Papers by Rodrigo Sandoval
BMC Public Health, 2015
Health effects of pesticides are easily diagnosed when acute poisonings occurs, nevertheless, con... more Health effects of pesticides are easily diagnosed when acute poisonings occurs, nevertheless, consequences from chronic exposure can only be observed when neuropsychiatric, neurodegenerative or oncologic pathologies appear. Therefore, early monitoring of this type of exposure is especially relevant to avoid the consequences of pathologies previously described; especially concerning workers exposed to pesticides on the job. For acute organophosphate pesticides (OPP) exposure, two biomarkers have been validated: plasma cholinesterase (ChE) and acetylcholinesterase (AChE) from erythrocytes. These enzymes become inhibited when people are exposed to high doses of organophosphate pesticides, along with clear signs and symptoms of acute poisoning; therefore, they do not serve to identify risk from chronic exposure. This study aims to assess a novel biomarker that could reflect neuropsychological deterioration associated with long-term exposure to organophosphate pesticides via the enzyme acylpeptide-hydrolase (ACPH), which has been recently identified as a direct target of action for some organophosphate compounds.
Epilepsia, 2003
Purpose: To study seizure-induced changes in signaling proteins present in postsynaptic densities... more Purpose: To study seizure-induced changes in signaling proteins present in postsynaptic densities (PSDs) isolated from human epileptic neocortex and from rat cortex in which seizures were induced by injection of kainic acid.
Columbia University/New York-Presbyterian Hospital: improving access to renal transplantation
Clinical transplants, 2010
There continues to be an increasing disparity between organ supply and demand in kidney transplan... more There continues to be an increasing disparity between organ supply and demand in kidney transplantation with over 87,000 patients currently on the waiting list. Prolonged waiting times on dialysis is associated with significant morbidity and mortality rates. At Columbia University Medical Center/New York-Presbyterian Hospital we have implemented several strategies to improve access to transplantation. Here we present these key steps that have resulted in a significant reduction in our median waiting times and successfully increased the rate of transplantation at our center.
Frontiers in cellular neuroscience, 2013
† These authors have contributed equally to this work.
EX VIVO RESECTION AND AUTOTRANSPLANTATION FOR LOCALLY INVASIVE TUMORS INVOLVING MAJOR VASCULAR PEDICLES: 3023
Transplantation, 2010
COMPARISON OF SELECTIVE URETERAL STENTING TO UNIVERSAL STENTING DURING THE CREATION OF THE URETERONEOCYSTOSTOMY A SINGLE CENTER EXPERIENCE: 1448
Transplantation, 2010
Biochemical and Biophysical Research Communications, 2004
Protein kinase CK2 (CK2) is highly expressed in rat forebrain where its function is not well unde... more Protein kinase CK2 (CK2) is highly expressed in rat forebrain where its function is not well understood. Subcellular distribution studies showed that the catalytic subunit of CK2 (CK2α) was enriched in postsynaptic densities (PSDs) by 68%. We studied the putative role of CK2 activity on N-methyl-d-aspartate receptor (NMDAR) function using isolated, patch-clamped PSDs in the presence of 2 mM extracellular Mg2+. The usual activation by phosphorylation of the NMDARs in the presence of ATP was inhibited by the selective CK2 inhibitor 5,6-dichloro-1-β-ribofuranosyl benzimidazole (DRB). This inhibition was voltage-dependent, i.e., 100% at positive membrane potentials, while at negative potentials, inhibition was incomplete. Endogenous CK2 substrates were characterized by their ability to use GTP as a phosphoryl donor and susceptibility to inhibition by DRB. Immunoprecipitation assays and 2D gels indicated that PSD-95/SAP90, the NMDAR scaffolding protein, was a CK2 substrate, while the NR2A/B and NR1 NMDAR subunits were not. These results suggest that postsynaptic NMDAR regulation by CK2 is mediated by indirect mechanisms possibly involving PSD-95/SAP90.
Toxicology and Applied Pharmacology, 2009
Dichlorvos is the active molecule of the pro-drug metrifonate used to revert the cognitive defici... more Dichlorvos is the active molecule of the pro-drug metrifonate used to revert the cognitive deficits associated with Alzheimer's disease. A few years ago it was reported that dichlorvos inhibits the enzyme acylpeptide hydrolase at lower doses than those necessary to inhibit acetylcholinesterase to the same extent. Therefore, the aim of our investigation was to test the hypothesis that dichlorvos can enhance synaptic efficacy through a mechanism that involves acylpeptide hydrolase instead of acetylcholinesterase inhibition. We used long-term potentiation induced in rat hippocampal slices as a model of synaptic plasticity. Our results indicate that short-term exposures (20 min) to 50 μM dichlorvos enhance long-term potentiation in about 200% compared to the control condition. This effect is correlated with approximately 60% inhibition of acylpeptide hydrolase activity, whereas acetylcholinesterase activity remains unaffected. Paired-pulse facilitation and inhibition experiments indicate that dichlorvos does not have any presynaptic effect in the CA3 → CA1 pathway nor affect gabaergic interneurons. Interestingly, the application of 100 nM methyllicaconitine, an α7 nicotinic receptor antagonist, blocked the enhancing effect of dichlorvos on long-term potentiation. These results indicate that under the exposure conditions described above, dichlorvos enhances long-term potentiation through a postsynaptic mechanism that involves (a) the inhibition of the enzyme acylpeptide hydrolase and (b) the modulation of α7 nicotinic receptors.
Neuroscience Letters, 2012
Synaptic localization of ACPH was studied. Pre-and post-synaptic components were isolated from ra... more Synaptic localization of ACPH was studied. Pre-and post-synaptic components were isolated from rat brain. ACPH activity and protein levels were measured. We demonstrated the presence of active ACPH in pre-synaptic components. We provide new insights on the localization and the role of ACPH in the CNS.
Brain Research, 2007
Induction of status epilepticus (SE) with kainic acid results in a large reorganization of neuron... more Induction of status epilepticus (SE) with kainic acid results in a large reorganization of neuronal brain circuits, a phenomenon that has been studied primarily in the hippocampus. The neurotrophin BDNF, by acting through its receptor TrkB, has been implicated in such reorganization. In the present work we investigated, by Western blot and immunohistochemistry, whether regional changes of TrkB expression within the rat brain cortex are correlated with altered neuronal morphology and/or with apoptotic cell death. We found that the full-length TrkB protein decreased within the cortex when measured 24 h to 1 week after induction of SE. Analysis by immunohistochemistry revealed that TrkB staining diminished within layer V of the retrosplenial granular b (RSGb) and motor cortices, but not within the auditory cortex. In layer II/III, differential changes were also observed: TrkB decreased in the motor cortex, did not change within the RSGb but increased within the auditory cortex. Reduced TrkB was associated with dendritic atrophy and decreased spine density in pyramidal neurons within layer V of the RSGb. No correlation was observed between regional and cellular changes of TrkB protein and apoptosis, measured by the TdT-mediated dUTP nick end labeling (TUNEL) method. The global decrease of TrkB within the neocortex and the associated dendritic atrophy may counteract seizure propagation in the epileptic brain but may also underlie cognitive impairment after seizures.
Brain Research, 2007
Induction of status epilepticus (SE) with kainic acid results in a large reorganization of neuron... more Induction of status epilepticus (SE) with kainic acid results in a large reorganization of neuronal brain circuits, a phenomenon that has been studied primarily in the hippocampus.
Biochemical and Biophysical Research Communications, 2004
Protein kinase CK2 (CK2) is highly expressed in rat forebrain where its function is not well unde... more Protein kinase CK2 (CK2) is highly expressed in rat forebrain where its function is not well understood. Subcellular distribution studies showed that the catalytic subunit of CK2 (CK2a) was enriched in postsynaptic densities (PSDs) by 68%. We studied the putative role of CK2 activity on N-methyl-D D-aspartate receptor (NMDAR) function using isolated, patch-clamped PSDs in the presence of 2 mM extracellular Mg 2+ . The usual activation by phosphorylation of the NMDARs in the presence of ATP was inhibited by the selective CK2 inhibitor 5,6-dichloro-1-b-ribofuranosyl benzimidazole (DRB). This inhibition was voltage-dependent, i.e., 100% at positive membrane potentials, while at negative potentials, inhibition was incomplete. Endogenous CK2 substrates were characterized by their ability to use GTP as a phosphoryl donor and susceptibility to inhibition by DRB. Immunoprecipitation assays and 2D gels indicated that PSD-95/SAP90, the NMDAR scaffolding protein, was a CK2 substrate, while the NR2A/B and NR1 NMDAR subunits were not. These results suggest that postsynaptic NMDAR regulation by CK2 is mediated by indirect mechanisms possibly involving PSD-95/SAP90.
Gender Equality and International Human Rights in Costa Rican Constitutional Jurisprudence
The Gender of Constitutional Jurisprudence, 2004
El desarrollo y la movilidad ocupacional de los sectores medios en Colombia
Revista Mexicana de Sociología, 1971
Using a genetic algorithm for exploring a semiconductor fabrication model
2008 7th International Caribbean Conference on Devices, Circuits and Systems, 2008
Initial iterations or generations of this particular Genetic Algorithm (GA) implementation for op... more Initial iterations or generations of this particular Genetic Algorithm (GA) implementation for optimizing a semiconductor fabrication process, not only search for an optimal solution, but also, with the aid of a visual tool, help understanding the complex characteristics of the model. Finally, thanks to this visual analysis, some adjustments are proposed to the algorithm execution in order to drive the search more effectively, as explained using a reference TCAD simulation-based example.
Monoamniotic twin pregnancy discordant for lethal open cranial defect: management dilemmas
Prenatal Diagnosis, 2011
To report the sonographic findings, prenatal courses, and management options in four cases of mon... more To report the sonographic findings, prenatal courses, and management options in four cases of monoamniotic twin pregnancy complicated by a discordant, lethal open cranial vault defect. Cases were collected from two Latin American fetal medicine referral centers after the sonographic detection of a monoamniotic twin pregnancy in which one fetus was structurally normal and the other had a lethal open cranial vault defect. Three abnormal fetuses had acrania-anencephaly sequence and one had a large occipital encephalocele. The diagnosis was confirmed at referral, at which time umbilical cord entanglement was also diagnosed with color Doppler ultrasound in all cases. Two cases were managed with selective termination, one of which required referral to a fetal surgery center abroad because this option was illegal in Chile. The other case underwent radiofrequency ablation of the fetal intra-abdominal umbilical vessels after the corresponding ethics and legal committees approved the procedure. In both cases, the non-anomalous twin was born after 35 weeks and had no perinatal complications. Expectant management was performed in the other two cases, resulting in the death of the normal twin at 25 weeks. Monoamniotic twin pregnancy discordant for severe cranial vault defect is a serious condition with a high risk of fetal demise of the structurally normal fetus. Our experience, although limited, suggests that aggressive management with selective termination of the abnormal twin and transection of its umbilical cord in these cases may prevent the demise of the structurally normal co-twin.
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Papers by Rodrigo Sandoval