Abstract in English:Hymenoptera venoms are complex mixtures containing simple organic molecules, proteins, peptides, and other bioactive elements. Several of these components have been isolated and characterized, and their primary structures determined by biochemical techniques. These compounds are responsible for many toxic or allergic reactions in different organisms, such as local pain, inflammation, itching, irritation, and moderate or severe allergic reactions. The most extensively characterized Hymenoptera venoms are bee venoms, mainly from the Apis genus and also from social wasps and ant species. However, there is little information about other Hymenoptera groups. The Apis venom presents high molecular weight molecules - enzymes with a molecular weight higher than 10.0 kDa - and peptides. The best studied enzymes are phospholipase A2, responsible for cleaving the membrane phospholipids, hyaluronidase, which degrades the matrix component hyaluronic acid into non-viscous segments and acid phosphatase acting on organic phosphates. The main peptide compounds of bee venom are lytic peptide melittin, apamin (neurotoxic), and mastocyte degranulating peptide (MCD).
Abstract in English:Host nutritional state has an important role in susceptibility to bacteria, parasites, and viral infections. Infection precipitates the appearance of signs and symptoms of nutrition deficiencies in the undernourished; this can aggravate infection evolution. Infection stimulates specific and non-specific host defense mechanisms; these are directly influenced by the nutritional state of micro- and macronutrients. Immune alterations, which are closely related to nutritional status, markedly contribute to a higher susceptibility to infectious agents and can also contribute to worsening nutritional state, forming a vicious cycle.
Abstract in English:This study was undertaken to develop an experimental protocol using insects as biological models to assay venom toxicity of the following spiders Loxosceles gaucho, Phoneutria nigriventer, Nephilengys cruentata and Tityus serrulatus scorpion. Three different insect species were bioassayed: Apis mellifera (Hymenoptera), Grillus assimilis (Orthoptera), and Diatraea saccharalis (Lepidoptera). Venoms were injected into the hemocele of insects with a microsyringe at concentrations that caused dose/weight-dependent effects; doses causing either paralysis (ED50) or death (LD50) were recorded for each venom and insect test-species. T. serrulatus and L. gaucho venoms were lethal to all tested species, while P. nigriventer venom caused paralysis and death, and N. cruentata venom caused only paralysis at the doses assayed. A comparison between the insect test species described above revealed that A. mellifera was highly sensitive to all venoms tested; even a tiny amount of N. cruentata non-lethal venom caused a change in the walking pattern leading to transient paralysis. D. saccharalis larvae were very resistant to all four venoms.
Abstract in English:An in vitro and in vivo comparative study was performed on the effects of Crotalus durissus terrificus venoms from a mother and its 15 newborns. The venoms were tested for protein content, lethality, proteolytic, myotoxic, hemorrhagic, and phospholipase A2 activity. The minimum coagulant dose in plasma and human fibrinogen, protrhombin, and Factor II activations were analyzed. The venoms were also analyzed by polyacrylamide gel electrophoresis (PAGE). This showed that despite similar total protein content, the biological effects of the venoms were different. Venom from young snakes exhibited higher enzymatic and coagulant activities and higher myotoxicity compared to the mother’s. In addition, the PLA2 content paralleled myotoxicity. However, no difference could be detected in their toxicity (LD50 0.08 mg/Kg). High incidence of blood coagulation disorders and elevated circulating myoglobin may characterize systemic envenoming by young C. d. terrificus.
Abstract in English:Acute myocardiopathy in alloxan treated experimental dogs and rabbits was induced by subcutaneous (SQ) injection of scorpion venom from Mesobuthus tamulus concanesis, Pocock. Envenoming resulted in an initial transient hypertension (180-320 mm Hg.) followed by hypotension. Simultaneous administration of venom and species-specific scorpion antivenom (SAV) prevented hypertension and hypotension. Hypotension did not occur when SAV was given 60 min after envenoming. Blood glucose, triglycerides, cholesterol, amylase, insulin, glucagon, cortisol, hematocrit, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), platelet count, red blood cell (RBC) count, hemoglobin (Hb), 2,3-diphosphoglycerate (2,3-DPG), and glutathione levels were increased 60 and 90 min after envenoming. Total white blood cell (WBC) count was reduced 60 min and increased 90 min after envenoming. Simultaneous administration of venom and SAV did not alter Hb, MCHC, and packed cell volume (PCV) levels, or ECG, and cardiovascular, biochemical, metabolic, and hormonal changes. Hematological parameters were reversed when SAV was given 30 and 60 min after envenoming. PCV, Hb, and MCHC values returned to normal 120 min after SAV. Alloxan-treated dogs showed increased blood glucose, cholesterol, glucagon, cortisol levels; reduced glycogen content of liver, cardiac and skeletal muscles; and reduced insulin levels and insulin/ glucagon ratio (I/G ratio). Envenoming in the alloxan pre-treated dogs further increased these levels and reduced tissue glycogen content, insulin levels, and I/G ratio. Administration of 4 U of insulin to alloxan pre-treated envenomed rabbits caused a biochemical and clinical improvement and increased glycogen content of all tissues in comparison with the values from those administered with SAV to alloxan pre-treated envenomed animals. SAV administration to envenomed alloxan pre-treated rabbits did not cause clinical or biochemical improvement. Severe scorpion envenoming causes an autonomic storm with a massive release of catecholamines and other counter-regulatory hormones; changes in insulin secretion resulting in fuel energy deficits producing multi-system-organ-failure (MSOF); and death. Administration of either insulin or SAV (through the release of insulin) appears to be the physiological basis for the control of the metabolic support to control the adverse effects triggered by counter-regulatory hormones.
Abstract in English:Adenosine deaminase (ADA), histamine, and IgE are endogenously present in animals. Research from this laboratory reported decreased levels of these substances in organs of mice as a consequence of sub-lethal injection of Naja kaouthia venom. This research reports that decreased ADA, histamine, and IgE levels were prevented by specific treatment and prolonged recovery periods. Adult Balb/c mice injected IM with sub-lethal venom dose were divided into five groups. Group 1 were injected with PBS; Group 2 with anti-cobra venom; and Group 3 with lethal toxin neutralizing factor (LTNF). Groups 4 and 5 were treated with IM or oral synthetic LT-10. After 24 hours, mice were sacrificed and organ homogenates were assayed for ADA, histamine, and IgE. Group 1 showed substantial reduction in levels of these substances. It was revealed that decreased levels were prevented by treatment with anti-cobra venom, LTNF, and LT-10. In a second series of experiments, venom-injected mice were sacrificed after 3, 7, and 10 days and organs assayed for ADA, histamine, and IgE levels. The recovery period to homeostasis for ADA, histamine, and IgE was 7 to 10 days.
Abstract in English:Scorpion venom toxicity is of major concern due to its influence on human activities and public health. The cytotoxicity and apoptosis induced by scorpion L. quinquestriatus venom on two established eukaryotic cell lines (293T and C2C12) were analyzed. Both cultured cell lines were incubated with varying doses (10, 20, and 50 µg/ml) of scorpion venom in serum free medium (SFM) for 0.5, 1, 2, 4, and 8 hours at 37°C. The percentage of total lactate dehydrogenase (LDH) released in the culture during venom incubation was used as an index of cell damage. Control culture was treated with an equal amount of SFM. Cell injury was recognized morphologically and apoptosis was researched by a Fluorescing Apoptosis Detection System using the principle of TUNEL (TdT-mediated dUTP Nick-End Labelling) assay and confirmed by another assay concerning nuclear DNA staining with DAPI stain. Cytotoxicity was remarkable and cell survival highly reduced at the highest tested concentration (50 µg/ml). These effects were rapid and observed within 30 minutes. The apparent initial damage to the nucleus and lysis of the plasmalemma and/or organelle membranes, which was evident by a significant increase in cytosolic LDH release, suggested that this toxin acts at the membrane level. The morphological changes that occurred in apoptotic cells include condensation and compartmentalization of nuclear and cytoplasmic materials into structurally preserved membrane-bound fragments or blebs. The cytotoxic effects are dose and time dependent and cell death by apoptosis was more characteristic of 293T cells than C2C12 cells. The apoptotic effects were more prominent and clear in the early stages of toxicity, while other forms of cell damage such as swelling, rupture, and/or necrosis occurred at later stages.
Abstract in English:Eighty-nine of 144 isolates of Clostridium perfringens obtained from 187 samples of 71 bovine in several Brazilian states were submitted to esterase electrophoresis for typing. Mobilites electrophoresis, as parameter, were settled down by isolates from ATCC pattern of types A, B, C, and D. Of the 89 isolates, 43 (48.3%) were characterized as electrophoretic type A, 20 (22.5%) as D, 18 (20.2%) as C, and 3 (3.4%) as B. Five (5.6%) isolates did not identity with any type. Similarly, esterase electrophoresis enabled the typing of 94.4 % of the isolates, demonstrating to be an appropriate method for animal sample analyses.