Biomedical subjects

H Oyama

Publications and source records attributed to H Oyama.

At least 37 records · Page 2Linked to original sources

PubMed2000

Molecular cloning, sequencing, and expression in Escherichia coli of the gene encoding a novel 5-oxoprolinase without ATP-hydrolyzing activity from Alcaligenes faecalis N-38A.

The gene encoding a novel 5-oxoprolinase without ATP-hydrolyzing activity from Alcaligenes faecalis N-38A was cloned and characterized. The coding region of this gene is 1,299 bp long. The predicted primary protein is composed of 433 amino acid residues, with a 31-amino-acid signal peptide. The mature protein is composed of 402 amino acid residues with a molecular mass of 46,163 Da. The derived amino acid sequence of the enzyme showed no significant sequence similarity to any other proteins reported so far. The 5-oxoprolinase gene was expressed in Escherichia coli by using a regulatory expression system with an isopropyl-beta-D-thiogalactopyranoside-inducible tac promoter, and its expression level was approximately 16 mg per liter. The purified enzyme has the same characteristics as the authentic enzyme, except for the amino terminus, which has three additional amino acids. The enzyme was markedly inhibited by p-chloromercuribenzoic acid, EDTA, o-phenanthroline, HgCl(2), and CuSO(4). The EDTA-inactivated enzyme was completely restored by the addition of Zn(2+) or Co(2+). In addition, the enzyme was found to contain 1 g-atom of zinc per mol of protein. These results suggest that the 5-oxoprolinase produced by A. faecalis N-38A is a zinc metalloenzyme.

Adenosine Triphosphate↗

PubMed2000

Expression and secretion of scytalidopepsin B, an acid protease from Scytalidium lignicolum, in yeast.

An expression and secretion system for scytalidopepsin B, an acid protease from Scytalidium lignicolum, was constructed in yeast. Saccharomyces cerevisiae AH22 was transformed with an yeast-E. coli shuttle vector, pAM82, in which an yeast invertase signal segment and the cDNA encoding the pro- and mature enzyme regions were inserted. The transformant was found to secret a pepstatin-insensitive acid protease, when cultured aerobically in a low phosphate (Pi) medium. Amino terminal amino acid sequencing analysis indicated that the recombinant acid protease was accurately processed and secreted as a mature form.

Amino Acid Sequence↗

PubMed2000

[A case of epithelial membrane antigen-positive leiomyosarcoma of the urinary bladder].

A 41-year-old woman was admitted with gross hematuria and pain on urination. Cystoscopy showed a huge and lobulated submucosal non-papillary bladder tumor. Pelvic computed tomography demonstrated a heterogeneous and enhanced lobulated mass, 8 cm in diameter, with extravesical invasion but there appeared to be no metastatic lesions. Transurethral biopsy revealed leiomyosarcoma pathologically. Total cystectomy and construction of an ileal conduit were performed. The tumor was histologically diagnosed as leiomyosarcoma. Immunohistochemical studies revealed the tumor to be positive for epithelial membrane antigen (EMA) and muscle actin but negative for desmin, and S-100. We reviewed 102 cases of vesical leiomyosarcoma reported in Japan. Among these 102 cases, there were no EMA-positive cases. Immunohistochemical and electromicroscopic evaluation should be performed to evaluate this disease.

Adult↗

PubMed2000

Enhanced video image guidance for biopsy using the safety map.

We present the system design and the methods of video-based guidance to assist with brain tumor biopsy procedures. The system comprises of a three-dimensional (3-D) position sensor, a CCD camera, a liquid crystal display (LCD) and a graphics computer equipped with a video capture board. The markers for positional measurement are attached to the CCD camera, a surgical tool, and the patient head. In order to be integrated into the camera-viewing capacity, 3-D images of the head and guidance indicators are visualized to form a life like video image. For reliable guidance, we also use the surgical plan, called the "safety map", which is a sphere surface highlighting the covering area of anatomically significant tissues and obstacles around the target for the indication of the biopsy needle's insertion starting-point. The safety map can be visualized in exactly the same way as it would be in a real life situation. The preliminary experiments were performed at the National Cancer Center. A high degree of flexibility in terms of views was created by using general apparatuses which are a CCD camera and a LCD. The display of the safety map enabled a successful completion of both craniotomy and biopsy needle insertion procedures.

Biopsy, Needle↗

PubMed1999

Identification of catalytic residues of pepstatin-insensitive carboxyl proteinases from prokaryotes by site-directed mutagenesis.

Pepstatin-insensitive carboxyl proteinases from Pseudomonas sp. (PCP) and Xanthomonas sp. (XCP) have no conserved catalytic residue sequences, -Asp*-Thr-Gly- (Asp is the catalytic residue) for aspartic proteinases. To identify the catalytic residues of PCP and XCP, we selected presumed catalytic residues based on their high sequence similarity, assuming that such significant sites as catalytic residues will be generally conserved. Several Ala mutants of Asp or Glu residues were constructed and analyzed. The D170A, E222A, and D328A mutants for PCP and XD79A, XD169A, and XD348A mutants for XCP were not converted to mature protein after activation, and no catalytic activity could be detected in these mutants. The specificity constants toward chromogenic substrate of the other PCP and XCP mutants, except for the D84A mutant of PCP, were similar to that of wild-type PCP or XCP. Coupled with the result of chemical modification (Ito, M., Narutaki, S., Uchida, K., and Oda, K. (1999) J. Biochem. (Tokyo) 125, 210-216), a pair of Asp residues (170 and 328) for PCP and a pair of Asp residues (169 and 348) for XCP were elucidated to be their catalytic residues, respectively. The Glu(222) residue in PCP or Asp(79) residue in XCP was excluded from the candidates as catalytic residues, since the corresponding mutant retained its original activity.

Amino Acid Sequence↗

PubMed1999

Extragonadal germ cell tumor of the prostate associated with Klinefelter's syndrome.

PURPOSE: We report on a case of extragonadal germ cell tumor of the prostate associated with Klinefelter's syndrome. METHODS/RESULTS: The patient was a 33-year-old man. A transrectal prostate biopsy suggested combined germ cell tumor (yolk sac tumor + teratoma). Because there was no tumor except from the prostate, we considered this case to be a primary extragonadal germ cell tumor of the prostate. The prostate tumor responded to systemic chemotherapy with cisplatin, vinblastine and bleomycin and elevated lactate dehydrogenase and alpha-fetoprotein levels normalized. In addition to chemotherapy, the patient also underwent radiation therapy. CONCLUSION: The patient has survived for approximately 4 years since the diagnosis.

Adult↗

PubMed1999

Expression pattern of chemoresistance-related genes in human malignant brain tumors: a working knowledge for proper selection of anticancer drugs.

BACKGROUND: In addition to traditional modalities such as surgical intervention and radiotherapy, chemotherapy is a common therapeutic method for human malignant brain tumors. However, the effectiveness of chemotherapy is frequently hampered by cancer cell chemoresistance, resulting in an unsatisfactory outcome. To overcome this disadvantage, the proper selection of efficacious anticancer agents is required. METHODS: The expression levels of chemoresistance-related genes, MGMT, mdr1, MRP, MTIIA and GST-pi, in 28 surgical specimens of human brain tumors and in 10 human glioma cell lines were examined by Northern blot analysis. In addition, the SD10 values of human glioma cell lines against ACNU, CDDP, ADM and VP16 were estimated by a cell survival assay. RESULTS: The expression levels of each of the chemoresistance-related genes, except MRP, were generally higher in brain tumors than those in non-neoplastic brain tissues. MGMT expression correlated exclusively with ACNU resistance in all glioma cell lines examined (p = 0.0002). The transcriptional level of mdr1 in the tumor cells correlated with the SD10 values of VCR (p = 0.04) and ADM (p = 0.034). In contrast, the expression levels of MTIIA and GST-pi did not correlate with resistance to any of the drugs tested. A correlation of MRP mRNA expression with multidrug resistance was not apparent in the 10 cell lines tested. CONCLUSIONS: The data indicate that knowledge of the expression levels of MGMT and mdr1 may be particularly useful for a more rational selection of drugs which are not influenced by these resistance genes and which have improved efficacy against human brain tumors.

Antigens, CD↗

PubMed1999

An endothelial nitric oxide synthase inhibitor aggravates CDL-induced acute pancreatitis in rats.

To clarify the role of nitric oxide (NO) in the development and progression of acute pancreatitis, we investigated the effect of different NO synthase inhibitors and NO donors on experimental pancreatitis in rats. Closed duodenal loop (CDL)-induced pancreatitis was produced in male Wistar rats, and the animals were treated with normal saline, the NO-synthase substrate L-arginine, the NO donor S-nitroso-N-acetylpenicillamine, aminoguanidine, which is a more powerful inhibitor of inducible NO synthase (iNOS) than is endothelial NO synthase (eNOS), and N-nitro-L-arginine methyl ester (L-NAME), a more powerful inhibitor of eNOS than of iNOS. All drugs were infused intravenously during a period of 6 or 12 h in each group. Pancreatic tissue was removed at 6 and 12 h after creating the CDL. L-Arginine, S-nitroso-N-acetyl-penicillamine, and aminoguanidine treatment had no effect on the elevation of serum pancreatic enzymes, whereas L-NAME administration significantly exacerbated their elevation. Pathologically, L-NAME treatment resulted in a significantly worse histologic score at 6 and 12 h, especially in terms of the degree of hemorrhage, acinar cell necrosis, and microvascular thrombosis. Addition of L-arginine clearly reversed the effect of L-NAME. Neither the NO substrate nor NO donor could inhibit the progression of hemorrhagic pancreatitis in CDL-induced pancreatitis. Aminoguanidine had no effect on the severity of the pancreatitis. We therefore concluded that NO production by eNOS may play a significant role in preventing the development and progression of acute pancreatitis.

Acute Disease↗

PubMed1999

Purification and characterization of a novel 5-oxoprolinase (without ATP-hydrolyzing activity) from Alcaligenes faecalis N-38A.

A novel type of 5-oxoprolinase was found in a cell extract of strain N-38A, which was later identified as Alcaligenes faecalis. The enzyme in the cell extract was purified to a homogeneous state with a yield of 16.6%. The molecular weight of the purified enzyme was estimated to be 47,000 by both sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration, suggesting that the enzyme is a monomeric protein. The enzyme specifically catalyzed a decyclization of L-pyroglutamate without hydrolyzing ATP and also without any requirements for metal ions such as Mg2+ and K+. The optimal pH for the decyclization was 7.4. The reaction was reversible. The equilibrium constant of the reaction, Keq = [L-glutamate]/[L-pyroglutamate], was evaluated to be approximately 0. 035, which indicates that the reaction tends to form L-pyroglutamate. The amino-terminal amino acid sequence of the enzyme was H-Glu-Pro-Arg-Leu-Asp-Thr-Ser-Gln-Leu-Tyr-Ala-Asp-Val-His-Phe-. No protein with a similar sequence was found in the DNASIS database. Based on these data, it was strongly suggested that the enzyme described here is a novel type of 5-oxoprolinase.

Journal Article↗

PubMed1999

[Open surgery for pontine hemorrhage: experience in 3 cases].

Experience in three pontine hemorrhage cases which were treated by open surgery is recorded here. They were operated on by trans-fourth ventricular, subtemporal transtentorial on retromastoid suboccipital approaches. The neurological symptom improved noticeably in one case who was operated on through the retromastoid suboccipital approach seven days after the onset. The pontine hemorrhage can even be cured with open surgery which is performed in the early stage and through the operative approach.

Aged↗

PubMed1999

[The relationship between coagulation time and bilateral occurrence in chronic subdural hematoma].

The relationship between the bilateral occurrence and coagulation time was analyzed in 137 cases of chronic subdural hematoma. Bilateral chronic subdural hematomas more frequently happened in the patient with coagulation time elongation beyond the normal control. This tendency was significant in the non-traumatic group and bilateral subdural hematomas were found in: 45% in prothrombin time (PT)-elongated group vs 10.3% in non-elongated group and 38.9% in activated partial thromboplastin time (aPTT)-elongated group vs 14.6% in non-elongated group. The ratio of PT and aPTT coagulation time against the normal control was significantly larger in the bilateral group than in the unilateral group. The ratio was as follows: PT ratio was 1.056 in bilateral group and 0.995 in unilateral group. aPTT ratio was 1.051 in bilateral group and 0.954 in unilateral group. Furthermore the bilateral hematomas tended to happen in hemodialysis cases, and in patients on warfarin or anti-platelet drugs. Bilateral hematomas were found in 41.7%, 37.5% and 33.3% respectively. The ratio of PT and aPTT coagulation time was as follows: PT ratio was 1.040 in hemodialysis cases and 1.082 in warfarin-applicated cases. aPTT ratio was 1.022 in hemodialysis cases and 1.055 in warfarin-applicated cases. These results suggest that the suppressed coagulation ability and platelet function are involved in the genesis of bilateral chronic subdural hematomas.

Aged↗

PubMed1999

[Percutaneous resection of renal pelvic fibroepithelial polyp with medullary sponge kidney: a case report].

Benign polyp of the renal pelvis is extremely rare. We report a case of fibroepithelial polyp in the renal pelvis complicated with medullary sponge kidney successfully treated by percutaneous resection. The patient had recurrent bilateral renal stones because of medullary sponge kidney. Percutaneous resection of renal pelvic polyps was carried out through a 26 Fr Amplatz sheath using a 24 Fr resectoscope. Pathological diagnosis was a fibroepithelial polyp. The etiology of this polyp was suggested to be chronic irritation of renal stone.

Adult↗

PubMed1999

[Ultrasonogram of carotid artery in endoarterectomy patients].

Ultrasonograms of the carotid artery were compared with the intraoperative finding of atheroma plaque in terms of stenosis, fragility, ulceration and calcification. Soft type, intermediate type and these mixed type plaques were fragile plaques in almost all cases. All hard type plaques were tough plaques. The detection of stenosis and calcification was satisfactory, however that of ulceration was not sufficient. The stenotic lesions frequently existed in bilateral carotid arteries and the intima was easy to become thick even after the endoarterectomy. The ultrasonogram was thought to be the essential study for the carotid artery lesions.

Aged↗

PubMed1998

Reirradiation of brain and skull base tumors with fractionated stereotactic radiotherapy.

PURPOSE: We evaluated the feasibility of fractionated stereotactic radiotherapy for small intracranial recurrences after conventional radiotherapy. METHODS AND MATERIALS: Nineteen patients who had initially undergone conventional radiotherapy to intracranial lesions, receiving a median total dose of 50 Gy in 5 weeks, were retreated with stereotactic radiotherapy for their recurrences and received a median total dose of 42 Gy in seven fractions over 2.3 weeks. RESULTS: Of the 19 patients, 15 achieved local control 3-51 months after reirradiation. No patient suffered from acute reaction, but one patient with a history of extensive radiotherapy developed progressive radionecrosis 9 months after reirradiation. CONCLUSIONS: Fractionated stereotactic radiotherapy of intracranial recurrences appears to be effective in achieving in local control with negligible morbidity. We believe it merits further investigation in a prospective study.

Adult↗

PubMed1998

Effects of glucose in drinking water on the changes in whole blood viscosity and plasma osmolality of broiler chickens during high temperature exposure.

This study was conducted to elucidate the influence of glucose in drinking water on whole blood viscosity and plasma osmolality of broilers during high temperature exposure. Two groups of birds, which had ad libitum access to either a 4% glucose-water solution (Group G) or tap water (Group W), were exposed simultaneously to 30 C from 0300 h for 12 h each day for 3 d. During the experimental period, Group G birds had greater metabolic energy intake and body weight gain than Group W. Hematocrit and whole blood viscosity decreased significantly at 30 C compared to controls at 20 C in Group W, whereas, in Group G, no changes were found for these two variables. Plasma osmolality also decreased at 30 C compared to 20 C in Group W, whereas no change was noted in this variable in Group G. However, at 20 C, plasma osmolality was significantly higher in Group W than in Group G, but no difference was observed between the two groups at 30 C. Plasma protein concentration decreased during exposure to 30 C in both groups, but the decrease tended to be greater in Group W than in Group G. These results suggest that glucose intake may alleviate the influence of heat stress on whole blood viscosity and plasma osmolality.

Animals↗

PubMed1998

Nucleotide sequence of the gene encoding the precursor protein of pepstatin insensitive acid protease B, scytalidopepsin B, from Scytalidium lignicolum.

A chromosomal DNA of Scytalidium lignicolum was digested with Sau3AI. The digest was self-ligated and amplified by inverse PCR procedure using primers designed based on the nucleotide sequences of up- and down-stream regions of an intron present in the scytalidopepsin B gene. Analysis of the nucleotide sequence of PCR product (700 bp) showed that the enzyme is synthesized as a precursor protein consisting of the prepro- and mature enzyme regions. The deduced amino acid sequence was highly similar to those of aspergillopepsin A and recently reported endothiapepsins B and C, but quite different from those of pepstatin-insensitive bacterial acid proteases and the pepstatin-sensitive aspartic protease family.

Amino Acid Sequence↗

PubMed1998

Treatment of the survivors from the Nagoya air crash.

Six patients were taken to our hospital alive just after the air crash at Nagoya Airport in 1994. On admission, all patients suffered from profound shock which rapidly progressed. Serum albumin and hemoglobin levels, and platelet count decreased on admission or soon after. The four patients who died could not recover from the shock and associated rapid deterioration of neurological signs. However, two patients were successfully treated with massive transfusion of packed red blood cells, fresh frozen plasma, fresh blood, and/or platelet concentrate and survived to discharge. We recommend addition of albumin to the transfusate in such cases.

Accidents, Aviation↗

PubMed1998

[Renal hemangiopericytoma: report of a case].

A 34-year-old house wife presented with a right renal mass detected by work-up for epigastralgia. The mass located in the right renal sinus was round and approximately 3 cm in diameter. Although the tumor was well enhanced with contrast medium on CT scan, it was hypovascular on the early arterial phase of renal angiography. Translumbar radical nephrectomy was performed on suspicion of the right renal cell carcinoma. The tumor was solid and hard and, the cut surface of the tumor was homogenously colored pale pink. Microscopically it was hemangiopericytoma arising in the renal sinus, composed of well-developed pericytes and capillaries with so-called staghorn configuration, with invasion of hilar renal vein. Immunohistochemically, the hemangiopericytes were strongly positive for CD34, but negative for factor VIII associated antibodies. To our knowledge, the present patient is the 6th case in the Japanese literature and the first case with incidentally detected renal hemangiopericytoma.

Adult↗