Large-Scale Patterns of Turnover and Basal Area Change in Andean Forests

General patterns of forest dynamics and productivity in the Andes Mountains are poorly characterized. Here we present the first large-scale study of Andean forest dynamics using a set of 63 permanent forest plots assembled over the past two decades. In the North-Central Andes tree turnover (mortality and recruitment) and tree growth declined with increasing elevation and decreasing temperature. In addition, basal area increased in Lower Montane Moist Forests but did not change in Higher Montane Humid Forests. However, at higher elevations the lack of net basal area change and excess of mortality over recruitment suggests negative environmental impacts. In North-Western Argentina, forest dynamics appear to be influenced by land use history in addition to environmental variation. Taken together, our results indicate that combinations of abiotic and biotic factors that vary across elevation gradients are important determinants of tree turnover and productivity in the Andes. More extensive and longer-term monitoring and analyses of forest dynamics in permanent plots will be necessary to understand how demographic processes and woody biomass are responding to changing environmental conditions along elevation gradients through this century.     

Age of spent Octopus vulgaris and stress mark analysis using beaks of wild individuals

Age estimation of the cephalopod Octopus vulgaris by using beaks has improved in recent years, but maximum age and longevity in the wild have not been confirmed due to the low availability of senescent wild octopuses. In this study, a beak analysis of lateral wall surfaces (LWS) from 20 spent specimens confirmed the 1-year lifecycle of the species in Central East Atlantic waters. Stress marks (checks) were clearly located in the daily increment sequence of rostrum sagittal sections (RSS). The highest daily variations in sea surface temperature (ΔT) that occurred during the last months of their lifetimes coincided with the locations of the marks on the beak, enabling confirmation of O. vulgaris beaks as life recorders for the first time. It also supports the daily deposition of RSS beak increments in the wild. Individuals were grouped into two main zones, at 20ºN and 18ºN, respectively. Both groups showed different thermal check patterns, in accordance with the oceanographic differences. Two other checks (not coinciding with high values of ΔT) were observed in RSS at averages of 15 and 28 days before death, respectively, which were interpreted as responding to senescent-related events.     

A brief review

This article serves as a brief history and review of EBM—how EBM developed, its strengths and limitations, and the need for constant improvements. Hopefully, this review will have enhanced your understanding of EBM and its importance and stimulated you to apply EBM to your own practice. As more data and therapies become available, and as clinical guidelines continue to evolve based on EBM, we should expect patient outcomes to improve.     

Hospital hypoglycemia: From observation to action

Background: A preponderance of evidence indicates that when treatment of hyperglycemia with insulin is provided for certain hospitalized populations, the attainment of appropriate glycemic targets improves nonglycemic outcomes such as mortality rates, morbidities (eg, wound infection, critical illness polyneuropathy, bacteremia, new renal insufficiency), duration of ventilator dependency, transfusion requirements, and length of hospital stay. Nevertheless, randomized controlled trials (RCTs) of intensive insulin therapy and studies of outcomes before and after implementation of tight glycemic control have consistently recognized an increased incidence of hypoglycemia as a complication associated with the use of lower glycemic targets and higher doses of insulin.Objectives: This commentary compares the quality of the available evidence on the clinical impact of iatrogenic hypoglycemia. We present treatment strategies designed to prevent iatrogenic hypoglycemia in the hospital setting.Methods: The PubMed database and online citations of articles tracked subsequent to publication were searched for articles on the epidemiology, clinical impact, and mechanism of harm of hypoglycemia published since 1986. In addition, we searched the literature for RCTs conducted since 2001 concerning intensive insulin therapy in the hospital critical care setting, including meta-analyses; letters to the editor were excluded. The retrieved studies were scanned and chosen selectively for full-text review based on the study size and design, novelty of findings, and evidence related to the possible clinical impact of hypoglycemia. Reference lists from the retrieved studies were searched for additional studies. Reports were summarized for the purpose of comparing and contrasting the qualitative nature of information about iatrogenic hypoglycemia in the hospital.Results: Eight RCTs of intensive glycemic management, 16 observational studies of hospitalized patients with hypoglycemia (including studies of outcomes before and after implementation of tight glycemic control), and 4 case reports on patients with hypoglycemia were selected for discussion of the incidence of hypoglycemia, significance of hypoglycemia as a marker or cause of poor prognosis, and clinical harm of hypoglycemia. Hypoglycemia was identified in clinical trials as either a category of adverse events or a complication of intensified insulin treatment. For example, a recent meta-analysis found that the incidence of severe hypoglycemia was higher among critically ill patients treated with intensive insulin therapy than among control patients, with a pooled relative risk of 6.0 (95% CI, 4.5–8.0). In the largest multisite RCT on glycemic control among patients in intensive care units (ICUs) conducted to date, deaths were reported for 27.5% (829/3010 patients) in the intensive-treatment group and 24.9% (751/3012 patients) in the conventional-treatment group (odds ratio, 1.14; 95% CI, 1.02–1.28; P = 0.02). In another multisite ICU study, although the intensive and control groups had similar mortality rates, the mortality rate was higher among hypoglycemic participants than among nonhypoglycemic participants (32.2% vs 13.6%, respectively; P < 0.01). Pooled data from 2 singlesite studies in medical and surgical ICUs revealed an increased risk of hypoglycemia in the intensive-treatment group compared with the conventional-treatment group (11.3% [154/1360] and 1.8% [25/1388], respectively; P < 0.001), but the hospital mortality rate was similar for the 2 groups (50.6% [78/154] and 52.0% [13/25], respectively). Specific sequelae of hypoglycemia affecting individual patients were described in the RCTs as well as in the observational studies. New guidelines for glycemic control have recently been issued, but results of the studies using the new targets are not yet available. We propose treatment strategies designed to prevent iatrogenic hypoglycemia in the hospital setting.Conclusions: In response to the growing evidence on the risk of hypoglycemia during intensified glycemic management of hospitalized patients, professional organizations recently revised targets for glycemic control. It is appropriate for institutions to reevaluate hospital protocols for glycemic management with intravenous insulin and, on general wards, to implement standardized order sets for use of subcutaneous insulin to achieve beneficial targets using safe strategies.     

Inhibition of fatty acid biosynthesis prevents adipocyte lipotoxicity on human osteoblasts in vitro

Although increased bone marrow fat in age‐related bone loss has been associated with lower trabecular mass, the underlying mechanism responsible remains unknown. We hypothesized that marrow adipocytes exert a lipotoxic effect on osteoblast function and survival through the reversible biosynthesis of fatty acids (FA) into the bone marrow microenvironment. We have used a two‐chamber system to co‐culture normal human osteoblasts (NHOst) with differentiating pre‐adipocytes in the absence or presence of an inhibitor of FA synthase (cerulenin) and separated by an insert that allowed unidirectional trafficking of soluble factors only and prevented direct cell–cell contact. Supernatants were assayed for the presence of FA using mass spectophotometry. After 3 weeks in co‐culture, NHOst showed significantly lower levels of differentiation and function based on lower mineralization and expression of alkaline phosphatase, osterix, osteocalcin and Runx2. In addition, NHOst survival was affected by the presence of adipocytes as determined by MTS‐formazan and TUNEL assays as well as higher activation of caspases 3/7. These toxic effects were inhibited by addition of cerulenin. Furthermore, culture of NHOst with either adipocyte‐conditioned media alone in the absence of adipocytes themselves or with the addition of the most predominant FA (stearate or palmitate) produced similar toxic results. Finally, Runx2 nuclear binding was affected by addition of either adipocyte conditioned media or FA into the osteogenic media. We conclude that the presence of FA within the marrow milieu can contribute to the age‐related changes in bone mass and can be prevented by the inhibition of FA synthase.     

A population genetics study of Anopheles darlingi (Diptera: Culicidae) from Colombia based on random amplified polymorphic DNA-polymerase chain reaction and amplified fragment lenght polymorphism markers

The genetic variation and population structure of three populations of Anopheles darlingi from Colombia were studied using random amplified polymorphic markers (RAPDs) and amplified fragment length polymorphism markers (AFLPs). Six RAPD primers produced 46 polymorphic fragments, while two AFLP primer combinations produced 197 polymorphic fragments from 71 DNA samples. Both of the evaluated genetic markers showed the presence of gene flow, suggesting that Colombian An. darlingi populations are in panmixia. Average genetic diversity, estimated from observed heterozygosity, was 0.374 (RAPD) and 0.309 (AFLP). RAPD and AFLP markers showed little evidence of geographic separation between eastern and western populations; however, the F ST values showed high gene flow between the two western populations (RAPD: F ST = 0.029; Nm: 8.5; AFLP: F ST = 0.051; Nm: 4.7). According to molecular variance analysis (AMOVA), the genetic distance between populations was significant (RAPD:phiST = 0.084; AFLP:phiST = 0.229, P < 0.001). The F ST distances and AMOVAs using AFLP loci support the differentiation of the Guyana biogeographic province population from those of the Chocó-Magdalena. In this last region, Chocó and Córdoba populations showed the highest genetic flow.     

Effects of human versus mouse leukemia inhibitory factor on the in vitro development of bovine embryos

Leukemia inhibitory factor (LIF) is a cytokine that shows conflicting effects on in vitro produced (IVP) bovine embryos. Bovine LIF (bLIF) has been cloned and used in culture, but there is no commercially available bLIF. Thus, researchers use human LIF (hLIF) to supplement the culture medium for bovine embryos because of its greater sequence homology compared to murine LIF (mLIF). We compared the effects of mLIF and hLIF on the development of bovine embryos in culture with the effects described for bLIF. Oocytes were matured and fertilized in vitro and cultured in modified synthetic oviduct fluid with BSA. On Day 6 post-insemination, morulae were cultured for 48h in the presence of: (1) mLIF, 100ngml(-1); (2) hLIF, 100ngml(-1); or (3) no LIF. Reduced blastocyst rates were observed on Day 8 for hLIF at the middle and expanded stages, while mLIF had no effect. In contrast, Day 8 blastocysts showed decreased cell counts both in terms of inner cell mass (ICM) and ICM/total cell proportions in the presence of mLIF, while hLIF had no effect. No changes were seen in trophectoderm (TE) and total cell counts. The increased hatching rates and TE cell counts previously described for bLIF, together with the disparate effects exhibited by hLIF and mLIF during blastocyst formation indicate these compounds are inappropriate to replace bLIF. We recommend that heterospecific LIF should not be used to supplement the culture medium for bovine embryo or embryonic stem cells.     

Adsorption of fluorobenzene onto granular activated carbon: isotherm and bioavailability studies

The adsorption of a recalcitrant fluoroaromatic compound, fluorobenzene (FB), onto granular activated carbon (GAC) was evaluated. The respective isotherm was obtained and the Langmuir, Freundlich and Redlich-Peterson models were fitted to the experimental data, with the Redlich-Peterson model giving the best fitting. Freundlich model also provided a good fit but the Langmuir model could not adequately fit the experimental data, especially at high FB concentrations. Maximal adsorption capacity of FB onto GAC was found to be 388mg of FB per gram of GAC. The reversibility of the adsorption of FB onto GAC was investigated, both in the absence and presence of microorganisms. Abiotic desorption of FB occurred to a small extent (between 3% and 22%, for amounts of FB initially adsorbed to the GAC between 37 and 388mgg(-1)), and bioregeneration of GAC was shown to occur when the matrix was exposed to a FB degrading culture, with 58-80% of the adsorbed FB being biodegraded. A residual amount of FB showed not to be bioavailable, suggesting that part of the adsorbed FB may be irreversibly bound. The fraction of the non-bioavailable FB increased at higher amounts of adsorbed FB, from 19% to 33%. The results indicate that the GAC employed in this study has a good capacity to adsorb FB and that bioregeneration of this matrix is a feasible process.