Revista Española de Geriatría y Gerontología, 2013
Age-related biological deterioration also includes immune system deterioration and, in consequenc... more Age-related biological deterioration also includes immune system deterioration and, in consequence, a rise in the incidence and prevalence of infections and cancers, as well as low responses to vaccination strategies. Out of all immune cell subsets, T-lymphocytes seem to be involved in most of the age-related defects. Since T-lymphocytes mature during their passage through the thymus, and the thymus shows an age-related process of atrophy, thymic regression has been proposed as the triggering event of this immune deterioration in elderly people. Historically, it has been accepted that the young thymus sets the T-lymphocyte repertoire during the childhood, whereupon atrophy begins until the elderly thymus is a non-functional evolutionary trace. However, a rising body of knowledge points toward the thymus functioning during adulthood. In the elderly, higher thymic function is associated with a younger immune system, while thymic function failure is associated with all-cause mortality. Therefore, any new strategy focused on the improvement of the elderly quality of life, especially those trying to influence the immune system, should take into account, together with peripheral homeostasis, thymus function as a key element in slowing down age-related decline.
Species with restricted geographic distributions consisting of isolated populations are particula... more Species with restricted geographic distributions consisting of isolated populations are particularly susceptible to extinction because these demes face an increased risk of disappearing due to environmental, demographic, and genetic stochasticity. We used partial DNA sequences of the cytochrome b (1083 bp) and ND2 (1041 bp) mitochondrial genes to investigate the phylogeography and population genetics of Anolis cooki, a threatened lizard endemic to the southwestern coast of the Caribbean Island of Puerto Rico. Maximum likelihood and Bayesian methods revealed relatively shallow genetic differentiation among 27 unique haplotypes (from 52 individuals) from the known extant populations of A. cooki in mainland Puerto Rico. Despite this pattern, specimens from the same geographic area tended to nest together. The most basal division within A. cooki is between haplotypes from the three westernmost populations (Punta Á guila, Morrillos, Playa Santa) and the remainder demes (Bahía Ballena, La Cueva, Punta Verraco). The three westernmost populations of A. cooki are separated from their conspecific demes by the Guánica Bay and the Loco River drainage system, which together may represent a physiographic barrier for A. cooki. Each population of A. cooki only has private haplotypes; in other words, there are no shared mitochondrial types between populations. Because the number of private haplotypes can be used as an indirect measure of gene flow, this finding suggests that currently there is no migration among demes, and that each is an independent demographic unit, despite the relatively short distances (ca. 2 km) that separate some of them. Pairwise F ST values and spatial analyses of molecular variation confirmed the existence of distinct groups of genetically defined sampling areas, and of significant molecular variation among populations within groups and within populations. The conservation status of the populations of A. cooki varies greatly. The demes from Punta Á guila, Morrillos, and Bahía Ballena inhabit protected areas, and are larger, genetically diverse, and seemingly stable. The population from Playa Santa showed a high level of genetic diversity, but it occurs in an area that has been intensively developed for residential and touristic purposes, and its long-term survival is uncertain. A. cooki is also known from Caja de Muertos, an island off the southcentral coast of Puerto Rico. Surveys conducted on September 2006 and March 2007 did not produce any specimens, and a thorough assessment of Caja de Muertos is needed to determine the present status of A. cooki on the island.
We tested the prediction of the sensory drive hypothesis using four allopatric populations of the... more We tested the prediction of the sensory drive hypothesis using four allopatric populations of the lizard Anolis cristatellus from two distinct environments (i.e., mesic and xeric conditions). For each population, we measured habitat light characteristics and quantified signal design by measuring the spectral and total reflectance and transmittance of the dewlap. We used these data to calculate dewlap detectability using an empirically based model of signal detection probability. We found that populations from mesic and xeric conditions occupy two distinct habitats with respect to light intensity and spectral quality and that dewlap design has diverged between populations in a way that increases signal detectability in each habitat. The major difference in dewlap design was in total reflectance and transmittance, making dewlaps from xeric habitats darker and dewlaps from mesic habitats brighter. Furthermore, dewlap detection decreased significantly when a dewlap from a xeric habitat is detected under the spectral conditions of a mesic habitat. The converse is true for a dewlap from a mesic habitat. We propose that sensory drive has promoted divergence in dewlap design in distinct habitat light conditions, and we discuss the possibility that selection might promote early stages of reproductive isolation as a by-product of selection on dewlap design to distinct habitat light conditions.
Proceedings of the National Academy of Sciences, 2014
Significance Communication often is a major component of social interactions. Signaling individua... more Significance Communication often is a major component of social interactions. Signaling individuals are faced with the challenge of capturing the attention of intended receivers while limiting eavesdropping by potential predators. We conducted an experiment in nature to evaluate the hypothesis that prey species can modulate the physical properties of movement-based displays in response to the presence of predators. We found that male brown anoles dramatically decreased the amplitude of their head-bob displays in the presence of a predatory lizard, resulting in less conspicuous signals. Although less conspicuous signals may be safer for the signaling individuals, they also reduce the distance from which potential mates or competitors can detect them, which might affect the territory size and reproductive success of signaling males.
Two factors that can lead to geographic structuring in conspecific populations are barriers to di... more Two factors that can lead to geographic structuring in conspecific populations are barriers to dispersal and climatic stability. Populations that occur in different physiographic regions may be restricted to those areas by physical and ⁄ or ecological barriers, which may facilitate the formation of phylogeographic clades. Long-term climatic stability can also promote genetic diversification, because new clades are more likely to evolve in areas that experience lesser climatic shifts. We conducted a phylogeographic study of the Puerto Rican lizard Anolis krugi to assess whether populations of this anole show genetic discontinuities across the species' range, and if they do, whether these breaks coincide with the boundaries of the five physiographic regions of Puerto Rico. We also assessed whether interpopulation genetic distances in A. krugi are positively correlated with relative climatic stability in the island. Anolis krugi exhibits genetic structuring, but the phylogroups do not correspond to the physiographic regions of Puerto Rico. We used climatic reconstructions of two environmental extremes of the Quaternary period, the present conditions and those during the last glacial maximum (LGM), to quantify the degree of climatic stability between sampling locations. We documented positive correlations between genetic distances and relative climatic stability, although these associations were not significant when corrected for autocorrelation. Principal component analyses indicated the existence of climatic niche differences between some phylogeographic clades of A. krugi. The approach that we employed to assess the relationship between climatic stability and the genetic architecture of A. krugi can also be used to investigate the impact of factors such as the spatial distribution of food sources, parasites, predators or competitors on the genetic landscape of a species.
To perform an extensive analysis of the immune status of asymptomatic children with the 22q11.2 d... more To perform an extensive analysis of the immune status of asymptomatic children with the 22q11.2 deletion syndrome, with special emphasis on the regulatory T cells (Treg) population. Analysis of thymic function, frequency and absolute counts of immune subsets, and phenotype of Treg were performed in 10 asymptomatic children bearing the 22q11.2 deletion and compared with 12 age-matched, healthy children. Children with 22q11.2 deletion syndrome showed a curtailed thymic output, lower T-cell levels, and a homeostatic deregulation in the CD4 T-cell compartment, characterized by a greater proliferative history in the naïve CD4 T-cell subset. Treg numbers were markedly reduced in children with 22q11.2 deletion syndrome, and remaining Treg showed mostly an activated phenotype. Reduced thymic output in children with 22q11.2 deletion syndrome could be related with an increased proliferation in the naïve CD4 T-cell compartment and the consequent Treg activation to ensure that T-cell expansion remains under control. Deregulated peripheral homeostasis and loss of suppressive capacity by Treg could compromise the integrity of T-cell immunity during adulthood and play a relevant role in the increased incidence of autoimmune diseases reported in patients with the 22q11.2 deletion syndrome.
The prevalence of genotypic resistance to nucleoside analogues was examined in 150 naive individu... more The prevalence of genotypic resistance to nucleoside analogues was examined in 150 naive individuals with chronic HIV-1 infection acquired before June 1996, when protease inhibitors began to be used in Spain, and in a group of 52 recent seroconverters infected since 1997. Overall, the prevalence of subjects carrying nucleoside-resistant genotypes was similar in both groups (12.6% and 15.4%, respectively). A polymorphism at codon 70 accounted for more than half of cases (63.1%) in naive individuals infected before protease inhibitors became available, in contrast most recent seroconverters carried genotypes with one or more key nucleoside resistance mutations, mainly associated with lack of sensitivity to zidovudine or lamivudine (prevalence 9.6% and 5.9%, respectively). When only key mutations were considered in each of the two periods, the prevalence of nucleosideresistant genotypes was increased signi®cantly among recent seroconverters (13.5% vs. 4.7%; P`0.05). The relatively high rate of resistance to nucleosides in Spain justi®es the introduction of drug resistance testing in naive recent seroconverters before beginning antiretroviral therapy.
Background. A subgroup of human immunodeficiency virus type 1 (HIV-1)-infected patients with seve... more Background. A subgroup of human immunodeficiency virus type 1 (HIV-1)-infected patients with severe immunodeficiency show persistently low CD41 cell counts despite sustained viral suppression. It is unclear whether this immuno-virological discordance translates into an increased risk for clinical events. Methods. Data analysis from a large multicenter cohort incorporating 14,433 HIV-1-infected patients in Germany. Treatment-naive patients beginning antiretroviral therapy (ART) with CD41 cell counts ,200 cells/lL who achieved complete and sustained viral suppression ,50 copies/mL (n 5 1318) were stratified according to the duration of immuno-virological discordance (failure to achieve a CD41 cell count >200 cells/lL). Groups were compared by descriptive and Poisson statistics. The time-varying discordance status was analyzed in a multivariable Cox model. Results. During a total of 5038 person years of follow-up, 42 new AIDS events occurred. The incidence rate of new AIDS events was highest in the initial 6 months of complete viral suppression (immuno-virological discordance group, 55.06; 95% confidence interval [CI], 30.82-90.82; and immune responder group, 24.54; 95% CI, 10.59-48.35) and decreased significantly by 65% per year in patients with immuno-virological discordance (incidence risk ratio, 0.35; 95% CI, 0.14-0.92; P 5 .03). Immuno-virological discordance and prior AIDS diagnosis were independently associated with new AIDS events (hazard ratio, 3.10; 95% CI, 1.09-8.82; P 5 .03). Conclusion. Compared with immune responders, patients with immuno-virological discordance seem to remain at increased risk for AIDS. Absolute risk is greatly reduced after the first 6 months of complete viral suppression.
Background/Aims: A unusually high rate of HCV-infected individuals in whom the HCV genotype canno... more Background/Aims: A unusually high rate of HCV-infected individuals in whom the HCV genotype cannot be ascertained by means of single PCR and LIPA procedures has recently been reported in our area. The aim of the present study was to investigate the epidemiological, clinical and molecular characteristics of these patients. Metkk Cross-sectional study. Eighty anti-HCVpositive patients with chronic liver disease, 45 (56.25%) of them intravenous drug users, were included. HCV genotyping was carried out in all patients using commercial single PCR and LIPA procedures Samples where no HCV RNA amplification and/or indeterminate HCV genotype were found were also tested by means of a nested PCR. HCV viral load was measured in all patients. Results: HCV genotyping was not achieved in 23 (28.75%) individuals. No amplification of HCV RNA EPATITIS C virus (HCV) is the most frequent cause
The Journals of Gerontology Series A: Biological Sciences and Medical Sciences, 2014
Human thymus is completely developed in late fetal stages and its function peaks in newborns. Aft... more Human thymus is completely developed in late fetal stages and its function peaks in newborns. After the first year of life, the thymus undergoes a progressive atrophy that dramatically decreases de novo T-lymphocyte maturation. Hormonal signaling and changes in the microRNA expression network are identified as underlying causes of human thymus involution. However, specific pathways involved in the age-related loss of thymic function remain unknown. In this study, we analyzed differential gene-expression profile and microRNA expression in elderly (70 years old) and young (less than 10 months old and 11 years old) human thymic samples. Our data have shown that WNT pathway deregulation through the overexpression of different inhibitors by the nonadipocytic component of the human thymus stimulates the age-related involution. These results are of particular interest because interference of WNT signaling has been demonstrated in both animal models and in vitro studies, with the three major hallmarks of thymic involution: (i) epithelial structure disruption, (ii) adipogenic process, and (iii) thymocyte development arrest. Thus, our results suggest that secreted inhibitors of the WNT pathway could be explored as a novel therapeutical target in the reversal of the age-related thymic involution.
Phenotypic plasticity can contribute to the process of adaptive radiation by facilitating populat... more Phenotypic plasticity can contribute to the process of adaptive radiation by facilitating population persistence in novel environments. West Indian Anolis lizards provide a classic example of an adaptive radiation, in which divergence has occurred along two primary ecological axes: structural microhabitat and climate. Adaptive plasticity in limb morphology is hypothesized to have facilitated divergence along the structural niche axis in Anolis, but very little work has explored plasticity in physiological traits. Here, we experimentally ask whether Puerto Rican Anolis cristatellus from mesic and xeric habitats differ in desiccation rates, and whether these lizards exhibit an acclimation response to changes in relative humidity. We first present microclimatic data collected at lizard perch sites that demonstrate that abiotic conditions experienced by lizards differ between mesic and xeric habitat types. In Experiment 1, we measured desiccation rates of lizards from both habitats maintained under identical laboratory conditions. This experiment demonstrated that desiccation rates differ between populations; xeric lizards lose water more slowly than mesic lizards. In Experiment 2, lizards from each habitat were either maintained under the conditions of Experiment 1, or under extremely low relative humidity. Desiccation rates did not differ between lizards from the same habitat maintained under different treatments and xeric lizards maintained lower desiccation rates than mesic lizards within each treatment. Our results demonstrate that A. cristatellus does not exhibit an acclimation response to abrupt changes of hydric conditions, and suggest that tropical Anolis lizards might be unable to exhibit physiological plasticity in desiccation rates in response to varying climatic conditions.
Background: HIV-1-infected individuals progressively loss CD4 + T cells leading to immunosuppress... more Background: HIV-1-infected individuals progressively loss CD4 + T cells leading to immunosuppression and raising the risk of opportunistic infections. CD8 + T-cells play an important role in the immune response against virus infections through their TCR. Objective: To evaluate the CD8-TCR repertoire and immunologic markers in HIV-1-infected patients. Study design: Ten chronic HIV-1-infected individuals on prolonged effective antiretroviral treatment (ART) were analyzed at baseline (before treatment interruption), after at least one year of treatment interruption (TI) and after at least one year from ART resume (TR). Twenty-four TCR-V gene families were analyzed by a modified CDR3 spectratyping method in isolated CD8 + T-cells. Immune activation, exhaustion and subpopulation markers were analyzed by flow cytometry. Results: Expansion of V10, V14 and V15 families, associated with low cell activation and stable exhaustion markers, were found at TI. Moreover, an increment of effector memory cells was found. Besides, depletion of V20, V28, and V29 families, associated with an increase in cell activation and exhaustion markers, at TI were also found. These alterations seemed to be more pronounced in patients who had longer time from diagnosis. ART seemed to restore altered CD8 + T-cell repertoire and most of the immunologic markers. Conclusions: During TI (that was more pronounced in patients with longer HIV-1 infection) it was observed the expansion of V families correlated with decreased cell activation, while V families correlated with cell activation and exhaustion were depleted. These specific repertoire alterations reverted after ART resume.
Journal of Cardiothoracic and Vascular Anesthesia, 2009
The purpose of this study was to evaluate the influence of preoperative type I and II immune resp... more The purpose of this study was to evaluate the influence of preoperative type I and II immune responses on blood transfusion requirements. Design: A prospective and observational trial. Setting: A postcardiac surgery unit of a university hospital. Participants: Seventy-one consecutive patients undergoing elective cardiac surgery. Interventions: Blood samples drawn for laboratory analysis and immunologic study. Measurements and Main Results: Patients were divided into 2 groups according to blood transfusion requirements: <2 units (n ؍ 35) and >2 units of red blood cells (n ؍ 36). The preoperative immune response was assessed by flow cytometry, measuring the proportion of CD4 ؉ T helper cells producing cytokines, including Th1 response (interferon-␥ and tumor necrosis factor-␣ [TNF-␣]) and Th2 response (interleukin 4 and 10). Two logistic regression analyses (including and not including immunologic variables) were used to select and weight perioperative variables associated with an increased risk of transfusion. Three variables were found to be independent predictors of transfusion requirements when immunologic variables were not included: preoperative platelet count, preoperative hemoglobin, and hypertension. When all the variables were included, preoperative hemoglobin, cardiopulmonary bypass time, and the preoperative proportion of CD4؉ T cells producing TNF-␣ were associated with an increased risk of transfusion (Hosmer-Lemeshow, 0.33; c-index, 0.93), but preoperative platelet count and hypertension were not. Conclusions: A low preoperative Th1 immune response, as assessed by the proportion of CD4؉ T-helper-producing TNF-␣, was associated with a higher blood transfusion rate.
JAIDS Journal of Acquired Immune Deficiency Syndromes, 2006
Objective: To analyze the predictive capacity of thymic volume in CD4 T-cell loss after treatment... more Objective: To analyze the predictive capacity of thymic volume in CD4 T-cell loss after treatment interruption in HIV-infected patients with high nadir CD4 count. Methods: Thirty-nine HIV-infected patients with CD4 counts greater than or equal to 500 cells/KL, nadir CD4 counts greater than or equal to 250 cells/KL, and plasma viral loads less than 50 copies/mL for at least the past 12 months began a treatment interruption program. The event of interest for this study was the decrease of CD4 count below 350 cells/KL. Kaplan-Meier curves were used for all time-to-event analyses, and log-rank tests were used for comparison between groups in the univariate analysis. All variables with statistical association with CD4 T-cell loss were analyzed using multivariate Cox proportional hazards regression models. Results: Twenty-three percent of the patients had a decrease in CD4 count to less than 350 cells/KL. In the univariate analysis, only thymic volume was statistically significant with this event (P = 0.02). Nadir CD4 count nearly reached statistical significance. However, age, sex, HCV coinfection, CD4 count, T-cell receptor excision circleYbearing cells, and early viral load rebound did not show statistical differences. Thymic volume and CD4 T-cell loss were independently associated using Cox proportional hazards regression model (P = 0.04; relative risk, 0.76; 95% confidence interval, 0.59Y0.99). Conclusions: In this study, we demonstrate for the first time that thymic volume predicts CD4 T-cell loss in patients with nadir CD4 count greater than or equal to 250 cells/KL under treatment interruption.
1. Rising global temperatures are predicted to impact organisms in diverse ways. For ectotherms, ... more 1. Rising global temperatures are predicted to impact organisms in diverse ways. For ectotherms, recent broad-scale analyses have predicted global patterns of vulnerability to warming, with tropical species at higher risk of detrimental effects than temperate species. However, vulnerability results from complex interactions between environment, physiology and behaviour. For species that inhabit a diversity of habitat types, these interactions may change across their range. 2. We measured operative thermal environments (T e) and body temperatures (T b) of the tropical Caribbean lizard Anolis cristatellus at nine sites representing two habitat types: mesic and xeric forest. The thermal sensitivity of whole-organism physiological performance (i.e. sprint speed) of one mesic and one xeric population was also measured. Thermal and performance data were integrated to determine how habitat thermal variation, behavioural thermoregulation and thermal physiology influence current physiological performance capacity in the field. We then evaluate if habitat suitability and physiological capacity would change assuming climate warming of 3°C over the next century. 3. The mean T e of the xeric habitat was 4AE5°C warmer than that of the mesic habitat. However, behavioural thermoregulation by xeric lizards led to lesser differences in T b (3AE5°C) between habitat types. The thermal sensitivity of sprint performance was similar for mesic and xeric lizards, and lizards from both habitats maintain sprint capacities near 100%. Climate warming is predicted to influence mesic and xeric lizards differently. Xeric lizards currently live in a thermal environment near their upper temperature threshold, while mesic lizards do not. As a result, the number of suitable perch sites is predicted to decrease dramatically in the xeric but not the mesic habitat. In addition, the physiological capacity of mesic lizards is predicted to increase by approximately 4%, whereas a decrease of approximately 30% is predicted for xeric lizards. 4. We characterized variation in the current biophysical and ecophysiological conditions experienced by A. cristatellus by integrating fine-scale measurements of thermal microhabitats with data on body temperatures and physiological performance capacities. These data allowed us to explicitly demonstrate how variation in these parameters can influence population susceptibility to climate warming across a species range and highlight the utility of a mechanistic approach in studies of global climate change.
Why convergent evolution occurs among some species occupying similar habitats but not among other... more Why convergent evolution occurs among some species occupying similar habitats but not among others is a question that has received surprisingly little attention. Caribbean Anolis lizards, known for their extensive convergent evolution among islands in the Greater Antilles, are an appropriate group with which to address this question. Despite the well-documented pattern of between-island convergence, some Greater Antillean anoles are not obviously part of the convergence syndrome. One example involves aquatic anoles-species that are found near to and readily enter streams-which have evolved independently twice in the Caribbean and also twice on mainland Central America. Despite being found in similar habitats, no previous study has investigated whether aquatic anoles represent yet another case of morphological convergence. We tested this hypothesis by collecting morphological data for seven aquatic anole species and 29 species from the six convergent types of Greater Antillean habitat specialists. We failed to find evidence for morphological convergence: the two Caribbean aquatic species are greatly dissimilar to each other and to the Central American species, which, however, may be convergent upon each other. We suggest two possible reasons for this lack of convergence in an otherwise highly convergent system: either there is more than one habitat type occupied by anoles in the proximity of water, or there is more than one way to adapt to a single aquatic habitat. We estimate that almost all of the 113 species of Greater Antillean anoles occupy habitats that are also used by distantly related species, but only 15% of these species are not morphologically similar to their distantly related ecological counterparts. Comparative data from other taxa would help enlighten the question of why the extent of convergence is so great in some lineages and not in others.
Enfermedades Infecciosas y Microbiología Clínica, 2010
Estudio comparativo entre una té cnica de reacció n en cadena de la polimerasa en transcripció n ... more Estudio comparativo entre una té cnica de reacció n en cadena de la polimerasa en transcripció n reversa en tiempo real, un mé todo de enzimoinmunoaná lisis y el cultivo shell-vial en la detecció n de virus gripales A y B en pacientes adultos.
Revista Española de Geriatría y Gerontología, 2013
Age-related biological deterioration also includes immune system deterioration and, in consequenc... more Age-related biological deterioration also includes immune system deterioration and, in consequence, a rise in the incidence and prevalence of infections and cancers, as well as low responses to vaccination strategies. Out of all immune cell subsets, T-lymphocytes seem to be involved in most of the age-related defects. Since T-lymphocytes mature during their passage through the thymus, and the thymus shows an age-related process of atrophy, thymic regression has been proposed as the triggering event of this immune deterioration in elderly people. Historically, it has been accepted that the young thymus sets the T-lymphocyte repertoire during the childhood, whereupon atrophy begins until the elderly thymus is a non-functional evolutionary trace. However, a rising body of knowledge points toward the thymus functioning during adulthood. In the elderly, higher thymic function is associated with a younger immune system, while thymic function failure is associated with all-cause mortality. Therefore, any new strategy focused on the improvement of the elderly quality of life, especially those trying to influence the immune system, should take into account, together with peripheral homeostasis, thymus function as a key element in slowing down age-related decline.
Species with restricted geographic distributions consisting of isolated populations are particula... more Species with restricted geographic distributions consisting of isolated populations are particularly susceptible to extinction because these demes face an increased risk of disappearing due to environmental, demographic, and genetic stochasticity. We used partial DNA sequences of the cytochrome b (1083 bp) and ND2 (1041 bp) mitochondrial genes to investigate the phylogeography and population genetics of Anolis cooki, a threatened lizard endemic to the southwestern coast of the Caribbean Island of Puerto Rico. Maximum likelihood and Bayesian methods revealed relatively shallow genetic differentiation among 27 unique haplotypes (from 52 individuals) from the known extant populations of A. cooki in mainland Puerto Rico. Despite this pattern, specimens from the same geographic area tended to nest together. The most basal division within A. cooki is between haplotypes from the three westernmost populations (Punta Á guila, Morrillos, Playa Santa) and the remainder demes (Bahía Ballena, La Cueva, Punta Verraco). The three westernmost populations of A. cooki are separated from their conspecific demes by the Guánica Bay and the Loco River drainage system, which together may represent a physiographic barrier for A. cooki. Each population of A. cooki only has private haplotypes; in other words, there are no shared mitochondrial types between populations. Because the number of private haplotypes can be used as an indirect measure of gene flow, this finding suggests that currently there is no migration among demes, and that each is an independent demographic unit, despite the relatively short distances (ca. 2 km) that separate some of them. Pairwise F ST values and spatial analyses of molecular variation confirmed the existence of distinct groups of genetically defined sampling areas, and of significant molecular variation among populations within groups and within populations. The conservation status of the populations of A. cooki varies greatly. The demes from Punta Á guila, Morrillos, and Bahía Ballena inhabit protected areas, and are larger, genetically diverse, and seemingly stable. The population from Playa Santa showed a high level of genetic diversity, but it occurs in an area that has been intensively developed for residential and touristic purposes, and its long-term survival is uncertain. A. cooki is also known from Caja de Muertos, an island off the southcentral coast of Puerto Rico. Surveys conducted on September 2006 and March 2007 did not produce any specimens, and a thorough assessment of Caja de Muertos is needed to determine the present status of A. cooki on the island.
We tested the prediction of the sensory drive hypothesis using four allopatric populations of the... more We tested the prediction of the sensory drive hypothesis using four allopatric populations of the lizard Anolis cristatellus from two distinct environments (i.e., mesic and xeric conditions). For each population, we measured habitat light characteristics and quantified signal design by measuring the spectral and total reflectance and transmittance of the dewlap. We used these data to calculate dewlap detectability using an empirically based model of signal detection probability. We found that populations from mesic and xeric conditions occupy two distinct habitats with respect to light intensity and spectral quality and that dewlap design has diverged between populations in a way that increases signal detectability in each habitat. The major difference in dewlap design was in total reflectance and transmittance, making dewlaps from xeric habitats darker and dewlaps from mesic habitats brighter. Furthermore, dewlap detection decreased significantly when a dewlap from a xeric habitat is detected under the spectral conditions of a mesic habitat. The converse is true for a dewlap from a mesic habitat. We propose that sensory drive has promoted divergence in dewlap design in distinct habitat light conditions, and we discuss the possibility that selection might promote early stages of reproductive isolation as a by-product of selection on dewlap design to distinct habitat light conditions.
Proceedings of the National Academy of Sciences, 2014
Significance Communication often is a major component of social interactions. Signaling individua... more Significance Communication often is a major component of social interactions. Signaling individuals are faced with the challenge of capturing the attention of intended receivers while limiting eavesdropping by potential predators. We conducted an experiment in nature to evaluate the hypothesis that prey species can modulate the physical properties of movement-based displays in response to the presence of predators. We found that male brown anoles dramatically decreased the amplitude of their head-bob displays in the presence of a predatory lizard, resulting in less conspicuous signals. Although less conspicuous signals may be safer for the signaling individuals, they also reduce the distance from which potential mates or competitors can detect them, which might affect the territory size and reproductive success of signaling males.
Two factors that can lead to geographic structuring in conspecific populations are barriers to di... more Two factors that can lead to geographic structuring in conspecific populations are barriers to dispersal and climatic stability. Populations that occur in different physiographic regions may be restricted to those areas by physical and ⁄ or ecological barriers, which may facilitate the formation of phylogeographic clades. Long-term climatic stability can also promote genetic diversification, because new clades are more likely to evolve in areas that experience lesser climatic shifts. We conducted a phylogeographic study of the Puerto Rican lizard Anolis krugi to assess whether populations of this anole show genetic discontinuities across the species' range, and if they do, whether these breaks coincide with the boundaries of the five physiographic regions of Puerto Rico. We also assessed whether interpopulation genetic distances in A. krugi are positively correlated with relative climatic stability in the island. Anolis krugi exhibits genetic structuring, but the phylogroups do not correspond to the physiographic regions of Puerto Rico. We used climatic reconstructions of two environmental extremes of the Quaternary period, the present conditions and those during the last glacial maximum (LGM), to quantify the degree of climatic stability between sampling locations. We documented positive correlations between genetic distances and relative climatic stability, although these associations were not significant when corrected for autocorrelation. Principal component analyses indicated the existence of climatic niche differences between some phylogeographic clades of A. krugi. The approach that we employed to assess the relationship between climatic stability and the genetic architecture of A. krugi can also be used to investigate the impact of factors such as the spatial distribution of food sources, parasites, predators or competitors on the genetic landscape of a species.
To perform an extensive analysis of the immune status of asymptomatic children with the 22q11.2 d... more To perform an extensive analysis of the immune status of asymptomatic children with the 22q11.2 deletion syndrome, with special emphasis on the regulatory T cells (Treg) population. Analysis of thymic function, frequency and absolute counts of immune subsets, and phenotype of Treg were performed in 10 asymptomatic children bearing the 22q11.2 deletion and compared with 12 age-matched, healthy children. Children with 22q11.2 deletion syndrome showed a curtailed thymic output, lower T-cell levels, and a homeostatic deregulation in the CD4 T-cell compartment, characterized by a greater proliferative history in the naïve CD4 T-cell subset. Treg numbers were markedly reduced in children with 22q11.2 deletion syndrome, and remaining Treg showed mostly an activated phenotype. Reduced thymic output in children with 22q11.2 deletion syndrome could be related with an increased proliferation in the naïve CD4 T-cell compartment and the consequent Treg activation to ensure that T-cell expansion remains under control. Deregulated peripheral homeostasis and loss of suppressive capacity by Treg could compromise the integrity of T-cell immunity during adulthood and play a relevant role in the increased incidence of autoimmune diseases reported in patients with the 22q11.2 deletion syndrome.
The prevalence of genotypic resistance to nucleoside analogues was examined in 150 naive individu... more The prevalence of genotypic resistance to nucleoside analogues was examined in 150 naive individuals with chronic HIV-1 infection acquired before June 1996, when protease inhibitors began to be used in Spain, and in a group of 52 recent seroconverters infected since 1997. Overall, the prevalence of subjects carrying nucleoside-resistant genotypes was similar in both groups (12.6% and 15.4%, respectively). A polymorphism at codon 70 accounted for more than half of cases (63.1%) in naive individuals infected before protease inhibitors became available, in contrast most recent seroconverters carried genotypes with one or more key nucleoside resistance mutations, mainly associated with lack of sensitivity to zidovudine or lamivudine (prevalence 9.6% and 5.9%, respectively). When only key mutations were considered in each of the two periods, the prevalence of nucleosideresistant genotypes was increased signi®cantly among recent seroconverters (13.5% vs. 4.7%; P`0.05). The relatively high rate of resistance to nucleosides in Spain justi®es the introduction of drug resistance testing in naive recent seroconverters before beginning antiretroviral therapy.
Background. A subgroup of human immunodeficiency virus type 1 (HIV-1)-infected patients with seve... more Background. A subgroup of human immunodeficiency virus type 1 (HIV-1)-infected patients with severe immunodeficiency show persistently low CD41 cell counts despite sustained viral suppression. It is unclear whether this immuno-virological discordance translates into an increased risk for clinical events. Methods. Data analysis from a large multicenter cohort incorporating 14,433 HIV-1-infected patients in Germany. Treatment-naive patients beginning antiretroviral therapy (ART) with CD41 cell counts ,200 cells/lL who achieved complete and sustained viral suppression ,50 copies/mL (n 5 1318) were stratified according to the duration of immuno-virological discordance (failure to achieve a CD41 cell count >200 cells/lL). Groups were compared by descriptive and Poisson statistics. The time-varying discordance status was analyzed in a multivariable Cox model. Results. During a total of 5038 person years of follow-up, 42 new AIDS events occurred. The incidence rate of new AIDS events was highest in the initial 6 months of complete viral suppression (immuno-virological discordance group, 55.06; 95% confidence interval [CI], 30.82-90.82; and immune responder group, 24.54; 95% CI, 10.59-48.35) and decreased significantly by 65% per year in patients with immuno-virological discordance (incidence risk ratio, 0.35; 95% CI, 0.14-0.92; P 5 .03). Immuno-virological discordance and prior AIDS diagnosis were independently associated with new AIDS events (hazard ratio, 3.10; 95% CI, 1.09-8.82; P 5 .03). Conclusion. Compared with immune responders, patients with immuno-virological discordance seem to remain at increased risk for AIDS. Absolute risk is greatly reduced after the first 6 months of complete viral suppression.
Background/Aims: A unusually high rate of HCV-infected individuals in whom the HCV genotype canno... more Background/Aims: A unusually high rate of HCV-infected individuals in whom the HCV genotype cannot be ascertained by means of single PCR and LIPA procedures has recently been reported in our area. The aim of the present study was to investigate the epidemiological, clinical and molecular characteristics of these patients. Metkk Cross-sectional study. Eighty anti-HCVpositive patients with chronic liver disease, 45 (56.25%) of them intravenous drug users, were included. HCV genotyping was carried out in all patients using commercial single PCR and LIPA procedures Samples where no HCV RNA amplification and/or indeterminate HCV genotype were found were also tested by means of a nested PCR. HCV viral load was measured in all patients. Results: HCV genotyping was not achieved in 23 (28.75%) individuals. No amplification of HCV RNA EPATITIS C virus (HCV) is the most frequent cause
The Journals of Gerontology Series A: Biological Sciences and Medical Sciences, 2014
Human thymus is completely developed in late fetal stages and its function peaks in newborns. Aft... more Human thymus is completely developed in late fetal stages and its function peaks in newborns. After the first year of life, the thymus undergoes a progressive atrophy that dramatically decreases de novo T-lymphocyte maturation. Hormonal signaling and changes in the microRNA expression network are identified as underlying causes of human thymus involution. However, specific pathways involved in the age-related loss of thymic function remain unknown. In this study, we analyzed differential gene-expression profile and microRNA expression in elderly (70 years old) and young (less than 10 months old and 11 years old) human thymic samples. Our data have shown that WNT pathway deregulation through the overexpression of different inhibitors by the nonadipocytic component of the human thymus stimulates the age-related involution. These results are of particular interest because interference of WNT signaling has been demonstrated in both animal models and in vitro studies, with the three major hallmarks of thymic involution: (i) epithelial structure disruption, (ii) adipogenic process, and (iii) thymocyte development arrest. Thus, our results suggest that secreted inhibitors of the WNT pathway could be explored as a novel therapeutical target in the reversal of the age-related thymic involution.
Phenotypic plasticity can contribute to the process of adaptive radiation by facilitating populat... more Phenotypic plasticity can contribute to the process of adaptive radiation by facilitating population persistence in novel environments. West Indian Anolis lizards provide a classic example of an adaptive radiation, in which divergence has occurred along two primary ecological axes: structural microhabitat and climate. Adaptive plasticity in limb morphology is hypothesized to have facilitated divergence along the structural niche axis in Anolis, but very little work has explored plasticity in physiological traits. Here, we experimentally ask whether Puerto Rican Anolis cristatellus from mesic and xeric habitats differ in desiccation rates, and whether these lizards exhibit an acclimation response to changes in relative humidity. We first present microclimatic data collected at lizard perch sites that demonstrate that abiotic conditions experienced by lizards differ between mesic and xeric habitat types. In Experiment 1, we measured desiccation rates of lizards from both habitats maintained under identical laboratory conditions. This experiment demonstrated that desiccation rates differ between populations; xeric lizards lose water more slowly than mesic lizards. In Experiment 2, lizards from each habitat were either maintained under the conditions of Experiment 1, or under extremely low relative humidity. Desiccation rates did not differ between lizards from the same habitat maintained under different treatments and xeric lizards maintained lower desiccation rates than mesic lizards within each treatment. Our results demonstrate that A. cristatellus does not exhibit an acclimation response to abrupt changes of hydric conditions, and suggest that tropical Anolis lizards might be unable to exhibit physiological plasticity in desiccation rates in response to varying climatic conditions.
Background: HIV-1-infected individuals progressively loss CD4 + T cells leading to immunosuppress... more Background: HIV-1-infected individuals progressively loss CD4 + T cells leading to immunosuppression and raising the risk of opportunistic infections. CD8 + T-cells play an important role in the immune response against virus infections through their TCR. Objective: To evaluate the CD8-TCR repertoire and immunologic markers in HIV-1-infected patients. Study design: Ten chronic HIV-1-infected individuals on prolonged effective antiretroviral treatment (ART) were analyzed at baseline (before treatment interruption), after at least one year of treatment interruption (TI) and after at least one year from ART resume (TR). Twenty-four TCR-V gene families were analyzed by a modified CDR3 spectratyping method in isolated CD8 + T-cells. Immune activation, exhaustion and subpopulation markers were analyzed by flow cytometry. Results: Expansion of V10, V14 and V15 families, associated with low cell activation and stable exhaustion markers, were found at TI. Moreover, an increment of effector memory cells was found. Besides, depletion of V20, V28, and V29 families, associated with an increase in cell activation and exhaustion markers, at TI were also found. These alterations seemed to be more pronounced in patients who had longer time from diagnosis. ART seemed to restore altered CD8 + T-cell repertoire and most of the immunologic markers. Conclusions: During TI (that was more pronounced in patients with longer HIV-1 infection) it was observed the expansion of V families correlated with decreased cell activation, while V families correlated with cell activation and exhaustion were depleted. These specific repertoire alterations reverted after ART resume.
Journal of Cardiothoracic and Vascular Anesthesia, 2009
The purpose of this study was to evaluate the influence of preoperative type I and II immune resp... more The purpose of this study was to evaluate the influence of preoperative type I and II immune responses on blood transfusion requirements. Design: A prospective and observational trial. Setting: A postcardiac surgery unit of a university hospital. Participants: Seventy-one consecutive patients undergoing elective cardiac surgery. Interventions: Blood samples drawn for laboratory analysis and immunologic study. Measurements and Main Results: Patients were divided into 2 groups according to blood transfusion requirements: <2 units (n ؍ 35) and >2 units of red blood cells (n ؍ 36). The preoperative immune response was assessed by flow cytometry, measuring the proportion of CD4 ؉ T helper cells producing cytokines, including Th1 response (interferon-␥ and tumor necrosis factor-␣ [TNF-␣]) and Th2 response (interleukin 4 and 10). Two logistic regression analyses (including and not including immunologic variables) were used to select and weight perioperative variables associated with an increased risk of transfusion. Three variables were found to be independent predictors of transfusion requirements when immunologic variables were not included: preoperative platelet count, preoperative hemoglobin, and hypertension. When all the variables were included, preoperative hemoglobin, cardiopulmonary bypass time, and the preoperative proportion of CD4؉ T cells producing TNF-␣ were associated with an increased risk of transfusion (Hosmer-Lemeshow, 0.33; c-index, 0.93), but preoperative platelet count and hypertension were not. Conclusions: A low preoperative Th1 immune response, as assessed by the proportion of CD4؉ T-helper-producing TNF-␣, was associated with a higher blood transfusion rate.
JAIDS Journal of Acquired Immune Deficiency Syndromes, 2006
Objective: To analyze the predictive capacity of thymic volume in CD4 T-cell loss after treatment... more Objective: To analyze the predictive capacity of thymic volume in CD4 T-cell loss after treatment interruption in HIV-infected patients with high nadir CD4 count. Methods: Thirty-nine HIV-infected patients with CD4 counts greater than or equal to 500 cells/KL, nadir CD4 counts greater than or equal to 250 cells/KL, and plasma viral loads less than 50 copies/mL for at least the past 12 months began a treatment interruption program. The event of interest for this study was the decrease of CD4 count below 350 cells/KL. Kaplan-Meier curves were used for all time-to-event analyses, and log-rank tests were used for comparison between groups in the univariate analysis. All variables with statistical association with CD4 T-cell loss were analyzed using multivariate Cox proportional hazards regression models. Results: Twenty-three percent of the patients had a decrease in CD4 count to less than 350 cells/KL. In the univariate analysis, only thymic volume was statistically significant with this event (P = 0.02). Nadir CD4 count nearly reached statistical significance. However, age, sex, HCV coinfection, CD4 count, T-cell receptor excision circleYbearing cells, and early viral load rebound did not show statistical differences. Thymic volume and CD4 T-cell loss were independently associated using Cox proportional hazards regression model (P = 0.04; relative risk, 0.76; 95% confidence interval, 0.59Y0.99). Conclusions: In this study, we demonstrate for the first time that thymic volume predicts CD4 T-cell loss in patients with nadir CD4 count greater than or equal to 250 cells/KL under treatment interruption.
1. Rising global temperatures are predicted to impact organisms in diverse ways. For ectotherms, ... more 1. Rising global temperatures are predicted to impact organisms in diverse ways. For ectotherms, recent broad-scale analyses have predicted global patterns of vulnerability to warming, with tropical species at higher risk of detrimental effects than temperate species. However, vulnerability results from complex interactions between environment, physiology and behaviour. For species that inhabit a diversity of habitat types, these interactions may change across their range. 2. We measured operative thermal environments (T e) and body temperatures (T b) of the tropical Caribbean lizard Anolis cristatellus at nine sites representing two habitat types: mesic and xeric forest. The thermal sensitivity of whole-organism physiological performance (i.e. sprint speed) of one mesic and one xeric population was also measured. Thermal and performance data were integrated to determine how habitat thermal variation, behavioural thermoregulation and thermal physiology influence current physiological performance capacity in the field. We then evaluate if habitat suitability and physiological capacity would change assuming climate warming of 3°C over the next century. 3. The mean T e of the xeric habitat was 4AE5°C warmer than that of the mesic habitat. However, behavioural thermoregulation by xeric lizards led to lesser differences in T b (3AE5°C) between habitat types. The thermal sensitivity of sprint performance was similar for mesic and xeric lizards, and lizards from both habitats maintain sprint capacities near 100%. Climate warming is predicted to influence mesic and xeric lizards differently. Xeric lizards currently live in a thermal environment near their upper temperature threshold, while mesic lizards do not. As a result, the number of suitable perch sites is predicted to decrease dramatically in the xeric but not the mesic habitat. In addition, the physiological capacity of mesic lizards is predicted to increase by approximately 4%, whereas a decrease of approximately 30% is predicted for xeric lizards. 4. We characterized variation in the current biophysical and ecophysiological conditions experienced by A. cristatellus by integrating fine-scale measurements of thermal microhabitats with data on body temperatures and physiological performance capacities. These data allowed us to explicitly demonstrate how variation in these parameters can influence population susceptibility to climate warming across a species range and highlight the utility of a mechanistic approach in studies of global climate change.
Why convergent evolution occurs among some species occupying similar habitats but not among other... more Why convergent evolution occurs among some species occupying similar habitats but not among others is a question that has received surprisingly little attention. Caribbean Anolis lizards, known for their extensive convergent evolution among islands in the Greater Antilles, are an appropriate group with which to address this question. Despite the well-documented pattern of between-island convergence, some Greater Antillean anoles are not obviously part of the convergence syndrome. One example involves aquatic anoles-species that are found near to and readily enter streams-which have evolved independently twice in the Caribbean and also twice on mainland Central America. Despite being found in similar habitats, no previous study has investigated whether aquatic anoles represent yet another case of morphological convergence. We tested this hypothesis by collecting morphological data for seven aquatic anole species and 29 species from the six convergent types of Greater Antillean habitat specialists. We failed to find evidence for morphological convergence: the two Caribbean aquatic species are greatly dissimilar to each other and to the Central American species, which, however, may be convergent upon each other. We suggest two possible reasons for this lack of convergence in an otherwise highly convergent system: either there is more than one habitat type occupied by anoles in the proximity of water, or there is more than one way to adapt to a single aquatic habitat. We estimate that almost all of the 113 species of Greater Antillean anoles occupy habitats that are also used by distantly related species, but only 15% of these species are not morphologically similar to their distantly related ecological counterparts. Comparative data from other taxa would help enlighten the question of why the extent of convergence is so great in some lineages and not in others.
Enfermedades Infecciosas y Microbiología Clínica, 2010
Estudio comparativo entre una té cnica de reacció n en cadena de la polimerasa en transcripció n ... more Estudio comparativo entre una té cnica de reacció n en cadena de la polimerasa en transcripció n reversa en tiempo real, un mé todo de enzimoinmunoaná lisis y el cultivo shell-vial en la detecció n de virus gripales A y B en pacientes adultos.
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