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Biomedical subjects

H Takagi

Publications and source records attributed to H Takagi.

At least 361 records · Page 20Linked to original sources
PubMed1997

Sequence analysis of functional regions of homoserine dehydrogenase genes from L-lysine and L-threonine-producing mutants of Brevibacterium lactofermentum.

The homoserine dehydrogenase (HD) genes from Brevibacterium lactofermentum lysine- and threonine-producing mutants were cloned, using the polymerase chain reaction, and sequenced. We found the amino acid substitutions, Val104Ile in the lysine-producing mutants in which HD may cause leaky mutation and Ser393Phe in the threonine-producing mutant with feedback-insensitive HD.

Amino Acid Sequence↗
PubMed1997

Secretory production of erythropoietin and the extracellular domain of the erythropoietin receptor by Bacillus brevis: affinity purification and characterization.

Bacillus brevis secretes a large amount of cell wall proteins into the culture medium. For construction of Bacillus brevis expression-secretion vectors of human erythropoietin (EPO) and the extracellular domain of mouse erythropoietin receptor (sEPOR), cDNA for each mature form was inserted into a plasmid containing the promoter region and the signal-peptide encoding region of a cell wall protein. Culture supernatants of transformants were affinity purified using a monoclonal antibody-fixed gel for EPO and and EPO-fixed gel for sEPOR. The affinity purification efficiently removed unwanted proteins, giving samples with sufficiently high purity to analyze amino acid sequences of N-terminal regions and biological activities. Combination of this secretory production and affinity purification may facilitate isolation of a large amount of pure EPO and sEPOR, and is useful for further understanding the molecular mechanism of interaction between EPO and EPOR.

Amino Acid Sequence↗
PubMed1997

High-level expression of the chemically synthesized gene for microbial transglutaminase from Streptoverticillium in Escherichia coli.

We developed a novel approach for the high-level production of a microbial transglutaminase (TGase) from Streptoverticillium in E. coli. The direct expression of the TGase gene in E. coli cells did not cause overproduction, probably due to the harmful influence of TGase activity, which introduces covalent crosslinks between proteins. Therefore, we fused the chemically synthesized TGase gene coding for the entire 331 amino acid residues at the amino terminus to a bacteriophage T7 gene 10 leader peptide (260 amino acids) using an inducible expression vector. The TGase gene was expressed as inclusion bodies in the E. coli cytoplasm. Restoring 15 amino acid residues upstream of the amino terminus of the mature TGase by a two-step deletion of the fusion sequence facilitated solubilization and subsequent proteolytic cleavage, thus releasing mature TGase. Although the mature form had less TGase activity than native TGase, because of the poor refolding rate, these results suggest that this system is suitable for the efficient production of TGase.

Amino Acid Sequence↗
PubMed1997

[Effects of carcinostatic agents in the hematogenous metastasis of cancer].

The experimental studies in vitro and in vivo were performed to investigate the effects of carcinostatic agents in the adhesion of cancer cells to endothelial cells. Certain carcinostatic agents induce the expression of E-selectin on endothelial cells and enhance the expression of carbohydrate ligands on cancer cells. Consequently, increased adhesion of cancer cells to endothelial cells was observed by the treatment of carcinostatic agents. In the trans-splenic hepatic metastasis model using nude mice, the augmentation of cancer metastasis was observed by the treatment of carcinostatic agents. From the above, we concluded that carcinostatic agents may increase the metastatic ability of cancer cells in patients with cancer.

Animals↗
PubMed1997

Evaluation of tetrahydropyranyladriamycin as an immunosuppressant in concordant xenotransplantation.

BACKGROUND: Tetrahydropyranyladriamycin (THP), a derivative of anthracycline, exhibits a stronger antiproliferative activity and a lower cardiotoxicity than the other anthracyclines. The value of THP as an immunosuppressant has not been examined yet, whereas cyclophosphamide, which is another antiproliferative drug, has shown promise as an immunosuppressant in concordant xenotransplantation. METHODS: The effect of THP on the marginal zone in the spleen and anti-species antibody production was evaluated and was compared with that of cyclophosphamide in a concordant xenogeneic splenocyte injection model (hamster-to-rat). Next, THP was used as monotherapy for hamster-to-rat heart transplantation to substantiate the potency of its immunosuppressive activity in concordant xenotransplantation. Finally, combination therapy with THP plus FK506 was tried. RESULTS: THP (5 mg/kg) suppressed the expansion of the marginal zone more than did cyclophosphamide (40 mg/kg) and inhibited the production of antispecies antibody as much as did cyclophosphamide (40 mg/kg) in the splenocyte injection model. THP monotherapy could prolong the survival of hamster-to-rat heart grafts up to 14.5 +/- 3.2 days (n = 21). The rejected grafts in the THP-treated animals did not show any histologic evidence of vascular endothelial damage but did exhibit a mononuclear cell infiltration. Combination therapy with THP plus FK506 provided excellent graft survival. CONCLUSIONS: THP can prevent early phase humoral rejection in concordant xenotransplantation.

Animals↗
PubMed1997

[Diagnosis of local recurrence of colorectal cancer, using PET and immunoscintigraphy by means of 131I or 111In anti-CEA monoclonal antibody].

The accurate and early diagnosis of the tumor in the point of the size, the location, the depth of invasion of other organs or the stages of the recurrent cancer became much more important than before, not only for the selection of the treatment method but also for the decision of the quality of the operation for preserving the function as much as possible for the quality of the life of the patient. The usefulness of positron emission tomography (PET) and immunoscintigraphy by means of 131I or 111In anti-CEA onoclonal antibody for the diagnosis of the recurrent colorectal cancer had been confirmed in clinical use of colorectal cancers. No adverse effect of this monoclonal anti-body of the mouse was seen in this studies. The differential absorption ratio (DAR) was useful indicator in PET-imaging to differentiate the true tumor tissue from the scar tissue or granulation-tissue around the tumor. Even though the imaging, structure of PET is inferior to those of CT or MRI, the imaging of PET reflects the biological character of tumor, itself and makes the more accurate diagnosis possibly by combined use with regular CT and MRI.

Adult↗
PubMed1997

Regional adjuvant chemotherapy after partial hepatectomy for metastatic colorectal carcinoma.

The prognostic factors after hepatic resection for metastases from colorectal carcinoma were examined, and the results of adjuvant hepatic arterial chemotherapy are presented. Hepatic resection was undertaken in 57 patients with metastatic liver tumor from colorectal cancer. Adjuvant hepatic arterial chemotherapy using 5-fluorouracil, doxorubicin or epirubicin, and mitomycin C was administered to 31 patients. The 3- and 5-year survival rates for the 57 patients were 53% and 23%, respectively. The significant prognostic factors were solitary liver tumor and metachronous liver tumor. However, type of hepatectomy, surgical margin, site of the primary tumor, and histologic differentiation of the carcinoma did not relate to the prognosis. The 3- and 5-year survival rates for the patients given adjuvant arterial chemotherapy were 57% and 57%, respectively, indicating a significantly better survival rate than in the nontreated patients. These results suggest that hepatic arterial chemotherapy is effective treatment in patients with hepatic resection for metastases from colorectal carcinoma. However, recurrence in the lung is relatively high. Further improvement might be achieved by administering hepatic arterial chemotherapy as well as effective systemic chemotherapy.

Adult↗
PubMed1997

[Surgical management of constrictive pericarditis].

Cases of constrictive pericarditis per a institute is few for decrease of this disease. Therefore for surgical management of constrictive pericarditis, it has not been clear whether cardiopulmonary bypass during operation is necessary or not, and the reports of long term results are few. We gathered information by questionnaires from thirty-four institutes, which constitute Tokai Cardiovascular Surgeons Conference in Shizuoka, Aichi, Mie and Gifu Prefecture, for surgical management of constrictive pericarditis, and investigated its results. Etiology of constrictive pericarditis is idiopathic (49%), tuberculosis (29%) or post open heart surgery (10%). Hospital death included operative death is 14%, and postoperative liver complications was many next to heart complications. The cases, whose NYHA functional class at discharge did not improve compared with preoperative state, was 33%. At one year after operation two third of them improved in NYHA functional class, but the others did not improved.

Adolescent↗
PubMed1997

Clinical application of a new monoclonal antibody (19B7) against PIVKA-II in the diagnosis of hepatocellular carcinoma and pancreatobiliary malignancies.

OBJECTIVES: A new monoclonal antibody (19B7) against prothrombin induced by vitamin K absence or antagonist-II (PIVKA-II) was clinically applied in patients diagnosed with hepatocellular carcinoma and pancreatobiliary malignancies, and the results were compared with those obtained using the conventional monoclonal antibody (MU-3) against PIVKA-II. METHODS: The assays were the standard E-1023 using MU-3, a high sensitivity kit using MU-3 and a highly sensitive avidin-biotin complex method, and a new monoclonal antibody (19B7) kit. RESULTS: The rate of PIVKA-II positivity in patients with hepatocellular carcinoma (n = 182) was 44% with E-1023, 55.5% with the high sensitivity kit, and 58.2% with the new monoclonal antibody kit. Small liver cancers <2 cm in diameter (n = 45) had a positivity rate of 15.6% with E-1023, 26.7% with the high sensitivity kit, and 31.1% with the new monoclonal antibody kit. The incidence of PIVKA-II positivity in patients with pancreatobiliary carcinoma (n = 91) was 29.7% with the high sensitivity kit and 52.7% with the new monoclonal antibody kit. The PIVKA-II ratio (plasma concentration with the high sensitivity kit/plasma concentration with the new monoclonal antibody kit) was calculated as > 1.0 in 89 of the 113 (78.8%) patients with hepatocellular carcinoma with the new monoclonal antibody kit assay level above 0.002 arbitrary units/ml, compared with <1.0 in almost all patients with pancreatobiliary malignancies. CONCLUSIONS: MU-3 has much greater affinity for PIVKA-II in hepatocellular carcinoma than does 19B7, whereas 19B7 has much greater affinity for PIVKA-II in pancreatobiliary malignancies than does MU-3. The new monoclonal antibody, 19B7, is useful for diagnosing hepatocellular carcinoma and can also distinguish patients with hepatocellular carcinoma from those with other pancreatobiliary malignancies when combined with a PIVKA-II assay using the conventional monoclonal antibody, MU-3.

Adult↗
PubMed1997

Analysis of specific accumulation of radiolabeled anti-carcinoembryonic antigen monoclonal antibody CEA 102 in colorectal cancer using computed radiography.

The specific accumulation of radiolabeled anti-carcinoembryonic antigen (CEA) monoclonal antibody (MoAb) CEA 102 in colorectal cancers was investigated by autoradiography of surgical specimens using Fuji Computed Radiography (FCR). Five patients with colorectal cancer were injected intravenously with [13I]-labeled intact CEA 102 or its F(ab')2. Primary tumor and liver metastases were successfully detected by external scanning with gamma camera in four cases. Autoradiographic study using FCR showed predominant localization of [13I]-labeled CEA 102 in primary tumors and liver metastases in all cases. Even the small-sized liver metastasis (0.5 cm) was clearly visualized. The pixel distribution curves showed the heterogeneity of the distribution of administered MoAb in the tumors. In the quantitative distribution analysis of CEA 102, the uptake of the primary tumor was 10-fold greater than that of the normal colon mucosa. These results suggest that MoAb has great potential in radioimmunodetection as well as possible use in antibody-directed therapy.

Antibodies, Monoclonal↗
PubMed1997

[Findings of genetic changes in small intestinal carcinomas].

There is now good evidence that a series of genetic lesions in both dominant oncogenes and tumor suppressor genes are involved in the pathogenesis of human digestive tract carcinomas. Small intestinal carcinomas are very rare, accounting for only about 0.19% of all primary gastrointestinal malignant tumors in Japan, so there are few reports investigating genetic changes of small intestinal carcinoma. We analyzed 3 microsatellite loci and the status of K-ras and p53 genes isolated from tumors and surrounding normal tissue samples obtained during surgery. The polymerase chain reaction (PCR) technique used frequent genetic instability to assess differences between tumor and matched DNAs. Replication errors (RERs) were observed in 3 of the 29 cases (10%) of gastric carcinoma and in 11 of the 72 cases (15%) of colorectal carcinoma. None of the 13 (0%) esophageal carcinoma cases showed any RER, but 5 of 11 cases of small intestinal carcinoma (45%) had RERs, reflecting a significantly high incidence. None of the 11 small intestinal carcinoma cases exhibited K-ras gene mutations. Of 7 case amplified successfully by polymerase chain reaction (PCR) in exon 5-8 loci in p53 gene, 2 exhibited abnormally migrated bands in polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis. It is thus clear that the genetic carcinogenesis in the small intestine is different from other parts of the digestive tract. These results suggest that genetic instability plays an important role in the pathogenesis of small intestinal carcinomas.

Adenocarcinoma↗
PubMed1997

[Surgical treatment for colorectal carcinoma combined with liver cirrhosis].

Surgical treatment for colorectal carcinoma associated with liver cirrhosis is discussed. Resection of this carcinoma is considered safe for patients whose liver function belongs to clinical stage I, II or Grade A, B of Child-Pugh classification or KICG more than 0.06/min. When hepatocellular carcinoma (HCC) is associated and the remnant liver function is feasible, hepatic resection should be undertaken at a favorable opportunity. When risky esophageal varices are present, endoscopic variceal ligation (EVL) or sclerotherapy (EIS) should be performed preoperatively. Lymph node dissection should be restricted to D1 or D2. In the postoperative phase, attention should be paid to maintaining liver function and hepatic circulation. Dobutamine or dopamine is useful for increasing hepatic blood flow. Fresh frozen plasma or platelet transfusion is used when needed.

Colorectal Neoplasms↗