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Biomedical subjects

M Kikuchi

Publications and source records attributed to M Kikuchi.

At least 937 records · Page 52Linked to original sources
PubMed1986

Effects of chaetoglobosin J on the G-F transformation of actin.

It was shown that substoichiometric concentrations of chaetoglobosin J, one of the fungal metabolites belonging to cytochalasins, inhibited the elongation at the barbed end of an actin filament. Stoichiometric concentrations of chaetoglobosin J decreased both the rate and the extent of actin polymerization in the presence of 75 mM KCl, 0.2 mM ATP and 10 mM Tris-HCl buffer at pH 8.0 and 25 degrees C. In contrast, stoichiometric concentrations of cytochalasin D accelerated actin polymerization. Chaetoglobosin J slowly depolymerized F-actin to G-actin until an equilibrium was reached. Analyses by a number of different methods showed the increase of monomer concentration at equilibrium to depend on chaetoglobosin J concentrations. F-actin under the influence of stoichiometric concentrations of chaetoglobosin J only slightly activated the Mg2+-enhanced ATPase activity of myosin at low ionic strength. It is suggested that when the structure of the chaetoglobosin-affected actin filaments is modified, the equilibrium is shifted to the monomer side, and the interaction with myosin is weakened.

Actins↗
PubMed1986

Cloning and sequencing of Serratia protease gene.

The gene encoding an extracellular metalloproteinase from Serratia sp. E-15 has been cloned, and its complete nucleotide sequence determined. The amino acid sequence deduced from the nucleotide sequence reveals that the mature protein of the Serratia protease consists of 470 amino acids with a molecular weight of 50,632. The G+C content of the coding region for the mature protein is 58%; this high G+C content is due to a marked preference for G+C bases at the third position of the codons. The gene codes for a short pro-peptide preceding the mature protein. The Serratia protease gene was expressed in Escherichia coli and Serratia marcescens; the former produced the Serratia protease in the cells and the latter in the culture medium. Three zinc ligands and an active site of the Serratia protease were predicted by comparing the structure of the enzyme with those of thermolysin and Bacillus subtilis neutral protease.

Amino Acid Sequence↗
PubMed1986

Cross-linking study on protein neighborhoods at the subunit interface of rat liver ribosomes with 2-iminothiolane.

Rat liver 80 S ribosomes were cross-linked with 2-iminothiolane. Proteins extracted from the cross-linked 80 S ribosomes were separated into 25 fractions by chromatography on carboxy methylcellulose. Each protein fraction was analyzed by diagonal polyacrylamide-sodium dodecyl sulfate gel electrophoresis. Eight pairs characteristic of 80 S ribosomes were detected which did not appear when isolated 40 S and 60 S subunits were cross-linked, and the cross-linked proteins were analyzed in similar manners. The cross-linked components were radioiodinated and then analyzed by two-dimensional gel electrophoresis, followed by autoradiography. Eight kinds of cross-links between 60 S subunit proteins and 40 S subunit proteins were identified as follows: SA30 (acidic protein with Mr 30,000)-LA33 (acidic protein with Mr 33,000), S2-LA33, S2-L11, S3a-L11, S4-L5, S25-L5, S4-L24 and S6-L24.

Animals↗
PubMed1986

[Basic studies on colony formation of erythroid progenitor cells].

Fundamental studies on CFU-E colony formation were done using bone marrow cells of mice by the methylcellulose culture method. The number of CFU-E colonies reached a peak after 48 hours of incubation. A linear relationship was observed between the number of CFU-E colonies and the number of inoculated bone marrow cells. The number of CFU-E colonies increased dependently on the concentration of erythropoietin (Epo) and reached almost a plateau above 0.25 U/ml. There was little difference in the CFU-E colony forming activity of the two sources of Epo (one partially purified from human urine at our laboratory and the other obtained from Connaught Laboratories Ltd. as Step III derived from plasma of anemic sheep). There was little difference in the number of marrow CFU-E of two strains of mice (ddY and BDF1). The best conditions in the concentration of culture medium were 10-30% in FCS, 0.5-1.0% in BSA, 10(-4) M in 2-mercaptoethanol, respectively. These observations are thought to be useful for the development of studies on CFU-E.

Animals↗
PubMed1986

[Basic studies on granulocyte-macrophage colony formation by mouse bone marrow cells].

In order to study the growth of granulocyte-macrophage colony-forming unit (GM-CFU), fundamental studies on in vitro colony formation were carried out using mouse bone marrow cells by the soft agar culture and the following results were obtained: The number of colonies increased to a maximum level after 4 days of incubation and decreased thereafter. There was a positive correlation between the number of colonies and that of cultured bone marrow cells. There was a linear dose-response relationship between the number of colonies and the concentration of colony stimulating factor (CSF), and the maximum response was obtained at the concentration of 10% CSF. As the fetal calf serum (FCS) dose increased, the number of colonies also multiplied. No significant difference was observed in the colony forming ability between non-separated and separated (non-phagocytic) cells in bone marrow cells. The addition of 2-mercaptoethanol increased doubled the number of colonies at the concentration of 1 X 10(-4) M. The results of these fundamental studies on GM-CFU are thought to be useful for the investigation of granulopoiesis.

Animals↗
PubMed1986

Membrane glycophorins in Sta blood group erythrocytes.

Structural and immunochemical studies of glycophorins isolated from erythrocytes of an individual homozygous for the M Sta blood group phenotype are described. Reactivities with specific monoclonal antibodies indicated that two major M and N glycophorins were present. The M and N Sta glycophorins were resolved by Lens culinaris lectin affinity chromatography. The N species was not held on the lectin but the M species, like control alpha glycophorins, was retained and could be eluted with alpha-methylmannoside. The two proteins were present in almost equimolar amounts. Studies of the CNBr fragments provided evidence that the structure of M Sta glycophorin is the same as that of the usual M alpha glycophorin but that the N Sta glycophorin is a variant. The amino-terminal octapeptides of the M and N species were similar in amino acid and carbohydrate composition to those isolated, respectively, from M and N alpha glycophorins. The studies focused on CNBr glycopeptide B that, in control alpha glycophorins, extends from amino acid residues 9 to 81. The fragment from the M species exhibited properties identical to those of the corresponding fragment of control alpha glycophorins in terms of size, chromatographic behavior, amino acid and carbohydrate contents and compositions, the presence of O-glycosidically linked saccharides and a single Asn-linked carbohydrate unit. The structures of the O-linked units were inferred experimentally to be NeuAc(alpha 2,3)Gal-(beta 1,3)GalNAc and NeuAc(alpha 2,3)Gal(beta 1,3) [NeuAc(alpha 2,6)]GalNAc, present in a ratio similar to that found in controls; and the Asn-linked unit also appeared to be as in the control. The tryptic glycopeptide pattern of the M Sta glycophorin CNBr fragment B was identical to the pattern of the corresponding control fragment, and the composition of the tryptic peptides suggested sequence identity with the control fragment. In contrast, the N Sta glycophorin yielded two CNBr glycopeptides B; both contained fewer amino acid residues and virtually lacked Man and GlcNAc, indicating the absence of the Asn-linked carbohydrate. The much decreased levels of these carbohydrates in the intact N protein, corroborated the latter finding. The O-glycosidic saccharides appeared similar to those found in control alpha glycophorins. However, the tryptic glycopeptide pattern of the variant differed from control M or N alpha glycophorins, suggesting a deletion of a large segment of the molecule near residues 40-61 and/or a substitution of methionine for a residue upstream from residue 40.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acids↗
PubMed1986

Cross-linking of elongation factor 2 to rat-liver ribosomal proteins by 2-iminothiolane.

Complexes containing rat liver 80S ribosomes treated with puromycin and high concentrations of KCl, elongation factor 2 (EF-2) from pig liver, and guanosine 5'-[beta, gamma-methylene]triphosphate were prepared. Neighboring proteins in the complexes were cross-linked with the bifunctional reagent 2-iminothiolane. Proteins were extracted and then separated into 22 fractions by chromatography on carboxymethylcellulose of which seven fractions were used for further analyses. Each protein fraction was subjected to diagonal polyacrylamide/sodium dodecyl sulfate gel electrophoresis. Nine cross-linked protein pairs between EF-2 and ribosomal proteins were shifted from the line formed with monomeric proteins. The spots of ribosomal proteins cross-linked to EF-2 were cut out from the gel plate and labelled with 125I. The labelled protein was extracted from the gel and identified by three kinds of two-dimensional gel electrophoresis, followed by autoradiography. The following proteins of both large and small subunits were identified: L9, L12, L23, LA33 (acidic protein of Mr 33000), P2, S6 and S23/S24, and L3 and L4 in lower yields. The results are discussed in relation to the topographies of ribosomal proteins in large and small subunits. Furthermore we found new neighboring protein pairs in large subunits, LA33-L11 and LA33-L12.

Animals↗
PubMed1986

Effect of absolute and relative changes of hematocrit on erythropoiesis in mice.

The serial changes of peripheral reticulocytes and marrow erythroid progenitor cells (CFU-e) in mice were monitored under the conditions of absolute or relative changes in red cell mass to study the regulatory mechanism of erythropoiesis. A decreased number of marrow CFU-e and peripheral reticulocytes was observed in the mice with relative polycythemia induced by dehydration as well as in the mice with absolute polycythemia induced by hypertransfusion. On the other hand, a transient increase in the number of marrow CFU-e followed by a gradual increase in the number of peripheral reticulocytes was seen after a considerable amount of exsanguination. Similar stimulatory effects on marrow CFU-e were also observed either by rehydrating the dehydrated mice or by overhydrating the untreated mice to relatively decrease the level of hematocrit. The results suggested that in addition to factors relating to the balance between oxygen supply and requirement, which has been well known, erythropoiesis is greatly affected by hematocrit.

Animals↗
PubMed1986

Immunohistological study of histiocytic necrotizing lymphadenitis.

Immunohistological study of 18 cases of histiocytic necrotizing lymphadenitis (HNL) demonstrated numerous helper/inducer cells (OKT-4) and suppressor/cytotoxic cells (OKT-8) with activation (Tac) and proliferation (OKT-9) markers, and histiocytes (lysozyme, alpha-1 anti-chymotrypsin, OK-M1) in the affected areas. However, B cells (B-1), NK cells (Leu-7 and Leu-11), complement proteins and receptor (C4 and C3d receptor), and neutrophils (chloroacetate esterase) were scanty or absent in these foci. Activity of NK cells was also decreased in the peripheral blood of 2 cases examined. The results suggest that HNL might be induced by the abnormal T cell-histiocyte response against some causative agents which induce a similar reaction of delayed hypersensitivity type.

Adolescent↗
PubMed1986

A new model of type 2 (non-insulin-dependent) diabetes mellitus in spontaneously hypertensive rats: diabetes induced by neonatal streptozotocin treatment.

This study was designed to develop an animal model of Type 2 (non-insulin-dependent) diabetes with persistent hypertension. Male spontaneously hypertensive rats were treated with 25.0, 37.5, 50.0, 62.5 or 75.0 mg/kg of streptozotocin given intraperitoneally at 2 days of age and maintained for 12 weeks. In the rats which received 50.0 mg/kg or more streptozotocin, overt hyperglycaemia gradually and consistently developed following incomplete recovery from an initial hyperglycaemia. Compared to vehicle-treated controls, body weight gain in these animals did not differ for the first 8 weeks; thereafter, it was slightly but significantly (p less than 0.05) reduced. The animals treated with 25.0 or 37.5 mg/kg streptozotocin developed mild to moderate hyperglycaemia, but their body weight gain was similar to controls. The relationships between streptozotocin dose and metabolic responses (plasma glucose, glycosylated haemoglobin, urinary glucose, food intake, etc.) were clearly demonstrated. Systolic blood pressure rose with progressing age in both controls and streptozotocin-treated rats, irrespective of dosage or metabolic response. This new rat model of Type 2 diabetes associated with persistent hypertension may be useful in studying these combined effects on small and large vessels.

Animals↗
PubMed1986

Heterogeneity of epithelial cells and reactive components in thymomas: an ultrastructural and immunohistochemical study.

Fourteen thymomas were studied by electron microscopy and immunohistochemistry. Based on the ultrastructure of the neoplastic epithelial cells in comparison with normal thymic epithelium, four cortical-, three mixed-, five medullary-, and two corpuscular-type tumors were categorized. Histologically the tumors of cortical type showed prominent lymphocytic infiltration, but scant interdigitating reticulum cells (IDCs) were demonstrated by immunoperoxidase method on paraffin sections with anti-S-100 protein antiserum. Fewer lymphocytes but more IDCs were present in the tumors of medullary and corpuscular types, although variable in those of mixed type. This corticomedullary difference among thymomas was confirmed in some of them by the immunoperoxidase method on frozen sections with monoclonal antibodies. The cortical-type tumors were HLA-DR positive in tumor cells and infiltrated predominantly with cortical thymocytes (OKT-6+, OKT-3-, both Leu 3a/3b+ and OKT-8+), whereas the medullary- and corpuscular-type tumors were HLA-DR positive primarily in IDCs but not in tumor cells and were infiltrated more with medullary thymocytes (OKT-6-, OKT-3+, either Leu 3a/3b+ or OKT-8+). The classification of thymomas based on neoplastic epithelial cells will serve to refine the traditional classification based on reactive lymphocytes.

Adult↗