The hierarchical assembly of a multi-level DNA ring-based nanostructure in a precise order and its application for screening tumor cells.

DNA nanotechnology can be used to precisely construct nanostructures of different shapes, sizes and surface chemistry, which is appreciated in a variety of areas such as biomaterials, nanodevices, disease diagnosis, imaging, and drug delivery. Enzymatic degradation resistance and cell-targeting capability are indispensable for the applications of DNA nanostructures in biological and biomedical fields, and is challenging to rationally design the desirable nanoscale DNA materials suitable for the clinical translation by the existing assembly methodologies. Herein, we present a simple and efficient method for the hierarchical assembly of a three-level DNA ring-based nanostructure (DNA h-Nanoring) in a precise order, where DNA compositions at the primary level, the second level and the third level are a single DNA ring, two-ring-hybridized duplex and uniform complex macro-cycle, respectively. Most as-assembled DNA h-Nanorings exhibit the regular two-dimensional cycle-shaped structure characterized by atomic force microscopy (AFM). The Nanoring exhibits a significantly enhanced resistance to enzymatic attack, such that it can remain intact in 10% fetal bovine serum (FBS) for 24 h, and even stably exist in the presence of nuclease at a high concentration. More importantly, it is very easy to modify the DNA h-Nanoring with functional moieties (e.g., targeting ligand aptamer) because there are many single-stranded fragments available for further hybridization. By combining with receptor-targeted Sgc8, the nanoring can be used to accomplish the cell imaging and criminate target CEM cells from control cells, demonstrating a potential platform for in vivo tumor imaging and targeted chemotherapeutics delivery.

Tibiofemoral Contact Mechanics After Horizontal or Ripstop Suture in Inside-Out and Transtibial Repair for Meniscus Radial Tears in a Porcine Model.

PURPOSE: To compare tibiofemoral contact mechanics after horizontal or ripstop (horizontal plus vertical) sutures in inside-out and transtibial repair for meniscal radial tears with 10 porcine knees in each group. METHODS: Ten matched pairs of porcine knees were tested under a 1500-N axial compressive load at 0°, 30°, 60°, and 90° of knee flexion. Each knee underwent 4 testing conditions consecutively: (1) intact, (2) medial meniscal radial tear, (3) horizontal suture repair configuration, and (4) ripstop suture repair configuration. Tekscan sensors measured tibiofemoral contact pressure and contact area in the medial and lateral compartments. RESULTS: All repair groups improved their contact mechanics when compared with the tear state among all flexion angles analyzed (all P < .05). Furthermore, ripstop sutures with both inside-out and transtibial repairs restored intact knee contact area and pressures (peak and mean) in the medial compartment at all flexion angles, whereas the horizontal sutures alone failed to do so for contact pressures at 60° and 90° and for contact surface areas at all flexion angles. However, the aforementioned parameters were not significantly different between inside-out sutures and transtibial sutures, regardless of horizontal or ripstop configuration (P > .05). CONCLUSIONS: Radial tears of the meniscus in a porcine model significantly decreased medial contact area and increased mean and peak contact pressure. Both inside-out and transtibial ripstop repairs for radial tears aid in restoring intact tibiofemoral contact mechanics at all assessed knee flexion angles. CLINICAL RELEVANCE: Our results suggest that both inside-out and transtibial ripstop repairs for radial tears can restore tibiofemoral contact mechanics to the intact state. Since the study were performed in an open fashion porcine model, the results should be carefully used in clinical practices, and the efficacy of the techniques through arthroscopic method should be further explored.

Intracellular Nonenzymatic In Situ Growth of Three-Dimensional DNA Nanostructures for Imaging Specific Biomolecules in Living Cells.

Real-time in situ monitoring of low-abundance cancer biomarkers (e.g., miRNAs and proteins) in living cells by nonenzymatic assembly entirely from original DNA probes remains unexplored due to an extremely complex intracellular environment. Herein, a nonenzymatic palindrome-catalyzed DNA assembly (NEPA) technique is developed to execute the in situ imaging of intracellular miRNAs by assembling a three-dimensional nanoscale DNA spherical structure (NS) with low mobility from three free hairpin-type DNAs rather than from DNA intermediates based on the interaction of designed terminal palindromes. Target miRNA was detected down to 1.4 pM, and its family members were distinguished with almost 100% accuracy. The subcellular localization of NS products can be visualized in real time. The NEPA-based sensing strategy is also suitable for the intracellular in situ fluorescence imaging of cancer-related protein receptors, offering valuable insight into developing sensing protocols for understanding the biological function of vital biomolecules in disease pathogenesis and future therapeutic applications.

A Series of 210 Peripheral Arterial Disease Below-Knee Amputations and Predictors for Subsequent Above-Knee Amputations.

Objective: To review patient characteristics and outcomes after peripheral arterial disease (PAD)-related below-knee amputation (BKA), and identify risk factors predicting subsequent above-knee amputation (AKA). Materials and Methods: A retrospective study of 210 BKAs between May 2008 and December 2015. Results: The mean age of the study population was 66 years. Most of the patients had cardiovascular comorbidities, and 33% had end-stage renal failure (ESRF); 89% were American Society of Anesthesiologists 3 or 4. Previous ipsilateral lower-limb minor amputation was present in 49% and previous contralateral lower-limb major amputation was present in 20% patients. Limb salvage revascularization via angioplasty prior to BKA was performed in 73%, while 27% had extensive tissue loss that was not suitable for limb salvage. Postoperatively, 20% had BKA wound infection, with 3% requiring further surgical debridement, and 9% (19 patients) required subsequent AKA within 1 month. Overall survival analysis at 1-5 years was 75%, 66%, 64%, 59%, and 58%, respectively. Multivariate analysis showed ESRF (Odds Ratio [OR]=3.85; p=0.01) and preoperative non-ambulatory status (OR=5.58; p=0.01) to be independent risk factors in predicting for subsequent AKA. Conclusion: Patients with underlying ESRF or preoperative non-ambulatory status may benefit from direct AKA if major amputation is required.