PubMed Health⌕ Search

Biomedical subjects

A Yasui

Publications and source records attributed to A Yasui.

At least 91 records · Page 5Linked to original sources
PubMed1992

Mitochondrial DNA repair by photolyase.

Photolyase genes of Saccharomyces cerevisiae and Escherichia coli were expressed in S. cerevisiae and photoreactivation in nuclei and mitochondria of the host cells was analyzed by determination of survival and petit rates. Yeast photolyase was able to repair mitochondrial DNA effectively, whereas E. coli photolyase could reduce only a small fraction of the petit rate produced by UV irradiation. Analysis using fusion between yeast photolyase and E. coli lacZ genes as well as a chimeric gene between yeast and E. coli photolyase genes suggests the importance of the protruding amino terminal region of the yeast photolyase for its transport into mitochondria. A significant similarity between the protruding amino termini of yeast photolyase and yeast uracil-DNA-glycosylase suggests a common functional importance of the terminal sequences for both DNA repair enzymes.

Amino Acid Sequence↗
PubMed1992

Serum calcium increases the incidence of arrhythmias during acetate hemodialysis.

We investigated the occurrence of arrhythmias during maintenance acetate hemodialysis (HD) using a 24-hour continuous electrocardiogram recording system. Three of 22 patients showed augmented increases in both ventricular premature beats and supraventricular premature beats during HD. When we changed the dialysate from one with a Ca2+ concentration of 1.75 mmol/L (3.5 mEq/L), to one with a Ca2+ concentration of 1.25 mmol/L (2.5 mEq/L), the elevation of serum Ca2+ concentration during HD was abolished and the increases in both ventricular premature beats and supraventricular premature beats were significantly decreased. The elevation of serum Ca2+ concentration during HD might induce either extracellular or intracellular increase in Ca2+ concentration in the heart and elicit either reentry- or triggered-activity types of arrhythmias during HD. The present results indicate that the dialysate with a lower Ca2+ concentration is advisable to use in patients with underlying cardiac diseases.

Acetates↗
PubMed1992

Changes in hepatic hemodynamics and oxygen consumption after partial hepatic congestion in dogs.

The effects of 66% hepatic congestion (group 2, n = 6) on liver blood flow and hepatic oxygen metabolism were investigated in anesthetized dogs using an ultrasonic transit time flowmeter. The results were compared with those for control dogs (group 1, n = 6) and for 60% hepatectomized dogs (group 3, n = 6) wherein almost the same amount of hepatic parenchyma was removed as was congested in group 2. Portal blood flow (PVF) in group 2 and group 3 decreased similarly to 60 and 63% of the baseline values, respectively (p less than 0.05). Cardiac output (CO) in group 2 and group 3 also decreased significantly in proportion to the decrease in PVF. Among the dogs in group 2, hepatic arterial blood flow (HAF) was fairly well maintained at 86% of the baseline value, despite the decrease of cardiac output, whereas the HAF in group 3 decreased to 49% of the baseline value at 1 h after hepatectomy. The calculated hepatic arterial resistance (HAR) in group 3 increased significantly due to the 60% loss of the hepatic arterial vascular bed. The HAR in group 2, by contrast, became lower than that in group 1, suggesting a compensatory decrease of HAR for the obstructed portal flow to the congested area. These results were well consistent with our angiographic findings (n = 3) that the portal flow to the congested segments was completely obstructed and the congested segments received only an arterial blood supply. The centrilobular hepatocytes of the congested segments showed marked vacuolar degeneration and the total hepatic oxygen consumption in group 2 was reduced (p less than 0.05). However, the decrease in oxygen consumption in group 2 was not so severe as in group 3 (p less than 0.05). These data suggest that some parts of the preserved congested segments were still viable and had the capacity of aerobic metabolism even 4 h after the ligation of the drainage vein of those segments. In this study, the importance of the hepatic arterial flow to the congested segment has been demonstrated. When the congested hepatic segment is to be preserved intraoperatively, care must be taken to maintain the hepatic arterial blood flow during the perioperative period.

Animals↗
PubMed1992

DNA repair pathways in mammalian cells analyzed by isolation of ACNU-sensitive Chinese hamster ovary cells.

1-[(4-amino-2-methyl-5-pyrimidinyl)methyl]-3-(2-chloroethyl)-3- nitrosourea hydrochloride (ACNU) causes chloroethylation of DNA strand followed by cross linking through an ethylene bridge. We recently isolated two ACNU sensitive mutants from mutagenized Chinese hamster ovary cells, and found them to be new drug sensitive recessive mutants (Hata et al. 1991). The O6-methyl guanine DNA methyl transferase (MT) activities of these cells were undetectable as the parental cell line, indicating that the sensitivity of the mutant cell lines to ACNU was not due to the decreased cellular level of this enzyme. By complementation analysis with the 7 established UV-sensitive CHO cell lines, one of the mutants, UVS1, turned out to complement their UV-sensitivity and, therefore, build a new complementation group among all the CHO cell lines ever reported. The other mutant, CNU1 showed hypersensitivity only to chlorethylating agents (ACNU, CCNU) and exhibited a slightly reduced unscheduled DNA synthesis (UDS) induced by UV. It is, therefore, suggestive that this mutant is defective in a specific step of DNA repair systems, which is important for the processing of DNA damages produced by ACNU. Only cell lines from the complementation group 1 and 4 out of 7 established complementation groups of UV-sensitive CHO mutants were more sensitive to ACNU than UVS1 and CNU1, indicating some steps of excision repair pathways as well as specific repair system play important roles in repairing ACNU-induced DNA damages.

Animals↗
PubMed1992

Cholangiocellular carcinoma in the caudate lobe with intraluminal growth in the extrahepatic bile duct.

A case of cholangiocellular carcinoma in the caudate lobe with intraluminal growth in the extrahepatic bile duct is reported. The main tumor in the caudate lobe was detected by computed tomography and angiography, and two intraluminal tumors at the hepatic hilus and at the root of the right posterior segmental duct were well demonstrated by cholangiography and percutaneous transhepatic cholangioscopy. Independent total caudate lobectomy with bile duct resection was performed. Cholangiocellular carcinoma of the liver with intraluminal growth in the extrahepatic bile duct is very rare and has not been reported in the literature. Independent caudate lobe resection requires a rather complicated technique. However, this method has the advantage of reducing to a minimum the hepatic volume to be resected, and is useful for poor-risk patients or for cases with localized carcinoma at the hepatic hilus.

Adenocarcinoma↗
PubMed1991

Cloning and functional characterization of a eucaryotic DNA photolyase gene from Neurospora crassa.

We cloned a genomic fragment of a photolyase gene from Neurospora crassa by polymerase chain reaction using synthesized oligonucleotide primers designed from the most conserved amino acid sequences among photolyases of various organisms. Using the cloned fragment as a hybridization probe we isolated a genomic fragment and cDNA clones encoding the complete photolyase gene of this organism. The amino acid sequence of the photolyase deduced from the determined nucleotide sequence indicates a protein consisting of 615 amino acid residues (Mr 69,971), which is most similar to that of Saccharomyces cerevisiae. Like yeast photolyase it contains a protruding amino terminus which is missing in photolyases of bacterial origin. Comparison of amino acids sequences among six photolyases suggests that the Neurospora crassa photolyase is more similar to photolyases of pterin type than those of deazaflavin type.

Amino Acid Sequence↗
PubMed1991

Role of cysteine residues in the activity of rat glutathione transferase P (7-7): elucidation by oligonucleotide site-directed mutagenesis.

To clarify the role(s) of thiol (sulfhydryl) groups of cysteine (Cys) residues in the activity of the rat glutathione transferase P (7-7) form (GST-P), a cDNA clone, pGP5, containing the entire coding sequence of GST-P (Y. Sugioka et al., (1985) Nucleic Acids Res. 13, 6044-6057) was inserted into the expression vector pKK233-2 and the recombinant GST-P (rGST-P) expressed in E. coli JM109. All four Cys residues in rGST-P were independently substituted with alanine (Ala) by site-directed mutagenesis, the resultant mutants as well as the rGST-P being identical to GST-P purified from liver preneoplastic nodules with regard to molecular weight and immunochemical staining. Since all mutants proved as enzymatically active towards 1-chloro-2,4-dinitrobenzene as liver GST-P, it was indicated that none of the four Cys residues is essential for GST-P activity. However, the mutant with Ala at the 47th position from the N-terminus (Ala47) became resistant to irreversible inactivation by 0.1 mM N-ethylmaleimide (NEM), whereas the other three mutants remained as sensitive as the nonmutant type (rGST-P). Ala47 was also resistant to inactivation by the physiological disulfides, cystamine or cystine, which cause mixed disulfide and/or intra- or inter-subunit disulfide bond formation. These results suggest that the 47-Cys residue of GST-P may be located near the glutathione binding site, and modulation of this residue by thiol/disulfide exchange may play an important role in regulation of activity.

Animals↗
PubMed1991

Unique characteristics of superoxide dismutase of a strictly anaerobic archaebacterium Methanobacterium thermoautotrophicum.

The superoxide dismutase (SOD) gene of Methanobacterium thermoautotrophicum (Takao, M., Oikawa, A., and Yasui, A. (1990) Arch. Biochem. Biophys. 283, 210-216), a strictly anaerobic archaebacterium, was expressed in Escherichia coli. The gene product accounted for more than 30% of the host's soluble protein. The purified protein was an active iron-containing tetrameric SOD with specific activity similar to known manganese-containing SODs (MnSODs) of aerobic archaebacteria. Although M. thermoautotrophicum SOD is an iron-containing SOD (FeSOD), it resembles MnSODs in amino acid sequence as judged by criteria distinguishing FeSODs from MnSODs. Moreover, M. thermoautotrophicum SOD is resistant to azide and hydrogen peroxide as MnSODs are, suggesting that its evolution is distinct from known eubacterial FeSODs.

Amino Acid Sequence↗
PubMed1991

Active recombinant C3a of human anaphylatoxin produced in Escherichia coli.

DNA sequence coding for the complete human C3a with 77 amino acids was divided into three portions, synthesized separately and constructed for expression in Escherichia coli. High expression of the recombinant C3a was achieved by an expression system using T7 polymerase. Purified recombinant C3a showed the same activities of ileum contraction and platelet aggregation of guinea pig as C3a purified from human serum.

Amino Acid Sequence↗
PubMed1991

Isolation and characterization of lamprey rhodopsin cDNA.

Genomic DNA fragments coding a visual pigment of the lamprey were amplified by polymerase chain reaction, using oligonucleotide mixtures as primers. The complete coding region of the cDNA was obtained by separate amplification of both cDNA ends. The deduced amino acid sequence of the coding region showed 78-82% identity with those of rhodopsins of higher vertebrates, but only 43-47% identity with those of human color pigments. The cloned DNA appears to be the cDNA of a lamprey rhodopsin, which is expressed in the "short" photoreceptor cell.

Amino Acid Sequence↗
PubMed1991

Isolation of two chloroethylnitrosourea-sensitive Chinese hamster cell lines.

1-[(4-Amino-2-methylpyrimidin-5-yl)methyl]-3-(2-chloroethyl)-3- nitrosourea hydrochloride (ACNU), a cancer chemotherapeutic bifunctional alkylating agent, causes chloroethylation of DNA and subsequent DNA strand cross-linking through an ethylene bridge. We isolated and characterized two ACNU-sensitive mutants from mutagenized Chinese hamster ovary cells and found them to be new drug-sensitive recessive Chinese hamster mutants. Both mutants were sensitive to various monofunctional alkylating agents in a way similar to that of the parental cell lines CHO9. One mutant (UVS1) was cross-sensitive to UV and complemented the UV sensitivity of all Chinese hamster cell lines of 7 established complementation groups. Since UV-induced unscheduled DNA synthesis was very low, a new locus related to excision repair is thought to be defective in this cell line. Another ACNU-sensitive mutant, CNU1, was slightly more sensitive to UV than the parent cell line. CNU1 was cross-sensitive to 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea and slightly more sensitive to mitomycin C. No increased accumulation of ACNU and a low level of UV-induced unscheduled DNA synthesis in this cell as compared with the parental cell line suggest that there is abnormality in a repair response of this mutant cell to some types of DNA cross-links.

Animals↗
PubMed1991

Combined portal vein and liver resection for carcinoma of the biliary tract.

Twenty-nine patients with advanced carcinoma of the bile duct or gallbladder underwent combined portal vein and liver resection. Segmental excision of the portal vein was performed in 16 cases and wedge resection of the vessel wall in 13. The operative mortality rate was 17 per cent. The median survival for the 24 patients who left hospital was 19.8 months. Actuarial survival rates at 1, 3 and 5 years for all 29 patients were 48 per cent, 29 per cent, and 6 per cent respectively, whereas the median survival for 46 patients with unresectable carcinoma was 3 months and the 1 and 3-year actuarial survival rates were 13 per cent and zero respectively. This difference in survival times between patients undergoing hepatectomy with portal vein resection and those with unresectable carcinoma were statistically significant (P less than 0.01). Combined portal vein and liver resection is recommended as a reasonable surgical approach in selected patients with advanced carcinoma of the biliary tract.

Adult↗
PubMed1991

Percutaneous transhepatic manometry of sphincter of Oddi.

A nonoperative examination of the function of the sphincter of Oddi, involving percutaneous transhepatic manometry via the percutaneous transhepatic biliary drainage tract, was developed and clinically applied in 23 patients with biliary disease. Long-term recording of sphincter of Oddi motility, which was impossible using conventional intraoperative or endoscopic manometry, was made possible by means of this method and revealed various changes of sphincter of Oddi motility. The mean recording time was 131.33 +/- 9.77 min. The frequency of contractions of the sphincter of Oddi in basal fasting conditions varied from 0 to 13/min and high-frequency contractions (frequency 9.49 +/- 0.35/min, duration 5.77 +/- 0.54 min) were observed in 12 patients on a total of 19 occasions. In five patients, high-frequency contractions were observed twice during one session of continuous recording and the interval between burst contractions was 85.4 +/- 13.3 min. Long-term continuous recording is advantageous for the evaluation of the function of the sphincter of Oddi and short-term manometry may not be representative of overall sphincter of Oddi motility.

Adult↗
PubMed1991

Hepatopancreatoduodenectomy for advanced carcinoma of the biliary tract.

Twenty-four patients with advanced carcinoma of the gallbladder and/or the bile duct underwent hepatopancreatoduodenectomy, that is, en bloc hepatic resection with pancreatoduodenectomy. They included 14 cases of gallbladder carcinoma, nine cases of bile duct carcinoma, and one case of double cancer of the gallbladder and the bile duct. Eleven kinds of hepatic lobectomy or segmentectomy with pancreatoduodenectomy were carried out, and the caudate lobe was also removed en bloc from 17 patients with carcinoma involving the hepatic hilus. Combined resection of the portal vein was performed in 11 patients, of the inferior vena cava in 2, and of the colon in 5, patients. Forty-four postoperative complications occurred in 22 patients (91.7%). The operative mortality rate was 12.5% (3/24). The median survival and the 2-year survival rate were 7.0 months and 17.9% for all 24 patients, including 3 operative deaths, or 11.0 months and 20.4% for 21 patients surviving hepatopancreatoduodenectomy, and 12.4 months and 20.8% for all 14 patients with gallbladder carcinoma, and 5.2 months and 14.8% for all 9 patients with bile duct carcinoma. The longest survivor died of recurrent tumors at 5 years and 7 months. Hepatopancreatoduodenectomy offered not only an unexpectedly long survival period, but also unexpected morbidity in some cases.

Adenoma, Bile Duct↗
PubMed1991

Molecular cloning and sequence analysis of cDNA for the catalytic subunit 1 alpha of rat kidney type 1 protein phosphatase, and detection of the gene expression at high levels in hepatoma cells and regenerating livers as compared to rat livers.

A cDNA clone containing the full coding sequence of a type 1 protein phosphatase catalytic subunit 1 alpha has been isolated from a rat kidney lambda gt 10 library. The protein sequence deduced from the cDNA contains 330 amino acid residues with a molecular mass of 38 kDa. The cDNA clone from rat kidney was 89% identical at the nucleotide level in the coding region to type 1 protein phosphatase 1 alpha from rabbit skeletal muscle. However, the two protein sequences were completely identical. The type 1 alpha protein phosphatase from rat kidney shows 49% homology of amino acid sequence to the rat type 2A alpha protein phosphatase. Thus, the protein sequence of type 1 alpha protein phosphatase was completely conserved between rat and rabbit. The mRNA levels of type 1 protein phosphatase were determined in rat liver, AH13, a strain of rat hepatoma, and regenerating rat liver by Northern blot analysis using the cDNA fragment as a probe, under which conditions a single mRNA of 1.5 kb was detected. The mRNA levels of AH13 were remarkably increased when compared to those of normal ivers, whereas the mRNA levels of regenerating livers were slightly but significantly increased. These results demonstrate a marked increase in gene expression of type 1 protein phosphatase in hepatoma cells, suggesting an important role of the type 1 protein phosphatase in hepatocarcinogenesis.

Amino Acid Sequence↗
PubMed1991

[Serum beta 2-microglobulin as a index of the initiation of dialysis therapy for diabetic patients with chronic renal failure].

This study was designed whether serum beta 2-microglobulin is good index for the initiation of dialysis therapy in diabetic patients with chronic renal failure. Serum creatinine (S. Cr), beta 2-microglobulin (S. beta 2-MG) and guanidinoacetic acid (S. GAA) were measured in dialyzed or undialyzed diabetic patients with chronic renal failure in comparison with non diabetic patients. 28.6% of diabetic patients showed S. Cr below 8.0 mg/dl at the initiation of dialysis therapy although all of non diabetic patients showed it over 8.0 mg/dl. On the other hand, there was no significant difference in S. beta 2-MG between diabetic and non diabetic patients, and all patients of the two groups showed S. beta 2-MG over 12.0 mg/l. In non diabetic patients whose S. Cr was below 8.0 mg/dl, undialyzed patients had a significant correlation between S. Cr and S. beta 2-MG (r = 0.840, P less than 0.01), and all non diabetic patients showed relatively high value of S. Cr as compared with that of beta 2-MG at the initiation of dialysis therapy. Undialyzed diabetic patients whose S. Cr was below 8.0 mg/dl also revealed a close correlation between serum creatinine and beta 2-MG (r = 0.864, P less than 0.01), but dialyzed diabetic patients showed different correlation between S. Cr and S. beta 2-MG from it of non diabetic patients and S. Cr was underestimated as compared with S. beta 2-MG. Undialyzed diabetic patients showed significant lower values of S. Cr and S. GAA of non diabetic patients whose S. beta 2-MG were almost same as diabetics.(ABSTRACT TRUNCATED AT 250 WORDS)

Creatinine↗
PubMed1991

[Management of cholangitis complicated in biliary carcinoma with hilar bile duct stenosis].

We reviewed 60 cases of biliary carcinoma with hilar bile duct stenosis which had received percutaneous transhepatic cholangio-drainage (PTCD). Of the 60 cases, nine were complicated with acute cholangitis (AC) and three with segmental acute obstructive suppurative cholangitis (S-AOSC). The incidence of cholangitis was 20%. Six patients with AC and three with S-AOSC underwent hepatic resection for carcinoma. As to preoperative management for cholangitis in these 9 cases, conservative chemotherapy was effective in only 2 cases, and additional PTCD or segmental introduction of the drainage catheter under PTCS were useful in 5 cases. The remaining 2 cases with S-AOSC needed urgent hepatic resection including suppurative hepatic segments after various interventional treatments. No significant difference was found in resectability, morbidity and mortality between the cholangitis group and non-cholangitis group. In conclusion, it is emphasized that postoperative outcome of biliary carcinoma with cholangitis will be improved by adequate PTCD and/or urgent hepatic resection.

Acute Disease↗