Takashi Tojo

Management of malignant tracheobronchial stenosis with metal stents and dumon stents

BACKGROUND Tracheobronchial stenosis caused by malignancy is a life- threatening problem. Stenting is one of the treatment modalities and recently has been used widely for the management of such stenosis, but we do not have a clear guide as to which stent should be selected. METHODS We evaluated 25 patients (19 men, 6 women; mean age, 60.7 years; range, 34 to 77 years) received 24 metal stents (four covered with silicone rubber) and three Dumon stents. All 25 patients had severe dyspnea because of airway stenosis caused by malignant tumors. RESULTS Among the 25 patients, airway obstruction due to extrinsic compression by tumor developed in 11 and was treated with a bare metal stent. The airway remained patent in 10 patients. In 16 patients with intraluminal tumor invasion, nine lesions were treated with a bare metal stent, four lesions with a covered metal stent, and the remaining three lesions with a Dumon stent. Recurrent stenosis did not occur in any patient with a covered metal stent or a Dumon stent. However, restenosis occurred in 4 patients with a bare metal stent, all of whom received laser therapy. In all patients, stenting immediately relieved dyspnea. Six patients lived for 32 days to 53 months after stenting, and 19 patients died of primary malignancies with a mean survival of 131.9 days. CONCLUSIONS Metal stents are effective in treating malignant extrinsic tracheobronchial compression. The use of covered metal stents or Dumon stents is preferable for intraluminal stenosis due to malignant growth.

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.

In vitro study of ablated lung tissue in Nd:YAG laser irradiation

BACKGROUND Neodymium:yttrium-aluminum garnet lasers are used to reduce lung volume. An assessment of the relationship between the histologic and gross findings in the lung irradiated by a laser would be helpful in laser-assisted pneumoplastic procedures. METHODS In vitro lung lobes surgically resected for pulmonary carcinomas were irradiated with a neodymium:yttrium-aluminum garnet laser at three energy levels in three modes: contact rubbing, contact pointing, and noncontact. Pleural degeneration in 216 samples from 24 lobes was classified as coagulative, amorphous, or destructive. At all energy levels, the laser was applied for 1.5 seconds. RESULTS Noncontact mode at 7.5 W or 15 W and contact rubbing at 5 W caused coagulative or amorphous degeneration but no destructive degeneration. The energy level correlated with the color of the degenerated pleura. The incidence of destructive pleural degeneration, which led to air leaks as revealed by an air inflation test, was 0% in pink and white samples, 59% in brown samples, and 100% in black samples (p < 0.0001, white versus brown samples). CONCLUSIONS In neodymium:yttrium-aluminum garnet laser ablation of lung tissue, the color of the degenerated pleura correlates with the intensity of the applied laser energy and the degree of pleural degeneration.

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.