Myotoxicity of Crotoxin on C2C12 Myoblasts and its Inhibition by Crotalus Neutralizing Factor versus Enhanced Resistance in Myotubes: Exploring Toxicity and Membrane Potential.

Background: Crotalus Neutralizing Factor (CNF) is a γ-type Phospholipase A2 (PLA2) inhibitor present in the blood of Crotalus durissus terrificus snake. Particularly, CNF inhibits the toxic action of Crotoxin (CTX), which is a major neurotoxin found in C. d.

Presence of Leishmania sp. amastigotes in the reproductive tract of dogs with visceral leishmaniasis.

Background: Although canine visceral leishmaniasis (CVL) transmission primarily occurs through the bite of phlebotomine sand flies infected with Leishmania infantum, alternative routes may exist.

Methods: Thirty-four dogs diagnosed with CVL were sampled for parasitological investigation in tissues from the reproductive tract.

Results: Amastigotes of Leishmania sp.

Entomological aspects of leishmaniasis transmission in the urban area of Teófilo Otoni, a municipality endemic for the disease in the Brazilian state of Minas Gerais.

Brazil is endemic for both visceral (VL) and cutaneous (CL) clinical forms of leishmaniasis, poverty-associated diseases with worldwide distribution. parasites are the etiological agents of leishmaniases, which are transmitted to humans through the bites of infected phlebotomine sand flies. From 2018 to 2023, 15 cases of VL and 129 cases of CL were reported in Téofilo Otoni, an important economic center in the Brazilian state of Minas Gerais.

The PLA inhibitor from Crotalus durissus terrificus blood plasma (CNF) inhibits group III-PLA from honeybee venom.

Crotalus neutralizing factor (CNF) is an endogenous glycoprotein from Crotalus durissus terrificus snake blood that inhibits secretory phospholipases A (sPLA) from the Viperid but not from Elapid venoms (subgroups IA and IIA, respectively). In the present study, we demonstrated that CNF can inhibit group III-PLA from bee venom by forming a stable enzyme-inhibitor complex. This finding opens up new possibilities for the potential use of CNF and/or CNF-based derivatives in the therapeutics of bee stings.

Mapping possible interaction sites for crotoxin in CNF, a gamma PLA inhibitor from Crotalus durissus terrificus rattle snake, using SPOT synthesis.

Phospholipases A (PLAs) are main components of snake venoms. Several snake species possess endogenous PLA inhibitors in their circulating blood, which are generally known as sbPLIs (an acronym for snake blood phospholipase Ainhibitors). The sbPLIs are categorized in three classes (alpha, beta or gamma) depending on the existence of distinguishing protein domains in their structure.

Survey of phlebotomine sand fly fauna in a public Zoo in Brazil: Species diversity, seasonality, and host variety.

Leishmaniasis is a dynamic disease in which transmission conditions change due to environmental and human behavioral factors. Epidemiological analyses have shown modifications in the spread profile and growing urbanization of the disease, justifying the expansion of endemic areas and increasing number of cases in dogs and humans. In the city of Belo Horizonte, located in the southeastern state of Minas Gerais (Brazil), visceral leishmaniasis (VL) is endemic, with a typical urban transmission pattern, but with different regional prevalence.

The Program for the Control of Visceral Leishmaniasis in Brazil: The Effect of the Systematic Euthanasia of Seropositive Dogs as a Single Control Action in Porteirinha, a Brazilian City with an Intense Transmission of Visceral Leishmaniasis.

Background: Porteirinha is endemic for visceral leishmaniasis (VL), with intense disease transmission of the disease. We evaluated the impact of canine euthanasia as a single control measure on the incidence of VL in humans and canines.

Methods: A prospective observational cohort study was carried out over four years (1998-2002) in 8 of the 12 neighborhoods of the city.

Effects of inhibition of 5-lipoxygenase and 12-lipoxygenase pathways on skeletal muscle fiber regeneration.

We investigated the effect of inhibition of 5-lipoxigenase (LOX) and 12-LOX pathways on the regeneration of skeletal muscle fibers after injury induced by a myotoxin (MTX) phospholipase A from snake venom in an in vivo experimental model. Gastrocnemius muscles of mice injected with MTX presented an increase in 5-LOX protein expression, while 12-LOX was found to be a constitutive protein of skeletal muscle. Animals that received oral treatments with 5-LOX inhibitor MK886 or 12-LOX inhibitor baicalein 30 min and 48 h after MTX-induced muscle injury showed a reduction in the inflammatory process characterized by a significant decrease of cell influx and injured fibers in the degenerative phase (6 and 24 h after injury).

The early inhibition of the COX-2 pathway in viperid phospholipase A-induced skeletal muscle myotoxicity accelerates the tissue regeneration.

The administration of non-steroidal anti-inflammatory drugs in the treatment of injury and muscle regeneration is still contradictory in effectiveness, especially regarding the timing of their administration. This can interfere with the production of prostaglandins originating from inflammatory isoform cyclooxygenase-2 (COX-2), which is essential to modulate tissue regeneration. The phospholipases A (PLA) from viperid venoms cause myotoxicity, therefore constituting a tool for the study of supportive therapies to improve skeletal muscle regeneration.

Structural basis of the myotoxic inhibition of the Bothrops pirajai PrTX-I by the synthetic varespladib.

Varespladib (LY315920) is a potent inhibitor of human group IIA phospholipase A (PLA) originally developed to control inflammatory cascades of diseases associated with high or dysregulated levels of endogenous PLA. Recently, varespladib was also found to inhibit snake venom PLA and PLA-like toxins. Herein, ex vivo neuromuscular blocking activity assays were used to test the inhibitory activity of varespladib.

Impact of vector control actions in the abundance of Lutzomyia longipalpis in Montes Claros, Brazil.

Visceral leishmaniasis (VL) is endemic to many states in Brazil. To prevent further expansion of the disease, the Brazilian Ministry of Health adopted integrated measures through the Program of Surveillance and Control of Visceral Leishmaniasis (PSCVL), whose actions include the diagnosis and euthanasia of seropositive dogs (the main domestic reservoirs), the use of residual insecticides, environmental management (EM) to control vector population (mainly Lutzomyia longipalpis phlebotomine), rigorous epidemiological surveillance, and health education. The present study was conducted in areas with recent moderate VL transmission to evaluate the efficacy of vector control activities.

Varespladib (LY315920) prevents neuromuscular blockage and myotoxicity induced by crotoxin on mouse neuromuscular preparations.

Varespladib (LY315920) is a synthetic phospholipase A (PLA) inhibitor that has been demonstrating antiophidic potential against snake venoms that present PLA neurotoxins. In this study, we evaluate the capacity of Varespladib to inhibit the neuromuscular effects of crotoxin (CTX), the main toxic component of Crotalus durissus terrificus snake venom, and its PLA subunit (CB). We performed a myographic study to compare the neuromuscular effects of CTX or CB and the mixture of these substances plus Varespladib in mice phrenic nerve-diaphragm muscle preparations.

Catalytically active phospholipase A myotoxin from Crotalus durissus terrificus induces proliferation and differentiation of myoblasts dependent on prostaglandins produced by both COX-1 and COX-2 pathways.

Although crotoxin B (CB) is a well-established catalytically active secretory phospholipase A group IIA (sPLA-IIA) myotoxin, we investigated its potential stimulatory effect on myogenesis with the involvement of prostaglandins (PGs) produced by cyclooxygenase (COX)-1 and -2 pathways. Myoblast C2C12 were cultured in proliferation or commitment protocols and incubated with CB followed by lumiracoxib (selective COX-2 inhibitor) or valeryl salicylate (selective COX-1 inhibitor) and subjected to analysis of PG release, cell proliferation and activation of myogenic regulatory factors (MRFs). Our data showed that CB in non-cytotoxic concentrations induces an increase of COX-2 protein expression and stimulates the activity of both COX isoforms to produce PGE, PGD and 15d-PGJ.

Crotalus Neutralizing Factor (CNF) inhibits the toxic effects of Crotoxin at mouse neuromuscular preparations.

Crotalus Neutralizing Factor (CNF) was the first phospholipase A inhibitor isolated from the plasma of the South American rattlesnake (Crotalus durissus terrificus). Previous biochemical and biophysical studies demonstrate an interaction of CNF with Crotoxin (CTX), the main toxic component in the venom of these snakes. CTX promotes the blockade of neuromuscular transmission by a sum of neurotoxic and myotoxic activities.

Interaction of Biomphalaria cells in primary cultures with Schistosoma mansoni sporocysts.

Introduction: Biomphalaria snails may display varying levels of susceptibility to Schistosoma mansoni infection. We have been developing an in vitro model to study the interaction between the snail and the parasite, using tissue-derived cell cultures from Biomphalaria.

Methods: The digestive gland- and kidney-derived cells from primary cultures of resistant (B.

Canine visceral leishmaniasis in area with recent Leishmania transmission: prevalence, diagnosis, and molecular identification of the infecting species.

Introduction: Canine visceral leishmaniasis (CVL) is an endemic disease in Brazil, and integrated control actions have been adopted by the Brazilian Ministry of Health to control its spread. However, the transmission profile is unknown in areas with recent CVL cases, including Itaúna, located in the Brazilian state of Minas Gerais, where the present study was carried out.

Methods: A total of 2,302 dogs from 12 neighborhoods were serologically tested for canine VL using the current diagnostic protocol adopted by the Brazilian Ministry of Health.

Ecology of phlebotomine sand flies in a Brazilian area with recent leishmaniasis transmission (Itaúna, in Minas Gerais state).

Introduction: Leishmaniasis constitutes a serious but neglected tropical disease. Recently, socio-environmental, biological and physical changes have altered the range of leishmaniasis, causing it to spread into urban areas. In Minas Gerais, the disease is endemic, exhibiting regional differences and reaching urban centers.

Identification and characterization of the first endogenous phospholipase A inhibitor from a non-venomous tropical snake, (Serpentes: Boidae).

Background: Endogenous phospholipase A inhibitors from snake blood (sbPLIs) have been isolated from several species around the world, with the primary function of self-protection against the action of toxic phospholipases A In American snakes, sbPLIs were solely described in pit vipers, in which the natural protection role is justified. In this study, we described a sbPLI in (popularly known as ), a non-venomous snake species from America.

Methods: PLA inhibitory activity was tested in the blood plasma of using venom as the enzyme source.

Crotalus neutralising factor and its role in human leukocyte modulation.

Crotalus neutralising factor (CNF) is an endogenous γ-type phospholipase A (PLA) inhibitor that inhibits the toxic action of crotoxin, a neurotoxin present in Crotalus durissus terrificus venom. However, its effects on the activation and modulation of immune cells, which play a major role in the development of inflammation, is not known. The objective of the present study was to assess the effects of CNF on human leukocyte modulation in vitro by analysing the following parameters: cell viability, phagocytic capacity, lipid droplet formation, reactive oxygen species production, nitric oxide production, p38 MAPK activation, and cytosolic PLA (cPLA) gene expression.

Dogs with divergent serology for visceral leishmaniasis as sources of Leishmania infection for Lutzomyia longipalpis phlebotomine sand flies - an observational study in an endemic area in Brazil.

Visceral leishmaniasis (VL) is a neglected tropical disease, caused by Leishmania (Kinetoplastida, Trypanosomatidae) species. In Brazil, the transmission of this parasite essentially occurs through the bite of Lutzomyia longipalpis (Diptera: Psychodidae: Phlebotominae) previously infected with Leishmania infantum. Aiming at preventing VL expansion over the country, integrated control actions have been implemented through a Visceral Leishmaniasis Surveillance and Control Program (VLSCP).

Snake Venom and a Phospholipase A Isolated from This Venom Elicit Macrophages to Form Lipid Droplets and Synthesize Inflammatory Lipid Mediators.

Viper snake (Cdr) is a subspecies found in northern area of Brazil. Among the snakes of genus subspecies, the venom of Cdr presents highest level of crotoxin, which is the major component of snake venoms, formed by two subunits (crotapotin and a phospholipase A named CBr) and presents potent neurotoxic activity. Curiously, the venom of (CdrV) is better neutralized by antibothropic than by anticrotalic serum, strongly suggesting that this venom has similarities with venom of genus snakes with regard to the ability to induce inflammation.

Immunodetection of toxins in historesin-embedded sections of Phoneutria nigriventer venom glands using laser confocal scanning microscopy.

In the last decades, main advances were achieved in the identification, structural and pharmacological characterization of Phoneutria nigriventer toxins. However, studies on the venom-producing apparatus are rare. Presently, we applied immunolabeling to historesin-embedded cross-sections of P.

Entomological Studies in Itaúna, Brazil, an Area With Visceral Leishmaniasis Transmission: Fauna Survey, Natural Leishmania Infection, and Molecular Characterization of the Species Circulating in Phlebotomine Sand Flies (Diptera: Psychodidae).

Among neglected tropical diseases, visceral leishmaniasis (VL) shows great relevance in global terms and is a serious public health concern due to the possibility of severe and lethal forms in humans. In this study, we evaluate entomological factors such as diversity and abundance of phlebotomine sand flies (Diptera:Psychodidae) and the Leishmania species circulating in these species in possible association with VL transmission in the Brazilian town Itaúna. The entomological collections were performed during three consecutive nights, always in the third week of each month, within a period of 12 mo.

Identification, description and structural analysis of beta phospholipase A inhibitors (sbβPLIs) from Latin American pit vipers indicate a binding site region for basic snake venom phospholipases A.

Several snake species possess, in their circulating blood, endogenous PLA inhibitors (sbPLIs) with the primary function of natural protection against toxic enzymes from homologous and heterologous venoms. Among the three structural classes of sbPLIs - named α, β, and γ - the β class (sbβPLIs) is the least known with only four identified sequences, so far. The last class of inhibitors encompass molecules with leucine rich repeats (LRRs) motifs containing repeating amino acid segments.