Surface Integral Method for the Second Harmonic Generation in Metal Nanoparticles

Second harmonic (SH) radiation in metal nanoparticles is generated by both nonlocal-bulk and local-surface SH sources, induced by the electromagnetic field at the fundamental frequency. We propose a surface integral equation (SIE) method for evaluating the SH radiation generated by metal nanoparticles with arbitrary shapes, considering all SH sources. We demonstrate that the contribution of the nonlocal-bulk SH sources to the SH electromagnetic field can be taken into account through equivalent surface electric and magnetic currents. We numerically solve the SIE problem by using the Galerkin method and the Rao-Wilton-Glisson basis functions in the framework of the distribution theory. The accuracy of the proposed method is verified by comparison with the SH-Mie analytical solution. As an example of a complex-shaped particle, we investigate the SH scattering by a triangular nano-prism. This method paves the way for a better understanding of the SH generation process in arbitrarily shaped nanoparticles and can also have a high impact in the design of novel nanoplasmonic devices with enhanced SH emission

Full-wave analytical solution of second-harmonic generation in metal nanospheres

We present a full-wave analytical solution for the problem of second-harmonic generation from spherical nanoparticles. The sources of the second-harmonic radiation are represented through an effective nonlinear polarization. The solution is derived in the framework of the Mie theory by expanding the pump field, the nonlinear sources and the second-harmonic fields in series of spherical vector wave functions. We use the proposed solution for studying the second-harmonic radiation generated from gold nanospheres as function of the pump wavelength and the particle size, in the framework of the Rudnick-Stern model. We demonstrate the importance of high-order multipolar contributions to the second-harmonic radiated power. Moreover, we investigate the p- and s- components of the SH radiation as the Rudnick-Stern parameters change, finding a strong variation. This approach provides a rigorous methodology to understand second-order optical processes in metal nanoparticles, and to design novel nanoplasmonic devices in the nonlinear regime.Comment: 16 pages, 10 figure

ERAS with or without supplemental artificial nutrition in open pancreatoduodenectomy for cancer. A multicenter, randomized, open labeled trial (RASTA study protocol)

PurposeThe role of supplemental artificial nutrition in patients perioperatively treated according to enhanced recovery programs (ERAS) on surgery-related morbidity is not known. Therefore, there is a need of a clinical trials specifically designed to explore whether given a full nutritional requirement by parenteral feeding after surgery coupled with oral food “at will” compared to oral food “at will” alone, within an established ERAS program, could achieve a reduction of the morbidity burden.Materials and analysisRASTA will be a multicenter, randomized, parallel-arm, open labeled, superiority trial. The trial will be conducted in five Italian Institutions with proven experience in pancreatic surgery and already applying an established ERAS program. Adult patients (age ≥ 18 and < 90 years of age) candidate to elective open pancreatoduodenectomy (PD) for any periampullary or pancreatic cancer will be randomized to receive a full ERAS protocol that establishes oral food “at will” plus parenteral nutrition (PN) from postoperative day 1 to day 5 (treatment arm), or to ERAS protocol without PN (control arm). The primary endpoint of the trial is the complication burden within 90 days after the day of surgery. The complication burden will be assessed by the Comprehensive Complication Index, that incorporates all complications and their severity as defined by the Clavien-Dindo classification, and summarizes postoperative morbidity with a numerical scale ranging from 0 to 100. The H0 hypothesis tested is that he administration of a parenteral nutrition added to the ERAS protocol will not affect the CCI as compared to standard of care (ERAS). The H1 hypothesis is that the administration of a parenteral nutrition added to the ERAS protocol will positively affect the CCI as compared to standard of care (ERAS). The trial has been registered at ClinicalTrials.gov (number: NCT04438447; date: 18/05/2020).ConclusionThis upcoming trial will permit to establish if early postoperative artificial nutritional support after PD may improve postoperative outcomes compared to oral nutrition alone within an established ERAS program

Minimally invasive spleen-preserving distal pancreatectomy: real-world data from the italian national registry of minimally invasive pancreatic surgery

Aim: Minimally invasive distal pancreatectomy has become the standard of care for benign and low malignant lesions. Spleen preservation in this setting has been proposed to reduce surgical trauma and long-term sequelae. The aim of the current study is to present real-world data on indications, techniques, and outcomes of spleen-preserving distal pancreatectomy (SPDP). Methods: Patients who underwent SPDP and distal pancreatectomy with splenectomy (DPWS) were extracted from the 2019-2022 Italian National Registry for Minimally Invasive Pancreatic Surgery (IGoMIPS). Perioperative and pathological data were collected. Results: One hundred and ten patients underwent SPDP and five hundred and seventy-eight underwent DPWS. Patients undergoing SPDP were significantly younger (56 vs. 63.5 years; P < 0.001). Seventy-six percent of SPDP cases were performed in six out of thirty-four IGoMIPS centers. SPDP was performed predominantly for Neuroendocrine Tumors (43.6% vs.23.5%; P < 0.001) and for smaller lesions (T1 57.6% vs. 29.8%; P < 0.001). The conversion rate was higher in the case of DPWS (7.6% vs. 0.9%; P = 0.006), even when pancreatic cancer was ruled out (5.0% vs. 0.9%; P = 0.045). The robotic approach was most commonly used for SPDP (50.9% vs. 29.7%; P < 0.001). No difference in postoperative outcomes and length of stay was observed between the two groups, as well as between robotic and laparoscopic approaches in the SPDP group. A trend toward a lower rate of postoperative sepsis was observed after SPDP (0.9% vs. 5.2%; P = 0.056). In 84.7% of SPDP, splenic vessels were preserved (Kimura procedure) without an impact on short-term postoperative outcomes. Conclusion: In this registry analysis, SPDP was feasible and safe. The Kimura procedure was prevalent over the Warshaw procedure. The typical patient undergoing SPDP was young with a neuroendocrine tumor at an early stage. Robotic assistance was used more frequently for SPDP than for DPWS

Body composition parameters, immunonutritional indexes, and surgical outcome of pancreatic cancer patients resected after neoadjuvant therapy: A retrospective, multicenter analysis

Background and aims: Body composition parameters and immunonutritional indexes provide useful information on the nutritional and inflammatory status of patients. We sought to investigate whether they predict the postoperative outcome in patients with pancreatic cancer (PC) who received neoadjuvant therapy (NAT) and then pancreaticoduodenectomy. Methods: Data from locally advanced PC patients who underwent NAT followed by pancreaticoduodenectomy between January 2012 and December 2019 in four high-volume institutions were collected retrospectively. Only patients with two available CT scans (before and after NAT) and immunonutritional indexes (before surgery) available were included. Body composition was assessed and immunonutritional indexes collected were: VAT, SAT, SMI, SMA, PLR, NLR, LMR, and PNI. The postoperative outcomes evaluated were overall morbidity (any complication occurring), major complications (Clavien-Dindo ≥ 3), and length of stay. Results: One hundred twenty-one patients met the inclusion criteria and constituted the study population. The median age at the diagnosis was 64 years (IQR16), and the median BMI was 24 kg/m2 (IQR 4.1). The median time between the two CT-scan examined was 188 days (IQR 48). Skeletal muscle index (SMI) decreased after NAT, with a median delta of −7.8 cm2/m2 (p < 0.05). Major complications occurred more frequently in patients with a lower pre-NAT SMI (p = 0.035) and in those who gained in subcutaneous adipose tissue (SAT) compartment during NAT (p = 0.043). Patients with a gain in SMI experienced fewer major postoperative complications (p = 0.002). The presence of Low muscle mass after NAT was associated with a longer hospital stay [Beta 5.1, 95%CI (1.5, 8.7), p = 0.006]. An increase in SMI from 35 to 40 cm2/m2 was a protective factor with respect to overall postoperative complications [OR 0.43, 95% (CI 0.21, 0.86), p < 0.001]. None of the immunonutritional indexes investigated predicted the postoperative outcome. Conclusion: Body composition changes during NAT are associated with surgical outcome in PC patients who receive pancreaticoduodenectomy after NAT. An increase in SMI during NAT should be favored to ameliorate the postoperative outcome. Immunonutritional indexes did not show to be capable of predicting the surgical outcome

Learning Curves of Minimally Invasive Distal Pancreatectomy in Experienced Pancreatic Centers

IMPORTANCE Understanding the learning curve of a new complex surgical technique helps to reduce potential patient harm. Current series on the learning curve of minimally invasive distal pancreatectomy (MIDP) are mostly small, single-center series, thus providing limited data.OBJECTIVE To evaluate the length of pooled learning curves of MIDP in experienced centers.DESIGN, SETTING, AND PARTICIPANTS This international, multicenter, retrospective cohort study included MIDP procedures performed from January 1, 2006, through June 30, 2019, in 26 European centers from 8 countries that each performed more than 15 distal pancreatectomies annually, with an overall experience exceeding 50 MIDP procedures. Consecutive patients who underwent elective laparoscopic or robotic distal pancreatectomy for all indications were included. Data were analyzed between September 1, 2021, and May 1, 2022.EXPOSURES The learning curve for MIDP was estimated by pooling data from all centers.MAIN OUTCOMES AND MEASURES The learning curvewas assessed for the primary textbook outcome (TBO), which is a composite measure that reflects optimal outcome, and for surgical mastery. Generalized additive models and a 2-piece linear model with a break point were used to estimate the learning curve length of MIDP. Case mix-expected probabilities were plotted and compared with observed outcomes to assess the association of changing case mix with outcomes. The learning curve also was assessed for the secondary outcomes of operation time, intraoperative blood loss, conversion to open rate, and postoperative pancreatic fistula grade B/C.RESULTS From a total of 2610 MIDP procedures, the learning curve analysis was conducted on 2041 procedures (mean [SD] patient age, 58 [15.3] years; among 2040 with reported sex, 1249 were female [61.2%] and 791 male [38.8%]). The 2-piece model showed an increase and eventually a break point for TBO at 85 procedures (95% CI, 13-157 procedures), with a plateau TBO rate at 70%. The learning-associated loss of TBO rate was estimated at 3.3%. For conversion, a break point was estimated at 40 procedures (95% CI, 11-68 procedures); for operation time, at 56 procedures (95% CI, 35-77 procedures); and for intraoperative blood loss, at 71 procedures (95% CI, 28-114 procedures). For postoperative pancreatic fistula, no break point could be estimated.CONCLUSION AND RELEVANCE In experienced international centers, the learning curve length of MIDP for TBO was considerable with 85 procedures. These findings suggest that although learning curves for conversion, operation time, and intraoperative blood loss are completed earlier, extensive experience may be needed to master the learning curve of MIDP

Minimally invasive versus open distal pancreatectomy for resectable pancreatic cancer (DIPLOMA):an international randomised non-inferiority trial

Background: The oncological safety of minimally invasive surgery has been questioned for several abdominal cancers. Concerns also exist regarding the use of minimally invasive distal pancreatectomy (MIDP) in patients with resectable pancreatic cancer as randomised trials are lacking. Methods: In this international randomised non-inferiority trial, we recruited adults with resectable pancreatic cancer from 35 centres in 12 countries. Patients were randomly assigned to either MIDP (laparoscopic or robotic) or open distal pancreatectomy (ODP). Both patients and pathologists were blinded to the assigned approach. Primary endpoint was radical resection (R0, ≥1 mm free margin) in patients who had ultimately undergone resection. Analyses for the primary endpoint were by modified intention-to-treat, excluding patients with missing data on primary endpoint. The pre-defined non-inferiority margin of −7% was compared with the lower limit of the two-sided 90% confidence interval (CI) of absolute difference in the primary endpoint. This trial is registered with the ISRCTN registry (ISRCTN44897265). Findings: Between May 8, 2018 and May 7, 2021, 258 patients were randomly assigned to MIDP (131 patients) or ODP (127 patients). Modified intention-to-treat analysis included 114 patients in the MIDP group and 110 patients in the ODP group. An R0 resection occurred in 83 (73%) patients in the MIDP group and in 76 (69%) patients in the ODP group (difference 3.7%, 90% CI −6.2 to 13.6%; pnon-inferiority = 0.039). Median lymph node yield was comparable (22.0 [16.0–30.0] vs 23.0 [14.0–32.0] nodes, p = 0.86), as was the rate of intraperitoneal recurrence (41% vs 38%, p = 0.45). Median follow-up was 23.5 (interquartile range 17.0–30.0) months. Other postoperative outcomes were comparable, including median time to functional recovery (5 [95% CI 4.5–5.5] vs 5 [95% CI 4.7–5.3] days; p = 0.22) and overall survival (HR 0.99, 95% CI 0.67–1.46, p = 0.94). Serious adverse events were reported in 23 (18%) of 131 patients in the MIDP group vs 28 (22%) of 127 patients in the ODP group. Interpretation: This trial provides evidence on the non-inferiority of MIDP compared to ODP regarding radical resection rates in patients with resectable pancreatic cancer. The present findings support the applicability of minimally invasive surgery in patients with resectable left-sided pancreatic cancer. Funding: Medtronic Covidien AG, Johnson &amp; Johnson Medical Limited, Dutch Gastroenterology Society.</p

Minimally invasive versus open distal pancreatectomy for resectable pancreatic cancer (DIPLOMA):an international randomised non-inferiority trial

Background: The oncological safety of minimally invasive surgery has been questioned for several abdominal cancers. Concerns also exist regarding the use of minimally invasive distal pancreatectomy (MIDP) in patients with resectable pancreatic cancer as randomised trials are lacking. Methods: In this international randomised non-inferiority trial, we recruited adults with resectable pancreatic cancer from 35 centres in 12 countries. Patients were randomly assigned to either MIDP (laparoscopic or robotic) or open distal pancreatectomy (ODP). Both patients and pathologists were blinded to the assigned approach. Primary endpoint was radical resection (R0, ≥1 mm free margin) in patients who had ultimately undergone resection. Analyses for the primary endpoint were by modified intention-to-treat, excluding patients with missing data on primary endpoint. The pre-defined non-inferiority margin of −7% was compared with the lower limit of the two-sided 90% confidence interval (CI) of absolute difference in the primary endpoint. This trial is registered with the ISRCTN registry (ISRCTN44897265). Findings: Between May 8, 2018 and May 7, 2021, 258 patients were randomly assigned to MIDP (131 patients) or ODP (127 patients). Modified intention-to-treat analysis included 114 patients in the MIDP group and 110 patients in the ODP group. An R0 resection occurred in 83 (73%) patients in the MIDP group and in 76 (69%) patients in the ODP group (difference 3.7%, 90% CI −6.2 to 13.6%; pnon-inferiority = 0.039). Median lymph node yield was comparable (22.0 [16.0–30.0] vs 23.0 [14.0–32.0] nodes, p = 0.86), as was the rate of intraperitoneal recurrence (41% vs 38%, p = 0.45). Median follow-up was 23.5 (interquartile range 17.0–30.0) months. Other postoperative outcomes were comparable, including median time to functional recovery (5 [95% CI 4.5–5.5] vs 5 [95% CI 4.7–5.3] days; p = 0.22) and overall survival (HR 0.99, 95% CI 0.67–1.46, p = 0.94). Serious adverse events were reported in 23 (18%) of 131 patients in the MIDP group vs 28 (22%) of 127 patients in the ODP group. Interpretation: This trial provides evidence on the non-inferiority of MIDP compared to ODP regarding radical resection rates in patients with resectable pancreatic cancer. The present findings support the applicability of minimally invasive surgery in patients with resectable left-sided pancreatic cancer. Funding: Medtronic Covidien AG, Johnson &amp; Johnson Medical Limited, Dutch Gastroenterology Society.</p