Biomedical subjects

Masayoshi Yamaguchi

Publications and source records attributed to Masayoshi Yamaguchi.

79 records · Page 5Linked to original sources

PubMed2002

Role of endogenous regucalcin in nuclear regulation of regenerating rat liver: suppression of the enhanced ribonucleic acid synthesis activity.

The role of endogenous regucalcin in the regulation of ribonucleic acid (RNA) synthesis activity in the nucleus of normal and regenerating rat livers was investigated. Nuclear RNA synthesis was measured by the incorporation of [(3)H]-uridine 5'-triphosphate into the nuclear RNA in vitro. The presence of regucalcin (0.25 or 0.5 microM) in the reaction mixture caused a significant decrease in nuclear RNA synthesis of normal rat liver. alpha-Amanitin (10(-8)-10(-6) M), an inhibitor of RNA polymerase II and III, decreased significantly nuclear RNA synthesis activity. The effect of regucalcin (0.25 microM) in decreasing nuclear RNA synthesis activity was not seen in the presence of alpha-amanitin (10(-6) M). The calcium chloride (10 microM)-increased nuclear RNA synthesis activity was significantly suppressed by the addition of regucalcin (0.25 microM). RNA synthesis activity was significantly enhanced in the nuclei of regenating rat liver obtained at 24, 48, or 72 h after partial hepatectomy. This enhancement was significantly inhibited in the presence of PD98059 (10(-5) M), staurosporine (10(-6) M), or vanadate (10(-3) M). Western analysis of the nuclei of regenerating liver obtained at 24, 48, or 72 h after partial hepatectomy showed a significant increase in regucalcin protein as compared with that of sham-operated rats. The presence of anti-regucalcin monoclonal antibody (25 or 50 ng/ml) in the reaction mixture caused a significant increase in nuclear RNA synthesis activity of normal rat liver. This increase was completely blocked by the addition of regucalcin (1.0 microM). The effect of anti-regucalcin monoclonal antibody (50 ng/ml) in increasing nuclear RNA synthesis activity was significantly enhanced in the nuclei of regenerating liver obtained at 24, 48, or 72 h after partial hepatectomy. This enhancement was significantly suppressed by the addition of alpha-amanitin (10(-6) M), PD98059 (10(-5) M), staurosporine (10(-6) M), or vanadate (10(-3) M) in the reaction mixture. The present study demonstrates that endogenous regucalcin has a suppressive effect on the enhancement of RNA synthesis activity in the nucleus of regenerating rat liver with proliferative cells.

Amanitins↗

PubMed2002

Anabolic effect of phosphogenistein and phosphodaidzein on bone components in rat femoral-metaphyseal tissues in vitro.

The effect of phosphogenistein and phosphodaidzein, which are phosphorylated for the hydroxyl group (OH) at the 7-position of genistein and daidzein, on bone components was investigated. Femoral-metaphyseal tissues obtained from male rats (4 weeks old) were cultured for 24-72 h in Dulbecco's modified Eagle's medium (high glucose, 4.5%) supplemented with antibiotics and bovine serum albumin. The presence of phosphogenistein (10(-5) M) caused a significant increase in calcium content, alkaline phosphatase activity, and deoxyribonucleic acid (DNA) content in bone tissues cultured for 24 h. Phosphodaidzein (10(-5) M) significantly elevated bone calcium and DNA content. These effects were completely prevented by the presence of cycloheximide (10(-6) M), an inhibitor of protein synthesis. When femoral-metaphyseal tissues were cultured for 48 h in the presence of parathyroid hormone (1-34) (PTH; 10(-8) M) or prostaglandin E2 (PGE2; 10(-6) M), bone calcium content was significantly decreased. This decrease was significantly blocked by the presence of phosphogenistein (10(-6) and 10(-5) M) or phosphodaidzein (10(-6) and 10(-5) M). The presence of PTH (10(-8) M) or PGE2 (10(-6) M) caused a significant increase in glucose consumption and lactic acid production by bone tissues. These increases were significantly inhibited by the presence of phosphogenistein (10(-5) M) or phosphodaidzein (10(-5) M), indicating their inhibitory effect on bone resorption. The present study has demonstrated that both phosphogenistein and phosphodaidzein have an anabolic effect on bone metabolism in rat femoral-metaphyseal tissues in vitro.

Alkaline Phosphatase↗

PubMed2002

Suppressive effect of endogenous regucalcin on deoxyribonuclic acid synthesis in the nuclei of rat renal cortex.

The effect of regucalcin, a regulatory protein of Ca2+ signaling, on deoxyribonucleic acid (DNA) synthesis activity in the nuclei isolated from rat renal cortex was investigated. The addition of calcium chloride (10-100 microM) in the reaction mixture containing the nuclei caused a significant decrease in DNA synthesis activity. Nuclear DNA synthesis activity was significantly raised in the presence of EGTA (1 mM), a chelator of Ca2+, indicating that nuclear Ca2+ has an inhibitory effect. Regucalcin (0.1-0.5 microM) added in the reaction mixture in the presence of either EGTA (1 mM) or calcium chloride (50 microM) had a significant inhibitory effect on nuclear DNA synthesis activity. The presence of anti-regucalcin monoclonal antibody (10-50 ng/ml) in the reaction mixture caused a significant increase in DNA synthesis activity. This increase was completely abolished by the addition of regucalcin (0.5 microM). The effect of anti-regucalcin monoclonal antibody in increasing DNA synthesis was enhanced in the presence of EGTA. Additionally, an inhibitory effect of calcium chloride (10 or 50 microM) was enhanced in the presence of anti-regucalcin monoclonal antibody (25 ng/ml). The present study demonstrates that endogenous regucalcin has a suppressive effect on DNA synthesis in the nuclei of rat renal cortex.

Animals↗

PubMed2002

Potential role of regucalcin as a specific biochemical marker of chronic liver injury with carbon tetrachloride administration in rats.

The potential sensitivity of liver specific protein regucalcin as a biochemical marker of chronic liver injury with carbon tetrachloride (CCl4) administration in rats was investigated. CCl4 (10%; 1.0 ml/100 g body wt) was orally given 5 times at 3-day intervals to rats, and the animals were killed by bleeding at 3, 6, 18, and 30 days after the first administration of CCl4. The body weight of rats was significantly lowered 3 and 6 days after CCI4 administration as compared with that of control rats administered with corn oil, and then the weight was restored at 18 and 30 days. Serum glutamate-oxaloacetate transaminase (GOT) and glutamate-pyruvate transaminase (GPT) activities were significantly increased 3 days after the administration, while a significant increase in serum y-glutamyltranspeptidase (gamma-GTP) activity was seen at 3 and 6 days after the administration. Serum GOT, GPT, and gamma-GTP activities were restored to control levels at 18 and 30 days after CCl4 administration. Serum albumin, alpha-fetoprotein, and ammonium levels were not changed by CCl4 administration. Meanwhile, serum regucalcin concentration was markedly increased 3 and 6 days after CCl4 administration, and a significant increase in serum regucalcin concentration was observed 18 and 30 days after the administration. Liver regucalcin mRNA and liver cytosolic regucalcin levels were significantly decreased 18 and 30 days after CCl4 administration. Liver content of calcium, which intracellular calcium homeostasis is maintained, was significantly increased between 3 and 30 days after CCl4 administration. Hepatic mitochondrial succinate dehydrogenase activity was significantly increased 30 days after the administration. The present study demonstrates that serum regucalcin has a potential sensitivity as a specific biochemical marker of chronic liver injury with CCl4 administration in rats.

Animals↗

PubMed2002

Role of endogenous regucalcin in bone metabolism: bone loss is induced in regucalcin transgenic rats.

The role of endogenous regucalcin in the regulation of bone metabolism was investigated by using regucalcin transgenic (TG) rats. The expression of regucalcin mRNA in the femoral-diaphyseal and -metaphyseal tissues of normal (wild-type) rats was shown by using reverse transcription-polymerase chain reaction (RT-PCR) with a specific primer of regucalcin cDNA. Regucalcin protein was detected in the femoral-diaphyseal and -metaphyseal tissues of normal (wild-type) rats using Western analysis. Regucalcin levels were significantly increased in the femoral-metaphyseal tissues of regucalcin TG male rats and in the diaphyseal and metaphyseal tissues of the TG female rats. The morphologic change in the femoral-diaphyseal and -metaphyseal tissues of regucalcin TG rats was demonstrated by using a peripheral quantitative computed tomography (pQCT); morphologic change was great in the femoral tissues of female rats as compared with that of male rats. Mineral content, mineral density and polar strength strain index in the femoral-diaphyseal and -metaphyseal tissues were markedly reduced in regucalcin TG female rats. A significant decrease in cortical thickness was seen in the femoral diaphysis of regucalcin TG female rats. Calcium content in the femoral-diaphyseal and -metaphyseal tissues was significantly decreased in regucalcin TG male and female rats; a remarkable decrease was seen in female rats. Femoral-metaphyseal alkaline phosphatase activity was significantly lowered in regucalcin TG female rats. The enzyme activity was not significantly changed in the femoral-diaphyseal tissues of the TG female rats. In the diaphyseal tissue of male rats, the enzyme activity was significantly decreased in the TG rats. A significant decrease in deoxyribonucleic acid (DNA) content was seen in the metaphyseal tissue of regucalcin TG male rats and in the diaphyseal and metaphyseal tissues of the TG female rats. This study demonstrates that bone loss is induced in the femoral tissue of regucalcin transgenic rats, and that a remarkable decrease in bone morphologic index and biochemical component was seen in the female rats. Regucalcin may be involved in the regulation of bone metabolism.

Animals↗

PubMed2002

Stimulatory effect of menaquinone-7 on bone formation in elderly female rat femoral tissues in vitro: prevention of bone deterioration with aging.

Menaquinone-7 (MK-7) is vitamin K2 which is a series of vitamins with multiisoprene units at the 3-position of the naphthoquinone. MK-7 has been shown to prevent bone loss in ovariectomized rats, an animal model for osteoporosis. This study was undertaken to determine whether MK-7 has a stimulatory effect on bone components of elderly female rats in vitro. The femoral-diaphyseal and -metaphyseal tissues obtained from young (4 weeks old) or elderly (50 weeks old) female rats were cultured for 48 h in a Dullbecco's modified Eagle's medium (high glucose, 4.5%) supplemented with antibiotics and bovine serum albumin. Calcium content, alkaline phosphatase activity and deoxyribonucleic acid (DNA) in the diaphyseal and metaphyseal tissues obtained from elderly rats were significantly decreased as compared with those of young rats, indicating that aging causes a deterioration of bone formation. The presence of MK-7 (10(-6) or 10(-5) M) caused a significant increase in biochemical components in the femoral-diaphyseal and -metaphyseal tissues obtained from elderly rat in vitro. The anabolic effect of MK-7 (10(-6) or 10(-5) M) on the femoral calcium content was significantly enhanced in the presence of phytoestrogen genistein (10(-6) or 10(-5) M), suggesting that the mode of action of MK-7 differ from that of genistein. The effect of MK-7 (10(-5) M) in increasing calcium content, alkaline phosphatase activity and DNA content in the diaphyseal and metaphyseal tissues was completely abolished in the presence of cycloheximide (10(-6) M), an inhibitor of protein synthesis in vitro. These findings demonstrate that MK-7 has a stimulatory effect on bone formation in the femoral tissues of elderly female rats in vitro. MK-7 may have a preventive role for bone deterioration with aging.

Aging↗

PubMed2002

Suppressive role of endogenous regucalcin in the regulation of nitric oxide synthase activity in heart muscle cytosol of normal and regucalcin transgenic rats.

The role of regucalcin, a regulatory protein of Ca2+ signaling, in the regulation of nitric oxide (NO) synthase activity in the cytosol of rat heart muscle was investigated. The addition of calcium chloride (5-20 microM) into the enzyme reaction mixture containing the heart cytosolic protein caused a significant increase in NO synthase activity. The Ca2+ effect was significantly inhibited by trifluoperazine (TFP; 20 or 50 microM), an antagonist of calmodulin, indicating the existence of Ca2+/calmodulin-dependent NO synthase activity in rat heart muscle cytosol. NO synthase activity was significantly decreased by the addition of regucalcin (10(-9) or 10(-8) M). This effect was also seen in the presence of calcium chloride (10 microM), TFP (50 microM) or EGTA (1 mM), a chelator of Ca2+. Meanwhile, the effect of regucalcin (10(-8) M) in decreasing NO synthase activity was not seen in the presence of Nw-nitro-L-arginine methylester (NAME; 10(-6) or 10(-5) M), an inhibitor of the enzyme. The presence of anti-regucalcin monoclonal antibody (25 or 50 ng/ml) in the enzyme reaction mixture caused a significant increase in NO synthase activity. This effect was completely abolished by the addition of regucalcin (10(-7) M). NO synthase activity was not significantly changed in the heart muscle cytosol of transgenic rats overexpressing endogenous regucalcin as compared with that of wild-type rats. However, the effect of calcium (10 micro M) addition in increasing NO synthase activity was significantly weakened in the heart muscle cytosol of regucalcin transgenic rats. The present study demonstrates that endogenous regucalcin has a suppressive effect on NO synthase activity in the heart muscle cytosol of rats.

Animals↗