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Biomedical subjects

M Tsuda

Publications and source records attributed to M Tsuda.

At least 181 records · Page 10Linked to original sources
PubMed1997

Molecular cloning and expression of cDNA encoding human 3'-phosphoadenylylsulfate:galactosylceramide 3'-sulfotransferase.

We have isolated a cDNA clone encoding human 3'-phosphoadenylylsulfate:galactosylceramide 3'-sulfotransferase (EC 2.8.2.11). Degenerate oligonucleotides, based on amino acid sequence data for the purified enzyme, were used as primers to amplify fragments of the gene from human renal cancer cell cDNA by the polymerase chain reaction method. The amplified cDNA fragment was then used as probe to screen a human renal cancer cell cDNA library. The isolated cDNA clone contained an open reading frame encoding 423 amino acids including all of the peptides that were sequenced. The deduced amino acid sequence predicts a type II transmembrane topology and contains two potential N-glycosylation sites. There is no significant homology between this sequence and either the sulfotransferases cloned to date or other known proteins. Northern blot analysis demonstrated that a 1.9-kilobase mRNA was unique to renal cancer cells. When the cDNA was inserted into the expression vector pSVK3 and transfected into COS-1 cells, galactosylceramide sulfotransferase activity in the transfected cells increased from 8- to 16-fold over that of controls, and the enzyme product, sulfatide, was expressed on the transformed cells.

Amino Acid Sequence↗
PubMed1997

Role of the NMDA receptor complex in DMCM-induced seizure in mice.

We investigated the role of the NMDA receptor complex in DMCM (methyl-6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate)-induced seizures in mice. The seizure threshold of DMCM was evaluated using an i.v. infusion technique. Pretreatment with the non-competitive NMDA receptor antagonist MK-801 ((+)-5-methyl-10,11-dihydro-5H-dibenzo(a,d) cycloheptan-5,10-imine maleate) or phencyclidine (PCP) significantly increased the seizure threshold for DMCM. Furthermore, the seizure threshold of DMCM was increased by intracerebroventricular (i.c.v.), but not intrathecal (i.t.), pretreatment with MK-801. Moreover, 7-chlorokynurenic acid, a glycine site antagonist, also increased the seizure threshold of DMCM, whereas ifenprodil, a non-competitive polyamine site antagonist, did not. These findings indicate that the ion-channel binding site and the glycine binding site on the NMDA receptor complex in the brain may be involved in the expression of seizures induced by DMCM.

Animals↗
PubMed1997

Structural dynamics of water and the peptide backbone around the Schiff base associated with the light-activated process of octopus rhodopsin.

Difference Fourier transform infrared spectra were recorded for the formation of the photointermediates and isorhodopsin from octopus rhodopsin at low temperatures. Analysis was done for H bonding of the Schiff base, internal water molecules, and the peptide backbone. The imine hydrogen of the Schiff base was in the same H bonding state throughout the photointermediates and the unphotolyzed state. In contrast, H bonding of the hydrogen of the water molecule whose oxygen might be complexed with the imine hydrogen of the Schiff base was altered upon the formation of bathorhodopsin. The same water molecule was in a different H bonding state in the subsequent intermediates, lumirhodopsin and mesorhodopsin. These intermediates were also characterized by a decrease in the C = N bond order of the Schiff base as a reflection of distorted structure around the Schiff base. The polar N-H bond in these intermediates could be also ascribed to the Schiff base. Some changes in H bonding of water and the perturbation of the polyene chain in lumirhodopsin and mesorhodopsin were also observed in isorhodopsin. Acid metarhodopsin exhibited extensive changes in the H bonding states of the peptide backbone and internal water molecules. A large part of these changes was extinguished in alkaline metarhodopsin with the unprotonated Schiff base, suggesting interaction of the protonated Schiff base with the peptide backbone and intramembrane water molecules in acid metarhodopsin.

Animals↗
PubMed1997

CT and MR imaging of craniopharyngioma.

We reviewed imaging findings of CT and MR imaging in 20 cases of surgically confirmed craniopharyngioma in an attempt to determine their relation to patterns of tumor extent. The relationship between these patterns and the frequency of preoperative CT diagnosis and MR imaging diagnosis according to the surgical diagnosis were determined. The CT technique was superior to MR imaging in the detection of calcification. The MR imaging technique was superior to CT for determining tumor extent and provided valuable information about the relationships of the tumor to surrounding structures. Thus, CT and MR imaging have complementary roles in the diagnosis of craniopharyngiomas. In cases of possible craniopharyngioma, noncontrast sagittal T1-weighted images may enable the identification of the normal pituitary, possibly leading to the correct diagnosis.

Adolescent↗
PubMed1997

Light-induced protein conformational changes in the photolysis of octopus rhodopsin.

Light-induced protein conformational changes in the photolysis of octopus rhodopsin were measured with a highly sensitive time-resolved transient UV absorption spectrophotometer with nanosecond time resolution. A negative band around 280 nm in the lumirhodopsin minus rhodopsin spectra suggests that alteration of the environment of some of the tryptophan residues has taken place before the formation of lumirhodopsin. A small recovery of the absorbance at 280 nm was observed in the transformation of lumirhodopsin to mesorhodopsin. Kinetic parameters suggest that major conformational changes have taken place in the transformation of mesorhodopsin to acid metarhodopsin. In this transformation, drastic changes of amplitude and a shift of a difference absorption band around 280 nm take place, which suggest that some of the tryptophan residues of rhodopsin become exposed to a hydrophilic environment.

Animals↗
PubMed1997

Antinociceptive effect of buprenorphine in mu1-opioid receptor deficient CXBK mice.

The antinociceptive effect of buprenorphine was examined in mu1-opioid receptor-deficient CXBK mice. I.p. administration of buprenorphine at a dose of 3 mg/kg produced marked antinociception in the tail-flick test in C57BL/6 mice, a progenitor strain of CXBK mice. The antinociceptive effect of buprenorphine in C57BL/6 mice was antagonized by pretreatment with either beta-funaltrexamine (beta-FNA), a mu-opioid receptor antagonist, or naloxonazine (NXZ), a selective mu1-opioid receptor antagonist. The antinociceptive effect of buprenorphine (3 mg/kg, i.p.) in CXBK mice was significantly less than that in C57BL/6 mice. Neither beta-FNA nor NXZ reduced the antinociceptive effect of buprenorphine in CXBK mice. There was no significant difference between the buprenorphine-induced antinociceptive effect in CXBK mice and NXZ-treated C57BL/6 mice. Furthermore, neither naltrindole, a selective delta-opioid receptor antagonist, nor norbinaltorphimine, a selective kappa-opioid receptor antagonist, had a significant effect on the antinociceptive effects of buprenorphine in both CXBK and C57BL/6 mice. These results support our previous hypothesis that mu1- rather than mu2-, delta- or kappa-opioid receptors are involved in the antinociceptive effects of buprenorphine.

Animals↗
PubMed1997

Aggravation of DMCM-induced seizure by nitric oxide synthase inhibitors in mice.

The present study investigated the effects of nitric oxide synthase (NOS) inhibitors on the seizure threshold of DMCM in mice. The seizure threshold of DMCM was evaluated using an intravenous infusion technique. The threshold of DMCM was significantly decreased by pretreatment with N-nitro-L-arginine (NOARG; 8 mg/kg) and N-nitro-L-arginine methyl ester (L-NAME; 100 mg/kg), but not with D-NAME. Furthermore, these NOS inhibitors also decreased the threshold for pentylenetetrazole-induced seizure. However, the threshold for caffeine-induced seizure was not affected by NOARG. These results suggest that the endogenous NO system may play an important role in the expression of seizure by GABA(A) receptor inhibitory agents (DMCM and PTZ).

Animals↗
PubMed1997

Clinical and biochemical aspects of thiamine treatment for metabolic acidosis during total parenteral nutrition.

We encountered six cases of total parenteral nutrition (TPN)-associated lactic acidosis during the 6-y period of 1988-1993. The patients were characterized by severe disease of the digestive organs, minimal food intake before surgery, and postoperative TPN with no food intake and with no vitamin supplements. Within 4 wk of TPN, they developed hypotension (< or = 80/60 mmHg), Kussmaul's respiration, and clouding of consciousness, as well as abdominal pain not directly related to the underlying disease. Routine laboratory examinations revealed no acute aggravation in hepatic, renal, or pancreatic functions. Arterial blood gas analysis showed pH < or = 7.134 and base excess < or = -17.5 mmol/L. Additional laboratory examinations revealed serum lactate > or = 10.9 mmol/L, serum pyruvate > or = 159 mumol/L, and lactate/pyruvate ratio > or = 0.029. None of the patients responded to sodium bicarbonate or other conventional emergency treatments for shock and lactic acidosis. After the first case, we suspected that thiamine deficiency might be responsible for this pathologic condition, Serum thiamine was proved to be < or = 196 nmol/L in 5 patients. Thiamine replenishment at intravenous doses of 100 mg every 12 h resolved lactic acidosis and improved the clinical condition in 3 patients. This article includes a review of 11 relevant reports published from 1982-1992 and a discussion of the biochemical mechanism of onset of thiamine deficiency-associated lactic acidosis. We emphasize the needs (1) to supplement TPN with thiamine-containing vitamins for the patients whose food intake does not meet nutritional requirements; (2) to monitor the patients routinely measuring serum thiamine concentration and erythrocyte transketolase activity during TPN; and (3) to intravenously replenish using high-dose thiamine simultaneously with the manifestation of signs and symptoms of lactic acidosis.

Acidosis, Lactic↗
PubMed1997

Increased solubility of high-molecular-mass neurofilament subunit by suppression of dephosphorylation: its relation to axonal transport.

To investigate the role of phosphorylation in the turnover and transport of neurofilament (NF) proteins in vivo, we studied their solubility properties and axonal transport in the rat sciatic nerve using phosphatase inhibitors to minimize dephosphorylation during preparation. About 20% of the 200-kDa subunit (NF-H) in the axon was soluble in the 1% Triton-containing buffer under the present conditions, whereas this amount was less and more variable in the absence of phosphatase inhibitors. The 68-kDa subunit (NF-L) was exclusively insoluble and not affected by the inhibitors. Such selective solubilization of NF-H by phosphorylation differed significantly from the in vitro phosphorylation with cyclic AMP-dependent protein kinase, which resulted in NF disassembly. The carboxy-terminal phosphorylation state of NF-H probed with the phosphorylation-sensitive antibodies was also not directly related to solubility. The solubility of NF-H did not differ along the nerve. In contrast, the solubility of L-[35S]methionine-labeled, transported NF-H was lowest at the peak of radioactivity. Higher solubility at the leading edge, regardless of its location along the nerve, indicates that NF-H solubility is positively correlated with the rate of NF transport.

Animals↗
PubMed1997

A novel monoantennary complex-type sugar chain found in octopus rhodopsin: occurrence of the Gal beta1-->4Fuc group linked to the proximal N-acetylglucosamine residue of the trimannosyl core.

The N-linked sugar chains were liberated as oligosaccharides from octopus rhodopsin by hydrazinolysis. Most of the oligosaccharides were neutral, and separated into two major components by column chromatography using immobilized lectins and Bio-Gel P-4. Structural analysis of the one major component by sequential exoglycosidase digestion, chemical fragmentation in combination with methylation analysis revealed that it is a nonasaccharide; Man alpha1-->6(Gal beta1-->3GlcNAc beta1-->2Man alpha1-->3)Man beta1--> 4GlcNAc beta1-->4(Gal beta1-->4Fuc alpha1-->6)GlcNAc. This structure is quite unique in that a novel galactosylated fucose residue is attached to the reducing terminal N-acetylglucosamine residue.

Acetylglucosamine↗
PubMed1997

Isolation and characterization of an Escherichia coli mutant lacking the major serine transporter, and cloning of a serine transporter gene.

L-Serine as well as L-valine inhibits the growth of Escherichia coli cells, and L-isoleucine releases this growth inhibition. We isolated an E. coli mutant (designated as WAT9) that was able to grow on lactate (or glucose) as a carbon source even in the presence of L-serine, the parent not being able to. Cells of WAT9 were not able to grow on L-serine as a carbon source even if L-isoleucine was present in the culture medium, while the parental cells grew. This mutant was shown to lack the principal L-serine transporter in E. coli, the Na+/ serine symporter. This mutant is useful for analysis of the role(s) of the Na+/serine symporter in cell physiology and as a host for the cloning of L-serine transporter gene(s). In fact, we cloned a gene encoding a serine transporter from chromosomal DNA of E. coli using WAT9 as the host. The gene enabled the mutant cells to grow on L-serine. Transport activity for L-serine was restored in the mutant cells harboring a plasmid carrying the gene. We partially sequenced the gene and found that it was the tdcC gene. We showed that TdcC is an H+/serine symporter.

Amino Acid Transport Systems↗
PubMed1997

Whole-plant hydraulic resistance and vulnerability segmentation in Acer saccharinum.

Hydraulic properties were studied in Acer saccharinum L., a riparian species that also grows well on a dry soil when transplanted. Hydraulic resistances were measured by two independent techniques: a new high-pressure flowmeter (HPFM) method and a conventional evaporative flux (EF) method. Vulnerability to cavitation was also investigated on petioles, stems and roots using a hydraulic conductivity technique. Vulnerability segmentation was found, i.e., roots, stems and petioles had different vulnerabilities to xylem dysfunction. Petioles were most vulnerable with 50% loss of hydraulic conductivity at -0.5 MPa, roots were least vulnerable (50% loss at -2.2 MPa) and stems were intermediate in vulnerability. The HPFM and the EF methods gave comparable results, except that the EF method gave a significantly higher value for resistance across petioles plus leaves. Native embolism was high enough to explain the discrepancy in resistance across petioles plus leaves between the HPFM and the EF methods, indicating that the HPFM estimates the minimum (potential) hydraulic resistance of plants. Whole-plant hydraulic resistance of A. saccharinum was low compared to resistances of other temperate species. The hydraulic characteristics of A. saccharinum were consistent with adaptation to its typical environment: low whole-plant resistance assures high transpiration rates in the presence of sufficient water, and vulnerability segmentation provides the ability to survive during droughts through shedding of expendable organs.

Journal Article↗
PubMed1997

Identification of two palmitoyl groups in octopus rhodopsin.

We determined the structure and site of fatty acid incorporated in octopus rhodopsin using a combination of fluorescence label and enzymatic cleavage methods in conjunction with fast-atom bombardment (FAB) mass spectrometry. A single peptide containing two adjacent cysteines, Cys337 and Cys338, was successfully isolated using the fluorescence from a dye conjugated to Cys345. The FAB mass spectrometric analysis of the peptide (323Phe-340Phe) revealed that two palmitoyl groups are linked to Cys337 and Cys338 via thioester bonds in octopus rhodopsin as in bovine rhodopsin.

Amino Acid Sequence↗
PubMed1997

A resonance Raman study of the C=C stretch modes in bovine and octopus visual pigments with isotopically labeled retinal chromophores.

Previous resonance Raman spectroscopic studies of bovine and octopus rhodopsin and bathorhodopsin in the C-C stretch fingerprint region have shown drastically different spectral patterns, which suggest different chromophore-protein interactions. We have extended our resonance Raman studies of bovine and octopus pigments to the C=C stretch region in order to reveal a more detailed picture about the difference in retinal-protein interactions between these two pigments. The C=C stretch motions of the protonated retinal Schiff base are strongly coupled to form highly delocalized ethylenic modes located in the 1500 to 1650 cm-1 spectral region. In order to decouple these vibrations, a series of 11,12-D2-labeled retinals, with additional 13C labeling at C8, C10, C11 and C14, respectively, are used to determine the difference of specific C=C stretch modes between bovine and octopus pigments. Our results show that the C9=C10 and C13=C14 stretch mode are about 20 cm-1 lower in the Raman spectrum of octopus bathorhodopsin than in bovine bathorhodopsin, while the other C=C stretch modes in these two bathorhodopsins are similar. In contrast, only the C9=C10 stretch mode in octopus rhodopsin is about 10 cm-1 lower than in bovine rhodopsin, while other C=C stretches are similar.

Animals↗
PubMed1997

Aspergillus fumigatus Asp fI DNA is prevalent in sputum from patients with coal workers' pneumoconiosis.

Aspergillus fumigatus is an apportunistic nosocomial pathogen in immunosuppressed patients or in the lesion where the local defense mechanism was impaired. Patients with pneumoconiosis are known to be susceptible to chronic necrotizing pulmonary aspergillosis. Therefore, we hypothesized that A. fumigatus might be prevalent in sputum from patients with coal workers' pneumoconiosis, and also that asthmatic symptoms in patients with coal workers' pneumoconiosis may be associated with the presence of A. fumigatus. We tested for A. fumigatus in the sputum from patients with coal workers' pneumoconiosis by nested polymerase chain reaction amplification of the Asp fI gene. Sequences specific for this gene were detectable in 5 of 11 (45.5%) patients with coal workers' pneumoconiosis with asthmatic symptoms (group A), 5 of 10 (50.0%) patients with coal workers' pneumoconiosis without asthmatic symptoms (group B) and only 1 of 9 (11.1%) patients with chronic airflow obstruction without pneumoconiosis (group C). The frequency of the Asp fI gene detection was significantly higher in groups A and B than in group C (p < 0.05). The prevalence of A. fumigatus was not associated with asthmatic symptoms. These results demonstrated that A. fumigatus was prevalent in patients with coal workers' pneumoconiosis. We speculate that colonization with A. fumigatus may be associated with this disease.

Aged↗
PubMed1997

Na+(Li+)/H+ antiporter in Pseudomonas aeruginosa and effect of Li+ on cell growth.

Everted membrane vesicles were prepared from cells of Pseudomonas aeruginosa, and cation/H+ antiport was measured. We observed activities of Na+/H+ antiport, Li+/H+ antiport and K+/H+ antiport. Judging from the competition pattern, it seems that there are at least two types of antiporter, a Na+(Li+)/H+ antiporter and a K+/H+ antiporter. Na+ was a good substrate for the Na+(Li+)/H+ system, whereas Li+ was a poor substrate. Although the K(m) value for Na+ (or Li+) was similar to those in Escherichia coli Na+/H+ antiporters, the Vmax value for Na+ (or Li+) was much smaller in the P. aeruginosa antiporter than in the E. coli antiporters. Growth of P. aeruginosa was strongly inhibited by 0.4 M LiCl, but not by NaCl or KCl.

Amiloride↗
PubMed1997

Brasiliquinones A, B and C, new benz[alpha]anthraquinone antibiotics from Nocardia brasiliensis. I. Producing strain, isolation and biological activities of the antibiotics.

New benz[alpha]anthraquinone antibiotics (brasiliquinones A, B and C) with an ethyl group at C-3 were isolated. The producer was identified as Nocardia brasiliensis. The antibiotics were active against Gram-positive bacteria including Mycobacterium sp., but not active against Gram-negative bacteria or fungi. They were also active against multiple drug-resistant P388/ADR tumor cells.

Animals↗