Pilot Study Comparing Closed Versus Open Tracheal Suctioning in Postoperative Neonates and Infants With Complex Congenital Heart Disease

Objectives: To determine the hemodynamic effect of tracheal suction method in the first 36 hours after high-risk infant heart surgery on the PICU and to compare open and closed suctioning techniques. Design: Pilot randomized crossover study. Setting: Single PICU in United Kingdom. Participants: Infants undergoing surgical palliation with Norwood Sano, modified Blalock-Taussig shunt, or pulmonary artery banding in the first 36 hours postoperatively. Interventions: Infants were randomized to receive open or closed (in-line) tracheal suctioning either for their first or second study tracheal suction in the first 36 hours postoperatively. Measurements and Main Results: Twenty-four infants were enrolled over 18 months, 11 after modified Blalock-Taussig shunt, seven after Norwood Sano, and six after pulmonary artery banding. Thirteen patients received the open suction method first followed by the closed suction method second, and 11 patients received the closed suction method first followed by the open suction method second in the first 36 hours after their surgery. There were statistically significant larger changes in heart rate (p = 0.002), systolic blood pressure (p = 0.022), diastolic blood pressure (p = 0.009), mean blood pressure (p = 0.007), and arterial saturation (p = 0.040) using the open suction method, compared with closed suctioning, although none were clinically significant (defined as requiring any intervention). Conclusions: There were no clinically significant differences between closed and open tracheal suction methods; however, there were statistically significant greater changes in some hemodynamic variables with open tracheal suctioning, suggesting that closed technique may be safer in children with more precarious physiology. (Pediatr Crit Care Med 2017; XX:00–00

Secondary Metabolites of Marine Microbes: From Natural Products Chemistry to Chemical Ecology

Marine natural products (MNPs) exhibit a wide range of pharmaceutically relevant bioactivities, including antibiotic, antiviral, anticancer, or anti-inflammatory properties. Besides marine macroorganisms such as sponges, algae, or corals, specifically marine bacteria and fungi have shown to produce novel secondary metabolites (SMs) with unique and diverse chemical structures that may hold the key for the development of novel drugs or drug leads. Apart from highlighting their potential benefit to humankind, this review is focusing on the manifold functions of SMs in the marine ecosystem. For example, potent MNPs have the ability to exile predators and competing organisms, act as attractants for mating purposes, or serve as dye for the expulsion or attraction of other organisms. A large compilation of literature on the role of MNPs in marine ecology is available, and several reviews evaluated the function of MNPs for the aforementioned topics. Therefore, we focused the second part of this review on the importance of bioactive compounds from crustose coralline algae (CCA) and their role during coral settlement, a topic that has received less attention. It has been shown that certain SMs derived from CCA and their associated bacteria are able to induce attachment and/or metamorphosis of many benthic invertebrate larvae, including globally threatened reef-building scleractinian corals. This review provides an overview on bioactivities of MNPs from marine microbes and their potential use in medicine as well as on the latest findings of the chemical ecology and settlement process of scleractinian corals and other invertebrate larvae

Short-term and latent post-settlement effects associated with elevated temperature and oxidative stress on larvae from the coral Porites astreoides

Coral reefs across the Caribbean are undergoing unprecedented rates of decline in coral cover during the last three decades, and coral recruitment is one potential process that could aid the recovery of coral populations. To better understand the effects of climate change on coral larval ecology, the larvae of Porites astreoides were studied to determine the immediate and post-settlement effects of elevated temperature and associated oxidative stress. Larvae of Porites astreoides were exposed to 27 °C (ambient) and +3. 0 °C (elevated temperature) seawater for a short duration of 24 h; then, a suite of physiological parameters were measured to determine the extent of sublethal stress. Following the +3. 0 °C treatment, larvae did not show a significant difference in maximum quantum yield of PSII (Fv/Fm) or respiratory demand when compared to controls maintained at 27 °C. The addition of micromolar concentrations of hydrogen peroxide did not impact respiration or photochemical efficiency. Catalase activity in the larvae increased (\u3e60 %) following exposure to elevated temperature when compared to the controls. Short-term larval survival and settlement and metamorphosis were not affected by increased temperature or the H2O2 treatment. However, the settled spat that were exposed to elevated temperature underwent a 99 % reduction in survival compared to 90 % reduction for the control spat when examined 24 days following the deployment of 4-day-old settled spat on settlement tiles in the field. These results show that short-term exposure to some stressors might have small impacts on coral physiology, and no effects on larval survival, settlement and metamorphosis. However, due to post-settlement mortality, these stressors can cause a significant reduction in coral recruitment. © 2012 Springer-Verlag Berlin Heidelberg

Interspecific variation in coral settlement and fertilization success in response to hydrogen peroxide exposure

Hydrogen peroxide (H2O2) is involved in the regulation of numerous reproductive and morphogenic processes across an array of taxa. Extracellular H2O2 can be widespread in oceanicwaters, and elevated sea surface temperatures can cause increased levels of intracellular H2O2 within cnidarian tissue, but it remains unclear how this compound affects early life-history processes in corals, such as fertilization,metamorphosis, and settlement. To evaluate the effects of H2O2 on multiple stages of recruitment, experiments were conducted using Caribbean corals with various reproductive modes, including the brooders Porites astreoides and Favia fragum and the broadcast-spawning species Acropora palmata and Orbicella franksi. H2O2 accelerated settlement in all brooding species tested. Concentrations of 1000 µmol 1−1 H2O2 caused close to 100%settlement in all larval age classes, regardless of exposure duration. As larvae aged, the required threshold of H2O2 capable of inducing settlement decreased. In contrast, H2O2 concentrations of 100 µmol l21 or greater caused a significant reduction in metamorphosis and settlement in the larvae of spawners. Furthermore, fertilization of their gametes was inhibited in the presence of H2O2 concentrations as low as 100 µmol 1−1. In Porites astreoides larvae, internal levels of H2O2 reached a maximal value of 75 µmol 1−1 following 48 h of incubation at 31 ℃. This concentration was found to significantly alter settlement rates in both brooding coral species and likely induced a cellular cascade in the settlement signaling pathway. The results of this study suggest that temperature stress influences H2O2 production, which in turn impacts coral settlement. While it is unlikely that the current levels of externally derived concentrations of oceanic H2O2 are affecting coral larvae, internal concentrations (produced under heat stress) have the capacity to impact recruitment under a changing climate

Detecting hyperthermal stress in larvae of the hermatypic coral Porites astreoides: The suitability of using biomarkers of oxidative stress versus heat-shock protein transcriptional expression

Scleractinian coral populations are declining worldwide in response to a variety of factors including increases in sea surface temperatures. To evaluate the effects of predicted elevated seawater temperatures on coral recruitment, larvae from the coral Porites astreoides were exposed to seawater at ambient (27.3 °C) or elevated temperature (30.8 °C) conditions for 4, 24, or 48 h. Following exposure, larvae were tested for survival and settlement, oxidative stress, respiratory demand, and mRNA expression of heat-shock proteins (Hsps) 16 and 60. While elevated temperature had no effect on larval survival, settlement, or expression of Hsps, it did cause a significant increase in larval respiration, oxidative damage (lipid peroxidation), and antioxidant enzyme activity (catalase). The absence of a significant up-regulation of Hsp 16 or 60 expression in response to thermal stress suggests that the transcriptional expression of these genes is a less sensitive diagnostic tool compared to biomarkers of oxidative stress at the temperatures examined. The results of this study provide evidence that enhanced levels of oxidative stress are encountered in zooxanthellae-containing coral larvae in response to elevated temperatures and that this occurrence should be strongly considered for use as a biomarker when monitoring sub-lethal cellular responses to rising sea surface temperatures. © 2013 Springer-Verlag Berlin Heidelberg

Algal chemical ecology in a changing ocean

Macroalgae and benthic cyanobacteria are becoming increasingly abundant on reefs, and many of these dominant algae produce diverse secondary metabolites. Abundant brown and green macroalgae and nuisance blooms of cyanobacteria occur regularly throughout Florida and on the Belizean barrier reef. Crude extracts and compounds from some macroalgae and cyanobacteria deter feeding by natural assemblages of fishes and the sea urchin Diadema antillarum . In addition, macroalgal and cyanobacterial secondary metabolites may serve multiple ecological functions, including inhibition of microorganisms and competition for space. The role of allelopathy (chemical inhibition) in mediating the interactions between chemically rich species of algae and cyanobacteria and different life history stages of corals was tested. Extracts and isolated compounds from Dictyota spp., Lyngbya spp. and other cyanobacteria negatively influenced the settlement and metamorphosis of coral larvae. On reefs experiencing increased abundance of chemically defended macroalgae and benthic cyanobacteria, the restocking of adult coral populations may be slowed due to recruitment inhibition caused by algal secondary metabolites. These compounds protect some algae from herbivory (allowing increased space occupation) and reduce coral recruitment, both of which may perpetuate a “phase shift” from coral to algal dominated communities. Increases in atmospheric carbon dioxide concentrations are reducing ocean pH and the calcification rates of marine organisms. Changes in CO 2 concentrations may also cause sub-lethal stress and changes in concentrations of secondary metabolites that protect macroalgae from herbivores. We exposed two chemically-rich algae, the calcareous, terpene-producing macroalga Halimeda opuntia and the benthic marine cyanobacterium Lyngbya cf. confervoides , to seawater conditioned with increasing levels of CO 2 to test for effects of ocean acidification on growth, calcification, and secondary metabolite concentrations. Although terpene concentrations were not affected in H. opuntia , calcification decreased at CO 2 concentrations of 2200 ppm and above, which could increase its susceptibility to herbivory. We found no effect on growth rates over the range of CO 2 concentrations and temperatures tested for Lyngbya cf. confervoides . Halimeda opuntia and benthic cyanobacteria are conspicuous community members on coral reefs and in seagrass beds in tropical seas around the world, and the observed tolerance of these algae to ocean acidification suggests that they will continue to be abundant in a changing ocean

Responses of the tropical gorgonian coral Eunicea fusca to ocean acidification conditions

Ocean acidification can have negative repercussions from the organism to ecosystem levels. Octocorals deposit high-magnesium calcite in their skeletons, and according to different models, they could be more susceptible to the depletion of carbonate ions than either calcite or aragonite-depositing organisms. This study investigated the response of the gorgonian coral Eunicea fusca to a range of CO2 concentrations from 285 to 4,568 ppm (pH range 8.1-7.1) over a 4-week period. Gorgonian growth and calcification were measured at each level of CO2 as linear extension rate and percent change in buoyant weight and calcein incorporation in individual sclerites, respectively. There was a significant negative relationship for calcification and CO2 concentration that was well explained by a linear model regression analysis for both buoyant weight and calcein staining. In general, growth and calcification did not stop in any of the concentrations of pCO2; however, some of the octocoral fragments experienced negative calcification at undersaturated levels of calcium carbonate (>4,500 ppm) suggesting possible dissolution effects. These results highlight the susceptibility of the gorgonian coral E. fusca to elevated levels of carbon dioxide but suggest that E. fusca could still survive well in mid-term ocean acidification conditions expected by the end of this century, which provides important information on the effects of ocean acidification on the dynamics of coral reef communities. Gorgonian corals can be expected to diversify and thrive in the Atlantic-Eastern Pacific; as scleractinian corals decline, it is likely to expect a shift in these reef communities from scleractinian coral dominated to octocoral/soft coral dominated under a "business as usual" scenario of CO2 emissions

Root biomass of carbon plantings in agricultural landscapes of southern Australia: Development and testing of allometrics

Root biomass may to contribute a substantial proportion of the carbon sequestered in new tree plantings, particularly in regions where rainfall and/or site quality is relatively low as this may result in relatively high allocation of plant biomass below-ground to source required water or nutrients. However, root biomass is often overlooked because of difficulty with measurement. In Australia, most carbon plantings are currently mixed-species environmental or mallee eucalypt plantings on agricultural land in regions with rainfall of 250-850mmyear-1. Here, we collated new and existing root biomass data from ca. 900 individual trees or shrubs to develop and test allometric equations for predicting root biomass based on stem diameter (of unharvested trees or shrubs) or height (of coppice harvested trees) in these plantings. Equations developed showed significant differences between groupings of species with differing growth habits or from different genera. Grouping species into categories of: (i) non-eucalypts, (ii) tree-form eucalypts, (iii) unharvested mallee eucalypts, and (iv) coppiced mallee eucalypts, provided equations with model efficiencies of 0.64-0.90. In the process of collating data across different studies, corrections were required for data consistency. Uncertainty analysis showed that although these corrections resulted in some uncertainty in the equations developed, measurement errors, particularly of stem diameter, were also important contributors to this uncertainty. We tested equations developed using data from 11 environmental and mallee planting sites where direct measurements of root biomass were made through whole-plot excavation. Site-level predictions of root biomass from individual tree allometry were effective, with an efficiency of prediction of 0.98. These results indicate that the generic allometric equations developed can be confidently applied across the Australian agricultural region with 250-850mmyear-1 rainfall to obtain accurate regional estimates of root biomass in the currently relatively young (<20year old) environmental and mallee plantings

Development and testing of allometric equations for estimating above-ground biomass of mixed-species environmental plantings

To quantify the impact that planting indigenous trees and shrubs in mixed communities (environmental plantings) have on net sequestration of carbon and other environmental or commercial benefits, precise and non-biased estimates of biomass are required. Because these plantings consist of several species, estimation of their biomass through allometric relationships is a challenging task. We explored methods to accurately estimate biomass through harvesting 3139 trees and shrubs from 22 plantings, and collating similar datasets from earlier studies, in non-arid (&gt;300mm rainfallyear-1) regions of southern and eastern Australia. Site-and-species specific allometric equations were developed, as were three types of generalised, multi-site, allometric equations based on categories of species and growth-habits: (i) species-specific, (ii) genus and growth-habit, and (iii) universal growth-habit irrespective of genus. Biomass was measured at plot level at eight contrasting sites to test the accuracy of prediction of tonnes dry matter of above-ground biomass per hectare using different classes of allometric equations. A finer-scale analysis tested performance of these at an individual-tree level across a wider range of sites. Although the percentage error in prediction could be high at a given site (up to 45%), it was relatively low (&lt;11%) when generalised allometry-predictions of biomass was used to make regional- or estate-level estimates across a range of sites. Precision, and thus accuracy, increased slightly with the level of specificity of allometry. Inclusion of site-specific factors in generic equations increased efficiency of prediction of above-ground biomass by as much as 8%. Site-and-species-specific equations are the most accurate for site-based predictions. Generic allometric equations developed here, particularly the generic species-specific equations, can be confidently applied to provide regional- or estate-level estimates of above-ground biomass and carbon. © 2013 Elsevier B.V

Development and testing of allometric equations for estimating above-ground biomass of mixed-species environmental plantings

To quantify the impact that planting indigenous trees and shrubs in mixed communities (environmental plantings) have on net sequestration of carbon and other environmental or commercial benefits, precise and non-biased estimates of biomass are required. Because these plantings consist of several species, estimation of their biomass through allometric relationships is a challenging task. We explored methods to accurately estimate biomass through harvesting 3139 trees and shrubs from 22 plantings, and collating similar datasets from earlier studies, in non-arid (&gt;300mm rainfallyear-1) regions of southern and eastern Australia. Site-and-species specific allometric equations were developed, as were three types of generalised, multi-site, allometric equations based on categories of species and growth-habits: (i) species-specific, (ii) genus and growth-habit, and (iii) universal growth-habit irrespective of genus. Biomass was measured at plot level at eight contrasting sites to test the accuracy of prediction of tonnes dry matter of above-ground biomass per hectare using different classes of allometric equations. A finer-scale analysis tested performance of these at an individual-tree level across a wider range of sites. Although the percentage error in prediction could be high at a given site (up to 45%), it was relatively low (&lt;11%) when generalised allometry-predictions of biomass was used to make regional- or estate-level estimates across a range of sites. Precision, and thus accuracy, increased slightly with the level of specificity of allometry. Inclusion of site-specific factors in generic equations increased efficiency of prediction of above-ground biomass by as much as 8%. Site-and-species-specific equations are the most accurate for site-based predictions. Generic allometric equations developed here, particularly the generic species-specific equations, can be confidently applied to provide regional- or estate-level estimates of above-ground biomass and carbon. © 2013 Elsevier B.V