Histopathological changes induced by extracts from the tissue covering the stingers of Potamotrygon falkneri freshwater stingrays.

Pain is the most conspicuous symptom observed in patients wounded by stingrays, and skin necrosis is common in accidents by freshwater stingrays. The extract from the stinger integumentary tissue of Potamotrygon falkneri containing toxic components (venom) was tested for its ability to induce histopathological changes in the dorsal skin of mice at different times. 3-6 h after injection, foci of necrosis in isolated basal epidermal cells were observed. Full coagulative necrosis of the skin, subcutaneous tissue and skeletal muscle was evident as soon as 24 h after venom exposure, with a clear demarcation from the normal skin. After 48 h, round collections of necrotic cells start to coalesce originating extensive skin necrotic plaques that detach from viable tissue after 72-96 h. Inflammatory infiltrate was observed after 6 h, but was always mild. Acute vascular thrombosis was rare, and hemorrhage was not present at any time. Superficial bacterial infection was present in two of the examined cases. In conclusion, the venom of P. falkneri is responsible for the development of an early necrosis with mild inflammatory reaction, probably due to direct action of the venom. The severe local damage is probably worsened by the mechanical trauma caused by the stinger.

Histopathological changes induced by extracts from the tissue covering the stingers of Potamotrygon falkneri freshwater stingrays

Pain is the most conspicuous symptom observed in patients wounded by stingrays, and skin necrosis is common in accidents by freshwater stingrays. The extract from the stinger integumentary tissue of Potamotrygon falkneri containing toxic components (venom) was tested for its ability to induce histopathological changes in the dorsal skin of mice at different times. 3-6 h after injection, foci of necrosis in isolated basal epidermal cells were observed. Full coagulative necrosis of the skin, subcutaneous tissue and skeletal muscle was evident as soon as 24 h after venom exposure, with a clear demarcation from the normal skin. After 48 h, round collections of necrotic cells start to coalesce originating extensive skin necrotic plaques that detach from viable tissue after 72-96 h. Inflammatory infiltrate was observed after 6 h, but was always mild. Acute vascular thrombosis was rare, and hemorrhage was not present at any time. Superficial bacterial infection was present in two of the examined cases. In conclusion, the venom of P. falkneri is responsible for the development of an early necrosis with mild inflammatory reaction, probably due to direct action of the venom. The severe local damage is probably worsened by the mechanical trauma caused by the stinger.

Inflammatory mediators generated at the site of inoculation of Loxosceles gaucho spider venom.

Patients bitten by Loxosceles spiders generally manifest marked local inflammatory reaction and dermonecrosis. This report evaluated edema formation, leukocyte infiltration and release of inflammatory mediators at the injection site of Loxosceles gaucho venom. BALB/c mice were i.d. injected with venom and thereafter paws were disrupted and homogenized to obtain differential counts of migrated cells, as well to assay the levels of cytokines, chemokines and lipid mediators. Increased footpad thickness was detected as soon as 30 min after venom injection, and 24h later was similar to that of the control group. Loxosceles venom mildly augmented the recruitment of leukocytes to the footpad in comparison with PBS-injected mice. Moreover, it stimulated the release of IL-6, MCP-1 and KC at 2 and 24h after venom injection. In addition, higher levels of PGE(2) were detected 30 min after venom injection in comparison with control group. However, the venom failed to increase levels of IL-1 beta, TNF-alpha, TXB(2) and LTB(4). Our results demonstrate that L. gaucho venom evokes an early complex inflammatory reaction, stimulating the secretion of pro-inflammatory cytokines and lipid mediators (PGE(2)), and recruiting leukocytes to the footpad which contribute to the local reaction induced by L. gaucho venom.

Inflammatory mediators generated at the site of inoculation of Loxosceles gaucho spider venom

Patients bitten by Loxosceles spiders generally manifest marked local inflammatory reaction and dermonecrosis. This report evaluated edema formation, leukocyte infiltration and release of inflammatory mediators at the injection site of Loxosceles gaucho venom. BALB/c mice were i.d. injected with venom and thereafter paws were disrupted and homogenizedto obtain differential counts of migrated cells, as well to assay the levels of cytokines, chemokines and lipid mediators. Increased footpad thickness was detected as soon as30 min after venom injection, and 24 h later was similar to that of the control group. Loxosceles venom mildly augmented the recruitment of leukocytes to the footpad in comparison with PBS-injected mice. Moreover, it stimulated the release of IL-6, MCP-1 and KC at 2 and 24 h after venom injection. In addition, higher levels of PGE2 were detected30 min after venom injection in comparison with control group. However, the venom failed to increase levels of IL-1b, TNF-a, TXB2 and LTB4. Our results demonstrate that L. gaucho venom evokes an early complex inflammatory reaction, stimulating the secretionof pro-inflammatory cytokines and lipid mediators (PGE2), and recruiting leukocytes to the $footpad which contribute to the local reaction induced by L. gaucho venom.

Toxic activities of Brazilian centipede venoms.

Centipedes have a venom gland connected to a pair of forceps, which are used to arrest preys. Human victims bitten by centipedes usually manifest burning pain, paresthesia and edema, which may develop into superficial necrosis. The aim of this work was to characterize and compare toxic activities found in venoms of three species of Brazilian centipedes-Otostigmus pradoi, Cryptops iheringi and Scolopendra viridicornis. By SDS-PAGE (4-20%), important differences were noticed among venoms (between 7 and 205kDa). Few bands showed feeble caseinolytic, fibrinogenolytic and gelatinolytic activities by zymography, but strong hyaluronidase activity was observed in S. viridicornis and O. pradoi venoms. In addition, such activities could be inhibited by o-phenanthroline, indicating that these enzymes are metalloproteinases. All venoms induced nociception, edema and myotoxicity in mice, but only S. viridicornis induced mild hemorrhagic activity. No coagulant activity was detected in centipede venoms. Low phospholipase A(2) activity was observed exclusively in S. viridicornis and O. pradoi venoms, but these venoms had intense direct hemolytic activity on human erythrocytes. Cross-reactivity among venoms was observed using species-specific sera raised in rabbits. Differences were noticed among centipede venoms, but S. viridicornis is indeed the most toxic venom and thereby it could induce a more severe envenomation.

Predictors of Bothrops jararaca venom allergy in snake handlers and snake venom handlers.

Since allergic sensitization to snake venom has been reported, anaphylactic reactions to snake venom might be an underestimated factor contributing to fatal snakebites, independently from the toxicity of the venom itself. However, little information is available on the determinants of such reaction. Hence, we studied a group of workers exposed to Bothrops jararaca venom (BJV), in order to clarify the factors related with snake venom allergy. The aim of this work was to investigate the prevalence and predictors of venom allergy among workers exposed to BJV and to confirm the involvement of IgE-mediated mechanisms in this condition. Workers exposed to BJV were assessed for venom allergy using questionnaires and immunological tests. The presence of BJV sensitization was determined through quantification of specific IgE. Allergens were studied using the Western blots and inhibition assays. Of the 67 workers evaluated, 7 (10.4%) presented specific IgE antibodies to BJV. Of those, 6 presented typical symptoms of an IgE-mediated allergic reaction when exposed to BJV. Venom sensitization was associated with length of employment (P=0.042), high levels of total IgE (P=0.034), atopy (P=0.051), and specific tasks, primarily the handling of dried venom (P=0.014). Our observations suggest that exposure to BJV can result in allergic sensitization in snake handlers through IgE-mediated mechanisms. The prevalence rate of this condition appears to be high among these workers, and the handling of dried venom, total IgE level above 100 kU/L, length of employment, and probably history of atopy were predictors of its occurrence.

Alergia ocupacional causada pelo veneno de serpente Bothrops jararaca em biológos / Occupational allergy in biologist caused by the Bothrops jararaca sanke venom

Objetivo: Revisar a literatura para investigar a associação entre o uso dos esteróides inalados e a presença da doença periodontal. Fontes dos dados: Foi realizada uma revisão consultando a base de dados do Medline acessando o Pubmed; foram também consultadas as fontes de dados 880, Lilacs e Scielo, com as palavras-chaves: periodontal disease (gingivitis and periodontitis) - asthma - inhaled steroids. Síntese dos dados: Os esteróides inalados se constituem na medicação de primeira escolha para o tratamento da asma persistente, sendo bem documentado os efeitos adversos na cavidade bucal, como disfagia, faringite e candidíase. Existem alguns dados sobre os possíveis efeitos deletérios que os este¬róides inalados possam causar nos dentes e gengiva, como exacerbação da inflamação gengiva I, perda de inserção clínica periodontal e perda das unidades dentárias. Conclusão: Parece haver uma associação positiva entre o uso de esteróides inalados e alterações periodontais.

Objective: Review the literature to investigate the association between the use of inhaled steroids and the presence of periodontal disease. Source of data: Literature review was carried out in Medline, Lilacs, Scielo and BBO by Pubmed, using the key-words: periodontal disease (gingivitis and periodontitis) - asthma - inhaled steroids. Syntheses of data: Inhaled steroids are the main drug in the treatment of persistent asthma. Adverse side effects in the oral cavity are well documented, such as dysphagia, pharyngitis and candidiasis. There are some data on possible negative effects steroids cause to teeth and gums, like gingival inflammation, lack of clinical attachment and loss of teeth. Conclusion: The review suggests there is a positive association between the use of inhaled steroids and periodontal alterations.

Comparative study on extracts from the tissue covering the stingers of freshwater (Potamotrygon falkneri) and marine (Dasyatis guttata) stingrays.

Stingrays are elasmobranchs found along the seacoast and in some rivers of Brazil. Pain is the most conspicuous symptom observed in patients wounded by the bilaterally retroserrate stingers located in the tail, which are covered by glandular and integument tissues. In addition, cutaneous necrosis is commonly observed in injuries caused by freshwater stingrays. The aim of this work was to characterize and compare certain properties of tissue extracts obtained from the glandular tissues covering the stinger apparatus of Potamotrygon falkneri and Dasyatis guttata stingrays. By sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), tissue extracts have similar bands above 80 kDa, but most differences were observed below this molecular mass. Lethal, dermonecrotic and myotoxic activities were detected only in P. falkneri tissue extract. Edematogenic activity was similar and dose dependent in both tissue extracts. Nociceptive activity was verified in both tissue extracts, but P. falkneri presented a two-fold higher activity than D. guttata tissue extract. No direct hemolysis, phospholipase A2 and coagulant activities were observed in both tissue extracts. Antigenic cross-reactivity was noticed by ELISA and Western blotting, using antisera raised in rabbits. Species-specific sera reacted with several components of both tissue extracts, noticeably above 22kDa. Both tissue extracts presented gelatinolytic, caseinolytic and fibrinogenolytic activities, which were not caused by the action of metalloproteinases. Hyaluronidase activity was detected only in P. falkneri tissue extract. Our experimental observations suggest that P. falkneri tissue extract is more toxic than D. guttata tissue extract. These results may explain why injuries caused by freshwater stingrays are more severe in human accidents.

Morphological characterization of the venom secretory epidermal cells in the stinger of marine and freshwater stingrays.

Marine and freshwater stingrays are characterized by the presence of one to three mineralized serrated stingers on the tail, which are covered by epidermal cells secreting venom. When these animals are dorsally touched, the stinger can be introduced into the aggressor by a whip reflex mechanism of the tail, causing severe mechanical injuries and inoculating the venom. Accidents in humans are frequent causing intense local pain, oedema and erythema. Bacterial secondary infection is also common. In addition, injuries involving freshwater stingrays frequently cause a persistent cutaneous necrosis. The exact localization of the venom secretory epidermal cells in the stinger is controversial, but it is known that it is preferentially located in the ventrolateral grooves. A comparative morphological analysis of the stinger epidermal tissue of different marine and freshwater Brazilian stingray species was carried out. The results indicate that in freshwater species there is a larger number of protein secretory cells, of two different types, spread over the whole stinger epidermis, while in marine species the protein secretory cells are located only around or inside the stinger ventrolateral grooves. These differences between the stingers of the two groups can justify the more severe envenomation accidents with the freshwater species when compared with the marine species.