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International Journal of Molecular... Jun 2024Eastern Diamondback Rattlesnake () envenomation is a medical emergency encountered in the Southeastern United States. The venom contains a snake venom thrombin-like...
Eastern Diamondback Rattlesnake () envenomation is a medical emergency encountered in the Southeastern United States. The venom contains a snake venom thrombin-like enzyme (SVTLE) that is defibrinogenating, causing coagulopathy without effects on platelets in humans. This investigation utilized thrombelastographic methods to document this coagulopathy kinetically on the molecular level in a rabbit model of envenomation via the analyses of whole blood samples without and with platelet inhibition. Subsequently, the administration of a novel ruthenium compound containing site-directed antivenom abrogated the coagulopathic effects of envenomation in whole blood without platelet inhibition and significantly diminished loss of coagulation in platelet-inhibited samples. This investigation provides coagulation kinetic insights into the molecular interactions and results of SVTLE on fibrinogen-dependent coagulation and confirmation of the efficacy of a ruthenium antivenom. These results serve as a rationale to investigate the coagulopathic effects of other venoms with this model and assess the efficacy of this site-directed antivenom.
Topics: Animals; Rabbits; Antivenins; Crotalus; Crotalid Venoms; Blood Coagulation; Thrombelastography; Ruthenium; Snake Bites; Male; Venomous Snakes
PubMed: 38928044
DOI: 10.3390/ijms25126334 -
Biology Jun 2024Global climate change drives variations in species distribution patterns and affects biodiversity, potentially increasing the risk of species extinction. Investigating...
Global climate change drives variations in species distribution patterns and affects biodiversity, potentially increasing the risk of species extinction. Investigating the potential distribution range of species under future global climate change is crucial for biodiversity conservation and ecosystem management. In this study, we collected distributional data for 5282 reptile species to assess their conservation status based on distributional ranges using species distribution models. Our predictions indicate that the potential distribution ranges for over half of these species are projected to decrease under different scenarios. Under future scenarios with relatively low carbon emissions, the increase in the number of threatened reptiles is significantly lower, highlighting the importance of human efforts. Surprisingly, we identified some endangered species that are projected to expand their distribution ranges, underscoring the potential positive effects of climate change on some special species. Our findings emphasize the increased extinction risk faced by reptile species due to climate change and highlight the urgent need to mitigate the effects of habitat degradation and human activities on their potential distribution in the future.
PubMed: 38927316
DOI: 10.3390/biology13060436 -
Anais Da Academia Brasileira de Ciencias 2024The ecology of movement is an expanding area, marked by the diversity of analytical methods and protocols, which enables this integrative reading. We investigated...
Tracking the little ones: use of fluorescent powder to follow a leaf litter lizard (Coleodactylus meridionalis, Squamata: Sphaerodactylidae) in the Atlantic Forest of southern Bahia, Brazil.
The ecology of movement is an expanding area, marked by the diversity of analytical methods and protocols, which enables this integrative reading. We investigated movement ecology aspects of Coleodactylus meridionalis in southern Bahia, northeastern Brazil, using fluorescent powder with mineral oil to track individuals. We monitored 69 individuals of C. meridionalis that walked an average distance of 148 cm in 2h. We identified this movement as foraging due to the orientation of the step sequence and microenvironments used. We find no significant differences between walking distance and weight. However, we found a decrease in activity over the follow-up period. Most of the lizard's movements were directed north, while south, east, and west were followed equally. The individuals stayed predominantly on the ground (leaf litter), but it was possible to observe the use of other surfaces, such as trunks and burrows on the ground. Therefore, we studied the movement in three dimensions (ground height, distance traveled, and orientation of steps). We observed the lizard's foraging, one of the most common and least investigated movements in small lizards like C. meridionalis. This involves not only the species' activity schedule but other intrinsic and extrinsic factors that shape the movement decisions of individuals.
Topics: Animals; Lizards; Brazil; Forests; Powders; Male
PubMed: 38922256
DOI: 10.1590/0001-3765202420230728 -
Anais Da Academia Brasileira de Ciencias 2024The study aimed to characterize the digestive tract of Uranoscodon superciliosus and its associations to the diet and foraging behavior already described for the...
Morphological description of the digestive tract of the Amazonian Diving Lizard Uranoscodon superciliosus (Linnaeus, 1758) and its associations to the diet and foraging mode.
The study aimed to characterize the digestive tract of Uranoscodon superciliosus and its associations to the diet and foraging behavior already described for the species. Five lizards were captured in forest areas near the city of Manaus, Amazonas, Brazil. Tongue, oesophagus, stomach, small and large intestines fragments were collected, fixed, and processed for light microscopy. Hyaline cartilage was present in the center of the tongue, and the papillae from the apex and glands from the radix showed positive reaction to Alcian blue. The oesophagus presented a folded mucosa, covered by an epithelium with mucous and goblet cells positive to PAS and Alcian blue. There was presence of gastric glands in the cardic and fundic stomach regions, plus all the regions reacted positively to PAS. Fold and villi variations in both small and large intestine were noted, as well as the number and arrangement of goblet cells. Mucous and goblet cells from the small intestine were positively stained in PAS, while only the goblet cells were Alcian blue positive. These findings indicate that the Amazonian Diving Lizard's digestive tract organs, mainly the tongue and stomach, present morphologies associated to ambush-type foraging and a specific diet largely based on small invertebrates.
Topics: Animals; Lizards; Feeding Behavior; Gastrointestinal Tract; Brazil; Diet; Male
PubMed: 38922253
DOI: 10.1590/0001-3765202420220844 -
Brazilian Journal of Biology = Revista... 2024Hepatozoon spp. are the most common haemoparasites reported from reptiles around the world, however, only six species have been described infecting crocodilians. In...
Hepatozoon spp. are the most common haemoparasites reported from reptiles around the world, however, only six species have been described infecting crocodilians. In Brazil, Hepatozoon caimani Carini, 1909 is currently the only recognized species from the caiman hosts. This study provides new data on the diversity of species of Hepatozoon infecting Caiman crocodilus (Linnaeus) using molecular data and phylogenetic analysis, with additional support of morphological data of developmental stages from host blood and tissue. Forty-four individuals were collected and screened for haemogregarines, and blood and tissue samples were analysed by light microscopy with 31 (70.45%) infected. Hepatozoon spp. blood developmental stages included immature and mature gamonts with or without cytoplasmic vacuoles and free gamonts. Additionally, merogonic developmental stages were found in the liver and spleen of infected hosts. Based on the morphological and molecular data, this study identified two possible different species of Hepatozoon, being one of them the H. caimani with intragenotypic divergence.
Topics: Animals; Phylogeny; Brazil; Alligators and Crocodiles; Eucoccidiida; Coccidiosis; Coccidia
PubMed: 38922198
DOI: 10.1590/1519-6984.282989 -
Toxins Jun 2024Despite their evolutionary novelty, lizard venoms are much less studied in comparison to the intense research on snake venoms. While the venoms of helodermatid lizards...
Despite their evolutionary novelty, lizard venoms are much less studied in comparison to the intense research on snake venoms. While the venoms of helodermatid lizards have long been assumed to be for defensive purposes, there is increasing evidence of toxic activities more useful for predation than defence (such as paralytic neurotoxicity). This study aimed to ascertain the effects of , , and lizard venoms on the coagulation and cardiovascular systems. Anticoagulant toxicity was demonstrated for the species studied, with the venoms prolonging clotting times in human and bird plasma due to the destructive cleavage of fibrinogen. In contrast, thromboelastographic analyses on human and bird plasmas in this study demonstrated a procoagulant bioactivity for venoms. A previous study on venom using factor-depleted plasmas as a proxy model suggested a procoagulant factor was present that activated either Factor XI or Factor XII, but could not ascertain the precise target. Our activation studies using purified zymogens confirmed FXII activation. Comparisons of neonate and adult , revealed the neonates to be more potent in the ability to activate FXII, being more similar to the venom of the smaller species than the adult This suggests potent FXII activation a basal trait in the genus, present in the small bodied last common ancestor. This also indicates an ontogenetic difference in prey preferences in the larger species paralleing the change in venom biochemistry. In addition, as birds lack Factor XII, the ability to clot avian plasma suggested an additional procoagulant site of action, which was revealed to be the activation of Factor VII, with being the most potent. This study also examined the effects upon the cardiovascular system, including the liberation of kinins from kininogen, which contributes to hypotension induction. This form of toxicity was previously described for venoms, and was revealed in this study was to also be a pathophysiological effect of and venoms. This suggests that this toxic activity was present in the venom of the last common ancestor of the anguimorph lizards, which is consistent with kallikrein enzymes being a shared toxin trait. This study therefore uncovered novel actions of anguimorph lizard venoms, not only contributing to the evolutionary biology body of knowledge but also revealing novel activities to mine for drug design lead compounds.
Topics: Animals; Lizards; Blood Coagulation; Humans; Anticoagulants; Birds; Venoms; Cardiotoxins; Thrombelastography; Cardiotoxicity
PubMed: 38922177
DOI: 10.3390/toxins16060283 -
Toxins Jun 2024Snakebite envenoming is a neglected tropical disease that causes >100,000 deaths and >400,000 cases of morbidity annually. Despite the use of mouse models, severe local...
Snakebite envenoming is a neglected tropical disease that causes >100,000 deaths and >400,000 cases of morbidity annually. Despite the use of mouse models, severe local envenoming, defined by morbidity-causing local tissue necrosis, remains poorly understood, and human-tissue responses are ill-defined. Here, for the first time, an ex vivo, non-perfused human skin model was used to investigate temporal histopathological and immunological changes following subcutaneous injections of venoms from medically important African vipers ( and ) and cobras ( and ). Histological analysis of venom-injected ex vivo human skin biopsies revealed morphological changes in the epidermis (ballooning degeneration, erosion, and ulceration) comparable to clinical signs of local envenoming. Immunostaining of these biopsies confirmed cell apoptosis consistent with the onset of necrosis. RNA sequencing, multiplex bead arrays, and ELISAs demonstrated that venom-injected human skin biopsies exhibited higher rates of transcription and expression of chemokines (CXCL5, MIP1-ALPHA, RANTES, MCP-1, and MIG), cytokines (IL-1β, IL-1RA, G-CSF/CSF-3, and GM-CSF), and growth factors (VEGF-A, FGF, and HGF) in comparison to non-injected biopsies. To investigate the efficacy of antivenom, SAIMR Echis monovalent or SAIMR polyvalent antivenom was injected one hour following or venom treatment, respectively, and although antivenom did not prevent venom-induced dermal tissue damage, it did reduce all pro-inflammatory chemokines, cytokines, and growth factors to normal levels after 48 h. This ex vivo skin model could be useful for studies evaluating the progression of local envenoming and the efficacy of snakebite treatments.
Topics: Humans; Skin; Necrosis; Animals; Cytokines; Snake Bites; Elapid Venoms; Viper Venoms; Inflammation; Viperidae; Chemokines
PubMed: 38922170
DOI: 10.3390/toxins16060276 -
Toxins May 2024The genus encompasses most species of medically significant venomous snakes of Europe, with Italy harbouring four of them. Envenomation by European vipers can result in... (Review)
Review
The genus encompasses most species of medically significant venomous snakes of Europe, with Italy harbouring four of them. Envenomation by European vipers can result in severe consequences, but underreporting and the absence of standardised clinical protocols hinder effective snakebite management. This study provides an updated, detailed set of guidelines for the management and treatment of snakebite tailored for Italian clinicians. It includes taxonomic keys for snake identification, insights into viper venom composition, and recommendations for clinical management. Emphasis is placed on quick and reliable identification of medically relevant snake species, along with appropriate first aid measures. Criteria for antivenom administration are outlined, as well as indications on managing potential side effects. While the protocol is specific to Italy, its methodology can potentially be adapted for other European countries, depending on local resources. The promotion of comprehensive data collection and collaboration among Poison Control Centres is advocated to optimise envenomation management protocols and improve the reporting of epidemiological data concerning snakebite at the country level.
Topics: Snake Bites; Italy; Viperidae; Animals; Antivenins; Humans; Viper Venoms; Vipera
PubMed: 38922149
DOI: 10.3390/toxins16060255 -
Toxins May 2024This retrospective, observational study describes the clinical findings, case management trends, and outcomes of 83 dogs and nine cats exposed to eastern coral snakes in...
Retrospective Evaluation of Clinical and Clinicopathologic Findings, Case Management, and Outcome for Dogs and Cats Exposed to (Eastern Coral Snake): 92 Cases (2021-2022).
This retrospective, observational study describes the clinical findings, case management trends, and outcomes of 83 dogs and nine cats exposed to eastern coral snakes in a university teaching hospital setting. The medical records of dogs and cats that received antivenom following coral snake exposure were reviewed. Data collected included signalment, time to antivenom administration, physical and laboratory characteristics at presentation, clinical course during hospitalization, length of hospitalization, and survival to discharge. The mean time from presentation to coral snake antivenom administration was 2.26 ± 1.46 h. Excluding cases where the owner declined in-hospital care, the mean hospitalization time for dogs and cats was 50.8 h and 34 h, respectively. The mean number of antivenom vials was 1.29 (1-4). Gastrointestinal signs (vomiting and ptyalism) occurred in 42.2% (35/83) of dogs and 33.3% (3/9) of cats. Peripheral neurologic system deficits (ataxia, paresis to plegia, absent reflexes, and hypoventilation) were noted in 19.6% (18/92) of dogs and cats. Hemolysis was also common in 37.9% (25/66) of dogs but was not observed in cats. Mechanical ventilation (MV) was indicated in 12% (10/83) of dogs but no cats. Acute kidney injury (AKI), while rare, was a common cause of euthanasia at 20% (2/5) and was the most common complication during MV at 44.4% (4/9). Pigmenturia/hemolysis occurred in 88.9% (8/9) of MV cases and in all cases with AKI. Despite delays in antivenom administration by several hours, dogs and cats with coral snake exposure have low mortality rates (6% of dogs (5/83) and 0% of cats). Gastrointestinal signs were common but were not predictive of progression to neurological signs. Thus, differentiating between coral snake exposure and envenomation before the onset of neurological signs remains challenging.
Topics: Animals; Dogs; Antivenins; Retrospective Studies; Cats; Coral Snakes; Snake Bites; Cat Diseases; Elapid Venoms; Male; Female; Dog Diseases; Treatment Outcome; Venomous Snakes
PubMed: 38922141
DOI: 10.3390/toxins16060246 -
Cells Jun 2024Envenomation by the in the Western Ghats of India (particularly in the Malabar region of Kerala) and the subcontinent island nation of Sri Lanka is known to inflict...
Envenomation by the in the Western Ghats of India (particularly in the Malabar region of Kerala) and the subcontinent island nation of Sri Lanka is known to inflict devastating mortality and morbidity. Currently, bites in India are devoid of anti-venom regimens. A detailed characterization of the venom is essential to stress the need for therapeutic anti-venom. Notably, the deleterious effects of this venom on human blood cells have largely remained less explored. Therefore, in continuation of our previous study, in the present study, we envisioned investigating the effect of venom on the morphological and physiological properties of red blood cells (RBCs). The venom readily induced deleterious morphological changes and, finally, the aggregation of washed RBCs. The aggregation process was independent of the ROS and the intracellular Ca ion concentration. Confocal and scanning electron microscopy (SEM) images revealed the loss of biconcave morphology and massive cytoskeletal disarray. Crenation or serrated plasma membrane projections were evenly distributed on the surface of the RBCs. The venom did not cause the formation of methemoglobin in washed RBCs but was significantly induced in whole blood. Venom did not affect glucose uptake and Na/K -ATPase activity but inhibited glucose 6 phosphate dehydrogenase activity and decreased the fluidity of the plasma membrane. Venom-induced RBC aggregates exhibited pro-coagulant activity but without affecting platelet aggregation. In pre-incubation or co-treatment studies, none of the bioactive compounds, such as melatonin, curcumin, fisetin, berberine, and quercetin, sugars such as mannose and galactose, and therapeutic polyvalent anti-venoms (Bharat and VINS) were inhibited, whereas only N-acetylcysteine and monovalent anti-venom could inhibit venom-induced deleterious morphological changes and aggregation of RBCs. In post-treatment studies, paradoxically, none of the bioactives and anti-venoms, including N-acetylcysteine and monovalent anti-venom, reversed the venom-induced RBC aggregates.
Topics: Animals; Humans; Erythrocytes; Acetylcysteine; Crotalid Venoms; Erythrocyte Aggregation; Antivenins; Calcium; Crotalinae; Reactive Oxygen Species
PubMed: 38920625
DOI: 10.3390/cells13120994