Evaluation of different samplers and storage temperature effect on the methane carbon stable isotope analysis.

The present work evaluates the efficiency of some low-cost sampler container for a reliable carbon stable isotope analysis of methane. The procedure efficiency was evaluated for five containers, through 91 days, under two storage temperatures (4 °C and 25 °C) and the results are compared against a reference sampler by using univariate and multivariate statistical methods. Based on the univariate (ANOVA and comparison statistical methods) and multivariate (PCA and HCA) statistical methods, it was identified that (i) the isotopic value changes with time and, in this way, must be taken in account when choosing the appropriate sampler and (ii) the lower temperature reduces the isotopic fractionation process and is preferable for the gas sample storage. Among the storage systems, two options were found to be statistically equivalent to the reference container (IsoJar) for a time horizon of 91 days. We found that the exetainer (4 °C and 25 °C) storage systems are statistically equivalent to the reference container IsoJar and, in this way, it could be an alternative for the methane isotopic studies.

Antinociceptive effect of a novel tosylpyrazole compound in mice.

Pain is the most common complaint in the medical field and the identification of compounds that can effectively treat painful states without induction of side-effects remains a major challenge in biomedical research. The aim of the present study was to investigate the antinociceptive effect of a novel compound, 3-(4-fluorophenyl)-5-trifluoromethyl-1H-1-tosylpyrazole (compound A) in several models of pain in mice and compare with those produced by the known trifluoromethyl-containing pyrazole compound celecoxib. Compound A or celecoxib were administrated by oral (78-780 micromol/kg), intrathecal (9-22.5 nmol/site) or intracerebroventricular (9-22.5 nmol/site) routes. Oral administration of either compound A or celecoxib abolished the mechanical allodynia, but not the oedema caused by intraplantar injection of carrageenan. Similarly, compound A reduced the overt nociception, but not the oedema, produced by bradykinin or capsaicin. However, compound A (500 micromol/kg, orally) did not alter nociception nor oedema caused by intraplantar injection of prostaglandin E(2 )or glutamate, whereas celecoxib reduced only the nociception induced by the former. Moreover, oral and intrathecal administration of compound A or celecoxib also reduced the nociception induced by acetic acid. However, only celecoxib reduced the acetic acid-induced nociception when it was injected by the intracerebroventricular route. Finally, neither compound A nor celecoxib was able to produce antinociceptive effect in the tail-flick test or to alter the motor performance and the body temperature. Besides, compound A or celecoxib did not induce gastric lesion. Thus, compound A seems to be an interesting prototype for the development of novel analgesic drugs.