Traditional experimental methods are unable to study the kinematics of whole lumbar spine specimens under physiologic compressive preloads because the spine without active musculature buckles under just 120 N of vertical load. However, the lumbar spine can support a compressive load of physiologic magnitude (up to 1200 N) without collapsing if the load is applied along a follower load path. This study tested the hypothesis that the load-displacement response of the lumbar spine in flexion-extension is affected by the magnitude of the follower preload and the follower preload path. Twenty-one fresh human cadaveric lumbar spines were tested in flexion-extension under increasing compressive follower preload applied along two distinctly different optimized preload paths. The first (neutral) preload path was considered optimum if the specimen underwent the least angular change in its lordosis when the full range of preload (0-1200 N) was applied in its neutral posture. The second (flexed) preload path was optimized for an intermediate specimen posture between neutral and full flexion. A twofold increase in flexion stiffness occurred around the neutral posture as the preload was increased from 0 to 1200 N. The preload magnitude (400 N and larger) significantly affected the range of motion (ROM), with a 25% decrease at 1200 N preload applied along the neutral path. When the preload was applied along a path optimized for an intermediate forward-flexed posture, only a 15% decrease in ROM occurred at 1200 N. The results demonstrate that whole lumbar spine specimens can be subjected to compressive follower preloads of in vivo magnitudes while allowing physiologic mobility under flexion-extension moments. The optimized follower preload provides a method to simulate the resultant vector of the muscles that allow the spine to support physiologic compressive loads induced during flexion-extension activities. 相似文献
Purpose: The purpose of the study is to report the prognostic factors and outcomes of vitrectomy (PPV) with silicone oil tamponade in rhegmatogenous retinal detachment (RRD) secondary to acute retinal necrosis (ARN).
Methods: This retrospective, non-randomized, interventional comparative study included 38 eyes of 38 patients. All cases underwent PPV with silicone oil tamponade. The main outcome measure was improvement of final visual acuity relative to the presenting visual acuity and factors affecting the same Group A included eyes with favorable vision of 20/400 or better and Group B included the others.
Results: Group A included 16 eyes (42.10%), group B included 22 eyes (57.89%). In Group A 2 eyes out of 16 (12.5%) and in Group B 12 eyes out of 22 (54.54%) had RRD at presentation (p = 0.02, 95% CI for the difference 7.88–65.78%). The time interval between first presentation and development of RRD in Group A was 30.94 ± 38.8 days (median 30 days) whereas that in Group B was 10.81 ± 11.73 days (median 8 days) (p = 0.02). The odds of visual improvement post-vitrectomy when RRD occurred later was 8.4 (p = 0.01, 95% CI 1.53–46.1). The usage of systemic steroids (odds 5.2, p = 0.03, 95% CI 1.14–23.54) and oral valacyclovir (odds 4.33, p = 0.04, 95% CI 1.05–17.84) were associated with odds favoring a good visual outcome. Recurrent RRD was noted in 3/16 eyes (18.75%) in Group A and 13/22 eyes (59.09%) in Group B (p = 0.03).
Conclusion: Delayed occurrence of RRD after ARN is a good prognostic factor. Usage of systemic steroids and oral valacylocvir are associated with a favorable visual outcome when started before the onset of RRD. 相似文献
A series of new 5-aryliden-2-imino-4-thiazolidinones (5a–e and 6a–e) were synthesized via a three-step reaction and characterized by physicochemical and spectral data. The uniqueness of the derivatives lies in the fact that none of them had an acidic group, like conventional NSAIDS, but exhibited significant in vivo activity in acute inflammation models. In particular, 5-(3-chlorobenzyliden)-2-(pyridin-2-yl-imino)-4-thiazolidinone(5a) and 5-(3-chlorobenzyliden)-2-(5-methylisoxazol-3-yl-imino)-4-thiazolidinone (6a) showed remarkable paw oedema inhibition (67.76 and 74.47 % oedema inhibition, respectively, after 3 h) comparable to that of Ibuprofen (74.56 % oedema inhibition, after 3 h) at half of the dose of the standard drug. Also, compounds 5a (72.86 %) and 6a (80.20 %) were found to possess significant inhibition of albumin denaturation when screened for in vitro anti-inflammatory activity. In addition, these compounds were docked into the known active site of COX-2 protein using Glide XP and QPLD algorithms, and the binding-free energy was calculated using Prime MM/GBSA simulation methods. The combined use of molecular docking and MM/GBSA methods gave a good correlation between the predicted binding-free energy and experimentally determined biological activities. It was also evident from the docking results that 2-methylisoxazolylimino or 2-(pyridin-2-yl-imino substitution and 3-chloro moiety on 5-benzylidin nucleus of these 4-thiazolidinone derivatives can easily occupy the COX-2 binding pocket, considered as the critical interaction for COX-2 inhibition. Moreover, pharmacokinetic properties of all the synthesized compounds were predicted, with good results. Further, the synthesized derivatives showed neither acute toxicity nor symptoms of gastric ulceration, at extended doses, owing to the absence of an acidic group. 相似文献
The purpose was to study choroidal thickness and its profile based on location in healthy Indian children using enhanced depth spectral-domain-optical coherence tomography (SD-OCT).
Methods:
In this cross-sectional observational study 255 eyes of 136 children with no retinal or choroidal disease were consecutively scanned using enhanced depth SD-OCT. Eyes with any ocular disease or axial length (AXL) >25 mm or < 20 mm were excluded. A single observer measured choroidal thickness from the posterior edge of the retinal pigment epithelium to the choroid/sclera junction at 500-microns intervals up to 2500 microns temporal and nasal to the fovea. Generalized estimating equations were used to evaluate the correlation between choroidal thickness at various locations and age, AXL, gender and spherical equivalent (SEq).
Results:
Mean age of the subjects was 11.9 ± 3.4 years (range: 5–18 years). There were 62 Females and 74 males. The mean AXL was 23.55 ± 0.74 mm. Mean subfoveal choroidal thickness was 312.1 ± 45.40 μm. Choroid was found to be thickest subfoveally, then temporally. Age, AXL and SEq showed a significant correlation with choroidal thickness, whereas gender did not affect choroidal thickness.
Conclusion:
Our study provides a valid normative database of choroidal thickness in healthy Indian children. This database could be useful for further studies evaluating choroidal changes in various chorioretinal disorders. Age and AXL are critical factors, which negatively correlated with choroidal thickness. 相似文献
Women are at a 2-fold risk of developing late-onset Alzheimer's disease (AD) (onset at 65 years of age or older) compared with men. During perimenopausal years, women undergo hormonal changes that are accompanied by metabolic, cardiovascular, and inflammatory changes. These all together have been suggested as risk factors for late-onset AD. However, not all perimenopausal women develop AD; we hypothesize that certain genetic factors might underlie the increased susceptibility for developing AD in postmenopausal women. We investigated the Androgen Receptor gene (AR) in a clinical cohort of male and female AD patients and normal control subjects by sequencing all coding exons and evaluating the length and distribution of the CAG repeat in exon 1. We could not establish a correlation between the repeat length, sex, and the disease status, nor did we identify possible pathogenic variants. AR is located on the X chromosome; to assess its role in AD, X-inactivation patterns will need to be studied to directly correlate the actual expressed repeat length to a possible sex-specific phenotypic effect. 相似文献