A Single Nitrous Oxide (N2O) Exposure Leads to Persistent Alleviation of Neuropathic Pain in Rats

Using the rat chronic constriction injury (CCI) pain model, we evaluated whether nitrous oxide (N₂O), a gas shown to have potent anti-hyperalgesic properties, may alleviate neuropathic pain. Mechanical nociceptive threshold was estimated using the paw pressure vocalization test. Thermal allodynia was challenged by measuring the struggle latency by immersion of the hind paw in a 10°C water bath. A single 50% N₂O exposure for 1 hour, 15 minutes not only induced potent anti-nociception during N₂O exposure but also provoked a delayed and sustained reduction (37% to 46%) of pain hypersensitivity of the injured hind paw and abolished pain hypersensitivity of the contralateral uninjured hind paw for at least 1 month. Thermal allodynia was completely prevented by a single N₂O exposure. A preadministration of naltrexone, which markedly reduced acute N₂O-induced anti-nociception, did not affect the persistent reduction of hyperalgesia. The administration of naltrexone in N₂O-treated rats, 1 week after the gas exposure, did not induce any effect. This suggests that the long-lasting effect of N₂O was not due to its prior acute analgesic effect and was independent of endogenous opioid systems. These data suggest that 50% N₂O exposure could be an efficient and safe strategy for alleviating neuropathic pain in a persistent manner.PerspectiveBecause a single 50% N₂O exposure induced a persistent reduction of hyperalgesia-allodynia in a rat neuropathic pain model, clinical trials must be developed for evaluating the N₂O effects in patients with neuropathic pain. The ability of N₂O to potentiate analgesic effects of other drugs also must be evaluated.     

Interleukin-13 primes iNO synthase expression induced by LPS in mouse peritoneal macrophages

Th2 cytokines such as interleukin-13 (IL-13) have both, stimulatory and inhibitory effects on effector functions of macrophages. Reactive nitrogen species are classically induced in Th1 cytokines and/or lipopolysaccharides (LPS) activated macrophages and this response is inhibited by IL-13. In contrast, IL-13 primes macrophages to produce NO in response to LPS when IL-13 treatment happens prior to LPS exposure. This mechanism occurs through a complex signalling pathway, which involves the scavenger receptor CD36, the LPS receptor CD14 and the nuclear receptor PPARgamma. The enhancement of NO production is the consequence of iNOS induction at mRNA and protein levels. The increase of the NO production induced by LPS in IL-13 pre-treated macrophages is found to potentiate the inhibition of Toxoplasma gondii intracellular replication. These results reveal a novel IL-13 signalling pathway that primes the antimicrobial activity of macrophages induced by LPS caused by overexpression of the iNOS-NO axis.     

Trichinella spiralis in a South American sea lion (Otaria flavescens) from Patagonia,Argentina

Parasitology Research - Trichinella spp. from a sylvatic cycle has been found in several animal species such as pumas (Puma concolor), armadillos (Chaetophractus villosus), rats (Rattus...     

Analysis by immunoblotting ofToxoplasma gondii exo-antigens and comparison with somatic antigens

Two solubleToxoplasma gondii antigen preparations were compared using the immunoblotting technique. The first preparation, which is commonly employed in ELISA tests, corresponds to a lytic extract of the parasite. The second known as exo-antigen, has yielded good results in cell immunity research and is obtained fromToxoplasma gondii culture supernatants. In both preparations, components exhibiting same molecular weight of 57–52 (doublet), 43, 38, 35, 30 and 20 kDa were revealed. In addition, two major 27- and 78-kDa components were detected in exo-antigens. The 30 kDa protein was intensely recognised by all sera, confirming the advantage of its use as an antigen in serological reactions. Exo-antigens could be employed as a soluble antigenic solution because they are easy to obtain, they display good antigenicity and their antigenic composition has been defined. Moreover their preparation does not require mouse inoculation. An evaluation of the enzyme-linked immunosorbent assays (ELISAs) involving these antigens has yet to be performed.     

In vitro antimalarial activity and cytotoxicity of cochlospermum tinctorium and C. planchonii leaf extracts and essential oils.

The antimalarial and toxicological properties of Cochlospermum tinctorium and C. planchonii extracts and essential oils prepared from their leaves were studied. The oil components were extracted by hydrodistillation of the plant leaves and characterized by gas chromatography and mass spectrometry. Crude extracts and oils were tested for in vitro antimalarial activity on Plasmodium falciparum. The IC50 were evaluated after 24 and 72 h contact between the oils and the parasite culture, and ranged from 22 to 500 micrograms/ml. C. planchonii leaf oil yielded the best antimalarial effect (IC50: 22-35 micrograms/ml), while the most potent effect from crude leaf extracts was induced by C. tinctorium. The cytotoxicity of the leaf crude extracts and oils was assessed on the K562 cell line and showed IC50 values ranging between 33 and 2000 micrograms/ml.     

Implication of serotonin-transporter (5-HTT) gene polymorphism in subjective memory complaints and mild cognitive impairment (MCI)

Serotonin-transporter-linked polymorphism (5-HTTLPR) is involved in neuropsychiatric diseases and recently the S-isoform has been correlated with a higher risk of developing emotion-induced retrograde amnesia. In order to better clarify the possible role of the 5-HTT S/L polymorphism and its effects on cognitive ability, especially on memory skills, we report here the distributions of the 5-HTT genetic variant and the Apolipoprotein E (ApoE) ?-4 allele and their association with neuropsychological measures in older adults reporting problems with everyday memory. Moreover, we verified the presence of a possible association between the S-allele with depression and the personal trait of neuroticism. Our results indicate an association between the 5-HTTLPR S-allele and the risk of developing MCI. No association was found in the other three groups. We found a positive dose-dependent association between the S-allele and the Rey-Osterrieth complex figure test (recall) score. Finally, our data did not find an association between the same allele and depression or neuroticism. This data, in our opinion shows a slight, non-established influence of 5-HTTLPR on memory skills exhibited in challenging memory tests but no influence on other extra-mnesic cognitive abilities.