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Polymerization of actin filaments is the primary source of motility in lamellipodia and it is controlled by a variety of regulatory proteins. The underlying molecular mechanisms are only partially understood and a precise determination of dynamical properties of force generation is necessary. Using optical tweezers, we have measured with millisecond (ms) temporal resolution and picoNewton (pN) sensitivity the force-velocity (Fv) relationship and the power dissipated by lamellipodia of dorsal root ganglia neurons. When force and velocity are averaged over 3-5 s, the Fv relationships can be flat. On a finer timescale, random occurrence of fast growth and subsecond retractions become predominant. The maximal power dissipated by lamellipodia over a silica bead with a diameter of 1 microm is 10(-16) W. Our results clarify the dynamical properties of force generation: i), force generation is a probabilistic process; ii), underlying biological events have a bandwidth up to at least 10 Hz; and iii), fast growth of lamellipodia leading edge alternates with local retractions.
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http://dx.doi.org/10.1016/j.bpj.2009.11.041 | DOI Listing |
PLoS One
September 2025
Department of Economics, Cornell University, Ithaca, United States of America.
In this paper, we study the impact of momentum, volume and investor sentiment on U.S. tech sector stock returns using Principal Component Analysis-Hidden Markov Model (PCA-HMM) methodology.
View Article and Find Full Text PDFPLoS One
September 2025
Mechanical and Nuclear Engineering Department, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates.
Sectionally nonlinearly functionally graded (SNFG) structures with triply periodic minimal surface (TPMS) are considered ideal for bone implants because they closely replicate the hierarchical, anisotropic, and porous architecture of natural bone. The smooth gradient in material distribution allows for optimal load transfer, reduced stress shielding, and enhanced bone ingrowth, while TPMS provides high mechanical strength-to-weight ratio and interconnected porosity for vascularization and tissue integration. Wherein, The SNFG structure contains sections with thickness that varies nonlinearly along their length in different patterns.
View Article and Find Full Text PDFJ Appl Physiol (1985)
September 2025
Ludwig Engel Centre for Respiratory Research, Westmead Hospital, Sydney, NSW, Australia.
Lung volume change modifies pharyngeal airway patency by altering breathing-related passive force transmission between lower and upper airways (via tracheal and other connections). We hypothesise that such force transmission may also impact active upper airway dilator muscle function by altering resting muscle length. The aim of this study was to determine the relationship between end expiratory lung volume (EELV) and ability of sternohyoid muscle (SH) contraction to alter pharyngeal airway patency.
View Article and Find Full Text PDFJ Clin Invest
September 2025
Department of Clinical and Biomedical Sciences, Faculty of Health and Life Sciences, University of Exeter, Exeter, United Kingdom.
Understanding the genetic causes of diseases affecting pancreatic β cells and neurons can give insights into pathways essential for both cell types. Microcephaly, epilepsy and diabetes syndrome (MEDS) is a congenital disorder with two known aetiological genes, IER3IP1 and YIPF5. Both genes encode proteins involved in endoplasmic reticulum (ER) to Golgi trafficking.
View Article and Find Full Text PDFJMIR Med Inform
September 2025
Department of Radiology, Air Force Medical Center, Air Force Medical University, Fucheng Road 30, Haidian District, Beijing, CN.
Background: Lateral malleolar avulsion fracture (LMAF) and subfibular ossicle (SFO) are distinct entities that both present as small bone fragments near the lateral malleolus on imaging, yet require different treatment strategies. Clinical and radiological differentiation is challenging, which can impede timely and precise management. On imaging, magnetic resonance imaging (MRI) is the diagnostic gold standard for differentiating LMAF from SFO, whereas radiological differentiation on computed tomography (CT) alone is challenging in routine practice.
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