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At least 793 records · Page 44Linked to original sources
PubMed1988

Case report: dapsone hypersensitivity syndrome associated with treatment of the bite of a brown recluse spider.

Dapsone (4-4-diaminodiphenyl-sulfone) is a member of the sulfone group of antibiotics used in the treatment of leprosy and various dermatitidies and more recently employed in the management of local reactions to the bite of the brown recluse spider, Loxosceles reclusa. A dapsone hypersensitivity syndrome, consisting of fever, headache, nausea, vomiting, lymphadenopathy, hepatitis, hemolysis, leukopenia, and mononucleosis, has been described in patients treated with the drug for leprosy. A case report of the hypersensitivity syndrome occurring in a patient being treated with dapsone for a brown recluse spider bite is presented.

Anemia, Hemolytic↗
PubMed2001

The use of stimulus dimensions in judgement making in spider fearful and nonfearful individuals.

This study uses a multidimensional scaling approach to investigate the hypothesis that spider fearful individuals give priority to a threat-safety dimension when making judgments. The results show that when making judgments about stimuli, spider fearful individuals (1) placed significantly greater comparative weighting on a threat-relevant dimension than on a non-emotive dimension (colour), and (2) tended to rate threatening pairs of stimuli and safe pairs of stimuli as more similar than did the nonfearful group. This prioritised dimensional processing suggests a mechanism by which phobics can exhibit what initially appear to be paradoxical tendencies to give priority to both threat and safety information.

Adult↗
PubMed1997

One-session group therapy of spider phobia: direct versus indirect treatments.

Forty-six patients with spider phobia, fulfilling the DSM-IV criteria for specific phobia, were assessed with behavioral, physiological and self-report measures. They were randomly assigned to three group treatment conditions: (1) direct treatment; (2) direct observation; and (3) indirect observation. All treatments were carried out in large groups of eight patients, and consisted of one 3 hr session of massed exposure and modelling. The results showed that on the behavioral test, measures and the specific self-report measures of spider phobia the direct treatment was significantly better than direct observation and indirect observation, which did not differ. On the physiological measures and the psychopathology self-report measures there were significant pre-post improvements, but no differences between the groups. The effects were maintained or furthered at the one year follow-up assessment. The proportion of clinically significantly improved patients were, at post-treatment, 75% in the direct treatment, 7% in the direct observation, and 31% in the indirect observation group. At follow-up, the corresponding figures were 75, 14, and 44%, respectively. The conclusion that can be drawn is that direct treatment is the treatment of choice.

Adult↗
PubMed2003

The role of 20-hydroxyecdysone on the control of spider vitellogenesis.

We investigated the role of 20-hydroxyecdysone (20E) on the ovarian maturation and protein levels and pattern in adult females of the spider Tegenaria atrica. In unmated females, the ovaries did not initiate vitellogenesis and levels of proteins in the hemolymph and ovaries were low. Unmated females treated with 20E showed an increase in the total amount of proteins in their hemolymph and ovaries, comparable with that in untreated mated females. Vitellogenesis was observable histologically in 20E treated unmated females as in untreated mated ones. The electrophoretic analysis of total proteins revealed a 47 kDa band expressed in the vitellogenic ovaries and hemolymph of 20E treated unmated females and untreated mated ones as in newly laid eggs. We hypothesize that this 47 kDa protein could belong to the vitellogenin-vitellin complex. We describe in this paper, for the first time in a spider, the partial characterization of putative yolk protein.

Amino Acid Sequence↗
PubMed1989

Management of the brown recluse spider bite.

The objectives in the treatment of the brown recluse spider bite are to prevent skin necrosis and the need for reconstructive surgery. A simple technique that consists of curetting the subcutaneous tissue in the necrotic area of the lesion, to prevent the local destructive actions of the toxin, is described. From 1981 to 1987, 18 patients were treated with this technique. The wounds were generally curetted under local anesthesia in an outpatient setting. In all but one case, the erythema, edema, and pain resolved significantly in 24 to 48 hours, and the wounds healed primarily with minimal scarring. We consider curettage the treatment of choice for brown recluse spider bites when the lesions are noted in relatively early stages. It can be performed as an outpatient procedure; it controls the symptoms and prevents further necrosis, with excellent cosmetic results.

Adolescent↗
PubMed2002

Ultrastructure of the major ampullate gland of the black widow spider, Latrodectus hesperus.

Silk production in the spider occurs within specialized glands that are capable of the synthesis of large fibrous proteins and the post-translational processing of those proteins to form an insoluble fiber. The major ampullate gland of Latrodectus hesperus (black widow) is similar in morphology to those found in the Araneid spiders. The tail domain of this gland is highly protein synthetic, giving rise to a core, fibrous protein product. In addition to a storage function, the ampulla region also synthesizes and exports an electron dense material that appears to form a 'coat' surrounding the silk generated within the tail. The duct of the gland consists of at least two distinct cell types: one type contains 'honeycomb' vesicles of unknown function, while the other possesses elaborate apical microvilli that may be involved in the reabsorption of water and subsequent dehydration of the silk. As the silk product transits through these various stages of assembly, it can been seen to undergo a condensation or concentration, possibly reflecting the influence of both the shear forces induced by movement into the duct and the dehydration that is thought to occur there.

Animals↗
PubMed2001

Sandwich-ELISA detection of venom antigens in envenoming by Phoneutria nigriventer spider.

Enzyme linked immunosorbent assays (ELISA) were developed to detect antigens from Phoneutria nigriventer spider venom. Horse anti-P. nigriventer immunoglobulins were prepared by immunoaffinity chromatography and used to set up a sandwich-type ELISA. The specificity of the assay was demonstrated by its capacity to correctly discriminate between the circulating antigens in mice that were experimentally inoculated with P. nigriventer venom from those in mice inoculated with Lycosa sp. and Loxosceles intermedia spider venoms, Tityus serrulatus scorpion venom and Apis mellifera bee venom. Measurable absorbance signals were obtained with 0.8ng of venom per assay. The ELISA was used to follow the kinetic distribution of antigens in experimentally envenomed mice and to detect antigens in the sera of patients envenomed by P. nigriventer.

Animals↗
PubMed2001

Effects of a Lasiodora spider venom on Ca2+ and Na+ channels.

The venom of a Brazilian spider, Lasiodora sp (Mygalomorphae, Theraphosidae), was screened for activity against ion channels using Ca2+ imaging and whole-cell patch clamp in GH3 cells. When tetrodotoxin (TTX) was present to block Na+ channels, the venom abolished the Ca2+ oscillations that are normally present in these cells and reduced the basal level of intracellular Ca2+. Under patch clamp, the venom reduced the L-type Ca2+ channel conductance and caused a positive shift in its voltage dependence of activation. In addition to these effects, when applied without TTX, the venom also caused a slow and noisy increase in intracellular Ca2+. The sensitivity of this second effect to TTX suggested an effect on Na+ channels, which was tested using patch clamp. Control Na+ currents inactivated completely as a single exponential. Treatment with the venom did not affect the amplitude of I(Na), but caused it to divide in two slower exponential components plus a sustained component, all of which were suppressed by TTX. The venom also caused a negative shift in the voltage dependence of activation and steady-state inactivation of I(Na). The observed effects of this venom on whole-cell currents explain the changes it causes in intracellular Ca2+ in GH3 cells and demonstrate that the venom of this spider is a source of toxins active against ion channels.

Algorithms↗
PubMed1998

Evidence that histamine is the principal pharmacological component of venom from an Australian wolf spider (Lycosa godeffroyi).

Wolf spiders are common throughout Australia and have been known to cause severe reactions in both animals and humans. However, little work has been done on the pharmacological activity of Australian lycosids. The purpose of this study was to obtain a preliminary pharmacological profile of the venom from an Australian wolf spider (Lycosa godeffroyi). The venom caused dose-dependent contractions of guinea-pig isolated ileum (1-4 microg/ml), endothelium-dependent relaxation in rat isolated aortae (10 microg/ml), a decrease in mean arterial blood pressure in the anaesthetised rat (100 microg/kg, i.v.) and an increase in insufflation pressure in the anaesthetised guinea-pig (50 microg/kg, i.v.). All of these responses were significantly inhibited by the H1-receptor antagonist mepyramine at concentrations that selectively inhibited responses to histamine. Venom (5 microg/ml) caused a decrease in twitch height of the rat stimulated (0.3 msec, 0.2 Hz, 100 V) vas deferens (prostatic segment). A fluorometric assay for histamine detected a concentration of 44.5 ng/microg venom protein. It appears that the in vitro and in vivo activity of L. godeffroyi venom observed in the present study is due to the presence of histamine.

Animals↗
PubMed1998

Structural characterization of a new acylpolyaminetoxin from the venom of Brazilian garden spider Nephilengys cruentata.

The use of mass spectrometry, in which high-energy CID and charge remote fragmentation both of protonated and sodium-attached molecular ions was applied, afforded the structural elucidation of a new acylpolyaminetoxin with Mw=801 Da from the venom of the Brazilian garden spider Nephilengys cruentata. In spite of having the same Mw of the NPTX-2, previously described in the venom of the Joro spider Nephila clavata, neither toxins are isomers. In order to differentiate them by using the most usual nomenclature, the new toxin was named NPTX-801C and the NPTX-2 was renamed to NPTX-801E. Both toxins have as common structure the 4-hydroxyindole-3-acetyl-asparaginyl-cadaveryl moiety in their molecules and their structure may be represented in a simplified way: NPTX-801E is HO-indole-Asn-Cad-Pta-Orn-Arg and NPTX-801C is HO-indole-Asn-Cad-Gly-Put-Pta-Pta.

Amino Acids↗
PubMed1998

Investigation of the effect of PhTx2, from the venom of the spider Phoneutria nigriventer, on the release of [3H]-acetylcholine from rat cerebrocortical synaptosomes.

Venoms from spiders are an important source of toxins that can help on the dissection of mechanisms involved in neurotransmission. Among them is the venom of the spider Phoneutria nigriventer that contains several toxic fractions with different targets in mammals and/or insects. We here report that one of these fractions (PhTx2) is able to evoke acetylcholine release from rat cortical synaptosomes and that this effect is dependent on extracellular calcium and is inhibited by the sodium channel blocker tetrodotoxin.

Acetylcholine↗
PubMed2000

Cloning and functional expression of a synthetic gene encoding huwentoxin-I, a neurotoxin from the Chinese bird spider (Selenocosmia huwena).

Cloning and functional expression of a synthetic gene encoding huwentoxin-I, a neurotoxin from the Chinese bird spider Selenocosmia huwena. A gene encoding huwentoxin-I, a peptide neurotoxin consisted of 33 amino acid residues from the venom of the Chinese bird spider Selenocosmia huwena, was designed, synthesized and expressed in Escherichia coli as a hybrid protein fused with glutathione S-transferase at the N-terminal. The fusion protein was purified by GSH-Sepharose 4B affinity column chromatography and cleaved by thrombin to release the toxin peptide. The amino acid sequence of the recombinant toxin was consistent with the designed one by sequence determination and MALDI-TOF mass analysis, suggesting that the recombinant huwentoxin-I produced the same expression product as the native one. After reduction and renaturation, the biological activity of the recombinant toxin was identical with that of the native huwentoxin-I by electrophysiological method.

Amino Acid Sequence↗
PubMed1996

Wound assessment of the Loxosceles reclusa spider bite.

OBJECTIVE: The purpose of this study was to determine the data that are most important for nurses to recognize in the assessment of a Loxosceles reclusa (brown recluse) spider bite. Given such assessment elements, it may be possible to decrease the severity of complications and complexity of care by providing the most appropriate therapy. METHODS: This study involved a retrospective review of 39 identified patient charts. Aspects that were examined included demographics, wound assessments, and outcome data. Patients who came to the study facility within 48 hours of the bite and whose diagnosis was a probable or possible brown spider bite met inclusion criteria. RESULTS: Data analysis revealed that the majority of patients sustained bites on the extremities and that those bites produced the most commonly noted symptoms. This is the first study in which specific local and systemic symptoms have been quantified and related to the wound area. Because of varied treatment and limited follow-up, determining the relationship between wound assessment and outcome was problematic. DISCUSSION: Ongoing studies, in contrast to retrospective review, are needed to reduce the limitations of this study, such as the loss of patients to follow-up. Areas for further research include the replication of this study and detailed analysis of treatment variables in relation to wound outcome.

Adolescent↗
PubMed2000

Beta transition and stress-induced phase separation in the spinning of spider dragline silk.

Spider dragline silk is formed as the result of a remarkable transformation in which an aqueous dope solution is rapidly converted into an insoluble protein filament with outstanding mechanical properties. Microscopy on the spinning duct in Nephila edulis spiders suggests that this transformation involves a stress-induced formation of anti-parallel beta-sheets induced by extensional flow. Measurements of draw stress at different draw rates during silking confirm that a stress-induced phase transition occurs.

Animals↗
PubMed2001

Spider silk fibre extrusion: combined wide- and small-angle X-ray microdiffraction experiments.

The major and minor ampullate silks from live Nephila senegalensis (Tetragnathidae) and the major ampullate silk from Euprostenops spp. (Pisauridae) spiders were investigated in situ by X-ray diffraction during forced silking. Wide- (WAXS) and small-angle (SAXS) scattering patterns were obtained at the same time. WAXS data show that the thread at the exit of the spigots already contains beta-sheet poly(alanine) crystallites. SAXS data suggest the presence of microfibrils with an axial repeating period of approximately 8 nm for both Nephila and Euprostenops. Minor ampullate (MI) Nephila silk, however, does not show this axial repeat which is probably due to a higher amount of crystal forming poly(alanine). A microfibrillar morphology, connected by a network of random polymer chains, can explain the presence of highly oriented crystallites, an oriented halo and a diffuse background in the WAXS patterns. At high reeling speeds, bound water is co-extruded with the fibre. It can be squeezed out of the fibre by friction at a needle. Under natural conditions it is the spider's tarsal claws which might serve to squeeze out the water to improve the mechanical properties of the thread during dragline production.

Animals↗
PubMedDate not supplied

Biology of spider silk.

Studies are beginning to show that spider silk can be highly variable in chemical composition and mechanical properties. Clearly, both external and internal conditions affect silk production and thus the mechanical properties of the finished thread. An argument can be made that silk is optimised for a wide range of conditions rather than maximised for strength or toughness. Moreover, it seems that the spider is able to induce rapid and temporary adaptations of silk properties.

Amino Acids↗
PubMedDate not supplied

Supercontracted spider dragline silk: a solid-state NMR study of the local structure.

The local structure of supercontracted dragline silk from the spider Nephila madagascariensis was investigated by solid-state nuclear magnetic resonance. Two-dimensional (2D) spin-diffusion experiments did not show any significant conformational changes in short-range order (and the secondary structure of the protein) upon supercontraction. Our results are in accordance with the proposal by Vollrath et al. (Proc R Soc London B 1996;263:147-151) that urea-supercontraction does not alter the local structure of spider dragline silk fundamentally. However, significant differences in the dynamics of the polypeptide chain upon supercontraction are detected at room temperature. At low temperature, these dynamics are frozen out. In addition, the role of the solvent (water) in the silk is investigated in Nephila edulis. Mobile water is detected at temperatures significantly below the freezing point of bulk water.

Alanine↗
PubMedDate not supplied

Transmission of vibrations in funnel and sheet spider webs.

Behavior of the funnel web building spider, Hololena curta, was observed. The spider is dependent on vibratory signals transmitted through the web. Prey localization usually necessitates two to four pauses and reorientation, and cannot proceed if the prey ceases to struggle. Treating the web as a stretched membrane, we calculated fundamental and overtone normal frequencies and transmission velocities. Unlike the results reported for orb webs, resonance does appear to be a significant factor in the funnel web.

Algorithms↗