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Biomedical subjects

M Yamaguchi

Publications and source records attributed to M Yamaguchi.

At least 667 records · Page 37Linked to original sources
PubMed1996

Involvement of several protein kinases in the phosphorylation of p47-phox.

Protein kinases are stimulated during the microbicidal responses of neutrophils. In particular, the activation of protein kinase C causes the phosphorylation of p47-phox, one of the cytosolic components of NADPH oxidase. Phosphorylated p47-phox was accumulated not only by PMA treatment, but also by calyculin A treatment. However, p47-phox phosphorylated by calyculin A treatment lost its ability to activate NADPH oxidase. Several protein kinases were activated by calyculin A treatment. Furthermore the phosphorylation sites of p47-phox by calyculin A treatment were different from those by PMA treatment. These results indicated that calyculin A-activated kinases phosphorylated p47-phox at the site different from that phosphorylate by protein kinase C, resulting in suppression of NADPH oxidase activation.

Amino Acid Sequence↗
PubMed1996

Steroid hormonal regulation of calcium-binding protein regucalcin mRNA expression in the kidney cortex of rats.

The effect of various steroid hormones on the expression of calcium-binding protein regucalcin mRNA in the kidney cortex of rats was investigated. The change of regucalcin mRNA levels was analyzed by Northern blotting using rat liver regucalcin complementary DNA (0.9 kb of open-reading frame). Regucalcin mRNA was expressed in the kidney cortex but not the medulla. Rats received a single subcutaneous administration of steroid; the animals were sacrificed 60 min after the treatment of aldosterone (2.5, 5.0 and 10 micrograms/100 g body weight) or 6 h after the treatment of estrogen (17 beta-estradiol; 0.05, 0.1 and 0.2 mg/100 g), hydrocortisone (0.5, 1.0 and 3.0 mg/100 g) and dexamethasone (50, 100 and 150 micrograms/100 g). Regucalcin mRNA levels in the kidney cortex were clearly diminished by the administration of aldosterone or estrogen, while hydrocortisone administration had no effect. The administration of dexamethasone (100 micrograms/100 g) caused a remarkable increase of regucalcin mRNA levels in the kidney cortex. The dexamethasone-induced increase in regucalcin mRNA levels was completely blocked by the simultaneous administration of cycloheximide (150 micrograms/100 g), although the drug administration had no effect on the mRNA levels in control rats. Meanwhile, the dexamethasone administration did not cause an appreciable alteration of calcium content in the kidney cortex. The present study demonstrates that, of the various steroid hormones used, dexamethasone uniquely has a stimulatory effect on regucalcin mRNA expression in the kidney cortex of rats. The steroid effect may be mediated through a newly synthesized protein.

Aldosterone↗
PubMed1996

Isolation and characterization of cDNA for DREF, a promoter-activating factor for Drosophila DNA replication-related genes.

DREF, a transcription regulatory factor which specifically binds to the promoter-activating element DRE (DNA replication-related element) of DNA replication-related genes, was purified to homogeneity from nuclear extracts of Drosophila Kc cells. cDNA for DREF was isolated with the reverse-transcriptase polymerase chain reaction method using primers synthesized on the basis of partial amino acid sequences and following screening of cDNA libraries. Deduced from the nucleotide sequences of cDNA, DREF is a polypeptide of 701 amino acid residues with a molecular weight of 80,096, which contains three characteristic regions, rich in basic amino acids, proline, and acidic amino acids, respectively. Deletion analysis of bacterially expressed DREF fused with glutathione S-transferase (GST-DREF) indicated that a part of the N-terminal basic amino acid region (16-115 amino acids) is responsible for the specific binding to DRE. A polyclonal and four monoclonal antibodies were raised against the GST-DREF fusion protein. The antibodies inhibited specifically the transcription of DNA polymerase alpha promoter in vitro. Cotransfection experiments using Kc cells demonstrated that overproduction of DREF protein overcomes the repression of the proliferating cell nuclear antigen gene promoter by the zerknüllt gene product. These results confirmed that DREF is a trans-activating factor for DNA replication-related genes. Immunocytochemical analysis demonstrated the presence of DREF polypeptide in nuclei after the eighth nuclear division cycle, suggesting that nuclear accumulation of DREF is important for the coordinate zygotic expression of DNA replication-related genes carrying DRE sequences.

Amino Acid Sequence↗
PubMed1996

Expression of calcium-binding protein regucalcin mRNA in hepatoma cells.

Whether the gene expression of hepatic Ca(2+)-binding protein regucalcin is altered in hepatomas was investigated. The change in regucalcin mRNA levels was analyzed by Northern blotting using liver regucalcin complementary DNA (0.9 kb). Rat hepatoma was induced by continuous feeding of basal diet containing 0.06% 3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB). After 35 weeks feeding, rats were sacrificed, and the non-tumorous and tumorous tissues of the livers were removed. In individual rats, the regucalcin mRNA levels in the tumorous tissues were generally decreased in comparison with that of the non-tumorous tissues of the chemical-fed rats, although the chemical administration might decrease the mRNA expression in normal rat liver, suggesting that the chemical administration causes a suppressive effect on the mRNA expression. When the genomic DNA extracted from the liver tumorous tissues was digested with restriction enzymes (EcoRI, BamHI and HindIII) and analyzed by Southern blotting, no rear-ranged band was found in the regucalcin gene from the hepatoma. Interestingly, in the transplantable Morris hepatoma cells, the regucalcin mRNA was markedly expressed, while the albumin mRNA was expressed only slightly. The present study demonstrates that regucalcin mRNA is clearly expressed in the transformed cells (Morris hepatoma cells).

Animals↗
PubMed1996

Synthesis and characterization of polymer-coated mixed-functional stationary phases with several different hydrophobic groups for direct analysis of biological samples by liquid chromatography.

Three types of polymer-coated mixed-functional (PCMF) silica column-packing materials for the direct analysis of biological liquids have been synthesized. These packing materials all have polyoxyethylene groups as their hydrophilic part but differ in their hydrophobic part (methyl groups for Me-POE, phenyl groups for Ph-POE, and octyl groups for Oc-POE). Retention characteristics with respect to several drug molecules, and protein recovery, were studied for each of the three types with different amounts of hydrophobic groups attached. Of the PCMFs prepared, Oc-POE showed the greatest overall retention, and Me-POE displayed the greatest protein recovery.

Anti-Bacterial Agents↗
PubMed1996

Indication of fusion for lumbar spinal stenosis in elderly patients and its significance.

STUDY DESIGN: Selection of surgical therapy for lumbar canal stenosis in elderly patients is discussed. Decompression alone and decompression with fusion were evaluated. OBJECTIVES: To determine the indication of decompression with fusion for lumbar spinal stenosis in elderly patients. SUMMARY OF BACKGROUND DATA: Although there is no objection to posterior decompression, which is regarded as the first choice of surgical therapy for lumbar spinal stenosis in the elderly, it is debatable whether or not fusion should be used with decompression. METHODS: The presence or absence of instability was defined by Posner's method from preoperative plain radiographic lateral findings. Thirty-four elderly patients with lumbar canal stenosis were studied. Seventeen of the 34 patients were found to have instability. Ten of the 17 patients with spinal instability underwent decompression and instrumented fusion. The seven remaining patients with spinal instability underwent decompression alone. The 17 patients without spinal instability were treated by decompression alone. Preoperative symptoms, postoperative results, and changes in radiographic findings were compared among the three groups. RESULTS: The group treated by decompression and fusion showed the best results. The group treated by decompression in the presence of instability showed the worst results by the Japanese Orthopaedic Association back scores. Good results can be obtained by decompression alone only if the patients do not have instability as defined by Posner. CONCLUSIONS: The definition of instability by Posner's method proved useful for selecting elderly patients with instability for fusion treatment. Fusion with instrumentation should be performed on elderly patients with instability after decompression.

Aged↗
PubMed1996

Polyclonal B cell chronic lymphoproliferative disease with hairy cell morphology: a case report and clonal studies.

We describe a patient who has a chronic polyclonal B lymphocyte proliferation with a hairy-cell appearance. A 48-year-old Japanese woman with marked splenomegaly, systemic lymphadenopathy, and leukocytosis was referred to out hospital. Laboratory examination revealed marked polyclonal IgG hypergammaglobulinemia. Morphologic examination of the patient's peripheral blood, including May-Giemsa staining and scanning electron microscopy, showed a monotonous proliferation of hairy-appearing mature lymphocytes. An immunophenotypic study revealed an expansion of cells with mature B cell antigens positive for CD11c; however, light-chain restriction was not seen. The lack of both immuno-globulin heavy-chain and T cell receptor gene rearrangements by Southern blot analysis indicated the polyclonal nature of the proliferating B cells. This was confirmed further by a clonal analysis of the patient's lymphocytes using an X-chromosome-linked restriction fragment polymorphism within the X-linked phosphoglycerate kinase (PGK) gene. Since chronic B cell lymphoproliferation with a hairy cell appearance has not been described previously, this case might be extremely rare, and has important implication for the pathogenesis of mature B cell lymphoproliferative diseases, including hairy cell leukemia.

B-Lymphocytes↗
PubMed1996

Thrombopoietin modulates platelet activation in vitro through protein-tyrosine phosphorylation.

To determine the roles of thrombopoietin (TPO) in platelet function in vitro, we examined the effects of TPO on platelet aggregation. Although several proteins in platelets were tyrosine-phosphorylated by TPO treatment, TPO alone was unable to induce platelet aggregation. However, the secondary wave of platelet aggregation induced by adenosine diphosphate (ADP) was enhanced by TPO in a dose-dependent manner. TPO in conjunction with ADP augmented tyrosine phosphorylation of platelet proteins, including tyrosine-phosphorylated proteins induced by TPO alone. Genistein inhibited protein-tyrosine phosphorylation in platelets induced by TPO with ADP and suppressed TPO-enhanced platelet aggregation. Moreover, tyrosine phosphorylation of MAP-kinases induced by TPO alone and TPO with ADP was consistent with TPO-enhanced platelet aggregation. These findings in the present study suggest that signal transduction involved in TPO-enhanced platelet aggregation is mediated in part by tyrosine-phosphorylated proteins, including MAP-kinases, in platelets through TPO-stimulated c-Mpl, TPO receptor.

Adenosine Diphosphate↗
PubMed1996

Immunohisto- and immunocytochemical studies on the dynamics of TSH and GTH cells in normally metamorphosing, metamorphosed, and metamorphosis-arrested Hynobius retardatus.

The development and dynamics of TSH and GTH cells were studied immunohisto- and immunocytochemically in the salamander Hynobius retardatus, which had been reported to show neoteny in a specific environment and a precocious development and maturation of testis in goitrogen-treated larvae. Pituitary glands from normally metamorphosing and metamorphosed animals, and metamorphosis-arrested larvae which had been treated with goitrogens, were examined using anti-human TSH beta and anti-bullfrog LH beta sera. The immunoreactive TSH cells in the goitrogen-treated larvae began to exceed those in the controls in number at 40 days after hatching (stage 64). At the end of this experiment (220 days after hatching), the goitrogen-treated larvae had four times more immunoreactive TSH cells than the controls. The immunoreactive TSH cells in the goitrogen-treated larvae came to occupy nearly the whole area of the section of the pars distalis. Contrary to this, no significant differences were observed in the number of immunoreactive GTH cells between the goitrogen-treated larvae and the controls during their ontogeny. The number of immunoreactive GTH cells was much less than that of immunoreactive TSH cells. Immunocytochemistry at the electron microscopical level revealed many "thyroidectomy cells" with extraordinarily inflated ER and secretory granules which showed strong immunoreactivity with anti-TSH beta antibody only in the pars distalis of the goitrogen-treated larvae. These results suggest the possibility that TSH induces precocious testicular development and maturation in the goitrogen-treated larvae in H. retardatus.

Animals↗
PubMed1996

Effect of boiled barley-rice-feeding in hypercholesterolemic and normolipemic subjects.

Barley contains approximately 10% dietary fiber and is easily cooked with rice, the dominant cereal in Japan, to increase the intake of dietary fiber. This research involved three experiments to examine the influence of barley on blood lipids in human subjects. All subjects received a boiled barley-rice (50/50 w/w mix) supplement two times per day in place of rice for 2 or 4 weeks. In the normolipemic subjects, serum lipids were unaffected by the ingestion of barley for 4 weeks. In twenty hypercholesterolemic men aged 41 +/- 5 years, the ingestion of barley was associated with a significant fall in serum total cholesterol, LDL-cholesterol, phospholipids and LDL and VLDL-lipoproteins. In seven mildly hypercholesterolemic women aged 56 +/- 7 years, a significant improvement of serum lipid profiles was observed. The present study suggests the possibility that the ingestion of barley-rice could lower serum lipids in hypercholesterolemic subjects.

Adult↗
PubMed1996

Histomorphological confirmation of bone loss in the femoral-metaphyseal tissues of rats with skeletal unloading.

The alteration of mineral content in the femoral metaphysis of rats with skeletal unloading was investigated using a model of hindlimb suspension. Animals were fed for 4 days during the unloading. The femoral length, femoral dry weight and femoral mineral density were significantly decreased by the unloading. The calcium, phosphorus and zinc contents in the femoral metaphysis were appreciably reduced by the unloading, although, except for zinc, similar decreases were not seen in the femoral diaphysis. Moreover, the trabecular bone at the femoral metaphysis was clearly reduced by the unloading. Skeletal unloading caused a decrease in osteoid tissue in the primary and secondary spongiosa, indicating that osteoblastic bone formation may be inhibited. The present results clearly demonstrate that skeletal unloading can induce bone loss in the femoral metaphysis.

Animals↗
PubMed1996

Effect of vitamin K2 (menaquinone-7) on bone metabolism in the femoral-metaphyseal tissues of normal and skeletal-unloaded rats: enhancement with zinc.

The effect of vitamin K2 (menaquinone-7) on bone metabolism in the femoral-metaphyseal tissues of normal and skeletal-unloaded rats was investigated. Skeletal unloading was designed using a model of hindlimb suspension; the rats were fed for the 4 days of unloading. The metaphyseal tissues obtained from normal and skeletal-unloaded rats were cultured for 48 h in medium containing either vehicle or vitamin K2 (10(-6) and 10(-5) M). The presence of vitamin K2 (10(-5) M) caused a significant increase in alkaline phosphatase activity and calcium content in the metaphyseal tissues from normal rats. Such an effect was not seen in the bone tissues from skeletal-unloaded rats. Additionally, the presence of zinc sulfate (10(-5) M) in effective concentration produced a significant increase in alkaline phosphatase activity and calcium content in the metaphyseal tissues from normal and skeletal-unloaded rats. In the presence of vitamin K2 (10(-5) M), the stimulatory effect of zinc sulfate on bone calcium content was appreciably enhanced; although this effect was completely abolished by cycloheximide (10(-6) M), an inhibitor of protein synthesis. This study demonstrates that the effect of vitamin K2 (menaquinone-7) on trabecular bone calcification in rats with skeletal unloading-induced osteopenia is enhanced by zinc in vitro. The enhancement with zinc may be based on a newly synthesized protein in the bone tissues.

Alkaline Phosphatase↗
PubMed1996

Regulation of mouse placental lactogen secretion by G proteins before midpregnancy.

To determine whether G proteins are involved in the regulation of mouse placental lactogen-I (mPL-I) and/or mPL-II secretion before midpregnancy, mouse placental tissue from day 7 of pregnancy was dispersed with collagenase, cells were fractionated on a percoll gradient, and the purified trophoblast cells were cultured in a serum-free medium with cholera toxin (CTX) or pertussis toxin (PTX) which modulate the activities of distinct G proteins for 5 days. CTX inhibited both mPL-I and mPL-II secretion, but PTX inhibited mPL-I secretion and stimulated mPL-II secretion in a time- and dose-dependent manner. Addition of both CTX and PTX additionally inhibited mPL-I secretion but did not affect mPL-II secretion. 8-Bromo cAMP, which increases intracellular cAMP accumulation, inhibited both mPL-I and mPL-II secretion similarly to CTX. In contrast, H8, an inhibitor of cAMP-dependent protein kinase A, stimulated both mPL-I and mPL-II secretion. Addition of PTX and H8 synergistically stimulated mPL-II secretion. These findings suggest that G proteins play important roles in regulation of mPL-I and mPL-II secretion before midpregnancy.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1996

Gestational changes of glucose transporter gene expression in the mouse placenta and decidua.

Glucose is required for fetal development and energy metabolism. The glucose transfer from maternal circulation to fetus, in which glucose transporter (GLUT) should play an important role, is fundamental in the utero-placental-fetal system. In this study, the gestational changes of GLUT1 and GLUT3 mRNA level in the mouse placenta and decidua were analyzed by Northern blot analysis. The levels of GLUT1 mRNA in the mouse placenta and decidua increased as gestational day proceeded. Although the level of GLUT3 mRNA in the decidua slightly decreased as pregnancy proceeded, there was a switch in size of a major band of GLUT3 from 4.1 kb to 2.7 kb in the mouse placenta detected by Northern blot analysis. These findings suggest the presence of a difference in the gestational modulation of the level of GLUT1 and GLUT3 in the uteroplacental system.

Animals↗
PubMed1996

Intraventricular administration of estradiol modulates rat prolactin secretion and synthesis.

The effect of estradiol (E2) on rat tuberoinfundibular dopaminergic (TIDA) neurons was examined in vivo, employing chronic intraventricular (i.c.v.) infusion technique using an osmotic mini-pump. The activity of TIDA neurons was assessed by the release and synthesis of prolactin (PRL) in the rat pituitary gland and by the changes in the 3, 4-dihydroxyphenylacetic acid (DOPAC) and dopamine (DA) levels and in the DOPAC/DA ratio in the rat hypothalamus. We also examined the [3H] E2 binding in the rat hypothalamus. Ovariectomized female Wistar rats with E2 replacement were treated with daily i.c.v. infusion of 1 microM of E2 or saline vehicle for 1, 3, and 7 days using the Alzet osmotic mini-pump and brain infusion kit. At 1 day of i.c.v. infusion of E2, the serum PRL level was significantly decreased compared with that in the vehicle group. Northern blot analysis of the total RNA isolated from the pituitary glands demonstrated a decrease in the PRL gene transcript level in the E2 group. At 3 days of E2 treatment, however, the serum PRL level was significantly increased compared with that of the vehicle-injected group and Northern blot analysis also demonstrated that the PRL gene transcript level was increased in the E2 group. At 7 days of E2 administration, there were no significant differences between the E2 and vehicle groups in either serum PRL or PRL gene transcript levels. There was a significant increase in the DOPAC/DA ratio after 1 day in the E2 group. However, no significant effects of E2 on this ratio were observed at 3 and 7 days of treatment. The DOPAC concentration in the E2 group was significantly increased at day 1 and significantly decreased at day 3, compared with that of the respective time in vehicle group. At day 7 there was no significant change in DOPAC concentration in either groups. The DA concentrations in the hypothalamus was not changed on any day in either group. Specific [3H] E2 binding was observed in the rat hypothalamus. These data suggest that E2 may have a biphasic effect on the accumulation of PRL gene transcripts and on the PRL secretion in the rat pituitary by first stimulating and then inhibiting the TIDA neuronal activity.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1996

Regulation of mouse placental lactogen-II secretion by transforming growth factor-alpha after midpregnancy.

We investigated whether transforming growth factor-alpha (TGF-alpha) regulates mouse placental lactogen-II (mPL-II) secretion by cells from day 12 of pregnancy. TGF-alpha significantly inhibited mPL-II secretion by the third and fourth day of culture, and then stimulated mPL-II secretion from the sixth day. The inhibitory and stimulatory effects of TGF-alpha on mPL-II secretion were dose-dependent, and the lowest concentration of TGF-alpha-which caused significant inhibition or stimulation of mPL-II secretion was 10 ng/ml. When TGF-alpha treatment of placental cells was begun on the fifth day of the culture, significant stimulation of mPL-II secretion was observed 3 days later. TGF-alpha inhibited steady-state levels of mPL-II mRNA on the third day of culture but stimulated steady-state levels of mPL-II mRNA on the seventh day of culture. These results suggest that TGF-alpha biphasically regulates mPL-II secretion through regulation of mPL-II gene expression after midpregnancy.

Animals↗
PubMed1996

Transforming growth factor-alpha regulates subpopulation of giant cells which secrete mouse placental lactogen-I (mPL-I) and/or mPL-II at midpregnancy.

The aim of this study was to determine whether transforming growth factor-alpha (TGF-alpha) regulates expression of mouse placental lactogen-I (mPL-I) and mPL-II at midpregnancy in vitro. Treatment of placental cells from day 9 of pregnancy with TGF-alpha resulted in stimulation of mPL-I secretion and inhibition of mPL-II secretion in a time- and dose-dependent manner without changing the amount of newly synthesized trichloroacetic acid precipitable proteins and cell viability. Moreover, TGF-alpha increased the intra-cellular mPL-I concentration and immuno-precipitable newly synthesized mPL-I concentration both in the medium and cells. TGF-alpha increased the number of cells containing only mPL-I and cells containing both mPL-I and mPL-II, but decreased that of the cells containing only mPL-II assessed by double immunocytochemistry. TGF-alpha increased the number of cells releasing only mPL-I but decreased the number of cells releasing only mPL-II, however TGF-alpha did not affect the number of cells releasing both mPL-I and mPL-II assessed by sequential reverse hemolytic plaque assay (RHPA). TGF-alpha decreased the expression of mPL-II mRNA, but did not change the expression of mPL-I mRNA. In situ hybridization for epidermal growth factor receptor (EGF-R) after RHPA for mPL-I indicated that giant cells releasing mPL-I express EGF-R mRNA. These findings suggest that TGF-alpha regulates the subpopulation of giant cells which produces and releases mPL-I and mPL-II and it results in an increase of mPL-I secretion and decrease of mPL-II secretion, and suggests possible post-transcriptional stimulation of mPL-I secretion and transcriptional inhibition of mPL-II secretion by TGF-alpha. Giant cells releasing mPL-I express EGF-R mRNA, suggesting direct regulation of giant cell differentiation by EGF and TGF-alpha at midpregnancy.

Animals↗