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Biomedical subjects

M Tsuda

Publications and source records attributed to M Tsuda.

At least 343 records · Page 19Linked to original sources
PubMed1992

Binding sites for pituitary adenylate cyclase activating polypeptide (PACAP): comparison with vasoactive intestinal polypeptide (VIP) binding site localization in rat brain sections.

Pituitary adenylate cyclase activating polypeptide (PACAP) is structurally similar to vasoactive intestinal polypeptide (VIP). We investigated the characteristics and topographical distribution of [125I]PACAP binding sites compared with those of [125I]VIP binding sites in the rat brain. Radiolabeled PACAP and VIP showed highly specific binding to sections at the level of the dorsal hippocampus. The specific binding of [125I]PACAP was 10 times higher than that of [125I]VIP in hippocampal sections. [125I]PACAP binding was scarcely displaced by unlabeled VIP, while [125I]VIP binding was effectively displaced by unlabeled PACAP. Therefore, PACAP binding sites may reflect both PACAP specific binding sites and VIP/PACAP binding sites. However, the amount of VIP/PACAP binding sites was negligibly low. Autoradiography revealed that [125I]PACAP binding sites were dense in the piriform cortex, diagonal band, accumbens nucleus, anterior part of the striatum, hippocampal formation, habenular nucleus, lateral hypothalamic area, superior colliculus and dorsal raphe nucleus. Moderate to high labeling was observed in the medial septal nucleus, olfactory tubercle, caudal part of the striatum, most parts of the thalamus, supraoptic and periventricular hypothalamic nuclei, central gray, substantia nigra pars compacta, locus coeruleus, pontine reticular nucleus and cerebellum. Distribution pattern was remarkably different from that of [125I]VIP binding sites in the hippocampal formation, lateral hypothalamic area, substantia nigra pars compacta, pontine reticular nucleus and cerebellum. The present results suggest that PACAP may have a physiological role in the regulation of the central nervous system.

Animals↗
PubMed1992

Pituitary adenylate cyclase activating polypeptide provokes cultured rat chromaffin cells to secrete adrenaline.

Pituitary adenylate cyclase activating polypeptide (PACAP) provoked the rat chromaffin cells to secrete adrenaline. Within 20 min, the amount of adrenaline secreted by PACAP (10(-8) M) was as much as that caused by acetylcholine (10(-4) M). PACAP, but not acetylcholine, induced a long-term (over 120 min) increase in secretion of adrenaline. PACAP also activated adenylate cyclase and elevated cytosolic Ca2+ concentration. Furthermore, we found immunoreactive PACAP and PACAP binding sites in the rat adrenal medulla. These results suggest that PACAP has an important role in stimulating secretion of adrenaline in the adrenal medulla.

Adrenal Cortex↗
PubMed1992

Alpha-1-antichymotrypsin variant detected by PCR-single strand conformation polymorphism (PCR-SSCP) and direct sequencing.

A new mutant alpha-1-antichymotrypsin (variant ACT) was found by polymerase chain reaction single strand conformation polymorphism and direct sequencing. In this variant ACT, two bases (AA) were deleted from codon 391. This resulted in a different amino acid sequence downstream of the deletion point, elongating the peptide chain by 10 amino acids.

Amino Acid Sequence↗
PubMed1992

Cloning and sequencing of the melB gene encoding the melibiose permease of Salmonella typhimurium LT2.

The nucleotide sequence of the melB gene coding for the Na+ (Li+)/melibiose symporter of Salmonella typhimurium LT2 was determined, and its amino acid sequence was deduced. It consists of 1428 bp, corresponding to a protein of 476 amino acid residues (calculated molecular weight 52,800). The amino acid sequence is homologous to that of the melibiose permease of Escherichia coli K12, with 85% identical residues. All, except one, of the amino acid residues that have been reported to be important for cation or substrate recognition in the melibiose permease of E. coli are conserved in the melibiose permease of S. typhimurium. In addition, part of the sequence resembles the lactose permease of Streptococcus thermophilus, the animal glucose transporter (GLUT1), the plasmid-coded raffinose permease (RafB), and the NADH-ubiquinone oxidoreductase chain 4 (Nuo4) of Aspergillus amstelodami.

Amino Acid Sequence↗
PubMed1992

The characteristic negative Cotton effect of ganglioside lactones observed by circular dichroism spectrometry.

Circular dichroism spectrometry was applied to gangliosides and their lactones and revealed that the lactones have a characteristic strong negative Cotton effect around 235 nm. Four monolactones and two dilactones, which were formed from GM4, GD3, and GD1b, gave molar ellipticities at the wavelength in magnitude of 10(4), while their parent gangliosides, along with other gangliosides such as GM3, GM1, GD1a, GT1b, and GQ1b, showed no distinct feature. Two ganglioside esters, GM4-methyl ester and O-Ac-GT1b did not show the Cotton effect. The molar ellipticities had an additivity with respect to the number of lactone rings. The Cotton effect was attributed to the carbonyl group on the lactone ring.

Animals↗
PubMed1992

Studies on endogenous formation of N-nitroso compounds in the guinea pig supplemented with proline or thioproline and sodium nitrate.

The endogenous formation of N-nitrosoproline (NPRO) and N-nitrosothioproline (NTPRO, N-nitrosothiazolidine-4-carboxylic acid) was studied by monitoring their excretion in the urine of guinea pigs given oral doses of 10 mg proline or thioproline after supplementation with 34 mg (0.4 mmol) sodium nitrate. In order to estimate the conversion of nitrate to nitrite, the animals were also supplemented with 3.5 mg (0.05 mmol) sodium nitrite instead of sodium nitrate. In animals fed commercial diets, the excretion of NPRO and NTPRO under supplementation with sodium nitrate was 2.0 micrograms and 28.7 micrograms/animal/day, respectively, whereas the excretion under supplementation with sodium nitrite was 0.7 micrograms and 13.3 micrograms/animal/day, respectively. The higher excretion of NTPRO than NPRO in each case shows that thioproline is more effective for nitrite trapping than proline. The animals supplemented with nitrate excreted more than twice the amounts of NPRO or NTPRO than those supplemented with nitrite. It is assumed, therefore, that more than 0.1 mmol nitrate is reduced to nitrite and takes part in the endogenous nitrosation of the guinea pig. When various concentrations of L-ascorbic acid (AsA), known to inhibit the formation of N-nitroso compounds, were also administered orally to animals immediately after supplementation with sodium nitrate, the NPRO excretion decreased with increasing AsA concentration. These data indicate that the guinea pig, which is unable to synthesize AsA as well as humans, may be an appropriate animal model for evaluation of the endogenous nitrosation ability of humans ingesting nitrate.

Animals↗
PubMed1992

Stimulation of cultured cerebellar granule cells via glutamate receptors induces TRE- and CRE-binding activities mediated by common DNA-binding complexes.

By use of nuclear mini-extracts prepared from cultured cerebellar granule cells in a gel-mobility assay, exogenous N-methyl-D-aspartate (NMDA) or kainate was shown to increase both 12-O-tetradecanoylphorbol 13-acetate-responsive element (TRE)- and cyclic AMP-responsive element (CRE)-binding activity. These increases were specifically prevented by the NMDA receptor antagonist D,L-2-amino-5-phosphonovalerate and the non-NMDA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione, respectively. The increase of TRE-binding activity was dependent on de novo protein synthesis, and its inductions by both NMDA and kainate required extracellular Ca2+. TRE-binding activity was competitively inhibited by the CRE, and vice versa, showing higher DNA-binding affinity to the CRE than to the TRE. A proteolytic clipping bandshift assay demonstrated that the increase in CRE-binding activity could be mediated by the TRE-binding activity. Thus, the TRE-binding activity cross-binding to the CRE could be activated by NMDA or kainate stimulation. The involvement of c-Fos or Fos-related proteins in the TRE- and CRE-binding complexes was shown by a supershift gel-mobility assay using anti-c-Fos antiserum.

2-Amino-5-phosphonovalerate↗
PubMed1992

Interaction of rhodopsin, G-protein and kinase in octopus photoreceptors.

Light induced phosphorylation of octopus rhodopsin was greatly enhanced by guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S), suggesting that the kinases are involved in regulating interaction between rhodopsin and G-protein. We determined phosphorylated peptides of octopus rhodopsin in the presence or absence of GTP gamma S. Possible phosphorylation sites for octopus rhodopsin enhanced by GTP gamma S were Thr329, Thr330 and/or Thr336, which suggest that the G-protein associates with cytoplasmic loops including C-terminal peptide in the seventh helix of octopus rhodopsin.

Amino Acid Sequence↗
PubMed1992

Catabolite repression of the H(+)-translocating ATPase in Vibrio parahaemolyticus.

Cells of Vibrio parahaemolyticus grown in the presence of glucose showed reduced (by about 40%) oxidative phosphorylation. With this observation as a basis, we examined the effect of glucose on the level of H(+)-translocating ATPase. The addition of glucose to the growth medium reduced the specific activity and the amount of the H(+)-translocating ATPase in membrane vesicles of V. parahaemolyticus. These reductions were reversed by adding cyclic AMP (cAMP) to the growth medium. We cloned some parts of the unc genes encoding subunits of the H(+)-translocating ATPase of V. parahaemolyticus by means of the polymerase chain reaction. Using an amplified DNA fragment, we carried out Northern (RNA) blot analysis and found that glucose reduced the mRNA level of the H(+)-translocating ATPase gene by about 40% and that cAMP restored it. We determined the DNA sequence of the unc promoter region of V. parahaemolyticus and found a consensus sequence for the cAMP receptor protein-cAMP-binding site. Such a sequence was also found in the promoter region of the unc operon of Vibrio alginolyticus but not in its counterpart in Escherichia coli. We observed a similar reduction in the level of ATPase due to glucose in V. alginolyticus. In E. coli, however, reductions in the ATPase and the unc mRNA levels were not observed. Thus, the unc operon is controlled by cAMP-regulated catabolite repression in V. parahaemolyticus and V. alginolyticus but not in E. coli. Catabolite repression of the unc operon in V. parahaemolyticus is not severe.

Base Sequence↗
PubMed1992

Properties of recombinant cells capable of growing on serine without NhaB Na+/H+ antiporter in Escherichia coli.

Escherichia coli HIT-1 has a mutation in the Na+/H+ antiporter gene, nhaB (P. Thelen, T. Tsuchiya, and E. B. Goldberg, J. Bacteriol. 173:6553-6557, 1991). This strain is not able to utilize serine as a carbon source (T. Ishikawa, H. Hama, M. Tsuda, and T. Tsuchiya, J. Biol. Chem. 262:7443-7446, 1987), because an active NhaB is required to maintain the electrochemical potential of Na+, which drives serine transport via the Na+/serine carrier, the major transport system for serine. We isolated recombinant cells from a cross between strains HIT-1 and Hfr, and these cells were able to grow on serine even though the NhaB Na+/H+ antiporter of the recombinant cells was still defective. We found that the activity of the H+/serine cotransport system, one of the minor serine transport systems in E. coli, was elevated in the recombinant cells. H+/serine cotransport activity was induced by leucine in the recombinant cells more strongly than in strain HIT-1. A kinetic analysis showed that the Vmax, but not the Km, of the transport system was much higher in the recombinant cells than in strain HIT-1 cells.

Biological Transport↗
PubMed1992

Preferential utilization of glucose over melibiose, and vice versa, in a pts mutant of Salmonella typhimurium.

Preferential utilization of glucose and melibiose was investigated in wild type cells and in pts mutant (ptsI-leaky) cells of Salmonella typhimurium. A typical diauxic growth and preferential utilization of glucose over melibiose were observed in wild type cells when these two sugars were added as carbon source. Similar results were obtained with a pts mutant (SB1476) although utilization of glucose was slow. When cyclic adenosine 3',5'-monophosphate (cAMP) was added to the culture medium to release the catabolite repression, preferential utilization of glucose was still observed in wild type cells. With glucose-induced mutant cells, preferential utilization of glucose was observed in the presence of cAMP. Gradual utilization of melibiose took place when glucose concentration in the medium decreased. Surprisingly, preferential utilization of melibiose over glucose was observed with melibiose-induced and glucose-uninduced mutant cells in the presence of cAMP.

Cell Division↗
PubMed1992

[Genetical responses of neuronal cells to synaptic transmission].

To understand the cellular mechanisms that lead to the generation of synaptic plasticity of neuronal cells, it is important to understand the intracellular responses of neuronal cells stimulated via synaptic transmission. The stimulation of mouse cerebellar granule cells via NMDA (N-methyl-D-aspartate) receptors caused an increase in deoxyribonucleic acid (DNA)-binding activities to TRE (12-O-tetradecanoylphorbol-13-acetate-responsive element) and CRE (adenosine 3',5'-cyclic monophosphate-responsive element) motifs, depending upon the presence of extracellular Ca2+. The increases in TRE- and CRE-binding activities were also detected with the stimulation of non-NMDA receptors by kainate. The increases in TRE- and CRE-binding activities were both mediated by the same DNA-binding complexes whose binding affinity to CRE was about three-fold higher than that to TRE. On the other hand, the stimulation of neuroblastoma x glioma hybrid NG108-15 via muscarinic acetylcholine receptors, alpha 2-adrenergic receptors and bradykinin receptors caused a rapid induction of zif/268. An additive effect on the induction of zif/268 was observed when the different stimuli were simultaneously added. Thus, it is extremely likely that signals transduced via synaptic transmission are transferred to the level of gene expression and evoke some events which might contribute to the generation of synaptic plasticity in neuronal cells. In addition, we have found that the direct injection of plasmid DNAs into mouse skeletal muscle with fructose, glucose or NaCl solution led to a long-term expression of the introduced gene in muscle cells.

Animals↗
PubMed1992

Syntheses of recombinant yellowtail and flounder growth hormones in Escherichia coli.

For syntheses of recombinant yellowtail and flounder growth hormones (r-yGH and r-fGH) in E. coli, expression plasmids were constructed. The expression level of r-yGH and r-fGH in the host cells were very high, reaching 15 and 8% of the total protein, respectively. These product proteins were accumulated in inclusion bodies in the cells. The recombinant hormones were isolated from the pellets ina glutathione reduction/oxidation buffer. The refolded hormones were further purified by DEAE-Toyopearl 650M chromatography to homogeneity. The purified r-yGH and r-fGH were composed of 188 and 174 amino acid residues, respectively, having amino-terminal sequences starting with methionine. The recombinant hormones had potent growth-promoting activities on juvenile rainbow trout Salmo gairdneri in a dose-dependent manner.

Animals↗
PubMed1992

Cross-sectional study with multiple measurements of biological markers for assessing stomach cancer risks at the population level.

A cross-sectional study to determine correlations between measurable biologic markers and mortality from stomach cancer was performed in various areas of Japan. Blood and urine were collected from randomly selected 40- to 49-year-old men and their spouses in four areas with different rates of mortality from stomach cancer. The samples were analyzed for levels of the micronutrients vitamins A, C, and E, beta-carotene, and lycopene in plasma and for levels of NaCl, nitrate, and N-nitrosamino acids (N-nitrosoproline, N-nitrosothioproline [NTPRO] and N-nitrosomethylthioproline [NMTPRO]) in 24-hr urine. A significant, strong correlation was found between the amount of salt excreted in urine and stomach cancer mortality in both men and women. Although the amounts of nitrate and of the three N-nitrosamino acids in 24-hr urine were not correlated with stomach cancer rates, the low excretion levels of NTPRO and NMTPRO in the lowest risk area for stomach cancer were noteworthy, regardless of the high level of nitrate excretion in the same area. This suggests a lesser degree of endogenous nitrosation in the body. No protective effect of micronutrients was observed in this correlation study; there was, however, a negative correlation between plasma lycopene level and stomach cancer mortality. Salt intake was thus confirmed to play an important role in the development of stomach cancer and is likely to be a rate-regulating factor in Japanese populations. N-Nitrosamino acids and lycopene may also be related to stomach cancer mortality.

Adult↗
PubMed1992

Effect of systemic L-arginine administration on hemodynamics and nitric oxide release in man.

The effects of L-arginine administration on systemic hemodynamics and plasma concentrations of neuro-endocrine hormones and amino acids were investigated in 10 normotensive healthy volunteers. Nitrite/nitrate in urine and cyclic guanosine monophosphate (c-GMP) in plasma were also measured as indicators of release of nitric oxide (NO). L-arginine administration (30 g/300 ml/30 min) caused hypotension (mean arterial pressure; 79.3 +/- 3.9 mmHg fell to 68.8 +/- 2.2 mmHg) with tachycardia (62.3 +/- 2.3 beats/min increased to 67.5 +/- 1.9 beats/min). The plasma concentration of L-arginine before administration was 98.8 +/- 8.2 mumol/l and increased to 7263 +/- 567 mumol/l 20 min after administration. Cardiac output also increased to 127.2 +/- 3.9% by L-arginine administration. Total peripheral resistance was calculated to fall to 65.9 +/- 2.0%. L-arginine administration slightly changed several hormones, but all values were within normal ranges. Nitrite/nitrate in urine increased 142.1 +/- 12.4% compared to the values before L-arginine administration. Plasma concentrations of c-GMP and L-citrulline, the by-product of NO from L-arginine, were also significantly increased by L-arginine administration. All our results provide evidence for the first time that systemically administered L-arginine releases NO in man.

Adult↗