Biomedical subjects

T Enomoto

Publications and source records attributed to T Enomoto.

At least 235 records · Page 13Linked to original sources

PubMed1991

[Mitral regurgitation due to redundant chordae].

This paper reports the etiology and the findings of phonocardiograms and echocardiograms in four cases with mitral regurgitation caused by the redundant chordae. Redundancy of the chordae were determined by the surgeon during operation. The results were as follows: 1. The etiology of redundant chordae was either congenital, rheumatic, or mucoid degeneration. 2. Phonocardiographic findings of this condition are a holosystolic murmur accompanied by a diastolic rumble at the apex. 3. Two-dimensional echocardiogram shows holosystolic bulging of the mitral leaflet to which redundant chordae are attached. 4. The findings of the M-mode echocardiogram are multiple linear echoes and bowing of the mitral valve in systole.

Adult↗

PubMed1990

A novel epidermal cell differentiation inhibitor (EDIN): purification and characterization from Staphylococcus aureus.

A factor inhibiting the calcium-induced terminal differentiation of cultured mouse keratinocytes was purified to homogeneity from the extracellular products of S. aureus E-1 and designated 'epidermal cell differentiation inhibitor' (EDIN). EDIN activity was sensitive to trypsin and heat-labile, suggesting that EDIN is a protein. EDIN gave a single band with a molecular weight of 27,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and was found to be a single chain polypeptide, having an isoelectric point higher than 9. The N-terminal amino acid sequence of EDIN was determined as A-D-V-K-N-F-T-D-L. EDIN inhibited the differentiation of not only mouse but also human keratinocytes in culture.

Amino Acids↗

PubMed1990

Possible binding site of thyrotropin binding inhibitor immunoglobulin (TBII) on the thyrotropin (TSH) receptor, which is different from TSH binding site.

A synthetic decapeptide, P-194, which has the sequence No. 103 to 111 of hTSH receptor structure with an additional N-terminal tyrosine, did not bind TSH nor affected its receptor binding and thyroid stimulating activity. Preincubation of P-194 with sera from thyroid patients caused a significant decrease in TBII activity in almost all 12 TBII positive sera and an increase of thyroid stimulating activity in 3 of 7 Graves' IgG studied. In addition, [125I] P-194 bound to serum IgG fraction from thyroid patients with a positive correlation with TBII (N = 35, r = 0.509, p less than 0.01). The P-194 portion may be, at least a part of, TBII binding site distinct from the TSH binding site on the TSH receptor.

Animals↗

PubMed1990

Purification and characterization of mouse DNA polymerase alpha devoid of primase activity.

A simple method was developed for the isolation of primase-free DNA polymerase-alpha from the DNA polymerase-alpha-primase complex of mouse FM3A cells. The polymerase was separated from primase subunits by chromatography on a single-stranded DNA-cellulose column in the presence of 50% etylene glycol. The primase-free DNA polymerase-alpha contained two polypeptides with molecular masses of 180,000 and 68,000. Analysis of the DNA products with poly(dA)-oligo(dT)10 as template-primer revealed that both primase-free DNA polymerase-alpha and the DNA polymerase-alpha-primase complex predominantly synthesized short DNA with less than 30 nucleotides, but that the DNA polymerase-alpha-primase complex also synthesized some longer DNA with more than 300-400 nucleotides.

Animals↗

PubMed1990

K-ras activation in neoplasms of the human female reproductive tract.

The role of cellular oncogenes in the development of epithelial tumors of the human female reproductive tract has not previously been extensively studied. DNAs isolated from ten human uterine, 13 ovarian, and four cervical neoplasms and from three cell lines derived from endometrial adenocarcinoma were investigated by dot blot hybridization after polymerase chain reaction amplification of ras gene sequences and in some cases by NIH 3T3 transfection. Transforming activity was found in two of nine endometrial adenocarcinomas, but none of seven ovarian carcinomas and none of four cervical carcinomas showed transforming activity. K-ras sequences with a GGT----GAT mutation in codon 12 were demonstrated in both transformants derived from endometrial carcinoma. K-ras codon 12 mutations were similarly detected in six of 13 endometrial carcinomas (one GAT and GCT, one GTT and GCT, two GAT, two GTT) and two of 13 ovarian tumors (GAT and GCT, GAT), both mucinous adenocarcinomas. Point mutation of K-ras in codon 12 is thus comparably frequent in uterine endometrial carcinomas and in colorectal carcinomas and may have similar significance as an event that contributes to progression of these tumors. Cervical carcinomas and ovarian tumors in general, with the possible exception of mucinous adenocarcinoma of the ovary, do not appear to have this characteristic.

Animals↗

PubMed1990

DNA primase stimulatory factor from mouse FM3A cells has an RNase H activity. Purification of the factor and analysis of the stimulation.

Two forms of DNA primase stimulatory factor have been purified from mouse FM3A cells and shown to have RNase H activity. One of the factors, which consists of three polypeptides of 42,000, 41,000, and 27,000 daltons, was characterized in its properties as RNase H and DNA primase stimulatory factor. The nucleolytic activity of the factor specifically digested the RNA component of RNA-DNA hybrids in an endonucleolytic manner. The stimulation by the factor was observed in DNA synthesis by DNA primase-DNA polymerase alpha complex on unprimed DNA templates, and the DNA chains synthesized under these conditions in the presence of the factor were much shorter than those synthesized in its absence. The stimulatory effect of the factor on DNA primase activity was directly confirmed with DNA primase dissociated from DNA polymerase alpha by the observation of the increase in the number of synthesized oligoribonucleotides. The primer RNA synthesis by DNA primase-DNA polymerase alpha complex under the condition where DNA synthesis occurred was also significantly stimulated by the factor. Furthermore, under these conditions RNA primers were removed from DNA chains by the RNase H activity of the factor.

Animals↗

PubMed1990

Establishment of a human undifferentiated thyroid cancer cell line producing several growth factors and cytokines.

A cell line was established from undifferentiated giant cell carcinoma of the thyroid. The authors obtained cells from a 44-year-old patient admitted because of a rapidly growing anterior neck mass. The patient had significant leukocytosis and hypercalcemia shortly before her death. An autopsy revealed epidermoid metaplasia of the tumor cells. The cells (HTC/C3) had lost most of their differentiated functions. However, their thyroid nature was shown by peroxidase staining and by enzyme-linked immunostaining with Hashimoto patients' sera. The tumor extract was found to contain parathyroid (PTH)-like activity. Significant amounts of colony stimulating factor (CSF), which was further defined to be GM-CSF, and interleukin-1 alpha (IL-1 alpha) were detected in the conditioned media. Epidermal growth factor (EGF) binding to the HTC/C3 showed rich EGF receptors. Furthermore, the conditioned medium inhibited the binding of 125I-mEGF to HeLa cells, and transforming growth factor (TGF) was found repeatedly in the media.

Adult↗

PubMed1990

DNA helicase and nucleoside-5'-triphosphatase activities of polyoma virus large tumor antigen.

Polyoma virus large tumor antigen (PyV T antigen) has been purified to near homogeneity by immunoaffinity column chromatography. We have detected DNA helicase and ATPase (nucleoside-5'-triphosphatase) activities in the purified PyV T antigen fraction and characterized these activities. The ATPase activity was stimulated about 2-fold by poly(dT), which was the most effective stimulator among the synthetic polynucleotides tested. Natural nucleic acids, such as calf thymus native and heat-denatured DNA, and single-stranded circular fd DNA were also effective, but the degree of stimulation was less than 1.5-fold. The basal and poly(dT)-stimulated ATPase activities showed similar preference for nucleoside 5'-triphosphates, requirement for divalent cations, and pH optima. The preference for nucleoside 5'-triphosphates was ATP, dATP greater than CTP, UTP much greater than GTP. The only difference observed between the two activities was salt sensitivity. The basal ATPase activity was resistant to KC1 up to 300 mM. In contrast, poly-(dT)-stimulated activity was reduced to the level of basal activity at 300 mM KC1. DNA helicase activity required divalent cations and was dependent on hydrolysis of ATP. The activity showed similar preference for nucleoside 5'-triphosphates, requirement for divalent cations, and pH optimum as the two ATPase activities, and the salt sensitivity of DNA helicase activity was similar to that of poly(dT)-stimulated ATPase activity. The helicase activity was inhibited competitively by the addition of single-stranded or double-stranded DNA, and a relatively high inhibitory activity was observed with poly [d(A-T)]. The PyV T antigen helicase was found to migrate in the 3' to 5' direction along the DNA strand to which the protein bound.

Adenosine Triphosphatases↗

PubMed1990

Purification and characterization of type II DNA topoisomerase from mouse FM3A cells: phosphorylation of topoisomerase II and modification of its activity.

Type II topoisomerase has been purified from mouse FM3A cells by using P4 phage knotted DNA as a substrate. Analysis of the purified enzyme by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed two bands of apparent molecular masses of 167 and 151 kDa. Partial digestion of the two bands with Staphylococcus aureus V8 protease indicated that the two polypeptides were structurally related. The enzyme required ATP and Mg2+ for activity. dATP could substitute for ATP, and ITP was slightly effective at 5-10 mM. The activity was sensitive to 4'-(9-acridinylamino)methanesulfon-m-anisidide (m-AMSA), coumermycin, and ethidium bromide. A protein kinase activity was detected in the partially purified topoisomerase II fraction, and this protein kinase was further purified. The protein kinase phosphorylated the purified topoisomerase II, and the phosphorylation of topoisomerase II by the kinase increased the activity by 8.6-fold over that of the unmodified enzyme. The treatment of the purified topoisomerase II with alkaline phosphatase abolished the enzyme activity almost completely, and the treatment of the dephosphorylated topoisomerase II with the protein kinase restored the enzyme activity. The protein kinase activity was not stimulated by Ca2+ or cyclic nucleotides, and the aminoacyl residue phosphorylated by the kinase was serine. Enzymatic properties of the kinase were very similar to those of the kinase reported to be tightly associated with the Drosophila topoisomerase II [Sander, M., Nolan, J. M., & Hsieh, T.-S. (1984) Proc. Natl. Acad. Sci. U.S.A. 81, 6938-6942]. The immunoprecipitation of nuclear extracts prepared from 32P-labeled cells with anti-mouse topoisomerase II antiserum indicated that DNA topoisomerase II existed in mouse cells as a phosphoprotein.

Adenosine Triphosphate↗

PubMed1990

Isolation of temperature-sensitive cell cycle mutants from mouse FM3A cells. Characterization of mutants with special reference to DNA replication.

A large number of mutants that are temperature sensitive (ts) for growth have been isolated from mouse mammary carcinoma FM3A cells by an improved selection method consisting of cell synchronization and short exposures to restrictive temperature. The improved method increased the efficiency of isolating DNA ts mutants, which showed a rapid decrease in DNA-synthesizing ability after temperature shift-up. Sixteen mutants isolated by this and other methods were selected for this study. Flow microfluorometric analysis of these mutants cultured at a nonpermissive temperature (39 degrees C) for 16 h indicated that five clones were arrested in the G1 to S phase of the cell cycle, six clones were in the S to G2 phase, and two clones were arrested in the G2 phase. The remaining three clones exhibited 8C DNA content after incubation at 39 degrees C for 28 h, indicating defects in mitosis or cytokinesis. These mutants were classified into 11 complementation groups. All the mutants except for those arrested in the G2 phase and those exhibiting defects in mitosis or cytokinesis showed a rapid decrease in DNA synthesis after temperature shift-up without a decrease in RNA and protein synthesis. The polyomavirus DNA cell-free replication system, which consists of polyomavirus large tumor antigen and mouse cell extracts, was used for further characterization of these DNA ts mutants. Among these ts mutants, only the tsFT20 strain, which contains heat-labile DNA polymerase alpha, was unable to support the polyomavirus DNA replication. Analysis by DNA fiber autoradiography revealed that DNA chain elongation rates of these DNA ts mutants were not changed and that the initiation of DNA replication at the origin of replicons was impaired in the mutant cells.

Animals↗

PubMed1990

H-ras activation and ras p21 expression in bladder tumors induced in F344/NCr rats by N-butyl-N-(4-hydroxybutyl)nitrosamine.

Bladder tumors were induced in male F344/NCr rats by administration of N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) at 500 p.p.m. in their drinking water for 12 weeks. Twenty-one bladder tumors that developed between 25 and 50 weeks after BBN administration was begun were evaluated for immunoreactivity with polyclonal or monoclonal antibodies raised against ras p21, for amplification of ras genes by Southern blotting, and for activating point mutations in ras genes by selective oligonucleotide hybridization of products from polymerase chain reaction (PCR). Increased expression of ras p21 was detected by avidin-biotin immunohistochemistry in 18/21 (85%) of the neoplastic bladder lesions. By Southern analysis, there was no significant amplification of H-ras, K-ras or N-ras in any of the tumors except one that showed a 5-fold amplification of K-ras. Point mutations in ras genes were detected by selective oligonucleotide hybridization of the products of PCR. Of the 21 bladder tumors, three tumors were shown to have mutations in codon 12 (GGA----GAA), six tumors in codon 61 (two CAA----CTA, four CAA----CGA), and one in both codon 12 (GGA----GAA) and codon 61 (CAA----CGA), all in H-ras. Thus 10 of 21 tumors has ras gene mutations in a portion of the tumor cells. The variable pattern of point mutation in H-ras suggests that these mutations may not all be a direct consequence of interaction of BBN metabolites with H-ras. Enhanced expression of ras p21 was always focal and was not necessarily associated with transforming ras mutations. It is therefore suggested that tumorigenesis in BBN-initiated bladder cells might involve H-ras activation as part of a multistep pathway; however, H-ras involvement is not obligatory for tumor development.

Animals↗

PubMed1990

Novel non-tumorigenic cell variants showing potentially different susceptibility to v-src-induced metastasis.

Two non-tumorigenic variant cells were isolated from UV-irradiated Balb/c 3T3 cells on the basis of their different responsiveness in phorbol ester-induced morphological change (rounding formation). They showed marked differences of lung metastatic potentials after intravenous injections of their v-src transformants into nude mice; phorbol ester-resistant variant TR4 cells transformed by v-src were hypermetastatic, whereas v-src transformants of phorbol ester-sensitive variant TR5 cells were not metastatic at all. These different metastatic responses were not observed in v-K-ras-induced transformants of the variants. These non-tumorigenic variant cells may pre-acquire the genetic alteration of certain src-specific and metastasis-associated factors. This system may be useful for genetic analysis of the induction of metastasis.

Animals↗

PubMed1990

Prolonged effects of recombinant human interleukin-1 alpha on mouse thyroid function.

Rapid and prolonged effects of recombinant human interleukin-1 alpha (IL-1 alpha) on mouse thyroid were studied. After daily administration of 15 micrograms or 1 microgram IL-1 for 7 consecutive days, serum T4 concentrations rapidly fell to undetectable levels but returned to near control level after the cessation of IL-1. On the 31st day, 3 weeks after the drug cessation, a significant depression of serum T4 was observed again. In addition, the IL-1-treated mouse thyroid showed an in vitro unresponsiveness to TSH, with an increase of pituitary TSH (2.24-fold by 15 micrograms IL-1). To understand underlying mechanisms further, serial observations were performed. Thyroidal T4 contents increased initially, decreased to a low level at day 14, and returned to approximately the control level. IL-1 administration induced an increase in the basal thyroidal cAMP level for a prolonged period. Its response to TSH showed a gradual decline to a level approximately 30% of the control by the 31st day. Pituitary TSH contents on the 22nd and 31st days showed significant elevations. Slight decreases in thyroidal TSH binding and T4 contents also were seen concomitantly. These studies indicate that an administration of a large dose of IL-1 results in a dramatic decrease in serum T4 primarily through the inhibition of T4 release from the thyroid. The results also indicate the induction of a prolonged hypothyroid state due to the unresponsiveness to TSH via a postreceptor mechanism.

Animals↗

PubMed1990

Similarity and dissimilarity between clinical and laboratory findings, especially anti-thyrotropin receptor antibody in ophthalmic Graves' disease without persistent hyperthyroidism and hyperthyroid Graves' disease.

The aim of this study was to investigate thyroid states, significance of anti-TSH receptor antibodies and the clinical courses of patients with euthyroid Graves' ophthalmopathy. The clinical and laboratory finding of 30 patients with euthyroid Graves' ophthalmopathy were briefly as follows: 1) normal sized thyroid or small goiter; 2) negative or weakly positive thyrotropin binding inhibitor immunoglobulin (TBII); 3) normal thyroid [99 m-Tc] pertechnetate uptake; and 4) frequent observations of low serum TSH values. Besides TBII, thyroid stimulating antibody (TSAb) was measured under low salt and isotonic conditions using FRTL-5 rat thyroid cells. Both TBII and TSAb titers were lower in euthyroid Graves' ophthalmopathy than in hyperthyroid Graves' disease. Serum TSH levels frequently became low in patients considered as euthyroid upon the first examination as well as in Graves' patients in remission, reflecting preceding or mild hyperthyroidism. In follow-up studies, these patients with mildly elevated thyroid hormone levels and low TSH levels seldom reached a state of persistent hyperthyroidism, when TBII was negative or only weakly positive.

Adult↗

PubMed1990

[Study by I-123-IMP-SPECT before and after surgery for craniosynostosis].

Single photon emission computed tomography with N-isopropyl-p-[I-123]iodoamphetamine was performed in 13 cases of craniosynostosis before and after surgery. Of 13 cases, 8 cases (62%) showed focal low perfusion area on preoperative study. Four of seven cases (57%) with brachycephaly showed low perfusion areas in either of frontal lobes, occipital lobes, and cerebellum. Besides, two patients with scaphocephaly and one with plagiocephaly showed low perfusion area in unilateral cerebral hemisphere. Two Crouzon disease cases showed no focal low perfusion area, but an Apert disease showed low perfusion areas in both frontal lobes, cerebellum, as well as left occipital lobe. Corresponding CT and MRI showed no focal abnormality in any of these cases. These low perfusion areas were diminished or disappeared after surgical treatment in 6 cases (75%). We concluded that the I-123-IMP-SPECT is considered to be a useful index for the evaluation of functional recovery after surgery in cases with craniosynostosis.

Amphetamines↗

PubMed1989

A human homologue of the yeast GST1 gene codes for a GTP-binding protein and is expressed in a proliferation-dependent manner in mammalian cells.

A human homologue (GST1-Hs) of the yeast GST1 gene that encodes a new GTP-binding protein essential for the G1-to-S phase transition of the cell cycle was cloned from the cDNA library of human KB cells. The GST1-Hs cDNA contained a 1497 bp open reading frame coding for a 499 amino acid protein with mol. wt 55,754 and with the amino acid sequence homologies of 52.3 and 37.8% to the GST1 protein and polypeptide chain elongation factor EF1 alpha respectively. The regions potentially responsible for GTP binding and GTP hydrolysis were conserved in the GST1-Hs protein as well. When expressed in yeast cell, the GST1-Hs gene could complement the ts phenotype of yeast gst1 mutant. GST1-Hs and its mouse homologue were expressed in human fibroblasts and in various mouse cell types respectively, at relatively low levels in their quiescent states, and the level of those expressions increased rapidly, prior to the onset of DNA replication and the total RNA synthesis, when human or mouse fibroblasts were progressed out of the growth-arrested state by the addition of serum. A possible role of GST1-Hs in mammalian cell growth is discussed.

Amino Acid Sequence↗

PubMed1989

DNA primase-DNA polymerase alpha assembly from mouse FM3A cells. Purification of constituting enzymes, reconstitution, and analysis of RNA priming as coupled to DNA synthesis.

The mouse DNA primase-DNA polymerase alpha complex can be resolved with buffer containing 50% ethylene glycol (Suzuki, M., Enomoto, T., Hanaoka, F., and Yamada, M. (1985) J. Biochem. (Tokyo) 98, 581-584). The dissociated primase and DNA polymerase alpha have been purified sufficiently that there was no cross-contamination with each other. By the use of thus isolated DNA primase and DNA polymerase alpha in addition to DNA primase-DNA polymerase alpha complex, we have studied primer RNA synthesis and DNA elongation separately as well as the coupled reaction of the initiation and elongation of DNA chains. In the absence of deoxyribonucleoside triphosphates, the isolated primase synthesized oligoribonucleotides of an apparent length of 7-11 nucleotides (monomeric oligomer) and multiples of a modal length of 9-10 nucleotides (multimeric oligomer) and fd phage single-stranded circular DNA. Monomeric and dimeric oligomers were synthesized processively, and trimeric and larger oligomers were produced by repeated cycles of processive synthesis. The primase complexed with DNA polymerase alpha mainly synthesized monomeric and a small amount of dimeric oligomers. In the presence of deoxyribonucleoside triphosphates at concentrations above 10 microM, the DNA primase-DNA polymerase alpha complex exclusively synthesized monomeric oligomers only, which were utilized as primers for DNA synthesis. On the other hand, the products synthesized by the isolated primase were qualitatively unchanged as compared with those synthesized in the absence of DNA precursors. When the synthesis of oligomers by the isolated primase was coupled with DNA elongation by the addition of the primase-free DNA polymerase alpha, the synthesis of dimeric oligomers was inhibited as a result of efficient DNA elongation from monomeric oligomers.

Animals↗

PubMed1989

Infrequent activation of K-ras, H-ras, and other oncogenes in hepatocellular neoplasms initiated by methyl(acetoxymethyl)nitrosamine, a methylating agent, and promoted by phenobarbital in F344 rats.

Fischer 344/Ncr rats of both sexes were subjected to partial hepatectomy and then initiated 21-24 h later by a single injection of methyl(acetoxymethyl)nitrosamine at 0.1 mmol/kg body weight via the portal vein. Beginning 3 weeks later, development of hepatocellular neoplasms in initiated rats was promoted by feeding 0.05% phenobarbital (PB) in the diet. Not only intrahepatic lesions but also a variety of extrahepatic tumors were induced. High-molecular-weight DNAs were prepared from 67 samples of grossly normal liver containing multiple preneoplastic foci/areas of microscopic dimensions, 137 hepatocellular adenomas (nodules), 93 hepatocellular carcinomas (HCC), 10 cholangiomas, and 25 extrahepatic tumors in 95 rats and tested for transforming activity in the NIH 3T3 transfection assay. DNA preparations from 7 of 93 HCCs, 2 of 10 cholangiomas, 2 of 137 nodules, 1 histiocytic sarcoma, and 1 thyroid carcinoma were positive in the transfection assay. Southern blot analysis showed that NIH 3T3 transformants induced by DNA from 5 HCCs, 1 hepatocellular adenoma, 1 cholangioma, 1 histiocytic sarcoma, and 1 thyroid carcinoma contained an activated K-ras gene of rat origin. Rat-derived H-ras was identified in transformants from 2 additional HCCs and rat c-raf from 1 hepatocellular adenoma. The transforming gene from one cholangioma showed no sequence homology to the ras genes, neu, or c-raf. Immunoprecipitation analysis of ras Mr 21,000 protein in 11 transformants indicated that, based upon protein electrophoretic mobilities, activation of the ras genes consistently resulted from mutations in codon 12 of these genes. Selective oligonucleotide analysis revealed that a G----A transition in the second base of codon 12 of K-ras was present in the 9 K-ras-positive transformants and also in DNAs prepared from the original tumors. In contrast, oligonucleotide hybridization experiments with DNAs from 35 hepatocellular tumors that were negative in transfection assays revealed the presence of mutant K-ras in 1 of 15 HCCs; no mutation could be detected in 20 transfection-negative adenomas. The infrequency of detection of a specific oncogene, more frequent detection of oncogenes in malignant tumors, and failure to observe activated oncogenes in preneoplastic lesions suggest that activation of ras oncogenes may occur as a late and infrequent event in the evolution of some rat hepatocellular neoplasms and that mutation of a specific ras locus is not an obligatory early event in the genesis of these neoplasms.

Animals↗