Mechanical stimulus

Vasodilating molecule(s) liberated from vascular endothelial cells in response to chemical substances (i.e., Acetylcholine, bradykinin, substance P, etc.) or mechanical stimuli (i.e., shear stress, transmural pressure, etc.). The EDRF includes NO, prostaglandin J2 (prostacyclin), and endothelium-derived hypeipolarizing factor (EDHF). 

The release of NO from the endothelium is induced by various chemical substances, including acetylcholine polypeptides such as substance P, bradykinin, and arginine vasopressin histamine ATP/ADP a2-adrenoceptor agonists thrombin and Ca2+ iono-phores. NO formed in response to mechanical stimuli like shear stress or transmural pressure plays an important role in maintaining basal blood flow. Endothelial NO causes vasodilatation, decreased... 

For a skeletal element to respond to its mechanical environment, the cells in the tissue must regulate their environment in response to the mechanical stimuli they receive. The regulatory process can be thought of as a feedback loop (Figure 7.5) in which the osteocyte senses the stimulus and... 

Hydrogen ions accumulate in tissue damaged by inflammation and ischaemia and so pH is lowered. These protons may activate nociceptors directly via their own family of ion channels as well as sensitising them to mechanical stimulation. Acid-sensing ion channels (ASICS) are a family of sodium channels that are activated by protons — of special interest is one type found only in small dorsal root ganglion neurons that possibly are responsible for activation of nociceptors. Although the transduction of mechanical stimuli is poorly understood, ASICs are closely related to channels that respond to stretch. 

The cells comprising lamina V are more diverse than those of lamina IV and their dendrites extend vertically toward the superficial layers. Cell bodies in lamina V contribute to three projection pathways, the SCT, PSDC and STT. However, the STT cells appear to be predominant in this lamina. Lamina V plays an important role in nociception since it receives both A - and C-fibre inputs. Some cells in lamina V also respond to cutaneous low- and high-threshold mechanical stimuli and receive nociceptive inputs from the viscerae. Many of these neurons also project onto mononeurons and so act as interneurons in the polysynaptic withdrawal reflex to noxious stimuli. 

Mechanoreceptor A sensory receptor responding to mechanical stimuli, such as touch and air pressure. 

Hair cells are the sensory cells of the auditory and vestibular systems. Hair cells are the sensory cells of the internal ear, essential for the senses of sound and balance. The hair cell s transduction apparatus, the molecular machinery that converts forces and displacements into electrical responses, can respond to mechanical stimuli of less than 1 nm in amplitude, and of tens or even hundreds of kilohertz in frequency. Indeed, our hearing is ultimately limited by Brownian motion of water molecules impinging on the transduction apparatus. 

The molecules that transduce noxious heat or cold are members of the transient receptor potential (TRP) receptor family 929 Receptors that transduce mechanical stimuli are members of the Degenerin family 930... 

FIGURE 57-2 Noxious chemical, thermal and mechanical stimuli activate specific high-threshold receptors and ion channels that lead to inward currents in the peripheral terminals of nociceptors. 

Plays a key role in the perception of pain induced by thermal, chemical, physical, and mechanical stimuli. 9- ... 

Note Mechanical stimuli such as stresses and strains may produce cracks or fracture in a material. Loss of function of a photochromic material resulting from cyclic irradiation may also be considered fatigue. 

In the event of dietary Ca abundance, Ca in excess of adequate circulating concentrations is deposited in the skeleton. This occurs to the extent of the body s ability to store Ca, and any excess beyond this threshold is excreted. Accrual of Ca into bone is governed by such factors as dietary intake (including the absorption, bioavailability, utilization of nutrients and minerals, and other dietary constituents that influence absorption or retention), calciotropic hormones, genetic potential, lifestyle factors, life stage, general health, and the adaptive response to physical/mechanical stimuli within the constraints of metabolic economy. 

In preclinical studies, a number of TCAs (imipramine, amitriptyline, nortriptyline, desipramine) were shown to inhibit pain behavior in the formalin test after systemic as well as after i.t. administration, and this effect did not seem to be related to an antiinflammatory effect of these drugs (Sawynok and Reid, 2001). The effects of TCAs in preclinical acute pain models (involving acute thermal or mechanical stimuli) have been reviewed by Eschalier et al. (1999). TCAs were also active in models of chronic inflammation (Butler et al., 1985) and in models of neuropathic pain involving nerve injury (e.g. Ardid and Guilbaud, 1992 Abdi et al., 1998). 

Leem, J. W., Choi, E. J., Park, E. S., Paik, K. S. N-methyl-D-aspartate (NMDA) and non-NMDA glutamate receptor antagonists differentially suppress dorsal horn neuron responses to mechanical stimuli in rats with peripheral nerve injury, Neurosci. Lett. 1996, 211, 37-40. 

Pharmacological investigations have proven J-113397 to be the most potent ORL1 antagonist known today (Ozaki et al., 2000a, b Bigoni et al., 2000 Ichikawa et al., 2001). J-113397 is reported to be active in the formalin test, but inactive against pain responses to thermal and mechanical stimuli (Okuda et al., 2000). 

As early as 1892 (Ref 1) it was indicated that expl mixes with materials such as paraffin, vaseline, etc, which have a tendency to result in a softer material, are less sensitive to mechanical stimuli. Since that time many studies (Refs 42, 44, 67) have been conducted by various investigators to determine how waxes accomplish the desensitization of expls... 

There is no question that the method used and the degree of coating of the wax over the surface of either the RDX or HMX crystals is of prime importance in desensitizing the basic materials to mechanical stimuli. Likewise probably the most important property of a desensitizing wax for use in TNT-based expls is its... 

Abstract We describe mechanochromic and thermochromic photoluminescent liquid crystals. In particular, mechanochromic photoluminescent liquid crystals found recently, which are new stimuli-responsive materials are reported. For example, photoluminescent liquid crystals having bulky dendritic moieties with long alkyl chains change their photoluminescent colors by mechanical stimuli associated with isothermal phase transitions. The photoluminescent properties of molecular assemblies depend on their assembled structures. Therefore, controlling the structures of molecular assemblies with external stimuli leads to the development of stimuli-responsive luminescent materials. Mechanochromic photoluminescent properties are also observed for a photoluminescent metallomesogen and a liquid-crystalline polymer. We also show thermochromic photoluminescent liquid crystals based on origo-(/ -phenylenevinylene) and anthracene moieties and a thermochromic photoluminescent metallocomplex. 

Keywords Liquid crystal Mechanical stimuli Phase transition Photoluminescence Stimuli-responsive liquid crystal Thermal stimuli... 

Fig. 4 Molecular structure of compound 4 and observed mechanochromic photoluminescent behavior before and after applying mechanical stimuli...

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