Search PubMed⌕ Search

Biomedical subjects

Y Kondo

Publications and source records attributed to Y Kondo.

At least 559 records · Page 31Linked to original sources

Single retinal ganglion cells sending axon collaterals to the bilateral superior colliculi: a fluorescent retrograde double-labeling study in the Japanese monkey (Macaca fuscata).

Single retinal ganglion cells projecting bilaterally to the superior colliculi (SC) by way of axon collaterals were revealed in the Japanese monkey (Macaca fuscata). After injecting Fast blue into the SC on one side and Diamidino yellow into the SC on the opposite side, some retinal ganglion cells were double-labeled with both tracers. Most of them were large cells (more than 25 microns in diameter), and were localized in a narrow strip around the vertical meridian of the retina on each side. This retinal area roughly corresponds to the reported strip of nasotemporal overlap, where both crossed and uncrossed retinofugal projections arise.

Amidines↗

[Difference of acute ketone body metabolism between insulin-dependent diabetic and non-insulin-dependent diabetic individuals].

The difference in the acute metabolic change in ketone bodies between patients with insulin-dependent diabetes mellitus (IDDM) and non-insulin-dependent diabetes mellitus (NIDDM) was investigated in this study. The subjects employed were 7 patients with IDDM losing residual insulin secretion and 7 patients with NIDDM matched to the former patients for age, body mass index, duration of diabetes, daily insulin dosage, fasting plasma glucose and HbA1c. Blood samples were drawn at 3A.M. and 7A.M. on the same day, and plasma glucose, acetoacetic acid (AcAc), 3-beta-hydroxybutylic acid (3-OHBA), free fatty acid (FFA), glycerol, cortisol and growth hormone (GH) concentrations were determined. Plasma total ketone bodies (AcAc and 3-OHBA), 3-OHBA and FFA concentrations at 7A.M. were significantly higher in the patients with IDDM than in those with NIDDM (p < 0.05), while there were no significant differences in any other parameters at 3A.M. between the patients with IDDM and those with NIDDM. The ratios of 7A.M. value/3A.M. value of total ketone bodies, AcAc and 3-OHBA concentrations were also more significantly elevated in the patients with IDDM than in those with NIDDM. It was observed that the ratio of 3-OHBA was more than 2.0 in all of the patients with IDDM and less than 2.0 in all of the patients with NIDDM, the difference being significant with p < 0.001.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Characterization of ATP receptor which mediates norepinephrine release in PC12 cells.

PC12 cells, a rat pheochromocytoma cell line, has been reported to release norepinephrine in response to extracellular ATP in the presence of extracellular Ca2+. The potency order of ATP analogues was adenosine 5'-O-(3-thiotriphosphate) greater than ATP greater than adenosine 5'-O-(1-thiotriphosphate) = 2-methylthioadenosine 5'-triphosphate (MeSATP) greater than 2'- and 3'-O-(4-benzoyl-benzoyl)ATP (BzATP) greater than ADP greater than 5-adenylylimidodiphosphate. Adenosine 5'-O-(2-thiodiphosphate), beta, gamma-methyleneadenosine 5'-triphosphate, AMP and adenosine were inactive. The ATP action in the absence of extracellular Ca2+, suggests a small but appreciable contribution of intracellular Ca2+ mobilization, for norepinephrine release. However, for some ATP derivatives, like BzATP, almost no contribution of the phospholipase C-Ca2+ pathway is suggested, based on their low activity in inositol phosphates production. To identify the ATP-receptor protein, PC12 cell membranes were photoaffinity-labeled with [32P]BzATP. SDS-PAGE analysis showed that a 53-kDa protein labeling was inhibited by ATP and its derivatives, as well as by P2-antagonists, suramin and reactive blue 2, which inhibit the nucleotide-induced norepinephrine release. The inhibitory activity of the nucleotides was, in parallel with their potency, to induce norepinephrine release. Despite their inability to release norepinephrine, GTP and GTP gamma S inhibited the BzATP labeling, suggesting the participation of a putative G protein in the ATP-receptor-mediated actions. We suggest that the 53-kDa protein on the PC12 cell surface is an ATP receptor, which mediates the norepinephrine release, depending, mainly, on extracellular Ca2+ gating.

Adenosine Triphosphate↗

P2 purinoceptor-mediated cyclic AMP accumulation in bovine vascular smooth muscle cells.

Extracellular ATP has been shown to induce intracellular Ca2+ mobilization and adenylate cyclase inhibition via P2 purinoceptors in several species of cells. Now we found that in calf vascular smooth muscle cells the addition of ATP to the medium did not induce inhibition but stimulation of cyclic AMP accumulation, in addition to stimulation of inositol phosphate production. Adenosine and AMP also induced cyclic AMP accumulation but their efficacy was much less than that of ATP. The ATP action was not influenced by the presence of either adenosine deaminase or of an ATP regenerating system, whereas the AMP action was increased by the regenerating system. The results indicate that the cyclic AMP accumulation by ATP is due to ATP itself but neither to adenosine nor to AMP, both of which are produced from ATP. ATP receptor coupled to the cyclic AMP generation was shown to be different from that coupled to phospholipase C based on the difference in the potency order of the receptor agonists and in the sensitivity of P2 receptor agonists to 8-cyclopentyl-1,3-dipropylxanthine (CPX)- and suramin-induced antagonism. We conclude that in the aortic smooth muscle cells a novel P2-type receptor directly coupled to adenylate cyclase activation exists in addition to the previously known P2 receptor linked to phospholipase C activation.

Adenosine Triphosphate↗

Detection and time-course analysis of phospholipid hydroperoxide in soybean seedlings after treatment with fungal elicitor, by chemiluminescence-HPLC assay.

Direct evidence for the existence of phosphatidylcholine hydroperoxide (PCOOH) and the determination of the changes in PCOOH after treatment of soybean seedlings with fungal elicitor, were examined using chemiluminescence-HPLC of hydroperoxide specific assay. PCOOH was transiently accumulated within 6 h after elicitor treatment but such an event was not observed in control plants, thus suggesting that accumulation of PCOOH was a response to fungal elicitor in the host plant. The result suggested that singlet oxygen had participated in the lipid hydroperoxidation, since non-conjugated fatty acid hydroperoxide isomers due to the singlet oxygen oxidation were detected in the phospholipid fraction. The reaction of lipid hydroperoxidation, preceding the induction of a defense compound, may be involved in the triggering of a plant defense mechanism against fungal invasion.

Benzopyrans↗

cDNA cloning of a novel heterogeneous nuclear ribonucleoprotein gene homologue in Caenorhabditis elegans using hamster prion protein cDNA as a hybridization probe.

The mammalian prion protein (PrPc) is a cellular protein of unknown function, an altered isoform of which (PrPsc) is a component of the infectious particle (prion) thought to be responsible for spongiform encephalopathies in humans and animals. The evolutionary conservation of the PrP gene has been reported in the genomes of many vertebrates as well as certain invertebrates. In the genome of nematode Caenorhabditis elegans, the sequence capable of hybridizing with the mammalian PrP cDNA probe has been demonstrated, predicting the presence of the PrP gene homologue in C.elegans. In this study, Southern analysis with the hamster PrP cDNA (HaPrP) probe confirmed the previous observation. Moreover, Northern analysis revealed that the sequence is actively transcribed in adult worms. Thus, we screened C.elegans cDNA libraries with the HaPrP probe and isolated a cDNA that hybridizes to the same sequence in C.elegans that hybridized with the HaPrP probe in the Southern and Northern analyses. The deduced amino acid sequence of this cDNA, however, is substantially homologous with heterogeneous nuclear ribonucleoprotein (hnRNP) core proteins rather than mammalian PrPc. The hnRNPs contain the glycine-rich domain in the C-terminal half of the molecule, which also seemed to be in PrPc at the N-terminal half of the molecule. Both of the glycine-rich domains are composed of tracts with high G + C content, indicating that these tracts may due to the hybridizing signals. These results suggest that this cDNA clone is derived from a novel hnRNP gene homologue in C.elegans but not from a predicted PrP gene homologue.

Amino Acid Sequence↗

Discrimination between two types of P2 purinoceptors by suramin in rat hepatocytes.

Suramin, currently reported as a P2 purinoceptor antagonist, competitively inhibited P2 purinoceptor agonist-induced phospholipase C (PLC) stimulation, but not P2 purinoceptor agonist-induced adenylate cyclase (AC) inhibition in rat hepatocytes. Suramin did not inhibit vasopressin-induced PLC activity. We conclude that there are two types of P2 purinoceptors; one is suramin-sensitive and coupled to PLC in a stimulatory manner, and the other is suramin-insensitive and coupled to AC in an inhibitory manner.

Adenylyl Cyclase Inhibitors↗

[The possibility of hereditary factors in the susceptibility to diabetic nephropathy in NIDDM].

Diabetic nephropathy is the most important complication of diabetes, because it is a major cause of morbidity and mortality for diabetic subjects. Since not all subjects with diabetes are at risk of developing this complication, we conducted a study to determine if heredity might be a possible risk factor for diabetic nephropathy in non-insulin dependent diabetes. Twenty-one factors including inheritance of nephropathy and hypertension were investigated in 109 individuals with NIDDM: 50 patients without proteinuria (Group I), 20 patients with intermittent proteinuria (Group II), and 39 patients with continuous proteinuria (Group III) matched for age and duration of diabetes. Of those patients, 55 patients with inheritance of diabetes were also divided into three groups: 29 patients without proteinuria (Group I), 9 patients with intermittent proteinuria (Group II), and 17 patients with continuous proteinuria (Group III). Individuals in Groups II and III has significantly higher frequency of inheritance of diabetic nephropathy than those in Group I, and also individuals with inheritance of diabetic nephropathy had significantly higher frequency of diabetic nephropathy than those without it. Frequency of hypertension, retinopathy and body mass index in the past were significantly higher in subjects in Groups II or Group III than in those in Group I. There were no significant differences between subjects in Groups II and III. These findings suggest that susceptibility to diabetic nephropathy in NIDDM may be hereditary, although hypertension and obesity may also be important risk factors for diabetic nephropathy.

Aged↗

Biliary cystadenocarcinoma of the liver. A clinicopathologic and histochemical evaluation of nine cases.

Nine cases of biliary cystadenocarcinoma of the liver were studied, with emphasis on its clinicopathologic features, mucin profiles, and immunohistochemical characteristics. In general, the cystic tumors had protrusions that consisted of well-differentiated papillary adenocarcinoma cells with or without benign-appearing epithelial elements. In invading or metastatic foci, the carcinoma cells tended to show distinctive anaplastic changes. Tumor growth was confined to the cystic lesions in five cases (noninvasive type), whereas in four cases it extended to the hepatic parenchyma or neighboring organs (invasive type). There was a considerable difference between the two groups in terms of prognosis. In fact, the patients included in the group with the noninvasive type had no sign of tumor recurrence after an appropriate surgical procedure. With mucin histochemical and immunohistochemical approaches, positive reactions with carcinoembryonic antigen, tissue polypeptide antigen, carbohydrate 19-9, and Dupan-2 and the predominance of sialomucin were observed in most cases of biliary cystadenocarcinoma, indicating a similar cellular nature of cholangiocarcinoma.

Adenoma, Bile Duct↗

Synergism in cytosolic Ca2+ mobilization between bradykinin and agonists for pertussis toxin-sensitive G-protein-coupled receptors in NG 108-15 cells.

Bradykinin (BK) induced a transient and pertussis toxin (PT)-insensitive increase in cytosolic Ca2+ ([Ca2+]i) in NG 108-15 neuroblastoma x glioma hybrid cells, whereas leucine-enkephalin (EK), somatostatin, norepinephrine or carbachol showed a weak but PT-sensitive action. When any one of the latter agonists was applied to the cells treated with low doses of BK, however, the level of [Ca2+]i rise caused by the agonist was remarkably increased in a PT-sensitive manner. The decreasing of extracellular Ca2+ only slightly influenced the actions of these agonists. Thus, synergism between a BK receptor and PT-sensitive G-protein-coupled receptors results in marked intracellular Ca2+ mobilization by the latter agonists.

Bradykinin↗

Extracellular ATP stimulates three different receptor-signal transduction systems in FRTL-5 thyroid cells. Activation of phospholipase C, and inhibition and activation of adenylate cyclase.

In FRTL-5 thyroid cells, extracellular ATP, a P2-agonist, not only stimulates phospholipase C but also inhibits forskolin- or thyrotropin (TSH)-induced stimulation of adenylate cyclase in a pertussis toxin-sensitive manner [Okajima, Sato, Nazarea, Sho, & Kondo (1989) J. Biol. Chem. 264, 13029-13037]. We have now found that, in pertussis toxin-treated cells, ATP can directly stimulate adenylate cyclase. Although adenylate cyclase modulation occurs through ATP metabolites such as AMP and adenosine, we show that extracellular ATP itself also regulates cyclic AMP production, based on the following: (1) the actions of ATP were imitated by hydrolysis-resistant ATP analogues, (2) the elimination of adenosine by adenosine deaminase decreased the effect of ATP only partially, at least at concentrations greater than 10 microM-ATP, and (3) the amount of AMP produced from ATP was too low to account for the ATP effects. To identify the respective receptors for the three different actions of ATP, we established an antagonist profile. Suramin, which has been reported to be a P2-receptor antagonist, inhibited ATP-induced phospholipase C activation in a competitive fashion, but did not affect ATP-induced adenylate cyclase modulation. On the other hand, 8-cyclopentyl-1,3-diphenylxanthine competitively antagonized both the stimulatory and inhibitory ATP actions on cyclic AMP levels, but did not influence the activation of phospholipase C by ATP. The order of potency for various xanthine derivatives was clearly different with respect to their antagonistic effects on the stimulation and inhibition of adenylate cyclase induced by ATP. We conclude that ATP activates three receptors, each of which is coupled to a different signal transduction system in FRTL-5 cells, i.e. phospholipase C activation, and adenylate cyclase activation and inhibition.

Adenosine Triphosphate↗

Intranasal aerodynamic aspects in patients with nasal septal perforations.

In an attempt to determine the influence of septal perforations on nasal airflow, nasal resistances were measured with active posterior rhinomanometry and compared before and after closure of asymptomatic septal perforations in five patients. No significant differences were found in the nasal resistances before and after closure of perforations either on inspiration or expiration. All patients were also unaware of any perceptive changes in nasal patencies after closure of the perforations.

Aged↗

Increase of S-(1,2-dicarboxyethyl)glutathione in regenerating rat liver.

Changes in the level of S-(1,2-dicarboxyethyl)glutathione (DCE-GS) with time were determined during regeneration of rat liver after partial hepatectomy. The DCE-GS level increased in regenerating rat liver, reaching a maximum level (4.7-fold) on day 2 and reverted to the normal level in 1 week. During the liver regeneration process, the activity of DCE-GS-synthesizing enzyme in the liver retained its control level, while the level of glutathione--a substrate of the enzyme in the liver--fluctuated in parallel with that of DCE-GS.

Animals↗

Lesions of the medial amygdala produce severe impairment of copulatory behavior in sexually inexperienced male rats.

The effects of amygdaloid lesions on masculine copulatory behavior were examined in male rats. Sexually inexperienced male rats were castrated and subjected to bilateral lesions in one of the following areas: the medial amygdala, the cortical amygdala, or the basolateral amygdala. Three weeks later, all rats received implantation of silastic capsules containing testosterone. Then, four observations of copulatory behavior were carried out every 5 days following the implantation of testosterone. Rats with medial amygdala lesions showed a severe deficit of copulatory behavior, whereas rats with basolateral amygdala lesions showed no change in the performance of copulation. As for rats with cortical amygdala lesions, although their copulatory behavior was impaired, the effect was confined to a deficit in intromission and ejaculation responses. These findings suggest that the medial amygdala plays a critical role in regulating masculine sexual behavior in the rat.

Amygdala↗

Selective inhibition of T-cell-dependent immune responses by bisbenzylisoquinoline alkaloids in vivo.

The bisbenzylisoquinoline (BBI) alkaloids, chondocurine, tetrandrine, isotetrandrine and cepharanthine, were tested for immunosuppressive activity in mice. A plaque-forming cell (PFC) response to a T-cell-dependent antigen, sheep red blood cell, was significantly suppressed by a 7 day treatment of chondocurine or tetrandrine at 1 mg/kg/day and of isotetrandrine at 50 mg/kg/day, but not suppressed by cepharanthine treatment. The suppressive effect of chondocurine was greater when it was given after immunization rather than before or concurrently. However, it did not affect the PFC response to a T-cell-independent antigen, lipopolysaccharide. A delayed-type hypersensitivity was also suppressed by chondocurine treatment. There was no significant change in lymphocyte number and proportion of T-cell subsets in the BBI alkaloid-treated mice. These data suggest that there is selective inhibition by chondocurine and tetrandrine of the T-cell-dependent immune reactions.

Alkaloids↗