Aligned cellular and acellular collagen guidance substrates for peripheral nerve repair

There is a clinical demand to shorten the delay of reinnervation and improve functional recovery after peripheral nerve injury. A peripheral nerve repair device with the ability to direct and promote axon growth across a lesion would be a promising alternative to nerve autograft repair, the current gold standard treatment. The growth of axons across a lesion is most effective when supported by columns of aligned Schwann cells, as found in an autograft. Here we report the development of a robust aligned cellular collagen biomaterial that supports and directs neuronal growth. We also investigate the potential of these aligned cells to precondition the collagen biomaterial, before they are freeze-killed, leaving an acellular guidance matrix

Enumeration of idempotents in planar diagram monoids

We classify and enumerate the idempotents in several planar diagram monoids: namely, the Motzkin, Jones (a.k.a. Temperley-Lieb) and Kauffman monoids. The classification is in terms of certain vertex- and edge-coloured graphs associated to Motzkin diagrams. The enumeration is necessarily algorithmic in nature, and is based on parameters associated to cycle components of these graphs. We compare our algorithms to existing algorithms for enumerating idempotents in arbitrary (regular *-) semigroups, and give several tables of calculated values.Comment: Majorly revised (new title, new abstract, one additional author), 24 pages, 6 figures, 8 tables, 5 algorithm

Relationship between fish size and otolith length for 63 species of fishes from the Eastern North Pacific Ocean

Otoliths commonly are used to determine the taxon, age, and size of fishes. This information is useful for population management, predator-prey studies, and archaeological research. The relationship between the length of a fish and the length of its otoliths remains unknown for many species of marine fishes in the Pacific Ocean. Therefore, the relationships between fish length and fish weight, and between otolith length and fish length, were developed for 63 species of fishes caught in the eastern North Pacific Ocean. We also summarized similar relationships for 46 eastern North Pacific fish species reported in the literature. The relationship between fish length and otolith length was linear, and most of the variability was explained by a simple least-squares regression (r 2 > 0.700 for 45 of 63 species). The relationship between otolith length and fish length was not significantly different between left and right otoliths for all but one fish species. Images of otoliths from 77 taxa are included to assist in the identification of species. (PDF file contains 38 pages.

Bundling And Small Business Operations

The purpose of this paper is to develop and test a model for managing the inventory for a small, student managed food service business.  The Hazell Nut Café offers six coffees, six flavors of ice cream, four teas, hot chocolate, assorted pastries, bottled water, vitamin water, and four other types of cold beverages.  The purveyors for the all supplies, with the exception of dairy products, have on-call deliveries, but pre-set minimums for order quantities.  The dairy company requires a minimum weekly delivery.  After nearly one year of operation, the café’s student-managers are still developing an inventory management system.  The model developed here seeks to provide an easy to understand solution to the supply chain problems encountered by a small business such as the Hazell Nut Café

Fabrication of an endoneurium using engineered neural tissue within a peripheral nerve repair conduit

Peripheral nerve injury as a result of trauma affects approximately 1 million people in Europe and America annually. The current clinical gold standard treatment for repairing long gaps is the nerve autograft, in which only ~50% of cases result in satisfactory functional recovery. Tissue-engineered cellular bridging devices for peripheral nerve repair could provide an attractive alternative to autografts. Sheets of engineered neural tissue (EngNT), which is formed from columns of Schwann cells within a 3D aligned collagen matrix, can promote directed neurite outgrowth in vitro. These sheets of EngNT can be arranged to form the ‘endoneurium’ of a peripheral nerve repair device. Two different arrangements, rod-based and sheet-based designs, were tested within a clinically approved tube, NeuraWrap™, in a 5mm gap in the rat sciatic nerve. Cross sections were stained to detect neurofilament after 4 weeks in vivo and revealed where the axons were growing in relation to the EngNT structures (this was divided into three zones for the analysis). The axon density was significantly greater in zone 1 than in zone 3 in the devices (P2 (mean ± SEM), compared to the sheet-based arrangement (B) (2920 ± 587 axons/mm2). The rod-based arrangement was more stable; there were no observed changes to its structure or orientation as a result of surgical handling or limb movement post-implantation. The designs are modular and can be adapted for the repair of bigger nerves by, for example, having multiple rod structures in the core of outer tubes or sheath wraps. Aligned cellular EngNT rods can form the basis of a functional conduit for peripheral nerve repair

A 3D <i>in vitro</i> model reveals differences in the astrocyte response elicited by potential stem cell therapies for CNS injury.

Aim: This study aimed to develop a 3D culture model to test the extent to which transplanted stem cells modulate astrocyte reactivity, where exacerbated glial cell activation could be detrimental to CNS repair success. Materials & methods: The reactivity of rat astrocytes to bone marrow mesenchymal stem cells, neural crest stem cells (NCSCs) and differentiated adipose-derived stem cells was assessed after 5 days. Schwann cells were used as a positive control. Results: NCSCs and differentiated Schwann cell-like adipose-derived stem cells did not increase astrocyte reactivity. Highly reactive responses to bone marrow mesenchymal stem cells and Schwann cells were equivalent. Conclusion: This approach can screen therapeutic cells prior to in vivo testing, allowing cells likely to trigger a substantial astrocyte response to be identified at an early stage. NCSCs and differentiated Schwann cell-like adipose-derived stem cells may be useful in treating CNS damage without increasing astrogliosis

International lessons on the balance of funding issues: initial paper

This paper summarises the interim findings of a review of secondary data on approaches to the balance of funding in a range of western democracies. Its primary purpose is to identify specific countries that may offer lessons for the current review of the balance of funding in England or which the ODPM may wish us to study in more detail as part of its wider study of international approaches to local and regional governance

Engineered neural tissue with aligned, differentiated adipose-derived stem cells promotes peripheral nerve regeneration across a critical sized defect in rat sciatic nerve.

Adipose-derived stem cells were isolated from rats and differentiated to a Schwann cell-like phenotype in vitro. The differentiated cells (dADSCs) underwent self-alignment in a tethered type-1 collagen gel, followed by stabilisation to generate engineered neural tissue (EngNT-dADSC). The pro-regenerative phenotype of dADSCs was enhanced by this process, and the columns of aligned dADSCs in the aligned collagen matrix supported and guided neurite extension in vitro. EngNT-dADSC sheets were rolled to form peripheral nerve repair constructs that were implanted within NeuraWrap conduits to bridge a 15 mm gap in rat sciatic nerve. After 8 weeks regeneration was assessed using immunofluorescence imaging and transmission electron microscopy and compared to empty conduit and nerve graft controls. The proportion of axons detected in the distal stump was 3.5 fold greater in constructs containing EngNT-dADSC than empty tube controls. Our novel combination of technologies that can organise autologous therapeutic cells within an artificial tissue construct provides a promising new cellular biomaterial for peripheral nerve repair

Quantifying tumour-infiltrating lymphocyte subsets : a practical immuno-histochemical method

Background: Efficient histological quantification of tumour-infiltrating T and B lymphocyte (TIL) subsets in archival tissues would greatly facilitate investigations of the role of TIL in human cancer biology. We sought to develop such a method. Methods: Ten ×40 digital images of 4 μ sections of 16 ductal invasive breast carcinomas immunostained for CD3, CD4, CD8, and CD20 were acquired (a total of 640 images). The number of pixels in each image matching a partition of Lab colour space corresponding to immunostained cells were counted using the ‘Color range’ and ‘Histogram’ tools in Adobe Photoshop 7. These pixel counts were converted to cell counts per mm2 using a calibration factor derived from one, two, three or all 10 images of each case/antibody combination. Results: Variations in the number of labelled pixels per immunostained cell made individual calibration for each case/antibody combination necessary. Calibration based on two fields containing the most labelled pixels gave a cell count minimally higher (+ 5.3%) than the count based on 10-field calibration, with 95% confidence limits − 14.7 to + 25.3%. As TIL density could vary up to 100-fold between cases, this accuracy and precision are acceptable. Conclusion: The methodology described offers sufficient accuracy, precision and efficiency to quantify the density of TIL sub-populations in breast cancer using commonly available software, and could be adapted to batch processing of image files