Causal Pathways from Enteropathogens to Environmental Enteropathy: Findings from the MAL-ED Birth Cohort Study

Background Environmental enteropathy (EE), the adverse impact of frequent and numerous enteric infections on the gut resulting in a state of persistent immune activation and altered permeability, has been proposed as a key determinant of growth failure in children in low- and middle-income populations. A theory-driven systems model to critically evaluate pathways through which enteropathogens, gut permeability, and intestinal and systemic inflammation affect child growth was conducted within the framework of the Etiology, Risk Factors and Interactions of Enteric Infections and Malnutrition and the Consequences for Child Health and Development (MAL-ED) birth cohort study that included children from eight countries. Methods Non-diarrheal stool samples (N = 22,846) from 1253 children from multiple sites were evaluated for a panel of 40 enteropathogens and fecal concentrations of myeloperoxidase, alpha-1-antitrypsin, and neopterin. Among these same children, urinary lactulose:mannitol (L:M) (N = 6363) and plasma alpha-1-acid glycoprotein (AGP) (N = 2797) were also measured. The temporal sampling design was used to create a directed acyclic graph of proposed mechanistic pathways between enteropathogen detection in non-diarrheal stools, biomarkers of intestinal permeability and inflammation, systemic inflammation and change in length- and weight- for age in children 0–2 years of age. Findings Children in these populations had frequent enteric infections and high levels of both intestinal and systemic inflammation. Higher burdens of enteropathogens, especially those categorized as being enteroinvasive or causing mucosal disruption, were associated with elevated biomarker concentrations of gut and systemic inflammation and, via these associations, indirectly associated with both reduced linear and ponderal growth. Evidence for the association with reduced linear growth was stronger for systemic inflammation than for gut inflammation; the opposite was true of reduced ponderal growth. Although Giardia was associated with reduced growth, the association was not mediated by any of the biomarkers evaluated. Interpretation The large quantity of empirical evidence contributing to this analysis supports the conceptual model of EE. The effects of EE on growth faltering in young children were small, but multiple mechanistic pathways underlying the attribution of growth failure to asymptomatic enteric infections had statistical support in the analysis. The strongest evidence for EE was the association between enteropathogens and linear growth mediated through systemic inflammation

Effect Of Toxin-g From Tityus Serrulatus Scorpion Venom On Gastric Emptying In Rats

The effect of toxin-γ from Tityus serrulatus scorpion venom on the gastric emptying of liquids was studied in 176 young adult male Wistar rats (2-3 months of age) divided into subgroups of 8 animals each. Toxin-γ was injected iv at doses of 25, 37.5, 50 or 100 μg/kg and the effect on gastric emptying was assessed 30 min and 8 h later. A time-course study was also performed by injecting 50 μg of toxin-γ/kg and measuring the effect on gastric emptying at times 0.25, 0.5, 1, 2, 4, 8, 24 and 48 h post-venom. Each envenomed animal was paired with its saline control and all received a saline test meal solution containing phenol red (60 μg/ml) as a marker. Ten minutes after administering the test meal by gavage the animals were sacrificed and gastric retention was determined by measuring the residual marker concentration of the test meal. A significant delay in gastric emptying, at 30 min and 8 h post-venom, was observed only after 50 and 100 μg of toxin- γ/kg compared to control values. The responses to these two doses were significantly different after 8 h post-venom. Toxin-γ (50 μg/kg) significantly delayed the gastric emptying of liquids at all times studied, with a peak response at 4 h after toxin administration compared to control values. These results indicate that the iv injection of toxin-γ may induce a rapid, intense and sustained inhibition of gastric emptying 0.25 to 48 h after envenomation.324431434Freire-Maia, L., Campos, J.A., Pathophysiology and treatment of scorpion poisoning (1989) Natural Toxins, pp. 139-159. , Ownby CH & Odell GV (Editors), Pergamon Press, OxfordBucaretchi, F., Baracat, E.C.E., Nogueira, R.J.N., Chaves, A., Zambrone, F.A.D., Fonseca, M.R.C., Tourinho, F.S., A comparative study of severe scorpion envenomation in children caused by Tityus bahiensis and tityus serrulatus (1995) Revista Do Instituto de Medicina Tropical de Sāo Paulo, 37, pp. 331-336Andrade, S.P., Santos, R.A.S., Beraldo, W.T., Comparative study of the action of purified scorpion toxin (tityustoxin) on the submandibular and parotid glands of the rat (1981) Toxicon, 19, pp. 255-261Cunha-Melo, J.R., Gonzaga, H.M.S., Alzamora, F., Freire-Maia, L., Effects of purified scorpion toxin (tityustoxin) on gastric secretion in the rat (1983) Toxicon, 21, pp. 843-848Cunha-Melo, J.R., Almeida, A.P., Gonzaga, H.M.S., Gomez, M.V., Freire-Maia, L., Effect of scorpion toxin on gastric histamine and acetylcholine content in the rat (1987) Brazilian Journal of Medical and Biological Research, 20, pp. 393-401Novaes, G., Cabral, A.P.G., Falco, C.N.M.L., Queiroz, A.C., Acute pancreatitis induced by scorpion toxin, tityustoxin. Histopathological study in rats (1989) Arquivos de Gastroenterologia de Sāo Paulo, 26, pp. 9-12Cunha-Melo, J.R., Toppa, N.H., Martins, P., Colares, C.N., Castro, C.N., Freire-Maia, L., Acute gastric injury induced by toxins from Tityus serrulatus scorpion venom: A novel experimental model in the rat (1991) Toxicon, 29, pp. 1395-1401Hunt, J.N., Mechanisms and disorders of gastric emptying (1983) Annual Review in Medicine, 34, pp. 219-229Roman, C., Gonella, J., Extrinsic control of the stomach (1987) Physiology of the Gastrointestinal Tract. 2nd Edn., pp. 522-532. , Johnson LR (Editor), Raven Press, New YorkSampaio, S.V., Laure, C.J., Giglio, J.R., Isolation and characterization of toxic proteins from the venom of the Brazilian scorpion Tityus serrulatus (1983) Toxicon, 21, pp. 265-277Belangero, V.M.S., Collares, E.F., Estudo do esvaziamento gástrico e acidose metabólica. I. Estudo de um modelo experimental em ratos, empregando uma soluçāo de cloreto de amônio por via orogástrica (1991) Arquivos de Gastroenterologia de Sāo Paulo, 28, pp. 145-150Bucaretchi, F., Collares, E.F., Effect of Phoneutria nigriventer spider venom on gastric emptying in rats (1996) Brazilian Journal of Medical and Biological Research, 29, pp. 205-211Burks, T.F., Actions of drugs on gastrointestinal motility (1987) Physiology of the Gastrointestinal Tract. 2nd Edn., pp. 723-743. , Johnson LR (Editor), Raven Press, New YorkRees, M.R., Clark, R.A., Holdsworth, C.D., The effect of beta-adrenoceptor agonists on gastric emptying in man (1980) British Journal of Clinical Pharmacology, 10, pp. 551-554Sofer, S., Cohen, R., Shapir, Y., Chen, L., Colon, A., Sharf, S.M., Scorpion venom leads to gastrointestinal ischemia despite increased oxygen delivery in pigs (1997) Critical Care Medicine, 25, pp. 834-840Gwee, M.C.E., Cheah, L.S., Gopalakrishnakone, P., Involvement of the L-arginine-nitric-oxide synthase pathway in the relaxant responses of the rat isolated anococcygeus muscle to a scorpion (Leiurus quinquestriatus quinquestriatus) venom (1985) Toxicon, 33, pp. 1141-1150Teixeira, C.E., Bento, A.C., Lopes-Martins, R.A.B., Teixeira, S.A., Von Eicstedt, V., Muscará, M.N., Arantes, E.C., De Nucci, G., Effect of Tityus serrulatus scorpion venom on the rabbit isolated corpus cavernosum and the involvement of NANC nitrergic nerve fibres (1998) British Journal of Pharmacology, 123, pp. 435-442Chou, C.C., Relationship between intestinal blood flow and motility (1982) Annual Review of Physiology, 44, pp. 29-42Stark, M.E., Szurszewski, J.H., Role of nitric oxide in gastrointestinal function and disease (1992) Gastroenterology, 103, pp. 1928-1949Troncon, L.E.A., Garbacio, V.L., Santos, A., Secaf, M., Cunha-Melo, J.R., Efeitos da toxina escorpiônica sobre o esvaziamento gástrico em ratos (1996) Annals of the XI Reuniāo da Federaçāo das Sociedades de Biologia Experimental, p. 72. , Caxambu, 21-24 August, Abstract 09.005Barhanin, J., Ildefonse, M., Rougier, O., Sampaio, S.V., Giglio, J.R., Lazdunski, M., Tityus γ toxin, a high affinity effector of the sodium channel in muscle with a selectivity for channels in the surface membrane (1982) Pflügers Archives, 400, pp. 22-2

Kinetics of venom and antivenom serum levels, clinical evaluation and therapeutic effectiveness in dogs inoculated with Crotalus durissus terrificus venom

This work evaluated the clinical and therapeutic aspects as well as serum levels of venom and antivenom IgG by enzyme-linked immunosorbent assay (ELISA) in experimental envenomation of dogs with Crotalus durissus terrificus venom. Twenty-eight mixed breed adult dogs were divided into four groups of seven animals each, Group I: only venom; Group II, venom + 50 ml of anti-bothropic-crotalic serum (50mg) + fluid therapy; Group III, venom + 50 ml of anti-bothropic-crotalic serum + fluid therapy + urine alkalination; Group IV, 50 ml of anti-bothropic-crotalic serum. The lyophilized venom of Crotalus durissus terrificus was reconstituted in saline solution and subcutaneously inoculated at the dose of 1mg/kg body weight. The dogs presented clinical signs of local pain, weakness, mandibular ptosis, mydriasis, emesis and salivation. The venom levels detected by ELISA ranged from 0 to 90ng/ml, according to the severity of the clinical signs. Serum antivenom ranged from 0 to 3ug/ml and was detected for up to 138h after treatment. ELISA results showed the effectiveness of the serum therapy for the venom neutralization

Identification of New Sphingomyelinases D in Pathogenic Fungi and Other Pathogenic Organisms

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Sphingomyelinases D (SMases D) or dermonecrotic toxins are well characterized in Loxosceles spider venoms and have been described in some strains of pathogenic microorganisms, such as Corynebacterium sp. After spider bites, the SMase D molecules cause skin necrosis and occasional severe systemic manifestations, such as acute renal failure. In this paper, we identified new SMase D amino acid sequences from various organisms belonging to 24 distinct genera, of which, 19 are new. These SMases D share a conserved active site and a C-terminal motif. We suggest that the C-terminal tail is responsible for stabilizing the entire internal structure of the SMase D Tim barrel and that it can be considered an SMase D hallmark in combination with the amino acid residues from the active site. Most of these enzyme sequences were discovered from fungi and the SMase D activity was experimentally confirmed in the fungus Aspergillus flavus. Because most of these novel SMases D are from organisms that are endowed with pathogenic properties similar to those evoked by these enzymes alone, they might be associated with their pathogenic mechanisms.811Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Centre national de la recherche scientifique (CNRS) [2474]Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Centre national de la recherche scientifique (CNRS) [2474]CAPES [23038000825/2011-63]FAPESP [12/00235-5, 2009/16376-4

Design of antibody-reactive peptides from discontinuous parts of scorpion toxins.

International audienceThe Amm VIII protein was previously isolated from the venom of the scorpion Androctonus mauretanicus mauretanicus. Despite 87% identity with AaH II, the most toxic alpha-type scorpion toxin, Amm VIII is not toxic to mice. However, antisera against Amm VIII protect mice from AaH II lethal action. Here, we report that the Amm VIII protein elicits antibodies that only recognize discontinuous-type epitopes since we could not observe any antibody binding to overlapping 12-mer peptides covering the whole Amm VIII sequence. By using a new bioinformatic tool, 24 peptides mimicking discontinuous regions of Amm VIII were designed in silico, then prepared by Spot synthesis. Seven of these discontinuous-continuous peptides were recognized by anti-Amm VIII antibodies. Analysis of the 3D location of the segments that compose the antigenically reactive discontinuous-continuous peptides, allowed us to group those antigenic segments into three regions of Amm VIII, putatively corresponding to discontinuous antigenic regions of alpha-type scorpion toxins. Anti-Amm VIII antibodies were also found to cross-react towards several of the discontinuous-continuous peptides designed from the AaH II structure, pointing to a possible involvement of the corresponding discontinuous epitopes in the capacity displayed by anti-Amm VIII antibodies to neutralize AaH II. Altogether, our results show that it is possible to design antibody-reactive peptides from discontinuous parts of scorpion toxins. The position of the reactive segments in the structural context of scorpion toxins highlights the antigenic properties of the Amm VIII anatoxin and concurs to explain the capacity of anti-Amm VIII antibodies to neutralize the potent AaH II toxin

Brown spider dermonecrotic toxin directly induces nephrotoxicity

Brown spider (Loxosceles genus) venom can induce dermonecrotic lesions at the bite site and systemic manifestations including fever, vomiting, convulsions, disseminated intravascular coagulation, hemolytic anemia and acute renal failure. the venom is composed of a mixture of proteins with several molecules biochemically and biologically well characterized. the mechanism by which the venom induces renal damage is unknown. By using mice exposed to Loxosceles intermedia recombinant dermonecrotic toxin (LiRecDT), we showed direct induction of renal injuries. Microscopic analysis of renal biopsies from dermonecrotic toxin-treated mice showed histological alterations including glomerular edema and tubular necrosis. Hyalinization of tubules with deposition of proteinaceous material in the tubule lumen, tubule epithelial cell vacuoles, tubular edema and epithelial cell lysis was also observed. Leukocytic infiltration was neither observed in the glomerulus nor the tubules. Renal vessels showed no sign of inflammatory response. Additionally, biochemical analyses showed such toxin-induced changes in renal function as urine alkalinization, hematuria and azotemia with elevation of blood urea nitrogen levels. Immunofluorescence with dermonecrotic toxin antibodies and confocal microscopy analysis showed deposition and direct binding of this toxin to renal intrinsic structures. By immunoblotting with a hyperimmune dermonecrotic toxin antiserum on renal lysates from toxin-treated mice, we detected a positive signal at the region of 33-35 kDa, which strengthens the idea that renal failure is directly induced by dermonecrotic toxin. Immunofluorescence reaction with dermonecrotic toxin antibodies revealed deposition and binding of this toxin directly in MDCK epithelial cells in culture. similarly, dermonecrotic toxin treatment caused morphological alterations of MDCK cells including cytoplasmic vacuoles, blebs, evoked impaired spreading and detached cells from each other and from culture substratum. in addition, dermonecrotic toxin treatment of MDCK cells changed their viability evaluated by XTT and Neutral-Red Uptake methodologies. the present results point to brown spider dermonecrotic toxin cytotoxicity upon renal structures in vivo and renal cells in vitro and provide experimental evidence that this brown spider toxin is directly involved in nephrotoxicity evoked during Loxosceles spider venom accidents. (c) 2005 Elsevier Inc. All rights reserved.Univ Fed Parana, Dept Cell Biol, BR-81531990 Curitiba, Parana, BrazilUniversidade Federal de São Paulo, Dept Biochem, São Paulo, BrazilUniv Fed Minas Gerais, Dept Pharmacol, Belo Horizonte, MG, BrazilUniv Fed Minas Gerais, Dept Biochem & Immunol, Belo Horizonte, MG, BrazilUniv Fed Parana, Dept Physiol, BR-80060000 Curitiba, Parana, BrazilCatholic Univ parana, Hlth & Biol Sci Inst, Curitiba, Parana, BrazilUniversidade Federal de São Paulo, Dept Biochem, São Paulo, BrazilWeb of Scienc

General biochemical and immunological characteristics of the venom from Peruvian scorpion Hadruroides lunatus

This communication describes the general biochemical properties and some immunological characteristics of the venom from the Peruvian scorpion Hadruroides lunatus, which is the most medically relevant species in Peru. The soluble venom of this scorpion is toxic to mice, the LD50 determined was 0.1 mg/kg and 21.55 mg/kg when the venom was injected intracranial or intraperitoneally, respectively. The soluble venom displayed proteolytic, hyaluronidasic, phospholipasic and cardiotoxic activities. High performance liquid chromatography of the soluble venom resulted in the separation of 20 fractions. Two peptides with phospholipasic activity were isolated to homogeneity and their molecular masses determined by mass spectrometry (MALDI TOF). Anti-H. lunatus venom sera were produced in rabbits. Western blotting analysis showed that most of the protein content of this venom is immunogenic. H. lunatus anti-venom displayed consistent cross-reactivity with venom antigens from the new World-scorpions Tityus serrulatus and Centruroides sculpturatus venoms; however, a weaker reactivity was observed against the venom antigens from the old World-scorpion Androctonus australis Hector. (C) 2012 Elsevier Ltd. All rights reserved.Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior, Brazil - CAPES (Toxinologia) [23038000825/2011-63]Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior, Brazil CAPES (Toxinologia)Fundacao de Amparo a Pesquisa do Estado de Minas Gerais (FAPEMIG), BrazilFundacao de Amparo a Pesquisa do Estado de Minas Gerais, Brazil (FAPEMIG)INCTTOX of Conselho Nacional de Desenvolvimento Cientifico e Tecnologico, Brazil (CNPq)INCTTOX of Conselho Nacional de Desenvolvimento Cientifico e Tecnologico, Brazil (CNPq)Instituto Nacional de Salud, PeruInstituto Nacional de Salud, Per