Biomedical subjects

R Yamada

Publications and source records attributed to R Yamada.

At least 181 records · Page 10Linked to original sources

PubMed1992

[Direct injection chemotherapy combined with arterial embolization in the treatment of liver cancers].

Direct injection chemotherapy in combination with transcatheter arterial embolization (TAE) was carried out in primary and secondary liver cancers. In this treatment, the anticancer agents dissolved in contrast media were directly injected into the tumor tissue with the echo-guided puncture needle after TAE. The dynamics of the injected drugs marked with non-ionic and water-soluble contrast media was followed up by the sequential CT studies, on which the contrast media was observed only in the tumor area in 18 out of 30 nodules from 2 to 8 weeks after the injection. The procedure is considered an effective drug delivery system to achieve a targeting chemotherapy in the liver cancers.

Antineoplastic Agents↗

PubMed1992

Functional regulation of osteoblastic cells by the interaction of activin-A with follistatin.

A high number of 125I-activin-A binding sites (an apparent Kd of 260 pM and 5,600 sites/cell) were observed on MC3T3-E1 cells, a well characterized osteoblastic cell line. Activin-A has a mitogenic effect on these cells, with the greatest influence being observed on cells in an undifferentiated state, as well as a suppressive effect on the alkaline phosphatase activity. Northern and ligand blotting analyses revealed that these osteoblastic cells produce follistatin, which was down-regulated by retinoic acid treatment. Because follistatin is an activin-A-binding protein, we suggest that activin-A modulates the function of osteoblastic cells by being regulated by follistatin during differentiation.

Activins↗

PubMed1992

Anorectal anomalies associated with Kabuki make-up syndrome.

A case report of a 3-year-old girl with Kabuki make-up syndrome (KMS) associated with anovestibular fistula is presented. To our knowledge, 62 patients with KMS have been reported in the literature, three of whom were described as having an anorectal anomaly. Including the present patient, all four KMS patients were females with anovestibular fistula.

Abnormalities, Multiple↗

PubMed1992

Presence of D-aspartate oxidase and free D-aspartate in amphibian (Xenopus laevis, Cynops pyrrhogaster) tissues.

1. This paper is the first report on the presence of D-aspartate oxidase activity and free D-aspartate in the amphibian tissues. 2. The presence of D-aspartate oxidase activity in tissues of clawed toad (Xenopus laevis) and Japanese newt (Cynops pyrrhogaster) was demonstrated by requirements for enzyme activity, selective inhibition with meso-tartrate and substrate specificity. 3. In each animal, the highest activity was found in kidney, followed by liver and brain, and no gender difference in the specific activity was observed in each tissue. 4. A small but significant amount of D-aspartate was detected in liver and kidney, irrespective of species. 5. In the newt, there was a gender difference in the hepatic and renal content of D-aspartate and not in the D-/D+L-aspartate ratio.

Amino Acid Oxidoreductases↗

PubMed1992

Determination of t-PA activity and t-PA antigen in human milk.

Although a considerable number of publications on tissue plasminogen activator (t-PA) in human milk have appeared, most investigators have determined t-PA activity using an assay on fibrin plates [1, 2, 3, 4]. We measured t-PA activity by a bioimmunoassay and t-PA antigen by ELISA using a monoclonal antibody (SP-322) [6], and estimated t-PA index ((t-PA activity, ng/ml)/(t-PA antigen, ng/ml) x 100) in human colostrum and milk to evaluate the fluctuations of post-delivery t-PA. The concentrations of t-PA activity decreased slowly related to the duration of lactation varying between days one and two hundred and ten and showed significant negative correlation with the duration (P less than 0.001). The t-PA antigen made a slow descent, followed by a reciprocal ascent of the t-PA index to the fifty eighth post-delivery day and showed significant correlations with the duration (P less than 0.001, P less than 0.05, respectively). This information suggests that a high concentration of t-PA may be released into the narrow channels of the glands functioning to maintain duct patency under the regulation of an inhibitor such as plasminogen activator inhibitor (PAI).

Colostrum↗

PubMed1992

t-PA activity and antigen in the newborn and infant.

Concentrations of tissue plasminogen activator (t-PA) activity and t-PA antigen in blood obtained from neonates were investigated in order to elucidate a fibrinolytic condition of the neonates and compare with that of the infants and children. The t-PA activity was measured by bioimmunoassay using monoclonal antibody (SP-322), which bound with an epitope nonintervening with active site of t-PA. The t-PA antigen was detected by ELISA using the same monoclonal antibody (SP-322). As a result, t-PA activity in blood from the newborn baby increased to 0.97 +/- 0.48 IU/ml at the second to the fifth day, and decreased gradually to the baseline levels of healthy adult until 15 years old. The t-PA antigen level was increased from the seventh day. These results suggests that t-PA activity in blood from the neonates may be higher concentrations than those from the infants, children and adults.

Antibodies, Monoclonal↗

PubMed1992

[Detection of anti-HCV antibody, anti-GOR antibody and autoantibodies in sera of patients with non-A, non-B liver diseases].

Anti-HCV antibody, anti-GOR antibody and autoantibodies were measured in sera of 41 patients with non-A, non-B liver diseases. Anti-HCV antibody (C100-3) was positive in 73.1% of the patients. On the other hand, anti-GOR antibody, rheumatoid factor, anti-ssDNA antibody and anti-dsDNA antibody was positive in 56%, 26.8%, 12.1% and 2.4% of the patients, respectively. In 70.7% of the patients, at least one of these four antibodies was positive. No relationship was observed in both positive rate and antibody titers among these different antibodies. On the other hand, positive rates of anti-HCV and anti-GOR antibody were higher in patients with persistently elevated serum ALT. Anti-GOR antibody appears to be a kind of autoantibody since it recognizes liver cell protein which has amino acid sequence partly similar to an epitope of HCV protein. Therefore, it could be speculated that the frequent appearance of antibodies against self constituents may be related to the chronic inflammation of the liver induced by HCV infection.

Autoantibodies↗

PubMed1992

[Clinical study on incidental renal cell carcinoma].

Of 93 patients with renal cell carcinoma treated at our hospital between January 1974 and December 1990, thirty-two cases with incidentally detected cancer were evaluated clinically and pathologically. The average age of the patients was 61 years old ranging from 39 to 84 years. There were 25 men and 7 women with a sex ratio of 3.6:1. Fourteen tumors had developed in the right kidney and 17 in the left kidney. One patient had bilateral tumors synchronously and was treated by radical nephrectomy with contralateral enucleation of the tumor. The proportion of incidental renal carcinoma has been increasing steadily; 87.5% of the cases was found by either abdominal ultrasonography or CT scan. Nineteen patients (59.4%) had a tumor smaller than 5 cm in diameter. There were 29 cases with G1 or G2 renal cancer and twenty with pT2. The five-year survival rate in the incidental cases was 52.2% with significantly better survival than in cases when metastasis was initially suspected, but there was no significant difference in survival between the incidentally found cases and the cases of symptomatic renal cancer.

Adult↗

PubMed1992

[Clinical significance of plasma catecholamines in autonomic nerve diseases].

Although it was well known that noradrenaline was secreted from the terminal of sympathetic nervous system, we supposed that plasma noradrenaline does not always indicate sympathetic nervous activity. This was the reason, why we need at least 10 ml of plasma for noradrenaline measurement and so, many plasma sample could not be collect continuously from the same person, 15 years ago. Now, plasma noradrenaline was be analyzed from 0.05 ml of plasma for single isotope radioenzymatic assay. Blood samples of noradrenaline measurements could be collected through venous catheter inserted in cubital vein every 20 min 24 hours. We can study the relationship between circadian rhythm of plasma noradrenaline and that of blood pressure, etc.

Autonomic Nervous System Diseases↗

PubMed1991

Activin receptor mRNA is expressed early in Xenopus embryogenesis and the level of the expression affects the body axis formation.

Activin is a member of the transforming growth factor beta (TGF-beta) and possesses various activities in cellular control phenomena. During Xenopus embryonic development, activin is thought to act as a natural mesoderm-inducing factor. We isolated here the Xenopus activin receptor cDNA from Xenopus tadpole cDNA library and examined the expression of the Xenopus activin receptor gene during the course of early embryonic development. The Xenopus activin receptor has an 87% homology at the level of deduced amino acid sequence with the mouse activin receptor, and using the cDNA obtained, three bands of mRNA with different lengths were detected in Xenopus embryos throughout early embryogenesis. We synthesized activin receptor mRNA in vitro and tested the effect of the injection of the mRNA into Xenopus fertilized eggs on subsequent development. When the synthetic mRNA was injected into uncleaved fertilized eggs, embryos with reduced trunk structure were formed. However, when the mRNA was injected into the ventral blastomeres at the 16-cell stage, embryos with a secondary body axis were formed. These results indicate the importance of the function of activin receptor in the regulatory mechanism for body axis formation.

Activin Receptors↗

PubMed1991

Enzymological evidence for the indispensability of small intestine in the synthesis of arginine from glutamate. I. Pyrroline-5-carboxylate synthase.

The in vivo synthesis of arginine from glutamate in mammals requires seven enzymes to cooperate. Pyrroline-5-carboxylate synthase (PCS) is the first enzyme required. In order to establish the interorgan dependency of arginine synthesis, we quantitated PCS activity in as many as 32 rat tissues and found that the activity was concentrated only in the upper small intestine. Minor activity was found in pancreas, thymus, lymph node, and some other tissues: this was confirmed by the dependency on specific substrates, the loss of activity in the presence of an inhibitor, and identifying the reduced product as proline. No difference in activity was found between male and female rats on a milligram protein basis. The strict tissue localization of PCS and the localization of other enzymes of arginine synthesis previously reported clearly indicate that the upper small intestine is an indispensable tissue for the arginine synthesis from glutamate. Many of the tissues examined showed an activity to form an unknown product from glutamate. When assayed by the previously reported radiometric assay procedure using an AG1-X8 column (acetate), the product was not separated from PC and caused false-positive activities of PCS. An improved procedure was developed to overcome this technical difficulty. The new procedure enabled us to detect even 20 pmol PC without contamination by the adjoining unknown product. A preliminary characterization of the unknown product was achieved.

Animals↗

PubMed1991

Enzymological evidence for the indispensability of small intestine in the synthesis of arginine from glutamate. II. N-acetylglutamate synthase.

We describe here a concise assay procedure for N-acetylglutamate (AGA) synthase (AGAS) and its application to an extensive study of tissue distribution of AGAS activity. Crude mitochondria from several tissues were incubated in a pair of assay mixtures with [14C]glutamate in the absence and presence of acetyl-CoA at 15 degrees C for 10 min. Anionic components including [14C]AGA were first isolated from glutamate by a cation exchanger column. In order to remove anionic contaminants such as succinate, the AGA was converted to glutamate enzymatically by aminoacylase, and then the glutamate was isolated by cation exchange chromatography and counted. Recoveries were corrected individually. The difference between the pair incubations was taken as the activity. An extensive survey of AGAS activity in rats showed that, although the liver expressed the highest activity, the small intestine, testis, lung and submaxillary gland also exhibited considerable activity. Sexual differences in activity were not found in the liver and small intestine. We also detected activity in the human small intestine for the first time. Optimization of incubation temperature and time and the presence of arginine in an assay mixture was essential and we demonstrated that the AGAS reaction with crude mitochondria as an enzyme source was unstable without arginine and at higher temperatures. This procedure appears suitable for studying the physiological and nutritional role of AGAS in non-hepatic tissues. In the accompanying paper we applied this procedure to study the ontogeny of AGAS in developing rat tissues.

Acetyltransferases↗

PubMed1991

[A study of new retrievable expandable metallic stent].

The authors improved retrievable expandable metallic stent (REMS), instead of the nylon suture, the REMS was connected with the stainless steel thread. Under fluoroscopy the stainless steel thread of the shrinking body could be observed and was strong enough to retract the placed stent, then the stent could be removed by the stainless steel hook. We placed the REMS in the I.V.C. of canine, and removed them after one week placement, we could not remove them after two weeks placement. This study suggested that the REMS was considered to be useful and safe for clinical application.

Animals↗

PubMed1991

Administration of D-alanine did not cause increase of D-amino acid oxidase activity in mice.

D-amino acid oxidase (DAAO) activity was not altered in the liver and kidney by oral administration of D-alanine to adult mice. The enzyme was apparently not induced by the enteric microflora either, since the enzyme activity in the liver and kidney of germ-free mice was not different from that of specific-pathogen-free mice. The times of appearance of DAAO activity and of free D-amino acids in the kidney were elucidated using suckling mice. DAAO activity started to increase 7 days after birth, and reached almost the adult level by 28 days. The content of free neutral D-amino acids also increased with age, in a similar fashion. A possible conclusion is that the enzyme activity normally increases during this period, to eliminate the free D-amino acids which have increased with age in the suckling mice. Consequently, the administration of D-alanine had no further effect in increasing enzyme activity.

Alanine↗

PubMed1991

Expression of mRNA for activin-binding protein (follistatin) during early embryonic development of Xenopus laevis.

Follistatin is a specific activin-binding protein and is supposed to control activin functions. During Xenopus embryonic development, activin is thought to act as a natural mesoderm-inducing factor. We isolated here the Xenopus follistatin cDNA from Xenopus ovary cDNA library and studied the expression of Xenopus follistatin gene during the course of early embryonic development. The Xenopus follistatin has an 84% homology at the level of deduced amino acid sequence with human and porcine follistatin. Its 3.5 kb mRNA is first expressed at the gastrula stage, when the expression of activin mRNA becomes first detectable, and increased thereafter. Another species of 2 kb mRNA become detectable from early neurula and also increased dramatically in tadpole. These results suggest that the follistatin acts also as a regulator of activin in inductive interactions during amphibian embryonic development.

Amino Acid Sequence↗

PubMed1991

Rat liver polysome N alpha-acetyltransferase: isolation and characterization.

Rat liver polysome N alpha-acetyltransferase has been purified to homogeneity by a four-step procedure that utilizes ammonium sulfate precipitation, gel filtration, hydroxylapatite chromatography, and Mono Q ion exchange chromatography. The enzyme is greatly stabilized by the inclusion of EDTA and 0.01% deoxycholate in the isolation buffers. The purified enzyme has a native molecular weight of 190,000 and a subunit molecular weight of 95,000, suggesting that it is a homodimer. The enzyme shows a pH optimum of 8.0 and is strongly inhibited by Cl-, I-, SCN-, and ClO4- and to a lesser degree by sulfate and acetate. It is unaffected by phosphate, citrate, and F- and by Na+ and K+; NH4+ is partially inhibitory. The enzyme is also sensitive to iodoacetic acid. It is generally more similar to yeast N alpha-acetyltransferase [Lee, F.-J. S., Lin, L.-W., & Smith, J. A. (1988) J. Biol. Chem. 263, 14948-14955] than to the hen oviduct enzyme, which contains a 7S RNA subunit [Kamitani, K., & Sakiyama, F. (1989) J. Biol. Chem. 264, 13194-13198], although the amino acid compositions are quite different.

Acetyltransferases↗

PubMed1991

Rat liver polysome N alpha-acetyltransferase: substrate specificity.

The substrate specificity of polysome rat liver N alpha-acetyltransferase (NAT) has been examined by utilizing a series of synthetic and natural substrates that has been systematically altered with respect to N-terminal sequence and length. Families of peptides of the structure S-Y-S-G-G-L-L-L were generated by successively replacing the N-terminal serine, the penultimate tyrosine, and the antepenultimate serine with all 19 commonly occurring amino acids, which were then assessed for their reactivity with the rat liver enzyme. Only peptides with N-terminal serine, alanine, methionine, leucine, and phenylalanine were modified. Glycine, lysine, arginine, valine, isoleucine, and tryptophan in the second position are (with N-terminal serine) strongly inhibitory, and proline completely blocks modification. Third-position substitutions have less of an effect on NAT activity with glycine, aspartic acid, glutamic acid, and tryptophan being most inhibiting (with N-terminal Ser-Tyr). These observations are generally in agreement with in situ modifications although there are some significant differences particularly with respect to the amino-terminal residues. Optimal chain length was determined to be 10-11 residues with either synthetic peptides of the structure S-Y-S-(G)n-L-L-L or adrenocorticotropin (ACTH) sequences ranging from 8 to 39 residues. The ACTH peptides were generally found to be severalfold better substrates than the corresponding synthetic ones. Activity was not affected by increased chain length beyond approximately 17 residues. These data support the view that polysome-catalyzed N alpha-acetylation occurs as a cotranslational event on nascent chains of about 20-40 amino acids in length.

Acetylation↗

PubMed1991

Molecular cloning of a cDNA of a camptothecin-resistant human DNA topoisomerase I and identification of mutation sites.

Camptothecin (CPT), a plant alkaloid with antitumor activity, is a specific inhibitor of eukaryotic DNA topoisomerase I. We have previously isolated and characterized a CPT-resistant topoisomerase I isolated from a CPT-resistant human leukemia cell line, CPT-K5. cDNA clones of topoisomerase I were isolated from the CPT-resistant and the parental CPT-sensitive cell lines, respectively. Sequencing of the clones identified two mutations in the cDNA isolated from the resistant cells, which cause amino acid changes from aspartic acid to glycine at residues 533 and 583 of the parental topoisomerase I. When the CPT-K5 topoisomerase I was expressed in E. coli as a fusion protein with Staphylococcal Protein A fragment, the activity was resistant to CPT at a dose level up to 125 microM, whereas the parental fusion protein was sensitive to CPT as low as 1 microM. The resistance index (greater than 125) of the CPT-K5 fusion topoisomerase I is similar to that of the native CPT-K5 topoisomerase I. These results indicate that either or both of the two amino acid changes identified in the mutant enzyme is responsible for the resistance to CPT.

Amino Acid Sequence↗