Histopathological changes of mice tissues in course of the envenomation by the Macrovipera lebetina obtusa venom and the neutralizing effect of the ovine-derived experimental antivenom.

Viper bites pose a significant public health issue in Armenia, even within urban areas, often resulting in clotting disorders, hypofibrinogenemia, and tissue necrosis in humans. This study investigates histopathological changes in various tissues during mice envenomation by West-Asian blunt-nosed viper (Macrovipera lebetina obtusa) venom, as well as the recovery process aided by experimental antivenom derived from sheep. The high venom dose caused substantial damage to the heart, lungs, liver, and kidneys in mice, indicating systemic harm. While antivenom administration can prevent mortality in mice envenomation, it may not fully mitigate histological damage in affected organs. Additionally, the study highlights the importance of timing antivenom administration, as the severity of tissue alterations can vary depending on the duration of envenomation. These findings shed light on antivenom's effects on viper envenomation and stress the need for further research to optimize its timing and dosage for minimizing histological damage and enhancing clinical outcomes.

A molecular dynamics study of protein denaturation induced by sulfonate-based surfactants.

Microsecond timescale explicit-solvent atomistic simulations were carried out to investigate how anionic surfactants modulate protein structure and dynamics. We found that lysozyme undergoes near-complete denaturation at the high concentration (> 0.1 M) of sodium pentadecyl sulfonate (SPDS), while only partial denaturation occurs at the concentration slightly below 0.1 M. In large part, protein denaturation is structurally manifested by disappearance of helical segments and loss of tertiary interactions. The computational prediction of the extent of burial of cysteine residues was experimentally validated by measuring the accessibility of the respective sulfhydryl groups. Overall, our work indicates an interesting synergy between electrostatic and hydrophobic contributions to lysozyme's denaturation process by anionic surfactants. In fact, first disulfide bridges and hydrogen bonds from protein surface to SPDS head groups loosen the protein globule followed by fuller denaturation via insertion of the surfactant's hydrophobic tails into the protein core.

The development and evaluation of the efficacy of ovine-derived experimental antivenom immunoserum against Macrovipera lebetina obtusa (MLO) venom.

Here we describe the processing and development of animal-derived monovalent antibody serum against Macrovipera lebetina obtusa venom by purification and concentration of the immunoglobulins using caprylic acid. We demonstrate that this new viper venom antiserum is pre-clinically effective in neutralizing lethal toxicity and hemorrhagicity of the venom of the Armenian Levantine viper - a significant public health problem in Armenia and a wide region from south-east parts of Europe to south-west Asia. The developed product shows a high capacity to inhibit metalloproteinases and phospholipase activity of venom included in the study in comparison to current specific antivenoms, and following additional experimental approvals, it will be possible to derive the monovalent antivenom satisfying international standards, which will be much cheaper and accessible compared with the current market rivals.

Neurobiology and therapeutic utility of neurotoxins targeting postsynaptic mechanisms of neuromuscular transmission.

The neuromuscular junction (NMJ) is the principal site for the translation of motor neurochemical signals to muscle activity. Therefore, the release and sensing machinery of acetylcholine (ACh) along with muscle contraction are two of the main targets of natural toxins and pathogens, causing paralysis. Given pharmacology and medical advances, the active ingredients of toxins that target postsynaptic mechanisms have become of major interest, showing promise as drug leads. Herein, we review key facets of prevalent toxins modulating the mechanisms of ACh sensing and generation of the postsynaptic response, with muscle contraction. We consider the correlation between their outstanding selectivity and potency plus effects on motor function, and discuss emerging data advocating their usage for the development of therapies alleviating neuromuscular dysfunction.

Neurobiology and therapeutic applications of neurotoxins targeting transmitter release.

Synaptic transmission is a fundamental neurobiological process enabling exchange of signals between neurons as well as neurons and their non-neuronal effectors. The complex molecular machinery of the synaptic vesicle cycle and transmitter release has emerged and developed in the course of the evolutionary race, to ensure adaptive gain and survival of the fittest. In parallel, a generous arsenal of biomolecules and neuroactive peptides have co-evolved, which selectively target the transmitter release machinery, with the aim of subduing natural rivals or neutralizing prey. With advances in neuropharmacology and quantitative biology, neurotoxins targeting presynaptic mechanisms have attracted major interest, revealing considerable potential as carriers of molecular cargo and probes for meddling synaptic transmission mechanisms for research and medical benefit. In this review, we investigate and discuss key facets employed by the most prominent bacterial and animal toxins targeting the presynaptic secretory machinery. We explore the cellular basis and molecular grounds for their tremendous potency and selectivity, with effects on a wide range of neural functions. Finally, we consider the emerging preclinical and clinical data advocating the use of active ingredients of neurotoxins for the advancement of molecular medicine and development of restorative therapies.

Anti-tumor effect investigation of obtustatin and crude Macrovipera lebetina obtusa venom in S-180 sarcoma bearing mice.

Over the last few decades, research on snake venom toxins has provided not only new tools to decipher molecular details of various physiological processes, but also inspiration to design and develop a number of therapeutic agents. Isolated from the venom of Macrovipera lebetina obutusa (MLO), obtustatin represents the shortest known snake venom monomeric disintegrin specific inhibitor of α1ß1 integrin. This low molecular weight peptide revealed a potent therapeutic effect on melanoma progression. Its oncostatic effect was related to the inhibition of angiogenesis. The aim of the proposed investigation was to study the influence of obtustatin and crude MLO venom on the S-180 sarcoma growth in vitro and in vivo. A S-180 sarcoma bearing mouse model, histological examination, DNA retardation assay were utilized to investigate the anti-tumor effects of MLO and obtustatin. In addition, some biochemical tests (chemiluminescence-ChL, TBA-test) were applied to elucidate the influence of obtustatin and crude MLO venom on the S-180 sarcoma. The size of tumor was significantly inhibited by MLO venom and obtustatin with the inhibitory rate of 50% and 33% at the doses of 10 µg/mouse and 1mg/kg/day respectively. Both ChL and MDA decrease in the two treated groups. Both obtustatin and MLO venom have an anticancer activity and might be candidates for the treatment of malignant sarcoma. All our results have shown that both obtustatin and MLO venom have an anticancer activity and might be candidates for the treatment of malignant sarcoma.

Phospholipases a2 from Viperidae snakes: Differences in membranotropic activity between enzymatically active toxin and its inactive isoforms.

We describe the interaction of various phospholipases A2 (PLA2) from snake venoms of the family Viperidae (Macrovipera lebetina obtusa, Vipera ursinii renardi, Bothrops asper) with giant unilamellar vesicles (GUVs) composed of natural brain phospholipids mixture, visualized through fluorescence microscopy. The membrane fluorescent probes 8-anilino-1-naphthalenesulfonicacid (ANS), LAUDRAN and PRODAN were used to assess the state of the membrane and specifically mark the lipid packing and membrane fluidity. Our results have shown that the three PLA2s which contain either of aspartic acid, serine, or lysine residues at position 49 in the catalytic center, have different effects on the vesicles. The PLA2 with aspartic acid at this position causes the oval deformation of the vesicles, while serine and lysine-containing enzymes lead to an appreciable increase of fluorescence intensity in the vesicles membrane, wherein the shape and dimensions of GUVs have not changed, but in this case GUV aggregation occurs. LAURDAN and PRODAN detect the extent of water penetration into the bilayer surface. We calculated generalized polarization function (GP), showing that for all cases (D49 PLA2, S49 PLA2 and K49 PLA2) both LAUDRAN and PRODAN GP values decrease. A higher LAURDAN GP is indicative of low water penetration in the lipid bilayer in case of K49 PLA2 compared with D49 PLA2, whereas the PRODAN mainly gives information when lipid is in liquid crystalline phase.

Lipid bilayer condition abnormalities following Macrovipera lebetina obtusa snake envenomation.

Viper bites is an endemic public health problem in Armenia, even in the cities. Human envenomation is often characterized by clotting disorders, hypofibrinogenemia, and local tissue necrosis. In this original study, we assess some changes of cell membranes plastic properties (namely, its microviscosity, thickness, permeability) in a rat envenomation model using the biophysical approaches. We describe the interaction of Macrovipera lebetina obtusa (MLO) venom with giant unilamellar vesicles (GUVs) composed of the native phospholipid mixtures visualized through fluorescent microscopy. GUVs with a mean diameter of 30 µm have a minimum curvature and mimic cell membranes in this respect. The membrane fluorescence probe, ANS and pyrene, were used to assess the state of membrane and specifically mark the phospholipid domains. Independent of their lipid composition, GUVs were enlarged in size as venom-dependent lipid hydrolysis proceeded. Except of the visible morphological changes, ANS and pyrene also allows us to quantify the fluidity changes in the membrane by measuring of the fluorescence intensity. The presence of viper venom in GUVs media reveals a noticeable decreasing of membrane fluidity compare the control, while the binding of fluorophores with GUVs modified by venom lead to appearance of channel activity. These studies also emphasize the importance of a membrane surface curvature for its interaction with enzymatic components of venom.

Molecular events associated with Macrovipera lebetina obtusa and Montivipera raddei venom intoxication and condition of biomembranes.

Studies on the interaction of snake venom and organized lipid interfaces have been conducted using a variety of systems, including BLMs, SUVs and GUVs. The present study was undertaken to elucidate how the plastic properties (namely, its microviscosity, thickness, permeability) of model membranes from native lipids of different tissues of rats change in the course of Macrovipera lebetina obtusa (MLO), Montivipera raddei (MR) and Naja kaouthia (NK) venoms processing. The presence of viper venom in organism leads to increasing of the electrical resistance of BLMs from liver and muscle lipids approximately on a sequence, while the BLMs from brain lipids have not shown noticeable differences of plastic properties compared to the control. Giant unilamellar vesicles (GUVs) with a mean diameter of 30µm have a minimum curvature and mimic cell membranes in this respect. Snake venom was added to the sample chamber before the vesicles were formed. The membrane fluorescence probes, ANS and pyrene, were used to assess the state of the membrane and specifically mark the phospholipid domains. Fluorescent spectra were acquired on a Varian fluorometer instrument. ANS and pyrene allow us to quantify the fluidity changes in the membrane by measuring of the fluorescence intensity. The presence of viper venom in GUVs media reveals a noticeable decreasing of membrane fluidity compared to the control, while the binding of fluorophores with GUVs modified by venom leads to the appearance of channel activity. These studies also emphasize the importance of a membrane surface curvature for its interaction with enzymatic components of venom.