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Biomedical subjects

A Negami

Publications and source records attributed to A Negami.

11 recordsLinked to original sources
PubMed1996

In vitro development of bovine embryos in conditioned media from bovine granulosa cells and vero cells cultured in exogenous protein- and amino acid-free chemically defined human tubal fluid medium.

We have investigated the effect of protein- and amino acid-free simple human tubal fluid (HTF) medium conditioned with bovine granulosa cells (BGC) or Vero cells on the development of early bovine embryos to the blastocyst stage. Serum-containing medium (SCM) and serum-free medium (CM) conditioned by BGC (BGC-SCM, BGC-CM) and by Vero cells (VC-SCM, VC-CM) were prepared. Early embryos (1-cell stage and 5- to 8-cell stage) were obtained by in vitro maturation and fertilization of oocytes from slaughtered cows. Embryos were randomly divided into 7 culture groups as follows: culture with BGC-SCM, BGC-CM, VC-SCM, or VC-CM; coculture with BGC or Vero cells; or culture with fresh HTF medium without serum. The proportion of 5- to 8-cell embryos developing to the blastocyst stage in BGC-CM (16%) and VC-CM (12%) was significantly lower (p < 0.05) than in BGC-SCM (41%) and in VC-SCM (29%) and after coculture with BGC (48%) and Vero cells (30%). Similarly, the percentages of 1-cell embryos developing to blastocyst in BGC-CM and VC-CM were significantly lower than in BGC-SCM and VC-SCM and after coculture. Cell numbers per blastocyst developed from 5- to 8-cell embryos in BGC-CM (96.8 cells) and in VC-CM (94.0 cells) were somewhat lower than those in BGC-SCM (128.5 cells) and VC-SCM (117.1 cells) and after coculture with BGC (124.2 cells) and Vero cells (115.3 cells). These results suggest that BGC and Vero cells cultured in a protein- and amino acid-free simple HTF medium synthesize and secrete factor(s) promoting blastocyst formation in vitro. Physiochemical analysis indicated that the embryotrophic substances in BGC-CM were distributed in two molecular size ranges, one between 10 kDa and 30 kDa and another greater than 30 kDa.

Amino Acids↗
PubMed1985

Purification of protein phosphatase from hen oviduct.

Two protein phosphatases of 103 and 29 kDa as determined by gel filtration, were purified from hen oviducts. The 103 -kDa phosphatase was purified 7300-fold to near homogeneity and dissociated into two polypeptides in the presence of SDS. Molecular masses of these polypeptides were estimated to be 60 and 38 kDa by SDS-polyacrylamide slab gel electrophoresis using the buffer system of Laemmli, but 68 and 35 kDa using the buffer system of Weber and Osborn. The stoichiometry of these polypeptides was approx 1:1 according to the densitometric analysis of gels at 550 nm. The 29 -kDa phosphatase was purified 2900-fold. Both phosphatases dephosphorylated the alpha-subunit of phosphorylase kinase more rapidly than the beta-subunit.

Animals↗
PubMed1985

Calcium- and calmodulin-dependent phosphorylase kinase activity in porcine uterine smooth muscle.

Porcine uterine smooth muscle phosphorylase kinase has been partially purified. The enzyme was activated about 1.5-2.0-fold by exogenous calmodulin. Half maximal stimulation was observed at about 100 nM calmodulin. The activation was dependent on calcium and was maximum at pH 7.5 in the range of pH from 6 to 9. This activation was completely abolished by 100 microM trifluoperazine. The result suggested that unlike slow and cardiac muscles, phosphorylase kinase of uterine smooth muscle showed similar response to calmodulin with that of fast muscle. The physiological role of the calcium and calmodulin-dependent activation of myometrium phosphorylase kinase is briefly discussed.

Animals↗
PubMed1985

Comparison of enzyme activities on glycogen metabolism in rabbit slow and fast muscles.

Activities of glycogen synthase (total) and branching enzyme in slow (soleus) muscle are higher than those in fast (vastus lateralis) muscle, while those of phosphorylase kinase (total), phosphorylase (total) and debranching enzyme are reversed. The active form ratio of glycogen synthase is higher in fast muscle, while those of phosphorylase kinase and phosphorylase are higher in slow muscle. Activities of cAMP-dependent protein kinase and protein phosphatase in slow muscle are higher than those in fast muscle. These results suggest that glycogen metabolizing enzymes in slow muscle, distinct from those in fast muscle, are regulated more strongly by cAMP-dependent protein kinase rather than by protein phosphatase.

Animals↗
PubMed1985

Stimulation of autophosphorylation of rabbit skeletal muscle phosphorylase kinase by glycogen synthase on glycogen particles.

Glycogen synthase stimulated the autophosphorylation and autoactivation of phosphorylase kinase from rabbit skeletal muscle. This stimulation was additive to that by glycogen and the reaction was dependent on Ca2+. The effect by glycogen synthase was maximum within the activity ratio (the activity of enzyme without glucose-6-P divided by the activity with 10 mM glucose-6-P) of 0.3 and over 0.3 it was rather inhibitory. The results suggest that autophosphorylation of phosphorylase kinase in the presence of glycogen synthase on glycogen particles may be an important regulatory mechanism of glycogen metabolism in skeletal muscle.

Animals↗
PubMed1984

Phosphorylation of myelin basic protein by glycogen phosphorylase kinase.

The ability of homogeneous glycogen phosphorylase kinase (Phk) from rabbit skeletal muscle to phosphorylate bovine brain myelin basic protein (MBP) was investigated. Phk could incorporate a maximum of 1.9 mol phosphate/mol MBP. The apparent Km and Vmax for Phk phosphorylation of MBP were 27 microM and 90 nmol/min per mg enzyme, respectively. Properties of MBP phosphorylation by Phk are similar to those of phosphorylase as a substrate. Only serine residues of MBP are phosphorylated by Phk. Phosphorylation sites of MBP by Phk are not identical to those by cAMP-dependent protein kinases.

Animals↗
PubMed1984

Two diverse effects of poly(L-lysine) on rabbit skeletal muscle phosphorylase kinase: stimulation of autophosphorylation and inhibition of its activity.

Polylysine greatly stimulated the autophosphorylation of phosphorylase kinase from rabbit skeletal muscle. When fully autophosphorylated, about 14 mol of phosphate per tetramer (alpha beta gamma delta) were incorporated in the presence of polylysine, which was twice as much as those observed without polylysine. In contrast to this stimulatory effect of polylysine on the autophosphorylation, polylysine strongly inhibited the conversion reaction of phosphorylase b to a. The inhibition is competitive with a Ki of 2.3 micrograms/ml. No effects of polylysine were observed on the activities of phosphorylase and cAMP-dependent protein kinase.

Animals↗
PubMed1983

Calcium--calmodulin-dependent activation of porcine liver phosphorylase kinase.

Porcine liver phosphorylase kinase was activated about 1.5-fold by calmodulin in a calcium-dependent manner. Half-maximal stimulation was observed at about 80 nM calmodulin and the activation was almost pH-independent. The specific binding of porcine liver phosphorylase kinase to calmodulin--Sepharose affinity column exhibited an absolute dependence upon the presence of calcium. The physiological role of the calmodulin-dependent activation for liver phosphorylase kinase is discussed.

Animals↗