To paralyze their more agile prey, the venomous fish-hunting cone snails (Conus) have developed a potent biochemical strategy. They produce several classes of toxic peptides (conotoxins) that attack a series of successive physiological targets in the neuromuscular system of the fish. The peptides include presynaptic omega-conotoxins that prevent the voltage-activated entry of calcium into the nerve terminal and release of acetylcholine, postsynaptic alpha-conotoxins that inhibit the acetylcholine receptor, and muscle sodium channel inhibitors, the mu-conotoxins, which directly abolish muscle action potentials. These distinct peptide toxins share several common features: they are relatively small (13 to 29 amino acids), are highly cross-linked by disulfide bonds, and strongly basic. The fact that they inhibit sequential steps in neuromuscular transmission suggests that their action is synergistic rather than additive. Five new omega-conotoxins that block presynaptic calcium channels are described. They vary in their activity against different vertebrate classes, and also in their actions against different synapses from the same animal. There are susceptible forms of the target molecule in peripheral synapses of fish and amphibians, but those of mice are resistant. However, the mammalian central nervous system is clearly affected, and these toxins are thus of potential significance for investigating the presynaptic calcium channels.

The omega-conotoxins from the venom of fish-hunting cone snails are probably the most useful of presently available ligands for neuronal Ca channels from vertebrates. Two of these peptide toxins, omega-conotoxins MVIIA and MVIIB from the venom of Conus magus, were purified. The amino acid sequences show significant differences from omega-conotoxins from Conus geographus. Total synthesis of omega-conotoxin MVIIA was achieved, and biologically active radiolabeled toxin was produced by iodination. Although omega-conotoxins from C. geographus (GVIA) and C. magus (MVIIA) appear to compete for the same sites in mammalian brain, in amphibian brain the high-affinity binding of omega-conotoxin MVIIA has narrower specificity. In this system, it is demonstrated that a combination of two omega-conotoxins can be used for biochemically defining receptor subtypes and suggested that these correspond to subtypes of neuronal Ca2+ channels.

Geographic tongue is a chronic, inflammatory, and immune-mediated oral lesion of unknown etiology. It is characterized by serpiginous white areas around the atrophic mucosa, which alternation between activity, remission and reactivation at various locations gave the names benign migratory glossitis and wandering rash of the tongue. Psoriasis is a chronic inflammatory disease with frequent cutaneous involvement and an immunogenetic basis of great importance in clinical practice. The association between geographic tongue and psoriasis has been demonstrated in various studies, based on observation of its fundamental lesions, microscopic similarity between the two conditions and the presence of a common genetic marker, human leukocyte antigen (HLA) HLA-C*06. The difficulty however in accepting the diagnosis of geographic tongue as oral psoriasis is the fact that not all patients with geographic tongue present psoriasis. Some authors believe that the prevalence of geographic tongue would be much greater if psoriatic patients underwent thorough oral examination. This study aimed to develop a literature review performed between 1980 and 2014, in which consultation of theses, dissertations and selected scientific articles were conducted through search in Scielo and Bireme databases, from Medline and Lilacs sources, relating the common characteristics between geographic tongue and psoriasis. We observed that the frequency of oral lesions is relatively common, but to establish a correct diagnosis of oral psoriasis, immunohistochemical and genetic histopathological analyzes are necessary, thus highlighting the importance of oral examination in psoriatic patients and cutaneous examination in patients with geographic tongue.

Geographic tongue (GT) and fissured tongue (FT) are the more frequent oral lesions in patients with psoriasis. The aims of this study were to compare the prevalence of GT/FT between psoriasis group (PG) and healthy controls (HC) and investigate the correlation between GT/FT and psoriasis severity using the PASI and age of psoriasis onset. Three hundred and forty-eight PG and 348 HC were selected. According to the age of psoriasis onset, the individuals were classified as having early psoriasis and late psoriasis. The severity of vulgaris psoriasis was determined according to PASI. A follow-up was conducted in patients with psoriasis vulgaris (PV) with GT to evaluate the progression of oral and cutaneous lesions. The FT and GT were more frequent in PG than in HC. The incidence of GT was higher in patients with early psoriasis and that of FT in late-psoriasis. There is association between psoriasis intensity and GT; and a higher monthly decrease of PASI score in patients without GT. The presence of GT and FT is higher in PG than in the HC. GT is associated with disease severity and may be a marker of the psoriasis severity.