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Biomedical subjects

Y Shibata

Publications and source records attributed to Y Shibata.

At least 685 records · Page 38Linked to original sources
PubMed1983

Possible association of NADPH-cytochrome P-450 reductase and cytochrome P-450 in reconstituted phospholipid vesicles.

A fluorescent probe, N-(1-anilinonaphth-4-yl)-maleimide (ANM), was specifically labeled to SH group(s) in the hydrophilic moiety of NADPH-cytochrome P-450 reductase at a ratio of 1 +/- 0.1 ANM/mol of protein. The ANM-labeled reductase and P-450 were reconstituted in phosphatidylcholine-phosphatidylethanolamine-phosphatidylserine vesicles in which all of the enzymes were functionally active. The reconstitution of the mixed-function oxidase system was found to be strongly dependent on both the lipid to protein molar ratio and phospholipid composition. The interactions of ANM-labeled reductase with P-450 in proteoliposomes were investigated by perturbation of the fluorescence of ANM. Upon incorporation of P-450 into the phospholipids vesicles (ANM-reductase/P-450/lipids identical to 1:1.4:800), a significant decrease of total fluorescence intensity and slight increase of emission anisotropy of ANM were observed. In the average fluorescence lifetime of ANM bound with reductase, an appreciable change was shown between the absence and presence of P-450 in the vesicles. These data provide clear evidence that significant molecular interactions occur between the two proteins in a membranous reconstituted system.

Animals↗
PubMed1983

The stimulation of macrophage prostaglandin E2 and thromboxane B2 secretion by Streptococcus mutans insoluble glucans.

The effect of insoluble glucan synthesized by Streptococcus mutans on [3H]arachidonate metabolites secretion from peritoneal macrophages was studied. Insoluble glucans stimulated [3H]arachidonate release and secretion of prostaglandin E2 and thromboxane B2 from macrophages. In contrast, commercial soluble glucan (dextran) did not induce [3H]arachidonate release.

Animals↗
PubMed1983

Purification, characterization and identification of rat liver mitochondrial kynurenine aminotransferase with alpha-aminoadipate aminotransferase.

Kynurenine aminotransferase (L-kynurenine:2-oxoglutarate aminotransferase (cyclizing), EC 2.6.1.7) was purified 378-fold from rat liver mitochondria by digitonin solubilization, heat treatment, DEAE-Sepharose CL-6B chromatography, Sephadex G-100 gel filtration, hydroxyapatite chromatography and chromatofocusing. Elution patterns of alpha-aminoadipate aminotransferase (EC 2.6.1.39) activity were identical with those of kynurenine aminotransferase activity on all column chromatographies. The ratios of the two specific activities were constant throughout the purification. On polyacrylamide gel electrophoresis both activities were detected at the same position. Both enzymatic activities showed the same inactivation curves upon heat inactivation at various temperatures. alpha-Aminoadipate showed competitive inhibiton against kynurenine or 3-hydroxykynurenine. alpha-Ketoadipate was utilized in the kynurenine aminotransferase reaction as an amino acceptor in place of alpha-ketoglutarate. The Km value for alpha-ketoadipate was 10 microM, lower than for alpha-ketoglutarate. These observations indicate that kynurenine aminotransferase is identical with alpha-aminoadipate aminotransferase. The Km values of purified kynurenine aminotransferase were determined at pH 6.5 as: kynurenine, 4.3 mM; pyridoxal 5'-phosphate, 4.2 microM; alpha-ketoglutarate, 20 microM (kynurenine substrate), and 3-hydroxykynurenine, 5.7 mM; pyridoxal 5'-phosphate, 1.7 microM; alpha-ketoglutarate, 13 microM (3-hydroxy-kynurenine substrate). The enzyme was strongly inhibited by Hg2+ and p-chloromercuribenzoate.

2-Aminoadipate Transaminase↗
PubMed1983

Regular structures on the microvillar surface membrane of ileal epithelial cells in suckling rat intestine.

Freeze-fracture deep-etch studies were done to examine regular patterns of surface membrane particles in the suckling rat ileal epithelium by using quick-freezing method. In addition to the presence on the luminal surfaces of well-developed endocytic complexes, latticed particles were consistently observed on almost the entire apical membrane between microvilli and frequently on the microvilli. These particles seemed to be partly integrated in the outer half layer of membranes. After rinsing with phosphate-buffered saline, patterns on the microvilli appeared to be parallel circle lines rather than latticed particles found in fresh preparations. Filipin treatment showed the presence of filipin-sterol complexes on most of the particle-covered membrane areas except small tubules and vesicles. Possibilities were suggested that these latticed particles were transferred to the apical surface along the outer half layer of membranes, and released or secreted into the intestinal lumen.

Animals↗
PubMed1983

Studies on the retention of passively transferred antibodies in man. II. Antibody activity in the blood after intravenous or intramuscular administration of anti-HBs human immunoglobulin.

Catabolism of intravenously or intramuscularly administered human immunoglobulin in man was studied by the administration of HBs antibodies at a high titer and analysis with a highly sensitive radioimmunoassay technique. The half-life in the blood of the antibodies in the aggregate-reduced antibody preparation administered intravenously was found to be 17.7 days and of those in the antibody preparation administered intramuscularly to be 23.8 days.

Adult↗
PubMed1983

In vivo analysis of the suppressive effects of immunosuppressive acidic protein, a type of alpha 1-acid glycoprotein, in connection with its high level in tumor-bearing mice.

Suppressed concanavalin A response of spleen cells which appeared on Day 21 in C3H/He mice bearing methylcholanthrene-induced fibrosarcoma was attributed to macrophages. These macrophages were not only immunoglobulin and Thy 1.2 negative and mitomycin C resistant but were also found in the light-specific-gravity (1.077) fraction and were completely removed by carbonyl iron treatment. These suppressor macrophages, however, disappeared 4 days after surgical resection of the tumor, suggesting that the control mechanism originally resides in tumor tissues. Immunosuppressive acidic protein (IAP) levels in the sera of these tumor-bearing mice increased along with the appearance of these suppressor macrophages. Inasmuch as the suppressor macrophages obtained from the spleens of tumor bearers and cultured in vitro produced 4 times more IAP (88 ng/ml) than did resident macrophages, the elevated levels of IAP in the sera of tumor-bearing mice at the late stage might be explained partly by the appearance of suppressor macrophages. On the other hand, an i.v. administration of IAP (5 mg/mouse) into normal mice not only induced the same unresponsiveness of spleen cells to concanavalin A shown by tumor-bearing mice but also induced suppressor macrophages in the spleens of these mice. This fact may indicate that IAP elevation, even though artificial, triggers the induction of suppressor macrophages in the spleen or at least points to a keen correlation between the appearance of suppressor macrophages and increased IAP level in the serum.

Animals↗
PubMed1983

[10 cases of congenital cystic dilatation of the common bile duct].

Ten cases of congenital cystic dilatation of the common bile duct (including insufficiency form) were examined for mode of pancreatico-biliary anastomosis and cholangiographic findings. The results were as follows. Male to female ratio was 1:9 in this series. Regarding the mode of pancreatico-biliary anastomosis, type I (pancreatic duct flowing into common bile duct) tended to occur frequently in patients 30 years old or more, while type II (common bile duct flowing into pancreatic duct) in patients under 30 years old. With respect to clinical symptoms, no cases had triad (jaundice, abdominal pain and palpation of mass), but abdominal pain occurred in all the cases. Jaundice and palpation of mass were seen in 30% and 10% of the cases, respectively. Regarding the age at the onset and the duration of the disease, type I occurred in elderly cases with a longer duration of disease, while type II occurred in young cases with a shorter duration of disease. The degree of distention increased in proportion to the severity of the peripheral stenosis of the biliary duct. Complication with biliary tract carcinoma was seen in 2 type I cases. Among the type I cases, those with mild distention were considered to be insufficient form.

Adult↗
PubMed1983

[Determination of urinary immunosuppressive acidic protein in cancer patients].

The urine levels of immunosuppressive acidic protein (IAP) were measured in patients with and without cancer, using passive hemagglutination inhibition test and 24-h urine samples. In 23 control healthy adults, the urine levels of IAP were 0.13-1.3 mg/day. If an elevation of IAP levels were found in 46 (48%) of 96 cancer patients. Elevated urine IAP levels were found in 6 (18%) of 34 patients with non-cancerous gastrointestinal tract diseases. Increased urine IAP was demonstrated in 11 (58%) of 19 non-cancer patients with rheumatoid arthritis.

Adolescent↗
PubMed1982

Studies on FAD- and FMN-binding domains in NADPH-cytochrome P-450 reductase from rabbit liver microsomes.

Six sulfhydryl group were determined after complete denaturation of NADPH-cytochrome P-450 reductase; of these, about 5.2 in both the native holoenzyme and FMN-depleted enzyme are accessible to p-hydroxychloromercuribenzoate (pCMB), which may be differentiated as follows: four --SH groups are modified by low concentration of the reagent but are not essentially involved in the catalytic function; additional block of one --SH group at high concentrations of pCMB completely inhibited the reductase activity. The fluorescence quenching of the FAD in the FMN-depleted enzyme was removed after the fifth --SH group was reacted slowly with pCMB. Kinetic and fluorometric analysis indicated that this finally modified --SH group was assumed to be essential for the activity and significantly protected by either 1 mM NADP+ or 2'-AMP against attack by mercurial compounds. A strong negative ellipticity at around 450 nm is clearly decreased upon binding of pCMB to an essential --SH group, while the CD spectra in the near and far UV region show only minor differences during the modification of --SH groups. Removal of the FMN prosthetic group from the native holoprotein results in 1.25-fold greater tryptophan fluorescence with a slight red shift of the emission maximum from 332 to 336 nm, and FMN reconstitution reduces the protein fluorescence quantum yield to approximately that of the holoprotein. Oxidation of tryptophan indol rings of the FMN-depleted enzyme is associated with a loss of FMN binding ability to the protein which causes the inactivation of cytochrome c reductase activity, but ferricyanide reductase activity is not strongly affected by tryptophan modification.

Animals↗
PubMed1982

Inhibitory effect of prostaglandin A2 on Na+-K+-ATPase activity in synaptic plasma membrane of rat brain in vitro.

1. The Na+-K+-ATPase activity in the synaptic plasma membrane of rat brain was inhibited by PGA2 in vitro. 2. PGA2 concentration required for 50% inhibition was 8.91 x 10(-5) M. 3. Inhibition mode of PGA2 for both ATP and Mg2+ was uncompetitive type. 4. PGA2 was competitive and noncompetitive with Na+ and K+, respectively. 5. The Ki values for PGA2 inhibition for ATP. Na+, K+ and Mg2+ were 6.0 x 10(-5), 2.7 x 10(-5), 10.8 x 10(-5) and 0.6 x 10(-5) M, respectively.

Animals↗
PubMed1982

Studies on the retention of passively transferred antibodies in man. I. Quantitative measurement of the antibody activities to HBs by radioimmunoassay and its application to studies on the blood level of intravenously administered 7 S or 5 S antibody.

Measurement of diluted samples of high-titred antisera to hepatitis B surface antigen (HBs) by radioimmunoassay (RIA) proved that the RIA kit can be used quantitatively in a wider range than stated by the manufacturer. Analysis of the blood level of anti-HBs activities by RIA in a homologous system gave straight declines corresponding to the diffusion and the catabolic phases of human 7 S or 5 S antibody. The half-life of the intravenously given antibody was calculated from the catabolic decline to 17.7 days for human immunoglobulin or 2.7 days for human F(ab')2 fragment.

Hepatitis B Antigens↗