Biomedical subjects

K Arai

Publications and source records attributed to K Arai.

At least 253 records · Page 14Linked to original sources

PubMed1998

[Studies of prostate-specific antigen (PSA) immunoassays--differences in characteristic of immunoreactivity and reference materials among the kits].

PURPOSE: We conducted this study to examine differences in characteristics of immunoreactivity for free PSA and alpha(1)-antichymotrypsin complex PSA (ACT-PSA) as well as in compositions and concentrations of PSA reference materials among commercially available PSA kits. METHODS: Fractionated serum samples using a Sephacryl S-200 column were measured by Tandem-R, Delfia-PSA, Ab bead PSA, ACS-PSA, Markit-M and gamma-seminoprotein (gamma-Sm) kits. The calibrators of Tandem-R, Delfia-PSA, Ab bead PSA and Markit-M were fractionated by the same method and measured by Tandem-R. The calibrators of Delfia-PSA, Ab bead PSA and Markit-M and control serums of ACS-PSA were measured by Tandem-R. RESULTS: Although the characteristic of immunoreactivity of Tandem-R, Delfia-PSA, and Ab bead PSA were found to be similar, they were not shown identical. ACS-PSA was proved to recognize free PSA greater than above three PSA kits, while Markit-M could scarcely detect free PSA. gamma-Sm recognized only free PSA. The calibrators of Tandem-R, Delfia-PSA, Ab bead PSA and Markit-M were proved to be only free PSA. The linear correlation was obtained between Tandem-R and Delfia-PSA or Ab bead PSA or Markit-M. The ratio of Delfia-PSA to Tandem-R, Ab bead PSA to Tandem-R and Markit-M to Tandem-R was 0.66, 0.93 and 2.2, respectively. With regard to relation of ACS-PSA and Tandem-R, two ratios of 0.22 and 0.25 were obtained between the two kits according to the different concentrations of control sera. CONCLUSION: The present studies suggest that the difference in PSA values among the commercial PSA kits results from (1) different characteristics of immunoreactivity for ACT-PSA and free PSA among PSA kits, (2) compositions of PSA calibrators among the kits, and (3) different concentrations of PSA calibrators among the kits.

Biomarkers, Tumor↗

PubMed1998

[Studies of type I collagen related substances as bone metastatic markers of prostate carcinoma with special regard to serum carboxyterminal propeptide of type. I. Procollagen (PICP), cross-linked carboxyterminal telopeptide of type I collagen (ICTP) and Urinary deoxypyridinoline levels].

BACKGROUND: To investigate if serum levels of carboxyterminal propeptide of type I procollagen (PICP), cross-linked carboxyterminal telopeptide of type I collagen (ICTP) and urinary levels of deoxypyridinoline (D-Pyr) are useful markers of bone metastasis in patients with prostate carcinoma, we measured these markers in patients with untreated benign prostatic hyperplasia (BPH) and untreated prostate carcinoma (PCA). METHODS: Serum PICP, ICTP and urinary D-Pyr levels were determined in 53 patients; 16 patients with BPH, 15 patients with PCA without bone metastasis (stage A, B, C and D1) and 22 patients with PCA with bone metastasis (stage D2). At the same time correlations among these markers and serum total alkaline phosphatase (ALP) activity were studied. RESULTS: Serum PICP, ICTP and urinary D-Pyr levels in the PCA patients with bone metastasis were significantly higher than those of BPH. The serum levels of PICP in patients with PCA with bone metastasis group were significantly higher than those of without bone metastasis group. The serum levels of ICTP in patients with PCA without bone metastasis group were significantly higher than those of BPH group, while no significant difference was observed between PCA group with and without bone metastasis. In the PCA patients with bone metastasis, serum PICP and serum total alkaline phosphatase (ALP) activity were significantly correlated (r = 0.80). In these patients, serum ICTP and urinary D-Pyr levels were also significantly correlated (r = 0.70). CONCLUSION: These results suggest that serum PIPC, ICTP and urinary D-Pyr are the useful markers to quantitate bone metastasis in the patients with PCA. Moreover, the determination of serum ICTP levels may be significant for detecting occult bone metastasis in the patients with PCA.

Aged↗

PubMed1998

[Intrahepatic arterial infusion chemotherapy with angiotensin II for liver metastasis from gastric cancer].

The theoretical purpose of induced hypertensive chemotherapy used together with injection of Angiotensin II is to increase the delivery of anticancer drug to the target tumor tissue by increasing blood flow in the tumor. Angiotensin II (50 micrograms) was dissolved in 50 ml of normal saline, and given through a peripheral vein by a microinfusion pump. When systolic pressure rose to about 140 to 150 mmHg, mitomycin C (10 to 20 mg/body) was given for 10 minutes via implanted port, whose tip was located in hepatic artery, followed by continuous infusion of 5-FU at 250 mg/day for 5 days. Response could be measured in 7 of all 10 cases (70.0%), CR was found in 4 and PR in 3. As for complications, one case of pseudo-aneurysm and one case of bile duct necrosis owing to drug toxicity were observed. Bone metastases or carcinomatous peritonitis occurred after a few months in two CR cases. We concluded that this mode of chemotherapy was a useful measure for the treatment of liver metastases from gastric cancer.

Aged↗

PubMed1998

[Relationship between vascular endothelial growth factors and advanced glycation end products in the human vitreous].

The relation between vascular endothelial growth factor (VEGF) and advanced glycation end product (AGE) is considered a primary factor in the development of diabetic retinopathy. Regarding the relation between VEGF in the vitreous body and pentosidine, an AGE, we compared a diabetic (DM) group (7 eyes) with a nondiabetic (nonDM) group (7 eyes), and investigated the correlation between VEGF and pentosidine by calculating the correlation coefficient. Levels of both VEGF and pentosidine were significantly higher in the DM group (p < 0.01, p < 0.05), and a positive correlation was observed between the levels of VEGF and pentosidine (r = 0.770, p < 0.001). Since it is clear that there is a relation between VEGF and pentosidine in the vitreous body, we speculated that AGE is related to the secretion of cytokine in patients with diabetic retinopathy, and that it affects the development and progression of the disease.

Adult↗

PubMed1997

Molecular cloning and functional characterization of murine cDNA encoding transcription factor NFATc.

Transcription factors of the NFAT (nuclear factor of activated T cells) family play important roles in immune and inflammatory responses by regulating the expression of genes encoding cytokines and immunoregulatory proteins. Here we describe cloning and characterization of full-length cDNA encoding murine (m) NFATc which predicts that the protein has all the conserved structural motifs of NFAT family members, including the rel homology domain, the NFAT homology domain and the nuclear translocation signals. mNFATc complexed with AP-1 bound specifically to the murine IL-2 NFAT recognition sequence and activated transcription from the co-transfected IL-2 promoter in COS-7 cells. Northern blot analysis showed that the cDNA probe hybridized with a 4.5 kb transcript which is highly inducible in murine T cells. By Northern and in situ hybridization, mNFATc transcript was detected from the early stage of development. In the mouse embryo, mNFATc transcript was strongly expressed in thymus, lung and submandibular gland and weakly in skeletal muscle and heart suggesting that mNFATc may have a role both in embryogenesis and in mature T cells.

Amino Acid Sequence↗

PubMed1997

Serum concentration of type I collagen metabolites as a quantitative marker of bone metastases in patients with prostate carcinoma.

BACKGROUND: Bone scans, widely used for the detection of bone metastases from prostate carcinoma, can neither quantitate metastatic lesions nor detect osteolytic lesions. METHODS: Serum concentrations of the carboxyterminal propeptide of Type I procollagen (PICP), the carboxyterminal pyridinoline cross-linked telopeptide of Type I collagen (ICTP), and prostate specific antigen (PSA) were measured by radioimmunoassays in 48 patients with benign prostatic hyperplasia (BPH), 25 patients with prostate carcinoma (PCA) without bone metastases, and 36 patients with PCA and bone metastases. RESULTS: Serum concentrations of PICP were significantly higher in patients with PCA with bone metastases than in patients with BPH or PCA without bone metastases. No significant differences were observed between patients with BPH and those with PCA without bone metastases. Serum ICTP concentrations were significantly higher in patients with PCA than in patients with BPH regardless of the presence or absence of bone metastases. Serum concentrations of PICP, ICTP, and PSA correlated significantly with Soloway's grading system for bone scans. The serum concentrations of PICP and ICTP in patients without bone metastases showed a significant downward trend in response to antiandrogen therapy. CONCLUSIONS: These observations suggest that the serum concentrations of PICP and ICTP are quantitative markers of bone metastases from PCA when followed serially in individual patients.

Age Factors↗

PubMed1997

Serial lectin affinity chromatography with concavalin A and wheat germ agglutinin demonstrates altered asparagine-linked sugar-chain structures of prostatic acid phosphatase in human prostate carcinoma.

Differences between human prostate carcinoma (PCA, five cases) and benign prostatic hyperplasia (BPH, five cases) in asparagine-linked (Asn) sugar-chain structure of prostatic acid phosphatase (PAP) were investigated using lectin affinity chromatography with concanavalin A (Con A) and wheat germ agglutinin (WGA). PAP activities were significantly decreased in PCA-derived PAP, while no significant differences between the two PAP preparations were observed in the enzymatic properties (Michaelis-Menten value, optimal pH, thermal stability, and inhibition study). In these PAP preparations, all activities were found only in the fractions which bound strongly to the Con A column and were undetectable in the Con A unbound fractions and in the fractions which bound weakly to the Con A column. The relative amounts of PAP which bound strongly to the Con A column but passed through the WGA column, were significantly greater in BPH-derived PAP than in PCA-derived PAP. In contrast, the relative amounts of PAP which bound strongly to the Con A column and bound to the WGA column, were significantly greater in PCA-derived PAP than in BPH-derived PAP. The findings suggest that Asn-linked sugar-chain structures are altered during oncogenesis in human prostate and also suggest that studies of qualitative differences of sugar-chain structures of PAP might lead to a useful diagnostic tool for PCA.

Acid Phosphatase↗

PubMed1997

Hematopoietic and lymphopoietic responses in human granulocyte-macrophage colony-stimulating factor (GM-CSF) receptor transgenic mice injected with human GM-CSF.

Using a clonal assay of bone marrow (BM) cells from transgenic mice (Tg-mice) expressing the human granulocyte-macrophage colony-stimulating factor receptor (hGM-CSFR), we found in earlier studies that hGM-CSF alone supported the development not only of granulocyte-macrophage colonies, but also of erythrocytes, megakaryocytes, mast cells, blast cells, and mixed hematopoietic colonies. In this report, we evaluated the in vivo effects of hGM-CSF on hematopoietic and lymphopoietic responses in the hGM-CSFR Tg-mice. Administration of this factor to Tg-mice resulted in dose-dependent increases in numbers of reticulocytes and white blood cells (WBCs) in the peripheral blood. Morphological analysis of WBCs showed that the numbers of all types of the cell, including neutrophils, eosinophils, monocytes, and lymphocytes increased; the most remarkable being in lymphocytes that contained a number of large granular lymphocytes (LGLs) in addition to mature T and B cells. However, total cellularity of the BM of the Tg-mice decreased in a dose-dependent manner when hGM-CSF was injected. In sharp contrast to the BM, spleens of the Tg-mice were grossly enlarged. Although all types of blood cells and hematopoietic progenitors increased in the spleen, erythroid cells and their progenitors showed the most significant increase. Increased numbers of megakaryocytes and LGLs were also observed in spleen and liver of the treated Tg-mice. Flow cytometric analysis showed that LGLs expanded in Tg-mice expressed Mac-1+ CD3- NK1.1+. The thymus of Tg-mice treated with hGM-CSF exhibited a dose-dependent shrinkage and a remarkable decrease in CD4+ CD8+ cells. Thus, hGM-CSF stimulated not only myelopoiesis but also erythropoiesis and megakaryopoiesis of hGM-CSFR Tg-mice in vivo, in accordance with our reported in vitro findings. In addition, hGM-CSF affected the development of lymphoid cells, including natural killer cells of these Tg-mice.

Animals↗

PubMed1997

Human and Xenopus cDNAs encoding budding yeast Cdc7-related kinases: in vitro phosphorylation of MCM subunits by a putative human homologue of Cdc7.

Saccharomyces cerevisiae Cdc7 kinase is essential for initiation of DNA replication, and Hsk1, a related kinase of Schizosaccharomyces pombe, is also required for DNA replication of fission yeast cells. We report here cDNAs encoding Cdc7-related kinases from human and Xenopus (huCdc7 and xeCdc7, respectively). The cloned cDNA for huCdc7 contains an open reading frame consisting of 574 amino acids with a predicted molecular weight of 63,847 that possesses overall amino acid identity of 32% (54% including similar residues) to Cdc7 and Hsk1. huCDC7 is transcribed in the various tissues examined, but most abundantly in testis. Three transcripts of 4.4, 3.5 and 2.4 kb in length are detected. The 3.5 kb transcript is the most predominant and is expressed in all the tissues examined. A cDNA containing a 91 nucleotide insertion at the N-terminal region of huCDC7 is also detected, suggesting the presence of multiple splicing variants. The huCdc7 protein is expressed at a constant level during the mitotic cell cycle and is localized primarily in nuclei in interphase and distributed diffusibly in cytoplasm in the mitotic phase. The wild-type huCdc7 protein expressed in COS7 cells phosphorylates MCM2 and MCM3 proteins in vitro, suggesting that huCdc7 may regulate processes of DNA replication by modulating MCM functions.

Amino Acid Sequence↗

PubMed1997

Frpo: a novel single-stranded DNA promoter for transcription and for primer RNA synthesis of DNA replication.

We describe a novel promoter for E. coli RNA polymerase that functions efficiently only in the form of single-stranded DNA. Derived from the leading region of F plasmid, single-stranded Frpo sequence directs RNA polymerase to initiate transcription at a specific site within Frpo, and this specific transcription is highly stimulated by SSB. Prior denaturation activates transcription from otherwise inactive duplex DNA containing Frpo. Since RNAs synthesized on SSB-coated single-stranded Frpo are efficiently elongated into DNA chains by DNA polymerase III holoenzyme, transcription at Frpo serves also for priming DNA replication. A mode of recognition by RNA polymerase of a unique secondary structure within Frpo is proposed, and possible roles of this novel single-stranded promoter in expression and replication during conjugal transfer of F plasmid are discussed.

Chromosome Mapping↗

PubMed1997

Cloning of a human homolog of the yeast OGG1 gene that is involved in the repair of oxidative DNA damage.

We report the cloning of a human homolog of the yeast OGGC1 gene, which encodes a DNA glycosylase that excises an oxidatively damaged form of guanine, 8-hydroxyguanine (also known as 7,8-dihydro-8-oxoguanine). Since the deduced amino acid sequence (68 amino acids) of a human expressed sequence tag, N55394, matched a short stretch of yeast OGG1 protein with greater than 40% amino acid identity, a full length cDNA clone was isolated from a HeLa cell cDNA library with the N55394 clone as a probe. The cDNA clone encodes a predicted protein of 345 amino acids which is homologous to yeast OGG1 protein throughout the entire polypeptide sequence and shares 38% amino acid identity with yeast OGG1 protein. Moreover, we found that both a human homolog and yeast OGG1 protein possess two distinct DNA binding motifs, a helix-hairpin-helix (HhH) motif and a C2H2 zinc finger like motif, and a domain homologous to human and E. coli MutY proteins. Expression of a human homolog suppressed spontaneous mutagenesis of an E. coli (mutM mutY) mutant as in the case of yeast OGG1 protein. The gene was ubiquitously expressed in a variety of human organs and mapped to chromosome 3p26.2. These results strongly suggest that the gene isolated here is a human counterpart of the yeast OGGI gene and is involved in the repair of oxidative DNA damage in human cells.

Amino Acid Sequence↗

PubMed1997

The inv(11)(p15q22) chromosome translocation of de novo and therapy-related myeloid malignancies results in fusion of the nucleoporin gene, NUP98, with the putative RNA helicase gene, DDX10.

The inv(11)(p15q22) is a recurrent chromosomal abnormality associated with de novo and therapy-related myeloid malignancies. Here we report the molecular definition of this chromosomal aberration in four patients. Positional cloning showed the consistent rearrangement of the DDX10 gene on chromosome 11q22, which encodes a putative RNA helicase. The translocation targets the NUP98 gene on 11p15, a member of the FG peptide repeat nucleoporin family. In DDX10 and NUP98, the inv(11) breakpoints occurred within two introns of each gene and the two genes merged in-frame to produce the chimeric transcripts characteristic of this translocation. Although two reciprocal chimeric products, NUP98-DDX10 and DDX10-NUP98, were predicted, only NUP98-DDX10 appears to be implicated in tumorigenesis. DDX10 is predicted to be involved in ribosome assembly. NUP98 has been identified as a nuclear pore complex protein and a target of chromosomal translocation in acute myeloid leukemia through the t(7;11)(p15;p15) translocation. The predicted NUP98-DDX10 fusion protein may promote leukemogenesis through aberrant nucleoplasmic transport of mRNA or alterations in ribosome assembly.

Amino Acid Sequence↗

PubMed1997

Activation of c-Jun N-terminal kinase by human granulocyte macrophage-colony stimulating factor in BA/F3 cells.

Human granulocyte-macrophage colony-stimulating factor (hGM-CSF) induces various signaling events in hematopoietic cells. We reported that there are at least two distinct pathways of hGM-CSF signals, one for activation of proliferation and the other one for activation of c-fos promoter through the MAPK cascade. Activation of other members of the MAPK family, c-Jun N-terminal kinase (JNK) and p38 MAPK under various cellular stress have also been reported. We found that hGM-CSF activates JNK in BA/F3 cells expressing the hGM-CSF receptor (hGMR) and that activation depends on a membrane proximal region including box1 and requires a more membrane distal region of hGMR beta subunit (beta c). There are 8 known tyrosine (tyr) residues in the cytoplasmic region of beta c. Mutant beta c lacking all the tyr residues hardly activates JNK, thereby indicating that the tyr residue(s) is essential for the activation of JNK. Mutation analyses of each tyr residue indicated that none of the tyr residues seems essential for the activation of JNK, indicating multiple tyr residues play a similar function to transduce signals for this activation.

Calcium-Calmodulin-Dependent Protein Kinases↗

PubMed1997

Analyses of Saccharomyces cerevisiae Cdc7 kinase point mutants: dominant-negative inhibition of DNA replication on overexpression of kinase-negative Cdc7 proteins.

Saccharomyces cerevisiae Cdc7 kinase is required for initiation of S phase, and its kinase activity, which is positively regulated by Dbf4 protein, reaches maximum at the G1/S boundary. In this study, we constructed Cdc7 point mutants (T281E, T281A, D182N, D163N, and T167E) and examined the effect of each mutant on growth. All the mutants lost the ability to complement temperature-sensitive growth of cdc7(ts) mutants at a low protein level, whereas T281A (putative target of phosphorylation) and T167E (residue involved in substrate recognition) restored the growth of cdc7(ts) when overproduced to a high level. Three putative kinase-negative mutants (T281E, D182N, and D163N) inhibited growth when overexpressed in a wild-type strain. Analyses of DNA content and morphology revealed that most cells were arrested as dumbbells with 1C DNA, indicative of a block in the G1 to S transition. This growth inhibition was suppressed by co-overexpression of the wild-type Cdc7 or Dbf4 protein. Furthermore, deletion of the Dbf4 protein-binding region in each Cdc7 mutant resulted in loss of growth inhibitory effect. Thus, dominant-negative effects of T281E, D182N, and D163N on growth can be best explained by inactivation of the wild-type Cdc7 function through titration of Dbf4 by these inactive kinases. Our results are consistent with the notion that association of Dbf4 with Cdc7 is essential for the G1 to S transition in S. cerevisiae.

Amino Acid Sequence↗

PubMed1997

Human small Maf proteins form heterodimers with CNC family transcription factors and recognize the NF-E2 motif.

The transcription factor NF-E2, a heterodimeric protein complex composed of p45 and small Maf family proteins, is considered crucial for the regulation of erythroid gene expression and platelet formation. To facilitate the characterization of NF-E2 functions in human cells, we isolated cDNAs encoding two members of the small Maf family, MafK and MafG. The human mafK and mafG genes encode proteins of 156 and 162 amino acid residues, respectively, whose deduced amino acid sequences show approximately 95% identity to their respective chicken counterparts. Expression of mafK mRNA is high in heart, skeletal muscle and placenta, whereas mafG mRNA is abundant in skeletal muscle and is moderately expressed in heart and brain. Both are expressed in all hematopoietic cell lines, including those of erythroid and megakaryocytic lineages. In electrophoretic gel mobility shift assays binding to NF-E2 sites was found to depend on formation of homodimers or heterodimers with p45 and p45-related CNC family proteins. The results suggest that the small Maf family proteins function in human cells through interaction with various basic-leucine zipper-type transcription factors.

Amino Acid Sequence↗

PubMed1997

Cytokine signal networks and a new era in biomedical research.

Elucidation of the biochemical nature of the signal transduction pathway that regulate transcription and replication is the focus of attention in molecular biology. This research may make feasible manipulation of growth and differentiation of mammalian cells, which in turn would have profound implication in biomedical research on cell and gene therapy, and development of pharmaceutical products. Cytokines control growth, differentiation, death, and function of cells of lymphocytic, hemopoietic systems, and together with nerve cells provide a pertinent model to study intercellular communications and intercellular signal networks. This review outlines general features of signal transduction and several aspects of cytokine networks are discussed with emphasis on: transcriptional regulation of Th1 and Th2-specific cytokine genes in T cells, the roles of cytokines and their receptors in growth and differentiation of hemopoietic cells, and the manipulation of cytokine networks.

Animals↗

PubMed1997

Characterization of cis-acting sequences and trans-acting signals regulating early growth response 1 and c-fos promoters through the granulocyte-macrophage colony-stimulating factor receptor in BA/F3 cells.

Human granulocyte-macrophage colony-stimulating factor (hGM-CSF) activates a set of genes such as c-fos, jun, myc, and early growth response gene 1 (egr-1). Studies on BA/F3 cells that express hGM-CSF receptor (hGMR) showed that two different signaling pathways controlled by distinct regions within the beta subunit are involved in activation of c-fos/c-jun genes and in c-myc, respectively. However, the region(s) of the beta subunit responsible for activation of the egr-1 gene and other regulatory genes has not been identified. We describe here how egr-1 promoter is activated by hGMR through two regions of the beta subunit, with these regions being required for activation of the c-fos promoter. Coexpression of dominant negative (dn) Ras (N17ras) or dn JAK2 almost completely suppressed the activation of egr-1 and c-fos promoters. Deletion analysis of egr-1 promoter showed two cis-acting regions responsible for activation by hGM-CSF or mouse interleukin-3 (mIL-3), one between nucleotide positions (nt) -56 and -116, and the other between nt -235 and -480, which contains tandem repeats of the serum response element (SRE) sites. Similar experiments with the c-fos promoter showed that cis-acting regions containing the SRE/AP-1 sites is sufficient for activation by hGM-CSF. Based on these observations, we propose that signaling pathways activating egr-1 and c-fos promoters are controlled by SRE elements, either through the same or overlapping pathways that involve JAK2 and Ras.

Animals↗

PubMed1997

Human granulocyte-macrophage colony-stimulating factor (hGM-CSF) induces inhibition of intrathymic T-cell development in hGM-CSF receptor transgenic mice.

Thymocytes show differential cytokine responses, depending on the stage of differentiation. Whether these responses are due to preferential cytokine receptor expression or due to downstream signaling mechanisms is unknown. In this study, we examined the relationship between receptor expression and T-cell proliferation or differentiation using thymocytes from transgenic mice constitutively expressing the human granulocyte-macrophage colony-stimulating factor (hGM-CSF) receptor. Transgenic CD4- CD8-, CD4+ CD8-, and CD4- CD8+ cells proliferated when cultured with hGM-CSF in vitro, whereas CD4+ CD8+ cells failed to proliferate. To examine the effect of hGM-CSF receptor signaling on T-cell development, we used fetal thymic organ cultures. The addition of exogenous hGM-CSF resulted in the failure of CD4- CD8- cells to differentiate into CD4+ CD8+ cells. To more closely identify this maturational inhibition, we reconstituted normal fetal lobes with sorted pro-T-, pre-T-, or post-pre-T-precursor cells from transgenic mice. The addition of hGM-CSF to these cultures led to a block in both pro-T- and pre-T-cell differentiation, whereas the more mature post-pre-T cells differentiated normally. We propose that hGM-CSF receptor signaling during T-cell development results in a stage-specific inhibition of thymic precursor maturation.

Animals↗