Keiji Kushibe

Epithelial regeneration and preservation of tracheal cartilage after tracheal replacement with cryopreserved allograft in the rat

OBJECTIVE We investigated the origin of the epithelium in transplanted cryopreserved tracheal allografts in rats and tried to clarify the mechanism by which immunogenicity is reduced in this procedure. METHODS Tracheal transplantation was performed with PVG rats (allele at the RT1 locus: c) used as donors and ACI rats (allele at the RT1 locus: a) as recipients. After resection of a 5-ring segment of the cervical trachea of an ACI rat, the trachea was reconstructed with the cryopreserved tracheal segment of a PVG rat (n = 6). No immunosuppressive agents or steroids were given. Histologic changes were determined and immunohistochemical staining was performed to investigate major histocompatibility complex class I antigens of the transplanted tracheal segment. RESULTS Two months after tracheal transplantation, 6 surviving ACI rats were killed. Histologically, the epithelium and tracheal cartilage of the transplanted cryopreserved segment displayed normal structure. Immunohistochemical staining showed that the major histocompatibility complex class I antigen of the ACI rat was expressed in the epithelium of the transplanted segment and that the class I antigen of the PVG rat was expressed in the cartilage of the transplanted segment. CONCLUSIONS After transplantation of the cryopreserved trachea, the epithelium of the transplanted cryopreserved segment originated from the recipient epithelium whereas the cartilage retained the structure of the donor trachea. We hypothesize that transplantation of a cryopreserved trachea leads to the growth of the recipients epithelium over the donor trachea, thereby reducing the antigenicity of the transplant.

Sealing Effect of Cross-Linked Gelatin Glue in the Rat Lung Air Leak Model

BACKGROUND Air leak is a common problem in pulmonary surgical procedures. In this study, we evaluated the efficacy and safety of gelatin glue (cross-linked with glutaraldehyde) in a rat model of lung air leak. METHODS A model of pulmonary fistula was created in the rat lung with the use of a needle. The fistula was then sealed with either gelatin glue (group A), fibrin glue (group B), or fibrin glue with a polyglycolic acid sheet (group C). The seal breaking pressures were measured for each group, and the results were compared. To assess the biocompatibility of the gelatin glue, a model of lung damage was created with incision, and the gelatin glue was applied to seal the wound. Histologic analysis was then performed on the lung tissue. RESULTS The seal breaking pressure in group A (47.88 ± 6.69 mm Hg) was significantly higher than that in group B (24.67 ± 3.24 mm Hg, p = 0.0302) or group C (28.67 ± 3.55 mm Hg, p = 0.0406). Histologically, the gelatin glue adhered firmly to the lung surface, and only localized tissue inflammation was observed. CONCLUSIONS The sealing effect of gelatin glue was superior to that of fibrin glue, with or without a polyglycolic acid sheet. In addition, the gelatin glue only caused mild inflammation of the lung and was absorbed without any adverse foreign body response. These findings suggest that gelatin glue may be a therapeutically effective biomaterial for sealing lung wounds and restoring respiratory function.

Can preoperative imaging studies accurately predict the occurrence of bullae or blebs? Correlation between preoperative radiological and intraoperative findings.

BACKGROUND Radiological findings of patients with primary spontaneous pneumothorax (PSP) undergoing surgery have not been well analyzed. The aim of this study was to evaluate the accuracy of imaging studies for predicting the presence of emphysema-like changes (ELCs) detectable during surgery. METHODS Ninety-three PSP patients who underwent surgery from September 2005 to October 2009 were included in the study. We analyzed preoperative chest radiographic and computed tomographic (CT) findings, and compared the findings with intraoperative detection of ELCs. Chest radiographic findings were analyzed by classifying the PSP size into three categories: small, moderate, and complete. RESULTS Seventy-six of the 93 patients (82%) had ELCs detected during surgery. The size of the PSP on a radiograph was significantly correlated with the presence of ELCs (p=0.0121). Preoperative CT revealed 64 of the 76 ELCs (sensitivity, 84%; specificity, 100%; accuracy, 87%). Twenty-nine patients without ELCs detected by preoperative CT were analyzed separately. In this group, a larger PSP size also increased the likelihood of ELCs being present (p=0.0049). Seven patients (8%) experienced a recurrence after surgery. No factor could significantly predict recurrence. CONCLUSIONS Chest CT analysis alone was associated with a false-negative rate of about 15% for ELCs. Combining the analysis of chest radiographic and CT findings could improve sensitivity.

Flow Cytometric Analysis of the DNA Content of Thymomas

In this study, the prognostic value of determining the nuclear DNA content of thymomas by flow cytometry was evaluated. Of a total 31 resected thymomas, 10 (32%) showed DNA aneuploidy, the presence of which was significantly correlated with an advanced clinical stage of disease. The patients with an aneuploid tumor had a poorer prognosis than those with a diploid tumor, demonstrating a survival rate of 50% at 7 postoperative years, which was considerably less favorable than that of the patients with a diploid tumor, being 100% in the same period (p<0.05). Moreover, patients with a high DNA index (DI), i.e., a DI≧1.5, tended to have a poorer prognosis than those with a low DI. These findings indicated that the DNA content can be an important prognostic index in patients with thymomas.