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At least 955 records · Page 53Linked to original sources
PubMed1987

A study of myonecrosis induced by the venom of the scorpion tityus serrulatus.

The pathogenesis of skeletal muscle necrosis produced by Tityus Serrulatus venom was studied by means of light microscopy and electron microscopy. Wistar rats were inoculated subcutaneously, at some distance from the muscles under study, with a sublethal dose of scorpion venom. Samples were taken of the tibialis anterior muscles of both rear legs, 2, 7 and 24 hours postinoculation. Light microscopy analysis after 2 hours revealed certain changes identified as "delta lesions", and also the presence of hyperconcentrated muscle cells. Electron microscopy confirmed these lesions and also enabled us to identify a degree of discontinuity in the plasma membrane with a persistence of the basal membrane. Hyperconcentrated fibers could still be observed 7 hours postinoculation. Histochemical analysis revealed high levels of calcium within the fibers. 24 hours after inoculation with the venom, numerous phagocytic cells were found in the degenerated fibers. Muscle cells were also found to have undergone alterations indicative of an ischemic process. The most characteristic finding 7 days postinoculation was the appearance of regenerative fibers. After thirty days the muscles regained their normal appearance. It is suggested that Tityus Serrulatus venom induces myonecrosis by means of a twofold action: direct action, which gives rise in the first place to a rupture of the plasma membrane, permitting a massive entry of calcium this being a key factor in the process of cell lesion and an assumed indirect action due to ischemia.

Animals↗
PubMedDate not supplied

[Scorpionism complicated by transient blindness. Apropos of a case].

A six years old child, string by a Leiurus quinquestriatus scorpion (Buthidae fam), got, 15 hours after having been string, consciousness disorders and convulsions within a feverish context. The general status recovered rapidly, but disorders of upper functions and a total blindness both occurred. The latter disappeared in few weeks time; central disorders improved progressively while a pyramidal syndrome appeared. No satisfactory explanation was given of such phenomena.

Blindness↗
PubMed1984

Preliminary X-ray investigation of variant-2 scorpion toxin from Centruroides sculpturatus Ewing. Evidence of a reversible transition between crystal forms.

Crystals of Variant-2 scorpion toxin have been grown using seeding techniques from 30% 2-methyl-2,4-pentanediol at pH 9.2 and T = 4 degrees C. These crystals display a temperature-dependent, reversible phase transition near room temperature. The apparent space group for the high-temperature form is P3121 or P3221 with a = 48.8(1) A and c = 43.7(1) A, and with one molecule per asymmetric unit. At lower temperature, the crystals undergo a phase transition in which the space group remains the same but with c' (approximately equal to 2c) = 86.1(1) A. In addition, the low-temperature form displays several weak, diffuse reflections that correspond to a tripling of the a axis. The high-temperature form diffracts beyond 1.8-A resolution and appears to be suitable for a complete structural study.

Animals↗
PubMed1984

[Anti-scorpion control in the governorship of Sidi Bouzid (Tunisia)].

The authors describe the incidence, the clinical aspects and the epidemiology of scorpion poisoning in the area of Sidi Bouzid. They expose and propose public health measures which should diminish the incidence of stings, and the number of hospitalisations and deaths. Improvement of housing and food hygiene, education of the population are essential.

Adult↗
PubMed1997

[Snakes and scorpions: what are the risks for the traveler?].

The risk of being bitten by a snake or stung by a scorpion is low for the ordinary, non-thrill-seeking traveler. Travelers who plan hazardous outdoor activities should be advised to be careful and bring along adequate protective clothing (boots, long trousers, and gloves). If envenomation occurs, the victim should be immobilized and rushed to a treatment center. Administration of antivenin using massive doses in severe cases is the best therapy. For quickest and most efficient results, antivenins should be administered by the intravenous route. Packing antivenins is necessary only under special circumstances when high-risk activities are scheduled. In this case contingency planning may also be necessary taking into account health care facilities in the destination country and the availability of antivenins.

Animals↗
PubMed1998

1H NMR structure of an antifungal gamma-thionin protein SIalpha1: similarity to scorpion toxins.

The three-dimensional structure of the Sorghum bicolor seed protein gamma-thionin SIalpha1 has been determined by 2D 1H nuclear magnetic resonance (NMR) spectroscopy. The secondary structure of this 47-residue antifungal protein with four disulphide bridges consists of a three-stranded antiparallel sheet and one helix. The helix is tethered to the sheet by two disulphide bridges which link two successive turns of the helix to alternate residues i, i+2 in one strand. Possible binding sites for antifungal activity are discussed. The same fold has been observed previously in several scorpion toxins.

Amino Acid Sequence↗
PubMed1999

Solution structure of potassium channel-inhibiting scorpion toxin Lq2.

Lq2 is a unique scorpion toxin. Acting from the extracellular side, Lq2 blocks the ion conduction pore in not only the voltage- and Ca2+ -activated channels, but also the inward-rectifier K+ channels. This finding argues that the three-dimensional structures of the pores in these K+ channels are similar. However, the amino acid sequences that form the external part of the pore are minimally conserved among the various classes of K+ channels. Because Lq2 can bind to all the three classes of K+ channels, we can use Lq2 as a structural probe to examine how the non-conserved pore-forming sequences are arranged in space to form similar pore structures. In the present study, we determined the three-dimensional structure of Lq2 using nuclear magnetic resonance (NMR) techniques. Lq2 consists of an alpha-helix (residues S10 to L20) and a beta-sheet, connected by an alphabeta3 loop (residues N22 to N24). The beta-sheet has two well-defined anti-parallel strands (residues G26 to M29 and residues K32 to C35), which are connected by a type I' beta-turn centered between residues N30 and K31. The N-terminal segment (residues Z1 to T8) appears to form a quasi-third strand of the beta-sheet.

Amino Acids↗
PubMed2000

A new fold in the scorpion toxin family, associated with an activity on a ryanodine-sensitive calcium channel.

We determined the structure in solution by (1)H two-dimensional NMR of Maurocalcine from the venom of Scorpio maurus. This toxin has been demonstrated to be a potent effector of ryanodyne-sensitive calcium channel from skeletal muscles. This is the first description of a scorpion toxin which folds following the Inhibitor Cystine Knot fold (ICK) already described for numerous toxic and inhibitory peptides, as well as for various protease inhibitors. Its three dimensional structure consists of a compact disulfide-bonded core from which emerge loops and the N-terminus. A double-stranded antiparallel beta-sheet comprises residues 20-23 and 30-33. A third extended strand (residues 9-11) is perpendicular to the beta-sheet. Maurocalcine structure mimics the activating segment of the dihydropyridine receptor II-III loop and is therefore potentially useful for dihydropyridine receptor/ryanodine receptor interaction studies. Proteins 2000;40:436-442.

Amino Acid Sequence↗
PubMed2000

BmK AS: new scorpion neurotoxin binds to distinct receptor sites of mammal and insect voltage-gated sodium channels.

This study was undertaken to assess the binding properties of BmK AS on both mammal and insect excitable cell membranes. It was found that BmK AS bound specifically to a single class of non-interacting binding sites on both rat brain and cockroach nerve cord synaptosomes with high affinity (K(d) = 1.49 +/- 0.14 and 0.79 +/- 0.29 nM) and low capacity (B(max) = 1.39 +/- 0.09 and 6.60 +/- 1.25 pmol/mg protein), respectively. Binding kinetics showed that BmK AS could bind and reach equilibrium quickly, and dissociate partially from its binding sites on both kinds of synaptosomes. The binding of BmK AS was independent of membrane potential. Veratridine could not modify the binding of BmK AS. The competitive binding assay showed that specific binding of (125)I-BmK AS could be significantly inhibited by native BmK AS, BmK AS-1, BmK IT2 and BmK IT on both synaptosomes. Unexpectedly, only about 20-30% binding of BmK AS on mammal synaptosomes was inhibited by BmK I at 10(-5)-10(-9) M, but not on insect synaptosomes. It thus suggests that BmK AS type neurotoxins might bind to a distinct receptor site of sodium channels on mammal and insect excitable cell membranes with a manner similar to beta-scorpion toxins.

Animals↗
PubMed2002

Chlorotoxin, a scorpion-derived peptide, specifically binds to gliomas and tumors of neuroectodermal origin.

Highly migratory neuroectodermal cells share a common embryonic origin with cells of the central nervous system (CNS). They include enteric, parasympathetic, sympathoadrenal, and sensory neurons of the peripheral nervous system, Schwann cells, melanocytes, endocrine cells, and cells forming connective tissue of the face and neck. Because of their common embryologic origin, these cells and the tumors that derive from them can share genetic and antigenic phenotypes with gliomas, tumors derived from CNS glia. We recently discovered that chlorotoxin (ClTx), a 4-kD peptide purified from Leiurus quinquestriatus scorpion, is a highly specific marker for glioma cells in biopsy tissues (Soroceanu et al. Cancer Res 58:4871-4879, 1998) that can target tumors in animal models. We report on the specificity of ClTx as a marker for tumors of neuroectodermal origin that include peripheral neuroectodermal tumors (PNET) and gliomas. Specifically, we histochemically stained frozen and paraffin tissue sections of human biopsy tissues from 262 patients with a synthetically manufactured and biologically active ClTx bearing an N-terminal biotin. The vast majority (74 of 79) of primary human brain tumors investigated showed abundant binding of ClTx with greater than 90% ClTx-positive cells in each section. By comparison, 32 biopsies of uninvolved brain used for comparison were largely ClTx-negative, with only a few isolated reactive astrocytes showing some ClTx binding. However, as with gliomas, the vast majority of PNETs examined showed specific ClTx binding (31 of 34). These include medulloblastomas (4 of 4), neuroblastomas (6 of 7), ganglioneuromas (4 of 4), melanomas (7 of 7), adrenal pheochromocytomas (5 of 6), primitive PNET (1), small cell lung carcinoma (2 of 3), and Ewing's sarcoma (2 of 2). Under identical staining conditions, normal tissues from brain, skin, kidney, and lung were consistently negative for ClTx. These results suggest that chlorotoxin is a reliable and specific histopathological marker for tumors of neuroectodermal origin and that chlorotoxin derivatives with cytolytic activity may have therapeutic potential for these cancers.

Adult↗
PubMed2004

Morphology and function of male genitalia (spermatophores) in Euscorpius italicus (Euscorpiidae, Scorpiones): complex spermatophore structures enable safe sperm transfer.

The structure and function of the spermatophore of Euscorpius italicus are analyzed. We show how the spermatophore gets shaped from two hemispermatophores and for the first time the sperm transfer mechanism is shown in detail, illustrating function and importance of all complex lobe structures of an euscorpiid spermatophore. A detailed description of the interaction of spermatophore and female genitalia is given. The capsular region of the spermatophore bears different lobes: The distal and basal lobes hook into two cavities on the inner side of the female's genital operculum. A so-called "crown-like structure" hooks into a membranous area in the genital atrium. During sperm transfer, these crown-like structures move backwards, in this way widening the female's genital opening. The sperm duct of the spermatophore is coated with numerous spicules on its outer side, which could serve as a sealing mechanism and/or may stimulate the female. Furthermore, we conclude that "safeguarding of sperm transfer" is one driving force for evolution of male genital complexity in scorpions, but also sexual selection by cryptic female choice could partly play a role.

Animals↗
PubMed1992

The beta-type toxin Ts II from the scorpion Tityus serrulatus: amino acid sequence determination and assessment of biological and antigenic properties.

The toxin Ts II from the venom of the Brazilian scorpion Tityus serrulatus was purified in two successive chromatographic steps. The amino acid sequence was then determined by automated Edman degradation of the reduced and S-carboxymethylated protein and of proteolytic peptides derived from it. This sequence appears to differ from that of previously characterized toxins found in this venom. However, it is identical to the recently published sequence of protein III-8 from the same venom [Possani et al., J Biol Chem 266:3178-3185, 1991], except that the C-terminus was found to be amidated. Homologies were found between the sequence of Ts II and that of other toxins from Tityus; in particular, the amino acid sequence of Ts II displays 72% sequence identity with Ts VII (also called Titx gamma). Consistent with this structural similarity, some biological properties of Ts II were found to be similar to those of Ts VII: Ts II has an intracerebroventricular LD50 of 6 ng, as compared to 0.6 ng for Ts VII; in a receptor binding assay Ts II, like Ts VII, was found to behave as a beta-type toxin and to inhibit the binding of the reference labelled toxin with a K0.5 of 5 x 10(-9) M, as compared to 7 x 10(-11) M for Ts VII. Nevertheless, Ts II is unable to bind to anti-Ts VII antibodies in radioimmunoassay experiments, indicating the non-conservation between the two toxins of at least some antigenically important residues.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1990

Conformational flexibility of a scorpion toxin active on mammals and insects: a circular dichroism study.

Three scorpion toxins have been analyzed by circular dichroism in water and in 2,2,2-trifluoroethanol (TFE) solutions. These toxins were chosen because they are representative of three kinds of pharmacological activities: (1) toxin AaH IT2, an antiinsect toxin purified from the venom of Androctonus australis Hector, which is able to bind to insect nervous system preparation, (2) toxin Css II, from the venom of Centruroides suffusus suffusus, which is a beta-type antimammal toxin capable of binding to mammal nervous system preparation, and (3) the toxin Ts VII from the venom of Tityus serrulatus, which is able to bind to both types of nervous systems. In order to minimize bias, CD data were analyzed by a predictive algorithm to assess secondary structure content. Among the three molecules, Ts VII presented the most unordered secondary structure in water, but it gained in ordered forms when solubilized in TFE. These results indicated that the Ts VII backbone is the most flexible, which might result in a more pronounced tendency for this toxin molecule to undergo conformational changes. This is consistent with the fact that it competes with both antiinsect and beta-type antimammal toxins for the binding to the sodium channel.

Amino Acid Sequence↗
PubMed1995

Beta-scorpion toxin 2 from Centruroides noxius blocks voltage-gated K+ channels in human lymphocytes.

Using the patch-clamp technique, we determined that beta-scorpion toxin 2 from Centruroides noxius Hoffmann decreased whole-cell n-type K+ currents in human peripheral blood lymphocytes, with a half blocking concentration of approx. 5 microM. Toxin-2-accelerated inactivation, however, did not influence the kinetics of activation of the K+ conductance. The percentage increase in K+ channel inactivation rate and the degree of drug-induced block was independent of membrane potential. K+ channel block by Toxin 2 was instantaneous, not removable by washing with drug free extracellular solution. However, 10 mg/ml BSA in the bath lifted the toxin-induced block almost instantaneously and completely. Flow cytometric membrane potential measurements with the oxonol dye showed that Toxin 2 depolarizes human lymphocytes in concert with its K+ channel blocking effect.

Barbiturates↗
PubMed1998

A novel toxin form the scorpion Androctonus australis blocks Shaker K+ channels expressed in Xenopus oocytes.

The Shaker B potassium channel expressed in Xenopus laevis oocytes is blocked, in a total reversible manner from the outside part, by a new toxin (Aa1) composed of 40 amino acid residues, purified from the venom of the North African scorpion Androctonus australis Garzoni. The experiments were performed with patch-clamp technique in the outside-out configuration. The half blocking concentration is approximately 4.5 microM with a 1:1 stoichiometry. The activation and inactivation kinetics of the current are not modified by the blocking mechanism. The binding affinity is not voltage dependent. These results suggest a simple bimolecular mechanism of blockade by which the toxin occludes the external vestibule of the channel and thereby inhibits the K+ ions conduction.

Animals↗
PubMed1998

Pandinus imperator scorpion venom blocks voltage-gated K+ channels in human lymphocytes.

Using the patch-clamp technique, we determined that Pandinus imperator scorpion venom blocked whole-cell n-type K+ currents in human peripheral blood lymphocytes in a dose-dependent manner with Kd = 0.02 microgram/ml. K+ channel block was instantaneous and removable by washing with venom-free extracellular solution. The venom-induced block was independent of membrane potential. The venom did not influence activation and inactivation kinetics of the K+ channels, however, accelerated recovery from inactivation. Purified peptides Pi1, Pi2, and Pi3 from the P. imperator venom powerfully blocked Kv1.3 channels in human lymphocytes with Kd values of 9.7 nM, 50 pM, and 0.5 nM, respectively. Flow cytometric membrane potential measurements with the oxonol dye showed that Pi2, the most effective peptide toxin of the P. imperator venom, depolarizes human lymphocytes in accordance with its K+ channel blocking effect.

Barbiturates↗
PubMed2000

Solution structure of BmP01 from the venom of scorpion Buthus martensii Karsch.

From the venom of scorpion Buthus martensii Karsch,a short peptide (BmP01, 29 amino acid residues) was isolated and characterized as previously reported (Lebren, R. R., et al. (1997) Eur. J. Biochem. 245, 457-464). It was shown to reduce 33% outward K(+) channel (hippocampal neurons) currents at 10 microM. The solution structure of BmP01 was determined by 2D (1)H NMR spectroscopy. The NOEs, coupling constants, and H-D exchange obtained from NMR spectroscopy were used in structural calculations. The conformation of BmP01 is composed of a short alpha-helix (Cys 3-Thr 12) and a two-stranded antiparallel beta-sheet (Ala 15-Asp 20 and Lys 23-Pro 28). There are three disulfide bridges (Cys 3-Cys 19, Cys 6-Cys 24 and Cys 10-Cys 26) connecting the alpha-helix and beta-sheet. Asp 20 to Lys 23 form a type II turn linking the two strands. Structural and electrostatic potential comparison between BmP01 and its analogues are also presented.

Amino Acid Sequence↗