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T Miyata

Publications and source records attributed to T Miyata.

At least 19 recordsLinked to original sources
PubMed1979

The preferential codon usages in variable and constant regions of immunoglobulin genes are quite distinct from each other.

The pattern of codon utilization in the variable and constant regions of immunoglobulin genes are compared. It is shown that, in these regions, codon utilizations are quite distinct from one another: For most degenerate codons, there is a selective bias that prefers C and/or G ending codons to U and/or A ending codons in the constant region compared with the bias in the variable region. This would strongly suggest that, in immunoglobulin genes, the bias in code word usage is determined by other factors than those concerning with the translational mechanism such as tRNA availability and codon-anticodon interaction. A possibility is also suggested that this differance of code word usage between them is due to the existence of secondary structure in the constant region but not in the variable region.

Anticodon↗
PubMed1979

Secondary structure of MS2 phage RNA and bias in code word usage.

Based on the secondary structural model of MS2 RNA, it is shown that, in base-pairing regions of the RNA, there is a bias in the use of synonymous codons which favours C and/or G over U and/or A in the third codon positions, and that in non-pairing regions, there is an opposite bias which favours U and/or A over C and/or G. This nature is interpreted as a result of selective constraint which stabilises the secondary structure of the single-stranded RNA genome of the MS2 phage.

Base Sequence↗
PubMed1979

Two types of amino acid substitutions in protein evolution.

The frequency of amino acid substitutions, relative to the frequency expected by chance, decreases linearly with the increase in physico-chemical differences between amino acid pairs involved in a substitution. This correlation does not apply to abnormal human hemoglobins. Since abnormal hemoglobins mostly reflect the process of mutation rather than selection, the correlation manifest during protein evolution between substitution frequency and physico-chemical difference in amino acids can be attributed to natural selection. Outside of 'abnormal' proteins, the correlation also does not apply to certain regions of proteins characterized by rapid rates of substitution. In these cases again, except for the largest physico-chemical differences between amino acid pairs, the substitution frequencies seem to be independent of the physico-chemical parameters. The limination of the substituents involving the largest physico-chemical differences can once more be attributed to natural selection. For smaller physico-chemical differences, natural selection, if it is operating in the polypeptide regions, must be based on parameters other than those examined.

Amino Acid Sequence↗
PubMed1979

[Clasp designing].

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Denture Design↗
PubMed1978

Collagen-induced platelet aggregation and release. I Effects of side-chain modifications and role of arginyl residues.

To investigate the mechanisms governing collagen interaction with blood platelets, the effects of side-chain modifications on collagen-induced platelet aggregation and release of serotonin were studied. Since many chemical modifications alter the ability of collagen to form fibers that, according to current theory, may complicate interpretation of data, we eliminated this possibility by using collagen stabilized in a native-type fibrillar structure by treatment with either glutaraldehyde or ultraviolet irradiation. Acetylation, methylation, succinylation, treatment with 2,4-dinitrofluorobenzene, 2,4,6-trinitrobenzene sulfonic acid or 1,2-cyclohexanedione, and deguanidination with hypobromite were used to modify collagen side-chain reactive groups: amino, carboxyl, hydroxyl and guanidino. Both unmodified monomeric dispersed and fibrillar collagen preparations initiated platelet aggregation and release, although the kinetics and magnitude of the response were different. Monomeric collagen which had been modified by deguanidination, methylation or succinylation, failed to polymerize in physiological conditions and did not induce platelet aggregation and release. However, none of the chemical modifications of stabilized native-type collagen fibers, except treatment with hypobromite or cyclohexanedione, had an effect on collagen-induced platelet aggregation and release. Both hypobromite and cyclohexanedione modified guanidino groups of arginyl residues. Results showed that the ability of a collagen sample to induce platelet aggregation and release of serotonin is dependent on the arginine content of fibrillar collagen. These data demonstrate that manipulation of amino, carboxyl and hydroxyl groups is unimportant as long as the native-type fibrillar structure is maintained, and that arginyl residues are directly involved in collagen-platelet interaction. Moreover, the data suggest that only the arginyl residues in the Y position of the tripeptide unit Gly-X-Y of collagen are responsible.

Amino Acid Sequence↗
PubMed1978

Soluble gentamicin ophthalmic inserts as a drug delivery system.

A comparison was made of soluble 14C-gentamicin ophthalmic inserts with drop, ointment, and the subconjunctival routes of administration. The insert is a solid, solubilizable collagen polymer containing 14C-gentamicin. We compared the levels of 14C-gentamicin in the rabbit tear film and in multiple corneal and scleral biopsies to determine which route of administration gave the best results. The wafer route of administration gave the highest tear film and tissue concentration of drug. The tear film concentration by subconjunctival injection was surprisingly low. Soluble collagen inserts offer a new method of delivering high doses of gentamicin in infected corneal tissue in a convenient and atraumatic fashion.

Administration, Topical↗
PubMed1978

Metabolites of piperidine in rat urine.

Piperidine is one of pharmacologically active biogenic amines. While two pathways for piperidine production have been reported, little is known about metabolism of the compound. In the present study, piperidine and its hydroxylated, conjugated and unknown metabolites were detected in rat urine by radiochromatographic analysis. Using GC-MS technique, it was confirmed that 3-hydroxypiperidine and 4-hydroxypiperidine are major metabolites of piperidine of either exogenous or endogenous origin. The findings substantiate the existence of a mechanism which inactivates piperidine in the living body, since both metabolites lack the potent pharmacological activities as those induced by piperidine.

Acetylation↗
PubMed1978

[Action of 4-amino-alpha-](tertbutylamino) methyl]-3, 5-dichlorobenzylalchol hydrochloride (N-AB 365, clenbuterol) on the respiratory system (author's transl)].

The bronchodilating effect and other related pharmacological properties of N-AB 365 were studied in comparison with those of isoproterenol, salbutamol and clorprenaline. N-AB 365 was found to produce a bronchodilating effect 1/20 approximately 1/100, 1/10 approximately 1/40 and was 2 to 5 times as strong as effects of isoproterenol, salbutamol and clorprenaline, respectively. The bronchodilating effect of N-AB 365 was sustained more than 10 times as long as those of isoproterenol and salbutamol, and in particular with oral administration, was much more potent. The bronchodilating effect of N-AB 365 seems to be due mainly to excitation of the adrenergic beta2-receptor and partially to papaverine-like action. N-AB 365 showed an inhibitory effect on experimentally induced bronchial asthma by spraying of bronchoconstrictors and the effect by oral administration was much stronger than those of isoproterenol and salbutamol. N-AB 365 affected neither the volume output of respiratory tract fluid nor the tracheal ciliary movement with the doses around ED50 in bronchodilating action, however, it increased ciliary activity and decreased the volume output of respiratory tract fluid with large doses. Antitussive effect was also demonstrated only with the large doses. N-AB 365 induced a moderate decrease in blood pressure through vasodilatation but did not influence respiration. The effect of N-AB 365 on heart rate varied. There were cases of no change, slight increase or slight decrease in heart rate.

Acetylcholine↗
PubMed1977

Soluble artifical tear inserts.

This article reports a new concept in the treatment of tear film abnormalities. Solubilization of an artifical tear insert provides a continuous flow of polymer into the tear film in place of intermittent drop therapy. The physiochemical properties of succinylated collagen were studied in vitro and compared favorably with presently available tear substitutes. The use of this polymer as a solid solubilizable insert was evaluated in normal patients. It was found to be comfortable, resulted in no blurring of vision, and prolonged the tear film breakup time.

Cellulose↗