Enameloid-bound δ15 N reveals large trophic separation among Late Cretaceous sharks in the northern Gulf of Mexico.

The nitrogen isotopic composition (15 N/14 N ratio, or δ15 N) of enameloid-bound organic matter (δ15 NEB ) in shark teeth was recently developed to investigate the biogeochemistry and trophic structures (i.e., food webs) of the ancient ocean. Using δ15 NEB , we present the first nitrogen isotopic evidence for trophic differences between shark taxa from a single fossil locality. We analyze the teeth of four taxa (Meristodonoides, Ptychodus, Scapanorhynchus, and Squalicorax) from the Late Cretaceous (83-84 Ma) Trussells Creek site in Alabama, USA, and compare the N isotopic findings with predictions from tooth morphology, the traditional method for inferring shark paleo-diets. Our δ15 NEB data indicate two distinct trophic groups, with averages separated by 6.1 ± 2.1‰. The lower group consists of Meristodonoides and Ptychodus, and the higher group consists of Scapanorhynchus and Squalicorax (i.e., lamniforms). This δ15 NEB difference indicates a 1.5 ± 0.5 trophic-level separation between the two groups, a finding that is in line with paleontological predictions of a higher trophic level for these lamniforms over Meristodonoides and Ptychodus. However, the δ15 NEB of Meristodonoides is lower than suggested by tooth morphology, although consistent with mechanical tests suggesting that higher trophic-level bony fishes were not a major component of their diet. Further, δ15 NEB indicates that the two sampled lamniform taxa fed at similar trophic levels despite their different inferred tooth functions. These two findings suggest that tooth morphology alone may not always be a sufficient indicator of dietary niche. The large trophic separation revealed by the δ15 NEB offset leaves open the possibility that higher trophic-level lamniforms, such as those measured here, preyed upon smaller, lower trophic-level sharks like Meristodonoides.

Assessment of phthalic acid esters plasticizers in sediments of coastal Alabama, USA: Occurrence, source, and ecological risk.

Considering the ubiquitous occurrences and ecotoxicity of phthalates (PAEs), it is essential to understand their sources, distribution, and associated ecological risks of PAEs in sediments to assess the environmental health of estuaries and support effective management practices. This study provides the first comprehensive dataset on the occurrence, spatial variation, inventory, and potential ecological risk assessment of PAEs in surface sediments of commercially and ecologically significant estuaries in the southeastern United States, Mobile Bay and adjoining eastern Mississippi Sound. Fifteen PAEs were widely detected in the sediments of the study region, with total concentrations varying between 0.02 and 3.37 µg/g. The dominance of low-molecular-weight (LMW) PAEs (DEP, DBP and DiBP) relative to high-molecular-weight (HMW) PAEs (DEHP, DOP, DNP) indicates that residential activities have stronger impacts than industrial activities on PAE distributions. The total PAE concentrations displayed an overall decreasing trend with increasing bottom water salinity, with the maximum concentrations occurring near river mouths. These observations suggest that river inputs were an important pathway by which PAEs were transported to the estuary. Linear regression models identified sediment adsorption (measured by total organic carbon and median grain size) and riverine inputs (measured by bottom water salinity) as significant predictors for the concentrations of LMW and HMW PAEs. Estimated 5-year total inventories of sedimentary PAEs in Mobile Bay and the eastern Mississippi Sound were 13.82 tons and 1.16 tons, respectively. Risk assessment calculations suggest that LMW PAEs posed a medium-to-high risk to sensitive aquatic organisms, and DEHP posed a low or negligible risk to the aquatic organisms. The results of this study provide important information needed for establishing and implementing effective practices for monitoring and regulating plasticizer pollutants in estuaries.

Lipid biomarkers recording marine microbial community structure changes through the Frasnian-Famennian mass extinction event.

Studying the response and recovery of marine microbial communities during mass extinction events provides an evolutionary window through which to understand the adaptation and resilience of the marine ecosystem in the face of significant environmental disturbances. The goal of this study is to reconstruct changes in the marine microbial community structure through the Late Devonian Frasnian-Famennian (F-F) transition. We performed a multiproxy investigation on a drill core of the Upper Devonian New Albany Shale from the Illinois Basin (western Kentucky, USA). Aryl isoprenoids show green sulfur bacteria expansion and associated photic zone euxinia (PZE) enhancement during the F-F interval. These changes can be attributed to augmented terrigenous influxes, as recorded collectively by the long-chain/short-chain normal alkane ratio, carbon preference index, C30 moretane/C30 hopane, and diahopane index. Hopane/sterane ratios reveal a more pronounced dominance of eukaryotic over prokaryotic production during the mass extinction interval. Sterane distributions indicate that the microalgal community was primarily composed of green algae clades, and their dominance became more pronounced during the F-F interval and continued to rise in the subsequent periods. The 2α-methylhopane index values do not show an evident shift during the mass extinction interval, whereas the 3ß-methylhopane index values record a greater abundance of methanotrophic bacteria during the extinction interval, suggesting enhanced methane cycling due to intensified oxygen depletion. Overall, the Illinois Basin during the F-F extinction experienced heightened algal productivity due to intensified terrigenous influxes, exhibiting similarities to contemporary coastal oceans that are currently undergoing globalized cultural eutrophication. The observed microbial community shifts associated with the F-F environmental disturbances were largely restricted to the extinction interval, which suggests a relatively stable, resilient marine microbial ecosystem during the Late Devonian.

Stability of organic matter-iron-phosphate associations during abiotic reduction of iron.

The stability of organic matter-iron-phosphate (OM-Fe-P) association has an important impact on the migration and sequestration of organic carbon (OC) and P in the environment. Here, we examined the release characteristics of Fe, P and OM due to the abiotic reduction of OM-Fe-P associations by Na-dithionite. The associations were synthesized with algae-derived OM (AOM) and terrestrial humic acid (HA) through either adsorption onto iron (hydr)oxide or coprecipitation with Fe(III). Results indicated that OM and P adsorbed onto the associations were rapidly released, whereas coprecipitation yielded much lower release rates of Fe, P, and OM. The stronger inhibitory effect on reduction from coprecipitation can be explained by larger particles formed by coprecipitation and coprecipitation taking up more OC that had a passivation effect on the associations. The release rates of OM and P were lower in coprecipitates formed with HA than formed with AOM for a given OC/Fe ratio. This observation can be attributed to a patchy distribution of OC in AOM associated coprecipitates, which showed a weaker aggregation of OC with Fe and P. In contrast, the distribution of OC in HA-associated coprecipitates was more homogenous, enabling a stronger aggregation of OM with P and a greater passivation effect on P release. Our results revealed that OM sources, association formation pathways, and elemental stoichiometry collectively controlled the stability of OM-Fe-P associations.

Seasonal changes of trace elements, nutrients, dissolved organic matter, and coastal acidification over the largest oyster reef in the Western Mississippi Sound, USA.

Seasonal changes of trace elements, nutrients, dissolved organic matter (DOM), and carbonate system parameters were evaluated over the largest deteriorating oyster reef in the Western Mississippi Sound using data collected during spring, summer, and winter of 2018, and summer of 2019. Higher concentrations of Pb (224%), Cu (211%), Zn (2400%), and Ca (240%) were observed during winter of 2018 compared to summer 2019. Phosphate and ammonia concentrations were higher (> 800%) during both summers of 2018 and 2019 than winter of 2018. Among the three distinct DOM components identified, two terrestrial humic-like components were more abundant during both spring (12% and 36%) and summer (11% and 33%) of 2018 than winter of 2018, implying a relatively lesser supply of humic-like components from terrestrial sources during winter. On the other hand, the protein-like component was more abundant during summer of 2019 compared to rest of the study period, suggesting a higher rate of autochthonous production during summer 2019. In addition, to their significant depth-wise variation, ocean acidification parameters including pH, pCO2, CO32-, and carbonate saturation states were all higher during both summers of 2018 and 2019. The measured variables such as trace elements, organic carbon, suspended particulates, and acidification parameters exhibited conservative mixing behavior against salinity. These observations have strong implications for the health of the oyster reefs, which provides ecologically important habitats and supports the economy of the Gulf Coast.

Identifying survival protective factors for chronic dialysis patients with surgically confirmed acute mesenteric ischemia.

BACKGROUND: Mesenteric ischemia is significantly more common in end-stage kidney disease patients undergoing chronic dialysis than in the general population and is associated with high morbidity and mortality. However, reports on prognostic factors in this population are limited. AIM: To elucidate the in-hospital outcomes of acute mesenteric ischemia in chronic dialysis patients and to analyze protective factors for survival. METHODS: The case data of 426 chronic dialysis patients who were hospitalized in a tertiary medical center for acute mesenteric ischemia over a 14-year period were retrospectively reviewed. Of these cases, 103 were surgically confirmed, and the patients were enrolled in this study. A Cox regression analysis was used to evaluate the protective factors for survival. RESULTS: The in-hospital mortality rate among the 103 enrolled patients was 46.6%. Univariate analysis was performed to compare factors in survivors and nonsurvivors, with better in-hospital outcomes associated with a surgery delay (defined as the time from onset of signs and symptoms to operation) < 4.5 d, no shock, a higher potassium level on day 1 of hospitalization, no resection of the colon, and a total bowel resection length < 110 cm. After 1 wk of hospitalization, patients with lower white blood cell count and neutrophil counts, higher lymphocyte counts, and lower C-reactive protein levels had better in-hospital outcomes. Following multivariate adjustment, a higher potassium level on day 1 of hospitalization (HR 1.71, 95%CI 1.19 to 2.46; P = 0.004), a lower neutrophil count (HR 0.91, 95%CI 0.84 to 0.99; P = 0.037) at 1 wk after admission, resection not involving the colon (HR 2.70, 95%CI 1.05 to 7.14; P = 0.039), and a total bowel resection length < 110 cm (HR 4.55, 95%CI 1.43 to 14.29; P = 0.010) were significantly associated with survival. CONCLUSION: A surgery delay < 4.5 d, no shock, no resection of the colon, and a total bowel resection length < 110 cm predicted better outcomes in chronic dialysis patients with acute mesenteric ischemia.

Sources and composition of natural and anthropogenic hydrocarbons in sediments from an impacted estuary.

Hydrocarbons in estuarine sediments provide information on sources of sedimentary organic matter (OM), and they are thus useful for tracing natural and anthropogenic OM inputs to the estuary. Here, we assessed the amounts, compositions and sources of natural and anthropogenic hydrocarbons from the sediments of a large, ecologically important estuary, Mobile Bay in Southeast USA. TOC/TN ratios and δ13C of organic carbon suggest that the bulk natural OM was sourced from marine phytoplankton and bacteria mixed with marsh and terrigenous C3 plants. Normal alkanes show high proportions of long-chain compounds with a high Carbon Preference Index, indicating the importance of C3 plants-derived OM in Mobile Bay. High concentrations of biogenic hopanes and perylene indicate microbial sources and degradation played an important role in shaping OM compositions. Anthropogenic hydrocarbons, αß-hopanes and polycyclic aromatic hydrocarbons (PAHs), were widely detected in Mobile Bay sediments. The source diagnostic ratios of hopanes and steranes suggest they were sourced from coal and diesel combustions. The source diagnostic ratios of PAHs, together with a positive correlation between PAHs and total mercury, suggests that PAHs originated primarily from coal combustion. We proposed two ratios, αß-hopanes/(ßß-hopanes+hopenes) and 16 PAHs/perylene, to evaluate anthropogenic versus natural contributions of hydrocarbons. These ratios were higher in the western estuary than in the eastern estuary, suggesting elevated anthropogenic hydrocarbon inputs to the western estuary. Correspondingly, the toxic equivalent quantity (TEQBaQ) of PAHs showed a higher ecological risk for the western estuary. This spatially uneven distribution of hydrocarbon pollutants can be attributed to more concentrated urban and industrial areas on the western shore, suggesting the importance of adjacent pollution sources. Collectively, our results provide new insights into the origins and dynamics of natural and anthropogenic OM and highlight the significance of coal combustion in contributing hydrocarbon pollutants in Mobile Bay sediments.

Adsorption of humic acids to lake sediments: Compositional fractionation, inhibitory effect of phosphate, and implications for lake eutrophication.

Humic acid (HA) and phosphate interactions play a vital role in the biogeochemical cycle of carbon and nutrients and thus the trophic state of a lake. The adsorption behavior of HAs to sediments in the absence and presence of phosphate was investigated in this study. Three types of HAs were used, AHA from algae-dominated lake sediments, MHA from macrophyte-dominated lake sediments, and a reference HA (RHA) with terrestrial sources. The adsorption capacity of lake sediments was highest for AHA, which can be explained by that AHA contained more carboxyl-containing molecules, proteinaceous compounds and polysaccharides that were preferentially adsorbed by minerals. Phosphate showed a stronger inhibitory effect on MHA adsorption than on AHA adsorption, suggesting that AHA can more effectively replace phosphate adsorbed to sediments. Our findings show that the functional groups of organic compounds control not only their fractionation and burial but also their ability to replace phosphate in sediments. We propose a novel mechanism to explain the legacy effect of lake eutrophication. That is, as lakes shift from a macrophyte-dominated state to more eutrophic, algae-dominated state, increasing algae-derived organic compounds can promote the release of phosphate from sediments, forming a positive feedback loop that sustains internal phosphorus loading and hence lake eutrophication.

In-Hospital Outcomes and Recurrence of Infectious Spondylitis in Patients with and without Chronic Hemodialysis: A Nationwide Cohort Study.

Purpose: The incidence of bloodstream infection among end-stage kidney disease (ESKD) patients on chronic hemodialysis (HD) was 26-fold higher than population controls, causing higher morbidity and costs. The aim of this investigation was to clarify the prognostic factors, in-hospital outcomes and recurrence of infectious spondylitis of patients with and without chronic HD. Patients and Methods: This nationwide study analyzed 2592 patients who admitted for first-time infectious spondylitis between January 1, 2003, and December 31, 2015. Patients were classified into the chronic HD or the non-HD group. The logistic regression model and the general linear model were utilized to determine the impact of chronic HD on in-hospital mortality and recurrence. The Cox proportional hazard model was used to estimate the predictive factors of in-hospital mortality and recurrence. Results: Compared to the non-HD group, patients in the chronic HD group had a higher risk of respiratory failure, sepsis, in-hospital mortality, longer hospital stay, and higher medical spending. Chronic HD was an independent risk factor for in-hospital mortality (hazard ratio 2.21, 95% confidence interval 1.34-3.65, p=0.0019), but not for recurrence. Intravascular device implantation or revision was a prognosticator for the mortality of both groups and a predictor for recurrence of the non-HD group. Surgical treatment was associated with a decreased risk of recurrence, whereas treatment with CT-guided abscess drainage was associated with an increased risk of recurrence in both groups. Conclusion: Patients with infectious spondylitis who were receiving chronic HD had a higher in-hospital mortality compared to those without HD. Intravascular device implantations or revision within 6 months was a significant predictor of in-hospital mortality and disease recurrence. Surgical treatment of infectious spondylitis had a lower risk of recurrence than those with CT-guided abscess drainage in both patient groups.

Clinical and visual outcomes following endogenous endophthalmitis: 175 consecutive cases from a tertiary referral center in Taiwan.

BACKGROUND: To elucidate the linkage between organisms and visual outcome in cases of endogenous endophthalmitis. METHODS: Patients who presented with signs of endogenous endophthalmitis between January 2008 and December 2015 and underwent a vitreous tapping were enrolled. The patients' demographics and clinical findings were recorded. The outcomes include visual acuity and enucleation. RESULTS: A total of 175 consecutive patients with endogenous endophthalmitis were enrolled. Forty-four percent of the patients had a known distal focus of infection. The most common focus was liver abscess (24.6%), and the major intravitreal isolate was Klebsiella pneumoniae (34.4%). In this series, 51.4% of the intravitreal cultures were positive. The visual acuity of fungal ophthalmitis were better than in bacterial ophthalmitis. Multivariate logistic regression showed that Gram negative vitreous isolates, compared with the negative vitreous culture, were associated with higher risk of enucleation (Odds ratio [OR]: 10.424, 95% confidence interval [95% CI]: 3.019-35.995). The use of intravitreal antibiotics, compared non-users, was associated with a reduced risk of enucleation (OR:0.084, 95% CI: 0.026-0.268). Trans pars plana vitrectomy was not associated with risk of enucleation (OR: 0.307, 95% CI: 0.035-2.693). The post-treatment VA was positively correlated with the presenting VA (r = 0.718, p = 0.0001). CONCLUSION: Our study demonstrated that liver abscess is the most common source of endogenous endophthalmitis in Taiwan. The visual outcome is good when the presenting visual acuity is relatively well preserved and when the infecting organism is fungus. The use of intra-vitreal antibiotics reduces the risk of enucleation.

CD147 mediates the CD44s-dependent differentiation of myofibroblasts driven by transforming growth factor-ß1.

Progressive fibrosis leads to loss of organ function and affects many organs as a result of excessive extracellular matrix production. The ubiquitous matrix polysaccharide hyaluronan (HA) is central to this through association with its primary receptor, CD44, which exists as standard CD44 (CD44s) or multiple splice variants. Mediators such as profibrotic transforming growth factor (TGF)-ß1 and proinflammatory interleukin (IL)-1ß are widely associated with fibrotic progression. TGF-ß1 induces myofibroblast differentiation, while IL-1ß induces a proinflammatory fibroblast phenotype that promotes fibroblast binding to monocyte/macrophages. CD44 expression is essential for both responses. Potential CD44 splice variants involved, however, are unidentified. The TGF-ß1-activated CD44/epidermal growth factor receptor complex induces differentiation of metastatic cells through interactions with the matrix metalloproteinase inducer, CD147. This study aimed to determine the CD44 variants involved in TGF-ß1- and IL-1ß-mediated responses and to investigate the potential profibrotic role of CD147. Using immunocytochemistry and quantitative PCR, standard CD44s were shown to be essential for both TGF-ß1-induced fibroblast/myofibroblast differentiation and IL-1ß-induced monocyte binding. Co-immunoprecipitation identified that CD147 associated with CD44s. Using CD147-siRNA and confocal microscopy, we also determined that incorporation of the myofibroblast marker, αSMA, into F-actin stress fibers was prevented in the absence of CD147 and myofibroblast-dependent collagen gel contraction was inhibited. CD147 did not associate with HA, but removal of HA prevented the association of CD44s with CD147 at points of cell-cell contact. Taken together, our data suggest that CD44s/CD147 colocalization is essential in regulating the mechanical tension required for the αSMA incorporation into F-actin stress fibers that regulates myofibroblast phenotype.

miR-141 mediates recovery from acute kidney injury.

Acute kidney injury (AKI) is a global clinical problem characterised by a sudden decline in renal function and mortality as high as 60%. Current AKI biomarkers have limited ability to classify disease progression and identify underlying pathological mechanisms. Here we hypothesised that alterations in urinary microRNA profiles could predict AKI recovery/nonrecovery after 90 days, and that injury-specific changes would signify microRNA mediators of AKI pathology. Comparison of urinary microRNA profiles from AKI patients with controls detected significant injury-specific increases in miR-21, miR-126 and miR-141 (p < 0.05) and decreases in miR-192 (p < 0.001) and miR-204 (p < 0.05). Expression of miR-141 increased in renal proximal tubular epithelial cells (PTECs) under oxidative stress in vitro and unilateral ischaemic reperfusion injury in vivo. Forced miR-141 expression in the presence of H2O2 increased PTEC death and decreased cell viability. Of nine messenger RNA targets with two or more miR-141 3'-untranslated region binding sites, we confirmed protein tyrosine phosphatase receptor type G (PTPRG) as a direct miR-141 target in PTECs. PTPRG-specific siRNA knockdown under oxidative stress increased PTEC death and decreased cell viability. In conclusion, we detected significant alterations in five urinary microRNAs following AKI, and identified proximal tubular cell PTPRG as a putative novel therapeutic target.

Agricultural land use changes stream dissolved organic matter via altering soil inputs to streams.

Agricultural land use leads to significant changes in both the quality (e.g., sources and compositions) and quantity of dissolved organic matter (DOM) exported from terrestrial to aquatic ecosystems. However, the effect of agricultural activities often interacts with those of hydroclimatic drivers, making it difficult to delineate agriculture-induced changes and identify associated mechanisms. Using partial least square path modeling (PLS-PM), we examined the relative importance of agricultural land use, stream order, precipitation, and temperature in mediating allochthonous versus autochthonous sources and pathways that influenced stream DOM quality and quantity. We analyzed stream water DOM from 15 small streams draining watersheds across a gradient of agricultural land use in Southeast USA for about one year. For DOM quantity, agricultural land use increased the export of DOC and various DOM pools (terrestrial humic, microbial humic, and protein-like DOM) from land to streams, and for DOM quality, agricultural streams showed greater proportions of microbial humic compounds than forested streams. The PLS-PM model for DOM quantity accounted for 75.5% of total variance and identified that agricultural land use increased stream water DOM quantity primarily through increasing allochthonous inputs, which can be attributed to shallower flow paths in agricultural watersheds that enabled the export of organic materials from the upper, organic-rich soil horizon. PLS-PM models for DOM quality only explained ~13% of the total variance, highlighting the complex dynamics between environmental drivers and stream water DOM. Relative to commonly used multivariate statistic modeling (e.g., redundancy analysis (RDA)), PLS-PM models offer the advantages of identifying the primary pathway by which agricultural lands alter freshwater DOM and quantifying the relative importance of interactive effects of agriculture and hydroclimatic drivers. Therefore, structural equation modeling is a powerful tool that should be more widely adopted to distinguish among multiple drivers and mechanisms regulating freshwater biogeochemistry.

Single-Nucleus RNA Sequencing Identifies New Classes of Proximal Tubular Epithelial Cells in Kidney Fibrosis.

BACKGROUND: Proximal tubular cells (PTCs) are the most abundant cell type in the kidney. PTCs are central to normal kidney function and to regeneration versus organ fibrosis following injury. This study used single-nucleus RNA sequencing (snRNAseq) to describe the phenotype of PTCs in renal fibrosis. METHODS: Kidneys were harvested from naïve mice and from mice with renal fibrosis induced by chronic aristolochic acid administration. Nuclei were isolated using Nuclei EZ Lysis buffer. Libraries were prepared on the 10× platform, and snRNAseq was completed using the Illumina NextSeq 550 System. Genome mapping was carried out with high-performance computing. RESULTS: A total of 23,885 nuclei were analyzed. PTCs were found in five abundant clusters, mapping to S1, S1-S2, S2, S2-cortical S3, and medullary S3 segments. Additional cell clusters ("new PTC clusters") were at low abundance in normal kidney and in increased number in kidneys undergoing regeneration/fibrosis following injury. These clusters exhibited clear molecular phenotypes, permitting labeling as proliferating, New-PT1, New-PT2, and (present only following injury) New-PT3. Each cluster exhibited a unique gene expression signature, including multiple genes previously associated with renal injury response and fibrosis progression. Comprehensive pathway analyses revealed metabolic reprogramming, enrichment of cellular communication and cell motility, and various immune activations in new PTC clusters. In ligand-receptor analysis, new PTC clusters promoted fibrotic signaling to fibroblasts and inflammatory activation to macrophages. CONCLUSIONS: These data identify unrecognized PTC phenotype heterogeneity and reveal novel PTCs associated with kidney fibrosis.

In-Hospital and Long-Term Outcomes of Infective Endocarditis in Chronic Dialysis Patients.

PURPOSE: To elucidate the in-hospital and long-term outcomes of infective endocarditis (IE) in end-stage kidney disease (ESKD) patients on chronic dialysis and to analyze the risk factors of mortality. PATIENTS AND METHODS: The case files of 1,817 patients who were hospitalized for IE over a 14-year period were retrospectively reviewed. Of these, 116 ESKD patients on chronic dialysis were enrolled in this study. Cox's proportional hazard model was used to evaluate the risk factors of mortality and long-term outcomes. RESULTS: The in-hospital mortality rate of the 116 enrolled patients was as high as 43.1%. Patients who survived the index admission had a three-year mortality rate of 33%. Univariate analysis was used to compare survivors and non-survivors; poor in-hospital outcomes were associated with the use of a tunneled cuffed catheter for dialysis access, a shorter duration hospitalization, shock or respiratory failure during hospitalization, a higher white blood count, a higher percentage of polymorphonuclear leukocytes, a higher C-reactive protein level, a lower serum albumin level, and a higher total bilirubin level. Following multivariate adjustment, shock (odds ratio, 9.29, with a 95% confidence interval [CI] of 2.78 to 34.24; p<0.001) or respiratory failure (odds ratio, 25.16, with a 95% CI of 5.63 to 153.54; p<0.001) during hospitalization was strongly associated with increased in-hospital mortality. Patients who underwent cardiac operations (odds ratio, 0.22, with a 95% CI of 0.052 to 0.86; p=0.031) had better in-hospital outcomes. Heart failure reduced ejection fraction (HFrEF) at the time of initial hospitalization was an independent risk factor for 3-year mortality (hazard ratio, 3.48, with a 95% CI of 1.09 to 11.09; p=0.035). CONCLUSION: The outcomes of IE for ESKD patients on chronic dialysis were poor. Only 56.9% of these patients survived the index admission and their mortality rate over three years was 33%. Shock or respiratory failure during hospitalization was associated with increased in-hospital mortality. Patients who underwent cardiac operations had better in-hospital outcomes. HFrEF at the time of initial hospitalization was an independent risk factor for three-year mortality.

Irrigation alters source-composition characteristics of groundwater dissolved organic matter in a large arid river basin, Northwestern China.

It has been well documented that agricultural activities lead to significant alterations in surface water dissolved organic matter (DOM), yet their impacts on groundwater DOM remain poorly constrained. The quantity, source, and composition of DOM play a pivotal role in a range of groundwater ecosystem services that are of important ecological and societal values. We assessed the impact of irrigation on the source and compositional characteristics of groundwater DOM in a large river basin supporting intensive agriculture in arid northwestern China. We sampled five water types along a river reach of approximately 40 km, including groundwater, river water, irrigation canal water, hyporheic water, and soil leachates. The excitation-emission matrix (EEM) measurements coupled with parallel factor analysis (PARAFAC) identified two terrestrial-derived, humic-like fluorescent components (C1 and C2) and one protein-like autochthonous component (C3). DOM composition and dissolved organic carbon (DOC) concentration varied as a function of water type, with subsurface waters showing relatively lower DOC and terrestrial humic fluorescence than surface waters. Combining nitrate, electrical conductivity, dissolved inorganic carbon (DIC), and δ13C-DIC, irrigation-influenced samples were identified, and the influence of irrigation on groundwater DOM appeared only in shallow aquifers (<50 m). Irrigation-influenced groundwater exhibited higher DOC and terrestrial fluorescence than unimpacted groundwater, suggesting that irrigation return flows accelerated the downward movement of terrestrial humic compounds and led to their accumulation in aquifers. This effect was propagated via surface water-groundwater interactions to upwelling hyporheic water, which also showed enrichment in terrestrial fluorescence. Our findings demonstrate that irrigation can accelerate the biogeochemical cycling of organic compounds via a subsurface pathway of from the soil to aquifer to hyporheic zone. The enrichment of soil-derived compounds in subsurface waters may have important ecological consequences, such as altering the transport of nutrients and pollutants and changing carbon and energy flows across the surface-subsurface boundary.

Direct versus indirect effects of human activities on dissolved organic matter in highly impacted lakes.

Human activities can alter dissolved organic matter (DOM) in lakes through both direct (i.e., exporting DOM of anthropogenic sources) and indirect effects (i.e., enhancing the autochthonous production of DOM via nutrient loading). Distinguishing between the direct and indirect effects is important to better understand human impacts on aquatic systems, but it remains highly challenging due to the interdependence of associated environmental variables. Here, we demonstrated that disentangling the direct and indirect effects can be achieved through combining large-scale environmental monitoring with the Partial Least Squares Path Modeling (PLS-PM). We presented DOM data from 61 lakes within the floodplain of the Yangtze River (Lakes-YR), China, a region that has been subjected to intense anthropogenic disturbances. We analyzed the amount and composition of DOM through dissolved organic carbon (DOC), chromophoric DOM (CDOM), and fluorescent DOM (FDOM). Four fluorescence components were identified, including one tyrosine-like component, one tryptophan-like component, and two humic-like components. Most of the lakes were dominated by freshly produced DOM with small molecular weights and low humification. Results from the PLS-PM models showed that the autochthonous production was more important than anthropogenic inputs in mediating DOC and CDOM. In contrast, FDOM parameters in lakes were more sensitive to the direct, anthropogenic sources, including treated domestic, industrial wastewater, and the effluents of aquaculture. These sources can be identified by elevated FDOM content per DOC (FDOM: DOC ratio) relative to autochthonous DOM, suggesting the potential of using FDOM as a tracer to identify and monitor the contribution of anthropogenic organic matter to inland waters.

Mid-term survival of patients with chronic kidney disease after extracorporeal membrane oxygenation.

OBJECTIVES: Chronic kidney disease (CKD) impairs the elimination of fluids, electrolytes and metabolic wastes, which can affect the outcomes of extracorporeal membrane oxygenation (ECMO) treatment. This study aimed to elucidate the impact of CKD on in-hospital mortality and mid-term survival of adult patients who received ECMO treatment. METHODS: Patients who received first-time ECMO treatment between 1 January 2003 and 31 December 2013 were included. Those with CKD were identified and matched to patients without CKD using a 1:2 ratio and were followed for 3 years. The study outcomes included in-hospital outcomes and the 3-year mortality rate. A subgroup analysis was conducted by comparing the dialytic patients with the non-dialytic CKD patients. RESULTS: The study comprised 1008 CKD patients and 2016 non-CKD patients after propensity score matching. The CKD patients had higher in-hospital mortality rates [69.5% vs 62.2%; adjusted odds ratio 1.41; 95% confidence interval (CI) 1.15-1.72] than the non-CKD patients. The 3-year mortality rate was 80.4% in the CKD group and 68% in the non-CKD group (adjusted hazard ratio 1.17; 95% CI 1.06-1.28). The subgroup analysis showed that the 3-year mortality rates were 84.5% and 78.4% in the dialytic and non-dialytic patients, respectively. No difference in the 3-year mortality rate was noted between the 2 CKD subgroups (P = 0.111). CONCLUSIONS: CKD was associated with increased risks of in-hospital and mid-term mortalities in patients who received ECMO treatment. Furthermore, no difference in survival was observed between the patients with end-stage renal disease and non-dialytic CKD patients.

Abundance and morphology of charcoal in sediments provide no evidence of massive slash-and-burn agriculture during the Neolithic Kuahuqiao culture, China.

It remains debatable whether slash-and-burn practices were adopted in rice cultivation by the Neolithic Kuahuqiao culture in the Ningshao Plain, one of the birthplaces of rice farming. Here, we established charcoal-based indices to reconstruct the history of fire and vegetation in the Ningshao Plain since the last glacial period. We collected representative modern vegetation and conducted combustion and fragmentation experiments to simulate fire and depositional processes, respectively. Charcoals from modern vegetation show clear morphological differences between herbaceous and woody plants. In particular, the length to width ratios (L/W) of herbaceous charcoals were systematically higher than those of woody charcoals, and the associated end-member values were 4.50 and 1.94, respectively. These values were then applied to sediment cores (KHQ-14/15) collected in proximity to the Kuahuqiao archaeological site. Results show that the amount of combusted herbaceous plants increased sharply after the Holocene, and the most remarkable rise occurred around 8550 yr B.P. This observation may reflect local environment (sedimentary and/or climatic) changes or small-scale early human activities. During the Kuahuqiao cultural period (8250-7450 yr B.P.), the relative abundance of woody charcoals increased, but the overall fire intensity decreased. This finding suggests that the Kuahuqiao farming was restricted to a small geographic area and large-scale slash-and-burn farming activities were not adopted.

Effects of nitrogen fertilization and bioenergy crop type on topsoil organic carbon and total Nitrogen contents in middle Tennessee USA.

Nitrogen (N) fertilization affects bioenergy crop growth and productivity and consequently carbon (C) and N contents in soil, it however remains unclear whether N fertilization and crop type individually or interactively influence soil organic carbon (SOC) and total N (TN). In a three-year long fertilization experiment in switchgrass (SG: Panicum virgatum L.) and gamagrass (GG: Tripsacum dactyloides L.) croplands in Middle Tennessee USA, soil samples (0-15cm) were collected in plots with no N input (NN), low N input (LN: 84 kg N ha-1 yr-1 in urea) and high N input (HN: 168 kg N ha-1 yr-1 in urea). Besides SOC and TN, the aboveground plant biomass was also quantified. In addition to a summary of published root morphology data based on a separated mesocosm experiment, the root leachable dissolved organic matter (DOM) of both crops was also measured using archived samples. Results showed no significant interaction of N fertilization and crop type on SOC, TN or plant aboveground biomass (ABG). Relative to NN, HN (not LN) significantly increased SOC and TN in both crops. Though SG showed a 15-68% significantly higher ABG than GG, GG showed a 9.3-12% significantly higher SOC and TN than SG. The positive linear relationships of SOC or TN with ABG were identified for SG. However, GG showed structurally more complex and less readily decomposed root DOM, a larger root volume, total root length and surface area than SG. Collectively, these suggested that intensive N fertilization could increase C and N stocks in bioenergy cropland soils but these effects may be more likely mediated by the aboveground biomass in SG and root chemistry and morphology in GG. Future studies are expected to examine the root characteristics in different bioenergy croplands under the field fertilization experiment.