Search PubMed⌕ Search

Biomedical subjects

M Fukunaga

Publications and source records attributed to M Fukunaga.

At least 415 records · Page 23Linked to original sources
PubMed1981

[Studies on the measurement of vitamin D derivatives in human plasma. I. A competitive protein binding assay for 25-hydroxyvitamin D in plasma (author's transl)].

A simple and precise method has been developed for the determination of 25-hydroxyvitamin D in 1 ml of human plasma. The method consists of methanol/chloroform extraction, purification by high pressure liquid chromatography and a competitive protein binding assay using vitamin D deficient rat serum. The ethanol extract from vitamin D deficient chick serum was added to the sample before CPBA to eliminate the non-specific interference in the CPBA system as a vitamin D free serum extract. The assay was sensitive to 0.72 ng/ml of plasma. Satisfactory results were obtained in the dilution and recovery tests. The coefficients of variation were 5.8 approximately 9.1% for the within-assay, and 7.4 approximately 10.3% for the between-assay. Plasma concentrations of 25-hydroxyvitamin D in 46 samples of normal human plasma were 21 +/- 10.5 ng/ml (mean +/- SD), and the seasonal variation was demonstrated. Plasma levels for 25-hydroxyvitamin D were high in patients receiving vitamin D2 and low in patients suffering from liver cirrhosis.

25-Hydroxyvitamin D 2↗
PubMed1981

Comparison of petite induction in yeast by acridines, ethidium and their photoaffinity probes.

The production of petite mutations by different acridine analogs was studied in Saccharomyces cerevisiae. Compounds with amino substituents at the 2 and 3 positions of the acridine nucleus and methylation at position 10 were effective for petite induction in growing cells but not in resting cells, while those with chloro, nitro and methoxy substituents were not effective in either resting or growing cells. Photosensitive azido derivatives of the acridines were tested to evaluate the role of covalent drug attachment for mutagenesis in resting cells. Photolysis of resting cells with 9-axido, 3-azido-6-amino-, 9-azido-10-methyl-, or 3-azido-6-amino-10-methyl-acridine was highly toxic. 3-Azido-6-amino-acridine, and especially 3-azido-10-methyl-, and 3-azido-6-amino-10-methyl-acridine, were effective petite inducers in resting cells. Thus, the photosensitive (azido) group at position 9 produced only cell killing while the azido group at position 3 and/or 6 led to effective petite induction in resting cells. In contrast, petite induction was observed only for growing cells, for dark control experiments with these compounds or with the monoazide precursor compounds.

Acridines↗
PubMed1981

Induction of petite "mutants" in an ethidium-resistant strain of Saccharomyces cerevisiae by photoaffinity labeling. Distinction between early and late steps.

A strain of Saccharomyces cerevisiae (MH41-7B/011) was resistant to petite induction by ethidium bromide at 30 degrees, but was sensitive to induction by photolabeling with ethidium monoazide. These results suggested a defect in the mutant in metabolic activation of ethidium to account for its resistance. Synchronized cultures of both the mutant and the normal parent strains showed a substantial reduction in petite response to photolabeling in stationary phase cells which could not be accounted for by changes in cell penetration of the drug. The use of photolabeling with normal and mutant cells suggested that petite induction can be divided into early and late steps.

Drug Resistance, Microbial↗
PubMed1981

Plasmid deoxyribonucleic acid and translucent-to-opaque variation in Mycobacterium intracellulare 103.

After treatment with mitomycin D and other antibacterial agents, a translucent, smooth-colony-forming mycobacterium, isolated from sputum and designated as Mycobacterium intracellulare strain 103, gave rise to variants forming opaque colonies. These opaque variants were more sensitive streptomycin, kanamycin, viomycin, and rifampin than were the wild-type translucent variants. Plasmid deoxyribonucleic acids taken from translucent strain cells and from cells of certain opaque variants were analyzed by agarose gel electrophoresis. Two plasmids of molecular weights of approximately 2 x 10(6) and 50 x 10(6), respectively, were found in the wild-type translucent cells; one of them, the 2 x 10(6)-molecular-weight plasmid, was always missing from deoxyribonucleic acids of the opaque variant cells. The results suggested that translucent colonial appearance and antibiotic resistance of the strain are plasmid-determined functions.

Anti-Bacterial Agents↗
PubMed1981

Adenylate cyclase activation and competitive binding with renal tissue using synthetic eel calcitonin analog and its fragments.

The structure-function relationship of calcitonin (CT) was investigated using a synthetic eel CT (E-CT) analog and its fragments. Adenylate cyclase activation and competitive binding to rat renal receptors were used as parameters of function. [Asu1,7]E-CT analog, synthesized by replacing the S-S bond of Cys1-Cys7 in the natural hormone with ethylene linkage of 1-amino suberic acid (Asu), and E-CT fragment 11-32 had about 1/5th and 1/50th the potencies of synthetic E-CT, respectively, in both adenylate cyclase activation and competitive inhibition of 125I-labeled [Asu1,7]iodo-E-CT binding on rat renal plasma membranes. The minimal chain length required to activate adenylate cyclase in rat renal plasma membranes was between 12-18 amino acids, and the minimal chain length required to affect the CT receptor binding was between 6-12 amino acids, near the C-terminus. Fragments, including the C-terminus, show a disproportionate and potent inhibition of the binding compared with the potency required for adenylate cyclase activation. Thus, the amino acid sequence near the C-terminus probably plays an important role in the binding of CT to the receptor. (Endocrinology 108: 698, 1981.)

Adenylyl Cyclases↗
PubMed1981

Fat-storing cells (Ito's cell) of human liver. Biological characteristics and changes occurring in circulatory disturbance.

An enzyme histochemical study was carried out on fat-storing cells, which are distributed in the space of Disse of mammalian liver. The livers used for study consisted of human autopsy materials demonstrating either acute or chronic circulatory disturbance. Fat-storing cells contain abundant glycogen, and demonstrate a marked gamma-glutamyl transpeptidase activity and a weak lactate dehydrogenase activity. It is highly probable that an active glyconeogenesis rather than glycogenolysis is being carried out in these cells. In acute circulatory disturbance, an elevated alkaline phosphatase activity is found in the wall of sinusoids. This phenomenon is a manifestation of activated capillary endothelial cells participating in the regeneration of liver parenchyma. On the other hand, in chronic congestive liver, elevated gamma-glutamyl transpeptidase activity in fat-storing cells is concerned in the proliferation of fibers in the wall of sinusoids, and elevated pressure in sinusoids is considered to be the main factor in its increased activation.

Adult↗