Biomedical subjects

Tatsuya Takayama

Publications and source records attributed to Tatsuya Takayama.

6 recordsLinked to original sources

PubMed2003

Thymidine phosphorylase and dihydropyrimidine dehydrogenase in renal cell carcinoma: relationship between histological parameters and chemosensitivity to 5-fluorouracil.

OBJECTIVES: Thymidine phosphorylase (TdR-Pase) and dihydropyrimidine dehydrogenase (DPD) are thought to be key enzymes in the metabolic pathway of 5-fluorouracil (5-FU). Theoretically, cancer cells which have high TdR-Pase activity and/or low DPD activity should be sensitive to 5-FU. TdR-Pase is also known to have angiogenic activity which helps tumor progression and metastasis. On the other hand, little is known concerning the relationship of DPD activity with clinical malignant potential in renal cell carcinoma (RCC). In this study, we measured both TdR-Pase and DPD activities in surgically obtained RCC tissues and examined the relationship between these enzymatic activities and histological parameters. In addition, the results of in vitro chemosensitivity testing were also analyzed to determine whether TdR-Pase and/or DPD activity in carcinoma cells can predict the efficacy of 5-FU. METHODS: RCC tissues from 53 patients were obtained. TdR-Pase and DPD activities were measured by ELISA and radioenzyme assay, respectively. Sensitivity to 5-FU was assessed by histoculture drug response assay (HDRA), an in vitro chemosensitivity test, for 20 of the 53 specimens. RESULTS: Both TdR-Pase and DPD activities of RCC increased with histological grade. There was a significant positive correlation between the TdR-Pase activity and 5-FU sensitivity. In addition, a stronger positive correlation was found between TdR-Pase / DPD ratio and 5-FU sensitivity. DPD exhibited no correlation with 5-FU sensitivity. CONCLUSIONS: The activity of both enzymes increased with malignant potential of RCC. TdR-Pase appeared to be the enzyme regulating activation of 5-FU in RCC.

Antimetabolites, Antineoplastic↗

PubMed2003

Primary prostatic endodermal sinus tumor (yolk sac tumor) combined with a small focal seminoma.

We report on a primary endodermal sinus tumor (EST) (yolk sac tumor) combined with a focal seminoma of the prostate occurring in a 24-year-old man. The prostate was widely infiltrated with neoplasms that penetrated the capsule and invaded into the bladder wall and urethra. Most areas of the tumor were composed of papillary and glandular epithelium in the fibrous or myxoid stroma. Schiller-Duval bodies and periodic acid-Schiff-positive hyaline bodies were focally present. In addition to yolk sac tumor, solid nests of seminoma were found in some areas. Immunohistochemistry using specific antibodies for alpha-fetoprotein and cytokeratin showed positive reaction on the EST portion, and placental alkaline phosphatase revealed positive staining in the seminoma portion and a part of EST. Tumor cells exhibited negative staining for prostate-specific antigen, prostatic acid phosphatase, carcinoembryonic antigen, vimentin, chromogranin A, and human chorionic gonadotropin. Despite radical surgery and ordinary cisplatin-based chemotherapy, the patient died 8 months after operation. At autopsy, only EST elements had metastasized to the lungs, liver, and brain, and no tumors were found in either testis. To our knowledge, this is the first reported case of a primary EST combined with a focal seminoma in the prostate.

Adult↗

PubMed2003

Control of oxalate formation from L-hydroxyproline in liver mitochondria.

Serine:pyruvate/alanine:glyoxylate aminotransferase (SPT/AGT) is largely located in mitochondria in carnivores, whereas it is entirely found within peroxisomes in herbivores and humans. In rat liver, SPT/AGT is found in both of these organelles, and only the mitochondrial enzyme is markedly induced by glucagon. Although SPT/AGT is a bifunctional enzyme involved in the metabolism of both L-serine and glyoxylate, its contribution to L-serine metabolism is independent of mitochondrial or peroxisomal localization (Xue HH et al., J Biol Chem 274: 16028-16033, 1999). Therefore, the species-specific and food habit-dependent organelle distribution might be required for proper metabolism of glyoxylate at the subcellular site of its formation. Glyoxylate formation from glycolate and that from L-hydroxyproline have been shown to occur in peroxisomes and mitochondria, respectively. The present study found that urinary excretion of oxalate was markedly increased when a large dose of L-hydroxyproline or glycolate was administered to rats. Oxalate formation from L-hydroxyproline but not that from glycolate was significantly reduced when mitochondrial SPT/AGT had been induced by glucagon. The hydroxyproline content of collagen is 10 to 13%, and collagen accounts for about 30% of total animal protein; therefore, these results suggest that an important role of mitochondrial SPT/AGT in carnivores is to convert L-hydroxyproline-derived glyoxylate into glycine in situ, preventing undesirable overflow into the production of oxalate.

Animals↗

PubMed2003

[Laparoscopic adrenalectomy using telementoring system].

We report on our experience in telementoring during laparoscopic adrenalectomy. An experienced laparoscopic surgeon supervised a less experienced surgeon from a control room about 100 meter away. Mentoring was accomplished over a fiber optic cable employing real-time video imaging, two-way audio communication, OES ImageTrac Video System used to control the laparoscopic image, and a telestrator. The patient was a 52-year-old male with primary aldosteronism due to a left adrenal adenoma 2 cm in diameter. The procedure was successfully performed in 195 minutes with minimal blood loss. The patient recovered without complications and returned home on postoperative day 7. As broadband telecommunication expands, telementoring will become an important method for the training and supporting of laparoscopic surgery.

Adrenalectomy↗

PubMed2002

Thymidine phosphorylase activity in renal cell carcinoma: relationship between histological parameters and chemosensitivity to fluorouracil-related drugs.

Thymidine phosphorylase (TdR-Pase) is an essential enzyme in the metabolism of fluorouracil-related drugs and is also a potent angiogenic factor. We measured the TdR-Pase activity in human renal cell carcinomas (RCCs) to assess the relationship between TdR-Pase activity and the degree of tumor malignancy. We also investigated the relationship between TdR-Pase activity and chemosensitivity to fluorouracil-related drugs. A total of 61 RCC tissue specimens and 39 normal kidney tissue specimens were obtained. TdR-Pase activity was measured by enzyme-linked immunosorbent assay. The in vitro histoculture drug response assay was also performed to examine tumor sensitivity to 5-fluorouracil (5-FU) and doxifluridine (5'-DFUR). The TdR-Pase activity of RCCs was 13-fold that of the normal tissues. Activity increased with histological grade, and,was significantly higher in high-stage tumors (T3 or higher). TdR-Pase activity exhibited a significant positive correlation with sensitivity to 5-FU and 5'-DFUR. High TdR-Pase activity in human RCC was confirmed to predict high tumor grade and stage. RCCs with high TdR-Pase activity were also sensitive to FU-related drugs.

Antimetabolites, Antineoplastic↗

PubMed2002

[Repeat prostate biopsy in patients with previous negative biopsies].

We retrospectively analyzed the results of 104 patients who underwent a second prostate needle biopsy. Between January 1993 and September 2000, 654 needle biopsies were performed and cancer was found in 239 patients. Among the other 415 patients, 104 patients underwent a second biopsy. The average prostate specific antigen (PSA) value was 9.6 ng/ml (2.0-30.9) (Tandem R conversion value). Cancer was detected in 16 out of 104 cases (15%) at the second biopsy, 4 out of 39 (10%) at the third biopsy, and 3 out of 10 (30%) at the fourth biopsy. The age, PSA value, digital examination, echography, and magnetic resonance imaging (MRI) were not helpful in distinguishing the patients with prostate cancer and atypical histological findings at the previous biopsy were the most important information. Among the 9 patients who showed atypical findings at the previous biopsy, 6 (67%) had cancer.

Aged↗