No abstract available.
Biophysics* ; Metabolism*

As an important intracellular genetic and regulatory center, the nucleus is not only a terminal effector of intracellular biochemical signals, but also has a significant impact on cell function and phenotype through direct or indirect regulation of nuclear mechanistic cues after the cell senses and responds to mechanical stimuli. The nucleus relies on chromatin-nuclear membrane-cytoskeleton infrastructure to couple signal transduction, and responds to these mechanical stimuli in the intracellular and extracellular physical microenvironments. Changes in the morphological structure of the nucleus are the most intuitive manifestation of this mechanical response cascades and are the basis for the direct response of the nucleus to mechanical stimuli. Based on such relationships of the nucleus with cell behavior and phenotype, abnormal nuclear morphological changes are widely used in clinical practice as disease diagnostic tools. This review article highlights the latest advances in how nuclear morphology responds and adapts to mechanical stimuli. Additionally, this article will shed light on the factors that mechanically regulate nuclear morphology as well as the tumor physio-pathological processes involved in nuclear morphology and the underlying mechanobiological mechanisms. It provides new insights into the mechanisms that nuclear mechanics regulates disease development and its use as a potential target for diagnosis and treatment.
Cell Nucleus ; Biophysics ; Cytoskeleton ; Phenotype ; Signal Transduction

A biphasic porous medium model based on the mixture theory in continuum mechanics frame was used to depict the distributions of osseous stress field, distortion field and pore pressure when the bone tissue was subject to various dynamic loads. In the model, the bone tissue was considered as a transversely isotropic, liquid saturated porous material. The coupling relationship among the distortion, fluid flow and the streaming potential is studied. The Galerkin weighted residual method was used to derive the finite element formulation for dynamic response and the streaming potential calculating formulation of bone tissue, the penalty finite element formulation was obtained via introducing the ratio term of pressure p and penalty parameter beta in the continuity equation and, in turn, eliminated the pressure term in governing equation sets. The computational results show that the viscoelastic behavior and the energy dissipation property in the bone tissue, especially in the cancellous bone, is caused to a great extent by the pore liquid flow and diffusion. Meanwhile, because of the existence of electrical double layer between the solid phase and liquid phase, when the liquid constituents in the pore diffuse, the streaming potential appears, and the growth and absorption of bone tissue is expedited.
Biomechanical Phenomena ; Biophysical Phenomena ; Biophysics ; Bone and Bones ; physiology ; Elasticity ; Electrophysiology ; Finite Element Analysis ; Humans ; Models, Biological ; Porosity ; Stress, Mechanical ; Viscosity

Outwardly rectifying swelling-activated chloride conductance (ICl,Swell) in rabbit heart plays a critical role in cardioprotection following ischemic preconditioning (IP). But the functional characterization and molecular basis of this chloride conductance in rabbit heart ventricular myocytes is not clear. Candidate chloride channel clones (e.g. ClC-2, ClC-3, ClC-4 and ClC-5) were determined using RT-PCR and Western blot analysis. Whole cell ICl,Swell was recorded from isolated rabbit ventricular myocytes using patch clamp techniques during hypo-osmotic stress. The inhibitory effects of 4,4' isothiocyanato-2,2-disulfonic acid (DIDS), 5-nitro-2(3-phenylroylamino) benzoic acid (NPPB) and indanyloxyacetic acid 94 (IAA-94) on ICl,Swell were examined. The expected size of PCR products for ClC-2, ClC-3 and ClC-4 but not for ClC-5 was obtained. ClC-2 and ClC-3 expression was confirmed by automated fluorescent DNA sequencing. RT-PCR and Western blot showed that ClC-4 was expressed in abundance and ClC-2 was expressed at somewhat lower levels. The biological and pharmacological properties of I(Cl,Swell), including outward rectification, activation due to cell volume change, sensitivity to DIDS, IAA-94 and NPPB were identical to those known properties of ICl,Swell in exogenously expressed systems and other mammals hearts. It was concluded that ClC-3 or ClC-4 might be responsible for the outwardly rectifying part of ICl,Swell and may be the molecular targets of cardioprotection associated with ischemic preconditioning or hypo-osmotic shock.
Biophysics/methods ; Chlorides/*chemistry ; Chlorides/metabolism ; DNA Primers/chemistry ; Electrophysiology/methods ; Gene Expression Regulation ; Glycolates/pharmacology ; Heart Ventricles/*cytology ; Ischemic Preconditioning ; Muscle Cells/*cytology ; Osmosis ; Sequence Analysis, DNA

We studied the intradiscal pressure in order to understand the biophysics of the lumbar intervertebral disk. We evaluated the relationship between disk morphology and intradiscal pressure in 90 lumbar intervertebral disks of 64 patients. The intrinsic intradiscal pressure in the ruptured disks was much lower than that in the normal or bulging disk, but intrinsic intradiscal pressure alone did not correlate in a statistically significant way to the absence, or presence and/or type of disk herniation. The elastance of normal disks was statistically significantly higher than that of the protruded disk(p<0.05) ; however, the elastance of lumbar disk was not affected by type of disk protrusion. Factors affecting disk elastance were the degeneration and the integrity of the annulus fibrosus and the posterior longitudinal ligament. The authors experienced no complication during the procedure. The measurement of the intradiscal pressure to evaluated the biophysical function of lumbar intervertebral disks is only a simple and risk-free procedure. Also it is suggested that patients with bulging disks of high elastance may be treated by reducing intradiscal pressure with percutaneous procedures such as chemonucleolysis, and automated discectomy using Nucleotome.
Biophysics ; Diskectomy ; Humans ; Intervertebral Disc Chemolysis ; Intervertebral Disc* ; Longitudinal Ligaments

Biomedical Research ; trends ; Biophysics ; trends ; Magnetics ; trends ; Science ; trends

In recent years, investigation focusing on biophysical characteristics of moxibustion results in advancement. The investigations aiming at elucidating the mechanism of maoxibustion from the angle of biophysics show that the effectiveness of moxibustion results not only from thermal effect, but also from the combine effects of spectral radiation, bio-thermal effect and non-thermal-bio effect. Currently, multi-discipline techniques are applied in research about biophysical characteristics of moxibustion which received broad attention. These researches show a good way and method to elucidating the mechanism of moxibustion; furthermore, they provid experimental evidence for the advancement in clinical practices and the research and design of imitating moxibustion instruments. This paper states the researches focusing on the effect of moxibustion on local body temperature, the infrared spectrum characteristics of moxibustion, bio-thermal effect and energy conversion of moxibustion, bio-heat transfer of moxibustion and microcirculation.
Animals ; Biophysics ; Body Temperature ; Energy Transfer ; Humans ; Microcirculation ; Moxibustion

The cryoballoon was invented to achieve circumferential pulmonary vein isolation more efficiently to compliment the shortcomings of point-by-point ablation by radiofrequency ablation (RFA). Its efficacy and safety were shown to be comparable to those of RFA, and the clinical outcomes have improved with the second-generation cryoballoon. The basic biophysics, implemental techniques, procedural recommendations, clinical outcomes, and complications of the cryoballoon are presented in this practical and systematic review.
Atrial Fibrillation ; Biophysics ; Catheter Ablation ; Cryosurgery ; Pulmonary Veins

The extracellular matrix (ECM) is a heterogeneous, connective network composed of fibrous glycoproteins that coordinate in vivo to provide the physical scaffolding, mechanical stability, and biochemical cues necessary for tissue morphogenesis and homeostasis. This review highlights some of the recently raised aspects of the roles of the ECM as related to the fields of biophysics and biomedical engineering. Fundamental aspects of focus include the role of the ECM as a basic cellular structure, for novel spontaneous network formation, as an ideal scaffold in tissue engineering, and its essential contribution to cell sheet technology. As these technologies move from the laboratory to clinical practice, they are bound to shape the vast field of tissue engineering for medical transplantations.
Biomedical Engineering ; Biophysics ; Cellular Structures ; Collagen ; Cues ; Elastin ; Extracellular Matrix* ; Fibronectins ; Glycoproteins ; Homeostasis ; Morphogenesis ; Tissue Engineering*

T cell activation and function require physical contact with antigen presenting cells at a specialized junctional structure known as the immunological synapse. Once formed, the immunological synapse leads to sustained T cell receptor-mediated signalling and stabilized adhesion. High resolution microscopy indeed had a great impact in understanding the function and dynamic structure of immunological synapse. Trends of recent research are now moving towards understanding the mechanical part of immune system, expanding our knowledge in mechanosensitivity, force generation, and biophysics of cell-cell interaction. Actin cytoskeleton plays inevitable role in adaptive immune system, allowing it to bear dynamic and precise characteristics at the same time. The regulation of mechanical engine seems very complicated and overlapping, but it enables cells to be very sensitive to external signals such as surface rigidity. In this review, we focus on actin regulators and how immune cells regulate dynamic actin rearrangement process to drive the formation of immunological synapse.
Actin Cytoskeleton ; Actins ; Antigen-Presenting Cells ; Biophysics ; Immune System ; Immunological Synapses ; Microscopy ; T-Lymphocytes ; Ursidae