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Biomedical subjects

Y Ishida

Publications and source records attributed to Y Ishida.

At least 703 records · Page 39Linked to original sources
PubMed1981

Red-cell enzyme activities and properties of mutant pyruvate kinase after 1-year storage in a -80 degrees C freezer.

Red cells from 5 healthy adults and an unstable mutant pyruvate kinase (PK), PK Maebashi, were stored for 12 months in a -80 degrees C freezer. With an exception of triosephosphate isomerase and phosphoglycerate kinase activities, normal red-cell enzyme activities remained essentially unchanged. Mutant PK was characterized by the methods recommended by the International Committee for Standardization in Haematology (ICSH). Normal control and PK Maebashi remained essentially unchanged in their characteristics after storage in a -80 degrees C freezer for 12 months. These results indicate that the red cells stored over a long term in a -80 degrees C freezer can be used for the study of unstable mutant PK.

Blood Preservation↗
PubMed1981

A comparative study of the relaxing effect of nitroprusside and verapamil on human umbilical vessels.

Relaxing effects of nitroprusside and verapamil on the resting or K-stimulated tension and 45Ca uptake in human umbilical vessels were investigated. Both nitroprusside and verapamil reduced the resting and K-stimulated tensions in a dose-dependent manner. Nitroprusside was much more effective than verapamil in reducing resting tension. However, verapamil caused a greater relaxation of the K-induced contraction than nitroprusside. In a Ca2+-free medium, K+ still caused a small and sustained contraction. Nitroprusside abolished the contraction in the Ca2+-free medium, which verapamil failed to inhibit. Neither nitroprusside nor verapamil affected the resting 45Ca uptake measured by a lanthanum method. The K-induced increase in 45Ca uptake was inhibited by verapamil, but not by nitroprusside. The results suggest that nitroprusside unlike verapamil does not act as a Ca2+ influx inhibitor resulting in the relaxation of human umbilical vessels.

Calcium↗
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

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

Intracytoplasmic inclusions (Bunina bodies) in amyotrophic lateral sclerosis.

In an autopsy case of sporadic amyotrophic lateral sclerosis, there were intracytoplasmic eosinophilic inclusions of the Bunina type in motor neurons. Electron microscopically, these bodies were observed as amorphous substances, irregularly deposited around the endoplasmic reticulum to form masses. Similar small masses were also visible in mitochondria. These substances did not stain for acid phosphatase. By analytical electron microscopy they contained silicon. Bunina bodies, therefore, seem to be due to deposition of some metabolite, but their nature is still obscure.

Aged↗
PubMed1980

Disseminated necrotizing leukoencephalopathy.

A 30-year-old male with chronic myelogenous leukemia was treated by intrathecal instillation of methotrexate and cytosine arabinoside because of meningeal infiltration of leukemic cells. He developed neurlogical signs of bilateral cerebral dysfunction with progressive deterioration and died. The neuropathological changes consisted of multiple small areas of demyelination and coagulative necrosis that were randomly disseminated in the cerebral white matter. There was a remarkable decrease of glial nuclei and occasional deposits of mineral salts. Numerous axonal swellings were observed within and around the necrotizing foci. A moderate astrocytosis and mild status spongiosus were found in the surrounding white matter. The etiological relationship of these changes to intrathecal methotrexate is discussed.

Adult↗
PubMed1980

Potentiation by dilazep on the negative inotropic effect of adenosine on guinea-pig atria.

1 Dilazep, a coronary dilator, has been reported to potentiate the negative inotropic and negative chronotropic responses of guinea-pig atria to adenosine. Studies were made on the mechanism of the potentiating action of dilazep with special reference to the degradation and uptake of adenosine. 2 The negative inotropic actions of adenosine and adenine nucleotides, such as ATP, ADP, AMP and cyclic AMP, on guinea-pig atria were selectively and dose-dependently augmented by dilazep at concentrations insufficient to produce any effect alone (0.01 to 1 microM). 3 Incubation of atrial tissue with 8.8 nM adenosine, containing 0.1 microCi of [3H]-adenosine, resulted in accumulation of [3H]-adenosine in the tissue; dilazep (0.01 to 1 microM) inhibited this accumulation. 4 Adenosine (10 microM to 10 mM) was degraded to inosine and hypoxanthine during incubation with atrial tissue; dilazep (0.1 to 10 microM) retarded the disappearance of adenosine and the formation of inosine and hypoxanthine. 5 These results suggest that dilazep potentiates the negative inotropic effect of adenosine on guinea-pig atria by preventing both its accumulation by atrial tissue and degradation by deaminase.

Adenosine↗
PubMed1980

Vasorelaxant action of caroverine fumarate (a quinoxaline derivative), a calcium-blocking agent.

1 Caroverine fumarate, 1-(2-diethylaminoethyl)-3-(p-methoxy-benzyl)-1,2-dihydro-2-quinoxalinone fumarate, caused a greater inhibition of the pressor response to KCl (8 x 10(-2) M) than that to noradrenaline (10(-6) M) in the rat hindquarter preparation. 2 In the isolated aorta of the rat, caroverine (up to 10(-6) M) markedly suppressed the contraction caused by KCl (4 x 10(-2) M) (high-K) but had little effect on the contractile response to noradrenaline (10(-6) M) whether added before the spasmogen or in its presence. 3 In the high-K-treated aorta, caroverine shifted the concentration-response curve for external calcium to the right, competitively. The negative logarithm of the affinity (pA2) of caroverine was calculated to be approx. 7. 4 Increased 45Ca uptake of the high-K-treated aorta measured by a modified lanthanum method was inhibited by either caroverine (3 x 10(-6) M) or verapamil (10(-6) M). 5 Concentrations of caroverine and verapamil reducing high-K-induced aortic contraction to 50% of its maximum were 2.4 x 10(-7) and 6.6 x 10(-8) M respectively. 6 Following washout the caroverine-induced inhibition of high-K-induced aortic contraction was more rapidly restored than the verapamil-induced inhibition. 7 These results suggest that caroverine fumarate is a specific and readily reversible calcium influx inhibitor in the rat vascular smooth muscle.

Animals↗