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S Nishimura

Publications and source records attributed to S Nishimura.

At least 685 records · Page 38Linked to original sources
PubMed1987

Effect of 16,16-dimethyl prostaglandin E2 on gastric surface epithelial cell damage induced by 20% ethanol in rats.

Prostaglandins protect against the gross damage of gastric mucosa induced by 50-100% ethanol, but do not protect surface epithelial cells (SEC) from necrosis. Since this induced damage to SEC is so severe, we attempted to determine the effects of a prostaglandin on slightly induced SEC damage and gastric potential difference (PD) in response to low concentrations of ethanol. The necrotizing effects of graded concentrations of ethanol (10-50%) to SEC on the rat gastric mucosa were studied by scanning electron and light microscopy. Intragastric instillation of 20% ethanol (v/v, 1 ml/100 g body wt.) to pylorus-ligated rats for 10 min induced slight and reproducible SEC damage consisting mainly of the apical cell membrane erosion of SEC. Pretreatment with 16,16-dimethyl prostaglandin E2 (dmPGE2, 3 or 30 micrograms/kg, p.o. or s.c.) afforded protection of the SEC from 20% ethanol-induced damage. However, the cytoprotective effects of dmPGE2 were abolished when gastric contents were emptied prior to 20% ethanol instillation. Intragastric instillation of ethanol immediately reduced PD in a concentration-related manner. dmPGE2 (3 or 30 micrograms/kg, s.c.) had no effect on the reduction of gastric PD after 20% ethanol treatment and the recovery of reduced PD to normal levels. We conclude that dmPGE2 has no cytoprotective effect on 20% ethanol-induced SEC damage in rat gastric mucosa.

16,16-Dimethylprostaglandin E2↗
PubMed1987

The antitumor potency of oral tegafur against adenocarcinoma 755 in mice is markedly enhanced by oral (E)-5-(2-bromovinyl)-2'-deoxyuridine.

A significant inhibition of the growth of adenocarcinoma 755 tumors in BDF1 mice was effected by oral tegafur (FT) in combination with oral (E)-5-(2-bromovinyl)-2'-deoxyuridine (BVdUrd), at doses at which neither drug used alone had antitumor activity. The maximum inhibition of tumor growth (97%) was achieved by using a combination of 50 mg FT/kg with 10 mg BVdUrd/kg but, even at a dose as low as 1 mg BVdUrd/kg, the antitumor potency of FT was enhanced. The effect which BVdUrd has on the antitumor potency of FT is apparently due to inhibitory action by bromovinyluracil, the phosphorolytic product of BVdUrd, on the degradation of 5-fluorouracil, the oxidative product of FT, by dihydrothymine dehydrogenase.

Adenocarcinoma↗
PubMed1987

Monoclonal antibody highly sensitive for the detection of ras p21 in immunoblotting analysis.

Four murine monoclonal antibodies (NCC-RAS-001, -004, -005, -017) reactive with ras p21 were produced by using recombinant c-Ha-ras p21 as an immunogen. Among these antibodies, NCC-RAS-004 was extremely sensitive when used in immunoblotting analysis, facilitating semiquantitative detection of c-Ha-, c-Ki- and N-ras p21 in cell and tissue lysates. In cells carrying a point-mutationally activated ras, p21 with abnormal mobility upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis was clearly detected.

Antibodies, Monoclonal↗
PubMed1987

[Magnetic resonance imaging (MRI) of pituitary adenomas].

MRI of 20 patients, 17-82 years old, with pituitary adenomas confirmed histopathologically, and 30 normal patients without pituitary dysfunction were reviewed. The studies were performed with a 0.5 Tesla MR scanner with a slice thickness of 10 mm. Inversion recovery sequences were employed as T 1-weighted examination, with repetition time (TR) of 2100-2500 msec, an inversion time (TI) of 600 msec and an echo time (TE) of 40 msec. The T 2-weighted examination had a TR of 1800-2500 msec and a TE of 120 msec. T 1-weighted images were obtained in all cases and T 2-weighted images in 14 cases. Spin echo images with a TR of 600-1000 msec and a TE of 40 msec (SE 40/600-1000) were also obtained in 14 cases. On T 1-weighted images, 20 adenomas were classified into six groups, according to their signal intensities; marked low intensity (1), low intensity (1), isointensity (11), high intensity (3), marked high intensity (1) and mixed intensity (3). On T 2-weighted images, 14 adenomas were classified into five groups; low intensity (1), isointensity (2), high intensity (4), marked high intensity (6) and mixed intensity (1). On SE 40/600-1000 images, 14 adenomas were also classified into four groups; low intensity (8), high intensity (2) and mixed intensity (3). Two adenomas with recent intratumoral hemorrhage had marked high intensity on both T1 and T2-weighted images. SE 40/600-1000 images were useful in evaluating the size and the extent of the visual pathway was best appreciated on IR images. Comparison between normal and involved cavernous sinus by adenomas was made.

Adenoma↗
PubMed1987

[Two cases of glioblastoma involving the orbit and maxillary sinus].

Two cases of glioblastoma involving orbit and maxillary sinus are presented. Case 1: A 49-year-old male was admitted on May 20, 1982, with complaints of headache and impairment of memory. On July 27, 1982, operation was carried out. The tumor in the left temporal lobe was totally removed, and he subsequently received chemotherapy and irradiation. The postoperative course was uneventful. On Oct. 26, 1983, he was readmitted with complaints of disturbance of gait and memory. A CT scan revealed no local recurrence of the tumor but a diffusely enhanced mass in orbit and maxillary sinus. Reoperation was carried out on Nov. 10, 1983. No recurrence was seen at the original site where the first operation was done. The dura was intact so far as observed from inside and was protruding into the cavity from the side of the sphenoidal ridge. The tumor showed destructive growth to orbit and maxillary sinus. He died on May 20, 1984. The autopsy was refused. Case 2: A 33-year-old male was admitted on Oct. 24, 1981, with complaints of headache, vomiting and impairment of memory. A CT scan revealed a right temporal mass lesion. He was operated on three times, on Oct. 27, 1981, Feb. 23, 1984 and Sep. 6, 1984, respectively. He also received chemotherapy and irradiation. Finally, a CT scan revealed the recurrence of the tumor in the right frontal, temporal, parietal lobe and basal ganglia, and an invasion into orbit on a CT scan. He died on Nov. 26, 1984. We discussed the course of the extension of tumors and the reports in the literature were reviewed.

Adult↗
PubMed1986

15N-labeled tRNA. Identification of 4-thiouridine in Escherichia coli tRNASer1 and tRNATyr2 by 1H-15N two-dimensional NMR spectroscopy.

Uridine is uniquely conserved at position 8 in elongator tRNAs and binds to A14 to form a reversed Hoogsteen base pair which folds the dihydrouridine loop back into the core of the L-shaped molecule. On the basis of 1H NMR studies, Hurd and co-workers (Hurd, R. E., Robillard, G. T., and Reid, B. R. (1977) Biochemistry 16, 2095-2100) concluded that the interaction between positions 8 and 14 is absent in Escherichia coli tRNAs with only 3 base pairs in the dihydrouridine stem. We have taken advantage of the unique 15N chemical shift of N3 in thiouridine to identify 1H and 15N resonances for the imino units of S4U8 and s4U9 in E. coli tRNASer1 and tRNATyr2. Model studies with chloroform-soluble derivatives of uridine and 4-thiouridine show that the chemical shifts of the protons in the imino moieties move downfield from 7.9 to 14.4 ppm and from 9.1 to 15.7 ppm, respectively; whereas, the corresponding 15N chemical shifts move downfield from 157.5 to 162.5 ppm and from 175.5 to 180.1 ppm upon hydrogen bonding to 5'-O-acetyl-2',3'-isopropylidene adenosine. The large difference in 15N chemical shifts for U and s4U allows one to unambiguously identify s4U imino resonances by 15N NMR spectroscopy. E. coli tRNASer1 and tRNATyr2 were selectively enriched with 15N at N3 of all uridines and modified uridines. Two-dimensional 1H-15N chemical shift correlation NMR spectroscopy revealed that both tRNAs have resonances with 1H and 15N chemical shifts characteristic of s4UA pairs. The 1H shift is approximately 1 ppm upfield from the typical s4U8 resonance at 14.8 ppm, presumably as a result of local diamagnetic anisotropies. An additional s4U resonance with 1H and 15N shifts typical of interaction of a bound water or a sugar hydroxyl group with s4U9 was discovered in the spectrum of tRNATyr2. Our NMR results for tRNAs with 3-base pair dihydrouridine stems suggest that these molecules have an U8A14 tertiary interaction similar to that found in tRNAs with 4-base pair dihydrouridine stems.

Magnetic Resonance Spectroscopy↗
PubMed1986

Formation of 8-hydroxyguanine residues in cellular DNA exposed to the carcinogen 4-nitroquinoline 1-oxide.

8-Hydroxyguanine (8-OH-Gua) residues were formed in DNA of Ehrlich ascites cells exposed to the carcinogen 4-nitroquinoline 1-oxide. Formation of 8-OH-Gua was confirmed by chemical treatment of calf thymus DNA with the proximate metabolite of this carcinogen, 4-hydroxyaminoquinoline 1-oxide, together with seryl-adenosine monophosphate. The ratio of the rates of formations of 8-OH-Gua and the quinoline-bound adducts was about 0.2-0.3. A conceivable mechanism of formation of 8-OH-Gua is proposed.

4-Hydroxyaminoquinoline-1-oxide↗
PubMed1986

15N-labeled tRNA. Identification of dihydrouridine in Escherichia coli tRNAfMet, tRNALys, and tRNAPhe by 1H-15N two-dimensional NMR.

The N3 imino units of dihydrouridine were identified in samples of 15N-labeled Escherichia coli tRNAfMet, tRNALys, and tRNAPhe by 1H-15N two-dimensional NMR. The peaks for dihydrouridine had high field 1H (9.7-9.8 ppm) and 15N (147.8-149.5 ppm) chemical shifts. Assignments were made by 1H-15N chemical shift correlation based on values obtained in model studies with tri-O-benzoyl- and tri-O-acetyldihydrouridine. The rates of exchange of the imino protons with water suggest that the D-loop in tRNAfMet is less stable than the D-loops in tRNALys or tRNAPhe. Closely spaced peaks were observed for the two dihydrouridines in tRNAPhe in a high resolution spectrum.

Escherichia coli↗
PubMed1986

Improvement of the dideoxy chain termination method of DNA sequencing by use of deoxy-7-deazaguanosine triphosphate in place of dGTP.

The dideoxy chain termination method using deoxy-7-deazaguanosine triphosphate (dc7GTP) in place of dGTP was found to be very useful. Sequencing of a part of the human N-myc gene having 85% GC content is impossible by the original method using dGTP, because of compression of bands. However, the nucleotide sequence of this part was unambiguously determined by analysis of both strands by the modified method. Use of dc7GTP is concluded to improve the dideoxy chain termination method for DNA sequencing.

Base Sequence↗