Ivan Dario Velez - Independent Researcher

Ivan Dario Velez - Independent Researcher
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Artículo original A PCR assay for the identification of Leishmania species of the Viannia subgenus
Revista de la Sociedad Venezolana …
, 2011
We have identified a novel DNA sequence of 500 bp (β500-DNA) on the Leishmania (Viannia) subgenus...
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We have identified a novel DNA sequence of 500 bp (β500-DNA) on the Leishmania (Viannia) subgenus, located in the intergenic region of one of the loci of the β-tubulin gene family. The sequence analysis showed that this sequence has no homology to any other sequence described so far, including the β-tubulin gene. We improved a specific β500-PCR assay, which generated a PCR product of 375 bp for total genomic DNA from Leishmania strains belonging to the L. (Viannia) subgenus. In contrast, no amplification was found when using genomic DNA from species of L. (Leishmania) subgenus or other organisms. Under our PCR conditions, the lower detection limit was 1 fg when a purified DNA clone (pLgβ4), which contains one copy of the β500-DNA sequence, was used. The β500-DNA PCR assay confirmed the preliminary diagnosis of cutaneous leishmaniasis in clinical samples in which the Montenegro skin test was positive and parasite cultures were negative. The analytical specificity and the sensitivity of the PCR assay provide a tool for epidemiological studies of the disease.
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The β500-PCR assay exhibited high sensitivity and specificity for detecting L. (Viannia) parasites in clinical samples.
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Improving the COI DNA barcoding library for Neotropical phlebotomine sand flies (Diptera, Psychodidae)
Research Square (Research Square)
, Feb 3, 2023
Background: Sand y species are traditionally identi ed using morphological traits, thought this m...
more
Background: Sand y species are traditionally identi ed using morphological traits, thought this method is hampered by the presence of cryptic species. DNA barcoding is a widely used tool in the case of insects of medical importance, where it is necessary to know quickly which species are present in a transmission area. Here, we assess the usefulness of COI DNA barcoding as a practical tool for species identi cation, correct assignment of isomorphic females, and to evaluate the detection of cryptic diversity that occurs in the same species. Results: A fragment of the mitochondrial cytochrome c oxidase subunit I (COI) gene was used to generate 156 new barcode sequences for sand ies from different countries of the Neotropical region, mainly Colombia, which had been identi ed morphologically as 43 species. The sequencing of the COI gene allowed the detection of cryptic diversity within species and correctly associated isomorphic females with males identi ed by morphology. The maximum intraspeci c genetic distances ranged from 0 to 8.32% and 0 to 8.92% using uncorrected p distances and the K2P model, respectively. The minimum interspeci c distance (nearest neighbor) for each species ranged from 1.5 to 14.14% and 1.51 to 15.7% using p and K2P distances, respectively. Three species had more than 3% maximum intraspeci c distance: Psychodopygus panamensis, Micropygomyia cayennensis cayennensis, and Pintomyia evansi. They also were splitted into at least two MOTUs each, using different species delimitation algorithms. Regarding interspeci c genetic distances, the species of the genera Nyssomyia and Trichophoromyia generated values lower than 3% (except Ny. ylephiletor and Ny. trapidoi). However, the maximum intraspeci c distances did not exceed these values, indicating the presence of a barcode gap despite their proximity. Also, nine sand y species were DNA barcoded for the rst time: Evandromyia georgii, Lutzomyia sherlocki, Ny. ylephiletor, Ny. yuilli pajoti, Psathyromyia punctigeniculata, Sciopemyia preclara, Trichopygomyia triramula, Trichophoromyia howardi, and Th. velezbernali. Conclusions: The COI DNA barcode analysis allowed the correct delimitation of several Neotropical sand y species from South and Central America and raised questions about the presence of cryptic species for some taxa, which should be further assessed.
In vitro and in vivo antileishmanial activity of Artemisia annua L. leaf powder and its potential usefulness in the treatment of uncomplicated cutaneous leishmaniasis in humans
Revista Da Sociedade Brasileira De Medicina Tropical
, Feb 1, 2017
Introduction: Cutaneous leishmaniasis (CL) is a tropical disease that affects millions of individ...
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Introduction: Cutaneous leishmaniasis (CL) is a tropical disease that affects millions of individuals worldwide. The current drugs for CL may be effective but have serious side effects; hence, alternatives are urgently needed. Although plant-derived materials are used for the treatment of various diseases in 80% of the global population, the validation of these products is essential. Gelatin capsules containing dried Artemisia annua L. leaf powder were recently developed as a new herbal formulation (totum) for the oral treatment of malaria and other parasitic diseases. Here, we aimed to determine the usefulness of A. annua gel capsules in CL. Methods: The antileishmanial activity and cytotoxicity of A. annua L. capsules was determined via in vitro and in vivo studies. Moreover, a preliminary evaluation of its therapeutic potential as antileishmanial treatment in humans was conducted in 2 patients with uncomplicated CL. Results: Artemisia annua L. capsules showed moderate in vitro activity in amastigotes of Leishmania (Viannia) panamensis; no cytotoxicity in U-937 macrophages or genotoxicity in human lymphocytes was observed. Five of 6 (83.3%) hamsters treated with A. annua capsules (500mg/kg/day) for 30 days were cured, and the 2 examined patients were cured 45 days after initiation of treatment with 30g of A. annua L. capsules, without any adverse reactions. Both patients remained disease-free 26 and 24 months after treatment completion. Conclusion: Capsules of A. annua L. represent an effective treatment for uncomplicated CL, although further randomized controlled trials are needed to validate its efficacy and safety.
Improving the COI DNA barcoding library for Neotropical phlebotomine sand flies (Diptera: Psychodidae)
Parasites & Vectors
, Jun 12, 2023
Sand fly species are traditionally identified using morphological traits, though this method is h...
more
Sand fly species are traditionally identified using morphological traits, though this method is hampered by the presence of cryptic species. DNA barcoding is a widely used tool in the case of insects of medical importance, where it is necessary to know quickly which species are present in a transmission area. Here, we assess the usefulness of mitochondrial cytochrome c oxidase subunit I (COI) DNA barcoding as a practical tool for species identification, correct assignment of isomorphic females, and to evaluate the detection of cryptic diversity that occurs in the same species. A fragment of the COI gene was used to generate 156 new barcode sequences for sand flies from different countries of the Neotropical region, mainly Colombia, which had been identified morphologically as 43 species. The sequencing of the COI gene allowed the detection of cryptic diversity within species and correctly associated isomorphic females with males identified by morphology. The maximum intraspecific genetic distances ranged from 0 to 8.32% and 0 to 8.92% using uncorrected p distances and the Kimura 2-parameter (K2P) model, respectively. The minimum interspecific distance (nearest neighbor) for each species ranged from 1.5 to 14.14% and 1.51 to 15.7% using p and K2P distances, respectively. Three species had more than 3% maximum intraspecific distance: Psychodopygus panamensis, Micropygomyia cayennensis cayennensis, and Pintomyia evansi. They also were split into at least two molecular operational taxonomic units (MOTUs) each, using different species delimitation algorithms. Regarding interspecific genetic distances, the species of the genera Nyssomyia and Trichophoromyia generated values lower than 3% (except Nyssomyia ylephiletor and Ny. trapidoi). However, the maximum intraspecific distances did not exceed these values, indicating the presence of a barcode gap despite their proximity. Also, nine sand fly species were DNA barcoded for the first time: Evandromyia georgii, Lutzomyia sherlocki, Ny. ylephiletor, Ny. yuilli pajoti, Psathyromyia punctigeniculata, Sciopemyia preclara, Trichopygomyia triramula, Trichophoromyia howardi, and Th. velezbernali. The COI DNA barcode analysis enabled the correct delimitation of several Neotropical sand fly species from South and Central America and raised questions about the presence of cryptic species for some taxa, which should be further assessed.
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Sequencing produced a 601 base pair consensus COI fragment, with maximum intraspecific distances ranging from 0-8.92%.
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El reto de ganar credibilidad para poder innovar desde la provincia
Biomedica
, Jun 30, 2023
Colombia es un país que invierte muy poco en investigación, menos del 0,3 % del producto interno ...
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Colombia es un país que invierte muy poco en investigación, menos del 0,3 % del producto interno bruto (PIB) por lo que está condenado a seguir en su dependencia tecnológica y al subdesarrollo. Iniciativas esporádicas, temporales y focalizadas han tratado de cambiar este panorama y lograr, al menos, que alguna ciudad o región sirva de ejemplo y muestre que sí es posible investigar, innovar, transformarse y ser competitivos, independientemente de las aberrantes políticas nacionales donde la ciencia, la tecnología y la innovación son las cenicientas en las prioridades del Estado. Ya hace más de 20 años que la llamada Primera Comisión de Sabios, luego de un trabajo juicioso, trazó un rumbo para que Colombia, por fin, fuera un país innovador y pidió que en pocos años la inversión en Ciencia y Tecnología fuera del orden del 3 % del PIB. Sin embargo, como se dijo, en el año 2023 está inversión no llega al 0,3 % con tendencia a disminuir en los próximos años.
Cutaneous leishmaniasis and co-morbid major depressive disorder: A systematic review with burden estimates
PLOS Neglected Tropical Diseases
, Feb 25, 2019
Major depressive disorder (MDD) associated with chronic neglected tropical diseases (NTDs) has be...
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Major depressive disorder (MDD) associated with chronic neglected tropical diseases (NTDs) has been identified as a significant and overlooked contributor to overall disease burden. Cutaneous leishmaniasis (CL) is one of the most prevalent and stigmatising NTDs, with an incidence of around 1 million new cases of active CL infection annually. However, the characteristic residual scarring (inactive CL) following almost all cases of active CL has only recently been recognised as part of the CL disease spectrum due to its lasting psychosocial impact. We performed a multi-language systematic review of the psychosocial impact of active and inactive CL. We estimated inactive CL (iCL) prevalence for the first time using reported WHO active CL (aCL) incidence data that were adjusted for life expectancy and underreporting. We then quantified the disability (YLD) burden of co-morbid MDD in CL using MDD disability weights at three severity levels. Overall, we identified 29 studies of CL psychological impact from 5 WHO regions, representing 11 of the 50 highest burden countries for CL. We conservatively calculated the disability burden of co-morbid MDD in CL to be 1.9 million YLDs, which equalled the overall (DALY) disease burden (assuming no excess mortality in depressed CL patients). Thus, upon inclusion of co-morbid MDD alone in both active and
Article Synthesis, Leishmanicidal and Cytotoxic Activity of Triclosan-Chalcone, Triclosan-Chromone and
Twelve hybrids derived from triclosan were obtained via Williamson etherification of O-triclosan ...
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Twelve hybrids derived from triclosan were obtained via Williamson etherification of O-triclosan alkyl bromide plus chalcone and O-coumarin or O-chromone alkyl bromide plus triclosan, respectively. Structures of the products were elucidated by spectroscopic analysis. The synthesized compounds were evaluated for antileishmanial activity against L. (V) panamensis amastigotes. Cytotoxic activity was also evaluated against mammalian U-937 cells. Compounds 7-9 and 17, were active against Leishmania parasites (EC 50 = 9.4; 10.2; 13.5 and 27.5 µg/mL, respectively) and showed no toxicity toward mammalian cells (>200 µg/mL). They are potential candidates for antileishmanial drug development. Compounds 25-27, were active and cytotoxic. Further studies using other cell types are needed in order to discriminate whether the toxicity shown by these compounds is against tumor or non-tumor cells. The results indicate that compounds containing small alkyl chains show better selectivity indices. Moreover, Michael acceptor moieties may modify both the leishmanicidal activity and cytotoxicity. Further studies are required to evaluate if the in vitro activity against Leishmania panamensis demonstrated here is also observed in vivo.
Establecimiento de la infección con Wolbachia en los mosquitos Aedes aegyti de Bello, Medellín e Itaguí (Colombia), y su impacto en el control de la transmisión del dengue y otros arbovirus
Diagnóstico
En las ciudades de Bello, Medellín e Itagüí, localizadas en el Valle del Aburrá, la liberación co...
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En las ciudades de Bello, Medellín e Itagüí, localizadas en el Valle del Aburrá, la liberación controlada durante 20 semanas de mosquitos Aedes aegypti criados en el laboratorio e infectados con la bacteria Wolbachia logró el establecimientode esta bacteria en la mayoría de las poblaciones locales de este mosquito, lo que ha llevado al control de la transmisión dedengue, medida por series de tiempo antes y después de las liberaciones y con un estudio caso-control, y que estas ciudadespresenten el menor número de casos desde el 2001, año en que se inició la notificación obligatoria de casos.
Nanoemulsions for increased penetrability and sustained release of leishmanicidal compounds
Archiv der Pharmazie
In the last decade, the World Health Organization has driven the development of drugs for topical...
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In the last decade, the World Health Organization has driven the development of drugs for topical use in patients with cutaneous leishmaniasis (CL), the most prevalent clinical form of leishmaniasis, a neglected tropical disease. The chemicals C6I, TC1, and TC2 were reported as promising antileishmanial drugs. We aimed to develop a topical nanoformulation that enhances the advantageous effect of C6I, TC1, and TC2, guaranteeing higher stability and bioavailability of the pharmacologically active components through the topical route. Nanoemulsions were prepared by ultrasonication based on oleic acid (0.5 g). A relation of Tween®‐80/ethanol (1:3) and water was obtained; physicochemical characterization of all formulations was performed, and the preliminary stability and transdermal penetration of these nanoemulsions were also investigated. Newtonian‐type fluids with high load capacity, 147–273 nm globule size, and −15 to −18 mV zeta potential were obtained with differential permeabilit...
Diversity and temporal distribution of sand flies in an endemic area of cutaneous leishmaniasis in Centre-West Colombia
Journal of Medical Entomology
The community structure of sand flies indicates the level of adaptation of vector species in a re...
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The community structure of sand flies indicates the level of adaptation of vector species in a region, and in the context of vector management and control, this information allows for identifying the potential risks of pathogen transmission. This study aimed to analyze sand fly diversity and spatial-temporal distribution in an endemic area of cutaneous leishmaniasis. The study was carried out in the Carrizales hamlet (Caldas), between September 2019 and October 2021. The monthly distribution of sand fly species was evaluated through collections with CDC traps. Shannon and evenness indices were calculated and used to compare species frequencies at each house. The association between climatic variables and the frequency of sand flies was evaluated using Spearman’s correlation. A total of 6,265 females and 1,958 males belonging to 23 species were found. Low diversity and evenness were observed, with the dominance of Nyssomyia yuilli yuilli (Young & Porter). Ecological and diversity ind...
Cutaneous leishmaniasis treatment and therapeutic outcomes in special populations: A collaborative retrospective study
PLOS Neglected Tropical Diseases
Background Treatment guidance for children and older adult patients affected by cutaneous leishma...
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Background Treatment guidance for children and older adult patients affected by cutaneous leishmaniasis (CL) is unclear due to limited representation of these groups in clinical trials. Methods We conducted a collaborative retrospective study to describe the effectiveness and safety of antileishmanial treatments in children ≤ 10 and adults ≥ 60 years of age, treated between 2014 and 2018 in ten CL referral centers in Latin America. Results 2,037 clinical records were assessed for eligibility. Of them, the main reason for non-inclusion was lack of data on treatment follow-up and therapeutic response (182/242, 75% of children and 179/468, 38% of adults). Data on 1,325 eligible CL patients (736 children and 589 older adults) were analyzed. In both age groups, disease presentation was mild, with a median number of lesions of one (IQR: 1–2) and median lesion diameter of less than 3 cm. Less than 50% of the patients had data for two or more follow-up visits post-treatment (being only 28% ...
Búsqueda de sustancias antiparasitarias de la flora colombiana
Actualidades Biológicas
En este trabajo se analiza la funcionalidad de una investigación dirigida hacia la búsqueda de su...
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En este trabajo se analiza la funcionalidad de una investigación dirigida hacia la búsqueda de sustancias antiparasitarias de la flora colombiana, sus fundamentos y desarrollo. Además se presentan los criterios de selección de los materiales promisorios del proyecto así como de otros ejemplos reportados en la literatura.
Study of the genetic structure of the Colombian amerind population
Medellin
, 1999
IP 1115-05-132-9
El drama de las enfermedades tropicales desatendidas
Biomedica
, Aug 1, 2018
Utility of the combination of hederagenin glucoside saponins and chromane hydrazone in the topical treatment of canine cutaneous leishmaniasis. An observational study
Parasitology Research
, 2022
Canine cutaneous leishmaniasis (CCL) is an emerging zoonotic infection endemic in several countri...
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Canine cutaneous leishmaniasis (CCL) is an emerging zoonotic infection endemic in several countries of the world. Due to variable response to therapy and frequency of relapses, a more effective, safer, and inexpensive treatment is needed. Recently, it was reported that the hederagenin glucoside saponins (SS) and chromane-derived hydrazone (TC2) combined in a 1:1 ratio has high potential in antileishmanial therapy since both compounds alter the survival of Leishmania and the ability to infect adjacent macrophage. Not only the skin permeation and the absorption of an ointment containing 2% TC2 and 2% SS (w/w) was determined in this work, but also the acute dermal toxicity in both in vitro and in vivo assays. Last, the effectiveness and safety of the topical therapy with 2% TC2-2% SS ointment was evaluated in an observational study in dogs with diagnosis of cutaneous leishmaniasis (CL). Both TC2 and SS diffused through pig ear skin and traces of TC2 (but not SS) were detected in the stratum corneum of mice at 6-24 h. Neither TC2 nor SS was detected in plasma. The acute dermal toxicity was negative. Treatment with 2% TC2-2% SS ointment produced a complete long-term clinical cure in 56 dogs (24 females and 32 males) from the Orinoco and Amazonas regions in southeastern Colombia without adverse effects. All dogs have remained disease-free for the last 24 months. In conclusion, these results support the use of this topical therapy as a safer and new first-line local treatment of CCL that could help limit the spread of CL from dogs to humans.
The camera trap as a powerful tool for mammal sightings to improve the knowledge of species distribution and diversity records in Colombia
DNA barcoding of Lutzomyia longipalpis species complex (Diptera: Psychodidae), suggests the existence of 8 candidate species
Acta Tropica
, 2021
The sand fly Lutzomyia (L.) longipalpis has been implicated as the primary vector of Leishmania i...
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The sand fly Lutzomyia (L.) longipalpis has been implicated as the primary vector of Leishmania infantum, the causative agent of visceral leishmaniasis VL. In addition, it has been associated with atypical cutaneous leishmaniasis transmission in the Neotropic and Central America, respectively. The existence of a L. longipalpis complex species has been suggested with important implications for leishmaniasis epidemiology; however, the delimitation of species conforming it remains a topic of controversy. The DNA Barcoding Initiative based on cox1 sequence variation was used to identify the MOTUs in L. longipalpis including previously described L. pseudolongipalpis. The genetic variation was analyzed based on tree and distance methods. Fifty-five haplotypes were obtained from 103 sequences which were assigned to MOTUs, with a clear separation and a high correspondence of individuals to the groups. Maximum likelihood and Bayesian phylogenetic analysis showed eight MOTUs (100% bootstrap) with high genetic divergence (12.6%). Data obtained in the present study suggest that L. longipalpis complex consists of at least 8 lineages that may represent species. It would be desirable perform additional morphological and molecular analysis of L. longipalpis from Colosó (Caribbean ecoregion) considering that specimens from that area were grouped with L. pseudolongipalpis one of the complex species previously described from Venezuela, which has not been registered in Colombia.
New thiazolyl‐pyrazoline derivatives bearing nitrogen mustard as potential antimicrobial and antiprotozoal agents
Archiv der Pharmazie
, 2020
A new series of N‐substituted pyrazoline derivatives 6a–g, 7a–g, 8a–g, and 9a–g was synthetized b...
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A new series of N‐substituted pyrazoline derivatives 6a–g, 7a–g, 8a–g, and 9a–g was synthetized by reaction of hydrazine derivatives and chalcone–thiazole hybrids bearing nitrogen mustard 5a–g. The chalcones 5a–g were obtained by Claisen–Schmidt condensation of thiazole‐2‐nitrogen mustard 3 and selected acetophenones 4a–g. These new compounds 6/7/8/9a–g were screened for their antifungal activity against Cryptococcus neoformans, with IC50 values of 3.9–7.8 µg/ml for the N‐3,5‐dichlorophenyl pyrazolines 9e–g. Interestingly, those compounds show low cytotoxic effects toward erythrocytes (RBC). In addition, N‐acetyl (6a,b) and N‐formyl pyrazolines (7a, 7b, 7c, and 7g) showed inhibitory activity against methicillin‐susceptible Staphylococcus aureus, methicillin‐resistant S. aureus, and vancomycin‐intermediate S. aureus, with the most important minimum inhibitory concentration values ranging from 31.25 to 125 µg/ml. Regarding the antiprotozoal activity, thiazolyl‐pyrazolines 9g, 8f, and ...
A new high-resolution melting analysis for the detection and identification of Plasmodium in human and Anopheles vectors of malaria
Scientific Reports
, 2019
Among vector-borne diseases malaria is the leading cause of morbidity in the world, with more tha...
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Among vector-borne diseases malaria is the leading cause of morbidity in the world, with more than 200 million cases per year and a large number of deaths. The techniques traditionally used for the detection of Plasmodium in humans and Anopheles mosquitoes include microscopy, IRMA, ELISA, antibody or molecular assays, and anopheline dissection. However, these techniques are limited by their requirement of skilled personnel, low sensitivity or long processing times. A PCR-based high-resolution melting (PCR-HRM) analysis was developed for the detection and identification of P. falciparum, P. vivax and P. malariae that infect humans and Anopheles. In 41 human samples PCR-HRM detected 14 samples positive for P. vivax, 17 for P. falciparum, three for P. malariae, three mixed infections for P. vivax/P. malariae and four negative samples. Whereas benchmarking assays of microscopy and nested PCR had false positive detections. Additionally, PCR-HRM was able to detect natural infection with P...
El niño, oscilación del sur (ENOS), con relación a la transmisión de malaria, densidad y paridad de An. albimanus y An. darlingi (diptera: culicidae) en dos regiones …
Iatreia
, 2000
Una fuerte asociación ha sido registrada entre los incrementos en la transmisiónas forzadas por e...
more
Una fuerte asociación ha sido registrada entre los incrementos en la transmisiónas forzadas por el fenómeno El Niño. Entre las posibles explicaciones para esta asociación está el efecto del clima sobre la dinámica de población de vectores, por ejemplo, generando cambios ...
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