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1.
PLoS One ; 18(7): e0288067, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37405993

RESUMO

Bark beetle infestations have historically been primary drivers of stand thinning in Mexican pine forests. However, bark beetle impacts have become increasingly extensive and intense, apparently associated with climate change. Our objective was to describe the possible association between abundance of bark beetle flying populations and the occurrence of given value intervals of temperature, precipitation and their balance, in order to have a better comprehension of the climatic space that might trigger larger insect abundances, an issue relevant in the context of the ongoing climatic change. Here, we monitored the abundance of two of the most important bark beetle species in Mexico, Dendroctonus frontalis and D. mexicanus. We sampled 147 sites using pheromone-baited funnel traps along 24 altitudinal transects in 11 Mexican states, from northwestern Chihuahua to southeastern Chiapas, from 2015 to 2017. Through mixed model analysis, we found that the optimum Mean Annual Temperatures were 17°C-20°C for D. frontalis in low-elevation pine-oak forest, while D. mexicanus had two optimal intervals: 11-13°C and 15-18°C. Higher atmospheric Vapor Pressure Deficit (≥ 1.0) was correlated with higher D. frontalis abundances, indicating that warming-amplified drought stress intensifies trees' vulnerability to beetle attack. As temperatures and drought stress increase further with projected future climatic changes, it is likely that these Dendroctonus species will increase tree damage at higher elevations. Pine forests in Mexico are an important source of livelihood for communities inhabiting those areas, so providing tools to tackle obstacles to forest growth and health posed by changing climate is imperative.


Assuntos
Besouros , Pinus , Gorgulhos , Animais , México , Conservação dos Recursos Naturais , Florestas , Árvores
2.
PeerJ ; 10: e13812, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35942126

RESUMO

Background: In the projected climate change scenarios, assisted migration might play an important role in the ex situ conservation of the threatened plant species, by translocate them to similar suitable habitats outside their native distributions. However, it is unclear if such habitats will be available for the Rare Endemic Plant Species (REPS), because of their very restricted habitats. The aims of this study were to perform a population size assessment for the REPS Picea martinezii Patterson and Picea mexicana Martínez, and to evaluate the potential species distributions and their possibilities for assisted migration inside México and worldwide. Methods: We performed demographic censuses, field surveys in search for new stands, and developed distribution models for Last Glacial Maximum (22,000 years ago), Middle Holocene (6,000 years ago), current (1961-1990) and future (2050 and 2070) periods, for the whole Mexican territory (considering climatic, soil, geologic and topographic variables) and for all global land areas (based only on climate). Results: Our censuses showed populations of 89,266 and 39,059 individuals for P. martinezii and P. mexicana, respectively, including known populations and new stands. Projections for México indicated somewhat larger suitable areas in the past, now restricted to the known populations and new stands, where they will disappear by 2050 in a pessimistic climatic scenario, and scarce marginal areas (p = 0.5-0.79) remaining only for P. martinezii by 2070. Worldwide projections (based only on climate variables) revealed few marginal areas in 2050 only in México for P. martinezii, and several large areas (p ≥ 0.5) for P. mexicana around the world (all outside México), especially on the Himalayas in India and the Chungyang mountains in Taiwan with highly suitable (p ≥ 0.8) climate habitats in current and future (2050) conditions. However, those suitable areas are currently inhabited by other endemic spruces: Picea smithiana (Wall.) Boiss and Picea morrisonicola Hayata, respectively. Conclusions: Assisted migration would only be an option for P. martinezii on scarce marginal sites in México, and the possibilities for P. mexicana would be continental and transcontinental translocations. This rises two possible issues for future ex situ conservation programs: the first is related to whether or not consider assisted migration to marginal sites which do not cover the main habitat requirements for the species; the second is related to which species (the local or the foreign) should be prioritized for conservation when suitable habitat is found elsewhere but is inhabited by other endemic species. This highlights the necessity to discuss new policies, guidelines and mechanisms of international cooperation to deal with the expected high species extinction rates, linked to projected climate change.


Assuntos
Picea , Mudança Climática , Ecossistema , Espécies em Perigo de Extinção , México , Plantas
3.
Ecol Appl ; 30(2): e02041, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31758621

RESUMO

The high biodiversity of the Mexican montane forests is concentrated on the Trans-Mexican Volcanic Belt, where several Protected Natural Areas exist. Our study examines the projected changes in suitable climatic habitat for five conifer species that dominate these forests. The species are distributed sequentially in overlapping altitudinal bands: Pinus hartwegii at the upper timberline, followed by Abies religiosa, the overwintering host of the Monarch butterfly at the Monarch Butterfly Biosphere Reserve, P. pseudostrobus, the most important in economic terms, and P. devoniana and P. oocarpa, which are important for resin production and occupy low altitudes where montane conifers merge with tropical dry forests. We fit a bioclimatic model to presence-absence observations for each species using the Random Forests classification tree with ground plot data. The models are driven by normal climatic variables from 1961 to 1990, which represents the reference period for climate-induced vegetation changes. Climate data from an ensemble of 17 general circulation models were run through the classification tree to project current distributions under climates described by the RCP 6.0 watts/m2 scenario for the decades centered on years 2030, 2060 and 2090. The results suggest that, by 2060, the climate niche of each species will occur at elevations that are between 300 to 500 m higher than at present. By 2060, habitat loss could amount to 46-77%, mostly affecting the lower limits of distribution. The two species at the highest elevation, P. hartwegii and A. religiosa, would suffer the greatest losses while, at the lower elevations, P. oocarpa would gain the most niche space. Our results suggest that conifers will require human assistance to migrate altitudinally upward in order to recouple populations with the climates to which they are adapted. Traditional in situ conservation measures are likely to be equivalent to inaction and will therefore be incapable of maintaining current forest compositions.


Assuntos
Traqueófitas , Biodiversidade , Mudança Climática , Ecossistema , México
4.
Biochim Biophys Acta ; 1860(6): 1163-72, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-26922831

RESUMO

BACKGROUND: Acetate is an end-product of the PPi-dependent fermentative glycolysis in Entamoeba histolytica; it is synthesized from acetyl-CoA by ADP-forming acetyl-CoA synthetase (ACS) with net ATP synthesis or from acetyl-phosphate by a unique PPi-forming acetate kinase (AcK). The relevance of these enzymes to the parasite ATP and PPi supply, respectively, are analyzed here. METHODS: The recombinant enzymes were kinetically characterized and their physiological roles were analyzed by transcriptional gene silencing and further metabolic analyses in amoebae. RESULTS: Recombinant ACS showed higher catalytic efficiencies (Vmax/Km) for acetate formation than for acetyl-CoA formation and high acetyl-CoA levels were found in trophozoites. Gradual ACS gene silencing (49-93%) significantly decreased the acetate flux without affecting the levels of glycolytic metabolites and ATP in trophozoites. However, amoebae lacking ACS activity were unable to reestablish the acetyl-CoA/CoA ratio after an oxidative stress challenge. Recombinant AcK showed activity only in the acetate formation direction; however, its substrate acetyl-phosphate was undetected in axenic parasites. AcK gene silencing did not affect acetate production in the parasites but promoted a slight decrease (10-20%) in the hexose phosphates and PPi levels. CONCLUSIONS: These results indicated that the main role of ACS in the parasite energy metabolism is not ATP production but to recycle CoA for glycolysis to proceed under aerobic conditions. AcK does not contribute to acetate production but might be marginally involved in PPi and hexosephosphate homeostasis. SIGNIFICANCE: The previous, long-standing hypothesis that these enzymes importantly contribute to ATP and PPi supply in amoebae can now be ruled out.


Assuntos
Acetato Quinase/fisiologia , Acetato-CoA Ligase/fisiologia , Difosfatos/metabolismo , Entamoeba histolytica/metabolismo , Acetato Quinase/genética , Acetato-CoA Ligase/genética , Acetatos/metabolismo , Trifosfato de Adenosina/metabolismo , Metabolismo Energético , Etanol/metabolismo , Glicólise
5.
Biochim Biophys Acta ; 1853(12): 3266-78, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26434996

RESUMO

The role of p53 as modulator of OxPhos and glycolysis was analyzed in HeLa-L (cells containing negligible p53 protein levels) and HeLa-H (p53-overexpressing) human cervix cancer cells under normoxia and hypoxia. In normoxia, functional p53, mitochondrial enzyme contents, mitochondrial electrical potential (ΔΨm) and OxPhos flux increased in HeLa-H vs. HeLa-L cells; whereas their glycolytic enzyme contents and glycolysis flux were unchanged. OxPhos provided more than 70% of the cellular ATP and proliferation was abolished by anti-mitochondrial drugs in HeLa-H cells. In hypoxia, both cell proliferations were suppressed, but HeLa-H cells exhibited a significant decrease in OxPhos protein contents, ΔΨm and OxPhos flux. Although glycolytic function was also diminished vs. HeLa-L cells in hypoxia, glycolysis provided more than 60% of cellular ATP in HeLa-H cells. The energy metabolism phenotype of HeLa-H cells was reverted to that of HeLa-L cells by incubating with pifithrin-α, a p53-inhibitor. In normoxia, the energy metabolism phenotype of breast cancer MCF-7 cells was similar to that of HeLa-H cells, whereas p53shRNAMCF-7 cells resembled the HeLa-L cell phenotype. In hypoxia, autophagy proteins and lysosomes contents increased 2-5 times in HeLa-H cells suggesting mitophagy activation. These results indicated that under normoxia p53 up-regulated OxPhos without affecting glycolysis, whereas under hypoxia, p53 down-regulated both OxPhos (severely) and glycolysis (weakly). These p53 effects appeared mediated by the formation of p53-HIF-1α complexes. Therefore, p53 exerts a dual and contrasting regulatory role on cancer energy metabolism, depending on the O2level.


Assuntos
Neoplasias da Mama/metabolismo , Metabolismo Energético , Proteína Supressora de Tumor p53/fisiologia , Neoplasias do Colo do Útero/metabolismo , Neoplasias da Mama/patologia , Divisão Celular , Hipóxia Celular , Feminino , Células HeLa , Humanos , Células MCF-7 , Neoplasias do Colo do Útero/patologia
6.
J Hazard Mater ; 288: 104-12, 2015 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-25698571

RESUMO

The facultative protist Euglena gracilis, a heavy metal hyper-accumulator, was grown under photo-heterotrophic and extreme conditions (acidic pH, anaerobiosis and with Cd(2+)) and biochemically characterized. High biomass (8.5×10(6)cellsmL(-1)) was reached after 10 days of culture. Under anaerobiosis, photosynthetic activity built up a microaerophilic environment of 0.7% O2, which was sufficient to allow mitochondrial respiratory activity: glutamate and malate were fully consumed, whereas 25-33% of the added glucose was consumed. In anaerobic cells, photosynthesis but not respiration was activated by Cd(2+) which induced higher oxidative stress. Malondialdehyde (MDA) levels were 20 times lower in control cells under anaerobiosis than in aerobiosis, although Cd(2+) induced a higher MDA production. Cd(2+) stress induced increased contents of chelating thiols (cysteine, glutathione and phytochelatins) and polyphosphate. Biosorption (90%) and intracellular accumulation (30%) were the mechanisms by which anaerobic cells removed Cd(2+) from medium, which was 36% higher versus aerobic cells. The present study indicated that E. gracilis has the ability to remove Cd(2+) under anaerobic conditions, which might be advantageous for metal removal in sediments from polluted water bodies or bioreactors, where the O2 concentration is particularly low.


Assuntos
Cádmio/metabolismo , Euglena gracilis/metabolismo , Anaerobiose , Biodegradação Ambiental , Biomassa , Reatores Biológicos , Cádmio/farmacologia , Carbono/metabolismo , Meios de Cultura , Euglena gracilis/efeitos dos fármacos , Euglena gracilis/crescimento & desenvolvimento , Glicólise , Cinética , Fotossíntese
7.
PLoS One ; 10(2): e0117331, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25706146

RESUMO

Methanosarcina acetivorans, considered a strict anaerobic archaeon, was cultured in the presence of 0.4-1% O2 (atmospheric) for at least 6 months to generate air-adapted cells; further, the biochemical mechanisms developed to deal with O2 were characterized. Methane production and protein content, as indicators of cell growth, did not change in air-adapted cells respect to cells cultured under anoxia (control cells). In contrast, growth and methane production significantly decreased in control cells exposed for the first time to O2. Production of reactive oxygen species was 50 times lower in air-adapted cells versus control cells, suggesting enhanced anti-oxidant mechanisms that attenuated the O2 toxicity. In this regard, (i) the transcripts and activities of superoxide dismutase, catalase and peroxidase significantly increased; and (ii) the thiol-molecules (cysteine + coenzyme M-SH + sulfide) and polyphosphate contents were respectively 2 and 5 times higher in air-adapted cells versus anaerobic-control cells. Long-term cultures (18 days) of air-adapted cells exposed to 2% O2 exhibited the ability to form biofilms. These data indicate that M. acetivorans develops multiple mechanisms to contend with O2 and the associated oxidative stress, as also suggested by genome analyses for some methanogens.


Assuntos
Metano/biossíntese , Methanosarcina/metabolismo , Estresse Oxidativo , Oxigênio/metabolismo , Ar , Genoma Microbiano , Metano/metabolismo , Methanosarcina/genética , Methanosarcina/crescimento & desenvolvimento , Peroxidase/genética , Polifosfatos/metabolismo , Espécies Reativas de Oxigênio/metabolismo
8.
Cell Microbiol ; 17(7): 1037-51, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25611463

RESUMO

Adhesion to cells, cytotoxicity and proteolysis are functions required for virulence and pathogenicity of Entamoeba histolytica. However, there was no correlation between these in vitro functions and the early elimination of non-pathogenic E. dispar and non-virulent E. histolytica (nvEh) in experimental amoebic liver abscesses developed in hamsters. Thus, additional functions may be involved in amoebic pathogenicity and virulence. In the present study, an integral experimental assessment, including innovative technologies for analyses of amoebal pathophysiology, cell biology, biochemistry and transcriptomics, was carried out to elucidate whether other cellular processes are involved in amoebal pathogenicity and virulence. In comparison with virulent E. histolytica, the data indicated that the main reasons for the early clearance of nvEh from hamster liver are decreased intracellular H2 O2 detoxification rate and deficient heat shock protein expression, whereas for E. dispar, it is a relatively lower capacity for O2 reduction. Therefore, maintenance of an intracellular hypoxic environment combined with the induction of an adequate parasite response to oxidative stress are essential requirements for Entamoeba survival in the liver, and therefore for pathogenicity.


Assuntos
Entamoeba histolytica/patogenicidade , Resposta ao Choque Térmico , Interações Hospedeiro-Patógeno , Estresse Oxidativo , Animais , Sobrevivência Celular , Cricetinae , Fígado/parasitologia , Fígado/patologia , Virulência
9.
FEBS Lett ; 587(2): 178-84, 2013 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-23201265

RESUMO

By applying metabolic control analysis and inhibitor titration we determined the degree of control (flux control coefficient) of pyruvate:ferredoxin oxidoreductase (PFOR) and bifunctional aldehyde-alcohol dehydrogenase (ADHE) over the fluxes of fermentative glycolysis of Entamoeba histolytica subjected to aerobic conditions. The flux-control coefficients towards ethanol and acetate formation determined for PFOR titrated with diphenyleneiodonium were 0.07 and 0.09, whereas for ADHE titrated with disulfiram were 0.33 and -0.19, respectively. ADHE inhibition induced significant accumulation of glycolytic intermediates and lower ATP content. These results indicate that ADHE exerts significant flux-control on the carbon end-product formation of amoebas subjected to aerobic conditions.


Assuntos
Ácido Acético/metabolismo , Álcool Desidrogenase/metabolismo , Aldeído Oxirredutases/metabolismo , Entamoeba histolytica/metabolismo , Proteínas de Protozoários/metabolismo , Aerobiose , Álcool Desidrogenase/antagonistas & inibidores , Aldeído Oxirredutases/antagonistas & inibidores , Dissulfiram/farmacologia , Entamoeba histolytica/efeitos dos fármacos , Inibidores Enzimáticos/farmacologia , Etanol/metabolismo , Glicólise/efeitos dos fármacos , Cinética , Redes e Vias Metabólicas , Oniocompostos/farmacologia , Proteínas de Protozoários/antagonistas & inibidores , Piruvato Sintase/antagonistas & inibidores , Piruvato Sintase/metabolismo , Trofozoítos/efeitos dos fármacos , Trofozoítos/metabolismo
10.
Microbiology (Reading) ; 157(Pt 12): 3469-3482, 2011 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22130740

RESUMO

The Trichomonas vaginalis 120 kDa protein adhesin (AP120) is induced under iron-rich conditions and has sequence homology with pyruvate:ferredoxin oxidoreductase A (PFO A), a hydrogenosomal enzyme that is absent in humans. This homology raises the possibility that, like AP120, PFO might be localized to the parasite surface and participate in cytoadherence. Here, the cellular localization and function of PFO that was expressed under various iron concentrations was investigated using a polyclonal antibody generated against the 50 kDa recombinant C-terminal region of PFO A (anti-PFO50). In Western blot assays, this antibody recognized a 120 kDa protein band in total protein extracts, and proteins with affinity to the surface of HeLa cells from parasites grown under iron-rich conditions. In addition to localization that is typical of hydrogenosomal proteins, PFOs that were expressed under iron-rich conditions were found to localize at the surface. This localization was demonstrated using immunofluorescence and co-localization assays, as well as immunogold transmission electron microscopy. In addition to describing its enzyme activity, we describe a novel function in trichomonal host interaction for the PFO localized on the parasite surface. The anti-PFO50 antibody reduced the levels of T. vaginalis adherence to HeLa cell monolayers in a concentration-dependent manner. Thus, T. vaginalis PFO is an example of a surface-associated cell-binding protein that lacks enzyme activity and that is involved in cytoadherence. Additionally, PFO behaves like AP120 in parasites grown under iron-rich conditions. Therefore, these data suggest that AP120 and PFO A are encoded by the same gene, namely pfo a.


Assuntos
Proteínas de Membrana/metabolismo , Piruvato Sintase/metabolismo , Trichomonas vaginalis/enzimologia , Trichomonas vaginalis/patogenicidade , Animais , Adesão Celular , Células Epiteliais/parasitologia , Feminino , Células HeLa , Humanos , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Microscopia de Fluorescência , Microscopia Imunoeletrônica , Dados de Sequência Molecular , Coelhos , Análise de Sequência de DNA
11.
Rev. colomb. cienc. pecu ; 24(1): 29-37, ene,-mar. 2011. ilus, tab
Artigo em Espanhol | LILACS | ID: lil-636075

RESUMO

Some arthropod species are vectors of diseases to human's beings, domestic and sylvatic animals acting as biological or mechanical vectors of important pathogens. They produce direct damage due to feeding habits and attachment to different parts of animals and humans bodies. The aim of this study was to identify different species of ectoparasites from wild birds located at "Centro de Atención y Valoración de Fauna Silvestre del area metropolitana del Valle de Aburrá". From October 2006 to November 2007 a descriptive longitudinal study was done in 43 birds infested with ectoparasites. A total of 202 ectoparasites belonging to Diptera and Phthiraptera (Insecta) orders and Parasitiformes mites (Arachnida: Acari) were found.The Phtiraptera order shows the highest diversity with 18 species all of them belonging to Mallophaga group. From Diptera order, one specie was identified and ten larvae from Muscidae family was identified too, from Acari three genera of the Astigmata and Mesostigmata soborders was identified. The results of this study allow us to expand the host range of Bonnetella genera to Ramphastos citroelaemus specie. Also the presence of Menacanthus eurysternus and Colpocephalum turbinatum is registered in Pelecanus occidentalis and Buteo platypterus. The development of microbiological and parasitological studies to identify pathogen species in these ectoparasites is recommended to establish disease transmission risk and prevention and control strategies of zoonotic diseases.


Algunas especies de artrópodos son causantes de enfermedades en humanos, animales domésticos y silvestres, actuando como vectores biológicos y mecánicos de importantes patógenos; además de los daños directos que ocasionan por sus hábitos alimenticios y de fijación en diferentes partes del cuerpo de sus hospederos. El objetivo de este trabajo fue identificar las diferentes especies de ectoparásitos presentes en las aves silvestres ingresadas al Centro de Atención y Valoración de Fauna Silvestre (CAV) del área metropolitana del Valle de Aburrá. Se realizó un estudio descriptivo longitudinal, en el cual se analizaron 43 aves infestadas con ectoparásitos que ingresaron al centro, durante el periodo de octubre de 2006 a noviembre de 2007. Se colectaron 202 ectoparásitos de los órdenes Pthiraptera, Diptera y ácaros del orden Parasitiformes (Arachnida). El orden Phthiraptera presentó la mayor diversidad, con 18 especies, todas del grupo Mallophaga. Del orden Diptera se identificó una especie y diez larvas de la familia Muscidae, mientras que en los ácaros se identificaron tres géneros, de los subórdenes: Astigmata y Mesostigmata. Los resultados de este estudio permiten ampliar el rango de hospederos del género Bonnetella a la especie Ramphastos citroelaemus. Además se registra la presencia de Menacanthus eurysternus y Colpocephalum turbinatum en Pelecanus occidentalis y Buteo platypterus. Se recomienda realizar estudios microbiológicos y parasitológicos para identificar las especies patógenas presentes en estos ectoparásitos, que permitan establecer el riesgo de transmisión de enfermedades y proponer medidas de prevención y control de enfermedades zoonóticas.


Algumas espécies de artrópodes são causadores de doenças tanto para os humanos como para animais domésticos e silvestres, atuando como vetores biológicos e mecânicos de patogenias importantes, além de causar danos diretos por seus hábitos alimentares e a sua fixação em diferentes partes do corpo do hospedeiro. O objetivo foi identificar as diferentes espécies de ectoparasitas hachados em aves silvestres do "Centro de Atención y Valoración de Fauna Silvestre del area metropolitana del Valle de Aburrá". Foi feito um estudo descritivo longitudinal em 43 aves as quais ingressaram ao Centro infestadas com ectoparasitas desde outubro de 2006 até novembro de 2007. Coletaram-se 202 ectoparasitas das ordens Phthiraptera, Diptera e ácaros da ordem Parasitiformes (Arachnida). A ordem Phthiraptera apresentou a maior diversidade, com 18 espécies todas do grupo Mallophaga, Da ordem Díptera identificou-se uma espécie e dez larvas da família Muscidae, enquanto nos ácaros identificaram-se três gêneros das subordens Astigmata y Mesostigmata. Os resultados do estudo permitem ampliar o rango dos hospedeiros do gênero Bonnetella á espécie Ramphastos citroelaemus. Alem de mais se registra a presencia de Menacanthus eurysternus y Colpocephalum turbinatum em Pelecanus occidentalis y Buteo platypterus. Recomenda-se realizar estudos microbiológicos e parasitológicos para identificar as espécies patogenias presentes nestes ectoparasitas que permitam estabelecer o risco de transmissão de doenças e propor medidas de prevenção e controle de zoonoses.

12.
CES med ; 24(2): 107-107, jul.-dic. 2010.
Artigo em Espanhol | LILACS | ID: lil-612538

RESUMO

La tripanosomosis bovina es unenfermedad causada por el protozoo Trypanosoma vivax, afecta a bovinos, ovinos y búfalos. Estaenfermedad causa grandes pérdidas económicas debidas a abortos, disminución en la producciónde leche y altos costos en tratamiento veterinario.El T. vivax fue introducido a Suraméricaa través de animales traídos del África, donde lamosca Glossina es el vector biológico del hemoparásito.En Colombia, T. vivax se ha adaptadoa nuevas condiciones ambientales y ecológicas,causando infecciones endémicas en el ganado de zonas cálidas. Muchos aspectos epidemiológicosson aún desconocidos. El propósito delestudio fue identificar los posibles vectores de la tripanosomosis bovina y registrar la densidady la diversidad de tábanos en la zona.


Assuntos
Animais , Vetores de Doenças , Trypanosoma vivax , Tripanossomíase Bovina
13.
Cyberpsychol Behav ; 12(6): 699-705, 2009 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-19886825

RESUMO

Many studies have shown the ability of media--television, movies, and virtual reality (VR) experiences--to elicit emotions. Nevertheless, it is still unclear how the different factors involved--user related and medium related--play a role in producing an emotional response during a VR experience. We investigate this issue, analyzing the role played by the cultural and technological backgrounds of the users in the emotional responses to VR. Specifically, we use the "core affect" model of emotions developed by Russell (2003) to explore how these factors influence the way in which participants experience virtual worlds. Our sample includes 20 Mexican participants: 8 living in El Tepeyac, a small rural and isolated Mexican village characterized by a very primitive culture, and 12 high civilized inhabitants of Mexico City. The "Green Valley," a noninteractive, relaxing immersive environment showing a mountain landscape around a calm lake, was used to induce relaxation in the two groups during an ambulatory surgical operation. To investigate the effects of VR on the relaxation process, we measured participants' physiological (heart rate) and emotional (VAS-A) responses before, during, and after the operation. The results show that VR significantly modified the core affect (reduced arousal) in all participants but that the final emotional response produced by this change was influenced by the attribution process: the civilized inhabitants of Mexico City, who were able to attribute the reduced arousal to the VR experience, reported a significant reduction in the self-reported level of anxiety, while people from El Tepeyac showed a reduction in their physiological reactions but not in their perceived anxiety.


Assuntos
Ansiedade/psicologia , Comparação Transcultural , Emoções , Terapia de Relaxamento/métodos , Relaxamento/psicologia , Adulto , Idoso , Simulação por Computador , Meio Ambiente , Feminino , Frequência Cardíaca/fisiologia , Humanos , Masculino , México , Pessoa de Meia-Idade , Inquéritos e Questionários , Terapia Assistida por Computador/métodos , Interface Usuário-Computador
14.
Int J Parasitol ; 39(6): 693-702, 2009 May.
Artigo em Inglês | MEDLINE | ID: mdl-19073188

RESUMO

Entamoeba histolytica virulence has been attributed to several amoebic molecules such as adhesins, amoebapores and cysteine proteinases, but supporting evidence is either partial or indirect. In this work we compared several in vitro and in vivo features of both virulent E. histolytica (vEh) and non-virulent E. histolytica (nvEh) axenic HM-1 IMSS strains, such as complement resistance, proteinase activity, haemolytic, phagocytic and cytotoxic capacities, survival in mice caecum, and susceptibility to O(2). The only difference observed was a higher in vitro susceptibility of nvEh to O(2). The molecular mechanism of that difference was analyzed in both groups of amoebae after high O(2) exposure. vEh O(2) resistance correlated with: (i) higher O(2) reduction (O(2)(-) and H(2)O(2) production); (ii) increased H(2)O(2) resistance and thiol peroxidase activity, and (iii) reversible pyruvate: ferredoxin oxidoreductase (PFOR) inhibition. Despite the high level of carbonylated proteins in nvEh after O(2) exposure, membrane oxidation by reactive oxygen species was not observed. These results suggest that the virulent phenotype of E. histolytica is related to the greater ability to reduce O(2) and H(2)O(2) as well as PFOR reactivation, whereas nvEh undergoes irreversible PFOR inhibition resulting in metabolic failure and amoebic death.


Assuntos
Entamoeba histolytica/fisiologia , Entamoeba histolytica/patogenicidade , Oxigênio/metabolismo , Oxigênio/toxicidade , Estresse Fisiológico , Animais , Peróxido de Hidrogênio/metabolismo , Camundongos , Oxirredução , Peroxidase/metabolismo , Piruvato Sintase/antagonistas & inibidores , Superóxidos/metabolismo , Virulência
15.
Bol. malariol. salud ambient ; 48(1): 95-98, ene.-jul. 2008. tab
Artigo em Espanhol | LILACS | ID: lil-503687

RESUMO

En el municipio Valencia, departamento Córdoba, Colombia, se presenta una alta prevalencia de malaria. En promedio se presentan más de 3.000 casos anualmente, de los cuales 75% son producidos por Plasmodium vivax, 13% por Plasmodium falciparum y 12% de los casos son debidos a infecciones mixtas. En las veredas Mieles Medio, Mieles Abajo, San Rafael y Santo Domingo, se realizó un estudio de tipo descriptivo de corte transversal, para identificar las especies de Anopheles presentes en el área, determinar actividad de picadura y describir los criaderos más frecuentes. La captura de Anopheles adultos se realizó por el método de cebo humano protegido en áreas de intra y peridomicilio. El muestreo de larvas se hizo por el método del cucharón en los criaderos alrededor de las viviendas. Se hicieron mediciones de tasa de ataque (índice de picadura/hombre/ hora), tipo y tamaño de los criaderos y densidad larvaria. Se obtuvieron en total 203 anofelinos adultos correspondientes a cuatro especies: Anopheles (Nyssorhynchus) nuneztovari (91,1%), An. (Anopheles) neomaculipalpus (4,4%), An. (An.) pseudopunctipennis (4,0%) y Anopheles (Nys.) evansae (0,5%). El mayor pico de actividad de picadura lo presentó An. nuneztovari en el peridomicilio a las 21:00 horas, así mismo esta especie fue la que se halló en mayor densidad en los 80 criaderos positivos para larvas. Los resultados sugieren que An. nuneztovari es el vector primario de malaria en las veredas estudiadas.


Assuntos
Humanos , Anopheles , Malária/prevenção & controle , Plasmodium , Colômbia , Medicina Tropical
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