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H Naka

Publications and source records attributed to H Naka.

At least 37 records · Page 2Linked to original sources
PubMed1996

Transcriptional regulation of the human factor IX promoter by the orphan receptor superfamily factor, HNF4, ARP1 and COUP/Ear3.

A study of the human clotting factor IX promoter by DNase I footprinting and gel shifts in vitro, and by functional analysis of HepG2 cells in vivo, suggests that the liver-enriched transcription factor, HNF4, is involved in transactivating two cis-acting elements, i.e. X (nucleotides -15 to +3) and Y (nucleotides +15 to +36), in addition to the well-known element centred around nucleotide -20. Other members of the orphan receptor superfamily, e.g. ARP1 and COUP/Ear3, repress the factor IX promoter possibly by competition with HNF4 binding sites in the X and Y elements, but probably not at the -20 element. Mutations at -6 in the promoter, similar to those found in patients with haemophilia B, hinder HNF4 binding and transactivation of the X element, suggesting that impaired HNF4 binding contributes to the down-regulation of the factor IX expression in these patients, but is unlikely to be the only factor involved.

Base Sequence↗
PubMed1996

Cytokine effects on phagocytosis of rod outer segments by retinal pigment epithelial cells of normal and dystrophic rats.

PURPOSE: Phagocytosis of rod outer segments (ROS) is an important function of retinal pigment epithelial (RPE) cells. Since the details of the process are not fully known, we studied effects of cytokines produced by RPE and photoreceptor cells on phagocytosis of ROS by rat RPE cells. METHODS: RPE cells were isolated and cultivated from two strains of rats: Sprague-Dawley (SD) rats with normal phagocytosis and Royal College of Surgeons (RCS) rats, which have genetic deficiencies in ROS phagocytosis. A double immunofluorescence staining technique was used to study the effects in vitro of several cytokines on phagocytosis of ROS. RESULTS: We found that transforming growth factor beta-1 (TGF-beta 1) had dose-dependent effects on RPE cells of both strains of rat: at a concentration of 10 ng/ml, TGF-beta 1 significantly (p < 0.01) reduced total ROS (to 74% of control in SD rats and to 51% of control in RCS rats), reduced bound ROS (to 56% of control in SD rats and to 48% in RCS rats), and increased the ratio of ingested ROS to total ROS (to 140% in SD rats but not significantly in RCS rats). Treatment of medium with anti-TGF-beta 1 antibody before incubation of RPE cells of SD rats with TGF-beta 1 decreased the magnitude of these effects. The cytokine acidic fibroblast growth factor (aFGF, 10 ng/ml) affected RPE cells of SD rats only, decreasing ROS ingested to 56% of control and the ratio of ingested ROS to total ROS to 64% of control. We also examined effects of basic fibroblast growth factor and insulin-like growth factor. None of the cytokines tested increased ingestion of ROS by RPE cells of RCS rats. CONCLUSIONS: Our results suggest that TGF-beta 1 and aFGF have roles in regulating ROS phagocytosis by normal and dystrophic RPE cells in the rat.

Animals↗
PubMed1996

Lysosomal enzyme activities in cultured retinal pigment epithelial and glial cells of RCS rat.

PURPOSE: To compare the activities of acid phosphatase, N-acetyl-beta-glucosaminidase and alpha-mannosidase in cultured retinal pigment epithelium (RPE) and glial cells of Royal College of Surgeons (RCS) rat with those in Long Evans (LE). METHODS: The cultured RPE and glial cells of RCS and LE rat were plated into the same 96 well microtitre, and the biochemical method in microsystem were used for enzyme assays. RESULTS: The activities of acid phosphatase and N-acetyl-beta-glucosaminidase are higher by, respectively, 30% and 46% in cultured RPE of RCS rat than LE rat. The activity of alpha-mannosidase has no significant difference. The activities of 3 enzymes in the retinal glial cells derived from RCS rats are higher than LE rat by 13% to 77%. CONCLUSION: These results suggest that the high activities of lysosomal enzymes in RCS RPE and glial cells may play an important role in the pathogenesis of retinal dystrophy.

Acetylglucosaminidase↗
PubMed1995

A rapid method for isolation of retinal pigment epithelial cells from rat eyeballs.

A new, simple method for isolating retinal pigment epithelial (RPE) cells from rat eyeballs was developed: incubation of the eyeballs in 0.1% proteinase K solution. This method yielded an average of 4 x 10(4) viable RPE cells from each Sprague-Dawley rat eyeball in 1 h. These RPE cells were hexagonal and had cytokeratin in their cytoplasm and numerous microvilli on their surface, similar to RPE cells evaluated in vivo. The results of this study thus show that our method for incubating eyeballs in proteinase K can provide good-quality RPE cells in sufficient quantities for study in a short time.

Animals↗
PubMed1995

[Quality control of enzyme immunoassay--assurance and control of analytical sensitivity, accuracy and precision].

Although the basic concept for quality control of enzyme immunoassay (EIA) is the same as that of quality control of the usual chemical analysis, immunological analytic methods including enzyme immunoassay have some specific features depending on the method as compared with the chemical method. In addition to the usual QC method, therefore, it is necessary to add some QC techniques to control the variables derived from the method. In accuracy control of EIA, standard materials, reagents and analytical equipment will be the major sources of error. Points to be considered in accuracy control are described. In precision control of EIA, between-run precision is generally larger than within-run precision. In consideration of the characteristics, mean-Rs-R control chart method and Z-V control chart method appropriate for immunological method are described. Analytical sensitivity expressed as detectability and detection limits is very important in EIA. A procedure to determine the detection limits is described in detail. Between reagent lot difference in immunological reagent is considerably larger than that of chemistry reagent and a shift of the point on the control chart is not adequate to assess the reliability of the patient data. Therefore, an evaluation method of the between reagent lot difference is described. General procedures of precision control are not described here because the procedures are well known.

Immunoenzyme Techniques↗
PubMed1993

Molecular defect in factor IX Tokyo: substitution of valine-182 by alanine at position P2' in the second cleavage site by factor XIa resulting in impaired activation.

Utilizing polymerase chain reaction and directly sequencing the amplified exon 6 of the factor IX gene derived from a mild hemophilia Bm patient, we have identified a T to C mutation at nucleotide 20,525. This point mutation predicted a Val182 to Ala substitution in the abnormal factor IX molecule, designated as factor IX Tokyo. The patient manifested a low factor IX activity and a moderately prolonged ox-brain prothrombin time but a normal factor IX antigen level in plasma. Immunopurified factor IX derived from the patient was found to have a normal molecular weight but a reduced specific activity (23% of normal). Limited proteolysis by activated factor XI or by a snake venom-derived factor X-activating enzyme was considerably delayed, indicating the presence of structural alteration(s) most probably at or near the second enzyme-cleavage site. Once activated, however, factor IXa Tokyo was able to activate factor X normally and was inactivated by antithrombin III also in a normal fashion. The structural model of factor IXa and a docking model of factor IX and activated factor VII (factor VIIa) suggested that the Val182 to Ala substitution would not affect the local conformation of the catalytic domain. This mutation would rather loosen the fitness of the molecule into the substrate-binding pocket of factor VIIa due to a shorter side chain of the Ala substitution at the P2' position of the second cleavage site.

Adolescent↗
PubMed1993

Myocardial reperfusion can be predicted by myoglobin/creatine kinase ratio of a single blood sample obtained at the time of admission.

To evaluate noninvasive markers for determining the reperfusion status without coronary angiography (CAG) or serial blood sampling in patients with acute myocardial infarction (AMI), two markers were examined: (1) serum myoglobin (Mb) level and (2) serum myoglobin/creatine kinase ratio (Mb/CK). Before emergency CAG a blood sample was drawn from 72 AMI patients within 6 hours after the onset of AMI. CAG revealed thrombolysis in myocardial infarction grades (TIMI) 0 to 1 in 56 and TIMI 2 to 3 in 16 patients (spontaneous reperfusion). No patients had received thrombolytic therapy before admission. TIMI 0 to 1 patients were characterized with lower Mb levels than TIMI 2 to 3 patients at admission (346 +/- 476 vs 1558 +/- 2005, mean +/- SD, p < 0.001). Furthermore, the mean Mb0/CK0 ratio in TIMI 2 to 3 patients, who had already achieved the reperfusion at admission, was significantly higher than that in patients with TIMI 0 to 1 patients (6.5 +/- 3.9 vs 2.1 +/- 1.8, mean +/- SD, p < 0.0001). When Mb0/CK0 > 5.0 was assumed to indicate the sufficient reperfusion at admission, the sensitivity, specificity, and accuracy evaluating the reperfusion status were 75%, 96%, and 92%, respectively. It can be concluded that the reperfusion status can be predicted satisfactorily by a single blood sample obtained at the time of admission without CAG.

Aged↗
PubMed1993

[Turning point in quality control: problems at present and themes in future].

Quality control in clinical laboratory has a longer than forty-year history after its introduction. At present, quality control has been considered as one of essential tools to evaluate the quality of clinical laboratory data. However, several problems to be solved have still remained. I clarify the problems at present and declare the themes in future. Problems of internal quality control (IQC): Analytical precision of clinical laboratory test has remarkably improved recent years because of the advancement of technologies including analytical procedures and instruments. However, analytical accuracy has not attained the subjects. Furthermore, QC procedures have been converting into subjects and it has been generally considered that using a lot of QC material and QC method is a good manner. As a result, fundamental control procedures such as material control, reagent control and instrument maintenance have been ignored. Problems of external quality control (EQC): It has been considered that EQC serves as an indicator of analytical accuracy and shows the average analytical performance of all participants. However, some problems have remained as follows: (1) Problem of samples for proficiency testing. (2) Problem of classification of peer group. (3) Problem of target value. (4) Problem of evaluation criteria. In general, various IQC methods have been used without careful consideration. However, I would like to emphasize that we have to select the best QC method which can detect the error to be checked according to the method performance. For this reason, we have to grasp the purpose of QC and be careful to not change the subjects into the QC procedure.(ABSTRACT TRUNCATED AT 250 WORDS)

Forecasting↗
PubMed1991

Factor IX Amagasaki: a new mutation in the catalytic domain resulting in the loss of both coagulant and esterase activities.

Factor IX Amagasaki (AMG) is a naturally occurring mutant of factor IX having essentially no coagulant activity, even though normal levels of antigen are detected in plasma. Factor IX AMG was purified from the patient's plasma by immunoaffinity chromatography with an anti-factor IX monoclonal antibody column. Factor IX AMG was cleaved normally by factor VIIa-tissue factor complex, yielding a two-chain factor IXa. Amino acid composition and sequence analysis of one of the tryptic peptides isolated from factor IX AMG revealed that Gly-311 had been replaced by Glu. We identified a one-base substitution of guanine to adenine in exon VIII by amplifying exon VIII using the polymerase chain reaction method and sequencing the product. This base mutation also supported the replacement of Gly-311 by Glu. In the purified system, factor IXa AMG did not activate factor X in the presence of factor VIII, phospholipids, and Ca2+, and no esterase activity toward Z-Arg-p-nitrobenzyl ester was observed. The model building of the serine protease domain of factor IXa suggests that the Gly-311----Glu exchange would disrupt the specific conformational state in the active site environment, resulting in the substrate binding site not forming properly. This is the first report to show the experimental evidence for importance of a highly conserved Gly-142 (chymotrypsinogen numbering) located in the catalytic site of mammalian serine proteases so far known.

Amino Acid Sequence↗
PubMed1991

[The determination of CK-MB protein mass].

It has been well known that the determination of CK-MB is a useful parameter for the diagnosis of acute myocardial infarction (AMI). Currently, several methods such as Electrophoresis, Ion-exchange chromatography, Immunoinhibition method and Protein mass determination are available. From a point of the diagnosis of AMI, the method should be satisfied with the requirements of high speed, ease to perform, high analytical specificity and high analytical sensitivity. However, there are no appropriate methods which can satisfy all of the requirement. In this paper, we have introduced the present situation concerning the determination of CK-MB in our hospital and discussed the results of study on the IMx method based on the determination of protein mass of CK-MB. We obtained good results in the fundamental study and found some advantages of protein mass determination. The first advantage was its high analytical specificity by use of monoclonal antibody. The second advantage was its high analytical sensitivity because of its low detection limit. The third advantage was the stability of sample because the antigenicity of CK-MB to the antibody of reagent is stable comparing with that of enzyme activity. From those advantages, the mass determination of CK-MB will be a useful method for the diagnosis of AMI in the near future.

Creatine Kinase↗
PubMed1991

Rapid identification of Escherichia coli from urine by using Fluorocult media.

For rapid identification of Escherichia coli, we evaluated Fluorocult MacConkey Agar, Fluorocult Laurylsulfate Broth and Bactident E. coli, which are incorporating fluorogenic substrate, MUG (4-methylumbeliferyl-beta-D-Glucuronide) that specifically reacts with E. coli. To assess the specificity and sensitivity of Fluorocult MacConkey Agar and Laurylsulfate Broth, beta-D-glucuronidase; beta-GUR activities of 264 strains from urine including 72 of E. coli were investigated. For both media, sensitivity was 92% and specificity was 100%. When there was 10(8) c.f.u./ml of E. coli in urine specimen, incubation times required for positive fluorescence by Fluorocult MacConkey Agar, Laurylsulfate Broth, and Bactident E. coli were 8 h, 4 h and 15 min, respectively. Influence of drugs in urine to fluorescence reaction was not observed.

Bacteriological Techniques↗
PubMed1991

[The determination of serum and urine myoglobin].

We have reviewed the current methods of determining serum and urine myoglobin. Qualitative determination of urine myoglobin has been possible for over 20 years, but the quantitative determination is a recent development. Between 1963 (spectrophotometry) and 1978 (radioimmunoassay, RIA), efforts have been made to develop a more sensitive determination method. The RIA method thus developed has a sensitivity as high as 1 ng/ml. Such methods are valuable in the diagnosis of acute myocardial infarction. Recently, simple, rapid, and non-isotopic method such as enzyme immunoassay (EIA) and latex agglutination test have been developed and made rapid determination possible. We applied the "Mb-latex [Seiken]", one such latex agglutination method to the TBA-30 R single-multi type automated analyzer. We obtained good results in the fundamental study such as in precision and accuracy. The reference ranges obtained using serum and urine samples corresponded to the values reported by others with the exception of the lower limit of the ranges. Proficiency testing data using the same reagents and same samples at five laboratories revealed some systematic biases. The reasons for such interlaboratory differences is not clear. However, these systematic biases may be due to the type of equipment, the type of calibration procedure and others including reagents and standard solutions. We are continuing our effort to improve the reliability of interlaboratory data.

Female↗
PubMed1990

[Multiple primary cancers of the head and neck].

From January 1985 to June 1988, the authors have treated 138 cases of head and neck cancers. Among this number, six cases (4.3%) involved patients with a multiple primary cancer. With the exception of 1 case, all patients were male with a history of heavy smoking and excessive drinking. The primary cancer of the head and neck was most frequently located in the hypopharynx, and a secondary multiple cancer in the upper digestive tract especially the esophagus. Although we were unable to detect an early esophageal cancer by an esophagogram in some cases, each lesion could be detected by using lugol stain and gastrointestinal endoscopy.

Aged↗
PubMed1989

First trimester prenatal diagnosis of haemophilia A using factor VIII gene probe.

Accurate first-trimester prenatal diagnosis was achieved in a Japanese haemophilia A family by the use of a restriction fragment length polymorphism (RFLP) located within the F.VIII gene. Since the pregnant woman's heterozygosity for BclI polymorphism in F.VIII/intron 18 (F8A) probe was informative, chorionic villus sampling (CVS) was performed at 9 weeks of gestation. Restriction analysis showed that the fetus was heterozygous for the BclI site and had received a normal paternal X chromosome (0.9 kb) and a normal maternal X (1.2 kb). Therefore, we concluded that the fetus was a non-carrier female. Pregnancy went to term and woman gave birth to an apparently healthy female. At one week after birth a coagulation study confirmed that the newborn infant is not a carrier. The first-trimester prenatal diagnosis of haemophilia A is possible by CVS due to a RFLP in the F.VIII gene.

Blotting, Southern↗