Causative bacteria associated with a clinically relevant postoperative pancreatic fistula infection after distal pancreatectomy.

PURPOSE: Clinically relevant postoperative pancreatic fistulas (CR-POPF) occurring after distal pancreatectomy often cause intra-abdominal infections. We monitored the presence of bacterial contamination in the ascitic fluid after distal pancreatectomy to clarify the bacterial origin of intra-abdominal infections associated with CR-POPF. METHODS: In 176 patients who underwent distal pancreatectomy, ascitic fluid bacterial cultures were performed on postoperative days (POD) 1-4 and when the drainage fluid became turbid. The association between postoperative ascitic bacterial contamination and CR-POPF incidence was investigated. RESULTS: CR-POPF occurred in 18 cases (10.2%). Among the patients with CR-POPF, bacterial contamination was detected in 0% on POD 1, in 38.9% on POD 4, and in 72.2% on the day (median, day 9.5) when the drainage fluid became turbid. A univariate analysis revealed a significant difference in ascitic bacterial contamination on POD 4 (p < 0.001) and amylase level on POD 3-4 (p < 0.001). A multivariate analysis revealed the amylase level and ascitic bacterial contamination on POD 4 to be independent risk factors. CONCLUSIONS: In the CR-POPF group, ascitic bacterial contamination was not observed in the early postoperative stage, but the bacterial contamination rate increased after pancreatic juice leakage occurred. Therefore, CR-POPF-related infections in distal pancreatectomy may be caused by a retrograde infection of pancreatic juice.

Clinical Impact of Neoadjuvant Chemotherapy and Chemoradiotherapy in Borderline Resectable Pancreatic Cancer: Analysis of 884 Patients at Facilities Specializing in Pancreatic Surgery.

BACKGROUND: The efficacy of neoadjuvant therapy (NAT), including neoadjuvant chemotherapy (NAC) and neoadjuvant chemo-radiotherapy (NACRT), for patients with borderline resectable pancreatic cancer (BRPC) has not been elucidated. This study aimed to clarify the efficacy of NAC and NACRT for patients with BRPC. METHODS: The study analyzed the treatment outcomes of 884 patients treated for BRPC from 2011 to 2013. Treatment results were compared between upfront surgery and NAT and between NAC and NACRT using propensity score-matching analysis. Overall survival (OS) was calculated via intention-to-treat analyses. RESULTS: The overall resection rates for the patients who underwent NAT were significantly lower than for the patients who underwent upfront surgery (75.1% vs 93.3%; p < 0.001). However, the R0 resection rate was significantly higher for NAT than for upfront surgery (p < 0.001). Additionally, the OS for the patients who received NAT was significantly longer than for those who underwent upfront surgery (median survival time [MST], 25.7 vs 19.0 months; p = 0.015). The lymph node rate for the patients with NACRT was significantly lower than for those who underwent NAC (p < 0.001). However, the resection rate for the NACRT cases was significantly lower than for the NAC cases (p = 0.041). The local recurrence rate for the NACRT cases was significantly lower than for the NAC cases (p = 0.002). However, OS did not differ significantly between NAC and NACRT (MST, 29.2 vs 22.5 months; p = 0.130). CONCLUSIONS: The study showed that NAT has potential benefit for patients with BRPC. Compared with NAC, NACRT decreased the rates for lymph node metastasis and local recurrence but did not improve the prognosis.

Approaching the superior mesenteric artery from the right side using the proximal-dorsal jejunal vein preisolation method during laparoscopic pancreaticoduodenectomy.

BACKGROUND: Although the artery-first approach is widely used in open pancreaticoduodenectomy, it is difficult to laparoscopically expose the origin of the inferior pancreaticoduodenal artery (IPDA) from the left side of the superior mesenteric artery (SMA). By contrast, damaging the inferior pancreaticoduodenal veins (IPDVs) is possible when approaching the IPDA from the right side of the SMA. To facilitate the artery-first approach in laparoscopic pancreaticoduodenectomy (LPD), we focused on the proximal-dorsal jejunal vein (PDJV) that branched from the superior mesenteric vein (SMV) dorsal side and drained the IPDVs. This study aimed to clarify the usefulness of the right SMA approach using the PDJV preisolation method. METHODS: The PDJV was first isolated, and the IPDVs were divided along the PDJV on the right side of the SMA. Then, the IPDA was divided at the root without first separating the pancreatic head from the portal vein and the SMV. Overall, 21 patients underwent this approach, and the results were retrospectively compared with those of 21 patients who underwent the artery-first approach, which was performed on the left side of the SMA. Anatomical characteristics of the PDJV were evaluated using multidetector computed tomography for the two groups. RESULTS: Operative times and resection times were significantly lower for the PDJV preisolation group than for the conventional LPD group (489.3 vs. 541.7 min, respectively; p = 0.002). During anatomical evaluation, 41 patients (97.6%) had a PDJV that drained from the SMV dorsally and was in contact with the anterior aspect of the uncinate process. The PDJV was confirmed as the first jejunal vein in 31 patients (73.8%) and as the second jejunal vein in 10 patients (23.8%). CONCLUSIONS: This approach facilitates dissection of the IPDA on the right side of the SMA, thereby reducing operative times.

Serum SPan-1 Is a Significant Risk Factor for Early Recurrence of Pancreatic Cancer after Curative Resection.

BACKGROUND/AIMS: Curative resection is still the only treatment for patients with pancreatic ductal adenocarcinoma (PDAC). However, early postoperative recurrence occurs frequently. The aim of this study was to investigate the predictors of early recurrence of PDAC. METHODS: Clinical data of 172 consecutive patients with PDAC who underwent curative resection (R0) between 2000 and 2015 at Tokyo Medical University Hospital were retrospectively analyzed. RESULTS: The median follow-up period was 18.2 months. Recurrence occurred in 96 of 172 (55.8%) patients, 27 in whom recurrence occurred within 6 months (early recurrence). Median survival time of the early recurrence group was 10.7 months. The optimal cutoff concentrations for the prediction of early recurrence were 111.3 U/ml, 3.0 ng/ml, 41 U/ml and 670 U/ml for CA19-9, carcinoembryonic antigen, SPan-1 and DUPAN-2, respectively. Multivariate analysis demonstrated that a SPan-1 concentration of >41 U/ml, having received neoadjuvant therapy and having never received adjuvant chemotherapy were significant and independent predictors of early recurrence. CONCLUSION: A preoperative SPan-1 concentration of >41 U/ml is a significant and independent predictor of the early recurrence of pancreatic adenocarcinoma.

The Straightened Splenic Vessels Method Improves Surgical Outcomes of Laparoscopic Distal Pancreatectomy.

BACKGROUND: In laparoscopic distal pancreatectomy (LDP), isolating the splenic artery and vein requires advanced techniques. This study aimed to assess the efficacy of a novel method termed the 'straightened splenic vessels' (SSV) method for isolating the splenic vessels in LDP. METHODS: In SSV, to adjust the instrument axis, the splenic artery was straightened by grasping 2 points of its nerve sheath. Then, the layer between the splenic artery's nerve sheath and the pancreatic parenchyma was dissected. Next, the pancreas was mobilized from body to tail, and the splenic vein was straightened by 3-point retraction before isolation. To evaluate this method's efficacy, we investigated 51 patients who underwent LDP. RESULTS: In 39 patients who underwent LDP with splenectomy, the mean operating time was significantly shorter in the SSV group than in the conventional group (p = 0.004). In 12 patients who underwent LDP with preserving the splenic vessels, the mean intraoperative blood loss in the SSV group was 27.6 ml, which was significantly lower than that in the conventional group (p = 0.012). CONCLUSION: This method may be applied as a standard procedure with little blood loss and short operation time for LDP. Larger prospective studies are needed to further evaluate the feasibility.

Serum Type IV Collagen Concentration Correlates with Indocyanine Green Retention Rate.

BACKGROUND/AIMS: Assessment of oxaliplatin-associated hepatotoxicity in patients receiving oxaliplatin, fluorouracil and leucovorin chemotherapy (FOLFOX) for colorectal cancer remains controversial. The aims of this study were to clarify which variables are indicators of such hepatotoxicity. METHODOLOGY: Twenty-seven patients who were to receive FOLFOX for colorectal cancer were included in this study. A range of liver function tests, including serum hyaluronic acid (HA) and type IV collagen concentrations, indocyanine green (ICG) retention rate at 15 min (ICGR15) and splenic volume were assessed before commencement of chemotherapy and after four cycles of FOLFOX. RESULTS: No significant changes were found in conventional liver function tests or splenic volume. Significant changes pre- and post-FOLFOX were found in type IV collagen concentrations and ICGR15. Correlation analyses showed that the following two factors were associated with significant changes in ICGR15 after four cycles of FOLFOX: platelet count (p = 0.028, correlation coefficient 0.423), and type IV collagen concentration (p < 0.001, correlation coefficient 0.830). The regression line between type IV collagen concentration and ICGR15 was Y = 2.70 + 0.84 x X. CONCLUSION: Serum type IV collagen concentration is an indicator of oxaliplatin-associated hepatotoxicity and correlates with significant changes in ICGR15 in patients receiving FOLFOX.

A Novel "Artery First" Approach Allowing Safe Resection in Laparoscopic Pancreaticoduodenectomy: The Uncinate Process First Approach.

BACKGROUND/AIMS: Laparoscopic pancreaticoduodenectomy (LPD) is still a challenging operation, particularly because the dissection around the superior mesenteric artery (SMA) and bleeding control are difficult. Although it has been reported that early ligation of the origin of the inferior pancreaticoduodenal artery (IPDA) reduces blood loss, it is difficult to laparoscopically expose the origin of the IPDA. We sought to develop a novel approach to simplify the dissection of the IPDA and reduce bleeding. METHODOLOGY: The uncinate process was exposed at the left posterior side of the SMA, and the branches of the IPDA were divided at positions where they enter and exit the uncinate process before isolating the pancreatic head from the right aspect of the SMA. Ten patients were operated using this new approach, and the results were retrospectively compared to those of 22 patients treated with conventional LPD. RESULTS: The operation times did not differ significantly between the two groups. However, the intraoperative blood loss was significantly lower in the "uncinate process first" group than in the conventional LPD group. (162.7 ml vs. 463.8 ml, respectively; P = 0.023). CONCLUSIONS: The new approach facilitates the initial dissection of the IPDA at the right side of the SMA, reducing intraopera- tive blood loss.

Serum Type IV Collagen Concentration Correlates with Indocyanine Green Retention Rate and is an Indicator Of Hepatotoxicity In Patients Receiving FOLFOX for Colorectal Cancer.

BACKGROUND: Assessment of oxaliplatin-associated hepatotoxicity in patients receiving oxaliplatin, fluorouracil and leucovorin chemotherapy (FOLFOX) for colorectal cancer remains controversial. The aims of this study were to clarify which variables are indicators of such hepatotoxicity. METHODOLOGY: Twenty-seven patients who were to receive FOLFOX for colorectal cancer were included in this study. A range of liver function tests, including serum hyaluronic acid (HA) and type IV collagen concentrations, indocyanine green (ICG) retention rate at 15 min (ICGR15) and splenic volume were assessed before commencement of chemotherapy and after four cycles of FOLFOX. RESULTS: No significant changes were found in conventional liver function tests or splenic volume. Significant changes pre- and post-FOLFOX were found in type IV collagen concentrations and ICGR15. Correlation analyses showed that the following two factors were associated with significant changes in ICGR15 after four cycles of FOLFOX: platelet count (p = 0.028, correlation coefficient 0.423), and type IV collagen concentration (p < 0.001, correlation coefficient 0.830). The regression line between type IV collagen concentration and ICGR15 was Y = 2.70 + 0.84 x X. CONCLUSION: Serum type IV collagen concentration is an indicator of oxaliplatin-associated hepatotoxicity and correlates with significant changes in ICGR15 in patients receiving FOLFOX.

[A Large Number of Circulating Tumor Cells(CTCs)Can Be Isolated from Samples Obtained by Using Leukapheresis Procedures].

We hypothesized that a large number of circulating tumor cells(CTCs)may be isolated from samples obtained by using the leukapheresis procedures that are utilized to collect peripheral blood mononuclear cells for dendritic cell vaccine therapy. We utilized the CellSearch System to determine the number of CTCs in samples obtained by using leukapheresis in 7 patients with colorectal cancer, 5 patients with breast cancer, and 3 patients with gastric cancer. In all patients, a large number of CTCs were isolated. The mean number of CTCs per tumor was 17.1(range 10-34)in colorectal cancer, 10.0(range 2-27)in breast cancer, and 24.0(range 2-42)in gastric cancer. We succeeded in culturing the isolated CTCs from 7 patients with colorectal cancer, 5 patients with breast cancer, and 3 patients with gastric cancer. In conclusion, compared to conventional methods, a large number of CTCs can be obtained by using leukapheresis procedures. The molecular analyses of the CTCs isolated by using this method should be promising in the development of personalized cancer treatments.

Limited subtotal gastrectomy for early remnant gastric cancer.

BACKGROUND: Detection of early remnant gastric cancer (ERGC) is increasing as a result of the development of endoscopic technology and a surveillance program. The aim of this study was to evaluate the results of limited subtotal gastrectomy (SG) surgery for ERGC compared to total gastrectomy (TG). METHODS: We retrospectively reviewed a database of 72 consecutive patients with remnant gastric cancer who underwent laparotomy at the National Cancer Center Hospital East between January 1993 and December 2008. Thirty-five patients with a preoperative diagnosis of ERGC underwent curative resection: 13 SG and 22 conventional TG. Patients and tumor characteristics, operative results, and postoperative assessments 1 year after surgery were compared between the two groups. RESULTS: Operating time, blood transfusion, and hospital stay were similar in the two groups. In the SG group, blood loss and postoperative recovery of body weight tended to be better than in the TG group. There was no dumping syndrome in the SG group, while this occurred in three patients in the TG group. The levels of hemoglobin and total protein were higher 1 year after remnant gastrectomy in the SG group than in the TG group. No recurrence of gastric cancer was detected in the SG group during median follow-up of 99.2 months. CONCLUSION: In comparison to TG, limited SG surgery for ERGC improved the postoperative course, with no recurrence of cancer. Therefore, SG is a safe and effective treatment for ERGC.

Pancreaticoduodenectomy with right-oblique posterior dissection of superior mesenteric nerve plexus is logical procedure for pancreatic cancer with extrapancreatic nerve plexus invasion.

BACKGROUND/AIMS: To achieve R0 resection, pancreaticoduodenectomy with right-side half dissection of the superior mesenteric artery nerve plexus is performed for pancreatic cancer with extrapancreatic nerve plexus invasion in many facilities. However, this cancer mainly spreads behind the superior mesenteric artery. METHODOLOGY: Forty-two patients underwent pancreaticoduodenectomy with right-oblique posterior dissection of the superior mesenteric artery nerve plexus from the 4 to 10 o'clock position for pancreatic ductal adenocarcinoma. The cancer spread was evaluated using preoperative multi-detector computed tomography and postoperative pathological examination. RESULTS: Thirty-one patients (73.8%) showed extrapancreatic nerve plexus invasion on multi-detector computed tomography. In 20 patients (47.6%), the tumor extended within 5 mm of the superior mesenteric artery, ranging between the 4-10 o'clock position in 19 (95.0%) patients. Although pathological examination revealed that the cancer infiltrated within 3 mm of the superior mesenteric artery margin in 17 (54.8%) patients with extrapancreatic nerve plexus invasion, R0 resection was achieved in 95.2% of cases. Six patients (14.3%) experienced postoperative diarrhea requiring administration of antidiarrheal agents. CONCLUSIONS: Pancreatic head cancer spreads mainly right-posterior of the superior mesenteric artery; and therefore, right-oblique posterior dissection is a logical procedure to achieve negative margin resection with complete clearance of nerve plexus involvement.

Indication of conservative treatment by antibiotics for uncomplicated and complicated acute appendicitis.

BACKGROUND: Acute appendicitis is one of the most common emergency abdominal disease, and recent studies have evaluated conservative treatment using antibiotics for uncomplicated appendicitis. Although the efficacy of conservative treatment for uncomplicated appendicitis is known, its efficacy for complicated appendicitis remains unknown, so are risk factors for the conservative treatment of appendicitis. In our institution, conservative treatment has long been the first choice for most appendicitis cases, except for perforation. Therefore, this novel study investigated the outcomes of conservative treatment for uncomplicated and complicated acute appendicitis and the risk factors associated with conservative treatment. AIM: To investigate the indication of conservative treatment by antibiotics for uncomplicated and complicated acute appendicitis. METHODS: We investigated 270 patients who received conservative treatment for acute appendicitis at the Nishitokyo Central General Hospital, between April 2011 and February 2022. Twenty-eight (10.3%) patients were resistant to conservative treatment and underwent surgery. We retrospectively investigated the outcomes of conservative treatment for appendicitis and the risk factors for resistance to conservative treatment using the receiver operating characteristic curves and Cox hazard model. RESULTS: Two hundred and forty-two (89.7%) patients improved with conservative treatment. The significant and independent predictors of resistance to conservative treatment were body temperature ≥ 37.3 °C, appendicolith and Douglas sinus fluid visible on computed tomography (CT). The rate of resistance to conservative treatment was 66.7% (6/9) for patients with the above three factors, 22.9% (8/35) for patients with two factors (appendicolith and body temperature ≥ 37.3 °C), 16.7% (2/12) for patients with two factors (Douglas sinus fluid and appendicolith) and 11.1% (1/9) for patients with two factors (Douglas sinus fluid and body temperature ≥ 37.3 °C). CONCLUSION: A temperature ≥ 37.3 °C, appendicolith and Douglas sinus fluid on CT might be clinical risk factors of resistance to conservative treatment for acute appendicitis.

Clinicopathological features and prognostic factors of adenocarcinoma of the esophagogastric junction according to Siewert classification: experiences at a single institution in Japan.

BACKGROUND: Treatment strategy for adenocarcinoma of the esophagogastric junction (AEG) remains controversial. The aims of this study are to evaluate results of surgery for AEG, to clarify clinicopathological differences according to the Siewert classification, and to define prognostic factors. METHODS: We retrospectively analyzed 179 consecutive patients with Siewert type I, II, and III AEG who underwent curative (R0) resection at the National Cancer Center Hospital East between January 1993 and December 2008. RESULTS: Patients with AEG were divided according to tumor: 10 type I (5.6%), 107 type II (59.8%), and 62 type III (34.6%). Larger, deeper tumors and nodal metastasis were more common in type III than type II tumors. No significant differences were seen in 5-year survival rates among the three types: type I (51.4%), type II (51.8%), and type III (62.6%). Multivariate analysis showed that depth of tumor and mediastinal lymph node metastasis were independent prognostic indicators. The recurrence rate for patients with mediastinal lymph node metastasis was 87.5%. The risk factors for mediastinal lymph node metastasis were length of esophageal invasion and histopathological grade. CONCLUSIONS: Mediastinal lymph node metastasis and tumor depth were significant and independent factors for poor prognosis after R0 resection for AEG. Esophageal invasion and histopathological grade were significant and independent factors for mediastinal lymph node metastasis.

Reconsideration of the Appropriate Dissection Range Based on Japanese Anatomical Classification for Resectable Pancreatic Head Cancer in the Era of Multimodal Treatment.

Patients with resectable pancreatic cancer are considered to already have micro-distant metastasis, because most of the recurrence patterns postoperatively are distant metastases. Multimodal treatment dramatically improves prognosis; thus, micro-distant metastasis is considered to be controlled by chemotherapy. The survival benefit of "regional lymph node dissection" for pancreatic head cancer remains unclear. We reviewed the literature that could be helpful in determining the appropriate resection range. Regional lymph nodes with no suspected metastases on preoperative imaging may become areas treated with preoperative and postoperative adjuvant chemotherapy. Many studies have reported that the R0 resection rate is associated with prognosis. Thus, "dissection to achieve R0 resection" is required. The recent development of high-quality computed tomography has made it possible to evaluate the extent of cancer infiltration. Therefore, it is possible to simulate the dissection range to achieve R0 resection preoperatively. However, it is often difficult to distinguish between areas of inflammatory changes and cancer infiltration during resection. Even if the "dissection to achieve R0 resection" range is simulated based on the computed tomography evaluation, it is difficult to identify the range intraoperatively. It is necessary to be aware of anatomical landmarks to determine the appropriate dissection range during surgery.

Clinical impact of pancreaticoduodenectomy for pancreatic cancer with resection of the secondary or later branches of the superior mesenteric vein.

PURPOSE: To evaluate the feasibility of pancreaticoduodenectomy with resection of the second jejunal vein (J2V) for pancreatic ductal adenocarcinoma (PDAC). METHODS: Among 114 patients with PDAC undergoing pancreaticoduodenectomy with portal-superior mesenteric vein resection (PVR), surgical outcomes, and prognoses of 10 patients with resection of J2V or later branches of the superior mesenteric vein (J2VR) were compared to 104 patients with PVR above J2V (standard PVR). The reconstruction methods in the J2VR group were reviewed. RESULTS: There were no significant differences in the operative time (470 vs 435 min), morbidity (30% vs 27%), presence of portal vein stenosis (10% vs 5%) or thrombosis (10% vs 1%), and induction of adjuvant therapy (80% vs 88%) between the J2VR and standard PVR groups, although blood loss was higher in the J2VR group (1184 vs 494 ml; P = .002). R0 proportion and 2-year survival rates were not significantly worse in the J2VR group compared to the standard PVR group (90 and 88%; 67 and 45%, respectively). At least one branch of the superior mesenteric vein was reconstructed in the J2VR group. CONCLUSION: Pancreaticoduodenectomy with J2VR for PDAC can be safely performed with a satisfactory overall survival rate.

Preoperative cholangitis is associated with increased surgical site infection following pancreaticoduodenectomy.

BACKGROUND: Few reports describe the relationship between preoperative cholangitis and surgical site infections (SSIs) after pancreaticoduodenectomy (PD). We aimed to determine the association between the incidence of preoperative cholangitis and surgical site infection following PD. METHODS: The surgical outcomes of 359 patients who underwent PD were compared between patients with (n = 92) and without (n = 267) preoperative cholangitis. Bacterial cultures from the postoperative drainage fluid were examined. Risk factors for postoperative infectious complication were evaluated. RESULTS: The incidence of postoperative infectious complications including grade B/C postoperative pancreatic fistula was high among patients with preoperative cholangitis (P < .01). The positive rate of bacterial culture in the drainage fluid until postoperative day 3 (P < .01) and the detection rate of Enterococcus species (P < .01) were higher in the preoperative cholangitis group. The most common cause of preoperative cholangitis was drainage device dysfunction mainly with plastic stent occlusion. In the multivariate analysis, preoperative cholangitis (odds ratio 2.04, 95% confidence interval 1.13 to 3.69; P = .02) was an independent risk factor for postoperative infectious complications. CONCLUSIONS: Preoperative cholangitis significantly increased ascitic bacterial contamination and the incidence of postoperative infectious complications. after PD. Appropriate preoperative biliary drainage for the prevention of preoperative cholangitis is important for improving outcomes after PD.

Blumgart method using LAPRA-TY clips facilitates pancreaticojejunostomy in laparoscopic pancreaticoduodenectomy.

The modified Blumgart method for pancreaticojejunostomy has been shown to reduce the rate of postoperative pancreatic fistula (POPF) in open surgery. We describe a modified Blumgart method using LAPRA-TY suture clips to facilitate laparoscopic pancreaticojejunostomy.We prepared a double-armed 4-0 nonabsorbable monofilament, which was ligated using the LAPRA-TY clip at the tail end, 12-cm in length. Next, the U-suture was placed through the pancreatic stump and the seromuscular layer of the jejunum. We performed duct-to-mucosa suturing with a 5-0 absorbable monofilament. After completing the duct-to-mucosa suturing, as a final step we placed the sutures through the seromuscular layer of the jejunum on the ventral side and tightly secured the thread with the LAPRA-TY clips. We performed laparoscopic Blumgart pancreaticojejunostomy during pancreaticoduodenectomy in 39 patients. We compared the surgical outcomes of 19 patients who underwent Blumgart pancreaticojejunostomy using the LAPRA-TY clips (LAPRA-TY group) with 20 patients undergoing surgery not using the LAPRA-TY clips (conventional group).The rate of clinically relevant postoperative pancreatic fistula in the LAPRA-TY group was 21.1%, which did not differ significantly from the rate of the conventional group. However, the mean time of pancreaticojejunostomy in the LAPRA-TY group was 56.2 min (range, 39-79 min), which was significantly shorter than that of the conventional group (69.7 min; range, 53-105 min, P < .001).Although the modified Blumgart pancreaticojejunostomy using LAPRA-TY suture clips did not improve the pancreatic fistula rate, it allowed for shorter operative times. Thus, this procedure lends itself to positive surgical and patient outcomes.

Growth of single-crystalline Bi2Te3 hexagonal nanoplates with and without single nanopores during temperature-controlled solvothermal synthesis.

Bismuth telluride (Bi2Te3) is a promising thermoelectric material for applications near room temperature. To increase the thermoelectric performance of this material, its dimensions and thermal transport should be decreased. Two-dimensional nanoplates with nanopores are an ideal structure because thermal transport is disrupted by nanopores. We prepared Bi2Te3 nanoplates with single nanopores by a solvothermal synthesis and investigated their structural and crystallographic properties. The nanoplates synthesized at a lower reaction temperature (190 °C) developed single nanopores (approximately 20 nm in diameter), whereas the nanoplates synthesized at a higher reaction temperature (200 °C) did not have nanopores. A crystal growth mechanism is proposed based on the experimental observations.

Why Does Postoperative Pancreatic Fistula Occur After Hand-sewn Parenchymal Closure and Staple Closure in Distal Pancreatectomy?

Hand-sewing (HS) and stapling are common parenchymal closure techniques after distal pancreatectomy. However, these methods cannot completely prevent postoperative pancreatic fistula (POPF). The mechanisms of POPF formation after closure are unknown. We performed distal pancreatectomy in mongrel dogs to identify the mechanisms of POPF formation after HS and staple closure. We measured the closed pancreatic duct burst pressures and examined the histology of the remnant pancreas. The after staple-closure burst pressures depended on stapler height; lower pressures were associated with greater stapler heights. Post-HS closure burst pressures were significantly higher than those at each stapler height (P<0.01). Post-HS closure pathologic findings showed extensive necrosis (day 3), and some regenerated pancreatic duct stumps (day 5). Necrosis was not observed around the stapled tissues. Although HS completely closes the pancreatic ducts, stump necrosis and blood flow disturbances may cause POPF. With stapler closure, pancreatic fluid leakage may occur even with appropriate stapler heights.

Irreversible Electroporation for Nonthermal Tumor Ablation in Patients with Locally Advanced Pancreatic Cancer: Initial Clinical Experience in Japan.

Objective To evaluate irreversible electroporation (IRE) for locally advanced pancreatic cancer (LAPC). Methods This study was approved by our local review board. Eight patients with histologically proven LAPC ≤5 cm were prospectively enrolled to undergo ultrasound-guided IRE. The primary endpoint was complications within 90 days. Secondary outcomes were the overall survival (OS) and time to local progression. Safety was assessed using Common Terminology Criteria for Adverse Events Version 4.0. Results All patients were treated successfully. The median procedure time was 150 min. The median largest tumor diameter was 29.5 mm (20.0-48.0 mm) in the pancreatic head (n=5) and body (n=3). Open (n=4) and percutaneous (n=4) approaches were used. No patients died within 90 days after IRE. There were 5 minor complications in 3 patients and 4 major complications in 3 patients. The incidence rates of major complications did not differ significantly between the approaches. The median time to local progression after IRE was 12.0 months, and the median OS was 17.5 months from IRE and 24.0 months from the diagnosis, with no significant differences between the approaches. Conclusions Percutaneous and open IRE may be acceptable for patients with LAPC (despite some major adverse events) and may represent a useful new therapeutic option.