Contrasting Effects Of Land Use Intensity And Exotic Host Plants On The Specialization Of Interactions In Plant-herbivore Networks.

Human land use tends to decrease the diversity of native plant species and facilitate the invasion and establishment of exotic ones. Such changes in land use and plant community composition usually have negative impacts on the assemblages of native herbivorous insects. Highly specialized herbivores are expected to be especially sensitive to land use intensification and the presence of exotic plant species because they are neither capable of consuming alternative plant species of the native flora nor exotic plant species. Therefore, higher levels of land use intensity might reduce the proportion of highly specialized herbivores, which ultimately would lead to changes in the specialization of interactions in plant-herbivore networks. This study investigates the community-wide effects of land use intensity on the degree of specialization of 72 plant-herbivore networks, including effects mediated by the increase in the proportion of exotic plant species. Contrary to our expectation, the net effect of land use intensity on network specialization was positive. However, this positive effect of land use intensity was partially canceled by an opposite effect of the proportion of exotic plant species on network specialization. When we analyzed networks composed exclusively of endophagous herbivores separately from those composed exclusively of exophagous herbivores, we found that only endophages showed a consistent change in network specialization at higher land use levels. Altogether, these results indicate that land use intensity is an important ecological driver of network specialization, by way of reducing the local host range of herbivore guilds with highly specialized feeding habits. However, because the effect of land use intensity is offset by an opposite effect owing to the proportion of exotic host species, the net effect of land use in a given herbivore assemblage will likely depend on the extent of the replacement of native host species with exotic ones.

Long-term Efficacy And Safety Of Tenofovir Disoproxil Fumarate In Hiv-1-infected Adolescents Failing Antiretroviral Therapy: The Final Results Of Study Gs-us-104-0321.

Reports of long-term tenofovir disoproxil fumarate (TDF) treatment in HIV-infected adolescents are limited. We present final results from the open-label (OL) TDF extension following the randomized, placebo (PBO)-controlled, double-blind phase of GS-US-104-0321 (Study 321). HIV-infected 12- to 17-year-olds treated with TDF 300 mg or PBO with an optimized background regimen (OBR) for 24-48 weeks subsequently received OL TDF plus OBR in a single arm study extension. HIV-1 RNA and safety, including bone mineral density (BMD), was assessed in all TDF recipients. Eighty-one subjects received TDF (median duration 96 weeks). No subject died or discontinued OL TDF for safety/tolerability. At week 144, proportions with HIV-1 RNA <50 copies/mL were 30.4% (7 of 23 subjects with baseline HIV-1 RNA >1000 c/mL initially randomized to TDF), 41.7% (5 of 12 subjects with HIV-1 RNA <1000 c/mL who switched PBO to TDF) and 0% (0 of 2 subjects failed randomized PBO plus OBR with HIV-1 RNA >1000 c/mL and switched PBO to TDF). Viral resistance to TDF occurred in 1 subject. At week 144, median decrease in estimated glomerular filtration rate was 38.1 mL/min/1.73 m (n = 25). Increases in median spine (+12.70%, n = 26) and total body less head BMD (+4.32%, n = 26) and height-age adjusted Z-scores (n = 21; +0.457 for spine, +0.152 for total body less head) were observed at week 144. Five of 81 subjects (6%) had persistent >4% BMD decreases from baseline. Some subjects had virologic responses to TDF plus OBR, and TDF resistance was rare. TDF was well tolerated and can be considered for treatment of HIV-infected adolescents.

Atividade diaria e (in)atividade fisica na sociedade indigena Terena : Aldeias Buriti e Corrego do Meio

Universidade Estadual de Campinas . Faculdade de Educação Física