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Biomedical subjects

T Enomoto

Publications and source records attributed to T Enomoto.

At least 217 records · Page 12Linked to original sources
PubMed1992

Termination complex in Escherichia coli inhibits SV40 DNA replication in vitro by impeding the action of T antigen helicase.

DNA replication terminus (ter)-binding protein (TBP) in Escherichia coli binds specifically to the terminus (ter) site, and the resulting complex severely blocks DNA replication in an unique orientation by inhibiting the action of helicases. To generalize the intrinsic nature of the orientated ter-TBP complex against various helicases, we tested the potential of the complex to inhibit the action of three helicases, DNA helicase I, simian virus 40 (SV40) large tumor (T) antigen, and helicase B, derived from F plasmid, SV40, and mouse FM3A cell, respectively. The complex impeded the unwinding activities of all tested helicases in a specific orientation, with the same polarity observed in case of blockage of a replication fork, and, as a result, there was a block of SV40 DNA replication in both crude and purified enzyme systems in vitro. As the specificity in polarity of inhibition extends to heterologous systems, there may be common structure/mechanism features in helicases.

Antigens, Polyomavirus Transforming↗
PubMed1992

Alteration of a DNA-dependent ATPase activity in xeroderma pigmentosum complementation group C cells.

DNA-dependent ATPase activities in crude extracts prepared from HeLa cells were separated into five peaks by fast protein liquid chromatography Mono Q column chromatography. Similar elution profiles were observed with the extracts from human cells normal in repair and xeroderma pigmentosum cells belonging to complementation groups A through G except for group C. An alteration in elution of one of the five ATPases, designated DNA-dependent ATPase Q1, was observed with a cell line of complementation group C. This alteration was observed with all tested cell lines that belonged to group C. ATPase Q1 in HeLa cell extracts exhibited about 2-fold higher activity with ultraviolet light-irradiated DNA as compared to that with non-irradiated DNA, whereas little difference in the effects of two DNAs was observed with the ATPase activities in the extract from group C cells.

Adenosine Triphosphatases↗
PubMed1992

DNA-dependent adenosinetriphosphatase C1 from mouse FM3A cells has DNA helicase activity.

In our previous study, we identified four chromatographically distinct DNA-dependent ATPases, B, C1, C2, and C3, in mouse FM3A cells (Tawaragi, Y., Enomoto, T., Watanabe, Y., Hanaoka, F., and Yamada, M. (1984) Biochemistry 23, 529-533). The DNA-dependent ATPase C1 has been purified and characterized in detail. A divalent cation and a polynucleotide cofactor were required for the ATPase activity. Poly(dT), single-stranded circular DNA, and heat-denatured DNA were very effective. Almost no ATPase activity was observed with S1 nuclease-treated native DNA. ATPase C1 hydrolyzed ATP only among the ribo- and deoxyribonucleoside triphosphates tested, and this fact distinguished ATPase C1 from ATPases B, C2, and C3, because the latter enzymes are capable of hydrolyzing both ATP and dATP. The purified DNA-dependent ATPase C1 fraction was shown to have a DNA helicase activity that was dependent on hydrolysis of ATP. The helicase activity and DNA-dependent ATPase activity cosedimented at 5.2 S on glycerol gradient centrifugation. Both activities showed similar preferences for nucleoside 5'-triphosphates and similar requirements for divalent cations. The DNA helicase activity was inhibited by the addition of single-stranded DNAs that served as cofactor for the ATPase activity. The efficiency of a single-stranded DNA to inhibit DNA helicase activity correlated well with the capacity of the DNA to serve as cofactor for DNA-dependent ATPase activity. The helicase was shown to migrate along the DNA strand in the 5' to 3' direction, which is the same direction of migration of the mouse DNA helicase B (Seki, M., Enomoto, T., Yanagisawa, J., Hanaoka, F., and Ui, M. (1988) Biochemistry 27, 1766-1771).

Adenosine Triphosphatases↗
PubMed1992

Growth state and cell cycle dependent phosphorylation of DNA topoisomerase II in Swiss 3T3 cells.

We have investigated the amount of DNA topoisomerase II and phosphorylation of the enzyme in Swiss 3T3 cells during the transition from cell quiescence to proliferation. A relatively high level of phosphorylation was observed with proliferating cells while no or a very low level of phosphorylation was observed with quiescent cells. Phosphoamino acid analysis of the phosphorylated topoisomerase II revealed that the phosphorylated aminoacyl residue was serine. When quiescent cells were stimulated to grow by the addition of serum, DNA synthesis began to increase at 9 h after serum addition, reaching a maximum at 15 h and then declining. The amount of topoisomerase II began to increase at 6 h and reached a maximum at 22-27 h, corresponding to the G2 phase. The phosphorylation of topoisomerase II measured by pulse-labeling gradually increased from 6 to 18 h and reached a maximum at 22 h when the amount of the enzyme was maximum. The level of phosphorylation measured by continuous-labeling increased gradually up to 12 h and markedly up to 28 h, and then declined. The increase in the rate of phosphorylation in the G2 phase was affected by inhibiting DNA synthesis, but the increase in the amount of the enzyme was not. Thus, it was suggested that the regulation of phosphorylation of topoisomerase II differs from that of the amount of the enzyme.

3T3 Cells↗
PubMed1992

Cavernous hemangioma over the anterior fontanelle.

This is a report of an extremely rare case of cavernous hemangioma over the anterior fontanelle in a 5-year-old boy. Cavernous hemangioma is most common in or beneath the skin of the face, neck, and extremities and sometimes occurs in the scalp. Although cavernous hemangioma is often quoted in the literature as a differential diagnosis of a mass located at the anterior fontanelle, we could not find an illustrative case in published articles. We discuss the characteristics and differential diagnosis of cavernous hemangioma over the anterior fontanelle.

Carotid Arteries↗
PubMed1992

Effect of TPA, okadaic acid and 1 alpha,25-dihydroxyvitamin D3 on neoplastic transformation induced by 60Co gamma-rays or 252Cf fission neutrons in Balb/c 3T3 cells.

The effects of 12-O-tetradecanoylphorbol-13-acetate (TPA), 1 alpha,25-dihydroxyvitamin D3 [1 alpha,25(OH)2D3] and okadaic acid were individually examined on the neoplastic transformation of Balb/c 3T3 cells which were exposed to either 60Co gamma-rays or 252Cf fission neutrons. The addition of 1 alpha,25(OH)2D3, or TPA, enhanced the transformation induced by gamma-rays or low doses of fission neutrons. No enhancement was observed by the addition of okadaic acid except at toxic concentrations (5 ng/ml) and with higher doses of radiation. Moreover, the enhancement of transformation by either 1 alpha,25(OH)2D3 or TPA decreased as the radiation dose was increased. The enhancement ratio, calculated by least-square analysis from 0 Gy to 1 Gy, was greater for 1 alpha,25(OH)2D3 than for TPA, and also greater for gamma-ray irradiation than for neutron irradiation. These results suggest that the promotion of radiation-induced transformation depends on the level of the initial damage caused by radiation; and that the differences in the enhancement properties of different chemicals may be due to different individual triggering mechanisms involved in the transformation process.

3T3 Cells↗
PubMed1992

Correlation of HLA types and clinical findings in Japanese patients with hyperthyroid Graves' disease: evidence indicating the existence of four subpopulations.

OBJECTIVES: To re-evaluate the associations of HLA types with Japanese patients having hyperthyroid Graves' disease, HLA types and clinical findings were correlated. DESIGN: Four independent clinical findings (ophthalmopathy, family history, age at onset and size of goitre) and two autoantibody titres, thyrotrophin binding inhibitor immunoglobulin (TBII) and anti-thyroid microsmall antibody (anti-M), were analysed. PATIENTS: Eighty-eight Japanese patients with hyperthyroid Graves' disease and 186 control subjects were assessed. MEASUREMENT: Serological HLA typing was performed on 73 antigens in HLA-A, -B, -C, -DR and -DQ loci. HLA-D and -DP (29 antigens) were determined by the restricted fragment length polymorphism (RFLP) methods. TBII and anti-M were measured by commercially available kits. RESULTS: Patients with potent antibody titres had HLA antigens commonly seen among all the patients with Graves' disease. Interestingly, however, HLA-B35 and -Cw11 were found to relate with negative and/or weak TBII, and HLA-B7 and absence of HLA-Aw19 with negative anti-M. Significant associations were observed between HLA-DRw8 and large goitre and absence of ophthalmopathy, and between HLA-DQw4 and a negative family history of diffuse goitre (corrected P less than 0.05). Several other antigens were also found to be significant. Among these antigens, four pairs of MHC classes I and II were found to relate to the clinical findings independently. HLA-DQw4 and negative -A31 pair was closely related to ophthalmopathy, negative family history and late onset of disease. The HLA-B5 and -Dw12 pair was associated with ophthalmopathy, positive family history and early onset of disease. The HLA-A11 and negative -DPw2 pair was associated with ophthalmopathy, negative family history and early onset of disease. The HLA-Bw46 and -DRw8 pair did not increase in frequency above that seen with HLA-DRw8 alone. These four antigen groups (HLA-DRw8, HLA-DQw4 and negative-A31, HLA-B5 and -Dw12, and HLA-A11 and negative -DPw2) were observed in the majority (68%) of patients with Graves' disease and at a significantly higher incidence than in the control group (P less than 0.05). CONCLUSION: There are four subpopulations of Japanese patients with hyperthyroid Graves' disease. This is one of the reasons why the association of HLA types in Japanese patients is rather weak when they are studied as one group.

Adolescent↗
PubMed1992

[A case of sarcoidosis presenting with Heerfordt's syndrome, associated with hepatosplenomegaly, pleural effusion, and ascites].

A 30-year-old female developed symptoms consistent with Heerfordt's syndrome (complete type) and was effectively treated with steroid. However, she developed hepatosplenomegaly, bloody pleural effusion, and ascites one year after discontinuation of steroid therapy. The symptoms were considered to be due to sarcoidosis since serum ACE level, and ACE level and OKT4/8 ratio in pleural and peritoneal effusions were significantly elevated, and readministration of steroid normalized these changes. Bloody pleural and peritoneal effusions are very rare complications of sarcoidosis.

Adult↗
PubMed1992

[Interpeak components of event-related potentials--comparison between normal and schizophrenic groups].

Event-related potentials (ERPs) during a two-tone discrimination task were recorded in 85 normal subjects and 110 schizophrenic subjects. We divided ERPs into 4 interpeak components. We named them A, A', B and B'. A is the component from the stimulus point to n100 peak. A' is the one from n100 peak to p200 peak. B is the one from p200 peak to n200 peak. B' is the one from n200 peak to p300 peak. Their latency was named Al, A'l, Bl, and B'l respectively. Their amplitude was also named Aa, A'a, Ba and B'a respectively. Bl and A'l of the schizophrenic group were both significantly longer than those of the normal group. B'a of the schizophrenic group was significantly smaller than that of the normal group. Interrelations between interpeak components of the normal group were examined statistically. Regarding latency, a significant negative correlation was seen between Al and A'l, and also between Bl and B'l. Regarding amplitude, a significant positive one was seen between Aa and A'a, and also between Ba and B'a. Interrelations between Al and A'l, Bl and B'l, Aa and A'a, and Ba and B'a of the schizophrenic group were the same as those of the normal group. These negative correlations in latency suggest that n100 peaks and n200 peaks have 'jitter'. A combination of interpeak components is supposed to reflect a higher function of the brain. There was a significant negative correlation between (A + A')l and (B + B')l in the normal group, but there was not a significant one between them in the schizophrenic group. The schizophrenic group is supposed to have a certain abnormality in a higher function of the brain. Our result suggests that we may possibly be able to associate an abnormal focus around p200 peak with some symptoms and signs of schizophrenia.

Adult↗
PubMed1992

[Mechanism of attention in sleep--the changes of waveforms of event-related potentials in sleep].

Since attention has such a close correlation with arousal level, the influence of sleep on the waveforms of event related potential (= ERP) must be studied in advance for evaluating attentiveness of human mental activity. ERP, which odd-ball paradigm was used to elicit, was examined in 9 adult and healthy subjects from arousal to sleep. And ERP during a whole night was also examined in 5 of them to study the relation of the waveforms of ERP and sleep stages including a stage of rapid eye movement. As a result, there were some clear differences between the waveforms of the rare and frequent stimuli, and with change of sleep stages the differences also changed. Remarkable increase of amplitude and prolongation of latency of P200 and N200 were found in the waves of target stimuli in stage I. Activities of both components were connected with each other like a complexed component and preceded by the change of P300 activities. The waveforms of target stimuli in stage II had same kind of components with those of arousal stage. There were increased P200, N200, P300 activities and subsequent large negative activity which we called N3. These components were not clear in the waveforms of non-target stimuli. But P300 and N3 components were disappeared gradually during stage III. The averaged waveforms in stage III accompanied with 14-16 Hz fast wave suggested that they were identical with K-complex of sleep EEG. Add to this result, the habituation usually observed on P200 and N200 of nontarget stimuli in arousal let us to think that they are also identical with orienting reflex by rare and novel stimuli of external events (Sokolov). According to the result of examination changing the probability of target stimuli (20%----50%----80%), the waves of target stimuli in stage II were dependent on the probability of rare stimuli as well as in arousal stage. The dependence on probability was thought to reflect an automatic processing of selecting stimuli by orienting reflex in sleep. Another 3 subjects were examined of auditory evoked response in sleep with the same stimuli and without a task of counting numbers of rare stimuli. In stage II, however, they showed the waveforms by rare stimuli just like those by rare and target stimuli of 9 subjects. Then, it was supposed that attentiveness for external stimuli might be existent in sleep and changeable with sleep stages.

Adult↗
PubMed1991

K-ras activation in premalignant and malignant epithelial lesions of the human uterus.

We previously reported (Cancer Res., 50:6139-6145, 1990) a significant frequency of activating point mutations in codon 12 of the K-ras oncogene in endometrial adenocarcinomas of the uterine corpus (series 1). To further define the role of ras activation in the development of endometrial adenocarcinoma, we surveyed cystic, adenomatous, and atypical hyperplasias of uterine endometrium and additional cases of endometrial and cervical carcinoma (series 2) for the presence of activating mutations in cellular protooncogenes of the ras family. Polymerase chain reaction was performed from deparaffinized sections of formalin-fixed paraffin-embedded tissue. We screened for point mutations in codons 12, 13, and 61 of the K-, H-, and N-ras genes by dot blot hybridization analysis with mutation-specific oligomers. Mutations in K-ras were also confirmed by direct genomic DNA sequencing. Of 19 endometrial adenocarcinomas in series 2, point mutations in ras genes were found in 7 tumors. Six contained single-base substitutions, five in codon 12 of K-ras and one in codon 12 of N-ras. The seventh tumor contained two different point mutations in codon 12 of K-ras. In one endometrial adenocarcinoma, tumor cells with point mutations in K-ras were predominantly localized to a portion that had a more aggressive histological pattern. In endometrial hyperplasia, K-ras mutations, one in codon 12 and one in codon 13, were found in 2 of 16 hyperplasias histologically classified as atypical and clinically considered premalignant. None of 6 adenomatous hyperplasias and none of 12 cystic hyperplasias, the latter of which is considered clinically benign, contained any detectable ras mutations. No mutations in H-ras were detected in either carcinomas or hyperplastic tissue.

Adenocarcinoma↗
PubMed1991

A synthetic oligopeptide derived from human thyrotropin receptor sequence binds to Graves' immunoglobulin and inhibits thyroid stimulating antibody activity but lacks interactions with TSH.

An 11-residue oligopeptide, P-195, was synthesized to match human thyrotropin (TSH) receptor structure from No. 333 to 343 of amino acid sequence. Preincubation of 5 Graves' IgGs with P-195 up to 10 micrograms resulted in dose-dependent reductions of thyroid stimulating antibody (TSAb) activity. [125I] labeled P-195 was found to bind Graves' IgG. The bound radioactivity correlated significantly with their TSAb activity (N = 25, r = 0.587, p less than 0.01). A peptide having a completely reverse sequence as P-195 did not show such biological activity. The peptide did not affect TSH and thyrotropin binding inhibitor immunoglobulin (TBII) on their receptor binding nor biological activities. P-195 was concluded to have a part of TSAb binding sites.

Amino Acid Sequence↗
PubMed1991

K-ras activation in gastric epithelial tumors in Japanese.

Point mutation in codons 12, 13 and 61 of the K-ras oncogene in gastric epithelial tumors were investigated by polymerase chain reaction from sections of formalin-fixed, paraffin-embedded tissue followed by dot-blot hybridization with mutation-specific oligonucleotide probes. Point mutations were found specifically in four of 20 tumors of intestinal histological subtype; GGT to GAT in three cases and to GTT in one case, all in codon 12 of K-ras. These mutations were also confirmed by direct sequencing. In contrast, none of 11 diffuse-type tumors showed K-ras point mutations. While K-ras point mutations may not be frequent events in gastric tumorigenesis, the similarity of the intestinal-type gastric tumors and colorectal tumors for K-ras point mutations as well as the association of mutations in K-ras with a particular gastric tumor histology implicates K-ras activation in the development of these tumors.

Adenoma↗
PubMed1991

Reversible porencephaly. Alteration of the cerebrospinal fluid flow after shunt malfunction.

The cases of four infants (five lesions) are reported, where "porencephalic cysts," located along the ventricular catheter after shunt malfunction and Ommaya reservoir insertion, disappeared after ventriculoperitoneal (VP) shunt revision and combined cyst peritoneal (CP) shunt, or after VP shunt alone. This pathological state is thought to be a rare postoperative complication. Its pathogenesis and therapy are discussed. Shunt malfunction or Ommaya reservoir insertion may result in a hypertensive hydrocephalic state. Cerebrospinal fluid (CSF) flows out through a catheter penetrating the site of the ventricular wall and expands in the surrounding white matter to form a porencephalic cavity. Once this porencephalic state occurs, it will not disappear spontaneously because the CSF flows in one direction. As treatment for closed porencephaly, CP shunt following a VP shunt revision was markedly effective; for communicating porencephaly, a VP shunt revision alone was effective.

Brain↗
PubMed1991

Human ubiquitin-activating enzyme (E1): compensation for heat-labile mouse E1 and its gene localization on the X chromosome.

We have constructed interspecific somatic cell hybrids between a temperature-sensitive (ts) mutant cell line of mouse FM3A cells, ts85, that has a heat-labile ubiquitin-activating enzyme (E1) and a human diploid fibroblast cell line, IMR-90. A hybrid clone that could grow stably at a nonpermissive temperature (39 degrees C) was obtained. Segregation of the hybrid cells at a permissive temperature (33 degrees C) gave rise to temperature-sensitive clones. The electrophoresis of extracted histones and karyotype analysis of the segregants revealed a close correlation of the ability to grow at 39 degrees C, the presence of uH2A (ubiquitin-H2A semihistone) at 39 degrees C, and the presence of the human X chromosome. One of the hybrid clones that could grow at the nonpermissive temperature contained the X chromosome as the only human chromosome. The sodium dodecyl sulfate-polyacrylamide gel electrophoretic pattern of affinity-purified E1 showed that this hybrid clone contained both human and mouse type E1. Thus we conclude that the functional gene for human E1 is located on the X chromosome.

Animals↗
PubMed1991

Mouse DNA primase plays the principal role in determination of permissiveness for polyomavirus DNA replication.

We have investigated the species-specific replication of polyomavirus DNA in the cell-free system that was established previously (Y. Murakami, T. Eki, M. Yamada, C. Prives, and J. Hurwitz, Proc. Natl. Acad. Sci. USA 83:6347-6351, 1986). Extracts from various species of cells supported polyomavirus DNA replication in a species-specific manner that was consistent with the host range specificity of polyomavirus; extracts prepared from mouse and hamster cells were active, whereas extracts prepared from human, monkey, and insect cells were inactive. The addition of DNA polymerase alpha-primase purified from mouse cells induced the replication of polyomavirus DNA in a cell-free system containing polyomavirus large tumor antigen and nonpermissive cell extracts, such as human and insect cell extracts. Isolated mouse DNA primase alone also induced polyomavirus DNA replication in human cell extracts but not in insect cell extracts, indicating that mouse DNA primase plays the principal role in determining permissiveness for polyomavirus DNA replication.

Animals↗
PubMed1991

K-ras activation occurs frequently in mucinous adenocarcinomas and rarely in other common epithelial tumors of the human ovary.

To explore the role of mutational activation of members of the ras family of cellular protooncogenes in the development of human ovarian neoplasms, a series of 37 ovarian tumors from Japanese patients was studied. These included 30 common epithelial tumors (1 mucinous tumor of borderline malignancy, 7 mucinous adenocarcinomas, and 22 nonmucinous carcinomas: 10 serous, 3 clear cell, 8 endometrioid, and 1 undifferentiated), 5 tumors of germ cell origin, and 2 sex cord/stromal cell tumors. Polymerase chain reaction was performed from selected areas of deparaffinized sections of formalin-fixed paraffin-embedded tissue, and the presence of activating point mutations in codons 12, 13, and 61 of the H-, N-, and K-ras genes was probed by dot-blot hybridization analysis with mutation specific oligonucleotides. Mutations in K-ras were also looked for by direct genomic sequencing. The overall frequency of ras gene mutations was 10/37 (27%). Mutations were detected only in K-ras, and were found in most of the mucinous tumors, including the one such tumor of borderline malignancy (6/8; 75%). In one mucinous adenocarcinoma, two mutations were detected in paraffin-embedded material that had not previously been found in high molecular weight DNA isolated from frozen tissue from the same case. K-ras mutations occurred significantly more frequently in mucinous tumors (6/8, 75%) than in serous carcinomas (2/10, 20%; P = 0.031) or in all nonmucinous types of epithelial ovarian tumors combined (3/22, 14%; P = 0.0031).

Adenocarcinoma, Mucinous↗