Margin Sites Research Articles

311. PROGNOSTIC VALUE OF DIFFERENT CIRCUMFERENTIAL MARGIN SITES IN OESOPHAGEAL CANCER: A 10-YEAR COHORT STUDY

Abstract Background There’s a growing interest towards the prognostic value of circumferential resection margin (CRM) involvement in oesophageal cancers. However, there is no sufficient data about the association of the site-specific CRM and survival. In this study, we analysed the influence of different involved CRM sites on survival. Methods This study included patients who had curative oesophagectomy for oesophageal cancer between 2010 till June 2021. Follow up till April 2022 was achieved. Patients with involved proximal or distal margins were excluded. The sites of CRM were defined anatomically to anterior (pericardial), posterior (aorta), lateral (pleurae). The outcomes between different CRM margins were retrospectively analysed. The long-term follow up data was obtained via direct contact with the patients during our oncological clinics, cross-checked with our hospital/national patients’ electronic databases. Results 117 patients had CRM-positive after curative oesophagectomy during the study period. 33 cases had multi-involved CRM sites, while 84 patients had single involved CRM site. Posterior margins were the most common involved site 37/117 (31.6%). No differences in baseline pathological criteria (pT, pN stages and type of cancer) and neoadjuvant therapy. Positive anterior margins carried the worst overall (OS) and disease-free (DFS) survival compared to lateral and posterior margins (OS: 29 vs 41 vs 32 months respectively, p-value 0.37, DFS: 19.2 vs 32.1 vs 28.7 months respectively, p-value 0.39). Multi-involved CRM sites led to worse OS and DFS in comparison with single involved CRM site (OS: 19 vs 32 months respectively, p-value 0.008, DFS: 12.1 months vs 27.6 months respectively, p-value 0.05). Conclusion The site of involved CRM should be rigorously assessed in oesophagectomy specimens. The involved margin sites within CRM had different survival rates, with inferiority towards anterior resection margins. Larger studies are required to better evaluate the prognostic significance of various CRM sites.

Impact of radiation therapy for breast cancer with involved surgical margin after immediate breast reconstruction: A multi-institutional observational study

IntroductionInvolved surgical margins are risk factors for local recurrence and re-excision is often difficult, particularly in patients with breast cancer undergoing immediate breast reconstruction (IBR). However, the magnitude of the effect of radiation therapy on preventing local recurrence for breast cancers with involved margins has not been sufficiently assessed. Materials and methodsWe retrospectively assessed sites of involved surgical margins and local recurrence after mastectomy with IBR in patients with early breast cancer between 2008 and 2016. The effect of postoperative radiation therapy was evaluated in patients with involved margins, adjusted for nuclear grade, lymphatic invasion, surgical procedures, and primary systemic therapy. ResultsA total of 274 (5.8 %) out of 4726 patients who underwent mastectomy with IBR had involved surgical margins: 133, 68, 88, and 26 had involvement of the skin, deep margin, lateral margins, and nipple, respectively (including duplicates). Radiation therapy was administered to 54 patients with involved margins. In patients with involved margins, 7-year cumulative incidences of local recurrence were 1.9 % and 12.6 % with and without radiation therapy, respectively (adjusted hazard ratio, 0.17; 95 % CI, 0.04–0.80). Local recurrence occurred in 28 patients, and the sites were skin, subcutaneous tissue, muscle, and nipple-areola complex in 7, 17, 1, and 3 patients, respectively. Among them, 23 (82.1 %) were associated with involved margin sites. ConclusionsRadiation therapy meaningfully reduced the incidence of local recurrence in patients with breast cancer with margin involvement after mastectomy with IBR. Most local recurrences occurred at involved margin-related sites.

Predicting chronological age based on age-related osteophyte development in the superior and inferior vertebral centrum margins of T12-L5.

The purpose of this study was to determine the relationship between vertebral margins at individual vertebral levels between T12-L5 vertebra and chronological age and develop predictive models. Three hundred and nineteen CT scans from a medical imaging database in North America were randomly selected. Three superior and inferior vertebral margin sites were scored based on observable age-related changes. All individual vertebral margin site scores significantly correlated with age at death with Pearson r values ranging from 0.47 to 0.77. Totaling the individual vertebral margin site scores for L1-L5 improved Pearson r to 0.92. All resulting predictive models were significant, and the best models predicted age at death within 10 years 70%-76% of the time for males, females, and combined male and females. In conclusion, this study produced accurate and reliable models to predict age at death using age-related changes in the spine for a North American population.

British–Irish Ice Sheet and polar front history of the Goban Spur, offshore southwest Ireland over the last 250 000 years

Deep Sea Drilling Program (DSDP) Site 548 was cored in 1984 at a water depth of 1256 m on the Goban Spur, offshore southwest Ireland. Coring retrieved a ~100‐m‐thick Pleistocene contourite sequence. This study uses planktonic foraminiferal assemblage and benthic foraminiferal oxygen isotope analyses to establish an age model for the upper 40 m of this core. This site's multidisciplinary analyses of planktonic foraminiferal assemblages, lithic grains, facies and calcium carbonate concentration reveal a 250 000‐year record of the North Atlantic polar front variability and British–Irish Ice Sheet (BIIS) history. The sequence is characterized by alternations of ice rafted debris (IRD) laden pelagic mud facies with calcium carbonate‐rich silty sand contourite facies that track glacial/interglacial cycles. The polar front migrated southward across the area several times during glacial maxima and stadial periods, while warmer Mediterranean Outflow Water (MOW) flowed northward across the region during interglacial and interstadial periods depositing contourites. Lithic analyses reveal a complex history of IRD deposition associated with iceberg calving from the Laurentide Ice Sheet and northwest European ice sheets, mainly the BIIS. Comparison between the Goban Spur (DSDP Site 548) and the Celtic Margin (MD03‐2692) and central North Atlantic Integrated Ocean Drilling Program (IODP) Site U1308 suggests differences between the ‘non‐Laurentide Ice Sheet’ Heinrich Events (HE) 6 and 3 at the Goban Spur, with IRD from the BIIS being prominent during HE 6 and IRD from other European ice sheets north of the BIIS likely being more dominant during HE 3. The nature of lithics in IRD‐rich horizons during Terminations 3, 3A, 2 and 1 suggests significant iceberg calving episodes preceding BIIS retreat during the onset of interstadial intervals.

Virtual 3D Specimen Mapping in Head & Neck Oncologic Surgery.

Virtual 3D specimen mapping of oncologic surgical specimens provides a visual record of the specimen and margin sampling sites which can be utilized in a variety of cancer care settings. Our objective was to perform a retrospective review of head and neck surgical oncology cases where the specimen was mapped post-operatively and to evaluate the utility of these 3D specimen maps amongst the multidisciplinary cancer care team. A retrospective review of our 3D specimen model biorepository was performed. Surgical specimens were 3D scanned and then graphically annotated (or "mapped") during routine pathologic processing. The resulting 3D specimen maps were distributed to the multidisciplinary oncologic care team. Final margin status and any use of the 3D specimen maps were recorded. A total of 28 cases were included. Virtual 3D specimen maps were utilized by the cancer care team in 8 cases (29%), including 2 positive margin cases, 2 close margin cases, and 4 indeterminate margin cases. 3D specimen maps were used to visualize positive margin sites for pathologist-surgeon communication as a visual reference during tumor board discussions and to inform radiation treatment planning. Post-operative virtual 3D specimen mapping of oncologic specimens creates a permanent visual record of the specimen and the margins sampled and may serve as a beneficial tool for communication amongst the multidisciplinary cancer care team. 4 Laryngoscope, 134:191-197, 2024.

Methane Index: Towards a quantitative archaeal lipid biomarker proxy for reconstructing marine sedimentary methane fluxes

In marine sediments, anaerobic methane oxidation (AOM) carried out by consortia of methanotrophic archaea (ANME groups) and sulfate reducing bacteria (SRB) represents a major sink for methane (40–290 Tg of C yr−1). The variability of seafloor methane seepage and AOM is crucial to sedimentary biogeochemistry and global carbon/sulfur cycling, yet poorly constrained for Earth’s history. Based on the rationale that a major group of ANME preferentially synthesizes certain tetraether lipids, Methane Index (MI) measured from sedimentary archaeal lipid biomarkers called GDGTs (glycerol dialkyl glycerol tetraethers) has been widely used as a qualitative indicator for methane-impact on sediments. However, it was unclear whether small amounts of diagenetic methane in porewater could cause high MI values or that high methane flux associated with, for example cold seeps, is required. Since not all ANME groups synthesize GDGTs, another contested issue is whether this index is broadly representative of AOM. Here, we use modern porewater and sedimentary lipid profiles from the world’s ocean to further explore MI’s potential to address these questions. The new data show that MI is quantitatively linked to sedimentary methane diffusive flux and the depth of sulfate-methane transition zone (SMTZ) which is the diagenetic front where AOM activity is mostly concentrated. In particular, high MI values (>0.3–0.5) are strongly associated with high methane fluxes (>∼0.1 mmol m−2 d−1) and shallow SMTZ depths (<1–3 m) commonly linked to gas hydrate dissociations. Sensitivity analyses suggest that when the variability of several key parameters (e.g., seawater sulfate concentration, geothermal gradient, and sediment porosity) is small, modern MI – methane flux and MI – SMTZ depth relationships can be applied to reconstruct methane history and diagenetic zonation of the geological past. Although only Group I of ANME archaea synthesizes GDGTs, the co-occurrence of AOM biomarkers (e.g., crocetane, PMI, and hydroxyarchaeol) that are attributed to ANME-2 or ANME-3 and high MI values suggest that MI is broadly representative of AOM. Lastly, we applied MI to probe the methane venting history by using new data from a Cascadia Margin site (Hydrate Ridge, IODP U1328) since the penultimate interglacial, and reinterpreted recently reported MI data from three Southern Ocean sites (ODP 1168, 1170, and IODP U1356) during the late Oligocene – early Miocene. Overall, these applications demonstrate that MI can serve as a sensitive and quantitative proxy to help broadly establish Cenozoic and Mesozoic history of marine methane biogeochemical cycling.

Effect of a novel coating material on the microleakage of glass hybrid restoration in primary teeth – An in vitro study

Background: Glass ionomer restorations are widely employed in the field of pediatric dentistry. There is a constant demand for a durable restoration that remains functional until exfoliation. This study aimed to measure and compare the effect of a novel coating material (EQUIA Forte Coat) on the microleakage of glass hybrid restoration (EQUIA Forte HT) in primary teeth. Material and method: Thirty cavitated (class-II) primary molars were allocated randomly into two groups based on the coat application; uncoated (control) and coated group (experimental). Cavities were prepared by the use of a ceramic bur (CeraBur) and restored with EQUIA Forte HT with or without applying a protective coat (EQUIA Forte Coat). Samples went through the thermocycling process and dipped in 2% methylene blue dye before being sectioned through the center of the restoration. Microleakage was evaluated digitally using software and a camera connected to a stereomicroscope (30 x magnification) to assess dye penetration of the sectioned samples at both the occlusal and gingival marginal levels. Results: There was a significant difference between the coated and uncoated groups at both occlusal (p=.029) and gingival margin sites (p=.001). Conclusion: Higher microleakage values were associated with the uncoated group compared to the coated one. The application of a protective coating to the restorations is an efficient approach to decrease the microleakage of the restorations that can be usefully adopted in clinical practice.

Geochemical conditions regulating chromium preservation in marine sediments

In the marine sediment record, concentrations and isotope ratios of chromium (Cr) can be used to reconstruct ocean biogeochemical conditions. These reconstructions rely on a detailed understanding of the chemical pathways that Cr undergoes as it is transferred from the water column to the sediment record. We examined Cr concentrations in marine pore fluids and sediments from six continental margin sites, which can be grouped into two basic environments: (1) sites where sediments are oxygenated and rich in solid phase Mn (herein termed oxic), and (2) sites where sediments are organic C (Corg)-rich and oxygen is depleted (anoxic). We found Cr concentrations to be lower (maximum of 12 nM in pore fluids and 124 ppm sediment solid phase) at oxic sites compared with anoxic sites (maximum of 77 nM and 184 ppm). Our findings confirm previously published interpretations of dissolved Cr in pore fluids (Brumsack and Gieskes, 1983; Shaw et al., 1990). In oxic surface sediments, particulate Cr(III) can be oxidised by Mn oxides, which leads to elevated concentrations of dissolved Cr co-occurring at the same depth as elevated Mn concentrations in the sediment. Under these oxidising conditions, down-core sediments contain relatively low solid-phase Cr concentrations. In oxic sediments, Cr speciation reveals that most of the pore fluid Cr is in the Cr(VI) state. At the site where Mn oxide-rich sediments rest below an oxic water column, oxidative loss of Cr from the sediment to the bottom water leads to the lowest estimated Cr burial efficiency of the sites examined here. Under anoxic Corg-rich conditions, both pore fluids and sediment solid phases contain high Cr concentrations, with 40–80% of dissolved pore fluid Cr present as Cr(III). This enrichment of Cr appears to be tightly linked to the presence of high total organic carbon (TOC) content and scavenging of Cr by (organic) particles in the water column. Combined, these data highlight the strong dependence of Cr on both sedimentary redox conditions as well as biological productivity. Based on the data from modern continental margin sediments, we propose that Cr concentrations and isotope compositions of the authigenic sediment fraction may record a combination of redox conditions and biological productivity in the water column. If confirmed by Cr isotope analyses, these findings will add support for the notion that Cr may serve as a proxy for ocean biological and chemical sedimentological conditions. Thus, careful assessment of the impact of organic matter on Cr is required for reconstructions of redox conditions with sedimentary records.

Fluorescence imaging analysis of the glioma microenvironment

Glioma is the most malignant brain cancer. The neurons, macrophages, T cells and other immune cells constitute the glioma immunosuppressive microenvironment. The accurate spatial distribution of these cells in the glioma microenvironment and its relationship with glioma metastasis is unknown. We constructed a mouse glioma cell line stably expressing the large Stokes-shifted yellow fluorescent protein and applied it to the multicolor immunofluorescence imaging. The imaging data revealed that the neurons were sparsely distributed in the glioma core and the number of neurons decreased by 90% compared with normal brain site. The spatial distribution of monocyte-macrophages and microglia is heterogeneous. The monocyte-macrophages and T cells were heavily recruited into the glioma core and metastasis. There was no significant difference in the distribution of microglia among glioma core, margin, and normal brain site. Our results provided new perspectives for targeting immune regulation cells and developing new immunotherapy strategies for glioma.

Shallow- and deep-ocean Fe cycling and redox evolution across the Pliensbachian–Toarcian boundary and Toarcian Oceanic Anoxic Event in Panthalassa

The late Pliensbachian to early Toarcian was characterized by major climatic and environmental changes, encompassing the early Toarcian Oceanic Anoxic Event (T-OAE, or Jenkyns Event, ∼183 Ma) and the preceding Pliensbachian–Toarcian boundary event (Pl/To). Information on seawater redox conditions through this time interval has thus far come mainly from European sections deposited in hydrographically restricted basins, and hence our understanding of the redox evolution of the open ocean (and in particular Panthalassa – the largest ocean to have existed) is limited. Here, we present high-resolution Fe-speciation and redox-sensitive trace metal data from two Panthalassic Ocean sections across the Pl/To and the T-OAE intervals, one deposited in deep water (paleo-water depth >∼2.7 km) and the other on a shallow margin (paleo-water depth likely <∼50 m). Data from the deep-water open-ocean site indicate anoxic-ferruginous conditions from the late Pliensbachian to the onset of the T-OAE, with a rather fluctuating redox state alternating between oxic and anoxic/euxinic conditions across the Pl/To boundary. At least intermittent bottom-water euxinia characterized the T-OAE, followed by a subsequent transition toward more oxygenated conditions. By contrast, trace metal data from the shallow margin site indicate that oxygenated to possibly suboxic conditions prevailed. However, elevated highly reactive iron contents, dominated by Fe (oxyhydr)oxides, characterize this shallow-water site. These observations suggest that upwelling, driven in part by increased sea level and prevailing winds from the open ocean, brought anoxic-ferruginous waters onto the shelf, whereupon Fe2+ oxidation was initiated in oxic shallow waters.

OGC P19 The future insights of evaluating the circumferential resection margin (CRM) status in oesophageal cancer: A 12-year cohort study

Abstract Background The definition of CRM (circumferential resection margins) for oesophageal cancers varies among the international pathological bodies with an ongoing controversy about the optimal definition. There is also no enough data about the prognostic relevance of different sites in CRM. In this study, we examined the prognostic impacts of different CRM distances and sites. Methods This study included patients who had curative oesophagectomy for oesophageal cancer between 2010 till June 2021. Follow up till April 2022 was achieved. CRM status was carefully examined for the distance and site of involved tumour cells. Patients with involved proximal or distal margins were excluded. The outcomes between different CRM margins were retrospectively analysed. The long-term follow up data was obtained via direct contact with the patients during our oncological clinics, cross-checked with our hospital/national patients’ electronic databases. Results 456 patients were included in this study. Involved tumour cells within 1mm of CRM was observed in 192 patients (42.1%). CRM+ (&amp;lt;1mm) was associated with worse overall (OS) and disease-free survival (DFS) (22.8 and 16.3 months respectively) compared to CRM-negative (47.7 and 45.1 months respectively), (p-value &amp;lt;0.001 for both). CRM+ (0mm) had worse OS and DFS (20.5 and 12 months respectively) compared to CRM+(0.1–1mm) (26.4 and 20 months respectively), (p-values 0.028 and 0.006 respectively). CRM-positive posterior margin was the most common involved site (32%), but was associated with better OS and DFS compared to anterior and lateral sites, (p-values 0.1 and 0.08 respectively). Conclusions The site and distance of tumour cells within CRM should be rigorously assessed in oesophagectomy specimens. The presence of tumour cells within 1mm of CRM was an independent factor for OS and DFS. The CRM+(0 mm) had significant lower survival rates compared to other CRM+ distances (0.1–1 mm). The involved margin sites within CRM had different survival rates, with superiority towards posterior resection margins.

PE10 - Evaluation of involvement positive surgical margin site and biochemical recurrence after robot-assisted radical prostatectomy

PE10 - Evaluation of involvement positive surgical margin site and biochemical recurrence after robot-assisted radical prostatectomy

Clinical outcomes for men with positive surgical margins after radical prostatectomy—results from the South Australian Prostate Cancer Clinical Outcomes Collaborative community-based registry

ObjectivePositive surgical margins (PSMs) after radical prostatectomy (RP) indicate failure of surgery to completely clear cancer. PSMs confer an increased risk of biochemical recurrence (BCR), but how more robust outcomes are affected is unclear. This study investigated factors associated with PSMs following RP and determined their impact on clinical outcomes (BCR, second treatment [radiotherapy and/or androgen deprivation therapy], and prostate cancer-specific mortality [PCSM]). MethodsThe study cohort included men diagnosed with prostate cancer (pT2-3b/N0/M0) between January 1998 and June 2016 who underwent RP from the South Australian Prostate Cancer Clinical Outcomes Collaborative database. Factors associated with risk of PSMs were identified using Poisson regression. The impact of PSMs on clinical outcomes (BCR, second treatment, and PCSM) was assessed using competing risk regression. ResultsOf the 2827 eligible participants, 28% had PSMs—10% apical, 6% bladder neck, 17% posterolateral, and 5% at multiple locations. Median follow-up was 9.6 years with 81 deaths from prostate cancer recorded. Likelihood of PSM increased with higher pathological grade and pathological tumor stage, and greater tumour volume, but decreased with increasing surgeon volume (odds ratio [OR]: 0.93; 95% confidence interval [CI]: 0.88–0.98, per 100 previous prostatectomies). PSMs were associated with increased risk of BCR (adjusted sub-distribution hazard ratio [sHR] 2.5; 95% CI 2.1–3.1) and second treatment (sHR 2.9; 95% CI 2.4–3.5). Risk of BCR was increased similarly for each PSM location, but was higher for multiple margin sites. We found no association between PSMs and PCSM. ConclusionOur findings support previous research suggesting that PSMs are not independently associated with PCSM despite strong association with BCR. Reducing PSM rates remains an important objective, given the higher likelihood of secondary treatment with associated comorbidities.

Image-guided surgery with a new tumour-targeting probe improves the identification of positive margins.

SummaryBackgroundGiven the lack of visual discrepancy between malignant and surrounding normal tissue, current breast conserving surgery (BCS) is associated with a high re-excision rate. Due to the increasing cases of BCS, a novel method of complete tumour removal at the initial surgical resection is critically needed in the operating room to help optimize the surgical procedure and to confirm tumour-free edges.MethodsWe developed a unique near-infrared (NIR) fluorescence imaging probe, ICG-p28, composed of the clinically nontoxic tumour-targeting peptide p28 and the FDA-approved NIR dye indocyanine green (ICG). ICG-p28 was characterized in vitro and evaluated in multiple breast cancer animal models with appropriate control probes. Our experimental approach with multiple-validations and -blinded procedures was designed to determine whether ICG-p28 can accurately identify tumour margins in mimicked intraoperative settings.FindingsThe in vivo kinetics were analysed to optimize settings for potential clinical use. Xenograft tumours stably expressing iRFP as a tumour marker showed significant colocalization with ICG-p28, but not ICG alone. Image-guided surgery with ICG-p28 showed an over 6.6 × 103-fold reduction in residual normalized tumour DNA at the margin site relative to control approaches (i.e., surgery with ICG or palpation/visible inspection alone), resulting in an improved tumour recurrence rate (92% specificity) in multiple breast cancer animal models independent of the receptor expression status. ICG-p28 allowed accurate identification of tumour cells in the margin to increase the complete resection rate.InterpretationOur simple and cost-effective approach has translational potential and offers a new surgical procedure that enables surgeons to intraoperatively identify tumour margins in a real-time, 3D fashion and that notably improves overall outcomes by reducing re-excision rates.FundingThis work was supported by NIH/ National Institute of Biomedical Imaging and Bioengineering, R01EB023924.

Anammox bacteria drive fixed nitrogen loss in hadal trench sediments

Benthic N2 production by microbial denitrification and anammox is the largest sink for fixed nitrogen in the oceans. Most N2 production occurs on the continental shelves, where a high flux of reactive organic matter fuels the depletion of nitrate close to the sediment surface. By contrast, N2 production rates in abyssal sediments are low due to low inputs of reactive organics, and nitrogen transformations are dominated by aerobic nitrification and the release of nitrate to the bottom water. Here, we demonstrate that this trend is reversed in the deepest parts of the oceans, the hadal trenches, where focusing of reactive organic matter enhances benthic microbial activity. Thus, at ∼8-km depth in the Atacama Trench, underlying productive surface waters, nitrate is depleted within a few centimeters of the sediment surface, N2 production rates reach those reported from some continental margin sites, and fixed nitrogen loss is mainly conveyed by anammox bacteria. These bacteria are closely related to those known from shallow oxygen minimum zone waters, and comparison of activities measured in the laboratory and in situ suggest they are piezotolerant. Even the Kermadec Trench, underlying oligotrophic surface waters, exhibits substantial fixed N removal. Our results underline the role of hadal sediments as hot spots of deep-sea biological activity, revealing a fully functional benthic nitrogen cycle at high hydrostatic pressure and pointing to hadal sediments as a previously unexplored niche for anaerobic microbial ecology and diagenesis.

A Comparative Study of the Accuracy of Dental CAD Programs in Designing a Fixed Partial Denture.

Error testing at each stage of prosthetic manufacturing remains relatively underdeveloped for computer-aided design/computer-aided manufacturing methods, and no experimental studies have validated the computer-aided design programs. This study aimed to test the accuracy and trueness of the computer-aided design of a three-unit fixed prosthesis. Three computer-aided design programs (Exocad, Dental System™, and inLab 16) were tested on the designs of a three-unit fixed partial denture, and a three-dimensional analysis program was used to calculate the internal clearance error for the computer-aided design prostheses. The Kruskal-Wallis and Dunn's post hoc tests were used to reveal significant differences in trueness between the three computer-aided design programs (α < 0.05). Dental System™ showed the lowest mean error values for #24 and #26 at the mesial margin (both 0 µm), mesial wall (0.10, 0.12 µm, respectively), occlusal surface (-0.05, 0.10 µm), distal wall (0.23, -0.02 µm), and distal margin (both 0 µm). In sum, except for the mesial margin and distal margin site of tooth #26, the mean error value of Dental System™ was statistically the lowest, followed by those of Exocad and inLab 16 (p < 0.003). The accuracy of computer-aided design differed according to the type of computer-aided design program. Dental System™ achieved the best trueness at the margins, axial walls, and occlusal surface, followed by Exocad and inLab 16.

Bottom trawling noise: Are fishing vessels polluting to deeper acoustic habitats?

The impact of bottom trawling noise was quantified on two surrounding marine acoustic habitats using fixed mooring acoustic recorders. Noise during trawling activity is shown to be considerably louder than ambient noise and a nearby underway research vessel. Estimated source levels were above cetacean damage thresholds. Measurements at a submarine canyon indicated potential noise focussing, inferring a role for such features to enhance down slope noise propagation at continental margin sites. Modelled sound propagates more efficiently when sourced from trawling gear dragging along the seabed relative to the vessel as a surface source. Results are contextualised with respect to marine mammal harm, to other anthropogenic ocean noise sources, topography and seasons. Noise energy emitted by bottom trawling activity is a source of pollution that requires further consideration, in line with other pervasive trawling pressures on marine species and seabed habitats, especially in areas of heightened ecological susceptibility.

Deuterium Excess in Precipitation Reveals Water Vapor Source in the Monsoon Margin Sites in Northwest China

The deuterium excess (d) in precipitation, determined by the stable hydrogen and oxygen isotopes (δ2H and δ18O), is a widely applied parameter in tracing the water vapor source. Based on the multiple-year observations of stable water isotopes in precipitation at four stations in the Lanzhou city, Northwest China, we analyzed the variations in deuterium excess in precipitation at the Asian monsoon margin region. The mean value of deuterium excess at the study region is 11.0‰ in the dry season and 8.0‰ in the wet season. The d value in precipitation negatively correlates with air temperature and vapor pressure. The low d value during the wet season reflects the monsoon moisture transported from long distances. During the dry season, the continental air masses correspond to the higher d value in precipitation. The moisture regimes based on reanalysis data are generally consistent with the findings using a stable isotopic approach, and the monsoon moisture is highlighted in summer precipitation at these monsoon margin sites.

Macrofaunal control of microbial community structure in continental margin sediments

Through a process called "bioturbation," burrowing macrofauna have altered the seafloor habitat and modified global carbon cycling since the Cambrian. However, the impact of macrofauna on the community structure of microorganisms is poorly understood. Here, we show that microbial communities across bioturbated, but geochemically and sedimentologically divergent, continental margin sites are highly similar but differ clearly from those in nonbioturbated surface and underlying subsurface sediments. Solid- and solute-phase geochemical analyses combined with modeled bioturbation activities reveal that dissolved O2 introduction by burrow ventilation is the major driver of archaeal community structure. By contrast, solid-phase reworking, which regulates the distribution of fresh, algal organic matter, is the main control of bacterial community structure. In nonbioturbated surface sediments and in subsurface sediments, bacterial and archaeal communities are more divergent between locations and appear mainly driven by site-specific differences in organic carbon sources.

Detailed Analysis of Margin Positivity and the Site of Local Recurrence After Pancreaticoduodenectomy.

The association between a positive surgical margin and local recurrence after resection of pancreatic adenocarcinoma (PDAC) has been reported. Assessment of the location of the a positive margin and the specific site of local recurrence has not been well described. A prospectively maintained database was queried for patients who underwent R0/R1 pancreaticoduodenectomy for PDAC between 2000 and 2015. The pancreatic, posterior, gastric/duodenal, anterior peritoneal, and bile duct margins were routinely assessed. Postoperative imaging was reviewed for the site of first recurrence, and local recurrence was defined as recurrence located in the remnant pancreas, surgical bed, or retroperitoneal site outside the surgical bed. During the study period, 891 patients underwent pancreaticoduodenectomy, and 390 patients had an initial local recurrence with or without distant metastases. The 5-year cumulative incidence of local recurrence by site included the remnant pancreas (4%; 95% confidence interval [CI], 3-5%), the surgical bed (35%; 95% CI, 32-39%), and other regional retroperitoneal site (4%; 95% CI, 3-6%). In the univariate analysis, positive posterior margin (hazard ratio [HR], 1.50; 95% CI, 1.17-1.91; p = 0.001) and positive lymph nodes (HR, 1.36; 95% CI, 1.06-1.75; p = 0.017) were associated with surgical bed recurrence, and in the multivariate analysis, positiveposterior margin remained significant (HR, 1.40; 95% CI, 1.09-1.81; p = 0.009). An isolated local recurrence was found in 197 patients, and a positive posterior margin was associated with surgical bed recurrence in this subgroup (HR, 1.51; 95% CI, 1.08-2.10; p = 0.016). In this study, the primary association between site of margin positivity and site of local recurrence was between the posterior margin and surgical bed recurrence. Given this association and the limited ability to modify this margin intraoperatively, preoperative assessment should be emphasized.