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Made available in DSpace on 2022-05-01T09:47:17Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-12-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Universidade Federal do Paraná Fundação Araucária Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Accidents involving Brown spiders are reported throughout the world. In the venom, the major toxins involved in the deleterious effects are phospholipases D (PLDs). In this work, recombinant mutated phospholipases D from three endemic species medically relevant in South America (Loxosceles intermedia, L. laeta and L. gaucho) were tested as antigens in a vaccination protocol. In such isoforms, key amino acid residues involved in catalysis, magnesium-ion coordination, and binding to substrates were replaced by Alanine (H12A-H47A, E32A-D34A and W230A). These mutations eliminated the phospholipase activity and reduced the generation of skin necrosis and edema to residual levels. Molecular modeling of mutated isoforms indicated that the three-dimensional structures, topologies, and surface charges did not undergo significant changes. Mutated isoforms were recognized by sera against the crude venoms. Vaccination protocols in rabbits using mutated isoforms generated a serum that recognized the native PLDs of crude venoms and neutralized dermonecrosis and edema induced by L. intermedia venom. Vaccination of mice prevented the lethal effects of L. intermedia crude venom. Furthermore, vaccination of rabbits prevented the cutaneous lesion triggered by the three venoms. These results indicate a great potential for mutated recombinant PLDs to be employed as antigens in developing protective vaccines for Loxoscelism. Department of Cell Biology Federal University of Paraná (UFPR) Production and Research Center of Immunobiological Products (CPPI) State Department of Health Veterinary Hospital Federal University of Paraná (UFPR) Department of Structural Molecular Biology and Genetics State University of Ponta Grossa (UEPG) Multiuser Center for Biomolecular Innovation Departament of Physics Universidade Estadual Paulista (UNESP) Multiuser Center for Biomolecular Innovation Departament of Physics Universidade Estadual Paulista (UNESP) Universidade Federal do Paraná: 02/2020 Universidade Federal do Paraná: 04/2019 Fundação Araucária: 057/2017 CNPq: 303868/2016-3 CNPq: 408633/2018-2

Mais conhecida como aranha marrom, o aracnídeo do gênero Loxosceles pode ser encontrado por todo país, porém é mais presente na região sul. São animais não agressivos e de hábitos noturnos que geralmente picam quando comprimidas contra o corpo. Devido a tal característica as picadas geralmente acontecem ao dormir ou vestir roupas e em locais cobertos como raiz da coxa e tronco. A picada do aracnídeo tem como característica ser indolor, por isso muitas vezes não são percebidas pelo paciente. Os sintomas são predominantemente locais e se iniciam lenta e progressivamente de 24-72 horas após a picada. Os mais comuns são o rash, dor e edema.

Loxosceles spp. (Araneae, Sicariidae), known as brown spiders, are distributed in temperate and tropical regions worldwide. Accidents caused by these spiders are known as loxoscelism and constitute a public health problem, especially in Brazil. The present review describes the taxonomy, distribution, and ecological profile of brown spiders, as well as the molecular and biochemical aspects of Loxosceles venom. Additionally, it presents an overview on L. similis, a species found in the Southeastern region of Brazil. In this region, the number of Loxosceles accidents has been increasing in the past few years, thus calling attention to its raising importance as a medically relevant spider species in Brazil.

Brown spider (genus Loxosceles) venoms are mainly composed of protein toxins used for predation and defense. Bites of these spiders most commonly produce a local dermonecrotic lesion with gravitational spread, edema and hemorrhage, which together are defined as cutaneous loxoscelism. Systemic loxoscelism, such as hematological abnormalities and renal injury, are less frequent but more lethal. Some Loxosceles venom toxins have already been isolated and extensively studied, such as phospholipases D (PLDs), which have been recombinantly expressed and were proven to reproduce toxic activities associated to the whole venom. PLDs have a notable potential to be engineered and converted in non-toxic antigens to produce a new generation of antivenoms or vaccines. PLDs also can serve as tools to discover inhibitors to be used as therapeutic agents. Other Loxosceles toxins have been identified and functionally characterized, such as hyaluronidases, allergen factor, serpin, TCTP and knottins (ICK peptides). All these toxins were produced as recombinant molecules and are biologically active molecules that can be used as tools for the potential development of chemical candidates to tackle many medical and biological threats, acting, for instance, as antitumoral, insecticides, analgesic, antigens for allergy tests and biochemical reagents for cell studies. In addition, these recombinant toxins may be useful to develop a rational therapy for loxoscelism. This review summarizes the main candidates for the development of drugs and biotechnological inputs that have been described in Brown spider venoms.

Spiders of the genus Loxosceles, popularly known as Brown spiders, are considered a serious public health issue, especially in regions of hot or temperate climates, such as parts of North and South America. Although the venoms of these arachnids are complex in molecular composition, often containing proteins with distinct biochemical characteristics, the literature has primarily described a family of toxins, the Phospholipases-D (PLDs), which are highly conserved in all Loxosceles species. PLDs trigger most of the major clinical symptoms of loxoscelism i.e., dermonecrosis, thrombocytopenia, hemolysis, and acute renal failure. The key role played by PLDs in the symptomatology of loxoscelism was first described 40 years ago, when researches purified a hemolytic toxin that cleaved sphingomyelin and generated choline, and was referred to as a Sphingomyelinase-D, which was subsequently changed to Phospholipase-D when it was demonstrated that the enzyme also cleaved other cellular phospholipids. In this review, we present the information gleaned over the last 40 years about PLDs from Loxosceles venoms especially with regard to the production and characterization of recombinant isoforms. The history of obtaining these toxins is discussed, as well as their molecular organization and mechanisms of interaction with their substrates. We will address cellular biology aspects of these toxins and how they can be used in the development of drugs to address inflammatory processes and loxoscelism. Present and future aspects of loxoscelism diagnosis will be discussed, as well as their biotechnological applications and actions expected for the future in this field.

LiTCTP is a toxin from the Translationally Controlled Tumor Protein (TCTP) family identified in Loxosceles brown spider venoms. These proteins are known as histamine-releasing factors (HRF). TCTPs participate in allergic and anaphylactic reactions, which suggest their potential role as therapeutic targets. The histaminergic effect of TCTP is related to its pro-inflammatory functions. An initial characterization of LiTCTP in animal models showed that this toxin can increase the microvascular permeability of skin vessels and induce paw edema in a dose-dependent manner. We evaluated the role of LiTCTP in vitro and in vivo in the inflammatory and allergic aspects that undergo the biological responses observed in Loxoscelism, the clinical condition after an accident with Loxosceles spiders. Our results showed LiTCTP recombinant toxin (LiRecTCTP) as an essential synergistic factor for the dermonecrotic toxin actions (LiRecDT1, known as the main toxin in the pathophysiology of Loxoscelism), revealing its contribution to the exacerbated inflammatory response clinically observed in envenomated patients.

Bites by Loxosceles spiders (also known as recluse spiders or brown spiders) can cause necrotic ulcerations of various sizes and dimensions. The current standard of care for brown spider bites includes analgesics, ice, compression, elevation, antihistamines, and surgical debridement. Hyperbaric oxygen therapy (HBOT) in the treatment of brown spider bites has been administered in the early stage of ulceration, or 2 to 6 days after the bite. Unfortunately, the diagnosis of spider bite-related ulcers is often delayed and weeks or months may elapse before HBOT is considered.To evaluate the effect of HBOT on nonhealing wounds caused by brown spider bites in the late, chronic, nonhealing stage.Analysis of 3 patients with brown spider-bite healing wounds treated at The Sagol Center for Hyperbaric Medicine and Research in Israel. Patients presented 2 to 3 months after failure of other therapies including topical dressings, antibiotics, and corticosteroids. All patients were treated with daily 2 ATA (atmospheres absolute) with 100% oxygen HBOT sessions.All 3 patients were previously healthy without any chronic disease. Their ages were 30, 42, and 73 years. They were treated once daily for 13, 17, and 31 sessions, respectively. The wounds of all 3 patients healed, and there was no need for additional surgical intervention. There were no significant adverse events in any of the patients.Microvascular injury related to brown spider bites may culminate in ischemic nonhealing wounds even in a relatively young, healthy population. Hyperbaric oxygen therapy should be considered as a valuable therapeutic tool even months after the bite.

Loxoscelism is one of the most important forms of araneism in South America. The Health Authorities from countries with the highest incidence and longer history in registering loxoscelism cases indicate that specific antivenom should be administered during the first hours after the accident, especially in the presence or at risk of the most severe clinical outcome. Current antivenoms are based on immunoglobulins or their fragments, obtained from plasma of hyperimmunized horses. Antivenom has been produced using the same traditional techniques for more than 120 years. Although the whole composition of the spider venom remains unknown, the discovery and biotechnological production of the phospholipase D enzymes represented a milestone for the knowledge of the physiopathology of envenomation and for the introduction of new innovative tools in antivenom production. The fact that this protein is a principal toxin of the venom opens the possibility of replacing the use of whole venom as an immunogen, an attractive alternative considering the laborious techniques and low yields associated with venom extraction. This challenge warrants technological innovation to facilitate production and obtain more effective antidotes. In this review, we compile the reported studies, examining the advances in the expression and application of phospholipase D as a new immunogen and how the new biotechnological tools have introduced some degree of innovation in this field. Fil: Fingermann, Matias. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Salud de la Nación. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud "Doctor Carlos G. Malbrán". Instituto Nacional de Producción de Biológicos; Argentina Fil: de Roodt, Adolfo Rafael. Ministerio de Salud de la Nación. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud "Doctor Carlos G. Malbrán". Instituto Nacional de Producción de Biológicos; Argentina. Universidad de Buenos Aires. Facultad de Medicina; Argentina Fil: Cascone, Osvaldo. Ministerio de Salud de la Nación. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud "Doctor Carlos G. Malbrán". Instituto Nacional de Producción de Biológicos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Nanobiotecnología. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Nanobiotecnología; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología. Cátedra de Microbiología Industrial y Biotecnología; Argentina Fil: Miranda, Maria Victoria. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología y Biotecnología. Cátedra de Microbiología Industrial y Biotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Nanobiotecnología. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Nanobiotecnología; Argentina

Background Loxoscelism is caused by the bite of a specific spider type called the Loxosceles genus. In Turkey, most cases are seen after L. rufescens bites. Clinical manifestation of the bites ranges from local cutaneous reaction to severe ulcerative necrosis. Systemic loxoscelism may also occur. Case Herein, we report a previously healthy five-year-old male patient who developed a secondary hemophagocytic lymphohistiocytosis after a presumed brown spider bite. He was treated with dexamethasone. Within the following 14 days, hemophagocytic syndrome resolved. Local hyperbaric oxygen therapy was applied to the necrotic areas. Conclusion Secondary hemophagocytic lymphohistiocytosis may develop after systemic loxoscelism. In the presence of persistent fever, hepatosplenomegaly and laboratory findings this clinical entity should be kept in mind.

The Brazilian brown spider Loxosceles similis (Moenkhaus, 1898) is, like others from the same genus, an arachnid that can cause serious accidents, which is called loxoscelism. Here, we present the ...

Brown spiders are venomous arthropods that use their venom for predation and defense. In humans, bites of these animals provoke injuries including dermonecrosis with gravitational spread of lesions, hematological abnormalities and impaired renal function. The signs and symptoms observed following a brown spider bite are called loxoscelism. Brown spider venom is a complex mixture of toxins enriched in low molecular mass proteins (4–40 kDa). Characterization of the venom confirmed the presence of three highly expressed protein classes: phospholipases D, metalloproteases (astacins) and insecticidal peptides (knottins). Recently, toxins with low levels of expression have also been found in Loxosceles venom, such as serine proteases, protease inhibitors (serpins), hyaluronidases, allergen-like toxins and histamine-releasing factors. The toxin belonging to the phospholipase-D family (also known as the dermonecrotic toxin) is the most studied class of brown spider toxins. This class of toxins single-handedly can induce inflammatory response, dermonecrosis, hemolysis, thrombocytopenia and renal failure. The functional role of the hyaluronidase toxin as a spreading factor in loxoscelism has also been demonstrated. However, the biological characterization of other toxins remains unclear and the mechanism by which Loxosceles toxins exert their noxious effects is yet to be fully elucidated. The aim of this review is to provide an insight into brown spider venom toxins and toxicology, including a description of historical data already available in the literature. In this review article, the identification processes of novel Loxosceles toxins by molecular biology and proteomic approaches, their biological characterization and structural description based on x-ray crystallography and putative biotechnological uses are described along with the future perspectives in this field.

Loxoscelism (the term used to define accidents by the bite of brown spiders) has been reported worldwide. Clinical manifestations following brown spider bites are frequently associated with skin degeneration, a massive inflammatory response at the injured region, intravascular hemolysis, platelet aggregation causing thrombocytopenia and renal disturbances. The mechanisms by which the venom exerts its noxious effects are currently under investigation. The whole venom is a complex mixture of toxins enriched with low molecular mass proteins in the range of 5-40 kDa. Toxins including alkaline phosphatase, hyaluronidase, metalloproteases (astacin-like proteases), low molecular mass (5.6-7.9 kDa) insecticidal peptides and phospholipases-D (dermonecrotic toxins) have been identified in the venom. The purpose of the present review is to describe biotechnological applications of whole venom or some toxins, with especial emphasis upon molecular biology findings obtained in the last years.

Objectives: this study aimed to identify puerperal women’s level of knowledge about the Loxosceles spider, its bite, and their own conduct in the event of a loxoscelic accident involving them or their children. Methods: this was a quantitative cross-sectional study using a structured questionnaire that included the socioeconomic profile of the participants, and knowledge about the brown spider and loxoscelism. Participants included postpartum women (between the first to tenth day of delivery), admitted to the maternity ward of the Hospital do Trabalhador, Curitiba-PR, between July and October 2011. From a total of 208 postpartum women, eight were excluded because the questionnaires were filled incorrectly. Data were tabulated using Microsoft Excel 2007® and analyzed using the χ2 test and Fisher’s exact test. Results: regarding the knowledge about the spider, 61% of the participants said that they knew the spider and identified the correct picture. About their conduct in case of loxoscelic accidents, 87.5% gave appropriate responses, but only 37% identified the correct symptoms. Hypothesis testing revealed that age, education, and prior experience of loxoscelic accidents were directly proportional to the participants’ knowledge (p

Introduction: Loxosceles species, known as brown-spiders, are considered to be of medical importance, being responsible for the most severe form of araneism in Brazil. Loxosceles amazonica is a still little-studied species with wide geographic distribution in Northern, Northeastern, and Central-Western Brazil, although it is reported in a few localities. Objectives: new geographic records of L. amazonica are reported in northeastern Brazil in this study. Methods: occasional records for this spider were obtained in herpetological studies or fortuitously in urban environments, between September of 2011 and August of 2012. Results: specimens were found in the States of Paraiba (Matureia and Serra Branca), Pernambuco (Serra Talhada), and Maranhao (Itapecuru Mirim, Santa Ines, Arari, Buriticupu, and Bom Jesus das Selvas) in a synanthropic form associated with houses in altered areas, and in an autochthonous form in secondary forests, in Amazon and the Caatinga domains. Conclusions: there is little information about the epidemiology of accidents with L. amazonica, however, it is likely that the species is the primary etiological agent of loxoscelism in its distribution area, which allows recognizing the species as of medical importance.

Loxoscelism, the term used to describe lesions and clinical manifestations induced by brown spider's venom (Loxosceles genus), has attracted much attention over the last years. Brown spider bites have been reported to cause a local and acute inflammatory reaction that may evolve to dermonecrosis (a hallmark of envenomation) and hemorrhage at the bite site, besides systemic manifestations such as thrombocytopenia, disseminated intravascular coagulation, hemolysis, and renal failure. The molecular mechanisms by which Loxosceles venoms induce injury are currently under investigation. In this review, we focused on the latest reports describing the biological and physiopathological aspects of loxoscelism, with reference mainly to the proteases recently described as metalloproteases and serine proteases, as well as on the proteolytic effects triggered by L. intermedia venom upon extracellular matrix constituents such as fibronectin, fibrinogen, entactin and heparan sulfate proteoglycan, besides the disruptive activity of the venom on Engelbreth-Holm-Swarm basement membranes. Degradation of these extracellular matrix molecules and the observed disruption of basement membranes could be related to deleterious activities of the venom such as loss of vessel and glomerular integrity and spreading of the venom toxins to underlying tissues.

Background Acute generalized exanthematous pustulosis (AGEP) is a rare and severe cutaneous reaction usually triggered by drugs. Other causative factors such as viral infections are rarely involved. In this study, we report a case of AGEP caused by a spider bite. Case Summary A 56-year-old woman was referred to the allergy unit after a spider bite at the left popliteal fossa, while gardening, 5 days earlier. The offending spider was captured and identified by an entomologist as belonging to the Loxosceles rufescens species. No acute reaction was observed; however, after 24 hours, due to the occurrence of typical dermonecrotic skin lesions associated with erythema and edema, Cefuroxime and Clindamycin were administered intramuscularly after medical advice was given. Almost 72 hours after the spider bite, an erythematous and partly edematous eruption appeared locally in the gluteus area bilaterally, which progressively expanded to the trunk, arms and femors. Within 24 hours dozens of small, pinhead sized, non- follicular pustules were present, mainly in the folds. The patient complained of a burning sensation of the skin in addition to pruritus; and simultaneously had a fever of 38-39 °C as the eruption expanded. Discussion A spider bite may represent a possible causative factor of AGEP. A spider's venom contains sphingomyelinase that stimulates the release of IL8 and GM-CSF, which are involved in AGEP pathogenesis. Whether or not the con-current use of antibiotics has an effect in AGEP appearance when combined with a spider's venom, cannot be excluded.

Loxosceles is the most poisonous spider in Brazil and, at least, three different species of medical importance are known in Brazil (L. intermedia, L. gaucho, L. laeta), with more than 5000 cases of envenomation reported each year. In South Africa, L. parrami and L. spinulosa are responsible for cutaneous loxoscelism (Newlands et al., 1982). In Australia, a cosmopolitan species, L. rufescens, is capable of causing ulceration in humans. In the USA, at least five Loxosceles species, including L. reclusa (brown recluse), L. apachea, L. arizonica, L. unicolor and L. deserta are known to cause numerous incidents (Ginsburg W Gendron, 1990; Bey et al., 1997; Desai et al., 2000). Several studies have indicated that sphingomyelinase D (SMase D) present in the venoms of Loxosceles spiders is the main component responsible for the local and systemic effects observed in loxoscelism (Forrester et al., 1978; Kurpiewski et al., 1981; Tambourgi et al., 1998, 2000, 2002, 2004, 2005, 2007; van den Berg et al., 2002, 2007; Fernandes Pedrosa et al., 2002; Paixao Cavalcanti et al., 2006, Tambourgi et al., 2010). SMases D hydrolyze sphingomyelin resulting in the formation of ceramide-1-phosphate and choline (Forrester et al., 1978; Kurpiewski et al., 1981; Tambourgi et al., 1998) and, in the presence of Mg2+, are able to catalyze the release of choline from lysophosphatidylcholine (van Meeteren et al., 2004). All spider venom SMases D sequenced to date display a significant level of sequence similarity and thus likely possess the same (┙/┚)8 or TIM barrel fold (Murakami et al., 2005, 2006). Based on sequence identity, biochemical activity and molecular modelling, a scheme for classification of spider venom SMases D was proposed (Murakami et al., 2006). The class 1 enzymes include SMase I and H13, SMases D from L. laeta, which possess a single disulphide bridge and contain an extended hydrophobic loop or variable loop (Murakami et

We examined the post-embryonic development of the male and female genital apparatus of the brown spider, Loxosceles intermedia. The development of the genital apparatus for both sexes begins with the appearance of inner structures. In the male genital apparatus, formation of the testes occurs first, followed by differentiation of the duct, ampulla and vas deferens, and finally the formation of the genital opening and differentiation of the copulatory organ (secondary sexual characteristic). Similarly, the development of the female genital apparatus begins with the formation of the ovaries, followed by the appearance of oocytes in vitellogenesis, then the development of oviducts and uterus internus and, finally, the spermatheca. These data may be very important in further comparative studies on the development of the reproductive system of spiders.

Most arthropod bites and stings cause limited swelling, itching, pain, and redness and can be managed by ice application and tetanus prophylaxis as necessary. Stings by bees, wasps, and stinging ants can cause anaphylaxis that may require treatment with epinephrine and antihistamines and respiratory and cardiac maintenance measures. Widow spider bite management is controversial, but interventions for systemic reactions include calcium gluconate, methocarbamol, diazepam, narcotics, and antivenom. Victims of brown spider bites may need hospitalization if lesions enlarge rapidly or there are signs of systemic poisoning. Those stung by a bark scorpion may require oxygen, an intravenous line, pulse oximetry, and cardiac monitoring.

Loxosceles laeta é a espécie de aranha-marrom de maior importância médica, causando acidentes de maior gravidade, além de apresentar hábito sinantrópico. No presente trabalho, é apresentado o primeiro registro sinantrópico de Loxosceles laeta no Município do Rio de Janeiro, RJ, Brasil, a partir de encontro e coleta ocasional de espécimes, no período de agosto de 2005 a junho de 2009. A espécie foi registrada em um prédio do Museu Nacional/UFRJ, localizado no parque da Quinta da Boa Vista, área urbana na Zona Norte da Cidade do Rio de Janeiro. O foco foi considerado localizado e restrito. Loxosceles laeta é adaptável às condições climáticas da região metropolitana do Rio de Janeiro, o que torna possível o estabelecimento de novos focos da espécie e a ocorrência de loxoscelismo na região. Loxosceles laeta is the species of brown spider of greatest medical importance. It causes accidents of great severity and presents synanthropic habits. In this paper, the first synanthropic record of Loxosceles laeta in the municipality of Rio de Janeiro, RJ, Brazil, is presented. This came from occasional encounters and sampling of specimens between August 2005 and June 2009. The species was recorded in a building of the Museu Nacional/UFRJ, located in the Quinta da Boa Vista park, in the urban area of the northern zone of the city of Rio de Janeiro. The focus was considered to be localized and restricted. Loxosceles laeta is adaptable to the climatic conditions of the metropolitan region of Rio de Janeiro, which makes possible for new foci of the species to become established, with occurrences of loxoscelism in the region.

Some venomous spiders of the genus Loxosceles can reach high population densities inside and around houses. In Brazil, most spider accidents are related to Loxosceles intermedia. Control of loxoscelism should utilize integrated pest management tools, such as vacuum cleaners, to eliminate egg sacs, webs and spiders. The present study tested the efficacy of one type of vacuum cleaner (for professional and domestic use) in the control of L. intermedia populations. Cockroaches (Pycnoscelus surinamensis) were used in some tests for comparison. Vacuuming using standard accessories or a paper tube resulted in the death of all female (n=60), male (n=60), young (n=60) and just-hatched (n=60) L. intermedia, and all egg sacs (n=5) were destroyed. The removal of the plastic plate present at the bottom of the vacuuming tube inside the machine allowed some spiders to survive the vacuuming process. When kept inside a vacuum bag full of dust and debris, adult females (n=10) survived for 10 days; however, significant mortality was observed among male (n=10) and young individuals (n=10). Addition of cornstarch to the vacuum bag did not affect the spiders (n=20). Vacuum cleaners, such as the one used in the present investigation, are promising tools for integrated management of L. intermedia and other spiders in domestic environments.

The venom of the brown spider is remarkable because it causes dermonecrotic injury, hemorrhagic problems, hemolysis, platelet aggregation and renal failure. The mechanism by which the venom causes hemorrhagic disorders is poorly understood. Rabbits intradermally exposed to the venom showed a local hemorrhage starting 1 h after inoculation and reaching maximum activity between 2 and 3 days. Biopsies examined by light and transmission electron microscopy showed subendothelial blebs, vacuoles and endothelial cell membrane degeneration in blood vessels, plasma exudation into connective tissue, and fibrin and thrombus formation within blood vessels. Loxosceles intermedia venom incubated with fibrinogen partially degrades Aalpha and Bbeta chains of intact fibrinogen, and significantly cleaves all Aalpha, Bbeta and gamma chains when they were separated or when fibrinogen is denatured by boiling. Proteolytic kinetic studies showed that the Aalpha chain is more susceptible to venom hydrolysis than the Bbeta chain. The fibrinogenolysis is blocked by ethylenediamine tetraacetic acid and 1,10-phenanthroline, but not by other protease inhibitors. Human plasma incubated with the venom had coagulation parameters such as prothrombin time, activated partial thromboplastin time and thrombin time increased. Through molecular sieve chromatography, we isolated a venom toxin of 30 kDa with fibrinogenolytic activity. We propose that the local and systemic hemorrhagic disorders evoked in loxoscelism are consequences of direct venom fibrinogenolysis together with cytotoxicity to subendothelial structures and endothelial cells in blood vessels.

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. Discussions 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.

Diagnosis of the occurrence of the genus Loxosceles Heineken and Lowe, 1832 (Araneae, Sicariidae) in the municipal district of União da Vitória, Paraná. This paper aims to carry out a comparative evaluation of the populations of Loxosceles spp. (brown spiders) found in the municipal district of União da Vitória, Paraná. Natural and anthropic substrata were inspected in the intra- and peridomicile in urban and rural areas. Loxosceles intermedia Mello-Leitão, 1934 was present in 57% of the residences. It was not randomly distributed among the neighborhoods or the substrata and was less frequent than other species of spiders found in the same habitats. The few records of loxoscelism may be due to the small population of brown spiders in domestic habitats. Notwithstanding the seemingly adequate climatic and substratic conditions, the population growth of L. intermedia might be limited by the presence of other species inside and around houses. Esse trabalho tem por objetivo realizar um diagnóstico comparado da ocorrência de populações de Loxosceles sp. (aranha-marrom) no município de União da Vitória, Paraná. Foram inspecionados substratos naturais e antrópicos presentes no intra- e peridomicílio da área urbana e rural. Loxosceles intermedia Mello-Leitão, 1934 ocorreu em 57% das residências, porém não ocorreu homogeneamente entre os diferentes bairros e substratos e foi menos freqüente do que outras espécies de aranhas encontradas no mesmo habitat. A pequena notificação de loxoscelismo pode ser devida à pequena população de aranhas-marrom em ambientes domiciliares. Apesar de encontrar substratos e condições climáticas aparentemente adequadas no ambiente antrópico, o crescimento de populações de L. intermedia pode ser limitado pela presença de outras espécies de aranhas.

We present two patients with airway obstruction due to supraglottic swelling; one was caused by a brown spider bite on an ear (loxoscelism) and the other from eating buffalo fish. In the latter patient it was likely due to scrombroid poisoning, a histamine-like reaction, but may have been an anaphylaxic reaction.

Summary The first occurrence of Loxosceles laeta in North America is recorded and the habits of these spiders are described. Their venom possessed toxic properties like that of other Loxosceles spp., but specimens of the population under study seemed reluctant to bite guinea pigs. The spiders in this dense indoor infestation were controlled by applications of lindane and chlordane.

The brown recluse spider (Loxosceles reclusa), found in many areas of the United States, is capable of producing significant medical problems and potentially life-threatening systemic manifestations. This paper reviews the clinical presentation, diagnostic workup, pathophysiology, and management of the brown spider bite. Emphasis is placed on the potential for error in establishing this diagnosis. The need for a simplified management program is discussed along with current concepts on how to achieve this management program. Attention is also directed to the more serious complications.

Recent reports have suggested the use of dapsone for brown spider bites. This drug, for many years restricted to use in cases of leprosy and rare dermatologic disorders, has significant side effects that must be recognized. A case of methemoglobinemia is reported in one such patient treated with dapsone. The difficulty of making the diagnosis of brown spider bite is discussed.

Although the clinical course in this patient's illness was not proven to follow the bite of the brown spider, its characteristics seem identical with the proven cases reported in children. It thus would represent the first fatal case in an adult.

Made available in DSpace on 2022-04-28T20:55:53Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-10-12 Envenomations caused by Loxosceles (brown spider) have been reported throughout the world. Clinical signs associated to bites of these spiders involve dermonecrotic lesions and intense local inflammatory response, besides systemic manifestations such as intravascular hemolysis, thrombocytopenia, disseminated intravascular coagulation and acute renal failure. The present study aimed to report and to describe dermonecrotic lesions probably caused by a Loxosceles envenomation in a four year-old poodle female dog, treated at the Dermatology Service of the Veterinary Hospital of the Veterinary Medicine and Animal Husbandry School, São Paulo State University, Botucatu, Brazil. Initially, the animal presented two skin lesions with blackish aspect that evolved into ulcerative crusts. The owner reported the presence of a brown spider near the place where the animal spent most of the time. Histological examination of lesions revealed necrosis of the epidermis extending to adnexa and panniculi, which is compatible with Loxosceles bite reaction. The animal was treated with systemic antibiotic and local curatives. Lesions healed by second intention in two months. Department of Clinics Veterinary Medicine and Animal Husbandry School São Paulo State University, UNESP, Botucatu, São Paulo State Department of Pathology Botucatu Medical School São Paulo State University, UNESP, Botucatu, São Paulo State Departamento de Clínica Faculdade de Medicina Veterinária e Zootecnia UNESP, Distrito de Rubião Jr., s/n, Botucatu, SP, 18.618-000 Department of Clinics Veterinary Medicine and Animal Husbandry School São Paulo State University, UNESP, Botucatu, São Paulo State Department of Pathology Botucatu Medical School São Paulo State University, UNESP, Botucatu, São Paulo State Departamento de Clínica Faculdade de Medicina Veterinária e Zootecnia UNESP, Distrito de Rubião Jr., s/n, Botucatu, SP, 18.618-000

IN 1929, Schmaus1reported the treatment of the first documented case of cutaneous loxoscelism in North America with sedation, starch, and sodium bicarbonate, which was ineffective. Current therapies for brown spider bites, using corticosteroids, antibiotics, antihistaminics, and surgical excision, may not be much more effective management for the skin ulcer that the venom produces.2,3We have treated a documented bite from the brown recluse spiderLoxosceles reclusawith dapsone and produced a dramatic resolution of the skin lesion with no complications. Report of a Case A 27-year-old man killed a spider immediately after being bitten on the right leg while dressing. He went directly to the hospital emergency room, where no treatment was given because he was told that the spider was nonvenomous. He saw his private physician 24 hours later, after the bite site became larger (8×8 cm), swollen, and erythematous. He complained of itching and pain.

There are many different species of the Loxosceles throughout the continental United States. Several of these have been reported to cause arachnidism similar to that of the L reclusa , the brown spider. Thirty-three patients had L reclusa spider bites. Hospitalization and nonoperative treatment (11 cases), late incision (15 cases), and early excision (seven cases) led us to the conclusion that early excision of lesions greater than 1 cm is the best treatment. Early symptoms from the bite may be minor and delayed or occur within a few hours and be severe. Necrosis taking several weeks to heal is common. The bites are arranged in four categories of severity. A specific test for loxoscelism with radioactive thymidine is available, but anyone bitten by a spider should capture it and bring it with him to the physician.

The authors are correct when they state that there is no current laboratory book specifically for the multifacets of dermatology. However, there is a detailed one now in preparation. This compendium of Butterworth and See is an excellent introduction to the subject. It is something you could carry around in your pocket to give you a clue as to where to look. It provides no critical evaluation or significant interpretation. For the pediatrician, it may be necessary to add that in many states a brown spider is also found in addition to the black widow, and this spider can produce necrotic lesions in the child. Cutaneous congo-red tests may produce discoloration in children not only from local injection but also from intravenous use in cutaneous amyloidosis. Generalized herpetic dermatitis in children, the so-called Kaposi's varicelliform dermatitis, is associated usually with herpes simplex virus, whereas the coxsackievirus is found in herpangina.