Insulin-induced electrophysiology changes in human pleura are mediated via its receptor.

BACKGROUND: Insulin directly changes the sheep pleural electrophysiology. The aim of this study was to investigate whether insulin induces similar effects in human pleura, to clarify insulin receptor's involvement, and to demonstrate if glibenclamide (hypoglycemic agent) reverses this effect. METHODS: Human parietal pleural specimens were mounted in Ussing chambers. Solutions containing insulin or glibenclamide and insulin with anti-insulin antibody, anti-insulin receptor antibody, and glibenclamide were used. The transmesothelial resistance (R(TM)) was determined. Immunohistochemistry for the presence of Insulin Receptors (IRa, IRb) was also performed. RESULTS: Insulin increased R(TM) within 1st min (P = .016), when added mesothelially which was inhibited by the anti-insulin and anti-insulin receptor antibodies. Glibenclamide also eliminated the insulin-induced changes. Immunohistochemistry verified the presence of IRa and IRb. CONCLUSION: Insulin induces electrochemical changes in humans as in sheep via interaction with its receptor. This effect is abolished by glibenclamide.

The role of surgery in the management of malignant pleural mesothelioma.

Malignant pleural mesothelioma (MPM) is a relatively rare multifocal pleural tumor with low metastatic potential. Surgery can be used in MPM for diagnostic and therapeutic purposes. Thoracoscopy is a useful tool to obtain tissue biopsy to establish a definitive diagnosis and to perform talc poudrage of the pleural cavity in order to prevent reaccumulation of fluid. Cytoreductive procedures, such as pleurectomy/ decortication (PD) and extrapleural pneumonectomy (EPP) are also used in multimodal treatment protocols. The available evidence until now suggests that EPP offers better palliation of dyspnea and orthopnea due to a trapped lung and ventilation perfusion mismatch and better adjuvant radiation therapy planning when compared to PD. Better local disease control and obvious survival benefit by using EPP instead of PD are at the moment unproven. However, EPP is connected with high mortality and morbidity rates, especially if performed in centers without expertise with this complex procedure. EPP and thoracoscopic parietal pleurectomy are now tested in two ongoing prospective randomized trials for their efficacy in the treatment of this disease. In the absence of any controlled randomized trial, EPP should be considered as part of the treatment of MPM only within the context of a prospective randomized trial or in special centers with expertise in the procedure and always within a tri-modal or four-modal treatment protocol, including also chemotherapy, radiotherapy, intrapleural immunochemotherapy and laser photodynamic therapy.

Fibrous tumor of the lung: diagnostic and therapeutic considerations apropos of two cases.

Solitary fibrous tumor (SFT) of the pleura and the lung is an uncommon spindle cell neoplasm arising from the visceral pleura in the majority of the cases. Current diagnostic and therapeutic considerations are discussed apropos of 2 recent cases. 1st case: A 46-year-old male, heavy smoker, presented with nonspecific complaints and a mass in the left posterior mediastinum at the level of the 5th thoracic vertebra. Computed tomography (CT) and magnetic resonance imaging (MRI) of the chest confirmed the position of the mass in proximity to the thoracic wall at that level. Through a left posterolateral thoracotomy, a 4 x 5 x 2 cm mass, mushroom-shaped, stalky, completely covered by the lung parenchyma, was resected. Histopathological examination revealed a SFT of the lung. 2nd case: A 54-year-old woman presented with symptoms of respiratory distress and persistent hypoglycaemia. CT scan of the chest showed a huge mass within the right hemithorax, compressing the mediastinum and the contralateral lung. The mass was initially detected on chest radiography and CT scan 3 years before resection. Fine needle biopsy (FNB) results were inconclusive and resection of the mass through a right thoracotomy established the diagnosis of malignant SFT. Resection of the mass resulted in recovery of respiratory function and the paraneoplastic hypoglycaemia. Radiologic features and inconclusive fine needle aspiration (FNA)/FNB results make preoperative diagnosis of SFTs of the pleura and lung difficult. Diagnosis of SFT will be established with certainty after surgery. Resection with clear margins is the main important prognostic factor.

Low glucose level and low pH alter the electrochemical function of human parietal pleura.

The aim of the present study was to investigate whether low glucose and pH level, which are usually measured in complicated pleural effusions, alter the electrochemical function of healthy human parietal pleura. Parietal pleural pieces were stripped from 66 patients during thoracic surgery and were mounted in Ussing chambers. Krebs' solutions containing different glucose levels (0, 40 and 100 mg) and balanced at different pH levels (7.4, 7.3 and 7.2) were added to the pleural cavity surface of the pieces. Transmesothelial potential difference was measured at various time-points as an electrophysiological variable and transmesothelial resistance (R(TM)) was calculated using Ohm's law. When normal-glucose Krebs at pH 7.45 was used, R(TM) remained unchanged over time, but when low-glucose Krebs was used, R(TM) decreased. Krebs without glucose caused the greatest decrease in R(TM). Use of low-pH Krebs decreased R(TM). The lower the pH of the Krebs, the faster the decrease in R(TM) and the greater the effect. The decrease in R(TM) was greater with low-pH than with low-glucose Krebs. Low glucose and low pH caused an additive decrease in R(TM). Low glucose concentration and low pH cause alteration of the electrochemical function of human parietal pleura and could act as agents that lead to further exudate progression.

Pulmonary dirofilariasis mimicking lung tumor with chest wall and mediastinal invasion.

We present a case of human pulmonary dirofilariasis, diagnosed in a 55-year-old heavy smoker (male) by wedge resection of the pulmonary lesion and histologic examination. The dirofilaria lesion had the clinical and radiographic appearance of a peripheral pulmonary lesion invading the anterior chest wall and mediastinum. The reported radiographic image of the disease is different from the usually described picture of a pulmonary coin lesion.

The role of mediastinoscopy in postresection lung cancer patients.

PURPOSE: To emphasize the role of mediastinoscopy in the evaluation of mediastinal lymphadenopathy in postresection lung cancer patients. PATIENTS AND METHODS: During the period 1997-1999, 11 patients who had a previous lobectomy or bilobectomy and mediastinal lymph node dissection for primary lung cancer underwent cervical mediastinoscopy for the evaluation and tissue diagnosis of mediastinal lymphadenopathy, discovered at planned, part of the follow-up,computed tomography (CT) of the chest. Five patients had received postoperative adjuvant radiation therapy and/or chemotherapy. RESULTS: Nodal metastasis was histologically confirmed in 9 patients who subsequently received a combination of chemotherapy and radiation therapy, with a mean survival of 8.1 months. Two patients had no evidence of lymph node metastasis and remain alive and disease-free 21 and 27 months after mediastinoscopy, without any additional therapy. CONCLUSION: Cervical mediastinoscopy, after a previously performed mediastinal lymph node dissection, is a special condition. However, it is the method of choice for the evaluation of the nature of mediastinal lymphadenopathy in postresection lung cancer patients. The alternative way of repeat thoracic CT at frequent intervals and the lymph node size enlargement criterion should be preserved for patients with a previous pneumonectomy or those who cannot tolerate additional radiation therapy or chemotherapy.