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Biomedical subjects

K Fukuhara

Publications and source records attributed to K Fukuhara.

At least 127 records · Page 7Linked to original sources
PubMed1988

Development of the epididymal adipose tissue in monosodium glutamate-induced obese mice.

Obesity was induced in neonatal mice by subcutaneous injections of monosodium glutamate (MSG) at an early neonatal stage. The process of adipocyte formation was studied comparatively in the developing epididymal adipose tissue of the MSG-treated mice and in normal mice during the period from the 6th to the 100th postnatal day. Tritiated thymidine autoradiographic studies showed that cell proliferation activity was the highest on the 6th postnatal day both in the MSG-treated and the control mice. In normal mice, however, cell proliferation took place less frequently after 6 days and had almost ceased after 49 days. In the obese mice, as evidenced by relatively high labeling indices, cell proliferation continued to occur even after 49 days. Ultimately there was no difference in the number of adipocytes counted by Hirsch's method in the MSG-treated and the control mice at the 100th postnatal day. The storage of fat droplets became more noticeable in obese mice than in normal mice after 35 days. The mean size of fat droplets of the obese mice was twice as large as that in normal mice on the 49th postnatal day. These results indicate that the MSG-induced obesity is of the hypertrophic type.

Adipose Tissue↗
PubMed1987

Primary structure of Paim I, an alpha-amylase inhibitor from Streptomyces corchorushii, determined by the combination of Edman degradation and fast atom bombardment mass spectrometry.

Paim I, a protein alpha-amylase inhibitor, inhibits animal alpha-amylases from pig, dog, cow, horse, etc. but has no activity against human salivary and pancreatic amylases. The primary structure of Paim I has been determined by Edman degradation and fast atom bombardment mass spectrometry (FABMS). This protein is a single-chain polypeptide of 73 amino acid residues with a calculated molecular weight from the sequence data of 7415.3 (monoisotopic molecular weight) and 7420.2 (average molecular weight). The sequencing strategy chosen for Paim I consists of four steps. First, the accurate molecular weights of the intact and tetra-S-carboxymethylated Paim I are determined by fast atom bombardment mass spectrometry. Second, the primary fragments generated by Staphylococcus aureus V8 protease are isolated by reversed-phase high-performance liquid chromatography. The molecular weights of these subpeptides are determined by FABMS. The peptides that must be sequenced are selected by the molecular weights of these subpeptides and the tetra-S-carboxymethylated Paim I. Third, these subpeptides and the whole protein are sequenced by automated Edman degradation. Finally, the primary structure of tetra-S-carboxymethylated Paim I is confirmed by the combination of tryptic, chymotryptic, and S. aureus V8 protease digestion and FABMS. The sequence of Paim I is compared with those of Haim II, Hoe-467A, Z-2685, and AI-3688 because they have different alpha-amylase inhibition spectra against mammalian alpha-amylases but belong to a family of related proteins.

Amino Acid Sequence↗
PubMed1987

Characterization of disulfide bonds in recombinant proteins: reduced human interleukin 2 in inclusion bodies and its oxidative refolding.

Cloned cDNA of human interleukin 2 (IL-2) was expressed in Escherichia coli cells in which IL-2 formed insoluble inclusion bodies. Human IL-2 has three Cys residues, namely, Cys-58, Cys-105, and Cys-125, and native IL-2 has an intramolecular disulfide bond between Cys-58 and Cys-105. Since the formation of inclusion bodies was thought to be due to disorder in the oxidation state of these Cys residues, all intramolecular disulfide bond isomers of IL-2 were prepared by denaturation of native IL-2 to characterize the state of a disulfide bond in IL-2 in the inclusion bodies. These isomers can be separated from native IL-2, reduced IL-2, and IL-2's with intermolecular disulfide bonds by means of reversed-phase high-performance liquid chromatography. Human IL-2 produced in inclusion bodies in E. coli carrying a recombinant DNA was analyzed by HPLC and was proved to be a fully reduced form with no intra- and intermolecular disulfide bonds. Refolding of reduced IL-2 in the presence of reduced and oxidized glutathione and a low concentration of guanidine hydrochloride resulted in the formation of the biologically active IL-2 quantitatively. Further purification provided a practically pure IL-2 preparation without contamination of any disulfide bond isomers.

Amino Acid Sequence↗
PubMed1987

Crystallization and preliminary X-ray studies of human recombinant interleukin-2.

Two different forms of crystals (potentially) suitable for x-ray structure analysis were obtained for recombinant human interleukin-2 (IL-2) using ammonium sulfate as a precipitant in the pH range of 6.3-7.3 (in the case of hexagonal bipyramidal crystals) and 4.5-5.5 (in the case of plate crystals). The hexagonal bipyramidal crystal belongs to a hexagonal space group P6(2)22 or P6(4)22 with a = b = 105.8 A and c = 122.2 A. The crystal diffracts up to 3.4 A resolution and contains 2 or 3 IL-2 molecules in an asymmetric unit. The plate crystal belongs to an orthorhombic space group P2(1)2(1)2 with a = 47.9 A, b = 79.6 A, and c = 31.9 A. The crystal diffracts up to 2.5 A resolution and contains only 1 IL-2 molecule in an asymmetric unit. These facts reconfirmed crystallographically the high homogeneity of the present preparation of human recombinant IL-2.

Cloning, Molecular↗
PubMed1987

Purification and properties of a pepstatin-insensitive carboxyl proteinase from a gram-negative bacterium.

A carboxyl proteinase was found in the culture filtrate of a Gram-negative bacterium. The optimum for the action of the purified enzyme was approx. pH 3 and its caseinolytic activity was not inhibited by carboxyl proteinase inhibitors, such as pepstatin, Streptomyces pepsin inhibitor and diazoacetyl-DL-norleucine methyl ester. 1,2-epoxy-3-(p-nitrophenoxy)propane modified the enzyme with concomitant loss of its enzyme activity. The enzymatic and physicochemical properties of the enzyme were compared with those of known pepstatin- and diazoacetyl-DL-norleucine methyl ester-insensitive carboxyl proteinases previously reported. To our knowledge, this is the first carboxyl proteinase isolated from bacteria.

Amino Acids↗
PubMed1987

Determination of chinoform in biological fluids and nervous tissues of the dog by gas chromatography-mass spectrometry.

A sensitive gas chromatographic-mass spectrometric method for the determination of 5-chloro-7-iodo-8-hydroxyquinoline (chinoform, clioquinol) in biological fluids and nervous tissues is described. Chinoform was converted into the pentafluorobenzyl ether, which was separated on a 10% Dexsil 300GC column and determined by the use of chinoform-d4 as an internal standard. The clean-up of chionoform in plasma and urine was efficiently achieved by extracting with benzene, while the drug in the tissue was pretreated successively by extraction with 12.5% v/v pyridine-benzene, separation on a Clin-Elut cartridge and adsorption on alumina. The quantitation limit of chinoform was 100 pg, and the recovery rates of chinoform added to plasma and tissue were 98% and 92%, respectively. The chinoform levels in biological fluids and tissues in dogs after prolonged administration of the drug at a dose of 400 mg/kg/day were measured by the proposed method. The plasma level and tissue distribution of chinoform are also discussed.

Animals↗
PubMed1985

Verification by mass spectrometry of the primary structure of human interleukin-2.

Proteolytic digests of interleukin-2 from a human leukemic T-cell line produced by Escherichia coli carrying a recombinant DNA were analyzed by fast atom bombardment mass spectrometry. The mass values of intense signals observed in the mass spectrum were consistent with peptides predicted from the nucleotide sequence of cDNA for human interleukin-2, an indication that the protein with the predicted amino acid sequence was produced by E. coli. BrCN and proteolytic digests of interleukin-2 obtained from cultured cells were also examined by fast atom bombardment mass spectrometry. The observed mass values were identical with those from interleukin-2 from E. coli except for that of the NH2-terminal sequence, in which the Thr residue at position 3 was bound to a sugar moiety. The mass spectra of the digests of the two interleukin-2 preparations and synthetic peptides with sequences from 117 to 128 and 121 to 128 predicted from the nucleotide sequence of cDNA for a human interleukin-2 indicated that Cys residues at positions 58 and 105 are linked by a disulfide bond and that the Cys residue at position 125 is free.

Amino Acid Sequence↗
PubMed1982

Determination of captopril and its disulphide in biological fluids.

A gas chromatographic-mass spectrometric method for the simultaneous determination of captopril (SQ 14,255) and its disulphide (SQ 14,551) in biological fluids by means of selected ion monitoring is described. In order to prevent oxidative degradation, captopril was treated with N-ethylmaleimide (NEM). The captopril-NEM adduct and the disulphide were converted into the hexafluoroisopropyl esters, which were separated on a 10% Dexsil 300 GC column and determined by employing the captopril-N-butylmaleimide adducts as an internal standard. The blood and urine levels of captopril and its disulphide in dogs to which captopril had been administered orally were measured by the proposed method. The urinary excretion of these two substances in rats was also determined in a similar manner.

Animals↗
PubMed1981

Characterization of aminoindamines and aminoindoanilines formed by oxidative hair dyeing and their mutagenicity.

2-Amino-5-methoxy-2'(or 3')-methylindamine and 2-amino-5-methoxy-2'(or 3')-methylindoaniline were isolated from a coloring matter formed by oxidative condensation of 2,5-diaminotoluene with 2,4-diaminoanisole, and their structures were elucidated on the basis of nuclear magnetic resonance and mass spectral data. These two main components of the oxidation product formed at the early stage exhibited a positive result in the mutagenicity test on the thin-layer chromatography plate. The mutagenic activities of purified aminoindamines and aminoindoanilines against Salmonella typhimurium TA 98 were as strong as that of 2-acetamidofluorene. It was also demonstrated that 5-methoxy-2'(or 3')-methylindamine was formed in 10% yield under the conditions used for hair dyeing and the yield was dependent upon the molar ratio of 2,5-diaminotoluene to 2,4-diaminoanisole.

Aniline Compounds↗
PubMed1980

Determination of captopril in biological fluids by gas-liquid chromatography.

The quantitation of captopril in biological fluids by gas-liquid chromatography using a flame photometric detector is described. Captopril was converted into an adduct with N-ethylmaleimide and then into the hexafluoroisopropyl ester. The latter derivative was separated on a 2% OV-210 column and determined by employing the captopril-N-hexylmaleimide adduct as an internal standard. The blood level and urinary excretion of captopril administered intravenously to dogs were measured by the proposed method.

Animals↗
PubMed1980

Toxicity and reproduction studies of ceftizoxime sodium.

Sodium (6R,7R)-7-[(Z)-2-(2-amino-4-thiazoyl)-methoxyiminoacetamido]-8-oxo-5-thia-1-azabicyclo[4,2,0] oct-2-ene-2-carboxylate (ceftizoxime sodium), a new semisynthetic cephalosporin derivative, was tested for acute toxicity in various laboratory animal species, nephrotoxicity in rabbits, subacute and chronic toxicity in rats and dogs, and effect on fertility and teratogenicity in rats and rabbits. The i.v. LD50 values of ceftizoxime sodium in mice and rats were around 6000 mg/kg, and no deaths occurred in dogs after the largest dose of 3200 mg/kg. There was no evidence of nephrotoxicity of ceftizoxime sodium in rabbits after an i.v. dose of 1000 mg/kg. Clear-cut changes in subacute and chronic toxicity studies of ceftizoxime sodium were local damage at the injection site and its secondary reactions, although reversible peripheral anemia was observed in one female dog given 1000 mg/kg i.v. In the reproduction studies, ceftizoxime sodium had no adverse effects on fertility or fetal development in rats or rabbits.

Animals↗