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Exogenous retinoic acid (RA) induces marked effects on limb patterning, but the precise role of endogenous RA in this process has remained unknown. We have studied the role of RA in mouse limb development by focusing on CYP26B1, a cytochrome P450 enzyme that inactivates RA. Cyp26b1 was shown to be expressed in the distal region of the developing limb bud, and mice that lack CYP26B1 exhibited severe limb malformation (meromelia). The lack of CYP26B1 resulted in spreading of the RA signal toward the distal end of the developing limb and induced proximodistal patterning defects characterized by expansion of proximal identity and restriction of distal identity. CYP26B1 deficiency also induced pronounced apoptosis in the developing limb and delayed chondrocyte maturation. Wild-type embryos exposed to excess RA phenocopied the limb defects of Cyp26b1(-/-) mice. These observations suggest that RA acts as a morphogen to determine proximodistal identity, and that CYP26B1 prevents apoptosis and promotes chondrocyte maturation, in the developing limb.
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http://dx.doi.org/10.1016/s1534-5807(04)00062-0 | DOI Listing |
Biol Cybern
September 2025
Department of Mechanical Science and Engineering, University of Illinois Urbana-Champaign, 61801, IL, USA.
In this article, a biophysically realistic model of a soft octopus arm with internal musculature is presented. The modeling is motivated by experimental observations of sensorimotor control where an arm localizes and reaches a target. Major contributions of this article are: (i) development of models to capture the mechanical properties of arm musculature, the electrical properties of the arm peripheral nervous system (PNS), and the coupling of PNS with muscular contractions; (ii) modeling the arm sensory system, including chemosensing and proprioception; and (iii) algorithms for sensorimotor control, which include a novel feedback neural motor control law for mimicking target-oriented arm reaching motions, and a novel consensus algorithm for solving sensing problems such as locating a food source from local chemical sensory information (exogenous) and arm deformation information (endogenous).
View Article and Find Full Text PDFPsychol Res
September 2025
Neurorehabilitation Research Center, Kio University, Nara, Japan.
The ability to detect small errors between sensory prediction in the brain and actual sensory feedback is important in rehabilitation after brain injury, where motor function needs to be restored. To date in the recent study, a delayed visual error detection task during upper limb movement was used to measure this ability for healthy participants or patients. However, this ability during walking, which is the most sought-after in brain-injured patients, was unclear.
View Article and Find Full Text PDFJ Orthop Res
September 2025
University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA.
The primary purpose of this study was to determine the preoperative predictors of gait biomechanics 6 months after unilateral total knee arthroplasty (TKA). There were 126 participants (age 64.4 ± 7.
View Article and Find Full Text PDFMov Disord
September 2025
Department of Medical Sciences and Public Health, University of Cagliari, Cagliari, Italy.
Background: The hallmark feature of tremor is rhythmicity, which can be quantified using power spectral density (PSD) analysis. However, tremor exhibits considerable variability, ranging from highly regular to more irregular patterns. Similarly, rhythmicity in myoclonus varies, but it typically manifests as arrhythmic jerks.
View Article and Find Full Text PDFTrauma Surg Acute Care Open
September 2025
CRT 4, US Army Institute of Surgical Research Burn Center, Fort Sam Houston, Texas, USA.
Acute extremity compartment syndrome (CS) is a serious medical complication triggered by factors such as trauma, vascular injury, or prolonged compression, resulting in elevated intracompartmental pressure (ICP) and tissue ischemia. Diagnosis remains challenging, mainly relying on the subjective evaluation of clinical symptoms. Different animal models have been used to study pathophysiology and evaluate diagnostic and therapeutic approaches.
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