Macro- and micro-designed chitosan-alginate scaffold architecture by three-dimensional printing and directional freezing.

While many tissue-engineered constructs aim to treat cartilage defects, most involve chondrocyte or stem cell seeding on scaffolds. The clinical application of cell-based techniques is limited due to the cost of maintaining cellular constructs on the shelf, potential immune response to allogeneic cell lines, and autologous chondrocyte sources requiring biopsy from already diseased or injured, scarce tissue. An acellular scaffold that can induce endogenous influx and homogeneous distribution of native stem cells from bone marrow holds great promise for cartilage regeneration. This study aims to develop such an acellular scaffold using designed, channeled architecture that simultaneously models the native zones of articular cartilage and subchondral bone. Highly porous, hydrophilic chitosan-alginate (Ch-Al) scaffolds were fabricated in three-dimensionally printed (3DP) molds designed to create millimeter scale macro-channels. Different polymer preform casting techniques were employed to produce scaffolds from both negative and positive 3DP molds. Macro-channeled scaffolds improved cell suspension distribution and uptake overly randomly porous scaffolds, with a wicking volumetric flow rate of 445.6 ± 30.3 mm(3) s(-1) for aqueous solutions and 177 ± 16 mm(3) s(-1) for blood. Additionally, directional freezing was applied to Ch-Al scaffolds, resulting in lamellar pores measuring 300 µm and 50 µm on the long and short axes, thus creating micrometer scale micro-channels. After directionally freezing Ch-Al solution cast in 3DP molds, the combined macro- and micro-channeled scaffold architecture enhanced cell suspension uptake beyond either macro- or micro-channels alone, reaching a volumetric flow rate of 1782.1 ± 48 mm(3) s(-1) for aqueous solutions and 440.9 ± 0.5 mm(3) s(-1) for blood. By combining 3DP and directional freezing, we can control the micro- and macro-architecture of Ch-Al to drastically improve cell influx into and distribution within the scaffold, while achieving porous zones that mimic articular cartilage zonal architecture. In future applications, precisely controlled micro- and macro-channels have the potential to assist immediate endogenous bone marrow uptake, stimulate chondrogenesis, and encourage vascularization of bone in an osteochondral scaffold.

Smartphone use at a university health science center.

This article describes the results of a survey of library patrons conducted by librarians and information technology specialists at the Health Science Center Libraries at the University of Florida. The purpose of the survey was to learn if and how library patrons were using smartphones to perform their work-related tasks and how patrons felt the library could support smartphone use at the Health Science Center.

Lacrimal sac compression by an anterior ethmoidal mucocele presenting as a late complication of dacryocystorhinostomy.

This was an unusual case of lacrimal sac compression by an anterior ethmoidal mucocele presenting as a late complication of a dacryocystorhinostomy (DCR) that was jointly managed by ophthalmic and ENT surgeons via an endoscopic approach. A 22-year-old lady presented with a 12-month history of a painless lump in her left medial canthus area and a 6-month history of left intermittent epiphora. She had a DCR when she was 15 years old with initial symptom control until recent recurrence. There were no nasal or other eye symptoms. The rest of the eye and nasendoscopic examinations were unremarkable. An MRI scan suggested a dacryocystocele; however, a further CT scan revealed a 1.6 cm cystic lesion consistent with an anterior ethmoidal mucocele compressing the lacrimal sac. An endoscopic left anterior ethmoidectomy with marsupialisation of the mucocele was performed in combination with an endoscopic DCR. She made good post-operative recovery.