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Biomedical subjects

S Uchida

Publications and source records attributed to S Uchida.

At least 415 records · Page 23Linked to original sources
PubMed1990

[Parasomnia associated with abnormal REM sleep in the aged].

Three aged patients (age 63-78 years) had 3-15-year histories of abnormal behaviors during nocturnal sleep. These three patients presented no other psychiatric problems. Polysomnographic recordings were carried out from 1-3 nights after adaptation. The patients were simultaneously monitored via a video system during the recording period. Various nocturnal behaviors, including laughing, weeping, the shaking of arms and getting up were detected during these recordings. These behaviors appeared exclusively during REM periods which were associated with a large amount of abnormal REM sleep lacking muscle atonia (d-STREM with EMG). NREM sleep architecture was intact and %SWS was within the normal limits per age for all the patients. The patients, manifesting such abnormal behaviors during sleep, could be aroused completely with awakening stimuli, and could recall in detail their unpleasant dreams. Two of the three were treated with clonazepam (0.5-1 mg/day) which immediately decreased the abnormal behaviors during sleep. Polysomnographic studies after the treatment showed a marked decrease in the d-STREM with EMG. The above results indicate that these abnormal behavior during nocturnal sleep were closely linked to d-STREM with EMG. And the administration of clonazepam not only led to an amelioration in the abnormal behaviors but also in the polysomnographic pathology. It is concluded that parasomnia in the aged is characterized by behavioral manifestations of the dreaming due to dysfunctions of the muscle atonia system.

Aged↗
PubMed1989

Molecular cloning of cDNA coding for kidney aldose reductase. Regulation of specific mRNA accumulation by NaCl-mediated osmotic stress.

Cells generally respond to long-term hyperosmotic stress by accumulating nonperturbing organic osmolytes. Unlike bacteria, in which molecular mechanisms involved in the increased accumulation of osmolytes have been identified, those in multicellular organisms are virtually unknown. In mammals, during antidiuresis, cells of the renal inner medulla are exposed to high and variable extracellular NaCl. Under these conditions, the cells contain a high level of sorbitol and other osmolytes which help balance the high extracellular osmolality. PAP-HT25 is a continuous line of cells derived from rabbit renal inner medulla. When medium osmolality is increased by raising the NaCl concentration, these cells accumulate sorbitol. The sorbitol is synthesized from glucose in a reaction catalyzed by aldose reductase. When the medium is made hyperosmotic, aldose reductase activity increases because of a larger increase in the amount of enzyme. This increase is produced by the accelerated rate of synthesis of aldose reductase protein. The purpose of the present studies was to examine the mechanism of this increase in aldose reductase protein by measuring the relative abundance of aldose reductase mRNA. A cDNA clone coding for rabbit kidney aldose reductase was isolated. Antisense RNA probes transcribed from this clone hybridized specifically with a 1.5-1.6 kilobase mRNA in Northern blots. Cells grown chronically in hyperosmotic medium had a relative abundance of this specific mRNA which was six times that of cells grown in isoosmotic medium. When cells grown in isoosmotic medium were switched to hyperosmotic medium, the level of aldose reductase mRNA peaked (18-fold) at 18-24 h. The induction of aldose reductase mRNA by osmotic stress was reversible. Our finding of increased abundance of a specific mRNA in direct response to hyperosmotic stress represents the first report of such an effect in animals.

Aldehyde Reductase↗
PubMed1989

The H-L subgroup of guinea-pig cardiac M2 receptors (M2 beta) regulates inositol phosphate formation.

In previous studies, we showed that cardiac muscarinic receptors (M2) are composed of two subgroups, M2 alpha and M2 beta, with different affinities for agonists and that the M2 alpha subgroup is coupled with inhibition of adenylate cyclase. We now studied which subgroup was responsible for the formation of inositol mono- (IP), bis- (IP2), tris- (IP3) and tetrakis- (IP4) phosphates in guinea pig heart. Carbachol (1 mM) significantly stimulated the formation of all four IPs in [3H]myoinositol-preloaded slices of guinea-pig ventricles. Acetylcholine (1 mM) also stimulated the formation of IP2, IP3 and IP4. However, oxotremorine (1 mM) only slightly stimulated the formation of IP2, and pilocarpine did not stimulate the formation of any IP. The pED50 values of carbachol for IP2 and IP3 formation were 3.76 and 4.23, respectively, which coincided with the pKd values of the low-affinity agonist binding site (L site) measured by competition of carbachol with [3H]quinuclidinyl benzilate [( 3H]QNB) binding while the pKd value for inhibition of adenylate cyclase coincided with the pKd value of the high-affinity agonist binding site (H site). Treatment of animals with pertussis toxin decreased the formation of IP2 and IP3 by carbachol to 66 and 54%, respectively, but resulted in complete inhibition of adenylate cyclase. These results suggested that muscarinic stimulation of the formation of IPs was manifested through a different receptor subgroup (M2 beta) and GTP binding protein different from those for inhibition of adenylate cyclase.

Acetylcholine↗
PubMed1989

Nephrotoxicity assessment by measuring cellular ATP content. I. Substrate specificities in the maintenance of ATP content in isolated rat nephron segments.

To clarify the characteristics of cellular ATP synthesis in individual nephron segments for assessing nephrotoxicity of chemicals, cellular ATP content was measured by the luciferin/luciferase system under various conditions using intact nephron segments isolated from male Sprague-Dawley rats. Increasing the duration of collagenase treatment of kidney slices significantly lowered the cellular levels of ATP newly synthesized from 2 mM glutamine in PST at 37 degrees C over 30 min (p less than 0.01). The tubular incubation time significantly affected the cellular ATP content in the early and middle portions (S2) of the proximal tubule (p less than 0.05 and p less than 0.01, respectively) over 20 min and in the late proximal tubule over 10 min. Among numerous substrates tested, such as D-glucose, glutamine, pyruvate, DL-lactate, and beta-hydroxybutyrate, the substrate utilization for maintaining cellular ATP content was entirely variable according to each nephron segment. Pyruvate and glutamine were the best substrates in the proximal tubule. On the other hand, ATP production from glutamine was less than that from the other substrates in the distally located nephron segments: medullary and cortical thick ascending limbs of Henle's loop (MAL and CAL, respectively), distal tubule, cortical and medullary collecting tubules (CCT and MCT, respectively). In general, glucose, pyruvate, and lactate appear to be equivalent in maintaining ATP content in the distal segments of renal tubules. A monovalent cation ionophore, monensin, at 10 micrograms/ml decreased the cellular ATP content in MAL, CAL, and MCT significantly. Mercuric chloride (HgCl2) was used as a model compound to study nephrotoxicity by investigating its effects on cellular ATP metabolism in microdissected nephron segments. HgCl2 at 1 x 10(-6) M significantly decreased ATP content only in S2 (p less than 0.05), clearly demonstrating S2 to be the most sensitive segment within the nephron. These results indicate that measurement of cellular ATP content would be a useful method forecasting the intrarenal toxic site and potency of possible nephrotoxic chemical compounds.

Adenosine Triphosphate↗
PubMed1989

N-methyl-D-aspartate-sensitive [3H]glutamate binding sites in brain synaptic membranes treated with Triton X-100.

Specific binding activity of radiolabeled L-glutamic acid, a putative central excitatory neutrotransmitter, was drastically increased with increasing concentrations of Triton X-100 used for pretreatment of rat brain synaptic membranes. The binding in these Triton-treated membranes was a protein dependent, inversely temperature-dependent, stereospecific, structure-selective and saturable process with a high affinity for the amino acid. The binding activity was invariably inhibited by agonists and antagonists for the N-methyl-D-aspartic acid (NMDA)-sensitive subclass, but not by agonists for the other subclasses of excitatory amino acid neurotransmitter receptors in the brain. Scatchard analysis revealed that the binding sites consisted of a single component with a Kd of 24.4 +/- 2.5 nM and a Bmax of 0.94 +/- 0.09 pmol/mg protein. Some endogenous tryptophan metabolites such as kynurenic acid and quinolinic acid also inhibited the binding. These results suggest that synaptic membranes may indeed contain the NMDA-sensitive receptors which are disclosed by Triton X-100 treatment.

Amino Acids↗
PubMed1989

Heterologous desensitization of bradykinin-induced phosphatidylinositol response and Ca2+ mobilization by neurotensin in NG108-15 cells.

The heterologous desensitization of the bradykinin (BK)-induced increase in intracellular Ca2+ concentration ([Ca2+]i) by neurotensin was studied in neuroblastoma x glioma hybrid NG108-15 cells. The addition of neurotensin to the cells resulted in an increase in [Ca2+]i and an increase in the formation of inositol phosphates in Ca2+-free medium. Pretreatment of the cells with neurotensin resulted in 43% decrease in the BK-induced increase of [Ca2+]i. The increase in [Ca2+]i induced by ionomycin, which causes Ca2+ release from the intracellular pool, was not decreased by pretreatment with neurotensin. This indicates that the inhibitory effect of neurotensin on the BK-induced increase of [Ca2+]i was not due to depletion of the intracellular Ca2+ pool. Pretreatment with neurotensin also caused a 47% decrease in the BK-induced formation of inositol trisphosphates (IP3). This decrease was not due to depletion of phosphatidylinositol bisphosphates. Neurotensin did not inhibit [3H]BK binding to cell membranes. These results show that neurotensin desensitizes the BK responses of NG108-15 cells, heterologously, perhaps by changes in phospholipase C and/or guanine nucleotide-binding protein (G-protein).

Animals↗
PubMed1989

Effects of calcitonin gene-related peptide on the adenylate cyclase system in cultured rat skeletal muscle cells.

Adenylate cyclase (AC) activity in skeletal muscle cells isolated from new born rats was increased with time in culture, indicating the presence of heterologous supersensitivity as in the case of denervation in vivo. The effect of addition of calcitonin gene-related peptide (CGRP) to the cultures of skeletal muscle cells on increase in the AC activity was studied. The increases in AC activity stimulated by CGRP, isoproterenol, NaF and forskolin were depressed by exposure to CGRP (1 microM) for 24 hours, depression of CGRP-stimulated AC activity being the greatest. The extent of reduction in increase in AC activity depended on the concentration of CGRP and duration of exposure. The AC activity stimulated by CGRP was also decreased by exposure to dbc-AMP for 24 hours. When muscle cells were exposed to CGRP for 3 days, no significant difference among the AC activity stimulated by NaF, forskolin and CGRP was seen. These results suggest that exposure to CGRP for one day caused mainly homologous desensitization of the CGRP receptor, whereas exposure for 3-4 days caused heterologous desensitization of the AC catalytic unit, perhaps by elevating the c-AMP level in the cells. These results imply that CGRP, which is located in the motor nerve terminal, may play a role as a physiological trophic factor on skeletal muscle.

Adenylyl Cyclases↗
PubMed1989

Increase in the amount of adenylate cyclase in rat gastrocnemius muscle after denervation.

After section of the sciatic nerve, the basal adenylate cyclase (AC) activity in rat gastrocnemius muscle increased 6-7 times per membrane protein and about 2 times per whole muscle in the following 30 or 40 days. The AC activity in the muscle 30 days after denervation was increased about 4 times by forskolin. Calcitonin gene-related peptide (CGRP) also increased the adenylate cyclase activity in the denervated muscle. The binding of [3H]-forskolin (10nM) to cells isolated from gastrocnemius muscle was examined to determine the amount of AC molecules. Inhibition of [3H]-forskolin binding by increasing amounts of unlabeled forskolin gave a sigmoid curve with a IC50 value of 3 x 10(-7) M. Results showed that the number of [3H]-forskolin binding sites per cell was higher on the denervated side than on the control side, like the basal AC activity. The IC50 values for inhibition by unlabeled forskolin of binding of [3H]-forskolin were similar to muscles on the control and denervated sides. These results suggest that an increase in the AC activity induced by denervation was due to an increase in the numbers of AC molecules in the muscle.

Adenylyl Cyclases↗
PubMed1989

[Clinical analysis of 17 cases of Japanese encephalitis experienced in the last ten years].

We studied on the prognosis-related factors on 17 cases of Japanese encephalitis experienced during the last ten years and compared the clinical features with those in previous reports, especially when the disease was prevalent. The patients, ranging from 33 to 91 years old, consisted of 7 men and 10 women. All of them showed an encephalitis type. 47.1% of the patients were completely cured, 35.3% cured with sequelae and 17.6% died. The mortality rate was decreased compared to that of previous reports. All of the death cases were women. There was no relationship between the mortality rate and the patients' age. As previously reported, the more severe the disturbance of consciousness, the higher the mortality was. However the rate of death was lower than that of previous reports. We conclude from this study that clinical features of the disease have changed when compared with that of the older days.

Adult↗
PubMed1989

Signal for induction of aldose reductase in renal medullary cells by high external NaCl.

GRB-PAP1 is a continuous line of epithelial cells derived from rabbit renal inner medulla. These cells accumulate large amounts of sorbitol when extracellular NaCl concentration is elevated. The accumulation involves an increase in aldose reductase, an enzyme that catalyzes production of sorbitol from glucose. The purpose of the present studies was to investigate the mechanism by which high NaCl triggers an increase in aldose reductase activity. When NaCl was added to increase medium osmolality from 300 to 500 mosmol/kg, enzyme activity began to increase after 12-24 h, was half-maximal in 2 days, and was maximal by 4 days. To test the effect of other solutes, medium osmolality was increased to 500 mosmol/kg by adding raffinose, urea, or glycerol. Raffinose increased aldose reductase activity as much as NaCl did. In contrast, neither urea nor glycerol affected the enzyme activity. NaCl and raffinose caused a sustained decrease in cell water content and an increase in cell sodium and potassium concentration, but urea did not. In some experiments, ouabain was added either with or without an increase in osmolality. Taking into account all of the experiments, with and without ouabain, we found that aldose reductase activity did not correlate with either cell sodium concentration or cell water content alone. It did correlate, however, with cell potassium concentration and even more strongly with the sum of cell sodium plus potassium concentration. We conclude that the signal by which hyperosmolality triggers an increase in aldose reductase activity most likely involves an increase in intracellular ionic strength.

Aldehyde Reductase↗