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Biomedical subjects

H Oya

Publications and source records attributed to H Oya.

At least 91 records · Page 5Linked to original sources
PubMed1982

The course of Angiostrongylus cantonensis infection in athymic nude and neonatally thymectomized mice.

BALB/c athymic nude and thymus-reconstituted nude mice and neonatally thymectomized BALB/c mice were infected with stage 3 larvae of Angiostrongylus cantonensis and the worm burdens of the mice were determined at various times after infection. When the nude and thymectomized mice were exposed to the parasite, some worms were found to migrate from the brain to lungs but died there without reaching maturity. This pulmonary arterial migration of the worms in the nude did not occur following thymic reconstitution. These data suggest that the inability of murine intracranial worms to migrate to the lungs is at least in part due to thymus-dependent mechanisms, and also that the failure of worm maturation in mouse lungs might be due to thymus-independent immune mechanisms and/or nonimmunological mechanisms.

Angiostrongylus↗
PubMed1980

Control of pyrimidine biosynthesis in the Ascaris ovary: regulatory properties of glutamine-dependent carbamoyl-phosphate synthetase and copurification of the enzyme with aspartate carbamoyltransferase and dihydroorotase.

Glutamine-dependent carbamoyl-phosphate synthetase, the first enzyme of the de novo biosynthetic pathway for pyrimidine nucleotides, was purified about twenty-fold from 105 000 x g supernatant of the Ascaris ovary homogenate. The enzyme activity was feedback-inhibited by UDP and UTP while it was stimulated by 5-phosphoribosyl 1-pyrophosphate. Most of the catalytic and regulatory properties of the Ascaris synthetase were similar to those of the mammalian synthetase. A significant difference is that the Ascaris enzyme was more strongly inhibited by UDP than by UTP whereas the mammalian enzyme is more sensitive to UTP than to UDP. The Ascaris enzyme was also inhibited by other various nucleoside diphosphates, such as dUDP, dADP and CDP, generally more strongly than by the corresponding nucleoside triphosphates. Aspartate carbamoyltransferase and dihydroorotase, the second and third enzymes of the pathway, were also demonstrated in the supernatant fraction. These two enzymes were copurified with the synthetase and the relative activities of the three enzymes remained nearly constant (1:850-890:50-60) throughout the purification. In a sucrose gradient centrifugation, the enzymes cosedimented as a single peak with a sedimentation coefficient (s20,w) of about 32 S under the condition used. These results strongly suggest that the enzymes exist as a multienzyme complex similar to those found in higher animals. The activity of the carbamoyltransferase was insensitive to nucleotides and related compounds. These results indicate that the synthetase plays a key role in the control of pyrimidine biosynthesis in the Ascaris ovary.

Amidohydrolases↗
PubMed1979

Glutamine-dependent carbamoyl-phosphate synthetase and control of pyrimidine biosynthesis in the parasitic helminth Schistosoma mansoni.

1. Carbomoyl-phosphate synthetase in Schistosoma mansoni utilizes L-glutamine as well as ammonia as nitrogen donor but does not require N-acetyl-L-glutamate for the activity. 2. The enzyme activity was inhibited by UDP, UTP, ADP and AMP, among which UDP was the most effective. 3. Aspartate carbamoyltransferase and dihydroorotase were also found and copurified with the synthetase. 4. Relative activities among these three enzymes were 1:30-60:3-8 throughout the purification. 5. These results suggest that the synthetase plays a key role in the control of pyrimidine biosynthesis de novo.

Animals↗
PubMed1976

X-Prolyl dipeptidyl-aminopeptidase activity, with X-proline p-nitroanilides as substrates, in normal and pathological human sera.

X-Prolyl dipeptidyl-aminopeptidase (no EC no. assigned) activity in normal and pathological human sera was assayed with several newly synthesized X-proline p-nitroanilides as chromogenic substrates. Normal values for 88 healthy subjects (15 to 81 years old), with glycylproline p-nitroanilide as substrate at pH 8.7, were 54.9 +/- 1.5 (SE) (range, 25.7 - 96.0) mumol/min per liter of serum at 37 degrees C. The results suggest that the enzyme activities with all X-proline p-nitroanilides were increased in patients with hepatitis and decreased in patients with gastric cancer. On Sephadex G-200 column chromatography, normal human sera showed a single peak of enzyme activity with glycylproline p-nitroanilide as the substrate, which coincided with the peak with glycylproline beta-naphthylamide but was different from the peaks with leucine beta-naphthylamide. Sera from patients with hepatitis or liver cirrhosis showed an increase in the normal peak and the appearance of another new peak with glycylproline p-nitroanilide as substrate.

Adolescent↗
PubMed1975

Subacute sclerosing panencephalitis (SSPE): isolation of a defective variant of measles virus from brain obtained at autopsy.

A cytopathic agent causing formation of syncytial giant cells was isolated by co-cultivation of human embryonic lung cells with brain cells obtained at autopsy from a patient with subacute sclerosing panencephalitis. Measles specific intracellular immunofluorescence was detected in syncytial giant cells developed by the agent. Paramyxovirus-like nucleocapsids were observed by electron microscopy in nuclei of the syncytial giant cells. Measles specific immunofluorescence was also detected on the surface of unfixed syncytial giant cells. However, the synycytial giant cells did not produce either virions or hemogglutinin, and did not show hemadsorption of African green monkey red cells. Hence, the newly isolated agent seems to be a defective variant of measles virus, and was designated as the SSPE-"BIKEN" strain.

Brain↗
PubMed1972

[Glycoproteins].

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Electrophoresis↗