Search PubMed⌕ Search

Biomedical subjects

A Yoshida

Publications and source records attributed to A Yoshida.

At least 1,261 records · Page 70Linked to original sources
PubMed1976

Urinary levels of vanilmandelic acid and homovanillic acid determined by high-speed liquid chromatography.

High-speed liquid chromatographic determinations of vanilmandelic acid and homovanillic acid in human urine have been made. The effects of taking refreshments on the assay were examined. HVA conjugates in urine also were hydrolyzed and determined. Urinary excretion of vanilmandelic acid, free and conjugated homovanillic acid in normal subjects and patients with neuroblastoma, phaeochromosytoma and Sipple's syndrome were determined and discussed. Urinary excretion values (mean +/- 1 S.D.) of vanilmandelic acid and homovanillic acid in 14 normal subjects were 2.0 +/- 0.7 mg/day and 4.0 +/- 1.0 mg/day, respectively.

Adult↗
PubMed1976

Purification and chemical characterization of human hexosaminidases A and B.

N-Acetyl-beta-hexosaminidases A and B were purified to homogeneity from human placenta. In the initial step of purification, the enzymes were adsorbed on concanavalin A-Sepharose 4B and eluted from the column with alpha-methyl D-mannosides. Subsequent purification steps included DEAE-cellulose column chromatography, QAE-Sephadex [diethyl-(2-hydroxypropyl)aminoethyl-Sephadex] column chromatography, Sephadex G-200 gel filtration and preparative disc polyacrylamide-gel electrophoresis, followed by another QAE-Sephadex chromatography for the hexosaminidase A preparation, and DEAE-cellulose column chromatography, calcium phosphate gel chromatography, Sephadex G-200 gel filtration, QAE-Sephadex chromatography and CM-cellulose chromatography for the hexosaminidase B preparation. The purified preparations, particularly hexosaminidase A, had significantly higher specific enzyme activities than previously reported. The preparations moved on polyacrylamide-gel electrophoresis as single protein bands, which also stained for enzyme activity. Sedimentation-equilibrium centrifugation indicated homogenous dispersion of the enzymes, and the molecular weight was estimated as about 110000 for both enzymes. Complete amino acid and carbohydrate compositions of the two isoenzymes were determined, and, in contrast with previous suggestions, no sialic acid was found in the enzymes.

Amino Acids↗
PubMed1976

The subunits of human hexosaminidase A.

Previous studies of the subunit structure of hexosaminidase gave ambiguous results, but suggested that the enzyme was composed of six equally sized subunits. Dissociation of hexosaminidase A with p-chloromercuribenzoate produces an alkylated fragment with mol.wt. approx. 50000, which is converted into hexosaminidase S by treatment with dithiothreitol. Treatment of native hexosaminidase A with sodium dodecylsulphate results in the formation of a large and a small fragment. However, although the native enzyme has a sedimentation coefficient of 5.8S, dissociation by S-carboxymethylation and maleic anhydride treatment results in subunits exhibiting a single schlieren boundary on analytical ultracentrifugation with a sedimentation coefficient of 2.18S. These results indicate that the enzyme is composed of four subunits, each with molwt. approx. 25000-27000. The mol.wt. of the native enzymes is calculated to be approx. 110000. Our data are consistent with the subunit structures of hexosaminidases A, B and S as being alpha2beta2, beta4 and alpha4 respectively.

Electrophoresis, Polyacrylamide Gel↗
PubMed1976

Human-serum cholinesterase subunits and number of active sites of the major component.

The major C4 component of human serum cholinesterase was highly purified by a two-step procedure involving chromatography on DEAE-cellulose and preparative disc electrophoresis. The final product was about 8 000-fold purified with a yield of 64%. The subunit structure was determined by 8M urea polyacrylamide disc electrophoresis and by the sedimentation equilibrium centrifugation method in 5M guanidine hydrochloride. It was found that the C4 enzyme has a tetrameric structure. The subunits are equal in size and charge and a molecular weight comparable to that of the C1 enzyme from native serum. The major C4 enzyme and the minor C1 enzyme were subjected to an 'active enzyme centrifugation'. It was found that the C4 enzyme was a tetramer and the C1 enzyme was a monomer in the presence of substrate. The number of diisopropylphosphofluoridate-binding sites was measured from the molar ratio of bound diisopropylphosphate to protein. A value close to two binding sites was found for the C4 enzyme.

Amino Acids↗
PubMed1976

Glucose 6-phosphate dehydrogenase in rainbow trout.

Electrophoretic analysis of glucose 6-phosphate dehydrogenase from liver and blood of rainbow trout revealed a complex series of bands, which could differ between fish. The partial interconvertible nature of these bands was demonstrated with enzyme that had been incompletely inactivated at pH 8.4. In a single population of 40 fish, a homozygote and a heterozygote for an electrophoretic variant allele were found. We suggest that G6PD in rainbow trout liver and blood is determinted by two alleles at a single locus, with posttranslational modification responsible for the complex electrophoretic patterns seen. The basis for this variation appears to be NADH binding to the protein molecule. Another variant and other properties of the enzyme are described.

Animals↗
PubMed1976

Molecular abnormality of human alpha1-antitrypsin variant (Pi-ZZ) associated with plasma activity deficiency.

A human alpha1-antitrypsin variant protein was purified to homogeneity from homozygous variant subjects (Pi-ZZ) who had a deficiency of plasma trypsin inhibitory capacity. Molecular weight, specific trypsin inhibitory capacity, and immunologic activity of the variant protein were identical to those of normal. Amino acids, N-acetylglucosamine, and hexose contents were closely similar in the normal and variant proteins, but the sialic acid content in the variant protein was significantly lower than normal. The structural difference between the normal and the variant alpha1-antitrypsin was elucidated by fingerprinting of their tryptic peptides. Two amino acid substitutions, i.e., glutamic acid in the normal protein to lysine in the variant protein, and glutamic acid in the normal protein to glutamine in the variant protein, were found.

Amino Acids↗
PubMed1976

Some factors affecting the nitrogen sparing action of methionine and threonine in rats fed a protein free diet.

It was previously reported that methionine and threonine supplementation of a protein free diet had a greater nitrogen sparing action than methionine supplementation alone. Investigated in this study were (1) effects of depletion of labile body protein on the nitrogen sparing action of methionine and threonine supplementation of a protein free diet, (2) the effects of graded levels of methionine and threonine on urinary nitrogen excretion, (3) the effect of supplementation of other amino acids to the protein free diet plus methionine and threonine on the urinary excretion of nitrogen and (4) sex differences in the nitrogen sparing action of methionine and threonine supplementation of a protein free diet. After 10 days of feeding a protein free diet to deplete the body labile proteins, nitrogen excretion in urine of female rats was significantly reduced within the first 2 days of feeding a protein free diet supplemented with methionine and threonine. After 7 days of feeding a protein free diet supplemented with methionine and threonine, nitrogen excretion was reduced when even as little as 0.0188% of each amino acid was added. The supplementation of all essential amino acids to the protein free diet did not reduce the urinary excretion of nitrogen further than the supplementation of methionine and threonine, but improved the nitrogen balance slightly. The excretion of urinary nitrogen by female rats fed the protein free diet supplemented with small amounts (0.0188%) of methionine and threonine was significantly reduced after 7 to 14 days of feeding. In males, small amounts of methionine and threonine had no significant effect at either 7 or 14 days.

Amino Acids↗
PubMed1976

Myosin-free ghosts of single fibers and an attempt to re-form myosin filaments in the ghost fibers.

With the final aim of replacing myosin in a single muscle fiber, a technique for removing myosin almost completely from single fibers was developed and an attempt to "re-form" thick filaments in the myosin-free ghosts of single fibers was made. Complete removal of myosin from single glycerol-treated rabbit psoas fibers with Hasselbach-Schneider solution was difficult. However, when skinned glycerol-treated fibers were used and 1% (v/v) Triton X-100 was added to the Hasselbach-Schneider solution, almost complete removal of myosin was possible. The myosin-free ghosts of skinned single fibers were very fragile but retained the overall structure. In the ghost fibers, Z-membranes and thin filaments remained. The ghost fibers, after irrigation with myosin, underwent contraction upon addition of Mg-ATP. In the myosin-irrigated fibers, thick filaments were re-formed in lengths from one Z-membrane to the other Z-membrane of a sarcomere, running parallel to the thin filaments. The packing of these two filaments was not good. The isometric tension developed by the irrigated fibers upon addition of mg-ATP was about 10% of the tension developed by untreated fibers. The weak tension developed by irrigated fibers is probably due to the irregular packing of the thick and thin filaments in the fibers. The ghost fibers also contracted, though only slightly, upon addition of Mg-ATP after irrigation with heavy meromyosin.

Adenosine Triphosphate↗
PubMed1976

Temperature-dependence of tension development by glycerinated muscle fibers of rabbit psoas in Mn (II)-ATP and Mg-ATP solutions.

The tension of single fibers isolated from glycerinated rabbit psoas muscle was measured at various temperatures using Mg-ATP or Mn-ATP as a substrate. The tension developed in Mn-ATP was 80-89% of that in Mg-ATP at 4 degrees-16 degrees, and both tensions decreased as the temperature was reduced. Myosin forms the myosin-product complex predominantly generated on admixture with ADP (and Pi) at the burst site during Mn(II)-ATP hydrolysis below 10 degrees, while it forms the myosin-product complex predominantly formed via ATP hydrolysis upon hydrolysis above 10 degrees, as it does during Mg-ATP hydrolysis (Hozumi & Tawada (1975) Biochim. Biophys. Acta 376, 1; Tawada & Yoshida (1975) J. Biochem. 78, 293; Yazawa & Morita (1973) J. Biochem. 74, 1107). Since the cycle time of cross-bridge attachment to and detachment from actin in muscle is about 1-10 sec and because the spontaneous decay time of the myosin-product complex into the myosin-product complex in the absence of actin is less than 1 sec, then if most of the cross-bridges are detached from actin as suggested by X-ray data, it can be inferred that most of the cross-bridges detached from actin may form the predominant myosin-product complex in Mn-ATP below 10 degrees. If this is so, the tension development in Mn-ATP below 10 degrees cannot be compatible with some muscle models which assume the formation of the myosin-product complex by the cross-bridges prior to combination with actin during contraction.

Adenosine Triphosphate↗
PubMed1976

[Clinical study of amoxicillin used in the otorhinolaryngological field (author's transl)].

The following results were obtained from oral administration of amoxicillin to 20 cases of acute otorhinolaryngological infections for 5 consecutive days; the daily dose was 1,500 mg for adult and 750mg for child. 1. Six cases with acute tonsillitis, 6 with acute pharyngolaryngitis, 5 with acute otitis media, 2 with furuncle of the nose and 1 with acute laryngitis were treated with amoxicillin. This drug was remarkably effective in 2 of 20 cases in total, effective in 15, slightly effective in 1 and non-effective in 2. 2. The sensitivity test to amoxicillin by the use of ampicillin sensitivity disk revealed that all of isolated bacteria were remarkably sensitive to amoxicillin, except one strain of Staphylococcus aureus which was moderately sensitive. 3. Side effect occurred at the rate of 25%; 4 cases of eruption and 1 of esophagitis. Other severe side effects were not observed. From the above results, amoxicillin is considered to be an effective drug for clinical application in the otorhinolaryngological field.

Acute Disease↗
PubMed1976

Studies on gamma-glutamyl transpeptidase in human and rabbit erythrocytes.

Gamma-glutamyl transpeptidase transfers the gamma-glutamyl moiety of glutathione to a variety of acceptor amino acids. Through the operation of the gamma-glutamyl-cyclotransferase cycle, this enzyme has been implicated in the transport of amino acids into cells, especially the cells of the proximal tubules of kidney. It has been reported to be present in rabbit erythrocytes. However, using white cell-free preparations, we have not been able to demonstrate the presence of gamma-glutamyl transpeptidase in human or rabbit erythrocytes either by measuring the utilization of GSH or by following the formation of the product. 14C-L-methionine was used as acceptor amino acid, and the formation of gamma-glutamyl-14C-L-methionine was followed. Using similar conditions, we have been able to demonstrate the presence of gamma-glutamyl transpeptidase in human and rabbit leukocytes and in human kidney. In contrast to a previous report, we were unable to find the accumulation of 5-oxoproline, an intermediate of the gamma-glutamyl-cyclotransferase pathway in human red cells incubated in Krebs-Ringer solution. Immunologic studies demonstrated that human red cell membranes contained no protein antigenically similar to kidney gamma-glutamyl transpeptidase. Thus our studies indicated that in human and rabbit erythrocytes, the gamma-glutamyl transpeptidase-cyclotransferase pathway was not operative.

Animals↗