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Biomedical subjects

K Ishimura

Publications and source records attributed to K Ishimura.

At least 109 records · Page 6Linked to original sources
PubMed1986

Antigenic specificity of a rabbit antiserum raised against the 15-28 segment of thymosin alpha 1.

Thymosin alpha 1, an acidic 28-residue peptide, enhances immune function. We have described a radioimmunoassay for this thymic factor based on a rabbit antiserum raised against a thymosin alpha 1-(15-28) conjugate (Incefy et al., J. Immun. Meth. 1986, in press). The detailed antigenic specificity of this antiserum was determined by measuring the ability of synthetic segments and analogues of thymosin alpha 1 and related peptides to compete with radioiodinated Ac-Tyr-thymosin alpha 1-(15-28) in this radioimmunoassay. The antiserum bound segments Ac-(1-28), (15-28), (20-28) and (21-28) with nearly equal efficiency but failed to bind segments Ac-(1-10), (11-20), (19-24) and (22-28). Thus, the major immunoreactive site seen by the antiserum is the COOH-terminal segment (21-28) (Glu-Val-Val-Glu-Glu-Ala-Glu-Asn-OH). Immunoreactivity of (21-28) was nearly abolished when the carboxylate groups of Glu-21, Glu-27 and Asn-28 were omitted separately. The antiserum bound to prothymosin alpha and thymosin alpha 11, which lack the alpha-carboxylate group of Asn-28, with 0.9 and 0.2%, respectively, of the efficiency of thymosin alpha 1. But it bound nonspecifically to parathymosin alpha, which contains the internal segment . . . -Glu-Val-Val-Glu-Glu-Glu-Glu-Asn- . . . . Residues Glu-21, Glu-27 and Asn-28 of thymosin alpha 1 may be important features of the antigenic site through their ability to induce helical structure, through the ability of their negatively charged carboxylate groups to bind to specific sites on the antibody or both.

Amino Acid Sequence↗
PubMed1986

Ultrastructural changes in the ovaries of Sl/Slt mutant mice, showing developmental deficiency of follicles and tubular adenomas.

Structural changes in the ovaries of WBB6F1-Sl/Slt mutant mice aged 10, 25, 35, and 60 days and 7 months were studied light and electron microscopically. Neither secondary nor Graafian follicles could be found in any of the animals studied, and only primary follicles were usually seen until 35 days. In most follicles, the oocyte was lost. The hyperplastic proliferation of follicle epithelial cells, forming large round or oval cell clusters, occurred in 60-day-old mice. In 7-month-old animals, the ovaries were mostly occupied with invasive peritoneal epithelial tubules and masses of epitheloid cells which are apparently derived from the follicle epithelial cells. Although the ultrastructure of the oocyte and the follicle epithelial cell of the primary follicle is not different from that of +/+ control animals, the lack of gap junctions between the oocytes and the surrounding follicle epithelial cells may cause these abnormalities. The epitheloid cells that appeared in the 60-day-old animals are suggested to produce some steroid hormones, since they have cell organelles characteristic for steroid biosynthesis, such as well-developed smooth endoplasmic reticulum, oval mitochondria with tubulovesicular cristae, and numerous lipid droplets.

Adenoma↗
PubMed1985

Ultrastructural and immunohistochemical studies on non-ciliated cells of the tracheal epithelium of normal, phenobarbital-treated and 3-methylcholanthrene-treated mice.

Non-ciliated SER-rich cells of the tracheal epithelium of normal, phenobarbital-treated and 3-methylcholanthrene-treated mice were studied ultrastructurally and immunohistochemically. The apical portion of these cells protrudes into the tracheal lumen, especially in the mice treated with the two compounds, and the apical cytoplasm is filled with numerous tubular elements of SER. Besides, the non-ciliated cells of 3-methylcholanthrene-treated mice show a strong positive reaction to the antiserum against microsomal cytochrome P-450 of liver. These findings support the concept that the non-ciliated tracheal cell may be involved in the metabolism of endogeneous and exogeneous chemical compounds.

Animals↗
PubMed1985

Immunocytochemical localization of aromatase in rat testis.

The immunocytochemical localization of aromatase in the testes of young and adult rats was investigated by an indirect-immunofluorescent method using antihuman placental aromatase-II cytochrome P-450 antibody. In both young (1 and 2 weeks old) and adult rats, only the Leydig cells in the interstitial tissue showed a positive immunoreaction for aromatase, while the germ cells and Sertoli cells in the seminiferous tubule were entirely negative. In addition, electron microscopy revealed that the Leydig cells in the testes of young as well as adult rats have a well-developed smooth endoplasmic reticulum, mitochondria with tubulovesicular cristae, and a few lipid droplets, these structures being characteristic of steroid secretory cells. On the basis of these results, we suggest that estrogens are mainly synthesized in Leydig cells of the testes.

Animals↗
PubMed1985

Ultrastructural and immunohistochemical studies on the zona-reticularis cells of the adrenal cortex of normal and 3-methylcholanthrene-treated mice.

The drug-metabolism activity of adrenocortical cells of normal and 3-methylcholanthrene (MC)-treated ddY mice were examined ultrastructurally and immunohistochemically. Immunoblot analyses performed prior to immunohistochemistry revealed the presence of a protein - possible equivalent to cytochrome P-450 found in the liver microsomes of MC-treated male rats - in the adrenal homogenate of MC-treated female mice. Immunohistochemistry demonstrated the presence of a cytochrome-P-450-like protein in the adrenal-cortical cells (especially in the zona-reticularis cells) of MC-treated female mice; at the same time, a remarkable increase in the amount of SER in these cells was observed by electron microscopy. These findings suggest that cells of the mouse adrenal gland, particularly those of the zona-reticularis, might participate not only in steroid biosynthesis but also in some sort of drug metabolism (detoxication). In addition, there might be a sex-related difference in ddY mice.

Adrenal Cortex↗
PubMed1985

Properties of porcine platelet myosin. II. Shape change of the molecule.

Porcine platelet myosin molecules were examined by electron microscopy for changes in their shape. At high ionic strength, the molecules were morphologically indistinguishable from skeletal muscle myosin, except for a slight difference in the bent regions of their tails. At physiological ionic strength, however, the following important difference was observed between the two myosins. Unlike skeletal muscle myosin, the filaments of nonphosphorylated platelet myosin could be disassembled by stoichiometric ATP into a monomeric form with sharply bent or folded tail, and reassembled after ATP hydrolysis. Similar disassembly changes could be induced by various nucleotide triphosphates (CTP, GTP, ITP, and UTP) and to a lesser extent by ADP, AMP, and AMPPNP. These results suggest that ATP binds to the hydrolytic sites in platelet myosin molecule and induces the molecular shape change.

Adenosine Triphosphate↗
PubMed1985

Light and electron microscopic immunohistochemistry on the localization of cytochrome P-450 of the side chain cleavage system and of cytochrome P-450 of 11 beta-hydroxylase in the bovine adrenal cortical cells.

In order to know the mechanism of steroid hormone biosynthesis, the localization of cytochromes P-450 of cholesterol side-chain cleavage enzymes (P-450SCC) and P-450 of 11 beta-hydroxylase (P-450(11)beta) were studied in bovine adrenal glands by light as well as electron microscopic immunohistochemistry, using monoclonal antibodies. With light microscopy the cytoplasm of the glomerulosa cells was faintly immunostained, while that of the fasciculata-reticularis cells was intensely immunostained by both monoclonal antibodies for cytochrome P-450SCC and cytochrome P-450(11)beta, though the capsular connective tissue cells and the adrenal medullary cells were entirely negative for these reactions. Electron microscopic immunohistochemistry revealed that the positive reaction products for cytochromes P-450 were present on the matrix side of the inner mitochondrial membrane including the tubulovesicular cristae of the cortical cells, and especially of the fasciculata and reticularis cells. The present results indicate that both cholesterol side-chain cleaving enzymes and 11 beta-hydroxylase are present in the inner mitochondrial membrane of bovine adrenal cortical cells.

Adrenal Cortex↗
PubMed1985

Monoclonal antibodies against bovine adrenal cytochrome P-450(11 beta) and cytochrome P-450SCC. Their isolation, characterization and application to immunohistochemical analysis of adrenal cortex.

Seven monoclonal antibodies directed against bovine adrenocortical cytochrome P-45011 beta were isolated. They were found to be immunoglobulins each having distinct affinity to the antigen. Five clones had IgG1 heavy chains, whereas the other two had IgG2b heavy chains. All the clones had kappa light chains. All the monoclonal antibodies recognized a protein among mitochondrial proteins of bovine adrenal cortex, whose mol. wt, 50,000, was the same as that of cytochrome P-45011 beta. Among the monoclonal antibodies isolated, monoclonal antibody 258 recognized a protein of Mr 50,000 in rat adrenal mitochondria, a protein of Mr 47,000 in pig adrenocortical mitochondria, a protein of Mr 50,000 in guinea pig adrenal mitochondria, a protein of Mr 55,000 in rabbit adrenal mitochondria and a protein of Mr 50,000 in human adrenocortical mitochondria. These results suggest that each of these proteins, having a mol. wt around 50,000, recognized by monoclonal antibody 258 is very likely to be the cytochrome P-45011 beta of adrenocortical mitochondria of each animal species. Monoclonal antibody 42718 inhibited by 50% the steroid hydroxylation activity of cytochrome P-45011 beta. In addition to the monoclonal antibodies against cytochrome P-45011 beta, three monoclonal antibodies directed against bovine adrenocortical cytochrome P-450SCC were also isolated and characterized. Immunohistochemical staining of bovine adrenal cortex with the use of these two kinds of monoclonal antibodies revealed that the contents of both cytochrome P-45011 beta and cytochrome P-450SCC were greater in the zona fasciculata and zona reticularis than in the zona glomerulosa. Electron microscopical observation of immunoperoxidase-stained preparations confirmed the presence of these cytochromes in the mitochondria.

Adrenal Cortex↗
PubMed1984

Immunocytochemical demonstration of caldesmon (a calmodulin-binding, F-actin-interacting protein) in smooth muscle fibers and absorptive epithelial cells in the small intestine of the rat.

The distribution of caldesmon (a calmodulin-binding, F-actin-interacting protein) (Sobue et al. 1982) and of actin was studied in the rat's small intestine by means of light-microscopic immunocytochemistry. Positive immunostaining for caldesmon was seen in smooth muscle cells of the intestinal wall, and of blood vessels, and in the apical portion of the absorptive epithelial cells. The immunoreactivity in goblet cells was difficult to recognize. The positive reaction to immunostaining for actin showed almost the same pattern as that for caldesmon. These results suggest that this calmodulin-binding protein may play an important role in the control of actin-myosin interaction in smooth muscle cells and in non-muscle cells.

Actins↗
PubMed1984

Immunocytochemical demonstration of caldesmon and actin in thyroid glands of rats.

The distribution of caldesmon (a calmodulin-binding, F-actin interacting protein; Sobue et al. 1982) and actin was studied in the rat thyroid gland by means of light-microscopic immunocytochemistry, and the fine-structural distribution of actin filaments was examined by use of heavy meromyosin (HMM). Caldesmon and actin were demonstrated in the apical cytoplasm of almost all the follicle epithelial cells in normal as well as TSH-treated animals. Immunoreactivities for both caldesmon and actin showed almost the same pattern in localization. The smooth muscle cells of the blood vessels were also positive for caldesmon and actin. By electron microscopy, numerous actin filaments decorated by HMM and running perpendicularly or randomly to the apical surface were recognized in the apical cytoplasm of the follicle epithelial cell. These results suggest that caldesmon and actin, in conjugation with calmodulin, play a role in the regulation of cellular activity such as exocytosis and endocytosis in the apical portion of the follicle epithelial cell.

Actins↗
PubMed1984

Effects of tunicamycin on thin-section and freeze-fracture images of microvilli of the duodenal epithelial cells of the mouse.

The effect of tunicamycin, which is known to inhibit the synthesis of N-linked glycoprotein, on the duodenal absorptive epithelial cell of the mouse was studied in thin-section as well as freeze-fracture images. In tunicamycin-treated animals, the apical part of the epithelial cell was almost negative to the PAS reaction. Moreover, microvilli of the epithelial cell became shorter, larger in diameter, and fewer in number in tunicamycin-treated mice. In addition, freeze-fracture images revealed that the population density of membrane particles of the microvillus membrane was lowered by tunicamycin treatment. These results may indicate that the inhibition of synthesis of N-linked glycoprotein causes a decrease of membrane supply from the Golgi apparatus to the apical plasma membrane.

Animals↗
PubMed1984

An arachnoid cyst in an 8-year-old boy with neurofibromatosis.

Although associations of a variety of developmental abnormalities of the brain and the spinal cord with neurofibromatosis have been reported, association of a cerebral arachnoid cyst with neurofibromatosis is extremely rare. We report the second case of this association in an 8-year-old Japanese boy.

Arachnoid↗
PubMed1984

Cholesterol accumulation in adrenocortical mitochondria after ACTH-stimulation.

Rat adrenocortical cell suspensions (10(6) cells) were incubated with ACTH (40 nM) in 2 ml of Krebs-Ringer bicarbonate buffer for 90 min. About 42 nmol of corticosterone and 14 nmol of 18-hydroxydeoxycorticosterone were generated and released into the medium. Aminoglutethimide at 50 microM inhibited the steroidogenesis to 16%. Mitochondrial pellets were prepared from the cells incubated in the absence, or in the presence, of ACTH and aminoglutethimide, and cholesterol content was determined. The mitochondria of the cells incubated without the drugs contained 25.2 micrograms cholesterol/mg protein. Cholesterol content increased by 10% in the mitochondria of the ACTH-stimulated cells. The mitochondria of the cells incubated in the presence of both ACTH and aminoglutethimide contained 143% of cholesterol compared to those of the nontreated cells. When rats were subjected to ether stress after aminoglutethimide pretreatment, cholesterol content of the mitochondrial fraction increased to about 200% compared to that of the control rats. These results suggest that a cholesterol pool exists in the adrenocortical mitochondria and that the amount increases during the steroidogenic stimulation of the cells. The mitochondria were fixed with filipin-containing fixative and examined by freeze-fracture electron microscopy. Accumulations of filipin-cholesterol complexes were observed in the inner membrane of the mitochondria as protuberances or pits 25 nm in diameter.

Adrenal Cortex↗