Kwhanmien Kim

Formability of AA5182/polypropylene/AA5182 sandwich sheets

Abstract A sandwich sheet, AA5182/polypropylene/AA5182 (AA/PP/AA), has been developed by the roll bonding of two AA5182 aluminum alloy skin sheets with a pre-rolled polypropylene core sheet at 140xa0°C. The strain-hardening exponent of the aluminum skin was higher than that of the sandwich sheet, while the strain rate sensitivity of the sandwich sheet was higher than that of the aluminum skin. In order to optimize the sandwich sheet, the formability has been analyzed by constructing the forming limit diagram (FLD) based on the modified Marciniak–Kuczynski (M–K) theory. To account for the planar anisotropic property of the aluminum alloy skin sheet, Hill’s and Barlat’s new yield functions, published in 1948 and 2000, respectively, were employed. When compared with experimental results, the calculated FLD showed reasonably good qualitative agreement. Further analysis showed that the positive effect of the higher strain rate sensitivity of the sandwich sheet is compensated for by the negative effect of its lower strain-hardening exponent so that the greater thickness was the main cause of the higher formability of the sandwich sheet compared to that of the skin sheet.

Staple Line Coverage After Bullectomy for Primary Spontaneous Pneumothorax: A Randomized Trial

BACKGROUNDnThoracoscopic wedge resection is generally accepted as a standard surgical procedure for primary spontaneous pneumothorax. Because of the relatively high recurrence rate after surgery, additional procedures such as mechanical pleurodesis or visceral pleural coverage are usually applied to minimize recurrence, although mechanical pleurodesis has some potential disadvantages. The aim of this study was to clarify whether an additional coverage procedure on thexa0staple line after thoracoscopic bullectomy prevents postoperative recurrence compared with additional pleurodesis.nnnMETHODSnA total of 1,414 patients in 11 hospitals with primary spontaneous pneumothorax undergoing thoracoscopic bullectomy were enrolled. After bullectomy with staplers, patients were randomly assigned to either the coverage group (nxa0= 757) or the pleurodesis group (nxa0= 657). In the coverage group, the staple line was covered with absorbable cellulose mesh and fibrin glue. The pleurodesis group underwent additional mechanical abrasion on the parietal pleura.nnnRESULTSnThe coverage group and the pleurodesis group showed comparable surgical outcomes. After a median follow-up of 19.5 months, the postoperative 1-year recurrence rate was 9.5% in the coverage group and 10.7% in the pleurodesis group. The 1-year recurrence rate requiring intervention was 5.8% in the coverage group and 7.8% in the pleurodesis group. The coverage group showed better recovery from pain.nnnCONCLUSIONSnIn terms of postoperative recurrence rate, visceral pleural coverage after thoracoscopic bullectomy was not inferior to mechanical pleurodesis. Visceral pleural coverage may potentially replace mechanical pleurodesis, which has potential disadvantages such as disturbed normal pleural physiology.

Predictive factors for node metastasis in patients with clinical stage I non-small cell lung cancer.

BACKGROUNDnAccurate clinical staging of non-small cell lung cancer (NSCLC) is essential for developing a treatment plan and evaluating suitability for minimally invasive surgery. The aim of this study was to evaluate predictive factors for metastasis of N1 and N2 nodes in clinical stage I NSCLC.nnnMETHODSnRecords of patients with clinical stage I NSCLC who had undergone pulmonary resection with systematic node dissection or node sampling between 2003 and 2011 were retrospectively reviewed. To identify predictive factors for node metastasis, univariate and multivariate logistic regression analyses were performed.nnnRESULTSnAmong the 770 patients in this study, the overall prevalence of node metastasis was 19.4%, which included 11.3% of N1 nodes and 8.1% of N2 nodes. Predictive factors for N1 node metastasis included male sex, current smoker, non-adenocarcinoma, solid consistency, centrally located tumor, clinical T stage, cytokeratin fragment 21-1 level, tumor size, maximum standardized uptake value of the mass, and ground-glass opacity proportion. Adenocarcinoma, solid consistency, clinical T stage, carcinoembryonic antigen level, tumor size, and ground-glass opacity proportion were identified as predictors for N2 node metastasis. Both tumor size and solid consistency were independent predictive values of N1 node and N2 node metastasis by multivariate analysis.nnnCONCLUSIONSnAmong the patients with clinical stage I NSCLC, 19.4% of the patients showed unexpected node metastasis, and large size and solid consistency of the tumor were predictive factors of node metastasis in clinical stage I NSCLC. Preoperative staging should be performed more thoroughly to increase the accuracy of preoperative staging, especially in those who have the larger size and solid consistency of the tumor.

Pathology and Prognosis of Persistent Stable Pure Ground-Glass Opacity Nodules After Surgical Resection

BACKGROUNDnThis study aimed to show the pathologic results of pure ground glass opacities (pGGOs) that showed no change in patients who underwent surgical resection.nnnMETHODSnThe data used in this study were collected from the records of patients who underwent surgical resection for pGGOs between January 2004 and December 2009. All pGGOs were detected and followed up until operation with high-resolution computed tomography atxa0our hospital and were followed up by computed tomography of the chest at least 2 years after operation. Surgical resection was performed for patients with pGGOs if no change was observed after a minimum of 1xa0month of follow-up and if any growth of the nodules or newly formed solid components occurred in pGGOs of any size.nnnRESULTSnForty-six patients were enrolled into the study group. No changes in the pGGOs during serial follow-up occurred in 39 patients (84.8%), and 7 patients (15.2%) underwent surgical resection because of growth of the lesions or newly developed solid lesions during follow-up. Of 39 patients in the no-change group, pathologic types ofxa0the cancerous pGGOs in 23 patients included adenocarcinoma in situ in 21 patients, minimally invasive adenocarcinoma in 1 patient, and invasive adenocarcinoma in 1 patient. In the change group, 5 patients were diagnosed with cancer. Between the two groups, there was no difference in sex, time intervals, or tumor size.xa0Neither group had lymph node metastasis or recurrence.nnnCONCLUSIONSnThis study showed the pathology of persistent stable pGGO postoperatively, which confirmed the 59% chance of a cancer diagnosis including adenocarcinoma in situ, minimally invasive adenocarcinoma, or invasive adenocarcinoma.

Prediction of acute pulmonary complications after resection of lung cancer in patients with preexisting interstitial lung disease.

INTRODUCTIONnInterstitial lung disease (ILD) is associated with a high morbidity from acute pulmonary complications, such as acute lung injury (ALI) or acute respiratory distress syndrome (ARDS), after pulmonary resection. This study attempts to uncover the risk factors for postoperative ALI/ARDS in lung cancer patients with ILD.nnnMATERIALS AND METHODSnWe retrospectively reviewed 100 patients with ILD who underwent curative lung resection for lung cancer, from January 2000 to December 2008.nnnRESULTSnOf the 100 patients, 91 were male, and 9 were female. The median age was 66 years. Fifty-eight patients underwent a preoperative carbon monoxide diffusing capacity test (DLCo). Twelve pneumonectomies and 88 lobectomies were performed. Acute pulmonary complications were observed in 28 patients (13 with ALI and 15 with ARDS). Operative mortality was 14%. Cause of death was due to respiratory failure from ALI/ARDS in all patients, except in one patient who died due to complications of acute renal failure. For all 100 patients, univariate analysis revealed that preexisting comorbidities, such as ischemic heart disease, renal failure, COPD, and neoadjuvant treatment for lung cancer, were risk factors for the development of postoperative ALI/ARDS. For the 58 patients who underwent preoperative DLCo testing, significant univariate risk factors included preexisting comorbidities and decreased DLCo. Multivariate analysis did not show any significant risk factors for ALI/ARDS.nnnCONCLUSIONSnPreexisting comorbidities and decreased preoperative DLCo were the most significant risk factors for the development of acute pulmonary complications after pulmonary resection in patients with lung cancer and ILD.

The effect of postoperative change in bronchial angle on postoperative pulmonary function after upper lobectomy in lung cancer patients

OBJECTIVESnUpper lobectomy inevitably leads to an upward displacement of the remaining lower lobe. Such displacement may result in bronchial angulation, thereby narrowing the airway. We hypothesized that the degree of displacement of the bronchus is associated with the degree of exacerbation of postoperative pulmonary dysfunction. This study investigated whether bronchial angulation affects postoperative pulmonary function.nnnMETHODSnPatients undergoing upper lobectomy for lung cancer were retrospectively evaluated. A check for the presence of dyspnoea, pulmonary function test, chest X-ray and chest computed tomography (CT) were performed at 3 and 12 months postoperatively in these patients. The angle formed by the main bronchus and the bronchus intermedius on the right side and that by the main bronchus and the lower lobar bronchus were measured using the coronal view of the chest CT. We analysed the relationship between the change in bronchial angle and pulmonary function.nnnRESULTSnNinety-nine patients were enrolled in this study. Among these patients, 50 underwent left upper lobectomy (LUL) and 49 underwent right upper lobectomy (RUL). Nine patients who underwent LUL showed worsening symptoms, and among them, 8 presented an increase in the angle. However, among the 9 patients with worsening symptoms after RUL, only 4 presented an increase in the angle. Decreased forced expiratory volume in 1 s (FEV1) from 3 to 12 months after surgery was observed in 16 patients in the LUL group and 14 in the RUL group. Exacerbation of pulmonary dysfunction was associated with an increase in the bronchial angle (P = 0.04 for LUL and P = 0.02 for RUL). The degree of angle change was also associated with the extent of FEV1 reduction (P = 0.02 for LUL and P = 0.02 for RUL).nnnCONCLUSIONSnAlthough the change in the bronchial angle is a physiological condition, it can reduce postoperative pulmonary function. The measurement of the change in the angle using the coronal view of a chest CT is a useful screening tool for predicting the postoperative reduction in FEV1.

Inactivation of multidrug resistant (MDR)- and extensively drug resistant (XDR)-Mycobacterium tuberculosis by photodynamic therapy

We investigated the effects of photodynamic therapy (PDT) on anti-tuberculosis (TB) activity by measuring inactivation rates, expressed as D-value, of MDR- and XDR-Mycobacterium tuberculosis (M. tb) clinical strains in vitro. Approximately 10(6) colony forming unit per milliliter (CFU/ml) of the bacilli were irradiated with various doses of laser light after exposure to photosensitizers. Survival of M. tb was measured by enumerating CFU in 7H10 medium to measure D-values. No inactivation of M. tb was observed when exposed to photosensitizers (radachlorin or DH-I-180-3) only or laser light only (P>0.1). Treatment with a combination of photosentizer and laser inactivated M. tb although there was a significant difference between the types of photosensitizers applied (P<0.05). Linear inactivation curves for the clinical M. tb strains were obtained up to laser doses of 30 J/cm(2) but prolonged irradiation did not linearly inactivate M. tb, yielding sigmoid PDT inactivation curves. D-values of M. tb determined from the slope of linear regression lines in PDT were not significantly different and ranged from 10.50 to 12.13 J/cm(2) with 670 nm laser irradiation at 100 mW/cm(2) of the fluency rate, except for a drug-susceptible strain among the clinical strains tested. This suggests that PDT inactivated M. tb clinical strains regardless of drug resistance levels of the bacilli. Intermittent and repeated PDT allowed acceleration of the inactivation of the bacilli as a way to avoid the sigmoid inactivation curves. In conclusion, PDT could be alternative as a new option for treatment for MDR- and XDR-tuberculosis.

Frequency of Lymph Node Metastasis According to the Size of Tumors in Resected Pulmonary Adenocarcinoma with a Size of 30 mm or Smaller

Background: This study analyzed the relation between the tumor size and the lymph node metastasis in adenocarcinoma of the lung with a size of 30 mm or smaller. Methods: Four hundred thirteen patients who had undergone curative resection for lung adenocarcinoma were enrolled. If the tumor presented ground-glass opacities on the preoperative high-resolution computed tomography, both the total size including ground-glass opacities and the solid size alone were measured. To calculate the rates of lymph node metastasis by the tumor size, the tumors were divided into six groups by their sizes: 5 mm or less, 6 to 10 mm, 11 to 15 mm, 16 to 20 mm, 21 to 25 mm, and 26 to 30 mm. Results: The average numbers of dissected lymph nodes and dissected lymph node stations were 17 and 5, respectively. Seventy-five patients (18%) were postoperatively discovered to have positive nodes. The rates of node metastasis in each total size group were 0/1 (0%), 0/29 (0%), 5/77 (7%), 17/121 (14%), 27/101 (27%), and 26/84 (31%), respectively. The rates of node metastasis in each solid size group were 0/37 (0%), 1/53 (2%), 9/88 (10%), 17/104 (16%), 23/78 (30%), and 25/53 (47%), respectively. The area under the curve of receiver operating characteristic curves for the total size was measured as 0.701, and that for the solid size was measured as 0.777. By multivariate analysis, solid size, maximum standardized uptake value, and lymphovascular invasion were independent significant predictive factors. Conclusions: Solid size, maximum standardized uptake value, and lymphovascular invasion were independent predictors for lymph node metastasis of lung adenocarcinoma. The size of the solid component explained the relation between the tumor size and the lymph node metastasis more accurately than that explained by the total tumor size on high-resolution computed tomography.

Prognostic factors for post-recurrence survival in patients with completely resected Stage I non-small-cell lung cancer

OBJECTIVESnThe clinical course from recurrence to cancer-related death after curative resection has not been clearly elucidated in non-small-cell lung cancer (NSCLC). This study examined the clinical outcomes after postoperative recurrence in patients with completely resected Stage I NSCLC.nnnMETHODSnThis study included patients who had recurrence after complete resection for pathological Stage I NSCLC between 2003 and 2009. Clinical data evaluated in this study included the diagnostic process of recurrence, recurrence pattern, treatment process and prognosis. A number of clinicopathological factors were analysed for post-recurrence survival by univariate and multivariate analyses.nnnRESULTSnSeventy-two patients experienced recurrence during a median follow-up period of 37.5 months. Thirteen patients (18%) presented symptoms at the initial recurrence. Tumour markers, computed tomography (CT) and positron emission tomography/CT were chosen as the initial diagnostic tools and detected recurrences in 1 (1%), 51 (71%) and 7 (10%) patients, respectively. The mean recurrence-free interval (RFI) was 15.4 months (≤12 months in 34, >12 months in 38 patients). The patterns of recurrence were presented as loco-regional recurrence in 36 (50%) and distant metastasis in 36 patients (50%). Types of the initial treatment included operations in 28 (39%), chemotherapy and/or radiotherapy in 38 (53%) and radiofrequency ablation in 2 patients (3%). Four patients (6%) rejected treatment. Forty-three patients (62%) presented a good response to the initial treatment. Thirty-seven patients (51%) died, and the cause of death in all of these patients was cancer-related. The median survival duration after recurrence was 43.6 (1-136) months. Univariate analysis identified no recurrence of symptoms, a good response to treatment and a longer RFI as good prognostic factors, while a good response to treatment and a longer RFI were independent prognostic factors in multivariate analysis.nnnCONCLUSIONSnMost postoperative recurrences were detected in an asymptomatic condition during the routine follow-up period, and a good response to initial treatment and a longer RFI were significant predictors of better post-recurrence survival in patients with completely resected Stage I NSCLC.

Surgical resection of nodular ground-glass opacities without percutaneous needle aspiration or biopsy

BackgroundPercutaneous needle aspiration or biopsy (PCNA or PCNB) is an established diagnostic technique that has a high diagnostic yield. However, its role in the diagnosis of nodular ground-glass opacities (nGGOs) is controversial, and the necessity of preoperative histologic confirmation by PCNA or PCNB in nGGOs has not been well addressed.MethodsWe here evaluated the rates of malignancy and surgery-related complications, and the cost benefits of resecting nGGOs without prior tissue diagnosis when those nGGOs were highly suspected for malignancy based on their size, radiologic characteristics, and clinical courses. Patients who underwent surgical resection of nGGOs without preoperative tissue diagnosis from January 2009 to October 2013 were retrospectively analyzed.ResultsAmong 356 nGGOs of 324 patients, 330 (92.7%) nGGOs were resected without prior histologic confirmation. The rate of malignancy was 95.2% (314/330). In the multivariate analysis, larger size was found to be an independent predictor of malignancy (odds ratio, 1.086; 95% confidence interval, 1.001-1.178, p =0.047). A total of 324 (98.2%) nGGOs were resected by video-assisted thoracoscopic surgery (VATS), and the rate of surgery-related complications was 6.7% (22/330). All 16 nGGOs diagnosed as benign nodules were resected by VATS, and only one patient experienced postoperative complications (prolonged air leak). Direct surgical resection without tissue diagnosis significantly reduced the total costs, hospital stay, and waiting time to surgery.ConclusionsWith careful selection of nGGOs that are highly suspicious for malignancy, surgical resection of nGGOs without tissue diagnosis is recommended as it reduces costs and hospital stay.