Purinergic receptors and neglected tropical diseases: why ignore purinergic signaling in the search for new molecular targets?

Purinergic receptors are widespread in the human organism and are involved in several physiological functions like neurotransmission, nociception, platelet aggregation, etc. In the immune system, they may regulate the expression and release of pro-inflammatory factors as well as the activation and death of several cell types. It is already described the participation of some purinergic receptors in the inflammation and pathological processes, such as a few neglected tropical diseases (NTDs) which affect more than 1 billion people in the world. Although the high social influence those diseases represent endemic countries, most of them do not have an efficient, safe or affordable drug treatment. In that way, this review aims to discuss the current literature involving purinergic receptor and immune response to NTDs pathogens, which may contribute in the search for new therapeutic possibilities.     

Muon Spectroscopy Applied to Biological Systems: A Study of Thiyl Radicals, RS

Thiyl radicals (RS.) are formed when positive muons (μ⁺) are implanted into solutions of thiocarbonyl compounds (C = S) in ethanol, tetrahydrofuran or formamide solvents. A solvent dependence is found, which reflects changing electronic interactions and overall conformations, suggesting that the properties of RS. radicals may be dependent on the polarity (philicity) of the environment in which they are formed.     

Leishmanial antigens in the diagnosis of active lesions and ancient scars of American tegumentary leishmaniasis patients.

Cutaneous biopsies (n = 94) obtained from 88 patients with American tegumentary leishmaniasis were studied by conventional and immunohistochemical techniques. Specimens were distributed as active lesions of cutaneous leishmaniasis (n = 53) (Group I), cicatricial lesions of cutaneous leishmaniasis (n = 35) (Group II) and suggestive scars of healed mucosal leishmaniasis patients (n = 6) (Group III). In addition, active cutaneous lesions of other etiology (n = 24) (Group C1) and cutaneous scars not related to leishmaniasis (n = 10) (Group C2) were also included in the protocol. Amastigotes in Group I biopsies were detected by routine histopathological exam (30.2%), imprint (28.2%), culture (43.4%), immunofluorescence (41.4%) and immunoperoxidase (58.5%) techniques; and by the five methods together (79.3%). In Group II, 5.7% of cultures were positive. Leishmanial antigen was also seen in the cytoplasm of macrophages and giant cells (cellular pattern), vessel walls (vascular pattern) and dermal nerves (neural pattern). Positive reaction was detected in 49 (92.5%), 20 (57%) and 4 (67%) biopsies of Groups I, II and III, respectively. Antigen persistency in cicatricial tissue may be related to immunoprotection or, on the contrary, to the development of late lesions. We suggest that the cellular, vascular and neural patterns could be applied in the immunodiagnosis of active and cicatricial lesions in which leishmaniasis is suspected.     

CAROTENOID COMPOSITION OF MARINE RED ALGAE1

Photosynthetic organisms possess carotenoids that function either as accessory, photoprotective, or structural pigments. Therefore, the carotenoid profile provides information about certain photoacclimation and photoprotection responses. Carotenoids are also important chemosystematic markers because specific enzymes mediate each step of carotenoid biosynthesis. For red algae, diverse and often contradictory carotenoid compositions have been reported. As a consequence, it is difficult to infer the physiological importance of carotenoids in Rhodophyta. To characterize the relationship between carotenoid composition, rhodophycean phylogeny, and the presence of potentially photoprotective pigments, we analyzed the carotenoid composition of 65 subtropical species from 12 orders and 18 rhodophyte families. Our results showed that red algae do not present a unique carotenoid profile. However, a common profile was observed up to the level of order, with exception of the Ceramiales and the Corallinales. The main difference between profiles is related to the xanthophyll that represents the major carotenoid. In some species lutein is the major carotenoid while in others it is substituted by zeaxanthin or antheraxanthin. The presence of this epoxy carotenoid together with the presence of violaxanthin that are xanthophyll cycle (XC)‐related pigments was found in four of the 12 analyzed orders. The carotenoid pigment profiles are discussed in relation to Rhodophyta phylogeny, and it is suggested that the xanthophyll cycle‐related pigments appeared early in the evolution of eukaryotic phototrophs.