The Experts below are selected from a list of 198 Experts worldwide ranked by ideXlab platform
Eduardo Costas - One of the best experts on this subject based on the ideXlab platform.
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Rapid adaptation of some phytoplankton species to osmium as a result of spontaneous mutations
Ecotoxicology, 2014Co-Authors: Fernando Marvá, Camino García-balboa, Beatriz Baselga-cervera, Eduardo CostasAbstract:To understand the vulnerability of individual species to anthropogenic contamination, it is important to evaluate the different abilities of phytoplankton to respond to environmental changes induced by pollution. The ability of a species to adapt, rather than its Initial Tolerance, is the basis for survival under rapidly increasing levels of anthropogenic contamination. High doses of osmium (Os) cause massive destruction of diverse phytoplankton groups. In this study, we found that the coastal chlorophyte Tetraselmis suecica and the continental chlorophyte Dictyosphaerium chlorelloides were able to adapt to a lethal dose of Os. In these species, Os-resistant cells arose as a result of rare spontaneous mutations (at rates of approximately 10^−6 mutants per cell division) that occurred before exposure to Os. The mutants remained in the microalgal populations by means of mutation–selection balance. The huge size of phytoplankton populations ensures that there are always enough Os-resistant mutants to guarantee the survival of the population under Os pollution. In contrast, we observed that neither a haptophyte species from open ocean regions nor a cyanobacterium from continental freshwater were able to adapt to the lethal Os dose. Adaptation of phytoplankton to Os contamination is relevant because industrial activities are leading to a rapid increase in Os pollution worldwide.
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Estimating the capability of different phytoplankton groups to adapt to contamination: herbicides will affect phytoplankton species differently.
New Phytologist, 2010Co-Authors: I.e. Huertas, Mónica Rouco, Victoria López-rodas, Eduardo CostasAbstract:Summary •Investigating the differential capacity of the response of phytoplankton to human-induced environmental forcing has become a key issue to understanding further the future repercussions on the functioning of aquatic ecosystems. •The Initial Tolerance to the widely dispersed herbicide simazine was measured in diverse phytoplankton species. An experimental ratchet system maintaining large populations of dividing cells (which ensures the occurrence of rare spontaneous mutations that confer adaptation) and a strong selection pressure (which ensures the preservation of such mutations within the population) was later applied to estimate the capability of different groups of phytoplankton to adapt to simazine. •Initially, simazine doses between 0.05 and 0.15 ppm were able to inhibit 100% growth in all the species tested. However, a significant increase in simazine resistance was achieved in all derived populations during the ratchet experiment. The differential capacity for simazine adaptation was observed among the different species. •The capacity of different species to adapt to simazine can be explained in relation to taxonomic group, ploidy, growth rate and habitat preference. Haploid populations of continental Chlorophyta showed the greatest capacity to adapt to simazine. By contrast, populations of Haptophyta of open ocean regions were the group least capable of adapting to the herbicide.
Thomas F Babor - One of the best experts on this subject based on the ideXlab platform.
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Diagnosis of alcohol dependence in epidemiological surveys: an epidemic of youthful alcohol dependence or a case of measurement error?
Addiction (Abingdon England), 2020Co-Authors: Raul Caetano, Thomas F BaborAbstract:To review the literature on the prevalence of alcohol dependence according to age, presenting data suggesting that the increased prevalence of alcohol dependence among young adults may be inflated because of measurement error. Household surveys with random selection of respondents. General population. Survey respondents 12 years of age and older. Alcohol dependence. Data for male current drinkers show that 4.6% of adolescents (aged 12-17 years) meet criteria for past year dependence, and the rate increases to 8.5% in the 18-23 age group, decreasing thereafter. Symptom level prevalence estimates indicate that younger age groups report higher rates of Tolerance and withdrawal symptoms than older age groups. Young adults may be reporting Tolerance and withdrawal symptoms partly because the wording of structured interview schedules leads to confusion of binge drinking and its sequelae with physical symptoms of alcohol dependence. There is a need to examine whether young adults are confusing the sequelae of acute intoxication with alcohol withdrawal, and rapid Initial Tolerance with the classical Tolerance reported by alcoholics. Epidemiologists and clinicians need to be cautious of the tendency of structured psychiatric interviews to classify young adults as being alcohol-dependent. It may be useful to characterize individuals who meet alcohol dependence criteria at a young age (e.g. prior to age 25 years) as manifesting a form of 'adolescent alcohol dependence', which may represent a less severe form of alcohol use disorder than that observed in adults.
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Diagnosis of alcohol dependence in epidemiological surveys: an epidemic of youthful alcohol dependence or a case of measurement error?
Addiction, 2006Co-Authors: Raul Caetano, Thomas F BaborAbstract:Aim: To review the literature on the prevalence of alcohol dependence according to age, presenting data suggesting that the increased prevalence of alcohol dependence among young adults may be inflated because of measurement error. Household surveys with random selection of respondents. General population. Survey respondents 12 years of age and older. Alcohol dependence. Data for male current drinkers show that 4.6% of adolescents (aged 12-17 years) meet criteria for past year dependence, and the rate increases to 8.5% in the 18-23 age group, decreasing thereafter. Symptom level prevalence estimates indicate that younger age groups report higher rates of Tolerance and withdrawal symptoms than older age groups. Young adults may be reporting Tolerance and withdrawal symptoms partly because the wording of structured interview schedules leads to confusion of binge drinking and its sequelae with physical symptoms of alcohol dependence. There is a need to examine whether young adults are confusing the sequelae of acute intoxication with alcohol withdrawal, and rapid Initial Tolerance with the classical Tolerance reported by alcoholics. Epidemiologists and clinicians need to be cautious of the tendency of structured psychiatric interviews to classify young adults as being alcohol-dependent. It may be useful to characterize individuals who meet alcohol dependence criteria at a young age (e.g. prior to age 25 years) as manifesting a form of 'adolescent alcohol dependence', which may represent a less severe form of alcohol use disorder than that observed in adults. Language: en
George M Barnwell - One of the best experts on this subject based on the ideXlab platform.
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Initial Tolerance and tissue response to complete dentures by diabetic patients
Journal of Prosthodontics, 1992Co-Authors: Peter T Soderstrom, Richard R Seals, Robert M Morrow, Valerie A Murrah, George M BarnwellAbstract:Purpose The oral effects of diabetes in dentate patients have been studied extensively, but little clinical data has been collected with regards to edentulous patients who have diabetes. The purpose of this study was to investigate whether there are differences between diabetic and nondiabetic patients in Initial patient Tolerance and tissue response to complete dentures. Materials and Methods Complete dentures were constructed for 62 diabetic and 56 nondiabetic patients. Treatment followed accepted prosthodontic principles recommended for diabetic patients. Twenty-four hour and 1 week post-placement appointments consisted of a patient questionnaire, intraoral examinations and indicated adjustments. The variables studied were the differences between responses to the questionnaire and the frequency of type, location, and size of clinically visible areas of mucosal irritation reported on standardized tissue evaluation forms. Results Analysis of the responses to the questionnaire indicated diabetic patients reported xerostomia more often than nondiabetics. There were no statistically significant differences in Initial tissue response to new complete dentures between the diabetic and nondiabetic patients. A statistically significant difference in tissue response was reported within the diabetic group, significantly fewer diabetic patients exhibited oral irritations at the second examination than at the first examination. Conclusions The results of the present study indicate that when prosthodontic principles recommended for diabetic complete denture patients are followed, there are no clinically significant differences between diabetic and nondiabetic patients in Initial patient Tolerance and tissue response to complete dentures.
Karel De Schamphelaere - One of the best experts on this subject based on the ideXlab platform.
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the Initial Tolerance to sub lethal cd exposure is the same among ten naive pond populations of daphnia magna but their micro evolutionary potential to develop resistance is very different
Aquatic Toxicology, 2013Co-Authors: Marlies Messiaen, Colin R Janssen, Luc De Meester, Karel De SchamphelaereAbstract:Abstract Genetic variation complicates predictions of both the Initial Tolerance and the long-term (micro-evolutionary) response of natural Daphnia populations to chemical stressors from results of standard single-clone laboratory ecotoxicity tests. In order to investigate possible solutions to this problem, we aimed to compare the Initial sub-lethal Tolerance to Cd of 10 naive natural pond populations of Daphnia magna as well as their evolutionary potential to develop increased resistance. We did so by measuring reproductive performance of 120 clones, i.e. 12 clones hatched from the recent dormant egg bank of each of 10 populations, both in absence (Cd-free control) and presence of 4.4 μg Cd/L. We show that the Initial Tolerance , defined as the reproductive performance of individuals of the first generation exposed to Cd relative to that in a Cd-free control was not significantly different among the 10 studied pond populations and averaged 0.82 ± 0.04 over these populations. Moreover, these populations’ Initial Tolerances were also not significantly different from the mean Initial Tolerance of 0.87 ± 0.08 at 4.0 μg Cd/L measured for a group of 7 often-used laboratory clones, collected from a range of European ecotoxicity testing laboratories. This indicates that the Initial response of naive natural pond populations to sub-lethal Cd can be relatively accurately predicted from ecotoxicity test data from only a handful of laboratory clones. We then used estimates of broad-sense heritability of Cd Tolerance ( H 2 ) – based on the same dataset – as a proxy of these populations’ capacities to evolutionarily respond to Cd in terms of the development of increased resistance , which is here defined as the increase with time of the frequency of clones with a higher Cd Tolerance in the population (accompanied with an increase of mean Cd-Tolerance of the population above the Initial Tolerance). We show that the populations’ estimated H 2 values of Cd-Tolerance cover almost the entire theoretically possible range, ranging from not significantly different from zero (for five populations) to between 0.48 and 0.81 (for the five other populations). This indicates that, unlike the Initial Tolerance to Cd, the (long-term) micro-evolutionary response to Cd may be very different among natural pond populations. Therefore, we conclude that it may be very difficult to predict the long-term response of an unstudied population to chemical stress from Tolerance data on a sample of other populations. It is therefore suggested that new methods for forecasting long-term responses should be explored, such as the development of predictive models based on the combination of population-genomic and Tolerance time-series data.
Carol H Miao - One of the best experts on this subject based on the ideXlab platform.
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441 il2 plasmid treated hemophilia a mice show an increase in regulatory t cell population and Initial Tolerance to fviii
Molecular Therapy, 2016Co-Authors: Meghan J Lyle, Richard Y Fu, Carol H MiaoAbstract:Hemophilia A is an inherited X chromosomal linked recessive disease. Hemophilia A patients lack or possess low levels of functional FVIII protein, which results in an inability for the blood to clot when injury occurs. This inability to clot can result in major blood loss and potential death. The current treatment for patients with hemophilia A is FVIII protein replacement, but this treatment is expensive and often results in anti-FVIII immune responses, neutralizing the clotting effect. In order to overcome this potential immune response patients undergo a high dose regimen of FVIII to induce Tolerance. However, a third of patients still develop an immune response.Regulatory T (Treg) cells help balance T effector (Teff) cells through their suppressive function during an immune response and keep autoimmunity in check. Both of these cell types bind to interleukin 2 (IL2), a cytokine which promotes the differentiation, expansion and activation of these cell populations. Treg cells possess a high affinity epitope of the IL2 receptor. With a low dose of IL2, the Treg population outcompetes the Teff cells, leading to an increase in activation and number. The increased suppressive activity may induce Tolerance in hemophilia A mice treated with FVIII plasmid.Hemophilia A mice were hydrodynamically injected with either 2 µg or 5 µg IL2 plasmid and 50 µg FVIII plasmid, either sequentially (1 week apart) or simultaneously. Both plasmids were driven by a liver-specific promoter (hAAT-HCR). Cell staining data showed a marked increase in Treg cell population and activation, demonstrating that a small amount of IL2 plasmid incorporated into liver cells is enough to dramatically increase the Treg population. A larger increase of Teff cells were observed in mice treated with 5 µg IL2 plasmid than in mice treated with 2 µg IL2 plasmid. Importantly, Treg/Teff ratio was significantly increased in the 2 µg IL2 plasmid group in the first 3 weeks and maintained at increased levels over several weeks afterwards. ELISA showed an Initial higher level of IL2 production; IL2 expression dropped and maintained at low levels after one week. On Day 28-post FVIII plasmid injection, control mice had started to develop inhibitors associated with significant decrease of FVIII expression, while mice treated with IL2 plasmid showed no inhibitor development with persistent FVIII gene expression. The treated mice are monitored to determine the potential long term Tolerance effects induced by low dose IL2 plasmid. Using gene therapy to slightly increase the amount of a cytokine in patients could provide a better treatment option than existing drug regimens. FVIII protein is also extremely expensive, especially in the amounts needed for treating hemophilia A patients. Combined gene transfer of FVIII and IL2 plasmids has the potential to produce therapeutic FVIII and simultaneously prevent inhibitory antibody formation, therefore reducing the amount of expensive reagents needed, the number of doctor visits required, and the overall cost, potential morbidity and stress to the patient.