Biomedical subjects

R Yamada

Publications and source records attributed to R Yamada.

At least 19 recordsLinked to original sources

PubMed1992

[Expandable metallic stent therapy for SVC syndrome--effects on local venous pressure, vascular diameter, symptoms, and these correlations].

To evaluate the efficacy of Z-stent therapy for SVC syndrome, we studied changes in the pressure, the diameter of stenotic lumen and the symptoms in the cases of SVC syndrome with higher pressure than 30 cmH2O at distal to the stenosis. The symptoms were classified and graded to be scored up. Immediately after the Z-stent placement into the stenotic lesions, the venous pressure distal to the stenosis decreased from 36.0 +/- 3.4 cmH2O to 12.0 +/- 12.0 cmH2O (p < 0.001), the diameter of stenotic lumen increased from 3.3 +/- 3.4 mm to 14.0 +/- 3.4 mm (p < 0.01). According to the remarkable symptomatic improvements the averaged score decreased from 6.7 to 1.3 (p < 0.01). The pressure, the diameter and the symptom scores were highly correlated each other (magnitude of gamma not equal to 0.9). Among two cases with the right atrial pressure increase by 2 cmH2O after the placement one suffered transient cardiac in compensation due to overload by reperfusion. Conclusively, the Z-stent therapy was very effective on the SVC syndrome in reducing abnormally elevated venous pressure due to the stenosis, and relieving the symptoms, while the pressure monitor was necessary.

Aged↗

PubMed1992

[Transjugular intrahepatic portosystemic shunt: a case report].

Transjugular intrahepatic portosystemic shunt (TIPS) was performed in one patient with refractory esophageal varices due to portal hypertension by liver cirrhosis. Rösch modified Z-stent was placed to keep the lumen. The shunt lowered average portal pressure from 45 to 24 mmHg, and then decompressed the esophageal varices. The shunt was patent still for three months after the creation. No significant complication was observed. This initial success of TIPS in Japan encouragingly support the safeness and effectiveness of this therapy.

Esophageal and Gastric Varices↗

PubMed1992

Induction of differentiation of the human promyelocytic cell line HL-60 by activin/EDF.

A human promyelocytic cell line, HL-60, treated with activin/EDF was found to differentiate into monocyte/macrophage-like cells. This was shown not only by morphology but by the loss of myeloperoxidase granules and the appearance of nonspecific esterase. Dose-dependent inhibition of the differentiation by follistatin, an activin-binding protein, confirmed that it was indeed caused by activin. Thus, activin/EDF exerts its effect on hematopoietic cells not only on erythroid differentiation but also on at least a part of myeloid cell differentiation.

Activins↗

PubMed1992

[A stent therapy for portal tumor thrombi. Use of Dacron sheet covered self expandable metallic stent].

We developed a method of intraportal placement of a covered stent against portal tumor thrombi. Half around a z-stent was covered with a Dacron mesh sheet. In one case with portal tumor thrombi protruding into the main portal branch, the stent was placed percutaneously-transhepatically, through a coaxial introducer. Immediately after the placement, portal vein was dilated and, which was still patent after six months. No complication has been observed.

Carcinoma, Hepatocellular↗

PubMed1992

Follistatin is a developmentally regulated cytokine in neural differentiation.

Activin acts mitogenically on P19 cells as well as being inhibitory of the differentiation of retinoic acid-treated P19 cells and some neuroblastoma cell lines. Here, we show some lines of evidence that follistatin, an activin-binding protein, is also involved in neural differentiation. Counteracting the activity of activin, addition of follistatin suppresses the anchorage-independent growth of P19 cells in soft agar and stimulates neurite outgrowth of a neuroblastoma cell line, IMR-32 cells. While activin does not seem to be expressed significantly, follistatin is demonstrated in the conditioned medium of these cells. Furthermore, the expression of follistatin in P19 cells is subject to dynamic fluctuations in response to retinoic acid treatment. These neural cells may produce follistatin in a cell stage-specific manner in order to interact with exogenously derived activin.

Activin Receptors↗

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↗