Publications by authors named "Joaquín Peña"

34 Publications

Clinical validation of risk scoring systems to predict risk of delayed bleeding after EMR of large colorectal lesions.

Gastrointest Endosc 2020 04 23;91(4):868-878.e3. Epub 2019 Oct 23.

Hospital Universitario Virgen Macarena, Sevilla, Spain.

Background And Aims: The Endoscopic Resection Group of the Spanish Society of Endoscopy (GSEED-RE) model and the Australian Colonic Endoscopic Resection (ACER) model were proposed to predict delayed bleeding (DB) after EMR of large superficial colorectal lesions, but neither has been validated. We validated and updated these models.

Methods: A multicenter cohort study was performed in patients with nonpedunculated lesions ≥20 mm removed by EMR. We assessed the discrimination and calibration of the GSEED-RE and ACER models. Difficulty performing EMR was subjectively categorized as low, medium, or high. We created a new model, including factors associated with DB in 3 cohort studies.

Results: DB occurred in 45 of 1034 EMRs (4.5%); it was associated with proximal location (odds ratio [OR], 2.84; 95% confidence interval [CI], 1.31-6.16), antiplatelet agents (OR, 2.51; 95% CI, .99-6.34) or anticoagulants (OR, 4.54; 95% CI, 2.14-9.63), difficulty of EMR (OR, 3.23; 95% CI, 1.41-7.40), and comorbidity (OR, 2.11; 95% CI, .99-4.47). The GSEED-RE and ACER models did not accurately predict DB. Re-estimation and recalibration yielded acceptable results (GSEED-RE area under the curve [AUC], .64 [95% CI, .54-.74]; ACER AUC, .65 [95% CI, .57-.73]). We used lesion size, proximal location, comorbidity, and antiplatelet or anticoagulant therapy to generate a new model, the GSEED-RE2, which achieved higher AUC values (.69-.73; 95% CI, .59-.80) and exhibited lower susceptibility to changes among datasets.

Conclusions: The updated GSEED-RE and ACER models achieved acceptable prediction levels of DB. The GSEED-RE2 model may achieve better prediction results and could be used to guide the management of patients after validation by other external groups. (Clinical trial registration number: NCT03050333.).
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http://dx.doi.org/10.1016/j.gie.2019.10.013DOI Listing
April 2020

Clinical guidelines for endoscopic mucosal resection of non-pedunculated colorectal lesions.

Gastroenterol Hepatol 2018 Mar 12;41(3):175-190. Epub 2018 Feb 12.

Hospital Universitari i Politècnic La Fe, Valencia, España.

This document summarizes the contents of the Clinical Guidelines for the Endoscopic Mucosal Resection of Non-Pedunculated Colorectal Lesions that was developed by the working group of the Spanish Society of Digestive Endoscopy (GSEED of Endoscopic Resection). This document presents recommendations for the endoscopic management of superficial colorectal neoplastic lesions.
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http://dx.doi.org/10.1016/j.gastrohep.2017.08.013DOI Listing
March 2018

Clinical guidelines for endoscopic mucosal resection of non-pedunculated colorectal lesions.

Rev Esp Enferm Dig 2018 Mar;110(3):179-194

Digestive Endoscopy Unit. Gastoenterology, Hospital Universitari i Politècnic La Fe, España.

This document summarizes the contents of the Clinical Guidelines for the Endoscopic Mucosal Resection of Non-Pedunculated Colorectal Lesions that was developed by the working group of the Spanish Society of Digestive Endoscopy (GSEED of Endoscopic Resection). This document presents recommendations for the endoscopic management of superficial colorectal neoplastic lesions.
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http://dx.doi.org/10.17235/reed.2018.5086/2017DOI Listing
March 2018

A Scoring System to Determine Risk of Delayed Bleeding After Endoscopic Mucosal Resection of Large Colorectal Lesions.

Clin Gastroenterol Hepatol 2016 08 24;14(8):1140-7. Epub 2016 Mar 24.

Complejo Hospitalario de Navarra, Pamplona, Spain.

Background & Aims: After endoscopic mucosal resection (EMR) of colorectal lesions, delayed bleeding is the most common serious complication, but there are no guidelines for its prevention. We aimed to identify risk factors associated with delayed bleeding that required medical attention after discharge until day 15 and develop a scoring system to identify patients at risk.

Methods: We performed a prospective study of 1214 consecutive patients with nonpedunculated colorectal lesions 20 mm or larger treated by EMR (n = 1255) at 23 hospitals in Spain, from February 2013 through February 2015. Patients were examined 15 days after the procedure, and medical data were collected. We used the data to create a delayed bleeding scoring system, and assigned a weight to each risk factor based on the β parameter from multivariate logistic regression analysis. Patients were classified as being at low, average, or high risk for delayed bleeding.

Results: Delayed bleeding occurred in 46 cases (3.7%, 95% confidence interval, 2.7%-4.9%). In multivariate analysis, factors associated with delayed bleeding included age ≥75 years (odds ratio [OR], 2.36; P < .01), American Society of Anesthesiologist classification scores of III or IV (OR, 1.90; P ≤ .05), aspirin use during EMR (OR, 3.16; P < .05), right-sided lesions (OR, 4.86; P < .01), lesion size ≥40 mm (OR, 1.91; P ≤ .05), and a mucosal gap not closed by hemoclips (OR, 3.63; P ≤ .01). We developed a risk scoring system based on these 6 variables that assigned patients to the low-risk (score, 0-3), average-risk (score, 4-7), or high-risk (score, 8-10) categories with a receiver operating characteristic curve of 0.77 (95% confidence interval, 0.70-0.83). In these groups, the probabilities of delayed bleeding were 0.6%, 5.5%, and 40%, respectively.

Conclusions: The risk of delayed bleeding after EMR of large colorectal lesions is 3.7%. We developed a risk scoring system based on 6 factors that determined the risk for delayed bleeding (receiver operating characteristic curve, 0.77). The factors most strongly associated with delayed bleeding were right-sided lesions, aspirin use, and mucosal defects not closed by hemoclips. Patients considered to be high risk (score, 8-10) had a 40% probability of delayed bleeding.
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http://dx.doi.org/10.1016/j.cgh.2016.03.021DOI Listing
August 2016

Challenging combined EUS-and-ERCP-endoscopic retrieval of proximally migrated pancreatic stent.

Gastrointest Endosc 2016 Jul 21;84(1):187-8. Epub 2016 Jan 21.

Endoscopy Unit, Gastroenterology Department, Hospital Universitario Marqués de Valdecilla, Santander, Spain.

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http://dx.doi.org/10.1016/j.gie.2016.01.032DOI Listing
July 2016

Methionyl-tRNA Formyltransferase (MTFMT) Deficiency Mimicking Acquired Demyelinating Disease.

J Child Neurol 2016 Feb 9;31(2):215-9. Epub 2015 Jun 9.

Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.

Disease-related mutations in the mitochondrial methionyl-tRNA formyltransferase (MTFMT) gene encoding a critical enzyme for mitochondrial translation have been rarely reported and are described in association with Leigh syndrome and combined oxidative phosphorylation deficiency. Symptoms include developmental delay, followed by ataxia and spasticity manifesting at later stages. A man had a clinical picture suggestive of an acquired demyelinating disease. Brain magnetic resonance imaging (MRI) demonstrated extensive involvement of the optic nerves, cerebral white matter, brain stem, and spinal cord. Whole-exome sequencing detected a pathologic homozygous c.626C>T mutation in the MTFMT gene. These findings expand the clinical features and neuroimaging spectrum associated with MTFMT mutations to include a relapsing-remitting phenotype.
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http://dx.doi.org/10.1177/0883073815587946DOI Listing
February 2016

A hierarchical algorithm for molecular similarity (H-FORMS).

J Comput Chem 2015 Jul 2;36(19):1456-66. Epub 2015 Jun 2.

Departamento de Física Aplicada, Centro de Investigación y de Estudios Avanzados Unidad Mérida. Km 6 Antigua carretera a Progreso. Apdo. Postal 73, Cordemex, 97310, Mérida, Yuc, México.

A new hierarchical method to determine molecular similarity is introduced. The goal of this method is to detect if a pair of molecules has the same structure by estimating a rigid transformation that aligns the molecules and a correspondence function that matches their atoms. The algorithm firstly detect similarity based on the global spatial structure. If this analysis is not sufficient, the algorithm computes novel local structural rotation-invariant descriptors for the atom neighborhood and uses this information to match atoms. Two strategies (deterministic and stochastic) on the matching based alignment computation are tested. As a result, the atom-matching based on local similarity indexes decreases the number of testing trials and significantly reduces the dimensionality of the Hungarian assignation problem. The experiments on well-known datasets show that our proposal outperforms state-of-the-art methods in terms of the required computational time and accuracy.
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http://dx.doi.org/10.1002/jcc.23947DOI Listing
July 2015

Impact of anticoagulation on upper-gastrointestinal bleeding in cirrhosis. A retrospective multicenter study.

Hepatology 2015 Aug 27;62(2):575-83. Epub 2015 Apr 27.

Barcelona Hepatic Hemodynamic Laboratory, Liver Unit, Hospital Clínic-IDIBAPS, University of Barcelona, Spain.

Unlabelled: Recent studies have shown that liver cirrhosis (LC) behaves as an acquired hypercoagulable state with increased thrombotic risk. This is why anticoagulation therapy (AT) is now frequently used in these patients. Variceal bleeding is a severe complication of LC. It is unknown whether AT may impact the outcome of bleeding in these patients. Fifty-two patients on AT with upper gastrointestinal bleeding (UGIB) were evaluated. Portal vein thrombosis (PVT) and different cardiovascular disorders (CVDs) were the indication for AT in 14 and 38 patients, respectively. Overall, 104 patients with LC and UGIB not under AT matched for severity of LC, age, sex, source of bleeding, and Sequential Organ Failure Assessment (SOFA) score served as controls. UGIB was attributed to portal hypertension (PH) in 99 (63%) patients and peptic/vascular lesions in 57 (37%). Twenty-six (17%) patients experienced 5-day failure; SOFA, source of UGIB, and PVT, but not AT, were independent predictors of 5-day failure. In addition, independent predictors of 6-week mortality, which was observed in 26 (11%) patients, were SOFA, Charlson Comorbidity index, and use of AT for a CVD. There were no differences between patients with/without AT in needs for rescue therapies, intensive care unit admission, transfusions, and hospital stay.

Conclusions: Factors that impact the outcome of UGIB in patients under AT are degree of multiorgan failure and comorbidity, but not AT itself.
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http://dx.doi.org/10.1002/hep.27783DOI Listing
August 2015

Lymphocytic hypophysitis associated with pediatric multiple sclerosis.

Pediatr Neurol 2014 Oct 25;51(4):580-2. Epub 2014 Jun 25.

Division of Child Neurology, Baylor College of Medicine, Texas Children's Hospital, Houston, Texas.

Background: Lymphocytic hypophysitis (LH) is a rare inflammatory disorder of the pituitary gland and infundibulum most often observed in the setting of autoimmune disease with a variety of clinical and endocrine presentations. The association between lymphocytic hypophysitis and multiple sclerosis has not been reported.

Patient And Results: We describe an adolescent boy with polyfocal neurological signs including optic neuritis as well as hypopituitarism and diabetes insipidus related to lymphocytic hypophysitis. His imaging met 2010 McDonald criteria for multiple sclerosis. This diagnosis was further supported by cerebrospinal fluid analysis and a negative evaluation for an alternate diagnosis. Imaging features of lymphocytic hypophysitis include an absent posterior pituitary bright spot with an enlarged cystic pituitary gland, stalk thickening, and improvement with corticosteroid therapy.

Conclusions: Lymphocytic hypophysitis and multiple sclerosis share a common autoimmune pathogenesis, perhaps explaining the co-occurrence of the diseases. The presentation of endocrinologic disturbances such as diabetes insipidus with typical features of a multiple sclerosis attack should prompt further investigation of possible comorbid inflammatory disease involving the hypothalamic-pituitary axis.
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http://dx.doi.org/10.1016/j.pediatrneurol.2014.06.005DOI Listing
October 2014

Pediatric multiple sclerosis: current concepts and consensus definitions.

Autoimmune Dis 2013 2;2013:673947. Epub 2013 Nov 2.

Baylor College of Medicine, Houston, TX 77030, USA.

Multiple sclerosis (MS), a chronic inflammatory autoimmune disease of the central nervous system (CNS) commonly diagnosed in adults, is being recognized increasingly in children. An estimated 1.7%-5.6% of all patients with MS have clinical symptoms before reaching the age of 18 years. In comparison with adults, the diagnosis of MS in children can be more difficult, being dismissed or misdiagnosed as other clinical disorders. Although adults and children share basic aspects of the disorder, children have distinctive clinical features, neuroimaging, laboratory, and courses of the disease. The 2010 McDonald criteria have simplified the requirements for establishing the diagnosis of MS and have been proposed to be applicable for the diagnosis of pediatric MS, mainly in children 12 years and older. This paper describes the distinctive features of common pediatric demyelinating disorders, including MS, and summarizes the most recent advances based on the available literature.
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http://dx.doi.org/10.1155/2013/673947DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3835839PMC
December 2013

Pediatric multiple sclerosis in Venezuela.

Arq Neuropsiquiatr 2012 Apr;70(4):267-70

Pediatrics Department, School of Medicine, University of Zulia, Maracaibo, Venezuela.

Objective: To describe the epidemiological and clinical characteristics of Venezuelan pediatric patients with multiple sclerosis (MS).

Methods: Database records from the National Program for MS were searched for patients with an established diagnosis of MS whose first symptoms appeared before age 18.

Results: The national database held records of 1.710 patients; 3.8% had onset of the first symptoms before age 18. 46.7% were boys, yielding an F:M ratio of 1.13:1. Many children had a disease onset characterized by motor impairment (30.7%), brainstem/cerebellum and spinal cord affectation (27.6%), headache (26%). Less frequent symptoms were sensory symptoms (8%) and optic neuritis (7%).

Discussion: Pediatric MS patients in Venezuela represent a significant proportion of all MS cases. The clinical pattern is characterized by motor symptoms at onset, and predominantly monosymptomatic presentation with a relapsing-remitting pattern. This is the first systematic attempt to estimate the prevalence of pediatric MS in Venezuela.
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http://dx.doi.org/10.1590/s0004-282x2012000400008DOI Listing
April 2012

Efficacy and safety of anticoagulation on patients with cirrhosis and portal vein thrombosis.

Clin Gastroenterol Hepatol 2012 Jul 28;10(7):776-83. Epub 2012 Jan 28.

Hepatic Hemodynamic Laboratory, Liver Unit, Institut de Malalties Digestives i Metaboliques, Hospital Clínic-Institut de Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), University of Barcelona, Barcelona, Spain.

Background & Aims: Portal vein thrombosis (PVT) is a frequent event in patients with cirrhosis; it can be treated with anticoagulants, but there are limited data regarding safety and efficacy of this approach. We evaluated this therapy in a large series of patients with cirrhosis and non-neoplastic PVT.

Methods: We analyzed data from 55 patients with cirrhosis and PVT, diagnosed from June 2003 to September 2010, who received anticoagulant therapy for acute or subacute thrombosis (n = 31) or progression of previously known PVT (n = 24). Patients with cavernomatous transformation were excluded. Thrombosis was diagnosed, and recanalization was evaluated by using Doppler ultrasound, angio-computed tomography, and/or angio-magnetic resonance imaging analyses.

Results: Partial or complete recanalization was achieved in 33 patients (60%; complete in 25). Early initiation of anticoagulation was the only factor significantly associated with recanalization. Rethrombosis after complete recanalization occurred in 38.5% of patients after anticoagulation therapy was stopped. Despite similar baseline characteristics, patients who achieved recanalization developed less frequent liver-related events (portal hypertension-related bleeding, ascites, or hepatic encephalopathy) during the follow-up period, but this difference was not statistically significant (P = .1). Five patients developed bleeding complications that were probably related to anticoagulation. A platelet count <50 × 109/L was the only factor significantly associated with higher risk for experiencing a bleeding complication. There were no deaths related to anticoagulation therapy.

Conclusions: Anticoagulation is a relatively safe treatment that leads to partial or complete recanalization of the portal venous axis in 60% of patients with cirrhosis and PVT; it should be maintained indefinitely to prevent rethrombosis.
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http://dx.doi.org/10.1016/j.cgh.2012.01.012DOI Listing
July 2012

[Attention-deficit / hyperactivity disorder in autism spectrum disorders].

Invest Clin 2011 Jun;52(2):195-204

Departamento de Psicología, Escuela de Educación, Facultad de Medicina, Universidad del Zulia, Maracaibo, Venezuela.

According to the DSM-IV-TR, symptoms of inattention and hyperactivity are frequent in children with Autism Spectrum Disorders (ASD). This statement is supported by clinical observation and formal assessment. However, ASD diagnosis is still among the exclusion criteria for the Attention-Deficit/Hyperactivity Disorder (ADHD). Such exclusion generates controversy and questions regarding the need and benefits of maintaining or not these separations; so much so, that the proposed criteria for the DSM-V eliminate that exclusion condition. It is necessary a better understanding of the comorbidity between both entities in order to be able to have an appropriate sequence of the intervention goals. For that reason, if inattention and hyperactivity in individuals with ASD are considered as a representation of a comorbid diagnosis of ADHD, treatment plans for this group would be better adjusted and more likely to offer a real benefit in the outcome of their adaptive functioning.
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June 2011

NMO in pediatric patients: brain involvement and clinical expression.

Arq Neuropsiquiatr 2011 Feb;69(1):34-8

Pediatrics Department, School of Medicine, La Universidad del Zulia, Maracaibo, Venezuela.

Objective: To analyze the clinical, neuroimaging characteristics and positivity of the acquaporin water channel (NMO-IgG) in pediatric patients with neuromyelitis optica (NMO). This disorder could have a variable clinical expression. To address such variability, the term NMO spectrum has been suggested.

Method: We evaluated six pediatric patients, with a median age of 11 years at the time of the study, with the diagnosis of NMO by the Wingerchuck criteria.

Results: All the cases exhibited bilateral optic neuritis (ON). Four patients had abnormalities on brain MRI from the onset,although only three of them developed symptoms correlated to those lesions during the course of their disorder. NMO-IgG was positive in 80%.

Conclusion: Optic neuropathy is the most impaired feature in NMO patients. Brain MRI lesions are not compatible with multiple sclerosis and positivity of the NMO-IgG are also present in NMO pediatric patients, confirming the heterogeneity in the expression of this disorder.
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http://dx.doi.org/10.1590/s0004-282x2011000100008DOI Listing
February 2011

[Aicardi syndrome: a report of four Venezuelan patients].

Invest Clin 2010 Sep;51(3):415-22

Departamento de Pediatría, Facultad de Medicina, Universidad del Zulia, Maracaibo, Venezuela.

Aicardi syndrome is characterized by agenesis of the corpus callosum, infantile spasms and chorioretinal lacunae. The evolution of this disorder is variable, with a severe outcome over the first five years of age. The purpose of this report was to demonstrate the spectrum of the clinical phenotype and the course of this disorder in four Venezuelan patients. All patients met the major criteria, had severe psychomotor impairment and early onset seizures. There were microphtalmia in two of the patients. Three patients (75%) showed coloboma, interhemispheric cyst and periventricular heterotopias. The first patient, with longer follow-up, is currently aged 22. They all exhibited a typical asymmetric pattern on the electroencephalogram. These cases illustrate the variable clinical expression and severity of the Aicardi syndrome. A diagnosis of this disorder should be considered in girls with developmental delay, particularly, when there are accompanying recurrent seizures occurring in early childhood.
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September 2010

Region-based current-source reconstruction for the inverse EEG problem.

IEEE Trans Biomed Eng 2011 Apr 13;58(4):1044-54. Epub 2010 Dec 13.

Department of Computer Science, Centro de Investigación en Matemáticas (CIMAT), Guanajuato, Gto., 36000, Mexico.

This paper presents a new method for the reconstruction of current sources for the electroencephalography (EEG) inverse problem, which produces reconstructed sources, which are confined to a few anatomical regions. The method is based on a partition of the gray matter into a set of regions, and in the construction of a simple linear model for the potential produced by feasible source configurations inside each one of these regions. The proposed method computes the solution in two stages: in the first one, a subset of active regions is found so that the combined potentials produced by sources inside them approximate the measured potential data. In the second stage, a detailed reconstruction of the current sources inside each active region is performed. Experimental results with synthetic data are presented, which show that the proposed scheme is fast, computationally efficient and robust to noise, producing results that are competitive with other published methods, especially when the current sources are effectively distributed in few anatomical regions. The proposed method is also validated with real data from an experiment with visual evoked potentials.
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http://dx.doi.org/10.1109/TBME.2010.2099120DOI Listing
April 2011

Epidemiological findings of pervasive developmental disorders in a Venezuelan study.

Autism 2008 Mar;12(2):191-202

La Universidad del Zulia, Maracaibo,Venezuela.

The study aims to determine the prevalence of autism spectrum disorders (ASDs) for children receiving services in Maracaibo County, Venezuela. Children aged 3-9 with diagnosis of any ASD were recruited. We ascertained area, referral process, and definitions of ASD for each patient. A total of 430 children were identified, and 76.5 percent were boys. Prevalences were 1.7 per 1000 for all ASD, 1.1 per 1000 for autism, and 0.6 per 1000 for PDD-NOS and Asperger syndrome combined. These prevalences are lower than current reports in the literature. Differences in case-finding methods, diagnostic criteria, and lack of awareness in the general population may have influenced the number of cases identified. An ASD prevalence of 1.7 per 1000 should alert the health and education authorities to the need to reassess the services available for children with these disorders and their families.
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http://dx.doi.org/10.1177/1362361307086663DOI Listing
March 2008

[Clinical presentation of attention deficit/hyperactivity disorder as a function of the gender].

Invest Clin 2007 Dec;48(4):459-68

Unidad de Investigación del Trastorno por Déficit de Atención-Hiperactividad, Venezuela.

Results from studies comparing boys and girls diagnosed as having Attention Deficit-Hyperactivity Disorder (ADHD) have been non conclusive. In general, the results of such studies report boys as being more hyperactive and presenting more conduct problems, and girls as having more cognitive and learning problems. The aim of this study was to collect information about the characterization of the disorder depending on the gender. 169 children (123 males, 46 females), between 4 and 13 years of age with ADHD were studied. The assessment battery included Conners' rating scales-Revised for parents and teachers, short forms of the Wechsler Intelligence Scale for Children-Third Edition (WISC-III) and Wechsler Preschool and Primary Scale of Intelligence-Revised (WPPSI-R), academic achievement measures, developmental history and the Diagnostic Interview Schedule for Children-IV Version-Parents (DISC-IV). The results indicated the lack of significant differences between genders for the studied variables, ADHD boys and girls scored alike in the various behavioral and cognitive measures. The results presented describe homogeneity in the symptoms, demographic characteristics and neuropsychological functioning for children of both genders; suggesting a syndrome with the same criteria and independent of the gender.
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December 2007

Prevalence rates of attention deficit/hyperactivity disorder in a school sample of Venezuelan children.

Child Psychiatry Hum Dev 2008 Sep 22;39(3):311-22. Epub 2007 Dec 22.

Psychology Department, La Universidad del Zulia, Calle 79 No. 3E-31, Maracaibo, Estedo Zulia, Venezuela.

A total of 1,535 4-12 year-old children were screened with the Conners' rating scales, followed by diagnostic confirmation by the diagnostic interview schedule for children-IV-parent version. The prevalence of ADHD was estimated to be 10.03%, and only 3.9% of children had received medication for the treatment of ADHD symptoms. Prevalence rates and demographic profile of Venezuelan children with ADHD are very similar to those found in samples from other countries. Authorities need to develop public health policies to correctly identify and treat affected subjects. Furthermore, clinicians must actively search for children with ADHD in order to provide the best-available treatment.
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http://dx.doi.org/10.1007/s10578-007-0090-5DOI Listing
September 2008

[Molecular analysis of the GABRB3 gene in autistic patients: an exploratory study].

Invest Clin 2007 Jun;48(2):225-42

Unidad de Genética Médica, Facultad de Medicina, Universidad del Zulia, Maracaibo, Venezuela.

Autism is a complex neurodevelopmental disorder characterized by impairment of social interaction, language, communication, and stereotyped, repetitive behavior. Genetic predisposition to Autism has been demonstrated in families and twin studies. There is evidence (linkage and genetic association, biochemical, neuropathological, functional and cytogenetic) that the gamma-amino-butyric acid receptor beta 3 subunit gene (GABRB3) at 15q11-q13 is a susceptibility candidate gene for Autism. The aim of this exploratory study was to identify new variants of this gene. We performed the molecular analysis (SSCP/Sequencing) of 10 exons and its intronic flanking regions of GABRB3, using a candidate gene screening approach in 18 idiopathic autistic patients. We did not find non-synonymous mutations at the encoding regions, but we identified four SNP (Single Nucleotide Polymorphism). The first one, represented a silent mutation p.P25P in exon la and was found in 33.33% of the patients. The second one: IVS3 + 13C > T (5b far from the intron 5' consensus sequence), was found in 44.44% of the patients, while it was also identified in 16.67% of the controls. Simultaneously, 33.33% of the patients had both variants, and although, 16.67% of the controls also had the same combination of variants, 66.66% of the patients with those alleles had a familiar history of Autism. The third and fourth SNP: IVS5 + 40T > G and IVS-70A > G were identified in two different patients. None of the last three SNPs have been reported at the SNP database (dbSNP). The proximity of SNP: IVS3 + 13C > T with the consensus and interaction sequence with U1 nucleoriboprotein, could disturb the normal splicing of mRNA. This is in agreement with the evidence of lower levels of GABA-A receptors in autistic brains; so, it could be a common variant, that by itself could not cause a phenotypic effect, but joined to other variants with the same gene, in different related genes or with epigenetic changes, could explain the autistic phenotype and its heterogeneity.
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June 2007

[Multiple sclerosis in children: clarifying its place among the demyelinating spectrum].

Invest Clin 2006 Dec;47(4):413-25

Postgrado de Neurología Pediátrica, Facultad de Medicina, Universidad del Zulia, Maracaibo, Venezuela.

Multiple sclerosis (MS) is an autoimmune disease caused by the destruction of the myelin layer and the nervous fibers, and secondary by a progressive neuronal damage. It is characterized by episodes of demyelination disseminated in time and space in different areas of the white matter of the CNS which includes periventricular region, spinal cord, brain stem, cerebellum and optical nerve. Due to the confusing differential diagnosis of MS in children with other demyelinating diseases such as ADEM, it is important to reach this diagnosis when there is proof of white matter lesions disseminated in time and space that cannot be explained by any other mechanisms or pathologies. The goal of this paper is to review the diagnostic parameters used for MS in the pediatric age, the dilemmas regarding the validity of diagnostic criteria, clinical manifestations, differentiation of other demyelinating diseases, and the diagnostic process. MS although infrequent, is a valid diagnosis among the spectrum of childhood inflammatory demyelinating diseases. The clinical presentation might be indistinguishable from a multifocal acute disseminated encephalopathy or could be presented with just focal signs. A reasonable clinical judgment and the practice of laboratory tests confirm or rule out the diagnosis. It is not possible to differentiate between ADEM and MS in a first episode, nor by the clinical, the CSF, neither the neuroimaging. There are still needed consensus criteria both clinical and laboratory test. There are many question still to be answered using prospective studies, and standardized clinical measures that will allow the delimitation of the demographic, neurological, and neuropsychological aspects of the MS and other form of acquired demyelinating diseases in children.
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December 2006

Exploration of event-induced EEG phase synchronization patterns in cognitive tasks using a time-frequency-topography visualization system.

J Neurosci Methods 2007 Mar 5;161(1):166-82. Epub 2006 Dec 5.

Centro de Investigation en Matematicas (CIMAT), Guanajuato, Mexico.

In this paper, we present a method for the study of synchronization patterns measured from EEG scalp potentials in psychophysiological experiments. This method is based on various techniques: a time-frequency decomposition using sinusoidal filters which improve phase accuracy for low frequencies, a Bayesian approach for the estimation of significant synchrony changes, and a time-frequency-topography visualization technique which allows for easy exploration and provides detailed insights of a particular experiment. Particularly, we focus on in-phase synchrony using an instantaneous phase-lock measure. We also discuss some of the most common methods in the literature, focusing on their relevance to long-range synchrony analysis; this discussion includes a comparison among various synchrony measures. Finally, we present the analysis of a figure categorization experiment to illustrate our method.
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http://dx.doi.org/10.1016/j.jneumeth.2006.10.018DOI Listing
March 2007

[Comparison of esophageal stenoses produced by endoscopic sclerotherapy versus variceal ligation].

Gastroenterol Hepatol 2006 Nov;29(9):523-7

Servicio de Aparato Digestivo. Hospital Universitario Marqués de Valdecilla. Santander. España.

Introduction: Variceal ligation (VL) eradicates esophageal varices faster than endoscopic sclerotherapy (ES) with a lower rebleeding rate and fewer secondary effects. However, most studies have evaluated the short-term effects of these treatments and some late complications may be overlooked.

Patients And Methods: To determine the incidence and the characteristics of stenosis, we included 253 cirrhotic patients treated endoscopically for variceal bleeding from 1988 to 2004 in our hospital. ES was carried out with ethanolamine 5% and polidocanol 1.5%. ES and VL were carried out every 15 days until varices were eradicated and then at 3-, 6- and 12-month intervals; if varices reappeared, the initial treatment was repeated. Stenosis was considered mild when esophageal size was more than 10 mm and severe when the endoscope could not be passed through the stricture.

Results: We found stenosis in seven out of 105 (6.7%) ES-treated patients and in 10 out of 148 (6.7%) VL-treated patients. The clinical characteristics of the patients and the previous number of endoscopic sessions were similar in both groups. Four out of seven ES patients developed stenosis during the first eradication process (mean: 11 months, 1-60), but this early stenosis was observed in one out of 10 VL patients (mean: 20 months, 1-72). Stenosis was severe in three out of seven ES patients (43%) but in only two out of ten VL patients (20%) (NS).

Conclusions: The incidence of esophageal stenosis was similar after treatment of esophageal varices with ES and VL, although VL had a tendency to produce later stenosis.
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http://dx.doi.org/10.1157/13094346DOI Listing
November 2006

Myocyte enhancing factor-2A in Alzheimer's disease: genetic analysis and association with MEF2A-polymorphisms.

Neurosci Lett 2007 Jan 16;411(1):47-51. Epub 2006 Nov 16.

Genética Molecular-Instituto de Estudios Nefrológicos, Hospital Universitario Central Asturias, Oviedo, Spain.

Polymorphisms at different genes have been proposed as determinants of the risk for developing late-onset Alzheimer's disease (LOAD). Among the several candidate genes are those that encode proteins involved in neuronal degeneration/survival. Studies of primary neuronal cultures supported that members of the myocyte enhancing factor-2 (MEF2) family of transcription factors have an anti-apoptotic effect, regulating the expression of proteins involved in neuronal survival and differentiation. We analysed the MEF2A gene in a total of 357 patients (mean age 72 years, range 60-97 years). Among others, a Pro279Leu in exon 8 and a polyglutamine (CAG) repeat polymorphisms in exon 12 were found. These variants were also genotyped in 495 healthy controls (>50 years old), and the frequencies were statistically compared. Eight patients were 279L (six P/L and two L/L), compared to only one control (2% vs. 0.2%; p=0.004, OR=11.32). There was a significantly higher frequency of 279L-carriers among APOE epsilon4+ (7/154=4.5%), compared to epsilon4- (1/203) (p=0.02). In conclusion, our work suggests that the variation at the MEF2A gene could be involved in the risk of developing LOAD. Because MEF2 has been related with neuronal survival, and the 279L allele has been related with a reduction in the transcriptional activation activity of MEF2A, the effect of this allele could be mediated through a down-regulation of antiapoptotic genes.
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http://dx.doi.org/10.1016/j.neulet.2006.09.055DOI Listing
January 2007

Variceal ligation plus nadolol compared with ligation for prophylaxis of variceal rebleeding: a multicenter trial.

Hepatology 2005 Mar;41(3):572-8

Hospital Universitario Marques de Valdecilla, Santander, Spain.

beta-Blockers and endoscopic variceal ligation (EVL) have proven to be valuable methods in the prevention of variceal rebleeding. The aim of this study was to compare the efficacy of EVL combined with nadolol versus EVL alone as secondary prophylaxis for variceal bleeding. Patients admitted for acute variceal bleeding were treated during emergency endoscopy with EVL or sclerotherapy and received somatostatin for 5 days. At that point, patients were randomized to receive EVL plus nadolol or EVL alone. EVL sessions were repeated every 10 to 12 days until the varices were eradicated. Eighty patients with cirrhosis (alcoholic origin in 66%) were included (Child-Turcotte-Pugh A, 15%; B, 56%; C, 29%). The median follow-up period was 16 months (range, 1-24 months). The variceal bleeding recurrence rate was 14% in the EVL plus nadolol group and 38% in the EVL group (P = .006). Mortality was similar in both groups: five patients (11.6%) died in the combined therapy group and four patients (10.8%) died in the EVL group. There were no significant differences in the number of EVL sessions to eradicate varices: 3.2 +/- 1.3 in the combined therapy group versus 3.5 +/- 1.3 in the EVL alone group. The actuarial probability of variceal recurrence at 1 year was lower in the EVL plus nadolol group (54%) than in the EVL group (77%; P = .06). Adverse effects resulting from nadolol were observed in 11% of the patients. In conclusion, nadolol plus EVL reduces the incidence of variceal rebleeding compared with EVL alone. A combined treatment could lower the probability of variceal recurrence after eradication.
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http://dx.doi.org/10.1002/hep.20584DOI Listing
March 2005

Chemokines (RANTES and MCP-1) and chemokine-receptors (CCR2 and CCR5) gene polymorphisms in Alzheimer's and Parkinson's disease.

Neurosci Lett 2004 Nov;370(2-3):151-4

Genética Molecular-IRSIN/FRIAT, Hospital Central Asturias, Oviedo 33006, Spain.

Parkinson's disease (PD) is a complex disorder characterized by the progressive degeneration of dopaminergic neurons in the midbrain. Late-onset Alzheimer's disease (LOAD) is the most common cause of dementia in the elderly, affecting about 5% of the population older than 65 years. Several works have demonstrated the involvement of inflammation in the pathogenesis of both, PD and LOAD. Genetic susceptibility to develop PD and LOAD has also been widely recognised. Thus, functional polymorphisms at the genes encoding inflammatory proteins could influence the overall risk of developing these neurodegenerative disorders. We examined whether DNA-polymorphisms at the genes encoding chemokines MCP-1 (-2518 A/G) and RANTES (-403 A/G), and chemokine receptors 5 (CCR5, Delta32) and 2 (CCR2,V64I), were associated with the risk and/or the clinical outcome of LOAD and PD. A total of 200 PD, 326 LOAD, and 370 healthy controls were genotyped for the four polymorphisms, and genotype frequencies statistically compared. We did not find significant differences in the frequencies of the different genotypes between both groups of patients and controls. We conclude that the four DNA polymorphisms, which have been associated with several immuno-modulated diseases, did not contribute to the risk of PD or LOAD.
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http://dx.doi.org/10.1016/j.neulet.2004.08.016DOI Listing
November 2004

[Carrier detection of Duchenne/Becker muscular dystrophy by analysis of STRs loci linked to the gene of dystrophin in Venezuelan families].

Invest Clin 2002 Dec;43(4):239-54

Unidad de Genética Médica, Universidad del Zulia, Maracaibo, Venezuela.

The Duchenne/Becker Muscular Dystrophy (DMD/BMD) is an X linked recessive lethal disease. The female carrier will transmit the disease gene to half of her sons and half of her daughters; half of the daughters will be carriers, while half will be normal. Half of the sons will be normal and, on average, half will have the disease. It is of particular relevance to be able to detect carrier status among female relatives of the patients for genetic counseling and prenatal diagnosis. The method of Short Tandem Repeat (STR) sequence polymorphism analysis can determine haplotype at normal status or at risk status and, to establish genetic linkage between the mutated gene and the segregated haplotype. We have analyzed 105 members from 15 unrelated Venezuelan families with one or more siblings affected with DMD/DMB and 7 unrelated males. Of the 105, 37 were male (26 affected and 11 normal) and 68 were female. STR sequences (STR44, STR45, STR49, STR50, STR3'DYS) of the gene of the Dystrophin were amplified by polymerase chain reaction (PCR) to analyze allelic polymorphism in the families. Five of the 15 families (33%) had a deletion of one or several of the exons. Of the 68 females, 27 (39.7%) were carriers, 27 (39.7%) were non-carriers and in 14 cases (20.58%) it was not possible to reach a definitive diagnosis. The definitive diagnosis could be established in 79% of the females. This analysis also shows that the mutation occurred on the grandpaternal X chromosome in one family. Hemizygocity was detected and carrier status ascertained in the mother of other patient and in one family we were able to do prenatal diagnosis. The germinal mosaicism could not be excluded in 3 patients.
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December 2002