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K Hibino

Publications and source records attributed to K Hibino.

8 recordsLinked to original sources
PubMed1990

[Fundamental properties of the human lateral pterygoid muscle activity and quantitative observation in relation to vertical dimension and bite force].

The purpose of this study is to investigate the fundamental property of the superior head of the lateral pterygoid muscle (LPT) of the human beings. The experiments were performed on 6 subjects. Electromyographic activity of the superior head of LPT were simultaneously recorded with masseter, temporal and digastric muscle. The findings may be summarized as follows: 1. Superior head of LPT showed the maximum activity during closing and clenching. 2. Superior head of LPT showed remarkable tonic activity at rest position and notable activity during swallowing and passive retrusion. 3. Superior head of LPT activity was related to vertical dimension and bite force quantitatively, but such relationship was quite different from masseter and temporal muscle. 4. Jaw-jerk reflex was evoked by mechanical chin tap in the superior head of LPT, masseter and temporal muscle showing identical time course. 5. Periodontal excitatory reflex was evoked by mechanical tooth stimulation in the superior head of LPT and temporal muscle. From these findings it was concluded that superior head of LPT was qualitatively similar to but quantitatively distinct from jaw closing muscles such as masseter and temporal muscle.

Bite Force↗
PubMed1989

[Study of a particle counting method for index of masticatory efficiency].

The present report discusses our new simplified measuring method of masticatory efficiency by counting particles in the matter of making test materials and the standard equation for subjects with normal dentition. 1. Two kinds of hydrocolloid impression materials, reversible and irreversible, were used as the test materials. 2. For evaluating the shape of test materials, 12 subjects with normal dentition were tested and for calculating the standard equation, 108 subjects with normal dentition were tested. 3. Each subject was investigated by the simplified method of counting particles through a sieve system. The number of remaining particles on the mesh was calculated as a masticatory performance. 4. As indicated in a previous report by Dr. Ozawa about cubical test materials, columnar test materials are easier to make than the others and these were avairable for the present particle counting method for investigating masticatory efficiency. 5. We obtained the standard equation for both kinds of test material using 108 subjects with normal dentition. To simplify the measuring method, we selected the standard equation of a 5-mesh sieve with 10 strokes chewing for the index of masticatory efficiency. The standard equation of a 5-mesh sieve for both test materials are as follows; 1) Reversible hydrocolloid test material: Y = -1.605X+29.058 2) Irreversible hydrocolloid test material: Y = -1.116X+23.868 6. 5, 10-mesh sieve with 10 strokes chewing showed the smallest variation in the individual coefficient of variation with both kinds of test material.

Colloids↗
PubMed1988

Age-dependent effect of UV light in abnormal alpha neoprotein formation in the lens.

The aim of this study was to determine whether or not alpha neoprotein formation can occur in the lens in response to a photolytic process. Alpha crystallin from young calf and aged bovine lenses was irradiated for up to 22 hours with UV light. After cortical alpha crystallin had been irradiated, it completely preserved its quaternary antigenic determinants. In contrast, 24.3% of the bovine nuclear alpha crystallin completely lost their quaternary determinants as a result of irradiation. The latter population of molecules still preserved the association of A chains with B chains, suggesting the formation of abnormal proteins. The exposure to UV irradiation can cause the formation of alpha neoproteins from aged but not from young alpha crystallin. Comparison of photolytic rates based on spectroscopic and chromatographic parameters also show an age-related increase in the susceptibility of alpha crystallin to photolyze. It is suggested that this increase is due to the age-related formation of a photosensitizer in alpha crystallin.

Aging↗
PubMed1976

Hybridization of glyceraldehyde-3-phosphate dehydrogenase in borate.

Conditions for the hybridization of glyceraldehyde-3-phosphate dehydrogenase (GPD) [EC 1.2.1.12] in the presence of dilute borate were examined with horseshoe crab and rabbit GPDs. Hybridization was strongly dependent upon pH, borate concentration, and temperature. The optimum medium for hybridization was 10mM Tris-HCl-1 mM 2-mercaptoethanol-1mM EDTA containing 10-20 mM borate, pH 8.5-9.0. Hybridization was performed by incubation of two electrophoretically distinct GPDs at 30 degrees for 3-15 hr in the above medium at a protein concentration of 1-2 mg/ml. The time course of hybridization was analyzed under the optimized conditions. Symmetrical A2B2-type hybrid appeared only 5 min after incubation for 1 hr. Hybridization of GPDs from 7 different species was examined under the optimal conditions. Hybridization was detected with rabbit-horseshoe crab, yeast-rabbit, yeast-chicken, and chicken-horseshoe crab combinations. Subunit-subunit interaction, the mechanism of hybridization, and the structure of GPD are discussed based on the results obtained.

Animals↗