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Biomedical subjects

T Okazaki

Publications and source records attributed to T Okazaki.

At least 271 records · Page 15Linked to original sources
PubMed1992

Serum erythropoietin concentrations and iron status in patients on chronic hemodialysis.

We studied the relationship between serum erythropoietin (EPO) concentration and iron status in 67 patients undergoing chronic hemodialysis. Serum concentrations of EPO were measured by RIA with recombinant human EPO. The geometric mean of the serum EPO concentration was 10.9 int. units/L (mean +/- SD range = 7.8 - 15.3 int. units/L) in hemodialysis patients, considerably lower than that in normal subjects (12.9 int. units/L). We found no significant correlation between concentrations of serum EPO and hemoglobin in hemodialysis patients, but found a significant negative correlation between serum concentrations of EPO and iron in hemodialysis patients. Moreover, we also found a significant positive correlation between the EPO concentration and the unsaturated iron-binding capacity (UIBC) in serum, and a significant negative correlation between the serum concentrations of EPO and ferritin in hemodialysis patients. Several patients who had relatively high EPO concentrations for hemodialysis patients also had low iron concentrations, high UIBC values, and low ferritin concentrations. These findings suggest that iron was utilized even at these EPO concentrations, which were very low for the degree of anemia observed in the hemodialysis patients.

Adult↗
PubMed1992

[Increased red-cell sodium-lithium countertransport activity and urinary 11-dehydrothromboxane B2 during pregnancy].

The activity of Na-Li countertransport (CT), a marker of the risk of essential hypertension, was determined in 55 primigravid women during pregnancy, together with urinary 11-dehydro-thromboxane B2 (11-dehydro-TXB2) as a marker of thromboxane A2 synthesis. The mean Na-Li CT (mean +/- SEM) value was increased significantly at 20 weeks gestation and thereafter, and reached higher levels in late pregnancy than in non-pregnant controls (0.31 +/- 0.02 vs. 0.21 +/- 0.01mmol per hr per liter RBC, p less than 0.05). Fifty five primigravid women could be divided into two groups, depending upon Na-Li CT activity either higher or lower than the value of 0.25mmol per hr per liter RBC at any time in the pregnancy up to term. At 20 weeks gestation all but one of 13 women in the lower-activity group had Na-Li CT activity less than 0.20 mmol per hr per liter RBC, and none developed PIH, whereas out of 42 women in the higher-activity group, all but one had Na-Li CT activity more than this value, and 8 developed PIH. Urinary 11-dehydro-TXB2 increased as pregnancy progressed, maximum levels being attained in women at term, about 3 times higher than in controls (4.19 +/- 0.35 vs. 1.36 +/- 0.10 ng per mg creatinine, p less than 0.05). Although the formation of thromboxane A2 was reported to be higher in pregnancy complicated by hypertension, no significant difference existed in the levels of 11-dehydro-TXB2 between women with PIH and women with uncomplicated pregnancy.(ABSTRACT TRUNCATED AT 250 WORDS)

Biological Transport↗
PubMed1991

Negative regulatory elements in the human parathyroid hormone gene.

We have identified and characterized a pair of negative regulatory elements far upstream of the transcription start site of the human parathyroid hormone (hPTH) gene. Transfection of various types of cultured cells with a fusion plasmid containing 4.7 kilobase pairs of the 5'-flanking portion of the hPTH gene linked to the chloramphenicol acetyltransferase (CAT)-coding sequence generated only 10% of the CAT activity of a plasmid containing 684 base pairs of the 5'-flanking region of the hPTH gene. Deletion analyses reveal that there are at least two separate upstream DNA elements in the hPTH gene responsible for the negative regulation. We find that these cultured cells possess nuclear factors which specifically bind to several short DNA sequences within these elements and that these sequences can suppress transcription of the hPTH gene.

3T3 Cells↗
PubMed1991

Participation of the histone-like protein HU and of IHF in minichromosomal maintenance in Escherichia coli.

The closely related Escherichia coli genes, hupA, hupB, himA and himD (hip), encode the bacterial histone-like protein subunits, HU-2, HU-1, IHF chi and IHF beta, respectively. We report here that E. coli minichromosomes [plasmids (2.7-12.2 kb) with oriC] carrying the intact mioC region were unable to transform mutants deficient in both HU and integration host factor (IHF), whereas they could transform mutants deficient in either HU or IHF as efficiently as the wild-type strain. Minichromosomes carrying a deletion of the proximal part of mioC or a DnaA box just upstream from mioC could not transform cells deficient in IHF, but could transform cells deficient in HU. These results suggested that HU and IHF participate in minichromosomal replication from oriC in E. coli.

Bacterial Proteins↗
PubMed1991

Cloning and characterization of a DNA fragment that complements the nfxB mutation in Pseudomonas aeruginosa PAO.

The 2.2-kilobase DNA fragment that can complement the nfxB mutation in Pseudomonas aeruginosa PAO was cloned from chromosomal DNA of P. aeruginosa PAO1. The nfxB mutants show an increase in resistance to quinolones and hypersusceptibility to beta-lactam and aminoglycoside antibiotics. In the mutants, a 54 kDa outer membrane protein newly appeared. The phenotype was restored to the wild-type by transformation with plasmid carrying the 2.2-kb DNA fragment.

Chromosomes, Bacterial↗
PubMed1991

Specificity of recognition sequence for Escherichia coli primase.

We have surveyed the frequency of each of 64 trinucleotide permutations at every nucleotide frame located from 1 to 15 nucleotides upstream of primer RNA-DNA transition sites mapped within a 1.5 kb region of the bacteriophage lambda genome and a 1.4 kb region of the Escherichia coli genome. We have demonstrated that in both systems initiation of DNA synthesis strongly correlates with a CAG sequence located 11 nucleotides upstream of the DNA start sites. Based on the examination of various reports of the priming reaction catalyzed by E. coli primase in vivo and in vitro, we propose that (i) E. coli primase itself recognizes a 3'GTC 5' sequence on the template strand, (ii) DnaB helicase releases the specificity of E. coli primase and, (iii) the consensus recognition sequence for E. coli primase associated with DnaB helicase is 3'PuPyPy 5'.

Bacteriophage lambda↗
PubMed1991

Concurrent transcription from the gid and mioC promoters activates replication of an Escherichia coli minichromosome.

The origin of replication of the Escherichia coli chromosome (oriC) is located in an intercistronic region between the gidA and the mioC genes. The possibility that transcription from the promoters of these two genes is involved in minichromosome replication was examined. Inactivation of the gid promoter led to a reduction in transformation frequency with an oriC plasmid but inactivation of the mioC promoter did not. The decrease in transformation frequency was most pronounced when both promoters were inactive. Under conditions that selected for plasmid-harboring cells, mutation of the gid promoter caused efficient multimerization or integration of oriC plasmids into the chromosomal oriC region and loss of free plasmid molecules. These changes in plasmid structure were also observed, albeit less frequently, with some plasmids defective in mioC promoter activity. In an in vitro DNA replication system for oriC DNA, plasmids with a defective gid promoter had greatly reduced template activity and essentially no replication occurred when both promoters were inactive. These results suggest that coupled transcription starting from the gid as well as the mioC promoter activates initiation of plasmid replication, the major contribution being made by gid transcription. These two promoters are suggested to be under stringent control.

Base Sequence↗
PubMed1991

Transforming genes and chromosome aberrations in therapy-related leukemia and myelodysplastic syndrome.

The presence of activated transforming genes was investigated in four patients with therapy-related leukemia and in three with therapy-related myelodysplastic syndrome. DNA of bone marrow cells from six of the patients exhibited transforming activity in the tumorigenicity assay. Five of the six patients who were positive in the tumorigenicity assay contained activated N-ras oncogenes, and three contained activated K-ras oncogenes. Thus, concurrent activation of N-ras and K-ras oncogenes was observed in two patients. In vitro DNA amplification followed by oligonucleotide dot-blot analysis was used to investigate mutations in codons 12, 13, and 61 of the N-ras and K-ras oncogenes. Two patients exhibited an N-ras mutation, substituting aspartic acid (GAT) for glycine (GGT), and three patients exhibited an N-ras codon 13 mutation, substituting valine (GTT) for glycine. Two patients exhibited K-ras codon 12 mutations, substituting aspartic acid (GAT) or cysteine (TGT) for glycine (GGT), respectively, and one case exhibited a K-ras codon 61 mutation, substituting lysine (AAA) for glutamic acid (CAA). Cytogenetic analysis revealed that loss of chromosome 7 was frequent (four patients: 57%). Our data indicate that activation of N-ras and K-ras genes, as well as loss of heterozygosity for specific alleles on chromosome 7, plays a more important role in the leukemogenesis of both therapy-related leukemia and myelodysplastic syndrome.

Aged↗
PubMed1991

Expression of c-fos and c-myc in Raji Burkitt's lymphoma cells during the progression of DMSO-induced G1 cells into S phase.

Using flow cytometry, we have recently found that dimethyl sulfoxide (DMSO) reversibly induces G1-arrest in the cell cycle of human lymphoid cell lines such as Raji, Akata, and Molt-4. Here we investigated c-fos and c-myc expression in Raji Burkitt's lymphoma cells at DMSO-induced G1 arrest and after release from DMSO. A small but significant accumulation of c-fos mRNA was observed in G1-arrested Raji cells after treatment with 1.5% DMSO for 96 h. When G1-arrested Raji cells were transferred to DMSO-free medium, a transient increase in c-fos transcripts was detected 30-60 min after the release. The steady state level of c-myc transcripts in G1-arrested Raji cells was found to be one-third that in the log-phase cells. After removal of DMSO, the level of c-myc mRNA was restored and reached a maximum at 4.5-6 h. Immunoblot analysis with a monoclonal antibody against human c-myc protein indicated that c-myc protein in the G1-arrested cells was decreased less than one-tenth that in the log-phase cells. The level of c-myc protein gradually increased after the release from DMSO and reached a maximum at 6-9 h.

Blotting, Northern↗
PubMed1991

Serum transferrin as a marker of bone growth in boys: correlation with serum alkaline phosphatase activity, plasma insulin-like growth factor 1 and rate of growth in height.

Transferrin (TF) has a growth promoting activity in cell culture. The aim of this work was to study possible relationships between serum TF, alkaline phosphatase activity (ALP), plasma insulin-like growth factor 1 (IGF-1) levels and rate of height increase in boys. 149 boys aged 13-15 yrs were studied. TF levels were measured using turbidimetric method. The serum levels of ALP could be used as a biochemical marker for bone formation. Significant correlation was found between serum TF levels and ALP levels (r = 0.31, P less than 0.0005). The TF levels are higher in iron-deficiency anemia. The hemoglobin (Hb) and serum ferritin were measured in all boys. Thirty-one of 149 boys had no iron-deficiency anemia (Hb 14.0 g/dl and serum ferritin 23 ng/ml). The rate of growth in height was estimated over a 5 month period. In these boys, the rate of growth in height was significantly correlated with serum TF levels (r = 0.37; P less than 0.05). A significant correlation was found between serum TF levels and plasma IGF-1 levels (r = 0.45; P less than 0.05). These data indicate that serum TF levels may be a marker of skeletal growth in normal boys.

Adolescent↗
PubMed1991

Purification of a human centromere antigen (CENP-B) and application of DNA immunoprecipitation to quantitative assay for anti-CENP-B antibodies.

Centromere protein-B (CENP-B) was purified from HeLa nuclear extract by using a combination of Q-sepharose ion change and oligonucleotide sepharose column chromatography. CENP-B was purified more than 10,000 times and was analyzed by immunoblotting and DNA immunoprecipitation. Purified CENP-B was used as an antigen to develop DNA immunoprecipitation for rapid and specific detection of anti-CENP-B antibody in human sera. In this analysis, none of the tested sera immunoprecipitated DNA alone. All of the 40 anticentromere antibody (ACA)-positive sera immunoprecipitated CENP-B-alphoid DNA fragment complex, whereas 10 healthy control sera and 10 other autoantibody positive sera did not. Five of the ACA-positive sera, which did not show reactivity of CENP-B in immunoblotting analysis, immunoprecipitated CENP-B-DNA complex. In some sera antigenicity to CENP-B may be weakened by denaturation.

Autoantibodies↗
PubMed1991

Immunological classification of childhood acute lymphoblastic leukemia.

Seven hundred and forty-four newly diagnosed patients with acute leukemias between 1978 and 1990 were classified on the basis of immunological phenotypes. The majority of the patients were enrolled in the Tokyo Children's Cancer Study Group (TCCSG) studies. The incidence of subclassification of acute leukemias in this study was as follows: 522 patients with ALL (70%), 139 patients with ANLL (18%), 29 patients with biphenotypic leukemia, 8 patients with Ph1-positive acute leukemia (Ph1-AL), and 45 patients with infant leukemia. ALLs were classified into common ALL (cALL, 77%), T-ALL (15%), B-ALL (4%), and unclassified ALL (3%). The incidence of ALL subtypes in this study reflected those of TCCSG. Biphenotypic leukemias were categorized into 4 groups as follows; 1) cALL with positive myelomonocytic antigen(s) (N = 11), 2) unclassified ALL with positive myelomonocytic antigen(s) (N = 5), 3) ANLL with positive B-lymphoid antigen(s) (N = 4), and 4) acute leukemia with positive T-lymphoid and myeloid antigen(s). Infant leukemias were classified into ALL type (N = 27) and ANLL type (N = 18). In this present study, clinical features and immunological phenotypes of the acute leukemias with a poor prognosis, i.e. biphenotypic leukemia, Ph1-AL, and infant leukemia are analyzed and discussed.

Adolescent↗
PubMed1991

[A study of Ureaplasma urealyticum pathogenicity in human genitourinary tract].

Ureaplasma urealyticum was investigated in urine from 765 outpatients who visited Jikei University Affiliated Hospital and Tokyo Metropolitan Taito Hospital from June, 1988 to December, 1989 in order to clarify the pathogenicity of U. urealyticum in human genitourinary tract. U. urealyticum in urine was detected by means of Taylor-Robinson's method. The positive rates of U. urealyticum were 31.5% in 146 patients with gonococcal urethritis, 33.8% in 334 patients with non-gonococcal urethritis, 17.5% in non-bacterial chronic prostatitis and 27.5% in the other patients without infectious diseases, respectively; no significant difference was seen among these groups. U. urealyticum was detected in the urine from 32.1% of the 28% patients who were younger than 12. However, U. urealyticum was detected in the urine from 5.6% of the 18 patients who were older than 70. Therefore, there was no relationship between the age and U. urealyticum-positive rate in urine. Furthermore, there was no relationship between the detection of U. urealyticum and the subjective and objective findings in the patients with urethritis before and after the treatment. From these results, it is presumed that U. urealyticum has no pathogenicity in human genitourinary tract.

Adolescent↗