Biomedical subjects

M Ishikawa

Publications and source records attributed to M Ishikawa.

At least 19 recordsLinked to original sources

PubMed1992

Yolk vitronectin. Purification and differences from its blood homologue in molecular size, heparin binding, collagen binding, and bound carbohydrate.

This is the first report on a unique vitronectin molecule, yolk vitronectin, which is similar to its blood homologue in cell spreading activity but different in molecular size, bound carbohydrate, and heparin and collagen binding activity. Yolk vitronectin was purified 2,500-fold from chick egg yolk by a combination of hydroxylapatite, DEAE-cellulose, and anti-vitronectin-Sepharose column chromatographies. In SDS-polyacrylamide gel electrophoresis under reducing conditions, yolk vitronectin was separated into 54- and 45-kDa bands, which are 16 and 25 kDa smaller, respectively, than the 70-kDa major band of chick blood vitronectin. The 54-kDa band shares the same NH2-terminal sequence as chick blood vitronectin. In contrast, the NH2-terminal sequence of the 45-kDa band is somewhat homologous with the internal sequences of mammalian vitronectins beginning at the 50th amino acid from the NH2 terminus. The bound carbohydrate of the 54- and 45-kDa species of yolk vitronectin is similar to, but distinct from, that of blood vitronectin. Unlike blood vitronectin, yolk vitronectin cannot bind to either heparin or collagen.

Amino Acid Sequence↗

PubMed1992

Protection by chlorpromazine against lethality and renal toxicity of cisplatin in mice.

The effect of chlorpromazine on acute lethal toxicity and nephrotoxicity induced by cisplatin was studied in mice. Chlorpromazine given (i.p.) 1 h before cisplatin greatly reduced lethal and renal toxicities of cisplatin. Chlorpromazine did not reduce the antitumor activity of cisplatin against Sarcoma 180 in ddY mice or EL-4 Leukemia in C57BL/6J mice.

Animals↗

PubMed1992

Granulocyte-colony stimulating factor stimulates immunoreactive endothelin-1 release from cultured bovine endothelial cells.

We examined the effect of human recombinant granulocyte-colony stimulating factor (G-CSF) on the release of immunoreactive endothelin-1 (ET-1) from cultured bovine vascular endothelial cells. G-CSF dose dependently (10(-8)-10(-6) M) increased the release of immunoreactive ET-1 as a function of time under a serum-free condition. Coaddition of G-CSF and thrombin induced an additive effect on immunoreactive ET-1 release. Neither Ca2+ channel antagonist nor cyclooxygenase inhibitor affected immunoreactive ET-1 release stimulated by G-CSF. These results suggest that G-CSF, in addition to its effect on granulocyte progenitors, has a direct effect on vascular endothelium to induce the release of immunoreactive ET-1.

Animals↗

PubMed1992

Purification and characterization of a diptericin homologue from Sarcophaga peregrina (flesh fly).

A protein with a molecular mass of 8 kDa was found to be synthesized specifically when the fat-body from injured Sarcophaga peregrina larvae was cultured in vitro. This protein was purified from the haemolymph of the injured larvae to near-homogeneity. Partial amino acid sequencing revealed that this protein is a diptericin homologue. It showed bactericidal activity on growing, but not resting Escherichia coli cells. E. coli cells become elongated on treatment with this protein.

Amino Acid Sequence↗

PubMed1992

Molecular cloning of bovine actin-like protein, actin2.

Actins are major cytoskeletal components and highly conserved in evolution. In mammals, there are six actin isoforms, a pair of which shows at least 93% identity in the amino acid sequence. We have cloned cDNA for a bovine protein that is distantly related to members of the mammalian actin isotypes. The predicted amino acid sequence (418 residues long, calculated molecular mass 47369) shows that this protein, which we have named actin2, exhibits 36% identity to mammalian actins and 60% identity to the yeast actin-like protein, act2. We have concluded that actin2 defines a new class of mammalian actin-like proteins. It was also revealed that actin2 messenger RNA is expressed in a broad range of tissues.

Actins↗

PubMed1992

Detailed structural analysis of asparagine-linked oligosaccharides of the nicotinic acetylcholine receptor from Torpedo californica.

The structures of the major oligosaccharide moieties of the nicotinic acetylcholine receptor (AcChoR) protein from Torpedo californica have been reported [Nomoto, H., Takahashi, N., Nagaki, Y., Endo, S., Arata, Y. and Hayashi, K. (1986) Eur. J. Biochem. 157, 233-242] to be high-mannose types. Here we report detailed analyses of the structures of the remaining oligosaccharides in this receptor. The sialylated oligosaccharides released by glycopeptidase (almond) digestion were separated according to the number of sialic acid residues using high-performance anion-exchange chromatography with pulsed amperometric detection. After removal of sialic acid from each fraction, the resulting neutral oligosaccharides were separately pyridylaminated and were analyzed by a combination of sequential exoglycosidase digestion and HPLC, then identified on a two-dimensional sugar map. The structures of two desialylated pyridylamino-oligosaccharides were further analyzed by high-resolution proton NMR. Each oligosaccharide was composed of species containing varying numbers of sialic acids. The desialylated complex-type oligosaccharides of AcChoR consisted of ten, eight and one different biantennary, triantennary and tetraantennary oligosaccharide, respectively. The biantennary oligosaccharides were divided into two groups; oligosaccharides with fucose at the proximal N-acetylglucosamine (six varieties) and oligosaccharides without fucose (four varieties). Each group consisted of species differing in the number of terminal galactose residues. The major component of the biantennary oligosaccharides had two galactose residues at the non-reducing termini. The terminal alpha-galactose residue(s) linked to C3 of beta-galactose were found in the fucose-containing biantennary oligosaccharides (two varieties). The triantennary oligosaccharides were also divided into two groups; oligosaccharides with (four varieties) and without (four varieties) besecting N-acetylglucosamine. These groups were composed of species differing in the number of terminal galactose residues. The major component of the triantennary oligosaccharides was fully galactosylated with three galactose residues. An unusual group, Gal beta 1-3GlcNAc, was present in low levels in the triantennary oligosaccharides. In contrast, the tetraantennary oligosaccharide was composed of only one species, which is fully galactosylated with four galactose residues.

Animals↗

PubMed1992

Proteolytic processing of human lysosomal arylsulfatase A.

Arylsulfatase A purified from human placenta contained an unreported component with an apparent molecular mass of 7 kDa in addition to the two known components with apparent molecular masses of 58 and 50 kDa. The detailed relationship between the 58 kDa component and the 50 kDa component is as yet unknown. The present study was undertaken to define the structure of the subunits of the sulfatase. The N-terminal sequence of the 50 kDa component was identical to that of the 58 kDa component. Furthermore, the peptide maps of the 50 kDa component, which was separately digested with trypsin and Achromobacter proteinase I, were quite similar to those of the 58 kDa one. Through sequence analysis of the incompatible peaks in the peptide maps, the 50 kDa component was found to lack a sequence from Val-445 to the C-terminus. On the other hand, the N-terminal sequence of the 7 kDa component began with Ala-448, though there was a minor sequence commencing with Thr-449. These observations suggest that the 50 and 7 kDa components were produced by limited proteolysis near the C-terminus of the 58 kDa component. Through analysis using unreducing SDS-PAGE, the 58 and the 7 kDa components were found to be linked by disulphide bonds. Arylsulfatase A purified from human liver was also composed of the same subunits as the placental one. This finding suggests that human arylsulfatase A undergoes similar proteolytic processing regardless of the tissue involved.

Amidohydrolases↗

PubMed1992

Activation of the collagen-binding of endogenous serum vitronectin by heating, urea and glycosaminoglycans.

The present study describes that the collagen-binding activity of vitronectin in human serum increases by treatment with heparin, heating and urea. Vitronectin purified from human serum was bound to native collagen, whereas endogenous vitronectin in the serum was not. We have examined the conditions to change the collagen-binding activity of endogenous vitronectin. Endogenous vitronectin in human serum became considerably bound to collagen when the serum was boiled in 4-8 M urea for 5 min and mixed with heparin (0.5-5 micrograms/ml). Each treatment of heating, urea or heparin alone, and any combination of the two factors, inefficiently activated the binding. Dextran sulfate could substitute for heparin, but dermatan sulfate, keratan sulfate, chondroitin sulfate A and C, heparan sulfate and hyaluronan could not. Possible explanations for the activation of endogenous vitronectin are discussed.

Blood Proteins↗

PubMed1992

Changes in cerebral energy metabolism and calcium levels in relation to delayed neuronal death after ischemia.

Using a brief transient ischemic model, we examined changes in regional tissue calcium content and energy metabolism in the hippocampus. In the CA1 region, tissue calcium ions began to increase 24 h after reperfusion, accompanied by changes in tissue pH and ATP. In the CA3 region, energy metabolism remained unchanged for 72 h after reperfusion, and the calcium pool was first noted 24 h after reperfusion, while tissue calcium ions began to increase 48 h after reperfusion. These results suggest that the neurons in the CA3 region seem to survive because of the well-preserved metabolic function to cope with excessive calcium ions.

Adenosine Triphosphate↗

PubMed1992

Vitronectin diversity in evolution but uniformity in ligand binding and size of the core polypeptide.

We isolated vitronectins from the plasma or sera of 14 animal species including mouse and rat by heparin affinity chromatography. They cross-reacted with anti-vitronectin antibody and their amino terminal sequences showed strong homology. They also promoted spreading of BHK cells and were bound to heparin and collagen in the same way. Therefore, these properties appear to be essential for vitronectin function. However, the apparent molecular weights of these vitronectins varied considerable from 59 to 78 kDa in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). In addition, the number of bands also varied from 1 to 3. To search for the uniformity of vitronectin polypeptide, vitronectins were deglycosylated and examined by Ferguson plot analysis. The size of the polypeptide portion of vitronectins was estimated to range from 40 to 57 kDa which was 19-26 kDa smaller than original values. Supposing a possible cleavage site at 5-13 kDa far from the carboxyl terminus, all vitronectin polypeptides were speculated to be synthesized de novo in the size range of 50-57 kDa. Proteins reacting with anti-vitronectin antibody were also detected on the immunoblot of 13 more species including Drosophila and Physarum. Almost all of these vitronectin-like proteins showed marked species-specific variations in their apparent molecular weights from 51 to 96 kDa in SDS-PAGE.

Amino Acid Sequence↗

PubMed1992

Structural details of ribonuclease H from Escherichia coli as refined to an atomic resolution.

The crystal structure of RNase H from Escherichia coli has been determined by the multiple isomorphous replacement method, and refined by the stereochemically restrained least-squares procedure to a crystallographic R-factor of 0.196 at 1.48 A resolution. In the final structure, the root-mean-square (r.m.s.) deviation for bond lengths is 0.017 A, and for angle distances 0.036 A. The structure is composed of a five-stranded beta-sheet and five alpha-helices, and reveals the details of hydrogen bonding, electrostatic and hydrophobic interactions between intra- and intermolecular residues. The refined structure allows an explanation of the particular interactions between the basic protrusion, consisting of helix alpha III and the following loop, and the remaining major domain. The beta-sheet, alpha II, alpha III and alpha IV form a central hydrophobic cleft that contains all six tryptophan residues, and presumably serves to fix the orientation of the basic protrusion. Two parallel adjacent helices, alpha I and alpha IV, are associated with a few triads of hydrophobic interactions, including many leucine residues, that are similar to the repeated leucine motif. The well-defined electron density map allows detailed discussion of amino acid residues likely to be involved in binding a DNA/RNA hybrid, and construction of a putative model of the enzyme complexed with a DNA/RNA hybrid oligomer. In this model, a protein region, from the Mg(2+)-binding site to the basic protrusion, covers roughly two turns of a DNA/RNA hybrid double helix. A segment (11-23) containing six glycine residues forms a long loop between the beta A and beta B strands. This loop, which protrudes into the solvent region, lies on the interface between the enzyme and a DNA/RNA hybrid in the model of the complex. The mean temperature factors of main-chain atoms show remarkably high values in helix alpha III that constitutes the basic protrusion, suggesting some correlation between its flexibility and the nucleic acid binding function. The Mg(2+)-binding site, surrounded by four invariant acidic residues, can now be described more precisely in conjunction with the catalytic activity. The arrangement of molecules within the crystal appears to be dominated by the cancelling out of a remarkably biased charge distribution on the molecular surface, which is derived in particular from the separation between the acidic Mg(2+)-binding site and the basic protrusion.

Amino Acid Sequence↗

PubMed1992

An immunohistochemical study with an estrogen receptor-related protein (ER-D5) in human colorectal cancer.

The ER-D5 antigen is a protein associated with the estrogen receptor that is present only in estrogen receptor-positive tissues. To clarify the estrogen receptor in colon cancer, the localization of ER-D5 was studied immunohistochemically. Forty-three of 171 (25.1%) specimens of colon cancer showed reactivity for ER-D5. Reactivity was seen only in the cytoplasm. No reactivity was seen in cancer limited to the mucosa or in adenoma, but submucosal cancers showed a rate of positivity similar to cancers that involved lamina muscularis and beyond. Estradiol staining was done on serial sections from 56 specimens. There was a significant relationship between reactivity for estradiol and that for ER-D5. In the 15 specimens where both ER-D5 and estradiol were positive, the distribution of estradiol was similar to that of ER-D5. It was concluded that the immunohistochemical localization of ER-D5 indirectly shows that of the estrogen receptor in colorectal cancer tissues.

Adenocarcinoma↗

PubMed1992

A novel tumor-associated protein: clinical significance of serum levels in various clinical conditions with special reference to gynecological malignant diseases.

A novel tumor-associated protein (TAP), that was originally detected immunologically through the use of a monospecific antiserum against a placental antigen, was quantified by means of the rocket technique of Laurell. Four hundred and fifty-seven serum samples were obtained from healthy female subjects (55), and patients with leiomyomas (162), benign ovarian tumors (78), pelvic endometriosis (45), cervical cancer (73), endometrial cancer (18) and ovarian cancer (26), respectively. Statistical analysis showed that TAP exhibited the closest relationship in ovarian cancer patients in whom the appearance of TAP and its high level were most prominent. The present preliminary study suggests the clinical usefulness of this protein as a clinical adjunct for the management of ovarian cancer.

Antigens, Differentiation, T-Lymphocyte↗

PubMed1992

Xenopus MAP kinase activator is a serine/threonine/tyrosine kinase activated by threonine phosphorylation.

Xenopus MAP kinase activator, a 45 kDa protein, has been shown to function as a direct upstream factor sufficient for full activation and both tyrosine and serine/threonine phosphorylation of inactive MAP kinase. We have now shown by using an anti-MAP kinase activator antiserum that MAP kinase activator is ubiquitous in tissues and is regulated post-translationally. Activation of MAP kinase activator is correlated precisely with its threonine phosphorylation during the oocyte maturation process. It is a key question whether MAP kinase activator is a kinase or not. We have shown that Xenopus MAP kinase activator purified from mature oocytes is capable of undergoing autophosphorylation on serine, threonine and tyrosine residues. Dephosphorylation of purified activator by protein phosphatase 2A treatment inactivates its autophosphorylation activity as well as its activator activity. Thus, Xenopus MAP kinase activator is a protein kinase with specificity for both serine/threonine and tyrosine. Partial protein sequencing of purified activator indicates that it contains a sequence homologous to kinase subdomains VI and VII of two yeast protein kinases, STE7 and byrl.

Amino Acid Sequence↗

PubMed1992

Vitreous, retinal and subretinal hemorrhages associated with von Willebrand's syndrome.

Two patients with von Willebrand's syndrome had intraocular hemorrhages without trauma or neovascularization. A 13-year-old Japanese girl complained of sudden spotted vision in her left eye. Vitreous, peripapillary retinal, and subretinal hemorrhages were seen by ophthalmoscopy in the affected eye. In addition, a 19-year-old Japanese man had repeated vitreous hemorrhage and epistaxis. Also noted was gyrate atrophy of the choroid and retina. Analysis of the coagulation-fibrinolysis system revealed decreased activities of Factor VIII and von Willebrand's factor in both patients. The amount of von Willebrand's factor antigen also was decreased. These results suggested that the patients had von Willebrand's syndrome. The bleeding tendency in the disorder appeared to be responsible for the pathogenesis of the intraocular hemorrhages seen in these patients.

Adolescent↗

PubMed1992

A case of treatment-related leukoencephalopathy: sequential MRI, CT and PET findings.

A case of treatment-related leukoencephalopathy is presented. A patient with medulloblastoma was postoperatively treated with craniospinal axis irradiation. One month after irradiation, weekly intrathecal administration of methotrexate was performed 4 times to treat cerebrospinal fluid dissemination of the tumor. Two months after the initiation of intrathecal chemotherapy, the patient became somnolent and developed decerebrate posturing. Magnetic resonance imaging showed diffuse leukoencephalopathy. Positron emission tomography revealed a diffuse decrease in glucose uptake in the deep white matter. Auditory evoked potential also showed diffuse abnormalities, not only in the cerebrum, but also in the brain stem. High dose intravenous leucovorin rescue was attempted without any neurologic improvement.

Blood Proteins↗

PubMed1992

Effects of platelet activating factor on mouse sperm function.

Platelet activating factor (PAF) has been implicated in a variety of reproductive processes. This study was designed to investigate the effect of PAF and the specific PAF receptor antagonist, CV-3988, on capacitation and the acrosome reaction in mouse spermatozoa using an in vitro fertilization (IVF) system. When spermatozoa were preincubated for 30 min in medium containing PAF (10(-7) to 10(-11) M), a significant increase in the fertilization rate with both cumulus-free and zona-free oocytes was observed. In contrast, treatment of the spermatozoa with 10(-5) M CV-3988 caused a significant decrease in both sperm motility and fertilization rates with zona-intact and zona-free oocytes. This suppression was reversed by the addition of PAF. Furthermore, the acrosome reaction was enhanced by PAF treatment of spermatozoa in a dose-dependent manner. This stimulation of the acrosome reaction by PAF required the presence of calcium ions in the medium. While 10(-5) M CV-3988 inhibited the acrosome reaction, the inhibition was also reversed by the addition of PAF. These results suggest that PAF can stimulate not only the capacitation process but also the acrosome reaction, both of which are dependent on extracellular calcium.

Acrosome↗

PubMed1992

Inverse dose-rate effect of DNA breaks and inactivation of transforming activity induced by tritiated water and 60Co gamma-rays.

When an aqueous solution of plasmid DNA at a constant low concentration of 5 micrograms/cm3 was irradiated with 60Co gamma-rays, D37 dose of single-strand breaks was decreased from 18 Gy at a dose-rate of 6.77 Gy/h of acute irradiation to 2.3 Gy at a dose-rate of 0.00212 Gy/h. Or G value was increased from 0.0010 to 0.0081. Similar dose-rate dependency of D37 dose and G value were also found when the plasmid DNA solution was treated with various concentrations of tritiated water at various dose-rates, ranging from 5.13 Gy/h to 0.000118 Gy/h. RBE of tritium beta-rays for single-strand breaks was ranged from 0.3 to 0.5 in a wide range of dose-rates. When the DNA solution was saturated with argon to remove oxygen, the dose-rate dependency of gamma-rays was abolished and that of tritium beta-rays was significantly suppressed. When the DNA solution in air was kept at 4 degrees C for 50 h or 25 days after acute irradiation, the G value of DNA breaks was the same as that kept at -20 degrees C for the same period, but much lower than that of the solution irradiated for the same period at a lower dose-rate to give the same total doses. This shows that the inverse dose-rate effect could not be induced from the different exposure periods but from continuous irradiation of different dose-rates. The inverse dose-rate effect for inactivation of transforming activity of DNA irradiated with tritiated water was also observed in the range from 0.0588 Gy/h to 0.00118 Gy/h.

Cobalt Radioisotopes↗