Plantas medicinais na Amazônia Ocidental.

Os estudos com plantas medicinais, aromáticas e condimentares na Embrapa Amazônia Ocidental iniciaram-se, em 1996, com o pesquisador Antônio Franco de Sá Sobrinho. Posteriormente, houve a incorporação do pesquisador Antônio Nascim Kalil Filho na equipe, com a introdução de sacaca (Croton cajucara) tipos branca e vermelha, provenientes de várias localidades, tanto do Estado do Amazonas como de outros da região Norte, como: sacaca branca (Rio Preto da Eva, Presidente Figueiredo, Iranduba, Manaus, no Amazonas); sacaca vermelha (Belém, Santarém e Belterra, no Pará, e Rio Branco, no Acre)

La primauté du droit : la situation des immigrants et des réfugiés en droit canadien au regard des Chartes et des textes internationaux

The « rule of law » which for a long time was considered as an unwritten part of the Constitution now enjoys full constitutional status. Its enshrining in the preamble of the Canadian Charter sheds considerable light on the manner in which the rights and freedoms of the Charter should be perceived. The author opens his discussion by examining the impact that the constitutionalization of the « rule of law » has had on immigrants and refugees in Canada. As the Immigration Act of 1976 confers numerous discretionary powers which could result in their abusive use, the author analyses how the Human Rights charters applicable in Canada and in Quebec can insure the legal protection of immigrants and refugees. In the second part of his study, the author discusses the principal international texts ratified by Canada which have as their purpose the protection of the rights of immigrants and refugees. As international law is not « self-enforcing » in Canada, the author shows how the internal legal community conforms to the international obligations contracted by Canada

Potential benefits of the 19-nor-clerodane trans-dehydrocrotonin on the central nervous system

This study examined the effect of trans-dehydrocrotonin (DCTN), a 19-nor-clerodane diterpene isolated from Croton cajucara Benth (Euphorbiaceae), as analgesic and its effect on the central nervous system (CNS) of rodents using different animal models. The DCTN intraperitoneally exhibited mild analgesic activity on hot-plate test, but exhibited strong antinociceptive activity against acetic acid-induced abdominal writhing and the ED50 was calculated to be 44.88 mg/kg. At higher doses (100 mg/kg) it exhibited mild CNS depressant activities in laboratory animals. Moreover, it has negligible antidepressant activity. After taking consideration of the drug interaction, the DCTN can be used as a potent analgesic agent in case of peripheral algesia, without affecting the CNS. Neste estudo avaliou-se o efeito analgésico do diterpeno 19-nor-clerodano trans-desidrocrotonina (DCTN) isolado de Croton cajucara Benth (Euphorbiaceae), bem como seu efeito no sistema nervoso central utilizando-se diferentes tipos de modelos de animais roedores. A administração intraperitoneal deste diterpeno, no teste da placa quente, revelou sua atividade analgésica moderada. No entanto, no teste de contrações abdominais desencadeadas por ácido acético, a DCTN apresentou forte atividade antinociceptiva com DE50 de 44,88 mg/kg. Doses elevadas de DCTN (100 mg/kg) apresentaram moderada atividade depressiva do sistema nervoso central (SNC), não tendo sido evidenciado ação antidepressiva. Após algumas considerações da ação de DCTN em algesia periférica, concluiu-se que esta substância pode ser utilizada como um potente agente analgésico, sem afetar o SNC

Regulation of Nociceptive Glutamatergic Signaling by Presynaptic Kv3.4 Channels in the Rat Spinal Dorsal Horn

Presynaptic voltage-gated K+ (Kv) channels in dorsal root ganglion (DRG) neurons are thought to regulate nociceptive synaptic transmission in the spinal dorsal horn. However, the Kv channel subtypes responsible for this critical role have not been identified. The Kv3.4 channel is particularly important because it is robustly expressed in DRG nociceptors, where it regulates action potential (AP) duration. Furthermore, Kv3.4 dysfunction is implicated in the pathophysiology of neuropathic pain in multiple pain models. We hypothesized that, through their ability to modulate AP repolarization, Kv3.4 channels in DRG nociceptors help to regulate nociceptive synaptic transmission. To test this hypothesis, we investigated Kv3.4 immunoreactivity (IR) in the rat cervical superficial dorsal horn (sDH) in both sexes and implemented an intact spinal cord preparation to investigate glutamatergic synaptic currents from second order neurons in the sDH under conditions that selectively inhibit the Kv3.4 current. We found presynaptic Kv3.4 IR in peptidergic and nonpeptidergic nociceptive fibers of the sDH. The Kv3.4 channel is hypersensitive to 4-aminopyridine and tetraethylammonium (TEA). Accordingly, 50 μm 4-aminopyridine and 500 μm TEA significantly prolong the AP, slow the maximum rate of repolarization in small-diameter DRG neurons, and potentiate monosynaptic excitatory postsynaptic currents (EPSCs) in dorsal horn laminae I and II through a presynaptic mechanism. In contrast, highly specific inhibitors of BK, Kv7, and Kv1 channels are less effective modulators of the AP and have little to no effect on EPSCs. The results strongly suggest that presynaptic Kv3.4 channels are major regulators of nociceptive synaptic transmission in the spinal cord.SIGNIFICANCE STATEMENT Intractable neuropathic pain can result from disease or traumatic injury and many studies have been conducted to determine the underlying pathophysiological changes. Voltage-gated ion channels, including the K+ channel Kv3.4, are dysregulated in multiple pain models. Kv3.4 channels are ubiquitously expressed in the dorsal root ganglion (DRG), where they are major regulators of DRG excitability. However, little is known about the ionic mechanisms that regulate nociceptive synaptic transmission at the level of the first synapse in the spinal cord, which is critical to pain transmission in both intact and pathological states. Here, we show that Kv3.4 channels have a significant impact on glutamatergic synaptic transmission in the dorsal horn, further illuminating its potential as a molecular pain therapeutic target.This work was supported by the Vickie and Jack Farber Foundation (M.C.), the Dean's Transformational Science Award (M.C.), the National Institutes of Health (Grant NS079855 to M.C. and Grant NS079702 to A.C.L.), the Dubbs Fellowship Fund (T.M.), Sigma Xi (GIAR Grant G20141015648241 to T.M.), Autifony Therapeutics, Ltd. (M.C.), and the Luso-American Development Foundation (V.P.). We thank Drs. Matthew Dalva, Melanie Elliott, Ethan Goldberg, David Ritter, and Benjamin Zemel, and members of the Covarrubias laboratory for helpful comments and feedback on previous versions of this manuscript; members of the Dalva laboratory for sharing reagents; and Dr. Bruce Bean for providing helpful tips regarding the effects of Kv channel inhibitors on the AP in the DRG.info:eu-repo/semantics/publishedVersio