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Y Imai

Publications and source records attributed to Y Imai.

At least 1,009 records · Page 56Linked to original sources
PubMed1988

The importance of threonine-301 from cytochromes P-450 (laurate (omega-1)-hydroxylase and testosterone 16 alpha-hydroxylase) in substrate binding as demonstrated by site-directed mutagenesis.

Threonine-301 from rabbit liver cytochromes P-450 (laurate (omega-1)-hydroxylase and testosterone 16 alpha-hydroxylase) has been replaced by histidine via site-directed mutagenesis. In the oxidized state the mutant P-450s exhibited typical low-spin type absorption spectra of P-450 and their reduced CO complexes showed a Soret peak at 450 nm. However, no spectral change was induced on addition of substrates for their wild-type counterparts. The mutant P-450s were also completely devoid of the hydroxylase activity. These findings suggest that threonine-301, which is highly conserved in P-450s and located at the distal heme surface, plays an important role in substrate binding.

Amino Acid Sequence↗
PubMed1988

Effects of opioids on the heat stimulus-evoked substance P release and thermal edema in the rat hind paw.

We examined the effect of opioids on the heat stimulus-evoked release of substance P (SP) into the subcutaneous space and the formation of edema in the rat hind paw. Immersion of the rat hind paw for 30 min into hot water adjusted to 47 degrees C led to a marked increase in the release of SP into the subcutaneous perfusate with the formation of thermal edema. Intra-arterial infusion of morphine (10-100 mumol/kg) or ethylketocyclazocine (30-100 mumol/kg) inhibited dose dependently the heat stimulus-evoked increase in SP release and the thermal edema and the inhibitory effects were antagonized by pretreatment with N-methyl levallorphan (10 mg/kg i.p.) and Win 44,441-3 (10 mg/kg i.p.). The heat stimulus-evoked release of SP was reduced significantly during the intra-arterial infusion of [D-Ala2,Met5] enkephalinamide (100 mumol/kg). These results suggest that the opioid-induced inhibition of heat-induced edema could result from inhibition of the release of SP from peripheral sensory nerve endings.

Animals↗
PubMed1988

Incorporation of sulfhydryl compounds into melanins in vitro.

Cysteine is known to be involved in pheomelanin synthesis. Available evidence, however, indicates that glutathione may also play an important role in melanogenesis. This in vitro study clarifies how cysteine and glutathione participate in melanogenesis. Melanins were prepared by tyrosinase oxidation of 3,4-dihydroxyphenylalanine (dopa) with various amounts of cysteine or glutathione, and were subjected to HCl hydrolysis. Synthetic melanins and the hydrolyzed melanins gave N/S molar ratios corresponding to those calculated from the ratio of dopa to cysteine or glutathione. On hydriodic acid hydrolysis, dopa plus cysteine-melanins and dopa plus glutathione-melanins gave aminohydroxyphenylalanine and cysteine, respectively, the yields of which were proportional to the sulfur content. The results indicate that cysteine is integrated into benzothiazine units (pheomelanins) while glutathione is connected to dihydroxyindole units (eumelanins) with the retention of glutathione moiety. Analysis of natural melanins, prepared by HCl hydrolysis of Sepia, B16, and Harding-Passey melanosomes, indicates that sulfur (0.4-1.4%) in these natural melanins may be derived artificially from the reaction of melanins with cysteine or cystine in the course of HCl hydrolysis.

Animals↗
PubMed1988

Microheterogeneity in the major phenobarbital-inducible forms of rabbit liver microsomal cytochrome P-450 as revealed by nucleotide sequencing of cloned cDNAs.

We have isolated one full-length cDNA clone, termed pHP1, and a number of clones of shorter insert lengths, tentatively called b14, b46, etc., all encoding phenobarbital- (PB-) inducible forms of rabbit liver microsomal cytochrome P-450, and determined their nucleotide sequences. The polypeptides encoded by these cDNAs can be classified into five types, represented by HP1, b14, b46, b52, and b54, the deduced amino acid sequences of which are more than 95% similar to one another. Amino acid differences among them total 24 positions, which are distributed over the entire sequence, in contrast to the microheterogeneity observed in two PB-inducible rat liver microsomal cytochromes P-450 (P-450b and P-450e). The primary structure deduced for the HP1 protein is 97% similar to that determined for rabbit P-450 LM2 (form 2), which has been purified by Coon and co-workers [van der Hoeven, T. A., Haugen, D. A., & Coon, M. J. (1974) Biochem. Biophys. Res. Commun. 60, 569-675; Haugen, D. A., & Coon, M. J. (1976) J. Biol. Chem. 251, 7929-7939] as the major PB-inducible form of rabbit liver microsomal cytochrome P-450. The amino acid sequence of P-450(1), which we have purified as the major PB-inducible rabbit liver cytochrome P-450, was partially determined with the sequence reported for P-450 LM2 as a reference. The two sequences are closely similar to each other, but at least two amino acid differences can be detected between them.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1988

Comparison of primary structures deduced from cDNA nucleotide sequences for various forms of liver microsomal cytochrome P-450 from phenobarbital-treated rabbits.

cDNA clones, termed pHP2, b32-3, b43, and b43-1, encoding cytochromes P-450 that are expressed in the liver of phenobarbital- (PB-) treated rabbits were isolated, and their nucleotide sequences were determined. pHP2 cDNA contains an open reading frame for a 490-residue protein and is a full-length counterpart of pP-450PBc2 [Leighton, J. K., Debrunner-Vossbrinck, B. A., & Kemper, B. (1984) Biochemistry 23, 204-210]. The b32-3 insert has a sequence for a protein whose primary structure is 91% similar to that of progesterone 21-hydroxylase P-450 1, though this cDNA lacks the sequence encoding the amino-terminal 110 residues. The overlapping clones b43 and b43-1 together encode an ethanol-inducible form of cytochrome P-450, though the amino-terminal five or more residues are missing in the composite b43/b43-1 sequence. Northern blot analysis showed that the b43/b43-1 protein is more strongly inducible by polycyclic aromatic hydrocarbons and isosafrole than by PB, in contrast to the case of the HP2 and b32-3 proteins. A comparison of the primary structures of eight forms of cytochrome P-450, including the HP2, b32-3, and b43/b43-1 proteins, that are expressed in the liver of PB-treated rabbits showed that 149 out of 487-492 amino acid residues are conserved in these cytochromes P-450. The eight forms can be assigned to three rabbit cytochrome P-450 gene subfamilies, P450IIB, P450IIC, and P450IIE. It was also shown that the members of the rabbit P450IIC subfamily can be further classified into three subgroups on the basis of their sequence similarity.

Amino Acid Sequence↗
PubMed1988

The position of the microtubule-organizing center relative to the nucleus is independent of the direction of cell migration in Dictyostelium discoideum.

Dictyostelium amoebae can migrate in several different modes. We tested for correlations of the direction of cell locomotion with the relative positions of the nucleus and microtubule-organizing center (MTOC). Five cases were analyzed on electron micrographs with a microcomputer. Each mode of movement showed characteristic locations of the MTOC relative to the nucleus; however, they differed in the various cases. In randomly migrating interphase amoebae, the number of cells with the MTOC located behind the nucleus was twice as great as those with the MTOC located ahead of the nucleus. During chemotactic migration toward folic acid, cells with the MTOC behind the nucleus were more numerous, with a concomitant reduction of anterior MTOCs. When amoebae aggregated on agar plates, a posterior location of the MTOC was most strikingly favored, whereas in cells aggregating under submerged conditions, the MTOC was indifferently anterior or posterior to the nucleus. (It may be significant that EDTA-resistant cell-cell adhesion was fully expressed in the former cells, but weaker in the latter.) Finally, in the case of chemotactically migrating cells from dissociated pseudoplasmodia, which adhere by means of other molecules, the MTOC was consistently ahead of the nucleus. Thus the MTOC shows no necessary preferential position anterior or posterior to the nucleus; its position, rather, correlates with the type of migration and perhaps with the nature of cell-cell adhesion.

Cell Movement↗
PubMed1988

Serial assay for IGM anti-HBc in patients with anti-HBe-positive chronic hepatitis and its significance for long-term prognosis.

Serial assays for immunoglobulin M antibody to hepatitis B core antigen (IgM anti-HBc) were performed in 51 patients with antibody to hepatitis B e antigen (anti-HBe) in their sera. IgM anti-HBc was detected periodically and persistently in 8 (53%) of 15 patients with chronic hepatitis whose serum glutamic pyruvic transaminase (GPT) levels were elevated and was not detected in 36 patients with normal serum GPT levels. Antibody to delta agent was not detected in any of the patients. Of the eight patients positive for IgM anti-HBc, four had a high titer of IgM anti-HBc and either developed liver cirrhosis (three cases) or died due to massive hepatic necrosis (one case); the other four showed a low level of IgM anti-HBc and either recovered (two cases) or developed chronic persistent hepatitis (two cases). Of seven patients negative for IgM anti-Hbc, two had a fatty liver, and five, who had a history of blood transfusion, had chronic hepatitis. Thus, even though anti-HBe may be present, if the titer of IgM anti-HBc is high, the histological activity can be expected to increase, and the prognosis will be poor. If the titer of IgM anti-HBc is low, the histological activity may be expected to decrease, and the prognosis may be good. In patients with abnormally high serum GPT but without IgM anti-HBc, another type of hepatitis or a secondary form of liver disease should be considered.

Adult↗
PubMed1988

Morphological diversity of DRC-1 positive cells: human follicular dendritic cells and their relatives.

Follicular dendritic cells (FDC) and their relatives of the human tonsils and lymph nodes were immunoelectron microscopically analyzed with a monoclonal antibody DRC-1 (DAKO) in a combination with an enzymatic isolation technique. DRC-1+ cells were largely grouped into three type A (large mono- to multinucleated, sea anemone-fashioned, bearing labyrinth structures, in germinal center), type B (oligodendritic or stellate, medium-sized, in the corona and the primary follicle) and type C (individually located, medium-sized. lymphoid cell-fashioned, outside follicles). Type C were found in hyperplastic lymphoid tissue as well as in some granulation tissue. The DRC-1+ mononuclear cells were curiously encountered in the peripheral blood of some autoimmune disease patients in contrast with no identification in healthy persons. Furthermore some DRC-1+ cells obtained from autoimmune patient were confirmed to proliferate in culture.

Antibodies, Monoclonal↗
PubMed1988

Lysozyme localization in human gastric and duodenal epithelium. An immunocytochemical study.

The distribution of lysozyme in normal gastric and duodenal mucosa was studied by light- and electron-microscopic immunocytochemical techniques (direct enzyme-labeled antibody method). In the duodenal mucosa, lysozyme was found in the Paneth cells and the epithelial cells of Brunner's glands. Electron-microscopically, lysozyme was found in rough endoplasmic reticulum and perinuclear spaces, which were assumed to be protein-synthesizing organelles, and also in the secretory granules of Paneth cells. Additionally, lysozyme was detected in the stomach in mucinous granules and in some parts of the rough endoplasmic reticulum within the epithelial cells of the pyloric glands, the mucous neck cells of the fundic glands, and in several surface epithelial cells of the plyoric and fundic regions. This suggests that some quantity of lysozyme in gastrointestinal secretion originates from the gastric and duodenal glands, and that it acts as a defense mechanism in the gastrointestinal tract.

Duodenum↗
PubMed1988

Left ventricular characteristics during exercise in patients after Fontan's operation for tricuspid atresia.

Left ventricular function during supine bicycle exercise was studied using multigated blood pool imaging in ten patients with tricuspid atresia after Fontan's operation and in 13 children and adults (control group). The mean age of the patients was 16 years and the mean interval between operation and study was 5 years. The peak work loads that the patients could perform were similar to those in the control group. Work loads and heart rates during radionuclide study in the operated group were also similar to those in the control group. The left ventricular ejection fraction at rest and during exercise in the operated group was less than in the control group, although the net increase during exercise was similar in the two groups. During exercise, left ventricular end-diastolic volume decreased significantly in the operated group. In the control group, this variable did not change significantly. Left ventricular stroke volume increased during exercise in the control group but it did not change significantly in the operated group. These data indicate that in patients after Fontan's operation, left ventricular performance remains low during exercise, which is in part due to diminished left ventricular preload reserve, and this in turn may be caused by reduced reserve of right heart output.

Adolescent↗
PubMed1988

Enhancement of the activities of glycosyltransferases involved in the biosynthesis of mucin-type sugar chains in autoimmune MRL lpr/lpr mouse T cells.

Lymph node (LN) T cells from autoimmune MRL/MpJ-lpr/lpr (lpr) mice and control MRL/MpJ-+/+ (+/+) mice were compared as to their cell surface lectin-binding sites and glycosyltransferase activities. T cells from enlarged LN of lpr mice expressed a higher amount of binding sites for lectins reactive to mucin-type sugar chains than normal +/+ mouse T cells. Correspondingly, glycosyltransferase activities involved in the biosynthesis of mucin-type sugar chains were higher in lpr mouse T cells than in +/+ T cells. The activities of UDP-N-acetylgalactosamine (GalNAc):polypeptide GalNAc transferase and UDP-galactose (Gal):asialo bovine submaxillary mucin (BSM) Gal transferase were found to be elevated. The activity of UDP-Gal:asialo-agalacto transferrin Gal transferase, which is involved in the biosynthesis of complex type sugar chains, was also increased in lpr mice but to a smaller extent than the mucin-type Gal transferase activities. An abnormality in sialyltransferase activity was also found in lpr T cells.

Animals↗
PubMed1988

Functional deficiencies of spleen dendritic cells in autoimmune MRL/lpr mice.

We investigated functional aspects of splenic dendritic cells (DC) obtained from MRL/MpJ-lpr/lpr (MRL/l) mice, and their normal counterparts, MRL/MpJ-+/+ (MRL/+) mice. In vitro antigen-presenting activity of DC obtained from MRL/l mice was impaired compared with that of DC from MRL/+ mice. Another major functional aspect of DC, i.e., stimulator cell activity in the allogeneic mixed lymphocyte reaction (MLR), was also found to be impaired in MRL/l mice. MRL/l mice and MRL/+ mice were also examined for co-operation between macrophages (M luminal diameter) and DC. We found peritoneal resident M luminal diameter obtained not only from MRL/+ mice but also from MRL/l mice released a soluble factor which enhanced the activity of DC from the respective mice. Furthermore, DC from both MRL/l and MRL/+ mice responded to the culture supernatant of a mouse macrophage hybridoma clone, S44, which releases a factor that enhances the antigen-presenting activity of DC, and their activity as stimulator cells in the allogeneic MLR was enhanced. However, the degree of enhancement was less in MRL/l mice than in MRL/+ mice.

Animals↗
PubMed1988

Effect of an autoreactive T cell clone from (NZB x NZW)F1 mice on the production of anti-DNA antibodies in vivo and in vitro.

An autoreactive T lymphocyte clone, designated as F1C4 was established from an autoimmune mouse strain (NZB/NZW)F1. This clone proliferated in the presence of mitomycin C-treated splenic adherent cells (MMC-SAC) from syngeneic mice. This response was dependent on the numbers of MMC-SAC. The specificity of F1C4 for I-A was determined by an inhibition test carried out with monoclonal anti-Ia sera. Furthermore, the F1C4 cells did not exhibit alloreactivity in a proliferation assay and did not react to foreign antigens such as fetal calf serum (FCA) used in the culture medium. When F1C4 cells were cultured with autologous non-T cells in the absence of antigen, they strongly enhanced IgM class anti-ssDNA production from non-T cells of both young and old B/W F1 mice at appropriate cell numbers in vitro. Furthermore, the production of IgG class anti-ssDNA from non-T cells of old B/W F1 mice was also enhanced. The adoptive transfer of F1C4 cells enhanced the levels of both IgM and IgG anti-ssDNA antibodies in the serum of aged B/W F1 mice. Moreover, the serum levels of anti-ssDNA of IgG2a and IgG2b subclasses were readily enhanced by the transfer of F1C4 in vivo.

Animals↗
PubMed1988

A case of membranous lipodystrophy complicated by Fanconi's syndrome.

A case of membranous lipodystrophy complicated by Fanconi's syndrome is described. A 40-year old man complaining of pain in his legs was admitted to our hospital. Roentgenograms showed cystic changes in the long bones. Biopsy of the affected lesion of the femur revealed a peculiar membranocystic structure in the marrow that is typical of membranous lipodystrophy. He had a neuropsychiatric disorder which is often associated with this disease. Laboratory studies were remarkable for renal proximal tubular dysfunction, i.e., Fanconi's syndrome. Membranous lipodystrophy is a rare, hereditary disease that has been reported mainly from Japan and Finland. This is the first case of this disease complicated by Fanconi's syndrome. The possible relationship between these disorders is discussed.

Adult↗
PubMed1988

Conotruncal repair of tetralogy of Fallot.

A repair within the conotruncal portion of the right ventricle is introduced. It was used for the intracardiac repair of 30 consecutive patients with tetralogy of Fallot. The infundibular septum was totally resected to reduce the muscular outflow stenosis. Short patch infundibuloplasty with a large monocusp was then used. Instead of the tricuspid septal leaflet, the membranous flap was employed as the suture line for patching the ventricular septal defect (VSD) to avoid a conduction disturbance, residual VSD, and fixing of the tricuspid septal leaflet. The right ventricular (RV) to systemic arterial pressure ratio was 50.0 +/- 14.6% (N = 26) and right atrial pressure was 9.0 +/- 2.5 mm Hg (N = 26) one month after operation. RV end-diastolic volume was 93.0 +/- 30.5% of normal (N = 15) before operation and 96.7 +/- 29.0% of normal one month after operation in the same patients. These data suggest that a conotruncal repair can maintain good RV function with low right atrial pressure and with no increase of RV volume.

Child↗
PubMed1988

Changes in hepatic functional reserve after transcatheter embolization of hepatocellular carcinoma. Assessment by maximal removal rate of indocyanine green.

To clarify the influence of transcatheter arterial embolization (TAE) on hepatic function, the maximal removal rate of indocyanine green (ICG-Rmax), which represents the hepatic functional reserve, and the plasma disappearance rate of indocyanine green (k-ICG) were measured serially before and after 15 TAE procedures performed on 13 hepatocellular carcinoma (HCC) patients with underlying hepatic diseases. Compared to the values before TAE, ICG-Rmax values did not change or gradually decreased during 4 weeks in seven of the 13 patients but markedly decreased in the remaining six by as much as 50% during the first week. k-ICG values remained almost unchanged at any time after TAE. Albumin and prothrombin time were serially measured before and after 24 TAE procedures performed on 21 HCC patients with underlying hepatic diseases in whom no plasma products had been used for therapy. Albumin decreased by up to 75% in one of the 21 patients during the first week but did not change or gradually decreased in 20 of the 21 patients. Prothrombin time showed no obvious changes. This study showed that prominent changes occurred in ICG-Rmax, i.e., in the hepatic functional reserve, after TAE.

Aged↗
PubMed1988

Characterization of rabbit liver cytochrome P-450 (laurate omega-1 hydroxylase) synthesized in transformed yeast cells.

Three cDNAs for chimeras between cytochrome P-450s (pHP3 and pHP2-1) were constructed and inserted between the alcohol dehydrogenase promoter and terminator regions of the yeast expression vector pAAH5 to form expression plasmids, pAH3P2, pAH3E2, and pAH3A2. pAH3P2 contained the entire coding sequence of cytochrome P-450 (pHP2-1) except for the 3rd, the 8th, the 36th, and the 42nd residues of the total of 490 amino acids. Nucleotide sequences of pAH3P2 were replaced with those of cytochrome P-450 (pHP3) in the region coding for the NH2-terminal 210 and 262 amino acid residues to yield pAH3E2 and pAH3A2, respectively. The three expression plasmids were introduced into Saccharomyces cerevisiae AH22 cells and cytochrome P-450 s (3P2, 3E2, and 3A2) were purified from the microsomal fractions of the transformed yeast cells. In the oxidized state either of the cytochromes exhibited a low- and high-spin mixed-type spectrum of cytochrome P-450. The reduced CO complex of the cytochromes showed a Soret absorption maximum at 450 nm. When laurate or caprate was added to ferric cytochrome P-450 s (3P2 and 3E2), the spectrum was converted to that of the typical high-spin type, indicating the binding of the fatty acids to the substrate site of the cytochromes. On the other hand, the addition of the fatty acids to ferric cytochrome P-450 (3A2) induced no spectral change. Only chemicals having a carboxyl group caused such spectral conversion of cytochrome P-450 (3P2) among dodecyl compounds examined.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗