10 results on '"David Ramírez"'
Search Results
2. Trypanosoma cruzi I: Towards the need of genetic subdivision?, Part II
- Author
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Carolina Hernández and Juan David Ramírez
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0301 basic medicine ,Chagas disease ,Tcidom ,Review ,0302 clinical medicine ,Genotype ,Kinetoplastida ,Ecology ,biology ,Dtus ,Zoonosis ,Genomics ,Cardiovascular disease ,Classification ,Infectious Diseases ,Tci ,Human ,Trypanosoma cruzi ,Veterinary (miscellaneous) ,Genotypes ,030231 tropical medicine ,Ecological data ,03 medical and health sciences ,Parasitic disease ,parasitic diseases ,Genetics ,medicine ,Animals ,Humans ,Geographical variation (species) ,Chagas Disease ,Genetic variation ,Typing ,Chagas cardiomyopathy ,Protozoa ,Disease severity ,Genetic diversity ,Animal ,Protozoal genetics ,Bat ,Genetic Variation ,Nonhuman ,biology.organism_classification ,medicine.disease ,030104 developmental biology ,Evolutionary biology ,Insect Science ,Genetic variability ,Parasitology ,Geographical distribution - Abstract
Chagas disease is a complex zoonosis caused by the kinetoplastid parasite Trypanosoma cruzi. This protozoan exhibits remarkable genetic diversity evinced in at least six Discrete Typing Units (DTUs) with the foreseen emergence of a genotype associated to bats (TcBat). T. cruzi I is the DTU with the broadest geographical distribution and associated to severe cardiomyopathies. In 2011, we published a review questioning the need for genetic subdivision within TcI. However, after six years of intensive research. Herein, we attempted to determine if TcI should be subdivided or not in the light of the current genetic, biological, clinical and ecological data. The future perspectives are discussed. © 2017 Elsevier B.V.
- Published
- 2018
3. Genomic analyses reveal moderate levels of ploidy, high heterozygosity and structural variations in a Colombian isolate of Leishmania (Leishmania) amazonensis
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Luz H. Patiño, Marina Muñoz, Carlos Muskus, and Juan David Ramírez
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0301 basic medicine ,Epidemiology ,Parasite survival ,Genome ,Loss of heterozygosity ,0302 clinical medicine ,Ploidy ,Copy-number variation ,Leishmaniasis ,Phylogeny ,Species comparison ,Leishmania ,Genetics ,Diversity ,Heterozygosity ,biology ,Genomics ,030108 mycology & parasitology ,Parasite ,Infectious Diseases ,Parasite virulence ,Dna-seq ,Parasite development ,Heterozygote ,DNA Copy Number Variations ,Veterinary (miscellaneous) ,Chromosome variant ,030231 tropical medicine ,Colombia ,Genome sequencing ,Article ,Amazonensis ,03 medical and health sciences ,Cutaneous leishmaniasis ,medicine ,Animalia ,Humans ,Parasites ,Genetic variation ,Ploidies ,Copy number variation ,Genome analysis ,Aneuploidy ,Nonhuman ,medicine.disease ,biology.organism_classification ,Single nucleotide polymorphism ,Whole genome sequencing ,Insect Science ,Parasitology ,Controlled study ,Genome, Protozoan ,Leishmania amazonensis - Abstract
Leishmania amazonensis is one of the causative agents of the different forms of cutaneous leishmaniasis present in Latin America. This species has been isolated from humans and animals (canine/feline) in some endemic regions of Colombia. Therefore, L. amazonensis is of great relevance at the clinical and epidemiological levels in medicine and veterinary science. Until now, very few genomes from this species are available. Here, we report the complete genome sequence of a laboratory-adapted L. amazonensis strain isolated from a human patient with clinical manifestation of cutaneous leishmaniasis in Colombia. The genome sequence not only allowed inter and intra-species comparative analyses to be performed with the sequenced genomes of L. amazonensis strains from different geographical regions, but also increased our knowledge about the genomic behavior of this L. amazonensis Colombian strain. This isolate was also characterized in terms of single nucleotide polymorphisms, chromosome and gene copy number variations (CNVs). The results revealed moderate aneuploidy, CNVs in genes involved in the virulence, growth, and survival of the parasite, and in the distributions of the multicopy genes on some chromosomes, as well as a high level of heterozygosity. The data confirmed previous reports that identified unique variations in L. amazonensis, suggesting aneuploidy may not have a high fitness cost and may allow the rapid generation of diversity in Leishmania parasites growing normally. © 2019 Elsevier B.V.
- Published
- 2020
4. Molecular epidemiology of dengue, yellow fever, Zika and Chikungunya arboviruses: An update
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Adriana Higuera and Juan David Ramírez
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0301 basic medicine ,Epidemiology ,Arbovirus infections ,viruses ,Disease transmission ,Review ,Disease Vectors ,medicine.disease_cause ,Dengue virus ,Zika virus ,Dengue fever ,Dengue ,Aedes aegypti ,0302 clinical medicine ,Disease control ,Prevalence ,Chikungunya ,Chikungunya fever ,Phylogeny ,Developing world ,Arbovirus ,Public health ,Molecular Epidemiology ,biology ,Disease surveillance ,Transmission (medicine) ,Incidence ,Yellow fever ,030108 mycology & parasitology ,Aedes albopictus ,Disease vectors ,Virus strain ,Infectious Diseases ,Molecular epidemiology ,Enzootic ,Yellow fever virus ,Chikungunya virus ,Human ,Arthropoda ,Virus infection ,Veterinary (miscellaneous) ,030231 tropical medicine ,Arbovirus Infections ,03 medical and health sciences ,Zika virus disease ,Genetics ,medicine ,Animals ,Humans ,Mortality ,Health geography ,Dengue virus 4 ,Dengue virus 1 ,Animal ,Molecular analysis ,Dengue virus 3 ,Dengue virus 2 ,Latin america ,Zika Virus ,Dengue Virus ,Nonhuman ,biology.organism_classification ,medicine.disease ,Virology ,Zika fever ,Disease carrier ,Insect Science ,Vector (epidemiology) ,Chikungunya Fever ,Parasitology ,Geographic distribution ,Morbidity ,Arboviruses - Abstract
Arboviruses are a group of viruses transmitted by arthropods. They are characterized by a wide geographic distribution, which is associated with the presence of the vector, and cause asymptomatic infections or febrile diseases in humans in both enzootic and urban cycles. Recent reports of human infections caused by viruses such as dengue, Zika, and chikungunya have raised concern regarding public health, and have led to the re-evaluation of surveillance mechanisms and measures to control the transmission of these arboviruses. Viruses such as Mayaro and Usutu are not currently responsible for a high number of symptomatic infections in humans, but should remain under epidemiological surveillance to avoid the emergence of new epidemics, as happened with Zika virus, that are associated with new or more severe symptoms. Additionally, significant variation has been observed in these viruses, giving rise to different lineages. Until recently, the emergence of new lineages has primarily been related to geographical distribution and dispersion, allowing us to ascertain the possible origins and direction of expansion of each virus type, and to make predictions regarding regions where active infections in humans are likely to occur. Therefore, this review is focused on untangling the molecular epidemiology of Dengue, Yellow fever, Zika and Chikungunya due to their recent epidemics in Latinamerica but provides an update on the geographical distribution globally of these viral variants, and outlines the need for further understanding of the genotypes/lineages assignment. © 2018 Elsevier B.V.
- Published
- 2018
5. Blastocystis and urticaria: Examination of subtypes and morphotypes in an unusual clinical manifestation
- Author
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Juan David Ramírez, Florencia Mongi, Rodolfo D. Casero, and Angie Sánchez
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Male ,Abdominal pain ,Pathology ,Constipation ,Dna extraction ,Urticaria ,Blastocystosis ,Dna sequence ,Blastocystis Infections ,Gene sequence ,dna ,Polymerase Chain Reaction ,Gastroenterology ,law.invention ,Feces ,law ,Dna barcoding ,Middle aged ,Child ,Asymptomatic Infections ,Polymerase chain reaction ,Irritable bowel syndrome ,Allele ,Blastocystis st3 allele 34 and urticaria ,biology ,Protist ,Asymptomatic infection ,Sequence analysis ,Rna, ribosomal, 18s ,Middle Aged ,Classification ,Asymptomatic infections ,Parasite ,Parasite identification ,Diarrhea ,Infectious Diseases ,Protista ,Child, Preschool ,Protozoan ,Female ,medicine.symptom ,Blastocystis infections ,Human ,Morphology ,Adult ,medicine.medical_specialty ,Morphotype ,Adolescent ,Rna 18s ,Veterinary (miscellaneous) ,Argentina ,Major clinical study ,Asymptomatic ,Article ,preschool ,Young Adult ,Gastrointestinal symptom ,Internal medicine ,Genetics ,RNA, Ribosomal, 18S ,medicine ,Humans ,Genetic variation ,Blastocystis subtypes ,Alleles ,Blastocystis ,Argentinian ,Genetic Variation ,Infant ,Sequence Analysis, DNA ,Nonhuman ,biology.organism_classification ,medicine.disease ,Abdominal Pain ,Young adult ,Preschool child ,Insect Science ,Asymptomatic disease ,Genetic variability ,Parasitology ,Controlled study - Abstract
Blastocystis is a human common enteric protist that may colonize a large variety of non-human hosts linked to symptoms and diseases such as abdominal pain, constipation, diarrhea, urticaria, flatulence and irritable bowel syndrome (IBS). Blastocystis exhibits remarkable genetic diversity and multiple subtypes (STs) within the genus with no absolute associations with clinical symptomatology. Here we analyzed fecal samples from Argentinean patients (. n=. 270) belonging to symptomatic (urticaria and non-specific gastrointestinal symptoms, n=. 39) and asymptomatic control (. n=. 28). Those patients infected with Blastocystis (. n=. 67) were submitted for morphological analysis, DNA extraction, 18S PCR, sequencing and STs identification according to DNA barcoding. Blastocystis vacuolar forms were the predominant morphotype (75%), ameboid-like forms were evidenced in 1.5% of samples. Blastocystis ST3 was detected in 71.6% (. n=. 48), of which 71.4%, (. n=. 35) and 28.6% (. n=. 14) belonged to symptomatic and asymptomatic respectively. Other subtypes identified were ST1 (14.9%), ST6 (7.5%) and ST2 (5.9%). Blastocystis 18S barcoding evidenced in non-urticaria symptomatic patients and asymptomatic control group the presence of allele 134 (ST3) (. p less than . 0.0001), while allele 34 (ST3) was detected in 85.7% (18/21) of symptomatic uricaria as compared with control group (1/21) (. p less than . 0.0001). The presence of a particular allele (. a34) significantly associated with urticaria patients was detected and the clinical implications of these findings are herein discussed. © 2015.
- Published
- 2015
6. Towards the establishment of a consensus real-time qPCR to monitor Trypanosoma cruzi parasitemia in patients with chronic Chagas disease cardiomyopathy: A substudy from the BENEFIT trial
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Carlos A. Morillo, Sergio Sosa-Estani, Felipe Guhl, José Antonio Marin-Neto, Myllena de Fátima Alheiros Dias Melo, Elsa F. Velazquez, Otacilio C. Moreira, Carolina Lima-Ferreira, Juan David Ramírez, and Constança Britto
- Subjects
Chagas Cardiomyopathy ,Chagas disease ,Trypanosoma cruzi ,Veterinary (miscellaneous) ,Antiprotozoal Agents ,Argentina ,Parasitemia ,Colombia ,Real-Time Polymerase Chain Reaction ,Sensitivity and Specificity ,Parasite load ,Parasite Load ,Specimen Handling ,Placebos ,Double-Blind Method ,parasitic diseases ,medicine ,TaqMan ,Humans ,Randomized Controlled Trials as Topic ,biology ,DNA (EXTRAÇÃO) ,Reproducibility of Results ,DNA, Protozoan ,medicine.disease ,biology.organism_classification ,DNA extraction ,Infectious Diseases ,Real-time polymerase chain reaction ,Molecular Diagnostic Techniques ,Nitroimidazoles ,Benznidazole ,Insect Science ,Immunology ,Parasitology ,Drug Monitoring ,Brazil ,medicine.drug - Abstract
Quantitative real-time PCR (qPCR) is an accurate method to quantify Trypanosoma cruzi DNA and can be used to follow-up parasitemia in Chagas disease (CD) patients undergoing chemotherapy. The Benznidazole Evaluation for Interrupting Trypanosomiasis (BENEFIT) study is an international, multicenter, randomized, double-blinded and placebo-controlled clinical trial to evaluate the efficacy of benznidazole (BZ) treatment in patients with chronic Chagas cardiomyopathy (CCC). One important question to be addressed concerns the effectiveness of BZ in reducing overall parasite load in CCC patients, even in the absence of parasitological cure. This report describes the evaluation of multiple procedures for DNA extraction and qPCR-based protocols aiming to establish a standardized methodology for the absolute quantification of T. cruzi DNA in Guanidine-EDTA blood (GEB) samples. A panel of five primer sets directed to the T. cruzi nuclear satellite DNA repeats (Sat-DNA) and to the minicircle DNA conserved regions (kDNA) was compared in either SYBR Green or TaqMan systems. Standard curve parameters such as, amplification efficiency, coefficient of determination and intercept were evaluated, as well as different procedures to generate standard samples containing pre-established T. cruzi DNA concentration. Initially, each primer set was assayed in a SYBR Green qPCR to estimate parasite load in GEB samples from chronic Chagas disease patients. The results achieved from Bayesian transmutability analysis elected the primer sets Cruzi1/Cruzi2 ( p = 0.0031) and Diaz7/Diaz8 ( p = 0.0023) coupled to the QIAamp DNA Kit extraction protocol (silica gel column), as the most suitable for monitoring parasitemia in these patients. Comparison between the parasite burden of 150 GEB samples of BENEFIT patients from Argentina, Brazil and Colombia, prior to drug/placebo administration, was performed using Cruzi1/Cruzi2 primers in a SYBR Green approach. The median parasitemia found in patients from Argentina and Colombia (1.93 and 2.31 parasite equivalents/mL, respectively) was around 20 times higher than the one estimated for the Brazilian patients (0.1 parasite equivalents/mL). This difference could be in part due to the complexity of T. cruzi genetic diversity, which is a factor possibly implicated in different clinical presentations of the disease and/or influencing parasitemia levels in infected individuals from different regions of Latin America. The results of SYBR Green qPCR assays herein presented prove this methodology to be more cost efficient than the alternative use of internal fluorogenic probes. In addition, its sensitivity and reproducibility are shown to be adequate to detect low parasitemia burden in patients with chronic Chagas disease.
- Published
- 2013
7. Trypanosoma cruzi I diversity: Towards the need of genetic subdivision?
- Author
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Felipe Guhl and Juan David Ramírez
- Subjects
Chagas disease ,Genotype ,Trypanosoma cruzi ,Veterinary (miscellaneous) ,Disease Vectors ,Phylogenetics ,parasitic diseases ,Genetic variation ,medicine ,Animals ,Humans ,Chagas Disease ,Typing ,Genetic variability ,Phylogeny ,Genetics ,Genetic diversity ,Geography ,biology ,Genetic Variation ,Exons ,biology.organism_classification ,medicine.disease ,Infectious Diseases ,Insect Science ,Parasitology ,Americas ,Microsatellite Repeats - Abstract
Trypanosoma cruzi the aethiological agent of Chagas disease, a complex zoonoses that affects the American continent is a genetically variable parasite subdivided into six Discrete Typing Units (DTUs). T. cruzi I is the most prevalent DTU affecting the northern countries of America with sporadical cases in the southern countries. T. cruzi I has shown great genetic diversity showing plausible subdivisions needed for this group. Recently, TcI has gained novel importance because of the lately discovered relation with cardiomyopathy manifestations that raises the importance of establishing subdivisions within this DTU.
- Published
- 2011
8. Phylogenetic reconstruction based on Cytochrome b (Cytb) gene sequences reveals distinct genotypes within Colombian Trypanosoma cruzi I populations
- Author
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Juan David Ramírez, María Clara Duque, and Felipe Guhl
- Subjects
Chagas disease ,Genotype ,Sequence analysis ,Trypanosoma cruzi ,Veterinary (miscellaneous) ,Genes, Protozoan ,030231 tropical medicine ,Colombia ,03 medical and health sciences ,0302 clinical medicine ,Phylogenetics ,parasitic diseases ,medicine ,Chagas Disease ,Cloning, Molecular ,Gene ,Phylogeny ,030304 developmental biology ,Genetics ,0303 health sciences ,Genetic diversity ,Polymorphism, Genetic ,biology ,Cytochrome b ,Exons ,Sequence Analysis, DNA ,Cytochromes b ,DNA, Protozoan ,biology.organism_classification ,medicine.disease ,3. Good health ,Infectious Diseases ,Insect Science ,Parasitology ,Sequence Alignment - Abstract
Chagas disease caused by Trypanosoma cruzi comprises an important problem of public health in the Americas. This parasite has been recently divided into six Discrete Typing Units (DTUs) due to its high genetic diversity. We sequenced the Cytochorme b (Cytb) gene of 70 T. cruzi I Colombian clones finding four genotypes related to transmission cycles of Chagas disease in Colombia and also to specific hosts of T. cruzi. The genotypes herein described based on Cytb gene sequences are in accordance with those found using the mini-exon gene and reveals once again the enormous genetic diversity at sub-DTU level evidenced in T. cruzi I.
- Published
- 2011
9. Agreement of the Kato-Katz test established by the WHO with samples fixed with sodium acetate analyzed at 6 months to diagnose intestinal geohelminthes
- Author
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Patricia Reyes, Julián Alfredo Fernández-Niño, Myriam Consuelo López, Rubén Darío Heredia, Juan David Ramírez, and Ligia I. Moncada
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Male ,Veterinary medicine ,Fecal pellet ,Parasite load ,Parasite Load ,Feces ,Ascariasis ,Medicine ,Hookworm infections ,Sodium acetate ,Diagnostic test accuracy study ,Intestine ,Trichuris ,Biological transport ,Ascaris lumbricoides ,Human ,Hookworm ,medicine.medical_specialty ,Veterinary (miscellaneous) ,Colombia ,Acetic acid ,World Health Organization ,Sensitivity and Specificity ,Article ,Developing countries ,Fixatives ,Humans ,Soilborne disease ,Transport at the cellular level ,Developing Countries ,Kato katz test ,Feces analysis ,Intestinal geohelminthes ,Acetate ,Animal ,Time factors ,Sodium ,fungi ,parasitic ,medicine.disease ,Parasite egg count ,chemistry ,Insect Science ,Hookworm Infections ,Parasitology ,Comparative study ,Intestinal diseases ,Fixative ,Ancylostomatoidea ,Time Factors ,Developing country ,Sodium Acetate ,Helminthiasis ,chemistry.chemical_compound ,Soil ,fluids and secretions ,Diagnosis ,Prevalence ,Rural area ,Intestinal Diseases, Parasitic ,Middle aged ,Developing world ,Public health ,biology ,Ascaris ,Middle Aged ,Intestines ,Parasite identification ,Sensitivity and specificity ,Infectious Diseases ,Microbiological examination ,Female ,Soil-transmitted helminth ,Adult ,World health organization ,Time ,parasitic diseases ,Animals ,Trichuris trichiura ,Vermes ,Parasite Egg Count ,business.industry ,Biological Transport ,Nonhuman ,biology.organism_classification ,Endoparasite ,Surgery ,Isolation and purification ,Intestine infection ,business ,Controlled study - Abstract
The aim of this study was to evaluate the performance of the Kato-Katz test (WHO version) with stool samples from a rural area, fixed with sodium acetate (SAF). The Kato-Katz test was used to compare unfixed samples (conventional test) with the same samples containing SAF fixative at time 0 and at 6 months. The study included stools from 154 subjects.A marginally statistically significant decrease in prevalence was estimated only for hookworm, when comparing unfixed samples versus the SAF fixed samples read at 6 months (. p=. 0.06). A significant reduction in parasite load was found for hookworm (. p less than . 0.01) and Trichuris trichiura (. p less than . 0.01) between the unfixed and the fixed sample read at 6 months, but not for Ascaris lumbricoides (. p=. 0.10). This research suggests that the SAF fixative solution is a good option for transporting samples for diagnosis, especially in rural areas in developing countries. © 2015 Elsevier B.V.
- Published
- 2014
10. Agreement of the Kato-Katz test established by the WHO with samples fixed with sodium acetate analyzed at 6 months to diagnose intestinal geohelminthes
- Author
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Alfredo Fernández-Niño, Julián, primary, David Ramírez, Juan, additional, Consuelo López, Myriam, additional, Inés Moncada, Ligia, additional, Reyes, Patricia, additional, and Darío Heredia, Rubén, additional
- Published
- 2015
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