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Biomedical subjects

N Akamatsu

Publications and source records attributed to N Akamatsu.

At least 127 records · Page 7Linked to original sources
PubMed1982

UDP-N-methyl-D-glucosamine-phosphate--a possible intermediate of N-methyl-L-glucosamine moiety of streptomycin.

The formation of N-methyl-L-glucosamine moiety of streptomycin from D-glucosamine by Streptomyces griseus was studied. The addition of thymine to the culture medium stimulated the formation of streptomycin and the incorporation of D-glucosamine into N-methyl-L-glucosamine moiety. During a study of sugar nucleotides in the mycelia, a novel UDP-amino sugar was isolated. The compound was formed before the maximum production of streptomycin. It was UDP-N-methyl-D-glucosamine-phosphate.

Biotransformation↗
PubMed1982

Morphologic transformation and chromosomal changes induced by chemical carcinogens in skin fibroblasts from patients with familial adenomatosis coli.

Skin fibroblasts from patients with familial adenomatosis coli (AC) and normal individuals were treated once with the carcinogen 4-nitroquinoline 1-oxide or N-methyl-N'-nitro-N-nitrosoguanidine and then passaged sequentially. Morphologically altered cells appeared in the cultures of carcinogen-treated AC fibroblasts at passages 6-8 (days 100-140) after treatment with the carcinogens, but carcinogen-treated normal cells and untreated AC and normal cells did not become altered even after cultivation for 25 passages. The cultures containing morphologically altered cells showed characteristics of transformed cells, such as a high frequency of colony formation in soft agarose, increased growth ability, and chromosomal abnormalities. The results suggest tha AC patients have increased susceptibility to morphologic transformation and chromosomal changes induced by chemical carcinogens.

4-Nitroquinoline-1-oxide↗
PubMed1981

[Ultrasound irradiation effects on pre-implantation embryos (author's transl)].

To elucidate ultrasound irradiation effect on pre-implantation embryos, its mechanism and safety levels of ultrasound intensity, I had performed ultrasound irradiation and thermal experiments on pre-implantation embryos. The pre-implantation embryos, whose stages were late morula on early blastocyst, were located in the centre of ultrasound beam certainly by using closed microdroplet culture. Experiments were done under various conditions of ultrasound intensity, irradiation time and temperature of circumference. The statistically significant increase of morphological abnormality was observed when 3.0 W/cm2 continuous wave for 60 minutes of 0.65, 1.0 or 1.8 W/cm2 continuous wave for 720 minutes was irradiated. The statistically significant developmental retardation was observed when 2.0 or 3.0 W/cm2 continuous wave for 60 minutes or 0.65, 1.0 or 1.8 W/cm2 continuous wave for 720 minutes was irradiated. Pulsed ultrasound irradiated groups showed neither increase of morphological abnormality nor developmental retardation significantly. The reading of thermistor sonde located in the centre of beam was raised during irradiation. No significant change were observed between warming and irradiated groups, temperature of which were similarly raised. Similar results were seen when 3.0 W/cm2 continuous wave for 60 minutes were irradiated during cool circumference, in which temperature of the centre of ultrasound beam didn't raise more than 37 degrees C. These results suggest that thermal effect of ultrasound is most effective during various effects including cavitation in this study.

Animals↗
PubMed1980

Metabolism of sialic acid in regenerating rat liver.

In regenerating rat liver slices 24 h after partial hepatectomy, the incorporation of [1-14C]glucosamine into 'free sialic acid' (N-acetylneuraminic acid + CMP-N-acetylneuraminic acid) decreased to below 50% of the control values and the incorporation into protein-bound sialic acid decreased to the same extent. The incorporation of [14C]glucosamine into 'free sialic acid' decreased during the period from 6 to 47 h after hepatectomy, showing a minimum at 12 h, and recovered to the control value by 96 h. At 12 h, the activities of UDP-N-acetylglucosamine 2-epimerase (UDP-2-acetoamido-2-deoxy-D-glucose 2-epimerase, EC 5.1.3.14) and N-acyl-D-mannosamine kinase (ATP: 2-acylamino-2-deoxy-D-mannose 6-phosphotransferase, EC 2.7.1.60) in the liver were significantly decreased. The amount of protein-bound sialic acid in the liver was not changed after partial hepatectomy, but the amount in plasma was changed, with a similar pattern to that of the incorporation of [14C]glucosamine into slice 'free sialic acid'. These results indicate that the synthesis of sialic acid in the liver much decreases in the early stage of regeneration and that this may be correlated with the decreased synthesis of plasma sialoglycoproteins.

Animals↗
PubMed1980

Increased sensitivity of fibroblasts of skin from patients with adenomatosis coli and Peutz-Jegher's syndrome to transformation by murine sarcoma virus.

Skin fibroblasts from family members of cases of adenomatosis coli (AC) and Peutz-Jegher's syndrome (PJ) were examined for susceptibility to morphological transformation by Moloney murine sarcoma virus (MSV) of rate 78AI cells, which was found in the present study to contain both dualtropic and ecotropic murine leukemia virus (MLV). The fibroblasts from individuals with manifest AC (22 subjects) and manifest PJ (5 subjects) were up to 5 times more susceptible to transformation by rat 78AI-MSV(MLV) than those from normal individuals (7 subjects). Nonmanifest members of AC families (8 subjects) showed various sensitivities: the fibroblasts from 3 family members had a sensitivity as low as that of normal cells, and those of 5 individuals exhibited increased sensitivity similar to that of manifest cases of AC. The AC and PJ cells that were sensitive to 78AI-MSV(MLV) were also susceptible to transformation by other pseudo-types of Moloney MSV, although they were not transformed by infection of standard Moloney MSV. None of the fibroblasts were transformed by xenotropic MLV alone. The tumor promoter 12-O-tetradecanoyl phorbol-13-acetate enhanced transformation by 78AI-MSV(MLV) in both AC and normal cells.

Adenoma↗
PubMed1979

Mutagenicity of metal cations in cultured cells from Chinese hamster.

The mutations at the hypoxanthine-guanine phosphoribosyl transferase (HGPRTase) locus in Chinese hamster V79 cells induced by metal cations were examined by the development of resistance to 8-azaguanine (8AG). The spontaneous frequency of 8AG resistance was 5.8 per 10(6) cells, and the frequency was enhanced to 2-6 times that of the control by treatment of cells with the chlorides of beryllium and manganese. About 75% of 8AG-resistant colonies were sensitive to amethopterin, and 86% of the resistant colonies showed less than 3% of the HGPRTase activity of the wild-type cells. The mutant frequency in cultures treated with cobalt and nickel chlorides were slightly increased, and mutation induction was only detectable at very low rates of cell survival.

Animals↗
PubMed1979

Hexokinase of Angiostrongylus cantonensis: presence of a glucokinase.

1. Angiostrongylus cantonensis contains a glucokinase which was isolated by DEAE-cellulose column chromatography. 2. This enzyme has a much higher affinity toward glucose (apparent Km, 0.2 mM) than fructose (apparent Km, 85 mM). Glucose-6-phosphate (10 mM) does not inhibit glucose phosphorylation. 3. Molecular weight obtained by a molecular sieve chromatography (60,000) is also close to the value of mammalian glucokinase. 4. While Vmax value for mannose is one-third smaller than that for glucose, Km for mannose is rather lower than that for glucose. 5. In addition to the cytosol enzyme, a particle bound hexokinase is found in the worm.

Angiostrongylus↗
PubMed1978

UDP-N-acetylglucosamine-glycoprotein N-acetylglucosaminyltransferase in regenerating rat liver.

The assay condition for N-acetylglucosaminyltransferase activities in rat liver microsomal fraction was developed. The enzyme activities towards endogenous acceptors within 48 h after partial hepatectomy were lower than in controls, exceeding the control level by 96 h, and then higher than in controls up to 240 h after the operation. The changes in N-acetylglucosaminyltransferase activities towards exogenous acceptor (UDP-2-acetamido-2-deoxy-D-glucose: glycoprotein 2-acetamido-2-deoxy-D-glucosyltransferase, EC 2.4.1.51) were consistent with those in the enzyme activities towards endogenous acceptors at 144 h, but not at 48 h, after the operation. The contents of protein and the levels of protein-bound hexosamine in the liver microsomes were decreased at early period of liver regeneration. These results suggest that the acceptor capacity of liver microsomal proteins is diminished during first 48 h of the regeneration. This may be responsible for the decreased transfer of the amino sugar to nascent glycoproteins. However, the enzyme activity was enhanced at 144 h and the level of endogenous acceptors may increase.

Animals↗
PubMed1977

Biosynthesis of N-methyl-L-glucosamine from D-glucose by Streptomyces griseus.

Biosynthesis of N-methyl-L-glucosamine moiety of streptomycin from D-glucose by Streptomyces griseus was studied. A mixture of D-[1-(14) C] glucose and D-[6(-3)H]glucose was given to the culture of S. griseus. The 3H/14C ratio found in N-methyl-L-glucosamine further supports a mechanism that the conversion of D-glucose to L-hexose is carried out without scission of carbon skeleton. When D-[1-14C]glucose and D-[3-3H]glucose were used, the fall of 3H/14C ratio in N-metyl-L-glucosamine showed that the hydrogen atom at C-3 plays a rôle in such a transformation.

Glucosamine↗