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PubMed2001

Low metabolic rate in scorpions: implications for population biomass and cannibalism.

Scorpions are abundant in arid areas, where their population biomass may exceed that of vertebrates. Since scorpions are predators of small arthropods and feed infrequently across multi-year lifespans, a parsimonious explanation for their observed, anomalously high biomass may be a depressed metabolic rate (MR). We tested the hypothesis that scorpion MR is significantly depressed compared with that of other arthropods, and we also measured the temperature-dependence of the MR of scorpions to quantify the interaction between large seasonal variations in desert temperatures and MR and, thus, long-term metabolic expenditure. Scorpion MR increased markedly with temperature (mean Q(10)=2.97) with considerable inter-individual variation. At 25 degrees C, the MRs of scorpions from two genera were less than 24 % of those of typical terrestrial arthropods (spiders, mites, solpugids and insects) of the same mass. It is likely, therefore, that the low MR of scorpions contributes to their high biomass in arid areas. The combination of high biomass and high production efficiency associated with low MR may also favor a density-dependent "transgenerational energy storage" strategy, whereby juveniles are harvested by cannibalistic adults that may be closely related to their juvenile prey.

Animals↗
PubMed2001

[The hygienic examination and quality research of Chinese crude drug scorpion].

We selected the method of hygienic test to determinate the infection of colibacilli, salmonelli, mixed bacteria, mould fungus and yeasts on Chinese crude drug scorpion from 29 commerical samples in different storaged period, habitats and commerical standard. The results showed there were not colibacilli and salmonelli in all 29 samples, but infectious mixed bacteria rate is 100%, which is 2.1 times more than salty scorpion in 29 tested samples, and the infectious fungi rate is 72.4%. The fungi of salty scorpion is 15% more than fresh scorpion. The quantity of infected yeasts on salty scorpion is much more than scorpion. There are 4 species of fungi such as Alternaria neesex Wallroth, Aspergillus fumigatus Fresenius, Nocarcia sp. and Tricophyton violaceum Sabouraud. Because of infectious pathogenic bacteria rate is so high, we suggest to increase the item of hygienic test to control the quality of crude drug scorpion and strengthen the administration of commerical drugs, so as to reduce the contaminative condition.

Animals↗
PubMed1994

Scorpion envenoming and the role of insulin.

Scorpion envenoming results in a severe autonomic storm with a massive release of catecholamines, increased angiotensin II and inhibition of insulin secretion. These hormonal alterations could be responsible for the pathogenesis of a variety of clinical manifestations. Under these conditions, scorpion envenoming essentially results in a syndrome of fuel-energy deficits and an inability to utilize the existing metabolic substrates by vital organs causing multi-organ system failure and death. Based on our animal experiments in which insulin administration reversed the metabolic and ECG changes induced by scorpion envenoming and treating the poisonous scorpion sting victims with insulin, we consider that insulin has a primary metabolic role in preventing and reversing the cardiovascular, haemodynamic, and neurological manifestations and pulmonary oedema induced by scorpion envenoming. The use of continuous infusion of regular crystalline insulin at the rate of 0.3 U/g glucose and glucose at the rate of 0.1 g/kg/hr, with supplementation of potassium as needed and maintenance of fluid electrolytes and acid-based balance, has become a routine protocol in our setting for treating the victims of scorpion envenoming.

Angiotensin II↗
PubMed2000

Mode of action and application of Scorpion primers to mutation detection.

Scorpion primers can be used to detect PCR products in homogeneous solution. Their structure promotes a unimolecular probing mechanism. We compare their performance with that of the same probe sequence forced to act in a bimolecular manner. The data suggest that Scorpions indeed probe by a unimolecular mechanism which is faster and more efficient than the bimolecular mechanism. This mechanism is not dependent on enzymatic cleavage of the probe. A direct comparison between Scorpions, TaqMan and Molecular Beacons on a Roche LightCycler indicates that Scorpions perform better, particularly under fast cycling conditions. Development of a cystic fibrosis mutation detection assay shows that Scorpion primers are selective enough to detect single base mutations and give good sensitivity in all cases. Simultaneous detection of both normal and mutant alleles in a single reaction is possible by combining two Scorpions in a multiplex reaction. Such favourable properties of Scorpion primers should make the technology ideal in numerous applications.

Alleles↗
PubMed1999

NMR structures and activity of a novel alpha-like toxin from the scorpion Leiurus quinquestriatus hebraeus.

NMR structures of a new toxin from the scorpion Leiurus quinquestriatus hebraeus (Lqh III) have been investigated in conjunction with its pharmacological properties. This toxin is proposed to belong to a new group of scorpion toxins, the alpha-like toxins that target voltage-gated sodium channels with specific properties compared with the classical alpha-scorpion toxins. Electrophysiological analysis showed that Lqh III inhibits a sodium current inactivation in the cockroach axon, but induces in addition a resting depolarization due to a slowly decaying tail current atypical to other alpha-toxin action. Binding studies indicated that radiolabeled Lqh III binds with a high degree of affinity (Ki=2.2 nM) on cockroach sodium channels and that the alpha-toxin from L quinquestriatus hebraeus highly active on insects (LqhalphaIT) and alpha-like toxins compete at low concentration for its receptor binding site, suggesting that the alpha-like toxin receptor site is partially overlapping with the receptor site 3. Conversely, in rat brain, Lqh III competes for binding of the most potent anti-mammal alpha-toxin from Androctonus australis Hector venom (AaH II) only at very high concentration. The NMR structures were used for the scrutiny of the similarities and differences with representative scorpion alpha-toxins targeting the voltage-gated sodium channels of either mammals or insects. Three turn regions involved in the functional binding site of the anti-insect LqhalphaIT toxin reveal significant differences in the Lqh III structure. The electrostatic charge distribution in the Lqh III toxin is also surprisingly different when compared with the anti-mammal alpha-toxin AaH II. Similarities in the electrostatic charge distribution are, however, recognized between alpha-toxins highly active on insects and the alpha-like toxin Lqh III. This affords additional important elements to the definition of the new alpha-like group of scorpion toxins and the mammal versus insect scorpion toxin selectivities.

Amino Acid Sequence↗
PubMed1989

Epidemiological characteristics of scorpion sting in León, Guanajuato, México.

Poisoning with scorpion venom in the city of León, Guanajuato state, México, is a significant public health problem. The hospital of the Mexican Red Cross gave medical attention to 38,068 cases of envenomation by scorpion sting during 1981-1986; 77% of all accidents occurred among persons under 30 years of age. The 100% survival rate can be attributed to prompt serotherapy. Most stings were due to scorpions from the species Centruroides infamatus infamatus. Scorpion stings increase dramatically in the spring and are lowest during winter. The distribution of scorpions throughout the city is uniform and accidents occur at any time of day or night with no preference in regard to the sex of the affected persons. The epidemiological aspects of scorpion poisoning are emphasized.

Animals↗
PubMed2006

Genetic mechanisms of scorpion venom peptide diversification.

The diversity of scorpion venom peptides is well shown by the presence of about 400 such polypeptides with or without disulfide bonds. Scorpion toxins with disulfide bonds present a variety of sequence features and pharmacological functions by affecting different ion channels, while the venom peptides without disulfide bonds represent a new subfamily, having much lower sequence homology among each other and different functions (e.g. bradykinin-potentiating, antimicrobial, molecular cell signal initiating and immune modulating). Interestingly, all scorpion venom peptides with divergent functions may have evolved from a common ancestor gene. Over the lengthy evolutionary time, the diversification of scorpion venom peptides evolved through polymorphism, duplication, trans-splicing, or alternative splicing at the gene level. In order to completely clarify the diversity of scorpion toxins and toxin-like peptides, toxinomics (genomics and proteomics of scorpion toxins and toxin-like peptides) are expected to greatly advance in the near future.

Animals↗
PubMed1998

Delta-atracotoxins from Australian funnel-web spiders compete with scorpion alpha-toxin binding on both rat brain and insect sodium channels.

Atracotoxins are novel peptide toxins from the venom of Australian funnel-web spiders that slow sodium current inactivation in a similar manner to scorpion alpha-toxins. To analyse their interaction with known sodium channel neurotoxin receptor sites we determined their effect on scorpion toxin, batrachotoxin and saxitoxin binding. Nanomolar concentrations of delta-atracotoxin-Hv1 and delta-atracotoxin-Ar1 completely inhibited the binding of the scorpion alpha-toxin AaH II to rat brain synaptosomes as well as the binding of LqhalphaIT, a scorpion alpha-toxin highly active on insects, to cockroach neuronal membranes. Moreover, delta-atracotoxin-Hv1 cooperatively enhanced batrachotoxin binding to rat brain synaptosomes in an analogous fashion to scorpion alpha-toxins. Thus the delta-atracotoxins represent a new class of toxins which bind to both mammalian and insect sodium channels at sites similar to, or partially overlapping with, the receptor binding sites of scorpion alpha-toxins.

Amino Acid Sequence↗
PubMed1997

Clinical description of Parabuthus transvaalicus scorpionism in Zimbabwe.

An epidemiological and clinical study of Parabuthus transvaalicus scorpionism was conducted in Zimbabwe. Ten per cent of stings resulted in severe scorpionism. The clinical features of 17 patients with severe envenomation were primarily neuromuscular, with significant parasympathetic nervous system and cardiac involvement. The clinical course was prolonged compared to other scorpion syndromes, and significant therapeutic benefit was demonstrated in terms of hospital stay in response to species specific antivenom. The case fatality rate was 0.3%, with deaths in children below 10 years and adults above 50 years. The mortality rate in the district was 2.8 per 100,000 per year. This syndrome from a buthid scorpion resembles in many respects buthid scorpionism described elsewhere in the world, but shows important differences, notably cardiac involvement in the absence of clinical evidence of circulating catecholamines. The relevance of these findings to buthid scorpionism generally are presented as a hypothesis, in which it is postulated that the cardiac effects of the toxins are direct and primary, and autonomic effects secondary but synergistic, determining the ultimate clinical picture.

Adolescent↗
PubMed1997

Toxins and genes isolated from scorpions of the genus Tityus.

Scorpion venoms contain a variety of low mol. wt peptides toxic to different organisms. These peptides have been intensively studied because they represent excellent models for investigating structure-function relationships and they are also fine probes for studying ionic channel functions. This review deals with the biological and chemical aspects of toxic peptides that affect Na+ or K+ channels and the cloning of the cDNAs and genes encoding the main alpha and beta neurotoxins present in the venom of the three most dangerous species of Brazilian scorpion, Tityus bahiensis, Tityus stigmurus and Tityus serrulatus, and the Venezuelan scorpion Tityus discrepans. At least 16 different peptides specific for Na+ channels and five affecting K+ channels were isolated and characterized from the venom of these scorpions. The isolation of cDNAs and genes encoding four distinct toxins has permitted the elucidation of their nucleotide sequences as well as their genomic organization. Venoms and isolated toxins from scorpions of the genus Tityus were shown to enhance the secretory activity of the pancreas. Antisera obtained against venom of T. serrulatus show cross-reactivity with other species of the Brazilian scorpions.

Amino Acid Sequence↗
PubMed1999

Scorpion envenomation as a risk factor for development of dilated cardiomyopathy.

OBJECTIVES: Though scorpion envenomation is known to lead to acute myocarditis and a reversible decrease in left ventricular function, it has not been implicated as an etiological factor in idiopathic dilated cardiomyopathy. We studied the association of idiopathic dilated cardiomyopathy with a history of scorpion sting as well as with socio-economic status, history of smoking and alcoholism, rural habitation, and history of snake bites. METHODS: Consecutive cases of idiopathic dilated cardiomyopathy were recruited for this study: The association with putative risk factors was studied using a case-control study design with two sets of controls. One set of controls were age and sex matched inpatients selected at random, the other set of controls were spouse, or if not available, a close relative, ordinarily resident with the patient. RESULTS: On analysis, none of the factors except scorpion envenomation had a significant association. A past history of scorpion envenomation had an adjusted odds ratio of 8.01 (3.55-18.06) when compared to one set of controls and an odds ratio of 8.33 (6.55-10.59) when compared to the second group of controls. CONCLUSIONS: Our study indicates that a history of scorpion envenomation acts as a risk factor for the subsequent development of idiopathic dilated cardiomyopathy. Despite an apparently complete recovery from a scorpion sting, many patients probably retain sub-clinical deficits that predispose to the development of cardiomyopathy later in life, when other factors get added on. The known association of cardiomyopathy with catecholamine excess in experimental situations in animal studies, and in other disease states in humans, supports this hypothesis.

Adolescent↗
PubMed2003

Evaluation of scorpion stings: the poison center perspective.

Scorpion venom causes excessive adrenergic discharge and cardiotoxicity. Publications on scorpion stings using mainly admission data, has led to the belief that most scorpion stings are severe and mandate an observation period of at least 12 h regardless of symptomatology. We to assessed the characteristics of scorpion sting victims with emphasis on severity and time to presentation by retrospective poison center chart review of 225 calls over 12-mo. Thirteen percent of patients were asymptomatic and 72% and 15% were mild or moderately to severely ill, respectively. The most frequent manifestations were pain (97.3%), cardiovascular signs (23.1%) and ECG changes (13.7%). Ninety-four percent of the patients presented within 6 h; 86% within 3 h. Ninety-two percent of moderate to severe patients, including those with moderate to severe cardiotoxicity, presented within 3 h; 100% within 6 h. Clinical severity of the stings was greater in females than in males. No association was found between degree of severity and time to presentation and age. Most scorpion stings in Israel (at least those occurring in the north and central regions) are mild. The majority of envenomated patients present for medical assistance within 3 h including all patients with moderate to severe cardiotoxicity. Because of severity of potential complications, that scorpion sting victims should be observed in the emergency department for 6 h from the time of sting and should be admitted if symptoms other than local pain develop. Reduction of unnecessary in-hospital observation time is expected to save public health money.

Adolescent↗
PubMedDate not supplied

[Scorpion stings outbreaks in recently constructed urban dwellings inhabitants].

Scorpion stings are unfrequent in Chile. Most of cases occur in rural areas during the warm season. Clinical manifestations have a low to moderate intensity and consist in local pain and inflammation, sometimes associated with headache and hyperthermia. Two autbreaks of scorpion stings--affecting six and five adult residents (18-42 years old) of recently built urban dwelling complexes--have been recorded in Chile in summertime of 1957 and 1998. The first took place in the town of Maipú and the second in Villa Alborada sites respectively 10 and 150 km South of the city of Santiago. The Maipú dwelling complex was constituted by 112 one story houses in which lived 504 people. In Villa Alborada live 1,050 persons distributed in 158 apartments, 86 of which are in the main floor and in 26 of these last the occupants have observed scorpions inside. All the 11 cases occurred into the dwelling: four when sleeping at night, three performing different activities (trying to find a tool, searching a kee, housekeeping), two when putting their shoes, and two walking with bare feet in dormitory. In all the cases the causative scorpion was observed, captured or destroyed. Identification of six specimens from Maipú corresponded to Brachistoternus ehrenbergi and of two from Villa Alborada to Bothriurus borrelianus. All the patients presented mild to moderate symptomatology. Treatment consisted basically in oral antihistamanic and/or antinflammatory tablets. Recovery was observed within one to seven days with a mean of three days. Prophylactic measures consisted in health education and physical destruction of scorpions in Maipú and insecticide spraying on floors of basement apartments and surrounding areas in Villa Alborada. Though the majority of accidents by scorpion stings happens in rural areas, also may occur in urban areas--rural in the near past--where dwellings have been constructed in fields which in not to much preterit times constituted the habitat of the referred arthropod, phenomenom that have occurred in summertime in the two dwelling complexes described in the present communication.

Adolescent↗
PubMed1999

Solution structure of toxin 2 from centruroides noxius Hoffmann, a beta-scorpion neurotoxin acting on sodium channels.

We have determined the solution structure of Cn2, a beta-toxin extracted from the venom of the New World scorpion Centruroides noxius Hoffmann. Cn2 belongs to the family of scorpion toxins that affect the sodium channel activity, and is very toxic to mammals (LD50=0.4 microg/20 g mouse mass). The three-dimensional structure was determined using 1H-1H two-dimensional NMR spectroscopy, torsion angle dynamics, and restrained energy minimization. The final set of 15 structures was calculated from 876 experimental distance constraints and 58 angle constraints. The structures have a global r. m.s.d. of 1.38 A for backbone atoms and 2.21 A for all heavy atoms. The overall fold is similar to that found in the other scorpion toxins acting on sodium channels. It is made of a triple-stranded antiparallel beta-sheet and an alpha-helix, and is stabilized by four disulfide bridges. A cis-proline residue at position 59 induces a kink of the polypeptide chain in the C-terminal region. The hydrophobic core of the protein is made up of residues L5, V6, L51, A55, and by the eight cysteine residues. A hydrophobic patch is defined by the aromatic residues Y4, Y40, Y42, W47 and by V57 on the side of the beta-sheet facing the solvent. A positively charged patch is formed by K8 and K63 on one edge of the molecule in the C-terminal region. Another positively charged spot is represented by the highly exposed K35. The structure of Cn2 is compared with those of other scorpion toxins acting on sodium channels, in particular Aah II and CsE-v3. This is the first structural report of an anti-mammal beta-scorpion toxin and it provides the necessary information for the design of recombinant mutants that can be used to probe structure-function relationships in scorpion toxins affecting sodium channel activity.

Amino Acid Sequence↗
PubMed1993

Neutralizing capacity of murine sera induced by different antigens of scorpion venom.

Approximately 700 people die in Mexico each year from scorpion stings. The only useful therapy available is antiserum obtained from horses immunized with macerates of venomous gland from scorpions of the genus Centruroides. We report the results of experiments conducted with mice and rats in order to evaluate the relevant components of the venom from Centruroides noxius in the induction of a protective response against scorpion envenomation, either in vivo or in vitro. Gland macerates of whole telsons (stinger), soluble venom extracted by electrical stimulation, toxic fractions from gel filtration on Sephadex G-50 and highly purified toxin 2 from this scorpion venom were all used to produce hyperimmune mice and rats, which were challenged in vivo with the equivalent of the lethal dose 50% (LD50) of soluble venom, or their sera were prepared for in vitro neutralization experiments using non-immunized animals. The maximum neutralizing capacity (100%) was obtained when soluble venom was used as antigen, while purified toxin 2 produces 80% survival in vivo. The neutralizing capacity of murine antisera evaluated in vitro was: sera antifraction II > antitoxin 2 > antitotal venom > anti-gland macerates of whole telsons. Two additional aspects were further investigated in the present work. One is the demonstration by immunoblotting that proteins corresponding to the electrophoretic mobility of toxins known to block sodium channels are highly immunodominant in this venom. Second, there is a strong cross-reactivity of antisera produced with Centruroides noxius when assayed against venoms from other dangerous species of Centruroides scorpions from Mexico, but not against the Israeli scorpion Leiurus quinquestriatus. Finally, the immunodominance of toxic fractions in the immune response was observed either with immunization using Freund's adjuvant or by means of adsorption to nitrocellulose membranes. This latter vehicle was shown to be an excellent detoxifying agent, without changing the immunogenicity of the toxins, as might occur with chemical treatment of these neurotoxic peptides.

Animals↗
PubMed1995

The scorpion envenoming syndrome.

The pathophysiology of the scorpion envenoming syndrome is reviewed with emphasis on the body systems commonly affected. Concepts of the mechanisms underlying venom action, as can be explained by the recently discovered effects on ionic channels, are discussed. The results of clinical analysis of cases of scorpion sting victims and animal experiments with scorpion envenomation supporting these concepts are presented. The pharmacokinetic characteristics of scorpion venoms and their correlation to the magnitude of toxic effects are presented in relation to the potentials of therapeutic intervention. The pharmacological basis of the therapeutic usefulness and toxicities of the drugs commonly used in the treatment of scorpion envenoming is also projected. Finally, the results of a successful nation-wide clinical study with serotherapy of scorpion envenoming are presented and evaluated.

Animals↗
PubMed2005

Structure-activity relationship of an alpha-toxin Bs-Tx28 from scorpion (Buthus sindicus) venom suggests a new alpha-toxin subfamily.

Scorpion venoms are among the most widely known source of peptidyl neurotoxins used for callipering different ion channels, e.g., for Na(+), K(+), Ca(+) or Cl(-). An alpha-toxin (Bs-Tx28) has been purified from the venom of scorpion Buthus sindicus, a common yellow scorpion of Sindh, Pakistan. The primary structure of Bs-Tx28 was established using a combination of MALDI-TOF-MS, LC-ESI-MS, and automated Edman degradation analysis. Bs-Tx28 consists of 65 amino acid residues (7274.3+/-2Da), including eight cysteine residues, and shows very high sequence identity (82-94%) with other long-chain alpha-neurotoxins, active against receptor site-3 of mammalian (e.g., Lqq-IV and Lqh-IV from scorpions Leiurus sp.) and insect (e.g., BJalpha-IT and Od-1 from Buthotus judaicus and Odonthobuthus doriae, respectively) voltage-gated Na(+) channels. Multiple sequence alignment and phylogenetic analysis of Bs-Tx28 with other known alpha- and alpha-like toxins suggests the presence of a new and separate subfamily of scorpion alpha-toxins. Bs-Tx28 which is weakly active in both, mammals and insects (LD(50) 0.088 and 14.3microg/g, respectively), shows strong induction of the rat afferent nerve discharge in a dose-dependent fashion (EC(50)=0.01microg/mL) which was completely abolished in the presence of tetrodotoxin suggesting the binding of Bs-Tx28 to the TTX-sensitive Na(+)-channel. Three-dimensional structural features of Bs-Tx28, established by homology modeling, were compared with other known classical alpha-mammal (AaH-II), alpha-insect (Lqh-alphaIT), and alpha-like (BmK-M4) toxins and revealed subtle variations in the Nt-, Core-, and RT-CT-domains (functional domains) which constitute a "necklace-like" structure differing significantly in all alpha-toxin subfamilies. On the other hand, a high level of conservation has been observed in the conserved hydrophobic surface with the only substitution of W43 (Y43/42) and an additional hydrophobic character at position F40 (L40/A/V/G39), as compared to the other mentioned alpha-toxins. Despite major differences within the primary structure and activities of Bs-Tx28, it shares a common structural and functional motif (e.g., transRT-farCT) within the RT-CT domain which is characteristic of scorpion alpha-mammal toxins.

Action Potentials↗
PubMed1998

Evidence for a new class of scorpion toxins active against K+ channels.

cDNAs encoding novel long-chain scorpion toxins (64 amino acid residues, including only six cysteines) were isolated from cDNA libraries produced from the venom glands of the scorpions Androctonus australis from Old World and Tityus serrulatus from New World. The encoded peptides were very similar to a recently identified toxin from T. serrulatus, which is active against the voltage-sensitive 'delayed-rectifier' potassium channel, but they were completely different from the long-chain and short-chain scorpion toxins already characterised. However, there was some sequence similarity (42%) between these new toxins, Aa TX Kbeta and Ts TX Kbeta, and scorpion defensins purified from the hemolymph of Buthidae scorpions Leiurus quinquestriatus and A. australis. Thus, according to a multiple sequence alignment using CLUSTAL, these new toxins seem to be related to the scorpion defensins.

Amino Acid Sequence↗