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Biomedical subjects

S Kaneda

Publications and source records attributed to S Kaneda.

At least 73 records · Page 4Linked to original sources
PubMed1987

[Role of TRH or metoclopramide loading test in the diagnosis of so-called occult or latent hyperprolactinemia].

Present study was performed to investigate whether TRH or metoclopramide (MCP) loading test was useful for the diagnosis of so-called occulted or latent hyperprolactinemia (transient increase of serum prolactin levels more than 30 ng/ml during night; OHP). The circadian profiles of serum prolactin levels were examined in 31 women (age: 23-32 years old) whose BBT charts showed biphasic patterns. Blood samplings had been done every two hours through an intravenous indwelling catheter without any disturbances. And seven cases of the OHP were selected. Five cases of the control were also selected at random. Then, LH-RH (100 micrograms) and TRH (500 micrograms) loading test and LH-RH and MCP (10 mg) loading test were performed to these cases in the mid-luteal phase of the same menstrual cycle at interval of two or three days, and serum FSH, LH and prolactin levels (at 0, 30, 60, 90, 120 min. after the loading test) were determined by radioimmunoassay. Serum prolactin levels in the OHP group showed significant higher levels than those of the control from 22 to 6 o'clock (p less than 0.05-0.005). By the administration of 500 micrograms of TRH, serum prolactin levels of the OHP group increased significantly compared to those of the control at all sampling points (p less than 0.05-0.005), and also by the administration of 10 mg of MCP, the same result was obtained (p less than 0.05-0.02). The maximum peak of serum prolactin levels appeared at 30 min. after TRH or MCP loading.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Role in translation of a triple tandemly repeated sequence in the 5'-untranslated region of human thymidylate synthase mRNA.

A triple tandem repeat (TTR) consisting of 90 nucleotides exists immediately upstream of the ATG initiator codon in human thymidylate synthase (TS) cDNA (pcHTS-1). To investigate the role of the TTR in the expression of the TS cDNA, we used pcHTS-1 to construct mutant cDNA clones in which part of the TTR was deleted or an additional element was inserted. The mutant cDNA plasmid was introduced into murine TS-negative mutant cells and the relative translation efficiencies of the mutant cDNAs were determined by measuring the transient expression of TS activity and the amount of TS mRNA transcribed. The translation efficiency in transient expression of the mutants was increased by deletions covering all the first two repeated elements, and the part of the third closest to the ATG initiator codon, but was not affected by deletions of only parts of the first two repeated elements at the 5' end. The translation efficiency was also not affected by insertion of an additional repeated element into the TTR. These results suggest that the first two repeated elements at the 5' end both have inhibitory effects on translation of the TS mRNA, probably due to the unique structural feature of this element.

Animals↗
PubMed1986

Cell-cycle-directed regulation of thymidylate synthase messenger RNA in human diploid fibroblasts stimulated to proliferate.

Human diploid fibroblasts were synchronized in the resting phase by incubation in medium containing a low level of serum and then stimulated to proliferate by adding a high concentration of serum. DNA replication started 12 hours after addition of serum, and reached a maximum after 24 hours. Thymidylate synthase activity was very low in resting cells, but began to increase 12 hours after growth stimulation and thereafter continued to increase. Thymidylate synthase mRNA in the growing cells was compared with that in resting cells, using cloned human thymidylate synthase cDNA as a probe. Results showed that the mRNA content as a percentage of total RNA began to increase six hours after stimulation, reaching a level about 14 times that in unstimulated cells after 24 hours. However, the mRNA content relative to poly(A)+ RNA had increased two- to fourfold by 24 hours after growth stimulation. Transcription of the thymidylate synthase gene, determined by hybridizing labelled nascent transcripts obtained in isolated nuclei to immobilized human thymidylate synthase cDNA, was similar in the nuclei of resting and of growth-stimulated cells. These results show that the increase in thymidylate synthase mRNA in growth-stimulated cells is caused by an increase in post-transcriptional events.

Cell Division↗
PubMed1986

Bleeding esophageal varices caused by Graves' hypervascular cervical goiter.

A 65-year-old woman presented with an episode of hematemesis and a recurrent cervical goiter due to Graves' disease. The angiogram revealed bleeding esophageal varices which had developed through a drainage vein of the vascular goiter. Total thyroidectomy resulted in eradication of the esophageal varices.

Aged↗
PubMed1986

Induction, by thymidylate stress, of genetic recombination as evidenced by deletion of a transferred genetic marker in mouse FM3A cells.

Studies were made on the genetic consequences of methotrexate-directed thymidylate stress, focusing attention on a human thymidylate synthase gene that was introduced as a heterologous genetic marker into mouse thymidylate synthase-negative mutant cells. Thymidylate stress induced thymidylate synthase-negative segregants with concomitant loss of human thymidylate synthase activity with frequencies 1 to 2 orders of magnitude higher than the uninduced spontaneous level in some but not all transformant lines. Induction of the segregants was suppressed almost completely by cycloheximide and partially by caffeine. Thymidylate stress did not, however, induce mutations, as determined by measuring resistance to ouabain or 6-thioguanine. Thymidylate synthase-negative segregants were also induced by other means such as bromodeoxyuridine treatment and X-ray irradiation. In each of the synthase-negative segregants induced by thymidylate stress, a DNA segment including almost the whole coding region of the transferred human thymidylate synthase gene was deleted in a very specific manner, as shown by Southern blot analysis with a human Alu sequence and a human thymidylate synthase cDNA as probes. In the segregants that emerged spontaneously at low frequency, the entire transferred genetic marker was lost. In the segregants induced by X-ray irradiation, structural alterations of the genetic marker were random. These results show that thymidylate stress is a physiological factor that provokes the instability of this exogenously incorporated DNA in some specific manner and produces nonrandom genetic recombination in mammalian cells.

Animals↗
PubMed1986

Antitumor activity of new semisynthetic saframycin derivatives.

Saframycins Yd-1 and Y3, which have an amino functional group in the side chain, were recently obtained by a directed biosynthesis. Twenty-eight side chain-modified chemical derivatives were prepared from these saframycins, and their in vitro and in vivo antitumor activities were studied. Among these new derivatives, three saframycins, namely, two N-acyl derivatives, pivaloyl- and n-caproylsaframycin Y3, and one water-soluble type, saframycin Yd-1.HCl, were found to show marked antitumor activity against L1210 mouse leukemia cells. Further studies of these saframycin derivatives using B16-F10 melanoma and Lewis lung carcinoma indicated that all three saframycins are also active against B16-F10 melanoma; saframycin Yd-1.HCl showed the greatest prolongation of survival time. Marked inhibition of spontaneous metastasis of Lewis lung carcinoma was observed in mice treated with these new derivatives. Structure-activity relationships among these semisynthetic saframycins are discussed.

Animals↗
PubMed1986

[Two cases of bladder leiomyoma].

Two cases of leiomyoma of the bladder are reported. The first case was a 79-year-old female who presented with gross hematuria and frequent urination. Cystoscopy disclosed a large tumor covered by intact mucosa. This lesion was further evaluated by ultrasound, and was thought to be a submucosal tumor of the bladder. The second case was a 43-year-old female who was referred for further investigation of left giant hydronephrosis. During the investigation, submucosal tumor was incidentally found. Concerning the etiology of the hydronephrosis, left ureteral stenosis due to a previous gynecological operation was suspected. These lesions proved to be leiomyoma of the bladder histologically, and were successfully enucleated. Difficulty in diagnosis of this disease and controversy as to the optimal treatment prompted us to report these cases and to review 68 cases reported in the Japanese literature.

Adult↗
PubMed1985

Nucleotide sequence of a functional cDNA for human thymidylate synthase.

We have determined the nucleotide sequence of a cDNA clone, pcHTS-1, encoding human thymidylate synthase (5,10-methylenetetrahydrofolate: dUMP C-methyltransferase, EC 2.1.1.45) which was previously isolated from a human fibroblast expressible cDNA library and functional in mouse cells. The 1.6 kilobase cDNA insert of pcHTS-1 encodes a subunit protein of 313 amino acid (Mr = 35,706) and its predicted amino acid sequence is highly conserved in many regions including folylpolyglutamate and 5-fluoro-2'-deoxyuridylate binding sites, when compared with those of Lactobacillus casei, Escherichia coli, and bacteriophage T4. The cDNA contains in its 5'-untranslated region a triple tandemly repeated sequence consisting of 90 nucleotides, which starts immediately upstream of the ATG initiator codon, is very high in G+C content (80%), and can form three possible interconvertible stem-loop structures.

Amino Acid Sequence↗
PubMed1985

Relationship between beta-lactamase activity and resistance to beta-lactam antibiotics in Mycobacterium smegmatis.

Penicillin-susceptible mutants and beta-lactamase-negative mutants were isolated from Mycobacterium smegmatis after nitrosoguanidine mutagenesis. Both the mutants were found to be susceptible to low levels of penicillin and cephalosporins by twofold dilution testing. Clavulanic acid reduced the minimal inhibitory concentrations of beta-lactamase-labile beta-lactams for the penicillin-susceptible mutants and the parent strain, but had no effect on the susceptibility of the beta-lactamase-negative mutants. Comparison of the beta-lactamase activities found in these mutants and the parent strain indicated that there was a rough correlation between the beta-lactamase level in these organisms and their susceptibility to beta-lactams.

Anti-Bacterial Agents↗
PubMed1984

Isolation of functional cDNA clones for human thymidylate synthase.

Thymidine auxotrophic mutants of mouse FM3A cells due to thymidylate synthase deficiency can be transformed into prototrophs by DNA-mediated gene transfer using total human DNA (Ayusawa, D., Shimizu, K., Koyama, H., Takeishi, K., and Seno, T. (1983) J. Biol. Chem. 258, 48-53). From one such transformed cell clone, cloned recombinant lambda phages containing DNA fragments were obtained recently that were concluded by circumstantial genetic evidence to have been derived from the human thymidylate synthase gene (Takeishi, K., Ayusawa, D., Kaneda, S., Shimizu, K., and Seno, T. (1984) J. Biochem. (Tokyo) 95, 1477-1483). Using a DNA segment derived from the cloned genomic DNA fragment and free of repetitive sequences as a probe, functional cDNA corresponding to thymidylate synthase mRNA could be cloned from a cDNA library of SV40 transformed human fibroblasts constructed by Okayama and Berg (Okayama, H. and Berg, P. (1983) Mol. Cell. Biol. 3, 280-289). The cloned cDNA plasmid containing an insert of approximately 1.7-kilobase transformed mouse thymidine auxotrophic mutant cells to thymidine prototrophic cells at a frequency of 2-3 transformants/micrograms of DNA/10(5) cells, a value almost comparable to the highest so far reported. The resultant transformants retained the introduced cDNA and expressed human thymidylate synthase protein sufficient for supporting normal growth of otherwise auxotrophic mouse cells.

Cloning, Molecular↗
PubMed1984

Molecular cloning of genomic DNA segments partially coding for human thymidylate synthase from the mouse cell transformant.

Mouse cells deficient in the enzyme thymidylate synthase [TS; EC 2.1.1.45] were serially transformed with human DNA to yield primary and secondary transformants which produced human TS [Ayusawa, D., Shimizu, K., Koyama, H., Takeishi, K., & Seno, T. (1983) J. Biol. Chem. 258, 48-53]. Southern blot hybridization of their genomic DNA showed that six secondary transformants examined contained in common a 5.5 kb EcoRI fragment hybridized with a human Alu sequence. From the secondary transformant genomic library constructed with phage lambda Charon 4A, two recombinant phage clones carrying Alu sequences were isolated. Restriction endonuclease mapping revealed that the insert DNAs of the two phage clones overlapped and covered a region of 19 kb in total. Within this region at least six Alu sequences were located. A 2.0 kb DNA fragment, prepared from an EcoRI fragment subcloned in plasmid pBR322 and free of Alu sequences, hybridized to a single band on RNA blots of primary and secondary transformant poly(A)+ RNA, but not to RNA of mouse wild-type and recipient cell lines. The relative amount of the presumed human TS mRNA was linearly correlated with the relative activity of human TS in various types of mouse transformant cells. These results indicate that these two phage clones contain genomic DNA sequences encoding human TS.

Animals↗