Instrumented Lumbar Corpectomy and Spinal Reconstruction Comparing rhBMP-2/Compression-Resistant Matrix, rhBMP-2/Absorbable Collagen Sponge/Ceramic Granules Mixture, and Autograft in Two Different Devices: A Study in Sheep

Study Design. Fusion success with rhBMP-2 and autograft in titanium or PEEK corpectomy devices was evaluated in a sheep lumbar corpectomy model. The 6 treatment groups included titanium mesh or PEEK corpectomy devices filled with rhBMP-2 on a compression-resistant matrix (CRM) carrier; rhBMP-2 in a morselized absorbable collagen sponge (ACS) carrier combined with resorbable ceramic granules; and autograft. Objective. The aim of this study was to determine fusion rates associated with 2 different preparations of rhBMP-2 as well as autograft in an instrumented ovine lumbar corpectomy model 6 months postoperatively. Summary of Background Data. Vertebral reconstruction with corpectomy devices requires bone graft. Bone graft substitutes have the potential to avoid a second operation, donor site pain, and attendant morbidity associated with autograft. Methods. Twenty-four sheep in 6 treatment groups underwent lumbar corpectomy via a retroperitoneal trans-psoas approach. Spines were reconstructed with autograft, rhBMP-2 on a CRM, or rhBMP-2 on an ACS mixed with ceramic granules. Grafting materials were placed in either a titanium mesh or PEEK conduit in spines with internal fixation. Computed tomographic (CT) scans were evaluated for fusion. Undecalcified histology was used to evaluate for fusion as well as the amount and extent of graft incorporation and graft resorption. Results. Regardless of corpectomy device used, rhBMP-2/CRM or rhBMP-2/ACS with MASTERGRAFT resulted in a 100% fusion rate. The autograft group had a lower (75%) radiographic fusion rate. Using either preparation of rhBMP-2 resulted in the length of the defect filling with solid bone. Autograft fragments and ceramic granules were incorporated into the fusion masses with much of the ceramic granules being resorbed by 6 months. Conclusion. Both of the rhBMP-2 formulations have the potential to effect bony fusion and vertebral reconstruction within the corpectomy devices

Time-resolved velocity map imaging of methyl elimination from photoexcited anisole

To date, H-atom elimination from heteroaromatic molecules following UV excitation has been extensively studied, with the focus on key biological molecules such as chromophores of DNA bases and amino acids. Extending these studies to look at elimination of other non-hydride photoproducts is essential in creating a more complete picture of the photochemistry of these biomolecules in the gas-phase. To this effect, CH3 elimination in anisole has been studied using time resolved velocity map imaging (TR-VMI) for the first time, providing both time and energy information on the dynamics following photoexcitation at 200 nm. The extra dimension of energy afforded by these measurements has enabled us to address the role of πσ* states in the excited state dynamics of anisole as compared to the hydride counterpart (phenol), providing strong evidence to suggest that only CH3 fragments eliminated with high kinetic energy are due to direct dissociation involving a 1πσ* state. These measurements also suggest that indirect mechanisms such as statistical unimolecular decay could be contributing to the dynamics at much longer times

Linear models for control of cavity flow oscillations

Models for understanding and controlling oscillations in the flow past a rectangular cavity are developed. These models may be used to guide control designs, to understand performance limits of feedback, and to interpret experimental results. Traditionally, cavity oscillations are assumed to be self-sustained: no external disturbances are necessary to maintain the oscillations, and amplitudes are limited by nonlinearities. We present experimental data which suggests that in some regimes, the oscillations may not be self-sustained, but lightly damped: oscillations are sustained by external forcing, such as boundary-layer turbulence. In these regimes, linear models suffice to describe the behaviour, and the final amplitude of oscillations depends on the characteristics of the external disturbances. These linear models are particularly appropriate for describing cavities in which feedback has been used for noise suppression, as the oscillations are small and nonlinearities are less likely to be important. It is shown that increasing the gain too much in such feedback control experiments can lead to a peak-splitting phenomenon, which is explained by the linear models. Fundamental performance limits indicate that peak splitting is likely to occur for narrow-bandwidth actuators and controllers

Dramatic Loss of Ube3A Expression during Aging of the Mammalian Cortex

Neurobiological studies of aging are beginning to link functional changes with a loss of experience-dependent plasticity. In the visual system, age-related functional changes include decreases in visual acuity, orientation selectivity, motion perception, and ocular dominance plasticity. A recent paper has shown that Ube3A, an E3 ubiquitin ligase that is absent in Angelman's syndrome, is required for experience-dependent plasticity during development of the visual cortex. Knocking out Ube3A during development leads to rigidity of ocular dominance plasticity that is strikingly similar to the reduced plasticity seen in older animals. Furthermore, ubiquitin ligases have been linked with age-related neurodegenerative disorders and longevity. Ubiquitin ligases selectively mark proteins for degradation, and a balance between synaptic proteins and their degradation is important for neural transmission and plasticity. This led us to ask whether normal aging is characterized by a loss of Ube3A in the cortex. We used Western blot analysis in order to quantify Ube3A expression across the life span of humans, macaque monkeys, and cats. We found that Ube3A expression declines across the lifespan in human, monkey, and cat cortex. The losses were substantial (50–80%) in all areas studied which includes V1, V3, V4, frontal, and auditory cortex. In addition, when compared with other synaptic proteins there was a selective loss of Ube3A in human cortex. The progressive loss of Ube3A expression during cortical aging is an important new finding. Furthermore, the selective loss of Ube3A in human cortex highlights a specific vulnerability in human brain aging that may signify a dramatic shift in cortical function and plasticity

Unintentional and intentional recognition rely on dissociable neurocognitive mechanisms

Distractibility can lead to accidents and academic failures, as well as memory problems. Recent evidence suggests that intentional recognition memory can be biased by unintentional recognition of distracting stimuli in the same environment. It is unknown whether unintentional and intentional recognition depend on the same underlying neurocognitive mechanisms. We assessed whether human participants’ recognition of previously seen (old) or not seen (new) target stimuli was affected by whether a to-be-ignored distractor was old or new. ERPs were recorded to investigate the neural correlates of this bias. The results showed that the old/new status of salient distractors had a biasing effect on target recognition accuracy. Both intentional and unintentional recognition elicited early ERP effects that are thought to reflect relatively automatic memory processes. However, only intentional recognition elicited the later ERP marker of conscious recollection, consistent with previous suggestions that recollection is under voluntary control. In contrast, unintentional recognition was associated with an enhanced late posterior negativity, which may reflect monitoring or evaluation of memory signals. The findings suggest that unintentional and intentional recognition involve dissociable memory processes

6'-Methoxy Raloxifene-analog enhances mouse bone properties with reduced estrogen receptor binding

Raloxifene (RAL) is an FDA-approved drug used to treat osteoporosis in postmenopausal women. RAL suppresses bone loss primarily through its role as a selective estrogen receptor modulator (SERM). This hormonal estrogen therapy promotes unintended side effects, such as hot flashes and increased thrombosis risk, and prevents the drug from being used in some patient populations at-risk for fracture, including children with bone disorders. It has recently been demonstrated that RAL can have significant positive effects on overall bone mechanical properties by binding to collagen and increasing bone tissue hydration in a cell-independent manner. A Raloxifene-Analog (RAL-A) was synthesized by replacing the 6-hydroxyl substituent with 6-methoxy in effort to reduce the compound's binding affinity for estrogen receptors (ER) while maintaining its collagen-binding ability. It was hypothesized that RAL-A would improve the mechanical integrity of bone in a manner similar to RAL, but with reduced estrogen receptor binding. Molecular assessment showed that while RAL-A did reduce ER binding, downstream ER signaling was not completely abolished. In-vitro, RAL-A performed similarly to RAL and had an identical concentration threshold on osteocyte cell proliferation, differentiation, and function. To assess treatment effect in-vivo, wildtype (WT) and heterozygous (OIM+/-) female mice from the Osteogenesis Imperfecta (OI) murine model were treated with either RAL or RAL-A from 8 weeks to 16 weeks of age. There was an untreated control group for each genotype as well. Bone microarchitecture was assessed using microCT, and mechanical behavior was assessed using 3-point bending. Results indicate that both compounds produced analogous gains in tibial trabecular and cortical microarchitecture. While WT mechanical properties were not drastically altered with either treatment, OIM+/- mechanical properties were significantly enhanced, most notably, in post-yield properties including bone toughness. This proof-of-concept study shows promising results and warrants the exploration of additional analog iterations to further reduce ER binding and improve fracture resistance

ACCURACY OF BODY MASS PREDICTION USING SEGMENTAL INERTIA PARAMETERS MODELLED FROM PHOTOGRAPHIC IMAGES

The aim of this study was to evaluate the accuracy between the measured and predicted body mass, using the methods of Gittoes et al. (2009), and investigate the relationship between mass and stature and this accuracy. Fifteen male, recreational athletes from a university’s sporting population took part in the study. Measured whole-body masses were compared with predicted whole-body masses calculated using photographic dimensional data and an inertia model. Mean absolute error between measured and predicted whole-body mass was 5.42 ± 2.92 %. A strong, negative correlation between measured whole-body mass and relative % error (r = -0.80) and a normalising value and relative % error was found. It is suggested that for similar participants errors could be up to ± 10% for participants with body masses much greater or less than 71 kg or normalising values equating to 1230 Nm

THE INFLUENCE OF EXPERIENCE ON KINETIC CHARACTERISTICS OF THE LOOPED LONGSWING

The aim of this study was to increase understanding of the strategies performers use to complete the looped longswing (LLS) in order to provide useful information for the development of this skill. For an elite gymnast and two novice performers, kinematic and kinetic data were collected during 5 series of three LLS (CODA motion analysis system, 200 Hz; instrumented high bar, 1 kHz). Inverse dynamics were employed to determine joint kinetics during the second LLS in each trial for each performer. The elite gymnast performed positive work at the hips during the ownswing resulting in hip flexion, which facilitated the control of proceeding functional phase actions. Peak shoulder power values were highest for the elite gymnast and lowest for the least experienced novice participant

What do self-efficacy items measure? : Examining the discriminant content validity of self-efficacy items

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