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Biomedical subjects

K Okazaki

Publications and source records attributed to K Okazaki.

At least 433 records · Page 24Linked to original sources
PubMed1982

Absence of DNA in peroxisomes of Candida tropicalis.

Yeast peroxisomes were purified to near homogeneity from cells of Candida tropicalis grown on oleic acid for the purpose of examining the possible presence of DNA in this organelle. The purification procedure includes the effective conversion of cells to spheroplasts with Zymolyase and sodium sulfite and the separation of the organelles at extremely low ionic strength. The mitochondrial contamination was less than 1%, based on several criteria, and the yield of peroxisomes was about 40%. The purified peroxisomal fraction contained a very small amount of DNA, which yielded restriction fragments indistinguishable from those of mitochondrial DNA. The absence of DNA in peroxisomes was also supported by cesium chloride density gradient centrifugation of the organelles lysed with a detergent, staining of the organelles with a fluorescent dye specific to DNA, and labeling of the DNA with [3H]adenine.

Adenine↗
PubMed1981

Selective modification of aspartic acid-101 in lysozyme by carbodiimide reaction.

A general procedure which selectively introduced a nucleophilic group at a particular location in the active site of lysozyme has been developed. The coupling of hen egg white lysozyme with amine nucleophiles by 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide hydrochloride (EDC) was studied at pH 5 and room temperature. In the presence of an amine nucleophile, such as ethanolamine, ethylenediamine, methylamine, or 4(5)-(aminomethyl)imidazole, the carboxyl side chain of aspartic acid-101 in lysozyme was selectively modified by using a small excess of EDC. The reactivity of Asp-101 is probably due to the specific binding of EDC to the substrate binding site close to Asp-101. With histamine or D-glucosamine, the selectively of Asp-101 was somewhat decreased. This may be due to the specific binding of these amines to lysozyme in competition with EDC, causing a decrease of the selective activation of Asp-101 by EDC. Depending on the amine employed, the lysozyme derivatives obtained exhibited decreased activity (83-52% of native enzyme), suggesting that the modification of Asp-101 weakened substrate binding.

Amino Acids↗
PubMed1981

Identification of residue 103 in hen egg-white lysozyme.

Since it has been uncertain whether residue 103 in hen egg-white lysozyme is aspartic acid or asparagine, we reexamined the identity of this residue. To avoid complication, the tryptic peptide T-13 (Ile 98-Arg 112) was further cleaved. The peptide containing residues Gly 102-Arg 112 was obtained by tryptic digestion of lysozyme modified at Asp 101 with diethylenetriamine. The peptide containing residues Ile 98-homoserine 105 was obtained by BrCN treatment of peptide T-13. Both Edman degradation of the former peptide and carboxypeptidase X digestion of the latter peptide identified residue 103 in hen egg-white lysozyme as asparagine.

Amino Acid Sequence↗
PubMed1981

Mechanisms of expression of herpes simplex virus-common surface antigens in clonal cells of a herpes simplex virus type 2-transformed line.

Rabbit antiserum hyperimmune to herpes simplex virus type 1 was used to study the expression of herpes simplex virus type-common surface antigens (CSA) by indirect immunofluorescence tests in three representative cell clones isolated from a herpes simplex virus type 2-transformed hamster line, 155-4. These three clones showed different phenotypes with respect to CSA expression: (i) a CSA-positive type (clone (155-4-213), in which the antigens increased soon (5 h) after seeding at 37 degrees C, but not after treatment with actinomycin D; (ii) a CSA-inducible type (clone 155-4-03), in which the antigens increased after treatment with actinomycin D (2 micrograms/ml) for 20 h, but not after seeding only; and (iii) a CSA-negative type (clone 155-4-16), in which the antigens did not increase after seeding or after actinomycin D treatment. CSA expression in the CSA-positive type was inhibited by 2-deoxy-D-glucose, but not by puromycin, suggesting that the expression required glycosylation, but not active protein synthesis. CSA expression in this type was insensitive to the protease inhibitors antipain and p-nitrophenyl-p'-guanidinobenzoate. On the other hand, actinomycin D-induced CSA expression in the CSA-inducible type was inhibited by both 2-deoxy-D-glucose and puromycin, suggesting that the induced expression required both glycosylation and protein synthesis. CSA expression induced in this type was sensitive to the two protease inhibitors at concentrations having little effect on overall cellular metabolism or cell viability. These results indicate that CSA expressions in the CSA-positive type and the CSA-inducible type are enhanced by different mechanisms.

Animals↗
PubMed1981

Expression of herpes simplex virus common surface antigens and malignancy by clonal cells of a herpes simplex virus type 2-transformed line.

Herpes simplex virus (HSV) type common surface antigens (CSA) were examined by indirect immunofluorescence with rabbit antiserum to HSV type 1 in a clonal hamster cell line 155-4 transformed by HSV type 2. The tumor formation was examined in hamsters transplanted with various transformed and tumor cells. The examination of subclones derived from 1554-cell line gave the following results. (1) Thirty subclones were isolated and classified into three phenotypes as to CSA expression: (i) in CSA-positive type (20% of the clones isolated), the number of CSA-positive cells increased soon (5 hr) after seeding at 37 degree; (ii) in CSA-inducible type (33% of the clones), the number of CSA-positive cells increased after treatment with actinomycin D (ACT-D, 2 micrograms/ml), but not without ACT-D; (iii) CSA-negative type (47% of the clones), the number of CSA-positive cells did not increase after seeding or after ACT-D treatment. (2) In tumor cell lines derived from the parent line and from three representative clones, CSA expressions were similar to that by CSA-negative type. (3) Transformed cells expressing CSA after seeding or after ACT-D treatment formed tumors and metastases less efficiently than cells expressing little CSA in transplanted hamsters. (4) Tumor cell lines formed tumors and metastases more efficiently than transformed cells expressing little CSA in transplanted hamsters.

Animals↗
PubMed1981

[Studies on Au-Ag-Pd-Cu alloys. (Part 3) Effects of additional elements to Au-Ag-Pd-Cu alloys (author's transl)].

In the previous papers, the author pointed out that alloys containing 30 wt% Au, 15-25 wt% Pd and Cu were more favourable for Au-Ag-Pd-Cu quarternary dental alloys. In this paper, the experiments were carried out to find the effects of additional elements and so, Pt, Ir, Os, W, Mo, Cr, Mn, Co, Zn, In, Sn and Si were added to 30 wt% Au-30 wt% Ag-20 wt% Pd-20 wt% Cu alloys ranging 0.1 wt% to 2.0 wt% respectively. Then, tensile strength, elongation, hardness, corrosion resistivity and porosity ratio were tested on these specimen. Results were as follows. 1) The addition of 0.2 wt% Ir, 0.2 wt% Os and 1.0 wt% Co were comparatively effective for the fineness of grain sizes, elongation and tensile strength. 2) The addition of 0.2 wt% W, 1.0 wt% Mo and 0.2 wt% Si showed respectively bad effect for porosities or mechanical properties. 3) The addition of 1.0 wt% Cr, 2.0 wt% Mn, 1.0 wt% Co, 2.0 wt% Zn and 2.0 wt% In were good for the decrease of porosities respectively and showed that the porosity ratio was lower than 0.2%. 4) The additions of 2.0 wt% Zn-1.0 wt% Pt-0.5 wt% Co to Au-Ag-Pd-Cu alloy was especially good and showed 80 kg/mm2 of tensile strength, 5.1% of elongation, 249 of Vicker's hardness number and 0.4% of porosity ratio.

Copper↗
PubMed1981

[Examination of blood levels and urinary excretion of cefmetazole in the mature and immature neonates (author's transl)].

1. Cefmetazole was administered to mature and immature neonates for the purpose of treatment and prophylaxis of infections, and the blood level was examined. The mean blood level (moni-trol I standard) of cefmetazole after a single administration, 20 mg/kg intravenously, were 63.9 mcg/ml in 0 to 3 days old neonates and 57.4 mcg/ml in 4 to 7 days old neonates after 30 minutes, and 24.2 mcg/ml and 12.4 mcg/ml, respectively, after 6 hours. 2. The mean half-life of the blood level was 5.42 hours in 0 to 3 days old neonates and 2.55 hours in 4 to 7 old neonates. 3. The urinary excretion was varied, but approximately 80% of the administered dose seemed to be excreted during 0 to 12 hours. 4. Cefmetazole is seemed to be clinically effective by a single dose of 20 mg/kg giving twice daily in every 12 hours in 0 to 3 days old neonates, a dose of 20 mg/kg giving three times daily in every 8 hours in 4 to 7 days old infants, and a single dose of 20 mg/kg giving 3 to 4 times in every 6 to 8 hours in older than 8 days old neonates.

Anti-Bacterial Agents↗