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Biomedical subjects

S Asakawa

Publications and source records attributed to S Asakawa.

At least 91 records · Page 5Linked to original sources
PubMed1995

Nucleotide sequence and gene organization of the starfish Asterina pectinifera mitochondrial genome.

The 16,260-bp mitochondrial DNA (mtDNA) from the starfish Asterina pectinifera has been sequenced. The genes for 13 proteins, two rRNAs and 22 tRNAs are organized in an extremely economical fashion, similar to those of other animal mtDNAs, with some of the genes overlapping each other. The gene organization is the same as that for another echinoderm, sea urchin, except for the inversion of a 4.6-kb segment that contains genes for two proteins, 13 tRNAs and the 16S rRNA. Judging from the organization of the protein coding genes, mammalian mtDNAs resemble the sea urchin mtDNA more than that of the starfish. The region around the 3' end of the 12S rRNA gene of the starfish shows a high similarity with those for vertebrates. This region encodes a possible stem and loop structure; similar potential structures occur in this region of vertebrate mtDNAs and also in nonmitochondrial small subunit rRNA. A similar stem and loop structure is also found at the 3' end of the 16S rRNA genes in A. pectinifera, in another starfish Pisaster ochraceus, in vertebrates and in Drosophila, but not in sea urchins. The full sequence data confirm the presumption that AGA/AGG, AUA and AAA codons, respectively, code for serine, isoleucine, and asparagine in the starfish mitochondria, and that AGA/AGG codons are read by tRNA(GCUSer), which possesses a truncated dihydrouridine arm, that was previously suggested from a partial mtDNA sequence. The structural characteristics of tRNAs and possible mechanisms for the change in the mitochondrial genetic code are also discussed.

Amino Acid Sequence↗
PubMed1995

The organization of the human immunoglobulin lambda gene locus.

To elucidate the complex structure of the human immunoglobulin lambda gene locus, a 1020-kb contig was constructed using 184 cosmid clones and one bacterial artificial chromosome (BAC) clone. A high-resolution physical map of this contig revealed that the entire lambda gene locus is 911 kb in length. It contains seven constant region (C lambda) gene segments and 69 unique EcoRI-HindIII segments that hybridize to variable region gene (V lambda) probes. The VpreB gene, BCRL4, and gamma-glutamyl transpeptidase gene (GGT)-like sequences are also located within the lambda gene locus. Hybridization analysis suggested that the lambda gene locus has undergone extensive amplification events in evolution.

Base Sequence↗
PubMed1994

[Application of the Limulus test for practical quality control on endotoxin content in commercial human serum albumin (HSA) products. In comparison with the rabbit pyrogen test].

The bacterial endotoxin content in human serum albumin (HSA) products measured by two different Limulus amebocyte lysate (LAL) test methods, colorimetric and kinetic turbidimetric methods, were compared. So far as endotoxin-specific LAL reagents which do not show a false-positive reaction with (1-->3)-beta-D-glucan are used, a definite correlation was found between the results with the two LAL test methods. Endotoxin added to HSA products was recovered in a quantitative manner showing neither inhibition nor enhancement by HSA to the both LAL test methods. Results of the LAL tests showed a significant correlation with that of the rabbit pyrogen test. The correlation was much improved with endotoxin-added HSA. The present results indicate the practical applicability of the LAL test as an alternative method for the rabbit pyrogen test.

Animals↗
PubMed1994

DMSO preparation as a direct solubilizer of calcium bilirubinate stones.

Despite considerable progress in operative techniques, biliary surgeons continue to encounter difficulties when treating patients with intrahepatic gallstones. We have experienced a significant number of patients in whom complete stone removal was impossible during an operation due to the anatomical complexity of intrahepatic bile ducts, and the variety in the size and hardness of the stones. Under such circumstances, the application of a direct solubilizer capable of dissolving intrahepatic calcium bilirubinate stones, might be a possible alternative. Up to now, however, only calcium chelating agents have been used for removing calcium from calcium bilirubinate stones, and they are not always effective. As a promising solution to this problem, we have now developed a direct solubilize for bilirubin complexes--a dimethyl sulfoxide (DMSO) preparation. DMSO is a well-known bipolar nonprotonic solvent. We prepared solutions of DMSO and performed toxicological studies by administering this preparation to rats and dogs. Biochemical indices of liver and renal function remained unchanged after 7-28 days of DMSO administration. Nor were there any histological changes in the DMSO-treated animals on systemic survey of various organs. On comparing the in vitro capability for solubilizing calcium bilirubinate stones, the DMSO preparation was consistently superior to a calcium chelating agent alone. The combination of a chelating agent with DMSO had the highest solubilizing capacity.

Animals↗
PubMed1993

Two different histamine-sensitizing activities of pertussis vaccine observed in mice on the 4th and 12th days of sensitization.

The histamine-sensitizing (HS) activities of commercial precipitated diphtheria-tetanus-purified pertussis combined vaccines (DTP) submitted to the national quality control tests during the period from 1980 to 1991 were measured in mice on days 4 (EHS) and 12 (LHS) of sensitization. Annual averages of the EHS activity of the vaccines showed continuous decline during the period, while the LHS activity stayed unchanged except for 1990 and 1991. Correlation analysis between these two HS activities revealed that the vaccines could be differentiated into two groups, those showing a significant correlation and those lacking it, depending on their source manufacturers. When the vaccine was incubated at 37 C for four weeks, both the HS activities increased for the first couple of weeks at different rates, reaching their peaks after different periods; three weeks for the EHS activity and two weeks for the LHS activity. Treating the reference pertussis vaccine (for toxicity tests) with anti-pertussis toxin horse serum neutralized completely the EHS activity but the LHS activity resisted the serum. These findings suggest a possible difference between the two HS activities in their mode of action, therefore, in their roles in possible reactogenicity of the vaccine, and a necessity for separate controls of the two activities.

Animals↗
PubMed1992

A useful cholesterol solvent for medical dissolution of gallstones.

Dissolution of cholesterol gallstones by direct instillation of an agent into the biliary tract has been considered an alternate to surgical procedures. We developed an excellent direct solubilizer by combining d-limonene and medium-chain monoglyceride. This mixture enhances the advantages of each individual solvent and minimizes the disadvantages. In vitro experiments were done to determine the viscosities and the cholesterol dissolving rates of various combinations, and in vivo experiments were conducted to study their irritation effects on tissues. The optimal combination was a 3:2 mixture of d-limonene and medium-chain monoglyceride. It could quickly dissolve cholesterol gallstones with minimal or no observable side effect.

Animals↗
PubMed1992

[Application of the limulus amebocyte lysate test to measurement of endotoxin in therapeutic human plasma protein fraction. Comparison with the rabbit pyrogen test].

We applied the limulus amebocyte lysate (LAL) test to the detection of bacterial endotoxins in therapeutic human plasma protein fraction (PPF) and compared the LAL-test with the rabbit pyrogen test. Two endotoxin-specific LAL-reagents were used for the colorimetric method and turbidimetric kinetic method. The amounts of added endotoxin to the PPF were correctly estimated by either method. The results of four independent assays for the 53 samples of PPF corresponded well with each other (correlation coefficient: 0.851-0.959, regression coefficient: 0.898-1.151). The amounts of endotoxin in the PPF estimated by the LAL-test significantly correlated with the rise of body temperature in rabbits (correlation coefficient: 0.547-0.642, and 0.911-0.934 for the endotoxin added samples). These results suggest that the LAL-test could be used as an alternative method for the rabbit pyrogen test to PPF.

Animals↗
PubMed1991

Strand-specific nucleotide composition bias in echinoderm and vertebrate mitochondrial genomes.

The gene organization of starfish mitochondrial DNA is identical with that of the sea urchin counterpart except for a reported inversion of an approximately 4.6-kb segment containing two structural genes for NADH dehydrogenase subunits 1 and 2 (ND 1 and ND 2). When the codon usage of each structural gene in starfish, sea urchin, and vertebrate mitochondrial DNAs is examined, it is striking that codons ending in T and G are preferentially used more for heavy strand-encoded genes, including starfish ND 1 and ND 2, than for light strand-encoded genes, including sea urchin ND 1 and ND 2. On the contrary, codons ending in A and C are preferentially used for the light strand-encoded genes rather than for the heavy strand-encoded ones. Moreover, G-U base pairs are more frequently found in the possible secondary structures of heavy strand-encoded tRNAs than in those of light strand-encoded tRNAs. These observations suggest the existence of a certain constraint operating on mitochondrial genomes from various animal phyla, which results in the accumulation of G and T on one strand, and A and C on the other.

Amino Acid Sequence↗
PubMed1989

Conserved tRNA gene cluster in starfish mitochondrial DNA.

Partial sequencing of mtDNA from four long-diverged species of starfish reveals the existence of a conserved cluster of 13 tRNA genes, organized in a manner similar to that of the tRNA cluster of sea urchin mtDNA, but located at a position distant from the presumed replication origin. These findings suggest that a clustered organization of tRNA genes may have been present in the ancestral mitochondrial genome, and raise the possibility that tRNAs may have catalyzed the dispersal rather than the accumulation of the genes which encode them.

Amino Acid Sequence↗
PubMed1985

Biliary excretion of latamoxef and N-methyltetrazolethiol in humans and rats.

The biliary excretions of latamoxef and N-methyltetrazolethiol (NMTT) were studied in patients with T-tubes inserted in their common bile ducts, and in bile fistulated male rats. The highest concentrations of latamoxef and NMTT in 6 patients with cholelithiasis were obtained 1-2 h after intravenous injection of a single 1-g dose, and the mean peak values were 66.2 and 0.85 microgram/ml, respectively. The values in patients with gallbladder carcinoma or pancreas head carcinoma were much lower than those with cholelithiasis. The biliary excretions of latamoxef and NMTT in rats were much higher and faster than in humans, with the highest levels being obtained within 30 min after injection. About 20% of the injected dose was recovered as latamoxef and 4% as decomposed materials in 2.5 h after injection. Latamoxef was not decomposed in human or rat bile when kept at -20 degrees C for 4 weeks if the pH was adjusted to 6; some decomposition occurred (10-20%) if the pH was not adjusted.

Animals↗
PubMed1985

A curious histamine-sensitizing activity shown by the newly-developed Japanese acellular pertussis vaccine.

A new acellular pertussis vaccine, whose official name is "Precipitated Purified Pertussis Vaccine" (PPV), was prescribed in the Japanese Minimum Requirements for Biological Products in 1981. The PPV is composed of partially detoxified fractions of pertussis cells. The histamine-sensitizing (HS) activities of PPV vaccines are less than those of killed whole pertussis cell vaccines (WPV) produced in Japan until 1980, when the histamine challenge was carried out in mice on day four after injection. It was found that when the histamine challenge day was delayed that the HS activities of some lots of PPV gradually increased from those estimated on day four after injection of PPV and reached the maximum in about 12 days, while the activity of the reference whole cell pertussis vaccine reached the maximum several days after injection and then gradually decreased. Hereafter, HS activities of test materials estimated on days four and 12 after injection are referred to as early HS (EHS) and late HS (LHS) activities, respectively. Since LHS activity of the reference whole cell vaccine is lower than its EHS activity and the reverse is true with many lots of PPV, it is often observed that the EHS activity of PPV according to the Japanese requirement for PPV, ranges from 0.02 to 2.0 HSU whereas activities of some lots of PPV were estimated at 5.0 to 25.0 HSU. The relationship of the detoxifying process to EHS and LHS activities was studied with bulk materials, which were used for the purification procedure but prior to the detoxification process for the production of PPV.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Liquid crystal formation in ursodeoxycholate-rich human gallbladder bile.

We studied liquid crystal formation in bile samples obtained from the patients with radiolucent gallstones who had been administered either ursodeoxycholic acid (UDCA) at a dose of 600 mg/day or chenodeoxycholic acid (CDCA) at 400 mg/day for one week preoperatively. The UDCA/total bile acids ratio was found to range from 50 to 60% and the CDCA/total bile acids ratio ranged from 70 to 80%. Cholesterol molar percent was 5 in UDCA-rich bile and 6 in CDCA-rich bile. Phospholipid molar percentage was about the same in both groups. Liquid crystal formation was confirmed only in the UDCA-rich bile samples but not in the CDCA-rich bile samples. This result suggests that cholesterol in the UDCA-rich bile samples is not solubilized by the bile salt and phospholipid mixed micelles but also consumed to form liquid crystals.

Bile↗
PubMed1983

The quantitative determination of the paw-swelling activity of pertussis vaccine with special reference to its responsible toxic components.

A method has been developed for quantitative determination of the early appearing mouse paw swelling activity of pertussis vaccine. Mice were inoculated with the vaccine into the left hind paws. The difference in the thicknesses between the inoculated and the uninoculated paws was taken as the swelling response in 16 hr after inoculation. It was transformed into logarithm as a response metameter. A linear log dose-log response regression line was obtained over a relatively wide range of doses of the vaccine. No deviation from parallelism was significant among the regression lines of different vaccines tested. The swelling activities relative to that of a reference vaccine of diphtheria-pertussis-tetanus combined (DPT) vaccines recently produced in Japan were determined. The relative activities ranged from 0.6 to 2.5, being twice the mean width of the 95% confidence interval of the relative activity. Further experiments showed that the activity significantly correlated with endotoxin and histamine-sensitizing factor (HSF) but not with lymphocytosis-promoting factor (LPF). In addition, the multiple regression analysis of such relationship suggested that the swelling activity is accounted for by the combined action of endotoxin and HSF. A model experiment with a mixture of the two toxins supported this conclusion.

Adjuvants, Immunologic↗
PubMed1983

[A new direct solubilizer for bilirubinate calcium stones].

Hepatobiliary surgeons must have faced difficulty in treating patients with intrahepatic gallstones. In spite of considerable progress in operative methods or mechanical techniques, it is very difficult to remove intrahepatic gallstones completely. Under such circumstances, the development of a solubilizer that can dissolve intrahepatic bilirubinate calcium stones by means of injecting it through a postoperative catheter or PTCD catheter has been awaited. Up to now, a chelating agent, so-called hexametaphosphate (HMP) has been used for removing the calcium from calcium bilirubinate. But this chelating agent, in itself, cannot dissolve the bilirubin. The authors found a direct solubilizer for bilirubin, dimethyl sulfoxide (DMSO) which is a well known bi-polar non protonic solvent and used as an accelerator for bilirubin determination. After the purification of DMSO to 99.98%, toxicity was examined by oral administration, intravenous administration and infusion into biliary tract. But no remarkable toxicity or side effects were detected on biochemical and pathological examinations. Clinical application of 90% DMSO together with 5% HMP was performed and a satisfactory effect was obtained as a direct solubilizer for bilirubinate calcium stones.

Aged↗
PubMed1982

The effect of Bordetella pertussis lymphocytosis-promoting factor (LPF) on antibody response in mice: its enhancing and suppressive effects.

The effect of lymphocytosis-promoting factor (LPF) on antibody response in mice was estimated under different sets of experimental conditions. Four- and 6-week-old mice were intravenously inoculated with LPF. Three days later these mice were inoculated either intraperitoneally or intravenously with sheep red blood cell (SRBC) or human serum albumin (HSA) as an antigen. The adjuvant effect of LPF was demonstrated on antibody response in 6-week old mice to intraperitoneally inoculated SRBC but not to intravenously-inoculated one. When 4-week-old mice were immunized, hemagglutinin production in response to intraperitoneally inoculated SRBC was not enhanced by LPF. In addition, a rather suppressive effect of LPF at a comparatively high dose was demonstrated on hemagglutinin production in response to intravenously inoculated SRBC. Anti-HSA production was enhanced by inoculation of LPF in any combination of the mouse age and the route of antigen administration. These findings indicate that the adjuvant effect of LPF on antibody response in mice depends upon experimental conditions: the age of mice, the quality of antigen and the route of antigen administration used for immunization.

Animals↗
PubMed1981

ABO blood group activities in human albumin preparations.

By using hemagglutination-inhibition technique, A and B blood group activities were demonstrated in all of the tested batches of Plasma Protein Fraction and Human Serum Albumin prepared by one manufacturer in the period of 1975-1978; whereas all the tested batches prepared by other manufacturers were found to be free of blood group activities. With some batches of Plasma Protein Fraction prepared by the above-mentioned manufacturer, the presence A blood group activity was confirmed by the anti-A response in immunized rabbits. The blood group activities were localized in earlier fractions in Sephadex G-200 gel filtration analysis. The active principles were resistant to boiling for one hour. They were recovered in the aqueous phase by chilled buthanol treatment and could not be extracted with chloroform-methanol. These results seem to suggest that the blood group active principles detected in the albumin preparations are more likely of water-soluble glycoprotein nature than being glycosphingolipids.

1-Butanol↗