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T Kuno

Publications and source records attributed to T Kuno.

At least 109 records · Page 6Linked to original sources
PubMed1991

cDNA cloning of a novel testis-specific calcineurin B-like protein.

A cDNA clone encoding a novel calcineurin B-like protein (CBLP) was isolated from a rat testis cDNA library by cross-hybridization with a calcineurin B cDNA probe. CBLP is composed of 176 amino acids and contains four putative Ca(2+)-binding domains. The overall predicted amino acid sequence homology between CBLP and calcineurin B is 82%. Northern blots showed that transcripts for CBLP are specifically and highly expressed in the testis.

Amino Acid Sequence↗
PubMed1991

Expression of the GABAB receptor in Xenopus oocytes and inhibition of the response by activation of protein kinase C.

The functional GABAB receptor was expressed in Xenopus oocytes by injecting mRNA obtained from the cerebellum of the rat. Application of GABA in the presence of bicuculline induced a hyperpolarization under current-clamp conditions and an outward current under voltage-clamp conditions. Baclofen mimicked the effect of GABA in the presence of bicuculline, and the effect of baclofen was antagonized by phaclofen. The GABA-induced outward current was slightly inhibited by treatment with GDP-beta-S and was completely inhibited by treatment with GTP-gamma-S. The activation of protein kinase C by 12-O-tetradecanoylphorbol-13-acetate (TPA), but not 4 alpha-phorbol-12,13-didecanoate, suppressed the GABAB receptor-mediated hyperpolarization, and the effect of TPA was antagonized by sphingosine. Thus, activation of protein kinase C inhibits the expressed GABAB receptor-mediated response.

Animals↗
PubMed1991

Differential distribution of the mRNA encoding two isoforms of the catalytic subunit of calcineurin in the rat brain.

The distribution of mRNAs encoding two distinct isoforms of the catalytic subunit of calmodulin-dependent protein phosphatase (calcineurin A), designated calcineurin A alpha and A beta, in the rat brain was examined by using Northern blots and in situ hybridization histochemistry. The mRNAs for calcineurin A alpha and A beta were both unevenly present in the brain and showed different distribution. The differential distribution between calcineurin A alpha and A beta messages suggests that the individual isoforms are involved in specialized neural functions.

Animals↗
PubMed1991

Calmodulin antagonists differentiate between Ni(2+)- and Mn(2+)-stimulated phosphatase activity of calcineurin.

The interaction of calmodulin antagonists with a phosphoprotein phosphatase, calcineurin, was investigated using para-nitrophenyl phosphate (pNPP) as a substrate. Calmidazolium, a potent calmodulin antagonist, inhibited the Ni(2+)-stimulated calmodulin-independent phosphatase activity to much the same extent as it did the Ca2+/calmodulin-stimulated activity. Other calmodulin antagonists, such as trifluoperazine, thioridazine, and W-7, also inhibited the Ni(2+)-stimulated phosphatase activity. On the other hand, calmidazolium only weakly and partially inhibited the Mn(2+)-stimulated phosphatase activity and the other calmodulin antagonists examined increased the Mn(2+)-stimulated activity, in the absence of calmodulin. With the addition of an equimolar amount, as to the inhibited holoenzyme, of the purified B subunit of calcineurin, the Ni(2+)-stimulated phosphatase activity recovered from 38 to 63% of the control level in the presence of 5 microM calmidazolium. When the amount of additional B subunit was increased, the phosphatase activity recovered to 94% of the control level, thereby implying that calmidazolium inhibits the Ni(2+)-stimulated phosphatase activity by interacting with the B subunit, in the absence of calmodulin. The Mn(2+)-stimulated phosphatase activity also recovered from the inhibition by calmidazolium, but a much larger amount of the B subunit was necessary for the recovery. These results indicate that the Ni(2+)- and Mn(2+)-stimulated activities of calcineurin are differentially affected by calmodulin antagonists and that the B subunit plays a crucial role in the expression of the Ni(2+)-stimulated phosphatase activity.

4-Nitrophenylphosphatase↗
PubMed1991

Setleis bitemporal "forceps marks" syndrome and its pathogenesis: a case report.

Setleis bitemporal "forceps marks" syndrome is characterized by "forceps marks" and a peculiar facies. The syndrome has previously been reported mainly in the Puerto Rican population. We describe here a Japanese boy with the syndrome. In addition, the hypothesis is presented that the Setleis syndrome may result from an insufficient migration of neural crest cells into the frontonasal process and the first branchial arch.

Abnormalities, Multiple↗
PubMed1991

Histamine H1-receptor-mediated keratan sulfate production in rabbit chondrocytes: involvement of protein kinase C.

We investigated the characteristics of the histamine H1-receptor in cultured rabbit chondrocytes. Scatchard analysis of [3H]pyrilamine, an H1-antagonist, binding to the chondrocytes revealed a single class of binding sites with KD and Bmax values of 90 +/- 12 nM and 56 +/- 11 fmol/10(4) cells, respectively. H1-agonists stimulated the production of keratan sulfate in a dose-dependent manner. Stimulation of keratan sulfate production was inhibited by pyrilamine. Protein kinase C inhibitors (sphingosine and H-7) also had inhibitory effects. Phorbol 12,13-dibutyrate, a direct activator of protein kinase C, activated the production. When protein kinase C in the chondrocytes was down-regulated by preincubation with phorbol ester, the effect of the H1-agonist on keratan sulfate production was abolished. These results indicate that the histamine H1-receptor on chondrocytes mediates the accumulation of keratan sulfate production and that protein kinase C is involved in these events.

Animals↗
PubMed1991

Two cases of skeletal open bite treated by sagittal splitting osteotomy of the mandibular ramus--a comparison between successful treatment and subsequent relapse.

Sagittal split-ramus osteotomy was performed on two patients with severe open bite due to Class I malocclusion. The original open bite was -9 mm in case 1 and -6 mm in case 2. After presurgical orthodontic treatment, these values were changed to -7 mm and -8 mm, respectively. The surgical procedure for treating these patients required mobilization of the mandible to close the open bite. The operation was successful in one case, but partial relapse occurred in the other during retention. The factors leading to the relapse were considered by comparison between the two cases.

Adolescent↗
PubMed1991

Clebopride enhances contractility of the guinea pig stomach by blocking peripheral D2 dopamine receptor and alpha-2 adrenoceptor.

The mechanism of action of clebopride on the motility of guinea pig stomach was examined by the receptor binding assay for bovine brain membrane and by measuring gastric contractility and the release of acetylcholine from the stomach. The receptor binding assay revealed that clebopride bound to the D2 dopamine receptor with a high affinity and to the alpha-2 adrenoceptor and 5-HT2 serotonin receptor with relatively lower affinity, and not to D1 dopamine, alpha-1 adrenergic, muscarinic acetylcholine, H1 histamine, or opioid receptor. In strips of the stomach, clebopride at 10(-8) M to 10(-5) M enhanced the electrical transmural stimulation-evoked contraction and the release of acetylcholine. This enhancement was attributed to the blockade of the D2 dopamine receptor and alpha-2 adrenoceptor because: 1) Maximum responses obtained with specific D2 dopamine receptor antagonist, domperidone, and with specific alpha-2 adrenoceptor antagonist, yohimbine, were smaller than that with clebopride, and the sum of the effects of these two specific receptor antagonists is approximately equal to the effect of clebopride. 2) The facilitatory effect of clebopride was partially eliminated by pretreatment of the sample with domperidone or yohimbine, and the facilitatory effect of clebopride was not observed in preparations treated with the combination of domperidone and yohimbine. Clebopride also antagonized the inhibitory effects of dopamine and clonidine on the electrical transmural stimulation-evoked responses. These results indicate that clebopride acts on post ganglionic cholinergic neurons at D2 and alpha-2 receptors in this preparation to enhance enteric nervous system stimulated motility.

Acetylcholine↗
PubMed1991

Pharmacokinetics and optimum dose of disopyramide in patients with chronic renal failure.

The pharmacokinetics and optimum dose for maintenance of disopyramide (DP) which is effective against arrhythmia were studied in patients with chronic renal failure (CRF, n = 10), who had a creatinine clearance (Ccr) less than 30 ml/min. The plasma concentrations (PC) of DP and mono-isopropyl-disopyramide (MDP) an active metabolite of DP, were measured by high performance liquid chromatography. Samples from patients and controls were obtained at 0, 1, 2, 3, 4, 6, 8, 12, 24, 33, and 48 hr after oral administration (OA) of 100 mg DP. The pharmacokinetic parameters were calculated using a two-compartment model. In CRF, the plasma half life (T 1/2) of DP was 5.25 to 22.42 hr (average is 12.45 hr) and that of MDP was 5.09 to 131.66 hr (average is 16.9 hr). In normal controls, the T 1/2 of DP was 6.05 hr, but that of MDP could not be determined the available sensitivity of measurement. T max was 3.11 hr at the total PC of DP and MDP, and C max was 2.48 g/ml on average. In conclusion, the present study revealed that: (1) the PC of a mixture of DP and MDP should rise following OA of DP every 8 or 12 hr in CRF; (2) it is necessary therefore to monitor the accumulation of MDP after rolling OA of DP; and (3) OA of DP every 24 hr can maintain an effective PC.

Administration, Oral↗
PubMed1991

Phosphate kinetics in acetate-free biofiltration.

The phosphate kinetics during bicarbonate dialysis (BCD) and Acetate-free Biofiltration (AFB) were determined in 3 stable regular dialysis patients. These patients were switched to a 6-month period of AFB after a 12-month period of BCD. The plasma levels of phosphate, urea, and bicarbonate, and mass removal of phosphate and urea were measured every hour, during 3 consecutive dialysis sessions on BCD and AFB. The plasma phosphate behavior revealed a peculiar form with two main components, which differed from that of urea. The plasma phosphate level fell sharply during the first 2 hours of treatment, and then remained at a plateau towards to the end of the session. The plasma bicarbonate levels during the treatment sessions in the case of AFB were significantly higher than that in BCD. The actual mass removal in AFB was similar to that BCD, despite a significantly lower value of pre-plasma phosphate. A high ultrafiltration rate and better control of acidosis might be the reason for the better performance of phosphate mass removal in AFB. Better control of phosphatemia due to AFB can lead to a reduction in the amount of phosphate binders which have several untoward side effects.

Acidosis↗
PubMed1991

Effect of intraperitoneal administration of heparin to patients on continuous ambulatory peritoneal dialysis (CAPD).

The effect of intraperitoneal administration of heparin to patients on continuous ambulatory peritoneal dialysis (CAPD) remains obscure. We examined 8 patients on CAPD to investigate its effect. When 2.5 U/ml or 5 U/ml of heparin was given intraperitoneally, t1/2 of heparin activity in the dialysate was 0.5 to 2 hrs, and 6 hrs after administration its activity was 0.5 U/ml and 1.4 U/ml respectively. Whole blood clotting time was hardly affected because the transfer of heparin to the plasma was minimal. The plasma antithrombin III (AT-III) levels were comparable to patients on hemodialysis, but the AT-III level in the dialysate was only 1.5% of those in the plasma. We conclude that the intraperitoneal administration of heparin at these doses is effective in preventing fibrin precipitation when intraperitoneal AT-III levels are expected to be relatively increased such as at the start of CAPD or in the presence of peritonitis.

Adult↗
PubMed1990

Molecular cloning and expression of cDNAs coding for soluble guanylate cyclase from rat lung.

Complementary DNA clones corresponding to the 70- and 82-kDa subunits of soluble guanylate cyclase of rat lung have been isolated. Blot hybridization of total poly(A)+ RNA from rat tissues detected mRNA of about 3.4 kilobases for the 70-kDa subunit and about 5.5 kilobases for the 82-kDa subunit. Messenger RNA levels of both subunits were abundant in lung and cerebrum, moderate in cerebellum, heart, and kidney, and low in liver and muscle, consistent with previously described enzyme activities in these tissues. Southern blot analysis of high molecular weight genomic DNA from rat liver indicated that the genes for the 70- and 82-kDa subunits are different. The carboxyl-terminal region of the 70- and 82-kDa subunits showed a high degree of homology and also had a partial homology with the putative catalytic domain of particulate guanylate cyclase and adenylate cyclase, indicating that both the 70- and 82-kDa subunits have catalytic domains. The cDNAs were subcloned to an expression vector and transfected to L cells. The cells transfected with cDNA of the 70-kDa subunit or the 82-kDa subunit showed no guanylate cyclase activity, whereas the cells transfected with both the 70- and 82-kDa subunit cDNAs showed significant guanylate cyclase activity that was activated markedly by sodium nitroprusside. These data suggest that both subunits are required for both the basal catalytic and regulatory activity of soluble guanylate cyclase. Presumably both catalytic subunits must be present and interactive to permit synthesis of cyclic GMP and nitrovasodilator activation.

Amino Acid Sequence↗
PubMed1990

Radiation inactivation target-size analysis of soluble guanylate cyclase.

The soluble form of guanylate cyclase, which is a heterodimer of two subunits with molecular weights of 82,000 and 70,000, was analyzed by radiation inactivation experiments to determine its functional size. Lyophilized crude extract from rat lung or the purified enzyme were irradiated with different doses from 60Co gamma-rays, and the residual activities were measured in the presence or absence of a potent activator, sodium nitroprusside. The target sizes for the basal activity and for the activity in the presence of sodium nitroprusside were calculated from the decay curve was 77 and 192 kDa, respectively, on the crude enzyme, or as 71 and 163 kDa, respectively, on the purified enzyme. The size for the activatable form of the enzyme was more than twice that of the basal activity and close to the size of the holoenzyme, implying that the enzyme activity must reside on one of the subunits and the activation by sodium nitroprusside requires interaction of both subunits.

Animals↗
PubMed1990

Hyperammonemia caused by impaired mitochondrial ornithine transport in a patient with partial quantitative deficiency of ornithine carbamoyltransferase.

Late-onset hyperammonemia was observed in a male patient with partial quantitative deficiency of ornithine carbamoyltransferase (OCT). His liver contained 10% of the normal level of OCT, but with normal kinetics. This reduced enzyme activity alone, however, could not explain the hyperammonemia. Therefore, the effects of impaired ornithine transport into mitochondria, which seemed to be a possible precipitating factor, were examined by numerical simulation of the urea cycle. The results were as follows: (a) On the assumption that the ornithine concentrations in the cytosol and mitochondrial matrix were always equal, the ammonia handling efficiency would be unchanged by decrease in the OCT concentration to 10% of normal; (b) Under conditions of impaired mitochondrial ornithine transport that had no effects on ureagenesis with a normal amount of enzyme, 10% of the normal concentration of enzyme would impair ammonia handling efficiency. Thus, impaired mitochondrial ornithine transport seemed to cause hyperammonemia in the state of partial quantitative deficiency of OCT in this case.

Adolescent↗
PubMed1990

[Second messengers and protein phosphorylation in cellular signal transduction].

Protein phosphorylation has been recognized as a major mechanism by which cellular functions are controlled by neurotransmitters and hormones. In this review, applications of molecular biological techniques to the analyses of regulatory mechanisms of protein phosphorylation by four major second messengers, cAMP, cGMP, diacylglycerol, and Ca2+, are described. 1) Complementary DNA of the regulatory subunit of the cAMP-dependent protein kinase was cloned and expressed in E. coli. Point mutations were introduced in order to analyze functional domains of the subunit. 2) The soluble isoform of guanylate cyclase was purified, and a cDNA of its 70-KD subunit was cloned. Cyclic GMP binding to purified cGMP-dependent protein kinase was characterized using a rapid filtration assay. 3) Primary structure of the catalytic subunit of calmodulin-dependent protein phosphatase (calcineurin A) was determined and the presence of the second isoform of the enzyme was shown by the cDNA cloning technique. 4) The regulatory domain of the protein kinase C was expressed in E. coli. Analysis using site-directed mutagenesis revealed that a "zinc finger"-like structure is responsible for the binding of phorbol esters. In these studies, the molecular biological approach has proven to be useful for clarifying the molecular mechanisms of cellular signal transduction related to second messengers and protein phosphorylation.

Animals↗
PubMed1990

[The clinical value of correction of acidosis by acetate-free biofiltration in patients on regular dialysis treatment].

Effects of metabolic acidosis were compared between bicarbonate dialysis (BCD) and acetate-free biofiltration (AFB). Three stable dialysis patients (1M, 2F, mean age 30 yrs) were selected for the study because their bicarbonate (BC) pre-dialysis plasma concentration were always under 16 mmol/l while they were on 33 mmol/l-BCD thrice weekly for 12 months. They were switched to a 6 months period of AFB. Pre- and post-dialysis BC plasma concentration, other blood chemical parameters and mass removal (total collection of used dialysate) of urea (U), creatinine (Cr), uric acid (UA), and phosphate (P) were measured during the last week of each period, including 3 dialysis sessions. Mean calorie and protein intake were 29.4 KCal/kg.d and 1.5 g/Kg.d (BCD period) and 38.2 Kcal/Kg.d and 1.5 g/Kg.d (AFB period) respectively. BC plasma concentration (Mean +/- SE, mmol/l) at the pre and post-dialysis in AFB were significantly higher than those in BCD (16.6 +/- 0.7 vs 20.8 +/- 0.6; p less than 0.001, 22.7 +/- 0.8 vs 25.8 +/- 0.8; P less than 0.02). Pre- and post-dialysis U plasma concentration (Mean +/- SE, mmol/l) in AFB were significantly lower than those in BCD (34.3 +/- 2.51 vs 20.8 +/- 0.59, 10.5 +/- 1.32 vs 7.5 +/- 0.92; P less than 0.001). Pre-dialysis P plasma concentration (Mean +/- SE, mmol/l) in AFB was significantly lower than that in BCD (1.85 +/- 0.09 vs 1.50 +/- 0.15; P less than 0.01). Cr, UA and P mass removal in BCD and AFB were not significantly different. However, U mass removal in AFB was significantly lower than that in BCD.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetates↗
PubMed1989

Evidence for a second isoform of the catalytic subunit of calmodulin-dependent protein phosphatase (calcineurin A).

We have used a previously characterized rat cDNA clone for the catalytic (A) subunit of calmodulin-dependent protein phosphatase (calcineurin), which we designated A alpha, to isolate cDNA clones coding for a second isoform of the A subunit, A beta. The A beta cDNA encodes a protein of 525 amino acids that is 81% identical with A alpha. The N-terminal region is dissimilar and contains a characteristic proline-rich sequence. The region homologous to protein phosphatases 1 and 2A (region between residues 87 and 338, 91% identical) and the calmodulin binding domain (region between residues 401 and 424, 96% identical) are highly conserved. The presence of two genes coding for calcineurin A suggests the possibility of important functional differences in the two enzymes.

Amino Acid Sequence↗