39 research outputs found
Genotoxic and Cytotoxic Studies of Beta-Sitosterol and Pteropodine in Mouse
Beta-sitosterol (BS) and pteropodine (PT) are constituents of various plants with pharmacological activities potentially useful to man. The chemicals themselves possess biomedical properties related to the modulation of the immune and the nervous systems, as well as to the inflammatory process. Therefore, safety evaluation of the compounds is necessary in regard to their probable beneficial use in human health. The present study evaluates their genotoxic and cytotoxic potential by determining the capacity of the compounds to induce sister chromatid exchanges (SCE), or to alter cellular proliferation kinetics (CPK) and the mitotic index (MI) in mouse bone marrow cells. Besides, it also determines their capacity to increase the rate of micronucleated polychromatic erythrocytes (MNPE) in peripheral mouse blood, and the relationship polychromatic erythrocytes/normochromatic erythrocytes (PE/NE) as an index of cytotoxicity. For the first assay, four doses of each compound were tested: 200, 400, 600, and 1000âmg/kg in case of BS, and 100, 200, 300, and 600âmg/kg for PT. The results in regard to both agents showed no SCE increase induced by any of the tested doses, as well as no alteration in the CPK, or in the MI. With respect to the second assay, the results obtained with the two agents were also negative for both the MNPE and the PE/NE index along the daily evaluation made for four days. In the present study, the highest tested dose corresponded to 80% of the LD(50) obtained for BS and to 78% in the case of PT. The results obtained establish that the studied agents have neither genotoxic nor cytotoxic effect on the model used, and therefore they encourage studies on their pharmacological properties
2. Cambios climĂĄticos del Holoceno
Existe una variabilidad natural del clima. Se debe tanto a factores externos (como el cambio de la Ăłrbita de la Tierra) como internos (como erupciones volcĂĄnicas o movimientos tectĂłnicos entre otros). Los paleo-climatĂłlogos estudian los cambios del clima del pasado a travĂ©s de complejos anĂĄlisis de sedimentos de lagos, de testigos de hielo de los glaciares o tambiĂ©n de estalagmitas de las cavernas. Estos registros son como libros donde estĂĄ escrita la historia del clima de la Tierra. Usando estos marcadores ambientales y gracias a los modelos climĂĄticos a diferentes escalas espaciales y de tiempo, los investigadores buscan discriminar cual es la parte natural del cambio climĂĄtico actual de la parte debida a la actividad humana y disminuir las incertidumbres en las proyecciones futuras del clima.Il existe une variabilitĂ© climatique naturelle. Elle est due aussi bien Ă des facteurs externes (comme le changement dâorbite de la Terre) quâinternes (comme les Ă©ruptions volcaniques ou les mouvements tectoniques entre autres). Les palĂ©o-climatologues Ă©tudient les changements du climat du passĂ© en rĂ©alisant des analyses complexes de sĂ©diments de lacs, de carottes glaciaires ou encore de stalagmites des grottes. Ces registres sont comme des livres oĂč est Ă©crite lâhistoire du climat de la Terre. A partir de ces marqueurs environnementaux et des modelĂ©s climatiques Ă diffĂ©rentes Ă©chelles dâespace et de temps, les chercheurs cherchent Ă connaĂźtre quelle part du changement climatique actuel est naturelle et quelle part est liĂ©e Ă lâactivitĂ© humaine et rĂ©duire les incertitudes dans les projections climatiques.There is natural climate variability. It ÂĄs due to both external factors (such as changes in Earthâs orbit) as well as internal factors (such as volcanic eruptions and tectonic movements among others). Paleoclimatologists study historic climate changes performance by complex analysis of lake sediments, ice cores or stalagmite caves. These records are like books in where the history of Earthâs climate has been written. Thanks to these environmental markers and the climate models at different scales of space and time, researchers seek to differentiate which part of the current climate change is natural and which part is due to human activity, in order to reduce uncertainties in future climate projections
Bats, Bat Flies, and Fungi: Exploring Uncharted Waters
Bats serve as hosts to many lineages of arthropods, of which the blood-sucking bat flies (Nycteribiidae and Streblidae) are the most conspicuous. Bat flies can in turn be parasitized by Laboulbeniales fungi, which are biotrophs of arthropods. This is a second level of parasitism, hyperparasitism, a severely understudied phenomenon. Four genera of Laboulbeniales are known to occur on bat flies, Arthrorhynchus on Nycteribiidae in the Eastern Hemisphere, Dimeromyces on Old World Streblidae, Gloeandromyces on New World Streblidae, and Nycteromyces on Streblidae in both hemispheres. In this chapter, we introduce the different partners of the tripartite interaction and discuss their species diversity, ecology, and patterns of specificity. We cover parasite prevalence of Laboulbeniales fungi on bat flies, climatic effects on parasitism of bat flies, and coevolutionary patterns. One of the most important questions in this tripartite system is whether habitat has an influence on parasitism of bat flies by Laboulbeniales fungi. We hypothesize that habitat disturbance causes parasite prevalence to increase, in line with the âdilution effect.â This can only be resolved based on large, non-biased datasets. To obtain these, we stress the importance of multitrophic field expeditions and international collaborations
Photography-based taxonomy is inadequate, unnecessary, and potentially harmful for biological sciences
The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & NemĂ©sio 2007; Donegan 2008, 2009; NemĂ©sio 2009aâb; Dubois 2009; Gentile & Snell 2009; Minelli 2009; Cianferoni & Bartolozzi 2016; Amorim et al. 2016). This question was again raised in a letter supported
by 35 signatories published in the journal Nature (Pape et al. 2016) on 15 September 2016. On 25 September 2016, the following rebuttal (strictly limited to 300 words as per the editorial rules of Nature) was submitted to Nature, which on
18 October 2016 refused to publish it. As we think this problem is a very important one for zoological taxonomy, this text is published here exactly as submitted to Nature, followed by the list of the 493 taxonomists and collection-based
researchers who signed it in the short time span from 20 September to 6 October 2016
Tree and shrub flora in the surroundings of the Parque Nacional do Iguaçu, Paranå State, Brazil: contribution to ecological restoration
Compilação atualizada das espécies de morcegos (Chiroptera) para a AmazÎnia Brasileira
COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study
Background:
The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms.
Methods:
International, prospective observational study of 60â109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms.
Results:
âTypicalâ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (â€â18 years: 69, 48, 23; 85%), older adults (â„â70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each Pâ<â0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country.
Interpretation:
This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men