Ke-g Chen

Formation of crystalline silicon carbon nitride films by microwave plasma-enhanced chemical vapor deposition

We report that carbon nitride thin films can be formed by microwave plasma-enhanced chemical vapor deposition (PECVD). Gas mixtures containing CH4, H2, and NH3 in various ratios were tried as the precursors, and a Si(100) wafer was used as the substrate. The films were characterized by X-ray photoelectron spectroscopy (XPS), and electron microscopy (both SEM and TEM). A Si content of about half of the carbon content was observed when the substrate temperature exceeded 1000 °C. Microscopic investigation revealed the coexistence of large-grain (over 10 μm) and fine-grain (under 1 μm) crystals. We suggest the presence of a crystalline carbon nitride phase corresponding to an α-C3N4 structure (isomorphic to α-Si3N4), which may also be a stable hard material.

Nonintubated thoracoscopic lobectomy for lung cancer.

Objective:To evaluate the feasibility and safety of thoracoscopic lobectomy without endotracheal intubation. Summary Background Data:General anesthesia with single-lung ventilation is considered mandatory for thoracoscopic lobectomy for non–small cell lung cancer (NSCLC). Nonintubated thoracoscopic lobectomy has not been reported previously. Methods:From August 2009 through June 2010, some 30 consecutive patients with clinical stage I or II NSCLC were treated by nonintubated thoracoscopic lobectomy using epidural anesthesia, intrathoracic vagal blockade, and sedation. To evaluate the feasibility and safety of this novel technique, they were compared with a control group consisting of 30 consecutive patients with clinical stage I or II NSCLC who underwent thoracoscopic lobectomy using intubated general anesthesia from August 2008 through July 2009. Results:Collapse of the operative lung and inhibition of coughing were satisfactory in the nonintubated patients, induced by spontaneous breathing, and vagal blockade. Three patients in the nonintubated group required conversion to intubated-single lung ventilation because of persistent hypoxemia, poor epidural anesthesia pain control, and bleeding. One patient in each group was converted to thoracotomy because of bleeding. The 2 groups had comparable anesthesia durations, surgical durations, blood loss, and numbers of dissected lymph nodes. Patients who underwent nonintubated surgery had lower rates of sore throat (6.7% vs 40.0%, P = 0.002) and earlier resumption of oral intake (mean, 4.7 hours vs 18.8 hours, P < 0.001). Patients undergoing nonintubated surgery also had a trend toward better noncomplication rates (90% vs 66.7%, P = 0.057) and shorter postoperative hospital stays (mean, 5.9 days vs 7.1 days, P = 0.078). Conclusions:Nonintubated thoracoscopic lobectomy is technically feasible and is as safe as lobectomy performed with intubation in highly selected patients. It can be a valid alternative of single-lung-ventilated thoracoscopic surgery in managing early-stage NSCLC.

Autophagy promotes resistance to photodynamic therapy-induced apoptosis selectively in colorectal cancer stem-like cells

Recent studies have indicated that cancer stem-like cells (CSCs) exhibit a high resistance to current therapeutic strategies, including photodynamic therapy (PDT), leading to the recurrence and progression of colorectal cancer (CRC). In cancer, autophagy acts as both a tumor suppressor and a tumor promoter. However, the role of autophagy in the resistance of CSCs to PDT has not been reported. In this study, CSCs were isolated from colorectal cancer cells using PROM1/CD133 (prominin 1) expression, which is a surface marker commonly found on stem cells of various tissues. We demonstrated that PpIX-mediated PDT induced the formation of autophagosomes in PROM1/CD133+ cells, accompanied by the upregulation of autophagy-related proteins ATG3, ATG5, ATG7, and ATG12. The inhibition of PDT-induced autophagy by pharmacological inhibitors and silencing of the ATG5 gene substantially triggered apoptosis of PROM1/CD133+ cells and decreased the ability of colonosphere formation in vitro and tumorigenicity in vivo. In conclusion, our results revealed a protective role played by autophagy against PDT in CSCs and indicated that targeting autophagy could be used to elevate the PDT sensitivity of CSCs. These findings would aid in the development of novel therapeutic approaches for CSC treatment.

Si-containing crystalline carbon nitride derived from microwave plasma-enhanced chemical vapor deposition

Carbon nitride thin films have been grown by the microwave plasma-enhanced chemical vapor deposition (MW-PECVD) technique. Gas mixtures containing CH4, H2 and NH3 at various ratios were tested as precursors, and Si (100) wafers were used as substrates. X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), electron microscopy (both SEM and TEM), and Raman spectroscopy have been employed to characterize the resultant films. The phase contents in the films were found to be strongly dependent on the substrate temperature. The incorporation of significant amounts of Si into the film was observed when the substrate temperature exceeded 1000°C. However, the presence of Si along with a high substrate temperature also promotes the formation of large crystallites. XPS analyses of C(1s) and N(1s) core levels suggest a multiple bonding structure between carbon and nitrogen atoms. Microscopic investigations of the films reveal the coexistence of large grain (> 10 μm) and fine grain (< 1 μm) crystals. Preliminary structural studies suggest the presence of a crystalline carbon nitride compound corresponding to a hypothetical α-C3N4 phase (isomorphic to α-Si3N4), which may also be a stable hard material. Furthermore, we propose that some of the Si has been incorporated as a substitutional element for the C site in the new phase. The Raman spectra exhibit many sharp lines, of which the most distinct ones mimic those of the α-Si3N4 structure.

Nonintubated thoracoscopic lung resection: a 3-year experience with 285 cases in a single institution.

OBJECTIVE Tracheal intubation with one-lung ventilation is considered mandatory for thoracoscopic surgery. This study reported the experience of thoracoscopic lung resection without endotracheal intubation in a single institution. METHODS From August 2009 through July 2012, 285 consecutive patients were treated by nonintubated thoracoscopic surgery using epidural anesthesia, intrathoracic vagal blockade, and sedation for lobectomy, segmentectomy, or wedge resection in a tertiary medical center. The feasibility and safety of this technique were evaluated. RESULTS The final diagnosis for surgery were primary lung cancer in 159 patients (55.8%), metastatic lung cancer in 17 (6.0%), benign lung tumor in 104 (36.5%), and pneumothorax in 5 (1.8%). The operative methods consisted of conventional (83.2%) and needlescopic (16.8%) thoracoscopic surgery. The operative procedures included lobectomy in 137 patients (48.1%), wedge resection in 132 (46.3%), and segmentectomy in 16 (5.6%). Collapse of the operative lung and inhibition of coughing were satisfactory in most of the patients. Fourteen (4.9%) patients required conversion to tracheal intubation because of significant mediastinal movement [5], persistent hypoxemia [2], dense pleural adhesions [2], ineffective epidural anesthesia [2], bleeding [2], and tachypnea [1]. One patient (0.4%) was converted to thoracotomy because of bleeding. No mortality was noted in our patients. CONCLUSIONS Nonintubated thoracoscopic lung resection is technically feasible and safe in selected patients. It can be a valid alternative in managing patients with pulmonary lesions.

Exploring the relationship between preterm placental calcification and adverse maternal and fetal outcome.

To explore the relationship between preterm placental calcification and adverse pregnancy outcome, including maternal and fetal outcomes.

Nonintubated Needlescopic Video-Assisted Thoracic Surgery for Management of Peripheral Lung Nodules

BACKGROUND Video-assisted thoracic operations are usually performed with 5-mm or 10-mm instruments under general anesthesia with single-lung ventilation. Management of peripheral lung nodules by a needlescopic video-assisted thoracoscopic operation, without endotracheal intubation, has rarely been attempted. We evaluated the feasibility and safety of this minimally invasive technique in managing peripheral lung nodules. METHODS From August 2009 through March 2011, 46 patients with peripheral lung nodules were treated using 3-mm needlescopic video-assisted thoracoscopic operations for wedge resection with epidural anesthesia and sedation, without endotracheal intubation. RESULTS A definitive diagnosis was obtained in all 46. Extension of the 3-mm incisions was required in 8 patients because of primary lung cancer requiring a lobectomy in 3, pleural adhesions in 3, and difficulty in identifying or resecting the nodule in 2. Two patients required conversion to intubated single-lung ventilation because of dense adhesions between the lungs and the diaphragm. Operations lasted a mean of 69.2 ± 46.8 minutes. Postoperative side effects occurred in 4 patients, including sore throat, headache, and vomiting requiring medication. Operative complications developed in 1 patient who had air leaks for more than 3 days postoperatively. The mean postoperative chest tube drainage and hospital stay were 1.1 days and 2.7 days, respectively. Postoperative neuralgia was noted in 12 patients (26%). Most patients (74%) were very satisfied or satisfied with the resulting scars. CONCLUSIONS Nonintubated needlescopic video-assisted thoracoscopic operations are technically feasible and safe and may be a less invasive alternative in the management of selected patients with peripheral pulmonary nodules.

Descending necrotizing mediastinitis: A 10-year surgical experience in a single institution

OBJECTIVE Early diagnosis and aggressive surgical drainage are very important for successful treatment of descending necrotizing mediastinitis. However, the surgical techniques used for this condition remain controversial. We report our 10-year experience of managing this devastating disease, focusing on the multidisciplinary, minimally invasive operative procedures and the unique bacteriologic factors in Taiwan. METHODS Between January 1997 and January 2007, we retrospectively reviewed 18 patients with descending necrotizing mediastinitis who were treated in the National Taiwan University Hospital. Diagnosis and Endo classification were confirmed by computed tomography of the neck and chest. RESULTS Eight women and 10 men were included in this study. The mean age was 57.8 +/- 15.2 years. Cervical drainage was performed in the involved area in all patients. The methods for mediastinal drainage included transcervical (n = 10), video-assisted thoracic surgical drainage (n = 6), subxiphoid drainage (n = 1), and mediastinoscopy-assisted drainage (n = 1). We could not rescue 3 patients because of uncontrolled sepsis before surgery, for a mortality rate of 16.7%. Klebsiella pneumoniae uniquely represents the most common pathogen in diabetic patients (P = .01), leading to more complicated courses in older patients (P =.04) and requiring more surgical interventions (P =.05) than other pathogens. CONCLUSION Transcervical mediastinal drainage is first justified in patients with limited disease in the upper mediastinum. For those with involvement of the lower anterior mediastinum, an additional subxiphoid approach is suggested. Cervicotomy with video-assisted mediastinal drainage is an excellent combination for involvement of the posterior mediastinum and pleural space. Klebsiella pneumoniae uniquely represents the most important and threatening causative pathogen for diabetic patients with descending necrotizing mediastinitis.

Nonintubated thoracoscopic surgery using regional anesthesia and vagal block and targeted sedation

OBJECTIVE Thoracoscopic surgery without endotracheal intubation is a novel technique for diagnosis and treatment of thoracic diseases. This study reported the experience of nonintubated thoracoscopic surgery in a tertiary medical center in Taiwan. METHODS From August 2009 through August 2013, 446 consecutive patients with lung or pleural diseases were treated by nonintubated thoracoscopic surgery. Regional anesthesia was achieved by thoracic epidural anesthesia or internal intercostal blockade. Targeted sedation was performed with propofol infusion to achieve a bispectral index value between 40 and 60. The demographic data and clinical outcomes were evaluated by retrospective chart review. RESULTS Thoracic epidural anesthesia was used in 290 patients (65.0%) while internal intercostal blockade was used in 156 patients (35.0%). The final diagnosis were primary lung cancer in 263 patients (59.0%), metastatic lung cancer in 38 (8.5%), benign lung tumor in 140 (31.4%), and pneumothorax in 5 (1.1%). The median anesthetic induction time was 30 minutes by thoracic epidural anesthesia and was 10 minutes by internal intercostal blockade. The operative procedures included lobectomy in 189 patients (42.4%), wedge resection in 229 (51.3%), and segmentectomy in 28 (6.3%). Sixteen patients (3.6%) required conversion to tracheal intubation because of significant mediastinal movement (seven patients), persistent hypoxemia (two patients), dense pleural adhesions (two patients), ineffective epidural anesthesia (two patients), bleeding (two patients), and tachypnea (one patient). One patient (0.4%) was converted to thoracotomy because of bleeding. No mortality was noted in our patients. CONCLUSIONS Nonintubated thoracoscopic surgery is technically feasible and safe and can be a less invasive alternative for diagnosis and treatment of thoracic diseases.

Non-intubated thoracoscopic surgery using internal intercostal nerve block, vagal block and targeted sedation

OBJECTIVES Thoracoscopic surgery using internal intercostal nerve block, vagal block and targeted sedation without endotracheal intubation is a promising technique for selected patients, but little is known about its feasibility and safety. METHODS We evaluated 109 patients with lung (105), mediastinal (3) or pleural (1) tumours treated using non-intubated thoracoscopic surgery. Internal, intercostal nerve block was performed at the T3-T8 intercostal level and vagal block was performed adjacent to the vagus nerve at the level of the lower trachea for right-sided operations and at the level of the aortopulmonary window for left-sided operations. Sedation was performed with propofol infusion to achieve a bispectral index value between 40 and 60. RESULTS Thoracoscopic lobectomy was performed in 43 patients, wedge resection in 50, segmentectomy in 12 and mediastinal or pleural tumour excision in 4. Three patients (2.8%) required conversion to intubated one-lung ventilation because of vigorous mediastinal movement and dense diaphragmatic adhesions. Anaesthetic induction and operation had a median duration of 10.0 and 127.0 min, respectively. Operative complications developed in 13 patients with air leaks for more than 3 days and 1 patient required transfusion of blood products. The median postoperative chest drainage and hospital stay were 2.0 and 4.0 days, respectively. CONCLUSIONS Non-intubated thoracoscopic surgery using internal intercostal nerve block, vagal block and targeted sedation is technically feasible and safe in surgical treatment of lung, mediastinal and pleural tumours in selected patients.