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Introduction: The impact of asymptomatic infection by SARs-CoV-2 on foetal growth has not been described. The purpose of our study is to determine whether there is an increased risk of foetal growth restriction in pregnancies in which asymptomatic or mild infection by SARS-CoV-2 has been detected. Material and methods: Retrospective case-control study with a subset of pregnant women with a small for gestational age foetus. Groups were established according to birth weight percentile. Previous SARS-CoV-2 infection was defined by positive antibodies obtained on admission to hospital for delivery. Results: No statistically significant differences between controls and cases were recorded in terms of positive IgG antibodies (11.5 vs. 8.8%). There were no premature births or significant differences in the date or type of delivery. Conclusions: Asymptomatic infection by SARs-CoV-2 during pregnancy does not seem to affect foetal growth.
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Clinical history: An outbreak of intense pruritus and weight loss in a herd of 40 alpacas (Vicugna pacos) in the south-west of France was investigated after the death of 14 adults. One alpaca was referred to a veterinary teaching hospital for diagnosis and treatment but died soon after and one of the dead alpacas was submitted for necropsy. Clinical findings: The remaining alpacas were intensely pruritic with variably severe and extensive alopecia, erythema, lichenification and crusting on the face, ventral abdomen and distal limbs. Superficial skin scrapes from five animals revealed large numbers of Sarcoptes scabiei mites, and less frequent and numerous Chorioptes bovis mites. Coproscopic examinations revealed a median of 1,350 (min 500, max 8800) strongyle epg. The alpaca admitted for treatment was anaemic and hypoalbuminaemic. Skin scrapes revealed copious S. scabiei and C. bovis mites. The two alpacas examined post-mortem had similar skin lesions to those examined on-farm and were cachexic. One had lung lesions attributed to protostrongylid infestation and its liver contained numerous Dicrocoelium spp. adults. Diagnosis: Sarcoptic and chorioptic mange with secondary superficial bacterial skin infection, associated with severe internal parasitism and underfeeding. Treatment and outcome: All 25 alpacas were treated topically with a 3% chlorhexidine shampoo followed by a 0.025% amitraz wash at the initial visit and then 1, 2, 3, 7 and 9 weeks later. A systemic treatment with S/C 500â µg/kg ivermectin was administered at the initial visit and then 2, 7 and 9 weeks later. The alpacas were treated orally with 50â mg/kg praziquantel to control dicrocoeliosis. Nutritional measures, including increased pasture area and supplemental feeding were simultaneously implemented. Pruritus was reduced 1 week after the start of treatment and had resolved after 2 weeks. After 9 weeks, skin lesions were markedly improved. Six months after the initial visit, skin lesions entirely resolved and superficial skin scrapes, taken from half of the animals, were negative for mites. Clinical relevance: This is the first report of the use of two acaricides combined with a chlorhexidine shampoo to successfully treat simultaneous sarcoptic and chorioptic mange in alpacas.
Assuntos
Camelídeos Americanos/parasitologia , Inseticidas/uso terapêutico , Ivermectina/uso terapêutico , Escabiose/veterinária , Toluidinas/uso terapêutico , Administração Tópica , Animais , Anti-Helmínticos/uso terapêutico , Anti-Infecciosos Locais/uso terapêutico , Clorexidina/administração & dosagem , Clorexidina/uso terapêutico , Dicrocelíase/tratamento farmacológico , Dicrocelíase/veterinária , Quimioterapia Combinada , Feminino , Injeções Subcutâneas/veterinária , Inseticidas/administração & dosagem , Ivermectina/administração & dosagem , Masculino , Praziquantel/uso terapêutico , Escabiose/tratamento farmacológico , Escabiose/parasitologia , Toluidinas/administração & dosagemRESUMO
A room temperature benzene and formaldehyde gas sensor system with an ionogel as sensing material is presented. The sensing layer is fabricated employing poly(N-isopropylacrylamide) polymerized in the presence of 1-ethyl-3-methylimidazolium ethyl sulfate ionic liquid onto gold interdigitated electrodes. When the ionogel is exposed to increasing formaldehyde concentrations employing N2 as a carrier gas, a more stable response is observed in comparison to the bare ionic liquid, but no difference in sensitivity occurs. On the other hand, when air is used as carrier gas the sensitivity of the system towards formaldehyde is decreased by one order of magnitude. At room temperature, the proposed sensor exhibited in air higher sensitivities to benzene, at concentrations ranging between 4 and 20 ppm resulting, in a limit of detection of 47 ppb, which is below the standard permitted concentrations. The selectivity of the IL towards HCHO and C6H6 is demonstrated by the absence of response when another IL is employed. Humidity from the ambient air slightly affects the resistance of the system proving the protective role of the polymeric matrix. Furthermore, the gas sensor system showed fast response/recovery times considering the thickness of the material, suggesting that ionogel materials can be used as novel and highly efficient volatile organic compounds sensors operating at room temperature.Graphical abstract.
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Benzeno/análise , Formaldeído/análise , Géis/química , Imidazóis/química , Temperatura , Resinas Acrílicas/química , Eletrodos , Limite de Detecção , Compostos Orgânicos Voláteis/análiseRESUMO
Phosphoinositides are phosphatidylinositol derived, well known to be second messengers in various cell signaling pathways as well as in processes such as cell differentiation, cellular stress response, gene transcription, and chromatin remodeling. The pleckstrin homology domain of phospholipase C-delta 1 is responsible for recognizing and binding to PI(4,5)P2 and for this reason has been widely used to study this phosphoinositide as a biosensor when it is conjugated to a fluorescent tag. In this work, we modified the primary structure of pleckstrin homology domain by site-specific mutagenesis to change the specificity for phosphoinositides. We obtained 3 mutants: K30A, W36F, and W36Y with different specificity to phosphoinositides. Mutant domain K30A recognized PI(4,5)P2 , PI(3,4,5)P3 , phosphatidic acid (PA), and weakly PI(3,5)P2 . Mutant domain W36F recognized all the phosphoinositides studied and the PA. Finally, mutant domain W36Y seemed to interact with PA and all the other phosphoinositides studied, except PI(3)P. The changes in recognition argue against a simple charge and nonpolar region model for these interactions and more in favor of a specific docking region with a specific recognition site. We conducted in silico modeling that explains the mechanisms behind the observed changes and showed that aromatic amino acids appear to play more important role, than previously thought, in the specificity of phospholipids' binding domains.
Assuntos
Aminoácidos Aromáticos/química , Domínios de Homologia à Plecstrina , Sequência de Aminoácidos , Animais , Modelos Moleculares , Mutagênese Sítio-Dirigida , Proteínas Mutantes/química , Proteínas Mutantes/metabolismo , Fosfatos de Fosfatidilinositol/metabolismo , Fosfolipase C delta/química , RatosRESUMO
Inhibition of cerebral amyloid beta-protein deposition seems to be an important target for Alzheimer's disease therapy. Amyloidogenesis could be inhibited by short synthetic peptides designed as beta-sheet breakers. Here we demonstrate a 5-residue peptide that inhibits amyloid beta-protein fibrillogenesis, disassembles preformed fibrils in vitro and prevents neuronal death induced by fibrils in cell culture. In addition, the beta-sheet breaker peptide significantly reduces amyloid beta-protein deposition in vivo and completely blocks the formation of amyloid fibrils in a rat brain model of amyloidosis. These findings may provide the basis for a new therapeutic approach to prevent amyloidosis in Alzheimer's disease.
Assuntos
Doença de Alzheimer/terapia , Peptídeos beta-Amiloides/metabolismo , Amiloidose/prevenção & controle , Encéfalo/metabolismo , Fragmentos de Peptídeos/metabolismo , Peptídeos/farmacologia , Peptídeos beta-Amiloides/farmacologia , Peptídeos beta-Amiloides/toxicidade , Animais , Modelos Animais de Doenças , Humanos , Masculino , Fragmentos de Peptídeos/farmacologia , Fragmentos de Peptídeos/toxicidade , Ratos , Ratos Endogâmicos F344 , Células Tumorais CultivadasRESUMO
Aerosol-assisted Chemical Vapor Deposition (AACVD) is a thermally activated CVD technique that uses micro-droplets as deposition precursors. An AACVD system with a custom-designed reaction chamber has been implemented to grow ZnO thin films using zinc chloride as a precursor. The present work aims to study the impact of the deposition parameters on the thin film, as well as the microstructure evolution and growth kinetics. Aerosol flow has an effect on the density of nucleation sites and on the grain size. The temperature affects the morphology of the grown ZnO, showing a preferential orientation along the c-axis for 350 °C, 375 °C and 400 °C substrate temperatures. The microstructural evolution and the growth kinetics are also presented. A different evolution behavior has been observed for 350 °C, where nucleation site density is the highest at the early stages and it decreases over time in contrast with the cases of 375 °C and 400 °C, where there is an initial increase and a subsequent decrease. The activation energy of the chemical reaction is 1.06 eV. The optical characterization of the material has been performed through reflection measurements showing a relationship between the spectrum and the ZnO film thickness. The electrical characterization has been done by means of an interdigital capacitor, with which it is possible to measure the grain and grain boundary resistance of the material. Both resistances are of the order of 105-106 Ω.
RESUMO
ZnO conductometric gas sensors have been widely studied due to their good sensitivity, cost-efficiency, long stability and simple fabrication. This work is focused on NO2 sensing, which is a toxic and irritating gas. The developed sensor consists of interdigitated electrodes covered by a ZnO sensing layer. ZnO has been grown by means of the aerosol assisted chemical vapor deposition technique and then nanostructured by laser interference lithography with a UV laser. The SEM and XRD results show vertically oriented growth of ZnO grains and a 2D periodic nanopatterning of the material with a period of 800 nm. Nanostructuring lowers the base resistance of the developed sensors and modifies the sensor response to NO2. Maximum sensitivity is obtained at 175 °C achieving a change of 600% in sensor resistance for 4 ppm NO2 versus a 400% change for the non-nanostructured material. However, the most relevant results have been obtained at temperatures below 125 °C. While the non-nanostructured material does not respond to NO2 at such low temperatures, nanostructured ZnO allows NO2 sensing even at room temperature. The room temperature sensing capability possibly derives from the increase of both the surface defects and the surface-to-volume ratio. The long stability and the gas sensing under humid conditions have also been tested, showing improvements of sensitivity for the nanostructured sensors.
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Actin is a well-known protein that has shown a myriad of activities in the cytoplasm. However, recent findings of actin involvement in nuclear processes are overwhelming. Actin complexes in the nucleus range from very dynamic chromatin-remodeling complexes to structural elements of the matrix with single partners known as actin-binding proteins (ABPs). This review summarizes the recent findings of actin-containing complexes in the nucleus. Particular attention is given to key processes like chromatin remodeling, transcription, DNA replication, nucleocytoplasmic transport and to actin roles in nuclear architecture. Understanding the mechanisms involving ABPs will definitely lead us to the principles of the regulation of gene expression performed via concerting nuclear and cytoplasmic processes.
Assuntos
Actinas/metabolismo , Núcleo Celular/metabolismo , Proteínas dos Microfilamentos/metabolismo , Actinas/química , Animais , Núcleo Celular/química , Reparo do DNA , Replicação do DNA , Humanos , Proteínas dos Microfilamentos/química , Modelos BiológicosRESUMO
Canine haircoat quality, the time course of incorporation of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) into the canine erythrocyte membrane, changes in total lipids content on hair shafts and of neutral lipids on the skin surface, were investigated after administrating an n-3 fatty acids supplement. Twenty-four dogs with poor haircoat received a placebo or n-3 oil capsules (110 mg EPA/68 mg DHA) daily for 90 days. Clinical assessments and tissue sampling were performed monthly from day (D)0 to D180. The clinical score in treated dogs was significantly reduced from D60, then attained a plateau and returned to baseline levels on D180. EPA and DHA contents in the erythrocyte membrane increased significantly from D30 and decreased rapidly after supplement withdrawal in treated dogs. Total lipids on the hair shaft increased progressively in the supplemented group. EPA/DHA supplements impact blood and hair fatty acids important for haircoat quality in dogs.
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Pelo Animal/metabolismo , Suplementos Nutricionais , Membrana Eritrocítica/metabolismo , Ácidos Graxos Ômega-3/farmacologia , Pele/metabolismo , Animais , Cães , Método Duplo-Cego , Feminino , Masculino , Estudos ProspectivosRESUMO
We characterized dopamine toxicity in human neuroblastoma SH-SY5Y cells as a direct effect of dopamine on cell reductive power, measured as NADH and NADPH cell content. In cell incubations with 100 or 500 microM dopamine, the accumulation of dopamine inside the cell reached a maximum after 6 h. The decrease in cell viability was 40% and 75%, respectively, after 24 h, and was not altered by MAO inhibition with tranylcypromine. Dopamine was metabolized to DOPAC by mitochondrial MAO and, at 500 microM concentration, significantly reduced mitochondrial potential and oxygen consumption. This DA concentration caused only a slight increase in cell peroxidation in the absence of Fe(III), but a dramatic decrease in NADH and NADPH cell content and a concomitant decrease in total cell NAD(P)H/NAD(P)+ and GSH/GSSG and in mitochondrial NADH/NAD+ ratios. Dopaminechrome, a product of dopamine oxidation, was found to be a MAO-A inhibitor and a strong oxidizer of NADH and NADPH in a cell-free system. We conclude that dopamine may affect NADH and NADPH oxidation directly. When the intracellular concentrations of NAD(P)H and oxidized dopamine are similar, NAD(P)H triggers a redox cycle with dopamine that leads to its own consumption. The time-course of NADH and NADPH oxidation by dopamine was assessed in cell-free assays: NAD(P)H concentration decreased at the same time as dopamine oxidation advanced. The break in cell redox equilibrium, not excluding the involvement of free oxygen radicals, could be sufficient to explain the toxicity of dopamine in dopaminergic neurons.
Assuntos
Dopamina/toxicidade , NADP/metabolismo , Ácido 3,4-Di-Hidroxifenilacético/farmacologia , Biomarcadores , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Humanos , Mitocôndrias/efeitos dos fármacos , Oxigênio/metabolismo , Timidina/metabolismoRESUMO
The retinoblastoma (pRB) family of proteins includes three proteins known to suppress growth of mammalian cells. Previously we had found that growth suppression by two of these proteins, p107 and p130, could result from the inhibition of associated cyclin-dependent kinases (cdks). One important unresolved issue, however, is the mechanism through which inhibition occurs. Here we present in vivo and in vitro evidence to suggest that p107 is a bona fide inhibitor of both cyclin A-cdk2 and cyclin E-cdk2 that exhibits an inhibitory constant (Ki) comparable to that of the cdk inhibitor p21/WAF1. In contrast, pRB is unable to inhibit cdks. Further reminiscent of p21, a second cyclin-binding site was mapped to the amino-terminal portions of p107 and p130. This amino-terminal domain is capable of inhibiting cyclin-cdk2 complexes, although it is not a potent substrate for these kinases. In contrast, a carboxy-terminal fragment of p107 that contains the previously identified cyclin-binding domain serves as an excellent kinase substrate although it is unable to inhibit either kinase. Clustered point mutations suggest that the amino-terminal domain is functionally important for cyclin binding and growth suppression. Moreover, peptides spanning the cyclin-binding region are capable of interfering with p107 binding to cyclin-cdk2 complexes and kinase inhibition. Our ability to distinguish between p107 and p130 as inhibitors rather than simple substrates suggests that these proteins may represent true inhibitors of cdks.
Assuntos
Quinases relacionadas a CDC2 e CDC28 , Ciclina A/metabolismo , Ciclina E/metabolismo , Proteínas Nucleares/química , Proteínas Nucleares/metabolismo , Animais , Sítios de Ligação , Ciclina A/antagonistas & inibidores , Ciclina E/antagonistas & inibidores , Quinase 2 Dependente de Ciclina , Inibidor de Quinase Dependente de Ciclina p21 , Quinases Ciclina-Dependentes/antagonistas & inibidores , Quinases Ciclina-Dependentes/metabolismo , Ciclinas/metabolismo , Feminino , Inibidores do Crescimento/química , Inibidores do Crescimento/metabolismo , Humanos , Cinética , Mutagênese Sítio-Dirigida , Osteossarcoma , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Recombinantes de Fusão/metabolismo , Proteína p107 Retinoblastoma-Like , Spodoptera , Transfecção , Células Tumorais Cultivadas , Neoplasias do Colo do ÚteroRESUMO
The self-assembly of two derivatives of KLVFF, a fragment Aß(16-20) of the amyloid beta (Aß) peptide, is investigated and recovery of viability of neuroblastoma cells exposed to Aß (1-42) is observed at sub-stoichiometric peptide concentrations. Fluorescence assays show that NH2-KLVFF-CONH2 undergoes hydrophobic collapse and amyloid formation at the same critical aggregation concentration (cac). In contrast, NH2-K(Boc)LVFF-CONH2 undergoes hydrophobic collapse at a low concentration, followed by amyloid formation at a higher cac. These findings are supported by the ß-sheet features observed by FTIR. Electrospray ionization mass spectrometry indicates that NH2-K(Boc)LVFF-CONH2 forms a significant population of oligomeric species above the cac. Cryo-TEM, used together with SAXS to determine fibril dimensions, shows that the length and degree of twisting of peptide fibrils seem to be influenced by the net peptide charge. Grazing incidence X-ray scattering from thin peptide films shows features of ß-sheet ordering for both peptides, along with evidence for lamellar ordering of NH2-KLVFF-CONH2. This work provides a comprehensive picture of the aggregation properties of these two KLVFF derivatives and shows their utility, in unaggregated form, in restoring the viability of neuroblastoma cells against Aß-induced toxicity.
Assuntos
Peptídeos beta-Amiloides/química , Peptídeos beta-Amiloides/metabolismo , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/metabolismo , Agregados Proteicos , Sequência de Aminoácidos , Peptídeos beta-Amiloides/farmacologia , Amiloidose/tratamento farmacológico , Amiloidose/metabolismo , Amiloidose/patologia , Animais , Sobrevivência Celular/efeitos dos fármacos , Estrutura Molecular , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Fragmentos de Peptídeos/farmacologia , Agregação Patológica de Proteínas/tratamento farmacológico , Agregação Patológica de Proteínas/metabolismo , Estrutura Secundária de Proteína , Ratos , Espectrometria de Massas por Ionização por Electrospray , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios XRESUMO
The high rate of glycolysis despite the presence of oxygen in tumor cells (Warburg effect) suggests an important role for this process in cell division. The glycolytic rate is dependent on the cellular concentration of fructose 2,6-bisphosphate (Fru-2,6-P2), which, in turn, is controlled by the bifunctional enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK-2). The ubiquitous PFK-2 isoenzyme (uPFK-2, alternatively named UBI2K5 or ACG) coded by the pfkfb3 gene is induced by different stimuli (serum, progesterone, insulin, hypoxia, etc.) and has the highest kinase/phosphatase activity ratio amongst all PFK-2 isoenzymes discovered to date, which is consistent with its role as a powerful activator of glycolysis. uPFK-2 is expressed in brain, placenta, transformed cells and proliferating cells. In the present work, we analyze the impact of small interfering RNA (siRNA)-induced silencing of uPFK-2 on the inhibition of cell proliferation. HeLa cells treated with uPFK-2 siRNA showed a decrease in uPFK-2 RNA levels measured at 24h. uPFK-2 protein levels were severely depleted at 48-72h when compared with cells treated with an unrelated siRNA, correlating with decreased glycolytic activity, Fru-2,6-P2, lactate and ATP concentrations. These metabolic changes led to reduced viability, cell-cycle delay and an increase in the population of apoptotic cells. Moreover, uPFK-2 suppression inhibited anchorage-independent growth. The results obtained highlight the importance of uPFK-2 on the regulation of glycolysis, on cell viability and proliferation and also on anchorage-independent growth. These data underscore the potential for uPFK-2 as an effective tumor therapeutic target.
Assuntos
Ciclo Celular/genética , Inativação Gênica , Glicólise/genética , Fosfofrutoquinase-2/antagonistas & inibidores , Fosfofrutoquinase-2/genética , Células HeLa , Humanos , RNA Mensageiro/antagonistas & inibidores , RNA Mensageiro/efeitos dos fármacos , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/farmacologiaRESUMO
A diverse group of biochemically distinct proteins give rise to amyloids, each of which is associated with a different disease. These amyloid proteins share numerous properties and typically arise from the abnormal processing of an amyloid precursor protein. The classification, mechanisms and biochemistry of amyloid fibril formation are reviewed here, and two inherited types of amyloid affecting the nervous system are described.
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Amiloide/metabolismo , Amiloidose/genética , Sistema Nervoso/metabolismo , Amiloide/biossíntese , Amiloide/genética , Amiloidose/metabolismo , Animais , HumanosRESUMO
Transcriptional regulation depends on the appropriate set of positive and negative signals that provide correct gene expression. Studies in eukaryotic gene expression have shown NC2 to be a general repressor of transcription which blocks the interaction between TFIIB and TBP. However, during the last few years NC2 has been found to bind the transcriptionally active promoters and interact with several positive transcription factors. These data suggested a controversial role of NC2 in transcription. Using in vitro transcription on minimal LTR promoter of HIV-1, we show that removal of NC2 from HeLa nuclear extract increases the yield of transcripts as well as unspecific transcription initiation in a template amount dependent manner. Fractions of HeLa nuclear extract containing NC2 can restore basal transcription repression and precise selection of transcription initiation point. This points to a new role for NC2 as a repressor of inaccurate transcription initiation that allows specific transcription to take place.
Assuntos
Regulação da Expressão Gênica , Fosfoproteínas/metabolismo , Regiões Promotoras Genéticas , Fatores de Transcrição/metabolismo , Transcrição Gênica , Animais , Sistema Livre de Células/metabolismo , Células HeLa , Humanos , Fosfoproteínas/genética , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Fatores de Transcrição/genéticaRESUMO
We analyzed the influence of presenilins on the genetic cascades that control neuronal differentiation in Xenopus embryos. Resembling sonic hedgehog (shh) overexpression, presenilin mRNA injection reduced the number of N-tubulin+ primary neurons and modulated Gli3 and Zic2 according to their roles in activating and repressing primary neurogenesis, respectively. Presenilin increased shh expression within its normal domain, mainly in the floor plate, whereas an antisense X-presenilin-alpha morpholino oligonucleotide reduced shh expression. Both shh and presenilin promoted cell proliferation and apoptosis, but the effects of shh were widely distributed, while those resulting from presenilin injection coincided with the range of shh signaling. We suggest that presenilin may modulate primary neurogenesis, proliferation, and apoptosis in the neural plate, through the enhancement of shh signaling.
Assuntos
Proteínas de Membrana/genética , Proteínas do Tecido Nervoso , Neurônios/citologia , Proteínas Repressoras , Transativadores/genética , Proteínas de Xenopus , Xenopus laevis/embriologia , Secretases da Proteína Precursora do Amiloide , Animais , Apoptose , Ácido Aspártico Endopeptidases , Diferenciação Celular , Divisão Celular , Sistema Nervoso Central/embriologia , Proteínas de Ligação a DNA/genética , Regulação para Baixo , Embrião não Mamífero/citologia , Embrião não Mamífero/metabolismo , Endopeptidases/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Proteínas Hedgehog , Hibridização In Situ , Fatores de Transcrição Kruppel-Like , Proteínas de Membrana/fisiologia , Mutagênese Sítio-Dirigida , Oligonucleotídeos Antissenso , Presenilina-1 , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transdução de Sinais , Transativadores/fisiologia , Fatores de Transcrição/genética , Tretinoína/farmacologia , Tubulina (Proteína)/genética , Tubulina (Proteína)/metabolismo , Xenopus laevis/genética , Xenopus laevis/metabolismo , Proteína Gli3 com Dedos de ZincoRESUMO
Estriol acts as a weak estrogen when administered in a single dose into immature or ovariectomized laboratory animals, but produces full estrogenic responses upon chronic administration. However, when estriol is injected together with estradiol it acts as an antiestrogen. We studied the dual agonist/antagonist properties of estriol, using recombinant human estrogen receptor (hER) in ligand-binding assay, cell-free transcription assay, electrophoretic mobility shift assay with cVitII estrogen response element (ERE), and ERE-Sepharose chromatography. We show that the weak estrogenic activity of estriol results from impaired hER-ERE interaction. The antiestrogenic activity of estriol was demonstrated in a cell-free transcription assay where it reduced estradiol-dependent transcription in a dose-dependent manner. Estriol interfered with estradiol-induced positive cooperative binding and receptor dimerization, and binding of hER complexes to ERE. These effects of estriol were maximal at a 10-fold molar excess over estradiol; under these conditions estradiol-dependent transcription was decreased by 85%, although [3H]estradiol binding was reduced by only 50%. We propose that when hER, estradiol, and estriol are coequilibrated, several receptor species are formed: unliganded hER monomers and dimers; estradiol-hER monomers and dimers, estriol-hER monomers and dimers; and presumably mixed estradiol-estriol dimers. Since estrogen-hER complexes bind cooperatively to ERE sequences, the concentrations of transcriptionally active complexes (estriol- and estradiol-hER dimers) are reduced to low levels that fail to bind cooperatively with ERE and initiate transcription. We discuss our results in relation to the massive estriol production during pregnancy and to the "Estriol Hypothesis" on the protective role for estriol in opposing carcinogenic effects of estradiol.
Assuntos
Estriol/metabolismo , Estriol/farmacologia , Receptores de Estrogênio/agonistas , Receptores de Estrogênio/antagonistas & inibidores , Sistema Livre de Células , Estradiol/metabolismo , Estradiol/farmacologia , Humanos , Cinética , Ligação Proteica/efeitos dos fármacos , Receptores de Estrogênio/efeitos dos fármacos , Sequências Reguladoras de Ácido Nucleico/efeitos dos fármacos , Sequências Reguladoras de Ácido Nucleico/fisiologia , Ativação Transcricional/efeitos dos fármacosRESUMO
We study the effect of left-right symmetry on the distribution of the parametric derivative of the dimensionless conductance T with respect to an external parameter X , partial differentialT/ partial differentialX , of ballistic chaotic cavities with two leads, each supporting N propagating modes. We show that T and partial differentialT/ partial differentialX are linearly uncorrelated for any N . For N=1 we calculate the distribution of partial differentialT/ partial differentialX in the presence and absence of time-reversal invariance. In both cases, it has a logarithmic singularity at zero derivative and algebraic tails with an exponent different from the one of the asymmetric case. We also obtain explicit analytical results for the mean and variance of the distribution of partial differentialT/ partial differentialX for arbitrary N . Numerical simulations are performed for N=5 and 10 to show that the distribution P ( partial differentialT/ partial differentialX) tends towards a Gaussian one when N increases.
RESUMO
A method to discriminate virgin olive oil from other edible vegetable oils such as, sunflower, pomace olive, rapeseed, canola, corn and soybean, applying chemometric techniques to the liquid chromatographic representative fingerprint of sterols fraction, is proposed. After a pre-treatment of the LC chromatogram data - including baseline correction, smoothing signal and mean centering - different unsupervised and supervised pattern recognition procedures, such as principal component analysis (PCA), hierarchical cluster analysis (HCA), and partial least squares-discriminant analysis (PLSDA), have been applied. From the information obtained from PCA and HCA, two groups can be clearly distinguished (virgin olive and the rest of vegetable oils tested) which have been used to discriminate between two defined classes by means of a PLSDA model. Five latent variables (LVs) explained 76.88% of X-block variance and 95.47% of the defined classes block (γ-block) variance. A root mean square error for calibration and cross validation of 0.10 and 0.22 respectively, confirmed these results and a root mean square error for prediction of 0.15 evidences that the classification model proposed presents an adequate prediction capability. The contingency table also shows the good performance of the model, proving the capability of the LC-R-FpM, to discriminate virgin olive from other vegetable edible oils.
Assuntos
Olea , Óleos de Plantas/química , Esteróis/análise , Calibragem , Cromatografia Líquida de Alta Pressão , Análise Discriminante , Análise dos Mínimos Quadrados , Azeite de Oliva , Análise de Componente PrincipalRESUMO
Apolipoprotein E (apoE) has been found in association with several different types of systemic and cerebral amyloid deposits and the presence of the epsilon 4 allele constitutes a risk factor for Alzheimer's disease. It has been shown that apoE binds and promotes the fibrillogenesis in vitro of Alzheimer's amyloid beta-peptide, suggesting an important role for apoE in the modulation of amyloidogenesis. Due to the co-localization of apoE with several biochemically distinct amyloid deposits, it has been proposed that apoE plays a general role modulating and/or participating in amyloidosis. In the present study, we show for the first time that apoE, isolated from human plasma, increases fibril formation of synthetic peptides comprising the amyloidogenic sequences of gelsolin amyloid related to familial amyloidosis Finnish type, and amyloid A found in secondary amyloidosis and familial Mediterranean fever. Our results suggest that apoE acts as a general pathological chaperone in various amyloidoses by enhancing the transition from soluble peptides into amyloid-forming, pathological molecules.