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Reconstruções paleoecológicas da megafauna do Pleistoceno final da Região Intertropical Brasileira

2026-03-11T16:44:39Z

Título: Reconstruções paleoecológicas da megafauna do Pleistoceno final da Região Intertropical Brasileira Autor(es): Cruz, Evelyn Nathália da Silva Abstract: Pleistocene megafauna, composed of large-bodied mammals resilient to Quaternary climatic fluctuations, exhibited a wide distribution across the Brazilian territory, particularly within the Brazilian Intertropical Region, favored by high climatic suitability. The subsequent weakening of these populations, driven by climate changes and associated factors such as the arrival of PaleoIndians in South America, contributed to their extinction at the beginning of the Holocene, resulting in profound changes in ecosystem structure and functioning. The ecology of extinct species can be investigated through paleoecological tools, including stable and radiogenic isotope analyses. Stable carbon (δ¹³C) and oxygen (δ¹⁸O) isotopes allow inferences regarding diet and paleoenvironments, whereas radiogenic isotopes, such as strontium (⁸⁷Sr/⁸⁶Sr), enable the reconstruction of mobility and migration patterns. In tropical and subtropical regions, these signals are preferentially obtained from bioapatite due to the frequent degradation of collagen. However, to ensure the reliability of isotopic results, it is essential to assess fossil preservation and the potential influence of diagenetic processes, which remain poorly investigated in South America. In this study, we aimed to generate robust paleoecological inferences for different Pleistocene megafaunal species across distinct environmental contexts and analytical approaches. In the first chapter, we evaluated the quality of bioapatite in samples of Eremotherium laurillardi and Toxodontinae by comparing enamel, dentine, and associated soil, as well as testing sampling strategies for fossils recovered from natural tank deposits. In the second chapter, serial isotopic analyses were applied to identify seasonal dietary patterns in these species. In the third chapter, strontium isotope analyses demonstrated that Notiomastodon platensis exhibited migratory behavior, being capable of crossing geographic barriers such as the São Francisco River, and allowed the identification of the most recent specimen published to date. Finally, in the fourth chapter, we integrate isotopic data, climatic suitability, morphological attributes, and characteristics of fruits potentially consumed by browsing species, revealing a significant negative association between mean seed diameter and herbivore body mass. Taken together, this thesis strengthens methodological protocols, expands the application of isotopes in tropical contexts, and presents novel results on diet, seasonality, migration, and ecological interactions of Pleistocene megafauna in Brazil.

Perfil clínico-neurofisiológico da dor em pessoas com doença de Parkinson: estudo observacional transversal

2026-03-09T13:27:07Z

Título: Perfil clínico-neurofisiológico da dor em pessoas com doença de Parkinson: estudo observacional transversal Autor(es): Santos, Annanda Oliveira Abstract: Introduction: Parkinson's disease (PD) is a chronic, progressive neurodegenerative condition characterized by the degeneration of dopaminergic neurons in the nigrostriatal pathway and the presence of Lewy bodies, which result from misfolded α-synuclein proteins located in the dopaminergic presynaptic membrane within basal ganglia. The role of pain in PD is debated, as it may be a precursor, concurrent, or secondary symptom. Pain, whether acute or chronic, is complex and challenging in clinical management. Objective: To identify the characteristics of pain in PD and to explore its physiological mechanisms through qualitative sensory tests (QSTs). Materials and Methods: This cross-sectional epidemiological study (CAAE: 64807417.6.0000.5546) involved 33 volunteers with clinically diagnosed PD (20 men, age 58.75 ± 5.16 years; 13 women, age 65.92 ± 7.70 years). Variables analyzed included pain intensity, incidence, and impact, alongside peripheral sensory thresholds, primary and secondary hyperalgesia, ascending and descending nerve function, and thermal latency. Statistical analyses were conducted using SPSS 30.0 and GraphPad Prism 8.0, with significance set at p≤0.05. Tests included Shapiro-Wilk for normality, Mann-Whitney U, Wilcoxon, and one-way repeated measures ANOVA with Bonferroni post-hoc corrections. Results: Most participants reported moderate to severe pain in the last week, with a maximum pain intensity of 6.15 and an average of 3.61. Men reported higher average and minimum pain intensity compared to women, and pain during crises was significantly higher than at rest (p<0.001). Thermal and pain sensitivity testing revealed potential deficits in sensory accommodation, with only six volunteers enduring the maximum time for thermal stimulus, showing an average tolerance of 46.06 seconds. A total of 88 distinct pain sites were identified, highlighting pain’s significant impact on PD and suggesting sensory modulation deficits related to the condition. Conclusion: People with PD have associated chronic pain, with deficits in the excitatory and inhibitory pain pathways. In addition, pain perception is increased, corroborating the findings of chronification.

Avaliação citotóxica de derivados glicosídicos da lausona em linhagens tumorais

2026-03-09T13:11:27Z

Título: Avaliação citotóxica de derivados glicosídicos da lausona em linhagens tumorais Autor(es): Sousa, Rauan Cruz de Abstract: Cancer is a disease characterized by the abnormal growth of cells that can invade other tissues and spread to other organs, representing a major public health issue. One of the main challenges in cancer treatment is the low selectivity of the chemotherapeutic agents currently used, highlighting the need to investigate new compounds. Lawsone, a plant-derived product, has shown cytotoxic effects in different tumor cell lines, and chemical modifications to its structure can lead to more potent derivatives. Additionally, anomeric isomer derivatives exhibit similar chemical structures, differing only in the orientation of the anomeric carbon, which may influence their biological properties. Therefore, the aim of this study was to evaluate the cytotoxic activity of two anomeric derivatives of lawsone, APSO-5 and APSO-19, in lung carcinoma (A549), melanoma (B16-F10), and glioma (C6) cell lines. The cytotoxicity of the lawsone derivatives, as well as of lawsone itself, was assessed using the Sulforhodamine B assay in the tumor cell lines to determine the IC50 and select the most responsive cell line for subsequent experiments. The results showed that both compounds exhibited cytotoxic effects in all tested cell lines, with IC50 values below 12 μM. The A549 cell line was selected for further experiments, as lung carcinoma is the most prevalent and deadly type of cancer, making the identification of promising therapeutic compounds particularly relevant. The clonogenic assay demonstrated that both compounds reduced colony formation in A549 cells. Furthermore, APSO-19 was found to inhibit cell migration after 24 hours of treatment. Fluorescence assays using DAPI and Phalloidin/FITC revealed morphological changes in A549 cells treated with the derivatives, such as cytoplasmic shrinkage, cell rounding, and the presence of apoptotic bodies. It was also observed that higher concentrations of APSO-19 induced ROS production in A549 cells. Finally, none of the studied compounds showed toxicity toward human erythrocytes. In conclusion, the anomeric glycosidic derivatives of lawsone demonstrated strong cytotoxic effects in the tested cell lines and exhibited distinct biological activities, with APSO-19 showing greater ROS induction and inhibition of migration capacity in A549 cells.

Estudo da interferência do álcool perílico na atividade antitumoral da doxorrubicina em camundongos com sarcoma 180

2026-03-04T13:19:16Z

Título: Estudo da interferência do álcool perílico na atividade antitumoral da doxorrubicina em camundongos com sarcoma 180 Autor(es): Lima, Lorrane Nere de Abstract: The therapeutic management of sarcomas remains a clinical challenge due to the high heterogeneity and complexity of these neoplasms. Therefore, the combination of antineoplastic agents is fundamental to increase antitumor efficacy and mitigate toxic effects. Doxorubicin, the drug of choice in the treatment of sarcomas, has broad clinical efficacy; however, it can cause a risk of cardiotoxicity, as well as hepatotoxicity and hematological toxicity mediated by oxidative stress and inflammation. Perillyl alcohol, a monoterpene with anticancer, antioxidant, and anti-inflammatory properties, could potentiate the antitumor effect of doxorubicin and attenuate its toxic effects. Therefore, the aim of this study was to evaluate the interference of perillyl alcohol on the antitumor activity of doxorubicin in mice with sarcoma 180. For this, 56 male Swiss mice, transplanted with Sarcoma 180 cells, were distributed into 8 groups (n=7), namely: Saline [tween 80 0.2%, orally, on consecutive days + sodium chloride 0.9%, on alternate days, intraperitoneally (ip.)]; DOX (doxorubicin 2 mg/kg, on alternate days, i.p.); POH 50 (perillyl alcohol 50 mg/kg/day, orally), POH 100 (perillyl alcohol 100 mg/kg/day, orally), POH 200 (perillyl alcohol 200 mg/kg/day, orally), POH 50 + DOX (perillyl alcohol 50 mg/kg/day, orally + doxorubicin 2 mg/kg, every other day, intraperitoneally), POH 100 + DOX (perillyl alcohol 100 mg/kg/day, orally + doxorubicin 2 mg/kg, every other day, intraperitoneally), and POH 200 + DOX (perillyl alcohol 200 mg/kg/day, orally + doxorubicin 2 mg/kg, every other day, intraperitoneally). These treatments were administered for 9 days. Following the experiment, parameters of tumor inhibition, body and organ mass, biochemical markers of cardiac and hepatic injury, oxidative stress in cardiac and hepatic tissue – through levels of malondialdehyde (MDA), total sulfhydryls, and activity of glutathione peroxidase (GPX) and superoxide dismutase (SOD) – and hematological analysis were evaluated. Data were processed using the Shapiro-Wilk test, analysis of variance (one-way or two-way), and Tukey's post-hoc test. The results showed that the combined treatment did not present a significant antitumor effect. In toxicological parameters, the combined treatment led to loss of body mass and heart and liver mass, as well as elevation of levels of biochemical markers of cardiac and hepatic injury, especially in the POH 50 + DOX and POH 100 + DOX groups. In oxidative stress of cardiac tissue, the POH 100 + DOX and POH 200 + DOX groups showed elevated MDA levels, with increased SOD activity in the latter group. In liver tissue, MDA levels decreased in both combined treatment groups, and GPX activity increased. Hematological analysis showed that the alterations induced by doxorubicin persisted in the combined treatment. Therefore, perillyl alcohol combined with doxorubicin did not show promise in the treatment of sarcoma 180.