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Biomedical subjects

N Itoh

Publications and source records attributed to N Itoh.

At least 577 records · Page 32Linked to original sources
PubMed1985

Macrophages in glomerular injury. I. The kinetics of macrophages in accelerated Masugi nephritis in the rat.

To evaluate the role of macrophages in glomerulonephritis, the relationship between the existence of macrophages and proteinuria in the long course of glomerulonephritis was studied in accelerated Masugi nephritis in the rat. Non-specific esterase staining was used as a marker of macrophages and the kinetics of glomerular macrophages was analysed by an image processor. Macrophages became detectable 48 hours after nephrotoxic serum injection and their accumulation reached a maximum level at 5 days. At 1 month, they had clearly decreased. At 3 months, however, many macrophages were found within the capsular drop-like lesions and crescents. Urinary protein excretion took roughly the same time course as the number of macrophages for 2 weeks. However, at 1 month, whereas macrophages had decreased, the proteinuria kept a persistently high level. At 3 months it showed a tendency to decrease. The correlation between the rate of appearance of macrophages and the urinary protein excretion assessed in 20 cases exhibited no significance. In addition, discrepancy in their time course was evident at 1 month. Although macrophages may happen to contribute to the tissue injury resulting in proteinuria in the early phase of nephrotoxic serum nephritis, factors other than macrophages should be considered in the subsequent duration of proteinuria in this model.

Animals↗
PubMed1984

Messenger RNA guanlyltransferase from Saccharomyces cerevisiae. II. Catalytic properties.

Highly purified mRNA-capping enzyme from Saccharomyces cerevisiae catalyzes (a) removal of the gamma-phosphoryl group from the 5'-end of the newly formed mRNA and (b) guanylylation of the resulting diphosphoryl end. Characteristics of the two reactions catalyzed by this enzyme are studied. Guanylyltransferase is most active at pH 7.0 in the presence of 3 mM Mg2+, and utilizes GTP as a guanylyl donor with an apparent Km of 5 microM, and ppGCC (A2, U2, G)n as a guanylyl acceptor with two Km values of 0.5 and 4 microM. It catalyzes GTP-PPi exchange in the absence of the acceptor RNA, and forms a covalent enzyme-GMP intermediate having Mr = 45,000 in sodium dodecyl sulfate gel electrophoresis. RNAs with 5'-diphosphoryl as well as 5'-triphosphoryl ends are capped, while mononucleotides such as GDP and ppGp are inert. Since guanylyltransferase can utilize ppGpC and ppGpCpC as acceptors, the presence of at least one phosphodiester bond seems to be sufficient for the acceptor activity. However, oligonucleotides of longer chain length are preferred. RNA 5'-triphosphatase associated with the purified enzyme requires Mg2+ and exhibits a broad pH optimum from 6.5 to 8.5, and an apparent Km value for pppA-terminated poly(A) is 1.4 microM. The enzyme is specific for the gamma-phosphoryl group at the 5'-terminus of RNA and does not hydrolyze ATP. It can hydrolyze the gamma-phosphoryl group of pppGp, but the RNA substrates with longer chain length are preferred.

Guanosine Monophosphate↗
PubMed1984

Messenger RNA guanylyltransferase from Saccharomyces cerevisiae. I. Purification and subunit structure.

GTP:mRNA guanylyltransferase, an enzyme that catalyzes the transfer of the GMP moiety from GTP to the 5' end of the RNA to form a cap structure (G(5')pppN-), has been purified to an apparent homogeneity from Saccharomyces cerevisiae. The mRNA 5'-triphosphatase activity hydrolyzing the gamma-phosphoryl group from pppN-RNA was co-purified with mRNA guanylyltransferase activity through column chromatographies on CM-Sephadex and poly(U)-Sepharose, and centrifugation through glycerol gradients, suggesting that these two activities are physically associated. An 820,w value of 7.3, and Mr = 140,000 were estimated from the sedimentation behavior in glycerol gradients. Upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis, two major polypeptides, Mr = 45,000 (alpha) and 39,000 (beta), were detected with the purified enzyme preparation. Their molar ratios were close to unity when estimated by the relative density of silver staining. These results suggest that the yeast mRNA-capping enzyme is an oligomeric protein which may consist of two alpha and two beta chains (alpha 2 beta 2).

Chromatography, Affinity↗
PubMed1984

Cyclic AMP regulation of pro-vasoactive intestinal polypeptide/PHM-27 synthesis in human neuroblastoma cells.

The mechanism of N6,O2'-dibutyryl adenosine 3':5'-monophosphate (Bt2cAMP) induction of pro-vasoactive intestinal polypeptide (VIP)/PHM-27 biosynthesis was investigated in human neuroblastoma cells in culture. When neuroblastoma cells were grown for 48 h in the presence of 1 mM Bt2cAMP, the synthesis of pro-VIP/PHM-27 was stimulated 11-fold. The amount of prepro-VIP/PHM-27 mRNA determined both by hybridization with cloned prepro-VIP/PHM-27 cDNA and a reticulocyte cell-free translation assay was also increased 11-fold in the Bt2cAMP-induced cells. Transcription of prepro-VIP/PHM-27 mRNA in isolated nuclei was observed in induced cells, but not in uninduced cells. Blot hybridization with prepro-VIP/PHM-27 cDNA of total nuclear RNA isolated from neuroblastoma cells revealed an RNA species corresponding to mature prepro-VIP/PHM-27 mRNA, and the amount of the RNA was markedly increased in the induced cells. The quantity of VIP/PHM-27 gene in the DNA of neuroblastoma cells was analyzed after hydrolysis with a restriction endonuclease, EcoRI. However, VIP/PHM-27 gene was not amplified in the induced cells. These results indicate that Bt2cAMP-induced pro-VIP/PHM-27 synthesis is achieved by enhancing the transcription rate of prepro-VIP/PHM-27 mRNA.

Animals↗
PubMed1984

Central monoamines and the death process time (antemortem time) during asphyxia. An experimental study in the mouse brain.

The changes of the brain monoamines, norepinephrine (NE), dopamine (DA), and serotonin (5-HT), during acute asphyxia, caused by strangulation, anoxia, and drowning, were studied in the mouse. In several asphyxiated animal groups significant linear correlation was found between the level of monoamines, NE, DA, and 5-HT, and the death process times or antemortem times were r = 0.50, 0.98 (P less than 0.05), and 0.57, respectively. It is concluded that the level of brain NE and DA increased in the mouse that died of asphyxia, and the level of 5-HT showed only an apparent decrease in anoxia groups as compared with the control group and showed a twice as high increase in drowning groups. Especially, there was a tendency that the longer the death process times or antemortem times, the higher was the level of DA.

Animals↗
PubMed1984

Antiepileptic effect and serum levels of clorazepate on children with refractory seizures.

Clorazepate dipotassium is rapidly decarboxylated to yield desmethyl diazepam. The antiepileptic effect of clorazepate was studied in 29 epileptic children with refractory seizures. Their ages were ranged from one year 9 months to 20 years (mean 11 years 6 months). Serum clorazepate levels were also determined in 16 patients. The mean initial dose was 0.91 mg/kg/day, and the dose was increased up to 3 mg/kg/day. Within several days after initiation of clorazepate therapy, a decrease in seizure frequency was seen in patients in whom clorazepate was effective. Excellent results (decrease in seizure frequency by more than 80%) were obtained in 7 patients (24.1%), a moderate improvement with a 50 to 80% decrease was seen in 7 patients (24.1%), and a partial improvement with less than 50% decrease was seen in 7 patients (24.1%). No benefit was seen in 8 patients (27.7%). Serum clorazepate levels in patients with excellent results were 31 to 77 ng/ml (mean 55 ng/ml), those in patients with a moderate improvement were 130 to 225 ng/ml (mean 163 ng/ml), and those in patients with a partial improvement were 142 to 518 ng/ml (mean 273 ng/ml). Serum clorazepate levels in patients with no benefit were 34 to 97 ng/ml (mean 56 ng/ml). There was no direct relationship between serum clorazepate levels and clinical response. The results of this study indicate the efficacy of clorazepate for epileptic children with refractory seizures.

Adolescent↗
PubMed1984

Characterization of Gd3+ and Tb3+ binding sites on Ca2+,Mg2+-adenosine triphosphatase of sarcoplasmic reticulum.

Interaction between Gd3+ and Tb3+ ions and Ca2+,Mg2+-ATPase of sarcoplasmic reticulum was studied. Three classes of lanthanide-ion binding sites with different affinities were distinguished. Binding of Gd3+ to the site with the highest affinity seemed to occur at less than 10(-6)M free Gd3+ and resulted in severe inhibition of ATPase activity. The reaction rates of both E-P formation and decomposition in the forward direction were inhibited in parallel with this binding, whereas ADP-dependent decay of E-P in the backward direction was not. At these Gd3+ concentrations, Ca2+-binding to the transport site was not inhibited. Binding of Gd3+ and Tb3+ to the Ca2+-transport site did occur, but more than 10(-5)M free Gd3+ or Tb3+ was required for effective competition with Ca2+ for that site. Gd3+ bound to the transport site in place of Ca2+ did not activate the E-P intermediate formation. Addition of 10(-1)M Tb3+ to a suspension of sarcoplasmic reticulum membranes resulted in marked enhancement of Tb3+ fluorescence, which is due to an energy transfer from aromatic amino acid residues of ATPase to Tb3+ ions bound to the low affinity site of the enzyme. Gd3+ and Mn2+ competed with Tb3+ for that site, but Ca2+, Zn2+, and Cd2+ did not.

Binding Sites↗