Biomedical subjects

Kazuhiro Nagata

Publications and source records attributed to Kazuhiro Nagata.

58 records · Page 4Linked to original sources

PubMed2002

[A case of mediastinal teratoma with elevated serum tumor marker levels].

A 27-year-old man complaining of cough was admitted to our hospital because of a giant mediastinal tumor on the chest radiograph. Chest CT and MRI revealed a giant polycystic mediastinal tumor. Chest radiographs on admission showed left pleural effusion due to perforation of the cyst. Laboratory data showed high serum and pleural fluid concentrations of CA 125, CA 19-9, SLX and others. The mediastinal mass was resected and diagnosed pathologically as a mature teratoma. It is reported that patients with mediastinal teratomas often have pleural fluid as a result of self-digestion by pancreatic enzymes, and some mediastinal teratomas have high serum tumor marker levels. We suspected that the high serum tumor marker levels in our case were caused by the high concentrations of tumor markers in the pleural fluid. We suggest that serum tumor marker levels may be useful in the preoperative differential diagnosis of anterior mediastinal cystic tumors.

Adult↗

PubMed2002

[Mycobacterium abscessus infection complicated with diabetes mellitus].

We report a case of Mycobacterium abscessus infection complicated with diabetes mellitus. A 38-year-old man with diabetes mellitus as an underlying disease, was admitted to our hospital because of a productive cough. He had had pulmonary tuberculosis two years before. Chest radiography revealed infiltration in both lung apices and chest CT showed a cavitary lesion in the left upper lobe. Gaffky 2 was found on a sputum smear. However, in the examination of PCR on sputum, not only M. tuberculosis but M. avium complex was negative, and repeated cultures of sputum were positive for M. abscessus. On the basis of the diagnosis of an M. abscessus infection, the patient was initially treated with amikacin, imipenem/cilastatin and levofloxacin during hospitalization while receiving insulin for diabetes mellitus. The smear and culture of sputum became negative for Mycobacterium, and the findings of chest radiography and chest CT improved. After discharge, treatment was continued with clarithromycin and levofloxacin. It is considered that the choice of effective drugs and the additional treatment of an underlying disease are very important for the treatment of a Mycobacterium abscessus infection.

Adult↗

PubMed2001

Xaa-Arg-Gly triplets in the collagen triple helix are dominant binding sites for the molecular chaperone HSP47.

HSP47 is an essential procollagen-specific molecular chaperone that resides in the endoplasmic reticulum of procollagen-producing cells. Recent advances have revealed that HSP47 recognizes the (Pro-Pro-Gly)(n) sequence but not (Pro-Hyp-Gly)(n) and that HSP47 recognizes the triple-helical conformation. In this study, to better understand the substrate recognition by HSP47, we synthesized various collagen model peptides and examined their interaction with HSP47 in vitro. We found that the Pro-Arg-Gly triplet forms an HSP47-binding site. The HSP47 binding was observed only when Arg residues were incorporated in the Yaa positions of the Xaa-Yaa-Gly triplets. Amino acids in the Xaa position did not largely affect the interaction. The recognition of the Arg residue by HSP47 was specific to its side-chain structure because replacement of the Arg residue by other basic amino acids decreased the affinity to HSP47. The significance of Arg residues in HSP47 binding was further confirmed by using residue-specific chemical modification of types I and III collagen. Our results demonstrate that Xaa-Arg-Gly sequences in the triple-helical procollagen molecule are dominant binding sites for HSP47 and enable us to predict HSP47-binding sites in homotrimeric procollagen molecules.

Amino Acid Substitution↗

PubMedDate not supplied

Immunohistochemical distribution of heat shock protein 47 (HSP47) in scirrhous carcinoma of the stomach.

BACKGROUND: The aim of the present study was to examine the immunohistochemical distribution of the 47-kDa heat shock protein (HSP47) to enhance the understanding of the mechanisms involved in stromal fibrosis, which accompanies cancer infiltration in scirrhous carcinoma of the stomach. MATERIALS AND METHODS: In vitro gastric cancer models were prepared by collagen gel cultures using three different human gastric cancer cell lines (KATO-III, MKN-74, MKN-45) and a human fibroblast cell line (TIG-101). Tumor tissues were obtained from ten patients with early gastric cancer (5 scirrhous carcinoma; 5 non-scirrhous carcinoma) and three patients with advanced scirrhous gastric cancer. The gels and the tissues were immunostained by a monoclonal antibody against human HSP47 and then examined by light and electron microscopy. RESULTS: The staining intensity of the fibroblasts was stronger than that of cancer cells in both the culture models and patient tissues. Moreover, the number of fibroblasts in scirrhous gastric cancer was significantly greater than that in non-scirrhous gastric cancer (p = 0.0004). In addition, the discharge of HSP47 was observed in the extracellular matrix as granular deposits of staining. CONCLUSION: These findings indicate that fibroblasts predominantly produce stromal collagen and may play an important role in the development of stromal change in scirrhous gastric cancer. Further studies are required to elucidate the significance of HSP47 in the development of new clinical approaches for treating scirrhous gastric cancer.

Adenocarcinoma↗