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S Nishimura

Publications and source records attributed to S Nishimura.

At least 469 records · Page 26Linked to original sources
PubMed1992

A glutamic acid residue at position 31 of Ras protein is essential to the signal transduction for neurite outgrowth of PC12 cells and the stimulation of GTPase activity by GAPRas.

The roles of residues at positions 23-31 adjacent to the 'effector region' and residues at positions 61-65 in a phosphoryl binding loop of the human c-Ha-ras protein were studied by changing each residue of the normal (Gly-12 type) and oncogenic (Val-12 type) Ras proteins to the corresponding residue of the K-rev-1 protein. Firstly, the signal-transducing activities of the mutant Ras proteins of Val-12 type were examined by analysis of their ability to induce neurite outgrowth of phaeochromocytoma (PC12) cells upon expression of the mutant ras gene. Thus, replacement of Glu-31 by Lys was found to impair the signal-transducing activity of the oncogenic Ras protein. Furthermore, it was shown that expression of the Gly-12----Val/Glu-31----Lys mutant Ras protein in PC12 cells suppresses neurite outgrowth induced either by microinjection of the oncogenic Ras protein or by addition of nerve growth factor to the medium. As for the Glu-31----Lys mutant Ras protein (Gly-12 type), the GTPase activity in the presence of GTPase-activating protein for Ras (GAPRas) is much lower than that of the normal Ras protein, whereas the intrinsic GTPase activity is nearly the same as that of the normal Ras protein. Therefore, Gly-31 is one of the determinants for the signal transduction and the correct interaction with GAPRas. On the other hand, the GTPase activity of the Gln-61----Thr mutant Ras protein (Gly-12 type) is negligibly low both in the absence and in the presence of GAPRas.

Amino Acid Sequence↗
PubMed1992

[A retrospective comparison study of patients old and young with non-Hodgkin's lymphoma].

One hundred patients with diffuse non-Hodgkin's lymphoma were treated with combination chemotherapy including adriamycin. Seventy-one patients were under age 70 and 29 were 70 years or older. The clinical characteristics of the two groups were similar, except that the patients showed elevated serum BUN were in the elderly group. The complete remission rate in the elderly patients (66%) was slightly lower than that in the younger patients (75%) (p = NS). The average length of survival in the elderly patients was significantly shorter than in the younger patients (p less than 0.05) (projected 5-year survival: 28 +/- 11% vs 52 +/- 7%). The duration of remission for all patients in the elderly patients did not differ from that in the younger patients (projected 2-year survival: 40 +/- 10% vs 45 +/- 6%). Death during the induction chemotherapy from causes other than lymphoma occurred in 14% of patients over 70-year-old and in one percent of younger patients. At relapse, the response rate was significantly lower in the elderly patients than in the younger patients (CR+PR: 28% vs 78%, p = 0.03). To prevent toxic death in remission induction therapy, drug dose elderly patients should be attenuated according to their general conditions and performance status.

Age Factors↗
PubMed1992

cdc2-like kinase is associated with the retinoblastoma protein.

The growth-suppressive activity of the retinoblastoma (RB) protein is suggested to be regulated by phosphorylation. In studies on the kinase that phosphorylates the RB proteins, we have previously found that RB proteins can be phosphorylated by purified cdc2 kinase. In this study, we noted that RB proteins immunoprecipitated from human cell lysates are weakly phosphorylated in the absence of purified cdc2 kinase. Immunoblot analysis showed the presence of p34cdc2 in the immunoprecipitates with anti-RB monoclonal antibody. In addition, the coprecipitated kinase was found to have the same substrate specificity as cdc2 kinase. The associated kinase activity was particularly high in cells arrested in G1/S and S phase by aphidicolin. Furthermore, RB proteins were shown to be phosphorylated in nuclear extracts by some endogenous cdc2-like kinase(s). These results suggest that cdc2-like kinase is the main kinase for phosphorylation of RB proteins in vivo.

Amino Acid Sequence↗
PubMed1992

[Münchhausen syndrome with severe iron deficiency anemia].

A patient with Münchhausen syndrome who had severe iron deficiency anemia (IDA) is reported. A 31 year-old female presented with irregular genital bleeding. However, gynecological examination disclosed no evidence of specific disorders causing bleeding. Tests for bleeding tendency and hemolysis were all negative. Although massive bleeding was absent, she had three episodes of a rapid fall in Hb level associated with marked fatigue and weakness, and subsequently rapidly developed serious IDA afterwards. Factitious bleeding was strongly suspected. Blood transfusion performed when the patient was not being watched failed to increase Hb, while transfusions given while the patient was watched were effective. She was not cooperative throughout the hospital course and was discharged on her own request. In outpatient clinic, the diagnosis was confirmed by the evidence that she diluted her own blood samples.

Adult↗
PubMed1992

[Management of elderly patients with aneurysmal subarachnoid hemorrhage].

Clinical features of 61 elderly patients aged over 70 years with ruptured intracranial aneurysms were compared with those of 328 younger patients aged under 70 years. According to a policy of early operation, elderly patients with Hunt and Kosnik's grade I, II and younger patients with grade I, II, III were operated on in the acute stage. In elderly patients with grade III, IV and younger patients with grade IV, the indication for surgery was determined case by case. Surgery was performed on 29 patients (48%) in the elderly group and 277 patients (86%) in the younger group. Our conclusions are as follows: 1. Regarding cases of grade I, II and III of Hunt and Kosnik's classification, the rate of good outcome in the elderly group was similar to that in the younger group, following early surgery and meticulous post-operative care. 2. In the elderly group, no patient in cases of grade IV obtained good surgical outcome. 3. Symptomatic vasospasm was less frequent in elderly patients (18.8%) than in younger cases (37%). 4. Delayed operation was planned for some patients in the elderly group, but none of them underwent surgery because of rerupture of aneurysms and deterioration of general condition.

Adult↗
PubMed1992

[B-cell chronic lymphocytic leukemia complicated by autoimmune thrombocytopenic purpura].

A 74-year-old Japanese male was admitted because of anemia. Hepatosplenomegaly, lymphoadenopathy, and purpura were not found. The laboratory data on admission revealed that the white-cell count was 9,400/microliters, the hemoglobin 11.1 g/dl, and the platelet count 17,000/microliters. Platelet-associated IgG was 794.2 ng/10(7) cells. The patient was diagnosed as having autoimmune thrombocytopenic purpura (ATP) at this time. He was treated with prednisolone, but his thrombocytopenia not improve. In addition to prednisolone, azathioprine was given to him. During the course of treatment, leukocytosis gradually appeared and the white-cell count reached more than 30,000/microliters with over 70% lymphocytes. A bone marrow aspiration revealed 70% of small lymphocytes, and surface marker analysis showed that CD19 and HLA-DR were positive on these lymphocytes. Southern blotting analysis demonstrated rearrangements of JH and JK. He was finally diagnosed as B-CLL complicated by ATP. One month after the azathioprine administration, the platelet count increased more than 30,000/microliters and the white-cell count decreased less than 10,000/microliters. About 2% of patients with CLL are known to be complicated by ATP. To our knowledge, the present case is the first case of B-CLL complicated by ATP in Japan.

Aged↗
PubMed1991

A peptide from the GAP-binding domain of the ras-p21 protein as well as azatyrosine block ras-induced maturation of Xenopus oocytes.

The ras-oncogene-encoded p21 protein is known to produce malignant transformation of NIH 3T3 cells as well as maturation of Xenopus oocytes when microinjected into these cells. p21 protein is known to bind a GTPase activating protein (GAP) intracellularly; residues 32-45 have been implicated in interacting with GAP. We demonstrate here that a peptide corresponding to residues 35-47 of p21 as well as the antibiotic azatyrosine inhibit the ras-induced maturation of Xenopus oocytes in a dose-related manner upon microinjection. We have previously shown that this p21 peptide and azatyrosine could inhibit the effects of p21 protein on cell transformation and pinocytosis in NIH 3T3 cells. In the present study, in which we have extended these results to the oocyte system, we also demonstrate that both partially inhibit insulin-induced oocyte maturation, a process which is thought to involve activation of endogenous p21 protein; on the other hand, both agents fail to inhibit oocyte maturation induced by progesterone, which is known not to act through p21 protein activation. Control studies with other peptides and tyrosine analogues support the selective nature of these events. These results suggest that both the p21-related peptide and azatyrosine have potent anti-ras effects intracellularly.

Alanine↗
PubMed1991

Identification of amino acid residues of Ras protein that are essential for signal-transducing activity but not for enhancement of GTPase activity by GAP.

To determine the amino acid residues required for the signal-transducing activity of the human c-Ha-Ras protein, we introduced point mutations at residues 45-54 near the 'effector region' (residues 32-40). We transfected PC12 cells with these mutant genes and also micro-injected the mutant proteins, bound with an unhydrolyzable GTP analog, into PC12 cells. Both procedures showed that Val45----Glu and Gly48----Cys mutations impaired the ability of the Ras protein to induce morphological change of PC12 cells. These mutations did not affect the guanine nucleotide-binding activity or GTPase activity in the absence or presence of bovine GTPase-activating protein (GAP). Therefore, the Val45 and Gly48 residues should be included by definition in the effector region responsible for the signal transduction, while only a subset of the effector-region residues is required for enhancement of the GTPase activity by GAP.

Adrenal Gland Neoplasms↗
PubMed1991

N-methyl-D-aspartate and aspartate raise the cytosolic free calcium concentration by acting upon receptors transiently expressed on immature cerebellar Purkinje cells.

N-Methyl-D-aspartate (NMDA) or aspartate (Asp) increased the cytosolic free calcium concentration ([Ca]in) in some populations of Purkinje cells dissociated from immature rat cerebellum. The NMDA- and Asp-induced rise in [Ca]in was affected only a little by adding glycine or NMDA antagonists, but was reduced either by adding Mg2+, Gallopamil hydrochloride (D-600) and gamma-amino-butyric acid, or by removing external Na+. The results suggest that stimulation of the NMDA-sensitive receptors transiently expressed on immature Purkinje cell soma results in a rise in [Ca]in through the activation of voltage-dependent Ca2+ channels.

2-Amino-5-phosphonovalerate↗
PubMed1991

Production of hepatitis B virion-like particles in yeast.

We constructed a yeast strain that simultaneously expresses four genes encoding the major S, middle S, large S hepatitis B viral envelope proteins and the core protein under the control of the yeast glyceraldehyde-3-phosphate dehydrogenase promoter and terminator. The lysate from this cell line, examined by immunological, physicochemical methods and electron microscopy, was found to contain spherical particles with a diameter of about 40 nm and a density of 1.25 g/ml. These particles reacted with anti-envelope antibodies, but not with anti-core antibodies. However, core antigenicity appeared upon treatment with 3% Nonidet P-40 that eliminates an outer envelope. These observations suggest production of a virion-like complex structure, or at least its DNA-less analog, consisting of core particle enveloped by antibody-reactive envelope. Such a structure was made only when all the four gene products were synthesized in a yeast cell. This system may be useful for the study of virus structure and assembly, and for improved vaccine development.

Blotting, Western↗
PubMed1991

Two cases of steroid sulfatase deficiency with complex phenotype due to contiguous gene deletions.

We report contiguous gene deletions in the distal short arm of the X chromosome in two patients with ichthyosis, due to steroid sulfatase deficiency, and other complex phenotypes. One patient had chondrodysplasia punctata (CDP) and ichthyosis with a normal chromosome constitution. Another patient had a CDP-like phenotype, ichthyosis, and hypogonadism. His karyotype was 46, -X,Y, +der(X)t(X;Y)(p22;q11). DNA from the two patients was analyzed by Southern blotting using cloned fragments mapped in the Xp21-Xpter region to investigate gene deletions. DNA from the patient with CDP showed a gene deletion of the STS, DXS31, and DXS89 loci, and DNA from the patient with X-Y translocation lacked fragments of the STS, DXS31, DXS89, and DXS143 loci. These findings suggest that the common deleted region involving the STS locus might have caused the similar phenotypes in both patients.

Abnormalities, Multiple↗
PubMed1991

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↗
PubMed1991

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↗
PubMed1991

NMR studies of a DNA containing 8-hydroxydeoxyguanosine.

The effects of hydroxylation at the C8 of a deoxyguanosine residue in DNA were studied by NMR analysis of a self-complementary dodecanucleotide, d(C1-G2-C3-oh8G4-A5-A6-T7-T8-C9-G10-C11-G12), which has an 8-hydroxy-2'-deoxyguanosine (oh8dG) residue at the 4th position. NMR data indicate that the 8-hydroxyguanine (oh8G) base takes a 6,8-diketo tautomeric form and is base-paired to C with Watson-Crick type hydrogen bonds in a B-form structure. The thermal stability of the duplex is reduced, but the overall structure is much the same as that of the unmodified d(CGCGAATTCGCG) duplex. The structural changes caused by 8-hydroxylation of the deoxyguanosine, if any, are localized near the modification site.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1991

Receptor types mediating the rise in the cytosolic free calcium concentration by L-aspartate and L-glutamate in immature cerebellar neurons with N-methyl-D-aspartate receptors.

L-Aspartate (Asp) and L-glutamate (Glu) increased the cytosolic free calcium concentration ([Ca]in) in medium-sized cerebellar neurons having N-methyl-D-aspartate (NMDA) receptors. The sustained rise in [Ca]in induced by Asp, but not by Glu, was reduced by the addition of NMDA antagonists, which consistently suppressed the rise in [Ca]in induced by a low concentration of Asp or Glu in combination with glycine. The results suggest that Asp is a more preferential agonist of NMDA receptors than Glu, although Glu can also be an agonist in the presence of glycine.

2-Amino-5-phosphonovalerate↗
PubMed1991

Plasma islet amyloid polypeptide (Amylin) levels and their responses to oral glucose in type 2 (non-insulin-dependent) diabetic patients.

Fasting plasma islet amyloid polypeptide concentrations and their responses to an oral glucose load were determined in non-diabetic control subjects and patients with abnormal glucose tolerance in relation to the responses of insulin or C-peptide. Plasma islet amyloid polypeptide was measured by radioimmunoassay. In the non-diabetic control subjects, fasting plasma islet amyloid polypeptide was 6.4 +/- 0.5 fmol/ml (mean +/- SEM) and was about 1/7 less in molar basis than in insulin. The fasting islet amyloid polypeptide level rose in obese patients and fell in patients with Type 1 (insulin-dependent) diabetes mellitus. In non-obese patients with impaired glucose tolerance and Type 2 (non-insulin-dependent) diabetic patients without insulin therapy, the level was equal to that of the control subjects, but a low concentration of islet amyloid polypeptide relative to insulin or C-peptide was observed in the non-obese Type 2 diabetic group. The patterns of plasma islet amyloid polypeptide responses after oral glucose were similar to those of insulin or C-peptide. However, compared to non-obese patients, a hyper-response of islet amyloid polypeptide relative to C-peptide was noted in obese patients who had a hyper-response of insulin relative to C-peptide. This study suggests that basal hypo-secretion of islet amyloid polypeptide relative to insulin exists in non-obese Type 2 diabetes and that circulating islet amyloid polypeptide may act physiologically with insulin to modulate the glucose metabolism.

Adult↗