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Biomedical subjects

R Yamada

Publications and source records attributed to R Yamada.

At least 199 records · Page 11Linked to original sources
PubMed1991

Postoperative fluctuations of tissue plasminogen activator (t-PA) in aqueous humor of pseudophakes.

We studied the quantitative fluctuations of tissue plasminogen activator (t-PA) activity and antigen in aqueous humor before and after extracapsular cataract extraction and poly(methyl methacrylate) posterior chamber lens implantation. The t-PA activity level was measured by solid phase bioimmunoassay using monoclonal antibody against an epitope apart from the active site of t-PA, and the antigen by ELISA. In our patients the mean preoperative level of t-PA activity was 0.0664 +/- 0.0472 IU/ml (mean +/- SD) and of the antigen, 0.175 +/- 0.024 ng/ml. The t-PA activity level in aqueous humor was markedly decreased on the first postoperative day (0.0042 +/- 0.0037 IU/ml), recovered on the second day (0.0403 +/- 0.0251 IU/ml), and then progressively decreased from the fourth to the seventh days. The t-PA antigen level in aqueous humor increased on the first (0.366 +/- 0.108 ng/ml) and second (0.403 +/- 0.251 ng/ml) postoperative days and gradually decreased from the fourth to seventh days. Under the intracameral condition of the fibrinolytic system, various factors, e.g., serious inflammation or events affecting the balance of coagulation and fibrinolysis, may induce the decrease or depletion of t-PA activity, followed by the pupillary fibrin membrane formation. We suggest that fluctuations of t-PA activity in aqueous humor may affect fibrinous membrane formation over the IOL surface.

Aged↗
PubMed1991

Large cysts of the pineal gland: report of two cases.

Two cases of large, nontumorous cysts of the pineal gland are reported, the histopathology of which was confirmed using surgically resected specimens. Both patients were middle-aged, and the pineal cysts were found incidentally. The histopathological findings in the two cases were strikingly similar to each other and were characterized by the following points: 1) the cyst wall typically consisted of three layers, namely, collagenous fibers, glia-like cells, and normal pineal cells; 2) the cyst wall was relatively thin, approximately 100 to 300 microns in thickness; and 3) deposits of calcification almost always existed on the side of the layer of collagenous fiber. Because these findings are clearly different from those previously reported, large benign cysts of the pineal gland, or at least some of them, may constitute a new pathological entity. It is important to consider this possible pathological diagnosis when dealing with pineal cysts.

Adult↗
PubMed1990

[The movement of antineoplastic solutions in transcatheter hepatic arterial embolization].

Transcatheter hepatic arterial embolization (TAE) with gelatin sponge particles soaked in anticancer agents has been widely employed in the treatment of Hepatocellular carcinoma (HCC). The mechanism of TAE has been explained by blocking of blood flow to the tumor, however the role of anticancer agents used with embolic materials has remained unclear. The purpose of this study is to prove the role of anticancer agents used in TAE. 1) In eighteen cases of HCC and 4 cases of metastatic liver cancer, TAE was performed with gelatin sponge, anticancer agents and contrast media. The livers were examined by CT 4, 24 and 48 hours after TAE. A selective retention of contrast media containing anticancer agent in the tumor area was observed in 14 of 14 cases examined 4 hr. in 15 of 17 cases examined 24 hr and in 6 of 6 cases examined 48 hr after TAE. In the cases of metastatic liver cancer, retention of contrast media, was also observed in 4 of 4 cases examined at 24 hr and 3 of 3 cases examined 48 hr after TAE. 2) TAE was done in 12 cases of HCC by using gelatin sponge soaked in anticancer agent mixed with 99M-Tc-pertechnetate. Livers were observed by a scintillation camera 4 hr and 24 hr after TAE. A selective retention of 99M-Tc-pertechnetate in the tumor was observed in 12 of 12 cases examined 4 hr and in 3 of 3 cases examined 24 hr after TAE. 3) In one cases of HCC, hepatectomy was performed 2 days after TAE.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

D-aspartate oxidase activity and D-aspartate content in a mutant mouse strain lacking D-amino acid oxidase.

A mutant mouse strain ddY/DAO- lacks D-amino acid oxidase activity and accumulates free neutral D-amino acids in its tissues. In this study, D-aspartate oxidase activity and D-aspartate content in the tissues of these mutant mice were compared with those of normal mice. No significant difference was observed, indicating that the metabolism of acidic D-amino acids was unaffected in the mutant.

Amino Acid Oxidoreductases↗
PubMed1990

Surgical treatment of reflux stricture of the esophagus.

Ten children, aged 7 months to 15 years, with peptic esophageal stricture, were treated surgically. In four of the children, the stricture had occurred after esophageal anastomosis. Peptic stricture was diagnosed by esophagography, pH monitoring, manometry, and esophagoscopy. Barrett's esophagus was found in two children. Nine children underwent transabdominal Nissen fundoplication initially. In the first child of this series, a tight anastomotic stricture had been excised 2 weeks before fundoplication. Seven children became complaint-free within 2 or 3 months after fundoplication without any dilatation, and two children with anastomotic stricture improved after 1 or 2 postoperative dilatations. The condition of one boy, with a 6-year history of tight stricture, did not improve with repeat Nissen and subsequent dilatations. Histological examination showed proliferation of smooth muscle cells in the submucosa. A conservative surgical approach is effective for the management of peptic esophageal stricture in children, and direct surgical intervention for stricture should be attempted only in cases of stricture resistant to antireflux surgery with a long history of reflux.

Adolescent↗
PubMed1990

Association between tissue plasminogen activator and serum lipids in healthy volunteers.

The statistical association between tissue plasminogen activator (t-PA) activity, antigen, plasminogen activator inhibitor-1 (PAI-1) antigen and lipids levels in blood samples used for medical check ups in 111 volunteers attending hospital for health examinations was examined. The t-PA activity level of 111 volunteers was 0.08-0.56 ng/ml (5% trimmed range) (normal range: 0.08-0.70 ng/ml); t-PA antigen concentrations were 2.4-9.2 ng/ml (normal range: 1.0-7.0 ng/ml); PAI-1 antigen concentrations were 5.2-57.4 ng/ml (normal range: 5.2-45.0 ng/ml). The volunteers with the lowest t-PA activity in blood (group E) had higher concentrations of serum total cholesterol (P less than 0.001), triglycerides (P less than 0.001), or t-PA antigen (P less than 0.001) and lower concentrations of high-density lipoprotein cholesterol (P less than 0.001) than those having normal serum lipids and t-PA activity level (group A). These results show that t-PA activity, antigen and PAI-1 antigen in blood obtained from the healthy volunteers are influenced significantly by the concentrations of lipids in blood.

Adult↗
PubMed1990

[Balloon-occluded arterial infusion as chemotherapy in bladder cancer--long-term results].

One hundred three patients with bladder cancer underwent balloon-occluded arterial infusion. In 66 patients whose therapeutic effects could be evaluated by endoscope, CT and angiography, the anti-tumor effective rate (CR + PR) was 78.8%. In 15 patients who were not treated by trans-urethral resection or total cystectomy but BOAI, one-year cumulative survival rate was 46.7% and the two-year rate 13.3%. The longest survival period after BOAI was 7 years and 8 months. 133Xe activity of bladder tumor area in BOAI was 6.60 times higher than in simple arterial infusion. BOAI was thought to be a promising conservative treatment in advanced bladder cancer.

Aged↗
PubMed1990

[t-PA activity, antigen and PAI-1 antigen levels in blood obtained from the patients with cerebral infarction].

Tissue plasminogen activator (t-PA) produced by endothelial cells exerts a powerful effect on the course of thrombosis, embolism, or arteriosclerosis. However, the fluctuations of fibrinolytic system in the patients with cerebral infarction (CI), have yet to be demonstrated. This study was designed to investigate t-PA activity, t-PA antigen and plasminogen activator inhibitor-1 (PAI-1) antigen levels in the CI patients. The mean t-PA activity, t-PA antigen and PAI-1 levels in patients were 0.53 +/- 0.64 IU/ml, 10.9 +/- 5.2 ng/ml and 23.0 +/- 14.9 ng/ml, and the normal ranges were 0.02-0.28 IU/ml, 1.0-7.0 ng/ml and 5.3-45.0 ng/ml, respectively. Almost all the patients were plotted out to the abnormal range by scattergrams relating t-PA activity to t-PA antigen, and no daytime fluctuations of the above three parameters in the patients differed from those in normal controls. When CI patients were followed up to the 8th hospital day, abnormal fluctuations were also observed. Consequently we suggest that this information may help to attain the more progressive treatment or the preventive therapy of CI.

Adult↗
PubMed1990

[Arterial stasis chemotherapy].

"Arterial stasis chemotherapy" is a concept which summarizes administration methods of anticancer agents under the temporary blockade of the blood flow by any means. The drugs so infused is hardly diluted by blood flow, reaching the tumor tissue in high concentration and staying there much longer than that of administered by simple arterial infusion. "Arterial stasis chemotherapy" contains TAE (transcatheter arterial embolization) with gelatin sponge. TAE with ethiodol, TAE with microencapsulated anticancer drug, BOAI (balloon occluded arterial infusion), arterial administration of SMANCS/Lipiodol, intra-arterial administration of DSM (degradable starch microsphere) and so on. The authors confirmed that anticancer agents, which were soaked in gelatin sponge particles, densely stayed in the tumor for twenty hours after TAE using CT and iodinated contrast media. And we also confirmed a high level of the drug was present selectively in the tumor tissue for a longer time when it was given by BOAI than SAI using scintillation camera and Xe. After these basic studies, we applied TAE and BOAI on the patients with malignant tumors and got much better therapeutic effects than previous reports. We believe therapies based on the concept of "Arterial stasis chemotherapy" will prevail from now on.

Aged↗
PubMed1989

Administration of D-aspartate increases D-aspartate oxidase activity in mouse liver.

Oral administration of D-aspartate to mice for 2 weeks by addition of the amino acid to drinking water produced a nearly 4-fold increase in liver D-aspartate oxidase (EC 1.4.3.1) activity, whereas no increase was induced by L-aspartate administered in the same way. Administration of D-aspartate also produced a small significant increase in the kidney enzyme activity, but L-aspartate administration increased the activity as well. The enzyme activity in the brain and muscle was not affected by administration of either D- or L-aspartate. Intraperitoneal administration of D-aspartate increased the enzyme activity only in the liver, and other compounds tested, including D-glutamate and D-alanine, could not replace D-aspartate. The results indicate a specific relationship between D-aspartate and D-aspartate oxidase and suggest that the amino acid is, in fact, a physiological substrate of the enzyme.

Amino Acid Oxidoreductases↗
PubMed1989

Beneficial effects of cervical spinal cord stimulation (cSCS) on patients with impaired consciousness: a preliminary report.

Electrical stimulation of the spinal cord can be used for treatment of intractable pain and spasticity. Based on our experimental findings cervical spinal cord stimulation (cSCS) was performed on eight patients with severe brain dysfunction due to traffic accidents, pronounced vasospasm caused by subarachnoid hemorrhage or surgery of huge cerebral tumors (chordoma). After a 1 to 2 month period of stimulation, two patients became conscious and began to speak. It remains unclear whether cSCS induced the restoration of consciousness and improved neurological deficits. Although the successful results might be due to chance, cSCS might have stimulated brain function. This preliminary report shows such excellent results that further studies are warranted.

Adult↗
PubMed1989

[Therapeutic embolization of renal angiomyolipoma: a case report].

A case of bilateral renal angiomyolipoma without tuberous sclerosis is reported. A 49-year-old woman was admitted to the general practitioner with a sudden onset of severe left flank pain. An excretory urogram and ultrasonogram revealed an enlargement of the left kidney. She was subsequently referred to our clinic for further investigation and treatment. Computed tomographic scan and magnetic resonance imaging using Tl-weighted image showed several tumors with a fatty, dense area in the bilateral kidney. An arteriogram demonstrated a hypervascular renal mass with aneurysms in her left kidney. Diagnosis of bilateral renal angiomyolipoma was confirmed by percutaneous needle biopsy. Superselective embolization of the tumor was successfully performed, preserving normal renal tissue. Gelatin sponges containing Carboquone (CQ sponge) were used as embolic material. Angiomyolipoma has become relatively easy to diagnose by CT, ultrasound, MRI and so on. However, there are some cases of angiomyolipoma which are indistinguishable from renal cell carcinoma using these modes of testing. Therefore, in selecting a conservative management, we indicated that percutaneous biopsy or open biopsy should be done to confirm the results of the above procedures. Moreover, therapeutic embolization for angiomyolipoma was concluded to be very useful.

Embolization, Therapeutic↗