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Biomedical subjects

S Miwa

Publications and source records attributed to S Miwa.

At least 289 records · Page 16Linked to original sources
PubMed1985

Isozymes of human erythrocyte pyrimidine 5'-nucleotidase--chromatographic separation and their properties.

The biochemical properties of two isozymes of human erythrocyte pyrimidine 5'-nucleotidase (P5N) separated by ion-exchange chromatography were studied. These two isozymes, P5N-I and P5N-IIB, can be distinguished from each other by substrate specificity, pH dependent activity and thermostability. P5N-I is thermolabile and dephosphorylates various pyrimidine 5'-monophosphates optimally around pH 7. UMP and CMP were found to be most effective substrates. P5N-IIB is thermostable and characterized by its high Michaelis constant and maximum velocity for dUMP or dTMP and acidic pH optima. The molecular weight was estimated to be 39,000 for P5N-I and 44,000 for P5N-IIB by gel filtration. These data suggest that these two isozymes are independent proteins and probably encoded by distinct structural gene loci.

5'-Nucleotidase↗
PubMed1984

Change of pyruvate kinase (PK) isozymes in classical type PK deficiency and other PK deficiency cases during red cell maturation.

Conversion of pyruvate kinase (PK) isozymes during the maturation of erythroblasts in five cases of PK deficiency was compared with that in normal subjects using immunofluorescent antibody techniques. In normal erythroblasts, M2-type PK was clearly seen at the proerythroblast stage, then markedly declined with cell maturation whereas L-type PK continued to increase. In two patients with classical type PK deficiency, M2-type PK was still clearly seen in orthochromatic erythroblast, whereas L-type PK was hardly detected during maturation. In three patients with other types of PK deficiency, change of L-type PK was similar to that of normal subjects whereas M2-type PK was clearly seen even at the later stage of maturation as in classical-type PK deficiency. The present studies indicate that compensatory M2-type PK production occurs in the erythroblasts of patients with PK deficiency.

Adolescent↗
PubMed1984

Gd(-) Gifu and Gd(-) Fukuoka. Two new variants of glucose-6-phosphate dehydrogenase found in Japan.

Two new glucose-6-phosphate dehydrogenase (G6PD) variants were discovered in Japan. The first, found in a 9-year-old male, was associated with chronic hemolysis and hemolytic crises after upper respiratory infections. The enzyme activity of the variant was 2.9% of normal. The patient's G6PD showed an increased utilization of substrate analogue, deamino-NADP, and thermal instability. The second variant occurred in a 7-year-old male with drug-induced hemolysis. The main enzymatic characteristics were reduced enzyme activity, being 6.4% of normal, faster-than-normal anodal electrophoretic mobility, slightly high Michaelis constant for glucose-6-phosphate, thermal instability, and biphasic pH optima. Enzymatic properties of these variants allowed each to be distinguished from previously reported variants. The first variant was designated Gd(-)Gifu and the other, Gd(-)Fukuoka.

Child↗
PubMed1984

A unique electrophoretic slow-moving glucose 6-phosphate dehydrogenase variant (G6PD Asahikawa) with a markedly acidic pH optimum.

A new glucose 6-phosphate dehydrogenase (G6PD) variant associated with chronic nonspherocytic hemolytic anemia was discovered in Japan. The patient showed hemolytic crises after upper respiratory infections. The enzyme activity was about 3.8% of the normal. The partially purified enzyme revealed slow anodal electrophoretic mobility, high Km NADP, marked thermal-instability, and increased affinity for a substrate analogue (deamino-NADP). A particular characteristic of this enzyme was a biphasic pH curve with a greatly increased activity at low pH values. From these results, this variant was clearly different from hitherto observed G6PD variants, and was designated G6PD Asahikawa.

Anemia, Hemolytic↗
PubMed1984

Alteration of polypeptide synthesis and composition during differentiation of human leukemia cell line HL60.

Using two-dimensional gel electrophoresis, we have analyzed the polypeptide alteration of the human myeloid leukemia cell line HL60 during differentiation induced by dimethylsulfoxide (DMSO) and 12-0-tetradecanoylphorbol-13-acetate (TPA). Three polypeptides increased in synthesis after DMSO treatment, while 5 polypeptides increased after TPA treatment. Most other polypeptides were synthesized at a reduced rate though their net amounts remained unchanged, indicating that myeloid differentiation was associated not only with an increased synthesis of a few specific polypeptides but also with overall depression of most other polypeptides. One of the early differentiation marker proteins (mol. wt. approx. 20,000, pI approx. 6.0) of granulopoietic cells was increased specifically after DMSO treatment, while one of the monocyte specific marker proteins (mol. wt approx. 46,000, pI approx. 4.8) was detected after TPA treatment. But, the pattern of HL60 cells did not necessarily become similar to that of normal mature granulocytes after DMSO treatment, indicating that HL60 cell differentiation might be partial or incomplete.

Cell Differentiation↗
PubMed1984

Defective terminal maturation along monocyte-macrophage lineage in chronic myelomonocytic leukemia.

The maturation process of leukemic myelomonocytoid cells derived from peripheral blood of two typical cases of chronic myelomonocytic leukemia was investigated in vitro. In both cases, liquid culture of the leukemic cells in the presence or absence of 12-o-tetradecanoyl phorbol-13-acetate yielded either monocyte-macrophages or mature granulocytes, respectively, when examined by May-Giemsa staining. However, using cytochemical criteria, both of these mature cell fractions were found to be heterogenous and still contained substantial numbers of cells positive for both nonspecific and chloroacetate esterases. Phagocytic activity was markedly defective in the monocyte-macrophages recovered from culture as well as in freshly-isolated peripheral monocytes in both patients. In addition, active oxygen production from isolated monocytes stimulated by zymosan was also decreased in one of the cases. The results indicate that at least in some cases of chronic myelomonocytic leukemia, leukemic cells have the potential to differentiate in vitro to monocyte-macrophages which, however, show only limited development of functions, as well as freshly-isolated monocytes from peripheral blood.

Aged↗