Ultrasound imaging for measuring the material and mechanical properties of the Achilles tendon: inter-day reliability and correlation with a functional calf length test

poster abstractPurpose/Hypothesis: The ability to objectively assess Achilles tendon length and mechanical properties can be challenging because other factors such as muscle and joint mechanics can complicate standard clinical tests. Ultrasound imaging has the ability to provide isolated objective measures of the material and mechanical properties of the Achilles tendon. The primary aim of this study was to assess the inter-day reliability of the material and mechanical properties of the Achilles tendon in a single rater. A secondary aim was to investigate whether there was any relationship between measured tendon properties and calf muscle length measured with a lunge test. Number of subjects: Ten Achilles tendons in 5 subjects (all subjects were 24 years old; 80% female). Material/Methods: Healthy subjects attended 2 identical measurement sessions, 2 days apart. Subjects were measured at the same time of day and were encouraged to perform the same pre-test activities. Immediately prior to the ultrasound imaging, functional calf length was measured in standing with a lunge test. Subjects were then positioned prone with the knee extended and ankle held at 0 degrees of dorsiflexion, and measurements of the resting tendon length and tendon cross-sectional area were obtained from static ultrasound images. Tendon elongation was measured during isometric dynamometry through imaging the proximal movement of the musculotendinous junction of the medial gastrocnemius. Tendon strain was measured at maximum isometric torque. Intra-class correlation coefficients (ICCs) were calculated to determine the reliability of the ultrasound measures. The correlation between tendon properties and the lunge test were examined using a Pearson correlation coefficient, with the level of significance set at 0.05. Results: Reliability analysis demonstrated high inter-day test-retest reliability for resting Achilles tendon length (ICC = 0.95), cross-sectional area (ICC = 0.96) and strain (ICC = 0.95). Tendon elongation measured with ultrasound imaging during peak isometric force had good reliability (ICC = 0.81). A moderate correlation was found between resting tendon length and the lunge test on each day of testing; Day 1 (r=0.67, r2=0.45, p=0.034) and Day 2 (r=0.66, r2=0.44, p=0.038). Conclusion: Ultrasound imaging measurements of the material and mechanical properties of the Achilles tendon has good-to-high inter-day reliability in a single rater. It was also determined that Achilles tendon resting length accounted for ~45% of the variance in the lunge test, indicating other factors contribute to lunge test performance. The later may include talocrural and subtalar joint motion, and length of the gastrocnemius and soleus muscles. Clinical relevance: Ultrasound imaging can be used as a reliable, safe and cost-effective tool to measure isolated Achilles tendon properties. This may allow future studies to explore intervention effects on the material and mechanical characteristics of the tendon

Altered branching patterns of Purkinje cells in mouse model for cortical development disorder

Disrupted cortical cytoarchitecture in cerebellum is a typical pathology in reeler. Particularly interesting are structural problems at the cellular level: dendritic morphology has important functional implication in signal processing. Here we describe a combinatorial imaging method of synchrotron X-ray microtomography with Golgi staining, which can deliver 3-dimensional(3-D) micro-architectures of Purkinje cell(PC) dendrites, and give access to quantitative information in 3-D geometry. In reeler, we visualized in 3-D geometry the shape alterations of planar PC dendrites (i.e., abnormal 3-D arborization). Despite these alterations, the 3-D quantitative analysis of the branching patterns showed no significant changes of the 77 ± 8° branch angle, whereas the branch segment length strongly increased with large fluctuations, comparing to control. The 3-D fractal dimension of the PCs decreased from 1.723 to 1.254, indicating a significant reduction of dendritic complexity. This study provides insights into etiologies and further potential treatment options for lissencephaly and various neurodevelopmental disorders

The Reelin Receptors Apoer2 and Vldlr Coordinate the Patterning of Purkinje Cell Topography in the Developing Mouse Cerebellum

The adult cerebellar cortex is comprised of reproducible arrays of transverse zones and parasagittal stripes of Purkinje cells. Adult stripes are created through the perinatal rostrocaudal dispersion of embryonic Purkinje cell clusters, triggered by signaling through the Reelin pathway. Reelin is secreted by neurons in the external granular layer and deep cerebellar nuclei and binds to two high affinity extracellular receptors on Purkinje cells-the Very low density lipoprotein receptor (Vldlr) and apolipoprotein E receptor 2 (Apoer2). In mice null for either Reelin or double null for Vldlr and Apoer2, Purkinje cell clusters fail to disperse. Here we report that animals null for either Vldlr or Apoer2 individually, exhibit specific and parasagittally-restricted Purkinje cell ectopias. For example, in mice lacking Apoer2 function immunostaining reveals ectopic Purkinje cells that are largely restricted to the zebrin II-immunonegative population of the anterior vermis. In contrast, mice null for Vldlr have a much larger population of ectopic Purkinje cells that includes members from both the zebrin II-immunonegative and -immunopositive phenotypes. HSP25 immunoreactivity reveals that in Vldlr null animals a large portion of zebrin II-immunopositive ectopic cells are probably destined to become stripes in the central zone (lobules VI–VII). A small population of ectopic zebrin II-immunonegative Purkinje cells is also observed in animals heterozygous for both receptors (Apoer2+/−: Vldlr+/−), but no ectopia is present in mice heterozygous for either receptor alone. These results indicate that Apoer2 and Vldlr coordinate the dispersal of distinct, but overlapping subsets of Purkinje cells in the developing cerebellum

The novel selective PDE9 inhibitor BAY 73-6691 improves learning and memory in rodents.

The present study investigated the putative pro-cognitive effects of the novel selective PDE9 inhibitor BAY 73-6691. The effects on basal synaptic transmission and long-term potentiation (LTP) were investigated in rat hippocampal slices. Pro-cognitive effects were assessed in a series of learning and memory tasks using rodents as subjects. BAY 73-6691 had no effect on basal synaptic transmission in hippocampal slices prepared from young adult (7- to 8-week-old) Wistar rats. A dose of 10 mu M, but not 30 mu M BAY 73-6691 enhanced early LTP after weak tetanic stimulation. The dose effective in young adult Wistar rats did not affect LTP in hippocampal slices prepared from young (7- to 8-week-old) Fischer 344 X Brown Norway (FBNF1) rats, probably reflecting strain differences. However, it increased basal synaptic transmission and enhanced early LTP after weak tetanic stimulation in hippocampal slices prepared from very old (31 - to 35-month-old) FBNF1 rats. BAY 73-6691 enhanced acquisition, consolidation, and retention of long-term memory (LTM) in a social recognition task and tended to enhance LTM in an object recognition task. Bay 73-6691 attenuated the scoplamine-induced retention deficit in a passive avoidance task, and the MK-801-induced short-term memory deficits in a T-maze alternation task. The mechanism of action, possibly through modulation of the NO/cGMP-PKG/CREB pathway, is discussed. Our findings support the notion that PDE9 inhibition may be a novel target for treating memory deficits that are associated with aging and neurodegenerative disorders such as Alzheimer's disease