Biomedical subjects

J Koyama

Publications and source records attributed to J Koyama.

At least 91 records · Page 5Linked to original sources

PubMed1992

Functional assessment of the stratum corneum under the influence of oral aromatic retinoid (etretinate) in guinea-pigs and humans. Comparison with topical retinoic acid treatment.

Clinically we have noted that the skin of patients treated with long-term oral etretinate becomes uniformly soft and smooth to touch, like facial skin that becomes smoother and less wrinkled following treatment with topical tretinoin. This suggests that retinoids, whether used systemically or topically, alter the physical properties of the skin, particularly of the stratum corneum (SC). To study the influence of retinoids on the SC, we serially assessed the functional properties of the SC non-invasively in retinoid-treated humans and experimental animals. SC hydration and barrier function were assessed by measurement of high-frequency conductance and transepidermal water loss (TEWL), respectively. Daily application of topical retinoic acid creams was found to rapidly induce a time- and dose-dependent, linear increase in SC hydration of the forearm skin of healthy adults over a 2-week period and to compromise its water barrier function in a similar fashion. Systemic administration of high-dosage etretinate, 4 or 8 mg/kg/day, to guinea-pigs also induced dose-dependent increases in both SC hydration and TEWL measured on the plantar skin after 1 month. Moreover, in the animals given etretinate 4 mg/kg/day we confirmed a slight but significant decrease in the number of cell layers of the plantar SC. Likewise, patients with various dermatoses began to show similar functional changes of the SC in the uninvolved skin of the flexor surface of the forearms 3 weeks after the start of oral etretinate treatment, consisting of 50 mg daily for 2 weeks, followed by gradual dose tapering.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗

PubMed1991

Amino acid sequences of nerve growth factors derived from cobra venoms.

Amino acid sequences of nerve growth factors (NGFs), purified from the venoms of Indian cobra (Naja naja) and Thailand cobra (Naja naja siamensis) were determined. The sequence of N. naja NGF differed from that reported previously by Hogue-Angeletti et al. [(1976) Biochemistry 15, 26-34]. The sequence of N. naja siamensis NGF was identical to that of Formosan cobra Naja naja atra NGF, determined previously by Oda et al. [(1989) Biochem. Int. 19, 909-917] and to that deduced from the nucleotide sequence of an NGF cDNA from the venom gland of N. naja siamensis, as reported by Selby et al. [(1987) J. Neurosci. Res., 18, 293-298].

Amino Acid Sequence↗

PubMed1991

Different behaviour of two distinct types of Fc gamma receptor on guinea-pig peritoneal macrophages during phagocytosis of soluble immune complexes: identification of an intracellular pool for one of the receptors.

Guinea-pig peritoneal macrophages express two distinct types of Fc receptor for IgG (Fc gamma R): one specific for IgG2 (Fc gamma 2R) and the other for both IgG1 and IgG2 (Fc gamma 1/gamma 2R). When we employed flow cytometry for an assay, we found that the amount of ovalbumin (OA) complex of homologous IgG2 antibody bound on the surface of macrophages rapidly decreased during the phagocytosis in the presence of an excessive amount of the complex. This reduced binding capacity of the cells was gradually restored by incubating the cells in the complex-free medium, which showed that the Fc gamma Rs are consumed during the phagocytosis and again expressed on the cell surface. Flow cytometry with monoclonal anti-Fc gamma 2R Fab' and anti-Fc gamma 1/gamma 2R Fab' revealed that only the Fc gamma R type bound to the immune complex was selectively internalized, whereas another Fc gamma R type unbound persisted on the cell surface during the reaction. In addition, the amount of Fc gamma 1/gamma 2R on the cell surface was found to increase to a greater extent than did that of Fc gamma 2R, when phagocytosis was terminated by the removal of the immune complex. This result suggests that Fc gamma 1/gamma 2R is recruited from some intracellular store. In fact, we were able to demonstrate the existence of the membrane-associated intracellular Fc gamma 1/gamma 2R pool that increases the binding capacity of anti-Fc gamma 1/gamma 2R F(ab')2 by treatment of macrophages with saponin, and by fractionation of homogenized macrophages by sucrose density gradient centrifugation. The different behaviour of these two Fc gamma R type, thus shown, may cause the relatively sustained phagocytosing activity mediated by Fc gamma 1/gamma 2R compared with that caused by Fc gamma 2R; the former continued at least up to 6 hr, while the latter ceased within 2 hr.

Animals↗

PubMed1990

Two distinct types of Fc receptor for IgG on guinea pig macrophages activate the NADPH oxidase through different signal-transduction pathways.

Neither 5 microM calmodulin antagonist W-7 nor depletion of the intracellular Ca2+ affected the O2- generation triggered by the Fc receptor for IgG2 (Fc gamma 2 R) on guinea pig macrophages, although that by the Fc receptor for both IgG1 and IgG2 (Fc gamma 1/gamma 2 R) was lowered to 50% of a control level by W-7 and the Ca2+ depletion, respectively. Staurosporine inhibited all these responses, but to different extents. These results reveal that the signal-transduction pathways linked to these receptors differ from each other, and that Fc gamma 1/gamma 2 R triggers the O2- generation through the Ca2(+)-calmodulin system and the Ca2(+)-independent system.

Animals↗

PubMed1990

The structure and expression of the guinea pig Fc receptor for IgG1 and IgG2 (Fc gamma 1/gamma 2R).

A cDNA clone encoding the receptor for guinea pig immunoglobulin G was isolated from a guinea pig peritoneal macrophage cDNA library. The cloned cDNA encoded 271 amino acids containing an N-terminal signal sequence. The deduced amino acid sequence is most homologous to murine Fc gamma RII beta 2. The receptor protein could be expressed in COS-7 and L cells transfected with the cDNA, suggesting that the expression of this receptor does not require the co-expression of a second chain such as gamma chain of Fc epsilon RI or CD3 zeta chain. The transformant L cells showed the binding to both the guinea pig IgG1 and IgG2 antibodies complexed with antigen, indicating that the cDNA we cloned was the one for guinea pig Fc gamma 1/gamma 2R.

Amino Acid Sequence↗

PubMed1990

Different abilities of two types of Fc gamma receptor on guinea-pig macrophages to trigger the intracellular Ca2+ mobilization and O2- generation.

When exposed to hen ovalbumin (OA)-complexed IgG antibodies, guinea-pig macrophages undergo O2- generation and a rapid rise in the intracellular concentration of free Ca2+ ((Ca2+]i). These responses were found to depend on the IgG isotype of antibodies used; OA-complexed IgG2 antibody (OA gamma 2) induced these responses 3-5 times more intensively than did OA-complexed IgG1 antibody (OA gamma 1). The inhibitory effects of monoclonal antibody to Fc gamma receptor for IgG2 alone (Fc gamma 2R) and that to Fc gamma receptor for both IgG1 and IgG2 (Fc gamma 1/gamma 2R) showed that Fc gamma 2R triggered both an increase in [Ca2+]i and activation of the respiratory burst NADPH oxidase more effectively than did Fc gamma 1/gamma 2R. As the number of Fc gamma 2R molecules per macrophage is about one-half that of Fc gamma 1/gamma 2R molecules, the ability of Fc gamma 2R to trigger these responses may be much higher than that of Fc gamma 1/gamma 2R. This difference between their abilities was further demonstrated by measuring the responses induced by cross-linking of Fc gamma 2R or Fc gamma 1/gamma 2R molecules. In addition, the O2- generation with OA gamma 1 was found to be enhanced with cytochalasin B, and to be lowered by depletion of the intracellular Ca2+ of macrophages with Ionomycin and EGTA, though cytochalasin B and the Ca2+ depletion did not affect the O2- generation with OA gamma 2. These results suggest that the mechanisms of Fc gamma 2- and Fc gamma 1/gamma 2 R-mediated signal transmission leading to activation of the NADPH oxidase also differ from each other.

Animals↗

PubMed1990

Characterization of the Fc receptor for IgG2 on guinea pig polymorphonuclear leukocytes by the use of a monoclonal antibody.

Guinea pig polymorphonuclear leukocytes (PMNs) possess two distinct types of Fc gamma receptor (Fc gamma R): Fc gamma 1/gamma 2R for both IgG1 and IgG2, and Fc gamma 2R for IgG2 alone. The Fc gamma 2R was previously shown to differ antigenically from homologous macrophage (M phi) Fc gamma 2R by the use of a monoclonal antibody to M phi Fc gamma 2R (VIIAI IgG1), though the Fc gamma 1/gamma 2R cross-reacts with a monoclonal antibody to homologous M phi Fc gamma 1/gamma 2R (VIA2 IgG1). Recently, we obtained a monoclonal antibody (MP-2) secreted by a hybridoma prepared by fusion of the splenic cells of mice immunized with guinea pig PMNs with a myeloma cell line. This antibody completely inhibited both the Fc gamma 2R-mediated rosette formation of PMNs with IgG2 antibody-sensitized sheep erythrocytes and the Fc gamma 2R-mediated binding of ovalbumin (OA)-complexed IgG2 antibody to PMNs. When the antigen of MP-2 was isolated by affinity chromatography with the antibody-Sepharose, it gave a single band with a molecular weight of 120,000 on SDS-PAGE. The number of antigen molecules per PMN was estimated to be 9 X 10(4) by measuring the binding of 125I-MP-2 Fab. This value was essentially the same as that obtained by measuring the binding of OA-complexed IgG2 antibody to the PMNs treated with the Fab' of VIA2 IgG1. These results strongly suggest that MP-2 is a monoclonal antibody to PMN Fc gamma 2R.

Animals↗

PubMed1990

Primary structure of human plasma glutathione peroxidase deduced from cDNA sequences.

Human plasma glutathione peroxidase (GSHPx) has been shown to be a selenium-containing enzyme immunologically distinct from cellular GSHPx. Oligonucleotide probes, based on the partial amino acid sequence of plasma GSHPx, were synthesized and used to screen a human placenta cDNA library. Nucleotide sequence analysis of the obtained clones revealed that GSHPx consisted of a 678-base pair open reading frame coding for a 226-amino acid polypeptide with a Mr of 25,389. About 50% of the deduced amino acid sequence was confirmed by partial amino acid sequencing of the peptides in a lysine endopeptidase-digest of the purified enzyme. The amino acid sequence exhibited only 44% homology with that of human cellular GSHPx. Northern blot analysis revealed a single transcript of 2.2 kilobases in the poly(A)+ RNA fractions of human placenta and HepG2 (a human hepatic cell line), but not that of human liver and endothelial cells.

Amino Acid Sequence↗

PubMed1990

Different effects of cinnamic acid on the O2- generation by guinea pig macrophages stimulated with a chemotactic peptide and immune complex.

Cinnamic acid inhibits the O2(-)-generating response of guinea pig peritoneal macrophages elicited with a chemotactic peptide, N-formyl-methionyl-leucyl-phenylalanine (fMLP), but not those with ovalbumin complex of immunoglobulin G2 antibody and phorbol-myristate acetate. During the course of study on the inhibitory mechanism of cinnamic acid, we found that the acid also inhibited the Ca2+ mobilization elicited with fMLP, but not that with the immune complex. In addition, the treatment of macrophages with Ionomycin and ethyleneglycol bis-(beta-aminoethylether)-N,N'-tetraacetic acid for depletion of the intracellular Ca2+ inactivated completely the O2- generation elicited with fMLP, but not its counterpart of the immune complex. Thus, the inhibitory activity of cinnamic acid on the O2- generation elicited with fMLP seems partly due to that on the Ca2+ mobilization. On the other hand, cinnamic acid augmented the intracellular accumulation of adenosine 3',5'-cyclic monophosphate (cyclic AMP) in the presence of 3-isobutyl 1-methylxanthine (IBMX), and elevated more intensively the concentration of cyclic AMP when macrophages were stimulated with fMLP. Since IBMX inhibited the O2- generation elicited with fMLP, the enhancement of activation of an adenylate cyclase by cinnamic acid might cause depression of the O2- generation. This possibility, however, seems to be excluded by the fact that the same effect of cinnamic acid was observed even when macrophages were stimulated with the immune complex.

Animals↗

PubMed1989

Phosphorylation of NADPH-cytochrome c reductase in guinea pig peritoneal macrophages stimulated with phorbol myristate acetate.

The plasma membrane-bound NADPH-cytochrome c reductase of guinea pig macrophages (M phi) was found to be phosphorylated when [32P]phosphate-labeled cells were stimulated with 12-phorbol 13-myristate acetate (PMA). The time course of phosphorylation was parallel to that of O2- -generating activity elicited. These results suggest that the reductase participates as a flavoprotein in activation of the respiratory burst NADPH oxidase, when phosphorylated.

Adenosine Triphosphate↗

PubMed1989

Relative abilities of two Fc gamma receptors on guinea-pig macrophages to operate in the phagocytosis of soluble immune complexes.

Guinea-pig peritoneal macrophages possess two distinct types of Fc gamma receptor (Fc gamma R); one is specific for IgG2 alone (Fc gamma 2R) and the other is specific for both IgG1 and IgG2 (Fc gamma 1/gamma 2R). To study the relative abilities of these Fc gamma Rs to operate in the phagocytosis of soluble immune complexes, the binding, intracellular uptake and subsequent digestion of homologous IgG1 and IgG2 antibodies, complexed with ovalbumin (OA-IgG1 and OA-IgG2), were measured by incubating these complexes with the macrophages, which had been pretreated with the Fab' of monoclonal anti-Fc gamma 2R or anti-Fc gamma 1/gamma 2R antibody. The amount of OA-IgG1 or OA-IgG2 bound to Fc gamma 1/gamma 2R was found to be larger than that of OA-IgG2 to Fc gamma 2R, reflecting that the number of Fc gamma 1/gamma 2R molecules per macrophage is about two times larger than that of Fc gamma 2R molecules. The rates of intracellular uptake and subsequent digestion of Fc gamma 1/gamma 2R bound OA-IgG1 or Fc gamma 1/gamma 2R bound OA-IgG2 were virtually equal to those of Fc gamma 2R bound OA-IgG2, respectively. However, when an excessive amount of OA-IgG2 was incubated with anti-Fc gamma 1/gamma 2R Fab' or anti-Fc gamma 2R Fab' treated macrophages, the phagocytosis mediated by Fc gamma 2R ceased within 4 hr, whereas that mediated by Fc gamma 1/gamma 2R continued up to 6 hr. Thus, the Fc gamma 1/gamma 2R activity seems to be more rapidly restored than the Fc gamma 2R activity in the phagocytosing process.

Animals↗

PubMed1989

A Chinese traditional medicine, juzentaihoto, inhibits the O2- generation by macrophages.

Guinea pig peritoneal macrophages generate superoxide anion (O2-), when stimulated with N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP), phorbol-myristate acetate (PMA) or ovalbumin complex of guinea pig IgG2 antibody (OA gamma 2). These responses were found to be inhibited by a Chinese traditional medicine, Juzentaihoto (JT). When the inhibition was assayed by the use of fMLP as a stimulant, at least one of the substances responsible for the inhibitory activity of JT was identified to be cinnamic acid. An authentic sample of cinnamic acid also inhibited the O2- generation by fMLP-stimulated macrophages. Cinnamic acid, however, did not inhibit the O2- generation, when macrophages were stimulated with PMA and OA gamma 2. These results indicate that a certain cinnamic acid-inhibitable factor may be involved in the intracellular triggering event(s) initiated by fMLP, leading to activation of the respiratory burst reduced nicotinamide adenine dinucleotide phosphate oxidase, but not in those by PMA and OA gamma 2.

Animals↗

PubMed1989

In vivo effects of vitamin E on peritoneal macrophages and T-kininogen level in rats.

In order to clarify the modulating effect on macrophages by vitamin E, we investigated the in vivo effects of vitamin E on the peritoneal macrophages and T-kininogen level in rats. Peritoneal injections of vitamin E for 6 successive days resulted in a significant increase of leucocytes, mostly consisting of macrophages, in the peritoneal cavity. Namely, in the case of 5 mg vitamin E per rat (400 g body weight), the number of leucocytes in the peritoneal cavity and T-kininogen level in plasma showed 171.57 +/- 15.96 X 10(6) per rat and 1372 +/- 364 micrograms/ml, whereas the placebo vehicle was 28.54 +/- 8.24 X 10(6) and 315 +/- 130, respectively. Macrophages, in which alpha-tocopherol contained approximately 158.2 ng/10(6) cells after exogenous vitamin E treatment, showed less acid phosphatase activity and less O2- generation than that treated with placebo vehicle. In contrast, the acid phosphatase activity of cellfree peritoneal exudate fluid with vitamin E increased approximately two to three-fold as compared to the placebo vehicle. From these results, we discussed the relationship between in vivo effects of vitamin E on peritoneal macrophages and T-kininogen induction.

Acid Phosphatase↗

PubMed1988

Inhibition of anti-IgM and growth factor-induced proliferation of guinea pig B cells by one of two distinct Fc gamma receptors on the cells.

Guinea pig B cells were found to proliferate when co-stimulated with F(ab')2 of rabbit anti-guinea pig IgM and human 12-kDa B cell growth factor (BCGF), though the proliferation did not occur with the replacement of the F(ab')2 by its parent IgG antibody. In addition, the intact antibody inhibited the proliferation induced by F(ab')2 of anti-IgM and BCGF. Because both two distinct types of FcR for IgG on the B cells, one specific for IgG2 (Fc gamma 2R) and the other for both IgG2 and IgG1 (Fc gamma 1/gamma 2R), can bind rabbit IgG, we determined whether they participate in the inhibition of the B cell proliferation by intact anti-guinea pig IgM antibody. Blocking Fc gamma 1/gamma 2R by F(ab')2 of anti-Fc gamma 1/gamma 2R mAb significantly reversed the inhibitory effect of intact anti-IgM antibody. F(ab')2 of anti-Fc gamma 2R mAb, however, was not effective. Furthermore, guinea pig IgG1 and IgG2 anti-rabbit IgG antibodies suppressed similarly the B cell proliferation induced by F(ab')2 of rabbit anti-IgM and BCGF. These results show that between these two types of Fc gamma R on B cells, Fc gamma 1/gamma 2R alone is involved in the regulation of anti-IgM and BCGF-induced B cell proliferation, and inhibits the response when cross-linked to the surface IgM.

Animals↗

PubMed1988

Different sensitivities of the responses of human neutrophils stimulated with immune complex and C5a anaphylatoxin to pertussis toxin.

When stimulated with immune complex or C5a anaphylatoxin, human neutrophils undergo an increase in the concentration of intracellular Ca2+ [( Ca2+]i) that precedes the onset of superoxide (O2-) production. The extracellular Ca2+ is required for the O2- production of neutrophils stimulated by C5a, but is only partially required for those by immune complex. The addition of pertussis toxin to neutrophils does not inhibit the rise in [Ca2+]i and O2- production induced by immune complex but does inhibit those induced by C5a. These results suggest that a different sequence of reaction is involved by different stimulants, the anaphylatoxin and immune complex.

Antigen-Antibody Complex↗

PubMed1988

Two distinct Fc gamma Rs on guinea-pig polymorphonuclear leukocytes differ from each other in their eliciting activities for O2- generation.

When guinea-pig polymorphonuclear leukocytes (PMNs) are stimulated with hen ovalbumin (OA)-complexed IgG antibodies, they generate superoxide anion (O2-). This reaction was found to depend on the IgG isotype used for preparation of the immune complexes; OA-complexed IgG2 antibody (OA-IgG2) induced 3-4 times more intensively O2- generation than OA-complexed IgG1 antibody (OA-IgG1). The O2- generation with OA-IgG1 was almost completely inhibited by a monoclonal antibody to the Fc gamma R binding both IgG1 and IgG2 (Fc gamma 1/gamma 2 R), whereas that with OA-IgG2 was only slightly inhibited. Since guinea-pig PMNs are capable of binding OA-IgG2 not only through Fc gamma 1/gamma 2 R but also through another Fc gamma R which is specific for IgG2 alone (Fc gamma 2 R), the O2- generation with OA-IgG2 may be mainly mediated by Fc gamma 2 R. In addition, cytochalasin B was found to enhance markedly the O2- generation with OA-IgG1, though that with OA-IgG2 was only slightly affected. The results so far obtained indicate that Fc gamma 1/gamma 2 R and Fc gamma 2 R differ from each other in their activities for triggering O2- generation, namely activation of the respiratory burst NADPH oxidase. Furthermore, differing from the activation of the NADPH oxidase mediated by Fc gamma 2 R, that by Fc gamma 1/gamma 2 R was shown to be suppressed by some cytochalasin B-inhibitable factor or process though its biochemical nature is unknown.

Animals↗

PubMed1988

The different roles of two distinct Fc gamma receptors on guinea pig macrophages in the phagocytosis of sensitized sheep erythrocytes.

The functional roles of two distinct types of Fc gamma receptors (Fc gamma 1/gamma 2R specific for both IgG1 and IgG2, and Fc gamma 2R specific for IgG2 alone) on the surface of guinea pig macrophages in the phagocytosis of sensitized sheep erythrocytes (EA) were investigated by the use of two Fab's of monoclonal anti-Fc gamma 1/gamma 2R and anti-Fc gamma 2R antibodies. The binding and subsequent ingestion of IgG1 antibody-sensitized erythrocytes (EA gamma 1) by macrophages were completely inhibited by anti-Fc gamma 1/gamma 2R Fab', indicating that the reactions are mediated only by Fc gamma 1/gamma 2R. On the other hand, the binding and subsequent ingestion of IgG2 antibody-sensitized erythrocytes (EA gamma 2) were substantially inhibited by anti-Fc gamma 2R Fab', but not by anti-Fc gamma 1/gamma 2R Fab'. The inhibitory activities of anti-Fc gamma 2R Fab' were dependent upon the amount of IgG2 antibody bound on erythrocytes; increasing the amount of bound IgG2 antibody from 0.15 to 0.91 micrograms/2 X 10(8) erythrocytes resulted in a decrease in the inhibition of binding of EA gamma 2 by anti-Fc gamma 2R Fab' from 50 to 0%, and also a decrease in the inhibition of ingestion of EA gamma 2 from 100 to 50%.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1988

Characterization of a monoclonal antibody to guinea pig T cells that inhibits rosette formation of the cells with rabbit erythrocytes: similarity of the antigen to E-receptor on human T cells.

A monoclonal antibody, GPT-1, was prepared by fusion of the splenic cells of mice immunized with guinea pig thymocytes with a mouse myeloma cell line. GPT-1 completely inhibited spontaneous rosette formation of T cells with papain-treated rabbit erythrocytes. GPT-1 reacted with 90% of thymocytes, 70% of peripheral blood lymphocytes, and 45% of splenic lymphocytes, but not with B cells. These results indicate that GPT-1 has pan-T reactivity. The antibody specifically bound to a single polypeptide chain with a molecular size of 50-65 kD. The surface density of the antigen was higher on thymocytes than on peripheral T cells, suggesting that the antigen is a certain differentiation antigen on T cells. Phytohemagglutinin-activated T cells expressed more antigen molecules than resting T cells. In addition, GPT-1 suppressed the proliferation of T cells induced by the mitogen, indicating that GPT-1 recognizes a T cell-specific surface antigen which is associated with T cell activation. Based on these results, it was concluded that GPT-1 reacts with a guinea pig T cell surface antigen which is similar to the E-receptor protein on human T cells (CD2 molecule).

Animals↗