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N Okada

Publications and source records attributed to N Okada.

At least 271 records · Page 15Linked to original sources
PubMed1994

Molecular cloning of the rat complement regulatory protein, 5I2 antigen.

We have cloned a cDNA which encoded for rat complement regulatory protein, 5I2 antigen. The deduced amino acid sequence of 497 residues predicted essentially the same domain structure as the mouse complement regulatory protein, Crry/p65, composed of five short consensus repeat (SCR) domains, a transmembrane domain and a cytoplasmic domain. 5I2 antigen, however, had an additional SCR which showed a close similarity to the sixth SCR of mouse complement receptor 1 (CR1) or to the sixth, thirteenth, twentieth and twenty seventh SCR of human CR1. Corresponding domains of 5I2 antigen and mouse Crry/p65 showed 70%-86% amino acid identity, indicating that 5I2 antigen is the rat counterpart of mouse Crry/p65.

Amino Acid Sequence↗
PubMed1994

Identification and characterization of membrane cofactor protein (CD46) in the human kidneys.

Membrane cofactor protein (MCP, CD46) is an integral protein that serves as a cofactor for factor I in inactivating C3b/C4b deposited on the same cell membrane as C3bi/C4c+C4d. This C3b/C4b inactivation is closely associated with self-protection of host cells from autologous complement attack. We have studied the distribution and properties of MCP in the normal human kidney by immunohistochemical and immunoblotting methods using monoclonal antibodies against MCP. MCP was predominantly expressed on the juxtaglomerular apparatus. Glomerular capillary walls, mesangial areas, and tubulus were also MCP positive. Glomerulus MCP was composed of two major bands of 45-65 kDa, which were similar to those of lymphocyte MCP. The proportion of the high and low molecular weight components in glomerulus MCP, however, was considerably different from that of lymphocyte MCP among the individual samples tested. Glomerular epithelial cells and mesangial cells from an individual having equal amounts of high and low molecular weight components in the lymphocytes were cultured separately and the properties of their MCP investigated. MCP in the mesangial cells and glomerular epithelial cells showed profiles in which the upper band was predominant. The results may explain the unique distribution of the high and low molecular weight forms in the glomerulus. These forms of MCP together with factor I were all capable of inactivating C3b to C3bi. Message analysis suggested that glomerular epithelial cells and mesangial cells synthesized a single species of mRNA of 4.2 kb from which the polymorphic MCP species were generated. Flow cytometric analysis suggested that MCP was minimal in mesangial cells. These results, taken together with the previous reports on the distribution of other complement regulatory proteins, infer that the distribution profile of MCP is rather similar to that of DAF but differs from those of CD59 and CR1 in the normal human kidney; this may reflect the differences between their roles or functional properties in renal tissue.

Antigens, CD↗
PubMed1994

Relationship among coelacanths, lungfishes, and tetrapods: a phylogenetic analysis based on mitochondrial cytochrome oxidase I gene sequences.

To clarify the relationship among coelacanths, lungfishes, and tetrapods, the amino acid sequences deduced from the nucleotide sequences of mitochondrial cytochrome oxidase subunit I (COI) genes were compared. The phylogenetic tree of these animals, including the coelacanth Latimeria chalumnae and the lungfish Lepidosiren paradoxa, was inferred by several methods. These analyses consistently indicate a coelacanth/lungfish clade, to which little attention has been paid by previous authors with the exception of some morphologists. Overall evidence of other mitochondrial genes reported previously and the results of this study equally support the coelacanth/lungfish and lungfish/tetrapod clades, ruling out the coelacanth/tetrapod clade.

Amino Acid Sequence↗
PubMed1994

PCPA reduces both monoaminergic afferents and nonmonoaminergic synapses in the cerebral cortex.

In order to examine the possible trophic, nontransmitter role of monoaminergic fibers in the adult CNS, synaptic structures were examined in different laminae of the somatosensory cortex of the rat following a p-chlorophenylalanine (PCPA)-induced decrease of monoamine. Synaptic densities were reduced in a dose-dependent fashion by 30-50% in the target area of monoamine fibers following four injections of PCPA made over a 1-week period. Although serotonin- and tyrosine hydroxylase-immunopositive profiles were frequently observed in all laminae of the cerebral cortex, only a few such profiles had the morphology of synapses. Therefore, virtually all of the reduction in synaptic structures following PCPA treatment involved nonmonoaminergic fibers.

Animals↗
PubMed1994

Partial characterization of a low molecular weight phagocytosis inhibitory factor obtained from human erythrocyte membranes.

Phagocytosis Inhibitory Factor (PIF), a small (< 3000 D) molecule, was partially purified from human red blood cell membranes. This factor inhibits latex phagocytosis by monocytic cells. PIF is not toxic under the experimental conditions employed and the phagocytosis inhibitory activity is reversible since removal of this factor restores the phagocytic capability of cells. The phagocytic activity of murine macrophages was not affected by PIF.

Animals↗
PubMed1994

Epstein-Barr virus-associated large granular lymphocyte leukemia with cutaneous infiltration.

A 36-year-old man had a high titer of antibody to Epstein-Barr virus (EBV) and recurrent necrotizing papules and nodules on his face and oral mucosa. The disease was diagnosed as CD3+4- 8+ large granular lymphocyte leukemia of T-cell origin. Southern blot analysis demonstrated that EBV DNA was present in CD8+ lymphocytes; EBV antigens were also observed in these lymphocytes. These findings demonstrated that EBV latently infected the leukemic cells and may have played a role in the pathogenesis of this disease. This is the first report of an association between EBV and large granular lymphocyte leukemia of T-cell origin.

Adult↗
PubMed1994

Upregulation of human neutrophil CD59, a regulator of the membrane attack complex of complement, following cell activation.

CD59 is a membrane glycoprotein that regulates the membrane attack complex of complement and protects cells from autologous complement damage. Human polymorphonuclear leucocyte (PMN) expression of CD59 was confirmed by flow cytometry following staining with mAb 1F5, and western blotting revealed staining of a 19-23 kDa band. Warming of PMN from 4 to 37 degrees C resulted in spontaneous CD59 upregulation. A dose-dependent increase in expression following PMN stimulation with FMLP was observed and occurred within minutes, indicating that new protein synthesis was not required. Treatment of PMN with calcium ionophore A23187 resulted in similar increases in CD59 expression. This occurred in the presence or absence of extracellular calcium, indicating that upregulation was dependent on release of calcium from intracellular stores. Evidence for a mobilizable intracellular pool of CD59 was obtained by detection of increased binding of 1F5 following PMN permeabilization; CD59 could also be re-expressed after stripping by phosphatidylinositol specific phospholipase C (PI-PLC) by treatment with FMLP or A23187. There was a correlation between CD59 upregulation and lactoferrin release, suggesting that stores of CD59 may be associated with secondary granules. These studies indicate that PMN expression of CD59 is enhanced by cell activation and suggest the presence of an intracellular pool of CD59 which can be translocated to the cell membrane upon PMN stimulation.

Antibodies, Monoclonal↗
PubMed1994

Antimetastatic effects of synthetic peptides containing the core sequence of the type III connecting segment domain (IIICS) of fibronectin.

The antimetastatic activities of synthetic peptides corresponding to fragments of the adhesion-related molecules, such as fibronectin and laminin, were examined. We prepared three peptides derived from the type III connecting segment domain (IIICS) of fibronectin: Glu-Ile-Leu-Asp-Val (EILDV), Glu-Ile-Leu-Asp-Val-Pro-Ser-Thr (EILDVPST), Arg-Glu-Asp-Val (REDV), and a laminin-related peptide, Tyr-Ile-Gly-Ser-Arg (YIGSR). Each peptide inhibited the experimental tumor metastasis of B16-BL6 melanoma, while EILDV had the strongest effect. The peptides conjugated with poly(ethylene glycol) (PEG) were more effective than the unmodified peptides in molar ratio terms. A mixture composed of PEG hybrids with EILDV, REDV and YIGSR significantly inhibited tumor metastasis.

Amino Acid Sequence↗
PubMed1994

The use of CT and scintigraphy in diagnosing a cystic ameloblastoma of the jaw.

The results of CT and bone scintigraphy of eight patients with a histologically proven cystic ameloblastoma of the jaw are reviewed. CT imaging revealed unilocular and multilocular cystic lesions with well-defined thin cystic borders in all patients. CT also detected increased density in the bone marrow adjacent to the cystic radiolucent lesion, suggesting that the ameloblastoma had spread into the cancellous bone. Further, nuclear bone scans showed a doughnut-shaped pattern in all cases and radioactivity beyond the cystic wall, indicating intramedullary extension of the ameloblastoma. The use of these two modalities was found to be complementary in delineating the full nature and extent of the pathologic lesion.

Adult↗
PubMed1994

Bone mineral density of the lumbar spine in psoriatic patients with long term etretinate therapy.

Etretinate has been known to produce a variety of skeletal manifestations when administered for prolonged periods. To study whether osteoporotic changes occurred during the treatment bone mineral density (BMD) was measured by dual energy X-ray absorptiometry in 13 psoriatic patients who received long term etretinate therapy (average 3.7 yrs). The values of BMD of the lumbar spine in these patients were decreased from those of age-matched controls (92.3 +/- 9.7%), p < 0.01), while those in psoriatic patients who received topical corticosteroid applications alone showed no significant decrease. Our findings suggest that long term etretinate intake induces an increased risk of osteoporotic changes.

Absorptiometry, Photon↗
PubMed1994

Membrane-bound complement regulatory activity is decreased on vaccinia virus-infected cells.

Decay accelerating factor (DAF), membrane cofactor protein (MCP), complement receptor 1 and mouse Crry are cell surface-bound complement regulatory proteins capable of inhibiting C3 convertase activity on cell membranes, and therefore provide a substantial protection from attack by homologous complement activated either by the classical or by the alternative pathway. Decrease in complement regulatory activity might lead to spontaneous complement deposition and subsequent cell injury. MoAb 5I2 can inhibit the complement regulatory activity of molecules on rat cells, resulting in deposition of homologous complement. The antigen recognized by 5I2 MoAb in rats is homologous to mouse Crry. Fifteen to 20 h after infection with vaccinia virus, in vitro cultured KDH-8 rat hepatoma cells show a strong decrease in expression of Crry-like antigen, and proved to be sensitive to complement deposition when 1:5 diluted normal rat serum was added to the culture medium as a source of complement. Addition of complement to the cultured KDH-8 cells infected with a very low dose of vaccinia virus (1 plaque-forming unit (PFU)/1000 cells) substantially reduced spreading of virus infection in the cell culture, while inactivation of complement by heat or zymosan treatment abrogated the protective effect.

Animals↗
PubMed1994

vacC, a virulence-associated chromosomal locus of Shigella flexneri, is homologous to tgt, a gene encoding tRNA-guanine transglycosylase (Tgt) of Escherichia coli K-12.

The genetic determinants required for invasion of epithelial cells by Shigella flexneri and for the subsequent bacterial spreading are encoded by the large virulence plasmid. Expression of the virulence genes is under the control of various genes on the large plasmid as well as on the chromosome. We previously identified one of the virulence-associated loci near phoBR in the NotI-C fragment of the chromosome of S. flexneri 2a YSH6000 and designated the locus vacC. The vacC mutant showed decreased levels of IpaC, and IpaD proteins as well as transcription of ipa, an operon essential for bacterial invasion (N. Okada, C. Sasakawa, T. Tobe, M. Yamada, S. Nagai, K. A. Talukder, K. Komatsu, S. Kanegasaki, and M. Yoshikawa, Mol. Microbiol. 5:187-195, 1991). To elucidate the molecular nature of the vacC locus, we cloned the vacC region from YSH6000 on a 1.8-kb SalI-BamHI DNA fragment. The nucleotide sequence of the 1,822-bp vacC clone was highly (> 98%) homologous to the tgt region of Escherichia coli K-12, which is located at 9.3 min on the linkage map. Complementation tests indicated that the vacC function was encoded by an open reading frame expressing a 42.5-kDa protein, which corresponded to the tgt gene of E. coli K-12, coding for tRNA-guanine transglycosylase (Tgt) (K. Reuter, R. Slany, F. Ullrich, and H. Kersten, J. Bacteriol. 173:2256-2264, 1991). The cloned tgt gene from E. coli K-12 restored the virulence phenotype to the vacC mutant of YSH6000. Characterization of the vacC mutant indicated that levels of VirG, a protein essential for bacterial spreading, and VirF, the positive regulator for the expression of the virG and ipaBCD operons, decreased significantly compared with those of the wild type. Similar phenotypic changes occurred in vacC mutants constructed by insertion of a neomycin resistance gene in shigellae and enteroinvasive E. coli strains, consistent with the hypothesis that the vacC (tgt) gene contributes to the pathogenicity of Shigella flexneri.

Amino Acid Sequence↗
PubMed1994

Nucleotide sequence of the rhamnose biosynthetic operon of Shigella flexneri 2a and role of lipopolysaccharide in virulence.

N1308, a chromosomal Tn5 mutant of Shigella flexneri 2a, was described previously as a lipopolysaccharide (LPS) mutant with a short O side chain. N1308 formed foci, but not plaques, in LLC-MK2 cell monolayers and was negative in the Serény test. In this study, the wild-type locus inactivated in N1308 was cloned and further defined by means of complementation analysis. A 4.3-kb BstEII-XhoI fragment of S. flexneri 2a YSH6200 DNA was sufficient to restore both normal LPS and virulence phenotype to the mutant. DNA sequencing of this region revealed four genes, rfbA, rfbB, rfbC, and rfbD, encoding the enzymes required for the biosynthesis of activated rhamnose. The four genes were expressed in Escherichia coli, and the expected protein products were visualized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. N1308 was shown to have normal levels of surface IpaC and IpaD, while a Western blot (immunoblot) of whole-cell lysates or outer membrane fractions indicated an elevated level of appropriately localized VirG. An in vitro invasion assay revealed that N1308 had normal primary invasive capacity and was able to multiply and move normally within the initial infected cell. However, it exhibited a significant reduction in its ability to spread from cell to cell in the monolayer. A double immunofluorescence assay revealed differences between LLC-MK2 cells infected with the wild-type YSH6000 and those infected with N1308. The wild-type bacteria elicited the formation of the characteristic F-actin tails, whereas N1308 failed to do so. However, N1308 was capable of inducing deposition of F-actin, which accumulated in a peribacterial fashion with only slight, if any, unipolar accumulation of the cytoskeletal protein.

Amino Acid Sequence↗
PubMed1994

Pancreatic exocrine secretion in short-term pancreatic duct obstruction induced acute pancreatitis in rats: an in vivo and in vitro study.

We investigated digestive enzyme release following a short-term pancreatic duct obstruction in rats. An in vivo experiment demonstrated that a 6-hour pancreatic duct obstruction reduced digestive enzyme release evoked both by endogenously released cholecystokinin (CCK) due to pancreaticobiliary diversion and by exogenous administration of CCK8. In vitro experiments also showed that pancreatic duct obstruction reduced the maximal CCK8-evoked amylase secretion. Amylase secretion evoked by the calcium ionophore A23187 and by phorbol myristate acetate was also markedly decreased. These data suggest that pancreatic duct obstruction probably interferes with the secretory process downstream of hormone receptor binding, intracellular Ca2+ release and protein kinase C activation.

Acute Disease↗
PubMed1994

Pro-carboxypeptidase R cleaves bradykinin following activation.

Arginine carboxypeptidase (CPR) is a labile enzyme present in human serum which is unrelated to carboxypeptidase N. In this study we demonstrate that CPR exists in a precursor form in plasma and can be converted to the active form by trypsin and presumable trypsin-like enzymes. The trypsin-generated active form can not only cleave a small synthetic substrate, hippuryl-L-arginine, but can remove terminal arginine from bradykinin.

Bradykinin↗
PubMed1994

M protein and protein F act as important determinants of cell-specific tropism of Streptococcus pyogenes in skin tissue.

The pathogenic gram-positive bacterium Streptococcus pyogenes (group A streptococcus) causes numerous diseases of cutaneous tissue, each of which is initiated after the interaction of the bacterium with the cells of the epidermis. In this study, we show that different surface proteins of S. pyogenes play important roles in determining the cell-specific tropism of the bacterium in skin. Using streptococcal strains with defined mutations in the genes which encode surface proteins in combination with primary cultures of human skin and an in situ adherence assay which uses histological sections of human skin, we show that the M protein of S. pyogenes mediates the binding of the bacterium to keratinocytes, while a second streptococcal surface protein, protein F, directs the adherence of the organism to Langerhans' cells. Characterization of binding revealed that adherence was inhibited by purified streptococcal proteins and pretreatment of both host cells with the protease trypsin. Adherence was only slightly affected by the state of keratinocyte differentiation in vitro, but was considerably modulated in response to environmental conditions known to regulate expression of M protein and protein F, suggesting that the interaction between these bacterial cell-surface structures/adhesins and keratinocytes and Langerhans' cells may play an important role in streptococcal skin disease.

Antigens, Bacterial↗
PubMed1994

Tissue distribution of complement regulatory membrane proteins in rats.

Complement regulatory membrane proteins act either on C3/C5 convertase enzymes of the classical and alternative pathways or prevent the formation of membrane attack complexes (MAC). 5I2 is a monoclonal antibody (mAb) directed against a rat erythrocyte membrane inhibitor of the C3 convertase step which seems to be the rat counterpart of mouse Crry/p65. 6D1 is a mAb against rat CD59 which inhibits formation of MAC. Tissue distribution of these membrane inhibitors was visualized by immunohistochemical staining with the appropriate mAb. Rat CD59 (6D1 antigen) and 5I2 antigen were both widely distributed, being predominantly expressed on endothelial cells of the arteries, veins and capillaries as well as on all circulating cells. 6D1 antigen and 5I2 antigen were also detected on immature hepatocytes, systemic endothelial cells, skin fibroblasts, bronchial epithelial cells and bile canaliculi. Both were also expressed in the Schwann sheath of peripheral nerve fibres and ependymal cells. However, glial cells and myelin sheath in the central nervous system were not stained. Anti-CD59 (6D1) staining of epithelial and endothelial cells was observed in the cornea, while 5I2 stained only the epithelial cell layer.

Animals↗