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T Okazaki

Publications and source records attributed to T Okazaki.

At least 181 records · Page 10Linked to original sources
PubMed1996

A replication-enhancing element with transcriptional silencer activity in autonomously replicating human chromosomal fragments.

We have identified specific nucleotide sequences involved in autonomous replication of human chromosomal fragments in human cells. Nested deletion analysis of a 10.2-kb long human chromosomal fragment showed that replication efficiency of the fragment was reduced to about 50% by loss of a short specific segment. Deletions outside the segment reduced the replication efficiency depending on their lengths. By introducing linker substitutions, we found that the distinct segment required for the efficient replication consisted of an 18-bp sequence, named REE1 (Replication Enhancing Element 1). Single or tandem copies of REE1 alone had no significant replication activity, but they stimulated replication of human chromosomal DNA fragments. We found, in addition, that the REE1 sequence inserted at a site 2.7 kb upstream of the SV40 early promoter caused repression of transcription from the promoter, suggesting that REE1 had a transcriptional silencer activity. Introduction of linker substitutions into the REE1 indicated that the nucleotide sequences required for the repression of transcription were the same as those for enhancement of replication. Thus, REE1 is responsible for both enhancement of replication and repression of transcription.

Base Sequence↗
PubMed1996

Identification of five embryonic hemoglobins of rat and ontogeny of their constituent globins during fetal development.

Hemoglobins of rats switch from an embryonic to an adult type during fetal development. However, very little is known about the structures and molecular species of hemoglobins occurring in the fetal life of rats. In the present study we isolated five embryonic hemoglobins, designated E1, E2, E3, E4, and E5, from the blood of rat fetuses on day 14 of gestation by ion exchange chromatography. Reverse-phase high performance liquid chromatography revealed that these hemoglobins each consist of two kinds of globins: E1(11 alpha:epsilon 1), E2(1 alpha: epsilon 1), E3(zetta: epsilon 1), E4(1 alpha: epsilon 3), and E5(zetta: epsilon 3), respectively. The complete amino acid sequences of the zetta, epsilon 1, and epsilon 3 globins were determined. The zetta globin showed characteristic features common in alpha-type embryonic globins of known species in that the N-terminus is blocked and the amino acid at position 38 is Gln. epsilon 1 and epsilon 3 are beta-type embryonic globins, sharing 73.7% amino acid homology. Interestingly, they are more similar to the corresponding mouse beta-type embryonic globins, y and z, respectively, than to each other, implying that these globins have evolved orthologously from common ancestral proteins. It was also shown that the zetta, epsilon 1, and epsilon 3 globins are almost completely replaced by the adult type alpha and beta globins in the blood of rat fetuses by day 18 of gestation.

Amino Acid Sequence↗
PubMed1996

Centromere protein B of African green monkey cells: gene structure, cellular expression, and centromeric localization.

Centromere protein B (CENP-B) is a centromeric DNA-binding protein which recognizes a 17-bp sequence (CENP-B box) in human and mouse centromeric satellite DNA. The African green monkey (AGM) is phylogenetically closer to humans than mice and is known to contain large amounts of alpha-satellite DNA, but there has been no report of CENP-B boxes or CENP-B in the centromere domains of its chromosomes. To elucidate the AGM CENP-B-CENP-B box interaction, we have analyzed the gene structure, expression, biochemical properties, and centromeric localization of its CENP-B. The amino acid sequence deduced from the cloned AGM CENP-B gene was established to be highly homologous to that of human and mouse CENP-B. In particular, the DNA binding and homodimer formation domains demonstrated 100% identity to their human and mouse counterparts. Immunoblotting and DNA mobility shift analyses revealed CENP-B to be expressed in AGM cell lines. As predicted from the gene structure, the AGM CENP-B in the cell extracts exhibited the same DNA binding specificity and homodimer forming activity as human CENP-B. By indirect immunofluorescent staining of AGM mitotic cells with anti-CENP-B antibodies, a centromere-specific localization of AGM CENP-B could be demonstrated. We also isolated AGM alpha-satellite DNA with a CENP-B box-like sequence with CENP-B affinity. These results not only prove that CENP-B functionally persists in AGM cells but also suggest that the AGM genome contains the recognition sequences for CENP-B (CENP-B boxes with the core recognition sequence or CENP-B box variants) in centromeric satellite DNA.

Amino Acid Sequence↗
PubMed1996

Studies on 13C-phenacetin metabolism. II. A combination of breath test and urine test of in vivo metabolites in the diagnosis of liver disease.

We determined the optimum 13C-labeling position in phenacetin for use in a breath test to diagnose liver disease based on infrared spectroscopy detection of 13CO2 in exhaled air. ([1-13C]Ethoxy)phenacetin gave the best result. This compound was also employed in a urine test using 13C-NMR spectroscopy. In the urine test, healthy subjects gave a higher signal of phenacetin than of its metabolite, phenetidine, whereas in patients with liver disease the situation was the reverse. The combination of the breath and urine tests may be a valuable new tool for the diagnosis of liver disease.

Acute Disease↗
PubMed1996

Genetic relationship among three subspecies of Oncorhynchus masou determined by mitochondrial DNA sequence analysis.

It is generally accepted that there are 3 subspecies of Oncorhynchus masou in Japan, namely, Masu salmon (Oncorhynchus masou masou (Brevoort)), Amago salmon (O. masou ishikawae Jordan & McGregor), and Biwa salmon (O. masou rhodurus Jordan & McGregor or O. masou subsp. Kimura). Since the genetic relationship of these three taxa is not well known, there has been considerable confusion over their nomenclature. We have clarified the genetic relationship among these three taxa by partially sequencing their mitochondrial DNA. Sequences of 948 base pairs from the 3' region of the ATPase subunit 6 gene to the 5' region of the cytochrome oxidase subunit 3 gene were obtained for 20 individuals including wild Biwa salmon, wild and farmed Amago and Masu salmon. Furthermore, 2,162 base pairs from the 3' region of ATPase subunit 6 gene to the 5' region of NADH dehydrogenase subunit 4L gene were determined in 4 individuals. In total, there were 26 sites of base substitutions. The haplotypes of Masu salmon and Amago salmon were similar. On the other hand, 17 of the 26 sites had substitutions characteristic of Biwa salmon. A matrix of genetic distances and maximum parsimony analysis among the haplotypes indicated that Biwa salmon is genetically more distant from Masu and Amago salmon, than Masu salmon is from Amago salmon. This means that Biwa salmon diverged from the common ancestor of the Oncorhynchus masou complex before the divergence between Masu salmon and Amago salmon.

Animals↗
PubMed1996

A-72363 A-1, A-2 and C, novel heparanase inhibitors from Streptomyces nobilis SANK 60192. I. Taxonomy of producing organism, fermentation, isolation and structure elucidation.

Novel heparanse inhibitors, A72363 A-1, A-2, and C, were isolated from the culture filtrate of Streptomyces nobilis SANK 60192 by column chromatography on various resinous adsorbents, followed by preparative anion exchange HPLC. Spectroscopic studies revealed that they are diastereomers of siastatin B, a neuraminidase inhibitor.

Enzyme Inhibitors↗
PubMed1996

A new isopatulin derivative pintulin produced by Penicillium vulpinum F-4148 taxonomy, isolation, physico-chemical properties, structure and biological properties.

During our screening program of natural products from fungal metabolites for drugs effective against tumor cell lines, we discovered a new isopatulin derivative, pintulin, from the fermentation broth of Penicillium vulpinum F-4148. Pintulin shows weak activity against tumor cell lines, compared to that of adriamycin.

Antibiotics, Antineoplastic↗
PubMed1996

Mechanisms of glucocorticoid resistance in human leukemic cells: implication of abnormal 90 and 70 kDa heat shock proteins.

The unliganded glucocorticoid receptor is a multi-oligomer complex consisting of a ligand-binding protein with which two 90 kDa heat shock proteins (hsp90s) are associated. Upon binding of glucocorticoid to the receptor, the ligand-binding protein, which dissociated from hsp90s, enters the nucleus, binds to a specific site in DNA, and thus transmits signal(s). The 70 kDa heat shock protein (hsp70) also works as a molecular chaperone when the ligand-binding protein enters the nucleus. Regarding the mechanisms of glucocorticoid resistance, a decreased expression of glucocorticoid receptor and a mutant protein with low ligand binding affinity have been reported. In the present study, to address other mechanisms of glucocorticoid resistance, we examined the expression of hsp90 and hsp70 in addition to the number of glucocorticoid-binding sites and their affinity using glucocorticoid-sensitive and -resistant human leukemic cell lines. We showed that two of nine resistant cell lines with normal glucocorticoid-binding proteins express aberrant hsp90 and extremely low hsp70, while another seven resistant cell lines had decreased binding sites with normal hsps. These results suggest that there are at least two independent mechanisms of glucocorticoid resistance in human leukemic cell lines: the decreased ligand-binding sites and the abnormal hsps expression.

Antineoplastic Agents, Hormonal↗
PubMed1996

[A case of cardiac herniation following intrapericardial pneumonectomy after induction chemoradiotherapy].

A case of cardiac herniation following left intrapericardial pneumonectomy after induction chemoradiotherapy has been presented. Curative resection after induction chemoradiotherapy for central bronchogenic cancer may require intrapericardial pneumonectomy. Cardiac herniation through the pericardial defect is a fatal complication after a pneumonectomy unless pericardial repair should be done immediately. Closure of the pericardial defect with prosthetic patch, regardless of defect size, is always necessary for the prevention of the cardiac herniation following intrapericardial pneumonectomy after induction chemoradiotherapy.

Aged↗
PubMed1996

[A case of contralateral pneumothorax after right pneumonectomy].

A 46-year old man, who had a history of right pneumonectomy for pulmonary tuberculosis 28 years ago, was referred to our hospital for surgical treatment of contralateral pneumothorax. The patient underwent multiple excisions of bullae and parietal pleurectomy through the median sternotomy in order to save pulmonary function. The postoperative course was satisfactory as he could maintain preoperative pulmonary function. He returned to his work soon. We consider that the median sternotomy would be the most useful approach to save pulmonary function of patients who plan to undergo surgical treatment of contralateral pneumothorax after pneumonectomy.

Humans↗
PubMed1996

[Ceramide: a lipid mediator of apoptotic signal transduction].

Ceramide, the backbone of sphingolipids, is now recognized as an intracellular signal mediator of various cellular responses including cell differentiation and apoptosis. Tumor necrosis factor-alpha, anti-Fas antibody, anticancer drugs, radiation or heat shock induce apoptosis through generation of ceramide by activation of sphingomyelinase or ceramide synthase. The mechanism by which ceramide mediates apoptosis is unclear. We have found that ceramide induces the transcription of c-jun gene and increases the DNA binding activity of transcription factor AP-1 in human myelogenous leukemia HL-60 cells, and that activation of c-jun/AP-1 by ceramide(presumably through activation of Jun N-terminal kinase/stress-activated protein kinase) may be involved in the signaling pathway leading to apoptosis.

Apoptosis↗
PubMed1996

[Thoracic duct cyst--a case report].

The patient was a 59-year-old man with a 5-month history of cough, difficulty breathing, and palpitations while working. Initial examination at the internal medicine department of our hospital in August 1992 revealed a mass in the left side of the neck, and he was admitted for further examination and treatment. Preoperative investigations revealed a cystic lesion extending from the left neck area to the mediastinum. The mass was resected on August 13, 1992. Based on the intraoperative findings and postoperative histological examination, a diagnosis of thoracic duct cyst was made. The postoperative course was good and the patient was discharged after two weeks. This is extremely rare case, and the Trap door surgical approach proved useful for resection.

Humans↗
PubMed1996

Induction of apoptosis but not G1 arrest by expression of the wild-type p53 gene in small cell lung carcinoma.

Multiple genetic alterations, including inactivation of the p53 and RB genes and loss of heterozygosity on chromosome 3p, occur commonly in small cell lung carcinoma (SCLC). To assess the biological significance of p53 inactivation in the development of SCLC, tetracycline (Tc)-inducible p53 expression plasmids were introduced into a SCLC cell line, N417, in which the p53 gene as well as the RB gene was inactivated. In the absence (induced) of Tc, cells transfected with the wild-type p53 gene formed colonies in 29-58% of those with a mutant p53 gene. However, wild-type p53 genes were expressed in 0 of 43 transfectants, whereas mutant p53 genes were expressed in 75% (36/48) of the transfectants, suggesting that the growth of SCLC cells was suppressed by the expression of the wild-type p53 gene. Thus, wild-type p53-inducible clones were further established by transfection in the presence (repressed) of Tc. The in vitro growth was significantly suppressed by the induction of wild-type p53 expression, and apoptosis but not G1 arrest was observed within 24 h of p53 induction. These results strongly suggest that the restoration of the p53 function is sufficient to suppress the growth of SCLC cells in which other genetic alterations remain uncorrected, and that growth suppression by p53 is due to induction of apoptosis but not due to induction of G1 arrest through the RB pathway.

Apoptosis↗
PubMed1996

[Surgical strategy for the treatment of congenital biliary dilatation based on the location of intrahepatic bile duct dilatation].

Congenital biliary dilatation used to be regarded as having a good prognosis. However, some recent long-term follow-up studies have shown there to be quite a high incidence of postoperative intrahepatic bile duct (IHBD) stone formation. In most of the cases in whom IHBD stones form, the IHBD were found to be dilated as the time of initial surgery. Therefore, preoperative evaluation of IHBD dilatation using various imaging studies is extremely important. Surgically, in cases involving structure of the common hepatic duct (CHD) with dilatation above the structure, resection of the stricture and a wide hepaticointestinal anastomosis are strongly recommended. In cases where there is a stricture of the CHD or of the first branch of the IHBD, a reconstructive technique should be applied to dilate the stricture. Patients who have a structure and cystic dilatation of the IHBD above the second branch should be carefully followed-up postoperatively. Partial liver resection to remove the cyst may be required at the time of initial operation or at a later stage.

Bile Ducts, Intrahepatic↗
PubMed1995

Cloning and sequencing of the membrane-bound hydrogenase-encoding genes (hupS and hupL) from Pseudomonas hydrogenovora.

The membrane-bound hydrogenase (Hdg)-encoding structural genes were isolated from the hydrogen-utilizing bacterium Pseudomonas hydrogenovora (Ph). Nucleotide sequence analysis revealed two genes, hupS and hupL. The hupS gene encoded a 363-amino-acid (aa) polypeptide (40.4 kDa). The deduced aa sequence contained a putative 43-aa leader peptide sequence. The hupL gene started at 55 bp downstream from the stop codon of hupS and encoded a 622-aa polypeptide (69.3 kDa). The disruption of Ph hupS resulted in the loss of Hdg activity.

Amino Acid Sequence↗