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Biomedical subjects

T Noguchi

Publications and source records attributed to T Noguchi.

At least 19 recordsLinked to original sources
PubMed1995

Degradation of purines: only ureidoglycollate lyase out of four allantoin-degrading enzymes is present in mammals.

It is generally accepted that all of the allantoin-degrading enzymes (allantoinase, allantoicase, ureidoglycollate lyase and urease), used in purine degradation, were lost during mammalian evolution. However, surprisingly, ureidoglycollate lyase has been found in a mammalian tissue. Ureidoglycollate lyase was purified to homogeneity and characterized from rat-liver mitochondria. The apparent Km (17 mM) of the rat enzyme for ureidoglycollate was much higher than that (0.33 mM) of fish-liver ureidoglycollate lyase. The rat-liver enzyme differed from the fish-liver enzyme in enzymic, physical and immunological properties.

Allantoin↗
PubMed1995

Primary structure of murine red blood cell-type pyruvate kinase (PK) and molecular characterization of PK deficiency identified in the CBA strain.

To clarify the molecular abnormality of pyruvate kinase (PK) deficiency identified in the mutant mice of CBA-Pk-1slc/Pk-1slc, we cloned murine red blood cell-type PK (R-PK) cDNA of those animals. The cDNA sequence spans 1827 bp, including an open reading frame that can encode 574 amino acids. Homology in the coding sequences between murine and human R-PK was 86.1% at nucleotide and 91.5% at amino acid levels. A homozygous missense mutation at nucleotide 1013 GGT-->GAT was identified in the cDNA sequence of the mutant, causing a single amino acid substitution at no. 338Gly-->Asp of the murine R-PK. Six amino acid residues, 335Val-336Ala-337Arg-338Gly-339Asp-340L eu, were encoded in exon 8 of both human and rat L (liver-type)/R-PK genes and were evolutionarily conserved in PK from bacteria through humans. 337Arg was reported to be important for substrate binding, suggesting that the amino acid change would impair substrate affinity of the PK subunit. A homozygous missense mutation at the catalytic domain has been identified in a human PK variant, PK Hong Kong (941ATT-->ACT, 314 Ile-->Thr). Although both 1013A and 941C gave rise to an amino acid change adjacent to the active site and may interfere with substrate binding to the subunit, the degree of anemia was much more severe in the human case. The erythroid-progenitor cell number increased in the spleen of Pk-1slc/Pk-1slc mice to a level approximately 66 times higher than that in normal CBA mice, suggesting that compensatory extramedullary erythropoiesis in the spleen of the mutant mice, but not in the human variant, might account for the observed difference in the phenotype.

Amino Acid Sequence↗
PubMed1995

Molecular interactions of the redox-active accessory chlorophyll on the electron-donor side of photosystem II as studied by Fourier transform infrared spectroscopy.

A Fourier transform infrared (FTIR) difference spectrum upon photooxidation of the accessory chlorophyll (Chlz) of photosystem II (PS II) was obtained at 210 K with Mn-depleted PS II membranes in the presence of fericyanide and silicomolybdate. The observed Chlz+/Chlz spectrum showed two differential bands at 1747/1736 and 1714/1684 cm-1. The former was assigned to the free carbomethoxy C = 0 and the latter to the keto C = 0 that is hydrogen-bonded or in a highly polar environment. Also, the negative 1614 cm-1 band assignable to the macrocycle mode indicated 5-coordination of the central Mg. The negative 1660 cm-1 band, possibly due to the strongly hydrogen-bonded keto C = 0, may suggest oxidation of one more Chlz, although an alternative assignment, the amide I mode of proteins perturbed by Chlz oxidation, is also possible.

Cell Membrane↗
PubMed1995

Ras-independent and wortmannin-sensitive activation of glycogen synthase by insulin in Chinese hamster ovary cells.

Activation of glycogen synthase is one of the major metabolic events triggered by exposure of cells to insulin. The molecular mechanism by which insulin activates glycogen synthase was investigated. The possible role of Ras and mitogen-activated protein kinase cascade was investigated with a stable cell line, CHO-IR-C/S 46, that overexpresses insulin receptors and a catalytically inactive SH-PTP 2 protein phosphatase and in which insulin does not induce the formation of the Ras-GTP complex or the subsequently activation of the mitogen-activated protein kinase cascade. Insulin activated glycogen synthase in this cell line to a similar extent as in parental CHO-IR cells. The importance of heteromeric phosphoinositide (PI) 3-kinase in insulin activation of glycogen synthase was examined in a stable cell line, CHO-IR/delta p85, that overexpresses insulin receptors and a dominant negative mutant (delta p85) of the 85-kDa subunit of PI 3-kinase that lacks the binding site for the catalytic 110-kDa subunit. Insulin-dependent activation of PI-3 kinase and glucose transport, but not the formation of the Ras-GTP complex, are markedly attenuated in this cell line. In CHO-IR/delta p85 cells, insulin activated glycogen synthase to a similar extent as in parental CHO-IR cells. The failure of overproduction of the mutant (delta p85) protein to inhibit insulin activation of glycogen synthase was also confirmed by transient expression in Rat 1 cells with the use of a recombinant vaccinia virus. However, wortmannin abolished insulin activation of glycogen synthase in all cell lines. These data suggest that existence of a Ras-independent and wortmannin-sensitive pathway for activation of glycogen synthase by insulin.

Androstadienes↗
PubMed1995

Compound heterozygous mutations affecting both hepatic and erythrocyte isozymes of pyruvate kinase.

Novel erythrocyte pyruvate kinase gene defects were found in a patient without a family history of consanguinity. The polymerase chain reaction products of the R-type pyruvate kinase cDNA from the propositus contained two point mutations of Ser80 (TCC)-->Pro (CCC) and Arg490 (CGG)-->Trp (TGG). Allele-specific polymerase chain reaction of the genomic DNA revealed that this patient was a compound heterozygote. The mobilities of the patient's L- and R-type pyruvate kinase by thin-layer polyacrylamide gel electrophoresis were abnormal. The results are consistent with the fact that these mutations are within exons common to the hepatic and erythrocyte isozymes.

Adult↗
PubMed1995

Loss of heterozygosity and linkage analysis in breast carcinoma: indication for a putative third susceptibility gene on the short arm of chromosome 8.

We have analysed losses of heterozygosity (LOH) at eight markers from the p12-p22 region of human chromosome 8 in a panel of 113 breast tumors. LOH were detected in almost half of the tumors. The most frequently deleted region included microsatellite (CA)n repeats markers D8S258, D8S133 and D8S259, located at 8p12-p22, while markers NEFL and LPL appeared less frequently altered. In parallel, linkage analysis was performed using the same informative markers, to test for the involvement of chromosome 8p loci in familial breast cancer. Positive cumulative multipoint lod score of 2.51 at theta = 0.0 was obtained with markers NEFL and D8S259. These results suggest that region 8p12-p22 carries at least one tumor suppressor gene involved in sporadic and perhaps also in familial breast cancer.

Breast Neoplasms↗
PubMed1995

Biochemical characterization of two isoforms of FLT4, a VEGF receptor-related tyrosine kinase.

The FLT4 gene encodes a tyrosine kinase receptor related to the two identified receptors for vascular endothelial growth factor (VEGF), FLT1 and FLK1/KDR. Two isoforms of FLT4, differing by their C-terminal ends, have been identified. The long form has 65 additional amino acid residues. We have shown that FLT4 is a highly glycosylated, relatively stable, cell surface associated kinase of approximately 180 kDa. In order to study the signal transduction molecules associated with the FLT4 pathway, and in the absence of a known ligand, we constructed two chimeric molecules (FF4S and FF4L) made of the extracellular region of the CSF1 receptor (Fms gene product) and of the transmembrane and intracellular regions of either form of FLT4. These two chimeric forms were expressed in Rat 2 transfectants. We assayed the ligand-induced capacity of the FF4 short and long forms to sustain growth of Rat 2 cells in semisolid medium. In a soft agar assay, only the long form was able to induce the growth of Rat 2 cells upon ligand treatment. The two forms of FLT4 therefore have different functional capacities. We looked for association and/or phosphorylation of phospholipase C gamma (PLC gamma) and phosphatidylinositol-3'-phosphate (PI3K), after stimulation of the FF4 molecules by CSF1. Finally, we have studied the expression of the Flt4 gene in mouse embryos and in the adult by in situ hybridization. Flt4 transcripts were found at day 12.5 post-coïtum and thereafter, including the adult mouse, predominantly in the pericardium, pleural membranes and in the lung.

Amino Acid Sequence↗
PubMed1995

Photosensitive nitrile hydratase intrinsically possesses nitric oxide bound to the non-heme iron center: evidence by Fourier transform infrared spectroscopy.

Nitrile hydratase (NHase) from Rhodococcus sp. N-771 is a photosensitive enzyme that catalyzes hydration of nitriles to the corresponding amides. Light-induced Fourier transform infrared difference spectra between the inactive and active forms of NHase were measured with both the natural (14N) and 15N-labeled NHases. The results showed, for the first time, that NHase intrinsically possesses nitric oxide (NO) molecules bound to the non-heme iron center. The possible role of NO in the photoactivation process of NHase is discussed.

Enzyme Activation↗
PubMed1995

Alcohol:NAD+ oxidoreductase is present in rat liver peroxisomes.

Alcohol:NAD+ oxidoreductase was found in the peroxisomes of animal liver for the first time as follows. The distribution of alcohol:NAD+ oxidoreductase activity with nonanol as substrate in the light mitochondrial fraction (peroxisome-enriched fraction) of rat liver was examined by centrifugation in a sucrose density gradient. Most of the enzyme activity was localized in the mitochondria, with some activity in the peroxisomes. The administration of clofibrate, a peroxisome proliferator, to rats resulted in a marked increase of the enzyme activity in the peroxisomes, but not in the mitochondria. The enzyme was found to be located in the matrix of the peroxisomes. The evidence was obtained that the enzyme differed from alcohol dehydrogenases and alcohol oxidizing systems found previously. The enzyme activity was not affected by pyrazole, an inhibitor of alcohol dehydrogenase and sodium azide, an inhibitor of catalase. The enzyme was NAD(+)-dependent and oxidized straight chain aliphatic alcohols with a variety of carbon chains (C2-C18), showing the maximum on nonanol. Km values toward these aliphatic alcohols decreased with increasing chain length. The major reaction product was identified as the carboxylic acid by using high performance liquid chromatography.

Alcohol Dehydrogenase↗
PubMed1995

Patterns of loss of heterozygosity at loci from chromosome arm 13q suggests a possible involvement of BRCA2 in sporadic breast tumors.

Loss of heterozygosity (LOH) at loci from chromosome 13 is frequently observed in breast cancer. Chromosome 13 contains at least two cancer genes, the well-characterized RB1 gene located at 13q14 and the breast cancer-susceptibility gene, BRCA2, recently localized to 13q12. To investigate the possible involvement of BRCA2 in sporadic breast tumors, we looked at LOH at eight microsatellite (CA)n markers distributed along chromosome 13 in a panel of 59 primary breast carcinomas. We show that some LOH does not include the RB1 locus and is associated with the BRCA2 gene region.

Alleles↗
PubMed1995

The preoperative nutritional assessment of surgical patients with hepatic dysfunction.

The precise influence of malnutrition on postoperative complications in patients with hepatic dysfunction is not well known. In phase I of the present study, we evaluated the nutritional status of 102 patients with hepatic dysfunction who were admitted for elective hepatobiliary or pancreatic surgery, and a model for the prediction of postoperative complications was developed using a computer-based stepwise regression procedure. The equation for this Prognostic Nutritional Index for Surgery (PNIS) was calculated by [-0.147 x (% weight change) + 0.046 x (% ideal body weight) + 0.010 x (actual triceps skinfold thickness as a % of standard value) + 0.051 x (hepaplastintest)]. In phase II this model was prospectively tested in 182 patients, including 145 with hepatic dysfunction. A total of 18 patients were classified as having a poor prognosis (PNIS < 5) and all of these patients in fact developed postoperative complications: 128 patients were classified as having an intermediate prognosis (5 < or = PNIS < 10), 23 (18.0%) of whom developed postoperative complications, and none of the 36 patients who were classified as having a good prognosis (PNIS > or = 10) developed any postoperative complications. These results demonstrate the importance of performing a thorough preoperative nutritional assessment of patients with hepatic dysfunction as malnourished patients with PNIS < 10 may need preoperative nutritional management, even when their surgical procedures are not major.

Humans↗
PubMed1995

Alteration in gastric nerve fibers containing gastrin-releasing peptide in relation to the gastrin-producing cell population after truncal vagotomy in a rat model.

The fine structural alteration in the gastric nerve fibers containing gastrin-releasing peptide (GRP) was studied in relation to the dynamics of gastrin-producing cells (G-cells) after truncal vagotomy in a rat model. The circulating gastrin levels were markedly elevated from the 1st day after vagotomy and the number of G-cells with positive immunoreaction for G17 and G34(1-15) was significantly increased in the vagotomized group. On the 3rd day after vagotomy, the G-cells showed conspicuous ultrastructural changes characterized by hypertrophy of the Golgi complexes and increased numbers of secretory granules. The GRP-positive nerve fibers formed a fine network in the gastric wall and were densely distributed in the oxyntic mucosa close to the blood vessels and showing varicosities composed of either small clear or GRP-positive large vesicles containing an electron-dense core. In the oxyntic mucosa of the vagotomized rats, axonal swelling of the nerves occurred on the 3rd day, and a depletion of GRP immunoreactivity was evidenced by a markedly decreased number of large-cored vesicles on the 7th day, when the serum GRP levels were also found to be markedly elevated. These findings indicate that the alteration in gastric nerve fibers containing GRP after truncal vagotomy may be related to hypergastrinemia and antral G-cell hyperplasia in the rat gastric mucosa.

Animals↗
PubMed1995

Dinoflagellate Alexandrium tamarense as the source of paralytic shellfish poison (PSP) contained in bivalves from Hiroshima Bay, Hiroshima Prefecture, Japan.

In April 1993, a phytoplankton dinoflagellate was isolated from Hiroshima Bay, Hiroshima Prefecture, Japan, and unambiguously identified as Alexandrium tamarense on the basis of the morphological characteristics. The dinoflagellates, cultures in modified SW-2 medium at 15 degrees C for 15 days, showed a specific toxicity of 30.7 x 10-6 MU/cell. HPLC analysis demonstrated that the toxin was composed mainly of gonyautoxin-4 (GTX4) and protogonyautoxin-2 (PX2 or GTX8)(27.6 and 37.0 mole%, respectively). Total toxin concentration of this strain was 39.5 fmole/cell. Short-necked clams, mussels, and oysters contaminated by the dinoflagellate showed a more complicated composition, with GTX1 as the major component (61.8 mole% for short-necked clams, 60.5 mole% for mussels, 42.5 mole% for oysters), and PX2 was only present in trace amounts.

Animals↗
PubMed1995

Microflora and tetrodotoxin-producing bacteria in a gastropod, Niotha clathrata.

Shellfish (Niotha clathrata) were collected in both July and November from three locations in Taiwan (Pingtung, Kaohsiung and Chiai Prefecture) and assayed for anatomical distribution of tetrodotoxin (TTX) and aerobic heterotrophic bacteria. Pingtung specimens showed higher toxicity than those from Kaohsiung and Chiai, and did not show much seasonal variation. At each site, the total aerobic bacterial counts in November samples were higher than in July. The predominant genera were Vibrio, Pseudomonas, Pasteurella, Aeromonas and Plesiomonas. Vibrio comprised more than 35% of the genera, with V. alginolyticus as the major species. The viable counts of Vibrio species were higher in November than in July. However, the results did not suggest any relationship between the total count or viable count and the toxicity of the shellfish. HPLC, UV and gas chromatographic-mass spectrometric analyses demonstrated that some of the bacteria isolated, such as V. alginolyticus, V. parahaemolyticus, Pseudomonas spp. Plesiomonas sp. and Aeromonas sp., produced TTX and/or related substances.

Animals↗
PubMed1995

Effects of insulin-like growth factor-I, estrogen, glucocorticoid, and transferrin on the mRNA contents of ovalbumin and conalbumin in primary cultures of quail (Coturnix coturnix japonica) oviduct cells.

The effects of estrogen, dexamethasone, insulin-like growth factor-I (IGF-I), and transferrin on the messenger RNA (mRNA) contents of ovalbumin and conalbumin in primary cultures of quail oviduct cells were investigated. In the absence of one of the above hormones or factors, a decrease in ovalbumin mRNA was prominent. In particular, removal of IGF-I and transferrin caused a significant effect. Studies using a combination of estrogen, dexamethasone, IGF-I and transferrin indicated that IGF-I cooperates with estrogen or dexamethasone and transferrin works with dexamethasone. Specifically, IGF-I enhanced ovalbumin synthesis or increased cellular ovalbumin mRNA content depending on its concentration in the medium in the presence of estrogen. However, the effects of estrogen, dexamethasone, IGF-I, and transferrin were not similarly observed with conalbumin mRNA. These results show that ovalbumin synthesis is controlled by estrogen or glucocorticoid with IGF-I or transferrin and that cellular ovalbumin mRNA content is also regulated by these hormones or transferrin. In contrast, conalbumin synthesis and cellular content of conalbumin mRNA are not affected by these hormones under the conditions of the present study.

Animals↗
PubMed1995

Metabolism of clomipramine in a Japanese psychiatric population: hydroxylation, desmethylation, and glucuronidation.

We measured the concentrations of clomipramine and its metabolites, N-desmethylclomipramine, 8-hydroxy-N-desmethylclomipramine, 8-hydroxyclomipramine by high-performance liquid chromatography in 108 Japanese psychiatric patients receiving clomipramine hydrochloride PO. The concentrations of the glucuronide conjugates of 8-hydroxyclomipramine and 8-hydroxy-N-desmethylclomipramine were assayed via enzymatic hydrolysis. Although there were large interindividual variations of concentrations of parent, intermediate metabolic compounds, and glucuronide conjugates, significant positive correlations were observed between these drug concentrations and daily doses of clomipramine hydrochloride (mg/kg body weight). Although the metabolic ratios for desmethylation, hydroxylation, and glucuronidation that were calculated from steady-state drug concentrations varied substantially with 36-, 14-, and 28-fold interindividual variations, respectively, apparent poor desmethylators, poor hydroxylators, or poor glucuronidators were not found.

Adolescent↗
PubMed1995

Activation of Na(+)-H+ antiporter (NHE-1) gene expression during growth, hypertrophy and proliferation of the rabbit cardiovascular system.

The Na(+)-H+ antiporter is a unique transmembrane protein with multiple roles in cellular functions through intracellular alkalization. It participates in the regulation of intracellular pH, cell volume and intracellular signalling in response to various mitogenic stimuli. To clarify its role as a subcellular signal in cardiovascular remodeling like vascular hyperplasia or cardiac hypertrophy, we determined mRNA levels of the Na(+)-H+ antiporter isoform, NHE-1, in vascular smooth muscles and pressure-overloaded hearts in rabbits. The NHE-1 mRNA levels in rabbit aortas and hearts were developmentally regulated with high levels at embryonic and neonatal stages than in adults. In primary-cultured smooth muscle cells (SMC), the mRNA levels were increased during exponential growth, but decreased to initial levels at confluency. Growth of a mutant SMC line, C5, which is deficient in Na(+)-H+ antiporter activity, was markedly reduced in bicarbonate-free medium. However, when the activity was restored by transfecting cells with a full-length NHE-1 cDNA in an expression vector, the growth rate of C5 was accelerated again. After balloon injury to the vascular wall, the NHE-1 mRNA levels of the injured arteries were also increased, suggesting that Na(+)-H+ antiporter contributes to the network of the growth promoting systems in smooth muscle cells in vivo. Pressure-overload on the ventricle increased the NHE-1 mRNA levels in hearts approximately two-fold of sham-operated rabbits after 3 days and remained for at least two weeks (P < 0.05). We further demonstrated that 3-methylsulfonyl-4-piperidino-benzoyl guanidine mesylate (Hoe 694), a potent antagonist of Na(+)-H+ antiporter, partially inhibited stretch-induced activation of mitogen-activated kinase (MAP kinase) in the cultured cardiomyocytes. From these results, we conclude that activation of the Na(+)-H+ antiporter and its gene expression is involved in molecular mechanisms of both cardiac hypertrophy and vascular smooth muscle cell proliferation, indicating a potential target in developing new therapeutics for cardiovascular diseases.

Aging↗