Climate severity and land-cover transformation determine plant community attributes in Colombian dry forests

Tropical dry forests (TDF) are known to be resource-limited due to a marked seasonality in precipitation. However, TDF are also shaped by factors such as solar radiation, wind speed, soil fertility, and land-cover transformation. Together, these factors may determine different gradients of environmental harshness that are likely to drive changes in plant community attributes. Here, we evaluated the effects of environmental harshness on plant community diversity and structure of Colombian TDF, based on floristic and environmental data from 15 1-ha permanent plots. We also analyzed these effects on legumes species only (including both deciduous and non-deciduous species), deciduous species only (including both legumes and non-legumes species), and on the whole community excluding either legumes or deciduous separately. Drier conditions and higher land-cover transformation had the strongest negative effects on species diversity, basal area (BA), and canopy height. Soil fertility, on the contrary, did not have a significant effect on any of the evaluated response variables. Interestingly, legumes maintained their diversity and BA along the climatic gradient, while deciduous species were negatively affected by drier conditions and by an increase in secondary vegetation at the landscape level. Our results suggest that although TDF are limited by water availability, land-cover transformation strongly increases environmental harshness. Yet, both legumes and deciduous species were differentially impacted by climatic and land transformation variables. Thus, to better understand TDF plant community attributes, it is necessary to consider these gradients and to disentangle their effects on different plant functional groups. Abstract in Spanish is available with online material. © 2019 The Association for Tropical Biology and Conservatio

Climate severity and land-cover transformation determine plant community attributes in Colombian dry forests

Tropical dry forests (TDF) are known to be resource-limited due to a marked seasonality in precipitation. However, TDF are also shaped by factors such as solar radiation, wind speed, soil fertility, and land-cover transformation. Together, these factors may determine different gradients of environmental harshness that are likely to drive changes in plant community attributes. Here, we evaluated the effects of environmental harshness on plant community diversity and structure of Colombian TDF, based on floristic and environmental data from 15 1-ha permanent plots. We also analyzed these effects on legumes species only (including both deciduous and non-deciduous species), deciduous species only (including both legumes and non-legumes species), and on the whole community excluding either legumes or deciduous separately. Drier conditions and higher land-cover transformation had the strongest negative effects on species diversity, basal area (BA), and canopy height. Soil fertility, on the contrary, did not have a significant effect on any of the evaluated response variables. Interestingly, legumes maintained their diversity and BA along the climatic gradient, while deciduous species were negatively affected by drier conditions and by an increase in secondary vegetation at the landscape level. Our results suggest that although TDF are limited by water availability, land-cover transformation strongly increases environmental harshness. Yet, both legumes and deciduous species were differentially impacted by climatic and land transformation variables. Thus, to better understand TDF plant community attributes, it is necessary to consider these gradients and to disentangle their effects on different plant functional groups. Abstract in Spanish is available with online material. © 2019 The Association for Tropical Biology and Conservatio

Porcine models for the metabolic syndrome, digestive and bone disorders: a general overview

The aim of this review article is to provide an overview of the role of pigs as a biomedical model for humans. The usefulness and limitations of porcine models have been discussed in terms of metabolic, cardiovascular, digestive and bone diseases in humans. Domestic pigs and minipigs are the main categories of pigs used as biomedical models. One drawback of minipigs is that they are in short supply and expensive compared with domestic pigs, which in contrast cost more to house, feed and medicate. Different porcine breeds show different responses to the induction of specific diseases. For example, ossabaw minipigs provide a better model than Yucatan for the metabolic syndrome as they exhibit obesity, insulin resistance and hypertension, all of which are absent in the Yucatan. Similar metabolic/physiological differences exist between domestic breeds (e.g. Meishan v. Pietrain). The modern commercial (e.g. Large White) domestic pig has been the preferred model for developmental programming due to the 2- to 3-fold variation in body weight among littermates providing a natural form of foetal growth retardation not observed in ancient (e.g. Meishan) domestic breeds. Pigs have been increasingly used to study chronic ischaemia, therapeutic angiogenesis, hypertrophic cardiomyopathy and abdominal aortic aneurysm as their coronary anatomy and physiology are similar to humans. Type 1 and II diabetes can be induced in swine using dietary regimes and/or administration of streptozotocin. Pigs are a good and extensively used model for specific nutritional studies as their protein and lipid metabolism is comparable with humans, although pigs are not as sensitive to protein restriction as rodents. Neonatal and weanling pigs have been used to examine the pathophysiology and prevention/treatment of microbial-associated diseases and immune system disorders. A porcine model mimicking various degrees of prematurity in infants receiving total parenteral nutrition has been established to investigate gut development, amino acid metabolism and non-alcoholic fatty liver disease. Endoscopic therapeutic methods for upper gastrointestinal tract bleeding are being developed. Bone remodelling cycle in pigs is histologically more similar to humans than that of rats or mice, and is used to examine the relationship between menopause and osteoporosis. Work has also been conducted on dental implants in pigs to consider loading; however with caution as porcine bone remodels slightly faster than human bone. We conclude that pigs are a valuable translational model to bridge the gap between classical rodent models and humans in developing new therapies to aid human health

Vorapaxar in the secondary prevention of atherothrombotic events

Item does not contain fulltextBACKGROUND: Thrombin potently activates platelets through the protease-activated receptor PAR-1. Vorapaxar is a novel antiplatelet agent that selectively inhibits the cellular actions of thrombin through antagonism of PAR-1. METHODS: We randomly assigned 26,449 patients who had a history of myocardial infarction, ischemic stroke, or peripheral arterial disease to receive vorapaxar (2.5 mg daily) or matching placebo and followed them for a median of 30 months. The primary efficacy end point was the composite of death from cardiovascular causes, myocardial infarction, or stroke. After 2 years, the data and safety monitoring board recommended discontinuation of the study treatment in patients with a history of stroke owing to the risk of intracranial hemorrhage. RESULTS: At 3 years, the primary end point had occurred in 1028 patients (9.3%) in the vorapaxar group and in 1176 patients (10.5%) in the placebo group (hazard ratio for the vorapaxar group, 0.87; 95% confidence interval [CI], 0.80 to 0.94; P<0.001). Cardiovascular death, myocardial infarction, stroke, or recurrent ischemia leading to revascularization occurred in 1259 patients (11.2%) in the vorapaxar group and 1417 patients (12.4%) in the placebo group (hazard ratio, 0.88; 95% CI, 0.82 to 0.95; P=0.001). Moderate or severe bleeding occurred in 4.2% of patients who received vorapaxar and 2.5% of those who received placebo (hazard ratio, 1.66; 95% CI, 1.43 to 1.93; P<0.001). There was an increase in the rate of intracranial hemorrhage in the vorapaxar group (1.0%, vs. 0.5% in the placebo group; P<0.001). CONCLUSIONS: Inhibition of PAR-1 with vorapaxar reduced the risk of cardiovascular death or ischemic events in patients with stable atherosclerosis who were receiving standard therapy. However, it increased the risk of moderate or severe bleeding, including intracranial hemorrhage. (Funded by Merck; TRA 2P-TIMI 50 ClinicalTrials.gov number, NCT00526474.)