1.5- to 1.7-fold in nuclei isolated from cells exposed to A-23187 for either 30 min or 2 h. These results demonstrate that exposure to A-23187 stimulates GLUT-1 gene expression and that the increase in GLUT-1 mRNA content is mediated in part by enhanced GLUT-1 gene transcription as well as decreased GLUT-1 mRNA degradation. The increase in GLUT-1 mRNA content, in turn, is associated with increased cell GLUT-1 content and enhanced glucose transport.

Animals↗
PubMed1995

Antiarrhythmic drugs inhibit the G-protein and K+ channels in the cultured thyroid cell line.

We examined the effects of antiarrhythmic drugs on the induction of cAMP by TSH (thyroid-stimulating hormone), using continuously cultured FRTL-5 rat thyroid cells. Group Ia antiarrhythmic drugs had no effect, but Group Ib antiarrhythmic drugs suppressed cAMP induction by TSH. These drugs suppressed cAMP induction in response to cholera toxin but did not inhibit TSH receptor binding or cAMP induction by forskolin. These results indicate that Group Ib antiarrhythmic drugs inhibit thyroid G-protein, resulting in a decrease in cAMP induction by TSH. We also examined the effect of antiarrhythmic drugs on K+ channels. Group Ia antiarrhythmic drugs had no effect on K+ channel activation by TSH and cAMP. On the other hand, Group Ib antiarrhythmic drugs suppressed K+ channel activation by TSH and cAMP. This indicates that the mechanism of suppression is not inhibition of TSH receptors or G-proteins but the direct suppression of K+ channels. Group Ib antiarrhythmic drugs inhibited thyroid Gs-protein and thyroid K+ channels. Considering the close relationship between G-protein and ion channels in the cardiac cell membrane, these different effects of Group Ia and Group Ib antiarrhythmic drugs on G-proteins and K+ channels are of interest. Further investigation is necessary to clarify the relationship between thyroid G-proteins and thyroid K+ channels.

Animals↗
PubMed1994

Involvement of the C-terminal residues of the 20,000-dalton light chain of myosin on the regulation of smooth muscle actomyosin.

The segment of smooth muscle regulatory light chain essential for the phosphorylation dependent activation of actomyosin motor activity and the binding of myosin heavy chain was identified. The C-terminal domain of the 20-kDa light chain, which is less conserved than the rest of the polypeptide among various muscle types, was mutated by either deletion or substitution of amino acid residues and the mutant light chains were then incorporated into myosin by subunit exchange. Deletion of Lys149-Ala166 markedly reduced the affinity of the light chain for the heavy chain, whereas the C-terminal five residues, Lys167-Asp171, did not contribute to the binding affinity. Deletion of Lys149-Phe158 abolished the phosphorylation-dependent activation of actomyosin ATPase activity as well as superprecipitation activity. These results suggest that the C-terminal domain of the regulatory light chain is critical for transmitting the change in the conformation of the regulatory light chain induced by phosphorylation at Ser19 to the heavy chain.

Actomyosin↗
PubMed1994

[Prolongation and recovery under sevoflurane anesthesia of neuromuscular blocking action of vecuronium].

Thirty-seven patients (ASA I or II) undergoing elective abdominal surgery were randomly allocated to four groups, which were anesthetized with nitrous oxide 67%, oxygen 33% and sevoflurane 0%, 1%, 2% and 3% respectively. We administered clinically used doses of vecuronium for abdominal surgery and studied the duration (the time from 100% block after injection to 20% recovery) and the recovery time (time from the last injection of vecuronium to 20% recovery). No prolongation of neuromuscular blocking effect was demonstrated with the initial dose of vecuronium. Significant prolongations of the duration and the recovery time were demonstrated with the maintenance dose of vecuronium only with sevoflurane over 2% and the effect was concentration-dependent.

Abdomen↗
PubMed1993

The TSH-dependent potassium channel in a cloned rat thyroid cell line.

We found a TSH-dependent K+ channel in the membrane of a rat thyroid cell line (FRTL-5 cell). This K+ channel is activated by extracellular application of the thyroid stimulating hormone (TSH). Treatment of dibutyryladenosine cyclic monophosphate (Bt2 cAMP) also activated the TSH-dependent K+ channel. Intracellular application of protein kinase A activates this K+ channel without the presence of free Ca2+. These findings indicate that the thyroid K+ channel is activated through the TSH-cAMP-protein kinase A system. This is the first report of a polypeptide hormone activated K+ channel and it should be useful for examining the effects of this K+ channel on thyroid cell functions.

Amino Acid Sequence↗
PubMed1993

Renal hypouricemia with both drug-insensitive secretion and defective reabsorption of urate: a novel type of renal hypouricemia.

Renal handling of urate in the hypouricemic patient with increase in both urate clearance (Cur) and Cur/creatinine clearance (Ccr) and normal urinary excretion of urate was studied according to the pharmacological evaluation. In the present case there was no response of urate excretion to either pyrazinamide or probenecid. Both furosemide and prednisolone could not alter Cur and Cur/Ccr. Administration of inosine could have increased Cur, which was greater than Ccr. These results suggest that the present case had the defect of both pre- and postsecretory reabsorption of urate, accompanied by the existence of drug-insensitive secretion of urate, which is different from hitherto known types of renal hypouricemia, i.e. a novel type of renal hypouricemia.

Adult↗
PubMed1993

The effects of synthetic alpha-human atrial natriuretic peptide (alpha-hANP) on the overall baroreflex system in anesthetized mongrel dogs.

The effects of alpha-hANP (0.3 micrograms/kg body weight/min) on the baroreflex system were studied in anesthetized dogs according to three different protocols. In the first protocol, the effects of alpha-hANP on an open-loop gain (G(AP)) of the overall baroreflex system and a gain (GHR) of the baroreflex heart rate control system during quick mild hemorrhage and blood infusion were studied. G(AP) was decreased from 7.6 +/- 0.6 to 2.8 +/- 0.5 by alpha-hANP with hemorrhage. G(AP) decreased 7.4 +/- 0.8 to 2.9 +/- 0.4 by alpha-hANP with blood infusion. G(AP) was restored nearly to the control levels one hour after alpha-hANP administration. GHR did not change by alpha-hANP administration. In the second and third protocol, a site of action of alpha-hANP was analysed. alpha-hANP inhibited the responses of systemic vascular resistance to quick mild hemorrhage and blood infusion, but did not affect the responses of cardiac output to quick mild hemorrhage and blood infusion in the second protocol. After carotid sinus denervation and vagotomy, alpha-hANP inhibited an arterial pressure responses to phenylephrine and nitroglycerin bolus injection in the third protocol. These findings suggest that alpha-hANP has mainly an effect on the peripheral vascular system to decrease its responsiveness, resulting in a decrease in G(AP).

Anesthesia↗