Vps34 Kinase Domain Dynamics Regulate the Autophagic PI 3-Kinase Complex.

The class III phosphatidylinositol 3-kinase complex I (PI3KC3-C1) is required for the initiation of essentially all macroautophagic processes. PI3KC3-C1 consists of the lipid kinase catalytic subunit VPS34, the VPS15 scaffold, and the regulatory BECN1 and ATG14 subunits. The VPS34 catalytic domain and BECN1:ATG14 subcomplex do not touch, and it is unclear how allosteric signals are transmitted to VPS34. We used EM and crosslinking mass spectrometry to dissect five conformational substates of the complex, including one in which the VPS34 catalytic domain is dislodged from the complex but remains tethered by an intrinsically disordered linker. A "leashed" construct prevented dislodging without interfering with the other conformations, blocked enzyme activity in vitro, and blocked autophagy induction in yeast cells. This pinpoints the dislodging and tethering of the VPS34 catalytic domain, and its regulation by VPS15, as a master allosteric switch in autophagy induction.

Can remote endarterectomy expand access to kidney transplantation in patients with severe iliac calcification?

Severe iliac artery calcification in patients with end-stage renal disease is a common barrier to listing for kidney transplant. While few surgical solutions to iliac calcification have been reported, improving treatment may thus improve access to transplant care. Here we present two cases of a novel application of remote endarterectomy of the external iliac artery to facilitate listing for renal transplant. Both patients were listed following remote endarterectomy, followed by successful renal transplants using the treated vessels.

Artificial Intelligence Enables Quantitative Assessment of Ulcerative Colitis Histology.

Ulcerative colitis is a chronic inflammatory bowel disease that is characterized by a relapsing and remitting course. Assessment of disease activity critically informs treatment decisions. In addition to endoscopic remission, histologic remission is emerging as a treatment target and a key factor in the evaluation of disease activity and therapeutic efficacy. However, manual pathologist evaluation is semiquantitative and limited in granularity. Machine learning approaches are increasingly being developed to aid pathologists in accurate and reproducible scoring of histology, enabling precise quantitation of clinically relevant features. Here, we report the development and validation of convolutional neural network models that quantify histologic features pertinent to ulcerative colitis disease activity, directly from hematoxylin and eosin-stained whole slide images. Tissue and cell model predictions were used to generate quantitative human-interpretable features to fully characterize the histology samples. Tissue and cell predictions showed comparable agreement to pathologist annotations, and the extracted slide-level human-interpretable features demonstrated strong correlations with disease severity and pathologist-assigned Nancy histological index scores. Moreover, using a random forest classifier based on 13 human-interpretable features derived from the tissue and cell models, we were able to accurately predict Nancy histological index scores, with a weighted kappa (κ = 0.91) and Spearman correlation (⍴ = 0.89, P < .001) when compared with pathologist consensus Nancy histological index scores. We were also able to predict histologic remission, based on the absence of neutrophil extravasation, with a high accuracy of 0.97. This work demonstrates the potential of computer vision to enable a standardized and robust assessment of ulcerative colitis histopathology for translational research and improved evaluation of disease activity and prognosis.

Wound Closure with Transcutaneous Absorbable Polyglactin Sutures after Hidradenitis Suppurativa Excision.

OBJECTIVE: Wide surgical excision is the standard treatment for severe hidradenitis suppurativa (HS). Because of the nature of HS, these wounds are often nonsterile, located in moist intertriginous regions, and closed under tension, increasing the risk for surgical site complications. Although uncommon, absorbable sutures may confer benefits over nonabsorbable material for skin closure. Accordingly, the authors evaluated the use of absorbable, braided, transcutaneous polyglactin sutures after wide surgical excision of HS. METHODS: The authors performed a retrospective chart review for all consecutive patients who underwent wide surgical excision of HS at a tertiary university hospital between January 2009 and March 2020. RESULTS: Sixty consecutive patients with 174 operative sites were included in the study. The surgical site complication rate was 17.8%. Postoperative complications included wound dehiscence (n = 18), surgical site infection (n = 2), and scar contracture (n = 1). Sutures were removed from 12 (6.9%) operative sites. Factors influencing complications were Hurley grade and area of excision. Complications did not differ significantly among disease locations (P = .6417). CONCLUSIONS: The results support the growing evidence that absorbable sutures are an appropriate option after wide surgical excision of HS.

Spontaneous Thrombosis of an Isolated Internal Iliac Artery Aneurysm.

BACKGROUND: Isolated internal iliac artery aneurysms (IIAAs) are uncommon but potentially morbid lesions that are a challenge to monitor and treat. However, given the small numbers of reported cases and high rates of incidentally discovered lesions, the natural history of isolated IIAAs is not well characterized. This case describes an atypical and previously unreported spontaneous thrombosis of an isolated IIAA, a lesion typically thought to progressively enlarge and rupture. METHODS: Medical records and imaging studies were retrospectively reviewed with the approval of our Institutional Review Board. A single patient underwent fluoroscopic angiography followed by computed tomography (CT) angiography, with no subsequent operative intervention. RESULTS: An isolated 5.5 cm left IIAA was discovered incidentally on CT scan and subsequently seen with fluoroscopic pelvic angiography. Three weeks following initial angiography, repeat pelvic angiography and CT scan demonstrated spontaneous thrombosis of the aneurysm. CONCLUSIONS: Isolated IIAAs are conditions for which the natural history remains uncertain despite their potential risk for rupture and mortality. Spontaneous thrombosis of these lesions is possible, suggesting that the natural history as previously described warrants further consideration.

Autogenous Femoral Vein for Secondary Repair of Subclavian Arteries: A Salvage Solution for Complex Clinical Scenarios.

BACKGROUND: Endovascular stent and prosthetic graft placement are commonplace techniques for correction of subclavian artery (SCA) lesions. However, when initial surgical repair of the SCA becomes complicated by subsequent infection or thrombosis of the repair site, stents and prosthetic grafts are no longer suitable for secondary repair due to the risk of recurrent failure and limited longevity. Autogenous tissue is more resistant to infection and has improved long-term patency, and thus may be a better option for secondary reconstruction in these complex clinical scenarios. The most commonly used autogenous conduit for SCA reconstruction is the great saphenous vein; however, the significant size mismatch makes this unsuitable in many circumstances. The autogenous femoral vein is a promising alternative conduit for SCA repair. Here we present 3 successful cases of its use as a salvage technique following iatrogenic complications of prior surgical repair. METHODS: From 2015 to 2019, 3 patients underwent harvest of the femoral vein for use in SCA repair, with 2 carotid-axillary bypasses and 1 carotid-subclavian bypass. Indications included a mycotic pseudoaneurysm secondary to an infected SCA stent, an SCA avulsion secondary to an infected carotid-subclavian bypass graft, and an occluded SCA stent in a young patient. Postoperative graft patency was monitored via clinical resolution of symptoms and maintenance of perfusion, intact pulses, and arterial duplex or computed tomography (CT) scan. RESULTS: All these patients had a good outcome following their procedures. Each had intact radial pulses immediately postoperatively and maintained normal perfusion to the upper extremity for the duration of follow-up, with bypass patency confirmed via CT scan or arterial duplex. The SCA repair also allowed for salvage of the upper extremity and symptomatic relief in all patients. None of the patients developed deep vein thrombosis in the donor extremity, and neither of the infected patients developed recurrent infection of the repair site. CONCLUSIONS: The success of these cases demonstrates that the autogenous femoral vein is an effective and safe option for SCA reconstruction. It is particularly useful for secondary salvage when prior surgical repair via standard techniques is complicated by infection or thrombosis, and when target vessel size precludes the use of the great saphenous vein. This is an excellent choice of conduit that vascular surgeons should consider for use in complex SCA repairs.

Type B Aortic Dissection Complicated by Intimo-Intimal Intussusception and Extensive Intimal Denuding: Case Report with Long-term Follow-up.

BACKGROUND: Acute aortic dissection rarely results in circumferential dissections of the aortic intima that may lead to intimo-intimal intussusception (IIS) with complete separation from the aortic wall. Circumferential dissection may then result in distal embolization of the involved intima and media, adding considerable complexity to the management of such cases. Despite the severity of this complication, the natural history of aortic disease following extensive intimal denuding and IIS is not well documented in the literature. Here we present a case with long-term follow-up of type B aortic dissection (TBAD) complicated by IIS and embolization of the intima into the distal aorta following thoracic endovascular aortic repair. METHODS: Medical records and imaging studies were retrospectively reviewed with the approval of the Institutional Review Board. A single patient underwent repair of a TBAD that was complicated by IIS, with follow-up for 6 years. Aortic recovery was monitored with serial computerized tomography scans. RESULTS: During endovascular stent deployment, the patient's dissection progressed circumferentially, leading to distal embolization of the intima and aortic occlusion. An open transabdominal aortic exploration was performed to extract the embolized intima. Despite this severe aortic structural disruption, the patient recovered well postoperatively and exhibited favorable aortic remodeling over long-term follow-up. The denuded aorta did not rupture or develop progressive worsening aneurysmal dilation and the diameter of the involved aortic segment remained stable during follow-up. CONCLUSIONS: Acute TBADs can progress to circumferential intimal separation and IIS when managed with endovascular stenting and balloon dilation. Continued endovascular management once IIS has occurred may lead to further intimal damage, resulting in distal embolization of the intima and aortic occlusion. Thus, IIS may require conversion to open repair. However, in the event that loss of the aortic intima does occur following IIS, it is possible for the denuded aorta to recover well and remain stable with favorable remodeling over long-term follow-up.

Autophagy promotes primary ciliogenesis by removing OFD1 from centriolar satellites.

The primary cilium is a microtubule-based organelle that functions in sensory and signalling pathways. Defects in ciliogenesis can lead to a group of genetic syndromes known as ciliopathies. However, the regulatory mechanisms of primary ciliogenesis in normal and cancer cells are incompletely understood. Here we demonstrate that autophagic degradation of a ciliopathy protein, OFD1 (oral-facial-digital syndrome 1), at centriolar satellites promotes primary cilium biogenesis. Autophagy is a catabolic pathway in which cytosol, damaged organelles and protein aggregates are engulfed in autophagosomes and delivered to lysosomes for destruction. We show that the population of OFD1 at the centriolar satellites is rapidly degraded by autophagy upon serum starvation. In autophagy-deficient Atg5 or Atg3 null mouse embryonic fibroblasts, OFD1 accumulates at centriolar satellites, leading to fewer and shorter primary cilia and a defective recruitment of BBS4 (Bardet-Biedl syndrome 4) to cilia. These defects are fully rescued by OFD1 partial knockdown that reduces the population of OFD1 at centriolar satellites. More strikingly, OFD1 depletion at centriolar satellites promotes cilia formation in both cycling cells and transformed breast cancer MCF7 cells that normally do not form cilia. This work reveals that removal of OFD1 by autophagy at centriolar satellites represents a general mechanism to promote ciliogenesis in mammalian cells. These findings define a newly recognized role of autophagy in organelle biogenesis.

Scaffolding the cup-shaped double membrane in autophagy.

Autophagy is a physiological process for the recycling and degradation of cellular materials. Forming the autophagosome from the phagophore, a cup-shaped double-membrane vesicle, is a critical step in autophagy. The origin of the cup shape of the phagophore is poorly understood. In yeast, fusion of a small number of Atg9-containing vesicles is considered a key step in autophagosome biogenesis, aided by Atg1 complexes (ULK1 in mammals) localized at the preautophagosomal structure (PAS). In particular, the S-shaped Atg17-Atg31-Atg29 subcomplex of Atg1 is critical for phagophore nucleation at the PAS. To study this process, we simulated membrane remodeling processes in the presence and absence of membrane associated Atg17. We show that at least three vesicles need to fuse to induce the phagophore shape, consistent with experimental observations. However, fusion alone is not sufficient. Interactions with 34-nm long, S-shaped Atg17 complexes are required to overcome a substantial kinetic barrier in the transition to the cup-shaped phagophore. Our finding rationalizes the recruitment of Atg17 complexes to the yeast PAS, and their unusual shape. In control simulations without Atg17, with weakly binding Atg17, or with straight instead of S-shaped Atg17, the membrane shape transition did not occur. We confirm the critical role of Atg17-membrane interactions experimentally by showing that mutations of putative membrane interaction sites result in reduction or loss of autophagic activity in yeast. Fusion of a small number of vesicles followed by Atg17-guided membrane shape-remodeling thus emerges as a viable route to phagophore formation.

A composite risk assessment model for venous thromboembolism.

OBJECTIVE: Venous thromboembolism (VTE) is a preventable cause of hospitalization-related morbidity and mortality. VTE prevention requires accurate risk-stratification. Federal agencies mandated VTE risk-assessment for all hospital admissions. We have shown that the widely used Caprini (30 risk-factors) and Padua (11 risk-factors) VTE risk-assessment models (RAMs) have limited predictive ability for VTE when used for all general hospital admissions. Here we test whether combining the risk-factors from all 23 available VTE RAMs improves VTE risk-prediction. METHODS: We analyzed data from the first hospitalizations of 1,282,014 surgical and non-surgical patients admitted to 1,298 Veterans Affairs facilities nationwide between January 2016 and December 2021. We used logistic regression to predict VTE within 90 days of admission using risk-factors from all 23 available VTE RAMs. Area under the receiver-operating characteristic curves (AUC), sensitivity, specificity, positive (PPV) and negative predictive values (NPV) were used to quantify the predictive power of our models. The metrics were computed at two diagnostic thresholds that maximized 1) the value of sensitivity + specificity-1 and 2) PPV, and were compared using McNemar's test. The Delong-Delong test was used to compare AUCs. RESULTS: After excluding those with missing data, 1,185,633 patients (mean age 66 years, 93% male, and 72% white) were analyzed, of whom 33,253 (2.8%) had a VTE (DVT [deep venous thrombosis], n=19,218, 1.6%; PE [pulmonary embolism], n=10,190, 0.9%; PE+DVT, n=3,845, 0.3%). Our composite RAM included 102 risk-factors and improved prediction of VTE compared to the Caprini RAM risk-factors (AUC Composite model: 0.74; AUC Caprini risk-factor model: 0.63; p<0.0001). When the sum of sensitivity and specificity-1 was maximized, the composite model demonstrated small improvements in sensitivity, specificity and PPV; NPV was high in both models. When PPV was maximized, the PPV of the composite model was improved but remained low. The nature of the relationship between NPV and PPV precluded any further gain in PPV by sacrificing NPV and sensitivity. CONCLUSIONS: Using a composite of 102 risk-factors from all available VTE RAMs, we improved VTE prediction in a large, national cohort of >1 million general hospital admissions. However, neither model has a sensitivity or PPV that permits it to be a reliable predictor of VTE. We demonstrate the limits of currently available VTE risk prediction tools; no available RAM is ready for widespread use in the general hospital population.