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Biomedical subjects

S Miwa

Publications and source records attributed to S Miwa.

At least 361 records · Page 20Linked to original sources
PubMed1980

Electrophoretic and kinetic studies of human erythrocytes deficient in pyrimidine 5'-nucleotidase.

A new variant of hereditary hemolytic anemia due to erythrocyte pyrimidine 5'-nucleotidase deficiency was found in Japan. Biochemical parameters such as the Michaelis constant, thermostability, electrophoresis and pH curve were studied. The variant showed a high Michaelis constant for cytidine 5'-monophosphate, no thermolability, slower electrophoretic mobility and abnormal optimum pH. The results strongly suggest that the mechanism of this enzyme deficiency is due to a structural gene mutation.

5'-Nucleotidase↗
PubMed1980

A pedigree of amyotrophic chorea with acanthocytosis.

Several pedigrees of which some members showed a clinical syndrome consisting of mental changes, choreatic involuntary movements, limb muscles atrophy, and acanthocytosis have been reported in the United States and the United Kingdom. Such a case and some of the family members who had such abnormalities as acanthocytosis, hypo-beta-lipoproteinemia, convulsions, and confusion was observed. Results of biochemical analysis of catecholamines and their metabolites in CSF and urine showed an elevated value of norepinephrine in CSF and increased urinary secretion of DOPAC. The authors propose to designate this syndrome an amyotrophic chorea with acanthocytosis.

Athetosis↗
PubMed1980

Ionization of the catalytic groups and tyrosyl residues in human lysozyme.

The pH difference absorption spectra of human lysozyme [EC 3.2.1.17] were measured. The difference spectra in the acidic region had a peak at 300 nm, as observed for hen and turkey lysozymes. The pH dependence curve of the extinction difference at 300 nm was well interpreted in terms of the pK values of the catalytic groups (3.4 for Asp 52 and 6.8 for Glu 35 at 0.1 ionic strength and 25 degrees C) determined from the pH dependence of the circular dichroism at 303.5 nm (Kuramitsu et al. (1974) J. Biochem. 76, 671--683) and the fluorescence excited at 305 nm (Kuramitsu et al. (1978) J. Biochem. 83, 159--170). The difference spectra of human lysozyme in the alkaline pH region were characteristic of tyrosyl ionization. The perturbation of tryptophyl residues, which had been observed for hen and turkey lysozymes (Kuramitsu & Hamaguchi (1979) J. Biochem. 85, 443--456), was not observed for human lysozyme. On the basis of the pH dependence curves of the extinction difference at 245 and and 295 nm, we roughly estimated the apparent pK values of the six tyrosyl residues as 9.2 9.2, 10.5, 10.9, 12.4, and 12.5. A time-dependent spectral change observed above pH 11 was not due to the exposure of buried tyrosyl residues on alkali denaturation but was due mainly to disulfide cleavage and exposure of buried tryptophyl residues.

Catalysis↗
PubMed1980

Seven pyruvate kinase variants characterized by the ICSH recommended methods.

Seven new red-cell pyruvate kinase (PK) variants were characterized by the methods recently recommended by the International Committee for Stanardization in Haematology. The cases were all true homozygote as evidenced by consanguineous marriages of the parents; all are Japanese. These variants were designated as PK Tokyo, PK Nagasaki, PK Sapporo, PK Maebashi, PK Itabashi, PK Fukushima and PK Aizu, respectively. Low substrate affinity (high K0.5S for phosphoenolpyruvate) and thermal instability appear to play major roles in causing defective enzyme function, resulting in chronic haemolytic anaemia. Product inhibition of PK by ATP may also play an additional role in causing haemolysis in more than half the cases.

Adolescent↗
PubMed1980

Results of treatment for craniopharyngioma.

A review of the results of treatment for 155 cases of craniopharyngioma during the past 47 years by the palliative operation was made. Steroid and operative microscope reduced operative mortality and gave more chance of total extirpation, but survival rate was almost unchanged. It is noteworthy that 3 cases who underwent palliative operation more than 30 years ago are still alive and leading useful lives. The quality of survival was somewhat less favorable in pediatric than adult cases. Morbidity frequently encountered in pediatric cases was growth retardaton. Craniopharyngioma is a benign tumor pathohistologically, but it should be considered as malignant because of the region it occurs in. Therefore, no forceful attempt to total extirpation should be made and the operations should, as a rule, be palliative.

Adolescent↗