Structural and micro-anatomical changes in vertebrae associated with idiopathic-type spinal curvature in the curveback guppy model

Background: The curveback lineage of guppy is characterized by heritable idiopathic-type spinal curvature thatdevelops during growth. Prior work has revealed several important developmental similarities to the human idiopathicscoliosis (IS) syndrome. In this study we investigate structural and histological aspects of the vertebrae that areassociated with spinal curvature in the curveback guppy and test for sexual dimorphism that might explain a femalebias for severe curve magnitudes in the population.Methods: Vertebrae were studied from whole-mount skeletal specimens of curved and non-curved adult males andfemales. A series of ratios were used to characterize structural aspects of each vertebra. A three-way analysis of variancetested for effects of sex, curvature, vertebral position along the spine, and all 2-way interactions (i.e., sex and curvature,sex and vertebra position, and vertebra position and curvature). Histological analyses were used to characterize microarchitecturalchanges in affected vertebrae and the intervertebral region.Results: In curveback, vertebrae that are associated with curvature demonstrate asymmetric shape distortion,migration of the intervertebral ligament, and vertebral thickening on the concave side of curvature. There is sexualdimorphism among curved individuals such that for several vertebrae, females have more slender vertebrae than domales. Also, in the region of the spine where lordosis typically occurs, curved and non-curved females have a reducedwidth at the middle of their vertebrae, relative to males.Conclusions: Based on similarities to human spinal curvatures and to animals with induced curves, the concaveconvexbiases described in the guppy suggest that there is a mechanical component to curve pathogenesis incurveback. Because idiopathic-type curvature in curveback is primarily a sagittal deformity, it is structurally more similarto Scheuermann kyphosis than IS. Anatomical differences between teleosts and humans make direct biomechanicalcomparisons difficult. However, study of basic biological systems involved in idiopathic-type spinal curvature incurveback may provide insight into the relationship between a predisposing aetiology, growth, and biomechanics.Further work is needed to clarify whether observed sex differences in vertebral characteristics are related to the femalebias for severe curves that is observed in the population

Does Soil Respiration Decline Following Bark Beetle Induced Forest Mortality? Evidence from a Lodgepole Pine Forest

Lodgepole pine (Pinus contorta var. latifolia) forests across western North America have been undergoing a major mortality event owing to a mountain pine beetle (Dendroctonus ponderosae) infestation. We studied biotic and abiotic drivers of growing season soil respiration in four mature stands experiencing different levels of mortality between 2008 and 2012 in southeastern Wyoming, USA. Bark beetle infestation significantly altered forest structure during the 5-year study period. Live basal area (LBA) declined and mortality ranged from near zero to more than 80% in stands with the lowest and highest mortality, respectively. LBA explained 66% of the spatial variation in peak growing season soil respiration, which ranged from 1.4 ± 0.1 μmol m−2 s−1 in stands with lowest LBA to 3.1 ± 0.2 μmol m−2 s−1 with highest LBA. However, within stands, soil respiration did not change over the five-year study period, likely because pre-infestation LBA governed ecosystem-level differences. During peak growing season, soil respiration was significantly correlated with fine root biomass and mid-day photosynthetic photon flux density, providing strong evidence that autotrophic respiration dominated the forest soil respiration flux. Each factor predicted from 35% to 55% of seasonal soil respiration variability with the highest correlation coefficients in stands with the lowest mortality. However, we did not observe significant changes in the peak growing season soil respiration over time within stands undergoing beetle infestation, suggesting that remaining soil respiration activity in dead stands may be attributed to heterotrophic activity and surviving vegetation. Ecosystem modeling often does not adequately represent complex changes in stand structure following beetle infestation, but these dynamic processes should be included to better predict disturbance effects on carbon (C) cycling

Selection of fusion levels in adolescent idiopathic scoliosis (AIS) using the fulcrum bending radiograph prediction: verification based on pedicle screw strategy

Concurrent Free Papers 1 - Spine 1: no. 1.11The 29th Annual Congress of the Hong Kong Orthopaedic Association (HKOA 2009), Hong Kong, 28-29 November 2009

Hotplate precipitation gauge calibrations and field measurements

First introduced in 2003, approximately 70 Yankee Environmental Systems (YES) hotplate precipitation gauges have been purchased by researchers and operational meteorologists. A version of the YES hotplate is described in Rasmussen et al. (2011; R11). Presented here is testing of a newer version of the hotplate; this device is equipped with longwave and shortwave radiation sensors. Hotplate surface temperature, coefficients describing natural and forced convective sensible energy transfer, and radiative properties (longwave emissivity and shortwave reflectance) are reported for two of the new-version YES hotplates. These parameters are applied in a new algorithm and are used to derive liquid-equivalent accumulations (snowfall and rainfall), and these accumulations are compared to values derived by the internal algorithm used in the YES hotplates (hotplate-derived accumulations). In contrast with R11, the new algorithm accounts for radiative terms in a hotplate's energy budget, applies an energy conversion factor which does not differ from a theoretical energy conversion factor, and applies a surface area that is correct for the YES hotplate. Radiative effects are shown to be relatively unimportant for the precipitation events analyzed. In addition, this work documents a 10 % difference between the hotplate-derived and new-algorithm-derived accumulations. This difference seems consistent with R11's application of a hotplate surface area that deviates from the actual surface area of the YES hotplate and with R11's recommendation for an energy conversion factor that differs from that calculated using thermodynamic theory

Does Addition of Tobramycin Powder Reduce Infection Rates After Spine Surgery?

Study Design:Retrospective chart review. Objectives:To evaluate the efficacy of tobramycin and vancomycin powder in reducing surgical site infections in posterior lumbar instrumented fusion. Methods:A multicenter, electronic database search was conducted for all patients who underwent posterior instrumented lumbar fusions. Results:The addition of vancomycin powder decreased postoperative infections from an incidence of 5.7% down to a rate of 2.0%. This difference was statistically significant (P = .018). The addition of tobramycin powder to the wound in addition to vancomycin further decreased the infection rate down to 1.8%. The postoperative infection rate was statistically significant (P = .041) when compared with the no-powder group. However, the difference was not statistically significant (P = 1.00) when compared with vancomycin alone. There was also a trend toward gram-negative organisms with the addition of more antibiotic powder. In the control group, for example, the organisms cultured were 66% methicillin-sensitive Staphylococcus aureus and 33% gram-negative organisms. In the vancomycin group, 30% of the organisms cultured were Staphylococcus aureus and 60% gram-negative organisms. In the vancomycin and tobramycin powder group, 100% of the organisms cultured were gram-negative. Conclusions:There is a reduction in surgical site infections with addition of antibiotic powder to the wound prior to closure. However, the reduction in the infection rate was not as great with the addition of tobramycin powder to vancomycin alone and there was a noticeable change in the spectrum of organism cultured with this addition. Clinicians should consider the risk-to-benefit ratio in each case when deciding to use antibiotic powder

Expert’s comment concerning Grand Rounds case entitled “Surgical treatment of a 180° thoracolumbar fixed kyphosis in a young achondroplastic patient: a one stage ‘in situ’ combined fusion and spinal cord translocation” (by J. C. Aurégan, T. Odent, M. Zerah, J.-P. Padovani and C. Glorion)

An expert comment is provided for the case of an 18-year-old male achondroplastic patient with a severe thoracolumbar kyphosis and spinal stenosis managed with a five level hemilaminotomy, a decancellation osteotomy of the three apical vertebrae and circumferential fusion. A review incidence, presenting symptoms and treatment options for thoracolumbar kyphosis in adults with achondroplasia, is provided