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Biomedical subjects

S Okada

Publications and source records attributed to S Okada.

At least 577 records · Page 32Linked to original sources
PubMed1996

A novel nonsense mutation (G181X) in the human cholesteryl ester transfer protein gene in Japanese hyperalphalipoproteinemic subjects.

Cholesteryl ester transfer protein (CETP) plays an important role in regulating the concentration and composition of high density lipoprotein (HDL) and low density lipoprotein (LDL). Although several genetic abnormalities causing CETP deficiency have been identified in the Japanese subjects with a marked hyperalphalipoproteinemia (HALP), there are many CETP-deficient subjects for whom the genetic abnormalities have not been clarified. In the present study, we analyzed the molecular basis of an HALP subject without CETP activity and mass, and found a novel mutation in the CETP gene. This novel mutation (G181X) was a G-to-T substitution at codon 181 of exon 6 which replaced a codon for glycine (GGA) with a premature stop codon (TGA). The G181X mutation created a new cutting site by restriction enzyme MaeIII. To estimate the frequency of G181X, we investigated unrelated 294 HALP (HDL-cholesterol > or = 2.59 mmol/L = 100 mg/dl) subjects by restriction fragment length polymorphism (RFLP) analysis with Mae III. One (0.34%) HALP subject was homozygous and four (1.36%) were heterozygous for this mutation. The allelic frequency of a G-to-T substitution at codon 181 of exon 6 was 0.0102 in HALP subjects. From the lipid analysis of the proband and the homozygote, it was clarified that the G181X mutation had dominant effects on HDL and LDL metabolism, similar to a G-to-A substitution at the 5' splice donor site of the intron 14 (1451 + 1G-->A). In conclusion, the G181X mutation is one of causes of HALP in the Japanese HALP subjects, having dominant effects on lipid metabolism.

Carrier Proteins↗
PubMed1996

Nitric oxide, a physiological modulator of mitochondrial function.

The effect of nitric oxide (NO) on the energy transfer reactions of mitochondria was examined under different oxygen tensions. Mitochondrial functions, such as respiration, ATP synthesis and regulation of membrane potential, were inhibited by NO in a concentration-dependent manner. In the presence of various substrates, NO also inhibited uncoupled respiration in an oxygen concentration-dependent manner. The inhibited function recovered completely at certain times after adding NO. When added to mitochondrial suspensions, NO disappeared rapidly from the medium and more rapidly at high oxygen tensions than at low oxygen tensions as determined by the formation of methemoglobin and EPR methods. From these results it is concluded that NO might play an important role in the regulation of mitochondrial functions particularly under low oxygen concentrations.

Animals↗
PubMed1996

[Difference in expression of epithelial adhesion molecules between primary and metastatic lesions in small-cell lung cancer].

One crucial step in tumor metastasis is detachment of cells from the primary lesion. This involves down-regulation of homophilic binding intercellular adhesion molecules. To determine whether this occurs in metastasis of human small-cell lung cancer to lymph nodes, we examined expression of E-cadherin, carcinoembryonic antigen (CEA), and neural cell adhesion molecule (NACM) on cells from patients with small-cell lung cancer, some cells were obtained from primary lesions and others from lymph-node metastases. Cells in all of the five lines from primary lesions expressed E-cadherin, unlike those in all of the five lines from lymph-node metastases. Cells in all of the five lines from primary lesions expressed CEA, as did those in only one of the five cell lines from lymph-node metastases. Cells in lines from primary and metastatic lesions did not differ in the expression of NCAM (4/5 positive). Expression of E-cadherin and of CEA were closely correlated. Because E-cadherin and CEA are involved in the binding of epithelial cells, these findings demonstrate that metastasis of small-cell lung cancer to lymph nodes is associated with a lack of the epithelial intercellular adhesion molecules E-cadherin and CEA. The expression of these molecules is involved in the metastasis of small-cell lung cancer to lymph nodes.

Cadherins↗
PubMed1996

[Sennosides Reference Standard (Control 951) of the National Institute of Health Sciences].

The "Sennosides Reference Standard (Control 951)" was prepared, which is intended to be used for the fluorophotometric assay of sennosides content in the preparation of "Sennosides". In this assay hydroxylated mono- and dianthraquinone glucosides are chelated with boric acid, and the fluorescence intensity of the chelate is determined against that of the Reference Standard (RS). In the establishment of this RS, sennosides content in the candidate material must be determined accurately by fluorophotometry. The Sennoside AB for assay, prepared as an equimolar mixture of the purified sennoside A and Sennoside B, was used as the RS for the fluorophotometry. Based on the above concept, sennosides content in the candidate was determined as calcium salts to be 60.1 +/- 1.6% by the fluorophotometry. Thus the sennosides content of this Sennosides RS was certified to be 60%. Separately, contents of Sennoside A (SA) and Sennoside B (SB) in this candidate were determined by using HPLC. As a result, the sum of SA and SB was estimated to be 38% as free acids. Thus it was suggested that about 20% of dianthraquinone glucosides other than SA and SB and anthraquinone glucosides may be included in this Sennoside RS as free acids. Analytical results on the USP Sennosides RS were also shown and discussed, compared with the present Sennosides RS.

Anthraquinones↗
PubMed1996

[Digitoxin Reference Standard (Control 951) of the National Institute of Health Sciences].

The raw material of digitoxin was tested for preparation of the "Digitoxin Reference Standard (Control 951)". Analytical data obtained were as follows: loss on drying, 0.0%; infrared spectrum, the same as that of the JP Digitoxin Reference Standard (Control 845); thin-layer chromatography, no impurity was detected; high-performance liquid chromatography (HPLC), two kinds of impurities were detected and the total amount was estimated to be 0.16 +/- 0.01% (n = 3); assay, 99.0% by HPLC. Based on the above results, the raw material was authorized as the JP Digitoxin Reference Standard (Control 951).

Chemical Phenomena↗
PubMed1996

[Betamethasone Reference Standard (Control 951) of the National Institute of Health Sciences].

The raw material of betamethasone was tested for preparation of the "Betamethasone Reference Standard (Control 951)". Analytical data obtained were as follows: loss on drying, 0.0%; infrared spectrum, the same as that of the JP Betamethasone Reference Standard (Control 845); thin-layer chromatography, no impurity was detected; high-performance liquid chromatography (HPLC), two kinds of impurities were detected and the total amount was estimated to be 0.16 +/- 0.01% (n = 3); assay, 100.0% by HPLC. Based on the above results, the raw material was authorized as the JP Betamethasone Reference Standard (Control 951).

Betamethasone↗
PubMed1996

[Tocopherol Acetate Reference Standard (Control 941) of the National Institute of Health Sciences].

The raw material of tocopherol acetate was tested for the preparation of the "Tocopherol Acetate Reference Standard (Control 941)". Analytical data obtained were as follows: infrared spectrum, the same as that of the Tocopherol Acetate Reference Standard (Control 919); specific absorbance, E1(1%)cm (284nm) = 44.5; thin-layer chromatography, no impurities were detected until 50.0 micrograms; high-performance liquid chromatography (HPLC), 2-3 impurities were detected and the amount was estimated to be about 1%; assay by HPLC, 100.8%. Based on the above results, the raw material was authorized as the Japanese Pharmacopoeia Reference Standard (Control 941).

Chemical Phenomena↗
PubMed1996

[Cyanocobalamin Reference Standard (Control 951) of the National Institute of Health Sciences].

The raw material of cyanocobalamin was tested for preparation of the "Cyanocobalamin Reference Standard (Control 951)". Analytical data obtained are as follows: loss on drying, 1.8%; infrared spectrum, the same as that of the JP Cyanocobalamin Reference Standard (Control 936); thin-layer chromatography, three impurities were detected; high-performance liquid chromatography (HPLC), eight to nine kinds of impurities were detected and the total amount of impurities was estimated to be 1.6 +/- 0.13% (n = 4); assay, 99.7% by spectrophotometry specified in the JP XII and 100.4% by HPLC, respectively. Based on the above results, the raw material was authorized as the JP Cyanocobalamin Reference Standard (Control 951).

Chemical Phenomena↗
PubMed1996

[dl-Camphor Reference Standard (Control 951) of the National Institute of Health Sciences].

The raw material of dl-camphor was examined for the preparation of the "dl-Camphor Reference Standard". Analytical data obtained are as follows: ultraviolet spectrum, lambda max = 290 nm; infrared spectrum, the same as that of the present JP Camphor Reference Standard; melting point, 179.6 degrees C; purity test by gas-chromatography (GC), three kinds of impurities were detected; assay by GC, 99.0%. Based on the above results, the candidate raw material was authorized as the JP Reference Standard (Control 951).

Camphor↗
PubMed1996

[Lysozyme Reference Standard (Control 951) of the National Institute of Health Sciences].

The "Lysozyme Reference Standard (Control 951)" of the National Institute of Health Sciences was prepared. The lysozyme potency of the standard material was assayed against the Lysozyme Reference Standard (Control 915) by two turbidimetric methods using the drycells of Micrococcus luteus as the substrate. The potency of the standard material was in satisfactory agreement with that of Lysozyme Reference Standard (Control 915) and was defined as 1 mg [potency] per mg.

Amino Acids↗
PubMed1996

[The Somatropin Reference Standard (Control 951) of the National Institute of Health Sciences].

Somatropin material was examined for preparation of the "Somatropin Reference Standard". The candidate material was evaluated by a domestic collaborative study in which eight laboratories participated. The protein content was determined to be 4.5 mg/Vial based on amino acid analysis. Because of the possibility of application as a chemical reference standard for assay by the HPLC method, a physico-chemical evaluation of the candidate material was also performed. By SE-HPLC, the content of polymer, dimer were determined to be 0.54%, 0.98%, respectively. By RP-HPLC, the early peak area ascribed to desamido and sulfoxide form was 1.07% of the total peak area. And for informational data, the potency of the candidate material, being estimated by three different biological methods, weight gain assay, tibia test and adiposeconversion assay is 14.8 IU/vial. Based on the above results, the candidate was authorized as the Somatropin Reference Standard of the National Institute of Health Sciences.

Amino Acids↗
PubMed1996

[The Human Menopausal Gonadotrophin Reference Standard (Control 961) of the National Institute of Health Sciences].

Raw human menopausal gonadotrophin (HMG) material was examined for preparation of the "Human Menopausal Gonadotrophin Reference Standard (Control 961)". The candidate material was assayed its follicle stimulating hormone (FSH) activity and luteinizing hormone (LH) activity against the 3rd International Standard for FSH and LH, urinary (71/264) by the augmented ovarian weight gain assay and the seminal vesicle weight gain test, respectively. The potency of the new standard was defined as 56 international units of FSH activity per mg and 61 international units of LH activity per mg as the result of 13 and 5 assays, respectively, in four collaborative laboratories.

Animals↗
PubMed1996

[Application of thermal analysis to quality evaluation tests of drugs].

Thermal analysis method can be applied to the quality evaluation tests of drugs. Recent advances in the technology and the data-processing system on the apparatus have accelerated the utilization of this analytical techniques in the field of drug quality control. In this report, various application techniques of the thermal analysis such as DSC, DTA, TG and the impurity analysis by DSC, were reported and discussed from the viewpoints of a general test in the Japanese Pharmacopoeia. Further the present situations of this analytical method in the US Pharmacopoeia 23 and the British Pharmacopoeia 1993 are also explained.

Differential Thermal Analysis↗
PubMed1996

Experimental ligation versus embolization of the external carotid artery: a comparative hemodynamics study.

Patterns of collateral vascularization were investigated by SEM evaluation of microvascular corrosion casts following either ligation or embolization of the external carotid artery in the rabbit. Results indicated that rich collateral channels were established soon after ligation of this artery, and blood supply to the lesional area was never cut off. In contrast, embolization effectively obstructed blood supply by reducing collateral branches. We concluded that for purposes of controlling blood loss, it is more helpful to employ external carotid embolization rather than ligation for oral maxillofacial lesions with a rich blood supply.

Animals↗
PubMed1996

Spiral structures in the wall of the hepatic venous system in the dog.

Unique spiral structures, located in the wall of the hepatic venous system in the dog, were examined in the central veins and the hepatic venous branches, utilizing microvascular corrosion casting and freeze-fracture technique in scanning electron microscopy and transmission electron microscopy of tissue sections. The whole hepatic venous system was divided into 4 portions: the central, sublobular, collecting and branches of the hepatic veins. The central vein was spindle-shaped with several compressions. Removing the endothelial cells of the central vein, pathways of venous sinusoids were like a labyrinth. In the sublobular veins, spiral structures distinctly appeared as the diameter increased. Beneath the endothelial cells in the constricted portions, smooth muscle bundles were found. The spiral structures gradually became irregular in the collecting veins and discontinuous to form shallow constrictions in cast thicker branches of the intrahepatic veins. A single, fine spindle of the central vein was formed by the arrangement of liver cells. The spiral structures of the sublobular vein were formed by smooth muscle bundles. Irregularity of the spiral structures in the collecting veins was caused by smooth muscle bundles anastomosing with adjacent ones. Disappearance of the spiral structure in cast thicker branches of the intrahepatic veins was due to absence of muscle bundles.

Animals↗
PubMed1995

Oxidative damage of bovine serum albumin and other enzyme proteins by iron-chelate complexes.

Direct oxidative protein damage by iron-nitrilotriacetate (NTA), as well as physiological iron complexes, iron-citrate and iron-ADP was studied in the presence or absence of H2O2, using bovine serum albumin (BSA), glucose-6-phosphate dehydrogenase (G-6-PD), glutathione reductase (GSSGRase) and catalase as the target proteins. Both Fe(III)NTA+H2O2 and Fe(II)NTA+H2O2 caused marked BSA fragmentation which accompanied the decrease in the intrinsic tryptophan fluorescence and appearance of bityrosine fluorescence. However, Fe(III)citrate+H2O2 showed only slight BSA fragmentation. In the absence of H2O2, Fe(II) NTA but not Fe(III)NTA caused similar but slight BSA fragmentation, which depended on the molecular oxygen. Fe(II)citrate also showed O2-dependent BSA fragmentation to a comparable degree, however, Fe(II)ADP showed no detectable BSA damage. BSA fragmentation by Fe(II)NTA+O2 and by Fe(III)NTA+H2O2 resulted in the appearance of the new alpha-amino groups. Electron spin resonance study using 5,5-dimethyl-1-pyrroline N-oxide (DMPO) as a spin trapping reagent showed DMPO-OH spin adduct, which suggests the presence of hydroxyl radical, in Fe(III)NTA+H2O2, but not in Fe(II)NTA+O2 system. Fe(II)NTA inactivated G-6-PD and GSSGRase in a O2-dependent manner, however, G-6-PD was more susceptible to the damage. This enzyme inactivation also accompanied the protein fragmentation and was not due to simple sulfhydryl oxidation. Catalase was not significantly inactivated nor fragmented by Fe(II)NTA+O2. These findings suggest that the interaction between proteins and iron-chelate complexes is important in iron catalyzed oxidative damage, and that the structure of the chelating agent may determine the target molecules.

Animals↗
PubMed1995

Biallelic inactivation of the APC gene in hepatoblastoma.

Familial adenomatous polyposis (FAP) is an inherited disorder caused by germline mutation of the adenomatous polyposis coli (APC) gene. Increased risk of hepatoblastoma (HBL) in FAP kindreds has been reported. To determine whether inactivation of the APC gene plays a role in development of HBL, 13 sporadic infantile hepatic tumors were analyzed for genetic alterations in the APC gene. A PCR-mediated RNase protection analysis was performed to detect subtle genetic alterations in the mutation cluster region and in exons 3 and 4 of the APC gene. The results showed that a G to T transversion at the splice acceptor site of the intron 3-exon 4 junction had occurred in one HBL. Sequence analysis of normal tissue of the patient proved the mutation to be germinal. Southern blot analysis at the APC locus revealed that the tumor had lost the opposite allele and was isodisomic at this locus. RNA analysis indicated that the tumor contained only the small APC transcript, from which exon 4 was entirely absent. Since abnormal splicing causes termination due to frameshift, it was hypothesized that only the truncated APC protein was expressed in this tumor. These findings suggest that inactivation of the APC gene is closely related to tumorigenesis of HBLs in FAP patients.

Alleles↗