Search PubMed⌕ Search

Biomedical subjects

S Ohta

Publications and source records attributed to S Ohta.

At least 721 records · Page 40Linked to original sources
PubMed1988

Site-directed mutagenesis of stable adenosine triphosphate synthase.

Evidence was obtained that four ionizable residues in the alpha and beta subunits of thermophilic ATP synthase (TF0F1), corresponding to Lys-21 and Asp-119 in the MgATP binding segments of adenylate kinase, are essential for the normal catalytic activity. TF0F1 was used because it is the only ATP synthase whose alpha-, beta- and gamma-subunits can be reassembled into an active complex in the absence of both ATP and Mg. Lys-164 and Asp-252 of its beta-subunit were modified to isoleucine and asparagine, respectively, by site-directed mutagenesis using a multifunctional plasmid, and these genes were over-expressed in Escherichia coli. The resulting beta I164 and beta N252 subunits were both noncatalytic after re-assembly into the alpha beta gamma-complex, even though both subunits bound significant amounts of ADP. When Lys-175 and Asp-261 of the alpha-subunit were similarly replaced by isoleucine and asparagine, respectively, the resulting alpha I175 subunit reassembled weakly into an oligomer, while the alpha N261 subunit showed an increased dissociation constant for ADP and was reconstituted into an alpha beta gamma-complex that showed no inter-subunit cooperativity.

Adenosine Diphosphate↗
PubMed1988

Presence of tetrahydroisoquinoline and 1-methyl-tetrahydro-isoquinoline in foods: compounds related to Parkinson's disease.

This is the first report confirming the presence of 1,2,3,4-tetrahydroisoquinoline (TIQ) and 1-methyl-1,2,3,4-tetrahydroisoquinoline(1MeTIQ) in a number of foods with a high 2-phenylethylamine content. These compounds were determined by gas chromatography-mass spectrometry. This study also confirmed that 1MeTIQ and TIQ can cross the blood-brain barrier in rat. Thus, these compounds, suspected to have relation to parkinson's disease, may accumulate in the brain from food sources.

Animals↗
PubMed1988

Free radical reaction and biological defense mechanism in the pathogenesis of prolonged vasospasm in experimental subarachnoid hemorrhage.

The relationship between free radical reactions and the defense mechanisms against them was investigated in the pathogenesis of prolonged vasospasm following experimental subarachnoid hemorrhage (SAH) in dogs. The concentration of lipid peroxides in the cerebro spinal fluid (CSF) increased markedly up to the eighth day following SAH; the concentrations also rose in the arterial wall (p less than 0.01) and the gray matter of the temporal lobe where the subarachnoid blood clots were (p less than 0.01). On the other hand, the activity of superoxide dismutase (SOD) decreased significantly up to the eighth day after SAH (p less than 0.01), and there was a gradual increase of glutathione peroxidase (GSH-px) in the CSF. In the arterial wall, there was a slight decrease in the activity of SOD, a significant decrease in the activity of GSH-px (p less than 0.01), and also a significant decrease in the concentration of glutathione (p less than 0.01) up to the eighth day following SAH. In conclusion, lipid peroxidation with insufficient biological defense mechanisms against it in the arterial wall, concomitant with that in the CSF, might take part in the genesis of prolonged vasospasm following SAH.

Animals↗
PubMed1988

Cloning and sequencing of cDNAs encoding alpha and beta subunits of human pyruvate dehydrogenase.

The cDNAs encoding fragments of the alpha and beta subunits (PDH alpha and PDH beta) of human pyruvate dehydrogenase (PDH, EC 1.2.4.1) were isolated from a HeLa cell cDNA library in the lambda gt11 expression vector by immunoscreening. Phage cDNA fragments were subsequently used to screen a human foreskin fibroblast cDNA library by colony hybridization. Nucleotide sequence analyses of the positive plasmid clones (pHPDA and pHPDB) revealed an insert of 1.36 kilobases (kb) for PDH alpha and one of 1.69 kb for PDH beta, respectively, allowing us to predict the complete amino acid sequences of the precursor and mature proteins of these two subunits. A putative leader sequence of 29 amino acid residues was identified in pHPDA, resulting in a precursor protein of 392 amino acid residues (Mr 43,414) and a mature protein of 363 residues (Mr 40,334). A similar leader sequence of 30 amino acid residues in pHPDB was also identified, resulting in a precursor protein of 359 amino acid residues (Mr 39,046) and a mature protein of 329 residues (Mr 35,911). The amino acid sequences of NH2-terminal regions of the two subunits of human PDH were highly homologous with those of mature porcine PDH. The amino acid sequences of phosphorylation sites determined in PDH alpha of bovine and porcine enzymes were also conserved in the human PDH alpha. Blot analysis of HeLa cell poly(A)+ RNA showed a single mRNA of 1.8 kb for PDH alpha and 1.7 kb for PDH beta, respectively. The precursor proteins of PDH alpha and PDH beta were detected by immunoprecipitation from an 35S-labeled cell-free translation system.

Amino Acid Sequence↗
PubMed1988

Nucleotide sequence of the gene coding for cytochrome oxidase subunit I from the thermophilic bacterium PS3.

The gene coding for cytochrome oxidase subunit I (COI) was isolated from a genomic DNA library of the thermophilic bacterium PS3 and sequenced. The N-terminal of the COI protein was also sequenced to verify the initiation site of the reading frame. The deduced amino acid sequence of COI protein is composed of 536 amino acid residues and its molecular mass is 59,510. The protein is clearly homologous to the corresponding subunit in the mitochondrial cytochrome oxidase and similarly appears to have 12 trans-membrane segments. The proposed ligands to two hemes (cytochrome aa3) and a copper atom (CuB) in this protein (Holm et al. (1987) EMBO J. 6, 2819-2823) are conserved in the sequence.

Amino Acid Sequence↗
PubMed1988

Roentgenographically occult bronchogenic carcinoma of non-polypoid type: histological patterns of longitudinal growth within the bronchus.

Microscopy of the serial block-sections of the entire bronchial tree of all the resected specimens of roentgenographically occult bronchogenic carcinoma revealed new findings with respect to the histological patterns of longitudinal growth within the bronchial wall. Twenty-seven lesions which were non-polypoid on gross appearance with longitudinal extension of 16 mm and above were classified into the following four categories. (A) In standard superficial extension, transmural invasion by carcinoma became shallower and the area involved on section became smaller gradually from the site of the origin of carcinoma to the proximal and distal ends. (B) In intraepithelial extension, carcinoma was confined within the epithelium throughout the bronchi involved except at and near the site of the origin at which it penetrated the basement membrane. (C) In lymphatic extension, carcinoma extended from the site of the origin to the proximal and distal ends in a dual pattern so that it extended longitudinally within the epithelium in parallel with an invasion into the lymphatic vessels in the lamina propria and submucosa. At the site of the origin carcinoma invaded down to the level of the submucosa or adventitia. (D) In massive extension, a massive invasion by carcinoma from the site of the origin to the proximal and distal ends, and a simultaneous invasion and destruction by carcinoma of the epithelium, basement membrane, lamina propria, submucosa, and of adventitia in places were demonstrated. There was no marked difference in bronchoscopic finding among (A), (B) and (C). The length of the lesion as estimated by histology was different from that observed at bronchoscopy. Bronchoscopic examination was not always successful in determining the line of resection precisely. Therefore it is indispensable to examine frozen sections and/or imprint specimens of the margin of resection.

Bronchi↗
PubMed1988

[Antigenicity study of carboplatin in guinea pigs and mice].

Carboplatin and carboplatin-ovalbumin mixture were examined for their antigenicity in Hartley guinea pigs as well as BALB/c and C3H/He mice in comparison with ovalbumin (OVA) and 2,4-dinitrochlorobenzene (DNCB)-OVA conjugate. The results obtained were as follows: 1. When guinea pigs were sensitized with carboplatin or carboplatin-OVA emulsified with Freund's complete adjuvant (FCA), these animals showed negative reactions in active systemic anaphylaxis (ASA), active cutaneous anaphylaxis (ACA), passive cutaneous anaphylaxis (PCA), passive hemagglutination (PHA) and Schultz-Dale test. 2. When mice were sensitized with carboplatin or carboplatin-OVA adsorbed to alum, these animals revealed a negative reaction in PCA using rats. 3. As positive controls, guinea pigs were sensitized with OVA or DNCB-OVA emulsified with FCA, and mice with OVA or DNCB-OVA adsorbed to alum. As a result, these animals disclosed positive reactions in ASA, ACA, PCA, PHA and Schultz-Dale test. As shown above, carboplatin was considered to possess neither antigenic nor haptenic properties. In addition, the dose levels of carboplatin employed in the present experiment were confirmed not to suppress immune reactions.

Anaphylaxis↗
PubMed1988

[Reproduction studies of carboplatin (I)--Intravenous administration to rats prior to and in the early stages of pregnancy].

Carboplatin, an oncostatic drug, was administered intravenously to male Crj: CD (Sprague-Dawley) rats for 63 days and to female rats of the same strain for 14 days prior to mating at dose levels of 1, 2 and 4 mg/kg/day. These animals were then mated under the consecutive administration of this drug and the females confirmed to be copulated were further dosed from day 0 through 7 of gestation. The summarized results obtained are as follows: 1. Carboplatin 2 mg/kg and higher suppressed body weight gains accompanied by the decreases in food and water consumption in male rats. Further, body weight gains were suppressed in female rats followed by the decreases in food consumption at the same dose levels. 2. Though there were no differences between dosed animals and controls regarding the organ weights, the incidence of necrosis of the tails around the injection site was increased in male rats at 4 mg/kg. 3. Carboplatin failed to affect the reproductive ability of both sexes. 4. As for fetuses, the mortality was elevated at 2 mg/kg and higher and the number of live fetuses reduced at 4 mg/kg, but the influences on prenatal development were not apparently observed for live fetuses even at the highest dose level. Based on these results, the no-effect dose level of carboplatin under the present experimental condition was estimated to be 1 mg/kg/day against parent rats of both sexes and their offspring.

Animals↗
PubMed1988

[Reproduction studies of carboplatin (II)--Intravenous administration to rats during the period of fetal organogenesis].

Carboplatin, an oncostatic drug, was administered intravenously to pregnant Crj: CD (Sprague-Dawley) rats from day 7 through 17 of gestation at dose levels of 1, 2 and 4 mg/kg/day. The summarized results obtained are as follows: 1. Carboplatin 4 mg/kg suppressed the maternal body weight gains from day 13 through 20 of gestation. 2. Uterine weights were reduced in F0 dams at term at carboplatin 4 mg/kg. 3. Carboplatin 4 mg/kg brought the inhibition of fetal growth accompanied by the lowered values in fetal weights, crown-rump distances and tail lengths. Furthermore, the elevated incidences of unossified 5th and 6th sternum , as well as retarded ossification of sacrococcygeal vertebrae were also noted in this dose level. 4. The birth rate was reduced in neonates (F1) at carboplatin 4 mg/kg. 5. Body weight gains in male F1 rats were suppressed at carboplatin 4 mg/kg from 4 to 8 weeks of age. 6. Carboplatin 4 mg/kg decreased the brain weights on an absolute basis in female F1 rats, but failed to affect their postnatal differentiations, early behavioral developments, learning ability, motor activity or emotional development. 7. Reproductive ability in F1 rats of both sexes were not affected by carboplatin. 8. Influences on prenatal development were not apparently observed for F2 fetuses derived from F1 rats whose dams had ever received carboplatin during the organogenetic period. Based on these results, the no-effect dose level of carboplatin under the present experimental condition was estimated to be 2 mg/kg/day against dams and their offspring.

Animals↗
PubMed1988

[Reproduction studies of carboplatin(III)--Intravenous administration to rats during the perinatal and lactation periods].

Carboplatin, an oncostatic drug, was administered intravenously to pregnant Crj: CD (Sprague-Dawley) rats from day 17 of gestation through day 21 of postpartum at dose levels of 1, 2 and 4 mg/kg/day. The summarized results obtained are as follows: 1. Maternal body weight gains were suppressed during the former part of the lactation period at carboplatin 2 mg/kg and higher. 2. Thymic weights were decreased and lung weights were increased in dams (F0) at carboplatin 2 mg/kg and higher. Further, ovarian weights were reduced in dams (F0) at carboplatin 4 mg/kg. 3. Carboplatin failed to affect the parturition of F0 dams. 4. Carboplatin did not affect the viability of newborns (F1), and postnatal differentiations, early behavioral developments, learning ability, motor activity or emotional development in F1 animals. 5. Carboplatin 4 mg/kg brought a suppression of pituitary weights after mating in F1 male rats and decreases of adrenal and genital organ weights at weaning in F1 female rats, but failed to affect their reproductive ability. 6. Influences on prenatal development were not apparently observed for F2 fetuses derived from F1 rats whose dams had ever received carboplatin during the perinatal and lactation periods. Based on these results, the no-effect dose level of carboplatin under the present experimental condition was estimated to be 1 mg/kg/day against dams and 2 mg/kg/day against their offspring.

Adrenal Glands↗
PubMed1988

Glidobactins A, B and C, new antitumor antibiotics. I. Production, isolation, chemical properties and biological activity.

New antitumor antibiotic glidobactins A, B and C were isolated from the cultured broth of a gliding bacterium, Polyangium brachysporum sp. nov. No. K481-B101. They are novel molecules carrying the common cyclic tripeptide nucleus substituted with different alpha, beta, gamma, delta-unsaturated fatty acids. Glidobactins exhibit broad inhibitory activity against fungi and yeasts, and prolong the life span of mice inoculated with P388 leukemia cells.

Animals↗
PubMed1988

[Synchronous double cancers in the ovary and kidney--a case report].

UNLABELLED: A first case of synchronous double cancers in the ovary and kidney is presented. The patient is a 37-year-old woman complaining of an abdominal mass. Histopathological findings showed a mucinous cystadenocarcinoma of the right ovary and a renal cell carcinoma, common type, clear cell subtype of the right kidney. A metastatic renal cell carcinoma was found on the pelvic peritoneum and characteristic renal cancer cells were identified in the ascitic fluid. ( EVALUATIONS: ovarian cancer, stage Ia; renal cancer, stage IV) The patient received postoperative chemotherapy and, after recovery, was discharged in a healthy condition. Her 11-month postoperative evaluation revealed no evidence of disease.

Adenocarcinoma, Mucinous↗