Search PubMed⌕ Search

Biomedical subjects

N Katoh

Publications and source records attributed to N Katoh.

At least 199 records · Page 11Linked to original sources
PubMed1985

Inhibition by gossypol of phospholipid-sensitive Ca2+-dependent protein kinase from pig testis.

Gossypol, a polyphenolic binaphthalene-dialdehyde extracted from cotton plants which possesses male antifertility action in mammals, is a potent inhibitor of phospholipid-sensitive Ca2+-dependent protein kinase from pig testis. Gossypol inhibited Ca2+-dependent activity of the enzyme without affecting its basal activity. The IC50 value (concentration causing 50% inhibition) was 31 microM when lysine-rich histone was used as substrate. Kinetic analysis indicated that the compound inhibited the enzyme non-competitively with respect to ATP (Ki = 31 microM) or lysine-rich histone (Ki = 30 microM), and competitively with respect to phosphatidylserine (Ki = 2.1 microM). With Ca2+, irrespective of the presence or absence of 1,3-diolein, the compound lowered Vmax and increased the apparent Ka for Ca2+. The compound also inhibited phosphorylation by the enzyme of high-mobility-group 1 protein (one of the endogenous substrates in the testis for the enzyme located in nucleosome), with an IC50 value of 88 microM. These results suggested that a phospholipid-sensitive Ca2+-dependent protein phosphorylation system in the testis is involved in the regulation of spermatogenesis.

Animals↗
PubMed1985

Phosphorylation of high mobility group 1 protein by phospholipid-sensitive Ca2+-dependent protein kinase from pig testis.

Phospholipid-sensitive Ca2+-dependent protein kinase was partially purified from total particulate fraction of pig testis. The enzyme phosphorylated high mobility group 1 protein (HMG 1), one of the major chromatin-associated non-histone proteins. Other HMG proteins (HMG 2, 14 and 17) were not phosphorylated by the enzyme. Exhaustive phosphorylation of HMG 1 revealed that 1 mol of phosphate was incorporated/mol of HMG 1. The apparent Km value for HMG 1 was 3.66 microM. 1,3-Diolein stimulated the phosphorylation at 10 microM-Ca2+ in the presence of phosphatidylserine. The phosphorylation of HMG 1 was inhibited by adriamycin, an inhibitor of spermatogenesis.

Animals↗
PubMed1985

Effects of heparin and polyamines on the phosphorylation of high mobility group proteins by cyclic nucleotide-independent phosvitin kinase from pig testis.

In order to study the physiological role played by cyclic nucleotide-independent phosvitin kinase in pig testis, effects of heparin (an inhibitor of RNA synthesis) and polyamines (stimulators of the synthesis) on the enzyme, distribution in nuclei of the enzyme, and identification of endogenous substrates for the enzyme were examined. The enzyme was shown to be inhibited by heparin, nd the inhibition was removed by the addition of polyamines, when phosvitin (the best exogenous substrate for the enzyme) was used as substrate. The inhibition by heparin and inhibition removal by polyamines was dependent on Mg2+ concentration. The enzyme was found to be present in pig testis nuclei as well as in the cytosol. The enzyme phosphorylated chromatin-associated non-histone proteins in the testis nuclei. Of the non-histone proteins, high mobility group (HMG) 14 and 17 were identified as substrates for the enzyme. Phosphorylation of HMG 14 and 17 was also inhibited by heparin and inhibition of HMG 14 phosphorylation was removed by the addition of polyamines, although the effect was less dependent on Mg2+ concentration. These results suggested that phosvitin kinase was involved in the regulation of RNA synthesis int he testis.

Animals↗
PubMed1985

Translocation of phospholipid-sensitive Ca2+-dependent protein kinase and its substrate, Mr 38,000 protein, in chronic myelocytic and acute myelocytic leukemias.

Phospholipid-sensitive Ca2+-dependent protein kinase (PL-Ca-PK) and its substrates were investigated in neutrophils from normal subjects and in chronic myelocytic and acute myelocytic leukemic cells from patients with or without treatment for leukemia. PL-Ca-PK and its substrates were found in total particulate fraction of normal neutrophils, but less in cytosol. In leukemic cells from chronic myelocytic leukemia patients without treatment, PL-Ca-PK and its substrate, Mr 38,000 protein, increased in cytosol but decreased in total particulate fraction as compared with normal neutrophils. In leukemic cells obtained from chronic myelocytic leukemia patients after treatment mainly with busulfan, PL-Ca-PK and Mr 38,000 protein were increased in total particulate fraction but decreased in cytosol. Using leukemic cells from acute myelocytic leukemia patients with or without treatment, similar results were obtained. The change of localization of PL-Ca-PK and Mr 38,000 protein in leukemic cells appeared to be correlated to the increase or decrease of the number of leukemic cells. These results suggested that PL-Ca-PK together with the substrate, Mr 38,000 protein, might be translocated from total particulate fraction to cytosol with the onset of leukemia, and from cytosol to total particulate fraction accompanying treatment for leukemia.

Cell Division↗
PubMed1984

Phospholipid-sensitive Ca2+-dependent protein kinase system in testis: localization and endogenous substrates.

The presence and localization in pig and rat testes of phospholipid-sensitive Ca2+-dependent protein kinase (PL-Ca-PK) and its substrates were investigated. PL-Ca-PK activity was found in the testis total particulate fraction and epididymal fluid, but little in the testis total particulate fraction and epididymal fluid, but little in the testis cytosol and matured spermatozoa obtained from the epididymis. Similarly, at least three endogenous substrates (83,000, 33,000, and 26,000) and five substrates (greater than 100,000, 83,000, 60,000, 43,000, and 19,000) for PL-Ca-PK were detected in the testis total particulate fraction and the epididymal fluid, respectively, but little or no substrates were observed in the testis cytosol and matured spermatozoa. The three substrates detected in the total particulate fraction were also observed in the testis nuclear fraction. In rat testis, PL-Ca-PK activity was detected in the total particulate fraction of germ cells. The results suggested that PL-Ca-PK system might be important in membrane- or subcellular organellar-associated functions in testis.

Animals↗
PubMed1984

[A case of thyroid carcinoma with temporal bone metastasis].

A 34-year-old female who had received left hemi-thyroidectomy because of carcinoma of the thyroid complained of progressive deafness 5 years postoperatively. A red pulsating tumor was found in her mid-ear; it was removed incompletely. The tumor was diagnosed as a glomus jugulare tumor. The patient died at age 47 due to tumor progression. Autopsy revealed a temporal bone tumor with brain invasion; histological examination confirmed it to be a metastasis from the thyroid carcinoma. Clinical and histological details of this rare case are reported and the relevant literature is reviewed.

Adult↗
PubMed1983

Purification and properties of cyclic nucleotide-independent phosvitin kinase from pig testis.

Cyclic nucleotide-independent and Ca2+-independent phosvitin kinase was purified from pig testis to apparent homogeneity by DEAE-cellulose, Sephadex G-200 chromatography, followed by subsequent DEAE-cellulose chromatography and phosvitin-Sepharose 4B affinity chromatography. The purified enzyme was homogeneous by analytical polyacrylamide gel electrophoresis, and it consisted of two polypeptides with molecular weights of 92000 (alpha) and 84000 (beta), which were present in the ratio of 1:2. Molecular weight of the native enzyme was estimated at 240000 by gel chromatography on Sepharose 6B, suggesting that the enzyme consists of alpha beta 2. The enzyme had maximal activity with phosvitin as the substrate. Casein was less active than phosvitin. Histone, protamine and myosin light-chains were practically ineffective. The enzyme possessed no ability to autophosphorylate. The apparent Km values were 7.4 microM for phosvitin, 65 microM for ATP and 0.6 mM for Mg2+. Vmax was 2.16 mumol/min per mg. The enzyme was inhibited by ammonium sulfate and heparin, and it was not affected by the addition of cyclic nucleotides and Ca2+ with calmodulin or phospholipid.

Animals↗
PubMed1983

Phosphorylation of cardiac troponin inhibitory subunit (troponin I) and tropomyosin-binding subunit (troponin T) by cardiac phospholipid-sensitive Ca2+-dependent protein kinase.

Cardiac phospholipid-sensitive Ca2+-dependent protein kinase phosphorylated cardiac troponin inhibitory subunit (troponin I) and tropomyosin-binding subunit (troponin T), present either as the free form or as the troponin-tropomyosin complex. Exhaustive phosphorylation of troponin I and of troponin T revealed that 1.7 and 2 mol of phosphate was incorporated/mol of the subunits respectively. Cyclic AMP-dependent protein kinase, though incorporating 0.8 mol of phosphate/mol of troponin I, was unable to phosphorylate troponin T. Phosphorylation of troponin I (apparent Km = 3.4 microM; Vmax. = 2.6 mumol/min per mg of enzyme) or troponin T (apparent Km = 0.3 microM; Vmax. = 0.5 mumol/min per mg of enzyme) by the Ca2+-dependent enzyme was inhibited by various agents, such as adriamycin, palmitoylcarnitine, trifluoperazine, melittin and N-(6-aminohexyl)-5-chloronaphthalene-1-sulphonamide (compound W-7). Ca2+ antagonists (such as verapamil), forskolin and ouabain were ineffective. These findings indicate that troponin I and troponin T were effective substrates for this species of Ca2+-dependent protein kinase, suggesting its potential regulatory role in the contractile activity of myofibrils modulated by troponin.

Animals↗
PubMed1983

Isolation of Clostridium pseudotetanicum from a patient with gas gangrene.

Clostridium pseudotetanicum was isolated along with Serratia marcescens, Proteus mirabilis, and Staphylococcus epidermidis from a patient suffering from gas gangrene who had been injured in the right leg by a power cultivator. Experimental infection of the hind leg of mice with C. pseudotetanicum and the three kinds of aerobic bacteria did not produce any different macroscopic finding in the infection site, compared with aerobic bacterial injection, except for some enlargement of the involved tissue and some slightly altered histolytic findings. Ampicillin, rifampin, and tinidazole were the most active antimicrobial agents against C. pseudotetanicum.

Clostridium↗