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BackgroundPre-clinical studies indicate that dry-cold-carbon-dioxide (DC-CO2) insufflation leads to more peritoneal damage, inflammation and hypothermia compared with humidified-warm-CO2 (HW-CO2). Peritoneum and core temperature in patients undergoing colorectal cancer (CRC) surgery were compared.MethodsSixty-six patients were randomized into laparoscopic groups; those insufflated with DC-CO2 or HW-CO2. A separate group of nineteen patients undergoing laparotomy were randomised to conventional surgery or with the insertion of a device delivering HW-CO2. Temperatures were monitored and peritoneal biopsies and bloods were taken at the start of surgery, at 1 and 3 h. Further bloods were taken depending upon hospital length-of-stay (LOS). Peritoneal samples were subjected to scanning electron microscopy to evaluate mesothelial damage.ResultsLaparoscopic cases experienced a temperature drop despite Bair-HuggerTM use. HW-CO2 restored normothermia (≥ 36.5 °C) by 3 h, DC-CO2 did not. LOS was shorter for colon compared with rectal cancer cases and if insufflated with HW-CO2 compared with DC-CO2; 5.0 vs 7.2 days, colon and 11.6 vs 15.4 days rectum, respectively. Unexpectedly, one third of patients had pre-existing damage. Damage increased at 1 and 3 h to a greater extent in the DC-CO2 compared with the HW-CO2 laparoscopic cohort. C-reactive protein levels were higher in open than laparoscopic cases and lower in both matched HW-CO2 groups.ConclusionsThis prospective RCT is in accord with animal studies while highlighting pre-existing damage in some patients. Peritoneal mesothelium protection, reduced inflammation and restoration of core-body temperature data suggest benefit with the use of HW-CO2 in patients undergoing CRC surgery.

Abstract Background Anxiety disorders are highly prevalent and socio-economically costly. Novel pharmacological treatments for these disorders are needed because many patients do not respond to current agents or experience unwanted side effects. However, a barrier to treatment development is the variable and large placebo response rate seen in trials of novel anxiolytics. Despite this, the mechanisms that drive placebo responses in anxiety disorders have been little investigated, possibly due to low availability of convenient experimental paradigms. We aimed to develop and test a novel protocol for inducing placebo anxiolysis in the 7.5% CO2 inhalational model of generalized anxiety in healthy volunteers. Methods Following a baseline 20-minute CO2 challenge, 32 healthy volunteers were administered a placebo intranasal spray labelled as either the anxiolytic “lorazepam” or “saline.” Following this, participants surreptitiously underwent a 20-minute inhalation of normal air. Post-conditioning, a second dose of the placebo was administered, after which participants completed another CO2 challenge. Results Participants administered sham “lorazepam” reported significant positive expectations of reduced anxiety (P = .001), but there was no group-level placebo effect on anxiety following CO2 challenge post-conditioning (Ps > .350). Surprisingly, we found many participants exhibited unexpected worsening of anxiety, despite positive expectations. Conclusions Contrary to our hypothesis, our novel paradigm did not induce a placebo response, on average. It is possible that effects of 7.5% CO2 inhalation on prefrontal cortex function or behavior in line with a Bayesian predictive coding framework attenuated the effect of expectations on subsequent placebo response. Future studies are needed to explore these possibilities.

Background Anopheles gambiae , the major malaria mosquito in sub-Saharan Africa, feed largely indoors at night. Raising a house off the ground with no barriers underneath reduces mosquito-house entry. This experiment tested whether walling off the space under an elevated hut affects mosquito-hut entry. Methods Four inhabited experimental huts, each of which could be moved up and down, were used in rural Gambia. Nightly collections of mosquitoes were made using light traps and temperature and carbon dioxide levels monitored indoors and outdoors using loggers. Each night, a reference hut was kept at ground level and three huts raised 2 m above the ground; with the space under the hut left open, walled with air-permeable walls or solid walls. Treatments were rotated every four nights using a randomized block design. The experiment was conducted for 32 nights. Primary measurements were mosquito numbers and indoor temperature in each hut. Results A total of 1,259 female Anopheles gambiae sensu lato were collected in the hut at ground level, 655 in the hut with an open ground floor, 981 in the hut with air-permeable walls underneath and 873 in the hut with solid walls underneath. Multivariate analysis, adjusting for confounders, showed that a raised hut open underneath had 53% fewer mosquitoes (95% CI 47–58%), those with air-permeable walls underneath 24% fewer (95% CI 9–36%) and huts with solid walls underneath 31% fewer (95% CI 24–37%) compared with a hut on the ground. Similar results were found for Mansonia spp. and total number of female mosquitoes, but not for Culex mosquitoes where hut entry was unaffected by height or barriers. Indoor temperature and carbon dioxide levels were similar in all huts. Conclusion Raising a house 2 m from the ground reduces the entry of An. gambiae and Mansonia mosquitoes, but not Culex species. The protective effect of height is reduced if the space underneath the hut is walled off.

The productivity of rainforests growing on highly weathered tropical soils is expected to be limited by phosphorus availability 1 . Yet, controlled fertilization experiments have been unable to demonstrate a dominant role for phosphorus in controlling tropical forest net primary productivity. Recent syntheses have demonstrated that responses to nitrogen addition are as large as to phosphorus 2 , and adaptations to low phosphorus availability appear to enable net primary productivity to be maintained across major soil phosphorus gradients 3 . Thus, the extent to which phosphorus availability limits tropical forest productivity is highly uncertain. The majority of the Amazonia, however, is characterized by soils that are more depleted in phosphorus than those in which most tropical fertilization experiments have taken place 2 . Thus, we established a phosphorus, nitrogen and base cation addition experiment in an old growth Amazon rainforest, with a low soil phosphorus content that is representative of approximately 60% of the Amazon basin. Here we show that net primary productivity increased exclusively with phosphorus addition. After 2 years, strong responses were observed in fine root (+29%) and canopy productivity (+19%), but not stem growth. The direct evidence of phosphorus limitation of net primary productivity suggests that phosphorus availability may restrict Amazon forest responses to CO 2 fertilization 4 , with major implications for future carbon sequestration and forest resilience to climate change. Nutrient manipulation of low-phosphorus soil in an old growth Amazon rainforest shows that phosphorus availability drives forest productivity and is likely to limit the response to increasing atmospheric CO 2 concentrations.

Dietary deficiencies of zinc and iron are a major global public health problem. An estimated two billion people suffer these deficiencies causing a loss of 63 million life years annually. Most of these people depend upon grains and legumes as their primary dietary source of zinc and iron. This manuscript reports findings from the analysis of 540 pairs of crop samples grown at contemporary and elevated [CO2] from six different FACE experiments involving six food crops. We tested the nutrient concentrations of the edible portions of rice (Oryza sativa, 18 cultivars), wheat (Triticum aestivum, 8 cultivars), maize (Zea mays, 2 cultivars), soybeans (Glycine max, 7 cultivars), field peas (Pisum sativum, 4 cultivars) and sorghum (Sorghum bicolor, 1 cultivar). In all six experiments, the elevated [CO2] was in the range of 550-584 ppm. Each crop sample grown at elevated [CO2] was paired with an identical cultivar grown under the same conditions but at contemporary [CO2]. Our main outcomes were fractional changes in concentrations of the nutrients between samples grown at elevated and contemporary [CO2] levels, estimated using a linear mixed effects statistical model. We found that elevated [CO2] was associated with significant decreases in the concentrations of zinc and iron in all C3 grasses and legumes. For example, in wheat grains grown at elevated [CO2] compared with contemporary [CO2], zinc decreased 9.6% and iron decreased 5.2%. We also found that elevated [CO2] was associated with lower protein in C3 grasses with a 6.5% decrease in wheat grains and a 7.9% (95% CI: -8.9, -6.9) decrease in rice grains. Elevated [CO2] showed no significant effect on protein in C3 legumes or C4 crops. Response differences between cultivars suggest breeding crops for reduced sensitivity to elevations in atmospheric [CO2]. Such breeding efforts may partly address the new challenges to global health that these findings highlight.

Introduction The open surgical wound is exposed to cold and dry ambient air resulting in heat loss mainly through radiation and convection. This cools the wound and promotes local vasoconstriction and hypoxia. Carbon dioxide (CO 2 ) and water vapor are greenhouse gases with a warming effect. The aim was to evaluate if warm humidified CO 2 insufflated in surgical wound can affect long-term overall mortality Methods This is a retrospective study of two clinical trials, where patients were randomized to warm humidified CO 2 ( n  = 80) or not ( n  = 78). All patients underwent elective major open colon surgery. Patients in the treatment group received insufflation of warm humidified CO 2 into the open wound cavity via a gas diffuser to create a local atmosphere of 100 % CO 2 . Temperature in the wound cavity was measured with a heat-sensitive infrared camera. Core temperature was measured at the tympanic membrane. Median follow-up was 70.9 months. Results A multivariate analysis adjusted for age ( p  = 0.001) and cancer ( p  = 0.165) showed that the larger the temperature difference between final core temperature and wound edge temperature, the lower the overall survival rate ( p  = 0.050). Patients receiving insufflation of warm humidified CO 2 had a tendency to a better overall survival compared with control patients ( p  = 0.508). End-of-operation wound edge temperature was negatively associated with mortality (OR = 0.80, 95 % CI = 0.68-0.95, p = 0.011), whereas mortality was positively associated with age (10-year increase, OR = 1.78, 95 % CI = 1.37-2.33, p < 0.001) and cancer (OR = 8.1, 95 % CI = 1.95–33.7, p = 0.004). Conclusions A small end-of-operation temperature difference between final core and wound edge temperature was positively associated with patient survival in open colon surgery.

Summary •  The consequences of increasing atmospheric carbon dioxide for long‐term adaptation of forest ecosystems remain uncertain, with virtually no studies undertaken at the genetic level. A global analysis using cDNA microarrays was conducted following 6 yr exposure of Populus × euramericana (clone I‐214) to elevated [CO2] in a FACE (free‐air CO2 enrichment) experiment. •  Gene expression was sensitive to elevated [CO2] but the response depended on the developmental age of the leaves, and < 50 transcripts differed significantly between different CO2 environments. For young leaves most differentially expressed genes were upregulated in elevated [CO2], while in semimature leaves most were downregulated in elevated [CO2]. •  For transcripts related only to the small subunit of Rubisco, upregulation in LPI 3 and downregulation in LPI 6 leaves in elevated CO2 was confirmed by anova. Similar patterns of gene expression for young leaves were also confirmed independently across year 3 and year 6 microarray data, and using real‐time RT–PCR. •  This study provides the first clues to the long‐term genetic expression changes that may occur during long‐term plant response to elevated CO2.

The rhizosphere priming effect (RPE) is a mechanism by which plants interact with soil functions. The large impact of the RPE on soil organic matter decomposition rates (from 50% reduction to 380% increase) warrants similar attention to that being paid to climatic controls on ecosystem functions. Furthermore, global increases in atmospheric CO2 concentration and surface temperature can significantly alter the RPE. Our analysis using a game theoretic model suggests that the RPE may have resulted from an evolutionarily stable mutualistic association between plants and rhizosphere microbes. Through model simulations based on microbial physiology, we demonstrate that a shift in microbial metabolic response to different substrate inputs from plants is a plausible mechanism leading to positive or negative RPEs. In a case study of the Duke Free-Air CO2 Enrichment experiment, performance of the PhotoCent model was significantly improved by including an RPE-induced 40% increase in soil organic matter decomposition rate for the elevated CO2 treatment – demonstrating the value of incorporating the RPE into future ecosystem models. Overall, the RPE is emerging as a crucial mechanism in terrestrial ecosystems, which awaits substantial research and model development.

Global climate change accompanied by continuous increases in atmospheric carbon dioxide (CO2) concentration and temperature affects the growth and yield of important crops. The present study investigated the effect of elevated temperature and CO2 concentrations on the growth, yield, and photosynthesis of potato (Solanum tuberosum L. cv. Superior) crops using Korean Soil-Plant-Atmosphere-Research chambers that allow the regulation of temperature and CO2 concentration under daylight conditions. Based on the average temperature from 1991 to 2010 in the Jeonju area, South Korea, potato plants were exposed to four different conditions: ambient weather (400 μmol mol-1, aCaT), elevated temperature (+4°C, aCeT), elevated CO2 concentration (800 μmol mol-1, eCaT), and concurrently elevated CO2 concentration and temperature (eCeT). Under aCeT conditions, the temperature exceeded the optimal growth temperature range towards the late growth phase that decreased stomatal conductance and canopy net photosynthetic rate and subsequently reduced biomass and tuber yield. Stomatal conductance and chlorophyll concentration were lower under eCaT conditions than under aCaT conditions, whereas late-growth phase biomass and tuber yield were greater. Compared to other conditions, eCeT yielded a distinct increase in growth and development and canopy net photosynthetic rate during tuber initiation and bulking. Consequently, biomass and canopy net photosynthesis increased, and tuber yield increased by 20.3%, which could be attributed to the increased tuber size, rather than increased tuber number. Elevated CO2 reduced chlorophyll, magnesium, and phosphorus concentrations; reducing nitrogen concentration (by approximately 39.7%) increased the C:N ratio. The data indicate that future climate conditions will likely change nutrient concentration and quality of crops. The present study shows that while elevated temperature may negatively influence the growth and yield of potato crops, especially towards the late-growth phase, the concurrent and appropriate elevation of CO2 and temperature could promote balanced development of source and sink organs and positively effect potato productivity and quality.

Stimulation of terrestrial plant production by rising CO₂ concentration is projected to reduce the airborne fraction of anthropogenic CO₂ emissions. Coupled climate–carbon cycle models are sensitive to this negative feedback on atmospheric CO₂, but model projections are uncertain because of the expectation that feedbacks through the nitrogen (N) cycle will reduce this so-called CO₂ fertilization effect. We assessed whether N limitation caused a reduced stimulation of net primary productivity (NPP) by elevated atmospheric CO₂ concentration over 11 y in a free-air CO₂ enrichment (FACE) experiment in a deciduous Liquidambar styraciflua (sweetgum) forest stand in Tennessee. During the first 6 y of the experiment, NPP was significantly enhanced in forest plots exposed to 550 ppm CO₂ compared with NPP in plots in current ambient CO₂, and this was a consistent and sustained response. However, the enhancement of NPP under elevated CO₂ declined from 24% in 2001–2003 to 9% in 2008. Global analyses that assume a sustained CO₂ fertilization effect are no longer supported by this FACE experiment. N budget analysis supports the premise that N availability was limiting to tree growth and declining over time—an expected consequence of stand development, which was exacerbated by elevated CO₂. Leaf- and stand-level observations provide mechanistic evidence that declining N availability constrained the tree response to elevated CO₂; these observations are consistent with stand-level model projections. This FACE experiment provides strong rationale and process understanding for incorporating N limitation and N feedback effects in ecosystem and global models used in climate change assessments.