Estimation of the difference between peritoneal microenvironment and core body temperature during laparoscopic surgery - a prospective observational study.

Maintaining patients' temperature during surgery is beneficial since hypothermia has been linked with perioperative complications. Laparoscopic surgery involves the insufflation of carbon dioxide (CO2) into the peritoneal cavity and has become the standard in many surgical indications since it is associated with better and faster recovery. However, the use of cold and dry CO2 insufflation can lead to perioperative hypothermia. We aimed to assess the difference between intraperitoneal and core temperatures during laparoscopic surgery and evaluate the influence of duration and CO2 insufflation volume by fitting a mixed generalized additive model. In this prospective observational single-center cohort trial, we included patients aged over 17 with American Society of Anesthesiology risk scores I to III undergoing laparoscopic surgery. Anesthesia, ventilation, and analgesia followed standard protocols, while patients received active warming using blankets and warmed fluids. Temperature data, CO2 ventilation parameters, and intraabdominal pressure were collected. We recruited 51 patients. The core temperature was maintained above 36 °C and progressively raised toward 37 °C as pneumoperitoneum time passed. In contrast, the intraperitoneal temperature decreased, thus creating a widening difference from 0.4 [25th-75th percentile: 0.2-0.8] °C at the beginning to 2.3 [2.1-2.3] °C after 240 min. Pneumoperitoneum duration and CO2 insufflation volume significantly increased this temperature difference (P < 0.001 for both parameters). Core vs. intraperitoneal temperature difference increased linearly by 0.01 T °C per minute of pneumoperitoneum time up to 120 min and then 0.05 T °C per minute. Each insufflated liter per unit of time, i.e. every 10 min, increased the temperature difference by approximately 0.009 T °C. Our findings highlight the impact of pneumoperitoneum duration and CO2 insufflation volume on the difference between core and intraperitoneal temperatures. Implementing adequate external warming during laparoscopic surgery effectively maintains core temperature despite the use of dry and unwarmed CO2 gases, but peritoneal hypothermia remains a concern, suggesting the importance of further research into regional effects.Trial registration: Clinicaltrials.gov: NCT04294758.

Protocol for long-term monocultures of murine macrophages derived from distinct adult tissues.

Tissue-resident macrophages (TRMs) constitute the first line of defense against infection in all organs and perform organ-specific functions during tissue homeostasis. Here, we present a protocol for long-term monocultures of murine macrophages from different adult organs, including the brain, liver, peritoneal cavity, and lung. We describe steps for tissue preparation and the use of a combination of organotypic conditions to maintain a TRM-like identity in vitro, resulting in an ideal screening platform for a wide range of assays and readouts. For complete details on the use and execution of this protocol, please refer to Aktories et al.1.

Virus-specific antibody secreting cells reside in the peritoneal cavity and systemic immune sites of Atlantic salmon (Salmo salar) challenged intraperitoneally with salmonid alphavirus.

The development and persistence of antibody secreting cells (ASC) after antigenic challenge remain inadequately understood in teleosts. In this study, intraperitoneal (ip) injection of Atlantic salmon (Salmo salar) with salmonid alphavirus (WtSAV3) increased the total ASC response, peaking 3-6 weeks post injection (wpi) locally in the peritoneal cavity (PerC) and in systemic lymphoid tissues, while at 13 wpi the response was only elevated in PerC. At the same time point a specific ASC response was induced by WtSAV3 in PerC and systemic tissues, with the highest frequency in PerC, suggesting a local role. Inactivated SAV (InSAV1) induced comparatively lower ASC responses in all sites, and specific serum antibodies were only induced by WtSAV3 and not by InSAV1. An InSAV1 boost did not increase these responses. Expression of immune marker genes implies a role for PerC adipose tissue in the PerC immune response. Overall, the study suggests the Atlantic salmon PerC as a secondary immune site and an ASC survival niche.

Development and organization of omental milky spots.

The milky spots in omentum are atypical lymphoid tissues that play a pivotal role in regulating immune responses in the peritoneal cavity. The milky spots act as central hubs for collecting antigens and particles from the peritoneal cavity, regulating lymphocyte trafficking, promoting the differentiation and self-renewal of immune cells, and supporting the local germinal centre response. In addition, the milky spots exhibit unique developmental characteristics that combine the features of secondary and tertiary lymphoid tissues. These structures are innately programmed to form during foetal development; however, they can also be formed postnatally in response to peritoneal irritation such as inflammation, infection, obesity, or tumour metastasis. In this review, I discuss emerging perspectives on homeostatic development and organization of the milky spots.

The Importance of Lumbar Lordosis During Laparoscopic Trocar Entry.

STUDY OBJECTIVE: Investigating the effect of lumbar lordosis on the relationship between abdominal trocar entry points and major vascular structures. DESIGN: Retrospective cohort. SETTING: Tertiary referral center. PATIENTS: Distances between the skin and the aorta and inferior vena cava at the trocar entry points, both at the umbilicus and 3 cm and 5 cm superior to the umbilicus, were measured at entry angles of 90 and 45 degrees in 101 abdominal computer tomography images. INTERVENTIONS: The relationship of these values with lumbar lordosis was investigated concerning menopausal status, body mass index (BMI), and parity differences. To assess the isolated effect of lumbar lordosis, a simulated 30-degree increase in the lordosis angle was applied to the patients' computed tomography images. The impact of this increased lumbar lordosis angle on the distances between the skin and major vessels was then evaluated at both the umbilical and supraumbilical trocar entry sites. MEASUREMENTS AND MAIN RESULTS: In the tomographic images of all patients, the distances from the skin to vascular structures were measured at a 90-degree entry angle, resulting in measurements of 8.97 cm ± 2.81 at the umbilicus, 10.89 cm ± 3.02 at 3 cm above the umbilicus, and 11.36 cm ± 2.88 at 5 cm above the umbilicus. These distances exhibited significant differences between patients with BMI <30 and BMI ≥30, as well as between premenopausal and postmenopausal patients. However, at a 45-degree entry angle, vascular structures were observed in only a few patients during trocar projection, and no measurable values were determined. In the simulation, it was found that a 1-degree increase in lumbar lordosis angle resulted in a decrease of 0.272 mm ± 0.018 in the distance between the skin and vascular structures at the umbilicus, 0.425 mm ± 0.024 at 3 cm above the umbilicus, and 0.428 mm ± 0.024 at 5 cm above the umbilicus. CONCLUSION: An increase in the degree of lumbar lordosis reduces the distance between trocar entry points and major vascular structures. Along with other factors during Veress and trocar entry, lumbar lordosis should be carefully considered.

[Diffuse Hepatoid Adenocarcinoma in the Peritoneal Cavity:Report of One Case].

Hepatoid adenocarcinoma is a rare and unique type of adenocarcinoma,resembling hepatocellular carcinoma in histopathology.Most cases occur in the stomach,lacking specific clinical and imaging manifestations,which leads to high rates of missed diagnosis and misdiagnosis.Hepatoid adenocarcinoma in the peritoneal cavity is even rarer.This article reports a case of hepatoid adenocarcinoma with the manifestation of diffuse peritoneal thickening,aiming to provide reference for clinical diagnosis and treatment.

Lentiviral Vector Preparation for Efficient Gene and MicroRNA Modulation of Peritoneal Cavity Tissue-Resident Macrophages In Vivo in Mice.

Peritoneal tissue-resident macrophages have broad functions in the maintenance of homeostasis and are involved in pathologies within local and neighboring tissues. Their functions are dictated by microenvironmental cues; thus, it is essential to investigate their behavior in an in vivo physiological niche. Currently, specific peritoneal macrophage-targeting methodologies employ whole-mouse transgenic models. Here, a protocol for effective in vivo modulation of mRNA and small RNA species (e.g., microRNA) expression in peritoneal macrophages using lentivirus particles is described. Lentivirus preparations were made in HEK293T cells and purified on a single sucrose layer. In vivo validation of lentivirus effectivity following intraperitoneal injection revealed predominant infection of macrophages restricted to local tissue. Targeting of peritoneal macrophages was successful during homeostasis and thioglycolate-induced peritonitis. The limitations of the protocol, including low-level inflammation induced by intraperitoneal delivery of lentivirus and time restrictions for potential experiments, are discussed. Overall, this study presents a quick and accessible protocol for the rapid assessment of gene function in peritoneal macrophages in vivo.

[The functional differences of macrophages derived from murine bone marrow and peritoneal cavity].

Objective To compare the functional differences between bone marrow derived macrophages and peritoneal macrophages, which may provide the basis for the selection of macrophages in immunological research and immunoregulatory drug evaluation. Methods Marophage colony-stimulating factor (M-CSF) was used to induce the differentiation of bone marrow monocytes into macrophages, and thioglycolate medium was used to induce peritonitis to obtain peritoneal macrophages. After both macrophages being stimulated by zymosan, LPS, R848 and CpG respectively, mRNA levels of tumor necrosis factor α(TNF-α), interleukin 6(IL-6), macrophage inflammatory protein 1α(MIP-1α), monocyte chemoattractant protein 1(MCP-1) were measured by Real-time fluorescent quantitative PCR and the concentrations of secreted TNF-α, IL-6, MIP-1α and MCP-1 were detected by ELISA. In addition, the expression of costimulatory molecules CD80, CD86, CD40 and histocompatibility complex II (MHC II) on the cell surface was analyzed by flow cytometry. Results After inducing by different TLR ligands, mRNA expression levels of inflammatory cytokines and chemokines were increased in both macrophages. The secretion of TNF-α, IL-6, MIP-1α and MCP-1 in peritoneal macrophages and the expression of CD86 and MHC II on the surface of peritoneal macrophages were significantly higher than those of bone marrow derived macrophages. Conclusion There are significant differences in the expression of inflammatory factors, chemokines, costimulatory molecules, and histocompatibility complex between bone marrow derived macrophages and peritoneal macrophages. Peritoneal macrophages have more complete macrophage function and is more suitable for immunological research and immunomodulatory drug evaluation.

Human tissue-resident peritoneal macrophages reveal resistance towards oxidative cell stress induced by non-invasive physical plasma.

In the context of multimodal treatments for abdominal cancer, including procedures such as cytoreductive surgery and intraperitoneal chemotherapy, recurrence rates remain high, and long-term survival benefits are uncertain due to post-operative complications. Notably, treatment-limiting side effects often arise from an uncontrolled activation of the immune system, particularly peritoneally localized macrophages, leading to massive cytokine secretion and phenotype changes. Exploring alternatives, an increasing number of studies investigated the potential of plasma-activated liquids (PAL) for adjuvant peritoneal cancer treatment, aiming to mitigate side effects, preserve healthy tissue, and reduce cytotoxicity towards non-cancer cells. To assess the non-toxicity of PAL, we isolated primary human macrophages from the peritoneum and subjected them to PAL exposure. Employing an extensive methodological spectrum, including flow cytometry, Raman microspectroscopy, and DigiWest protein analysis, we observed a pronounced resistance of macrophages towards PAL. This resistance was characterized by an upregulation of proliferation and anti-oxidative pathways, countering PAL-derived oxidative stress-induced cell death. The observed cellular effects of PAL treatment on human tissue-resident peritoneal macrophages unveil a potential avenue for PAL-derived immunomodulatory effects within the human peritoneal cavity. Our findings contribute to understanding the intricate interplay between PAL and macrophages, shedding light on the promising prospects for PAL in the adjuvant treatment of peritoneal cancer.

Radiological characteristics and diagnostic clues for persistent descending mesocolon in patients with rectal cancer.

PURPOSE: Persistent descending mesocolon (PDM) increases the difficulty and colonic ischemia in the surgery of colorectal cancer, but the preoperative diagnostic criteria have not yet been clearly demonstrated. This study explored the MR imaging features and diagnostic criteria of PDM to improve the preoperative diagnostic rate. METHODS: The clinical data of 54 patients with PDM and 270 patients without PDM who underwent rectal surgery at the Department of Colorectal Surgery, Fujian Medical University Union Hospital, from March 2018 to December 2022 were analyzed, retrospectively. The radiological parameters of PDM from MRI were analyzed. RESULTS: On MRI T2WI axial image, the left edge of the abdominal aorta was defined as the reference line. The shortest vertical distance between the right edge of the descending colon and this line (dN) and the maximum transverse diameter of the peritoneal cavity (dA) at the same level and the maximum vertical distance between the right edge of the descending colon and this line (dW) were measured. There were significant statistical differences in dN, dW, dN/dW, and dN/dA between the PDM group and the non-PDM group. dN, dN/dW, and dN/dA have high diagnostic performance for the PDM. dN < 4.16 cm, dN/dW < 0.52, and dN/dA < 0.15 can all be used as clues to diagnose PDM. CONCLUSIONS: We propose a feasible set of diagnostic criteria for PDM based on abdominal MRI, which can quickly and accurately diagnose PDM, and provide some reference for preoperative planning and surgical decision-making.

Random Forest Modeling of Acute Toxicity in Anal Cancer: Effects of Peritoneal Cavity Contouring Approaches on Model Performance.

PURPOSE: Our purpose was to analyze the effect on gastrointestinal (GI) toxicity models when their dose-volume metrics predictors are derived from segmentations of the peritoneal cavity after different contouring approaches. METHODS AND MATERIALS: A random forest machine learning approach was used to predict acute grade ≥3 GI toxicity from dose-volume metrics and clinicopathologic factors for 246 patients (toxicity incidence = 9.5%) treated with definitive chemoradiation for squamous cell carcinoma of the anus. Three types of random forest models were constructed based on different bowel bag segmentation approaches: (1) physician-delineated after Radiation Therapy Oncology Group (RTOG) guidelines, (2) autosegmented by a deep learning model (nnU-Net) following RTOG guidelines, and (3) autosegmented but spanning the entire bowel space. Each model type was evaluated using repeated cross-validation (100 iterations; 50%/50% training/test split). The performance of the models was assessed using area under the precision-recall curve (AUPRC) and the receiver operating characteristic curve (AUROCC), as well as optimal F1 score. RESULTS: When following RTOG guidelines, the models based on the nnU-Net auto segmentations (mean values: AUROCC, 0.71 ± 0.07; AUPRC, 0.42 ± 0.09; F1 score, 0.46 ± 0.08) significantly outperformed (P < .001) those based on the physician-delineated contours (mean values: AUROCC, 0.67 ± 0.07; AUPRC, 0.34 ± 0.08; F1 score, 0.36 ± 0.07). When spanning the entire bowel space, the performance of the autosegmentation models improved considerably (mean values: AUROCC, 0.87 ± 0.05; AUPRC, 0.70 ± 0.09; F1 score, 0.68 ± 0.09). CONCLUSIONS: Random forest models were superior at predicting acute grade ≥3 GI toxicity when based on RTOG-defined bowel bag autosegmentations rather than physician-delineated contours. Models based on autosegmentations spanning the entire bowel space show further considerable improvement in model performance. The results of this study should be further validated using an external data set.

Loss of B1 and marginal zone B cells during ovarian cancer.

Recent advances in immunotherapy have not addressed the challenge presented by ovarian cancer. Although the peritoneum is an "accessible" locus for this disease there has been limited characterization of the immunobiology therein. We investigated the ID8-C57BL/6J ovarian cancer model and found marked depletion of B1 cells from the ascites of the peritoneal cavity. There was also selective loss of the B1 and marginal zone B cell subsets from the spleen. Immunity to antigens that activate these subsets validated their loss rather than relocation. A marked influx of myeloid-derived suppressor cells correlated with B cell subset depletion. These observations are discussed in the context of the housekeeping burden placed on innate B cells during ovarian cancer and to foster consideration of B cell biology in therapeutic strategies to address this challenge.

Supragastric lesser sac: an insidious site for surgical exploration during the debulking surgery in advanced ovarian cancer.

OBJECTIVE: Metastases in the supragastric lesser sac (SGLS) are not only occult but are also barriers to complete resection of ovarian cancer. We describe a cohort of patients with SGLS disease undergoing debulking surgery. METHODS: We identified all patients who underwent evaluation and eventual resection of SGLS disease as part of cytoreductive surgery for stage IIIC-IVB high-grade epithelial ovarian cancer at our institution from January 2018 to August 2022. RESULTS: Thirty-three of 286 patients (11.5%) underwent resection of SGLS disease. Metastases in the SGLS were identified by preoperative imaging in 4 of 33 patients (12.1%). The median peritoneal cancer index score was 22 (range, 9-33). Through surgical exploration, metastases were frequently seen in the right diaphragm (100%), hepatorenal recess (97%), lesser omentum (81.8%), left diaphragm (78.8%), supracolic omentum (75.8%), anterior transverse mesocolon (72.7%), splenic hilum (63.6%), ligamentum teres hepatis (60.6%), and gallbladder fossa (51.5%). The lesser omentum was normal in 6 of 33 (18.2%) patients, despite metastases within the SGLS. A total of 54.5% of patients underwent complex surgery (surgical complexity scores; median, 8; range, 3-14). Complete resections were achieved in 19 (57.6%) patients. No complications were related to the resection of SGLS disease. The median length of progression-free survival was 24.8 months (95% confidence interval=16.6-32.9). CONCLUSION: Metastases to the SGLS are not uncommon in advanced ovarian cancer, particularly those with widely disseminated disease. Disease in this recess is rarely identified by preoperative imaging and deserves systematic surgical exploration to attain complete cytoreduction.

Neuroendocrine tumour of the lesser omentum.

A man in his early 20s presented to us in the outpatient department with a history of diarrhoea for 4 months. Investigations revealed elevated serum chromogranin levels and an intensely avid lesion in the gastrohepatic ligament in Gallium DOTATATE positron emission tomography (PET). The tumour was excised laparoscopically, and no other lesions were seen. The patient improved clinically and had a normal serum chromogranin level postoperatively. He is currently much improved at the 1year follow-up. We did an extensive workup to look for a primary tumour. It was concluded that it was a de novo tumour arising from the lesser sac. The recommended investigations in case of neuroendocrine tumour (NET) with unknown primary include blood investigations to look for the functional status of the tumour, histopathological examination, including immunohistochemistry, and radiological imaging, which must include a Gallium DOTATATE PET. An isolated NET of the lesser sac has not been reported in the literature.

Farnesol remodels the peritoneal cavity immune environment influencing Candida albicans pathogenesis during intra-abdominal infection.

Candida albicans is a lifelong member of the mycobiome causing mucosal candidiasis and life-threatening, systemic, and intra-abdominal disease in immunocompromised and transplant patients. Despite the clinical importance of intra-abdominal candidiasis with mortality rates between 40% and 70%, the contribution of fungal virulence factors and host immune responses to disease has not been extensively studied. Secretion of the quorum-sensing molecule, farnesol, acts as a virulence factor for C. albicans during systemic infection, while inducing local, protective innate immune responses in oral models of infection. Previously, we reported that farnesol recruits macrophages to the peritoneal cavity in mice, suggesting a role for farnesol in innate immune responses. Here, we expand on our initial findings, showing that farnesol profoundly alters the peritoneal cavity microenvironment promoting innate inflammation. Intra-peritoneal injection of farnesol stimulates rapid local death of resident peritoneal cells followed by recruitment of neutrophils and inflammatory macrophages into the peritoneal cavity and peritoneal mesothelium associated with an early increase in chemokines followed by proinflammatory cytokines. These rapid inflammatory responses to farnesol significantly increase morbidity and mortality of mice with intra-abdominal candidiasis associated with increased formation of peritoneal adhesions, despite similar rates of fungal clearance from the peritoneal cavity and retro-peritoneal organs. C. albicans ddp3Δ/ddp3Δ knockout and reconstituted strains recapitulate these findings. This indicates that farnesol may be detrimental to the host during intra-abdominal infections. Importantly, our results highlight a need to understand how C. albicans virulence factors modulate the host immune response within the peritoneum, an exceedingly common site of Candida infection.

Revisiting the Use of Normal Saline for Peritoneal Washing in Ovarian Cancer.

The omentum is the predominant site of ovarian cancer metastasis, but it is difficult to remove the omentum in its entirety. There is a critical need for effective approaches that minimize the risk of colonization of preserved omental tissues by occult cancer cells. Normal saline (0.9% sodium chloride) is commonly used to wash the peritoneal cavity during ovarian cancer surgery. The omentum has a prodigious ability to absorb fluid in the peritoneal cavity, but the impact of normal saline on the omentum is poorly understood. In this review article, we discuss why normal saline is not a biocompatible solution, drawing insights from clinical investigations of normal saline in fluid resuscitation and from the cytopathologic evaluation of peritoneal washings. We integrate these insights with the unique biology of the omentum and omental metastasis, highlighting the importance of considering the absorptive ability of the omentum when administering agents into the peritoneal cavity. Furthermore, we describe insights from preclinical studies regarding the mechanisms by which normal saline might render the omentum conducive for colonization by cancer cells. Importantly, we discuss the possibility that the risk of colonization of preserved omental tissues might be minimized by using balanced crystalloid solutions for peritoneal washing.

TAPEWORMS (CESTODA: OPHIOTAENIA) FROM THE NORTHERN COTTONMOUTH (AGKISTRODON PISCIVORUS).

The northern cottonmouth, Agkistrodon piscivorus (Lacépède, 1789) (Viperidae: Crotalinae), occurs in the southeastern United States and is one of the few semiaquatic vipers in the world. Three proteocephalid tapeworms of the genus OphiotaeniaLa Rue, 1911 (Cestoda), have been described from this venomous snake. A critical evaluation of type specimens and tapeworms recently collected from A. piscivorus has revealed that only 2 species, Ophiotaenia marenzelleri (Barrois, 1898) and Ophiotaenia grandisLa Rue, 1911 (new synonym Ophiotaenia agkistrodontis [Harwood, 1933]), are specific parasites of this crotaline viper; both species are redescribed here. Ophiotaenia grandis was originally described from a mixture of 2 species: 'true' O. grandis, which is indistinguishable from O. agkistrodontis described 22 yr later and thus considered to be a junior synonym of O. grandis, and O. marenzelleri. Ophiotaenia marenzelleri, also reported from the pygmy rattlesnake, Sistrurus miliarius (Linnaeus, 1766), is a larger tapeworm with a massive scolex, a large cirrus sac, a very large, annular vaginal sphincter near the equatorial gonopore, and an oval, 3-layered embryophore surrounded by a nearly square hyaline outer membrane. Ophiotaenia grandis is much smaller and more slender and has a narrower scolex, a smaller cirrus sac and vaginal sphincter, a 2-layered embryophore, and a distinctly pre-equatorial gonopore. In addition to O. marenzelleri and O. grandis, other Ophiotaenia species typical of semiaquatic snakes (Colubridae: Natricinae) may be present in the northern cottonmouth, which serves only as a postcyclic or occasional host. There is also a tabular summary of 18 species of Ophiotaenia from semiaquatic snakes worldwide, with information on their hosts, distribution, and taxonomically important characters, including key measurements.

Homeostatic role of B-1 cells in tissue immunity.

To date, studies of tissue-resident immunity have mainly focused on innate immune cells and T cells, with limited data on B cells. B-1 B cells are a unique subset of B cells with innate-like properties, enriched in murine pleural and peritoneal cavities and distinct from conventional B-2 cells in their ontogeny, phenotype and function. Here we discuss how B-1 cells represent exemplar tissue-resident immune cells, summarizing the evidence for their long-term persistence & self-renewal within tissues, differential transcriptional programming shaped by organ-specific environmental cues, as well as their tissue-homeostatic functions. Finally, we review the emerging data supporting the presence and homeostatic role of B-1 cells across non-lymphoid organs (NLOs) both in mouse and human.

Iron increases the profibrotic properties of the senescent peritoneal mesothelial cells.

BACKGROUND: Treatment of anemia in peritoneal dialysis patients often requires intravenous iron supplementation. Iron diffuses into the peritoneal cavity and is injurious to the peritoneum. We studied how intermittent exposure to iron changes the properties of the senescent peritoneal mesothelial cells (MC). METHODS: Replicative senescence was induced in MC in control medium (Con) or in control medium with intermittent exposure to iron isomaltoside 15 µg/dL (Con-IIS). After 10 passages properties of MC from both groups were compared to MC not exposed to replicative senescence. RESULTS: In senescent MC population doubling time was elongated, intracellular generation of free radicals and staining for ß-galactosidase was stronger than in MC not exposed to replicative senescence. All these effects were stronger in MC intermittently exposed to IIS. In these cells intracellular iron content was also higher. Also expression of genes p21 and p53 was stronger in MC intermittently treated with IIS. In senescent cells higher release and expression of IL6 and TGFß1 was observed and that effect was stronger in MC treated with iron. Senescent MC had reduced fibrinolytic activity, what may predispose to the peritoneal fibrosis. Synthesis of collagen was higher in senescent cells, more in MC treated with iron. CONCLUSION: MC aging results in change of their genotype and phenotype which lead to their profibrotic effect. Exposure to iron enhances these changes.