Intraoperative color Doppler ultrasonography for partial-liver transplantation from the living donor in pediatric patients.
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Adult↗
Biomedical subjects
H Kasai
Publications and source records attributed to H Kasai.
Dual modes of transcriptional and translational initiation of SSP1, the gene for a mitochondrial HSP70, responding to heat-shock in Schizosaccharomyces pombe.
The SSP1 gene of Schizosaccharomyces pombe which is homologous to the SSC1 gene of Saccharomyces cerevisiae was cloned and its nucleotide sequence determined. A heat-shock element and three possible TATA boxes were found upstream of the coding region. Dual modes of transcriptional initiation were observed in primer extension analyses using as templates the mRNAs prepared from cells before and after heat-shock. Initiation sites situated 50 to 60 nucleotides downstream of the normal one were found to be additionally used in cells after heat-shock. Thus, the mode of transcription in heat-shocked cells of S. pombe appears to be more similar to the one observed in higher eukaryotes than that in S. cerevisiae. The SSP1 gene contains two methionine codons in the region predicted to encode a mitochondrial targeting signal sequence of its protein (Ssp1) and the stretch between the two methionine codons is capable of forming stem-loop structures. Both of the two methionine codons were confirmed to function as translational initiators in vitro. A possible mechanism is proposed for the response of the SSP1 gene towards heat-shock by the differential initiation of its transcription and translation.
Amino Acid Sequence↗
Tonic inhibition and rebound facilitation of a neuronal calcium channel by a GTP-binding protein.
A significant fraction of differentiated NG108-15 neuroblastoma/glioma cells have Ca2+ channel current different from that of undifferentiated cells. In the former cells, the Ca2+ channel sensitive to omega-conotoxin GVIA had slowed activation kinetics and was facilitated by depolarizing prepulses. These kinetic features are identical to those produced by inhibition of the channel by G proteins. Prolonged treatment with prostaglandin E1 and theophylline, agents that cause cellular differentiation, promoted incidence and extent of the tonic inhibition. Intracellular guanosine 5'-[beta-thio]diphosphate removed the tonic inhibition, suggesting sustained activation of a G protein, but pertussis toxin did not block it. A sulfhydryl alkylating agent, N-ethylmaleimide (0.1 mM), rapidly eliminated agonist-induced inhibition, whereas N-ethylmaleimide spared the tonic inhibition and the one induced by intracellular guanosine 5'-[gamma-thio]triphosphate. An agonist could further inhibit the Ca2+ channel that was already tonically inhibited. After washout of an inhibitory agonist, the tonic inhibition was temporarily removed. This "rebound facilitation" gradually faded within a few minutes. Pertussis toxin or N-ethylmaleimide prevented the rebound facilitation, whereas phorbol ester, forskolin, or arachidonic acid induced neither the rebound facilitation nor the tonic inhibition. Whatever its mechanism, the tonic inhibition of Ca2+ channels may serve as the basis for long-term and bidirectional regulation of activity of neuronal Ca2+ channels.
Animals↗
An endonuclease activity in human polymorphonuclear neutrophils that removes 8-hydroxyguanine residues from DNA+.
An endonuclease that specifically removes 8-hydroxyguanine (oh8Gua) from DNA has been isolated from Escherichia coli. As the amount of oh8Gua produced in DNA of X-ray-irradiated mice is known to decrease with time after irradiation, an attempt was made to find a similar activity in human polymorphonuclear neutrophils (PMNs) using a synthetic dsDNA containing oh8Gua as a substrate. The PMN enzyme was isolated free of other DNases, and found to cleave the substrate DNA simultaneously at 2 sites, the phosphodiester bonds 5' and 3' to oh8Gua, producing free hydroxyl and phosphate groups, respectively. The enzyme showed almost no activity on DNAs containing other kinds of modified base tested or mismatched DNA. Thus human cells also contain an endonuclease that specifically removes oh8Gua residues from DNA.
Base Sequence↗
8-oxoguanine (8-hydroxyguanine) DNA glycosylase and its substrate specificity.
Substrate specificities of FPG protein (also known as formamidopyrimidine DNA glycosylase) and 8-hydroxyguanine endonuclease were compared by using defined duplex oligodeoxynucleotides containing single residues of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), 8-oxo-7,8-dihydro-2'-deoxyadenosine (8-oxodA), and 2,6-diamino-4-hydroxy-5-(N-methyl)formamidopyrimidine (Me-Fapy). Duplexes containing 8-oxodG positioned opposite dC, dG, or dT were cleaved, whereas single-stranded DNA and duplexes containing 8-oxodG.dA or 8-oxodA positioned opposite any of the four DNA bases were relatively resistant. Both enzymes cut duplexes containing 8-oxoG.dC 3' and 5' to the modified base but failed to cleave duplex DNA containing synthetic abasic sites, mismatches containing dG, or unmodified DNA. 8-Oxoguanine, identified by HPLC-electrochemical detection techniques, was released during the enzymatic reaction. Apparent Km values for FPG protein acting on duplex substrates containing a single Me-Fapy or 8-oxodG residue positioned opposite dC were 41 and 8 nM, respectively, and those for 8-hydroxyguanine endonuclease were 30 and 13 nM, respectively. Comparison of the properties of the two enzyme activities suggest that they are identical. In view of the widespread distribution of 8-oxodG in cellular DNA, the demonstrated miscoding and mutagenic properties of this lesion, and the existence of a bacterial gene coding for FPG protein, we propose that 8-oxodG DNA is the primary physiological substrate for a constituent glycosylase found in bacteria and mammalian cells.
Base Sequence↗
An endonuclease activity of Escherichia coli that specifically removes 8-hydroxyguanine residues from DNA.
An enzyme that specifically removes an 8-hydroxyguanine (8-OH-Gua) residue in DNA has been purified from Escherichia coli. To assay the enzymatic activity, a synthetic double-stranded DNA (dsDNA) containing 8-OH-Gua at a defined position was used as a substrate. The substrate DNA was simultaneously cleaved at 2 sites, i.e., the phosphodiester bonds 5' and 3' to 8-OH-Gua, leaving a phosphate at each of the neighboring deoxynucleosides. The cleavage was observed only in dsDNA, but not with single-stranded DNA containing 8-OH-Gua. This enzyme showed almost no activity on DNAs containing other kinds of modified bases such as 8-hydroxyadenine, O6-methylguanine and N7-methylguanine. Also DNAs containing mismatches (A/G or C/T) were not cleaved. Studies on several other properties of this enzyme indicate that it differs from endonucleases previously isolated from E. coli, indicating that it is likely to be an endonuclease which specifically recognizes 8-OH-Gua in dsDNA.
Base Composition↗
Palatal myoclonus in Krabbe disease.
A seven-year-old girl with Krabbe disease presenting palatal myoclonus only when awake is reported. The patient was diagnosed as having Krabbe disease enzymatically at the age of eleven months. She developed rhythmical contractions of the soft palate, pharynx, larynx, lips and tongue at two years. The surface electromyography showed rhythmical 2 Hz electrical activities. The MRI disclosed markedly attenuated intensity in the midbrain, pons and medulla oblongata on T2-weighted images. Palatal myoclonus was not controlled by carbamazepine in therapeutic doses, but disappeared when the patient was asleep. This is the first reported case of Krabbe disease with palatal myoclonus.
Brain↗
Analysis of cytosolic phosphoethanolamine and ethanolamine and their correlation with prognostic factors in breast cancer.
Availability of accurate prognostic factors is vital in making decisions on cancer therapy. We have measured the cytosolic contents of phosphoethanolamine and ethanolamine in tumor tissues of 53 breast cancer patients in an attempt to explore the possibility that these amines could be used as prognostic indicators. The levels of phosphoethanolamine and ethanolamine were determined by high-performance liquid chromatography. The ratios of the molar quantity of these amines or amino acids to that of alanine plus tyrosine, which eluted as a single peak, were used to analyze and compare the results among different tumor samples. The results indicated that the values for phosphoethanolamine or ethanolamine varied significantly more than the values for amino acids, such as glycine plus threonine or glutamine plus serine (these amino acids were eluted as single peaks, respectively). The values for phosphoethanolamine, ethanolamine, and phosphoethanolamine plus ethanolamine were analyzed in relation to several commonly used prognostic factors of breast disease. The results indicated that groups having higher mitotic indices had significantly higher values for phosphoethanolamine or phosphoethanolamine plus ethanolamine than the group having lower mitotic indices. As the stage of the disease increased, the values for phosphoethanolamine plus ethanolamine also seemed to become higher. No correlation, however, was observed between steroid hormone receptor positive and negative groups or between positive and negative groups with regard to involved axillary lymph nodes. The content of phosphoethanolamine or phosphoethanolamine plus ethanolamine in cytosol therefore seems to be correlated with some prognostic indicators.
Amino Acids↗
8-Hydroxyguanine, a DNA adduct formed by oxygen radicals: its implication on oxygen radical-involved mutagenesis/carcinogenesis.
Oxygen radicals have been suggested to be involved in mutation/carcinogenesis. The C-8 position of guanine residues in DNA is hydroxylated to produce 8-hydroxyguanine (8-OH-Gua) in DNA in vitro by various oxygen radical producing agents. The formation of 8-OH-Gua was also observed in cellular DNA in vivo by radiation or oxygen radical forming carcinogens. The 8-OH-Gua residue in DNA is often misread in the position of 8-OH-Gua residue itself but also at neighboring residues next to 8-OH-Gua. When second guanine in codon 12 was specifically replaced with 8-OH-Gua and transferred to NIH3T3, the recipient cells were transformed to malignant cell type. E. coli was found to contain an endonuclease which specifically recognizes 8-OH-Gua residue and cleave DNA strand before and after the modified base. The data obtained imply that 8-OH-Gua formed in DNA in vivo is recognized as an abnormal modified base which, if not repaired, play a role in the mediation of oxygen radical-involved mutation/carcinogenesis.
Animals↗
Direct inhibition of chicken gizzard smooth muscle contractile apparatus by caffeine.
The mechanism of the inhibitory effect of caffeine on smooth muscle contraction was examined using chicken gizzard. Caffeine (0.1-5 mmol/l) inhibited the KCl-induced contraction of the muscle with an IC50 of 1.1 mmol/l. Forskolin (0.01-10 mumol/l) also inhibited KCl-induced contraction. The inhibitory effect of caffeine was potentiated by a low concentration of forskolin (0.3 mumol/l) and the inhibitory effect of forskolin was potentiated by a low concentration of caffeine (0.1 mmol/l). Although caffeine and forskolin increased tissue cyclic AMP levels, caffeine inhibited the KCl-induced contraction more strongly than forskolin at a given cyclic AMP level. Caffeine (1-40 mmol/l) inhibited the contractions induced by 3 mumol/l Ca2+ in Triton X-100-permeabilized muscle. Caffeine (1-40 mmol/l) inhibited the phosphorylation of 20 kDa myosin light chain (MLC) in native actomyosin preparation and the inhibition was enhanced by decreasing the ATP concentration in the reaction medium. Calmodulin (CaM) activity, as monitored by Ca2+/CaM-dependent erythrocyte membrane (Ca2+ + Mg2+)-ATPase, was not affected by 20 mmol/l caffeine. Time-dependent dephosphorylation of MLC upon removal of Ca2+, an indicator of phosphate activity, was not affected by caffeine. Caffeine also inhibited the Ca2(+)-independent contraction in thiophosphorylated permeabilized muscle. These results indicate that caffeine inhibits smooth muscle contraction by a direct inhibition of MLC kinase and actin-myosin interaction. A part of the inhibitory effect may be mediated by cyclic AMP-dependent mechanism(s).
Actomyosin↗
5-Formyldeoxyuridine: a new type of DNA damage induced by ionizing radiation and its mutagenicity to salmonella strain TA102.
An aqueous solution of calf thymus DNA was irradiated by 60Co gamma-rays and modified nucleosides produced in DNA were analyzed by high-pressure liquid chromatography coupled with a photodiode array UV detector. A new product with UV absorption maxima at 230 nm and 280 nm was observed. The structure of this compound was proposed to be 5-formyldeoxyuridine (f5dU) based on the mass spectrum of its trimethylsilyl derivative (M+, m/z472) and the structure was confirmed by chemical synthesis. The yield of f5dU (2.4/10(4) dT/krad) in DNA was of roughly the same order as that of 8-hydroxydeoxyguanosine and 5-hydroxymethyldeoxyuridine. Free f5dU was mutagenic to Salmonella typhimurium strain TA102: therefore f5dU incorporated into DNA may induce mutations.
Animals↗
Japanese encephalitis in a 7-month-old Japanese boy.
A 7-month-old Japanese boy was diagnosed as having meningo-encephalitis with anterior horn cell damage. The complement fixation (CF) and hemagglutination inhibition (HI) tests showed increased antibody titers against Japanese encephalitis (JE) virus, but HI antibody in the mother's serum was not increased. It appears that the lack of JE-antibodies from the mother may have resulted in increased JE viral infectivity in the patient. A decrease in the incidence of antibodies against various viruses in women of childbearing age may lead to increased rates of severe viral infection in infants.
Complement Fixation Tests↗
[Ifosfamide-induced urinary bladder lesion and its inhibition by mesna].
This study examined the characteristics of urinary bladder lesions (cystitis) induced by ifosfamide (IF), an antitumor agent, and their inhibition by mesna in rats. Single i.v. doses of 50 mg/kg or more of IF induced cystitis characterized by increased bladder weight with mucosal hemorrhage and edema within 3 hr, with a plateau being reached 1 to 3 days after the injection. This change occurred earlier than myelotoxicity. Injection of IF to ureter-ligated rats did not induce the cystitis. Also, when IF was infused to one of a pair of rats in which the ureters had been crossed, the cystitis occurred only in the non-injected member of the pair whose bladder received urine flow from the IF-injected rat. Cystitis did not occur with direct injection of 10 mg of IF into the urinary bladder, but did with injection of the metabolite, 14 micrograms of acrolein. These findings show that IF-induced cystitis is not a systemic effect like myelotoxicity or an antitumor effect but a local effect. The cystitis could be completely inhibited by mesna, and this effect, which was dose-dependent, occurred from one-tenth of the IF dose. The effect was strongest when mesna was administrated within 1 hr of the IF injection. There was little difference in the effect between single and divided doses. The combined administration of IF with mesna did not lower the antitumor effect of IF.
Animals↗
Cigarette smoking induces formation of 8-hydroxydeoxyguanosine, one of the oxidative DNA damages in human peripheral leukocytes.
Active oxygen species (AOS) such as O2- and H2O2 have been shown to be generated from both gas and tar phases of cigarette smoke and it has been suggested that they are involved in carcinogenesis due to cigarette smoking. Therefore, we investigated the effect of cigarette smoking on oxidative DNA damages in human peripheral blood cells using 8-hydroxydeoxy-guanosine (8-OH-dG) as a marker. From ten healthy male volunteers aged 20-22 years, 5 ml of blood was taken before and 10 minutes after smoking 2 cigarettes in 10 minutes. After lysis of blood cell membranes leukocyte DNA was isolated using a DNA extractor and 8-OH-dG levels were determined using high performance liquid chromatography (HPLC) with electrochemical detection. The mean levels of 8-OH-dG increased significantly (P less than 0.05) from 3.3 +/- 0.8/10(6) dG (mean +/- SD) to 5.1 +/- 2.5 after smoking. These results indicate that cigarette smoking induces oxidative DNA damage in peripheral blood cells in a relatively short time.
8-Hydroxy-2'-Deoxyguanosine↗
[A case of pineal epidermoid cyst showing an interesting magnetic resonance imaging].
A case of pineal epidermoid cyst with interesting findings of magnetic resonance imaging (MRI) is reported referring to the literature. In our case, homogeneous high density area is seen on CT and high signal intensity is recognized on T1-weighted MRI and low signal intensity on T2-weighted MRI.
Adult↗
Phospholipid molecular species in human umbilical artery and vein endothelial cells.
Molecular species of several phospholipid classes and subclasses were quantitatively determined in human umbilical artery and vein endothelial cells. Both types of endothelial cells were similar in phospholipid class composition, whereas they were markedly different in phospholipid subclass and molecular species composition. The amounts of two ether subclasses in phosphatidylcholine and phosphatidylethanolamine were higher in artery endothelial cells than those in vein endothelial cells. The relative content of alkylacyl subclass in phosphatidylcholine, a precursor of platelet-activating factor, was about three times higher in artery endothelial cells than in vein endothelial cells. In artery endothelial cells, arachidonic acid was in highest amounts in alkenylacyl phosphatidylethanolamine, followed by diacyl phosphatidylcholine, diacyl phosphatidylethanolamine, and phosphatidylinositol. In the vein endothelial cells, arachidonic acid was highest in phosphatidylinositol, followed by diacyl phosphatidylethanolamine, diacyl phosphatidylcholine, and alkenylacyl phosphatidylethanolamine. Artery endothelial cells had higher amounts of molecular species containing arachidonic acid than vein endothelial cells in all phospholipid classes and subclasses. These differences are thought to reflect the functional differences of artery and vein endothelial cells.
Cardiolipins↗
[Anesthetic management of adrenalectomy in a patient with aldosteronism complicated with hypertrophic cardiomyopathy].
We had a rare patient for adrenalectomy who had aldosteronism complicated with hypertrophic cardiomyopathy (HCM). It has been suggested that aldosteronism could be the cause of HCM. The association is not clear in this case, but there is a possibility that myocardial hypertrophy was deteriorated with hypertension caused by aldosteronism. Two important points of the anesthetic management of a patient with HCM are (1) to prevent direct or reflex increases in contractility, and (2) to maintain adequate preload and afterload. In a case complicated with aldosteronism, there is a risk that a significant increase in peripheral vascular resistance following the manipulation of the adrenal gland would aggravate left ventricular pressure load, resulting in a marked decrease in cardiac output. Therefore, in such a case, vasodilators which are said to be poorly tolerated in a patient with HCM might be considered to facilitate the anesthetic management, provided that the vascular system is kept appropriately full. In this case, we employed enflurane-oxygen-nitrous oxide with fentanyl to keep deep levels of general anesthesia. Nitroglycerin (NTG) was used when arterial pressure increased suddenly with the manipulation of the adrenal gland. The effect of NTG is not definitely convincing since blood pressure returned to normal after adrenal excision. But the fact that pulmonary capillary wedge pressure decreased with infusion of NTG suggests improvement of hemodynamic function.
Adrenalectomy↗
Biochemical characterization and comparison of rat thromboxane A2/prostaglandin H2 receptors in platelets and cultured aortic smooth muscle cells.
Comparison of thromboxane A2/prostaglandin H2 (TXA2/PGH2) receptors in rat cultured vascular smooth muscle cells (VSMC) with those in rat gel-filtered platelets (GFP) was carried out using a receptor-ligand binding assay. The binding of each of three radiolabeled TXA2/PGH2 receptor antagonists [( 3H]S-145,[3H]SQ29,548, and [3H]ONO3708) displayed high affinity and specificity as well as saturable and displaceable binding to a single class of recognition sites with the same maximum number in both VSMC and GFP. The Kd values for [3H]S-145 were almost identical for both VSMC and GFP, whereas the values for [3H]SQ29,548 and [3H]ONO3708 for VSMC were approximately two and six times larger than that for GFP. Kinetic analysis of the binding of each receptor antagonist revealed a smaller K1 value (the association rate constant) for [3H]SQ29,548 and a larger K-1 value (the dissociation rate constant) for [3H]ONO3708 for VSMC compared to GFP, in contrast with almost the same kinetic constants for the [3H]S-145 binding for both cells. Comparison of the inhibitory potencies (Ki values) for [3H]S-145 binding for both VSMC and GFP proved that S-145 had the same affinity for both cells; ONO11120 and BM13177, as well as SQ29,548 and ONO3708, possessed lower affinity for VSMC; and U46619 exhibited higher affinity for VSMC. The rank orders of potency were identical in both cells (S-145 greater than SQ29,548 greater than ONO3708 greater than ONO11120 greater than BM13177), which correlated well with their pharmacological activities. These results suggest a similarity in ligand binding specificity with some differences in the accessibility of the antagonists in the TXA2/PGH2 receptors between platelets and vascular smooth muscles.
Animals↗