Search PubMed⌕ Search

Biomedical subjects

M Takimoto

Publications and source records attributed to M Takimoto.

At least 73 records · Page 4Linked to original sources
PubMed1993

Transactivating function of integrated hepatitis B virus.

HBV DNAs are often found in integrated forms in human hepatocellular carcinoma (HCC). Discovery of a transactivation function coded by a limited region of the HBV genome has promoted us to survey our collection of HBV integrants with flanking cellular sequences, asking whether they might exhibit a transactivation function. In transient cotransfection assays using the HepG2 cell line, six out of the twelve integrants showed transactivation effects on the expression of cellular genes such as c-fos. These results strongly demonstrate that the transactivating effects of integrated HBV DNA are widely distributed, and some of these effects might be correlated to hepatocarcinogenesis.

Carcinoma, Hepatocellular↗
PubMed1993

Myeloperoxidase expression in CD34+ normal human hematopoietic cells.

Bone marrow (BM), adult peripheral blood (aPB), and umbilical cord blood (CB) samples contain small proportions of CD34+ cells that include virtually all hematopoietic progenitor cells. Myeloperoxidase (MPO) is considered to be selectively expressed in cells committed to granulomonocytic differentiation. Using flow cytometry and an antibody against MPO, we studied at which stage of normal hematopoietic differentiation CD34+ cells being to express MPO. We consistently observed a characteristic MPO/CD34 staining pattern and found that 35% +/- 9% of CD34+ BM cells express MPO. The MPO+ CD34+ subset and the CD33+ CD34+ subset were of similar size and overlapped considerably. MPO+ CD34+ cells expressed high levels of HLA-D molecules, were weakly CD71/transferrin receptor positive to negative, were CD45RA+ and lacked the CD45RO isoform of the leukocyte common antigen. Additionally, MPO+ CD34+ cells were on average larger in size than MPO- CD34+ cells. Virtually identical phenotypic features have previously been described for in vitro colony-forming granulomonocytic progenitor cells. In vitro clonogenic assays performed with MPO-enriched and MPO-depleted fractions of CD34+ BM cells performed by us also suggest, but do not formally prove, that at least a portion of MPO+ CD34+ cells have in vitro cluster (10 to 50 cells/colony) or colony-forming unit granulocyte-macrophage (> or = 50 cells/colony) forming capacity. CD34+ cells from CB and aPB resembled CD34+ BM cells in that considerable proportions of them coexpressed CD33. However, in contrast to BM, CD34+ cells from CB and aPB samples lacked significant MPO expression and, in line with this, the majority of them (CB, 59% +/- 7%; aPB, 66% +/- 5%) coexpressed CD45RO.

Adult↗
PubMed1993

Specific binding of heterogeneous ribonucleoprotein particle protein K to the human c-myc promoter, in vitro.

A homopurine/homopyrimidine-like sequence is found 100-150 base pairs upstream of the human c-myc promoter P1. This element, termed the CT-element, has been shown to augment expression from P1, and it serves as a positive transcriptional element when coupled to a heterologous promoter in vivo and in vitro. Synthetic oligonucleotides comprising this element were used to form DNA-protein complexes in electrophoretic mobility shift assays. By using conventional and affinity methods, 61- and 34-kDa proteins were shown to be associated with these complexes. Amino acid sequence analysis and immunological methods have identified these proteins as heterogeneous ribonucleoprotein particle (hnRNP) proteins K and A1. Surprisingly, hnRNP protein K binds to the pyrimidine-rich strand of the CT-element in a sequence-specific manner as well as to the double-stranded molecule. Cotransfection of vectors encoding hnRNP protein K in the sense or anti-sense orientations with reporter plasmids driven by wild-type or mutant CT-elements demonstrates that hnRNP protein K augments gene expression in a cis-element-dependent manner. Taken together, these results suggest that hnRNP protein K may play a role in the transcriptional regulation of the human c-myc gene.

Amino Acid Sequence↗
PubMed1993

Contraction of smooth muscle by activation of endothelin receptors on autonomic neurons.

Endothelin receptors, predominantly of the ETB type, were localized to cell bodies, processes, and varicosities of cholinergic and adrenergic intramural autonomic neurons that were present in primary cultures of guinea pig tracheal smooth muscle. Stimulation of the neuronal ETB receptor produced a tetrodotoxin-sensitive increase in the intracellular calcium concentration in neurons which was followed by contraction of the neighboring smooth muscle cells. These observations suggest that endothelins can induce smooth muscle contraction by means of a neuronally mediated mechanism, in addition to their direct actions on the smooth muscle.

Animals↗
PubMed1993

The prognostic significance of proliferating cell nuclear antigen, epidermal growth factor receptor, and mdr gene expression in colorectal cancer.

BACKGROUND: Proliferating cell nuclear antigen (PCNA), a proliferation marker, epidermal growth factor receptor (EGFR), a glycoprotein that plays a role in tumorigenesis by binding the mitogenic epidermal growth factor, and P-glycoprotein, the mdr gene product, are considered to be of prognostic relevance in different tumor types. Parameters that allow prediction of the course of disease in colorectal cancer would aid the development of improved treatment strategies. METHODS: Immunohistochemical staining was performed on paraffin-embedded sections of 82 colorectal adenocarcinomas and 18 lymph node metastases. EGFR and P glycoprotein expression was evaluated semiquantitatively; PCNA expression was analyzed quantitatively. RESULTS: An inverse relationship between the percentage of PCNA-positive cells and survival times could be demonstrated, survival differed significantly among the quartiles (P < 0.02). The median and range of the percentage of PCNA-positive cells in primary tumors and lymph node metastases were similar. The extent of EGFR expression also revealed significant differences concerning survival times; patients with more than 50% stained tumor cells had a poorer prognosis than those with less than 50% stained cells. P-glycoprotein expression was found to have no influence on survival. CONCLUSIONS: Knowledge of the percentage of PCNA-positive cells could be especially helpful in deciding whether to treat patients with localized disease further because adjuvant chemotherapy affects mainly dividing cells and should, therefore, be more successful in tumors with high proliferative activity.

Adult↗
PubMed1993

Transactivation of cellular promoters by an integrated hepatitis B virus DNA.

A new Hepatitis B virus(HBV) DNA integrant clone DA2-6, isolated from a human hepatocellular carcinoma(HCC) genomic library, was tested for its ability to transactivate expression of other genes. DA2-6 consists of 3.7 kb flanking cellular sequences and an integrated 2.8 kb HBV DNA which covers the region of preS, S, and the 3' truncated X. Using a chloramphenicol acetyltransferase (CAT) assay, a number of cellular and viral promoters were transactivated by DA2-6, and the spectrum of transactivational effect was the same as that by the wild type X gene of the virus. Deletion mutant analyses indicated that the transactivation function of DA2-6 is expressed by the region that encodes a truncated X-cell fusion product.

Amino Acid Sequence↗
PubMed1993

Respiratory syncytial virus infection in lower respiratory tract and asthma attack in hospitalized children in North Hokkaido, Japan.

Respiratory syncytial virus (RSV) infection is severe and life-threatening in some infants. To investigate the epidemiology of RSV infection in hospitalized children in North Hokkaido, Japan, we tried to detect RSV antigen in nasopharyngeal aspirates (NPA) from those children with lower respiratory tract infection (LRTI) and asthma attack. From April 1991 to March 1992, 317 patients were hospitalized in our pediatric ward for the treatment of LRTI and asthma attack. The presence of RSV antigen in NPA taken from 283 patients (89.3%) were examined by enzyme immunoassay. RSV antigen was detected in 88 patients (31.1%). RSV LRTI were noted throughout the year, and the epidemic peak was observed in November and December. There was no significant correlation between the RSV antigen positive rate and mean temperature. RSV played an important role in LTRI in children in North Hokkaido, Japan. RSV LRTI in North Hokkaido was not rare in summer, indicating that RSV was transmitted commonly among children throughout the year.

Adolescent↗
PubMed1992

[Athyreotic congenital hypothyroidism in two sisters].

Two sisters with athyreotic congenital hypothyroidism are described. This is the fifth report on athyreotic congenital hypothyroidism in siblings. The elder sister is 14 years old and the younger one is 12. The parents have no consanguinity or family history of thyroid disease. Both of the patients were born before the start of neonatal screening tests for congenital hypothyroidism. After birth, they had jaundice, abdominal distention and constipation, which are typical symptoms of congenital hypothyroidism. Serum T4 levels were decreased, and the serum TSH levels were markedly increased. Therefore we diagnosed them as having congenital hypothyroidism. They have received replacement therapy with thyroxine since diagnosis and have shown normal development physically and psychologically. They were tested for thyroid scintigram when the elder sister was 9 years old and the younger one was 7. 123I thyroid uptakes were 0.69% and 0.64%, respectively. The thyroid scans demonstrated no focus of accumulation of 123I. They do not have trapping defect of iodine, because 123I ratio of saliva and serum were 41.3 and 46.3, respectively. From these results, we diagnosed them as having athyreotic congenital hypothyroidism. They and their mother do not have any antithyroid antibodies. We suppose that some genetic factor is responsible for the athyreotic congenital hypothyroidism.

Child↗
PubMed1992

Autocrine receptors for endothelins in the primary culture of endothelial cells of human umbilical vein.

Human umbilical vein endothelial cells (HUVECs) in primary culture produced and secreted endothelin 1 (ET-1) actively. Specific binding of [125I]ET-1 to these cells was not detectable because of the saturation of ET receptors with endogenously produced ET-1. However, addition of phosphoramidon, an inhibitor of ET-converting enzyme, to the medium reduced the production of ET-1 and thus the receptors on HUVECs were made available for exogenously added [125I]ET-1. Binding studies using phosphoramidon-treated HUVECs indicated the existence of a non-isopeptide-selective type (ETB) of ET receptor with a Kd of 17 pM. This receptor is thought to be involved in ET-induced vasodilation in an autocrine manner in vivo.

Binding Sites↗
PubMed1992

Antigenic analysis of human haemopoietic progenitor cells expressing the growth factor receptor c-kit.

The cell surface molecule encoded by the protooncogene c-kit has recently been identified as the receptor for a growth factor variously termed stem cell factor (SCF), mast cell growth factor or steel factor. Using the c-kit antibody 17F11 we analysed, in triple staining experiments, the surface molecule profile and scatter characteristics of c-kit+CD34+ human haemopoietic progenitor cells. In 10 normal bone marrow samples we found 19-51% of CD34+ bone marrow progenitor cells to coexpress c-kit. These c-kit+CD34+ bone marrow cells turned out to represent a phenotypically heterogeneous population. A considerable proportion coexpressed CD33 (52 +/- 23%), and/or CD71 (62 +/- 26) antigens, marker molecules previously shown to be expressed by committed in vitro colony forming cells but not by their precursors. In line with a relatively differentiated phenotype c-kit+CD34+ cells also gave rise to on average higher forward and right-angle light scattering signals. The proportions of CD38 and/or HLA-D expressing cells were similar in the c-kit+ and in the c-kit- subsets of CD34+ progenitor cells. Coexpression of CD19 was found to be less frequent in the c-kit+ (4 +/- 5%) as compared to the c-kit- (17 +/- 14%) fraction of CD34+ cells. CD7+ CD34+ bone marrow cells were hardly detectable and their numbers too low to allow further subdivision in c-kit+ and c-kit- subsets.

Antigens, CD↗
PubMed1992

[Characteristics of group A streptococci isolated from children with non-suppurative complication or severe infection].

We determined the characteristics of group A streptococci isolated from 29 sporadic cases with non-suppurative complication or severe infection during a 15-year period from 1977 to 1991. The clinical diagnoses of children included 4 patients with rheumatic fever, 2 with reactive arthritis, 2 with central nervous system complication, 5 with glomerulonephritis, 11 with Honoch-Schölein purpura, 4 with sepsis and 1 with empyema. Twenty-four strains were isolated from throat swabs, 4 from blood specimens and one from pleural fluid. M/T-serotypes and the number of isolates were as follows; 1/1:10, 3/3:1, 3.3R/3:3, 4/4:7, 5/NT:1, 12/12:3, 18/18:2, 62/12:1, NT/13:1. All 29 isolates had productivity for at least one of streptococcal pyrogenic exotoxins (SPEs) A, B and C. Two strains were positive for A, 2 for A and B, 3 for A, B and C, 9 for B and 13 for B and C. Of 11 isolates from patients with Henoch-Schönlein purpura, 7 and 2 strains were serotyped in M1 and M4, respectively, but none was in M12. Ten of 11 isolates were positive for SPE B or SPEs B and C.

Adolescent↗
PubMed1991

Spectroscopic studies on lambda cro protein-DNA interactions.

Spectroscopic (circular dichroism and fluorescence) and thermodynamic studies were conducted on lambda Cro-DNA interactions. Some base substitutions were introduced to the operator and the effects on the conformation of the complex and thermodynamic parameters for dissociation of the complex were examined. It was found that, (1) in the specific binding of Cro with DNA which has a (pseudo) consensus sequence, DNA is overwound, while in non-specific binding it is unchanged, or rather unwound; (2) substitution of central base-pairs or the introduction of a mismatched base-pair at the center of the operator reduces the extent of DNA conformational change on Cro binding and lessens the stability of the Cro-DNA complex, even though there is apparently no direct interaction between Cro and DNA at these positions; (3) stability of the complex increases with the degree of DNA conformational change of the same type during binding; (4) in some cases of specific binding, there are three states in the dissociation of the complex as observed by salt titration: two conformational states for the complex depending on salt concentration and, in non-specific binding, dissociation is a two-state transition; (5) the number of ions involved in interactions between Cro and 17 base-pair DNA is about 7.7 for NaCl titrations; (6) dissociation free energy prediction of the Cro-DNA complex by simple addition of the dissociation free energy change of a single base-pair substitution agrees with our experimental results when DNA overwinding occurs during binding, i.e. in specific binding.

Base Sequence↗
PubMed1990

[Growth rate of experimental colonic cancer in rats].

Colonic cancers were induced in rats by subcutaneous injection of 1,2-Dimethylhydrazine. Tumor growth patterns were estimated by means of a double contrast barium enema technique. Tumor growth was almost exponential and the average doubling time was 20 +/- 5 (m +/- S.D.) days, at which time three different types of tumor growth patterns: Constant type, decreasing type and reaccelerating type, were noted. Serial double contrast barium enema technique appeared to be an useful method of studying in vivo primary colonic cancer growth patterns in rats.

1,2-Dimethylhydrazine↗
PubMed1989

Thrombus formation on the aorta injured by angioplasty and its prevention with dilazep in atherosclerotic rabbits.

To estimate the effect of dilazep in preventing restenosis after a transluminal angioplasty, we have attempted an animal experiment in which the efficacy of drug was tested on an angioplastic injury superimposed on to atherosclerotic lesions. Using a modification of Block's method, atherosclerotic lesions first were made in the rabbit aorta by an initial ablation of the endothelium, followed by successive cholesterol feedings. Then, for our second step, an angioplastic injury was inflicted on the atherosclerotic lesions. The thirty two rabbits used were divided into 3 groups: those given dilazep (100 micrograms/kg i.v.), those given dipyridamole (100 micrograms/kg i.v.) and a control group that was given the same volume of 0.9% saline. The angioplastic area in which thrombi developed was semiquantitatively measured and compared among all three groups. The mean value of the thrombus area in the dilazep group was 60% smaller and the distribution pattern of the thrombus by size was found to be composed of smaller thrombi than those of the control group. Dipyridamole showed the same trend as did dilazep, but less effectively. Our animal model and semiquantitative evaluation method that we employed were found useful from the view point of an easy applicable and inexpensive methodology. Our results point towards the possible clinical use of dilazep in the future, so as to prevent thrombus formation, which seems to cause the restenosis phenomenon that often occurs in patients who have undergone a coronary angioplasty.

Angioplasty, Balloon↗
PubMed1989

fos/jun and octamer-binding protein interact with a common site in a negative element of the human c-myc gene.

A negative element has previously been localized to a 57-base pair segment approximately 300 base pairs upstream of the human c-myc promoter P1. Within this element, a 26-base pair region was protected in vitro from DNase I digestion with a HeLa cell nuclear factor(s). Two specific DNA-protein complexes were identified in gel retardation assays using HeLa cell nuclear extracts and an oligonucleotide probe spanning the footprinted region. Exonuclease and chemical footprint analyses suggested that the binding sites for both complexes are almost entirely overlapping. One of the complexes was eliminated by oligonucleotide competitors possessing known AP-1 binding sites. This same complex reacted strongly with anti-fos immunoglobulin suggesting a role for c-fos in governing c-myc expression. Precipitation of fos protein bound to c-myc DNA that was immobilized on beads confirmed the involvement of c-fos in a specific complex with the c-myc upstream sequence. In contrast, the other complex seen by the c-myc probe could not be competitively inhibited by AP-1 binding sites and was not affected by anti-fos antibody. Instead, this complex was efficiently eliminated by unlabeled oligonucleotides containing the octamer DNA motif found in immunoglobulin gene promoters. Purified octamer-binding proteins formed stable complexes with the 26-base pair c-myc sequences. These results demonstrate that degeneracy in the consensus recognition sequences of these distinct factors allows each of them to bind the c-myc negative element. The interaction of known transcriptional activators with a negative element suggests that the same factors can mediate both transcriptional activation and repression.

Base Sequence↗
PubMed1989

A FOS protein is present in a complex that binds a negative regulator of MYC.

Regulation of the human proto-oncogene MYC apparently plays an important role in cellular proliferation and the genesis of diverse tumors. Transcription from MYC is governed principally by two promoters known as P1 and P2. Previously we have detected a negative regulator of these promoters upstream of MYC. We now report that this regulator comprises no more than 26 bp of DNA, with sequence that resembles the regulators of at least two other genes, and we describe nuclear factors that interact with the regulator. Nuclear extracts from human cells form three distinctive complexes with the negative regulator. One of these complexes includes the product of the proto-oncogene FOS or an antigenically related protein, and the FOS protein may, in turn, be associated with the product of the proto-oncogene JUN. Similarly, FOS and JUN proteins produced by translation in vitro bind cooperatively to the negative regulator. These results raise the possibility that FOS and JUN participate in the regulation of MYC.

Animals↗