The formalin test is a commonly used animal model of acute and tonic pain. However, the molecular targets of formaldehyde (FA, the main ingredient of the formalin solution) on primary nociceptor cells remain controversial. In this report, the effects of FA on electrophysiologically-identified primary nociceptor cells were evaluated in vitro and the roles of the vanilloid receptor TRPV1 in FA-produced activation of primary nociceptors were also examined at both cellular and behavioral levels. Of 92 acutely dissociated dorsal root ganglion (DRG) cells recorded by current patch-clamp technique, 34% were discharged by FA application with the mean onset latencies of the first action potential (AP) being (367.34+/-32.96) s. All the FA-sensitive cells were identified as nociceptor cells by their distinguishable features of AP including longer duration, existence of a hump (a shoulder or inflection) on the repolarizing phase, and longer after-hyperpolarization of APs. Co-application of capsazepine (CPZ), a competitive antagonist of TRPV1 receptors, could block FA-evoked firing with partial inhibition on the membrane depolarization of all cells tested. Of another 160 cells examined by confocal calcium imaging, 32% were shown to respond to FA with an intracellular Ca(2+) rise. Of 51 FA-sensitive cells, 67% were suppressed by CPZ, suggesting partial involvement of TRPV1 in mediation of the FA-evoked intracellular Ca(2+) rise. Under voltage-clamp mode, 41% of DRG cells were evoked to give rise to inward current with the remaining 59% being unchanged. In separate experiments on the other 56 FA-sensitive cells, concentration-dependent increase in the FA-evoked current amplitude was demonstrated. In comparison with controls, the FA-evoked inward current could be significantly suppressed by CPZ that was further enhanced by HC-030031, a TRPA1 selective antagonist. Finally, local effects of CPZ were confirmed in the formalin test and it was shown that the formalin-induced paw flinches were strongly suppressed by CPZ in phase 1 but with phase 2 being significantly suppressed only during 25-55 min. It is therefore concluded that FA can directly activate a subpopulation of primary nociceptor cells and the FA-induced AP discharges are likely to contribute mainly to phase 1, but not phase 2 of the formalin-induced nociception. The activation of primary nociceptor cells by FA is likely to be mediated, at least in part, through TRPV1 and/or TRPA1 receptors.
Acetanilides ; pharmacology ; Action Potentials ; Animals ; Capsaicin ; analogs & derivatives ; pharmacology ; Formaldehyde ; pharmacology ; Ganglia, Spinal ; physiology ; Nociceptors ; physiology ; Pain ; physiopathology ; Pain Measurement ; Patch-Clamp Techniques ; Purines ; pharmacology ; Rats ; Rats, Sprague-Dawley ; TRPV Cation Channels ; physiology

Clinical breakpoints are used in phaseⅡorⅢclinical trials to categorize microorganisms if susceptibility to new tested antibacterial agents that means the patient infected by the pathogen will be enrolled the study or not.The role of this consensus is to define procedure and required data to setting breakpoints and how to revaluate it in clinical trials.

Objective To determine whether the combination of traditional risk factors and quantitative coronary angiography (QCA) assessment could provide accurate prognostic information on a population-based study including 1137 adults with subclinical artherosclerosis and with coronary risk factors. Methods Participants underwent coronary angiography examination before the minimal stenotic diameters, segment diameters, percent stenosis, plaque areas. Other parameters were analyzed by the computer-assisted Coronary Angiography Analysis System. The Framingham Risk Score for each participant was assessed. During the 1 year follow-up period, all kinds of endpoint cardiovascular events were screened. Endpoint events were defined as death from coronary heart disease, nonfatal myocardial infarction (MI) or unstable angina pectoris. Results During the 1 year of follow-up period, a total of 124 participants developed an endpoint event, which was significantly associated with the Framingham Risk Score, calcium of plaques and the plaque areas (all Ps＜0.05).The QCA score incorporated with the QCA parameters was related to the endpoint events. The Framingham Risk Score was combined with QCA score through logistic regression for prediction of end-point events. Data from the ROC analysis showed the accuracy of this prediction algorithm was superior to the accuracy when variables themselves were used. The event-free survival rate was inferior to the control group in participates under high risk, when being screened with this prediction algorithm (P＜0.05). Conclusion The risk of cardiovascular attack in subclinical artherosclerosis individual seemed to be associated with the Framingham Risk Score, calcium of plaques and the plaque areas. When the traditional risk factors (the Framingham Risk Score) were combined with QCA, the new method could provide more prognostic information on those adults with subclinical artherosclerosis.