The peritoneal surface is the most frequent site of metastasis disease in patients with gastric cancer. Even after curative surgery and adjuvant chemotherapy, peritoneal recurrences often develop. Exosomes play pivotal roles in tumor metastasis via the transfer of microRNAs (miRNAs). In the present study, exosomes were isolated from peritoneal lavage fluid or ascites in 85 patients with gastric cancer and the relative expression levels of miR-29s were examined. The expression of miR-29a-3p, miR-29b-3p and miR-29c-3p in peritoneal exosomes were all downregulated in patients with peritoneal metastases (PM) compared to those without PM. In 30 patients who underwent curative gastrectomy with serosa-involved (T4) gastric cancer, 6 patients exhibited recurrence in the peritoneum within 12 months. The expression levels of miR-29s at gastrectomy tended to be lower in these 6 patients than in the other 24 patients with significant differences in miR-29b-3p (P=0.003). When the patients were divided into two groups based on median levels of miR-29s, peritoneal recurrence developed more frequently in patients with low expression of miR-29b-3p, and lower expression of miR-29s were related with worse overall survival. miR-29s are thought to play a suppressive role in the growth of disseminated peritoneal tumor cells. Reduced expression of miR-29b in peritoneal exosomes is a strong risk factor of developing postoperative peritoneal recurrence.

Background: Low-density neutrophils (LDN) have been shown to be increased in peripheral blood in patients with various diseases and closely related to immune-mediated pathology. However, the frequency and function of LDN in circulating blood of the patients following abdominal surgery have not been well understood. Methods: LDN were determined by CD66b(þ) cells, which were copurified with mononuclear cells by density gradient preparations of peripheral blood of surgical patients. The effects of the purified LDN on T cell proliferation and tumor cell lysis were examined in vitro. Neutrophil extracellular traps (NETs) production was examined by extracellular nuclear staining. Results: The number of LDN with an immature phenotype is markedly increased in peripheral blood samples in patients after abdominal surgery. The frequency of LDN correlated positively with operative time and intraoperative blood loss. The purified LDN significantly suppressed the proliferation of autologous T cells stimulated with anti-CD3 mAb coated on plate and partially inhibited the cytotoxicity of lymphocytes activated with recombinant interleukin-2 against a human gastric cancer cell, OCUM-1. The LDN also produced NETs after short-term culture in vitro, which efficiently trap many OCUM-1. These results suggest that surgical stress recruits immunosuppressive LDN in the circulation in the early postoperative period. Conclusions: The LDN may support the lodging of circulating tumor cells via NETs formation and inhibit T cellemediated antitumor response in target organs, which may promote postoperative cancer metastases. Functional blockade of LDN might be an effective strategy to reduce tumor recurrence after abdominal surgery.

Aim: Peritoneal metastases (PM) frequently occur in patients with gastric cancer and result in a poor prognosis. Exosomes play pivotal roles in tumor metastasis through the transfer of microRNAs (miRNAs). We examined the exosomal miRNA profile in peritoneal fluids to identify novel biomarkers to reflect tumor burden in the peritoneum. Methods: Exosomes were isolated from peritoneal fluids of patients of gastric cancer with macroscopic (P1) or microscopic (P0CY1) peritoneal metastasis (PM) and comprehensive miRNA expression analysis was carried out. Expressions of candidate miRNAs were then validated in all 58 samples using TaqMan Advanced miRNA Assays. Results: In initial screening, we carried out comprehensive analysis of exosomal miRNA using peritoneal fluids from 11 and 14 patients with or without PM, respectively, and identified 11 dysregulated miRNAs in PM (+) samples. Validation analysis showed that four miRNAs (miR-21-5p, miR-92a-3p, miR-223-3p, and miR-342-3p) were significantly upregulated in 12 PM (+) samples, and their expression levels showed positive correlation with peritoneal cancer index. In contrast, miR-29 family were all downregulated in patients with PM (+) samples. Moreover, in 24 patients with pT4 tumor, miR-29 at gastrectomy tended to be lower in six patients with peritoneal recurrence with significant differences in miR-29b-3p (P = .012). Conclusion: Expression pattern of miRNAs in peritoneal exosomes well reflects the tumor burden in the peritoneal cavity and could be a useful biomarker in the treatment of PM. K E Y W O R D S biomarker, exosome, intraperitoneal chemotherapy, microRNA, peritoneal metastasis | 85 OHZAWA et Al.

Background To explore best practices for acute cholecystitis, it is necessary to construct a system to assess the difficulty of laparoscopic cholecystectomy (LC) based on intraoperative findings. In this study, multiple evaluators assessed videos of LC to assemble a library of typical video clips for 25 intraoperative findings. Methods We have previously identified 25 items that contribute to surgical difficulty in LC. For each item, roughly 30‐second video clips were submitted from videos of LC performed at member institutions. We then selected one typical video from the collected clips based on simple tabulation of the instances of agreement. Inter‐rater agreement was assessed with Fleiss's κ and Gwet's agreement coefficient (AC). Results Except in the case of two assessment items (“edematous change” and “easy bleeding”), κ or AC significantly exceeded 0.5 and the typical videos were judged to be applicable. For the two remaining items, the evaluation was repeated after clarifying the definitions of positive and negative findings. Eventually, they were recognized as typical. The completed video clip library contains 31 clips and is divided into five categories (http://www.jshbps.jp/modules/project/index.php?content_id=13). Conclusions This clip library may be highly useful in clinical settings as a more objective standard for assessing surgical difficulty in LC.

These findings suggest that the cold stimulation response of finger skin vasoconstriction may be used to evaluate the relative alpha 1-adrenoceptor blocking potency of drugs.

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<b><i>Background/Aims:</i></b> Recent studies have demonstrated that the populations of several microbes are significantly increased in fecal samples from patients with colorectal cancer (CRC), suggesting their involvement in the development of CRC. The aim of this study was to identify microbes which are increased in distal CRCs and to identify the specific location of microbes increased in mucosal tissue around the tumor. <b><i>Methods:</i></b> Tissue specimens were collected from surgical resections of 28 distal CRCs. Five samples were collected from each specimen (location A: tumor, B: adjacent normal mucosa, C: normal mucosa 1 cm proximal to the tumor, D: normal mucosa 3 cm proximally, and E: normal mucosa 6 cm proximally). The microbiota in the sample were analyzed using 16S rRNA gene amplicon sequencing and the relative abundance (RA) of microbiota compared among the 5 locations. <b><i>Results:</i></b> At the genus level, the RA of <i>Fusobacterium</i> and <i>Streptococcus</i> at location A was the highest among the 5 locations, significantly different from that in location E. The dominant species of each genus was <i>Fusobacterium nucleatum</i> and <i>Streptococcus anginosus.</i> The RAs of these species gradually decreased from locations B to E with a statistically significant difference in <i>F. nucleatum</i>. The genus <i>Peptostreptococcus</i> also showed a similar trend, and the RA of <i>Peptostreptococcus stomatis</i> in location A was significantly associated with depth of tumor invasion and tumor size. <b><i>Conclusion:</i></b> Although the clinical relevance is not clear yet, these results suggest that <i>F. nucleatum, S. anginosus</i>, and <i>P. stomatis</i> can spread to the adjacent normal tissues and may change the surrounding microenvironment to support the progression of CRC.