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Biomedical subjects

R Sasaki

Publications and source records attributed to R Sasaki.

At least 181 records · Page 10Linked to original sources
PubMed1993

Characterization of erythropoietin isolated from rat serum: biochemical comparison of rat and human erythropoietins.

We isolated erythropoietin (Epo) from anemic-rat serum with 1.3 x 10(6)-fold purification and 38% recovery using immunoaffinity chromatography. The isolated Epo migrated in SDS polyacrylamide gel with a molecular size of 37 kDa. Biological properties of rat Epo were compared with those of human Epo using target cells of primate and murine origins. When murine cells were used as target cells for assaying Epo, rat Epo stimulated proliferation of the cells with a 50% lower potency than did human Epo. The activity of rat Epo on human cells was only 25% of that of human Epo. Studies of Epo binding to the receptor indicated that rat and human Epos were not distinguishable in binding to murine cells; however, rat Epo bound to the receptor on human cells with an affinity much lower than that of human Epo. Rat Epo was digested with N-glycanase. Complete removal of N-linked sugars converted the native Epo to the deglycosylated form with 18 kDa. The in vitro activity of deglycosylated Epo was 2.5-fold higher than that of the native Epo.

Amino Acid Sequence↗
PubMed1993

The prognosis of idiopathic portal hypertension in Japan.

To clarify the factors relating to the prognosis of patients with idiopathic portal hypertension (IPH), we followed 171 patients with IPH until the end of 1990, who were registered in the database among those with abnormal portal circulation as of 1985 in hospitals of Japan. During the follow-up period, twenty patients died; 6 from gastro-intestinal tract bleeding, 5 from hepatic insufficiency and 9 from other causes. Cox's proportional hazard model suggested that male patients (hazard ratio 4.85, 95% confidence interval 1.82-12.94), with a disease onset at less than 40 years of age (H.R.3.94, 95% C.I. 1.31-11.57), and/or with varices (H.R.2.86, 95% C.I. 1.05-7.77) generally had poorer prognoses.

Adult↗
PubMed1993

Terminal deoxynucleotidyl transferase and glucocorticoid receptors in rat thymocytes.

Higher level of terminal deoxynucleotidyl transferase (TdT) and peanut agglutinin (PNA)-positive cells were found in those fractions of albumin gradient separated rat thymocytes that had a higher level of glucocorticoid (GC) receptors and a lower level of sialyltransferase (S-T) activity. Incubation of thymocytes in these fractions with dexamethasone inhibited RNA synthesis significantly. Incubation of these thymocytes with tetradecanoylphorbol-acetate (TPA) reduced TdT activity, while increasing S-T activity. The higher level of GC receptors may be responsible for GC sensitivity of TdT-positive thymocytes. In addition, sialyltransferase may be a biochemical marker for thymocyte differentiation.

Animals↗
PubMed1993

Production of a specific monoclonal antibody to terminal deoxynucleotidyl transferase (TdT) and the extensive studies of TdT in patients with hematological malignancies.

Terminal deoxynucleotidyl transferase (TdT) was purified from calf thymus and a monoclonal antibody-producing clone was produced by the fusion of mouse myeloma cells and spleen cells of mice immunized with the purified enzyme. The antigens recognized by an immunoadsorbent column revealed TdT, whose molecular weight was 62 kDa. The extensive study of TdT in 196 patients with hematological disorders was done. The results from immunofluorescent analysis corresponded well to the results of biochemical assays of this enzyme. This monoclonal antibody will provide a useful means for the survey of leukemia and lymphoma patients.

Animals↗
PubMed1993

12-0-Tetradecanoylphorbol 13-acetate (TPA)-induced enzymatic change of human non-T, non-B lymphoid leukemia cell lines.

Culture of two lymphoid leukemia cell lines with 5 x 10(-9) to 10(-7) M 12-0-tetradecanoyl-phorbol 13-acetate (TPA) induced the significant increase in sialyltransferase, acid phosphatase and butyrate esterase activities, the decrease in poly(A) polymerase and terminal deoxynucleotidyl transferase (TdT) activities. B4-, J5-, TdT- or PNA-positive cells were decreased in TPA-treated cells, while B1-positive cells were increased. These results suggest enzymatic changes as an aspect of TPA-induced differentiation in lymphoid leukemia cell lines. These enzymatic activities may be useful markers for the differentiation of lymphoid leukemia cells.

Cell Differentiation↗
PubMed1992

Nucleotide sequence of rat erythropoietin.

The cDNA for the rat erythropoietin (EPO) has been cloned and sequenced. The deduced amino acid sequence consists of 166 amino acid residues, which has a 79% and 95% homology with human and mouse EPOs, respectively. Many short stretches, highly conserved in primate and rodent EPOs, are found in the 3'-noncoding region when insertions and deletions are taken into consideration.

Amino Acid Sequence↗
PubMed1992

Production and ligand-binding characteristics of the soluble form of murine erythropoietin receptor.

A recombinant soluble form (sEPO-R) of erythropoietin (EPO) receptor (EPO-R) was produced by Chinese hamster ovary cells and isolated in high yield with the EPO-fixed gel. Ligand binding assays were done using three methods; precipitation of sEPO-R radiolabeled EPO complex and competition of sEPO-R for the binding of radiolabeled EPO with the cellular EPO-R. The results showed a Kd of 17 nM which was much lower than those for cellular EPO-R. One N-glycosylation site exists in sEPO-R but the glycosylation did not affect the binding affinity to EPO. A complex with a molecular size that corresponded to a 1:1 complex of EPO and sEPO-R was detected.

Animals↗
PubMed1992

Developmental changes in erythropoietin receptor expression of fetal mouse liver.

Erythropoietin (EPO) stimulates proliferation and differentiation of late erythroid precursor cells (CFU-E) and thereby determines the rate of erythropoiesis. Liver is the major erythropoietic site in a fetus. We dealt with developmental changes in CFU-E and EPO receptor (EPO-R) of fetal mouse liver. The affinity of the EPO-R to EPO was unchanged during fetal development. The population size of CFU-E, the number of EPO-R per liver cell, and EPO-R mRNA decreased as gestation proceeded, in a pattern indicating that the expression of EPO-R on erythroid precursor cells in fetal mouse liver is governed mostly by the process of mRNA production.

Animals↗
PubMed1992

Protein deficiency impairs erythropoiesis in rats by reducing serum erythropoietin concentration and the population size of erythroid precursor cells.

Erythropoietin (EPO), a glycoprotein produced mainly by the kidney, is the major physiological regulator of erythropoiesis. We developed a sensitive and rapid ELISA for measurement of rat serum EPO with two monoclonal antibodies that recognize different epitopes. To understand the mechanism by which erythropoiesis is impaired in rats deficient in dietary protein, we investigated the levels of the immunoreactive EPO (iEPO) in serums and erythroid precursor cells in hemopoietic tissues during protein deprivation. The iEPO level of 32-d-old rats fed a protein-free diet was lowered to one-third that of rats fed 20% casein at 6 h after protein deprivation began. Protein deprivation decreased the number of EPO-responsive cells in spleen. These results indicate that the impairment of erythropoiesis during protein deficiency is caused by the decrease in serum EPO and the subsequent reduction of the population size of erythroid precursor cells in spleen.

Animals↗
PubMed1992

Juvenile dermatomyositis: a statistical study of 114 patients with dermatomyositis.

We conducted a statistical review of 114 cases of dermatomyositis (DMS) treated primarily at the Department of Dermatology at Nagoya University Hospital over 27 years from 1965 to 1991 in order to determine the primary characteristics of juvenile DMS with the following results. 1) Juvenile DMS was found slightly more often in males than females; the male-to-female ratio was 1.4:1. Therefore, unlike adult DMS with its preponderance of females, there was no clear gender predominance. 2) Muscular manifestations tended to follow the appearance of cutaneous manifestations, but the frequency of minor muscular manifestations was high over the entire course of the disease. 3) Laboratory findings showed increases in serum aldolase and serum creatinine kinase with significant frequency when compared with adult patients (p < 0.01 and p < 0.05, respectively). Elevated serum aldolase most often occurred prior to or at the time of the appearance of muscular manifestations, suggesting its usefulness in early diagnosis. The positive rates for the antinuclear antibody on HEp-2 cells and anti-DNA antibody were significantly lower in children than in adults (p < 0.001 and p < 0.05, respectively). 4) There were no cases of juvenile DMS complicated by malignant tumors, interstitial pneumonia, or pulmonary fibrosis. There were also no deaths, and the rate of "remission or improvement" was significantly higher than in adult DMS cases (p < 0.05). Adult cases which remained the same or worsened usually presented with intractable muscular manifestations. In children, however, the cutaneous manifestations were more difficult to treat.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Effect of omeprazole on ascorbate free radical formation.

In order to study the effect of omeprazole on the K/[H+] value of ascorbic acid (K = the ascorbic acid-ascorbic free radical equilibrium constant), changes of the concentration of ascorbate free radical in guinea pig sera were examined after intraperitoneal administration of omeprazole. Furthermore, to see the in vitro effect of omeprazole on ascorbate free radical, changes were examined in ascorbate solutions after addition of omeprazole. It was found that the K/[H+] value in the serum increased significantly after administration of omeprazole and also that the drug amplified the electron spin resonance (ESR) signal intensity of ascorbate free radical in vitro. These results suggested that omeprazole acts like oxygen radicals.

Animals↗
PubMed1992

[Acute undifferentiated leukemia from the viewpoints of diagnosis and therapy].

Myeloperoxidase (MPO)- and Sudan Black B-not more than 3%-positive, esterase staining-negative, lymphoid, megakaryocyte lineage and erythroid surface marker-negative and electron microscopic platelet peroxidase-negative acute leukemia (AL) was diagnosed as acute undifferentiated leukemia (AUL), and myeloid marker (CD13, CD33), electron microscopic MPO (EMMPO), and DNA analysis of immunoglobulin heavy chain and T cell receptor as well as chemotherapy and its reactivity were examined. Of 239 cases of AL, 10 (4.2%) were AUL, and of these 10 cases, 9 were CD13 or CD33-positive AML-MO (MO) cases. Of 9 cases examined for EMMPO, 4 (44%) were positive, and of 3 cases of MO subjected to DNA analysis, 1 and 1 showed rearrangements of immunoglobulin heavy chain and T cell receptor beta chain, respectively. Of 6 cases of MO on myeloid induction therapy, 1 and 1 showed complete remission (CR) and partial remission (PR), respectively, each having lymphoid genotype, and 4 showed no remission (NR), being 3 of them EMMPO-positive. Of 2 cases on lymphoid induction therapy, 1 and 1 showed CR and NR, respectively, the former being EMMPO-positive MO. BHAC-EM therapy with behenoyl cytosine arabinoside, VP-16 and mitoxantrone performed on 2 cases refractory to any one of both these myeloid and lymphoid induction therapies led to CR in all these 2 cases.

Adolescent↗
PubMed1992

[A multivariate analysis of prognostic factors of spinocerebellar degenerations].

To clarify the factors relating to the prognosis of spinocerebellar degenerations (SCD), we performed a follow-up study on the survival of patients with Friedreich disease, familial spastic paraparasis, sporadic olivopontocerebellar atrophy (OPCA), hereditary OPCA of Menzel type, sporadic late cortical cerebellar atrophy (LCCA), cerebellar atrophy of Holmes type, Shy-Drager syndrome, striatonigral degeneration, dentatorubropallidoluysian atrophy, or Joseph disease. One hundred and forty-eight patients admitted to the Nagoya University Hospital during the period of 1976 to 1990 were dealt with. They had been followed-up for 15 years at longest through the medical records, or through the direct informations from the patients or their family members or both. In order to find factors influencing the survival of the patients, Kaplan-Meier method was used as the 1st step to construct the survival curve for each factor. These were calculated by generalized Wilcoxon test. Employing Cox's proportional hazard model, a multivariate analysis was then performed based on the factors which were shown significant in the 1st step. The multivariate analysis showed that the following four factors are related to the prognosis of SCD patients, i.e., lack of hereditary trait, existence of orthostatic hypotension, lack of walking disorder at onset, and lack of nystagmus on admission. Of these factors, the lack of hereditary trait had the most intimate relation to their poor prognosis. Therefore, these four factors are statistically informative to predict prognosis of each patient with SCD.

Adolescent↗
PubMed1991

Effects of site-directed removal of N-glycosylation sites in human erythropoietin on its production and biological properties.

Erythropoietin (Epo) has three N-linked sugar chains. Codons for asparagine at N-glycosylation sites in genomic human Epo DNA were replaced with those for glutamine. The wild-type Epo gene and seven mutants that lacked N-glycosylation sites in every possible combination were introduced into baby hamster-kidney cells. To study the role of the N-linked sugars in Epo biosynthesis, Epo protein expressed transiently was measured by an enzyme-linked immunoassay. The elimination of all three N-glycosylation sites decreased Epo production to 10% of that of the wild-type Epo. Wild-type and mutant Epos produced by stably transfected cells were partially purified to investigate their properties. Removal of N-glycosylation sites changed affinity of Epo to the receptor. The in vitro activity of Epo that lost all N-glycosylation sites was comparable with that of the wild-type Epo, while the in vivo activity severely decreased. These results indicate that N-linked sugars of Epo have two major functions; N-linked sugars are important for 1) proper biosynthesis and/or secretion and 2) expression of the in vivo activity probably by enhancing survival in the circulation. N-Linked sugars of Epo affect binding affinity of the ligand to the receptor but do not play a key role in expression of the in vitro activity.

Base Sequence↗
PubMed1991

Erythroid differentiation of K-562 cells induced by ethidium bromide.

The exposure of K-562 cells to ethidium bromide or acridine orange as DNA-intercalating agents induced their differentiation to hemoglobin-producing cells. The addition of L-ethionine or dimethylsulfoxide induced neither such differentiation nor changes in poly(A) polymerase activity of K-562 cells, though the addition of ethidium bromide, acridine orange, hydroxyurea, or 1-beta-arabinofuranosylcytosine induced erythroid differentiation and decreases in poly(A) polymerase activity. These results suggest that DNA-intercalation is one of the pathways triggering differentiation of K-562 cells and the decrease in poly(A) polymerase activity may be an important change associated with differentiation of K-562 cells.

Acridine Orange↗