Search PubMed⌕ Search

Biomedical subjects

M Yamaguchi

Publications and source records attributed to M Yamaguchi.

At least 1,405 records · Page 78Linked to original sources
PubMed1988

Zinc stimulation of bone protein synthesis in tissue culture. Activation of aminoacyl-tRNA synthetase.

The present investigation was undertaken to clarify the effect of zinc on bone protein synthesis in tissue culture. Calvaria were removed from 3-week-old male rats and cultured for periods up to 96 hr in Dulbecco's Modified Eagle Medium (high glucose, 4500 mg/dl) supplemented with antibiotics and bovine serum albumin. The calvaria were incubated at 37 degrees in 5% CO2/95% air in the medium containing 10(-6)-10(-4) M zinc. Zinc content in bone cells was increased when the culture was treated with 10(-5) and 10(-4) M zinc for 48 hr. When calvaria cultured in the presence of 10(-4) M zinc were pulsed with [14C]uridine, the incorporation of [14C]uridine into the bone RNA was not increased significantly. In the pulse with [3H]leucine, the presence of 10(-5) to 10(-4) M zinc in the medium caused a significant increase in the incorporation of [3H]leucine into the acid-insoluble residues of bone tissue. This increase was blocked completely by treatment with 10(-7) M cycloheximide, an inhibitor of protein synthesis. When [3H]leucine was added into the reaction mixture containing the 5500 g supernatant fraction of the homogenate prepared from calvaria cultured in the presence of 10(-4) M zinc, the in vitro protein synthesis was increased about 2-fold. The activity of [3H]leucyl-tRNA synthetase in the 105,000 g supernatant fraction (cytosol) of the bone homogenate was increased about 2-fold by the culture with 10(-4) M zinc. The presence of 10(-4) M dipicolinate, a specific chelator of zinc, in the culture medium negated the effect of zinc on [3H]leucyl-tRNA synthetase activity. The addition of 10(-7) to 10(-6) M zinc into the reaction mixture containing enzyme extracts obtained from uncultured rat calvaria caused a 2-fold increase of [3H]leucyl-tRNA synthetase activity. These results clearly indicate that zinc induces the stimulation of protein synthesis at the translational level in bone cells. The present study further supports the view that zinc increases protein synthesis in bone cells and that the metal induces bone formation.

Amino Acyl-tRNA Synthetases↗
PubMed1988

Mouse DNA polymerase beta gene promoter: fine mapping and involvement of Sp1-like mouse transcription factor in its function.

The promoter of mouse DNA polymerase beta gene was analyzed by combining 5'-upstream region of this gene with chloramphenicol acetyltransferase (CAT) gene and by introduction of the recombinant plasmid DNA into mouse NIH/3T3 cells. Serial deletion of the mouse DNA sequence revealed that the promoter function resides within a 33 base pair region from the nucleotide position -48 to -15 with respect to the transcription initiation site, and is highly active without enhancer sequence. The promoter region was separated into two subregions: one (-48 to -35) contains a GC-box and the other contains a 10 base pair palindrome, whose sequence is similar to one of promoter consensus sequences found in a number of promoters including adenovirus promoters. The DNA polymerase beta promoter-directed CAT expression was competitively inhibited by the simultaneous transfection of plasmid DNA containing SV40 early promoter sequence. The viral sequences which are competitive to the GC-box of DNA polymerase beta gene promoter were the GC-boxes of SV40 promoter. Therefore, it is concluded that transcription of mouse DNA polymerase beta gene is regulated by mouse trans-acting factors equivalent to human Sp1 which is known to be trans-acting protein factor acting on SV40 GC-box sequences.

Animals↗
PubMed1988

Expression of active rat DNA polymerase beta in Escherichia coli.

A recombinant plasmid for expression of rat DNA polymerase beta was constructed in a plasmid/phage chimeric vector, pUC118, by an oligonucleotide-directed mutagenesis technique. The insert contained a 1005 bp coding sequence for the whole rat DNA polymerase beta. The recombinant plasmid was designed to use the regulatory sequence of Escherichia coli lac operon and the initiation ATG codon for beta-galactosidase as those for DNA polymerase beta. The recombinant clone, JMp beta 5, obtained by transfection of E. coli JM109 with the plasmid, produced high levels of DNA polymerase activity and a 40-kDa polypeptide that were not detected in JM109 cell extract. Inducing this recombinant E. coli with isopropyl beta-thiogalactopyranoside (IPTG) yielded amounts of 40-kDa polypeptide as high as 19.3% of total protein. Another recombinant clone, JMp beta 2-1, which was constructed by an oligonucleotide-directed mutagenesis to use the second ATG codon for the initiation codon, thus deleting the first 17 amino acid residues from the amino terminus, produced neither high DNA polymerase activity nor the 40-kDa polypeptide. The evidence suggests that this amino-terminal structure is important for stability of this enzyme in E. coli. The DNA polymerase was purified to homogeneity from the IPTG-induced JMp beta 5 cells by fewer steps than the procedure for purification of DNA polymerase beta from animal cells. The properties of this enzyme in activity, chromatographic behavior, size, antigenicity, and also lack of associated nuclease activity were indistinguishable from those of DNA polymerase beta purified from rat cells, indicating the identity of the overproduced DNA polymerase in the JMp beta 5 and the rat DNA polymerase beta.

Amino Acid Sequence↗
PubMed1988

The primary structure of the mitochondrial energy-linked nicotinamide nucleotide transhydrogenase deduced from the sequence of cDNA clones.

The amino acid sequence of the bovine mitochondrial nicotinamide nucleotide transhydrogenase, which catalyzes hydride ion transfer between NAD(H) and NADP(H) coupled to proton translocation across the mitochondrial inner membrane, has been deduced from the corresponding cDNA. Two clones were isolated by screening a bovine lambda gt10 cDNA library, using two synthetic oligonucleotides and a cDNA restriction fragment as probes. The inserts together covered 3,105 base pairs of coding sequence, corresponding to 1.035 amino acid residues. However, the reading frame at the 5' end was still open. N-terminal sequence analysis of the isolated enzyme indicated the presence of 8 additional residues. Thus, the mature transhydrogenase appeared to have 1,043 amino acid residues and a calculated molecular weight of 109,212. The deduced amino acid sequence of the transhydrogenase contained the sequences of four tryptic peptides that had been isolated from the enzyme. Two of these were the peptides that had been used for construction of the oligonucleotide probes. The other two were tryptic peptides isolated after labeling the NAD-binding site of the transhydrogenase once with [3H]p-fluorosulfonylbenzoyl-5'-adenosine (FSBA), and another time with [14C]N,N'-dicyclohexylcarbodiimide. The FSBA-labeled peptide was found to be located immediately upstream of the [14C]N,N'-dicyclohexylcarbodiimide-labeled peptide, about 230 residues from the N terminus. One of the tryptic peptides used for oligonucleotide probe construction was the same as that labeled with [3H]FSBA when the NAD-binding site was protected from FSBA attack. This peptide, which might be at the NADP-binding site of the transhydrogenase, was located very near the C terminus of the enzyme. The central region of the transhydrogenase (residues 420-850) is highly hydrophobic and appears to comprise about 14 membrane-spanning segments. By comparison, the N- and the C-terminal regions of the enzyme, which contain the NAD- and the putative NADP-binding sites, respectively, are relatively hydrophilic and are probably located outside the mitochondrial inner membrane on the matrix side. There is considerable homology between the bovine enzyme and the Escherichia coli transhydrogenase (two subunits, alpha with Mr = 54,000 and beta with Mr = 48,700), whose amino acid sequence has been determined from the genes (Clarke, D.M., Loo, T.W., Gillam, S., and Bragg, P.D. (1986) Eur. J. Biochem. 158, 647-653).

Amino Acid Sequence↗
PubMed1988

Identification and subcellular localization of the polypeptide for chick DNA primase with a specific monoclonal antibody.

Polypeptides responsible for activities of chick embryo DNA primase and DNA polymerase alpha were identified using monoclonal antibodies specific to these two enzymes. The 4-8H antibody neutralized DNA polymerase alpha activity measured on activated DNA template and also ribonucleoside triphosphate-dependent DNA synthesis on single-stranded DNA template (DNA primase-DNA polymerase alpha combined activity) to a partial extent (about 30%), but did not affect DNA primase activity. The 4-2D antibody, although it did not affect DNA polymerase alpha activity, did neutralize both DNA primase activity and DNA primase-DNA polymerase alpha combined activity extensively (up to 70%). Immunoblotting analysis of the DNA primase-DNA polymerase alpha complex showed that 4-2D and 4-8H antibodies recognize 60-kDa and 160-180-kDa polypeptides, respectively. An immunoaffinity column made of either of these antibodies retained DNA primase-DNA polymerase alpha complex. When the enzyme was eluted from the 4-8H column with alkaline solution, DNA primase was eluted prior to DNA polymerase alpha. In the case of 4-2D antibody column chromatography, the elution order of two enzymes was reversed. Results indicate that two enzymes in the complex which was retained in the antibody column were dissociated by lower alkaline pH than that dissociated the antigenic enzymes from the corresponding antibodies. In both cases, the fractions with DNA primase activity contained exclusively 60-kDa polypeptide, while those with DNA polymerase alpha contained 160-180-kDa polypeptides. Thus, DNA primase resided in 60-kDa polypeptide and was recognized by 4-2D antibody while DNA polymerase alpha resided in 160-180-kDa polypeptides and was recognized by 4-8H antibody. Immunofluorescence made with the DNA primase-specific 4-2D antibody as well as with 4-8H antibody appeared in granular structures which were tightly bound to the nuclear matrix. These nuclear fluorescences were much reduced in quiescent cells. Furthermore, since the fluorescence made by these antibodies was induced by adding serum to the quiescent cells in serum-deprived cultures, the expression of DNA primase and its organization in the structures on the nuclear matrix are regulated in correlation to the proliferating stage of cells, as observed with DNA polymerase alpha.

Animals↗
PubMed1988

The relationship between Ga-67 accumulation and cell cycle in malignant tumor cells in vitro.

Previously we reported that the deposition of 67Ga into malignant tumor may be a sensitive index of proliferative activity in tumor cells. For the purpose of elucidation of this hypothesis, we investigated the relationship between the accumulation of 67Ga into malignant tumor cells and the cell cycle in vitro. We discovered that the uptake of both 67Ga and 59Fe into synchronized mouse tumor cells reaches a peak at the G2 stage which precedes cellular proliferation. Both iron and transferrin are specifically required by cells in culture for cell division, and the fact that 67Ga and 59Fe uptake into tumor cells peaks at the G2 stage of the cell cycle suggests that there is a correlation between 67Ga uptake and the rate of cellular proliferation in malignant tumor cells.

Animals↗
PubMed1988

Urinary excretion of 6-keto prostaglandin F1 alpha in pre-eclampsia.

In order to investigate whether urinary excretion of prostaglandins (PG) is involved in the pathophysiology of pre-eclampsia, urinary immunoreactive 6-keto PGF1 alpha and TXB2 were measured in normal and pre-eclamptic women by radio-immunoassay after extraction with Bond Elut column. Urinary levels of 6-keto PGF1 alpha and TXB2 were expressed as ratio of urinary concentration of prostaglandin vs. creatinine (pg prostaglandin/mg creatinine; pg/mg cre.). Urinary excretion in normal pregnant and postpartum women were 211.2 +/- 33.8 and 160.1 +/- 9.1 pg/mg cre., respectively. In the pre-eclamptic group, urinary excretion of 6-keto PGF1 alpha was 105.3 +/- 28.2 pg/mg cre. in pregnancy and 99.0 +/- 12.5 pg/mg cre. in the postpartum period. Urinary excretion of 6-keto PGF1 alpha in the pre-eclamptic group was significantly lower (P less than 0.05) than in normal controls during pregnancy but not in the postpartum period. Urinary excretion of TXB2 was not significantly different between the two groups. The urinary excretion of 6-keto PGF1 alpha was measured before and after the onset of pre-eclampsia in four cases of edema and weight gain of more than 500 g/week (group e), one case of proteinuria of more than 200 mg/dl with edema (group ep) and three cases of pre-eclampsia (group eph). The urinary excretion of 6-keto PGF1 alpha in these eight patients before onset of pre-eclampsia was slightly lower than of normal controls but not significantly so. In group eph, urinary excretion of PG was decreased after the onset of pre-eclampsia. These results provide further evidence of the involvement of PG in the pathophysiology of pre-eclampsia.

6-Ketoprostaglandin F1 alpha↗
PubMed1988

Combined effects of UFT with other anticancer agents using in vivo chemosensitivity tests.

In order to estimate the combined effects of UFT with other anticancer agents, a nude mouse experimental system (NMES), and a subrenal capsule assay (SRCA) were investigated. Three human tumor xenografts were serially transplanted into nude mice and examined. These were; EH-1 established from esophageal cancer, SH-6 from gastric cancer and CH-3 from colon cancer. The antiproliferative effects were estimated in accordance with the NCI therapeutic protocol. Significant antiproliferative effects were obtained only in NMES and a positive relationship was observed between the two assays (p less than 0.05). In the groups which were treated with a single agent, positive tumor responses were observed against mitomycin C in SH-6, against cis-DD platinum in SH-6 and EH-1, and against adriamycin in EH-1, respectively. On this study the synergistic, additive and subadditive effects were defined as the positive combined effects. The combination of MMC and UFT produced positive combined effects for all xenografts in both assays.

Animals↗
PubMed1988

Plasma catecholamine concentrations during a 72-hour aminophylline infusion in children with acute asthma.

To explore the possibility that theophylline may act through adrenomedullary secretion of catecholamines, we examined the time courses of plasma norepinephrine (NE), epinephrine (E), and theophylline concentrations and peak expiratory flow (PEF) in nine children with an acute exacerbation of asthma receiving a 72-hour constant infusion of aminophylline. These measurements were made before (baseline) and at 2, 24, 48, and 72 hours after the infusion began. Plasma theophylline concentrations were kept constant in a near midpoint therapeutic range (mean +/- SEM, 14.1 +/- 1.3 to 16.1 +/- 1.1 micrograms/ml) during the 24- to 72-hour infusion periods. Compared with the respective baseline values (383.8 +/- 56.0 and 67.6 +/- 11.8 pg/ml for NE and E), the following postinfusion plasma catecholamines reached statistically significant difference: 664.0 +/- 125.1 pg/ml for NE at 24 hours (p less than 0.05), and 214.9 +/- 57.8, 233.7 +/- 82.2, and 137.6 +/- 39.4 pg/ml for E at 2, 24, and 48 hours (p less than 0.01). Despite the fact that similar plasma theophylline concentrations were maintained, plasma E, which peaked at 24 hours after dose, returned toward the baseline at the end of infusion (99.7 +/- 24.1 pg/ml), whereas this trend was not observed for NE. The postinfusion PEF increased (p less than 0.01) in a stepwise fashion, compared with the baseline, as the infusion progressed. The change in PEF correlated significantly (p less than 0.002) with plasma theophylline concentrations but not with the increase in plasma E from the baseline. Theophylline concentrations did not correlate with the increase in plasma NE or E from the baseline.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1988

Some more speract derivatives associated with eggs of sea urchins, Pseudocentrotus depressus, Strongylocentrotus purpuratus, Hemicentrotus pulcherrimus and Anthocidaris crassispina.

1. Fourteen peptides were isolated from the egg jelly of sea urchins, Pseudocentrotus depressus, Strongylocentrotus purpuratus, Hemicentrotus pulcherrimus and Anthocidaris crassispina and their amino acid sequences were determined. 2. The peptides stimulated H. pulcherrimus sperm respiration one half-maximally at about 8-60 pM. 3. Addition of speract to intact spermatozoa of P. depressus, H. pulcherrimus and A. crassispina resulted in the appearance of a newly stained protein (Mr 128,000 for P. depressus, Mr 128,000 for H. pulcherrimus and Mr 131,000 for A. crassispina) on sodium dodecyl sulfate-polyacrylamide gels.

Amino Acids↗
PubMed1988

A novel group of sperm activating peptides from the sea urchin Glyptocidaris crenularis.

1. Six new sperm activating peptides were purified from the egg jelly of the sea urchin Glyptocidaris crenularis and their amino acid sequences were determined as follows: Ser-Ala-Lys-Leu-Cys-Pro-Gly-Gly-Asn-Cys-Val, Lys-Leu-Cys-Pro-Gly-Gly-Asn-Cys-Val, Leu-Cys-Pro-Gly-Gly-Asn-Cys-Val, Ser-Phe-Lys-Leu-Cys-Pro-Gly-Gly-Gln-Cys-Val, Lys-Leu-Cys-Pro-Gly-Gly-Gln-Cys-Val and Leu-Cys-Pro-Gly-Gly-Gln-Cys-Val. 2. The peptides were specific for G. crenularis spermatozoa and caused significant increases of sperm respiration rates and sperm cyclic nucleotide concentrations at concentrations as low as 10(-10) M. 3. The addition of the peptides to intact spermatozoa resulted in the change of the apparent mol. wt of a sperm protein from 195,000 to 200,000.

Amino Acid Sequence↗
PubMed1988

Polarity and length of actin filaments at the fascia adherens of the cardiac intercalated disk.

Digestion of canine and bovine intercalated disks with a calcium-activated protease (CAF) removes the electron-dense material similar to that found at the Z-line and presumably consisting primarily of alpha-actinin. The major filaments exposed by CAF are actin, and the polarity is away from the intercalated disk, as was confirmed by decoration with heavy meromyosin. The length of actin filaments associated with the fascia adherens region at the concave region is 1.2- to 2.2-fold that of actin filaments (I-filaments) in the sarcomere and varies depending on the interdigitation of the membrane at the cell junction. Actin filaments at the intercalated disk seem to be attached (or very close) to the membrane in a direct, rather than looping, manner.

Actins↗
PubMed1988

Food deprivation decreases the blood TRH concentration in the rat.

Adult male rats were deprived of food for 1-6 days and the hypothalamo-pituitary axis in these rats was evaluated. Food deprivation caused a progressive decrease in TRH concentration in the peripheral blood with a concomitant reduction in the blood TSH level. No significant change was observed in the hypothalamic, extrahypothalamic or pancreatic TRH concentration between the control and starved groups. Starvation did not cause a significant change in the pituitary TRH receptors or the in vitro responsiveness of TSH to TRH. These data imply that the reduction in the blood TRH level may contribute in part to the decrease in the blood TSH level after food deprivation, but the origin of the blood TRH has remained to be determined.

Animals↗
PubMed1988

Hormonal regulation of biliary calcium excretion in rats: inhibition of calcitonin action by alpha 1-adrenergic stimulation.

The effect of synthetic [Asu1,7] eel calcitonin (CT) and other hormones on biliary calcium excretion was investigated in rats cannulated bile duct. Administration of CT (80 mU/100 g body weight) produced a significant increase in liver calcium and a corresponding elevation of bile calcium content. The increase in bile calcium content was also caused by administration of insulin (0.1 U/100 g), epidermal growth factor (10 micrograms/100 g), glucagon (10 micrograms/100 g), epinephrine (10 micrograms/100 g), norepinephrine (10 micrograms/100 g), 4 beta-phorbol 12-myristate-13-acetate (10 micrograms/100 g) and ATP (1.0 mg/100 g), suggesting that this increase may be a receptors-mediated response. Of these hormones and drugs, norepinephrine, a alpha-receptor mediator, clearly prevented CT effect on biliary calcium excretion. Moreover, phenylephrine, a alpha 1-receptor agonist, caused an inhibition of the CT effect, while the agonist significantly increased biliary calcium excretion. The present study clearly demonstrates that biliary calcium excretion is stimulated by various hormones which increase calcium influx into liver cells, and suggests that the CT action may be inhibited by alpha 1-adrenergic stimulation.

Adrenergic alpha-Agonists↗
PubMed1988

Three-dimensional determination of gastric ulcer size with laser endoscopy.

We have developed a new endoscopic system for measuring the three-dimensional structure of the gastric ulcer. The system consists of an argon ion laser generator, a side-viewing endoscope with diffraction grating made of glass fibers, and a graphic processing unit. Via a fiber grating fitted in the tip of the endoscope, about 1600 light spots produced by the diffracted laser beam were projected on to the gastric mucosa. By graphic processing involving the detection of the deviation of the laser spot array on the gastric lesion, the diameter, area, and height or depth of the lesion could be determined. To evaluate the accuracy of the system, the diameter and area of a rubber disc were determined in vitro and in the stomach. A cubic model 10 mm in height was used to evaluate the accuracy of the system in measuring height. Accuracy proved to be satisfactory for clinical use. The course of healing of 6 gastric ulcers treated by histamine receptor antagonist was followed with the system. A linear decrease in diameter and depth of the ulcer was observed.

Gastroscopy↗
PubMed1988

Early prenatal diagnosis of amniotic band syndrome.

A case of amniotic band syndrome diagnosed at 16 weeks gestation is presented. The pregnancy was complicated by cervical incompetence. Restriction of fetal head movement was important in sonographic diagnosis.

Abortion, Therapeutic↗