7-Dehydrocholesterol is an endogenous suppressor of ferroptosis.

Ferroptosis is a form of cell death that has received considerable attention not only as a means to eradicate defined tumour entities but also because it provides unforeseen insights into the metabolic adaptation that tumours exploit to counteract phospholipid oxidation1,2. Here, we identify proferroptotic activity of 7-dehydrocholesterol reductase (DHCR7) and an unexpected prosurvival function of its substrate, 7-dehydrocholesterol (7-DHC). Although previous studies suggested that high concentrations of 7-DHC are cytotoxic to developing neurons by favouring lipid peroxidation3, we now show that 7-DHC accumulation confers a robust prosurvival function in cancer cells. Because of its far superior reactivity towards peroxyl radicals, 7-DHC effectively shields (phospho)lipids from autoxidation and subsequent fragmentation. We provide validation in neuroblastoma and Burkitt's lymphoma xenografts where we demonstrate that the accumulation of 7-DHC is capable of inducing a shift towards a ferroptosis-resistant state in these tumours ultimately resulting in a more aggressive phenotype. Conclusively, our findings provide compelling evidence of a yet-unrecognized antiferroptotic activity of 7-DHC as a cell-intrinsic mechanism that could be exploited by cancer cells to escape ferroptosis.

Sodium fluorescein and 5-aminolevulinic acid fluorescence- guided biopsy in brain lesions: a systematic review and meta-analysis.

PURPOSE: Stereotactic brain biopsies are highly efficient for diagnosing intracerebral pathologies, particularly when surgical resection is infeasible. Fluorescence-based agents such as 5-aminolevulinic acid (5-ALA) and fluorescein sodium (NaFl) can enhance diagnostic accuracy and safety, improving the visualization of lesional tissues. This meta-analysis aimed to evaluate their effect on diagnostic yield and complication rates of brain biopsies. METHODS: This study adhered to Cochrane and PRISMA guidelines. We assessed studies for diagnostic yield and complication rates. Data was analyzed using a random-effects model in RStudio. Diagnostic accuracy measures such as sensitivity and predictive values were calculated based on fluorescence visibility in biopsy samples. RESULTS: Thirty-two non-randomized studies were included, comprising 947 patients, with a mean age ranging from 37 to 77 years, and a mean sample number ranging from 1 to 15 specimens. Diagnostic yields were high: 93% for NaFl and 96% for 5-ALA. Major complications occurred in 3% of procedures with both agents, while minor complications were reported in 7% and 5% with NaFl and 5-ALA respectively. The Negative-predictive-value (NPV) of 5-ALA and NaFl were 8-11% and 60-80% respectively. NaFl demonstrates higher sensitivity and specificity at 84% and 100% compared to 5-ALA's 66%. and 85% respectively. CONCLUSION: 5-ALA and NaFl provide high diagnostic yields with acceptable safety profiles in stereotactic biopsies. NaFl showed higher sensitivity and specificity. NaFl outperforms 5ALA in terms of NPV making it more efficient for small lesions near eloquent regions or major blood vessels. The significance of these findings can be further ascertained through randomized trials.

Baseline and stress-induced steroid plasma levels and immune function vary annually and are associated with vocal activity in male toads (Rhinella icterica).

Theoretical models predict that elevated androgen and glucocorticoid levels in males during the reproductive season promote immunosuppression. However, some studies report decreased stress response during this season. This study investigated annual variation in plasma corticosterone and testosterone levels, plasma bacterial killing ability (BKA), and neutrophil to lymphocyte ratio (NLR) in free-living male toads (Rhinella icterica). Toads were sampled in the field (baseline) and 1 h-post restraint over five months, and we considered the occurrence of vocal activity. Baseline corticosterone, testosterone, and BKA showed higher values during the reproductive period, specifically in calling male toads. The NLR was similar throughout the year, but higher values were observed in calling toads. Moreover, baseline NLR and BKA were positively correlated with both testosterone and corticosterone, suggesting higher steroid levels during reproduction are associated with enhanced cellular and humoral immunity. Despite fluctuation of baseline values, post-restraint corticosterone levels remained uniform over the year, indicating that toads reached similar maximum values throughout the year. Testosterone levels decreased following restraint before one specific reproductive period but increased in response to restraint during and after this period. Meanwhile, BKA decreased due to restraint only after the reproductive period, indicating immune protection and resilience to immunosuppression by stressors associated with steroid hormones during reproduction. Our results show that baseline and stress-induced hormonal and immune regulation varies throughout the year and are associated with vocal activity in R. icterica males, indicating a possible compromise between steroids and immune function in anuran males.

Radiosurgical thalamotomy for the management of tremors: a systematic review and meta-analysis.

Medical treatment for tremors may include beta-blockers, primidone, dopaminergic, and anticholinergic drugs but it frequently leads to pharmacoresistance. Therefore, surgical treatment gained relevance as an alternative for those patients.We aim to evaluate radiosurgical thalamotomy as an effective and safe alternative to manage tremors. Pubmed (MEDLINE), Embase, Web of Science, and the Cochrane Library databases were systematically searched for potential articles that evaluated radiosurgical thalamotomy for the management of tremor. Our analysis included 12 studies with 545 patients, 226 of whom were female. Of these, 64.6% of patients were diagnosed with essential tremor (ET), 34.6% with Parkinson's disease (PD), and 0.8% with both ET and PD. The FTM-TRS global score (MD -5.46; 95% CI [-10.44]-[-0.47]; I2 = 52%) and the drawing (MD -1.40; 95% CI [-2.03]-[-0.76]; I2 = 93%), drinking (MD -1.60; 95% CI [-1.82]-[-1.37]; I2 = 40%), and writing (MD -1.51; 95% CI [-1.89]-[-1.13]; I2 = 89%) grades showed significantly lower mean differences, favoring radiosurgical thalamotomy. A pooled proportion of 12% presented with tremor unchanged, while 38% presented with total elimination of tremor. Adverse events included: major paresis, minor paresis, dysarthria, and numbness. Thus, radiosurgical thalamotomy is a safe alternative for tremors resistant to medication, particularly in high-risk patients for RF or DBS procedures. The recommended dose of 130 to 150 Gy is effective and well-tolerated. However, randomized controlled trials (RCTs) are needed to understand the unpredictability of tissue response to radiation.

Efficacy and safety of adenosine, rapid ventricular pacing and hypothermia in cerebral aneurysms clipping: a systematic review and meta-analysis.

BACKGROUND AND OBJECTIVES: Cerebral aneurysms in complex anatomical locations and intraoperative rupture can be challenging. Many methods to reduce blood flow can facilitate its exclusion from the circulation. This study evaluated the safety and efficacy of using adenosine, rapid ventricular pacing, and hypothermia in cerebral aneurysm clipping. METHODS: Databases (PubMed, Embase, and Web of Science) were systematically searched for studies documenting the use of adenosine, rapid ventricular pacing, and hypothermia in cerebral aneurysm clipping and were included in this single-arm meta-analysis. The primary outcome was 30-day mortality. Secondary outcomes included neurological outcomes by mRs and GOS, and cardiac outcomes. We evaluated the risk of bias using ROBIN-I, a tool developed by the Cochrane Collaboration. OpenMetaAnalyst version 2.0 was used for statistical analysis and I2 measured data heterogeneity. Heterogeneity was defined as an I2 > 50%. RESULTS: Our systematic search yielded 10,100 results. After the removal of duplicates and exclusion by title and abstract, 64 studies were considered for full review, of which 29 were included. The overall risk of bias was moderate. The pooled proportions of the adenosine analysis for the different outcomes were: For the primary outcome: 11,9%; for perioperative arrhythmia: 0,19%; for postoperative arrhythmia: 0,56%; for myocardial infarction incidence: 0,01%; for follow-up good recovery (mRs 0-2): 88%; and for neurological deficit:14.1%. In the rapid ventricular pacing analysis, incidences were as follows: peri operative arrhythmia: 0,64%; postoperative arrhythmia: 0,3%; myocardial infarction: 0%. In the hypothermia analysis, the pooled proportion of 30-day mortality was 11,6%. The incidence of post-op neurological deficits was 35,4% and good recovery under neurological analysis by GOS was present in 69.2%. CONCLUSION: The use of the three methods is safe and the related complications were very low. Further studies are necessary, especially with comparative analysis, for extended knowledge.

Corticosterone treatment results in fat deposition and body mass maintenance without effects on feeding behaviour or immunity in female lizards (Tropidurus catalanensis).

Throughout life, animals must maintain homeostasis while coping with challenging events. The period after reproduction can be challenging for oviparous females to maintain homeostasis since they direct most of their energy stores to vitellogenesis, possibly increasing the vulnerability to stressors. Changes in glucocorticoids' (GC) secretion promote various behavioural and physiological adjustments daily and to restore balance after facing stressors. However, when GC are elevated for extended periods, which usually occurs in response to chronic exposure to stressors, they can affect feeding behaviour and suppress the immune function. We aim to elucidate the effects of chronic corticosterone (CORT) exposure on feeding behaviour, body condition and immune function in female lizards, Tropidurus catalanensis, in the post-reproductive period. Thirty animals were divided into three groups: 1. Control (no experimental procedure performed); 2. Empty Implant (animals implanted with empty silastic tube); and 3. CORT Implant (animals implanted with silastic tube filled with CORT, with a chronic continuous release for at least a week). CORT plasma levels feeding behaviour, body condition (body index [BI] and fat index [FI]), leukocyte count, and several immune function variables (bacterial killing ability [BKA], hemagglutination titer, phytohemagglutinin [PHA] immune challenge and leukocyte count) were evaluated. After implantation, CORT treated animals maintained stable body mass through the experiment, while Control and Empty Implant groups displayed weight loss. In the CORT treated animals, there was also a positive relation between BI and FI, and higher FI when compared to groups 1 and 2. No effects of CORT were observed on feeding behaviour nor on the immune function.

Dehydration followed by restraint sustains high circulating corticosterone and improves immunity in toads.

Amphibians are suffering population declines due to a variety of factors such as increased ultraviolet radiation, climate change, habitat loss, pathogens, and pollution, or a combination of these. Such changes are associated with a reduction in the availability of water, exposing these animals to a greater risk of desiccation. In this context, understanding how dehydration can modulate the hypothalamic-pituitary-interrenal axis (HPI) and the immune response is an imperative question to predict how stressors can affect amphibian species. We investigated whether dehydration promotes long-lasting effects on toads' ability to respond to a consecutive stressor (restraint) even if the toads are allowed to rehydrate, as well as its effects on the immune function. We also tested the hypothesis that the toads showing more severe dehydration would exhibit lower responsiveness to restraint challenge, even if the animals were allowed to rehydrate. Individuals of R. ornata were dehydrated mildly and severely. Thereafter, they were submitted to a restraint stress challenge for 1 and 24 h. Our results show that dehydration increased hematocrit and CORT in R. ornata toads. The restraint induced an acute stress response in fully hydrated toads (increased CORT and neutrophil: lymphocyte ratio). Otherwise, restraint in moistened cloth bags allowed full rehydration in previously dehydrated toads and did not induce an additional increase in CORT, but those toads sustained elevated CORT up to 24 h of restraint. Also, these animals showed increased neutrophil: lymphocyte ratio and the phagocytic activity of blood cells, even when they rehydrated during restraint. These results point to a continuous activation of the HPA during dehydration and subsequent restraint, even when they recovered from the dehydration state. Also, acute stressors seem to promote immune cell redistribution and augmentation of immune cellular function in R. ornata toads.

Baseline and stress-induced changes in plasma bacterial killing ability against gram-negative bacteria are partially mediated by the complement system in Rhinella diptycha toads.

The plasma bacterial killing ability (BKA) is modulated by the stress response in vertebrates, including amphibians. The complement system is an effector mechanism comprised of a set of proteins present in the plasma that once activated can promote bacterial lysis. Herein, we investigated whether changes in plasma BKA as a result of the acute stress response and an immune challenge are mediated by the complement system in Rhinella diptycha toads. Additionally, we investigated whether the observed changes in plasma BKA are associated with changes in plasma corticosterone levels (CORT). We subjected adult male toads to a restraint or an immune challenge (with three concentrations of Aeromonas hydrophila heat inactivated), and then evaluated the plasma BKA against A. hydrophila, in vitro. We determined the complement system activity on plasma BKA, by treating the plasma (baseline, 1 h and 24 h post-restraint, and after the immune challenge) with ethylenediaminetetraacetic acid, heat, or protease. Our results showed increased CORT 1 h and 24 h after restraint and decreased plasma BKA 24 h post-restraint. The inhibitors of the complement system decreased the plasma BKA compared with untreated plasma at all times (baseline, 1 h, and 24 h after restraint), demonstrating that the plasma BKA activity is partially mediated by the complement system. The immune challenge increased CORT, with the highest values being observed in the highest bacterial concentration, compared with control. The plasma BKA was not affected by the immune challenge but was demonstrated to be partially mediated by the complement system. Our results demonstrated that restraint and the immune challenge activated the hypothalamus-pituitary-interrenal axis, by increasing plasma CORT levels in R. diptycha. Also, our results demonstrated the complement system is participative in the plasma BKA for baseline and post-stress situations in these toads.

Immune and endocrine alterations at the early stage of inflammatory assemblage in toads after stimulation with heat-killed bacteria (Aeromonas hydrophila).

The red-leg syndrome in amphibians is a condition commonly associated with the bacteria Aeromonas hydrophila and has led to population declines. However, there is little information concerning the inflammatory assemblage in infected anurans. We evaluated immune and endocrine alterations induced by stimulation with heat-killed A. hydrophila injected in Rhinella diptycha toads. Control animals were not manipulated, while the others were separated into groups that received intraperitoneal injection of 300 µl of saline or heat-killed bacteria: groups A1 (3 × 107 cells), A2 (3 × 108 cells), and A3 (3 × 109 cells). Animals were bled and euthanized six hours post-injection. We evaluated neutrophil: lymphocyte ratio (NLR), plasma bacterial killing ability (BKA), testosterone (T), melatonin (MEL), and corticosterone (CORT) plasma levels. Heat-killed A. hydrophila increased CORT and NLR, and decreased MEL, especially at higher concentrations. There was no effect of treatment on T and BKA. We then selected the saline and A3 groups to conduct mRNA expression of several genes including glucocorticoid receptor (GR), toll-like receptor-4 (TLR-4), interferon-γ (IFN-γ), interleukin (IL)-1ß, IL-6, and IL-10. We found higher expression of IL-6, IL-1ß, IL-10, and IFN-γ in group A3 compared to the saline group. These results indicate the beginning of an inflammatory assemblage, notably at the two highest concentrations of bacteria, and give a better understanding of how anurans respond to an infection within an integrated perspective, evaluating different physiological aspects. Future studies should investigate later phases of the immune response to elucidate more about the inflammation in amphibians challenged with A. hydrophila.

Is time really brain in stroke therapy?: A meta-analysis of mechanical thrombectomy up to 155 h post ictus.

BACKGROUND AND OBJECTIVES: Mechanical thrombectomy (MT) has been established as the gold standard of treatment for patients with Acute Ischemic Stroke (AIS) who present up to 6 h after the onset of the stroke. Recently, the DEFUSE-3 and DAWN trials established the safety of starting the MT procedure up to 16 and 24 h after the patient was last seen well, respectively. The purpose of this study is to assess the safety and functional effects of thrombectomy in individuals with AIS detected at a late stage (> 24 h). MATERIALS AND METHODS: PubMed, Web of Science, Embase, and Cochrane databases were thoroughly searched for research on MT in patients in the extremely late time window after AIS. The primary outcomes were symptomatic cerebral hemorrhage, 90-day mortality, Thrombolysis in Cerebral Infarction (TICI) 2b-3, and Modified Rankin Scale (mRS) 0-2. RESULTS: Our study included fifteen studies involving a total of 1,221 patients who presented with AIS and an extended time window. The primary outcome of interest was the favorable functional outcome, mRS 0-2 at 90 days. The pooled proportion for this outcome was 45% (95% confidence interval 34-58%). Other outcomes included the TICI 2b or 3 (successful recanalization), which was reported in 12 studies and had a 79% incidence in the study population (95% CI 68-87%). Complications included: symptomatic intracranial hemorrhage (sICH), which revealed an incidence of 7% in the study population (95% CI 5-10%); and 90-day mortality, which reported a 27% incidence (95% CI 24-31%). In addition, we conducted a comparative analysis between endovascular treatment and standard medical therapy. CONCLUSION: Our meta-analysis provides evidence that supports the need of further randomized and prospective clinical trials to better assess the effectiveness and safety of MT in these patients.

Environmental and agronomic assessment of soil conditioners produced from bauxite residue and oil palm wastes.

Soil conditioner is class of products used to enhance physics, physicochemical or soil biological activities, being able to recover disturbed or nutritional unbalanced soils. The formulation of a soil conditioner composed by bauxite residue (BR), and organic oil palm wastes, as raw materials, was recently proposed as an innovative strategy for the Brazilian acid soils amendment. Here we show the results of soil conditioner amended soil leaching tests and agronomical performance. The soil conditioners were formulated by BR mixed with decomposed POC (palm oil compost) and non-decomposed POMW (palm oil mill waste) oil palm wastes, in the proportion of 25% BR + 75% POC (T1) and 50% BR + 50% POMW (T2), in addition to the treatment with 100% POMW without BR (T3) and limestone at a dose calculated to raise soil pH to 6.0 (T4). Except for T4, all conditioners were applied to the soil at doses of 40, 80, and 120 t ha-1 for leaching tests. The experimental plots were composed of polyvinyl chloride columns, filled with 5 kg of soil, with bottles adapted with hoses at the bottom to facilitate drainage of the leachate. After leaching tests, the respective columns were used as pots for the cultivation of Brachiaria grass, stage with addition of a control composed by undisturbed soil (T5). The pH of the leachates had changes, but the use of BR associated with POMW was similar to the use of limestone. Of the 65 chemical elements evaluated, only nine were identified in the leachate, being most of them considered as plant nutrients. As for soil pH, limestone was slightly higher (6.6) than treatments that had BR (5.5). Brachiaria grass cultivated in the soil amended with conditioners showed similar results of limestone treated soil for the parameters of plant development and showed fertility improvement.

Efficacy and safety of cavernous sinus medial wall resection in pituitary adenoma surgery: a systematic review and a single-arm meta-analysis.

INTRODUCTION: Pituitary adenomas, benign tumors, can lower quality of life. Pituitary adenomas that invade the medial wall and cavernous sinus (CS) indicate tumor recurrence and partial surgical excision. Despite the cavernous sinus's complexity and risks, new research has improved the surgical procedure and made excision safer. This comprehensive review and single-arm meta-analysis evaluates endocrinological remission and resection rates in pituitary adenomas to determine the benefits and risks of MWCS resection. METHODS: Databases were systematically searched for studies documenting the resection of the medial wall of the cavernous sinus. The primary outcome was endocrinological remission in patients who underwent resection of the MWCS. RESULTS: Eight studies were included in the final analysis. The pooled proportion of endocrinological remission (ER) was 63.3%. The excision of MWCS pooled a gross total resection (GTR) proportion of 72.9%. Finally, ICA injury attained a pooled ratio of 0.5%, indicating minimal morbidity in the procedure. CONCLUSION: The cavernous sinus was ruled out, proving the MWCS excision is safe. Limiting population selection to Knosp 3A or lower enhanced GTR frequencies and lowered recurrence, according to subgroup analyses. This meta-analysis shows that MWCS resection can be a beneficial treatment option for pituitary tumors, when there is no macroscopic medial wall invasion and careful patient selection is done, especially for GH- and ACTH-producing tumors that can cause life-threatening metabolic changes.

Relationships between hormone levels, metabolism and immune response in toads from a semi-arid region.

Steroid hormones (e.g. androgens [AN] and corticosterone [CORT]) modulate complex physiological functions such as reproduction, energy mobilization, metabolism, and immunity. The effects of these steroids on immunocompetence and its metabolic costs can also be affected by fluctuations in environmental resource availability and other factors such as parasitism. To understand these possible interactions, we studied AN and CORT, immune response [swelling response to phytohemagglutinin (PHA) injection and bacterial killing ability (BKA)], parasite load, resting metabolic rate (RMR) and post-immune challenge (PHA injection) oxygen consumption rates during two different phases of the annual cycle of Rhinella jimi toads from the Brazilian semi-arid region (Caatinga), where environmental conditions are highly seasonal. We observed an increase in O2 consumption rates after both PHA and saline (control) injections, indicating a metabolic response to adverse stimuli rather than the immune challenge. Toads showing higher RMR and VO2 after the adverse stimuli (PHA/saline injections) had lower field AN and CORT plasma levels, suggesting these hormones might mediate a metabolic energy conservation strategy both at baseline levels and after adverse stimuli. Parasite load appear to constrain the metabolic response to PHA and saline injections. Additionally, individuals with a higher swelling response to PHA had higher field CORT plasma levels (particularly when males are breeding), which opposes the idea of a possible trade-off between reproductive activity and other physiological traits, indicating the immunoenhancing effects of elevated CORT at physiological levels. BKA did not show a seasonal variation or correlation with body condition or hormone levels, indicating that the immune surveillance mediated by the complement remains constant despite ecological and physiological changes.

Early ambulation versus prolonged bed rest for incidental durotomies in spine procedures: a systematic review and meta-analysis.

Incidental durotomies are frequent complications of spine surgery associated with cerebrospinal fluid (CSF) leak-related symptoms. Management typically involves prolonged bed rest to reduce CSF pressure at the durotomy site. However, early ambulation may be a safer, effective alternative. PubMed, Web of Science, Embase, Cochrane, and Scopus were systematically searched for studies comparing early ambulation (bed rest ≤ 24 h) with prolonged bed rest (> 24 h) for patients with incidental durotomies in spine surgeries. The outcomes of interest were CSF leak, hypotensive headache, additional surgical repair, pseudomeningocele, and pulmonary complications. Systematic reviews and meta-analysis were performed following the Cochrane Handbook for Systematic Reviews of Interventions. We included a total of 704 patients from 6 studies. There was a significant reduction in the incidence of pulmonary complications (RR 0.23; 95% CI 0.08-0.67; p = 0.007) in the early mobilization group. The incidence of CSF leak (RR 1.34; 95% CI 0.83-2.14; p = 0.23), hypotensive headache (RR 0.72; 95% CI 0.27-1.90; p = 0.50), additional repair surgery (RR 1.29; 95% CI 0.76-2.2; p = 0.35), and pseudomeningocele (RR 1.29; 95% CI 0.20-8.48; p = 0.79) did not differ significantly. In patients with incidental durotomy following spinal surgery, early mobilization was associated with a lower incidence of pulmonary complications as compared with prolonged bed rest. There was no significant difference between groups in terms of CSF leak, need for additional repair, pseudomeningocele, and hypotensive headache.

Robot-assisted vs. manually guided stereoelectroencephalography for refractory epilepsy: a systematic review and meta-analysis.

Robotic assistance has improved electrode implantation precision in stereoelectroencephalography (SEEG) for refractory epilepsy patients. We sought to assess the relative safety of the robotic-assisted (RA) procedure compared to the traditional hand-guided one. A systematic search on PubMed, Web of Science, Embase, and Cochrane was performed for studies directly comparing robot-assisted vs. manually guided SEEG to treat refractory epilepsy. The primary outcomes included target point error (TPE), entry point error (EPE), time of implantation of each electrode, operative time, postoperative intracranial hemorrhage, infection, and neurologic deficit. We included 427 patients from 11 studies, of whom 232 (54.3%) underwent robot-assisted surgery and 196 (45.7%) underwent manually guided surgery. The primary endpoint, TPE, was not statistically significant (MD 0.04 mm; 95% CI - 0.21, - 0.29; p = 0.76). Nonetheless, EPE was significantly lower in the intervention group (MD - 0.57 mm; 95% CI - 1.08; - 0.06; p = 0.03). Total operative time was significantly lower in the RA group (MD - 23.66 min; 95% CI - 32.01, - 15.31; p < 0.00001), as well as the individual time of implantation of each electrode (MD - 3.35 min; 95% CI - 3.68, - 3.03; p < 0.00001). Postoperative intracranial hemorrhage did not differ between groups: robotic (9/145; 6.2%) vs. manual (8/139; 5.7%) (RR 0.97; 95% CI 0.40-2.34; p = 0.94). There was no statistically relevant difference in infection (p = 0.4) and postoperative neurological deficit (p = 0.47) incidence between the two groups. In this analysis, there is a potential relevance in the RA procedure when comparing the traditional one, since operative time, time of implantation of each electrode, and EPE were significantly lower in the robotic group. More research is needed to corroborate the superiority of this novel technique.

Absence of Gem1 (mammalian Miro/Rhot) mitigates alpha-synuclein toxicity in a yeast model of Parkinson's disease.

Alpha-synuclein aggregation is a hallmark of Parkinson's disease (PD). Mutants A30P and A53T alpha-synuclein are known to exacerbate the toxicity of alpha-synuclein, which includes oxidative stress, mitochondrial and endoplasmic reticulum (ER) dysfunction. Saccharomyces cerevisiae (budding yeast) is a cellular model widely used to investigate mechanisms underlying neurodegenerative disorders, such as PD. In yeast, Gem1 (Miro/Rhot mammalian orthologue) coordinates mitochondrial dynamics and ER homeostasis, which is impaired in the presence of mutant alpha-synuclein and can lead to cell death. In this study, A30P or A53T alpha-synuclein were expressed in wild type or ΔGem (deletion of Gem1 gene) yeast strains. ΔGem cells presented decreased viability and increased mitochondrial H2O2 production and ER stress compared to wild type cells. However, in the presence of mutant alpha-synuclein, ΔGem cells showed increased growth compared to cells that do not express mutant alpha-synuclein. ΔGem cells expressing A53T alpha-synuclein also presented reduced ER stress and increased ability to deal with oxidative stress. Together, our results suggest that deletion of Gem1 activates pathways that strengthen cells against other stressful agents such as the presence of mutant alpha-synuclein.

Elevated corticosterone levels are associated with increased immunocompetence in male toads, both when calling and under experimental conditions.

Circulating androgens can influence immune responses and sexual traits in male vertebrates. However, in the last 20 years, glucocorticoids have also been implicated as a possible source of variation in male sexual traits and immunocompetence. In this context, we studied the relations between male vocal mating display, immunity, androgens, and glucocorticoids in the explosive breeding toad Rhinella granulosa. In the field, males with high calling effort display either high- or low-corticosterone (CORT) plasma levels, but only males with both high calling effort and high CORT plasma levels showed high bacterial killing ability (BKA), suggesting that the acute CORT elevation can be immunostimulatory. CORT treatments increased BKA in laboratory experiments, confirming the functional relationship observed in the field. However, toads treated with a low dose of CORT increased BKA for 10 h after the treatment, while toads that received a high dose increased BKA for only 1 h after the treatment. These results indicate that different CORT doses can result in temporal differences in the immune response. We did not find any relationship between calling effort, immune response (BKA and PHA swelling response), and testosterone plasma levels in the field, or any effects of testosterone treatment on immunocompetence. Our results suggest a complex relationship between calling effort and immunity, mediated by CORT plasma levels.

Plasma steroids and immune measures vary with restraint duration in a toad (Rhinella icterica).

Immunoenhancing effects have been widely described following acute stressors in several vertebrates, and valuable contributions have been made from studies on acute stress to understand hormonal-immune interactions. However, most studies focus on hormonal and immune responses after standardized time lapses, neglecting potential influence of duration of exposition to stressor. Herein, we investigate fluctuations of plasma hormone concentrations (corticosterone and testosterone) and immunity (neutrophil to lymphocyte ratio, phagocytosis of blood cells, and plasma bacterial killing ability) in a toad species (Rhinella icterica) in response to six different periods of exposure to restraint stress. We observed increased plasma corticosterone concentrations following restraint in all sampled times (0.5 to 48 h), with the highest values being observed during the first hour (0.5 to 1 h). Restraint-induced increases in the neutrophil to lymphocyte ratio and phagocytosis percentage were observed from the first 0.5 h, gradually increasing after that with the time of restraint. We also observed decreased testosterone plasma concentrations in response to a more prolonged restraint (24 and 48 h). No changes were observed in plasma bacterial killing ability following restraint. Together, our results demonstrate dynamic time-related hormonal and immune changes. These results point to the fact that for some species measuring hormonal and immune variables at single time points following a stressor might work better when preceded by a study of the temporal changes of the response variables to the stimuli applied. Also, time of response needs to be considered when different variables are used as proxies of stress.

Immune and hormonal regulation of the Boa constrictor (Serpentes; Boidae) in response to feeding.

Feeding upregulates immune function and the systemic and local (gastrointestinal tract) concentrations of some immunoregulatory hormones, as corticosterone (CORT) and melatonin (MEL), in mammals and anurans. However, little is known about the immune and hormonal regulation in response to feeding in other ectothermic vertebrates, especially snakes, in which the postprandial metabolic changes are pronounced. Here, we investigated the effects feeding have on hormonal and innate immune responses in the snake, Boa constrictor. We divided juvenile males into two groups: fasting and fed with mice (30% of body mass). We measured the rates of oxygen consumption, plasma CORT levels, heterophil/lymphocyte ratio (HL ratio), plasma bacterial killing ability (BKA), and stomach and intestine MEL in fasting snakes and 48 h after meal intake. We observed increased rates of oxygen consumption, plasma CORT levels, and HL ratio, along with a tendency of decreased stomach and intestine MEL in fed snakes compared to fasting ones. BKA was not affected by feeding. Overall, we found that feeding modulates metabolic rates, CORT levels, and immune cell distribution in boas. Increased baseline CORT may be important to mobilize energy to support the metabolic increment during the postprandial period. Increased HL ratio might be an immunoregulatory effect of increased CORT, which has been shown in different physiological situations such as in response to immune challenge. Our results suggest that feeding activates the hypothalamic-pituitary-adrenal axis and modulates immune cell redistribution, possibly contributing to fighting potential injuries and infections derived from predation and from pathogens present in ingested food.

Immune and endocrine responses of Cururu toads (Rhinella icterica) in their natural habitat after LPS stimulation.

Glucocorticoids and melatonin display immunomodulatory functions, with both immune-stimulatory and suppressor effects, depending on the context. While their immune properties are well-explored in mammals, there are still few studies on this immune-endocrine interaction in an inflammatory context in amphibians, all of them under captivity conditions, which can constitute a stressor for these animals. Evaluating how amphibians react to an immune challenge in the field would reveal relevant information regarding how immune-physiological parameters are modulated in natural conditions. This study aimed to investigate the effects of lipopolysaccharide (LPS) injection in male toads (Rhinella icterica) recently captured in their natural habitat in the Atlantic Forest at two different times of the day. We evaluated: splenic cytokines mRNA (interleukin [IL]-1ß, IL-6, IL-10, interferon-γ) and complement system protein (C1s), plasma bacterial killing ability (BKA), plasma corticosterone (CORT), melatonin (MEL), and testosterone (T) levels, and neutrophil to lymphocyte ratio (NLR), two hours post-injections. LPS-injection increased NLR, the gene expression of IL-1ß, and less evidently CORT levels independently of the time of the day. These results evidence LPS-induced inflammation, similarly observed in toads in captivity. Saline and LPS-injected toads showed a positive correlation between IL-1ß and IL-6, both cytokines with pro-inflammatory effects. Also, CORT was negatively associated with T, suggesting inhibition of the hypothalamus-pituitary-gonadal axis in the LPS-stimulated group. Our results are associated with the first stage of the inflammatory assemblage. Studies evaluating further steps of this process might lead to a better understanding of the immune-endocrine relations in amphibians.