Universidad del Rosario
  • Bogotá, Cundinamarca, Colombia
Recent publications
Autoimmunity has emerged as a characteristic of the post-COVID syndrome (PCS), which may be related to sex. In order to further investigate the relationship between SARS-CoV-2 and autoimmunity in PCS, a clinical and serological assessment on 100 patients was done. Serum antibody profiles against self-antigens and infectious agents were evaluated by an antigen array chip for 116 IgG and 104 IgM antibodies. Thirty pre-pandemic healthy individuals were included as a control group. The median age of patients was 49 years (IQR: 37.8 to 55.3). There were 47 males. The median post-COVID time was 219 (IQR: 143 to 258) days. Latent autoimmunity and polyautoimmunity were found in 83% and 62% of patients, respectively. Three patients developed an overt autoimmune disease. IgG antibodies against IL-2, CD8B, and thyroglobulin were found in more than 10% of the patients. Other IgG autoantibodies, such as anti-interferons, were positive in 5–10% of patients. Anti-SARS-CoV-2 IgG antibodies were found in > 85% of patients and were positively correlated with autoantibodies, age, and body mass index (BMI). Few autoantibodies were influenced by age and BMI. There was no effect of gender on the over- or under-expression of autoantibodies. IgG anti-IFN-λ antibodies were associated with the persistence of respiratory symptoms. In summary, autoimmunity is characteristic of PCS, and latent autoimmunity correlates with humoral response to SARS-CoV-2.
Background There are few data on the clinical outcomes of patients with coronavirus disease 2019 (COVID-19) in cities over 1000 m above sea level (masl). Objectives To describe the clinical characteristics and mortality of patients with COVID-19 treated at a high complexity hospital in Bogotá, Colombia, at 2640 masl. Methods This was an observational study of a cohort including 5161 patients with confirmed COVID-19 infection from 19 March 2020 to 30 April 2021. Demographic data, laboratory values, comorbidities, oxygenation indices, and clinical outcomes were collected. Data were compared between survivors and nonsurvivors. An independent predictive model was performed for mortality and invasive mechanical ventilation (IMV) using classification and regression trees (CART). Results The median cohort age was 66 years (interquartile range (IQR) 53–77), with 1305 patients dying (25%) and 3856 surviving (75%). The intensive care unit (ICU) received 1223 patients (24%). Of 898 patients who received IMV, 613 (68%) of them perished. The ratio of partial pressure arterial oxygen (PaO 2 ) to fraction inspired oxygen (FiO 2 ), or the P/F ratio, upon ICU admission was 105 (IQR 77–146) and 137 (IQR 91–199) in the deceased and survivors, respectively. The CART model showed that the need for IMV, age greater than 79 years, ratio of oxygen saturation (SaO 2 ) to FiO 2 , or the S/F ratio, less than 259, and lactate dehydrogenase (LDH) greater than 617 U/L at admission were associated with a greater probability of death. Conclusion Among more than 5000 patients with COVID-19 treated in our hospital, mortality at hospital discharge was 25%. Older age, low S/F ratio, and high LDH at admission were predictors of mortality.
Background AQUILA (NCT03470103) was a prospective, observational, 12-month cohort study to understand treatment patterns and to evaluate the clinical effectiveness and safety of intravitreal aflibercept (IVT-AFL) in patients from Latin America with diabetic macular edema (DME). Methods Treatment-naïve and previously treated (switching to IVT-AFL) patients (aged ≥ 18 years) were enrolled from March 2018, with a primary completion date of September 2020, from Argentina, Colombia, Costa Rica and Mexico. Patients received IVT-AFL in a routine clinical practice setting. Results Of 258 patients in the full analysis set, 181 were treatment-naïve and 77 had received previous treatment. The mean ± standard deviation number of IVT-AFL injections by Month 12 was 3.7 ± 1.8 (treatment-naïve) and 4.0 ± 2.2 (previously treated). The median duration from diagnosis to IVT-AFL treatment was 1.8 months (treatment-naïve) and 16.0 months (previously treated). Mean best-corrected visual acuity (Early Treatment Diabetic Retinopathy Study letters) improved from baseline to Month 12 by + 8.1 ± 17.7 (treatment-naïve; baseline: 54.5 ± 19.4) and + 4.6 ± 15.4 letters (previously treated; baseline: 52.9 ± 18.6). Conclusion AQUILA is the first study to assess the use of IVT-AFL in routine clinical practice in Latin America. Despite few patients being treated with the label-recommended regimen of 5 initial monthly doses or receiving ≥ 8 injections in 12 months, functional and anatomic visual outcomes improved during 12 months of treatment with IVT-AFL. Patients receiving the label-recommended number of injections had numerically greater improvements in visual acuity outcomes. Patients with DME treated regularly and more frequently with IVT-AFL therefore have the potential to achieve outcomes consistent with those observed in interventional studies. Trial registration Clinicaltrials.gov, NCT03470103. Registered February 5, 2018, https://clinicaltrials.gov/ct2/show/NCT03470103
Dilemmas related to the use of environmental resources concern diverse populations at local or global scales. Frequently, individuals are unable to visualize the consequences of their actions, where they belong in the decision-making line, and have no information about past choices or the time horizon. We design a new one-shot extraction game to capture these dynamic decisions. We present results from a nationwide common pool resource experiment, conducted simultaneously in eleven French cities, involving a total of 2813 participants. We examine, for the first time, the simultaneous impact of several variables on the amount of resource extracted: the local vs. the national scale of the resource, the size of the group (small vs. big), the low vs. high recovery rate of the resource, and the available information. We show that individuals significantly reduce extraction levels in local as compared to national level dilemmas and that providing recommendations on sustainable extraction amounts significantly improves the sustainability of the resource. Overall, women extract significantly less, but care more about preserving the local resource; older participants extract significantly more resources but extract less from the national resource. Our experiment also fulfills a science popularization pedagogical aim, which we discuss.
Objectives We assessed the impact of a recently reported nutritional quality improvement program (QIP) on healthcare resource utilization and costs for older, community-living adults in Bogotá, Colombia. Methods The study included 618 community-dwelling, older adults (> 60 years) who were at risk or malnourished and receiving outpatient clinical care. The intervention was a QIP that emphasized nutritional screening, dietary education, lifestyle counseling, 60-day consumption of oral nutritional supplements, and 90-day follow-up. For economic modeling, we performed 90-day budget impact and cost-effectiveness analyses from a Colombian third-party payer perspective. The base-case analysis quantified mean healthcare resource use in the QIP study population. Analysis was based on mean input values (deterministic) and distributions of input parameters (probabilistic). As the deterministic analysis provided a simple point estimate, the cost-effectiveness analysis focused on the probabilistic results informed by 1000 iterations of a Monte-Carlo simulation. Results Results showed that the total use of healthcare resources over 90 days was significantly reduced by > 40% (hospitalizations were reduced by approximately 80%, emergency department visits by > 60%, and outpatient clinical visits by nearly 40%; P < .001). Based on economic modeling, total cost savings of $129 740 or per-patient cost savings of $210 over 90 days could be attributed to the use of nutritional QIP strategies. Total cost savings equated to nearly twice the initial investment for QIP intervention; that is, the per-dollar return on investment was $1.82. Conclusions For older adults living in the community in Colombia, the use of our nutritional QIP improved health outcomes while lowering costs of healthcare and was thus cost-effective.
Right atrial masses raised pose 3 major possibilities including tumors, thrombi, or vegetations. We present 2 cases: first, a 34-year-old male with no medical history, who presented with dyspnea, pleuritic pain, and fever; and the second, 65-year-old male with similar symptoms and a history of a left renal carcinoma. Both patients had right atrial masses found on a transthoracic echocardiogram. Cardiac magnetic resonance imaging and an 18 FDG-PET were necessary finding thrombi in the first patient; and tumoral thrombi in the second one. A multimodality imaging approach to right atrial masses is essential for proper diagnosis and therapeutic decision-making.
There is a complex interplay of criminal groups’ control over land, illicit activities, and forest cover change in the Colombian Andes-Amazon region. This area is dealing with diverse forms of conflict and peace, directly impacting landscape connectivity. While many studies have documented rapid deforestation after the peace agreement in 2016, we know little about the effect of these socio-political changes on the state of landscape connectivity. We disentangle habitat from connected habitat in forest ecosystems using the Landsat archive and landscape connectivity indices. We find that in the Andes-Amazon region during 2000–2020, connected habitat loss reached 18%, while habitat loss was 13%. This result is worrisome because it indicates that well-connected patches are more fragmented and isolated, affecting the natural connections between the Andes and Amazon biogeographical regions and the movement ability of species. The Colombian government should conduct a strategic peacebuilding process incorporating structural changes that prevent the increase of large-scale extractive activities that are often illegal in the region. While finding a balance between extractive activities and conservation remains a big challenge, legal land tenure, census/taxation, and specific agreements with local actors can initially prevent deforestation. We discourage localized military actions and the return of aerial fumigation of coca fields, which rather than stop deforestation might exacerbate land cover change deeper into pristine forests.
Deadwood is a large global carbon store with its store size partially determined by biotic decay. Microbial wood decay rates are known to respond to changing temperature and precipitation. Termites are also important decomposers in the tropics but are less well studied. An understanding of their climate sensitivities is needed to estimate climate change effects on wood carbon pools. Using data from 133 sites spanning six continents, we found that termite wood discovery and consumption were highly sensitive to temperature (with decay increasing >6.8 times per 10°C increase in temperature)-even more so than microbes. Termite decay effects were greatest in tropical seasonal forests, tropical savannas, and subtropical deserts. With tropicalization (i.e., warming shifts to tropical climates), termite wood decay will likely increase as termites access more of Earth's surface.
Poster session 1, September 21, 2022, 12:30 PM - 1:30 PM Background Cryptococcus neoformans (Cn), predominantly, and Cryptococcus gattii (Cg) cause cryptococcosis, a life-threatening systemic mycosis of global distribution affecting mainly immunocompromised adults. Objectives This study aimed to determine total and specific antibodies against C. neoformans and C. gattii antigens in sera from patients with cryptococcosis and from healthy individuals from Colombia, which will help to elucidate sero-epidemiological variations in the incidence of the disease in the country. Methods Sera from child and adult patients with cryptococcosis (n = 109) and sera from healthy children and adults from Colombia (n = 119) were studied. Using ELISA, total and Cn- and Cg-specific levels of immunoglobulin (Ig)G, IgA, and IgM were determined in sera. Results Total IgG, IgA, and IgM levels were higher in HIV + compared with HIV− patients with cryptococcosis. Specific IgG, IgA, and IgM levels tended to be higher in cryptococcosis patients than in healthy controls and to be higher in adults than in children, with a positive correlation between antibody reactivity and age. All serum immunoglobulins were more reactive against Cn-proteins than Cg-proteins. Including all samples, a positive correlation between total and specific IgG, IgA, and IgM levels was found. Conclusions In cryptococcosis patients from Colombia, serum immunoglobulins levels differ depending on HIV status, as reported previously. However, this study shows for the first-time variations in immunoglobulin production among adults and children with cryptococcal disease and between Cn and Cg-protein antigens. The observation of differential antibody reactivity with cryptococcal proteins encourages further studies of the humoral immunity for host defense against cryptococcosis.
Poster session 1, September 21, 2022, 12:30 PM - 1:30 PM Objectives Host defense peptides (HDP) are produced by a diversity of beetles. The aims of this work were (1) to find new promising peptides from the Coleoptera family Scarabaeidae with potential biomedical applications, (2) to modify physicochemical and structural characteristics of one of the most promissory peptides in order to improve its antimicrobial properties, and (3) to evaluate the in vitro activity of the HDPs against reference strains of pathogenic Candida and Cryptococcus yeasts. Materials and Methods From the Scarabaeidae family transcriptome, 14 promising HDPs were identified. Subsequently, we designed 19 new sequences from Act8 peptide modifying the net charge, hydrophobic angle, and the general composition of amino acids, among other properties, in order to improve the HDPs antifungal activity. The in vitro antifungal susceptibility of the 33 HDPs against C. albicans SC5314, C. krusei, ATCC 6558, C. parapsilosis ATCC 22019, C. glabrata ATCC 2001, C. tropicalis ATCC 750, C. neoformans H99, and C. gattii H0058-I-2029 isolates were evaluated by broth microdilution, with a concentration ranging from 0.19 to 50 μg/ml. Results All 14 peptides identified showed in vitro activity against C. krusei, C. parapsilosis, and C. glabrata. One peptide showed in vitro activity against C. albicans, 6 against C. tropicalis, 11 against C. neoformans and 13 against C. gattii. As well the 19 modified peptides showed in vitro activity against C. krusei, C. parapsilosis, C. tropicalis, C. neoformans, and C. gattii. A total of 15 modified peptides showed in vitro activity against C. albicans, and 3 against C. glabrata. MIC ranges per species and per peptide are shown in Table 1. Conclusions The HDPs herein analyzed showed a significant in vitro antifungal activity against six Candida and two Cryptococcus pathogenic species. Our findings encourage further work with in vivo experimental models in order to better understand the action mechanisms of these antimicrobial peptides. HDPs from different species are becoming a promising therapeutic alternative in the control of fungal infections.
S8.5 Genotyping of Cryptococcus neoformans and C. gattii, September 23, 2022, 3:00 PM - 4:30 PM Introduction: Cryptococcosis is a worldwide mycosis caused by Cryptococcus neoformans and Cryptococcus gattii. Although resistance to antifungals is infrequent, isolates with decreased susceptibility to fluconazole have been reported globally, including Colombia, which may be due to 1) heteroresistance, defined as the ability to adapt to increasing concentrations of this azolic antifungal, and 2) point mutations in the EGR11 gene encoding the fluconazole target enzyme, lanosterol 14-α-demethylase. Objective: To determine the development of heteroresistance to fluconazole in C. neoformans and C. gattii clinical isolates from Colombia and to amplify and sequence the ERG11 gene of the isolates to seek for mutations that might characterize resistant or heteroresistant phenotypes. Methods The minimum inhibitory concentration (MIC) to fluconazole was determined in 31 and 24 isolates of C. neoformans and C. gattii, respectively, using broth microdilution. Heteroresistance was evaluated by plating each isolate on YPD agar that contained fluconazole at concentrations equal to the MIC of each isolate. Heteroresistant colonies were then replated at increasing concentrations of fluconazole, as high as 128 μg/ml. Results All isolates were susceptible to fluconazole with MICs of 1 μg/ml (n = 3), 2 μg/ml (n = 6), 4 μg/ml (n = 17), 8 μg/ml (n = 23), 16 μg/ml (n = 5), and 32 μg/ml (n = 1). However, all isolates developed heteroresistant colonies, with increments in the MIC from 2 to 6 dilutions. Notably, 5 (16.1%) isolates of C. neoformans and 8 (33.3%) of C. gattii, grew up to 64 μg/ml of fluconazole, which is the MIC that defines resistance to this azole, and 1 (3,2%) isolate of C. neoformans and 4 (16.7%) of C. gattii grew up to 128 μg/ml of fluconazole. Currently, the ERG11 gene is being amplified for further sequencing. Conclusion: clinical isolates of C. neoformans and C. gattii that develop heteroresistance to fluconazole in high concentrations circulate in Colombia, which is important since this characteristic contributes to the relapse of cryptococcosis during therapy with this triazole.
Poster session 1, September 21, 2022, 12:30 PM - 1:30 PM Background Candidiasis is one of the most frequent opportunistic infections in immunosuppressed and/or hospitalized patients. In countries like Colombia, candidiasis is associated with a mortality rate of ∼ 46%. Growing pharmacological resistance of Candida spp., and the appearance of the emerging pathogen Candida auris, have turned candidiasis into a major public health problem. Different types of antimicrobial peptides have been investigated as a therapeutic alternative to control candidiasis effectively and safely. Objective This work aimed at evaluating the in vitro antifungal activity of three synthetic antimicrobial peptides (35 409, 1609, and 29 009) obtained from Plasmodium falciparum Rif1 protein against C. auris, C. albicans, C. glabrata, C. parapsilosis, C. krusei, and C. tropicalis, species with worldwide clinical importance. Methods The minimum inhibitory concentrations (MIC) of the three peptides against Candida species were determined by the plate microdilution method; the peptides’ effect on biofilm formation in C. auris and C. albicans species was also evaluated through the XTT metabolic activity assay. Additionally, the structural damages in C. auris and C. albicans caused by the action of the peptides were observed by transmission electron microscopy (TEM) and finally, the in vitro peptides’ cytotoxicity against L929 murine fibroblasts was verified. Results Our findings showed that the three peptides herein evaluated, displayed antifungal activity in both planktonic and sessile Candida cells. Likewise, the TEM evidenced morphological alterations induced by the peptides, both in the membrane and at the intracellular level of the yeasts. As well, total safety against the murine cell line L929 with 24 h of treatment was observed. Conclusions From these results, we conclude that the antimicrobial peptides 35 409, 1609, and 29 009 are potential therapeutic alternatives against the most important Candida species in Colombia and the world.
S5.4 Free oral paper session, September 22, 2022, 3:00 PM - 4:30 PM Objective: Recent genome-wide genotype-phenotype association studies (GWAS) of sets of clinical fungal isolates have reported problems resulting from strong phylogenetic clustering (apparent quasi-clonal population structure, difficulties in localizing association signals on chromosomes). We wished to directly investigate such difficulties, for whole-genome sequence data, and corresponding phenotypic data we had generated. Methods Our recently released Illumina read sequences (Bioproject PRJNA669191) for 29 clinical Colombian isolate genomes of Cryptococcus neoformans var. grubii (28 VNI and 1 VNII as outgroup)12 were assembled and aligned to the annotated H99 VNI reference genome. Single nucleotide polymorphisms (SNPs) were called for the VNI alignment. MLST types, phenotypes, and source metadata of the same isolates12 were integrated with the genomic data. Analyses were interpreted in the light of published literature. Results The 28 VNI isolates were assigned an order considering MLST classification and whole-genome phylogenetic distances. Most SNPs were biallelic, allowing straightforward barcoding: each of the 28 isolates was given a bar if it had the minor allele. Barcode profiles (SNP state vectors) were found repeated numerous times within genes and across entire chromosomes, indicating that neither fine nor ‘rough’ mapping of associations would succeed, except where flagged genes had already been characterized by relevant molecular biology experiments. The same repetitiveness can allow amplicons of individual MLST loci to tag and inform on variation present in other loci in the genome. The gene for the capsule-associated protein CAP59 and its promoter region illustrate such implications at a small (genic) scale. Conclusions: Most associations of phenotypes with fungal genomes from modestly sampled clinical isolate populations cannot be localized to one or a few regions in a genome. This problem is less restrictive in human GWAS studies or (possibly) in studies of recombining fungi sampled from the environment3. It limits the benefits for molecular etiologic understanding that one might expect from GWAS of isolates obtained in clinical contexts, where key fungal phenotypes can be under stronger selection pressure. Explanatory power may be low if one compares just MLST types or phylogenetic clusters4 or examines only variation within individual MLST types. More informative results may be gained by restricting the genomic search space a priori to a subset of genes that are likely to be related to a phenotype, and then zooming in to individual SNPs that are known/suspected to affect protein structure/function1 or influence transcription/translation of the gene. Where the modes of regulation of a key gene are still not completely characterized despite decades of research, such as in CAP59, the presence of a phenotypically monitored, lone SNP in a strategic position within an almost SNP-less region can give potentially precious hints where otherwise none exist; we illustrate this strategy of SNP-focused local exploration for the promoter/enhancer and currently used MLST amplicon of CAP59. Sources:
Poster session 1, September 21, 2022, 12:30 PM - 1:30 PM Background Hematopoietic stem cells (HSCs) are considered a multipotent population with high proliferative potential, and are widely used in the treatment of leukemias, multiple myeloma, and some lymphomas. In the context of infectious diseases, some microorganisms have been reported to induce changes in the expression of surface markers in HSCs by a direct effect or through the induction of cytokines. Systemic infections are characterized by inducing stress on the bone marrow, which is reflected in an increase or decrease in leukocytes and platelets in peripheral blood, a process known as ‘emergency hematopoiesis’. Histoplasmosis is a systemic mycosis caused by Histoplasma spp., which occurs mainly in immunosuppressed individuals; this mycosis can present a severe clinical picture with dissemination to various organs, including the bone marrow, and is associated with anemia and pancytopenia. So far, the effect of a possible interaction of Histoplasma with HSCs is unknown. Objectives To evaluate, in vitro, the effects of Histoplasma capsulatum infection on activation and proliferation of HSCs. Methods HSCs were obtained from bone marrow of C57BL/6 male mice; after isolation and purification, they were characterized by flow cytometry. Later, the basal expression of toll-like receptor (TLR)-2, TLR4, and Dectin-1 was determined using flow cytometry. HSCs were infected with H. capsulatum yeasts in a multiplicity of infection (MOI) of 5 and incubated for 24 h. In addition, some of the co-cultures were previously treated with specific blocking antibodies for TLR2 and TLR4 or with a blocking peptide specific for Dectin-1 (CLEC7A). Furthermore, phagocytosis, microbicidal, and cell proliferation assays were done, and the expression of the genes encoding the cytokines IL-1β, IL-6, IL-10, IL-17, TNF-α, and TGF-β as well as arginase-1 and iNOS were assessed. Results We observed that H. capsulatum has the capability to adhere and internalize within these HSCs; nonetheless, this process did not affect the survival of the fungus. The interaction of H. capsulatum with HSCs induced a significantly increased expression of TLR2 and Dectin-1 but not TLR4. In addition, this fungal interaction significantly induced an augmented expression of IL-6, IL-1β, IL-10, IL-17, TNF-α, TGF-β, as well as the immune mediators Arg-1 and iNOS. Interestingly, blockade of these receptors significantly decreased the phagocytosis process as well the expression of all inflammatory mediators evaluated, especially when blocking TLR4 and Dectin-1. Of note, H. capsulatum induced apoptosis but did not inhibit the proliferation of these stem cells. Conclusions These results indicate that HSCs are capable of phagocytosing H. capsulatum but do not affect its survival; moreover, this fungal pathogen could induce changes in the expression of pattern-recognition receptors (PRRs), especially TLR2 and Dectin-1, and could subsequently activate the HSCs leading to the expression of inflammatory mediators as well as affecting the viability of these stem cells. Altogether, these findings indicate that H. capsulatum could affect the hematopoiesis process as reflected in an increase or decrease in leukocytes, erythrocytes, and platelets as observed in patients with severe and disseminated disease, especially in those with dissemination to bone marrow.
Poster session 1, September 21, 2022, 12:30 PM - 1:30 PM Background Mesenchymal stromal cells (MSCs) have become a tool not only for tissue regeneration but also for the treatment of inflammatory diseases. Several studies have demonstrated the therapeutic potential of MSCs for the treatment of noninfectious inflammatory diseases; however, they appear to play a dual role in infectious diseases. Histoplasmosis is a systemic mycosis caused by Histoplasma spp., which occurs mainly in immunosuppressed individuals; this mycosis can present a severe clinical picture with dissemination to various organs and is associated with an exacerbated inflammatory response and with anemia and pancytopenia if bone marrow is affected. So far, the effect of a possible interaction of Histoplasma with stem cells present in the bone marrow is unknown. Objectives To examine, in vitro, the immunomodulatory effects of MSCs in response to H. capsulatum infection. Methods MSCs were obtained from bone marrow of C57BL/6 male mice; after isolation and purification, they were induced to mesodermal lineages and characterized by flow cytometry. Later, the basal expression of toll-like receptor (TLR)-2, TLR4, and Dectin-1 was determined using flow cytometry. MSCs were infected with H. capsulatum yeasts (isolate CIB 1980) in a multiplicity of infection (MOI) of 5 and incubated for 24 h. In addition, some of the co-cultures were previously treated with specific blocking antibodies for TLR2 and TLR4 or with a blocking peptide specific for Dectin-1 (CLEC7A). Furthermore, phagocytosis, microbicidal, and cell proliferation assays were done, and the expression of the genes encoding the cytokines IL-1β, IL-6, IL-10, IL-17, TNF-α, and TGF-β as well as of those for arginase-1 and iNOS were assessed. Results We observed that H. capsulatum has the capability to adhere and internalize within these MSCs; nonetheless, this process did not affect the survival of the fungus. The interaction of H. capsulatum with MSCs induced a slight but significantly increased expression of TLR2 but not TLR4 nor Dectin-1. In addition, this fungal interaction significantly induced an augmented expression of IL-6 and a decrease in the expression of IL-1β, IL-17, TNF-α, TGF-β, as well as the immune mediators Arg-1 and iNOS. Interestingly, blockade of these receptors did not affect phagocytosis, but increased IL-1β, IL-17, and TNF-α expression and reduced the expression of IL-6. Noteworthy, H. capsulatum induced apoptosis and inhibited the proliferation of these stem cells; furthermore, this fungus significantly reduced the expression of genes related to adipogenic differentiation and increased the expression of genes related to the osteogenic differentiation process. Conclusions The above results indicate that MSCs do not exert a notable antifungal effect against H. capsulatum; on the contrary, this fungal pathogen not only modulates the expression of inflammatory mediators in MSCs, by a mechanism dependent on TLR2, TLR4, and Dectin-1, but also affects their viability and their ability to differentiate into a different type of specialized cells. These events could, in principle, affect both hematopoiesis and the immune response in the infected host, and in addition, these stem cells may provide a niche for this fungus, allowing it to persist and evade host immunity.
O objetivo deste artigo é oferecer um panorama geral do lugar do meio ambiente na história do Brasil e do lugar do Brasil na governança global da mudança climática, área em que o país tem sido um ator de relevância. O marco teórico de referência é o enfoque do compromisso climático que analisa a trajetória das emissões, das políticas climáticas domésticas e externas ao país. Os conceitos do enfoque são aplicados a cinco períodos históricos.
Intrinsic soil properties have been shown to mediate the effects of ectomycorrhizal (ECM) fungi and their associated trees on soil organic matter (SOM) and nitrogen (N) cycling, but variation in the contribution of fungal communities to ECM effects across different forests remains uncertain. To investigate the potential role of fungal communities in driving observed variation in ECM effects, we characterized fungal community composition and function using DNA sequence variability of the ITS2 region of the fungal rRNA operon and measured chemical properties of forest floor leaf litter, soil organic horizon, and soil mineral horizons (0–5cm, 15–20 cm depth) beneath ECM-associated Oreomunnea mexicana focal trees. We sampled beneath focal trees in arbuscular mycorrhizal (AM)- and ECM-dominated stands within four adjacent watersheds that differed in underlying soil pH and fertility. We found that overall fungal community composition and the ratio of ECM to saprotrophic fungi differed between AM- and ECM-dominated stands in the lowest pH and fertility watershed but were similar between stand mycorrhizal types in the highest pH and fertility watershed. Patterns in fungal community composition and function aligned with patterns in N isotopic composition of forest floor leaf litter and mineral soil, which could reflect greater ECM transfer of N to the trees and greater contribution of hyphal biomass to SOM in the lowest pH and fertility watershed. Overall, our results suggest the potential for watershed-scale variation in soil pH and fertility to mediate fungal community contributions to variation in ECM effects on biogeochemical syndromes.
The damselflies Hetaerininae, a subfamily of Calopterygidae, comprise four genera distributed from North to South America: Hetaerina, Mnesarete, Ormenophlebia and Bryoplathanon. While several studies have focused on the intriguing behavioral and morphological modifications within Hetaerina, little of the evolutionary history of the group is well understood. Understanding the biogeographical history of Hetaerininae is further complicated by uncertainty in important geological events, such as the closure of the Central American Seaway (CAS). We generated a phylogenetic hypothesis to test the relationships and divergence times within Hetaerininae using IQtree and BEAST2 and found that Mnesarete and Ormenophlebia render Hetaerina paraphyletic. Reclassification of the genera within Hetaerininae is necessary based on our results. We also tested the fit to our dataset of two different hypotheses for the closure of CAS. Our results supported a gradual closure, starting in the Oligocene and ending in the Pliocene. Using Ancestral Character State Reconstruction, we found that the rubyspot, which is associated with higher fecundity in several species, was ancestral for Hetaerininae and subsequently lost four times. Estimates of diversification in association with the rubyspot are needed to understand the plasticity of this important character. Forest habitat was the ancestral state for Hetaerininae, with transitions to generalist species of Hetaerina found primarily in the Mesoamerican region. These results add to our understanding of the relationship between morphology, biogeography and habitat in a charismatic group of damselflies.
Introduction: Ocular toxoplasmosis is the leading cause of posterior uveitis worldwide, affecting individuals acrossdifferent age groups. The key to reducing vision loss includes prompt diagnosis and treatment. However, despite the prevalence of ocular toxoplasmosis, there has been little consensus regarding its pathophysiology,clinical features, diagnosis, and especially management. Methods: The data sources were literature reviews, including Pub Med and Medline databases. Search terms included toxoplasmosis, retinitis, vasculitis, vitritis, uveitis alone or in combination with, serum, aqueous, vitreous eye, ocular and review. Results: In this review paper, we have sought to provide an overview of the pathophysiology, epidemiology, and clinical features of the disease, both based on current literature and our own clinical experience. We have also discussed the use of serology, ocular fluid, and ophthalmic investigations that could further facilitate the diagnosis of ocular toxoplasmosis.Different management strategies have been reported worldwide, including newer approaches such as local therapy. Conclusion: A better understanding of critical aspects of ocular toxoplasmosis will hopefully lead to reduced morbidity, including blindness associated with this condition.
Institution pages aggregate content on ResearchGate related to an institution. The members listed on this page have self-identified as being affiliated with this institution. Publications listed on this page were identified by our algorithms as relating to this institution. This page was not created or approved by the institution. If you represent an institution and have questions about these pages or wish to report inaccurate content, you can contact us here.
5,261 members
Merlin-Patricia Grueso-Hinestroza
  • Grupo de Investigación en Dirección y Gerencia (DIGE)
Benjamin Quesada
  • Facultad de Ciencias Naturales
Juan F. Vargas
  • Faculty of Economics
Lilian Chuaire
  • Faculty of Natural Sciences and Mathematics
Alberto Velez-van-Meerbeke
  • Neuroscience Research Group
Information
Address
Calle 12C # 6-25, 111711, Bogotá, Cundinamarca, Colombia
Head of institution
José Alejandro Cheyne García
Website
http://www.urosario.edu.co/
Phone
(+571) 4225321
Fax
(+571) 2970200