Comparison of perioperative outcomes between colorectal operations performed on weekends vs those performed on weekdays.

BACKGROUND: Weekend surgical time is an underused asset. Concerns over a possible weekend effect (substandard care) may be a barrier. METHODS: This study examined whether a weekend effect applies to elective colorectal surgery via a single-center retrospective analysis comparing outcomes between patients who underwent elective colorectal surgery on a weekend vs a weekday. Demographics, length of stay (LOS), operative and anesthesia time, the rate of reoperation within 30 days, and the rate of major complications were compared between patient groups. RESULTS: Of the 2008 patients identified, 1721 (85.7%) underwent surgery on a weekday, and 287 (14.3%) underwent surgery on a weekend. The proportion of operations with an open approach was higher on weekends than weekdays (49.5% vs 41.8%, P = .017). Patients who underwent surgery on the weekend tended to have a shorter mean (SE) for LOS (4.2 [0.2] vs 6.1 [0.2], P < .001), anesthesia time (233.8 [6.5] vs 307.6 [3.3] minutes, P < .001), and operative time (225.4 [6.4] vs. 297.6 [3.3] minutes, P < .001). On multivariable analysis, patients who had an operation on a weekend had a 38% lower chance of having a prolonged LOS (>75th percentile of LOS) compared with those who had an operation on a weekday (adjusted odds ratio = 0.62; 95% CI 0.42-0.92). There were no differences in rates of complications or reoperation for patients undergoing surgery on a weekend compared with a weekday. CONCLUSION: At centers with experienced anesthesiologists, appropriately trained nursing staff, and expert surgeons, colorectal surgery performed on a weekend has similar safety outcomes as surgeries performed on a weekday.

Endoplasmic reticulum exit sites are segregated for secretion based on cargo size.

TANGO1, TANGO1-Short, and cTAGE5 form stable complexes at the endoplasmic reticulum exit sites (ERES) to preferably export bulky cargoes. Their C-terminal proline-rich domain (PRD) binds Sec23A and affects COPII assembly. The PRD in TANGO1-Short was replaced with light-responsive domains to control its binding to Sec23A in U2OS cells (human osteosarcoma). TANGO1-ShortΔPRD was dispersed in the ER membrane but relocated rapidly, reversibly, to pre-existing ERES by binding to Sec23A upon light activation. Prolonged binding between the two, concentrated ERES in the juxtanuclear region, blocked cargo export and relocated ERGIC53 into the ER, minimally impacting the Golgi complex organization. Bulky collagen VII and endogenous collagen I were collected at less than 47% of the stalled ERES, whereas small cargo molecules were retained uniformly at almost all the ERES. We suggest that ERES are segregated to handle cargoes based on their size, permitting cells to traffic them simultaneously for optimal secretion.

Tailored assemblies of COPII proteins in secretion.

Export of secretory cargoes from the endoplasmic reticulum (ER) requires COPII proteins, which were first identified for their ability to coat small vesicles that bud from the ER. Recent data indicate that COPII proteins can also organize into a collar at the necks of tubules, as well as phase-separate into liquid-like condensates. Thus, COPII assemblies seem to be tailored to accommodate variations in the size and quantities of cargo secreted.

TANGO1 inhibitors reduce collagen secretion and limit tissue scarring.

Uncontrolled secretion of ECM proteins, such as collagen, can lead to excessive scarring and fibrosis and compromise tissue function. Despite the widespread occurrence of fibrotic diseases and scarring, effective therapies are lacking. A promising approach would be to limit the amount of collagen released from hyperactive fibroblasts. We have designed membrane permeant peptide inhibitors that specifically target the primary interface between TANGO1 and cTAGE5, an interaction that is required for collagen export from endoplasmic reticulum exit sites (ERES). Application of the peptide inhibitors leads to reduced TANGO1 and cTAGE5 protein levels and a corresponding inhibition in the secretion of several ECM components, including collagens. Peptide inhibitor treatment in zebrafish results in altered tissue architecture and reduced granulation tissue formation during cutaneous wound healing. The inhibitors reduce secretion of several ECM proteins, including collagens, fibrillin and fibronectin in human dermal fibroblasts and in cells obtained from patients with a generalized fibrotic disease (scleroderma). Taken together, targeted interference of the TANGO1-cTAGE5 binding interface could enable therapeutic modulation of ERES function in ECM hypersecretion, during wound healing and fibrotic processes.

Pla2g12b drives expansion of triglyceride-rich lipoproteins.

Vertebrates transport hydrophobic triglycerides through the circulatory system by packaging them within amphipathic particles called Triglyceride-Rich Lipoproteins. Yet, it remains largely unknown how triglycerides are loaded onto these particles. Mutations in Phospholipase A2 group 12B (PLA2G12B) are known to disrupt lipoprotein homeostasis, but its mechanistic role in this process remains unclear. Here we report that PLA2G12B channels lipids within the lumen of the endoplasmic reticulum into nascent lipoproteins. This activity promotes efficient lipid secretion while preventing excess accumulation of intracellular lipids. We characterize the functional domains, subcellular localization, and interacting partners of PLA2G12B, demonstrating that PLA2G12B is calcium-dependent and tightly associated with the membrane of the endoplasmic reticulum. We also detect profound resistance to atherosclerosis in PLA2G12B mutant mice, suggesting an evolutionary tradeoff between triglyceride transport and cardiovascular disease risk. Here we identify PLA2G12B as a key driver of triglyceride incorporation into vertebrate lipoproteins.

Sorting of secretory proteins at the trans-Golgi network by human TGN46.

Secretory proteins are sorted at the trans-Golgi network (TGN) for export into specific transport carriers. However, the molecular players involved in this fundamental process remain largely elusive. Here, we identified the human transmembrane protein TGN46 as a receptor for the export of secretory cargo protein PAUF in CARTS - a class of protein kinase D-dependent TGN-to-plasma membrane carriers. We show that TGN46 is necessary for cargo sorting and loading into nascent carriers at the TGN. By combining quantitative fluorescence microscopy and mutagenesis approaches, we further discovered that the lumenal domain of TGN46 encodes for its cargo sorting function. In summary, our results define a cellular function of TGN46 in sorting secretory proteins for export from the TGN.

Paravertebral and erector spinae plane blocks decrease length of stay compared with local infiltration analgesia in autologous breast reconstruction.

BACKGROUND: Autologous breast reconstruction is associated with significant pain impeding early recovery. Our objective was to evaluate the impact of replacing surgeon-administered local infiltration with preoperative paravertebral (PVB) and erector spinae plane (ESP) blocks for latissimus dorsi myocutaneous flap reconstruction. METHODS: Patients who underwent mastectomy with latissimus flap reconstruction from 2018 to 2022 were included in three groups: local infiltration, PVB, and ESP blocks. Block effect on postoperative length of stay (LOS) and the association between block status and pain, opioid consumption, time to first analgesic, and postoperative antiemetic administration were assessed. RESULTS: 122 patients met the inclusion criteria for this retrospective cohort study: no block (n=72), PVB (n=26), and ESP (n=24). On adjusted analysis, those who received a PVB block had a 20-hour shorter postoperative stay (95% CI 11 to 30; p<0.001); those who received ESP had a 24-hour (95% CI 15 to 34; p<0.001) shorter postoperative stay compared with the no block group, respectively. Using either block was associated with a reduction in intraoperative opioids (23 morphine milligram equivalents (MME)), 95% CI 14 to 31, p<0.001; ESP versus no block: 23 MME, 95% CI 14 to 32, p<0.001). CONCLUSIONS: Replacing surgical infiltration with PVB and ESP blocks for autologous breast reconstruction reduces LOS. The comparable reduction in LOS suggests that ESP may be a viable alternative to PVB in patients undergoing latissimus flap breast reconstruction following mastectomy. Further research should investigate whether ESP or PVB have better patient outcomes in complex breast reconstruction.

A model for collagen secretion by intercompartmental continuities.

Newly synthesized secretory proteins are exported from the endoplasmic reticulum (ER) at specialized subcompartments called exit sites (ERES). Cargoes like procollagen are too large for export by the standard COPII-coated vesicle of 60 nm average diameter. We have previously suggested that procollagen is transported from the ER to the next secretory organelle, the ER-Golgi intermediate compartment (ERGIC), in TANGO1-dependent interorganelle tunnels. In the theoretical model presented here, we suggest that intrinsically disordered domains of TANGO1 in the ER lumen induce an entropic contraction, which exerts a force that draws procollagen toward the ERES. Within this framework, molecular gradients of pH and/or HSP47 between the ER and ERGIC create a force in the order of tens of femto-Newtons. This force is substantial enough to propel procollagen from the ER at a speed of approximately 1 nm · s-1. This calculated speed and the quantities of collagen secreted are similar to its observed physiological secretion rate in fibroblasts, consistent with the proposal that ER export is the rate-limiting step for procollagen secretion. Hence, the mechanism we propose is theoretically adequate to explain how cells can utilize molecular gradients and export procollagens at a rate commensurate with physiological needs.

Tetraspanin-8 sequesters syntaxin-2 to control biphasic release propensity of mucin granules.

Agonist-mediated stimulated pathway of mucin and insulin release are biphasic in which rapid fusion of pre-docked granules is followed by slow docking and fusion of granules from the reserve pool. Here, based on a cell-culture system, we show that plasma membrane-located tetraspanin-8 sequesters syntaxin-2 to control mucin release. Tetraspanin-8 affects fusion of granules during the second phase of stimulated mucin release. The tetraspanin-8/syntaxin-2 complex does not contain VAMP-8, which functions with syntaxin-2 to mediate granule fusion. We suggest that by sequestering syntaxin-2, tetraspanin-8 prevents docking of granules from the reserve pool. In the absence of tetraspanin-8, more syntaxin-2 is available for docking and fusion of granules and thus doubles the quantities of mucins secreted. This principle also applies to insulin release and we suggest a cell type specific Tetraspanin/Syntaxin combination is a general mechanism regulating the fusion of dense core granules.

Defects in lipid homeostasis reflect the function of TANGO2 in phospholipid and neutral lipid metabolism.

We show that TANGO2 in mammalian cells localizes predominantly to mitochondria and partially at mitochondria sites juxtaposed to lipid droplets (LDs) and the endoplasmic reticulum. HepG2 cells and fibroblasts of patients lacking TANGO2 exhibit enlarged LDs. Quantitative lipidomics revealed a marked increase in lysophosphatidic acid (LPA) and a concomitant decrease in its biosynthetic precursor phosphatidic acid (PA). These changes were exacerbated in nutrient-starved cells. Based on our data, we suggest that TANGO2 function is linked to acyl-CoA metabolism, which is necessary for the acylation of LPA to generate PA. The defect in acyl-CoA availability impacts the metabolism of many other fatty acids, generates high levels of reactive oxygen species, and promotes lipid peroxidation. We suggest that the increased size of LDs is a combination of enrichment in peroxidized lipids and a defect in their catabolism. Our findings help explain the physiological consequence of mutations in TANGO2 that induce acute metabolic crises, including rhabdomyolysis, cardiomyopathy, and cardiac arrhythmias, often leading to fatality upon starvation and stress.

Sorting and Export of Proteins at the Endoplasmic Reticulum.

Secretory proteins are transported from the endoplasmic reticulum (ER) to the Golgi complex in carriers that are formed by the concerted activities of cytoplasmic proteins in the coat protein complex II (COPII). COPII was first described in Saccharomyces cerevisiae and its basic functions are largely conserved throughout eukaryotes. The discovery of the TANGO1 (transport and Golgi organization 1) family of proteins is revealing insights into how cells can adapt COPII proteins to reorganize the ER exit site for the export of the most abundant and bulky molecules, collagens.

Case report: Spontaneous remission of synchronous endometrial and ovarian cancers following pregnancy.

Introduction: Endometrial cancer is one of the most common malignancies affecting women. It is uncommonly diagnosed in young women, particularly in the absence of abnormal vaginal bleeding symptoms. Case presentation: A 28-year-old woman was referred to our department with lower abdominal pain. Transvaginal ultrasound showed a complex right adnexal mass with mixed echogenicity. Magnetic resonance imaging (MRI) identified a right-sided, torted, cystic solid ovarian mass, and a polypoid lesion in the uterine cavity. Diagnosis: Following multidisciplinary team advice, hysteroscopic transcervical resection of endometrial polypoid mass and laparoscopic right salpingo-oophorectomy was performed. Histopathologic assessment of the endometrial tissue showed changes consistent with grade 1 endometrioid endometrial carcinoma, while the right ovarian mass showed a well-differentiated endometrioid carcinoma. Intervention: The patient underwent hormonal treatment and surveillance whilst making a final decision regarding further surgical management. However, the patient stopped hormonal treatment after 2 weeks, went abroad and absconded from treatment for 8 months. On her return, she had conceived naturally and was in the first trimester of pregnancy. Further management was postponed until the patient was 7 weeks postnatal. The patient was not keen on any further surgical management and opted for close surveillance with ultrasound scans and hysteroscopies with endometrial biopsies. All subsequent endometrial biopsies showed normal endometrium, with no evidence of hyperplasia or malignancy. Outcome: To date, the patient remains on a 6-monthly surveillance plan and is considered to have had complete natural remission of her endometrial and ovarian cancers following pregnancy. Conclusion: This unique case demonstrates a natural phenomenon, in which the complete, natural remission of endometrial and ovarian cancers occurred following pregnancy and childbirth. The aetiology may be related to the high progesterone levels occurring in pregnancy.

Patient outcomes following implementation of an enhanced recovery after surgery pathway for patients with metastatic spine tumors.

BACKGROUND: Metastatic spine tumor surgery consists of palliative operations performed on frail patients with multiple medical comorbidities. Enhanced recovery after surgery (ERAS) programs involve an evidence-based, multidisciplinary approach to improve perioperative outcomes. This study presents clinical outcomes of a metastatic spine tumor ERAS pathway implemented at a tertiary cancer center. METHODS: The metastatic spine tumor ERAS program launched in April 2019, and data from January 2018 to May 2020 were reviewed. Measured outcomes included the following: hospital length of stay (LOS), time to ambulation, urinary catheter duration, time to resumption of diet, intraoperative fluid intake, estimated blood loss (EBL), and intraoperative and postoperative day 0-5 cumulative opioid use (morphine milligram equivalent [MME]). RESULTS: A total of 390 patients were included in the final analysis: 177 consecutive patients undergoing metastatic spine tumor surgery enrolled in the ERAS program and 213 consecutive pre-ERAS patients. Although the mean case durations were similar in the ERAS and pre-ERAS cohorts (265 vs. 274 min; p = .22), the ERAS cohort had decreased EBL (157 vs. 215 ml; p = .003), decreased postoperative day 0-5 cumulative mean opioid use (178 vs. 396 MME; p < .0001), earlier ambulation (mean, 34 vs. 57 h; p = .0001), earlier discontinuation of urinary catheters (mean, 36 vs. 56 h; p < .001), and shorter LOS (5.4 vs. 7.5 days; p < .0001). CONCLUSIONS: The implementation of a multidisciplinary ERAS program designed for metastatic spine tumor surgery led to improved clinical quality metrics, including shorter hospitalizations and significant reductions in opioid consumption.

The ulcerative colitis-associated gene FUT8 regulates the quantity and quality of secreted mucins.

Mucins are the main macrocomponents of the mucus layer that protects the digestive tract from pathogens. Fucosylation of mucins increases mucus viscoelasticity and its resistance to shear stress. These properties are altered in patients with ulcerative colitis (UC), which is marked by a chronic inflammation of the distal part of the colon. Here, we show that levels of Fucosyltransferase 8 (FUT8) and specific mucins are increased in the distal inflamed colon of UC patients. Recapitulating this FUT8 overexpression in mucin-producing HT29-18N2 colonic cell line increases delivery of MUC1 to the plasma membrane and extracellular release of MUC2 and MUC5AC. Mucins secreted by FUT8 overexpressing cells are more resistant to removal from the cell surface than mucins secreted by FUT8-depleted cells (FUT8 KD). FUT8 KD causes intracellular accumulation of MUC1 and alters the ratio of secreted MUC2 to MUC5AC. These data fit well with the Fut8-/- mice phenotype, which are protected from UC. Fut8-/- mice exhibit a thinner proximal colon mucus layer with an altered ratio of neutral to acidic mucins. Together, our data reveal that FUT8 modifies the biophysical properties of mucus by controlling levels of cell surface MUC1 and quantity and quality of secreted MUC2 and MUC5AC. We suggest that these changes in mucus viscoelasticity likely facilitate bacterial-epithelial interactions leading to inflammation and UC progression.

A case of spinal melorheostosis.

Melorheostosis is a rare bone dysplasia of unknown etiology with an incidence of 0.9 cases per million. It typically affects the upper or lower limbs and can cause severe deformity and functional impairment. Diagnosis is radiological and is often described as a "flowing candle wax" appearance on the radiograph. Treatment is individualized depending on the site and severity of symptoms. We report a rare case of spinal melorheostosis. We demonstrate the imaging features of melorheostosis on CT and MRI. We discuss the classification, genetics, and management of this condition.

Reversing chemorefraction in colorectal cancer cells by controlling mucin secretion.

Fifteen percent of colorectal cancer (CRC) cells exhibit a mucin hypersecretory phenotype, which is suggested to provide resistance to immune surveillance and chemotherapy. We now formally show that CRC cells build a barrier to chemotherapeutics by increasing mucins' secretion. We show that low levels of KChIP3, a negative regulator of mucin secretion (Cantero-Recasens et al., 2018), is a risk factor for CRC patients' relapse in a subset of untreated tumours. Our results also reveal that cells depleted of KChIP3 are four times more resistant (measured as cell viability and DNA damage) to chemotherapeutics 5-fluorouracil + irinotecan (5-FU+iri.) compared to control cells, whereas KChIP3-overexpressing cells are 10 times more sensitive to killing by chemotherapeutics. A similar increase in tumour cell death is observed upon chemical inhibition of mucin secretion by the sodium/calcium exchanger (NCX) blockers (Mitrovic et al., 2013). Finally, sensitivity of CRC patient-derived organoids to 5-FU+iri. increases 40-fold upon mucin secretion inhibition. Reducing mucin secretion thus provides a means to control chemoresistance of mucinous CRC cells and other mucinous tumours.

TANGO1 marshals the early secretory pathway for cargo export.

TANGO1 protein facilitates the endoplasmic reticulum (ER) export of large cargoes that cannot be accommodated in 60 nm transport vesicles. It assembles into a ring in the plane of the ER membrane to create a distinct domain. Its lumenal portion collects and sorts folded cargoes while its cytoplasmic domains collar COPII coats, recruit retrograde COPI-coated membranes that fuse within the TANGO1 ring, thus opening a tunnel for cargo transfer from the ER into a growing export conduit. This mode of cargo transfer bypasses the need for vesicular intermediates and is used to export the most abundant and bulky cargoes. The evolution of TANGO1 and its activities defines the difference between yeast and animal early secretory pathways.