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Biomedical subjects

K Asaoka

Publications and source records attributed to K Asaoka.

At least 91 records · Page 5Linked to original sources
PubMed1991

Enzymes that metabolize acyl-coenzyme A in the monkey--their distribution, properties and roles in an alternative pathway for the excretion of nitrogen.

1. In various tissues from the monkey (Macaca fuscata), acyl-coenzyme A (CoA) hydrolase activities were found to be widely distributed within a 2-10 times range and present in liver cytosol having mol. wt of ca 60,000. 2. Acyl-CoA: amino acid N-acyltransferase activity were 4-250 times higher in liver and kidney than in other tissues, even no activity in heart, lung, and plasma. 3. The transferases abounded in liver mitochondria, being distributed evenly between the intracristate space, the inner membrane, and the matrix. 4. The partially purified transferases with benzoyl-CoA or phenylacetyl-CoA as substrates were shown to have mol. wt of ca 30,000 and reacted only with glycine or L-glutamine, respectively. 5. No amino acid tested had any effects on the enzyme as either inhibitors or activators. 6. These results suggest that the enzymes that metabolize acyl-CoA constitute an alternative pathway for the excretion of nitrogen.

Acyl Coenzyme A↗
PubMed1991

Visco-elastic deformation of dental porcelain and porcelain-metal compatibility.

A computer simulation using a visco-elastic stress analysis was conducted to clarify the effect of the heating rate on deformation temperature of dental porcelain during firing. In this simulation, the following temperature-dependent factors were incorporated: elastic modulus, viscosity, and coefficient of thermal expansion. The cooling/heating rate dependencies of both the glass-transition temperature and the temperature distribution in the slab were also included. Thermal expansion curves of porcelain with an applied load at various heating rates were computed. Effects of the applied stress and the heating rate on the deformation temperature of porcelain were revealed. The results suggest that the temperature where the incompatibility stress develops in the porcelain-fused-to-metal strips during cooling can be estimated closely from the deformation point of the heating curve of the porcelain with an applied stress of about 1.2 approximately 3.1 MPa. A method for measuring temperature dependence of viscosity as represented by an Arrhenius equation is proposed.

Computer Simulation↗
PubMed1991

Ankyloglossia with deviation of the epiglottis and larynx.

We observed ankyloglossia to be usually accompanied by displacement of the epiglottis and larynx. Infants with this disease developed dyspnea and skin and hair abnormalities. In addition, they had other symptoms, such as a dark forehead, a frowning expression, a dark color around the lips, scanty eyebrows, swelling around the palpebrae, harsh respiratory sounds, hard crying, snoring, and frequent yawning. In spite of these abnormalities, they had been considered to be healthy by their pediatricians. Arterial oxygen percent saturation (SaO2) was measured while the infants were asleep, suckling, and awake. The results revealed that their SaO2 was unstable and slightly low. The symptoms and signs of this disease were very similar to those observed in victims of sudden infant death syndrome before their death. Correction of the ankyloglossia and deviation of the epiglottis and larynx resulted in great improvement of these signs as well as a stabilization and increase of SaO2.

Cyanosis↗
PubMed1990

The complete amino acid sequence of bullfrog (Rana catesbeiana) parvalbumin pI4.97.

The primary structure of the parvalbumin (pI4.97) from bullfrog, Rana catesbeiana, skeletal muscle has been determined. It is composed of 110 amino acid residues and a free amino terminus, and has a molecular mass of 11919. The amino acid sequences which are thought to be functionally important sites are also conserved in the bullfrog parvalbumin. The calculated phylogenic tree indicates that this parvalbumin belongs to the alpha group of parvalbumins. The mutation rate of parvalbumin was fairly rapid in frogs compared to mammals. The subdivergence of frogs is also discussed.

Amino Acid Sequence↗
PubMed1990

Purification and characterization of the parvalbumin from monkey skeletal muscle.

1. A high affinity Ca2+ binding and low mol. wt protein, parvalbumin, was purified from monkey skeletal muscle. 2. As compared with other animals, only one component and a lower content of monkey parvalbumin were found. 3. This may suggest that both the component and the content of parvalbumin decreases with biological evolution. 4. The parvalbumin was found to have a mol. wt of 11,400, a pI of 5.1, a high aspartic acid and lysine content, maximum absorption at around 260 nm, a blocked amino-terminal, an immunological distinction, 2 mol Ca2+ binding/mol, and a conformational change by Ca2+ binding. 5. Parvalbumin was shown to have alpha type properties.

Amino Acids↗
PubMed1990

[Experiments of contamination with bacteria while transfusion between the newly developed porous polymer plug and by air needle plug].

We newly developed a transfusion plug that has an air passage of polymer porous material (I Cap). This porous polymer material theoretical does not pass the infectious microorganisms. We experimented contaminations during the transfusions by I Cap and that using air needles. Trypticated soy broth was used for the experiments. Experiments of transfusion in a dusty environment revealed that the transfusions by air needles got 100% contamination and that by I Cap was 0%. The experiments in a clinic room transfusions also revealed that air needle resulted in 30.3% contamination but on the contrary 0% with the I Cap. Dusty air was flown under high pressure (1.5 atmospheric pressure) through the same filter of I Cap for 30 minutes into the trypticated soy broth. These experiments revealed that the filter did not permeate bacteria and that transfusions with air needle was contaminated with dust.

Air↗
PubMed1990

Transient and residual stress in a porcelain-metal strip.

Porcelain-fused-to-metal (PFM) restorations may develop cracks during processing or in-mouth service if the relative physico-mechanical properties of the porcelain and metal are highly mismatched. Precise conditions when this might occur are not known. Many processing and property variations can affect the stresses developed throughout a porcelain-metal system. To understand this, we conducted a computer simulation of stress developed in a PFM beam. The simulation considers cooling from temperatures higher than the porcelain sagpoint. The following temperature-dependent factors were incorporated: the elastic modulus, shear viscosity (porcelain), and coefficients of thermal expansion. The cooling rate dependencies of the glass transition temperature, (Tg), and the temperature distribution during cooling were also included. The results suggest that transient tensile stress at the porcelain alloy interface may result in cracks in the porcelain during cooling. Occlusal forces may set up stresses to cause cracking at the surface of the porcelain if the compressive residual stress is not high enough. PFM restorations with an alloy of high thermal expansion coefficient require rapid cooling; on the contrary, PFM restorations with the alloys of lower coefficients require slow cooling. A high cooling rate can make up for thermal expansion mismatches between the alloy and the porcelain up to 2 x 10(-6)/degrees C. Finally, the results indicated that curvature was not a sensitive indication of stress for a multimaterial beam when visco-elastic relaxation and high cooling rates are involved. For the case modeled here, curvature varied inversely with a 1/2 to 1/7th power of the stress.

Computer Simulation↗
PubMed1990

Viscosity of dental porcelains in glass transition range.

Changes in the viscosity of dental porcelain as a function of temperature are the controlling factor determining incompatible stresses in porcelain-fused-to-metal restorations. A new method was used to estimate viscosity using a viscoelastic analytical model that considers the relation between the heating rate and deformation temperature (Td) of dental porcelain with stress applied during heating. The activation energy of viscous flow and the viscous constant in the Arrhenius equation were calculated for six kinds of commercial body and opaque porcelains. The effect of the heating rate on the instantaneous coefficient of thermal expansion was also measured. Tg onset was graphically determined using data on thermal deformation and agreed well with the strain point as defined by viscosity. The data gathered in this study was also compared to the experimental results of previous works by others.

Dental Porcelain↗
PubMed1990

Temperature dependence of thermal expansion coefficient for palladium-based binary alloy.

Temperature dependencies of thermal expansion coefficients for the alloys of Pd-Ag, Pd-Cu and Pd-Co binary systems were measured at temperatures up to 900 degrees C, with heating and cooling rates of 5 degrees C/min. The coefficient of thermal expansion of alloys with no transformation in the temperature range of interest in porcelain firing was well approximated by a linear equation of temperature. The constants in the equation were shown as a function of the weight for the added element. Thermal expansion of the palladium-based alloy with no transformation was well estimated at any temperature range and at any composition by using the constants represented here. The coefficients of thermal expansion before and after order-disorder transformation and magnetic transformation were measured in Pd-Cu and Pd-Co alloys, respectively. The results suggest that transient and residual stresses in porcelain-fused-to-metal restorations can be effectively controlled by making use of transformation of the alloy.

Cobalt↗
PubMed1990

Effect of viscoelastic deformation of soft tissue on stresses in the structures under complete denture.

The time dependency of stress distribution in the supporting structures under dentures was simulated, under three loading conditions, by visco-elastic finite element stress analysis. In this simulation, viscoelastic material, was used as a model for soft tissue. The results indicate that the viscous flow of soft tissue and the loading position are factors determining stress intensity in the supporting structures under the denture. The stress intensity in the supporting structures was lowered when the occlusal force shifted towards the palatal side. Simulated results support Pound's lingualized occlusion theory.

Alveolar Process↗
PubMed1990

[Finite element analysis on physiological mobility of individual teeth].

The initial movement of the tooth was investigated by the finite element method. The mechanical properties of the periodontal membrane were estimated from the results of the simulation. The analysis was made by using an 8 point isoparametric finite element method. The upper central incisor with an axial directional load was simulated. The concept of the apparent elastic modulus was introduced to the stress-strain relation of the soft tissue, that is, soft tissue such as the periodontal membrane and the gingiva was considered to have stress dependent elastic moduli. At the first stage of the simulation, the stress and strain distributions in the paradentium were calculated by the conventional method. From the next stage, the apparent elastic moduli for the soft tissue were introduced to the calculation, that is, the elastic moduli for the soft tissue were computed from the calculated equivalent stresses of the previous stage. The calculations were repeated until the displacement values converged. The initial displacement of the tooth was not proportional to the applied load but showed a non-linear relationship. The relationship between load and displacement was approxiated by the n-th power equation. These results were in agreement with the clinical experimental results. The periodontal membrane is built up of different elastic moduli. The elastic moduli were low at the alveolar edge and the root apex. The equivalent stresses of the periodontal membrane were marked low in the alveolar edge and the root apex. In conclusion, the concept of the apparent elastic modulus is useful to investigate the initial movement of the tooth and estimate the mechanical properties of the periodontal membrane.

Computer Simulation↗
PubMed1989

Glutathione conjugation of nitro compounds by monkey glutathione S-transferases.

The distribution in Japanese monkey tissues of glutathione S-transferase activity toward some aromatic nitro compounds was examined by measuring the release of the nitro group as nitrite ion. The activity was especially high in liver, kidney and small intestine when compounds such as 4-nitroquinoline N-oxide, 5-nitrofurfural diacetal and o-dinitrobenzene were used as substrates. The nitrite-releasing activity of the major enzyme purified from rhesus monkey liver was also tested on fifty-two nitro compounds including nineteen nitrofuran derivatives. Among the thirty-three nitro compounds other than the nitrofuran derivatives tested as substrates, the purified enzyme showed activity only toward o-dinitrobenzene, 4-nitroquinoline N-oxide, 3,4-dinitrobenzoic acid, p-dinitrobenzene, 2,5-dinitrobenzoic acid, 2,5-dinitrophenol, tetra-chloronitrobenzene and 2,4-dinitrobenzoic acid. The crude supernatant fraction of rhesus monkey liver showed activity in substrate specificity roughly similar to that of the purified enzyme. On the other hand, among at least ten carcinogenic 2-substituted 5-nitrofran derivatives tested, 4,6-diamino-2-(5-nitro-2-furyl)-s-triazine, 5-nitro-2-furaldehyde semicarbazone, N-[[3-(5-nitro-2-furyl)-1,2,4-oxadiazol-5-yl]methyl] acetamide, and N-[5-(5-nitro-2-furyl)-1-3,4-thiadiazol-2-yl)acetamide were shown to be enzymatically conjugated with reduced glutathione. Among the other nine 2-substituted 5-nitrofuran derivatives tested, six compounds could be the substrates of the enzyme, and 5-nitrofurfural and 5-nitrofurfural diacetal were especially good substrates. There was, however, little apparent correlation between their carcinogenicity and susceptibility to glutathione S-transferase. The bulky substituents at position 2 appeared to decrease the susceptibility of these nitrofuran derivatives to the enzyme. Both Vmax and Km values of the purified enzyme varied greatly among the substrates, and the optimum pH fell between 7.5 and 9.0 in most cases.

Animals↗
PubMed1989

[Use of Rokitamycin dry syrup in cases of upper deep cervical lymphadenitis and otitis media with exudatives].

Dry syrup of Rokitamycin (RKM.DS), a new macrolide antibiotic with 16-membered ring developed by Toyo Jozo Co., Ltd., was used on cases of upper deep cervical lymphadenitis (UDCL) and of otitis media with exudatives (OME) likely caused by chlamydia infections, and its clinical effects were investigated. 1) In four cases of UDCL (C. psittaci infections), daily doses of 20.0-28.6 mg/kg were administered for 10-42 consecutive days and good efficacies were observed with two cases of excellent results and two cases of good results. 2) In one case of OME (C. trachomatis infection) a daily dose of 30.0 mg/kg was administered for 15 consecutive days and good effectiveness was observed. 3) No side effect was observed in any of the cases. From the above results, it became clear that RKM.DS could effectively used as a therapeutic agent for UDCL and OME in children.

Child↗
PubMed1989

Transient and residual stresses in dental porcelains as affected by cooling rates.

The development of either transient or residual stress in a slab of dental porcelain during cooling was simulated by use of a super-computer. The temperature dependences of the elastic modulus, the thermal expansion coefficient, and the shear viscosity, and the cooling rate dependence of the glass transition temperature, Tg, were considered in this calculation. Internal stress and viscoelastic creep were computed for several cooling rates. Calculated results display stress profiles which agree reasonably well with reported measured profiles in quenched, tempered glasses. The calculated residual surface stress, sigma, could be fit by the following empirical formula, sigma = kl2(q/q0)n, q is the cooling rate, q0 is a reference cooling rate and l is the half-thickness of the porcelain. The method by which residual stress develops is also discussed. This discussion suggests a method for strengthening of the porcelain by the development of high-compressive residual stress on the surface.

Computer Simulation↗
PubMed1985

Differences among primates in defence against infection: sensitivity of polymorphonuclear leukocytes to fMet-Leu-Phe.

The sensitivity of polymorphonuclear leukocytes (PMN) to N-formyl-methionyl-leucyl-phenylalanine (fMet-Leu-Phe) for chemotaxis and for lysosomal enzyme release was examined using the PMN of four primate species, human (H. sapiens), chimpanzee (P. troglodytes), rhesus monkey (M. mulatta), and cotton-headed tamarin (S. (O) oedipus). The 50 per cent effective concentrations (EC50) of fMet-Leu-Phe for chemotaxis were 2.5 X 10(-9) M in human, 10(-9) M in chimpanzee, 8 X 10(-8) M in rhesus monkey, and 3.3 X 10(-6) M in tamarin. The EC50 values of fMet-Leu-Phe for myeloperoxidase (MPO) release were 10(-8) M in human, 4 X 10(-8) M in chimpanzee, 4 X 10(-8) M in rhesus monkey, and 10(-6) M in tamarin and those for beta-glucuronidase release were 4 X 10(-9) M, 6.4 X 10(-8) M, 1.8 X 10(-7) M, and 1.6 X 10(-6) M, respectively. Thus, the sensitivity to fMet-Leu-Phe for chemotaxis was in the order: chimpanzee congruent to human greater than rhesus monkey greater than tamarin, and that for the release of lysosomal enzymes, MPO and beta-glucuronidase, was in the order: human greater than chimpanzee greater than rhesus monkey greater than tamarin. These results appear to indicate that the sensitivity to fMet-Leu-Phe increases in the order of evolution of primates toward the human, and suggest that the sensitivity of PMN in the defence function against infection also increases in the same order.

Animals↗