Sensitization to Mechanical Stimulation by Inflammatory Mediators and by Mild Burn in Canine Visceral Nociceptors In Vitro

2002 ◽  
Vol 87 (4) ◽  
pp. 2043-2051 ◽  
Author(s):  
Hisashi Koda ◽  
Kazue Mizumura
Keyword(s):  
Mechanical Stimulation ◽  
Inflammatory Mediators ◽  
Mechanical Response ◽  
Second Messengers ◽  
Intracellular Camp ◽  
Solution Ph ◽  
In Vitro Investigation ◽  
Anesthetized Dogs ◽  
C 30

Hyperalgesia to mechanical stimulation and heat is commonly observed in inflamed conditions. Although sensitization to heat is well documented and its mechanism has also been well studied, it remains unclear whether and how nociceptors are sensitized to mechanical stimulation. Therefore we conducted in vitro investigation of which inflammatory mediators (bradykinin, histamine, prostaglandin E2, and protons) sensitize nociceptors to suprathreshold mechanical stimulation and at what concentrations. In addition, we studied the effects of possible second messengers for these mediators downstream of the receptors and also the effects of mild burn. Single polymodal receptor activities were recorded in canine testis-spermatic nerve preparations excised from deeply anesthetized dogs. Mechanical stimulation was applied to the identified receptive field for 10 s with a servo-controlled mechanical stimulator. Bradykinin at 0.001 μM induced neither excitation nor facilitation of the mechanical response; however, it facilitated the mechanical response at 0.01 μM and higher, levels at which significant excitation was also induced by bradykinin alone. Histamine excited the nociceptor and sensitized it to mechanical stimulation at 10 μM and higher. PG E2 also sensitized the mechanical response, but starting at 1 μM, without inducing excitation by itself. The effects of two possible intracellular messengers for these mediators were studied using forskolin (10 μM), which increases intracellular cAMP, and a protein-kinase-C-stimulating phorbol ester, phorbol 12,13-dibutyrate (0.1 μM). Both substances reversibly facilitated the mechanical response of testicular polymodal receptors. In contrast, low-pH solution (pH: 6.6–4.5) seldom induced excitation and failed to facilitate the mechanical response. After 55°C, 30-s heat stimulation, testicular polymodal receptors were sensitized to mechanical stimulation. These results demonstrated that inflammatory mediators and burn sensitized nociceptor responses to mechanical stimulation and provide support for the idea that peripheral nociceptor sensitization is a mechanism involved in hyperalgesia to mechanical stimulation in inflamed tissues.

scholarly journals Reverse Iontophoretic Extraction of Skin Cancer-Related Biomarkers

Pharmaceutics ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 79
Author(s):  
Maxim Morin ◽  
Sebastian Björklund ◽  
Skaidre Jankovskaja ◽  
Kieran Moore ◽  
Maria Begoña Delgado-Charro ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Skin Cancer ◽  
Skin Surface ◽  
Buffer Solution ◽  
Solution Ph ◽  
Reverse Iontophoresis ◽  
Non Invasive ◽  
In Vitro Investigation

Non-invasive methods for early diagnosis of skin cancer are highly valued. One possible approach is to monitor relevant biomarkers such as tryptophan (Trp) and kynurenine (Kyn), on the skin surface. The primary aim of this in vitro investigation was, therefore, to examine whether reverse iontophoresis (RI) can enhance the extraction of Trp and Kyn, and to demonstrate how the Trp/Kyn ratio acquired from the skin surface reflects that in the epidermal tissue. The study also explored whether the pH of the receiver medium impacted on extraction efficiency, and assessed the suitability of a bicontinuous cubic liquid crystal as an alternative to a simple buffer solution for this purpose. RI substantially enhanced the extraction of Trp and Kyn, in particular towards the cathode. The Trp/Kyn ratio obtained on the surface matched that in the viable skin. Increasing the receiver solution pH from 4 to 9 improved extraction of both analytes, but did not significantly change the Trp/Kyn ratio. RI extraction of Trp and Kyn into the cubic liquid crystal was comparable to that achieved with simple aqueous receiver solutions. We conclude that RI offers a potential for non-invasive sampling of low-molecular weight biomarkers and further investigations in vivo are therefore warranted.

Design and Development of an Unconstrained Dynamic Knee Simulator

1993 ◽  
Vol 115 (2) ◽  
pp. 144-148 ◽  
Author(s):  
C. A. McLean ◽  
A. M. Ahmed
Keyword(s):  
Mechanical Response ◽  
Dynamic Activity ◽  
Walking Gait ◽  
Knee Simulator ◽  
In Vitro Investigation ◽  
Flexion Extension ◽  
Time Histories ◽  
Fresh Frozen ◽  
Force Components

A dynamic knee simulator has been developed to allow in-vitro investigation of the mechanical response of the joint corresponding to dynamic functional activities, e.g., walking. In the simulator, the controlled inputs are the time-histories of three parameters of a given dynamic activity: the flexion angle, and the flexion/extension moment and tibial axial force components of the foot-to-floor reaction. A combination of stepping motors and electro-hydraulic actuators is used to apply to a knee specimen, simultaneously and independently, the specified load and/or displacement inputs while allowing unconstrained relative motion between the joint members. Satisfactory performance of the simulator has been established for walking gait conditions based on measurements on three fresh-frozen specimens.

scholarly journals Modulation of 3′,5′-cyclic AMP homeostasis in human platelets by coffee and individual coffee constituents

2014 ◽  
Vol 112 (9) ◽  
pp. 1427-1437 ◽  
Author(s):  
Gina A. Montoya ◽  
Tamara Bakuradze ◽  
Marion Eirich ◽  
Thomas Erk ◽  
Matthias Baum ◽  
...  
Keyword(s):  
Cyclic Amp ◽  
Mammalian Cells ◽  
Second Messengers ◽  
Human Platelets ◽  
Significant Inhibition ◽  
Intracellular Camp ◽  
Beneficial Effects ◽  
Underlying Mechanisms

3′,5′-Cyclic AMP (cAMP) is one of the most important second messengers in mammalian cells, mediating a multitude of diverse cellular signalling responses. Its homeostasis is primarily regulated by adenylate cyclases and phosphodiesterases (PDE), the activities of which are partially dependent on the downstream events of adenosine receptor signalling. The present study was conducted to determine whether coffee constituents other than caffeine can influence the homeostasis of intracellular cAMP in vitro and in vivo by evaluating the effects of selected constituents present in coffee, coffee brews and coffee extracts on platelet PDE activity. In addition, to evaluate the potential effects of these constituents on platelet cAMP concentrations and PDE activity in humans, a 7-week pilot intervention study with eight subjects was conducted. The subjects consumed a regular commercial coffee and a low-caffeine coffee at a rate of 750 ml/d for 2 weeks each. The in vivo results revealed a highly significant inhibition of PDE activity (P< 0·001) after coffee intervention that was not directly dependent on the caffeine content of coffee. Although our in vitro and in vivo findings suggest that caffeine plays some role in the modulation of platelet cAMP status, other natural and roasting-associated compounds such as pyrazines and other currently unidentified species also appear to contribute significantly. In conclusion, moderate consumption of coffee can modulate platelet PDE activity and cAMP concentrations in humans, which may contribute to the putative beneficial health effects of coffee. Further detailed mechanistic investigations will be required to substantiate these beneficial effects and to elucidate the underlying mechanisms.

A Subtype of α1Adrenoceptor Mediates Depression of Conduction in Purkinje Fibers Exposed to Halothane

1995 ◽  
Vol 82 (6) ◽  
pp. 1438-1446. ◽  
Author(s):  
Lawrence A. Turner ◽  
Sanja Vodanovic ◽  
Raymond G. Hoffmann ◽  
John P. Kampine ◽  
Zeljko J. Bosnjak
Keyword(s):  
Phospholipase C ◽  
Conduction Velocity ◽  
Second Messengers ◽  
Conduction Time ◽  
Muscarinic Agonist ◽  
Purkinje Fibers ◽  
Alpha Adrenoceptors ◽  
Anesthetized Dogs ◽  
Free Running

Background An action of epinephrine at alpha adrenoceptors has been reported to slow conduction in Purkinje fibers exposed to halothane. In Purkinje fibers one pharmacologically distinguishable alpha 1-adrenoceptor subtype (alpha 1B) sensitive to the noncompetitive antagonist chloroethylcholinidine mediates decreases in automaticity. Another alpha 1 subtype (alpha 1A), sensitive to the competitive antagonist WB4101, increases spontaneous rate and action potential duration by a mechanism thought to involve hydrolysis of membrane phosphoinositides by phospholipase C. This study examined the dose-response relation and receptor-effector mechanisms underlying depression of conduction in canine Purkinje fibers by epinephrine with halothane. Methods Conduction velocity was determined in vitro by measuring the conduction time between action potentials recorded from two Purkinje fibers located about 6 mm apart along the length of free running portions of the ventricular conduction system, the false tendons. Velocity was evaluated at 1-min intervals during trials of rapid exposure to different agonists in groups of 6-12 preparations. Results Epinephrine (0.2-5.0 microM) transiently decreased Purkinje conduction velocity in a dose-related manner by as much as 33% (at 5 microM epinephrine with 0.86 mM (2.8%) halothane). Velocity decreased by 5% (P &lt; or = 0.01) at an epinephrine concentration similar to "just-threshold" dysrhythmogenic plasma epinephrine concentrations (0.2 microM epinephrine with 0.46 mM halothane) reported in halothane-anesthetized dogs. The decreases of conduction velocity were blocked by prazosin but not by metoprolol, were produced by phenylephrine but not by clonidine, and were antagonized by equimolar (0.5 microM) concentrations of WB4101 more so (P &lt; or = 0.01) than by chloroethylclonidine. WB4101 (0.1 microM) produced 87% inhibition of the response to 0.2 microM epinephrine after chloroethylclonidine pretreatment, indicating mediation by the alpha 1A subtype. Other agonists linked to cardiac phospholipase C activation, including endothelin 1 (40 nM) and the muscarinic agonist carbamylcholine (1 mM), also decreased conduction velocity in fibers exposed to halothane. Conclusions Clinically relevant concentrations of epinephrine transiently depress conduction in Purkinje fibers exposed to halothane by activating cardiac alpha 1 adrenoceptors, largely but not exclusively the WB4101-sensitive alpha 1A subtype, reportedly coupled to stimulation of phospholipase C and generation of the second messengers diacylglycerol and inositol trisphosphate. Anesthetic potentiation of cardiac alpha 1-adrenoceptor effects may contribute to the generation of halothane-epinephrine dysrhythmias by abnormally slowing conduction and facilitating reentry.

In vitro investigation of Varizella zoster virus as an oncolytic virus in glioblastoma therapy

2008 ◽  
Vol 35 (S 01) ◽  
Author(s):  
H Leske ◽  
A Baiker ◽  
C Schichor ◽  
J.C Tonn ◽  
R Goldbrunner ◽  
...  
Keyword(s):  
Oncolytic Virus ◽  
In Vitro Investigation ◽  
Varizella Zoster Virus

Effect of Cyclic AMP and Cyclic GMP on Thromboplastin (Factor III) Synthesis in Human Monocytes In Vitro

1983 ◽  
Vol 50 (04) ◽  
pp. 804-809 ◽  
Author(s):  
Torstein Lyberg
Keyword(s):  
Cyclic Amp ◽  
Cyclic Gmp ◽  
Immune Complexes ◽  
Phosphodiesterase Inhibitors ◽  
Inhibitory Effect ◽  
Intracellular Camp ◽  
Human Monocytes ◽  
Purified Protein Derivative ◽  
A 23187

SummaryHuman monocytes in vitro respond to various agents (immune complexes, lectins, endotoxin, the divalent ionophore A 23187, 12-0-tetradecanoyl-phorbol 13-acetate [TPA], purified protein derivative [PPD] of Bacille Calmette-Guerin) with an increased synthesis of the protein component of thromboplastin. The effect of cyclic AMP and cyclic GMP on this response has been studied. Dibutyryl-cyclic AMP, prostaglandin E1 and the phosphodiesterase inhibitors 3-butyl-1-methyl-xanthine (MIX) and rac -4-(3-butoxy-4-methoxybenzyl)-2-imidazolidinone (Ro 201724), separately and in combination have a pronounced inhibitory effect on the response to immune complexes and PPD, and a moderate effect on the response to endotoxin and lectins. The effect on TPA response and on the response to A 23187 was slight. Dibutyryl-cyclic GMP (1 mM) gave a slight inhibition of the TPA arid IC response, but had essentially no effect on the response to other inducers. The intracellular cAMP level increased when monocytes were incubated with IC, TPA or A 23187 followed by a decrease to basal levels within 1-2 hr, whereas lectin (PHA) and PPD did not induce such changes. The cAMP response to endotoxin varied. Stimulation with IC induced an increase in monocyte cGMP levels, whereas the other stimulants did not cause such changes.

An In Vitro Investigation of Synergy or Antagonism between Antimicrobial Combinations against Isolates from Bacterial Keratitis

2010 ◽  
Vol 51 (8) ◽  
pp. 4151 ◽  
Author(s):  
Henri Sueke ◽  
Stephen B. Kaye ◽  
Timothy Neal ◽  
Amanda Hall ◽  
Stephen Tuft ◽  
...  
Keyword(s):  
Bacterial Keratitis ◽  
In Vitro Investigation ◽  
Antimicrobial Combinations
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