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Cold Stimuli (cold + stimulus)
Selected AbstractsReactive oxygen species in rats with chronic post-ischemia painACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 5 2009K. H. KWAK Background: An emerging theme in the study of the pathophysiology of persistent pain is the role of reactive oxygen species (ROS). In the present study, we examined the hypothesis that the exogenous supply of antioxidant drugs during peri-reperfusion would attenuate pain induced by ischemia/reperfusion (IR) injury. We investigated the analgesic effects of three antioxidants administered during peri-reperfusion using an animal model of complex regional pain syndrome-type I consisting of chronic post-ischemia pain (CPIP) of the hind paw. Methods: Application of a tight-fitting tourniquet for a period of 3 h produced CPIP in male Sprague,Dawley rats. Low-dose allopurinol (4 mg/kg), high-dose allopurinol (40 mg/kg), superoxide dismutase (SOD, 4000 U/kg), N -nitro- l -arginine methyl ester (l -NAME, 10 mg/kg), or SOD (4000 U/kg)+l -NAME (10 mg/kg) was administered intraperitoneally just after tourniquet application and at 1 and 2 days after reperfusion for 3 days. The effects of antioxidants in rats were investigated using mechanical and cold stimuli. Each group consisted of seven rats. Results: Allopurinol caused significant alleviation in mechanical and cold allodynia for a period of 4 weeks in rats with CPIP. Both SOD and l -NAME, which were used to investigate the roles of superoxide (O2 ,,) and nitric oxide (NO) in pain, also attenuated neuropathic-like pain symptoms in rats for 4 weeks. Conclusions: Our findings suggest that O2 ,, and NO mediate IR injury-induced chronic pain, and that ROS scavengers administered during the peri-reperfusion period have long-term analgesic effects. [source] Characteristics and physiological role of hyperpolarization activated currents in mouse cold thermoreceptorsTHE JOURNAL OF PHYSIOLOGY, Issue 9 2009Patricio Orio Hyperpolarization-activated currents (Ih) are mediated by the expression of combinations of hyperpolarization-activated, cyclic nucleotide-gated (HCN) channel subunits (HCN1,4). These cation currents are key regulators of cellular excitability in the heart and many neurons in the nervous system. Subunit composition determines the gating properties and cAMP sensitivity of native Ih currents. We investigated the functional properties of Ih in adult mouse cold thermoreceptor neurons from the trigeminal ganglion, identified by their high sensitivity to moderate cooling and responsiveness to menthol. All cultured cold-sensitive (CS) neurons expressed a fast activating Ih, which was fully blocked by extracellular Cs+ or ZD7288 and had biophysical properties consistent with those of heteromeric HCN1,HCN2 channels. In CS neurons from HCN1(,/,) animals, Ih was greatly reduced but not abolished. We find that Ih activity is not essential for the transduction of cold stimuli in CS neurons. Nevertheless, Ih has the potential to shape the excitability of CS neurons. First, Ih blockade caused a membrane hyperpolarization in CS neurons of about 5 mV. Furthermore, impedance power analysis showed that all CS neurons had a prominent subthreshold membrane resonance in the 5,7 Hz range, completely abolished upon blockade of Ih and absent in HCN1 null mice. This frequency range matches the spontaneous firing frequency of cold thermoreceptor terminals in vivo. Behavioural responses to cooling were reduced in HCN1 null mice and after peripheral pharmacological blockade of Ih with ZD7288, suggesting that Ih plays an important role in peripheral sensitivity to cold. [source] Dentine hypersensitivity , Australian dentists' perspectiveAUSTRALIAN DENTAL JOURNAL, Issue 2 2010N Amarasena Abstract Background:, Dentine hypersensitivity is a frequent clinical presentation though inadequately comprehended by dentists. The objective of this study was to describe Australian dentists' perception on the occurrence, predisposing factors, triggers, diagnosis and management of dentine hypersensitivity. Methods:, Eight hundred dentists were randomly selected using the Australian Dental Association membership list and invited to participate in a questionnaire-based survey. Results:, Out of 295 responding dentists, 284 private practitioners were included in the final analysis. Most dentists perceived that the occurrence of dentine hypersensitivity was <20% and commonest among 30,49 year olds. According to them, abrasion and gingival recession were the main predisposing factors whilst cold stimuli were the commonest trigger. A differential diagnosis-based approach was adopted by a majority to diagnose dentine hypersensitivity although routine screening was resorted to by a few. Most dentists were aware of the current mechanisms underlying dentine hypersensitivity whereas the majority perceived that ongoing predisposing factors was the main reason for dentine tubules to remain exposed. The commonest management strategy employed by most dentists was to prescribe desensitizing agents for home use. Conclusions:, Australian dentists' perception of dentine hypersensitivity is generally consistent with the current scientific consensus on this subject. [source] Review of pulp sensibility tests.INTERNATIONAL ENDODONTIC JOURNAL, Issue 9 2010Part I: general information, thermal tests Jafarzadeh H, Abbott PV. Review of pulp sensibility tests. Part ,: general information and thermal tests. International Endodontic Journal, 43, 738,762, 2010. Abstract A major, and essential, part of the diagnostic process for pulp disease is the use of pulp sensibility tests. When diagnosing pulp pain, these tests can be used to reproduce the symptoms reported by the patient to diagnose the diseased tooth as well as the disease state. However, a major shortcoming with these tests is that they only indirectly provide an indication of the state of the pulp by measuring a neural response rather than the vascular supply, so both false positive and false negative results can occur. The relevant literature on pulp sensibility tests in the context of endodontics up to January 2009 was reviewed using PubMed and MEDLINE database searches. This search identified papers published between November 1964 and January 2009 in all languages. Thermal tests have been used as an integral part of dental examinations. Two types of thermal tests are available, one uses a cold stimulus and the other uses a hot stimulus, and each has various methods of delivery. If these tests are used properly, injury to the pulp is highly unlikely. A review of the literature regarding the rationale, indications, limitations, and interpretation of thermal tests, the value of these diagnostic tests, as well as a discussion of the important points about each of these tests is presented. [source] Vagal Paroxysmal Atrial Fibrillation: Prevalence and Ablation Outcome in Patients Without Structural Heart DiseaseJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 5 2010RAPHAEL ROSSO M.D. Prevalence of Vagal Paroxysmal Atrial Fibrillation.,Introduction: The prevalence of vagal and adrenergic atrial fibrillation (AF) and the success rate of pulmonary vein isolation (PVI) are not well defined. We investigated the prevalence of vagal and adrenergic AF and the ablation success rate of antral pulmonary vein isolation (APVI) in patients with these triggers compared with patients with random AF. Methods and Results: Two hundred and nine consecutive patients underwent APVI due to symptomatic drug refractory paroxysmal AF. Patients were diagnosed as vagal or adrenergic AF if >90% of AF episodes were related to vagal or adrenergic triggers; otherwise, a diagnosis of random AF was made. Clinical, electrocardiogram (ECG), and Holter follow-up was every 3 months in the first year and every 6 months afterward and for symptoms. Of 209 patients, 57 (27%) had vagal AF, 14 (7%) adrenergic AF, and 138 (66%) random AF. Vagal triggers were sleep (96.4%), postprandial (96.4%), late post-exercise (51%), cold stimulus (20%), coughing (7%), and swallowing (2%). At APVI, 94.3% of patients had isolation of all veins. Twenty-five (12%) patients had a second APVI. At a follow-up of 21 ± 15 months, the percentage of patients free of AF was 75% in the vagal group, 86% in the adrenergic group, and 82% for random AF (P = 0.51). Conclusion: In patients with PAF and no structural heart disease referred for APVI, vagal AF is present in approximately one quarter. APVI is equally effective in patients with vagal AF as in adrenergic and random AF. (J Cardiovasc Electrophysiol, Vol. 21, pp. 489-493, May 2010) [source] Cold Exposure Enhances Tactile Allodynia Transiently In Mononeuropathic RatsJOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 2 2000T. Kauppila A laser and erythrosin-B-induced sciatic nerve injury decreases thresholds of a mechanically induced paw withdrawal reflex and enhances cold-induced withdrawal behavior of the affected limb. Exposure of the affected paw to a normally innocuous cold stimulus results in a transient decrease in the threshold of the mechanically evoked paw withdrawal reflex in neuropathic but not in intact rats. The present data suggest that in an experimental neuropathic state a normally innocuous cold stimulus may further sensitize spinally mediated withdrawal reflexes to stimuli of another stimulus modality, in this case, to innocuous tactile stimuli. Therefore, testing mechanical allodynia in neuropathic rats immediately after testing cold allodynia may produce artifactual results. [source] | ||||||||||