The HIV-Brazil Cohort Study: Design,Methods and Participant Characteristics

Background

The HIV-Brazil Cohort Study was established to analyze the effectiveness of combination antiretroviral therapy (cART) and the impact of this treatment on morbidity, quality of life (QOL) and mortality. The study design, patients’ profiles and characteristics of cART initiation between 2003 and 2010 were described.

Methodology/Principal Findings

Since 2003, the HIV-Brazil Cohort has been following HIV-infected adults receiving cART at 26 public health care facilities, using routine clinical care data and self-reported QOL questionnaires. When not otherwise available, data are obtained from national information systems. The main outcomes of interest are diseases related or unrelated to HIV; suppression of viral replication; adverse events; virological, clinical and immunological failures; changes in the cART; and mortality. For the 5,061 patients who started cART between 2003 and 2010, the median follow-up time was 4.1 years (IQR 2.2–5.9 years) with an 83.4% retention rate. Patient profiles were characterized by a predominance of men (male/female ratio 1.7∶1), with a mean age of 36.9 years (SD 9.9 years); 55.2% had been infected with HIV via heterosexual contact. The majority of patients (53.4%) initiated cART with a CD4⁺ T-cell count ≤200 cells/mm³. The medications most often used in the various treatment regimens were efavirenz (59.7%) and lopinavir/ritonavir (18.2%). The proportion of individuals achieving viral suppression within the first 12 months of cART use was 77.4% (95% CI 76.1–78.6). Nearly half (45.4%) of the patients presented HIV-related clinical manifestations after starting cART, and the AIDS mortality rate was 13.9 per 1,000 person-years.

Conclusions/Significance

Results from cART use in the daily practice of health services remain relatively unknown in low- and middle-income countries, and studies with the characteristics of the HIV-Brazil Cohort contribute to minimizing these shortcomings, given its scope and patient profile, which is similar to that of the AIDS epidemic in the country.     

Predation risk shapes thermal physiology of a predaceous damselfly

Predation risk has strong effects on organismal physiology that can cascade to impact ecosystem structure and function. Physiological processes in general are sensitive to temperature. Thus, the temperature at which predators and prey interact may shape physiological response to predation risk. We measured and evaluated how temperature and predation risk affected growth rates of predaceous damselfly nymphs (Enallagma vesperum, Odonata: Coenagrionidae). First, we conducted growth trials at five temperatures crossed with two levels of predation risk (fish predator present versus absent) and measured growth rates, consumption rates, assimilation efficiencies, and production efficiencies of 107 individual damselflies. Second, we used a model to evaluate if and how component physiological responses to predation risk affected growth rates across temperatures. In the absence of mortality threat, growth rates of damselflies increased with warming until about 23.5 °C and then began to decline, a typical unimodal response to changes in temperature. Under predation risk, growth rates were lower and the shape of the thermal response was less apparent. Higher metabolic and survival costs induced by predation risk were only partially offset by changes in consumption rates and assimilation efficiencies and the magnitude of non-consumptive effects varied as a function of temperature. Furthermore, we documented that thermal physiology was mediated by predation risk, a known driver of organismal physiology that occurs in the context of species interactions. A general understanding of climatic impacts on ectothermic populations requires consideration of the community context of thermal physiology, including non-consumptive effects of predators.     

Impact of climatic variation on populations of pine processionary moth Thaumetopoea pityocampa in a core area of its distribution

• 1 There is growing appreciation of climatic effects on insect population dynamics at the margins of distribution limits. Climatic effects might be less important and/or involve different drivers and processes near the centre of distributions.
• 2 We evaluated the effects of interannual variation in temperatures, radiation and precipitation on populations of pine processionary moth Thaumetopoea pityocampa in Central–South Portugal, a low altitude area with a relatively mild Mediterranean climate near the centre of the north–south range of the species.
• 3 We tested for effects of climate on mortality of young larvae, growth rates, final larval mass and fecundity.
• 4 Results indicated high mortality of early instars associated with low minimum and maximum daily temperatures and low precipitation. Low minimum temperatures were further associated with high parasitism by the larval parasitoid Phryxe caudata (Rondani) (Diptera, Tachinidae). Furthermore, larval growth rates were higher with high solar radiation during December and January, which was itself negatively related to precipitation and air temperature. Slow larval growth rates led to lower final mass at pupation in the spring, and smaller egg masses and smaller initial colony sizes during the next autumn.
• 5 Thus climatic factors, and temperature in particular, apparently contributed to population dynamics of T. pityocampa in the core of its distribution, as well as at its northern limits. The most specific climatic parameters of importance, however, and the connections between climate, physiology and insect demographics in the core area were clearly different from northern areas.

     

A decision support tool for the management of freshwater pest fish incursions in Australia

There are no national emergency response arrangements for freshwater pest fish incursions in Australia. Individual States and Territories vary widely in their current response arrangements to freshwater pest fish incursions, with many being dealt with on an ad‐hoc basis and with varying degrees of efficacy. In recognition of this, the Invasive Animals Cooperative Research Centre funded a project to ‘Advance the development of national emergency response arrangements for freshwater fish incursions in Australia’. One of the recommendations of this project was creating a web‐based support tool (DST) to provide direction and assistance in managing freshwater pest fish incursions. This article describes the DST created. The DST leads the user through a series of questions relating to the species sighting, details of the fish and its capture, and site information at a particular location. These questions address issues that managers must consider when choosing appropriate control techniques. Information entered in two sections (site details and fish details) influence the suggested control techniques. The final product of the DST is a standard online report that contains a summary of all information entered and a ranking of the most common control techniques used in Australia. The report is then submitted to and assessed by the relevant State Government authority responsible for the management of freshwater pest fish incursions. Managers are then able to consider their options, taking into consideration current permits, resources and capability. The DST is anticipated to maximize the speed and quality of freshwater pest fish incursion reporting and to help the responsible government agency decide on the most appropriate management action. The DST will also provide government agency staff access to other relevant information and facilitate consistency in the decision‐making approach by government agencies throughout Australia.     

Traceable Calibration,Performance Metrics,and Uncertainty Estimates of Minirhizotron Digital Imagery for Fine-Root Measurements

Even though fine-root turnover is a highly studied topic, it is often poorly understood as a result of uncertainties inherent in its sampling, e.g., quantifying spatial and temporal variability. While many methods exist to quantify fine-root turnover, use of minirhizotrons has increased over the last two decades, making sensor errors another source of uncertainty. Currently, no standardized methodology exists to test and compare minirhizotron camera capability, imagery, and performance. This paper presents a reproducible, laboratory-based method by which minirhizotron cameras can be tested and validated in a traceable manner. The performance of camera characteristics was identified and test criteria were developed: we quantified the precision of camera location for successive images, estimated the trueness and precision of each camera''s ability to quantify root diameter and root color, and also assessed the influence of heat dissipation introduced by the minirhizotron cameras and electrical components. We report detailed and defensible metrology analyses that examine the performance of two commercially available minirhizotron cameras. These cameras performed differently with regard to the various test criteria and uncertainty analyses. We recommend a defensible metrology approach to quantify the performance of minirhizotron camera characteristics and determine sensor-related measurement uncertainties prior to field use. This approach is also extensible to other digital imagery technologies. In turn, these approaches facilitate a greater understanding of measurement uncertainties (signal-to-noise ratio) inherent in the camera performance and allow such uncertainties to be quantified and mitigated so that estimates of fine-root turnover can be more confidently quantified.     

The distribution and abundance of animal populations in a climate of uncertainty

Current predictions regarding the ecological consequences of climate change on animal populations are generally autecological and species-specific, and/or non-mechanistic extrapolations of recent short-term patterns. To better understand and predict the effects of climate change on the distribution of species and the abundance of populations we offer a novel, broad theoretical framework. Climate-induced changes in trophic structure may actually be more predictable than effects on individual species. The logic is that there are general differences in climatic sensitivity among trophic levels – specifically, that as one moves up trophic levels, there is an increase in the temperature sensitivity of vital rates. More precisely, we provide: (1) a formal mathematical definition of distribution limits that is both operational and conceptual, introducing the concept DL₅₀, defined as the geographic and climatic isoline representing an equilibrium occupancy of half of the suitable habitats; (2) a matrix of the possible changes in trophic structure from climate change and the general theoretical consequences; and (3) a new idea that predicts broad effects of climatic warming on trophic systems. Our intention is to help meet the challenge of developing and testing general theoretical models that can predict which species will be winners and losers in ecological time, which evolutionary traits will be favoured or selected against, and what will be consequences for ecosystem structure and function.