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Biomedical subjects

S Fujii

Publications and source records attributed to S Fujii.

At least 775 records · Page 43Linked to original sources
PubMed1985

Effect of FUT-175, a new synthetic protease inhibitor, on the development of lupus nephritis in (NZB x NZW) F1 mice.

FUT-175 (6-amidino-2-naphthyl p-guanidinobenzoate dimethanesulphonate), a new synthetic protease inhibitor, was administrated to (NZB x NZB) F1 mice in order to examine its influence on the development of autoimmune diseases. A dose (400 mg/kg of body weight) of FUT-175 has both prophylactic and curative effects on the development of lupus nephritis: mice showed a significantly low percentage of proteinuria, a marked decrease in BUN levels, and the lowest degree of glomerular damages. Dexamethasone had almost the same effect as FUT-175 (400 mg/kg), but it was slightly less effective than FUT-175. These results suggest that the administration of FUT-175 may become a viable strategy for the treatment of human autoimmune diseases.

Animals↗
PubMed1984

Detection of intermediary Clr with complete active site, using a synthetic proteinase inhibitor.

The synthetic proteinase inhibitor, FUT-175 (6-amidino-2-naphthyl-4-guanidinobenzoate), strongly suppressed activation of Clr at 37 degrees C, causing 50% inhibition at 0.03 mM. To clarify whether the inhibitor was incorporated into the active site of intermediary Clr formed during the incubation, determination of the active site was tried using this inhibitor. Consequently, release of amidinonaphthol equimolar with the amount of Clr used was observed in the early period of incubation, in which the activation to Clr- was about 5%. These results indicate that intermediary Clr already has a complete active site.

Benzamidines↗
PubMed1984

18,19-Dihydroxydeoxycorticosterone, a new metabolite produced from 18-hydroxydeoxycorticosterone by cytochrome P-450(11) beta. Chemical synthesis and structural analysis by 1H NMR.

A new metabolite was produced from 18-hydroxydeoxycorticosterone by the cytochrome P-450(11) beta linked hydroxylase system purified from bovine adrenocortical mitochondria. It was identified as 18,19-dihydroxydeoxycorticosterone by chemical synthesis on the basis of high-performance liquid chromatography, gas chromatography-mass spectrometry, and proton nuclear magnetic resonance (1H NMR) spectroscopy, and detailed structural analysis of it was performed by 1H NMR spectroscopy. The methylene protons at the C-19 position of the steroid were nonequivalent and coupled with each other, having a coupling constant of 10.6 Hz. These protons had different coupling constants, 6.7 and 3.4 Hz, for the hydroxy proton at the C-19 position. Due to these couplings, the signals of the methylene protons were observed around 3.9 ppm as two double doublets. The methylene protons at the C-21 position were also nonequivalent, having a coupling constant of 11.1 Hz. Coupling constants between these methylene protons and the hydroxy proton at the C-21 position were 8.2 and 4.2 Hz, respectively. These results indicate that both hydroxymethyl groups at the C-19 and C-21 positions do not freely rotate in chloroform solution. The signals of hydroxy protons at the C-19 and C-21 positions were found at 1.25 and 1.87 ppm, respectively, by means of decoupling of the corresponding methylene protons. The hydroxy proton at the C-18 position was found to scarcely couple with any proton. This fact suggests that this hydroxy group is linked to the C-20 position, making a hemiketal bridge between the C-18 and the C-20.

18-Hydroxydesoxycorticosterone↗
PubMed1984

Production of monoclonal antibodies to islet cell surface antigens using hybridization of spleen lymphocytes from non-obese diabetic mice.

Non-obese diabetic mice display a syndrome with dramatic clinical and pathological features similar to those of Type 1 (insulin-dependent) diabetes in man. Circulating autoantibodies to the surface of islet cells were demonstrated in some of these mice by a protein A radioligand assay. To produce monoclonal antibodies to islet cell surface antigens, therefore, we took the spleens of non-obese diabetic mice, transferred the spleen cells into non-immunized recipient mice, which were made immunologically incompetent by a large dose of X-irradiation, and then fused their lymphocytes with FO mouse myeloma cells. After screening the resultant hybrids, one stable hybridoma (3A4) that produced a monoclonal antibody (IgG1) specifically bound to the surface of islet cells was obtained. The purified monoclonal antibody was bound to the surface of transplantable Syrian golden hamster insulinoma cells sevenfold more than control antibody. Adsorption of the antibody on mouse spleen lymphocytes or thymocytes resulted in only a slight decrease in 125I-protein A binding to insulinoma cells. This antibody also reacted with the surface of mouse and rat islet cells, but not with that of rat spleen cells or hepatocytes. A spectrophotometric assay for peroxidase activity demonstrated that six times more peroxidase bound to insulinoma cells incubated with the antibody than to cells treated with control antibody. Furthermore, this antibody could be visually detected in the immunoenzymatic labelling of the surface of insulinoma cells. In summary, we have developed a novel method of producing monoclonal antibodies to the surface of islet cells for probing into the pathogenesis of Type 1 diabetes.

Animals↗
PubMed1984

Cyclic AMP-dependent phosphorylation of erythrocyte variant pyruvate kinase.

Cyclic AMP-dependent phosphorylation of a variant erythrocyte pyruvate kinase (PK; EC 2.7.1.40) was studied. This variant PK shows a faster electrophoretic mobility than the normal enzyme. The decreased enzyme activity observed in this variant is associated with a quantitative decrease of enzyme protein. Other parameters are within normal ranges. The partially purified variant PK is phosphorylated with a subsequent increase of k0.5s (phosphoenolpyruvate) similar to the normal control, suggesting that the structural abnormality of the variant enzyme has no influence on the phosphorylation-deactivation mechanism. On the other hand, the variant PK in the erythrocyte was less extensively phosphorylated than PK in normal erythrocytes. This may be the result of abnormal metabolism in the patient's red cells, including increased 2,3-diphosphoglycerate and decreased adenosine triphosphate levels.

Adolescent↗
PubMed1984

Maturational impairment of thymic lymphocytes in streptozotocin-induced diabetes in rats.

Streptozotocin (STZ)-induced diabetes in rats was associated with marked decreases in thymus weight and the number of thymic lymphocytes. Histologically, the cortical lymphocytes which were present near the cortico-medullary junction in the thymus seemed to be reduced selectively in the STZ-induced diabetes. Rosette-forming cells, which bind to guinea pig erythrocytes in the presence of fetal calf serum, were also significantly decreased. Insulin treatment allayed these intrathymic changes. Preincubation of thymic lymphocytes from diabetic rats with thymosin fraction 5 significantly enhanced the percentage of rosette-forming cells to near the control level. These results suggest that a maturational impairment of thymus cortical lymphocytes may be caused in STZ-induced diabetes with hypoinsulinemia and it may be intimately related to reductions in thymus weight and the number of thymic lymphocytes.

Animals↗
PubMed1984

Delayed afterdepolarisations and triggered activity in canine Purkinje fibres treated with neuraminidase.

We investigated the electrophysiological alterations induced by the removal of sialic acid from the sarcolemma in canine Purkinje fibres. About 70% of total sialic acid content of Purkinje fibres was removed by 120 min of exposure to neuraminidase (1 U X ml-1). The treatment with neuraminidase did not change any of the action potential characteristics at normal Ca2+ concentration (2.7 mmol X litre-1). However, action potential duration and maximum upstroke velocity of phase zero of the action potential were reduced to a greater degree in neuraminidase-treated Purkinje fibres than in non-treated controls at high Ca2+ concentration (8.1 mmol X litre-1). At high Ca2+ concentration, delayed afterdepolarisations were induced in five out of nine neuraminidase-treated Purkinje fibres and triggered activity was observed in two, when driven in trains of 20 stimuli of different cycle length (1000 to 180 ms). No discernible delayed afterdepolarisations were observed in nine non-treated control Purkinje fibres. In addition, the amplitude of delayed afterdepolarisations induced by ouabain (0.2 mumol X litre-1) in neuraminidase-treated Purkinje fibres was larger than non-treated controls. These findings suggest that sialic acid residues of glycocalyx function as a kind of barrier to Ca2+ influx.

Action Potentials↗
PubMed1984

New synthetic inhibitors of chymotrypsin.

4-Substituted carbonylphenyl ester derivatives were prepared and their inhibitory effects on chymotrypsin, trypsin, thrombin, plasmin, pancreatic kallikrein, and plasma kallikrein were examined. Among the various inhibitors tested, 4-[2-(dimethylamino)ethylaminocarbonyl]phenyl 1,2,3,4-tetrahydro-1-naphthoate hydrochloride (FK-316), 4-[(2-[4-pyrrolidinocarbonylmethyl)oxycarbonyl]-phenyl 5-methoxyindole-3-acetate dihydrochloride (FK-375), 4-[(2-[4-(piperidinocarbonylmethylpiperadino]ethyl)oxycarbonyl+ ++]phenyl 1-naphthylacetate dihydrochloride (FK-386), 4-[(2-[4-(2-[morpholino]ethyl)piperadino]ethyl)oxycarbonyl]p henyl 5-methoxy-2-methylindole-3-acetate trihydrochloride (FK-401) and 4-(4-isopropylpiperadinocarbonyl)phenyl 1,2,3,4-tetrahydro-1-naphthoate methanesulfonate (FK-448) were the most effective and specific inhibitors of chymotrypsin.

Animals↗
PubMed1984

A 13C-NMR study on the interaction of riboflavin with egg white riboflavin binding protein.

The interaction between riboflavin and riboflavin binding protein (RBP) was studied by 13C-NMR spectroscopy. The 13C-NMR spectra of riboflavin selectively enriched at the 2-, 4-, 4a-, and 10a-positions and of (3-[13C]methyl)riboflavin were measured both in the free and RBP-bound forms. The 13C signals of 13C-enriched riboflavin or 3-methylriboflavin bound to RBP are broader than those of the free form, reflecting the restriction of flavin mobility. The 2-, 4-, and 10a-13C signals of riboflavin show no pH-dependent shift in the neutral to acidic pH region either in the bound or free form but the 4a-13C signal of bound riboflavin shifts to lower field in the acidic pH region while that of the free form remains unshifted. The 2-, 4-, 4a-, and 10a-13C signals of free riboflavin exhibited pH-dependent change in the alkaline pH region with a pK value of about 10, in association with the N(3)-H deprotonation. The pH titration profile of the 2-, 4-, and 4a-13C signals of bound riboflavin indicates that the pK of N(3)-H is shifted substantially to the alkaline side when riboflavin is bound to RBP. The 3-methyl-13C signal of 3-methylriboflavin shows no pH-dependent shift whether the compound is free or bound to RBP. The binding of riboflavin and 3-methylriboflavin was also studied spectrofluorometrically. The analysis of the pH dependence of the association constant revealed that one ionizable group in RBP with pK of about 5 and N(3)-H of riboflavin play important roles in the binding. We conclude that RBP preferentially binds the neutral, i.e., N(3)-protonated, form of riboflavin and that the neutral form in turn is stabilized by the hydrophobic environment of RBP surrounding the N(3) region of the bound riboflavin molecule.

Carbon Isotopes↗
PubMed1984

Purification and characterization of a bovine colostrum low molecular weight cysteine proteinase inhibitor.

Large amounts of cysteine proteinase inhibitors were found in bovine colostrum. One had a molecular weight of 90,000, and the other a molecular weight of 10,500. The concentrations of both these inhibitors were highest the day after parturition, and were about one-tenth as much on day 7. The lower molecular weight inhibitor was purified by acid treatment, ammonium sulfate fractionation, gel filtration on Sephadex G-50, CM-Sephadex chromatography and rechromatography on Sephadex G-50. The purified preparation gave a single band on SDS-polyacrylamide gel electrophoresis. This inhibitor contained one tryptophanyl residue and one cystinyl residue, and did not contain a free thiol group. Values obtained for its isoelectric point (pI) were 10.0 and 10.3. This material strongly inhibited cathepsin B, cathepsin H, and papain. the higher molecular weight inhibitor was partially purified. It had a pI of 4.2 and inhibited papain, cathepsin H, and cathepsin B.

Amino Acids↗
PubMed1984

Circus-movement tachycardia in frog atrium monitored by voltage-sensitive dyes.

Circus-movement tachycardia was studied using voltage-sensitive merocyanine-rhodanine dyes (dye XVII and NK2761). Excitatory waves were optically measured simultaneously from eight different regions of a ring of tissue formed from frog atrium. Application of acetylcholine in Ca2+-free solution (10(-10)-10(-9) g/ml) shortened the duration of optical action signals to cause nonuniform change in optical signal durations in about 60% of the preparations. Circus-movement tachycardia was produced by proper reduction and regional nonuniformity of optical signal durations. Under these circumstances it is easy to evoke circus-movement tachycardia by giving an extra stimulus to the site that shows a difference in optical signal durations.

Acetylcholine↗