Graphs that are not pairwise compatible: A new proof technique (extended abstract)

A graph G = (V,E) is a pairwise compatibility graph (PCG) if there exists an edge-weighted tree T and two non-negative real numbers dminand dmax, dmin≤ dmax, such that each node u∈V is uniquely associated to a leaf of T and there is an edge (u, v) ∈ E if and only if dmin≤ dT(u, v) ≤ dmax, where dT(u, v) is the sum of the weights of the edges on the unique path PT(u, v) from u to v in T. Understanding which graph classes lie inside and which ones outside the PCG class is an important issue. Despite numerous efforts, a complete characterization of the PCG class is not known yet. In this paper we propose a new proof technique that allows us to show that some interesting classes of graphs have empty intersection with PCG. We demonstrate our technique by showing many graph classes that do not lie in PCG. As a side effect, we show a not pairwise compatibility planar graph with 8 nodes (i.e. C28), so improving the previously known result concerning the smallest planar graph known not to be PCG

Colorectal surgery in Italy during the Covid19 outbreak: a survey from the iCral study group

Background The COVID19 pandemic had a deep impact on healthcare facilities in Italy, with profound reorganization of surgical activities. The Italian ColoRectal Anastomotic Leakage (iCral) study group collecting 43 Italian surgical centers experienced in colorectal surgery from multiple regions performed a quick survey to make a snapshot of the current situation. Methods A 25-items questionnaire was sent to the 43 principal investigators of the iCral study group, with questions regard- ing qualitative and quantitative aspects of the surgical activity before and after the COVID19 outbreak. Results Two-thirds of the centers were involved in the treatment of COVID19 cases. Intensive care units (ICU) beds were partially or totally reallocated for the treatment of COVID19 cases in 72% of the hospitals. Elective colorectal surgery for malignancy was stopped or delayed in nearly 30% of the centers, with less than 20% of them still scheduling elective colo- rectal resections for frail and comorbid patients needing postoperative ICU care. A significant reduction of the number of colorectal resections during the time span from January to March 2020 was recorded, with significant delay in treatment in more than 50% of the centers. Discussion Our survey confirms that COVID19 outbreak is severely affecting the activity of colorectal surgery centers partici- pating to iCral study group. This could impact the activity of surgical centers for many months after the end of the emergency

ICG fluorescence imaging in colorectal surgery: a snapshot from the ICRAL study group

Background: Fluorescence-guided visualization is a recently proposed technology in colorectal surgery. Possible uses include evaluating perfusion, navigating lymph nodes and searching for hepatic metastases and peritoneal spread. Despite the absence of high-level evidence, this technique has gained considerable popularity among colorectal surgeons due to its significant reliability, safety, ease of use and relatively low cost. However, the actual use of this technique in daily clinical practice has not been reported to date. Methods: This survey was conducted on April 2020 among 44 centers dealing with colorectal diseases and participating in the Italian ColoRectal Anastomotic Leakage (iCral) study group. Surgeons were approximately equally divided based on geographical criteria from multiple Italian regions, with a large proportion based in public (89.1%) and nonacademic (75.7%) centers. They were invited to answer an online survey to snapshot their current behaviors regarding the use of fluorescence-guided visualization in colorectal surgery. Questions regarding technological availability, indications and techniques, personal approaches and feelings were collected in a 23-item questionnaire. Results: Questionnaire replies were received from 37 institutions and partially answered by 8, as this latter group of centers do not implement fluorescence technology (21.6%). Out of the remaining 29 centers (78,4%), fluorescence is utilized in all laparoscopic colorectal resections by 72.4% of surgeons and only for selected cases by the remaining 27.6%, while 62.1% of respondents do not use fluorescence in open surgery (unless the perfusion is macroscopically uncertain with the naked eye, in which case 41.4% of them do). The survey also suggests that there is no agreement on dilution, dosing and timing, as many different practices are adopted based on personal judgment. Only approximately half of the surgeons reported a reduced leak rate with fluorescence perfusion assessment, but 65.5% of them strongly believe that this technique will become a minimum requirement for colorectal surgery in the future. Conclusion: The survey confirms that fluorescence is becoming a widely used technique in colorectal surgery. However, both the indications and methods still vary considerably; furthermore, the surgeons' perceptions of the results are insufficient to consider this technology essential. This survey emphasizes the need for further research to reach recommendations based on solid scientific evidence. Keywords: Colon cancer; Fluorescence guided surgery; ICG; Laparoscopy; Rectal cancer

Targeted Therapy with Nanatinostat and Valganciclovir in Recurrent EBV-Positive Lymphoid Malignancies: A Phase 1b/2 Study

Lymphomas are not infrequently associated with the Epstein-Barr virus (EBV), and EBV positivity is linked to worse outcomes in several subtypes. Nanatinostat is a class-I selective oral histone deacetylase inhibitor that induces the expression of lytic EBV BGLF4 protein kinase in EBV+ tumor cells, activating ganciclovir via phosphorylation, resulting in tumor cell apoptosis. This phase 1b/2 study investigated the combination of nanatinostat with valganciclovir in patients aged ≥18 years with EBV+ lymphomas relapsed/refractory to ≥1 prior systemic therapy with no viable curative treatment options. In the phase 1b part, 25 patients were enrolled into 5 dose escalation cohorts to determine the recommended phase 2 dose (RP2D) for phase 2 expansion. Phase 2 patients (n = 30) received RP2D (nanatinostat 20 mg daily, 4 days per week with valganciclovir 900 mg orally daily) for 28-day cycles. The primary end points were safety, RP2D determination (phase 1b), and overall response rate (ORR; phase 2). Overall, 55 patients were enrolled (B-non-Hodgkin lymphoma [B-NHL], [n = 10]; angioimmunoblastic T-cell lymphoma-NHL, [n = 21]; classical Hodgkin lymphoma, [n = 11]; and immunodeficiency-associated lymphoproliferative disorders, [n = 13]). The ORR was 40% in 43 evaluable patients (complete response rate [CRR], 19% [n = 8]) with a median duration of response of 10.4 months. For angioimmunoblastic T-cell lymphoma-NHL (n = 15; all refractory to the last prior therapy), the ORR/CRR ratio was 60%/27%. The most common adverse events were nausea (38% any grade) and cytopenia (grade 3/4 neutropenia [29%], thrombocytopenia [20%], and anemia [20%]). This novel oral regimen provided encouraging efficacy across several EBV+ lymphoma subtypes and warrants further evaluation; a confirmatory phase 2 study (NCT05011058) is underway. This phase 1b/2 study is registered at www.clinicaltrials.gov as #NCT03397706

2019 update of the WSES guidelines for management of Clostridioides (Clostridium) difficile infection in surgical patients

In the last three decades, Clostridium difficile infection (CDI) has increased in incidence and severity in many countries worldwide. The increase in CDI incidence has been particularly apparent among surgical patients. Therefore, prevention of CDI and optimization of management in the surgical patient are paramount. An international multidisciplinary panel of experts from the World Society of Emergency Surgery (WSES) updated its guidelines for management of CDI in surgical patients according to the most recent available literature. The update includes recent changes introduced in the management of this infection.Peer reviewe

CA 15-3 as a tumor marker in gynecological malignancies.

Serum levels of CA 15-3 were measured in 778 samples from 270 patients with benign and malignant gynecological conditions. Malignant tumors were present in 180 patients including 58 cases with cancer of the ovary, 47 of the endometrium, 61 of the cervix, and 14 of the vulva. The 90 cases with benign conditions included 24 patients with ovarian tumors, 28 with fibromyomatosis, 18 with endometriosis, and 20 with endometrial hyperplasia. Of 180 cancer patients, CA 15-3 serum levels were elevated (greater than 30 U/ml) in 74 cases (41%) and the frequency of abnormal marker values increased with clinical stage. Of 90 patients with benign conditions, high CA 15-3 levels were found in 5 cases (6%) with benign ovarian tumors. Elevated levels of the marker were most commonly seen in ovarian cancer patients (71%). In endometrial, cervical, and vulvar cancer abnormal CA 15-3 values occurred in 32, 26, and 14%, respectively. In endometrial cancer the percentage of positive marker levels increased with more infiltrating and/or less differentiated tumors. A positive correlation was found between residual tumor after surgery and CA 15-3 levels. Serial measurements in sera of patients who underwent chemotherapy showed a good correlation with response to treatment. CA 15-3 values were correlated with clinical course of disease in 87% of cases