Role of Rabenosyn-5 and Rab5b in host cell cytosol uptake reveals conservation of endosomal transport in malaria parasites.

Vesicular trafficking, including secretion and endocytosis, plays fundamental roles in the unique biology of Plasmodium falciparum blood-stage parasites. Endocytosis of host cell cytosol (HCC) provides nutrients and room for parasite growth and is critical for the action of antimalarial drugs and parasite drug resistance. Previous work showed that PfVPS45 functions in endosomal transport of HCC to the parasite's food vacuole, raising the possibility that malaria parasites possess a canonical endolysosomal system. However, the seeming absence of VPS45-typical functional interactors such as rabenosyn 5 (Rbsn5) and the repurposing of Rab5 isoforms and other endolysosomal proteins for secretion in apicomplexans question this idea. Here, we identified a parasite Rbsn5-like protein and show that it functions with VPS45 in the endosomal transport of HCC. We also show that PfRab5b but not PfRab5a is involved in the same process. Inactivation of PfRbsn5L resulted in PI3P and PfRab5b decorated HCC-filled vesicles, typical for endosomal compartments. Overall, this indicates that despite the low sequence conservation of PfRbsn5L and the unusual N-terminal modification of PfRab5b, principles of endosomal transport in malaria parasite are similar to that of model organisms. Using a conditional double protein inactivation system, we further provide evidence that the PfKelch13 compartment, an unusual apicomplexa-specific endocytosis structure at the parasite plasma membrane, is connected upstream of the Rbsn5L/VPS45/Rab5b-dependent endosomal route. Altogether, this work indicates that HCC uptake consists of a highly parasite-specific part that feeds endocytosed material into an endosomal system containing more canonical elements, leading to the delivery of HCC to the food vacuole.

The Kelch13 compartment contains highly divergent vesicle trafficking proteins in malaria parasites.

Single amino acid changes in the parasite protein Kelch13 (K13) result in reduced susceptibility of P. falciparum parasites to artemisinin and its derivatives (ART). Recent work indicated that K13 and other proteins co-localising with K13 (K13 compartment proteins) are involved in the endocytic uptake of host cell cytosol (HCCU) and that a reduction in HCCU results in reduced susceptibility to ART. HCCU is critical for parasite survival but is poorly understood, with the K13 compartment proteins among the few proteins so far functionally linked to this process. Here we further defined the composition of the K13 compartment by analysing more hits from a previous BioID, showing that MyoF and MCA2 as well as Kelch13 interaction candidate (KIC) 11 and 12 are found at this site. Functional analyses, tests for ART susceptibility as well as comparisons of structural similarities using AlphaFold2 predictions of these and previously identified proteins showed that vesicle trafficking and endocytosis domains were frequent in proteins involved in resistance or endocytosis (or both), comprising one group of K13 compartment proteins. While this strengthened the link of the K13 compartment to endocytosis, many proteins of this group showed unusual domain combinations and large parasite-specific regions, indicating a high level of taxon-specific adaptation of this process. Another group of K13 compartment proteins did not influence endocytosis or ART susceptibility and lacked detectable vesicle trafficking domains. We here identified the first protein of this group that is important for asexual blood stage development and showed that it likely is involved in invasion. Overall, this work identified novel proteins functioning in endocytosis and at the K13 compartment. Together with comparisons of structural predictions it provides a repertoire of functional domains at the K13 compartment that indicate a high level of adaption of endocytosis in malaria parasites.

[Watch and Wait for Rectal Cancer]. / Surveillance bei Watch-and-Wait nach neoadjuvanter Therapie beim Rektumkarzinom.

About one third of all colorectal carcinomas (CRC) are localised in the rectum. As part of a multimodal therapy concept, neoadjuvant therapy achieves downstaging of the tumour in 50-60% of cases and a so-called complete clinical response (cCR), defined as clinically (and radiologically) undetectable residual tumour after completion of neoadjuvant therapy, in 10-30% of cases.In view of the perioperative morbidity and mortality associated with radical rectal resection, including the occurrence of a symptom complex known as low anterior resection syndrome (LARS) and the need for deviation, at least temporarily, the question of the risk-benefit balance of organ resection in the presence of cCR has been raised. In this context, the therapeutic concept of a "watch-and-wait" approach with omission of immediate organ resection and inclusion in a structured surveillance regime, has emerged.For a safe, oncological implementation of this option, it is necessary to develop standards in the definition of a suitable patient clientele and the implementation of the concept. In addition to the initial correct selection of the patient group that is suitable for a primarily non-surgical procedure, the inherent goal is the early and sufficient detection of tumour recurrence (so-called local regrowth) during the "watch-and-wait" phase (surveillance).In this context, in this paper we address the questions of: 1. the optimal timing of initial re-staging, 2. the criteria for assessing the clinical response and selecting the appropriate patient clientele, 3. the rhythm and design of the surveillance protocol.

Nationwide volume-outcome relationship concerning in-hospital mortality and failure-to-rescue in surgery of sigmoid diverticulitis.

PURPOSE: A correlation between the hospital volume and outcome is described for multiple entities of oncological surgery. To date, this has not been analyzed for the surgical treatment of sigmoid diverticulitis. The aim of this study was to explore the impact of the annual caseload per hospital of colon resection on the postoperative incidence of complications, failure to rescue, and mortality in patients with diverticulitis. METHODS: Patients receiving colorectal resection independent from the diagnosis from 2012 to 2017 were selected from a German nationwide administrative dataset. The hospitals were grouped into five equal caseload quintiles (Q1-Q5 in ascending caseload order). The outcome analysis was focused on patients receiving surgery for sigmoid diverticulitis. RESULTS: In total, 662,706 left-sided colon resections were recorded between 2012 and 2017. Of these, 156,462 resections were performed due to sigmoid diverticulitis and were included in the analysis. The overall in-house mortality rate was 3.5%, ranging from 3.8% in Q1 (mean of 9.5 procedures per year) to 3.1% in Q5 (mean 62.8 procedures per year; p < 0.001). Q5 hospitals revealed a risk-adjusted odds ratio of 0.85 (95% CI 0.78-0.94; p < 0.001) for in-hospital mortality compared to Q1 during multivariable logistic regression analysis. High-volume centers showed overall lower complication rates, whereas the failure-to-rescue did not differ significantly. CONCLUSION: Surgical treatment of sigmoid diverticulitis in high-volume colorectal centers shows lower postoperative mortality rates and fewer postoperative complications.

How cortical waves drive fission of motile cells.

Cytokinesis-the division of a cell into two daughter cells-is a key step in cell growth and proliferation. It typically occurs in synchrony with the cell cycle to ensure that a complete copy of the genetic information is passed on to the next generation of daughter cells. In animal cells, cytokinesis commonly relies on an actomyosin contractile ring that drives equatorial furrowing and separation into the two daughter cells. However, also contractile ring-independent forms of cell division are known that depend on substrate-mediated traction forces. Here, we report evidence of an as yet unknown type of contractile ring-independent cytokinesis that we termed wave-mediated cytofission. It is driven by self-organized cortical actin waves that travel across the ventral membrane of oversized, multinucleated Dictyostelium discoideum cells. Upon collision with the cell border, waves may initiate the formation of protrusions that elongate and eventually pinch off to form separate daughter cells. They are composed of a stable elongated wave segment that is enclosed by a cell membrane and moves in a highly persistent fashion. We rationalize our observations based on a noisy excitable reaction-diffusion model in combination with a dynamic phase field to account for the cell shape and demonstrate that daughter cells emerging from wave-mediated cytofission exhibit a well-controlled size.

Versatile Patterns in the Actin Cortex of Motile Cells: Self-Organized Pulses Can Coexist with Macropinocytic Ring-Shaped Waves.

Self-organized patterns in the actin cytoskeleton are essential for eukaryotic cellular life. They are the building blocks of many functional structures that often operate simultaneously to facilitate, for example, nutrient uptake and movement of cells. However, identifying how qualitatively distinct actin patterns can coexist remains a challenge. Using bifurcation theory of a mass conserved activator-inhibitor system, we uncover a generic mechanism of how different actin waves-traveling waves and excitable pulses-organize and simultaneously emerge. Live-cell imaging experiments indeed reveal that narrow, planar, and fast-moving excitable pulses may coexist with ring-shaped macropinocytic actin waves in the cortex of motile amoeboid cells.

Evolution of endoscopic vacuum therapy for upper gastrointestinal leakage over a 10-year period: a quality improvement study.

BACKGROUND: Endoscopic vacuum therapy (EVT) is an effective treatment option for leakage of the upper gastrointestinal (UGI) tract. The aim of this study was to evaluate the clinical impact of quality improvements in EVT management on patients' outcome. METHODS: All patients treated by EVT at our center during 2012-2021 were divided into two consecutive and equal-sized cohorts (period 1 vs. period 2). Over time several quality improvement strategies were implemented including the earlier diagnosis and EVT treatment and technical optimization of endoscopy. The primary endpoint was defined as the composite score MTL30 (mortality, transfer, length-of-stay > 30 days). Secondary endpoints included EVT efficacy, complications, in-hospital mortality, length-of-stay (LOS) and nutrition status at discharge. RESULTS: A total of 156 patients were analyzed. During the latter period the primary endpoint MTL30 decreased from 60.8 to 39.0% (P = .006). EVT efficacy increased from 80 to 91% (P = .049). Further, the need for additional procedures for leakage management decreased from 49.9 to 29.9% (P = .013) and reoperations became less frequent (38.0% vs.15.6%; P = .001). The duration of leakage therapy and LOS were shortened from 25 to 14 days (P = .003) and 38 days to 25 days (P = .006), respectively. Morbidity (as determined by the comprehensive complication index) decreased from 54.6 to 46.5 (P = .034). More patients could be discharged on oral nutrition (70.9% vs. 84.4%, P = .043). CONCLUSIONS: Our experience confirms the efficacy of EVT for the successful management of UGI leakage. Our quality improvement analysis demonstrates significant changes in EVT management resulting in accelerated recovery, fewer complications and improved functional outcome.

Impact of preoperative weight loss achieved by gastric balloon on peri- and postoperative outcomes of bariatric surgery in super-obese patients: a retrospective matched-pair analysis.

BACKGROUND: An intragastric balloon is used to cause weight loss in super-obese patients (BMI > 60 kg/m2) prior to bariatric surgery. Whether weight loss from intragastric balloon influences that from bariatric surgery is poorly studied. METHODS: In this retrospective, single-center study, the effects of intragastric balloon in 26 patients (BMI 69.26 ± 6.81) on weight loss after bariatric surgery (primary endpoint), postoperative complications within 30 days, hospital readmission, operation time, and MTL30 (secondary endpoints) were evaluated. Fifty-two matched-pair patients without intragastric balloon prior to bariatric surgery were used as controls. RESULTS: Intragastric balloon resulted in a weight loss of 17.3 ± 14.1 kg (BMI 5.75 ± 4.66 kg/m2) with a nadir after 5 months. Surgical and postoperative outcomes including complications were comparable between both groups. Total weight loss was similar in both groups (29.0% vs. 32.2%, p = 0.362). Direct postoperative weight loss was more pronounced in the control group compared to the gastric balloon group (29.16 ± 7.53% vs 23.78 ± 9.89% after 1 year, p < 0.05 and 32.13 ± 10.5% vs 22.21 ± 10.9% after 2 years, p < 0.05), who experienced an earlier nadir and started to regain weight during the follow-up. CONCLUSION: A multi-stage therapeutic approach with gastric balloon prior to bariatric surgery in super-obese patients may be effective to facilitate safe surgery. However, with the gastric balloon, pre-treated patients experienced an attenuated postoperative weight loss with an earlier nadir and earlier body weight regain. This should be considered when choosing the appropriate therapeutic regime and managing patients' expectations.

[Online Teaching in Surgery]. / Online-Lehre in der Chirurgie.

For quite some time, the development and implementation of online teaching has been a controversial issue in surgical education for the degree in medicine. This has become more important with the progression of digitalisation and not least as a result of the current pandemic. It is becoming increasingly urgent to establish the opportunities and limits of online teaching, which has already proved successful under the current developmental pressure, and there are promising concepts. This article addresses the framework and the various online teaching formats in surgery, and illustrates the interplay between technical feasibility, practical experience, and didactic objectives.

Endoscopic full thickness resection vs. transanal endoscopic microsurgery for local treatment of rectal neuroendocrine tumors - a retrospective analysis.

PURPOSE: Local treatment of small well-differentiated rectal neuroendocrine tumors (NETs) is recommended by current guidelines. However, although several endoscopic methods have been established, the highest R0 rate is achieved by transanal endoscopic microsurgery (TEM). Since a recently published study about endoscopic full thickness resection (eFTR) showed a R0 resection rate of 100%, the aim of this study was to evaluate both methods (eFTR vs. TEM). METHODS: We retrospectively analyzed all patients with rectal NET treated either by TEM (1999-2018) or eFTR (2016-2019) in two tertiary centers (University Hospital Wuerzburg and Ulm). We analyzed clinical, procedural, and histopathological outcomes in both groups. RESULTS: Twenty-eight patients with rectal NET received local treatment (TEM: 13; eFTR: 15). Most tumors were at stage T1a and grade G1 or G2 (in the TEM group two G3 NETs were staged T2 after neoadjuvant chemotherapy). In both groups, similar outcomes for en bloc resection rate, R0 resection rate, tumor size, or specimen size were found. No procedural adverse events were noted. Mean procedure time in the TEM group was 48.9 min and 19.2 min in the eFTR group. CONCLUSION: eFTR is a convincing method for local treatment of small rectal NETs combining high safety and efficacy with short interventional time.

Impact of the COVID-19 pandemic on appendicitis treatment in Germany-a population-based analysis.

PURPOSE: Acute appendicitis is one of the most common reasons for emergency medical consultation. While simple appendicitis can be treated with antibiotics or surgery, complex appendicitis including gangrene, abscess, and perforation requires appendectomy. During the COVID-19 pandemic in early 2020, an overall drop in emergency room consultations was observed. We therefore aimed to investigate the incidence and treatment strategies of acute appendicitis during that period. METHODS: Data of insurance holders with the ICD code for "acute appendicitis" or OPS procedure of appendectomy of a major health insurance company in Germany were analyzed retrospectively. Groups were built, containing of the means of March-June of 2017, 2018, and 2019, defined as "pre-COVID group" with the "COVID group," defined as data from March to June of 2020. Data was analyzed by age, sex, comorbidities, length of hospital stay, diagnoses, and treatment. Data of the COVID group was analyzed for simultaneous COVID-19 infection. RESULTS: During the COVID-19 pandemic of early 2020, an overall reduction by 12.9% of patients presenting with acute appendicitis was noticeable. These results were mainly due to decreased rates of uncomplicated appendicitis, while complicated appendicitis was scarcely affected. Especially in the group of females < 40 years, a drastic reduction was visible. Rates of extended surgery did not change. Likewise, the complication rate like appendix stump leakage or need for re-operation did not differ. In March 2020, 4.8% of acute appendicitis patients had concomitant COVID-19 infection. CONCLUSION: In line with the overall drop of emergency room visits during the COVID-19 pandemic of spring 2020 in Germany, a significantly lowered number of patients with uncomplicated appendicitis were noticeable, whereas complicated appendicitis did not differ. Also, treatment and complication rate of acute appendicitis did not change. These findings might be a hint that acute appendicitis is not a progressing disease but caused by different entities for uncomplicated and complicated appendicitis and therefore another clue that uncomplicated appendicitis can be treated with antibiotics or observation. Nevertheless provided data does not cover outpatient treatment; therefore, no statement observation or antibiotics in outpatients can be made.

Intestinal Epithelial Barrier Maturation by Enteric Glial Cells Is GDNF-Dependent.

Enteric glial cells (EGCs) of the enteric nervous system are critically involved in the maintenance of intestinal epithelial barrier function (IEB). The underlying mechanisms remain undefined. Glial cell line-derived neurotrophic factor (GDNF) contributes to IEB maturation and may therefore be the predominant mediator of this process by EGCs. Using GFAPcre x Ai14floxed mice to isolate EGCs by Fluorescence-activated cell sorting (FACS), we confirmed that they synthesize GDNF in vivo as well as in primary cultures demonstrating that EGCs are a rich source of GDNF in vivo and in vitro. Co-culture of EGCs with Caco2 cells resulted in IEB maturation which was abrogated when GDNF was either depleted from EGC supernatants, or knocked down in EGCs or when the GDNF receptor RET was blocked. Further, TNFα-induced loss of IEB function in Caco2 cells and in organoids was attenuated by EGC supernatants or by recombinant GDNF. These barrier-protective effects were blunted when using supernatants from GDNF-deficient EGCs or by RET receptor blockade. Together, our data show that EGCs produce GDNF to maintain IEB function in vitro through the RET receptor.

A genetic system to study Plasmodium falciparum protein function.

Current systems to study essential genes in the human malaria parasite Plasmodium falciparum are often inefficient and time intensive, and they depend on the genetic modification of the target locus, a process hindered by the low frequency of integration of episomal DNA into the genome. Here, we introduce a method, termed selection-linked integration (SLI), to rapidly select for genomic integration. SLI allowed us to functionally analyze targets at the gene and protein levels, thus permitting mislocalization of native proteins, a strategy known as knock sideways, floxing to induce diCre-based excision of genes and knocking in altered gene copies. We demonstrated the power and robustness of this approach by validating it for more than 12 targets, including eight essential ones. We also localized and inducibly inactivated Kelch13, the protein associated with artemisinin resistance. We expect this system to be widely applicable for P. falciparum and other organisms with limited genetic tractability.

Patterns of Lymph Node Recurrence in Adrenocortical Carcinoma: Possible Implications for Primary Surgical Treatment.

BACKGROUND: In the surgical treatment of adrenocortical carcinoma (ACC), lymphadenectomy may improve oncologic outcome. However, patterns of metastatic lymphatic spread in ACC are unknown. METHODS: Clinical data of patients included in the European Network for the Study of Adrenal Tumors (ENSAT) registry were retrospectively reviewed. Inclusion criteria were: nonmetastatic ACC, complete resection of the primary tumor, a disease-free time of > 3 months, and lymph node metastases as the first disease relapse. The retroperitoneal lymphatic drainage area was evaluated by using follow-up imaging. RESULTS: Of 971 patients from the ENSAT registry, 56 patients were included. In left-sided ACC (n = 36), lymphatic recurrence was detected in the left renal hilum (50%), in the perirenal fat tissue cranial to the renal hilum (ventral, 47%; dorsal, 55%), para-aortic (47%), interaorto-caval (22%), and/or in the perirenal fat tissue caudal to the renal hilum (ventral, 20%; dorsal, 17%). In right-sided ACC (n = 20), lymph node metastases were detected in the perirenal fat tissue cranial to the renal hilum (dorsal, 55%; ventral, 45%), interaorto-caval (35%), in the area of the right renal artery (10%), and/or paracaval (15%). Patients with right-sided ACC showed left-paraaortic lymph node recurrences in 10% of cases. CONCLUSION: Metastatic lymphatic spread appears to be more extensive than previously thought. The distribution pattern of lymph node metastases described in our study could be used as a guide for a more extended lymph node dissection.

The glial cell-line derived neurotrophic factor: a novel regulator of intestinal barrier function in health and disease.

Regulation of the intestinal epithelial barrier is a differentiated process, which is profoundly deranged in inflammatory bowel diseases. Recent data provide evidence that the glial cell line-derived neurotrophic factor (GDNF) is critically involved in intestinal epithelial wound healing and barrier maturation and exerts antiapoptotic effects under certain conditions. Furthermore, not only the enteric nervous system, but also enterocytes synthesize GDNF in significant amounts, which points to a potential para- or autocrine signaling loop between enterocytes. Apart from direct effects of GDNF on enterocytes, an immunomodulatory role of this protein has been previously assumed because of a significant reduction of inflammation in a model of chronic inflammatory bowel disease after application of GDNF. In this review we summarize the current knowledge of GDNF on intestinal epithelial barrier regulation and discuss the novel role for GDNF as a regulator of intestinal barrier functions in health and disease.