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Artificial intelligence (AI) is rapidly moving from an experimental phase to an implementation phase in many fields, including medicine. The combination of improved availability of large datasets, increasing computing power, and advances in learning algorithms has created major performance breakthroughs in the development of AI applications. In the last 5 years, AI techniques known as deep learning have delivered rapidly improving performance in image recognition, caption generation, and speech recognition. Radiology, in particular, is a prime candidate for early adoption of these techniques. It is anticipated that the implementation of AI in radiology over the next decade will significantly improve the quality, value, and depth of radiology's contribution to patient care and population health, and will revolutionize radiologists' workflows. The Canadian Association of Radiologists (CAR) is the national voice of radiology committed to promoting the highest standards in patient-centered imaging, lifelong learning, and research. The CAR has created an AI working group with the mandate to discuss and deliberate on practice, policy, and patient care issues related to the introduction and implementation of AI in imaging. This white paper provides recommendations for the CAR derived from deliberations between members of the AI working group. This white paper on AI in radiology will inform CAR members and policymakers on key terminology, educational needs of members, research and development, partnerships, potential clinical applications, implementation, structure and governance, role of radiologists, and potential impact of AI on radiology in Canada.

The fortuitously discovered antiaging membrane protein αKlotho (Klotho) is highly expressed in the kidney, and deletion of the Klotho gene in mice causes a phenotype strikingly similar to that of chronic kidney disease (CKD). Klotho functions as a co-receptor for fibroblast growth factor 23 (FGF23) signaling, whereas its shed extracellular domain, soluble Klotho (sKlotho), carrying glycosidase activity, is a humoral factor that regulates renal health. Low sKlotho in CKD is associated with disease progression, and sKlotho supplementation has emerged as a potential therapeutic strategy for managing CKD. Here, we explored the structure-function relationship and post-translational modifications of sKlotho variants to guide the future design of sKlotho-based therapeutics. Chinese hamster ovary (CHO)- and human embryonic kidney (HEK)-derived WT sKlotho proteins had varied activities in FGF23 co-receptor and β-glucuronidase assays in vitro and distinct properties in vivo. Sialidase treatment of heavily sialylated CHO-sKlotho increased its co-receptor activity 3-fold, yet it remained less active than hyposialylated HEK-sKlotho. MS and glycopeptide-mapping analyses revealed that HEK-sKlotho is uniquely modified with an unusual N-glycan structure consisting of N,N′-di-N-acetyllactose diamine at multiple N-linked sites, one of which at Asn-126 was adjacent to a putative GalNAc transfer motif. Site-directed mutagenesis and structural modeling analyses directly implicated N-glycans in Klotho's protein folding and function. Moreover, the introduction of two catalytic glutamate residues conserved across glycosidases into sKlotho enhanced its glucuronidase activity but decreased its FGF23 co-receptor activity, suggesting that these two functions might be structurally divergent. These findings open up opportunities for rational engineering of pharmacologically enhanced sKlotho therapeutics for managing kidney disease.

Advancement in high-throughput screening methods of novel therapeutic proteins for early stage research and development, specifically mAbs, have given mid-scale (milligram to gram scale) purification groups access to more of these molecules. The available purification technologies built to support mid-scale production was not efficient or versatile enough to keep up with this surge. To remedy this problem, we have designed and built a custom instrument using an AKTA Pure. This system enables parallel processing up to 5 samples and has the versatility to perform 1- to 3-step purification processes in a single queue. Furthermore, a unique purification scheme can be selected for each of the five samples in the queue. Overall processing time has reduced by 83% compared to manual, non-parallel load methods. Here, we describe our novel approach and demonstrate the flexibility, speed and efficiency of the instrument.

Protein modifications by intricate cellular machineries often redesign the structure and function of existing proteins to impact biological networks. Disulfide bond formation between cysteine (Cys) pairs is one of the most common modifications found in extracellularly-destined proteins, key to maintaining protein structure. Unpaired surface cysteines on secreted mammalian proteins are also frequently found disulfide-bonded with free Cys or glutathione (GSH) in circulation or culture, the mechanism for which remains unknown. Here we report that these so-called Cys-capping modifications take place outside mammalian cells, not in the endoplasmic reticulum (ER) where oxidoreductase-mediated protein disulfide formation occurs. Unpaired surface cysteines of extracellularly-arrived proteins such as antibodies are uncapped upon secretion before undergoing disulfide exchange with cystine or oxidized GSH in culture medium. This observation has led to a feasible way to selectively modify the nucleophilic thiol side-chain of cell-surface or extracellular proteins in live mammalian cells, by applying electrophiles with a chemical handle directly into culture medium. These findings provide potentially an effective approach for improving therapeutic conjugates and probing biological systems.

Purpose The authors report on the use of Palmaz balloon-expandable intraluminal metallic stents to supplement conventional balloon angioplasty and to primarily treat a variety of supra-aortic arterial atherosclerotic lesions manifested by claudication or embolic phenomena. Patients and Methods Results from a series of seven patients are reported. Five patients received stents following percutaneous balloon angioplasty (PTA): four patients received five stents for suboptimal initial result of PTA and one patient received one stent for early restenosis following successful PTA. Two patients received three stents primarily: one patient had one stent placed for a highly eccentric innominate lesion and the other patient had two stents placed for an ulcerated nonocclusive subclavian lesion causing blue digits. Results Treatment produced immediate angiographic or hemodynamic improvement in all seven patients. Clinical follow-up was obtained on all patients (mean, 10 months; range, 3–18 months). One patient had an episode of vertigo after PTA of a right subclavian lesion that resolved after thrombolytic therapy and stent placement. Conclusion The placement of metallic stents in supra-aortic arteries represented an effective adjunct to PTA of atherosclerotic stenoses in these vessels. Primary stent placement may be an effective treatment for selected lesions.

[1] Lian K, Trollip J, Sandhu S, et al. Audit of atypical femoral fracture and a description of some of their features. Can Assoc Radiol J 2015;67:69e75. [2] Shane E, Burr D, Abrahamsen B, et al. Atypical subtrochanteric and diaphyseal femoral fractures: second report of a task force of the American Society for Bone and Mineral Research. J Bone Miner Res 2014;29:1e23. [3] Probyn L, Cheung AM, Lang C, et al. Bilateral atypical femoral fractures: how much symmetry is there on imaging? Skeletal Radiol 2015; 44:1579e84. [4] Khan AA, Leslie WD, Lentle B, et al. Atypical femoral fractures: a teaching perspective. Can Assoc Radiol J 2015;66:102e7. [5] Khan AA, Fortier M, Menopause and Osteoporosis Working Group, et al. Osteoporosis in menopause. J Obstet Gynaecol Can 2014;36: 839e40.

Site-specific conjugation of toxic payload to antibody yields homogeneous ADCs resulting in improved therapeutic index over conventional conjugation. To understand the role of conjugation site on pharmacokinetics, off-target toxicity, cysteine(cys) was engineered into a humanized anti-IL13Rα2 antibody, hAB08, at various sites within the IgG1/k constant domains. Single cys mutants L443C and Q347C with DAR 2, and double cys mutants K392C+L443C, L443C/kK183C and Q347C/kK183C with DAR 4 were conjugated using auristatin 0101 via maleimidocapronic - valine-citruline-p-aminobenzyloxycarbonyl (vc, cleavable linker). All cys mutants and their conjugates maintained their binding properties compared to parental hAb08. Cysteine substitution sites were selected based on conjugation efficiency and in vitro stability. In vivo efficacy was evaluated in mouse xenograph tumor models. Pharmacokinetics (PK) and off target toxicity (TOX) were assessed in both mouse and rat in vivo studies. Our data demonstrate that that all site specific conjugates show improved in vitro stability, comparable or better in vivo efficacy in mice xenograph models and in vivo stability (ratio of ADC-AUC/Ab-AUC) compared to conventional conjugates. However PK and off-target toxicity of antibody drug conjugates had been significantly impacted by conjugation site and animal species. L443 mutants show higher ADC-AUC, lower clearance and longer half life than Q347 mutants in mice while a reverse TK behavior was observed in rat. All site specific conjugates show higher dose tolerance and less off-target toxicity relative to conventional conjugates in rat. This off-target toxicity improvement depends on sites of conjugation. The L443 mutants exhibited a better off-target TOX profile relative to Q347 mutants. Taken together, site-specific conjugation improved in vivo efficacy and off-target toxicity relative to conventionally conjugated ADC. PK differences and off-target toxicity improvements depend on conjugation sites and animal species. Note: This abstract was not presented at the meeting. Citation Format: Dangshe Ma, Fang Jin, Frank Barletta, George Hu, Nathan Tumey, Haige Zhang, Tao He, Eric Sousa, Manoj Charti, Kiran Khadke, Judy Lucas, Darren Ferguson, Christoper Brown, Weijun Ma, Scott Gatto, William Brady, Edmund Graziani, Hans-Peter Gerber, Puja Sapra, Lioudmila Tchistikova. Impact of conjugation site on pharmacokinetics and off-target toxicity of site-specific antibody drug conjugates. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 644. doi:10.1158/1538-7445.AM2015-644

Purpose To retrospectively review and to report the results of stent placement for focal mid-abdominal aortic stenoses. Materials and Methods During a 4-year period, 10 focal mid-abdominal aortic stenoses were treated with stent placement in nine patients (six women and three men; mean age, 61 years; range, 49–73 years). All of the stenoses were atherosclerotic in nature except for one at the proximal anastomosis of an aortobifemoral graft, which may have been from fibrointimal hyperplasia. Seven of the 10 stenoses were treated with primary stent placement, whereas three were treated with stent placement after sub-optimal angioplasty. Results The technical success rate was 100%. Clinical success, defined as complete elimination or improvement of symptoms present before stent placement, was achieved in eight of the nine patients with a mean duration of follow-up of 1.6 years (range, 0.2–3.0 years). Conclusion In view of the excellent technical and clinical success, the authors believe that stent placement should be considered as an adjunctive therapy to angioplasty or as a primary method of treatment in properly selected patients with focal mid-abdominal aortic stenoses.