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At least 235 records · Page 13Linked to original sources
PubMed1999

Dobutamine in severe scorpion envenomation: effects on standard hemodynamics, right ventricular performance, and tissue oxygenation.

OBJECTIVES: To document the effects of dobutamine on standard hemodynamics and right ventricular (RV) performance in patients exhibiting pulmonary edema following severe scorpion envenomation, and to characterize the tissue oxygenation profile in patients sustaining scorpion envenomation-related shock. DESIGN: Prospective cohort study. SETTING: An ICU in a university hospital. PATIENTS: Nineteen consecutive patients were admitted to the ICU for severe scorpion envenomation; all 19 patients exhibited hemodynamic pulmonary edema, and 10 patients had peripheral shock. INTERVENTIONS: All patients underwent a hemodynamic study with a Swan-Ganz catheter. In 8 of 19 patients, the thermodilution catheter was equipped with a fast-response thermistor. MEASUREMENTS AND RESULTS: Standard hemodynamic parameters were recorded on admission and following the infusion of dobutamine in all patients at a dosage, from 7 to 20 microg/kg/min, intended to achieve the best hemodynamic and tissue oxygenation compromise. RV ejection fraction (RVEF) and RV volumes were simultaneously recorded in 8 patients, and tissue oxygenation parameters were assessed in the 10 patients with peripheral shock. The clinical signs of tissue hypoperfusion improved, and optimal hemodynamic parameters were achieved at a mean +/- SD dobutamine dosage of 17 +/- 7 microg/kg/min. Dobutamine infusion evoked statistically significant increases in cardiac index, from 2.3 +/- 0.6 to 3.6 +/- 0.7 L/min/m2; stroke volume index, from 18 +/- 5 to 31 +/- 10 mL/m2; and systemic arterial pressure, from 64 +/- 12 to 78 +/- 14 mm Hg. Pulmonary artery occlusion pressure (PAOP) and venous admixture decreased significantly: from 23 +/- 4 to 15 +/- 6 mm Hg and from 29 +/- 7% to 20 +/- 5%, respectively. With respect to RV function, dobutamine infusion significantly increased the RVEF, from 24 +/- 7% to 42 +/- 9%, without significantly changing the RV end-diastolic volume index, reflecting an enhanced RV contractility. In patients with peripheral circulatory failure, the baseline tissue oxygenation profile was consistent with cardiogenic shock, showing increased oxygen extraction as a consequence of a striking depression in oxygen delivery (DO2). After dobutamine infusion, DO2 improved significantly, from 386 +/- 104 to 676 +/- 156 mL/min/m2, with a significant decrease in oxygen extraction, from 34 +/- 8% to 24 +/- 6%. CONCLUSIONS: In severe scorpion envenomation, dobutamine infusion improves impaired heart function. The effects involve both left ventricular and RV dysfunction. Impaired tissue oxygenation is also improved.

Acute Disease↗
PubMedDate not supplied

Scorpion sting epidemiology in Montes Municipality of the State of Sucre, Venezuela: geographic distribution.

Scorpion stings were surveyed in the Montes Municipality of the State of Sucre, Venezuela, aiming to extend the information on these poisonous accidents by characterizing their geographic distribution. From 1980 to 1990, 184 cases of scorpion stings were recorded with an incidence rate of 38.6 cases per 10,000 inhabitants. The locality of San Fernando presented the highest incidence (68.3/1000) of poisonous accidents. The highest percentages of severe cases were recorded in the towns of Arenas (27%), San Lorenzo (21%), and Cocollar (19%), which are located at the foot of the Turimiquire Mountains. This region is a dispersion area of scorpions of the Tityus genus. Our results show that this region of the State of Sucre is endemic for scorpion stings which are an important public health problem.

Animals↗
PubMed2006

Efficient in vitro refolding and characterization of a new peptide from the scorpion Buthotus saulcyi venom produced in Escherichia coli.

The selective toxicity of depressant scorpion neurotoxins to insects is useful in studying the insect sodium channel gating, as well as being relevant to several other applications. In order to carry out structure/activity studies, the functional expression of such polypeptides is required. In the work reported here, the cDNA of a new peptide from the venom of the scorpion Buthotus saulcyi was cloned and sequenced. It codes for a 64 residues peptide (BsaulI) with 8 highly-conserved cysteines. This peptide shares high sequence similarity with depressant insect toxins of other scorpion species. Large amounts of insoluble BsaulI protein were expressed in Escherichia coli. Purification of this peptide was carried out under denaturing conditions. Renaturation was performed by pulsed dilution of the denatured BsaulI in the refolding buffer. Production of refolded Bsaul1, however, is approximately an order of magnitude higher than that obtained with similar scorpion depressant toxins. Intrinsic fluorescence, far-UV circular dichroism spectra and biological activity assays indicate that the peptide adopts a folded structure.

Amino Acid Sequence↗
PubMed2004

[Establishment and analysis of a log to record scorpion stings in Morocco].

Within the framework of a strategy against scorpion stings, an information system was established to track the indicators of morbidity and mortality caused by scorpion stings. The study of these indicators was carried out based upon a national record of scorpion stings. During the year 2001, 15,571 cases of scorpion stings were reported, that translates into an incidence rate of 1.2%. The patients were poisoned in 11.6% of the cases. Most of the patients (79.3%) were only put under clinical surveillance and did not receive any symptomatic treatment. The death rate was 6.3% and death only occurred in children of less than 15 years old (2.1% of the cases). This study demonstrated an improvement in morbidity and mortality indicators in comparison to the data collected before this campaign, all of which verifies the positive impact of the strategy which was put into place. However, it is necessary to continue monitoring until Morocco can overcome this problem.

Adolescent↗
PubMed2002

[Fifteen years' experience in scorpion envenomation control in Algeria].

In Algeria, scorpion envenomation is real public health problem. Since the creation of the National Committee of Control of Scorpion envenomations (CNLES), several steps have been taken to deal with this problem. After a brief historical introduction, we present the main elements of the action carried out both in terms of treatment and of prevention of scorpion proliferation. The epidemiological situation is presented by stressing the difficulties involved in collecting reliable data. We also address the question of citizen and stakeholder awareness since public participation is crucial in all prevention programmes. Training for healthcare providers is also one of the principal axes of the Committee's programme which includes national, regional, and even local seminars. We describe the improvement of production and research on venoms carried out by the Institute Pasteur of Algeria. We conclude by discussing the action plan for 2001 and prospects for an enhanced strategy in the fight against the scorpion envenomation.

Adolescent↗
PubMed2003

[Scorpion stings in an area of Nordeste de Amaralina, Salvador, Bahia, Brazil].

An epidemiological study was undertaken to determine the prevalence of individuals who referred scorpion sting accidents in a population sample from Areal, a neighborhood northeast of Amaralina, Salvador City, State of Bahia, Brazil. A random, systematic sample of 1,367 individuals was taken, corresponding to 44.4% of the total population. Eighty-two residents referred scorpion sting since they were resident in Areal, giving a prevalence coefficient of 6% (95% CI 4.7 - 7.3). The prevalence of persons stung by scorpions increased according to greater time spent in the domicile and more advanced age. It was remarkable that 92.7% of the scorpions stings occurred within the home. The incidence coefficient estimated for the most recent period of time (January to July, 2000) was 1.15 cases/1,000 inhabitants per month, comparable to the highest ever reported for an epidemic area.

Adolescent↗
PubMed2006

Androctonus crassicauda (Olivier 1807) scorpionism in the Sanliurfa provinces of Turkey.

In this study, the epidemiology and clinical findings of scorpion stings in the Sanliurfa province of Turkey was evaluated between May and September 2003. Data obtained from questionnaires was evaluated and the identification of scorpions collected from the region was carried out in the laboratory. It was determined that of the species of scorpions only Androctonus crassicauda was collected. This species plays the major role in 50.8% of scorpionism cases. This study also showed that intoxications caused by A. crassicauda in southeast Anatolia region were seen in the summer during the hot months especially in August. Females and people above 15 years of age were the most affected and they had been stung on the extremities. In clinical evaluations, it was found that 17.7% of the cases showed systemic effects and no deaths were reported. Also parasympathetic effects were more common in comparison to sympathetic effects.

Adolescent↗
PubMed1991

Treatment of cardiovascular manifestations of human scorpion envenoming: is serotherapy essential?

Death due to sting by the red scorpion is not uncommon in parts of India. Extensive clinical study has shown that fatality is due to cardiovascular involvement as a result of autonomic storm. Prazosin and nifedipine helped to counter the physiological actions of scorpion venom on the sympathetic nervous system. Scorpion antivenom remains unobtainable for human scorpionism in India.

Animals↗
PubMed1998

[Scorpion stings].

This article begins by describing how Iberian Peninsula scorpion bites poison humans. Then the only potentially dangerous scorpion species in the peninsula is identified. Other types of scorpions or those which inhabit other continents are not included. Once identified, the author describes the characteristics and effects on the symptoms of this scorpion bite and how to treat and handle a victim, both at the moment when the victim is bitten and in hospitals.

Animals↗
PubMed2006

Splicing of scorpion toxin gene BmKK2 in HEK 293T cells.

Using GFP as a reporter gene, splicing of scorpion toxin gene BmKK2 was investigated in cultured HEK 293T cells. The results of RT-PCR and western blotting showed that BmKK2's intron could be recognized and spliced in cultured HEK 293T cells. At the same time, a cryptic splicing site of BmKK2 gene was found at the 91st nucleotide site of the second exon, which is a typical form of alternative splicing. For the first time, alternative splicing would partially explain the diversity of scorpion toxins at the gene level. Moreover, replacing BmKK2's intron with BmP03's intron (an artificial BmKK2-BmP03 mosaic gene) did not affect the intron's recognition and splicing, but increased the expression of the toxin-GFP fusion protein by fluorescence imaging, which indicated that both introns may regulate the expression of toxin-GFP fusion protein. The artificial BmKK2-BmP03 mosaic gene was also spliced into two kinds of mRNA molecules, which showed that sequence of intron was not absolutely conserved. The results suggested that introns of scorpion toxin genes BmKK2 and BmP03 increase the diversity of scorpion toxins and regulate the expression of their genes.

Cell Line↗
PubMedDate not supplied

Structural analysis of the unique insecticidal activity of novel mungbean defensin VrD1 reveals possibility of homoplasy evolution between plant defensins and scorpion neurotoxins.

A variety of evolutionarily related defensin molecules is found in plants and animals. Plant gamma-thionins and scorpion neurotoxins, for instance, may be categorized in this functional group, although each class recognizes a distinct receptor binding site. Such molecules are also categorized into the superfamily of cysteine-rich proteins. Plant defensins were generally believed to be involved in antimicrobial or antifungal mechanisms and, unlike scorpion toxins, little is known about whether these molecules are also endowed with the function of insect resistance. We have previously reported the isolation of a cDNA encoding a small cysteine-rich protein designated VrD1 (VrCRP) from a bruchid-resistant mungbean, which is apparently the first discovered plant defensin exhibiting in vitro and in vivo both insecticidal and antifungal activities. Our previous data also successfully demonstrated that VrD1 is toxic to E. coli and able to completely arrest the growth of Sf-21 insect cells at low concentration. However, the molecular and structural basis of this unique insecticidal activity of VrD1 is not clear. Therefore, in the present study, we use structural approach and phylogenic analysis to investigate the evolutionary and functional relations for such unique insecticidal activity. From our results, it is suggested that VrD1, in addition to gamma-thionins and several amylase inhibitors, is highly homologous to scorpion toxins, especially the short toxins. Moreover, based on the observation from our homology structures, VrD1 may utilize a newly found cluster of basic residues to achieve its insecticidal function, whereas all the other plant gamma-thionins were known to use a previously identified basic cluster conserved for gamma-thionins. Considering the general feature of short scorpion toxins to act on insect cell membranes with K(+)- or Cl(-)-channels as molecular targets, our analysis of interaction and recognition modes provides reasonable correlations between this newly found basic cluster and the insecticidal activity of VrD1, which is also comprehended as a possible link for "homoplasy evolution" between plant and animal defensin molecules.

Amino Acid Sequence↗
PubMed1996

Crystal structure of an acidic neurotoxin from scorpion Buthus martensii Karsch at 1.85 A resolution.

The crystal structure of an acidic scorpion neurotoxin, BmK M8, purified from Chinese scorpion Buthus martensii Karsch (BmK), has been determined by the molecular replacement method. It is the first structure of an acidic alpha-scorpion neurotoxin reported so far. The crystals adopt a symmetry of space group P2(1) and contain one molecule per asymmetric unit. The structure has been refined to an R factor of 18.1% using reflection data in the range of 8 to 1.85 A resolution, with standard deviations from ideal geometry of 0.017 A and 2.43 degrees for bond length and angle, respectively. The 12 residues at the C terminus with unknown sequence were determined by crystallographic refinement. The refined model shows that the structural core, consisting of a motif beta alpha beta beta, is similar to that of toxin II from Androctonus australis Hector (AaH II) or Variant 3 from Centruroides sculpturatus Ewing (CsE V3). The three conformationally variable loops protruding from this structural core are different from that of AaH II, and especially from that of CsE V3. Compared with the most potent and basic alpha-toxin AaH II, the BmK M8 is a relatively inactive toxin (1100 times less active than AaH II) with an unusually low isoelectric point (pI 5.3). Sequence alignment of the two toxins shows a difference of 26 residues (40.6%). Among them four basic or neutral residues in AaH II, namely Val10, Lys28, Val55 and Gly59, are changed to acidic glutamate in BmK M8. The residues Glu10, Glu28 and Glu55 of BmK M8 are located on a surface (Face B), opposite the "conserved hydrophobic surface" (Face A). The latter is a functionally important area proposed by Fontecilla-Camps et al. Our observations suggest that in addition to Face A, Face B may also be involved in the biological activity of scorpion toxins. The structure of BmK M8 shows an evident conformational change of the alpha-amino group at the N terminus and a deorganization of Arg2 caused by the mutation D53A. These structural changes may also be responsible for the weak toxicity of BmK M8. In association with the information from chemical modifications, a multisite binding mode for toxin-receptor interaction and three "toxic regions" in relevance to the binding process, including Face A, Face B and Site C, are proposed. Face A, mainly consisting of Tyr5, 35, 47, the alpha-amino group, Arg2 and Asp3, may be more essential for the binding. Face B, mainly comprising conserved residues Tyr14, 21, Lys28 and Val55, may contribute to the high efficacy of the binding process and substitutions by acidic residues in this area could strongly weaken the toxic activity. Site C, formed by Lys58 and Arg62 at the C terminus and Arg41 and Tyr42 from loop 38-44, may be involved in binding site specificity.

Amino Acid Sequence↗
PubMed1983

Sodium-channels in non-excitable glioma cells, shown by the influence of veratridine, scorpion toxin, and tetrodotoxin on membrane potential and on ion transport.

Veratridine induces membrane potential oscillations in non-excitable glioma cells, which are not affected by ouabain (2 mM) or by D600 (0.1 mM). In the presence of veratridine, scorpion toxin causes depolarization of the glioma cells to a positive value of the membrane potential. These effects of veratridine and of scorpion toxin are observed in Na+ but not in choline medium and are inhibited by tetrodotoxin. The response of the glioma cells to bradykinin has also been studied during these experiments. Previously bradykinin has been shown in these cells to induce a hyperpolarizing response caused by an increase in K+ conductance. This response to bradykinin can still be seen during the veratridine-induced oscillations of the membrane potential. In the glioma cells the uptake of guanidinium, a substitute for Na+, is enhanced by veratridine plus scorpion toxin. This stimulation is tetrodotoxin-sensitive. However, in the excitable neuroblastoma X glioma hybrid cells studied for comparison, veratridine causes membrane potential oscillations accompanied at the rising phase by one action potential or a train of action potentials. The results demonstrate that in non-excitable glioma cells tetrodotoxin-sensitive Na+ channels can be activated by veratridine and by scorpion toxin.

Animals↗
PubMed1990

The complete amino acid sequence of toxin TsTX-VI isolated from the venom of the scorpion Tityus serrulatus.

The complete sequence of the toxin TsTX-VI from the venom of the scorpion Tityus serrulatus Lutz and Mello is presented. The sequence has been determined by automated Edman analysis of the reduced and carboxymethylated protein as well as of the resulting peptides, obtained from S. aureus protease and tryptic digestions. TsTX-VI is composed of 62 residues and has a calculated molecular weight of 6717. Homology studies with other scorpion toxins show that TsTX-VI is more similar to the Old World than to the North American scorpion toxins. The hydropathic index indicates that TsTX-VI is more hydrophobic than Ts-gamma. Toxicity studies carried out in mice demonstrate that i.v. injection of TsTX-VI is unable to evoke the usual symptoms induced by the typical neurotoxins of this venom, but only a generalized allergic reaction. These properties are important in clarifying the relationship between primary structure and biological function of scorpion toxins.

Amino Acid Sequence↗
PubMed1999

Dynamic diversification from a putative common ancestor of scorpion toxins affecting sodium, potassium, and chloride channels.

Scorpions have survived successfully over millions of years without detectable changes in their morphology. Instead, they have developed an efficient alomonal machinery and a stinging device supporting their needs for prey and defense. They produce a large variety of polypeptidic toxins that bind and modulate ion channel conductance in excitable tissues. The binding site, mode of action, and chemical properties of many toxins have been studied extensively, but little is known about their genomic organization and diversity. Genes representing each of the major classes of Buthidae scorpion toxins, namely, "long" toxins, affecting sodium channels (alpha, depressant, and excitatory), and "short" toxins, affecting potassium and chloride channels, were isolated from a single scorpion segment and analyzed. Each toxin type was found to be encoded by a gene family. Regardless of toxin length, 3-D structure, and site of action, all genes contain A+T-rich introns that split, at a conserved location, an amino acid codon of the signal sequence. The introns vary in length and sequence but display identical boundaries, agree with the GT/AG splice junctions, and contain T-runs downstream of a putative branch point, 5'-TAAT-3'. Despite little sequence similarity among all toxin classes, the conserved gene organization, intron features, and common cysteine-stabilized alpha-helical (CSH) core connecting an alpha-helix to a three-stranded beta-sheet suggest, that they all evolved from an ancestral common progenitor. Furthermore, the vast diversity found among genomic copies, cDNAs, and their protein products for each toxin suggests an extensive evolutionary process of the scorpion "pharmaceutical factory," whose success is due, most likely, to the inherent permissiveness of the toxin exterior to structural alterations.

Amino Acid Sequence↗
PubMed1983

High-affinity binding of alpha-scorpion toxin: a neuronal property.

alpha-Scorpion toxin binding to its receptor--one component of the voltage-sensitive sodium channel--was studied in an attempt to define its phenotypic specificity. To this end we investigated the ability of neuronal, glial myogenic and fibroblastic cell lines to bind alpha-toxin II, purified from venom of the scorpion Androctonus australis Hector. A single class of saturable high-affinity (Kd congruent to 1 nM) binding sites, was present only in cell lines exhibiting some of the characteristics of normal neuronal cells, such as the N18, NIE-115, NS20, BN10-10, NG108-15 and T28 cell lines. NIA-103, which is an electrically non-excitable neuronal cell, gave negative results. In glial (G26-20, TR6B, C6) myogenic (T984) or fibroblastic (L) cell lines, we were unable to detect high-affinity binding sites for alpha-scorpion toxin. Primary cultures of rat skeletal muscle cells were also negative. Thus specific binding in the nanomolar range seems to be selectively associated with the neuronal phenotype. alpha-Scorpion toxin binding was tested before and after induction of neurites: in N18, NIE-115, NS20 cell lines, the differentiation brought on an increase in the number of binding sites but had little effect on the dissociation constant; in the hybrids NG108-15 and T28 high affinity saturable binding sites were detectable after but not prior to morphological differentiation.

Animals↗
PubMed1985

Polymorphism and quantitative variations of toxins in the venom of the scorpion Androctonus australis Hector.

Using highly specific radioimmunoassays for toxins I, II and III of the scorpion Androctonus australis Hector, the concentrations of these neurotoxins have been determined in pooled as well as in individual samples. Variations were found that support polymorphism of scorpion toxins at an individual level. Radioimmunoassays were also used to detect toxin I of Buthus occitanus tunetanus and toxin II of Androctonus australis Hector and also antigenically homologous toxins in the venoms of several North African scorpions. These results are interpreted in terms of scorpion serotherapy.

Animals↗
PubMed2005

Purification and characterization of a novel lipase from the digestive glands of a primitive animal: the scorpion.

Higher animal's lipases are well characterized, however, much less is known about lipases from primitive ones. We choose the scorpion, one of the most ancient invertebrates, as a model of a primitive animal. A lipolytic activity was located in the scorpion digestive glands, from which a scorpion digestive lipase (SDL) was purified. Pure SDL, a glycosylated protein, has a molecular mass of 50 kDa, it presents the interfacial activation phenomenon. It was found to be more active on short-chain triacylglycerols than on long-chain triacylglycerols. SDL is a serine enzyme and possesses one accessible sulfhydryl group which is not essential for the catalysis. Among the NH2-terminal 33 residues, a 17 amino acids sequence shows similarities with sequence of Drosophila melanogaster putative lipase. Interestingly, neither colipase, nor bile salts were detected in the scorpion hepatopancreas. This indicates that colipase evolved in vertebrates simultaneously with the appearance of an exocrine pancreas and a true liver which produces bile salts. Furthermore, polyclonal antibodies directed against SDL failed to recognise the classical digestive lipases. Altogether, these results suggest that SDL is a member of a new group of digestive lipases belonging to invertebrates.

Amino Acid Sequence↗