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991.
Paula Michelotti Débora F. Gonçalves Tâmie Duarte Joelma M. Sarturi Rafael S. Da Silva Oscar E. D. Rodrigues João B. T. Rocha Cristiane L. Dalla Corte 《Journal of biochemical and molecular toxicology》2023,37(7):e23356
Zidovudine (AZT) is the most commonly prescribed antiviral drug for the treatment of human immunodeficiency virus (HIV) infection. However, its chronic administration causes toxic side effects limiting its use. This study aimed to evaluate the toxicity of different concentrations of AZT and novel chalcogen derivatives (7A, 7D, 7G, 7K, 7M) on locomotion, mitochondrial dysfunction, acetylcholinesterase (AChE) activity, and production of reactive oxygen species (ROS) in adult Drosophila melanogaster. Our results show that AZT and its derivative 7K at a concentration of 10 μM impaired flies' locomotor behavior. Furthermore, AZT and the derivatives 7K, 7A, and 7M induced mitochondrial dysfunction observed by a decrease in oxygen flux through mitochondrial complexes I and II. Neither of the compounds tested affected AChE activity or ROS production in flies. According to these data, AZT derivatives presented the following decreasing order of toxicity: 7K > AZT > 7G > 7A > 7M > 7D. Based on the chemical structure, it is possible to infer that the presence of the seleno-phenyl group in 7A and 7G increases their toxicity compared to compounds 7D and 7M. In addition, compounds 7G, 7M, and 7K with three carbon atoms as spacer were more toxic than analogs containing one carbon atom (7A and 7D). Finally, the insertion of a p-methoxyl group enhances toxicity (7K). Based on these results, excepting 7K, all other chalcogen derivatives presented lower toxicity than AZT and are potential drug candidates. 相似文献
992.
993.
Antioxidant protection by β‐selenoamines against thioacetamide‐induced oxidative stress and hepatotoxicity in mice 下载免费PDF全文
Sílvio Terra Stefanello Diane Duarte Hartmann Guilherme Pires Amaral Aline Alves Courtes Martim T. B. Leite Thayanara Cruz da Silva Débora Farina Gonçalves Micaela B. Souza Pâmela Carvalho da Rosa Luciano Dornelles Félix Alexandre Antunes Soares 《Journal of biochemical and molecular toxicology》2017,31(12)
Thioacetamide (TAA) is a hepatotoxin that rapidly triggers the necrotic process and oxidative stress in the liver. Nevertheless, organic selenium compounds, such as β‐selenoamines, can be used as pharmacological agents to diminish the oxidative damage. Thus, the aim of this study was to investigate the protective effect of the antioxidant β‐selenoamines on TAA‐induced oxidative stress in mice. Here, we observed that a single intraperitoneal injection of TAA (200 mg/kg) dramatically elevated some parameters of oxidative stress, such as lipid peroxidation and reactive oxygen species (ROS) production, as well as depleted cellular antioxidant defenses. In addition, TAA‐induced edema and morphological changes in the liver, which correlate with high serum aspartate and alanine aminotransferase enzyme activities, and a decrease in cell viability. Conversely, a significant reduction in liver lipid peroxidation, ROS production, and edema was observed in animals that received an intraperitoneal injection of β‐selenoamines (15.6 mg/kg) 1 h after TAA administration. 相似文献
994.
Marques Daniel Ruivo Gomes Ana Allen Clemente Vanda dos Santos José Moutinho Duarte Isabel Catarina Caetano Gina Castelo-Branco Miguel 《Sleep and biological rhythms》2017,15(2):167-177
Sleep and Biological Rhythms - Psychophysiological insomnia (PI) is a clinical condition characterized by sleep-related disturbing cognitive activity and biased self-related information processing.... 相似文献
995.
996.
Luis Artur Valões Bezerra André Andrian Padial Filipe Brasil Mariano Danielle Sequeira Garcez Jorge Iván Sánchez-Botero 《Environmental Biology of Fishes》2017,100(5):551-563
Tidepools are considered ecosystems of high interchangeable fish biota. However, natural and anthropogenic actions that alter negatively marine ecosystems functioning (e.g., algal exploitation) are causing homogenization of fish biodiversity. Here, we describe the functional and taxonomic assembling of fishes in beach rocks of northeastern Brazil. Traits of fish species were retrieved from Fishbase and beta diversity was assessed by the dispersion of abundance, presence-absence and functional diversity in the multivariate space. We explained spatial-temporal variation in: alpha diversity, taxonomic and functional community composition; as well as temporal variation in functional, beta and gamma diversities. We found an annual stability in fish diversity and composition, and that fish biota was assembled mainly per tidepools’ depths. Substrate heterogeneity was correlated to depth, highlighting the role of local features as filters to organize the fish fauna vertically in tidepools, especially a cultivation of algae that influences the local assembling. We also highlight the uniqueness status of beach rocks in the Brazilian tropical region. 相似文献
997.
M Valente P Murino T De Leo A Amato 《Bollettino della Società italiana di biologia sperimentale》1992,68(12):721-734
Accurate parameter estimation of allometric equations is a question of considerable interest. Various techniques that address this problem exist. In this paper it is assumed that the measured values are normally distributed and a maximum likelihood estimation approach is used. The computations involved in this procedure are reducible to relatively simple forms, and an efficient numerical algorithm is used. A listing of the computer program is included as an appendix. 相似文献
998.
Mattos-Guaraldi AL Duarte Formiga LC Pereira GA 《Microbes and infection / Institut Pasteur》2000,2(12):1507-1512
Main primary approaches and new developments in the study of the molecular basis of the adhesive process of Corynebacterium diphtheriae are reviewed along with a discussion of the potential importance of hemagglutinins, exposed sugar residues, hydrophobins and trans-sialidase enzymes as adhesins of strains of the sucrose fermenting and non-fermenting biotypes. 相似文献
999.
A Leprini U Valente S Barocci I Fontana A E Leprini S Bottero A Nocera 《Bollettino della Società italiana di biologia sperimentale》1990,66(11):1081-1088
In previous studies we have demonstrated that human normal pancreata were populated by interstitial mononuclear cells constituted by dendritic cells (70%), macrophages (30%) and few B cells (less than 1%). Furthermore, the endocrine parenchyma and the centroacinar cells appeared negative for the detection of HLA-A,B,C molecules. In the present report, 15 pancreata from cadaver donors were studied by means of immunohistochemical methods. 5 out of 15 organs were found to contain a larger amount of interstitial hematic cells that were constituted mainly by macrophages and B cells, together with a small percentage of granulocytes and T cells. In such "infiltrated" pancreata both endocrine parenchyma and centroacinar cells displayed a positivity for HLA-A,B,C antigens. As HLA-class I antigens have importance in allo-recognition and rejection responses, our data suggest that pre-transplant biopsies may be useful for a better evaluation of the pancreatic tissue immunogenicity. 相似文献
1000.
Filipe M. Cerqueira Amanda L. Photenhauer Heidi L. Doden Aric N. Brown Ahmed M. Abdel-Hamid Sarah Moraïs Edward A. Bayer Zdzislaw Wawrzak Isaac Cann Jason M. Ridlon Jesse B. Hopkins Nicole M. Koropatkin 《The Journal of biological chemistry》2022,298(5)
Ruminococcus bromii is a keystone species in the human gut that has the rare ability to degrade dietary resistant starch (RS). This bacterium secretes a suite of starch-active proteins that work together within larger complexes called amylosomes that allow R. bromii to bind and degrade RS. Starch adherence system protein 20 (Sas20) is one of the more abundant proteins assembled within amylosomes, but little could be predicted about its molecular features based on amino acid sequence. Here, we performed a structure–function analysis of Sas20 and determined that it features two discrete starch-binding domains separated by a flexible linker. We show that Sas20 domain 1 contains an N-terminal β-sandwich followed by a cluster of α-helices, and the nonreducing end of maltooligosaccharides can be captured between these structural features. Furthermore, the crystal structure of a close homolog of Sas20 domain 2 revealed a unique bilobed starch-binding groove that targets the helical α1,4-linked glycan chains found in amorphous regions of amylopectin and crystalline regions of amylose. Affinity PAGE and isothermal titration calorimetry demonstrated that both domains bind maltoheptaose and soluble starch with relatively high affinity (Kd ≤ 20 μM) but exhibit limited or no binding to cyclodextrins. Finally, small-angle X-ray scattering analysis of the individual and combined domains support that these structures are highly flexible, which may allow the protein to adopt conformations that enhance its starch-targeting efficiency. Taken together, we conclude that Sas20 binds distinct features within the starch granule, facilitating the ability of R. bromii to hydrolyze dietary RS. 相似文献