Biomedical subjects

T Noguchi

Publications and source records attributed to T Noguchi.

At least 19 recordsLinked to original sources

PubMed1992

Molecular cloning of hippocalcin, a novel calcium-binding protein of the recoverin family exclusively expressed in hippocampus.

We have isolated a cDNA clone encoding a novel calcium-binding protein of the recoverin family from rat brain cDNA library. This clone (PCB11) has 588 nucleotides in the open reading frame including the termination codon, 174 nucleotides of the 5' leader and 800 nucleotides of the 3' noncoding region. The complete amino acid sequence deduced from the cDNA is composed of 195 residues, has a calculated molecular mass of 22,574 Daltons, and contains three putative calcium-binding domains of the EF-hand structure. The deduced amino acid sequence has a striking sequence homology to those of the retinal recoverin family (recoverin, visinin, P26, 23kD protein, S-modulin) and the brain-derived recoverin family (P23k, 21-kDa CaBP and neurocalcin). Northern blot, in situ hybridization, immunoblot and immunohistochemical analyses revealed that the protein is exclusively expressed in pyramidal layer of the hippocampus. The protein was therefore designated hippocalcin.

Amino Acid Sequence↗

PubMed1992

(6R)-5,6,7,8-tetrahydro-L-biopterin modulates nitric oxide-associated soluble guanylate cyclase activity in the rat cerebellum.

(6R)-5,6,7,8-Tetrahydro-L-biopterin (R-THBP) is a cofactor not only for aromatic amino acid hydroxylases in mammalian tissues but also for nitric oxide synthase (NOS) induced by endotoxins or cytokines in some kinds of cells. Recently it has been reported that nitric oxide (NO) has biological activity in endothelium and in brain as well. NO activates soluble guanylate cyclase (sGC). Superoxide reacts with NO easily and shortens the half-life of NO actions. We found, in a study using rat cerebellar cytosol fraction, that R-THBP itself did not directly activate sGC, but activated sGC at concentrations ranging from 0.1 to 10 microM only under NO generating conditions of activated NOS and in the presence of sodium nitroprusside. In addition, R-THBP (1 microM) did not alter the NOS activity, which was determined by L-citrulline formation. These results suggest that R-THBP may regulate sGC activity associated with NO formation in the central nervous system.

Animals↗

PubMed1992

cDNA cloning of rat LRP, a receptor like protein tyrosine phosphatase, and evidence for its gene regulation in cultured rat mesangial cells.

Protein tyrosine phosphatases (PTPases) are a family of enzymes that play a crucial role in the regulation of signal transduction mediated by reversible protein tyrosine phosphorylation. To understand the significance of PTPases in physiological and pathophysiological processes in the kidney, we isolated three cDNA segments encoding PTPases (LAR, LRP and a novel PTPase) from rat kidney by polymerase chain reaction (PCR). Using PCR product as a probe, we isolated a full-length cDNA of rat LRP. LRP cDNA encoded a single membrane spanning protein consisted of 796 amino acids, with two tandemly located intracellular PTPase domains. By Northern analysis, a ubiquitous pattern of LRP gene expression in rat tissues was demonstrated. In cultured rat mesangial cells, LRP mRNA was detected and the mRNA level was suppressed by either interleukin-1 or interleukin-6 treatment.

Amino Acid Sequence↗

PubMed1992

Detection of structural changes upon S1-to-S2 transition in the oxygen-evolving manganese cluster in photosystem II by light-induced Fourier transform infrared difference spectroscopy.

The light-induced Fourier transform infrared (FT-IR) difference spectrum between the S1 and S2 states of the O2-evolving photosystem II (PSII) was obtained for the first time. Detection of an S2/S1 difference spectrum virtually free from contributions by the acceptor-side signals was achieved by employing an exogenous electron acceptor, potassium ferricyanide, to trypsin-treated PSII membranes and using one-flash excitation at 250 K. A synthetic difference spectrum obtained by adding this S2/S1 spectrum to the QA-/QA spectrum measured with Mn-depleted PSII was almost identical with the difference spectrum of the S2QA-/S1QA charge separation measured with untreated PSII. This successful simulation verifies the correctness of the S2/S1 spectrum thus obtained. The observed S2/S1 spectrum reflects the structural changes within the water-oxidizing Mn cluster upon the S1-to-S2 transition, most probably changes in vibrational modes of ligands coordinating to the Mn ion(s) that is (are) oxidized upon the S2 formation and/or changes in protein conformation. The present results demonstrate that FT-IR difference spectroscopy is a promising method to investigate the structure of the intermediates of the Mn cluster involved in photosynthetic water oxidation.

Cell Membrane↗

PubMed1992

Interleukin-6 down regulates the expression of transcripts encoding cytochrome P450 IA1, IA2 and IIIA3 in human hepatoma cells.

Effects of human interleukin-6 (hIL-6), the major acute phase inducer, on the expression of transcripts encoding cytochrome P450s were examined in human hepatoma-derived cells. Using reverse-transcription polymerase chain reaction, it was demonstrated that three hepatoma cell lines, HepG2, HepG2f and Hep3B, express P450 mRNAs encoding IA1, IA2 and IIIA3, the major P450 isozymes involved in carcinogen metabolism, and that they also show induction responses to treatment with their specific inducers. When hepatoma cells were treated with hIL-6, the levels of IA1, IA2 and IIIA3 mRNAs were markedly suppressed. These findings suggest that significant down regulation of cytochrome P450s may occur during the acute phase reaction, which may result in alterations in drug biotransformation.

Base Sequence↗

PubMed1992

Cell cycle-associated expression of M2-type isozyme of pyruvate kinase in proliferating rat thymocytes.

During a complete cell cycle of rat thymocytes stimulated by concanavalin A and interleukin 2, the activity and mRNA level of pyruvate kinase reached a maximum (8-12-fold increase) 48 h after stimulation coinciding with the S-phase of the cell cycle. Increases of cellular enzyme activity, pyruvate kinase protein, and mRNA levels are correlated up to 48 h of culture. Afterwards pyruvate kinase activity and mRNA levels decrease, whereas the pyruvate kinase protein continues to increase throughout mitosis. This change of specific pyruvate kinase activity points to a posttranslational modification of the enzyme besides its transcriptional regulation. The presence of the M2-type isozyme was determined by the following methods: (a) native cellulose acetate electrophoresis and activity staining, (b) Northern blot hybridization with M1- and M2-specific cDNA probes, and (c) determination of kinetic parameters. The isozyme pattern did not change during the cell cycle progression. The induction of pyruvate kinase is completely abolished by 2-difluoromethylornithine-mediated polyamine depletion. However, the proportion of hybridizable pyruvate kinase mRNA was not affected. These data suggest the requirement of polyamines for efficient translation rather than transcription during cell growth.

Animals↗

PubMed1992

Isolation and characterization of recoverin-like Ca(2+)-binding protein from rat brain.

Rat brain was found, by immunoblot analysis, to have a protein of Mr 23,000 (P23k) that was clearly different from recoverin and was labeled with an antiserum raised against the NH2-terminus of recoverin. P23k could not be detected by an antiserum raised against the COOH-terminus of recoverin. Blots with 45Ca demonstrated that P23k bound Ca2+. This calciprotein was further purified by Ca(2+)-dependent hydrophobic interaction and ion-exchange chromatography. In SDS polyacrylamide gel electrophoresis, P23k had an apparent Mr of 21,000 in the presence of 10 microM Ca2+ and 23,000 in the absence of Ca2+ (0.1 mM EGTA). The isoelectric point of P23k was 5.6. Ca(2+)-binding analysis indicated that P23k bound 2 moles of Ca2+ per mole of protein and had two binding sites with dissociation constants of 13 microM and 0.2 microM. Purified P23k bound to the crude membrane fractions from the cerebellum, cerebrum and retina in a Ca(2+)-dependent manner. Partial amino acid sequence analysis of proteolytic fragments of P23k revealed the sequence homology between P23k and recoverin. These results suggested that P23k may act as a Ca(2+)-sensitive regulator by forming a complex with its target on the membrane.

Amino Acid Sequence↗

PubMed1992

Anti-platelet action of isoliquiritigenin, an aldose reductase inhibitor in licorice.

The mechanism was studied by which isoliquiritigenin, a new aldose reductase inhibitor purified from licorice (Glycyrrhizae radix), inhibits platelet aggregation. This new agent significantly inhibited the phosphorylation of 40,000- and 20,000-dalton proteins, and inhibited the formation of 12 (S)-hydroxy-5,8,10-heptadecatrienoic acid, 12-hydroxyeicosatetraenoic acid and thromboxane B2. The inhibitory effect of isoliquiritigenin on platelet aggregation in vitro was comparable to that of aspirin. Our findings may indicate that isoliquiritigenin elicits an anti-platelet action by inhibiting not only cyclooxygenase but also lipoxygenase or peroxidase activity in platelets. Isoliquiritigenin also showed an anti-platelet action in vivo. Isoliquiritigenin appears to be the only aldose reductase inhibitor with a significant anti-platelet action. Since the hyperaggregability of platelets has been implicated in the pathogenesis of diabetic complications, isoliquiritigenin may offer a unique benefit as an aldose reductase inhibitor.

Aldehyde Reductase↗

PubMed1992

Structure and mapping of the fosB gene. FosB downregulates the activity of the fosB promoter.

We have determined the genomic structure of the fosB gene and shown that it consists of 4 exons and 3 introns at positions also found in the c-fos gene. By deletion analysis we have characterized a region upstream of the TATA box which is the promoter region of the gene. Several consensus sequences have been identified, including an SRE and AP-1 binding site whose relative positions are identical to those in the 5' upstream region of the c-fos gene. We have also shown that FosB and c-Fos can downregulate the activity of the fosB promoter to a similar extent. The fosB gene is located in the [A1-B1] region of mouse chromosome 7.

3T3 Cells↗

PubMed1992

Kallikrein-producing cells in the rat pituitary and pineal gland.

By using an immunohistochemical technique, kallikrein-producing cells in the anterior pituitary of rats were identified to be the same as prolactin-producing cells. Kallikrein was localized at the Golgi apparatus, the rough endoplasmic reticulum and secretory granules. Kallikrein was also located in the perivascular cells of the pineal gland.

Animals↗

PubMed1992

Activation and quantitative estimation of bacteriophage T4 late regulatory signal in cis- and transconditions.

Activation of the bacteriophage T4 late gene 22 carried on the phage genome (ciscondition) or borne on a plasmid (transcondition) was quantitatively analyzed after phage infection using a lacZ reporter gene. Transcription from the late promoter was activated postreplicatively by concomitantly infecting T4 phage. A truncated T4-lacZ gene including only 15 bp of sequence upstream of the late promoter consensus of gene 22 TATAAATA, was fully activated in the ciscondition but induced to a reduced extent in the transcondition. A possible mechanism for trans-activation is discussed.

DNA, Recombinant↗

PubMed1992

Significance of multidisciplinary therapy for hepatocellular carcinoma.

The effect of multidisciplinary therapy for hepatocellular carcinoma (HCC) was evaluated in 121 resected cases. The 5-year survival was 100% for absolute curative resection (12 cases), 59.1% for relative curative resection (n = 37) and 10.9% for relative non-curative resection (n = 59). However, none of the patients survived for more than 3 years after absolute non-curative resection (n = 13). The non-recurrence in the preoperative TAE groups was different from that in non-TAE groups undergoing absolute and relative curative resection. The 1- and 3-year non-recurrence rates for relative non-curative resection were 92.3% and 53.8%, respectively, for the preoperative TAE group and 56.1% and 28.1%, respectively for the non-TAE group. These data show that preoperative TAE is effective in relative non-curative resection. Functional disturbances of the coagulation-fibrinolysis system in cirrhotic patients were improved after PSE. All patients undergoing hepatectomy after PSE had an uneventful postoperative course, including well-maintained function of the coagulation-fibrinolysis system and a decrease in splenic volume. At 1 year after hepatectomy, cirrhotic patients with critical liver function and poor coagulation-fibrinolysis showed appreciable hepatic regeneration. One patient died of hepatic failure 1 year after the operation. In recurrent HCC, the 1-, 2- and 3-year survival values after reresection were 100%, 75.0% and 25.0%, respectively. The respective values following TAE were 79.0%, 42.0% and 9.0%. Three cases of recurrent HCC were effectively treated, i.e., two patients achieved a partial response and one showed no change, by continuous intra-arterial infusion of 5-FU and lentinan with intermittent one-shot injections of epirubicin using a subcutaneous infusion pump. These three patients are alive at 1 year and 7 months, 1 year and 4 months and 6 months after the treatment, respectively.

Adult↗

PubMed1992

Microcephalic cerebrum with hypomyelination in the congenital goiter mouse (cog).

2',3'-Cyclic nucleotide 3'-phosphohydrolase activity in the cerebrum of the congenital goiter mouse (cog/cog) is reduced in comparison with the normal heterozygote (cog/+). The weight of the cog/cog cerebrum and cerebellum were significantly less than those of the normal controls, 89.0% less for the cerebrum, and 81.1% less for the cerebellum. However, no differences were observed with regard to DNA and RNA content and the RNA/DNA ratio. The results of this study indicate that hypomyelination in the congenital goiter mouse is restricted to the cerebrum, and is not related to arrested glial proliferation.

Animals↗

PubMed1992

The thickness of the sound and periodontally diseased human cementum.

Cementum of teeth previously analysed for fluoride was re-examined in order to determine whether or not periodontal disease had affected the thickness of the tissue. In the periodontally diseased teeth the cementum was thinner than normal in the middle region of the root. The apical cementum, however, was significantly thicker in periodontally diseased than in the sound teeth of subjects over 60 yr old. This may account for the higher total fluoride levels previously reported in the apical cementum of these same teeth.

Adult↗

PubMed1992

Lactate dehydrogenase isoenzymes in matrix vesicles (review).

Matrix vesicles (MV) isolated from mineralizing tissues contain high alkaline phosphatase (ALPase) activities associated with the membrane; this may be because MV originate from the plasma membrane of chondrocytes. Previous studies in our laboratory demonstrated that lactate dehydrogenase (LDH) isoenzymes, which appeared to be derived from chondrocytes cytosol, were located in MV of the epiphyseal growth plate of young-rabbit leg bones [1]. In the epiphyseal cartilage, alkaline phosphatase (ALPase) is enriched in the growth zone, whereas it is rarely detected in the resting zone, suggesting that MV containing ALPase are not present in the resting zone. In recent study, we divided the epiphyseal cartilages of young-rat rib bones into the growth zone and the resting zone, followed by the isolation of MV after collagenase digestion. MV containing ALPase and LDH were found in the growth zone, and surprisingly, vesicles containing LDH without ALPase were found in the resting zone [2]. The function of LDH-containing vesicles without ALPase is unknown at the present. However, these findings might accelerate the studies on cell-mediated calcification, because (1) LDH could be a marker enzyme of these vesicles, (2) LDH is found to be a specific cytosolic enzyme which is enfolded in these vesicles, suggesting that an unknown mechanism for the specific uptake of the cytosolic enzyme might be present.

Animals↗

PubMed1992

Microcephalic cerebrum with hypomyelination in the pygmy mouse (pg).

To determine whether somatomedin has a direct action on cerebral development instead of an indirect action of a growth hormone, we examined the central nervous system of the pygmy mouse (pg), a mutant with normal somatomedin activity. Our findings are: (A) the weights of the pg/pg cerebrum and cerebellum weighted were significantly less than those of the normal controls (pg/+), 14 and 15% less, respectively; (B) the total DNA content was reduced by 17% in the cerebrum and cerebellum of the pg/pg mouse; (C) the total RNA content was reduced in the cerebrum and cerebellum, proportional to the reduction in DNA; (D) CNPase activity was reduced selectively in the cerebrum of the pg/pg mouse by 25%; and (E) the pg/pg mice exhibited a strikingly reduced level of activity with an indistinct diurnal periodicity. Therefore, the present findings suggest that the action of somatomedin on the proliferation and maturation of glial cells might be a necessary precondition to myelin formation.

Animals↗

PubMed1992

Dissociation of collagenase-tissue inhibitor of metalloproteinases-1 (TIMP-1) complex--its application for the independent measurements of TIMP-1 and collagenase activity in crude culture media and body fluids.

Collagenase-tissue inhibitor of metalloproteinases-1 (TIMP-1) complex was prepared from activated collagenase and TIMP-1 purified from culture media of human skin fibroblasts. After having been confirmed to be a complex by zinc chelate chromatography, the complex was demonstrated to dissociate by passage through an anti-TIMP-1 monoclonal antibody-affinity column. On the basis of above evidence, a simple strategy was set up for the independent measurements of TIMP-1 concentration, and both active and total collagenase activities in crude culture media and body fluids.

Body Fluids↗

PubMed1992

Effect of dietary proteins on insulin-like growth factor-1 (IGF-1) messenger ribonucleic acid content in rat liver.

Effects of quantity and quality of dietary proteins on plasma immunoreactive insulin-like growth factor-1 (IGF-1) concentration, and content of IGF-1 mRNA in rat liver were investigated in rats. Plasma immunoreactive IGF-1 concentration in rats given a casein diet was higher than that in rats given a soya-bean-protein or protein-free diet. The IGF-1 mRNA content in liver was estimated by the Northern blot hybridization technique employing 32P-labelled rat IGF-1 complementary DNA (cDNA). At least four molecular species of IGF-1 mRNA of different molecular weight were found in rat liver. The sizes were 0.8-1.2, 2.0, 3.6-4.0 and 7.4 kb. Most of the mRNA species decreased in the livers of rats given a gluten diet (120 g gluten/kg diet) compared with rats given the casein diet. In particular, mRNA of 7.4 kb decreased markedly. When rats were fed on the protein-free diet, mRNA of all species decreased significantly. The estimated IGF-1 mRNA in the livers of rats fed on the gluten or protein-free diet was almost 0.4 of that of the rats given the casein diet. Feeding the soya-bean-protein diet did not result in a marked effect on the hepatic content of mRNA species of IGF-1. The results showed that liver IGF-1 mRNA content is sensitively regulated by quantity and nutritional quality of dietary proteins.

Animals↗