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Biomedical subjects

T Aoki

Publications and source records attributed to T Aoki.

At least 1,135 records · Page 63Linked to original sources
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↗
PubMed1980

Concanavalin A inhibits the development of experimental allergic encephalomyelitis in guinea pigs.

The effect of concanavalin A (Con A) on experimental allergic encephalomyelitis (EAE) was assessed in guinea pigs with a various time, dose and route schedule. EAE was significantly suppressed when 5 mg of Con A was injected in the sensitizing injection sites within 3 days before or after sensitization with bovine spinal cord in complete Freund's adjuvant. The EAE-suppressive activity of Con A was shown by significant reductions in incidence and severity of EAE, a delayed onset of EAE and low mortality. The proliferative response of draining lymph node cells (LNC) to myelin basic protein (BP), the growth of the draining lymph nodes (LN) and the proliferation of active rosette-forming T cells in the draining LN were all significantly suppressed in Con A-treated animals than those of unsuppressed animals. The depressed LNC reactivity to BP in Con A-treated animals was not increased when nylon wool adherent cells were removed, whereas there was a significant increase in unsuppressed animals. These results suggest that Con A suppressed EAE by inhibiting the proliferation of BP-sensitized T cells in the draining LN and that the interaction between T cell subsets could exert an inhibitory effect on EAE.

Animals↗
PubMed1980

The effects of mucolytic agents and stirring on sputum viscoelasticity.

Changes in the behavior of sputum viscoelasticity due to differences in macroscopic appearance of sputum brought about by stirring and those due to the addition of an expectorant to purulent sputum in vitro, were studied in a coaxial cylinder rheometer. First, initial results from stirring the sputum indicated the following: Samples of untreated sputum showed no obvious differences among the three macroscopic groups, mucoid, mucopurulent and purulent, on the basis of dynamic viscoelasticity. However, when they were stirred sufficiently, dynamic viscosity and storage modulus increased in mucoid sputum and decreased in purulent sputum. Second, the addition of expectorants revealed the following results: (i) When distilled water was used as a control substance added to sputum, the addition of 0.5% semialkaline proteinase to sputum decreased the dynamic viscosity and storage modulus of the sputum to a large extent. (ii) The addition of 0.2% Bromhexine exerted a small influence upon the dynamic viscosity and slightly increased the storage modulus. (iiii) The addition of 20% N-acetyl-L-cysteine increased the dynamic viscosity slightly, but decreased the storage modulus to a large extent. In brief, each expectorant exerted a unique influence on the viscoelasticity of sputum. These results were discussed with regard to their clinical significance.

Elasticity↗
PubMed1980

A new cytoplasmic bar-like structure seen in type II alveolar cells of rat lungs.

Type II alveolar cells from healthy (control) and from pilocarpine-treated rats were studied using transmission electron microscopy of ultra-thin sections and freeze fracture replicas. In freeze-fracture preparations, a bar-like laminated structure about 0.4 micrometer in diameter and 1 similar to or approximately 6 micrometer in length was found in type II alveolar cells; it seemed to be identical to the membrane-bound slits containing electron dense materials which were also observed in ultra-thin sections. The frequency of this structure in the cells increased together with an increase in the number of lamellar bodies after injection of pilocarpine, suggesting a close connection between the bar-like structure and the formation of pulmonary surfactant.

Animals↗
PubMed1980

Serum ferritin concentration and isoferrtin patterns detected by immunoradiometric assay.

Two-site immunoradiometric assay for serum ferritin was developed by anti-human liver ferritin antiserum applied on polyvinyl V-bottom microtiter plates. The coefficient of variation was 4.4-5.9% of liver ferritin dissolved in 1/4 diluted human serum at a concentration of 0.625-125 ng/ml. The lowest concentration (0.625 ng/ml) was statistically distinguishable from the background by Student's t test (p < 0.05). Isoferritin patterns of serum ferritin and tissue ferritins were examined by the combination of gel isoelectric focussing and 2-site immunoradiometric assay in order to explore any similarities in pIs within these ferritins. Although serum ferritin had wide range of pIs, its basic isomers corresponded well to those of liver and spleen ferritin. Geometric means and their 95% confidence limits in serum ferritin concentration were 70 ng/ml and 12-411 ng/ml, respectively, in sera of 205 healthy males (16-25 years), and 12 ng/ml and 1-211 ng/ml, respectively, in 421 healthy females (16-59 years).

Adolescent↗