Site-specific protein modification using immobilized sortase in batch and continuous-flow systems

Transpeptidation catalyzed by ​sortase A allows the preparation of proteins that are site-specifically and homogeneously modified with a wide variety of functional groups, such as fluorophores, PEG moieties, lipids, glycans, bio-orthogonal reactive groups and affinity handles. This protocol describes immobilization of ​sortase A on a solid support (Sepharose beads). Immobilization of ​sortase A simplifies downstream purification of a protein of interest after labeling of its N or C terminus. Smaller batch and larger-scale continuous-flow reactions require only a limited amount of enzyme. The immobilized enzyme can be reused for multiple cycles of protein modification reactions. The described protocol also works with a Ca²⁺-independent variant of ​sortase A with increased catalytic activity. This heptamutant variant of ​sortase A (7M) was generated by combining previously published mutations, and this immobilized enzyme can be used for the modification of calcium-senstive substrates or in instances in which low temperatures are needed. Preparation of immobilized ​sortase A takes 1–2 d. Batch reactions take 3–12 h and flow reactions proceed at 0.5 ml h⁻¹, depending on the geometry of the reactor used.United States. National Institutes of Health (RO1 AI087879

Positive Pre-cystectomy Biopsies of the Prostatic Urethra or Bladder Neck Do Not Necessarily Preclude Orthotopic Bladder Substitution.

We investigated the influence of positive pre-cystectomy biopsies of the prostatic urethra in males and the bladder neck in females on urethral recurrence, cancer specific and overall survival, and functional outcomes after orthotopic bladder substitution. We retrospectively analyzed the records of 803 consecutive patients, including 703 males and 100 females, who underwent orthotopic bladder substitution as well as pre-cystectomy biopsy of the prostatic urethra in males and the bladder neck in females, at our institution between April 1986 and December 2017. Pre-cystectomy biopsies were negative in 755 of the 803 patients (94%) (group 1) and positive in 48 (6%) (group 2). Biopsies in group 2 revealed carcinoma in situ in 35 of the 48 cases (73%), pTaG1/G2 in 5 (10%) and pTaG3/pT1G3 in 8 (17%). Median followup was 64 months (IQR 21-128). At a median followup of 56 months (IQR 18-127) urethral recurrence developed in 45 of the 803 patients (5.6%), including 30 of the 755 (4%) in group 1 and 15 of the 48 (31.3%) in group 2 (p <0.001). Only 10 of the 45 patients (22%) with urethral recurrence required salvage urethrectomy while locally conservative treatment was successful in 27 (60%). Of the remaining 8 patients 6 of 45 (13%) underwent synchronous palliative chemotherapy and 2 of 45 (4%) refused treatment. Multivariate regression analysis revealed a higher risk of urethral recurrence if patients had positive pre-cystectomy biopsies (group 2 HR 6.49, 95% CI 3.33-12.62, p <0.001) or received neoadjuvant or adjuvant chemotherapy (HR 3.05, 95% CI 1.66-5.59, p <0.001). Cancer specific and overall survival as well as functional outcomes were similar in the 2 groups. Positive pre-cystectomy biopsies prior to orthotopic bladder substitution increased the urethral recurrence rate but did not lower cancer specific or overall survival. Most urethral recurrences were managed successfully by local treatment. Orthotopic bladder substitution is an option in highly selected patients with positive, noninvasive pre-cystectomy biopsies, provided that they undergo regular followup including urethral cytology

The growing impact of micro/nanomaterial-based systems in precision oncology: translating “multiomics” technologies

The field of precision oncology is rapidly progressing toward integrated “multiomics” analysis of multiple molecular species (such as DNA, RNA, or proteins) to provide a more complete profile of tumor heterogeneity. Micro/nanomaterial-based systems, which leverage the unique properties of miniature materials, are currently well positioned to expand beyond rudimentary biomarker detection toward multiomics signature analysis. To enable clinical translation, the rational design and implementation of miniaturized systems should be driven by the unique clinical challenges present at various crucial cancer stages. This review features micro/nanomaterial-based systems that are robustly tested on real patient samples for molecular biomarker detection at i) initial cancer screening and/or diagnosis, ii) cancer prognosis and risk stratification, and iii) longitudinal treatment/recurrence monitoring. Furthermore, this review discusses the use of micro/nanomaterials to facilitate sample preparation for different molecular biomarker species. Finally, this review deliberates on the recent paradigm shift of micro/nanomaterial-based system innovation toward integrated multiomics cancer signature analysis and puts forth insights and perspectives on existing challenges. It is anticipated that this review could stimulate the propagation of new concepts and approaches to kick-start a new generation of clinically translational technologies that capitalize on multiomics cancer signatures

Recent advances in enhancing the sensitivity of electrophoresis and electrochromatography in capillaries and microchips (2014–2016)

One of the most cited limitations of capillary (and microchip) electrophoresis is the poor sensitivity. This review continues to update this series of biennial reviews, first published in Electrophoresis in 2007, on developments in the field of on‐line/in‐line concentration methods in capillaries and microchips, covering the period July 2014–June 2016. It includes developments in the field of stacking, covering all methods from field amplified sample stacking and large volume sample stacking, through to isotachophoresis, dynamic pH junction, and sweeping. Attention is also given to on‐line or in‐line extraction methods that have been used for electrophoresis