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Robert S. Aronstam Michael W. Edwards John W. Daly X. Albuquerque 《Neurochemical research》1988,13(2):171-176
The interactions of eight piperidine derivatives with nicotinic receptor complexes fromTorpedo californica electric organ were studied using [125I]alpha-bungarotoxin ([125I]BGT) as a probe for the acetylcholine binding site and [3H]perhydrohistrionicotoxin ([3H]H12-HTX) as a probe for a site associated with the receptor-gated ion channel.Cis- andtrans-2-methyl-6-n-undecanyl piperidines (MUP), major constituents of fire ant venom, had a high-affinity for [3H]H12-HTX binding sites (Ki=0.08–0.24 M), but had no affect on receptor binding. MUP affinity for [3H]H12-HTX binding sites was approximately doubled in the presence of 1 M carbamylcholine. Introduction of a 2-hydroxyl group to the undecanyl side channel had little effect on activity of the alkaloid. The analog 2,6- (but not 3,5-) dimethylpiperidine was a moderately active inhibitor of [3H]H12-HTX binding (K
i-8.8 M). 2-Methylpiperidine was considerably less active (K
i=600 M), although it was more potent than either 3- or 4-methylpiperidine. The affinities of 2,6-dimethylpiperidine and 2-methylpiperidine for [3H]H12-HTX binding sites were decreased in the presence of 1 M carbamylcholine. Carbamylcholine affinity for the receptor was increased by up to 7 fold in the presence of 10 and 32 M MUP, but was decreased in the presence of 2,6-dimethylpiperidine and 2-methylpiperidine. Thecis- andtrans-isomers of MUP were equipotent in producing each of its effects. In these actions, MUP resembles a variety of other compounds derived from 2,6-disubstituted piperidines, including histrionicotoxins, gephyrotoxins and pumiliotoxins. These studies establish the importance of alkyl substitutions in theortho position of the piperidine ring in conferring ion channel specificity, and the importance of substantial alkyl side chains in conferring the ability of channel blockers to stabilize the nicotinic receptor complex in high affinity, desensitized conformations. 相似文献
3.
alpha-Bungarotoxin-sensitive hippocampal nicotinic receptor channel has a high calcium permeability. 总被引:5,自引:0,他引:5 下载免费PDF全文
The hippocampal nicotinic acetylcholine receptor (nAChR) is a newly identified ligand-gated ion channel that is blocked by the snake toxin alpha-bungarotoxin (alpha-BGT) and that probably contains the alpha 7 nAChR subunit in its structure. Here its ion selectivity was characterized and compared with that of the N-methyl-D-aspartate (NMDA) receptor channel. The reversal potentials (VR) of acetylcholine- and NMDA-activated whole-cell currents were determined under various ionic conditions. Using ion activities and a Goldman-Hodgkin-Katz equation for VR shifts in the presence of Ca2+, permeability ratios were calculated. For the alpha-BGT-sensitive nAChR, PNa/PCs was close to 1 and Cl- did not contribute to the currents. Changing the [Ca2+]0 from 1 to 10 mM, the VRs of the nAChR and NMDA currents were shifted by +5.6 +/- 0.4 and +8.3 +/- 0.4 mV, respectively, and the nAChR current decay was accelerated. These shifts yielded PCa/PCss of 6.1 +/- 0.5 for the nAChR channel and 10.3 +/- 0.7 for the NMDA channel. Thus, the neuronal alpha-BGT-sensitive nAChR is a cation channel considerably selective to Ca2+ and may mediate a fast rise in intracellular Ca2+ that would increase in magnitude with membrane hyperpolarization. 相似文献
4.
Alexandre P. Hercos Ana Carolina Prado-Valladares Jana M. del Favero Nagila A. Zuchi Túlio F. Teixeira Fábio E. A. Albuquerque Helder L. de Queiroz 《Zeitschrift fur angewandte Ichthyologie》2021,37(6):985-988
Length-weight relationships (LWRs) were estimated for 16 ornamental fish species from Amanã Lake and nine tributary streams, in Central Brazilian Amazonia. Sampling was carried out bimonthly for a year (2007–2008), using two sets of four gillnets (20 m × 2 m, 2,5; 3,5; 04; 4,5 cm stretch mesh size); trawls were performed with seine nets (35 m × 6 m, 3 mm stretch mesh size); native fish-traps (fyke-net like fish-traps woven from local lianas), and dip nets (0.5 m × 0.5 m stretch mesh size). Measurements were done for standard length (SL – 0.1 cm precision) and total weight (Wt – 0.01 g precision). This study provides information on the length–weight relationships for all sampled species and, in addition, provides new maximum standard lengths for six species. 相似文献
5.
Central giant cell lesion of the jaws: study of CCND1 gene amplification and p16INK4a protein levels
Renato Luiz Maia Nogueira Mário Henrique Girão Faria Rafael Lima Verde Osterne Roberta Barroso Cavalcante Ronaldo Albuquerque Ribeiro Cassiano Francisco Weege Nonaka Silvia Helena Barem Rabenhorst 《Journal of molecular histology》2013,44(5):527-534
Central giant cell lesions (CGCLs) are uncommon benign jaw lesions with uncertain etiology and a variable clinical behavior. In neoplasms, alterations in molecules involved in the G1/S checkpoint are frequently found. Loss of p16INK4a expression or overexpression of cyclin D1 may stimulate cell proliferation. The purpose of this study was to analyze CCND1 gene amplification and the expression of p16INK4a in CGCLs. Structural analysis of the CCND1 was performed using chromogenic in situ hybridization. Immmunohistochemistry was used to identify p16INK4a protein levels. Statistical analysis correlated the two biomarkers with clinical behavior and between each other. Twenty-four lesions were included, being 11 aggressive and 13 non-aggressive. Moderate/high-level CCND1 amplification was found in 12 lesions. Also, immunoreactivity for p16INK4a was present in 12 cases, mainly in mononuclear cells. There was a significantly higher level of p16INK4a expression in mononuclear cells of non-aggressive lesions and lesions with moderate/high-level CCND1 amplification in mononuclear cells. It could be speculated that some CGCLs may develop as a true benign neoplasm. The higher expression of p16INK4a in non-aggressive lesions and in cases with moderate/high-level CCND1 amplification may show that these molecules have a role in CGCLs. 相似文献
6.
Diego de Souza Gonalves Marina da Silva Ferreira Kamilla Xavier Gomes Claudia Rodríguez‐de La Noval Susie Coutinho Liedke Giovani Carlo Veríssimo da Costa Patricia Albuquerque Juliana Reis Cortines Regina Helena Saramago Peralta Jos Mauro Peralta Arturo Casadevall Allan J. Guimares 《Cellular microbiology》2019,21(10)
Free‐living amoebae (FLAs) are major reservoirs for a variety of bacteria, viruses, and fungi. The most studied mycophagic FLA, Acanthamoeba castellanii (Ac), is a potential environmental host for endemic fungal pathogens such as Cryptococcus spp., Histoplasma capsulatum, Blastomyces dermatitides, and Sporothrix schenckii. However, the mechanisms involved in this interaction are poorly understood. The aim of this work was to characterize the molecular instances that enable Ac to interact with and ingest fungal pathogens, a process that could lead to selection and maintenance of possible virulence factors. The interaction of Ac with a variety of fungal pathogens was analysed in a multifactorial evaluation that included the role of multiplicity of infection over time. Fungal binding to Ac surface by living image consisted of a quick process, and fungal initial extrusion (vomocytosis) was detected from 15 to 80 min depending on the organism. When these fungi were cocultured with the amoeba, only Candida albicans and Cryptococcus neoformans were able to grow, whereas Paracoccidioides brasiliensis and Sporothrix brasiliensis displayed unchanged viability. Yeasts of H. capsulatum and Saccharomyces cerevisiae were rapidly killed by Ac; however, some cells remained viable after 48 hr. To evaluate changes in fungal virulence upon cocultivation with Ac, recovered yeasts were used to infect Galleria mellonella, and in all instances, they killed the larvae faster than control yeasts. Surface biotinylated extracts of Ac exhibited intense fungal binding by FACS and fluorescence microscopy. Binding was also intense to mannose, and mass spectrometry identified Ac proteins with affinity to fungal surfaces including two putative transmembrane mannose‐binding proteins (MBP, L8WXW7 and MBP1, Q6J288). Consistent with interactions with such mannose‐binding proteins, Ac–fungi interactions were inhibited by mannose. These MBPs may be involved in fungal recognition by amoeba and promotes interactions that allow the emergence and maintenance of fungal virulence for animals. 相似文献
7.
Reinaldo Farias Paiva de Lucena Elcida de Lima Araújo Ulysses Paulino de Albuquerque 《Economic botany》2007,61(4):347-361
This study investigated the use of woody plants by a rural community in an area of dry land Caatinga vegetation in northeastern Brazil. Information was obtained concerning this woody species with a diameter that is equal to or greater than 3 centimeters (cm) at soil level surveyed in 100 sample plots totaling 1 hectare (ha). The following question is the hypothesis we tested. Is a plant’s relative importance (as measured by its use value) related to its “apparency,” as measured by its abundance and ecological dominance? “Apparency” explains the use value of plants in four categories: medicinal, construction, fuel, and technology. The most important uses of woody plants are related to harvesting for energy and construction purposes. 相似文献
8.
Rocha DD Dantas IN Albuquerque MR Montenegro RC Pessoa C de Moraes MO Pessoa OD Silveira ER Costa-Lotufo LV 《化学与生物多样性》2007,4(12):2835-2844
A detailed study on the cytotoxic effects of five known constituents isolated from the flowers and roots of Eupatorium betonicaeforme is reported, including 2,2-dimethyl-6-vinylchroman-4-one (1), 2-senecioyl-4-vinylphenol (2), 6-acetyl-2,2-dimethylchroman-4-one (3), (4E)-8beta-angeloyloxy-9beta,10beta-dihydroxy-1-oxogermacra-4,11(13)-dien-12,6alpha-olide (4), and 3beta-hydroxyicosan-1,5beta-olide (5). The sesquiterpene lactone 4 exhibited the highest cytotoxicity, with IC50 values ranging from 3.9 to 9.9 microM, showing some degree of cell selectivity. The antiproliferative activity of 4 was examined towards HL-60 cells, and found to diminish cell viability in a dose-dependent manner. Moreover, at all concentrations tested, there was a decrease in the number of cells capable of incorporating 5-bromo-2'-deoxyuridine (BrdU), indicating disruption of DNA synthesis. The morphological changes induced by 4 were compatible with apoptotic cell death. This work, thus, corroborates the anticancer potential of Eupatorium secondary metabolites. 相似文献
9.
10.
Campos Juliana Loureiro Almeida de Lima Araújo Elcida Gaoue Orou G. Albuquerque Ulysses Paulino 《Economic botany》2019,73(2):187-199
Economic Botany - Socioeconomic Factors and Cultural Changes Explain the Knowledge and Use of Ouricuri Palm (Syagrus coronata) by the Fulni–ô Indigenous People of Northeast... 相似文献