Do Hyun Jung

Risk factors of postoperative pancreatic fistula in curative gastric cancer surgery.

Purpose Postoperative pancreatic fistula is a dreadful complication after gastric cancer surgery. The purpose of this study is to evaluate the actual incidence and risk factors of postoperative pancreatic fistula after curative gastrectomy for gastric cancer. Materials and Methods A total of 900 patients who underwent gastrectomy for gastric cancer (laparoscopic gastrectomy, 594 patients; open gastrectomy 306 patients) were enrolled between January 2009 and December 2010. Clinical outcomes, including postoperative pancreatic fistula grade based on the International Study Group on Pancreatic Fistula, were investigated. Results Overall, the postoperative pancreatic fistula rate was 3.3% (30/900) (1.5% in laparoscopic gastrectomy versus 6.9% in open gastrectomy, P<0.001). Patients who underwent D2 lymphadenectomy, total gastrectomy, splenectomy or distal pancreatectomy showed higher postoperative pancreatic fistula rates (4.7%, 13.8%, 13.6%, or 57.1%, respectively, P<0.001). Patients with postoperative pancreatic fistula had higher morbidity (46.7% versus 13.1%, P<0.001), delayed gas out (4.9 days versus 3.8 days, P<0.001), belated diet start (5.8 days versus 3.5 days, P<0.001) and longer postoperative hospital stay (13.7 days versus 6.8 days, P<0.001). On the multivariate analysis, total gastrectomy (odds ratio 9.751, 95% confidence interval: 3.348 to 28.397, P<0.001), distal pancreatectomy (odds ratio 7.637, 95% confidence interval: 1.668 to 34.961, P=0.009) and open gastrectomy (odds ratio 2.934, 95% confidence interval: 1.100 to 7.826, P=0.032) were the independent risk factors of postoperative pancreatic fistula. Conclusions Laparoscopic gastrectomy had an advantage over open gastrectomy in terms of the lower postoperative pancreatic fistula rate. Total gastrectomy and combined resection, such as distal pancreatectomy, should be performed carefully to minimize postoperative pancreatic fistula in gastric cancer surgery.

High speed Cu-Ni filling into TSV for 3-Dimensional Si chip stacking

The effect of Ni addition on high speed Cu filling into a TSV (through-silicon-via) was investigated for three dimensional (3D) Si chip stacking. Tapered vias were prepared in a Si wafer by deep reactive ion etching process. In order to increase the filling ratio of Cu-Ni into the via, a periodic pulse reverse (PPR) current waveform was applied for electroplating. For comparison Cu filling in the via was also carried out using a PPR current waveform. The Cu and Cu-Ni alloy-filled via was observed by field emission scanning electron microscopy (FE-SEM) to investigate the filling ratio of the vias and to observe the deposition characteristics. The calculated rate of Cu-Ni nuclei formation on the cathode surface was increased by about 1.7 times by Ni addition compared to Cu filling and the increased nucleation rate of the Cu-Ni alloy over Cu was confirmed by FE-SEM. The filling ratio of the Cu-Ni alloy was 1.3 times higher than that of Cu at the same time. The Cu-Ni filling process by the PPR current waveform was confirmed to be effective to fill the TSV in a short time.

Solo Intracorporeal Esophagojejunostomy Reconstruction Using a Laparoscopic Scope Holder in Single-Port Laparoscopic Total Gastrectomy for Early Gastric Cancer

Single-incision laparoscopic total gastrectomy for gastric cancer has recently been reported by Seoul National University Bundang Hospital. However, this is not a popular procedure primarily because of the technical difficulties involved in achieving consistent intracorporeal esophagojejunostomy. At Seoul National University Bundang Hospital, we recently introduced a simple, easy-to-use, low-profile laparoscopic manual scope holder that enables the maintenance of a stable field of view, the most demanding condition in single-port gastrectomy. In this technical report, we describe in detail the worlds first solo single-incision laparoscopic total gastrectomy with D1+ lymph node dissection and intracorporeal esophagojejunostomy for proximal early gastric cancer.

Electrical characteristics and thermal shock properties of Cu-filled TSV prepared by laser drilling

The electrical characteristics and thermal shock properties of a Through Silicon Via (TSV) for the three dimensional (3D) stacking of a Si wafer were investigated. The TSVs were fabricated on a Si wafer by a laser drilling process. The via had a diameter of 75 µm at the via opening and a depth of 150 µm. A daisy chain was made for testing electrical characteristics, such as Rsh (sheet resistance), Rc (contact resistance) and Z0 (characteristic impedance). After Cu filling, a cross section of the via was observed by Field Emission-Scanning Electron Microscopy. The electrical characteristics were measured using a commercial impedance analyzer and probe station, which revealed the values of Rsh, Rc and Z0 as 35.5 mΩ/sq, 25.4 mΩ and 48.5 Ω, respectively. After a thermal shock test of 500 cycles, no cracks were observed between the TSV and Si wafer. This study confirms that the laser drilling process is an effective method for via formation on a Si wafer for 3D integration technology.

Proximal Gastrectomy for Gastric Cancer

Laparoscopic proximal gastrectomy (LPG) is theoretically a superior choice of minimally-invasive surgery and function-preserving surgery for the treatment of proximal early gastric cancer (EGC) over procedures such as laparoscopic total gastrectomy (LTG), open total gastrectomy (OTG) and open proximal gastrectomy (OPG). However, LPG and OPG are not popular surgical options due to three main concerns: the first, oncological safety; the second, functional benefits; and the third, anastomosis-related late complications (reflux symptoms and anastomotic stricture). Numerous recent studies have concluded that OPG and LPG present similar oncological safety profiles and improved functional benefits when compared with OTG and LTG. While OPG with modified esophagogastrostomy does not provide satisfactory results, OPG with modified esophagojejunostomy showed similar rates of anastomosis-related late complications when compared to OTG. At this stage, no standard reconstruction method post-LPG exists in the clinical setting. We recently showed that LPG with double tract reconstruction (DTR) is a superior choice over LTG for proximal EGC in terms of maintaining body weight and preventing anemia. However, as there is no definitive evidence in favor of LPG with DTR, a randomized clinical trial comparing LPG with DTR to LTG was recommended. This trial, the Korean Laparoscopic Gastrointestinal Surgery Study-05 (NCT01433861), is expected to assist surgeons in choice of surgical approach and strategy for patients with proximal EGC.

Clinical Relevance of the Tumor Location-Modified Lauren Classification System of Gastric Cancer

Purpose The Lauren classification system is a very commonly used pathological classification system of gastric adenocarcinoma. A recent study proposed that the Lauren classification should be modified to include the anatomical location of the tumor. The resulting three types were found to differ significantly in terms of genomic expression profiles. This retrospective cohort study aimed to evaluate the clinical significance of the modified Lauren classification (MLC). Materials and Methods A total of 677 consecutive patients who underwent curative gastrectomy from January 2005 to December 2007 for histologically confirmed gastric cancer were included. The patients were divided according to the MLC into proximal non-diffuse (PND), diffuse (D), and distal non-diffuse (DND) type. The groups were compared in terms of clinical features and overall survival. Multivariate analysis served to assess the association between MLC and prognosis. Results Of the 677 patients, 48, 358, and 271 had PND, D, and DND, respectively. Their 5-year overall survival rates were 77.1%, 77.7%, and 90.4%. Compared to D and PND, DND was associated with significantly better overall survival (both P<0.01). Multivariate analysis showed that age, differentiation, lympho-vascular invasion, T and N stage, but not MLC, were independent prognostic factors for overall survival. Multivariate analysis of early gastric cancer patients showed that MLC was an independent prognostic factor for overall survival (odds ratio, 5.946; 95% confidence intervals, 1.524~23.197; P=0.010). Conclusions MLC is prognostic for survival in patients with gastric adenocarcinoma, in early gastric cancer. DND was associated with an improved prognosis compared to PND or D.

Non-PR Sn-3.5Ag Bumping on a Fast Filled Cu-Plug by PPR Current

The electroplating of Sn-3.5 wt% Ag bumps without a photoresist (PR) mould on a Si chip was performed to reduce the production steps and cost for 3-D chip stacking. The electroplating characteristics of Sn-Ag and Sn-Ag bump growth were examined. The Sn-Ag bumps were electroplated on the Cu-plugged TSVs (through-silicon vias) of a Si chip. The Cu plug in the via was produced using a high-speed Cu filling process by a periodic pulse reverse current waveform. The electroplating current was supplied to the exposed Cu surface in the TSVs to produce the Sn-3.5Ag bumps. As the experimental results show, the Sn-3.5Ag bumps were fabricated successfully without a PR mould, with no serious defects by electroplating. The Ag contents in the Sn-Ag bump decreased with increasing current density. Besides, the bump height and width increased with increasing plating time. The bump width grew isotropically because of the absence of a PR mould. The Sn-3.55 wt% Ag bumps were obtained at a current density of -55 mA/cm2 for 20 min on the Cu plugs.

Long-term Follow-up for Type 2 Diabetes Mellitus after Gastrectomy in Non-morbidly Obese Patients with Gastric Cancer: the Legitimacy of Onco-metabolic Surgery

Purpose This study primarily aimed to investigate the short- and long-term remission rates of type 2 diabetes (T2D) in patients who underwent surgical treatment for gastric cancer, especially patients who were non-obese, and secondarily to determine the potential factors associated with remission. Materials and Methods We retrospectively reviewed the clinical records of patients with T2D who underwent radical gastrectomy for gastric cancer, from January 2008 to December 2012. Results T2D improved in 39 out of 70 (55.7%) patients at the postoperative 2-year follow-up and 21 of 42 (50.0%) at the 5-year follow-up. In the 2-year data analysis, preoperative body mass index (BMI) (P=0.043), glycated hemoglobin (A1C) level (P=0.039), number of anti-diabetic medications at baseline (P=0.040), reconstruction method (statistical difference was noted between Roux-en-Y reconstruction and Billroth I; P=0.035) were significantly related to the improvement in glycemic control. Unlike the results at 2 years, the 5-year data analysis revealed that only preoperative BMI (P=0.043) and A1C level (P=0.039) were statistically significant for the improvement in glycemic control; however, the reconstruction method was not. Conclusions All types of gastric cancer surgery can be effective in short- and long-term T2D control in non-obese patients. In addition, unless long-limb bypass is considered in gastric cancer surgery, the long-term glycemic control is not expected to be different between the reconstruction methods.

Brazing Filler Metal and Process for Stainless Steel

Abstract Brazing technology has been widely used among bonding technologies because it enables to bond variousmetals, even ceramics, dissimilar metals, and give higher bonding strength, cost down, automation, etc. However, there are many parameters to achieve optimal brazing joint such as brazing alloys, brazing atmospheres, designs and brazing methods, etc. The brazing parameters affect seriously on the characteristic of final brazingproducts. Stainless steel is broadly used in high temperature applications, chemical industry, heat exchangers,muffler of vehicles, and so on. Accordingly, in this article, brazing alloys, forms of brazing alloys, brazing methods and atmospheres for stainless steel were described.Key Words : Stainless steel, Brazing, Nickel brazing, Furnace brazing, Brazing alloy 1. 서 론 스테인리스강은 통상 Cr의 함량이 12% 이상인 철 (Fe) 합금을 말하는데, 첨가 원소의 종류와 양에 따라 페라이트계, 오스테나이트계, 마르텐사이트계, 석출경화계 등으로 나뉘어진다. 스테인리스강은 열교환기나, 화학 공업, 고온 및 저온용 소재, 식기, 배기관 등 산업 전반에 걸쳐 구조부품이나 기계부품으로 사용되고 있다. 스테인리스강의 접합법으로서의 브레이징은 대량 생산이 가능하고, 접합이 용이하며, 접합 후 가공이 필요 없는 장점이 있어 널리 사용되고 있다. 본고에서는 브레이징 합금, 브레이징 방법, 브레이징 분위기 등과 스테인리스강의 브레이징성에 관해 기술하고자 한다.