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Biomedical subjects

M Yamaguchi

Publications and source records attributed to M Yamaguchi.

At least 1,351 records · Page 75Linked to original sources
PubMed1989

Difference in the expression level of DNA polymerase beta among mouse tissues: high expression in the pachytene spermatocyte.

The expression level of DNA polymerase beta was determined in various mouse tissues. Northern blot hybridization analysis using rat cDNA as a probe revealed that the mRNA of about 1.5 kb for this enzyme is present in all kinds of tissues examined, but its content widely varies among tissues; the most abundant DNA polymerase beta mRNA was present in the testis, which was followed by brain, thymus, and spleen. The mRNA content was low in heart, kidney, and liver. In testis and brain, two minor species of transcripts of 3.3 and 6.2 kb were detected in addition to that of 1.5 kb. DNA polymerase beta activities in these tissues were closely correlated with the mRNA content, indicating that the expression of this enzyme is mainly regulated by the level of the mRNA. A survey of DNA polymerase beta mRNA levels in the testes at successive postnatal developmental stages and in isolated spermatogenic cells indicated that DNA polymerase beta mRNA was most abundant in spermatocytes at early pachytene. Since meiotic recombination occurs in this period, DNA polymerase beta may be involved in the repair-type DNA synthesis associated with the recombination process.

Animals↗
PubMed1989

Effect of calcitonin on exchangeable calcium transport in isolated rat hepatocytes.

The effect of calcitonin (synthetic [Asu1,7]eel) on the exchangeable Ca2+ transport was investigated in isolated rat hepatocytes by measuring 45Ca2+ uptake. Calcitonin (CT) increased the uptake of Ca2+ with 74.3 pM giving a half-maximal effect. The action of CT was evident within 5 min after the hormone addition to the cells, and the increase in Ca2+ uptake was maintained during 60 min. The increase in Ca2+ uptake caused by CT was dependent on extracellular Ca2+ concentration. On the other hand, the activity of mitochondrial succinate dehydrogenase in hepatocytes was significantly increased by addition of CT (74.3 pM) to the cells in the presence of 1.3 mM Ca2+, while the hormonal effect was not seen in the absence of added Ca2+. The presence of Ca2+ ionophore A23187 (0.1 and 1.0 microM) abolished the increase in enzyme activity caused by CT addition to the cells. It is proposed that CT can increase the rate of uptake of exchangeable CA2+ by hepatocytes, and that the hormone causes the elevation of mitochondrial succinate dehydrogenase activity which is mediated through Ca2+.

Animals↗
PubMed1989

The application of intrascrotal deep body temperature measurement for the noninvasive diagnosis of varicoceles.

The authors used intrascrotal deep body (intratesticular) temperature measurement in an attempt to make the diagnosis of varicoceles more objective. Two hundred five male patients complaining of infertility were classified into three groups: group A consisted of 84 patients with varicocele; group B of 66 patients without varicocele; and group C of 55 patients after varicocelectomy. The bilateral intrascrotal temperatures were recorded in the supine position and then monitored continuously in the standing position. The maximum temperatures in both positions were compared between each group. The mean temperature of the varicocele group was higher than that of the other two groups in the standing position. The authors studied the difference in temperature (delta T) due to postural change from supine to standing. The mean delta T of the left testis was +0.78 degrees C in the varicocele group, whereas it was approximately -0.5 degrees C in the other two groups. The authors conclude that deep body temperature provides a practical index of the intrascrotal temperature and is useful as one of the objective, clinical criteria for the diagnosis of varicocele.

Body Temperature↗
PubMed1989

Dual cis-acting negative regulatory elements located upstream of the mouse DNA polymerase beta gene.

A 2,200 base pair (bp) fragment containing the 5'-flanking region of the mouse DNA polymerase beta gene was placed adjacent to and upstream of the chloramphenicol acetyl transferase (CAT)-coding region of the CAT vector. A transient expression assay of CAT activity in mouse NIH/3T3 cells transfected with this recombinant plasmid or a set of its 5'-deletion derivatives was carried out to identify a cis-acting regulatory element(s) for DNA polymerase beta gene expression. Depending on the extent of the deletion, CAT activity was dramatically increased, indicating the existence of a negative regulatory region which could be divided into two distinct domains: removal of the first domain (NRE-I), nucleotides -1860 to -1580 (+1 denotes the position of 5'-most proximal transcription initiation site), caused two to three-fold stimulation of CAT activity, and removal of the second domain (NRE-II), nucleotides -828 to -456, stimulated CAT expression another two to three-fold. When an 1,864-bp segment containing these negative regulatory elements (-2190 to -327) was inserted in the plasmid carrying the simian virus 40 early promoter and enhancer-directed CAT gene, it inhibited the CAT expression relatively independently of the orientation of insertion and the distance from the promoter-enhancer. We also mapped the promoter element of the DNA polymerase beta gene to within a 133-bp DNA fragment from nucleotide position -100 to +33. Either the NRE-I region or the NRE-II region alone can inhibit DNA polymerase beta gene promoter function.

Animals↗
PubMed1989

Dermatan sulfate formation in gastrulae of the sea urchin Clypeaster japonicus.

Gastrullation of sea urchin embryos is arrested in sulfate-free sea water. This developmental arrest has been considered to be due to lack of sulfation of glycosaminoglycans in the extracellular matrix of the embryos. In the present study, we characterized a dermatan sulfate type component formed in gastrula-stage embryos of the sea urchin Clypeaster japonicus and examined the effects of sulfate deprivation on the formation. Glycosamino-glycans were prepared from gastrula-stage embryos incubated with [3H]acetate in normal and sulfate-free sea water. Enzymatic analyses indicated that embryos formed a glycosaminoglycan of the dermatan sulfate type which contained an N-acetylgalactosamine-6-sulfate-containing disaccharide as a major unit, plus a minor unidentified component. Under sulfate-free conditions, embryos formed an under-sulfated chondroitin/dermatan sulfate copolymer which mainly consisted of non-sulfate, glucuronic acid-containing (chondroitin) disaccharide units. These results suggest that sulfate deprivation diminishes not only the degree of sulfation but also the formation of L-iduronic acid-containing (dermatan) disaccharide units in dermatan sulfate in sea urchin embryos.

Acetates↗
PubMed1989

[A study of neutrophil functions in patients with chronic respiratory tract diseases].

We tested blood neutrophil functions in the patients with chronic respiratory tract diseases to study the mechanism of susceptibility to bacterial infections. Peripheral blood neutrophils were obtained from 15 healthy subjects and 14 patients including diffuse panbronchiolitis, bronchiectasis, chronic emphysema and chronic bronchitis. Seven patients suffered from the chronic P. aeruginosa infection. Firstly, neutrophil chemotaxis was determined by the method of Boyden Chamber assays using FMLP as a neutrophil chemoattractant. The number of migrated neutrophils were 239.2 +/- 65.6 cells/50 HPF in the patients group and 256.6 +/- 49.0 cells/50 HPF in the control group. Secondly, neutrophil phagocytosis against P. aeruginosa, E. coli and K. pneumoniae was determined by phagocytic activity (PA) and phagocytic index (PI). PA against each bacteria was 44.1 +/- 13.2% (P. aeruginosa), 44.8 +/- 12.3% (E. coli) and 35.8 +/- 13.6% (K. pneumoniae) in the patients group and 42.3 +/- 10.6% (P. aeruginosa), 43.0 +/- 11.9% (E. coli) and 36.3 +/- 16.0% (K. pneumoniae) in the control group. PI against each bacteria was 2.2 +/- 0.6 (P. aeruginosa), 2.1 +/- 0.3 (E. coli) and 2.6 +/- 0.9 (K. pneumoniae) in the patients group and 2.2 +/- 0.6 (P. aeruginosa), 2.2 +/- 0.4 (E. coli) and 2.5 +/- 0.6 (K. pneumoniae) in the control group. Thirdly, neutrophil bacteriocidal activity was determined by superoxide production and intracellular killing efficiency. Superoxide produced from OPZ-triggered neutrophils was 17.8 +/- 6.5 nmol/3.5 X 10(6) cells/20 min in the patients group and 20.2 +/- 5.8 nmol/3.5 X 10(6) cells/20 min in the control group, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1989

Actinomycin D affects thyrotropin-releasing hormone-induced heterogeneous forms of glycosylated thyroid-stimulating hormone in rat anterior pituitary.

Actinomycin D and cycloheximide were used to clarify the tight relationship between protein synthesis and heterogeneous carbohydrate synthesis of rat pituitary thyroid-stimulating hormone (TSH) under thyrotropin-releasing hormone (TRH) stimulation in vitro. Rat anterior pituitaries were incubated with [3H]glucosamine in the presence of TRH, cycloheximide and actinomycin D at 37 degrees C for 3 and 6 h. The TSH fraction of pituitary homogenates was obtained using affinity chromatography coupled with anti-TSH globulin, and was analyzed by isoelectric focusing. Anterior pituitary in the presence of TRH showed heterogeneous components of [3H]glucosamine-labeled TSH with 6 different isoelectric points (components I-VI). Radioactivities of the components increased with the incubation period. Cycloheximide changed these heterogeneous components. Actinomycin D also caused a striking change in the heterogeneity of pituitary [3H]glucosamine-labeled TSH: components I and II decreased and components III and IV increased as compared to the control group after a 6-hour incubation. The present study implies that actinomycin D affects the TRH-induced heterogeneous components of pituitary TSH glycosylation. The data indicate that messenger RNA is essential for the normal processing of carbohydrate synthesis of pituitary TSH.

Animals↗
PubMed1989

Plasminogen phenotypes in a Japanese population. Four new variants including one with a functional defect.

Human plasminogen (PLG) phenotypes were investigated by polyacrylamide gel isoelectric focusing followed by immunoblotting. In 5,735 plasma samples from unrelated, healthy Japanese individuals, four new variants were detected and tentatively designated PLG AOsaka, PLG BOsaka, PLG MOsaka and PLG ANara. The plasminogen concentrations and activities of the PLG phenotypes were studied. In agreement with previous studies PLG M5 was found to have a decreased activity. The new variant PLG MOsaka had a very low activity and appears to be an abnormal plasminogen with a functional defect similar to that of PLG M5.

Gene Frequency↗
PubMed1989

Alteration in bone metabolism with increasing age: effects of zinc and vitamin D3 in aged rats.

The alteration in bone metabolism with increasing age was investigated in the femoral diaphysis of male rats. Calcium content was highest in the bone from 3-week-old rats (491 +/- 13 mg/g bone ash), falling gradually with aged to 357 +/- 7 and 306 +/- 9 mg/g bone ash in 28- and 52-week-old rats, respectively. Bone zinc content increased until rats were 3 weeks of age, and thereafter remained constant. Deoxyribonucleic acid (DNA) content was highest in the bone from 1-week-old rats, and it decreased markedly with increasing age. Alkaline phosphatase and acid phosphatase activities increased up to 3 weeks, then subsequently declined with age. Thus, the retardation of bone metabolism was induced by ageing. When zinc sulfate (5.0, 10.0 and 20.0 mg Zn/kg body weight) was administered orally for 3 d to 28-week-old rats, alkaline phosphatase activity and calcium content in the femoral diaphysis was elevated markedly by all doses. The oral administration of vitamin D3 (2.0 and 20 micrograms/kg) for 3 d in 28-week-old rats did not produce an appreciable increase in bone alkaline phosphatase activity or calcium content, while 1,25-dihydroxyvitamin D3 (1.5 micrograms/kg) caused a significant increase in those biochemical indices. These results indicate that zinc and 1,25-dihydroxyvitamin D3 play a role as activators in bone metabolism of ageing rats.

Acid Phosphatase↗
PubMed1989

Stimulatory effect of calcitonin on bone formation in tissue culture.

The present investigation was undertaken to clarify the in vitro effect of synthetic [Asu1,7]eel calcitonin (CT) on bone metabolism in tissue culture. Calvaria were removed from weanling rats (3-week-old male) and cultured for periods up to 96 h in Dulbecco's Modified Eagle Medium supplemented with antibiotics and bovine serum albumin. The experimental cultures contained 1.0 to 100 ng/ml CT. All cultures were incubated at 37 degrees C in 5% CO2-95% air. Bone calcium content was increased significantly by the presence of 10 and 100 ng/ml CT. This increase was blocked by the presence of 10(-6) M cycloheximide or 10(-7) M actinomycin D. Bone alkaline phosphatase activity was significantly increased by the presence of 100 ng/ml CT for 48 and 96 h. Bone acid phosphatase activity was not altered significantly by CT (1-100 ng/ml). The incorporation of [3H]proline into the acid-insoluble residues of bone tissue was significantly increased by the presence of CT (1-100 ng/ml) for 96 h. This increase was completely blocked by the presence of 10(-7) M cycloheximide. Bone DNA content was significantly raised by the presence of 10 and 100 ng/ml CT for 96 h. Furthermore, the culture with CT (10 and 100 ng/ml) produced a significant decrease in glucose concentration in the medium. Also, CT (10 and 100 ng/ml) stimulated the production of pyruvic acid from bone tissue. These results suggest that CT had a direct stimulatory effect on bone formation and mineralization in vitro, and that the hormone stimulates energy metabolism in bone cells.

Animals↗
PubMed1989

Activation of hepatic microsomal Ca2+-adenosine triphosphatase by calcium-binding protein regucalcin.

The effect of regucalcin, a calcium-binding protein isolated from rat liver cytosol, on Ca2+-adenosine triphosphatase (ATPase) activity in hepatic microsomes was investigated. Mg2+-ATPase activity was clearly increased by the presence of 50 microM Ca2+. Regucalcin (1.0-4.0 microM) caused a remarkable elevation (about 3-fold) of Ca2+-ATPase activity. Also, Mg2+-ATPase activity was increased (about 1.6-fold) by the presence of regucalcin (2.0 and 4.0 microM). Guanosine-5'-O-(3-thiotriphosphate) (GTPrs; 10(-5) and 10(-4) M) and nicotinamide adenine dinucleotide phosphate oxidized form (NADP+; 10(-5) to 10(-3) M) or reduced form (NADPH; 10(-4) and 10(-3) M) significantly increased Ca2+-ATPase activity. These increases were not enhanced by the presence of regucalcin (2.0 microM). Of various metal ions, a comparatively low concentration of V5+ (10(-5) M) or Cd2+ (10(-6) M) significantly increased Ca2+-ATPase activity, while Hg2+, Zn2+, Cu2+ and Mn2+ did not have such an effect. Regucalcin (2.0 microM) did not enhance the effect of V5+ and Cd2+ on Ca2+-ATPase activity. The present finding, that regucalcin activates hepatic microsomal Ca2+-ATPase, suggests a cell physiological role of regucalcin as an activator in the microsomal Ca2+-pump activity. This action of regucalcin may not be influenced by other regulators.

Animals↗
PubMed1989

High-performance liquid chromatography of arachidonic acid metabolites and its application to the determination of leukotriene B4 in stimulated leukocytes.

A highly sensitive high-performance liquid chromatography with fluorescence detection for the determination of arachidonic acid metabolites is described. The metabolites are converted into corresponding fluorescent derivatives by reaction with 3-bromomethyl-6,7-methylenedioxy-1-methyl-2(1H)-quinoxalinone in the presence of potassium hydrogen carbonate and 18-crown-6 in acetonitrile. The derivatives are separated on a reversed-phase column (Inertsil ODS) with aqueous acetonitrile and detected fluorimetrically. The detection limits are 5-15 fmol at a signal-to-noise ratio of 3 in a 10-microliter injection volume. The method is applied to the determination of leukotriene B4 produced in stimulated leukocytes.

Arachidonic Acids↗
PubMed1989

Determination of 21-hydroxycorticosteroids in human urine by high-performance liquid chromatography with fluorescence detection.

A simple and sensitive high-performance liquid chromatographic method with fluorescence detection for the determination of nineteen 21-hydroxycorticosteroids is described. The corticosteroids are oxidized by cupric acetate to form the corresponding glyoxal derivatives. The derivatives are converted into fluorescent quinoxalines by reaction with 1,2-diamino-4,5-methylenedioxybenzene, a fluorogenic reagent for alpha-dicarbonyl compounds. The quinoxalines are separated within 70 min on a reversed-phase column (TSK gel ODS-120T) by stepwise elution with mixtures of methanol, acetonitrile, and 1.0 M ammonium acetate. The detection limits are 0.14-29.4 pmol at a signal-to-noise ratio of 3 in a 50-microliter injection volume. This sensitivity permits precise determination of hydrocortisone, cortisone, corticosterone, and their tetrahydro derivatives in 500 microliters of normal human urine.

Chromatography, High Pressure Liquid↗
PubMed1989

Effect of the calcium-binding protein regucalcin on the Ca2+ transport system in rat liver microsomes: the protein stimulates Ca2+ release.

The effect of the calcium-binding protein regucalcin on the Ca2+ transport system in the liver microsomes from fed rats was investigated. Ca2+ transport was assayed by the method of Millipore filtration to estimate microsomal 45Ca2+ accumulation following addition of 10 mM adenosine triphosphate (ATP). 45Ca2+ uptake was retarded by the presence of regucalcin (1.0-4.0 microM). This retardation was remarkable at 1 min after regucalcin addition, while appreciable retardation was no longer seen at 5 min. Regucalcin (2.0 microM)-induced retardation of 45Ca2+ uptake was prevented by the presence of calmodulin (5 micrograms/ml). Calmodulin alone (1 and 5 micrograms/ml) caused a significant increase in 45Ca2+ uptake at 3 min after the start of incubation. Also, regucalcin (2.0 microM)-induced retardation of 45Ca2+ uptake was completely blocked by the presence of a Ca2(+)-trapping agent, oxalate (3 mM). On the other hand, 45Ca2+, which accumulated in microsomes during 5 min after ATP addition, was markedly released by the addition of regucalcin. This release was dose-dependent (0.5-4.0 microM). Guanosine triphosphate (GTP; 10-100 microM) caused a significant release of 45Ca2+ from the microsomes. The presence of regucalcin (2.0 microM) further enhanced the GTP effect. Regucalcin (2.0 microM)-induced release of 45Ca2+ was not blocked by the presence of the protein thiol-protecting agent dithiothreitol (0.1 mM). The presence of oxalate (3 mM) completely blocked the effect of regucalcin on 45Ca2+ release from the microsomes. These results indicate that regucalcin stimulates Ca2+ release from liver microsomes, and that the protein retards the microsomal Ca2+ uptake. The present study suggests that regucalcin can regulate the Ca2+ transport system in rat liver microsomes.

Animals↗
PubMed1989

Effects of Ca2+ and V5+ on glucose-6-phosphatase activity in rat liver microsomes: the Ca2+ effect is reversed by regucalcin.

The effect of regucalcin, a calcium-binding protein isolated from rat liver cytosol, on glucose-6-phosphatase in the microsomes of rat liver was investigated. Addition of Ca2+ up to 2.5 microM to the enzyme reaction mixture caused a significant increase of glucose-6-phosphatase activity in hepatic microsomes, while Ni2+, Zn2+, Cd2+, Cu2+, Mn2+ and Co2+ (20 microM) did not have an appreciable effect. Vanadate (V5+) markedly inhibited the enzyme activity; a significant inhibitory effect was seen at 10 microM V5+. The Ca2+-induced increase of glucose-6-phosphatase activity was reversed by the presence of regucalcin; the effect was complete at 1.0 microM of the protein. Regucalcium had no effect on the basal activity of the enzyme. Meanwhile, the inhibitory effect of V5+ (10-100 microM) on glucose-6-phosphatase was not appreciably blocked by the presence of regucalcin (up to 2.0 microM). The present data suggest that hepatic microsomal glucose-6-phosphatase is uniquely regulated by Ca2+ and V5+, of various metals, and that the Ca2+ effect is reversed by regucalcin. The present study supports the view that regucalcin plays an important role as a regulatory protein in liver cell function related to Ca2+.

Animals↗
PubMed1989

[Effects in animal models of depression of lisuride alone and upon coadministration with antidepressants].

Effects of lisuride, a central dopamine and serotonin agonist of the ergot type, in animal models of depression were investigated in comparison with those of desipramine, mianserin and rolipram. Lisuride, like desipramine and mianserin, inhibited reserpine-induced hypothermia in mice (0.5-5.0 mg/kg, i.p.) and suppressed muricide in olfactory bulbectomized rats (ED50 = 0.16 mg/kg, i.p.) in a dose-dependent manner. The anti-muricidal effect was slightly enhanced by the repeated administration of 0.25 mg/kg lisuride. Lisuride (0.05-0.25 mg/kg, i.p.), like desipramine, dose-dependently reduced the duration of immobility in rats forced to swim, and this effect was antagonized by haloperidol. The reduction of immobility time was enhanced by the repeated administration of lisuride; at the same time, the ambulation in rats increased. Furthermore, the immobility-reducing effects of desipramine and rolipram were markedly enhanced by the co-administration of a low dose of lisuride (0.025 mg/kg, i.p.), which by itself had no effect on the immobility time. These results indicate that lisuride may be useful for the treatment of depression and indicate that a low dose of lisuride may enhance the clinical effectiveness of antidepressants such as desipramine.

Agonistic Behavior↗