Age effects on the pharmacokinetics of tityustoxin from Tityus serrulatus scorpion venom in rats

The pharmacokinetics of scorpion venom and its toxins has been investigated in experimental models using adult animals, although, severe scorpion accidents are associated more frequently with children. We compared the effect of age on the pharmacokinetics of tityustoxin, one of the most active principles of Tityus serrulatus venom, in young male/female rats (21-22 days old, N = 5-8) and in adult male rats (150-160 days old, N = 5-8). Tityustoxin (6 µg) labeled with 99mTechnetium was administered subcutaneously to young and adult rats. The plasma concentration vs time data were subjected to non-compartmental pharmacokinetic analysis to obtain estimates of various pharmacokinetic parameters such as total body clearance (CL/F), distribution volume (Vd/F), area under the curve (AUC), and mean residence time. The data were analyzed with and without considering body weight. The data without correction for body weight showed a higher Cmax (62.30 ± 7.07 vs 12.71 ± 2.11 ng/ml, P < 0.05) and AUC (296.49 ± 21.09 vs 55.96 ± 5.41 ng h-1 ml-1, P < 0.05) and lower Tmax (0.64 ± 0.19 vs 2.44 ± 0.49 h, P < 0.05) in young rats. Furthermore, Vd/F (0.15 vs 0.42 l/kg) and CL/F (0.02 ± 0.001 vs 0.11 ± 0.01 l h-1 kg-1, P < 0.05) were lower in young rats. However, when the data were reanalyzed taking body weight into consideration, the Cmax (40.43 ± 3.25 vs 78.21 ± 11.23 ng kg-1 ml-1, P < 0.05) and AUC (182.27 ± 11.74 vs 344.62 ± 32.11 ng h-1 ml-1, P < 0.05) were lower in young rats. The clearance (0.03 ± 0.002 vs 0.02 ± 0.002 l h-1 kg-1, P < 0.05) and Vd/F (0.210 vs 0.067 l/kg) were higher in young rats. The raw data (not adjusted for body weight) strongly suggest that age plays a pivotal role in the disposition of tityustoxin. Furthermore, our results also indicate that the differences in the severity of symptoms observed in children and adults after scorpion envenomation can be explained in part by differences in the pharmacokinetics of the toxin.

Standardization of an enzyme linked immunosorbent assay (ELISA) for detecting circulating toxic venom antigens in patients stung by the scorpion Tityus serrulatus

The sensitivity and specificity of an enzyme-linked immunosorbent assay (ELISA) for the detection of circulating antigens from toxic components of Tityus serrulatus scorpion venom was determined in patients stung by T. serrulatus before antivenom administration. Thirty-seven patients were classified as mild cases and 19 as moderate or severe cases. The control absorbance in the venom assay was provided by serum samples from 100 individuals of same socioeconomic group and geographical area who had never been stung by scorpions or treated with horse antisera. The negative cutoff value (mean + 2 SD) corresponded to a venom concentration of 4.8 ng/ml. Three out of the 100 normal sera were positive, resulting in a specificity of 97%. The sensitivity of the ELISA when all cases of scorpion sting were included was 39.3%. When mild cases were excluded, the sensitivity increased to 94.7%. This study showed that this ELISA can be used for the detection of circulating venom toxic antigens in patients with systemic manifestations following. T. serrulatus sting but cannot be used for clinical studies in mild cases of envenoming since the test does not discriminate mild cases from control patients.

Effect of toxin-g from Tityus serrulatus scorpion venom on gastric emptying in rats

The effect of toxin-g 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-g 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-g /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-g /kg compared to control values. The responses to these two doses were significantly different after 8 h post-venom. Toxin-g (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-g may induce a rapid, intense and sustained inhibition of gastric emptying 0.25 to 48 h after envenomation.

Inhibition of gastric emptying and intestinal transit in anesthetized rats by a Tityus serrulatus scorpion toxin

The effects of a fraction (T1) of Tityus serrulatus scorpion venom prepared by gel filtration on gastric emptying and small intestinal transit were investigated in male Wistar rats. Fasted animals were anesthetized with urethane, submitted to tracheal intubation and right jugular vein cannulation. Scorpion toxin (250 µg/kg) or saline was injected iv and 1 h later a bolus of saline (1.0 ml/100 g) labeled with 99m technetium-phytate (10 MBq) was administered by gavage. After 15 min, animals were sacrificed and the radioactivity remaining in the stomach was determined. Intestinal transit was evaluated by instillation of a technetium-labeled saline bolus (1.0 ml) through a cannula previously implanted in the duodenum. After 60 min, the progression of the marker throughout 7 consecutive gut segments was estimated by the geometric center method. Gastric retention of the liquid test meal in rats injected with scorpion toxin (median: 88%; range: 52-95%) was significantly higher (P<0.02) than in controls (54%; 21-76%), an effect which was not modified by gastric secretion blockade with ranitidine. The progression of the isotope marker throughout the small intestine was significantly slower (P<0.05) in rats treated with toxin (1.2; 1.0-2.5) than in control animals (2.3; 1.0-3.2). Inhibition of both gastric emptying and intestinal transit in rats injected with scorpion toxin suggests an increased resistance to aboral flow, which might be caused by abnormal neurotransmitter release or by the local effects of venom on smooth muscle cells.

Acidente por Tityus serrulatus e suas implicações epidemiológicas no Rio Grande do Sul

Relata-se o primeiro caso de acidente por escorpião Tityus serrulatus ocorrido em Março de 2001, em Porto Alegre, Rio Grande do Sul, Brasil. Um paciente masculino de 21 anos, ao manipular produtos hortifrutigranjeiros provenientes de outros estados do Brasil, foi picado na mão por um escorpião Tityus serrulatus com repercussões locais e sistêmicas, necessitando usar soro anti-escorpiônico. O caso foi considerado relevante em termos epidemiológicos, no sul do Brasil.

A comparative study of severe scorpion envenomation in children caused by Tityus bahiensis and Tityus serrulatus

From January 1984 to May 1994, 17 of 239 children under 15 years old stung by Tityus serrulatus (15.1%) or Tityus bahiensis (84.9%) presented severe envenoming. Of these 17 patients (1-11 years old; median=2 yr) 14 were stung by T.serrulatus and three by T.bahiensis. All of them received scorpion antivenom i.v. at times ranging from 45 min. to 5 h after the accident (median=2h). On admission, the main clinical manifestations and laboratory and electrocardiographic changes were: vomiting (17), diaphoresis (15), tachycardia (14), prostration (10), tachypnea (8), arterial hypertension (7), arterial hypotension (5), tremors (5), hypothermia (4), hyperglycemia (17), leukocytosis (16/16), hypokalemia (13/17), increased CK-MB enzyme activity (>6% of the total CK, 11/12), hyperamylasemia (11/14), sinusal tachycardia (16/17) and a myocardial infarction-like pattern (11/17). Six patients stung by T.serrulatus had depressed left ventricular systolic function assessed by means of echocardiography. Of these, five presented pulmonary edema and four had shock. A child aged two-years old presented severe respiratory failure and died 65 h after being stung by T.serrulatus. Severe envenomations caused by T.serrulatus were 26.2 times more frequent than those caused by T.bahiensis (p<0.001).

Programa de controle de surto de escorpião Tityus serrulatus, Lutz e Mello 1922, no município de Aparecida, SP (Scorpiones, Buthidae)

Os autores propuseram para o município de Aparecida, vale do Rio Paraíba, SP, região endêmica do Tityus serrulatus, um programa de controle do escorpionismo. Foram estudados a presença de focos do escorpião no campo e na cidade, as alterações ambientais periféricas à zona urbana e os novos ambientes de procriação e dispersão destes artrópodes. Além disso, foram avaliados os problemas básicos de infra-estrutura, tais como o acondicionamento e a coleta do lixo urbano público e domiciliar, o saneamento básico (esgotos e galerias pluviais) e a situação dos terrenos baldios e as construções da zona urbana. Após estudo epidemiológico, foram propostas medidas educativas, que constaram da confecção e distribuição de folhetos, de mutirões de limpeza, de visitas domiciliares e do engajamento de professores e alunos da rede de ensino pública e privada na campanha. Nos locais onde existiam focos de alto risco, em especial nas pré-escolas, foi proposto o emprego do controle químico. Dentro das normas sanitárias vigentes para a zona urbana, foi proposto ainda, o uso de predadores naturais no combate. Os autores concluem que as ações devem ser integradas e continuadas de forma ininterrupta por vários anos e propõem ação conjunta com a campanha da dengue. A instituição de uma semana por ano dedicada ao estudo do escorpionismo nas escolas dos municípios onde ocorre o problema seria uma medida educativa que viria contribuir sobremaneira para a prevenção dos acidentes e controle do escorpionismo.

Clinical update on scorpion envenoming

Abstract: Scorpion stings are currently the leading cause of venom-related injury to humans in Brazil and are a significant public health problem globally. Only scorpions of the Tityus genus are of medical importance in Brazil, and Tityus serrulatus is responsible for the most serious envenomations and deaths. The toxic effects of scorpion envenomation are due to a massive release of sympathetic and parasympathetic neurotransmitters; the severity is related to cardiac and hemodynamic changes, with cardiogenic shock and pulmonary edema contributing to the main causes of death. The pathophysiology of cardiac involvement has been discussed for decades and has been attributed to adrenergic discharge and a possible toxic effect of venom on the myocardium, while acute pulmonary edema may have a cardiogenic and/or non-cardiogenic origin. Currently, the clinical data point to catecholamine excess as the cause for reversible scorpion cardiomyopathy . These data include electrocardiographic changes, profiling of cardiac enzymes and troponin I, echocardiographic data with global or regional left ventricle dysfunction, and myocardial perfusion alterations compatible with spasm in the coronary microcirculation. Furthermore, recent data on cardiac magnetic resonance imaging findings, which are similar to those observed for stress-induced cardiomyopathy, have also been linked to catecholamine excess. The efficiency of antivenom serum treatment is controversial in the literature. Our experience in Brazil is that the management of patients with systemic manifestations of scorpion stings is based on three approaches, all of which are extremely important. These include symptomatic treatment, antivenom serum, and cardiorespiratory support.

Induction of neutralizing antibodies in mice immunized with scorpion toxins detoxified by liposomal entrapment

The possibility of producing neutralizing antibodies against the lethal effects of scorpion toxins was evaluated in the mouse model by immunization with an immunogen devoid of toxicity. A toxic fraction (5 mg) from the venom of the scorpion Tityus serrulatus was entrapped in sphingomyelin-cholesterol liposomes. The liposomes were treated for 1 h at 37oC with a 1% (w/w) trypsin solution in 0.2 M sodium carbonate buffer, pH 8.3. This treatment led to a strong reduction in venom toxicity. Immunization was performed as follows: mice were injected sc with 20 µg of the liposome-entrapped toxic fraction on days 1 and 21 and a final injection (20 µg) was administered ip on day 36. After injection of the immunogen, all mice developed an IgG response which was shown to be specific for the toxic antigen. The antibodies were measured 10 days after the end of the immunization protocol. In an in vitro neutralization assay we observed that pre-incubation of a lethal dose of the toxic fraction with immune serum strongly reduced its toxicity. In vivo protection assays showed that mice with anti-toxin antibodies could resist the challenge with the toxic fraction, which killed, 30 min after injection, all non-immune control mice

Effect of scorpion toxin on the enterochromaffin-like cells in normal and Trypanosoma cruzi-infected rats: a morphological study

Intravenous injection of scorpion toxin (Tityus serrulatus) in normal and Trypanosoma cruzi infected rats did not cause ultrastructural morphologic changes on enterochromaffin-like (ECL) cells of the stomach, although it induced a significant increase of the gastric secretion. Our data seem to indicate that gastric ECL cells structure is not affected by stimulation with scorpion toxin or by acute infection with T. cruzi in the rat.

Escorpionismo em Belo Horizonte, MG: um estudo retrospectivo

Os escorpiões (Arachnida, Scorpiones), especialmente na área urbana, devido à grande densidade demográfica e possibilidade de confronto, representam risco à saúde pública. A espécie Tityus serrulatus é a mais importante, do ponto de vista médico, causando o maior número de acidentes. Objetivou-se levantar dados epidemiológicos e a ocorrência de acidentes escorpiônicos em Belo Horizonte, entre 1990 e 1997. Os dados foram obtidos no Hospital de Pronto Socorro João XXIII. Ocorreram 3265 acidentes, sendo a maioria em 1996. Aconteceram 6 acidentes fatais. Com maior incidência nos meses de janeiro, o sexo masculino, os membros superiores e a faixa etária entre 25 e 65 anos, foram os mais atingidos. Os resultados constituem importante subsídio para o controle do escorpionismo, pois delimitam as áreas mais atingidas e o perfil dos acidentados, permitindo campanhas educativas e de prevenção mais eficientes.

Contribuição para o conhecimento da intoxicação pelo veneno dos "escorpiões"

Nous avons travaillé à Bello Horizonte, Etat de Minas, avec le venin de 4 espèces de Scorpions: Tityus bahiensis (C. L. KOCK, 1836). Tityus serrulatus (LUTZ-MELLO, 1922). Tityus dorsomaculatus (LUTZ – MELLO, 1922). Bothriurus (espèce em étude), sur un total de 13.640 individus. Nous avons essayé et observe l’action du venin sur 97 espèces differentes d’êtres vivants – depuis les chlamydozoaires jusqu’à l’«Homo sapiens». Nous avons cherché à déterminer une unité toxique «plus précise, plus régulierè». Les étalons dits «unité vésicule», «unité morsure» sont inconstants et sans rigueur. Tout au plus, peuvent ils server à l’étude de l’action générale du venin, et cela meme, dans certains cas seulement. Nous avons employé la pesée pour determiner l’unité toxique. Ce qui est important pour qui étudie ces sujets ce n’est pás lê nombre de vésicules, mais bien la quantité de venin humide ou desséché qu’elles contiennent. La balance, pour notre travail, est um moyen indicateur de bien plus grande précision que la «vésicule» ou la «morsure». Nous sommes parvenus à prouver qu’il existe une relation constante entre le poid brut des vésicules et la quantité de venin humide ou desséché qu’elles contiennent dans leur intérieur. Donc em pesant les vésicules, nous pesons indirectement le venin. Peu nous importe qu’il y ait 10 ou 100 vésicules. Il nous importe seulement de savoir combien elles pèsent, et de déterminer par ce fait, la quantité proportionnelle de vain pur. La technique générale est la suivante: Nous pesons um certain nombre de vésicules. Nous triturons ensuite, dans um mortier stérilisé et nous emulsionnons, par l’addition consécutive d’eau distillée, stérilisée. Nous filtrons l’émulsion sur le papier filtre employé em chimie, préalablement taré et desséché dans une atmosphere de chlorure de calcium. Après le filtrage on sèche à nouveau les papiers filtre employés d'abord à l'étuve et ensuite dans la même atmosphère de chlorure de calcium. Nous pesons plusieurs fois et on obtient la moyenne de ces pesées. On soustrait de cette dernière pesée le taux des substances non venimeuses, glandulaires, également dissoutes et calculées à 23 du poids brut et celles retenues par les papiers,-on obtient ainsi la moyenne réelle du venin pur contenu dans les vésicules utilisèés. Une simple divisiôn suffit pour fixer la moyenne de chacune. Ces données ont été vérifiées par les expériences faites avec du venin pur, largement obtenu dans notre Laboratoire. Nous avons trouvé de la sorte pour une vésicule de Tityus serrulatus: 0,gr.000,386 de T. bahiensis: 0,gr.001.261.24 de venin pur ce qui donne. 7/15,96 pour la 1ère. 1/8,36 pour la 2ème du poids sec de chaque vésicule. Le poids sec, pour une moyenne obtenue de 1.000 vésicules, fut de 0,gr.008,236 pour Tityus bahiensis. Maximum 0,gr.011. Minimum 0,gr.004.4 pour chacun. Pour Tityus serrulatus, en 1.049 vésicules le poids fut de 0,gr.006,08. Maximum 0,gr.014.03. Minimum 0,gr.003,1 pour chacun. C'est pour cette raison que l'unité-vésicule est incertaine. 2 poules A et B.; l'une, A, pesant 2 K.030 gr. reçoit dans une veinè, une émulsion en sèrum physiologique à 8,50/%, stérilisé, de 19 vésicules totales de Tityus serrulatus, et présence de légers phénomènes toxiques. L'autre, B, pesant 2 K.320 gr. meurt avec tous les phénomènes classiques de l'empoisonnement, par l'injection endoveineuse del'émulsion de 16 vésicules totales de venin de Tityus serrulatus! Les premières 19 vésicules pesaient 0,gr.58; les 16 derniéres-84 milligrammes. Les premières contenaient 0,gr.003. 634 et les secondes 0,gr.005.263 de venin pur! La moyenne obtenue de 6346 scorpions, (entre T. bahiensis et T. serrulatus) nous a fourni pour chacun: 0,gr.000,131,53 de venin pur, par piqûre. Si l'on spécifie: Pour 5.197 T. bahiensis. La moyenne pour une piqûre est 0,gr.000.106.15. Pour 1.149 T. serrulatus, la moyenne pour une piqûre est.......0,gr.000.246.30. La quantité a varié, selon les individus, de 0,gr.000.035.71, à 0,gr.000.436.01 de venin pur, pour une piqûre. D'après ce qui vient d'étre dit, on peut voir combien la quantité de venin éjaculé varie, chaque fois, chez les scorpions. L'unité-piqûre ne peut done pas ètre utiliseé pour des expériences dèlicates. Le mieux est de se servir de venin pur, et c'est ce que nous avons fait pour les expériences minutieuses. Quand on n'en possède pas, on peut établir pour chaque série des expériences à tenter-la dose minima mortelle en poids (grammes et fractions) de vésicules. D'après les bases ici consignées, et avec une trés petite erreur, on peut calculer la quantité de venin pur de cette dóse. Ce calcul est d'ailleurs dispensable. On peut s'en rapporter simplement au poids sec des vésicules totales et dire que la D. m. m. est de tant de milligr. secs. Comme le venin se conserve mal dans les vésicules, il faut, dans ce procédé, doser la D. m. m. toutes les fois que l'on veut procéder á une sériê d'expériences. Le venin desséché rappelle, d'après le temps de conservations au Laboratoire, celui de Crotatus terrificus et celui des Lachesis (quand il est vieux). Il est retenu au passage en partie, par les bougies Berkfeld et Chamberland. La conservation en état de dessication est la meilleure. Ainsi gardé, à l'abri de la lumierè, aux approches de 0,gr., pendant 8 mois, il perd à peine 1,2 à 1,4 de sa valeur primitive. L'echauffement à 100 gr. trouble une dissolution de venin dans l'eau distilleé; sans atteindre toutefois son pouvoir toxique, quand on l'injecte par la voie intra-cérébrale. Nous avons fait l'experience par 11 voies diverses. Sur des animaux sensibles, nous n'avons pas obtenu de phénomènes toxiques, apparemment, par les voies suivantes: 1) buccale; 2) gastrique; 3) rectale; 4) chambre oculaire antérieure; 5) cornéenne; 6) trachéenne; 7) meningée {sur; intra; 8) simple contact, bien que direct, avec le systemè nerveux central. La gravité des phènomènes décroît suivant l'échelle ci-dessous: 1) intra-cérébrale...

O combate ao escorpionismo

O outor estuda os processos de combate aos acidentes pelas picadas dos escorpiões, visando: a) Profilaxia e b) Terapêutica. Refere-se à luta nos campos e nas cidades e aqui, dentro e fora dos domicílios. Assinala os diferentes métodos para o combate a êsses artrópodos peçonhentos. Fala na luta direta, indireta, na vacinação pelo anaveneno, na propaganda pela educação racional da população contra o perigo dos acidentes. Refere-se à "cata" dos escorpiões, à luta química, ao emprêgo de animais escorpiófagos, á feitura de casas e jardins anti-escorpiões. Na primeira parte do presente trabalho o autor trata da luta química pelo d. D. T. contra os tityus bahiensis e serrulatus, concluindo que êste corpo químico é um poderoso elemento de luta contra êstes escorpiões. Na segunda parte do trabalho, o autor trata da terapêutica dos acidentes. Mostra a necessidade do emprêgo convenientemente da única terapêutica racional e eficaz contra a intoxicação escorpiônica: a soroterapia específica. Assinala a necessidade da injeção de doses maciças de um sôro de alta valência, preparado em bovídeos, para evitar o mais possível o choque anafilático, no menor tempo possível após as picadas. Aconselha o empêgo de anaveneno escorpiônico, para vacinação principalmente de crianças de baixa idade, nos lugares fortemente infestados pelos escorpiões (principalmente Tityus serrulatus), maximé quando no local não houver sôro anti-escorpiônico específico, como meio preventivo contra a gravidade das intoxicações. Cita finalmente os trabalhos recentes de Grasset, Shaasfsma e Hodgson, na África do Sul, que confirmam muitas idéias do autor e mostram a unidade universal do síndromo escorpiônico descrito no Brasil.

Envenenamento por Tityus stigmurus (Scorpiones; Buthidae) no Estado da Bahia, Brasil

A presente investigação é um estudo descritivo dos aspectos clínicos dos acidentes causados pelo escorpião Tityus stigmurus no Estado da Bahia, Brasil. Foram analisados 237 casos confirmados, tratados pelo Centro de Informações Antiveneno da Bahia (CIAVE), no período de 1982-1995. O envenenamento por T. stigmurus caracterizou-se por manifestações locais: dor (94,4%), dormência (30%), edema (17,8%), eritema (17,8%) e parestesia (15,6%) e gerais: cefaléia (14%), vômitos (4,4%) e sudorese (3,3%). A maioria dos envenenamentos (94%) foi leve e todos evoluíram para cura. A ausência de letalidade, com o restabelecimento dos pacientes, inclusive casos graves, sugere a eficácia do tratamento com o antiveneno específico, apesar do veneno desta espécie não estar presente no pool de produção nacional do soro. Há necessidade de revisão dos critérios regionais nos esquemas atuais de soroterapia. Os dados apontam para a semelhança da gravidade do envenenamento por T. serrulatus, com exceção da ocorrência de óbitos e complicações sistêmicas.

Severe scorpion envenomation in Brazil: clinical, laboratory and anatomopathological aspects

Scorpion stings in Brazil are important not only because of their incidence but also for their potential ability to induce severe, and often fatal, clinical situations, especially among children. In this report we present the clinical and laboratory data of 4 patients victims of scorpion stings by T. serrulatus, who developed heart failure and pulmonary edema, with 3 of them dying within 24 hours of the sting. Anatomopathologic study of these patients revealed diffuse areas of myocardiocytolysis in addition to pulmonary edema. The surviving child presented enzymatic, electrocardiographic and echocardiographic changes compatible with severe cardiac involvement, which were reversed within 5 days. These findings reinforce the need for continuous monitoring of patients with severe scorpion envenoming during the hours immediately following the sting.