1,721,012 research outputs found
Mass Spectrometry-Based Characterization of Posttranslational Modifications by 4-Hydroxy-2-Nonenal
No full textQuantitative Proteomic Investigation of Estrogenic Endocrine-Disrupting Effects in the Rat Uterus
No full textThe mammalian uterus is one of the most sensitive organs for estrogenicity. However, the widely used rat uterotrophic assay to assess known and potential estrogenic compounds only considers the uterine wet weight gain as an endpoint measurement. To complement this method with an advanced technology that reveals molecular targets, we analyzed changes in protein expression using label-free quantitative proteomic analysis by liquid chromatography–mass spectrometry from uterine protein extracts of ovariectomized rats after daily 17β-estradiol exposure for five days. We performed shotgun proteomic analysis of the uterus to identify candidate proteins for use as markers of estrogenicity. In addition, we mapped the differentially expressed proteins from untargeted analysis to signaling networks and biological processes through Ingenuity Pathway Analysis. We selected twelve of the top up- and down-regulated proteins for further evaluation by selected reaction monitoring-based targeted quantitation. Of the final six candidate markers, we verified all six as markers of estrogenicity by the application of the panel to testing rats exposed to a low and high dose of the known estrogenic compound bisphenol A. Altogether, the results of this study demonstrate the power of combining untargeted and targeted quantitative proteomic methods for a comprehensive analysis in rat uterus to evaluate changes in protein expression levels due to estrogen exposure, and to uncover candidate markers of estrogenicity in the development of a targeted proteomics panel
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Improving Brain Delivery of TRH: A Novel Prodrug Approach
No full textThe goal of my research project was to validate a novel prodrug design concept for the brain-enhanced delivery of an important neuropeptide, thyrotropin-releasing hormone (TRH, pGlu-His-Pro-NH2). TRH has a variety of clinically relevant central effects that cannot be utilized with the direct administration of TRH, due to intrinsic characteristics that give rise to metabolic instability and insufficient transport through the blood-brain barrier (BBB). Consequently, large doses are required to generate central effects, which concomitantly induces unwanted hormonal liabilities in the periphery. To overcome these caveats, the prodrug design described herein proposes a novel brain-targeting approach that synergistically utilizes two enzymes, both preferentially expressed in the brain, for the enhanced brain-delivery of TRH. The conjugation of a lipoamino acid (LAA) transport moiety to the N-terminus of a TRH progenitor sequence (Gln-His-Pro-NH2) via a prolyl oligopeptidase (POP)-sensitive linker allows the POP enzyme to release the TRH progenitor sequence at the site-of-action upon crossing the BBB, where it is further transformed by glutaminyl cyclase (QC). QC catalyzes Gln to form pGlu at the N-terminus of the progenitor sequence, thereby releasing TRH. I tested the hypothesis that a representative molecule, developed according to this prodrug design approach, would exhibit adequate drug-likeness for BBB penetration and efficacious release of TRH within the brain. Immobilized artificial membrane chromatography was used to predict the BBB penetration of this experimental prodrug, labeled “PRODRUG 1,” in addition to its calculated logP. Next, PRODRUG (1) was compared to TRH (the “parent” peptide) in an in vitro metabolic stability assessment, followed by an in vivo neuro-pharmacodynamical evaluation in rodents. The Porsolt swim test, PST, an established animal behavioral model that detects depressive-like behavior was used to confirm brain-delivery of prodrug-derived TRH after systemic administration of the prototype prodrug. Capitalizing on TRH’s antidepressant-like effect, the PST results were also used to validate the tail suspension test (TST), a new technique that I implemented in our laboratory for the evaluation of neuroactive compounds with potential antidepressant-like activity.
My findings support the extension of the TRH progenitor sequence from the N-terminus, through the conjugation of two LAA residues (each with a 10-carbon sidechain) via a single proline POP-sensitive linker, as a successful means to increase penetration across the BBB and sufficiently bind with cleaving and activating enzymes, POP and QC, respectively, for efficacious TRH release in the brain. Lastly, molecular modeling was used to create a library of similarly designed prodrugs to computationally assess their bindings with POP, the cleaving enzyme, to further explore the customizable prodrug design concept described here. Ultimately, this adaptable prodrug delivery model demonstrates the effectiveness of increased lipophilicity and site-of-action targeting to facilitate brain-enhanced delivery of TRH
Protein Biomakers of Estrogenic Impact on Mouse and Rat Uterus
No full textUnderstanding the structural and morphological impact that occur in the uterus upon exposure to estrogens can reveal how these hormones elicit changes in the organ. This study seeks to revalidate the data obtained in studies of ovariectomized mice and rats treated with 17β-estradiol, followed by comparative analysis of the protein expression between the two animal models (the mice model studied by Prokai et al. [1] and the rat model presented in a dissertation by Rahlouni [2]). During these studies, female Swiss-Webster mice and Sprague-Dawley rats were ovariectomized (OVX) and divided respectively into two groups: 1) The control was treated with a corn oil vehicle while 2) The treatment group received 17β-estradiol injection for 5 days. Raw data gathered from the earlier proteomics studies were reanalyzed using Maxquant version 1.6.17, which utilized extracted ion chromatography technique (XIC). LFQ analyst and Ingenuity Pathway Analysis (IPA) version 5.0 were used to identify proteins that were differentially regulated by 17β-estradiol and perform comparative analyses of the protein expression between OVX mice and rats. Reanalysis of OVX mice identified 59 proteins of interest at 95% confidence with 29 upregulated and 30 downregulated significantly. Reanalysis of the OVX rats identified 126 differentially expressed proteins at 95% confidence with 98 upregulated and 27 downregulated significantly. Comparative analysis using IPA® found 27 proteins unique to mice and 85 proteins unique to rats. Conversely, the OVX mice and rats shared 19 proteins regulated by 17β-estradiol in the uterus. Ingenuity Pathway Analysis® also created networks in OVX mouse and rat models showing a relationship with estrogen receptors in the nucleus, which can bind 17β-estradiol and then initiate gene transcription. Although there is overlap between OVX mice and rat protein expression, the proteins that were found to be unique to each animal demonstrate that a complementary model using both animals provides a much broader view of uterine protein expression in OVX animals treated with 17?-estradiol. Additionally, this study illustrates the merit of reanalyzing older data with improved computational and bioinformatic tools to pinpoint proteins of interest for future analysis as potential markers of estrogenic effects in the uterus
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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Revisiting the Neuroprotective Role of 17B-Estradiol (E2): A Multi-Omics Based Analysis of the Rat Brain and Serum
Get PDFThe ovarian hormone 17β-estradiol (E2) is one of the central regulators of the female reproductive system. E2 is also a pleiotropic regulator since it can exert its non-reproductive role on other organ systems. E2 is neuroprotective, it maintains body's energy homeostasis, participates in various repair mechanism and is required for neural development. However, there is a substantial evidence suggesting that there might be a molecular reprogramming of E2's action when it is supplied exogenously after E2 deprivation. Though the length of E2 deprivation and age has been linked to this phenomenon, the molecular components and how they activate this reprogramming is still elusive. Our main goal was to perform global proteomics and metabolomics study to identify the molecular components and their interaction networks that are being altered in the brain and serum after a short-term E2 treatment following ovariectomy (OVX) in Sprague Dawley rats. One of the strength of our global study is that it gave us extensive information on the brain proteome itself by identification of a wide number of proteins in different brain sections. By analyzing the differentially expressed proteins, our proteomics study revealed 49 different networks to be altered in 7 sections of the brain. Most of the perturbed networks were involved in cell metabolism, neural development, protein synthesis, cellular trafficking and degradation, and several stress response signaling pathways. We assessed the neuroenergetic status of the brain based on E2's response to various energy generating pathways, including glycolysis, TCA cycle, and oxidative phosphorylation, and several signaling pathways. All energetics pathways were shown to be downregulated in E2 treatment, which suggests that E2 exerts its neuroprotective role by restoring energy homeostasis in OVX rat model by regulating complex signaling and metabolic networks. Our second focus was to determine the metabolite response (amino acids and lipids) after E2 treatment in the brain and serum by employing targeted metabolomics study. We have found that in rat brain cortex there was significant upregulation of a wide number of amino acids suggesting alternate route of metabolism. Another alternate explanation is that E2 replacement replenished the amino acid pool in the tissue. Pathway enrichment analysis revealed upregulation of several pathways, including amino sugar metabolism, purine metabolism, and glutathione metabolism. By combining proteomics and metabolomics in two different biological matrices we were able to gather a vast array of information on how E2 replacement after E2 deprivation can confer neuroprotection. Our findings will help to create a foundation of basic science to be used for developing potentially effective hormone therapies
The impact of 17beta-estradiol on the estrogen-deficient female brain: from mechanisms to therapy with hot flushes as target symptoms
No full textSex steroids are essential for whole body development and functions. Among these steroids, 17beta-estradiol (E2) has been known as the principal female" hormone. However, E2's actions are not restricted to reproduction, as it plays a myriad of important roles throughout the body including the brain. In fact, this hormone also has profound effects on the female brain throughout the life span. The brain receives this gonadal hormone from the circulation, and local formation of E2 from testosterone via aromatase has been shown. Therefore, the brain appears to be not only a target but also a producer of this steroid. The beneficial broad actions of the hormone in the brain are the end result of well-orchestrated delayed genomic and rapid non-genomic responses. A drastic and steady decline in circulating E2 in a female occurs naturally over an extended period of time starting with the perimenopausal transition, as ovarian functions are gradually declining until the complete cessation of the menstrual cycle. The waning of endogenous E2 in the blood leads to an estrogen-deficient brain. This adversely impacts neural and behavioral functions and may lead to a constellation of maladies such as vasomotor symptoms with varying severity among women and, also, over time within an individual. Vasomotor symptoms triggered apparently by estrogen deficiency are related to abnormal changes in the hypothalamus particularly involving its preoptic and anterior areas. However, conventional hormone therapies to "re-estrogenize" the brain carry risks due to multiple confounding factors including unwanted hormonal exposure of the periphery. In this review, we focus on hot flushes as the archetypic manifestation of estrogen deprivation in the brain. Beyond our current mechanistic understanding of the symptoms, we highlight the arduous process and various obstacles of developing effective and safe therapies for hot flushes using E2. We discuss our preclinical efforts to constrain E2's beneficial actions to the brain by the DHED prodrug our laboratory developed to treat maladies associated with the hypoestrogenic brain."The author(s) declare financial support was received for the research, authorship, and/or publication of this article. The National Eye Institute, the Office of Research on Women's Health, and the National Cancer Institute (National Institutes of Health, Bethesda, MD, USA, grant numbers EY027005 to KP-T, and CA215550 to LP) and from the Robert A. Welch Foundation (endowment BK-0031 to LP)
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