Osvaldo Rivera - Academia.edu (original) (raw)

Papers by Osvaldo Rivera

Neuroscience Letters, 2010

Prenatal undernutrition induces hypertension later in life, possibly by disturbing the hypothalam... more Prenatal undernutrition induces hypertension later in life, possibly by disturbing the hypothalamopituitary-adrenal axis through programming decreased expression of hypothalamic glucocorticoid receptors. We examined the systolic blood pressure, heart rate and plasma corticosterone response to intra-paraventricular dexamethasone, mifepristone and corticosterone in eutrophic and prenatally undernourished young rats. Undernutrition was induced during fetal life by restricting the diet of pregnant mothers to 10 g daily (40% of diet consumed by well-nourished controls). At day 40 of postnatal life (i) intra-paraventricular administration of dexamethasone significantly reduced at least for 24 h both the systolic pressure (−11.6%), the heart rate (−20.8%) and the plasma corticosterone (−40.0%) in normal animals, while producing lower effects (−5.5, −8.7, and −22.3%, respectively) on undernourished rats; (ii) intra-paraventricular administration of the antiglucocorticoid receptor ligand mifepristone to normal rats produced opposite effects (8.2, 20.3, and 48.0% increase, respectively) to those induced by dexamethasone, being these not significant in undernourished animals; (iii) intra-paraventricular corticosterone did not exert any significant effect. Results suggest that the low sensitivity of paraventricular neurons to glucocorticoid receptor ligands observed in prenatally undernourished rats could be due to the already reported glucocorticoid receptor expression, found in the hypothalamus of undernourished animals.

En las ultimas decadas del siglo XX, el concepto de calidad surge con gran impacto en organizacio... more En las ultimas decadas del siglo XX, el concepto de calidad surge con gran impacto en organizaciones del ambito empresarial e industrial. Conforme avanzaron los anos y estas iniciativas se fueron difundiendo y popularizando, a la fecha han llegado a casi todos los sectores economicos; asi por ejemplo, este nuevo paradigma o cultura la encontramos en servicios financieros, educativos, politicos, de salud, organizacionales, administrativos, entre otros. Desde esta mirada, la lectura de esta obra nos permite reflexionar acerca de lo importante que es, como individuos y como sociedad, ser mas competentes en todos los ambitos de la vida. Ser una persona competente adquiere diferentes significados, la competencia humana general es el producto del dominio de conceptos, destrezas y actitudes; ser competente significa que la persona tiene el conocimiento declarativo; es decir, sabe lo que hace, por que lo hace y conoce el objeto sobre el que actua. Ser competente tambien implica, tener la ca...

Ciencia e investigación agraria, 1981

Journal of Comparative Physiology B, 2019

Obesity predisposes humans to a range of life-threatening comorbidities, including type 2 diabete... more Obesity predisposes humans to a range of life-threatening comorbidities, including type 2 diabetes and cardiovascular disease. Obesity also aggravates neural pathologies, such as Alzheimer's disease, but this class of comorbidity is less understood. When Drosophila melanogaster (flies) are exposed to high fat diet (HFD) by supplementing a standard medium with coconut oil, they adopt an obese phenotype of decreased lifespan, increased triglyceride storage, and hindered climbing ability. The latter development has been previously regarded as a potential indicator of neurological decline in fly models of neurodegenerative disease. Our objective was to establish the obesity phenotype in Drosophila and identify a potential correlation, if any, between obesity and neurological decline through behavioral assays and expression microarray. We found that mated female w 1118 flies exposed to HFD maintained an obese phenotype throughout adult life starting at seven days, evidenced by increased triglyceride stores, diminished life span, and impeded climbing ability. While climbing ability worsened between seven and fourteen days of exposure to HFD, there was no corresponding alteration in triglyceride content. Microarray analysis of the mated female w 1118 fly head revealed HFD-induced changes in expression of genes with functions in memory, metabolism, olfaction, mitosis, cell signaling, and motor function. Meanwhile, an Aversive Phototaxis Suppression assay in mated female flies indicated reduced ability to recall an entrained memory six hours after training. Overall, our results support the suitability of mated female flies for examining connections between diet-induced obesity and nervous or neurobehavioral pathology, and provide many directions for further investigation.

Molecular cell, Jan 18, 2018

DNA polymerase stalling activates the ATR checkpoint kinase, which in turn suppresses fork collap... more DNA polymerase stalling activates the ATR checkpoint kinase, which in turn suppresses fork collapse and breakage. Herein, we describe use of ATR inhibition (ATRi) as a means to identify genomic sites of problematic DNA replication in murine and human cells. Over 500 high-resolution ATR-dependent sites were ascertained using two distinct methods: replication protein A (RPA)-chromatin immunoprecipitation (ChIP) and breaks identified by TdT labeling (BrITL). The genomic feature most strongly associated with ATR dependence was repetitive DNA that exhibited high structure-forming potential. Repeats most reliant on ATR for stability included structure-forming microsatellites, inverted retroelement repeats, and quasi-palindromic AT-rich repeats. Notably, these distinct categories of repeats differed in the structures they formed and their ability to stimulate RPA accumulation and breakage, implying that the causes and character of replication fork collapse under ATR inhibition can vary in ...

American journal of physiology. Heart and circulatory physiology, 2018

After myocardial infarction, remodeling of the left ventricle involves a wound-healing orchestra ... more After myocardial infarction, remodeling of the left ventricle involves a wound-healing orchestra involving a variety of cell types. In order for wound healing to be optimal, appropriate communication must occur; these cells all need to come in at the right time, be activated at the right time in the right amount, and know when to exit at the right time. When this occurs, a new homeostasis is obtained within the infarct, such that infarct scar size and quality are sufficient to maintain left ventricular size and shape. The ideal scenario does not always occur in reality. Often, miscommunication can occur between infarct and remote spaces, across the temporal wound-healing spectrum, and across organs. When miscommunication occurs, adverse remodeling can progress to heart failure. This review discusses current knowledge gaps and recent development of the roles of inflammation and the extracellular matrix in myocardial infarction remodeling. In particular, the macrophage is one cell typ...

Methods in enzymology, 2018

Bacteriophage T4 encodes orthologs of the proteins Rad50 (gp46) and Mre11 (gp47), which form a he... more Bacteriophage T4 encodes orthologs of the proteins Rad50 (gp46) and Mre11 (gp47), which form a heterotetrameric complex (MR) that is responsible for host genome degradation and the processing of DNA ends for recombination-dependent DNA repair. In this chapter, we describe the ensemble methods currently employed by our laboratory to characterize the exonuclease activity of the T4 MR complex. DNA exonucleases play a vital role in maintaining the integrity of DNA through their participation in DNA repair pathways and as proofreaders for DNA polymerases. Methods for quantifying the general features of the exonuclease, and for determining steady-state kinetic parameters (K, k), the polarity of exonuclease activity, and processivity are presented. These methods should be applicable to all DNA exonucleases, and to some extent endonucleases.

G3 (Bethesda, Md.), Jan 15, 2017

Obesity has been shown to increase risk for cardiovascular disease and type-2 diabetes. In additi... more Obesity has been shown to increase risk for cardiovascular disease and type-2 diabetes. In addition, it has been implicated in aggravation of neurological conditions such as Alzheimer's. In the model organism Drosophila melanogaster, a physiological state mimicking diet-induced obesity can be induced by subjecting fruit flies to a solid medium disproportionately higher in sugar than protein or that has been supplemented with a rich source of saturated fat. These flies can exhibit increased circulating glucose levels, increased triglyceride content, insulin-like peptide resistance, and behavior indicative of neurological decline. We subjected flies to variants of the high-sugar diet, high-fat diet, or normal (control) diet, followed by a total RNA extraction from fly heads of each diet group for the purpose of Poly-A selected RNA-Sequencing. Our objective was to identify the effects of obesogenic diets on transcriptome patterns, how they differed between obesogenic diets, and ide...

Journal of Nanoparticle Research, 2015

Cadmium selenide quantum dots (CdSe QDs), inorganic semiconducting nanocrystals, are alluring inc... more Cadmium selenide quantum dots (CdSe QDs), inorganic semiconducting nanocrystals, are alluring increased attraction due to their highly refined chemistry, availability, and super tunable optical properties suitable for many applications in different research areas, such as photovoltaics, lightemitting devices, environmental sciences, and nanomedicine. Specifically, they are being widely used in bio-imaging in contrast to organic dyes due to their high brightness and improved photostability, and their ability to tune their absorption and emission spectra upon changing the crystal size. The production of CdSe QDs is mostly assisted by trioctylphosphine oxide compound, which acts as solvent or solubilizing agent and renders the QDs soluble in organic compounds (such as toluene, chloroform, and hexane) that are highly toxic. To circumvent the toxicity-related factor in CdSe QDs, we report the synthesis of CdSe QDs capped with thioglycolic acid (TGA) in an aqueous medium, and their biocompatibility in colo-205 cancer cells. In this study, the [Cd 2+ ]/ [TGA] ratio was adjusted to 11:1 and the Se concentration (10 and 15 mM) was monitored in order to evaluate its influence on the optical properties and cytocompatibility. QDs resulted to be quite stable in water (after purification) and RPMI cell medium and no precipitation was observed for long contact times, making them appealing for in vitro experiments. The spectroscopy analysis, advanced electron microscopy, and X-ray diffractometry studies indicate that the final products were successfully formed exhibiting an improved optical response. Colo-205 cells being exposed to different concentrations of TGA-capped CdSe QDs for 12, 24, and 48 h with doses ranging from 0.5 to 2.0 mM show high tolerance reaching cell viabilities as high as 93 %. No evidence of cellular apoptotic pathways was observed as pointed out by our Annexin V assays at higher concentrations. Moreover, confocal microscopy analysis conducted to evaluate the intracellular uptake of TGA-CdSe QDs reveal that the TGA-CdSe QDs were uniformly distributed within the cytosolic side of cell membranes. Our results also suggest that under controlled conditions, direct water-soluble TGA-CdSe QDs can be potentially employed for bio-imaging colo-205 cancer cells with minimal adverse effects.

min - Minimally Invasive Neurosurgery, 2006

The purpose of this work is to present our endoscopic neuroanatomical findings of a series of mye... more The purpose of this work is to present our endoscopic neuroanatomical findings of a series of myelomeningocele and hydrocephalus patients, treated with endoscopic third ventricular cisternostomy (ETVC), in order to describe ventricular configuration abnormalities in this group of patients, in which this neurosurgical procedure has limited performance. We checked the videos of 10 endoscopic third ventricular cisternostomies of myelomeningocele patients taken during 24 months as from December 1998. A previous guideline is designed to record anatomic variables in the lateral ventricles, IIIrd ventricle, and basal cisterns. The topic is analyzed in view of the necropsy and imaging background data. The ETVC of lateral ventricles showed: absence of septum (9/10); absence of anteroseptal vein (8/10); absence of choroid plexus and thalamostriate vein (0/10); absence of fornix (1/10): small foramen of Monro (4/10). The ETVC of the IIIrd ventricle showed: impossibility of recognizing any mammillary bodies (4/10); presence of septations (5/10); presence of atypical veins in the floor (6/10); translucent floor (5/10); floor umbilications (5/10); absence of infundibulum (4/10); arachnoid adherences (7/10); and visual contact of basilar artery (4/10). There are categorical structural alterations in the ventricular system of myelomeningocele patients that are well correlated with previous necropsy and imaging reports. The ventricular system of dysraphic children presents severe anatomic alterations, which alter the reference points of the classical endoscopic third ventricular cisternostomy.

Advanced Measurement and Ground Testing Conference, 1996

Enhancing wind tunnel test productivity in terms of increased efficiency, reduced cost, and expan... more Enhancing wind tunnel test productivity in terms of increased efficiency, reduced cost, and expanded flexi bility is a high-priority goal of the NASA Lewis Research Center's Aeropropulsion Facilities and Experiments Division. Over the past several years, several significant productivity improvements were implemented: test times were shortened by using facility and test article automation; additional flexibility was provided to the research customer by using the remote-access control room and by expanding facility operating envelopes; facility throughput was greatly increased and electric power cost for facility operation reduced by using the three-shift operation. One method being used to reduce electric power costs and expand the facility operating envelop in the 8-by 6-Foot Supersonic Wind Tunnel is operating the drive system with only one of the three drive motors. Metrics are being used to document several categories of facility utilization, which in tum allows tracking of test productivity. This paper provides an overview of the productivity improvements already in place in the large wind tunnels at NASA Lewis and presents plans for future improvements. Form Approved OMB N o. 0704-01 88 Public reporting burden for this collection of information is estimated to average 1 hour per res ponse, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed , and completing and reviewi ng the collecti on of information. Send comments regarding this burden estimate or any other aspect of th is collection of information, including suggestions for reducing this burden , to Washington Headquarters Services, Directorate for Information Operations and Reports , 1215 Jefferson