Raptor trapping at Wise Point Station: Year 2003 report

Large numbers of diurnal raptors from breeding populations across northern latitudes migrate south along the Atlantic flyway to reach winter destinations from southeastern North America to southern South America. Many of these birds become concentrated within geographic bottlenecks where they rest and forage. Each fall since 1978, staff, students, and associates of the Center for Conservation Biology at the College of William and Mary have trapped diurnal raptors near the tip of the Lower Delmarva Peninsula. The research objectives of this project continue to be 1) to monitor trends in the migration of several raptor species, 2) to learn more about the natural history of migratory raptors, and 3) to add to our understanding of migratory movements and pathways. During the fall of 2003, the Wise Point Station was operated on 52 days between 9 September and 23 November for a total of 359 hours. A combination of mist nets, bow nets, and dho-gaza nets were used in conjunction with lure birds to trap migrating raptors. A total of 516 raptors of seven species was banded resulting in an overall capture rate of 1.4 birds/operation hr. The project has recorded lower overall capture rates in only 2 of the previous 15 years. The 2003 season continued a downward trend in overall capture rate. Since 1989, capture rate has declined significantly at an average rate of approximately 6%/year. A decline in the capture rate of Sharp-shinned Hawks appears to be solely responsible for the decline in overall rate. The proportion of total captures accounted for by Sharp-shins has declined from more than 60% of total captures in the early 1990’s to less than 30% in recent years. The population-level implications of continued declines in capture rates for Sharp-shinned Hawks within the mid-Atlantic remain unclear. Six birds that were banded at Wise Point during the 2003 season have been recovered elsewhere. This includes 2 Sharp-shinned Hawks, 3 Cooper’s Hawks, and 1 Merlin. Recoveries ranged from Dover Delaware to Marathon Florida. The Merlin was banded on the 8th of October and recovered in Marathon, FL just 6 days later. A total of 19 birds were captured that had been banded previously elsewhere. These included a young, male Peregrine that was color banded in Canada

Anatomical Design and Production of a Novel 3-Dimensional Co-Culture System Replicating the Human Flexor Digitorum Profundus Enthesis

The enthesis, the specialized junction between tendon and bone, is a common site of injury. Although notoriously difficult to repair, advances in interfacial tissue engineering techniques are being developed for restorative function. Most notably are 3D in vitro co-culture models, built to recreate the complex heterogeneity of the native enthesis. While cell and matrix properties are often considered, there has been little attention given to native enthesis anatomical morphometrics and replicating these to enhance clinical relevance. This study focuses on the flexor digitorum profundus (FDP) tendon enthesis and, by combining anatomical morphometrics with computer-aided design, demonstrates the design and construction of an accurate and scalable model of the FDP enthesis. Bespoke 3D-printed mould inserts were fabricated based on the size, shape and insertion angle of the FDP enthesis. Then, silicone culture moulds were created, enabling the production of bespoke anatomical culture zones for an in vitro FDP enthesis model. The validity of the model has been confirmed using brushite cement scaffolds seeded with osteoblasts (bone) and fibrin hydrogel scaffolds seeded with fibroblasts (tendon) in individual studies with cells from either human or rat origin. This novel approach allows a bespoke anatomical design for enthesis repair and should be applied to future studies in this area.<br/

Optimizing an Intermittent Stretch Paradigm Using ERK1/2 Phosphorylation Results in Increased Collagen Synthesis in Engineered Ligaments

Dynamic mechanical input is believed to play a critical role in the development of functional musculoskeletal tissues. To study this phenomenon, cyclic uniaxial mechanical stretch was applied to engineered ligaments using a custom-built bioreactor and the effects of different stretch frequency, amplitude, and duration were determined. Stretch acutely increased the phosphorylation of p38 (3.5±0.74-fold), S6K1 (3.9±0.19-fold), and ERK1/2 (2.45±0.32-fold). The phosphorylation of ERK1/2 was dependent on time, rather than on frequency or amplitude, within these constructs. ERK1/2 phosphorylation was similar following stretch at frequencies from 0.1 to 1?Hz and amplitudes from 2.5% to 15%, whereas phosphorylation reached maximal levels at 10?min of stretch and returned toward basal within 60?min of stretch. Following a single 10-min bout of cyclic stretch, the cells remained refractory to a second stretch for up to 6?h. Using the phosphorylation of ERK1/2 as a guide, the optimum stretch paradigm was hypothesized to be 10?min of stretch at 2.5% of resting length repeated every 6?h. Consistent with this hypothesis, 7 days of stretch using this optimized intermittent stretch program increased the collagen content of the grafts more than a continuous stretch program (CTL=3.1%±0.44%; CONT=4.8%±0.30%; and INT=5.9%±0.56%). These results suggest that short infrequent bouts of loading are optimal for improving engineered tendon and ligament physiology.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98478/1/ten%2Etea%2E2011%2E0336.pd

Stellar adiabatic mass loss model and applications

Roche-lobe overflow and common envelope evolution are very important in binary evolution, which is believed to be the main evolutionary channel to hot subdwarf stars. The details of these processes are difficult to model, but adiabatic expansion provides an excellent approximation to the structure of a donor star undergoing dynamical time scale mass transfer. We can use this model to study the responses of stars of various masses and evolutionary stages as potential donor stars, with the urgent goal of obtaining more accurate stability criteria for dynamical mass transfer in binary population synthesis studies. As examples, we describe here several models with the initial masses equal to 1 Msun and 10 Msun, and identify potential limitations to the use of our results for giant-branch stars.Comment: 7 pages, 5 figures,Accepted for publication in AP&SS, Special issue Hot Sub-dwarf Stars, in Han Z., Jeffery S., Podsiadlowski Ph. ed

Engineering three-dimensional bone macro-tissues by guided fusion of cell spheroids

Introduction: Bioassembly techniques for the application of scaffold-freetissue engineering approaches have evolved in recent years towardproducing larger tissue equivalents that structurally and functionally mimicnative tissues. This study aims to upscale a 3-dimensional bone in-vitromodel through bioassembly of differentiated rat osteoblast (dROb) spheroidswith the potential to develop and mature into a bone macrotissue.Methods: dROb spheroids in control and mineralization media at differentseeding densities (1 × 104, 5 × 104, and 1 × 105 cells) were assessed for cellproliferation and viability by trypan blue staining, for necrotic core byhematoxylin and eosin staining, and for extracellular calcium by Alizarin redand Von Kossa staining. Then, a novel approach was developed tobioassemble dROb spheroids in pillar array supports using a customizedbioassembly system. Pillar array supports were custom-designed and printedusing Formlabs Clear Resin® by Formlabs Form2 printer. These supports wereused as temporary frameworks for spheroid bioassembly until fusionoccurred. Supports were then removed to allow scaffold-free growth andmaturation of fused spheroids. Morphological and molecular analyses wereperformed to understand their structural and functional aspects.Results: Spheroids of all seeding densities proliferated till day 14, andmineralization began with the cessation of proliferation. Necrotic core sizeincreased over time with increased spheroid size. After the bioassembly ofspheroids, the morphological assessment revealed the fusion of spheroidsover time into a single macrotissue of more than 2.5 mm in size with mineralformation. Molecular assessment at different time points revealed osteogenicmaturation based on the presence of osteocalcin, downregulation of Runx2(p &lt; 0.001), and upregulated alkaline phosphatase (p &lt; 0.01).Discussion: With the novel bioassembly approach used here, 3D bonemacrotissues were successfully fabricated which mimicked physiological osteogenesis both morphologically and molecularly. This biofabricationapproach has potential applications in bone tissue engineering,contributing to research related to osteoporosis and other recurrentbone ailments

Autumn Migration of the Northern Saw-whet Owl on the Lower Delmarva Peninsula: Fall 2012 Report

The Northern Saw-whet Owl (Aegolius acadicus) breeds in southern Canada and the northern United States. During the late fall months this species migrates south to the mid-latitudes of North America. Because of its secretive habits, little was known about the Northern Saw-whet Owl’s migration ecology and winter distribution prior to the increase in the number of banding operations during the late 1990’s. During the fall of 1994, The Center for Conservation Biology began a study of migrant Northern Saw-whet Owls along the lower Delmarva Peninsula. This study has been the first to document large numbers of migrants south of Maryland. During the 19-year study, 3,850 owls have been banded and more than 100 foreign recaptures and returns have been recorded. We have also recorded more than 1000 same year recaptures. The owl migration project is conducted each year between the third week of October and the middle of December. Three trap sites (Eastern Shore of Virginia National Wildlife Refuge, Gatr Tract/Mockhorn Island Wildlife Management Area, and Kiptopeke State Park) consisting of 6 mist nets and a continuous-loop audio-lure are opened nightly from dusk to dawn. Among other objectives, the project seeks to 1) determine the annual variation in the magnitude and timing of Northern Saw-whet Owl migration through the lower Delmarva Peninsula, 2) determine the spatial pattern of habitat use near the tip of the Delmarva Peninsula, 3) determine the relative timing of passage for different age classes of Northern Saw-whet Owls, and 4) determine the rate of movement of Northern Saw-whet Owls moving down the Atlantic Flyway. During the fall of 2012, 315 new owls were captured and processed during 44 nights and 8,343 hours of operation. Capture rate was 7.2 owls/night or 3.8 owls/100 net-hours. Age ratio was 86.0% (271 birds) hatching-year (HY) birds compared to 14.0% (44 birds) after-hatching-year (AHY). Nine Eastern Screech Owls (Otus asio) were also captured during the season

Histomorphology of the subregions of the scapholunate ligament and its enthesis

Background  The scapholunate interosseous ligament (SLIL) has three subregions: dorsal, proximal, and volar. The SLIL enthesis has not previously been studied despite its important mechanical function in wrist joint biomechanics. Questions/Purposes  This study aims to compare the histomorphological differences between the SLIL subregions, including at their entheses. Three questions are explored: Do the gross dimensions differ between SLIL subregions? Does the enthesis qualitatively, and its calcified fibrocartilage (CF) quantitatively, differ between (a) SLIL subregions and (b) scaphoid and lunate attachments? Methods  Twelve fresh-frozen human cadaveric wrists were dissected and the gross dimensions of the SLIL subregions measured. Subregions were histologically processed for morphological and compositional analyses, including quantification of enthesis CF area. Results  The dorsal subregion was the thickest. The dorsal and volar subregions had fibrocartilaginous entheses, while the proximal subregion was attached to articular cartilage. The dorsal subregion had significantly more CF than the volar subregion. There was no significant difference in the enthesis CF between scaphoid and lunate attachments in the three subregions. Conclusions  There are significant morphological differences between the SLIL subregions. The dorsal subregion has the largest amount of CF, which is consistent with the greater biomechanical force subjected to this subregion. The similar histomorphology of the ligament at the scaphoid and lunate entheses suggests that similar biomechanical forces are applied to both attachments. Clinical Relevance  The histomorphological results confirm that the dorsal subregion is the strongest of the three subregions. The results from the entheseal region may have important implications in the study of graft incorporation during SLIL reconstruction

Design and Development of a Bioreactor System for Mechanical Stimulation of Musculoskeletal Tissue

We report on the development of a bioreactor system for mechanical stimulation of musculoskeletal tissues. The ultimate object is to improve the quality of medical treatment following injuries of the enthesis tissue. To this end, the tissue formation process through the effect of mechanical stimulation is investigated. A six-well system was designed, 3D printed and tested. An integrated actuator creates strain by applying a force. A contactless position sensor monitors the travels. An electronic circuit controls the bioreactor using a microcontroller. An IoT platform connects the microcontroller to a smartphone, enabling the user to alter variables, trigger actions and monitor the system. The system was stabilised by implementing two PID controllers and safety measures. The results show that the bioreactor design is suited to execute mechanical stimulation and to investigate the tissue formation and regeneration process. The bioreactor reported here can now be implemented in tissue engineering applications including tissue specimen.</p

Comparing physicochemical properties of printed and hand cast biocements designed for ligament replacement

In order to combat the low regenerative capabilities of ligaments, full `bone to bone' replacements are required, which will integrate with bone while providing a smooth transition to the replacement soft tissue (tissues surrounding organs in the body, not being bone). This study investigated the use of three-dimensional powder printing technology to form calcium phosphate brackets, previously used for forming bespoke scaffold geometries, to 95±0·1% accuracy of their original computer aided design. The surface and internal structures of the printed samples were characterised both chemically and morphologically and compared with hand moulded cements in the dry state and after 3 days of immersion in phosphate buffered saline. X-ray diffraction, Raman spectroscopy and SEM all showed the presence of brushite in the hand moulded samples and brushite and monetite within the printed samples. Furthermore, the printed structures have a higher level of porosity in the dry state in comparison to the hand moulded samples (36±2·2% compared to 24±0·7%) despite exhibiting a compressive strength of almost double the hand cast material. Although the compressive strength of the printed cements decreases after the 3 day immersion, there was no significant difference between the printed and hand moulded cements under the same conditions. Three-dimensional powder printing technology has enabled the manufacture of bespoke calcium phosphate brackets with properties similar to those reported for hand moulded cements

Combined decellularisation and dehydration improves the mechanical properties of tissue-engineered sinews

Novel sources of replacement sinews are needed to repair damaged tissue after injury. The current methods of repair ultilise autografts, allografts or xenografts, although each method has distinct disadvantages that limit their success. Decellularisation of harvested tissues has been previously investigated for sinew repair with the long-term aim of repopulating the structure with autologous cells. Although this procedure shows promise, the demand for donor scaffolds will always outweigh supply. Here, we report the fabrication of fibrin-based tissue-engineered sinews, which can be decellularised, dehydrated and stored. The sinews may then be rehydrated and repopulated with an autologous cell population. In addition to enabling production of patient-specific implants, interestingly, the process of combined decellularisation, dehydration and rehydration enhanced the mechanical properties of the sinew. The treated sinews exhibited a 2.6-fold increase in maximum load and 8-fold increase in ultimate tensile strength when compared with the control group ( p < 0.05 in both cases)