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M Enomoto

Publications and source records attributed to M Enomoto.

At least 109 records · Page 6Linked to original sources
PubMed1990

Antithrombin-III assay without influence of heparin cofactor II.

A new biological method for the assay of plasma antithrombin-III (AT-III) activity was developed without influence from heparin cofactor II (HC-II). AT-III deficient plasma is used as a substrate and diluted prothrombin time reagent as a reaction trigger for the specific assay of AT-III. The AT-III deficient plasma is prepared by passage of plasma through a heparin-agarose column. In the presence of heparin, AT-III in the sample shows concentration dependent anticoagulant activity and calibration curve is linear on semi-logarithmic graph paper. The results of reproducibility, recoveries and correlation studies with a chromogenic assay indicate that this biological method is reliable and suitable for routine use in clinical laboratories. Influence of HC-II is minimal. The method provides several advantages over those of chromogenic substrate and fibrinogen.

Antithrombin III↗
PubMed1990

Effects of tumor necrosis factor alpha on proliferation and expression of differentiated phenotypes in rabbit costal chondrocytes in culture.

Tumor necrosis factor alpha (TNF alpha) decreased the synthesis of glycosaminoglycan (GAG) in rabbit costal chondrocytes in culture, but did not stimulate the release of GAG from cell layers. Like chondrocytes cultured in control medium, chondrocytes cultured in the presence of TNF alpha produced putative "cartilage-specific" proteoglycans identified by density gradient centrifugation under dissociative conditions. Although TNF alpha decreased the synthesis of the proteoglycans, it did not change their monomeric size, which is a marker of cartilage phenotypes. Moreover, TNF alpha did not affect the responsiveness to parathyroid hormone, insulin-like growth factor I, or transforming growth factor beta, which is known to stimulate GAG synthesis in cultured chondrocytes. TNF alpha decreased the alkaline phosphatase activity in the chondrocytes dose dependently. On the other hand, it stimulated their DNA synthesis slightly, but significantly. The stimulatory effect of TNF alpha on DNA synthesis was potentiated by fibroblast growth factor, epidermal growth factor, and fetal bovine serum. These findings suggest that in the presence of hormones and growth factors, TNF alpha promotes the proliferation of chondrocytes while suppressing their further differentiation at the stage of synthesis of cartilage-specific proteoglycans.

Alkaline Phosphatase↗
PubMed1990

Autoradiographic study of tissue distribution of [3H]ubenimex in IMC carcinoma-bearing mice.

[3H]Ubenimex was administered to IMC carcinoma-bearing mice, and the tissue distribution of the radioactivity was examined at various times after drug injection by autoradiography of glutaraldehyde-fixed tissues. Silver grains were concentrated on some of the macrophages present around the solid tumor and in thymic medulla, splenic red pulp, and mesenteric lymph node medulla. The grains were also seen at a similar concentration on some nurse cell-like cells in the thymic cortex and on some reticular cells in splenic red pulp. In the liver, grains were concentrated on the hepatocytes and bile duct epithelium. The grains were most densely concentrated on kidney proximal straight tubules, in which strong leucine aminopeptidase activity was also observed.

Animals↗
PubMed1990

Physiological role of vitamin A in growth cartilage cells: low concentrations of retinoic acid strongly promote the proliferation of rabbit costal growth cartilage cells in culture.

We have demonstrated that high concentrations of retinoic acid (RA) inhibit expression of the differentiated phenotypes of rabbit costal chondrocytes in culture [M. Takigawa et al. (1980) Proc. Natl. Acad. Sci. U.S. 77, 1481-1485]. In this study we examined the effects of low concentrations of RA on rabbit costal chondrocytes cultured in medium containing vitamin A-deficient serum. In vitamin A-deficient medium, chondrocytes isolated from growth cartilage (GC) proliferated only very slowly, and RA strongly stimulated their proliferation. This stimulatory effect was observable at a concentration of 10(-10) M RA and maximal at a concentration of 10(-8) M. RA at 10(-8) M did not change GC cells from a typical polygonal shape to fibroblast-like cells or inhibit their synthesis of type II collagen. Moreover, RA-treated cells did not synthesize type I collagen. RA inhibited glycosaminoglycan (GAG) synthesis by the cells dose-dependently, but did not change the distribution profile of proteoglycan monomers as determined by glycerol gradient centrifugation. The inhibitory action of RA on GAG synthesis was reversible: after removal of RA from the culture, the rate of GAG synthesis increased within 2 days. In contrast, resting cartilage (RC) cells proliferated well in vitamin A-deficient medium without addition of RA, and RA (10(-8) M) stimulated their proliferation only slightly. Furthermore, the inhibitory effect of RA on GAG synthesis in RC cells was much weaker than that in GC cells. These observations suggest a physiological role of RA in cartilage in stimulating the proliferation of GC cells without causing drastic change in their differentiated phenotypes.

Animals↗
PubMed1990

Heterotopic gastric mucosa of the small intestine in laboratory beagle dogs.

Out of the 365 young laboratory beagle dogs which were used in 17 toxicity bioassays, 15 cases (4.1%) were diagnosed as having congenital heterotopic gastric mucosa of the small intestine. Its incidence in the male dogs (12 cases out of 187) was higher than in the female dogs (3 cases out of 178). Grossly, the lesions were seen as an ulcerous focus of the small intestine, 25 cm to 88 cm proximal to the ileocecal valve. All of the lesions were quite similar histologically and electron microscopically to the normal gastric mucosa, which are composed of the surface mucous cells, chief cells, parietal cells, mucous neck cells and basal granulated cells of the stomach. And consequently, they were considered to be that of a congenital heterotopic tissue in the small intestine. The only morphological characteristic of these lesions different from the regular gastric mucosa was an association with the tubular structure seen in the basal region of these mucosal layers. These cells were considered to be of mucous-secreting cell origin because of secreting type III mucous evident from paradoxical concanavalin A or periodic acid Schiff stains. They seemed to be protecting the surrounding intestinal mucosa from gastric acid.

Animals↗
PubMed1989

Demonstration of receptors for parathyroid hormone on cultured rabbit costal chondrocytes.

Parathyroid hormone (PTH) receptors on cultured rabbit costal chondrocytes were demonstrated using HPLC-purified, radioiodinated [Nle8,-Nle18, Tyr34] bovine PTH-(1-34)amide. PTH binding was found to be specific for PTH agonists and antagonists and dependent on the time and temperature of incubation. Both growth cartilage (GC) cells and resting cartilage (RC) cells were shown to have a single class of saturable, high affinity PTH binding sites with a dissociation constant of 0.6-0.7 nM. However, the numbers of receptors per cell were approximately 49,000 on GC cells and 19,000 on RC cells. After crosslinking the receptors on these cells with the radioligand, one, major 125I-labeled band of 76 kDa was separated by SDS-PAGE.

Animals↗
PubMed1989

Establishment of a clonal human chondrosarcoma cell line with cartilage phenotypes.

A clonal cell line with cartilage phenotypes and tumorigenicity during more than 3 years in culture was established from a human chondrosarcoma. In sparse cultures, the clonal line, named HCS-2/8, consisted of slightly elongated polygonal cells, which proliferated with a doubling time of 3.5 days. The cells became polygonal to spherical as they became confluent. After reaching confluence, the cells continued to proliferate slowly and formed nodules, which showed metachromasia when stained with toluidine blue. The nodules were three-dimensional in structure; cells were multilayered in the surface regions, overlying a thick layer of extracellular matrix, which showed metachromasia. Electron microscopically, the cells resembling chondrocytes in vivo were surrounded by an extracellular matrix consisting of thin collagen-like fibrils with numerous fine granules, presumably of proteoglycans. The cells actively synthesized proteoglycans as determined by [35S]sulfate incorporation. The hydrodynamic size of major proteoglycan monomers synthesized by the cells was that of so-called cartilage-specific proteoglycans, as determined by glycerol gradient centrifugation. Immunostaining identified type II collagen but not type I collagen. Fluorography and immunoblotting of collagens separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis also demonstrated the synthesis of type II collagen but not type I collagen. Inoculation of HCS-2/8 cells into athymic mice resulted in the formation of chondrosarcomas that resembled the original tumor. Because of having these characters, HCS-2/8 cells should be useful not only in studies on the differentiated phenotypes of human chondrocytes but also in basic studies on the diagnosis, treatment, and etiology of human chondrosarcomas.

Aged↗
PubMed1989

Isolation and characterization of Escherichia coli hag operator mutants whose hag48 expression has become repressible by a Salmonella H1 repressor.

The expression of an Escherichia coli K12 flagellin gene, hagA48, is insensitive to the Salmonella H1 repressor (rh1+). By selecting merodiploid cells H2-rh1on-off/F'hag48 for motility in the presence of anti-H48 serum, mutants which had escaped from inhibition by the serum because of repression of their hag48 expression by rh1+ were isolated. Their nucleotide sequences were examined in the region containing the promoter, the position of which was confirmed by S1 nuclease analysis of the transcriptional initiation site. The two independently isolated mutants had the same heptamer insertion AGACGAT at a site overlapping with the promoter sequence, creating a putative operator sequence homologous to Salmonella H1, but not to H2. Other candidates for operator mutants had reduced flagellar synthesis because of mutations between the transcriptional and translational initiation sites or in the structural gene. The sequence analysis also revealed a repetitive extragenic palindrome (REP) consensus sequence and a transcriptional terminator of hag48 in a small, functionally unknown open reading frame (ORF).

Amino Acid Sequence↗
PubMed1989

Establishment from mouse growth cartilage of clonal cell lines with responsiveness to parathyroid hormone, alkaline phosphatase activity, and ability to produce an endothelial cell growth inhibitor.

Three clonal cell lines with differences in responsiveness to parathyroid hormone (PTH), alkaline phosphatase activity, and ability to produce an endothelial cell growth inhibitor(s) during more than 3 years, more than 58 passages, in culture were established from growth cartilage (GC) of mouse ribs. In sparse cultures the three clonal cell lines, MGC/T1.4, MGC/T1.17, and MGC/T1.18, all showed fibroblast-like morphology. However, as they became confluent, MGC/T1.4 cells became polygonal and then multilayered. MGC/T1.18 cells also became polygonal, but showed contact inhibition. MGC/T1.17 cells remained fibroblastic in confluent cultures and formed nodules when cultured for more than 7 days after they became confluent. These nodules calcified in the presence of beta-glycerophosphate. Glycosaminoglycan (GAG) synthesis in the parent uncloned line, MGC/T1 cells, at early passages was about 50-75% of that of primary cultures of mouse GC cells. The GAG syntheses in the three clonal lines were much lower than that of primary cultures of GC cells. Moreover, the sizes of proteoglycan monomers synthesized by these cells were not the same as that of cartilage-specific proteoglycan. The three clonal lines mainly synthesized type I collagen. PTH increased the intracellular cyclic AMP level in MGC/T1, MGC/T1.4, T1.17, and T1.18 cells: their maximal levels, observed after 2 minutes, were, respectively, about 160, 150, 70, and 200 times that of controls. The activity of alkaline phosphatase in MGC/T1.17 cells was higher than that in primary cultures of mouse GC cells, whereas those in MGC/T1 and T1.4 cells were comparable with that of GC cells, and that in MGC/T1.18 was lower. The three clonal lines, and especially MGC/T1.4, secreted a heat-stable, nondializable growth inhibitor(s) of endothelial cells into the culture medium. Because of their different properties, these cell lines should be useful for studies on endochondral ossification, the actions of PTH on skeletal cells, and anti-angiogenesis factors.

Alkaline Phosphatase↗
PubMed1989

A case of Gilbert's syndrome combined with macroamylasemia.

A 30-year-old Japanese male, who had no remarkable family history, visited our hospital with a complaint of abdominal pain, and unconjugated hyperbilirubinemia and hyperamylasemia were observed. He showed negative hemolysis tests, positive nicotinic acid test, low hepatic bilirubin UDP-glucuronyltransferase activity, decreased bilirubin diglucuronide and increased bilirubin monoglucuronide in bile, and a decrease in serum bilirubin after phenobarbital administration. He also showed high serum amylase level, low urine amylase level, and low amylase-creatinine clearance ratio. Gel filtration of serum with Sephadex G-200 revealed the existence of macroamylase. Countercurrent immunoelectrophoresis proved binding of serum amylase to lambda type IgA. From these results, the case was diagnosed as Gilbert's syndrome combined with macroamylasemia.

Adult↗
PubMed1988

Liver cell carcinomas in the medaka (Oryzias latipes) induced by methylazoxymethanol-acetate.

Medaka (Oryzias latipes) were treated with 0.3 ppm methylazoxymethanol-acetate (MAM-A) for 3 days (group I) and with 0.1 ppm MAM-A for 2 weeks (group II) and the effects on the medaka liver cells up to 6 weeks after commencement of the treatment and the induction of liver tumours at the 18th or 24th weeks were observed by light and electron microscopy. As an early effect, PAS-positive granules and basophilic liver cells appeared at the fourth or fifth week in group II. In group I, PAS-positive granules, basophilic liver cells and eosinophilic liver cells were observed from the second week. They tended to increase in number and formed aggregate bodies and basophilic liver cell foci. The aggregate bodies of PAS-positive granules resembled melano-macrophage centres (MMC). However, there were ultrastructural differences between these aggregate bodies and MMC. Basophilic liver cells contained much rough-surfaced endoplasmic reticulum and eosinophilic liver cells contained much smooth-surfaced endoplasmic retriculum and mitochondria by electron microscopical observation. Liver cell nodules appeared in 3 out of 21 fish but liver tumours were not found within 24 weeks in group II. In group I, basophilic liver cell foci progressed to liver cell nodules in 5 out of 9 fish. Furthermore, they progressed to liver cell adenomas in 3 and carcinomas in 3 of 9 fish at 18 weeks. The sequential morphological alterations observed in the present experiment were similar to those obtained in rats. Basophilic liver cell foci appeared to be an early aspect of hepatocarcinogenesis in medaka. Considering the susceptibility of medaka to the carcinogenic effect of MAM-A in a relatively short time and the low concentration of this material required for induction of tumours, medaka seems to be a useful animal for research on neoplasms and pre-screening carcinogenicity of chemicals.

Animals↗
PubMed1988

Physicochemical properties of charge isomers of recombinant human superoxide dismutase.

Recombinant human Cu2Zn2SOD expressed in Escherichia coli consisted of mainly three isomers with isoelectric points of 5.14 (A), 5.06 (B), and 4.99 (C). Each isomer was isolated by DEAE-Toyopearl chromatography and the physiochemical properties were investigated. No significant differences in chemical and spectrophotometric properties, such as specific activity, metal contents, amino acid composition, and UV and ESR spectra, were found. The result of labeling of free cysteine residues with ABD-F showed the disulfide bond to be formed between 57Cys and 146Cys in every isomer. A few differences were found in the CD spectrum around 260 nm and in the elution patterns on reverse-phase HPLC. The isoelectric points of the three isomers became the same after treatment by reduction and carboxymethylation and even after reduction only, pI of isomers tended to be at the value of component (A). These results suggest that the three isomers are identical in primary structure but slightly different in secondary or tertiary structure. These differences are probably derived from structural alterations around 111Cys.

Amino Acids↗
PubMed1988

Comparison of properties between human recombinant and placental copper-zinc SOD.

The physicochemical properties of purified recombinant human copper-zinc superoxide dismutase (r-hSOD) were compared with those of human placental copper-zinc superoxide dismutase (h-SOD). No differences were found in specific activity, metal contents, amino acid composition, and tryptic peptide map. The spectrophotometric properties including UV, ESR, and CD spectra were also similar. The result of isoelectric gel electrophoresis showed that the difference in isoelectric point (pI) was derived from acetylation of the N-terminal amino acid (alanine) in h-SOD. In SDS-polyacrylamide gel electrophoresis, both SODs showed the same behavior and enzymic activity was retained only under non-reducing conditions. ESR analysis of the denatured enzyme suggested that the high stability was derived from the structure of the active site around copper. Experiments using other metal-substituted SODs (Cu, Co in place of zinc) suggested that zinc contributed to the stability and the unique electrophoretic behavior of the enzyme.

Amino Acid Sequence↗
PubMed1988

Relation between ESR-detectable Cu(II) and superoxide dismutase activity.

The relation between ESR-detectable Cu(II) and Cu,Zn-superoxide dismutase activity was examined. The Cu(II) spin numbers per one unit of SOD were 6.26 X 10(12) (+/- 0.51 X 10(12] spins in several preparations of recombinant human Cu,Zn-SOD, native placental, and erythrocyte SOD. Measurement could be performed over a wide range of pH (4.0-10.0), preferably at temperatures below -40 degrees C. The data obtained by this method correlated well to the results obtained by the method of Fridovich et al. using the xanthine-xanthine oxidase system (correlation coefficient 0.995). The specific activity of SOD was proportional to the Cu(II) content measured by ESR, but not to the total Cu content measured by atomic absorption. This indicates that it is important to measure the Cu(II) content for determining Cu,Zn-SOD activity.

Copper↗
PubMed1988

Differential effects of 1 alpha,25-dihydroxycholecalciferol and 24R,25-dihydroxycholecalciferol on the proliferation and the differentiated phenotype of rabbit costal chondrocytes in culture.

1 alpha,25-Dihydroxycholecalciferol [1,25-(OH)2D3] stimulated the proliferation and DNA synthesis of rabbit costal growth cartilage cells in the logarithmic growth phase in culture. The stimulatory effects of 1,25-(OH)2D3 were observable at a concentration of 10(-10) M and maximal at a concentration of 10(-8) M. On the other hand, 1,25-(OH)2D3 inhibited their expression of the cartilage phenotype, as judged morphologically, histochemically, and biochemically by a decrease in glycosaminoglycan (GAG) synthesis. The inhibition of GAG synthesis was also dose dependent and observable at a concentration of 10(-10) M. 1,25-(OH)2D3 also stimulated the proliferation of resting cartilage cells and inhibited their GAG synthesis, but its effects on these cells were less than those on growth cartilage cells, suggesting that 1,25-(OH)2D3 acts more specifically on growth cartilage cells than on resting cartilage cells. 1,25-(OH)2D3 had no effect on either DNA synthesis or GAG synthesis of growth cartilage cells in confluent cultures. 24R,25-Dihydroxycholecalciferol [24,25-(OH)2D3] had no effect on proliferation, DNA synthesis, or GAG synthesis of growth cartilage cells in the logarithmic growth phase. However, 24,25-(OH)2D3 had no effect on DNA synthesis of these cells in confluent cultures, but stimulated their expression of the cartilage phenotype. The stimulatory effect was dose dependent and maximal at 10(-7) M. Since chondrocytes express their differentiated phenotype as they become confluent in culture, these results suggest that 1,25-(OH)2D3 stimulates the growth of rapidly proliferating chondrocytes with a poorly differentiated phenotype and suppresses their expression of the cartilage phenotype, while 24,25-(OH)2D3 stimulates expression of the differentiated phenotype of highly differentiated chondrocytes.

24,25-Dihydroxyvitamin D 3↗