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Biomedical subjects

T Imoto

Publications and source records attributed to T Imoto.

At least 163 records · Page 9Linked to original sources
PubMed1984

[Pharmacokinetic studies of ampicillin during and following intravenous drip infusion in healthy human volunteers].

The pharmacokinetics of ampicillin (ABPC) during and following intravenous drip infusion in 3 healthy volunteers weighing 63.0 kg to 75.0 kg. ABPC was administered 1.0 g by intravenous drip infusion for 1 hour. Serum concentrations were measured, and simulation curve were obtained by using one-compartment model and two-compartment model. The simulation curve by two-compartment model was more applicable than the simulation curve by one-compartment model. Most appropriate administration rate of intravenous drip infusion was discussed due to calculated serum levels, therapeutic AUC and effective time.

Adult↗
PubMed1983

Intramolecular cross-linkage of lysozyme. Imidazole catalysis of the formation of the cross-link between lysine-13 (epsilon-amino) and leucine-129 (alpha-carboxyl) by carbodiimide reaction.

The salt bridge between Lys-13 (epsilon-NH3+) and Leu-129 (alpha-COO-) in lysozyme was converted to an amide bond by 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide hydrochloride (EDC) reaction in the presence of imidazole (0.3-1 M) at pH 5 and room temperature, followed by dialysis at pH 10. Absence of imidazole under a similar condition did not give this intramolecularly cross-linked lysozyme derivative (CL-lysozyme) but resulted in the formation of intermolecularly cross-linked lysozyme oligomers. From the mechanistic studies on the formation of CL-lysozyme, imidazole was suggested to play the following three roles. (1) Some carboxyl groups activated by EDC in lysozyme were converted to acylimidazole groups which protected them from the reaction with amino groups in other lysozyme molecules at pH 5. These could be hydrolyzed at pH 10 to regenerate free carboxyls. (2) High concentrations of imidazole (pH 5) increased the ionic strength of the solution which weakened the salt bridge in lysozyme and facilitated the activation of the alpha-carboxyl group by EDC. (3) The alpha-carboxyl group activated by EDC was converted to an acylimidazole group which could react with the epsilon-amino group of Lys-13 in the same molecule to form an amide bond. The last step may involve some conformational change of the backbone of lysozyme and be slower than the hydrolysis reaction of the alpha-carboxyl group activated by EDC itself. However, acylimidazole groups are stable against hydrolysis at pH 5. This may afford enough time to allow the epsilon-amino group of Lys-13 to attack the acylimidazole group of Leu-129.

Animals↗
PubMed1983

Electrostatic free energy of lysozyme.

The electrostatic free energies of native and acetylated lysozymes were computed by the fixed charge model (Tanford, C., and J. G. Kirkwood, 1957, J. Am. Chem. Soc., 79:5333-5339). For each computation, the charges were transformed into a sphere of fixed radius without changing their depths or the distance between charges. The depths of charges were assumed proportional to one minus accessibility. When the conversion factor was set to 1.62 A, the computed titration curve fitted best to the experimental data. The calculated electrostatic free energies for native and acetylated lysozymes were consistent with our earlier finding that acetylated lysozyme is less stable than native around neutral pH (Imoto, T., K. Fukuda, and K. Yagishita, 1976, J. Biochem. [Tokyo], 80:1313-1318; Imoto, T., S. Moriyama, and K. Yagishita, 1976, J. Biochem. [Tokyo], 80:1319-1325). The contribution of each charge to the stabilization of the protein and the apparent pK's of ionizable groups were computed by this method.

Animals↗
PubMed1983

Otoneurological test results analyzed by means of a quantitative statistical method.

This report is a presentation of an approach to the prediction of cerebellar-pontine (C-P) angle tumors and four peripheral vestibular diseases from a mathematical statistical point of view. The present study was performed in an attempt to quantify multidimensional, quantitative data. The data analyzed were from a total of 143 patients with C-P angle tumors, Menière's disease, sudden deafness, vestibular neuronitis, and benign paroxysmal positional vertigo (BPPV). Tests were carried out mainly on otoneurological parameters. By means of discriminant analysis as employed in the quantification method, the patients were classified in the 4-dimensional space.

Adult↗
PubMed1983

[Pharmacokinetics of cephapirin sodium during intravenous infusion].

Studies on absorption and excretion of cephapirin (CEPR) are described. CEPR was administered by intravenous drip infusion to 4 healthy volunteers weighing 53 kg to 61 kg, and the serum levels were measured. Pharmacokinetic parameters were calculated by one-compartment model and two-compartment model. Each model was comparatively applied to every founds. Most appropriate administration rate of intravenous drip infusion was discussed due to calculated serum levels, therapeutic AUC and effective time.

Cephalosporins↗
PubMed1983

Glycerin and urea tests in Meniere's disease. A multifactorial analysis using a quantification method.

By using the quantification method for multidimensional qualitative data, 13 variables were analyzed. The younger the patient, the stronger was the correlation between age and positive glycerin and urea tests. At ages over 50 years no correlation with positive test results was found. The longer the duration of disease, the stronger was the correlation between this duration and a positive urea test. The glycerin test showed no correlation with the duration of the disease. Hearing losses of 40 to 69 dB. were correlated with both a positive glycerin test and a positive urea test. Greater hearing losses were correlated only to a positive glycerin test. Hearing losses less than 39 dB. were not correlated with positive results in either the glycerin or the urea test.

Adult↗
PubMed1982

Specificity of trypsin. Cleavage of aspartic acid 101 derivatives of lysozyme by trypsin.

The beta-carboxyl group of Asp 101 was modified with several amine nucleophiles by the amine-carbodiimide procedure and the trypsin susceptibilities of the derivatives were analyzed by peptide mapping. The (aminoethyl)asparaginyl peptide bond was completely cleaved by trypsin but the (3-aminopropyl)asparaginyl bond was not. When the positive charge was in the proper position, large residues such as (2-[imidazol-4(5)-ylmethylamino]ethyl) asparagine or (11-amino-3,-6,9-triazaundecyl)asparagine were susceptible to trypsin.

Amines↗
PubMed1982

Modification of catalytic groups in lysozyme with ethylenimine.

The reaction of lysozyme with ethylenimine has been studied at neutral and acidic pH. At least four singly modified lysozyme derivatives have been isolated. From the product analyses, only carboxyl groups in the protein were found to react. One of the derivatives, 1, was very labile and reverted back to native lysozyme during the isolation procedure. Its formation was markedly inhibited by the presence of tri(N-acetyl-D-glucosamine), indicating that the modified carboxyl residue in 1 is at or close to the binding site of lysozyme for the trisaccharide. Two other derivatives were identified as 2-aminoethyl esters of Glu-35 (2) and Asp-52 (3). At pH 10 and room temperature, these derivatives rearranged to the corresponding 2-hydroxyethylamide derivatives (5 and 6). A fourth derivative (4) did not contain an ethanolamine moiety; nevertheless, its Glu-35 was found to be modified by sequence analysis. Lysozyme derivatives modified at Glu-35 and Asp-52 were inactive toward glycol chitin but retained high affinity for tri(N-acetyl-D-glucosamine). Thus, Glu-35 and Asp-52 are essential for enzyme activity. A mechanism for the selective modification of these carboxyl residues in lysozyme has been proposed and related to the metal binding ability of lysozyme.

Animals↗
PubMed1982

A new electrophoretic variant of hemoglobin (Ogi) in which a leucine residue is replaced by an arginine residue at position 34 of the alpha-chain.

Hemoglobin Ogi, in which an arginine is substituted for a leucine residue at position 34 of the alpha-chain, was detected in a Japanese family. Although slightly increased oxygen affinity is associated with this amino acid substitution in the alpha 1 beta 1 contact, it is without obvious deleterious effect on the hematological parameters of the individuals heterozygous for this variant.

Amino Acid Sequence↗