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Immunotherapy for scorpion envenoming in Brazil
PII: S0041-0101(98)00141-X
Toxicon Vol. 36, No. 11, pp. 1507±1513, 1998 # 1998 Elsevier Science Ltd. All rights reserved Printed in Great Britain 0041-0101/98 $19.00 + 0.00
IMMUNOTHERAPY FOR SCORPION ENVENOMING IN BRAZIL N. A. REZENDE,1 C. F. S. AMARAL1 and L. FREIRE-MAIA2* Departamento de ClõÂ nica MeÂdica, Faculdade de Medicina, UFMG, Belo Horizonte, Brazil; and 2 Departamento de Farmacologia, ICB-UFMG, Belo Horizonte, Brazil
1
(Received 12 January 1998; accepted 10 April 1998)
N. A. Rezende, C. F. S. Amaral and L. Freire-Maia. Immunotherapy for scorpion envenoming in Brazil. Toxicon 36, 1507±1513, 1998.ÐUsing the ELISA we have shown that in rats subcutaneously injected with Tityus serrulatus scorpion venom there is a fast absorption rate, a fast and high distribution of venom to tissues, a great anity of the venom for the tissues and a slow elimination half-life. Because of these experimental data, i.v. immunotherapy should be given to patients stung by scorpions as soon as possible after hospital admission. The severity of scorpion envenoming is related to plasma venom concentration (ELISA). The high levels of plasma scorpion venom antigens (ELISA) were cleared 1 h after the infusion of antivenom (5±30 ml of Fab2 fragment) and high concentrations of circulating antivenom persisted for at least 24 h, con®rming the ecacy of immunotherapy to neutralise circulating venom. Some symptoms (e.g. local pain and vomiting) decreased 1 h after the starting of immunotherapy, whereas the other symptoms disappeared from 12±48 h later. Using our tripartite approach of treating scorpion envenoming (symptomatic measures, support of vital functions and serotherapy), the mortality rate was very low (0.28%). # 1998 Elsevier Science Ltd. All rights reserved
INTRODUCTION
Our group has used a tripartite approach to treat scorpion envenoming in Brazil: symptomatic measures, support of vital functions and immunotherapy (Campos et al., 1980; Freire-Maia et al., 1994, 1996). A sensitive and specific enzyme-linked immunosorbent assay (ELISA) was described for detection of Tityus serrulatus venom antigens (ChaÂves-OloÂrtegui et al., 1994). Using this method we estimated the concentrations of Tityus serrulatus scorpion venom and antivenom in plasma of patients stung by scorpions and admitted at `Hospital JoaÄo XXIII', Belo Horizonte, Brazil and performed a pharmacokinetic study of T. serrulatus scorpion venom subcutaneously injected in rats (Rezende et al., 1995; Santana et al., 1996). * Author to whom correspondence should be addressed. 1507
1508
N. A. REZENDE et al. METHODS
Patients who presented to the `Hospital JoaÄo XXIII' with only local pain at the site of the sting (N = 37) and patients with systemic manifestations of envenoming (N = 19) were considered for the study if the scorpions were captured and identified as Tityus serrulatus at the time of admission. Informed consent was obtained from patients or their relatives (Rezende et al., 1995) The clinical findings in severe cases of scorpion envenoming were similar to those previously described by Freire-Maia et al. (1994): local, pain, vomiting, sinus tachycardia, tachypnoea, sudoresis, restlessness, somnolence, abnormal breath sounds, cardiac arrhythmias other than sinus tachycardia or bradycardia, hyperthermia, dehydration, dyspnoea, prostration, heart failure, lung oedema, hypothermia, sinus bradycardia, pallor, tremors, hypertension, decreased capillary perfusion, mental confusion, cardiac arrest and convulsion. Venous blood was sampled for the venom and antivenom ELISA, before antivenom treatment and 1, 6, 12 and 24 h after the starting of immunotherapy. The ELISA for venom (sandwich ELISA) and antivenom (direct ELISA) were carried out blindly according to ChaÂves-OloÂrtegui et al. (1994). The patients who presented systemic manifestations after being stung by scorpions were treated with 5±30 ml of scorpion antivenom (Fab2 fragment, protein content = 7 g/ 100 ml, Fundac° aÄo Ezequiel Dias, Belo Horizonte, M.G., Brazil), infused intravenously over a 10 min period. According to Dr David Toledo (personal communication), each 5 ml of antivenom are sufficient to neutralise 3 mg of scorpion venom in the standard mouse assay. RESULTS AND DISCUSSION
Pharmacokinetics of Tityus serrulatus Our group made a pharmacokinetic study of Tityus serrulatus scorpion venom subcutaneously injected in rats (Santana et al., 1996), using the ELISA described by ChaÂves-OloÂrtegui et al. (1994). Table 1 shows the data obtained. The pharmacokinetic parameters showed a fast absorption rate (Ka=0.058 minÿ1), a fast and high distribution of venom to tissues (t1/2a = 31.50 min and Vdarea=6800.47 mlkgÿ1, respectively), a great Table 1. Pharmacokinetic parameters determined by ELISA after s.c. injection of T. serrulatus scorpion venom in rats (200 mg/100 g) Parameter ÿ1
a (min ) b (minÿ1) t1/2 a (min) t1/2 b (min) Ka (minÿ1) Kct (minÿ1)
Results
Parameter
Results
0.022 0.004 31.50 173.25 0.058 0.056
ÿ1
0.002 0.040 45.47 2380.95 6800.47 1.587
Ktc (min ) Kd (minÿ1) Tmax (min) Vc (mlkgÿ1) Vd area (mlkgÿ1) ClB (mlkgÿ1 minÿ1)
Male Wistar rats (200±250 g) were previously anaesthetized with uretane (140 mg/100 g, i.p.). The values represent the means of six experiments. a and b: apparent ®rst-order fast and slow disposition rate constant, respectively; t1/2a, distribution half-life; t1/2b, elimination half-life; Ka, apparent ®rst-order absorption rate constant; KCT and KTC, apparent ®rst-order rate constants from central compartment to tissue and from tissue to central compartment, respectively; Kd, apparent ®rst-order elimination rate constant from central compartment; Tmax, time needed to reach maximum plasma venom concentration; Vc, volume of the central compartment; Vd area, apparent volume of distribution; ClB, body clearance (according to Santana et al., 1996).
Immunotherapy for Scorpion Envenoming
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Fig. 1. Tityus serrulatus plasma venom concentrations in patients with systemic manifestations of envenoming (moderate±severe cases), in patients with only local pain at the site of sting (mild cases) and in control patients. S.E.M. = standard error of the mean.
affinity of the venom for the tissues (Kct=0.056 minÿ1 and Ktc=0.002 minÿ1) and a slow elimination half-life (t1/2b = 173.25 min). These experimental data (Santana et al., 1996) indicate that i.v. immunotherapy should be started as soon as possible, after the admission of patients to hospital, because of the fast absorption rate, but even in cases of a delay in the treatment (e.g. 3 h), i.v. antivenom should be prescribed, because of the slow elimination half-life.
1510
N. A. REZENDE et al.
Fig. 2. Time±course evolution of plasma venom and antivenom in 18 patients stung by Tityus serrulatus (± W ± indicates venom level; ± r ±, antivenom level, mean2S.E.M.) (according to Rezende et al., 1995).
Severity of clinical envenoming The patients stung by T. serrulatus scorpions admitted at hospital with systemic manifestations of envenoming had higher plasma venom concentration (ELISA) than those with only local pain at the site of the sting (Fig. 1). These data indicate, therefore, that the severity of envenoming in patients stung by Tityus serrulatus scorpion is related to plasma venom concentration (Rezende et al., 1996). Immunotherapy for scorpion envenoming Eighteen patients stung by T. serrulatus and presenting systemic manifestations of envenoming were treated with 5±30 ml of scorpion antivenom (Fab2 fragment), infused i.v. over a 10 min period. Figure 2 shows that the high levels of plasma scorpion venom antigens detected by ELISA were cleared 1 h after starting the immunotherapy. Figure 2 also shows that high antivenom titers were present in plasma for at least 24 h after antivenom infusion. Figure 3 shows that local pain and vomiting decreased 1 h after starting of immunotherapy and that hyperglycaemia was not detected 12 h after the infusion of antivenom. Cardiorespiratory manifestations other than pulmonary oedema in two patients disappeared 6±24 h after immunotherapy. The two patients with pulmonary oedema completely recovered 48 h after immunotherapy (Rezende et al., 1995). Silveira et al. (1995) have shown reversal by polyclonal antibodies of the effects of Tityus serrulatus scorpion toxin on frog sciatic nerve and Revelo et al. (1996) have demonstrated that scorpion antivenom (T. serrulatus) induces an important decrease in venom concentration both in serum and in tissues of mice subcutaneously injected with scorpion venom. Previous experiments had shown that immunoglobulins accelerate in vitro and in vivo the dissociation of a snake toxin from its receptor (Boulain and MeÂnez, 1982; Gatineau et al., 1988; MeÂnez et al., 1992). Therefore, it seems that the reversal of scorpion toxin effects by specific antibodies induced in vitro and in vivo could also be explained by the removal of the bound toxin. Based on these previous experiments, we
Immunotherapy for Scorpion Envenoming
1511
Fig. 3. Clinical and laboratory features of 18 patients stung by Tityus serrulatus before and after treatment with antivenom (according to Rezende et al., 1995).
present the hypothesis that the decrease of symptoms induced by scorpion venom in humans (Fig. 3) is due to neutralisation of circulating venom by antivenom (Fig. 2) and also by removal of bound venom by antivenom. Mortality rate A total of 3860 patients (Fig. 4) stung by Tityus serrulatus scorpions in Brazil were treated by our group using a tripartite approach: symptomatic measures, support of vital functions and immunotherapy (Campos et al., 1980; Freire-Maia et al., 1994). The mortality rate was very low (0.28%). Recent investigations using ELISA for the determination of plasma scorpion venom and antivenom concentrations confirmed
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N. A. REZENDE et al.
Fig. 4. Scorpion envenoming in Brazil. The ®gure shows the number of cases of scorpion envenoming in adults and children over a 16-year period in Belo Horizonte, Brazil. The mortality rate was 1% in children and 0.28% in the total population (adults and children). q, total population; striped area, children; Q, number of deaths (adapted from Freire-Maia and Campos, 1989).
the efficacy of immunotherapy in the treatment of scorpion envenomation in humans (Rezende et al., 1995). Acknowledgements ÐWe thank the Brazilian agencies CNPq, CAPES, FINEP and FAPEMIG for ®nancial aid and fellowships.
REFERENCES Boulain, J.-C. and MeÂnez, A. (1982) Neurotoxin-speci®c immunoglobulins accelerate dissociation of the Neurotoxin-acetylcholine receptor complex. Science 217, 732±733. Campos, J. A., Silva, O. A., Lopez, M. and Freire-Maia, L. (1980) Signs, symptoms and treatment of severe scorpion poisoning in children. In Natural Toxins, eds. D. Eaker and T. Wadstron, pp. 61±68. Pergamon Press, Oxford. ChaÂves-OloÂrtegui, C., Fonseca, S. C. G., Dias, M. B., Campolina, D., Amaral, C. F. S. and Diniz, C. R. (1994) ELISA for the detection of toxic antigens in experimental and clinical envenoming by Tityus serrulatus scorpion venom. Toxicon 32, 1649±1656. Freire-Maia, L. and Campos, J. A. (1989) Pathophysiology and treatment of scorpion poisoning. In Natural Toxins: Characterization, Pharmacology and Therapeutics, eds. C. L. Ownby and G. V. Odell, pp. 139±159. Pergamon Press, Oxford.
Immunotherapy for Scorpion Envenoming
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Freire-Maia, L., Campos, J. A. and Amaral, C. F. S. (1994) Approaches to the treatment of scorpion envenoming. Toxicon 32, 1009±1014. Freire-Maia, L., Campos, J. A. and Amaral, C. F. S. (1996) Treatment of scorpion envenoming in Brazil. In Envenomings and their Treatments, eds. C. Bon and M. Goyon, pp. 301±310. Fondation Marcel Merieux, Paris. Gatineau, E., Lee, C. Y., Fromageot, P. and MeÂnez, A. (1988) Reversal of snake neurotoxin binding to mammalian acetylcholine receptor by speci®c antiserum. European Journal of Biochemistry 171, 535±539. MeÂnez, A., Pillet, L., LeÂonetti, M., Bontems, F. and MailleÂre (1992) Snake toxins as antigens. In Structure of Antigens, ed. M. H. V. Von Regenmortel, Vol. I, pp. 293±320. CRC Press, Boca Raton, U.S.A. Revelo, M. P., Bambirra, E. A., Ferreira, A. P., Diniz, C. R. and ChaÂves-OloÂrtegui, C. (1996) Body distribution of Tityus serrulatus scorpion venom in mice and eects of scorpion antivenom. Toxicon 34, 1119± 1125. Rezende, N. A., Dias, M. B., Campolina, D., ChaÂves-OloÂrtegui, C., Diniz, C. R. and Amaral, C. F. S. (1995) Ecacy of antivenom therapy for neutralizing circulating venom antigens in patients stung by Tityus serrulatus scorpions. American Journal of Tropical Medicine and Hygiene 52, 277±280. Rezende, N. A., ChaÂves-OloÂrtegui, C. and Amaral, C. F. S. (1996) Is the severity of Tityus serrulatus scorpion envenoming related to plasma venom concentrations?. Toxicon 34, 820±823. Santana, G. C., Freire, A. C. T., Ferreira, A. P. L., ChaÂves-OloÂrtegui, C., Diniz, C. R. and Freire-Maia, L. (1996) Pharmacokinetics of Tityus serrulatus scorpion venom determined by enzyme-linked immunosorbent assay in the rat. Toxicon 34, 1063±1066. Silveira, J. N., Heneine, I. F. and BeiraÄo, P. S. L. (1995) Reversion by polyclonal antibodies of a eects of Tityus serrulatus venom on frog sciatic nerve. Toxicology Letters 76, 187±193.
Toxicon Vol. 36, No. 11, pp. 1507±1513, 1998 # 1998 Elsevier Science Ltd. All rights reserved Printed in Great Britain 0041-0101/98 $19.00 + 0.00
IMMUNOTHERAPY FOR SCORPION ENVENOMING IN BRAZIL N. A. REZENDE,1 C. F. S. AMARAL1 and L. FREIRE-MAIA2* Departamento de ClõÂ nica MeÂdica, Faculdade de Medicina, UFMG, Belo Horizonte, Brazil; and 2 Departamento de Farmacologia, ICB-UFMG, Belo Horizonte, Brazil
1
(Received 12 January 1998; accepted 10 April 1998)
N. A. Rezende, C. F. S. Amaral and L. Freire-Maia. Immunotherapy for scorpion envenoming in Brazil. Toxicon 36, 1507±1513, 1998.ÐUsing the ELISA we have shown that in rats subcutaneously injected with Tityus serrulatus scorpion venom there is a fast absorption rate, a fast and high distribution of venom to tissues, a great anity of the venom for the tissues and a slow elimination half-life. Because of these experimental data, i.v. immunotherapy should be given to patients stung by scorpions as soon as possible after hospital admission. The severity of scorpion envenoming is related to plasma venom concentration (ELISA). The high levels of plasma scorpion venom antigens (ELISA) were cleared 1 h after the infusion of antivenom (5±30 ml of Fab2 fragment) and high concentrations of circulating antivenom persisted for at least 24 h, con®rming the ecacy of immunotherapy to neutralise circulating venom. Some symptoms (e.g. local pain and vomiting) decreased 1 h after the starting of immunotherapy, whereas the other symptoms disappeared from 12±48 h later. Using our tripartite approach of treating scorpion envenoming (symptomatic measures, support of vital functions and serotherapy), the mortality rate was very low (0.28%). # 1998 Elsevier Science Ltd. All rights reserved
INTRODUCTION
Our group has used a tripartite approach to treat scorpion envenoming in Brazil: symptomatic measures, support of vital functions and immunotherapy (Campos et al., 1980; Freire-Maia et al., 1994, 1996). A sensitive and specific enzyme-linked immunosorbent assay (ELISA) was described for detection of Tityus serrulatus venom antigens (ChaÂves-OloÂrtegui et al., 1994). Using this method we estimated the concentrations of Tityus serrulatus scorpion venom and antivenom in plasma of patients stung by scorpions and admitted at `Hospital JoaÄo XXIII', Belo Horizonte, Brazil and performed a pharmacokinetic study of T. serrulatus scorpion venom subcutaneously injected in rats (Rezende et al., 1995; Santana et al., 1996). * Author to whom correspondence should be addressed. 1507
1508
N. A. REZENDE et al. METHODS
Patients who presented to the `Hospital JoaÄo XXIII' with only local pain at the site of the sting (N = 37) and patients with systemic manifestations of envenoming (N = 19) were considered for the study if the scorpions were captured and identified as Tityus serrulatus at the time of admission. Informed consent was obtained from patients or their relatives (Rezende et al., 1995) The clinical findings in severe cases of scorpion envenoming were similar to those previously described by Freire-Maia et al. (1994): local, pain, vomiting, sinus tachycardia, tachypnoea, sudoresis, restlessness, somnolence, abnormal breath sounds, cardiac arrhythmias other than sinus tachycardia or bradycardia, hyperthermia, dehydration, dyspnoea, prostration, heart failure, lung oedema, hypothermia, sinus bradycardia, pallor, tremors, hypertension, decreased capillary perfusion, mental confusion, cardiac arrest and convulsion. Venous blood was sampled for the venom and antivenom ELISA, before antivenom treatment and 1, 6, 12 and 24 h after the starting of immunotherapy. The ELISA for venom (sandwich ELISA) and antivenom (direct ELISA) were carried out blindly according to ChaÂves-OloÂrtegui et al. (1994). The patients who presented systemic manifestations after being stung by scorpions were treated with 5±30 ml of scorpion antivenom (Fab2 fragment, protein content = 7 g/ 100 ml, Fundac° aÄo Ezequiel Dias, Belo Horizonte, M.G., Brazil), infused intravenously over a 10 min period. According to Dr David Toledo (personal communication), each 5 ml of antivenom are sufficient to neutralise 3 mg of scorpion venom in the standard mouse assay. RESULTS AND DISCUSSION
Pharmacokinetics of Tityus serrulatus Our group made a pharmacokinetic study of Tityus serrulatus scorpion venom subcutaneously injected in rats (Santana et al., 1996), using the ELISA described by ChaÂves-OloÂrtegui et al. (1994). Table 1 shows the data obtained. The pharmacokinetic parameters showed a fast absorption rate (Ka=0.058 minÿ1), a fast and high distribution of venom to tissues (t1/2a = 31.50 min and Vdarea=6800.47 mlkgÿ1, respectively), a great Table 1. Pharmacokinetic parameters determined by ELISA after s.c. injection of T. serrulatus scorpion venom in rats (200 mg/100 g) Parameter ÿ1
a (min ) b (minÿ1) t1/2 a (min) t1/2 b (min) Ka (minÿ1) Kct (minÿ1)
Results
Parameter
Results
0.022 0.004 31.50 173.25 0.058 0.056
ÿ1
0.002 0.040 45.47 2380.95 6800.47 1.587
Ktc (min ) Kd (minÿ1) Tmax (min) Vc (mlkgÿ1) Vd area (mlkgÿ1) ClB (mlkgÿ1 minÿ1)
Male Wistar rats (200±250 g) were previously anaesthetized with uretane (140 mg/100 g, i.p.). The values represent the means of six experiments. a and b: apparent ®rst-order fast and slow disposition rate constant, respectively; t1/2a, distribution half-life; t1/2b, elimination half-life; Ka, apparent ®rst-order absorption rate constant; KCT and KTC, apparent ®rst-order rate constants from central compartment to tissue and from tissue to central compartment, respectively; Kd, apparent ®rst-order elimination rate constant from central compartment; Tmax, time needed to reach maximum plasma venom concentration; Vc, volume of the central compartment; Vd area, apparent volume of distribution; ClB, body clearance (according to Santana et al., 1996).
Immunotherapy for Scorpion Envenoming
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Fig. 1. Tityus serrulatus plasma venom concentrations in patients with systemic manifestations of envenoming (moderate±severe cases), in patients with only local pain at the site of sting (mild cases) and in control patients. S.E.M. = standard error of the mean.
affinity of the venom for the tissues (Kct=0.056 minÿ1 and Ktc=0.002 minÿ1) and a slow elimination half-life (t1/2b = 173.25 min). These experimental data (Santana et al., 1996) indicate that i.v. immunotherapy should be started as soon as possible, after the admission of patients to hospital, because of the fast absorption rate, but even in cases of a delay in the treatment (e.g. 3 h), i.v. antivenom should be prescribed, because of the slow elimination half-life.
1510
N. A. REZENDE et al.
Fig. 2. Time±course evolution of plasma venom and antivenom in 18 patients stung by Tityus serrulatus (± W ± indicates venom level; ± r ±, antivenom level, mean2S.E.M.) (according to Rezende et al., 1995).
Severity of clinical envenoming The patients stung by T. serrulatus scorpions admitted at hospital with systemic manifestations of envenoming had higher plasma venom concentration (ELISA) than those with only local pain at the site of the sting (Fig. 1). These data indicate, therefore, that the severity of envenoming in patients stung by Tityus serrulatus scorpion is related to plasma venom concentration (Rezende et al., 1996). Immunotherapy for scorpion envenoming Eighteen patients stung by T. serrulatus and presenting systemic manifestations of envenoming were treated with 5±30 ml of scorpion antivenom (Fab2 fragment), infused i.v. over a 10 min period. Figure 2 shows that the high levels of plasma scorpion venom antigens detected by ELISA were cleared 1 h after starting the immunotherapy. Figure 2 also shows that high antivenom titers were present in plasma for at least 24 h after antivenom infusion. Figure 3 shows that local pain and vomiting decreased 1 h after starting of immunotherapy and that hyperglycaemia was not detected 12 h after the infusion of antivenom. Cardiorespiratory manifestations other than pulmonary oedema in two patients disappeared 6±24 h after immunotherapy. The two patients with pulmonary oedema completely recovered 48 h after immunotherapy (Rezende et al., 1995). Silveira et al. (1995) have shown reversal by polyclonal antibodies of the effects of Tityus serrulatus scorpion toxin on frog sciatic nerve and Revelo et al. (1996) have demonstrated that scorpion antivenom (T. serrulatus) induces an important decrease in venom concentration both in serum and in tissues of mice subcutaneously injected with scorpion venom. Previous experiments had shown that immunoglobulins accelerate in vitro and in vivo the dissociation of a snake toxin from its receptor (Boulain and MeÂnez, 1982; Gatineau et al., 1988; MeÂnez et al., 1992). Therefore, it seems that the reversal of scorpion toxin effects by specific antibodies induced in vitro and in vivo could also be explained by the removal of the bound toxin. Based on these previous experiments, we
Immunotherapy for Scorpion Envenoming
1511
Fig. 3. Clinical and laboratory features of 18 patients stung by Tityus serrulatus before and after treatment with antivenom (according to Rezende et al., 1995).
present the hypothesis that the decrease of symptoms induced by scorpion venom in humans (Fig. 3) is due to neutralisation of circulating venom by antivenom (Fig. 2) and also by removal of bound venom by antivenom. Mortality rate A total of 3860 patients (Fig. 4) stung by Tityus serrulatus scorpions in Brazil were treated by our group using a tripartite approach: symptomatic measures, support of vital functions and immunotherapy (Campos et al., 1980; Freire-Maia et al., 1994). The mortality rate was very low (0.28%). Recent investigations using ELISA for the determination of plasma scorpion venom and antivenom concentrations confirmed
1512
N. A. REZENDE et al.
Fig. 4. Scorpion envenoming in Brazil. The ®gure shows the number of cases of scorpion envenoming in adults and children over a 16-year period in Belo Horizonte, Brazil. The mortality rate was 1% in children and 0.28% in the total population (adults and children). q, total population; striped area, children; Q, number of deaths (adapted from Freire-Maia and Campos, 1989).
the efficacy of immunotherapy in the treatment of scorpion envenomation in humans (Rezende et al., 1995). Acknowledgements ÐWe thank the Brazilian agencies CNPq, CAPES, FINEP and FAPEMIG for ®nancial aid and fellowships.
REFERENCES Boulain, J.-C. and MeÂnez, A. (1982) Neurotoxin-speci®c immunoglobulins accelerate dissociation of the Neurotoxin-acetylcholine receptor complex. Science 217, 732±733. Campos, J. A., Silva, O. A., Lopez, M. and Freire-Maia, L. (1980) Signs, symptoms and treatment of severe scorpion poisoning in children. In Natural Toxins, eds. D. Eaker and T. Wadstron, pp. 61±68. Pergamon Press, Oxford. ChaÂves-OloÂrtegui, C., Fonseca, S. C. G., Dias, M. B., Campolina, D., Amaral, C. F. S. and Diniz, C. R. (1994) ELISA for the detection of toxic antigens in experimental and clinical envenoming by Tityus serrulatus scorpion venom. Toxicon 32, 1649±1656. Freire-Maia, L. and Campos, J. A. (1989) Pathophysiology and treatment of scorpion poisoning. In Natural Toxins: Characterization, Pharmacology and Therapeutics, eds. C. L. Ownby and G. V. Odell, pp. 139±159. Pergamon Press, Oxford.
Immunotherapy for Scorpion Envenoming
1513
Freire-Maia, L., Campos, J. A. and Amaral, C. F. S. (1994) Approaches to the treatment of scorpion envenoming. Toxicon 32, 1009±1014. Freire-Maia, L., Campos, J. A. and Amaral, C. F. S. (1996) Treatment of scorpion envenoming in Brazil. In Envenomings and their Treatments, eds. C. Bon and M. Goyon, pp. 301±310. Fondation Marcel Merieux, Paris. Gatineau, E., Lee, C. Y., Fromageot, P. and MeÂnez, A. (1988) Reversal of snake neurotoxin binding to mammalian acetylcholine receptor by speci®c antiserum. European Journal of Biochemistry 171, 535±539. MeÂnez, A., Pillet, L., LeÂonetti, M., Bontems, F. and MailleÂre (1992) Snake toxins as antigens. In Structure of Antigens, ed. M. H. V. Von Regenmortel, Vol. I, pp. 293±320. CRC Press, Boca Raton, U.S.A. Revelo, M. P., Bambirra, E. A., Ferreira, A. P., Diniz, C. R. and ChaÂves-OloÂrtegui, C. (1996) Body distribution of Tityus serrulatus scorpion venom in mice and eects of scorpion antivenom. Toxicon 34, 1119± 1125. Rezende, N. A., Dias, M. B., Campolina, D., ChaÂves-OloÂrtegui, C., Diniz, C. R. and Amaral, C. F. S. (1995) Ecacy of antivenom therapy for neutralizing circulating venom antigens in patients stung by Tityus serrulatus scorpions. American Journal of Tropical Medicine and Hygiene 52, 277±280. Rezende, N. A., ChaÂves-OloÂrtegui, C. and Amaral, C. F. S. (1996) Is the severity of Tityus serrulatus scorpion envenoming related to plasma venom concentrations?. Toxicon 34, 820±823. Santana, G. C., Freire, A. C. T., Ferreira, A. P. L., ChaÂves-OloÂrtegui, C., Diniz, C. R. and Freire-Maia, L. (1996) Pharmacokinetics of Tityus serrulatus scorpion venom determined by enzyme-linked immunosorbent assay in the rat. Toxicon 34, 1063±1066. Silveira, J. N., Heneine, I. F. and BeiraÄo, P. S. L. (1995) Reversion by polyclonal antibodies of a eects of Tityus serrulatus venom on frog sciatic nerve. Toxicology Letters 76, 187±193.