Biomedical subjects

K Kageyama

Publications and source records attributed to K Kageyama.

At least 19 recordsLinked to original sources

PubMed2006

Gene analysis of the calcium channel 1 subunit and clinical studies for two patients with hypokalemic periodic paralysis.

Hypokalemic periodic paralysis (HypoPP) is a skeletal muscle disorder in which episodic attacks of muscle weakness occur; they are associated with decreased serum potassium (K+) levels. Recent molecular approaches have clarified that the condition is caused by mutations in the skeletal muscle voltage-gated calcium channel 1 subunit (CACNA1S). We describe two unrelated patients with HypoPP, followed by their relevant clinical studies and gene analysis. Clinical studies included an oral glucose tolerance test (OGTT), food-loading and insulin tolerance tests (ITT). For Case 1, serum K+ levels were extremely decreased following insulin tolerance testing compared with levels for controls. These results support the hypothesis that no efflux of K+ ion occurs in patients because of low activity of adenosine triphosphate (ATP)-sensitive K+ channel (KATP) channels. Mutational analysis of the CACNA1S gene showed a duplicate insertion of 14 base pairs (bp) from 52 to 65 in intron 26, present in the heterozygous state in both patients. No other mutations were detected in the CACNA1S gene, the muscle sodium channel gene (SCN4A) or the voltage-gated K+ channel gene (KCN3) of either patient. Further analysis showed that this duplicate insertion of 14 bp in intron 26 of the CACNA1S gene was found in 23.7% of healthy subjects. K+ dynamics studies are useful for confirming this syndrome, while further gene analysis for various ion channels using amplification and direct sequencing are required to evaluate the molecular basis of the disorder in the individual patient.

Adult↗

PubMed2006

A novel mutation of the thiazide-sensitive sodium chloride cotransporter gene in a Japanese family with Gitelman syndrome.

Gitelman syndrome is an inherited renal disorder characterized by impaired NaCl reabsorption in the distal convoluted tubule leading to hypokalemia, hypomagnesemia and normocalcemic hypocalciuria. It has been shown that this syndrome results from mutations in the gene encoding the thiazide-sensitive sodium chloride cotransporter (TSC). We performed the mutational analysis in the TSC gene of a 30-year-old Japanese woman with Gitelman syndrome and found two mutations at adjacent spots in both alleles. One was a frame shift mutation which generated stop codon at position 671, the other was a single nucleotide mutation, which resulted in an aminoacid substitution at position 672, Met to Ile. Her 52-year-old mother and two daughters had neither hypokalemia nor hypomagnesemia. However, her mother and her 8-year-old daughter had the Met672Ile mutation as heterozygotes. Her 4-year-old daughter had the same frame shift mutation as her mother, a heterozygotic mutation. These results suggest that Gitelman syndrome requires 2 compound heterozygotic mutations and the coexistence of the large deletion in the C-terminal domain with Met672Ile substitution of the TSC could impair the transporter activity underling the hypokalemia and hypomagnesemia in this patient.

Adult↗

PubMed2006

Promotive effects of hyperthermia on the inhibition of DNA synthesis in ehrlich ascites tumor cells by eicosapentaenoic and docosahexaenoic acids.

AIM: To evaluate inhibitory effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on DNA synthesis in combination with hyperthermia in vitro. METHODS: A suspension of Ehrlich ascites tumor cells (EAT) was mixed with DHA or EPA in a glass tube, heated at 37 degrees C, 40 degrees C, or 42 degrees C for 1 h in a water bath, and cultured at 37 degrees C for 19 or 96 h. DNA synthesis was assayed by monitoring of the incorporation of [3H]-thymidine into the acid-insoluble fraction. DHA or EPA incorporated into EAT cells was extracted and measured by thin-layer chromatography and gas-liquid chromatography. RESULTS: The inhibition of DNA synthesis by EPA or DHA increased markedly upon the treatment at 42 degrees C and 40 degrees C compared to that at 37 degrees C. At 37 degrees C, inhibitory action of EPA was more potent than that of DHA at low concentrations (at 50 microM -- DNA synthesis level: EPA, 63.1%; DHA, 87.9%), whereas inhibitory action of DHA was higher at 150 muM (16.7%, 4.4%, ibid.). The effect of DHA compared to EPA was more marked at 40 degrees C (29.0%, 19.2% at 100 microM) or 42 degrees C (19.7%, 10.6% at 100 microM). Evaluation of DNA synthesis rate in the cells treated for 1 h by EPA or DHA with the next culturing of EAT cells for 19 h resulted in the enhanced inhibitory activity of EPA even at concentrations as low as 50 microM at either 37 degrees C (0.5%, 11.3%) or 42 degrees C (0.6%, 4.5%), which in these conditions was higher than that of DHA. At the same time the rate of incorporation of EPA in EAT cells at 37 degrees C or 42 degrees C was lower than that of DHA. CONCLUSION: Administration of DHA or EPA in vitro significantly inhibit DNA synthesis, and such effect is enhanced by combination of PUFAs with hyperthermia.

Animals↗

PubMed2005

Diagnosis of a case of Gitelman's syndrome based on renal clearance studies and gene analysis of a novel mutation of the thiazide-sensitive Na-Cl cotransporter.

Gitelman's syndrome is a recessively inherited renal tubular disorder characterized by low plasma potassium and magnesium levels, reduced calcium excretion, metabolic alkalosis, and increased plasma renin activity and plasma aldosterone concentration with normal blood pressure levels. A 23-yr-old man was referred to our department for further evaluation of hypokalemia. The patient also had hypomagnesemia and markedly reduced urinary calcium excretion. Renal clearance studies and gene analysis of the thiazide-sensitive Na-Cl cotransporter (TSC) were performed in the patient. In response to an iv injection of furosemide, chloride clearance (CCl) increased markedly, while distal fractional chloride reabsorption CH2O/(CH2O+CCl) was considerably reduced. In contrast, thiazide ingestion had no significant effects on these parameters. The patient had compound heterozygous mutations in the alleles encoding the TSC gene, one of which has not been formerly reported. Renal clearance studies and TSC gene analysis by amplification and direct sequencing are useful diagnostic tools for confirming a diagnosis of Gitelman's syndrome.

Adult↗

PubMed2003

Anti-thrombotic effect of milrinone is caused by inhibition of calcium release from the dense tubular system in human platelets.

AIM: Milrinone, a phosphodiesterase III inhibitor, exerts positive inotropic effects which induce an increase in the intracellular calcium concentration by raising the cyclic adenosine monophosphate level in cardiac muscle. Milrinone was also reported to inhibit platelet aggregation, however, its mechanism remains unknown. Therefore, we investigated the effects of milrinone on intracellular calcium mobilization when platelets were activated. METHODS: Washed platelets, obtained from six healthy volunteers, were preincubated with milrinone (0.9 micro M) for 1 min and then exposed to 0.015 i micro ml-1 thrombin for 5 min. The effect of milrinone on changes in the intracellular calcium level using a fluorescent dye, fura-2, was also observed. Calcium mobilizations via plasma membrane calcium channels and the dense tubular system were assessed differentially. RESULTS: Milrinone (0.9 micro M) significantly suppressed the aggregation ratios at 5 min compared with those in controls (86+/-5%) to 75+/-8%. The increase in the intracellular calcium concentration was also significantly suppressed (controls, 915+/-293 nM vs. 405+/-240 nM) when stimulated by thrombin. Milrinone also significantly inhibited the release of calcium from the dense tubular system (controls, 284+/-111 nM vs. 158+/-51 nM). Calcium influx through the plasma membrane was suppressed by milrinone 2.4 micro M. CONCLUSION: Milrinone (0.9 micro M) inhibited thrombin-induced platelet aggregation. This inhibitory effect was mainly mediated by suppressing calcium release from the dense tubular system.

Adult↗

PubMed2002

Intention myoclonus in paediatric patients following severe cardiopulmonary failure: a report of three cases.

We describe the development of intention myoclonus following severe cardiopulmonary failure in three paediatric patients. Symptoms occurred during the withdrawal of midazolam and fentanyl, which were used for prolonged sedation, and resolved spontaneously. Because the three patients had concomitant brain injury secondary to cardiopulmonary failure.related hypoxia, we propose that the combination of hypoxic brain injury and sedative withdrawal may predispose to intention myoclonus.

Journal Article↗

PubMed2001

Application of modified sequential organ failure assessment score in children after cardiac surgery.

OBJECTIVE: To evaluate the usefulness of the modified sequential organ failure assessment (m/SOFA) score for assessing morbidity and mortality in pediatric patients after cardiac surgery. DESIGN: Analysis of a prospectively collected database. SETTING: Pediatric intensive care unit of a university-affiliated hospital. PARTICIPANTS: Consecutive pediatric patients (n = 142) undergoing cardiac surgery. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The m/SOFA score, consisting of 5 organ scores (maximum score of 20 points), was calculated on admission (initial) and at 12 and 36 hours postoperatively. An initial score of >5 points with an unchanged or upward postoperative trend predicted a higher postoperative mortality and a greater need for intensive care intervention. In neonates, sustained higher score >10 points predicted an outcome of death with a sensitivity of 100% and a specificity of 87%. Given the higher mortality related to immature organ function and a greater complexity of heart defects, the application of the m/SOFA score, a less invasive and simple way to assess organ damage, is especially suitable in neonates. The m/SOFA score would be more appropriately assessed according to the congenital heart defect or surgical procedure because the types of cardiac defect after the surgical repair affect each organ score measurement. CONCLUSION: Application of the m/SOFA score in the early postoperative period, which reflects cumulative perioperative organ damage, would provide some direction to eventual outcomes of morbidity and mortality in patients with congenital heart defects undergoing surgery.

Adolescent↗

PubMed2001

Arterial ketone body ratio for the assessment of the severity of illness in pediatric patients following cardiac surgery.

PURPOSE: The purpose of this study was to assess whether the arterial ketone body ratio (AKBR) can be effectively used to evaluate the severity of illness in children following cardiac surgery. MATERIALS AND METHODS: AKBR was measured in 157 consecutive pediatric patients following heart surgery on the odd numbers of postoperative days. The relationship between AKBR and patient outcome was analyzed using the data of 141 patients with cardiopulmonary bypass. RESULTS: Initial AKBR was frequently lower than 1.0, and this was associated with the increases in total ketone body counts. Insufficient glucose metabolism appeared to contribute to the low initial AKBR. As a result, the specificity of initial AKBR as a mortality predictor was lower than that of initial blood lactate. In the sequential analysis of AKBR for the 48 patients with PICU stay longer than 5 days, patients showing a sustained lower level <1.0 had significantly higher development of organ dysfunction (liver, heart) and greater mortality (56%). CONCLUSIONS: Sustained postoperative decrease in AKBR <1.0 represents lethal outcome. The analysis of AKBR trend in combination with a measurement of blood lactate level in early postoperative period appears to be useful for the assessment of the severity of illness in pediatric patients following heart surgery.

Adolescent↗

PubMed2001

The Purple leaf (Pl) locus of rice: the Pl(w) allele has a complex organization and includes two genes encoding basic helix-loop-helix proteins involved in anthocyanin biosynthesis.

The Purple leaf (Pl) locus of rice (Oryza sativa L.) affects regulation of anthocyanin biosynthesis in various plant tissues. The tissue-specific patterns of anthocyanin pigmentation, together with the syntenic relationship, indicate that the rice Pl locus may play a role in the anthocyanin pathway similar to the maize R/B loci. We isolated two cDNAs showing significant identity to the basic helix-loop-helix (bHLH) proteins found in the maize R gene family. OSB1 appeared to be allelic to the previously isolated R homologue, Ra1, but showed a striking difference at the C-terminus because of a 2-bp deletion. Characterization of the corresponding genomic region revealed that the sequence identical to a 5'-portion of OSB2 existed approximately 10-kb downstream of the OSB1 coding region. OSB2 lacks a conserved C-terminal domain. Restriction fragment length polymorphism analyses using an F(2) population indicate that both genes co-segregate with the purple leaf phenotype. A transient complementation assay showed that the anthocyanin pathway is inducible by OSB1 or OSB2. These results suggest that the Pl(w) allele may be complex and composed of at least two genes encoding bHLH proteins.

Alleles↗

PubMed2001

Regulation of corticotropin-releasing factor receptor type 2beta messenger ribonucleic acid by interleukin-1beta in rat vascular smooth muscle cells.

OBJECTIVE: Corticotropin-releasing factor receptor type 2 (CRF R2) messenger RNA (mRNA) expression in the rodent heart or vessels is modulated by exposure to urocortin and glucocorticoids. In addition, we previously found that incubation with a variety of cytokines, such as interleukin (IL)-1 and IL-6, and tumor necrosis factor-alpha also reduced CRF R2beta mRNA expression, with IL-1beta being the most effective. In this study, we further explored the regulation of CRF R2beta mRNA levels by IL-1beta in the rat vascular smooth muscle A7r5 cells. METHODS: A7r5 cells were incubated with IL-1beta, urocortin, or both for 6 h, after pre-incubating with or without anti-IL-1beta antibody (Ab) for 30 min, and then CRF R2beta mRNA levels were measured by RNase protection assay. Cells were incubated with lipopolysaccharides, IL-1beta, IL-6, dexamethasone, forskolin, or urocortin for 20 min, and then intracellular cAMP was measured by cAMP RIA. RESULTS: IL-1beta produced a significant time-dependent decrease in CRF R2beta mRNA levels. Combined urocortin and IL-1beta administration did not have synergistic effects on the decrease in CRF R2beta mRNA levels. IL-1beta Ab failed to block the ability of urocortin to regulate CRF R2beta mRNA levels, suggesting that urocortin regulated CRF R2beta mRNA levels via another pathway than IL-1beta production. Urocortin induced the intracellular cAMP production in A7r5 cells, while IL-1beta failed to induce it. CONCLUSION: The multifactorial regulation of CRF R2beta mRNA expression in the A7r5 cells serves to limit the inotropic and chronotropic effects of CRF R2 agonists such as urocortin during prolonged physical or immune challenge.

Animals↗

PubMed2001

[Perioperative assessment of blood lactate levels in pediatric heart surgery].

Measuring arterial lactate concentration is a prompt, easy and relatively non-invasive way to estimate tissue oxygen metabolism. We evaluated whether perioperative levels of the arterial lactate concentrations can reflect the general severity of a pediatric patient's condition. A consecutive series of 112 patients, aged 5 days to 17 years (median age: 12 months), admitted to our pediatric intensive care unit (PICU) following cardiac surgery under cardiopulmonary bypass were studied. Arterial blood lactate concentration was measured preoperatively, immediately upon termination of the cardiopulmonary bypass (postCPB), immediately following the operation, and 16th hours postoperatively (D1). Trends within arterial lactate concentrations were examined in relation to mortality rates, the duration of PICU stays and the patient's ages. The studied population had a mortality rate of 5.7% (6 patients). Lactate levels increased significantly and exceeded 4.0 mmol.l-1 during postCPB measurements in a majority of the patients. The increases in lactate levels are affected by the changes in interorgan blood flow, blood glucose levels and/or blood pH in addition to the effects of the CPB-priming lactated Ringer's solution. Thus, higher cut off values have to be determined, and lower probabilities assigned, when using postCPB lactate levels to predict the severity of an outcome. Significantly and sustained increases in D1 lactate levels were noted in neonates, patients with longer PICU stays (> 15 days) and those died later. Hyperlactemia greater than 2.2 mmol.l-1 at D1 predicted death with a sensitivity of 82% and a specificity of 72%. The measurement of early postoperative lactate levels, reflecting postoperative ability to eliminate intraoperative hyperlactemia, is a better way of assessing the severity of a pediatric patient's condition following cardiac surgery. The ideal time to measure early postoperative lactate levels should be determined by further research.

Adolescent↗

PubMed2001

Changes in plasma antiproteases in paraquat poisoned rats using micro two-dimensional electrophoretic analysis.

Rats were subjected to subacute paraquat (PQ) exposure (7 mg/kg sc daily for 6-9 administrations). They were divided into a group that died from subacute toxicity, a group that recovered from the subacute toxicity and progressed to pulmonary fibrosis, and a group that showed no effects from the PQ. The rats with subacute fatal toxicity had a remarkable increase in a2M-1. Those which progressed to pulmonary fibrosis had remarkable decreases in a2M-2, a2M-3, and a2M-4 and a1AT. The rats that showed no effects from the PQ had relative increases in all molecular species of a2M. Increases in major a2M molecular species, a2M-1 and a2M-4, and a minor molecular species, a2M-3, were characteristically observed.

Animals↗

PubMed2000

Palladium-catalyzed tert-butoxycarbonylation of trifluoroacetimidoyl iodides.

A modification and details of the palladium-catalyzed tert-butoxycarbonylation of 2,2,2-trifluoroacetimidoyl iodides 1, which gave the iminocarboxylates 2, one of the promising precursors to fluorinated alpha-amino acids, are described. The Pd-catalyzed carbonylation reaction was remarkably promoted by the use of DMF or DMI as an additive, enough to achieve the selective formation of tert-butyl iminoesters. Nucleophilic alkylation of the imine moiety of 2 and subsequent removal of N- and O-protecting groups gave a variety of 2-substituted 2-amino-3,3,3-trifluoropropanoic acid derivatives 3 in high yields.

Acetamides↗

PubMed2000

Sevoflurane does not inhibit human platelet aggregation induced by thrombin.

BACKGROUND: Sevoflurane reportedly inhibits adenosine diphosphate-induced platelet aggregation by suppressing thromboxane A2 formation. The increase in intracellular calcium concentration that fosters platelet aggregation, however, is also induced by other cell signaling pathways, such as activation of the production of inositol 1,4,5-triphosphate by thrombin. The current study aimed to clarify the net influence of sevoflurane on thrombin-induced platelet aggregation. METHODS: Washed platelets were stimulated by thrombin after incubation with 0.5, 1.0, or 1.5 mM sevoflurane, halothane, or isoflurane. Aggregation curves were measured by an aggregometer. Intracellular calcium concentration was measured fluorometrically using fura-2. Calcium mobilization via plasma membrane calcium channels and the dense tubular system was assessed differentially. Intracellular inositol 1,4,5-triphosphate was measured by radioimmunoassay. RESULTS: Halothane significantly suppressed aggregation ratios at 5 min compared with those in controls (89 +/- 7%) to 71 +/- 10% (1.0 mM) and 60 +/- 11% (1.5 mM) and the increase in intracellular calcium concentration (controls, 821 +/- 95 nM vs. 440 +/- 124 nM [1.0 mM] or 410 +/- 74 nM [1.5 mM]). Halothane also significantly inhibited release of calcium from the dense tubular system (controls, 220 +/- 48 nM vs. 142 +/- 31 nM [1.0 mM]). Neither sevoflurane nor isoflurane produced a net change in aggregation ratios, intracellular calcium concentration, or calcium mobilization. Halothane (1 mM) significantly suppressed inositol 1,4,5-triphosphate concentrations, whereas neither 1 mM isoflurane nor 1 mM sevoflurane had any effect. CONCLUSIONS: Although sevoflurane has been reported to inhibit human platelet aggregation induced by weak agonists such as adenosine diphosphate, it does not inhibit human platelet aggregation induced by strong agonists such as thrombin.

Anesthetics, Inhalation↗

PubMed2000

Hypoxic gas therapy using nitrogen in the preoperative management of neonates with hypoplastic left heart syndrome.

OBJECTIVE: To evaluate the efficacy of hypoxic gas therapy using nitrogen, where the fraction of inspired oxygen (Fio2) was reduced to <0.21 in patients with univentricular parallel circulation. DESIGN: Case report. SETTING: A pediatric intensive care unit at a university hospital. PATIENTS: Two neonatal patients with hypoplastic left heart syndrome admitted to the pediatric intensive care unit preoperatively. INTERVENTIONS: Nitrogen insufflation by using continuous-flow respiratory support. MEASUREMENTS AND MAIN RESULTS: We reduced the Fio2 in these patients by giving additional nitrogen to relieve pulmonary overcirculation and systemic hypoperfusion suspected by transcutaneous arterial oxygen saturation >90%, systemic arterial hypotension, and low urine output in the preoperative course. The improvement of systemic hemodynamics concomitant with decreases in transcutaneous arterial oxygen saturation <85% was accomplished by controlling Fio2 between 0.14 and 0.18. These infants were able to undergo Norwood's surgery after several days without complications relating to Fio2 reduction. CONCLUSION: Hypoxic gas therapy with nitrogen was effective clinically in preventing pulmonary overcirculation in neonatal patients with univentricular and parallel circulation.

Journal Article↗

PubMed2000

Regulation of corticotropin-releasing factor receptor type 2 beta messenger ribonucleic acid in the rat cardiovascular system by urocortin, glucocorticoids, and cytokines.

CRF receptor type 2 (CRF R2) messenger RNA (mRNA) expression in the rodent heart is modulated by exposure to both the bacterial endotoxin lipopolysaccharide (LPS) and glucocorticoids. In this study we examined the roles of glucocorticoids, cytokines, and CRF R2beta ligands in the regulation of CRF R2beta expression in the cardiovascular system both in vivo and in vitro. Using ribonuclease protection assays, we found that, in addition to the injection of LPS or corticosterone, physical restraint caused a decrease in CRF R2beta mRNA levels in the rat heart and aorta. Adrenalectomy with corticosterone replacement at constant levels partially blocked LPS-induced decreases in CRF R2beta mRNA expression in the heart. Thus, elevations of endogenous circulating corticosterone could contribute to the down-regulation of CRF R2beta mRNA expression in heart. To identify other putative modulating factors, we examined CRF R2beta expression in the aorta-derived A7R5 cell line. Incubation with CRF R2 ligands or dexamethasone reduced CRF R2beta mRNA levels. In addition, incubation with a variety of cytokines, proteins released during immune challenge, also reduced CRF R2beta mRNA expression. The multifactorial regulation of CRF R2beta mRNA expression in the cardiovascular system may serve to limit the inotropic and chronotropic effects of CRF R2 agonists such as urocortin during prolonged physical or immune challenge.

Adrenocorticotropic Hormone↗

PubMed2000

[The influence of the use of mupirocin nasal ointment on the incidence of endogenous MRSA infections in an intensive care unit].

Nasal carriage of MRSA is a significant risk-factor for the endogenous MRSA infection in immunocompromised patients. MRSA infection in ICU patients is thus mostly endogenous infection. To evaluate the impact of mupirocin use on the incidence of endogenous infection caused by MRSA in an intensive care unit, we prospectively treated all patients in the unit with mupirocin, 3 times daily for 3 days. This routine use of mupirocin led to eradication of nasal MRSA carriage in 81.8% of surveillance cultures and to a significant reduction in the total incidence of MRSA infection among MRSA carrier patients (0 episode in 11 patients) when compared to historical controls prior to the use of mupirocin (3 episodes in 7 patients). Mupirocin nasal ointment was significantly effective to prevent endogenous MRSA infection.

Administration, Intranasal↗

PubMed1999

Translocation of G-protein beta3 subunit from the cytosol pool to the membrane pool by beta1-adrenergic receptor stimulation in perfused rat hearts.

To elucidate the intracellular function and localization of the heterotrimeric G-protein beta3 subunit (Gbeta3) in the heart, we studied the effects of subtype-specific beta-adrenergic receptor (beta-AR) stimulation on Gbeta3 localization using isoform-specific antibodies. The amount of Gbeta3 in the cytosol dramatically decreased in hearts perfused with isoproterenol (ISO) alone or ISO with ICI 118551, a beta2-AR antagonist. Propranolol or CGP 20712A, a beta1-AR antagonist, blocked the ISO-induced decrease in the Gbeta3 content of the cytosol. In contrast, Gbeta3 content of the membrane fraction significantly increased in hearts perfused with ISO alone or ISO with ICI 118551. We conclude that stimulation of the beta1-AR induces isoform-specific translocation of Gbeta3 from the cytosol to the membrane fraction in rat hearts.

Animals↗