Biomedical subjects

A Okamoto

Publications and source records attributed to A Okamoto.

At least 109 records · Page 6Linked to original sources

PubMed1997

[Function of the accessory pancreatic duct in the pancreaticobiliary maljunction].

We examined the function of the accessory pancreatic duct (APD) in 56 cases of the pancreaticobiliary maljunction. APD existed in 11 of 26 cases of the congenital choledochal cyst. The maximal diameter of APD was over 2 mm in 5 cases. Patency of APD was detected in 5 of 9 cases examined by dye-injection endoscopic retrograde pancreatography (ERP). APD existed in 15 of 30 cases of the pancreaticobiliary maljunction without biliary dilatation, and all APDs were less 2 mm in diameter. By dye-injection ERP, APD was patent in 4 of 13 cases. There was no significant relationship between patency of APD and associated biliary carcinoma in the cases of the pancreaticobiliary maljunction, but 5 cases of the congenital choledochal cyst with APD bigger than 2 mm in diameter had no biliary carcinoma. Amylase level of the bile in cases of the pancreaticobiliary maljunction with patent APD was frequently lower than that of cases with nonpatent APD. It is suggested that in cases of the pancreaticobiliary maljunction with patent APD, the incidence of carcinogenesis of the biliary tract might be lower, as the reflux of the pancreatic juice to the bile duct might be reduced by the flow of pancreatic juice from the upper dorsal pancreatic duct into the duodenum via the minor duodenal papilla.

Bile Ducts↗

PubMed1997

Studies on the mechanism of DNA sequence selective alkylation by kapurimycin A3 analogs.

We synthesized kapurimycin A3 ABCD-ring analog and compared the sequence selectivity for DNA guanine alkylation with those of kapurimycin A3 and ABC-ring analog. In the binding to DNA, it was shown by DNA unwinding assay that ABCD-ring analog binds tightly to DNA by intercalation into DNA duplex. DNA alkylation by ABCD-ring analog was sequence selective with an order of G*G > G*A > G*T > G*C. ABCD-ring analog has a stronger binding ability, a higher reactivity to DNA and a higher GG sequence selectivity in DNA alkylation than those to ABC-ring analog. The aromatic ring system plays an important role in the effective GG selective alkylation.

Alkylation↗

PubMed1996

Molecular analysis of the cyclin-dependent kinase inhibitor genes p15INK4b/MTS2, p16INK4/MTS1, p18 and p19 in human cancer cell lines.

Cyclin-dependent kinase-4 inhibitor genes (INK4) regulate the cell cycle and are candidate tumor-suppressor genes. To determine if alterations in the coding regions of the p18 and p19 genes, which are novel members of the INK4 family and if they correlate with the development of human cancer, 100 human cancer cell lines were analyzed. Two other INK4 gene family members, p15INK4b/MTS2 and p16INK4/MTS1 genes were also analyzed. Homozygous deletions of the p15INK4b/MTS2 gene were detected in 29 cancer cell lines. Thirty-five homozygous deletions and 7 intragenic mutations of the pl6INK4/MTS1 gene were also detected in these cell lines. Neither homozygous deletions nor intragenic mutations of the p18 and p19 genes were found except in an ovarian cancer cell line, SKOV3, harboring a single base pair deletion in exon 1 of p19. In p16INK4/MTS1 expression analysis, 5 cell lines with both authentic and alternative spliced p16INK4/MTS1 mRNA had no detectable p16INK4/MTS1 protein. These results suggest the hypotheses that either post-translational modification or enhanced degradation may be responsible for the lack of detection of the p16INK4/MTS1 protein. Using Western blot analysis, subsets of 26 human cancer cell lines were examined for p18 expression and 39 cell lines for p19 expression. All of these cell lines expressed the p18 or p19 protein, with the exception of SKOV3, which did not express p19. Therefore, the INK4 gene family may be divided into 2 groups. One group includes p15INK4b/MTS2 and p16INK4/MTS1, in which genetic and epigenetic alterations might contribute to the development of human cancers. The other group includes p18 and p19, in which somatic mutations are uncommon in many types of human cancer, and their role in human carcinogenesis and cancer progression is uncertain.

Carrier Proteins↗

PubMed1996

Intragenic mutations of the p16(INK4), p15(INK4B) and p18 genes in primary non-small-cell lung cancers.

The p15(INK4B), p16(INK4) and p18 genes are members of the gene family coding for inhibitors of cyclin-dependent kinases 4 and 6. p15(INK4B) and p16(INK4) are located at 9p21, a chromosomal region frequently deleted in many human neoplasms. To examine the role of these 3 genes in lung carcinogenesis, somatic mutations within the genes were analyzed by single-strand conformation polymorphism and DNA sequencing in 71 non-small-cell lung cancer (NSCLC) samples. Six somatic mutations in the p16(INK4) gene and 3 cases with a polymorphic allele were observed. Loss of heterozygosity in the p18 gene was found in 1 sample. We did not find any intragenic mutations in the p15(INK4B) or p18 genes. We conclude that p16(INK4) mutations play a role in the formation of some NSCLCs, whereas the involvement of p15(INK4B) and p18 is uncommon.

Base Sequence↗

PubMed1996

Effects of the addition of hyaluronate segments with different chain lengths on the viscoelasticity of hyaluronic acid solutions.

The effects of the addition of sodium hyaluronate segments (sHA) with different chain lengths on the viscoelasticity of high molecular weight sodium hyaluronate (HA) aqueous solutions were studied. The additive effects of sHA depended on the chain length of sHA. Shorter sHA decreased storage (G') and loss (G") moduli, whereas longer sHA increased both moduli. In physiological saline, the effects of the addition of sHA depended on the chain length of sHA, as in aqueous solutions, except that shorter segments did not decrease both moduli. The effects of the addition of monosaccharides, i.e., N-acetyl glucosamine (GlcNAc) and sodium glucuronate (GlcANa), were also studied. Although GlcNAc increased G' and G", GlcANa decreased both moduli. A shift factor "A," which depended on chain-length effects, a sugar effect, and a salt effect, was developed to explain these additive effects quantitatively.

Carbohydrate Sequence↗

PubMed1996

Suppression of growth in vitro and tumorigenicity in vivo of human carcinoma cell lines by transfected p16INK4.

The function of p16INK4 as a putative tumor suppressor gene was examined by investigating its ability to inhibit the growth of cancer cell lines in vitro and tumor formation in vivo. A p16INK4 cDNA expression vector was transfected into five human cancer cell lines that varied in their p16INK4 and retinoblastoma (Rb) status. Suppression of colony-forming efficiency was seen in four cell lines. Of two cell lines wild type for p16INK4 but null for Rb protein expression, one (Hep 3B) showed inhibition of colony formation, whereas the other (Saos-2) did not. This observation may demonstrate involvement of p16INK4 independent of Rb. The transfected p16INK4 gene was frequently selected against and lost during continued growth in vitro. When compared to the colon carcinoma cell line (DLD-1),p16INK4-transfected DLD-1 clone 1 cells were less tumorigenic in athymic nude mice. Tumors arising from p16INK4-transfected DLD-1 clones, which were growth suppressed in vitro, either lost the integrated exogenous p16INK4 or expressed reduced amounts of p16INK4 protein. Therefore, p16INK4 was also selected against during tumor formation in vivo. These data are consistent with the hypothesis that p16INK4 is a tumor suppressor gene.

Animals↗

PubMed1996

Neuroendocrine differentiation in pancreatic duct carcinoma special emphasis on duct-endocrine cell carcinoma of the pancreas.

To evaluate the significance of neuroendocrine differentiation in duct carcinoma of the pancreas, we investigated 79 pancreatic carcinomas, applying histochemistry and immunohistochemistry (chromogranin A, Leu-7, synaptophysin and neuron-specific enolase (NSE), and correlated the morphologic differentiation pattern with clinicopathological characteristics. There were two types of neuroendocrine differentiation: scattered (n = 23) and diffuse (n = 3). The scattered type of pancreatic duct carcinoma contained scattered endocrine cells amounting to less than 10% of the neoplastic cells and was seen more frequently in well-differentiated carcinomas. There was no characteristic clinical feature found in the scattered type when compared with the tumors devoid of endocrine cells (n = 53). In contrast, the diffuse type showed diffuse immunostaining with NSE and synaptophysin in tumor cells and dense core granules ultrastructurally. These tumors showed a greater hypervascularity in angiography (p < 0.01) and the patients had relatively longer survival (33.3 months, p < 0.05) than unresectable cases of other histological types of pancreatic cancer. Two types of neuroendocrine differentiation (scattered and diffuse) existed in pancreatic ductal carcinoma. The diffuse type (Duct-Endocrine Cell Carcinoma of the Pancreas) showed synchronous duct and endocrine differentiation and particular clinical features.

Adenocarcinoma↗

PubMed1996

An aspartate aminotransferase from an extremely thermophilic bacterium, Thermus thermophilus HB8.

The aspartate aminotransferase gene (AspAT, EC 2.6.1.1) of an extremely thermophilic bacterium, Thermus thermophilus HB8, was cloned and sequenced, and its gene product was overproduced. The purified T. thermophilus AspAT was stable up to about 80 degrees C at neutral pH. T. thermophilus AspAT was strictly specific for acidic amino acid substrates, such as aspartate, glutamate, and the respective keto acids. The gene coding for T. thermophilus AspAT showed that it comprised 1,155 bp with a high G+C content (70 mol%), and encoded a 385-residue protein with a molecular weight of 42,050. The amino acid sequence of T. thermophilus AspAT deduced from its gene showed about 15, 46, and 29% homology with those from Escherichia coli, Bacillus sp. YM-2, and Sulfolobus solfataricus, respectively. When the amino acid sequence of T. thermophilus AspAT was compared with that of E. coli AspAT, the number of Cys was found to have decreased from 5 to 1, that of Asn from 23 to 9, that of Gln from 16 to 8, and that of Asp from 20 to 13, all of which are known to be relatively labile at high temperatures. Conversely, the number of Pro was increased from 15 to 25, Arg from 22 to 32, and Glu 27 to 37. As shown by the E. coli AspAT structure, there was a marked tendency for the extra prolyl residues to be located around the surface of the molecule. This was quite different from that in the case of RecA protein, which shows an increased number of prolyl residues in the interior of its molecule. Different strategies of different proteins as to prolyl contribution to thermostability have been suggested. Despite the high degree of conservation of active-site residues, Arg292 in E. coli AspAT, which interacts with the distal carboxylate of the substrate, was not found in T. thermophilus AspAT. Arg89 may complement the function of Arg292.

Amino Acid Sequence↗

PubMed1996

Isolation and characterization of the human chromosomal gene for prostacyclin-stimulating factor.

Prostacyclin-stimulating factor (PSF) is a protein which acts on vascular endothelial cells and stimulates the production of prostacyclin. Recently, we were able to purify PSF from the conditioned medium of cultured human diploid fibroblasts and clone PSF cDNA. In this study, we screened a human genomic library and isolated genomic clones to determine the structure of the human chromosomal PSF gene. By determining the nucleotide sequence and transcription initiation site of this gene, we found that it comprises 5 exons and 4 introns. Southern hybridization analysis indicated the presence of a single copy of the PSF gene per haploid set of chromosomes. The 300 bp upstream of the transcription initiation site had a very high GC content, and 7 binding sites for the transcription regulating factor Sp1 were present.

Base Sequence↗

PubMed1996

Japan's financing system for health care of the elderly.

The multiplicity of Japan's health insurance system fails to achieve equality among the different insurance groups of the sharing of the financial burden. This "horizontal" inequality is effectively offset by a unique redistribution mechanism established in 1982. However, there is no reserve fund so that savings can be accumulated for the greater financial need in the future. This will inevitably lead to a heavier financial burden for the future working generation or more utilization of the personal assets of the elderly. How to achieve "vertical" or intergenerational equality in financing the cost of health care for the elderly is the biggest social policy challenge for Japan.

Aged↗

PubMed1996

[Molecullar structure and function of the p16/INK4a/CDKN2/MTS1 and the INK4 family, and their association with carcinogenesis].

The p16INK4a was isolated as a gene which binds and inhibits the cyclin-dependent kinase 4. Other laboratories reported that the isolated gene frequently homozygously deleted within chromosome 9p21 was the p16INK4a. The p16INK4a gene was thought be a hot gene like the p53 gene at the time. Nevertheless, the gene was thought to be a false tumor suppressor gene due to the low incidence the alterations of the gene in various surgical tumor samples. Since then, there have been a lot of reports supporting that p16INK4a is a really tumor suppressor gene including the reports on the high incidence of p16INK4a alterations in some kinds of tumors, on the higher incidence of p16INK4a alterations in the metastatic tumors than that of the primary tumors, on the G1 arrest of p16INK4a lack cells transfected with p16INK4a cDNA, and on the inactivation of p16INK4a gene by hypermethylation. Therefore, the p16INK4a gene has become the tumor suppressor gene, lately. Moreover, the INK4 family including p15INK4b, p18INK4c, and p19INK4d was isolated. These reports taken together, p16INK4a and INK4 family might play important roles in the genesis and development of cancer.

Amino Acid Sequence↗

PubMed1996

Concentrations of vascular endothelial growth factor in the sera of normal controls and cancer patients.

Vascular endothelial growth factor (VEGF) is known to play crucial roles in tumor angiogenesis. We have investigated the circulating level of VEGF in sera from cancer patients as well as from healthy normal controls using a sensitive enzymatic immunoassay. Immunoreactive VEGF proteins were detectable in normal sera, and the cutoff level was determined to be 180 pg/ml. In examined patients with all types of cancer, including breast, gastrointestinal, hepatobiliary, and lung cancer, an aberrant increase in the circulating level of VEGF was detected. For example, in 137 primary breast cancer patients, 12 (8.8%) showed an aberrant increase in VEGF levels. This aberrant expression of VEGF in sera was significantly associated with the progression of the disease, and with VEGF protein expression in tumor tissues. In addition, a Western blot analysis confirmed the presence of the VEGF165 form in sera from a patient with recurrent breast cancer. It was concluded that VEGF was detectable in normal sera, and its level was increased in some populations of cancer patients. A positive angiogenesis regulator, VEGF might function as an endocrine growth factor, particularly for solid tumors.

Adult↗

PubMed1995

Mutations in the p16INK4/MTS1/CDKN2, p15INK4B/MTS2, and p18 genes in primary and metastatic lung cancer.

We examined the genomic status of cyclin-dependent kinase-4 and -6 inhibitors, p16INK4,p15INK4B, and p18, in 40 primary lung cancers and 31 metastatic lung cancers. Alterations of the p16INK4 gene were detected in 6 (2 insertions and 4 homozygous deletions) of 22 metastatic non-small cell lung cancers (NSCLCs; 27%), but none were detected in 25 primary NSCLCs, 15 primary small cell lung cancers (SCLCs), or 9 metastatic SCLCs, indicating that mutation in the p16INK4 gene is a late event in NSCLC carcinogenesis. Although three intragenic mutations of the p15INK4B gene were detected in 25 primary NSCLCs (12%) and five homozygous deletions of the p15INK4B gene were detected in 22 NSCLCs (23%), no genetic alterations of the p15INK4B gene were found in primary and metastatic SCLCs. The p18 gene was wild type in these 71 lung cancers, except 1 metastatic NSCLC which showed loss of heterozygosity. We also examined alterations of these three genes and expression of p16INK4 in 21 human lung cancer cell lines. Alterations of the p16INK4 and p15INK4B genes were detected in 71% of the NSCLC cell lines (n = 14) and 50% of the NSCLC cell lines (n = 14), respectively, but there were none in the 7 SCLC cell lines studied. No p18 mutations were detected in these 21 cell lines. These results indicate that both p16INK4 and p15INK4B gene mutations are associated with tumor progression of a subset of NSCLC, but not of SCLC, and that p15INK4B mutations might also be an early event in the molecular pathogenesis of a subset of NSCLC.

Base Sequence↗

PubMed1995

Reduced neck movement after operations for cervical spondylotic myelopathy.

Complaints resulting from reduced neck movements were investigated in 50 patients who had operations for cervical spondylotic myelopathy. Seventy per cent had difficulty in performing 11 basic movements of daily living. Lateral bending or rotation were more difficult than flexion and extension. To look backwards was the most difficult movement. Complaints were highest among those in whom more than three levels of fusion had been carried out.

Activities of Daily Living↗

PubMed1995

Reactivity of the co-type and baa3-type cytochrome c oxidases from Pseudomonas aeruginosa with different endogenous cytochromes c.

The reactivity between different cytochromes c purified from Pseudomonas aeruginosa cells grown aerobically in the absence of nitrate and isolated cytochromes co and baa3 was determined. The P. aeruginosa cytochrome co reacted most rapidly with the membrane-bound cytochrome c-551 among three c-type cytochromes analyzed, whereas the cytochrome baa3 reacted best with the membrane-bound cytochrome c-555. The results indicated that two terminal electron transfer systems are present in aerobic P. aeruginosa: one contains the cytochrome c-551 and cytochrome co, and the other contains the cytochrome c-555 and cytochrome baa3.

Aerobiosis↗

PubMed1995

Anti-hypertensive substances in fermented soybean, natto.

Natto is a traditional Japanese fermented food made by fermenting boiled soy beans with Bacillus natto. Its contents of inhibitors against the angiotensin converting enzyme (ACE, EC3.4.15.1) were investigated. Relatively strong inhibitory activity (IC50: 0.4 mg/ml, 11.8 inhibition units/g natto) was detected in natto extracts and the inhibitory activity observed in the viscous fraction was more potent than in the bean extract. Two groups of inhibitors in the viscous material, high and low molecular weight inhibitors, were resolved by dialysis test. The inhibitor of high molecular weight was a protein with low IC50 value (0.12 mg/ml). The two types of low molecular weight inhibitors were detected in ethanol extracts (IC50: 0.53 mg/ml and 0.95 mg/ml) and they were found to be stable over a wide range of pH and temperature up to 100 degrees C. They were different in the mode of ACE inhibition. One is competitive, and the other noncompetitive against the hydrolysis of Bz-Gly-His-Leu by ACE.

Amino Acid Sequence↗

PubMed1995

A case of pleomorphic carcinoma of the pancreas showing sequential histological change by immunohistochemical study.

Pleomorphic carcinoma of the pancreas is a rare, histologically characterized pancreatic tumor with a rapid and fatal course. We report a case of a resected pleomorphic carcinoma located in the body of the pancreas in a 61-yr-old male. Histological analysis of the resected specimen revealed the coexistence of pleomorphic carcinoma with adenocarcinoma, but the recurrent tumors at autopsy 20 mo later were only of the adenocarcinomatous type. Cells in the adenocarcinomatous component showed a diffuse reactivity for CA19-9, CEA, and cytokeratin, and a focal reactivity for vimentin. In contrast, vimentin was diffusely expressed in pleomorphic lesion. Adenocarcinoma at autopsy expressed CA19-9, CEA, and cytokeratin, but not vimentin. These findings suggest that the recurrent adenocarcinoma may have developed as a consequence of sequential change in the nature of the tumor.

CA-19-9 Antigen↗

PubMed1995

Genetic heterogeneity of chromosome 11 associated with tumorigenicity in HeLa D98-OR cells.

D98-OR is a tumorigenic subline of HeLa cells. We isolated nine subclones from D98-OR and examined their tumorigenicity in nude mice. Three, two, and four subclones were highly, weakly, and nontumorigenic, respectively. While they all contained two copies of intact chromosome 11, restriction fragment length polymorphism (RFLP) analysis revealed that the allelic composition of this chromosome differed among them. The highly tumorigenic subclones were heterozygous for the 11p and 11q loci, whereas those that were weakly or nontumorigenic were homozygous. Thus, the loss of one chromosome 11 with the duplication of another associated with the reduced tumorigenicity. Taken together with previous reports, our results indicate that a putative tumor suppressor gene on chromosome 11 controls tumorigenic expression in a gene dosage-dependent manner, and most importantly, suggested that the functional inactivation of the gene requires only a "one-hit" mutation.

Animals↗