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ABSTRACT Background: Spider venoms are rich natural sources of bioactive chemicals ranging from low-molecular-mass compounds to larger molecules such as low molecular mass peptides, proteins, and enzymes. Some compounds have been reported to exhibit neuroactivity and show potential as therapeutic agents against neurological disorders. Thus, this study analyzed the neurobehavioral effects of selected venom fractions from Philippine tarantula species compared to FDA-approved drugs targeting neuroreceptors, ion channels, and enzymes. Methods: The venom was collected from the tarantula by electrostimulation and fractionated by reverse-phase high-performance liquid chromatography (RP-HPLC). Nine of the eleven fractions were subjected to neurobehavioral analysis using zebrafish (Danio rerio) as the animal model. The fractions were administered intraperitoneally, and their neurobehavioral effects were examined using the novel tank test, fear response, social interaction, and mirror biting tests. Donepezil, lidocaine, and diazepam were used as positive controls, and normal saline solution (NSS) as the negative control of the study. The swimming patterns and trajectories of the zebrafish were monitored using idTracker and were graphed using GraphPad Prism v.9.0. Components of the most polar fraction were further analyzed by Ultra Performance Liquid Chromatography - Quadrupole Time of Flight Data Dependent Analysis to identify the components structurally. Results: Preliminary screening of all the fractions revealed that Fraction 1 with 0.1 µg/µL exhibited donepezil-like behavior based on similar rapid-swimming movement from 0 to 31 time intervals, Fraction 4 with 0.1 µg/µL concentration exhibited diazepam-like behavior due to non-significant differences in its time spent on top of the tank ranging from20 to 40 minutes, and Fraction 8 with 0.1 µg/µL concentration exhibited lidocaine-like behavior based on both rapid swimming movement and time spent on top of the tank. Fractions 1, 4, and 8 were further evaluated by determining their dose-dependent response, which follows the effect of their corresponding positive control. Analysis of Fraction 1 resulted in the annotation of several non-peptidic components 4-OH-PhLac434 and its isomer using VenoMS and isopimaric acid, palmitamide, 9-octadecenamide, and 13-docosenamide as putative compounds present in this spider venom using GNPS. Conclusion: Overall, the fractions of venom from the Orphnaecus tarantula species appear to induce distinct neurobehavioral effects, which may include hyperactivity, anxiolytic-like responses, and potential antinociceptive properties.

Resumo em Inglês:

Abstract Background: Bothrops snakebite is common in the Amazon region and can lead to severe complications in the affected limb, including secondary bacterial infections, blisters, necrosis, and acute compartment syndrome (ACS) in extreme cases. Many of these patients reside in remote areas with limited resources, where early recognition of clinical indicators is decisive for the timely identification of ACS and subsequent decision-making by healthcare professionals. The aim of this study was to identify risk factors associated with ACS following Bothrops atrox envenomation in the Brazilian Amazon. Methods: A case-control study was conducted in three health units of Manaus, Western Brazilian Amazon. The allocation ratio was 1:3, with cases defined as B. atrox-envenomed patients developing ACS, and a control group consisting of patients who did not develop ACS. Results: A total of 37 ACS cases and 111 controls were included in the study. Living in rural areas [OR = 4.59 (95%CI = 1.51-20.0; p = 0.017)], bites in the lower limbs [OR = 7.6 (95%CI = 3.18-19.3; p < 0.001)], time to medical care of 7-12 hours [OR = 4.23 (95%CI = 1.63-11.1; p = 0.003)], blisters [OR = 3.24 (95%CI = 1.12-9.25; p = 0.027)], and secondary bacterial infection [OR = 15 (95%CI = 3.54-103; p < 0.001)] were associated with ACS. Mean values of creatine kinase were significantly higher in ACS patients on the first (p = 0.022) and second (p = 0.013) days of hospitalization. Conclusion: This study presents, for the first time, the factors associated with ACS from B. atrox envenomation, providing a basis for early diagnosis and treatment, and enabling prompt medical intervention. This may reduce adverse events, promote faster recovery, and lower the rate of disability.

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Abstract Background: Heterometrus laoticus and Lychas mucronatus are widely distributed in Southeast Asia, yet their pathophysiological effects of both venoms remain poorly characterized due to low human fatality rates. This study compared their venom compositions and acute cardiovascular and renal effects. Methods: Anesthetized male New Zealand White rabbits were monitored for blood pressure (BP), heart rate (HR), and renal clearance following intravenous administration of crude venom (0.5 mg/kg). Venom components were identified via LC-MS/MS, and hematological/biochemical parameters were assessed. Results: H. laoticus venom induced a rapid, transient hypotension (p < 0.05), followed by a mild, prolonged hypotensive phase (up to 120 min). Conversely, L. mucronatus venom elicited a biphasic response: initial transient hypotension followed by significant hypertension (p < 0.05) and a subsequent terminal hypotensive stage. Renal hemodynamic changes in both groups were secondary to these systemic cardiovascular fluctuations. Conclusions: LC-MS/MS revealed that the neurotoxin-rich profile (KTx and NaTx) of L. mucronatus drives vasoconstriction and hypertension. In contrast, the higher PLA₂ content in H. laoticus mediates cytotoxic-like effects, resulting in vasodilation and hypotension. These distinct molecular mechanisms suggest that clinical management should be species-specific, even for venoms traditionally considered “mild.”

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Abstract Background: Sporotrichosis is a fungal infection caused by species of the Sporothrix schenckii complex. Antifungal treatment with itraconazole and amphotericin B is limited by increasing resistance, adverse effects, and prolonged treatment courses, highlighting the need for novel antifungal strategies. Methods: The antifungal activity of seven antimicrobial peptides derived from arthropod toxins against Sporothrix species was evaluated: six synthetic peptides derived from the spider Lycosa erythrognatha toxin and one peptide isolated from apitoxin (melittin). Minimum inhibitory concentrations (MICs) and minimum fungicidal concentrations (MFCs) were determined. Mechanistic assays were performed to investigate membrane damage, oxidative stress induction, and interactions with ergosterol and the fungal cell wall. Synergistic activity with itraconazole was assessed, and the effect of melittin on selected virulence factors was studied. To explore potential therapeutic applications, a melittin-based formulation for local (intralesional) usage was developed, and its cytotoxicity was tested in HEK-293 and HepG2 cell lines, as well as its short-term safety in murine models. Results: All peptides inhibited S. schenckii and S. brasiliensis, with MIC and MFC values ranging from 0.5 to 32 µM. Melittin displayed the strongest antifungal effect, acting predominantly through a membranolytic mechanism associated with oxidative stress. Combined with itraconazole, melittin demonstrated synergistic activity against both species. Melittin selectively reduced pyomelanin production, while urease activity remained unaffected. The melittin-based formulation showed lower cytotoxicity compared to melittin alone, and subcutaneous administration in mice was well tolerated at the lowest dose tested (0.1 mg/kg). Conclusion: Melittin exhibits potent antifungal activity against Sporothrix spp. and synergism with itraconazole, supporting further investigation as an antifungal candidate. Although therapeutic efficacy was not evaluated in infected animal models, the development of a safer melittin-based formulation provides a proof-of-concept foundation for future studies focusing on the local treatment of cutaneous sporotrichosis.

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Abstract Background: Envenomation by Daboia siamensis venom (RVV) can cause acute kidney injury (AKI), but its mechanisms remain unclear. Renal cell death via necrosis and apoptosis is central to AKI progression. Bax and Bcl-2 are key pro- and anti-apoptotic regulators and common markers of apoptosis; however, their roles in RVV-induced renal injury are poorly defined. Therefore, we investigated Bax and Bcl-2 gene expression and their ratio in AKI following the administration of RVV and its venom fractions. Methods: Kidney tissue samples from intact rabbits (in vivo) and the isolated perfused kidney (IPK) model treated with RVV and its venom fractions (PLA₂, MP, LAAO, and PDE) were analyzed for Bcl-2 family expression at both mRNA and protein levels, together with histopathological evaluation. Bcl-2 and Bax mRNA expression was quantified by RT-qPCR using the ΔΔCt method, and protein expression was assessed by immunohistochemical analysis. Results: Following the administration of RVV and its venom fractions, histopathological analysis revealed extensive tubulonephrosis across all renal tubular segments in both intact kidneys and the IPK model. In contrast, renal tubular necrosis involving all tubular segments occurred in the IPK model after exposure to the RVV, PLA₂ and MP fractions. Immunohistochemical analysis revealed a trend toward increased Bax protein expression and decreased Bcl-2 expression in multiple tubular segments compared to controls in both models. RT-qPCR analysis demonstrated a 1.5-fold upregulation of Bcl-2 and significant reductions in Bax expression and the Bax/Bcl-2 ratio (p < 0.05) in the IPK model relative to controls. Conclusions: Envenomation with RVV and its venom fractions induced nephrotoxic acute kidney injury by modulating Bax- and Bcl-2-mediated apoptosis in renal tubular epithelial cells, with greater susceptibility observed in intact kidneys and a reduced apoptotic response in the IPK model. These findings suggest that prolonged venom exposure may be partially reversible or may shift cell-death signaling from apoptosis toward necrosis.

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Abstract Background: In the Brazilian Amazon, most snakebites are caused by Bothrops atrox. Although pediatric cases are less frequent, children are more vulnerable to severe complications and long-term disabilities. This study aims to describe the clinical profile of B. atrox envenomation in children treated at a tertiary hospital in Manaus, in Western Brazilian Amazon, and to characterize the resulting long-term musculoskeletal impairments in a subgroup of these patients. Methods: We retrospectively analyzed sociodemographic and clinical data from patients up to 12 years and 11 months of age treated between January 2010 and December 2023. A total of 258 children who were victims of B. atrox envenoming were eligible; however, a subgroup of 27 children underwent in-person musculoskeletal evaluations starting three months after hospital discharge. Results: In the subgroup of children evaluated, the majority were male (63%), were aged over ten years (59.3%), and were from rural areas (96.3%). Over half (51.8%) received medical care within six hours after the bite. The lower limbs were most frequently affected (96.3%). Common local symptoms included pain (100%), edema (96.3%), bleeding (37%), and bruising (29.6%). Secondary infections occurred in 18.5% of cases. Most envenomations were classified as moderate in severity (44.4%). In this subgroup, long-term disabilities were identified in 21 children (77.7%), who presented primarily with intermittent chronic pain (55.5%). Physical examination revealed scars (59.3%), edema (22.2%), and deformities (3.7%). Sensory alterations were noted in tactile (11.1%), pain (25.9%), thermal (22.2%), and vibratory (29.6%) sensitivity. Range of motion was impaired in 37% of cases, and one child exhibited abnormal posture and reflexes. Conclusions: This study highlights a broad spectrum of persistent musculoskeletal sequelae following Bothrops envenomation in children. Our findings underscore the urgent need for comprehensive care, follow-up, and rehabilitation programs for pediatric snakebite victims in the Amazon region.

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Abstract Background: Although bone tissue possesses inherent regenerative capacity, critical-sized defects require grafts for complete functional repair. This in vivo study evaluated the bone repair process using laser photobiomodulation therapy (PBM) in defects filled with a combination of hydroxyapatite, β-tricalcium phosphate and heterologous fibrin biopolymer (HFB). Methods: Thirty male rats were divided into three groups: biomaterial alone (BG), biomaterial + HFB (BBG), and biomaterial + HFB + PBM (BBPG). A 5-mm circular calvarial osteotomy was performed and filled according to each protocol. In BBPG, an 830-nm laser was applied immediately post-surgery and three times weekly until euthanasia at 14 or 42 days. Analyses included micro-CT, histomorphology, histomorphometry, and polarized light microscopy of collagen fibers. Results: Micro-CT showed centripetal bone regeneration restricted to defect margins, with biomaterial particles persisting centrally. Histologically, new bone progressed from immature trabecular architecture at day 14 to a mature lamellar conformation by day 42, notably in BBPG. All groups showed a significant temporal increase in new bone percentage. BBPG demonstrated superior bone growth at 42 days (26.64 ± 2.15%) compared to BG (14.85 ± 1.63%) and BBG (20.05 ± 1.70%). The birefringence of the collagen fibers showed a color transition from red to yellowish-green during the analyzed periods. Conclusion: The combination of the biomaterial, fibrin biopolymer and photobiomodulation significantly enhanced bone defect repair and matrix maturation without barrier membranes, presenting high translational potential for cost-effective clinical applications in regenerative medicine.

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Abstract Background: Central nervous system aspergillosis is a rare and severe condition with high mortality and frequent diagnostic delay. Infection due to Aspergillus penicillioides in this setting is rarely reported. Case presentation: We describe a rare case of cerebral infection caused by A. penicillioides in an immunocompetent patient, initially mistaken for a schwannoma. Histopathological examination revealed hyaline septate hyphae, and molecular analysis of formalin-fixed and paraffin-embedded (FFPE) tissue supported the identification by sequencing of a fragment of the 28S rRNA gene. Following an initial surgical resection, clinical deterioration ensued, necessitating a repeat procedure and targeted antifungal therapy, which ultimately led to disease stabilization and outpatient discharge. Conclusion: This case highlights the diagnostic difficulties and therapeutic challenges posed by rare Aspergillus species in immunocompetent hosts.

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Abstract Background: Scorpion stings are an increasing public health concern in Brazil, where children are at a heightened risk of severe outcomes. Simple biomarkers, such as admission blood glucose may improve early risk stratification. To assess the association between admission blood glucose and clinical severity in children envenomated by Tityus serrulatus. Methods: This prospective observational cohort study was conducted at João XXIII Hospital, Minas Gerais State Hospital Foundation (FHEMIG), Belo Horizonte, Brazil, from September 2023 to March 2024. We included patients aged 0 to 17 years with confirmed scorpion envenomation. Clinical severity was classified as mild (no antivenom) or moderate/severe (antivenom administered). Blood glucose was measured at admission and two hours thereafter. Predictive performance was assessed using receiver operating characteristic (ROC) analysis. Results: Sixty-seven children were included; 13.4% progressed to moderate/severe envenomation. Admission glucose ≥ 142 mg/dL showed 100% specificity and a 100% positive predictive value for severe cases (ROC AUC 0.979; 95% CI, 0.937-1.000; p < 0.001). A 105 mg/dL threshold maximized sensitivity (100%) at the expense of lower specificity (79.3%). To our knowledge, this is the first study to systematically evaluate admission glucose in pediatric T. serrulatus envenomation and to propose cutoffs for risk stratification. Conclusion: Admission blood glucose is an accessible and accurate biomarker for early triage of severity in pediatric scorpion envenomation. A 105 mg/dL threshold favors maximal sensitivity for screening, whereas 142 mg/dL ensures high specificity for severe cases. Although promising, these cutoffs should be treated as clinical hypotheses and require multicenter external validation before widespread adoption.

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Abstract We report that the implementation of a multidisciplinary team (MDT) protocol - integrating early ultrasound surveillance, prompt surgical intervention, targeted antimicrobial therapy, and optimized antivenom administration - was associated with a marked reduction the length of hospital stay and surgical burden among patients with Naja atra envenomation at a tertiary medical center in Taiwan. This approach shifts management from a reactive to a proactive strategy by enabling the early detection of tissue involvement and timely intervention.