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Y Gotoh

Publications and source records attributed to Y Gotoh.

At least 163 records · Page 9Linked to original sources
PubMed1992

Electrophysiologic mechanisms responsible for inotropic responses to ketamine in guinea pig and rat myocardium.

Inotropic and electrophysiologic effects of ketamine were investigated in cardiac preparations isolated from guinea pigs and rats. Ketamine produced a concentration-dependent negative inotropic effect in electrically driven guinea pig papillary muscles, an effect that was accompanied by a decrease in action potential duration at the 0-mV level (APD0). In contrast, ketamine produced a concentration-dependent positive inotropic effect in rat left atria in the presence of 10(-6) M propranolol. The increase in force of contraction was accompanied by an increase in APD0. Experiments using patch clamp techniques revealed that ketamine reduced the transsarcolemmal Ca2+ current (ICa) as well as the inward rectifier K+ current and delayed outward K+ current in guinea pig single ventricular cells. These results indicate that the shortening of APD0 observed in guinea pig papillary muscles might result from the suppression of ICa. In rat single ventricular cells ketamine reduced the Ca(2+)-insensitive transient outward current (Ito) and did not enhance ICa, suggesting that the ketamine-induced prolongation of APD0 observed in rat left atria is due to a decrease in Ito rather than an increase in ICa. Treatment of rat left atria with the specific Ca(2+)-insensitive Ito inhibitor 4-aminopyridine (2 mM) produced a positive inotropic effect and prolongation of APD0, and these effects were equivalent to those caused by the highest concentration of ketamine. In the presence of 4-aminopyridine, ketamine failed to induce a positive inotropic effect and instead caused a negative inotropic one. In conclusion, the negative and positive inotropic effects of ketamine may result from the suppression of ICa and Ito, respectively. The inhibitory action on these membrane currents may at least in part explain the species and tissue differences in inotropic responses to ketamine.

Action Potentials↗
PubMed1991

Insulin and 12-O-tetradecanoylphorbol-13-acetate activation of two immunologically distinct myelin basic protein/microtubule-associated protein 2 (MBP/MAP2) kinases via de novo phosphorylation of threonine and tyrosine residues.

Two site-specific antibodies have been prepared by immunizing rabbits with chemically synthesized peptides derived from the partial cDNA-predicted amino acid sequence of extracellular signal-regulated kinase 1 (ERK1), which has been proposed to encode the microtubule-associated protein 2 (MAP2) kinase (Boulton, T. G., Yancopoulos, G. D., Gregory, J. S., Slauer, C., Moomaw, C., Hsu, J., and Cobb, M. H. (1990) Science 249, 64-67). With immunoprecipitation in the presence of sodium dodecyl sulfate (SDS) and Western blotting, an antibody to the peptide containing triple tyrosine residues (alpha Y91) resembling one of the insulin receptor autophosphorylation sites specifically recognized 42- and 44-kDa proteins. On the other hand, an antibody to the peptide corresponding to the COOH terminus portions (alpha C92) of the ERK1 cDNA gene product recognized the 44-kDa protein much more efficiently than the 42-kDa protein. With immunoprecipitation in the absence of SDS, alpha Y91 could barely recognize these two proteins and alpha C92 recognized the 44-kDa protein but failed to recognize the 42-kDa protein. Kinase assays in myelin basic protein (MBP)-containing gel, after SDS-polyacrylamide gel electrophoresis, revealed that insulin or 12-O-tetradecanoylphorbol-13-acetate (TPA)-stimulated MBP kinase activity in alpha Y91 immunoprecipitates comigrated at molecular mass 42 and 44 kDa. On the other hand, the stimulated MBP kinase activity in alpha C92 immunoprecipitates comigrated only at molecular mass 44 kDa. Insulin stimulated the MBP kinase activity in gels and phosphorylation of these two proteins by greater than 10-fold with a maximal level at 5 min. Insulin and TPA rapidly stimulate the phosphorylation of the 42- and 44-kDa proteins via de novo threonine and tyrosine phosphorylation. Tryptic phosphopeptide mapping analysis of the 42- and 44-kDa proteins, respectively, revealed a single major phosphopeptide containing phosphothreonine and phosphotyrosine, which was common to both insulin- and TPA-stimulated phosphoproteins. Protein phosphatase 2A treatment of these two phosphoproteins caused a complete loss of kinase activity with selective dephosphorylation of phosphothreonine. These data strongly suggest that these two proteins are highly related to the mitogen-activated protein (MAP) kinase with an apparent molecular mass of 42 kDa (Ray, L. B., and Sturgill, T. W. (1988) Proc. Natl. Acad. Sci. U.S.A. 85, 3753-3757) and that these two immunologically similar but distinct MBP/MAP2 kinases may represent isozymic forms of MBP/MAP2 kinases. These data also demonstrate that insulin and TPA activate MBP/MAP2 kinase activity by de novo phosphorylation of threonine and tyrosine residues via a very similar pathway.

Amino Acid Sequence↗
PubMed1991

Characterization of a cDNA for chicken osteopontin: expression during bone development, osteoblast differentiation, and tissue distribution.

The chicken bone phosphoprotein (approximately 66-kDa BPP) is a major noncollagenous component of bone and is the major phosphoprotein synthesized by cultured chicken embryo osteoblasts [Gotoh, Y., Gerstenfeld, L. C., & Glimcher, M. J. (1990) Eur. J. Biochem. 87, 49-58]. A cDNA clone for this protein was isolated from an expression library made from embryonic chicken bone mRNA. The complete primary protein sequence of 264 amino acids was deduced from the cDNA sequence inclusive of a 16 amino acid signal peptide sequence and terminated by 4 in-frame stop sequences. A sequence alignment indicated an approximate 35% overall similarity in protein sequence between the avian approximately 66-kDa BPP and the mammalian protein osteopontin, while at the nucleotide level 60% similarity was observed. Features of this sequence which showed the greatest similarity to mammalian osteopontin included a region in which seven of nine consecutive residues are aspartic acid, a recognition sequence for integrin-mediated cell binding (-Arg-Gly-Asp), and four possible recognition sequences for phosphorylation by casein kinase II. Hybridization analysis indicated a message of 1.5 kb found predominantly in bone and kidney. The mRNA was inducible in phorbol ester treated primary cultures of chondrocytes which show no expression under normal growth conditions. A temporal induction was seen during osteoblastic differentiation both in vivo and in vitro, thus suggesting that regulation of the approximately 66-kDa BPP is under transcriptional control during osteoblast development. In summary, both the protein's primary structure and its biological features suggest that it is the avian homologue to mammalian protein osteopontin.

Amino Acid Sequence↗
PubMed1991

In vitro effects on microtubule dynamics of purified Xenopus M phase-activated MAP kinase.

The protein kinase MAP kinase, also called MAP2 kinase, is a serine/threonine kinase whose activation and phosphorylation are induced by a variety of mitogens, and which is thought to have a critical role in a network of protein kinases in mitogenic signal transduction. A burst in kinase activation and protein phosphorylation may also be important in triggering the dramatic reorganization of the cell during the transition from interphase to mitosis. The interphase-metaphase transition of microtubule arrays is under the control of p34cdc2 kinase, a central control element in the G2-M transition of the cell cycle. Here we show that a Xenopus kinase, closely related to the mitogen-activated mammalian MAP kinase, is phosphorylated and activated during M phase of meiotic and mitotic cell cycles, and that the interphase-metaphase transition of microtubule arrays can be induced by the addition of purified Xenopus M phase-activated MAP kinase or mammalian mitogen-activated MAP kinase to interphase extracts in vitro.

Animals↗
PubMed1991

Xenopus M phase MAP kinase: isolation of its cDNA and activation by MPF.

MAP kinase is activated and phosphorylated during M phase of the Xenopus oocyte cell cycle, and induces the interphase-M phase transition of microtubule dynamics in vitro. We have carried out molecular cloning of Xenopus M phase MAP kinase and report its entire amino acid sequence. There is no marked change in the MAP kinase mRNA level during the cell cycle. Moreover, studies with an anti-MAP kinase antiserum indicate that MAP kinase activity may be regulated posttranslationally, most likely by phosphorylation. We show that MAP kinase can be activated by microinjection of MPF into immature oocytes or by adding MPF to cell-free extracts of interphase eggs. These results suggest that MAP kinase functions as an intermediate between MPF and the interphase-M phase transition of microtubule organization.

Amino Acid Sequence↗
PubMed1991

Effects of fixation and demineralization on the retention of bone phosphoprotein and other matrix components as evaluated by biochemical analyses and quantitative immunocytochemistry.

Aqueous tissue processing and demineralization procedures may adversely affect the inorganic mineral phase of a calcified sample and, where mineral and organic constituents interact, may consequently also indirectly alter organic matrix ultrastructure and distribution. In the present work, the effects of demineralization have been investigated on the retention in chicken bone of two phosphoamino acids, O-phosphoserine and O-phosphothreonine, found in bone phosphoproteins proposed to be important in vertebrate mineralization and, more specifically, on the retention and distribution of a 66 kD bone phosphoprotein (66 kD BPP, osteopontin) also implicated in the calcification process. In tibiae fixed initially with 1% glutaraldehyde and then demineralized in 0.5 N HCl, 0.5 N acetic acid, or 0.1 M EDTA (all containing 1% glutaraldehyde), amino acid analyses and quantitative immunocytochemistry revealed that the phosphoamino acid content and the distribution of the 66 kD BPP were essentially the same as in fixed undemineralized controls. However, demineralization slightly altered the ultrastructural appearance of immunolabeled, electron-dense patches of organic material in the bone matrix. In unfixed bone demineralized with any of these acids, there was a substantial loss of phosphoamino acids and the 66 kD BPP from the bone matrix. The relative ability of these acids to extract phosphoproteins from unfixed bone was found to decrease in the order EDTA greater than HCl greater than acetic acid. These results emphasize the differential effects on structural components of various demineralization and extraction procedures for biochemical and immunocytochemical studies of biologic tissues. Furthermore, they demonstrate that initial fixation with glutaraldehyde retains phosphoproteins in bone, with or without demineralization, while being adequate for immunocytochemical localization of certain bone matrix proteins and that an understanding of the action of specimen preparation on organic constituents (as well as inorganic components) is essential for accurately describing ultrastructural matrix-mineral relationships.

Amino Acids↗
PubMed1991

Immunohistochemical localization of a approximately 66 kD glycosylated phosphoprotein during development of the embryonic chick tibia.

Localization of a approximately 66 kD glycosylated phosphoprotein during morphogenesis of the embryonic chick tibia has been accomplished using immunohistochemistry. Although initial expression of the tibial osteoblast phenotype is detected as early as stage 28.5, with the deposition of osteoid matrix beginning at stage 30, little or no immunoreactivity against the approximately 66 kD glycosylated phosphoprotein is observed in pre-osteoblasts, osteoblasts, osteocytes, or in the uncalcified osteoid matrix during the early events of tibia development. Immunoreactivity was first observed at stage 32 when mineralization of the osteoid matrix is initiated. At this and all later stages, the phosphoprotein is located almost exclusively in the extracellular matrix at the mineralization front with essentially no detectable staining in the adjacent unmineralized osteoid matrix. Similarly, no cellular staining is observed when even the lightly mineralized extracellular matrix is strongly immunoreactive. Only scant immunostaining is present over the heavily mineralized regions, although demineralization of these areas with EDTA exposes a low intensity, punctate staining pattern. Additionally, cryosections of developing calvaria stained with this antiserum only display reactivity in regions of bone matrix undergoing mineralization. These localization studies support the hypothesis that this phosphoprotein is intimately associated with the process of bone matrix mineralization in the developing chick long bone.

Animals↗
PubMed1991

Inhibition of transient outward K+ current by DHP Ca2+ antagonists and agonists in rabbit cardiac myocytes.

The 1,4-dihydropyridine (DHP) Ca2+ antagonists and agonists can inhibit a time- and voltage-dependent, but intracellular Ca(2+)-independent transient outward K+ current (It), in myocytes from rabbit atrium. In the presence of 0.3 mM CdCl2, DHPs decreased the peak It slightly and markedly accelerated its apparent rate of inactivation. When the inhibition of It was measured from integrated It records, the 50% inhibitory concentrations (IC50) of nicardipine and BAY K 8644 were 630 nM and 7 microM, respectively, and the IC50 of nicardipine for inhibition of the Ca2+ current (ICa) was only approximately fourfold lower (160 nM). The inhibition of It by nicardipine was not affected by changing holding potential from -55 to -100 mV; in contrast, the inhibitory effect on ICa was significantly reduced by this hyperpolarization. We conclude that the DHP Ca2+ antagonist nicardipine blocks It at similar doses to those that block ICa and that nicardipine blocks this K+ current by mechanism different from that for ICa inhibition. This inhibitory effect on It is shared by other DHP compounds; the rank order for potency of It inhibition is nicardipine greater than benidipine greater than nisoldipine greater than BAY K 8644 greater than nitrendipine greater than nifedipine.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1991

Transurethral treatment of bladder diverticula.

We performed transurethral fulguration of the diverticular mucosa and incision of the diverticular neck in combination with transurethral prostatectomy or bladder neck resection to treat all aspects of diverticula in 9 patients. Eight cases with bladder outlet obstruction, involving 2 cases of large diverticula, have been successfully treated. A case with neurogenic bladder has failed. We found the transurethral procedure to be equally effective as open operation.

Aged↗
PubMed1991

Enzyme labeling in steroid enzyme immunoassays. Comparison of the p-nitrophenyl ester and N-succinimidyl ester methods.

Enzyme labeling of steroids by the p-nitrophenyl ester method was investigated in comparison with the N-succinimidyl ester method. The active ester of a testosterone or 11-deoxycortisol derivative was treated with beta-galactosidase and horseradish peroxidase to give labeled antigens. Various molar ratios of steroid to enzyme and pH conditions were tested. Satisfactory immunoreactivities with an anti-steroid antibody in each enzyme immunoassay system were obtained with the labeled antigens prepared at pH 8.5 by the use of molar ratios higher than 30. The enzyme labeling method should be useful in the case of polar steroids or drugs, since the p-nitrophenyl ester is relatively stable when compared with the N-succinimidyl ester.

Esters↗
PubMed1991

[The responses of somatosensory evoked potentials and cerebral blood flow to acetazolamide in patients with occlusive carotid disease].

The correlation between somatosensory evoked potential (SEP) and regional cerebral blood flow (rCBF) changes after acetazolamide administration was studied in six patients presented with transient ischemic attack (TIA) or minor completed stroke. All patients had no or only localized low density area on computed tomography, and severe occlusive disease in the ipsilateral common or internal carotid artery on cerebral angiography. In two patients with internal carotid artery occlusion, both marked decrease in ipsilateral N20 amplitude and prolongation of ipsilateral N20 latency were observed from 5-10 minutes after acetazolamide injection. These changes gradually improved and resolved 30-45 minutes after acetazolamide injection. In these cases, stable xenon CT revealed paradoxical rCBF decrease in the territory of the ipsilateral middle cerebral artery after acetazolamide injection. Especially, rCBF in the ipsilateral centrum semiovale fell to less than 20 ml/100 g/min. The other patients showed no change in SEPs and no paradoxical decrease in rCBF after acetazolamide injection. These results suggest that SEP test with acetazolamide loading could be valuable to evaluate a certain group of the patients with severely disturbed cerebral perfusion reserve in the carotid territory and suitable candidate for extracranial-intracranial arterial bypass (EC/IC bypass), although further investigations is needed.

Acetazolamide↗
PubMed1991

[SEP monitoring during balloon occlusion test or operation for vertebro-basilar aneurysms].

SEP (somatosensory evoked potential) monitoring was carried out on seven patients with vertebro-basilar aneurysms during balloon occlusion test, during operation, or after operation. In the patient (case 5) with basilar tip aneurysm, the amplitude of N20 remarkably decreased and this finding closely correlated with disturbed consciousness during transient balloon occlusion of the basilar artery. In another patient (case 6) with vertebral dissecting aneurysm, cerebellar retraction caused transient prolongation of N20 latency during operation. In another case, postoperative SEP monitoring revealed marked reduction of N20 amplitude in the patient (case 7) who showed disturbed consciousness and bilateral oculomotor palsy after operation for basilar aneurysms, but who showed no abnormality in postoperative ABR (auditory evoked brainstem response). The other four patients showed no neurological deterioration and no SEP change during transient balloon occlusion of the parent arteries. Because of the high rate of "false-negative" findings, it remains unclear whether SEP monitoring during surgery for vertebrobasilar aneurysms is of value to predict postoperative deficit due to brainstem ischemia. In our study, however, the changes of SEP were well correlated with neurological deterioration and/or the location of postoperative infarction. In conclusion, SEP monitoring during balloon occlusion tests or operations for vertebro-basilar aneurysms is considered to be useful in predicting ischemic complication of the brainstem caused by the occlusion of the parent artery. However other methodologies have to be developed in order to monitor the pyramidal tract and reticular activating system of the brainstem more accurately.

Adolescent↗
PubMed1991

[Differential lung ventilatory management during bronchoplasty].

We compared two methods of respiratory managements during bronchoplasty surgery. In one lung ventilation group (OLV-G), 10 patients were ventilated with Broncho-cath tube or Univent tube. On another 10 patients, ventilation was performed with Univent tube following insertion of bronchial blocker into main bronchus of dependent lung. Dependent lung was then ventilated using high frequency jet ventilation (HFJV) through bronchial blocker superimposed with low tidal volume IPPV (selective HFJV, S-HFJV-G). Oxygenation index (O.I.) of S-HFJV-G was significantly higher than that of OLV-G when bronchus was open. These phenomena might have occurred through prevention of pulmonary blood flow shift to the non-dependent lung when S-HFJV was used.

Aged↗
PubMed1991

[Early stellate ganglion block failed to prevent progress of facial nerve palsy in a patient with Ramsay-Hunt syndrome--a case report].

A 73-year-old man complained of pain in his right ear with vesicular lesion for three days. He complained of no weakness of facial musculatures, but muscle test revealed slight weakness in orbital and oral muscles on admission. His hearing acuity of the left ear was intact. Vertigo with spontaneous nystagmus to left was complained. The patient was treated with stellate ganglion block four times a day, prednisolone 80 mg a day p.o. and acyclovir i.v. Mannitol solution 300 ml a day for eight days was given i.v. to reduce edema and to protect facial nerve. On his 3rd hospital day, his paralysis progressed and he could not close his eye or whistle with his mouth. Evoked myogram showed 91% impairment of the nerve. During recovery period there was discrepancy between facial palsy score of clinical signs and degree of nerve impairment by evoked myogram. On his 12th hospital day his facial nerve score improved 9 to 12 (0 complete paralysis, 40 no paralysis) but evoked myogram showed further progress of nerve impairment from 86% to 91% (Evoked wave heights were 14% and 9% of normal site respectively). The discrepancy is probably because facial palsy score reflects also neurapraxia of inflammatory nerve, and stellate ganglion block has no effect on changing course of facial nerve injury.

Aged↗
PubMed1991

[Gas chromatographic determination of residual ethylene oxide in the endotracheal tube].

An accurate and simplified method has been developed for determination of residual ethylene oxide (EO) in the endotracheal tube using gas chromatography with a head space sampler. The endotracheal tube made of polyvinyl chloride was sterilized with EO and aerated. Residual EO after aeration was 6630 +/- 1915 ppm (mean +/- SD). It decreased to 72 +/- 46 ppm on 7th day. The endotracheal tube should be left unused for more than 7 days after sterilization and aeration. The safety level of residual EO in the endotracheal tube by U.S.FDA regulation is less than 250 ppm. The concentration of residual EO should be lower than 250 ppm, if this rule is observed.

Chromatography, Gas↗
PubMed1990

Comparison of two phosphoproteins in chicken bone and their similarities to the mammalian bone proteins, osteopontin and bone sialoprotein II.

Two phosphorylated proteins of approximately 66 kDa and approximately 60 kDa mass with different DEAE-Sephacel elution patterns were isolated from chicken bone and were shown to be genetically distinct by both biochemical and immunological analysis. A tryptic peptide from the 60 kDa protein was identified that was similar to a sequence of the rat bone sialoprotein II. Both proteins showed RGD inhibited cell-attachment with the MG-63 osteosarcoma cell, and the approximately 66 kDa phosphoprotein appeared to promote cell adhesion better than human vitronectin. The two phosphoproteins appear to share functional and biochemical characteristics and to be homologous to the mammalian bone phosphoproteins, osteopontin and bone sialoprotein II.

Amino Acid Sequence↗