Carbon fluxes in subduction zones can be better constrained by including new estimates of carbon concentration in subducting mantle peridotites, consideration of carbonate solubility in aqueous fluid ...along subduction geotherms, and diapirism of carbon-bearing metasediments. Whereas previous studies concluded that about half the subducting carbon is returned to the convecting mantle, we find that relatively little carbon may be recycled. If so, input from subduction zones into the overlying plate is larger than output from arc volcanoes plus diffuse venting, and substantial quantities of carbon are stored in the mantle lithosphere and crust. Also, if the subduction zone carbon cycle is nearly closed on time scales of 5â10 Ma, then the carbon content of the mantle lithosphere + crust + ocean + atmosphere must be increasing. Such an increase is consistent with inferences from noble gas data. Carbon in diamonds, which may have been recycled into the convecting mantle, is a small fraction of the global carbon inventory.
This paper reviews carbon fluxes into and out of subduction zones, using compiled data, calculations of carbon solubility in aqueous fluids, and estimates of carbon flux in metasedimentary diapirs. Upper-bound estimates suggest that most subducting carbon is transported into the mantle lithosphere and crust, whereas previous reviews suggested that about half is recycled into the convecting mantle. If upper-bound estimates are correct, and observed output from volcanoes and diffuse outgassing is smaller, then the mantle lithosphere is an important reservoir for carbon. If the subduction carbon cycle remains in balance, then outgassing from ridges and ocean islands is not balanced, so that the carbon content of the lithosphere + ocean + atmosphere has increased over Earth history.
Abstract Background Increases in serum creatinine (ΔSCr) from baseline signify acute kidney injury (AKI) but offer little granular information regarding its characteristics. The 10th Consensus ...Conference of the Acute Dialysis Quality Initiative (ADQI) suggested that combining AKI biomarkers would provide better precision for AKI course prognostication. Objectives This study investigated the value of combining a functional damage biomarker (plasma cystatin C pCysC) with a tubular damage biomarker (urine neutrophil gelatinase-associated lipocalin uNGAL), forming a composite biomarker for prediction of discrete characteristics of AKI. Methods Data from 345 children after cardiopulmonary bypass (CPB) were analyzed. Severe AKI was defined as Kidney Disease Global Outcomes Initiative stages 2 to 3 (≥100% ΔSCr) within 7 days of CPB. Persistent AKI lasted >2 days. SCr in reversible AKI returned to baseline ≤48 h after CPB. The composite of uNGAL (>200 ng/mg urine Cr = positive +) and pCysC (>0.8 mg/l = positive +), uNGAL+/pCysC+, measured 2 h after CPB initiation, was compared to ΔSCr increases of ≥50% for correlation with AKI characteristics by using predictive probabilities, likelihood ratios (LR), and area under the curve receiver operating curve (AUC-ROC) values. Results Severe AKI occurred in 18% of patients. The composite uNGAL+/pCysC+ demonstrated a greater likelihood than ΔSCr for severe AKI (+LR: 34.2 13.0:94.0 vs. 3.8 1.9:7.2) and persistent AKI (+LR: 15.6 8.8:27.5 versus 4.5 2.3:8.8). In AKI patients, the uNGAL−/pCysC+ composite was superior to ΔSCr for prediction of transient AKI. Biomarker composites carried greater probability for specific outcomes than ΔSCr strata. Conclusions Composites of functional and tubular damage biomarkers are superior to ΔSCr for predicting discrete characteristics of AKI.
Perioperative advances have led to significant improvements in outcomes after many complex neonatal open heart procedures. Whether similar improvements have been realized for the modified ...Blalock-Taussig shunt, the most common palliative neonatal closed-heart procedure, is not known.
Data were abstracted from The Society of Thoracic Surgeons Congenital Heart Surgery Database (2002 to 2009). Inclusion criteria were all neonates who received a modified Blalock-Taussig shunt with or without cardiopulmonary bypass, and with or without concomitant ligation of a patent ductus arteriosus. Discharge mortality was the primary end point. A composite morbidity end point one or more of the following: postoperative extracorporeal membrane oxygenation, low cardiac output, or unplanned reoperation. Associations with patient and procedural variables were assessed with univariable and multivariable analyses.
The inclusion criteria were met by 1273 patients. The discharge mortality rate was 7.2%, and composite morbidity, as defined, was 13.1%. Primary diagnoses were classified as (1) those potentially amenable to biventricular repair (62%), (2) functionally univentricular hearts (22%), and (3) pulmonary atresia with intact ventricular septum (PA/IVS; 14%), and miscellaneous (2%). Discharge mortality stratified by primary diagnoses was PA/IVS (15.6%), functionally univentricular hearts (7.2%), and diagnoses potentially amenable to biventricular repair (5.1%). Need for preoperative ventilatory support, diagnosis of PA/IVS or functionally univentricular hearts, and any weight less than 3 kg, were risk factors for death. Preoperative acidosis or shock (resolved or persistent) and diagnosis of PA/IVS or functionally univentricular hearts were predictors of composite morbidity. Nearly 33% of the deaths occurred within 24 hours postoperatively, and 75% within the first 30 days.
The mortality rate after the neonatal modified Blalock-Taussig shunt remains high, particularly for infants weighing less than 3 kg and those with the diagnosis of PA/IVS.
Heart valve disease is an important cause of morbidity and mortality worldwide. Little is known about valve disease pathogenesis, but increasing evidence implicates a genetic basis for valve disease, ...suggesting a developmental origin. Although the cellular and molecular processes involved in early valvulogenesis have been well described, less is known about the regulation of valve extracellular matrix (ECM) organization and valvular interstitial cell (VIC) distribution that characterize the mature valve structure. Histochemistry, immunohistochemistry, and electron microscopy were used to examine ECM organization, VIC distribution, and cell proliferation during late valvulogenesis in chicken and mouse. In mature valves, ECM organization is conserved across species, and developmental studies demonstrate that ECM stratification begins during late embryonic cusp remodeling and continues into postnatal life. Cell proliferation decreases concomitant with ECM stratification and VIC compartmentalization. Explanted, stenotic bicuspid aortic valves (BAVs) from pediatric patients were also examined. The diseased valves exhibited disruption of the highly organized ECM and VIC distribution seen in normal valves. Cusps from diseased valves were thickened with increased and disorganized collagens and proteoglycans, decreased and fragmented elastic fibers, and cellular disarray without calcification or cell proliferation. Taken together, these studies show that normal valve development is characterized by spatiotemporal coordination of ECM organization and VIC compartmentalization and that these developmental processes are disrupted in pediatric patients with diseased BAVs.
Objectives This study describes results of tracheal reconstruction in children with slide tracheoplasty with cardiopulmonary bypass and identifies predictors for adverse outcomes. Methods ...Preoperative characteristics, operative variables, and outcome measures were collected for children undergoing slide tracheoplasty with cardiopulmonary bypass between April 2001 and October 2009. Predictors of worse outcomes were identified by bivariate analysis. Multiple regression analysis was performed for predictors of prolonged hospital stay. Results Cohort included 80 patients (median age, 8.7 months; 7 days–21 years). Forty-eight patients had associated cardiac or great vessel anomalies; 24 had simultaneous repair of cardiovascular anomaly at tracheal reconstruction. Fifty (63%) were extubated within 48 hours after operation. Median stay was 18.5 days (range, 7–119 days). Twenty-three patients (29%) required significant airway reintervention during median follow-up of 12 months (range, 4 months–7.8 years). There were 4 deaths, 2 early and 2 late. In bivariate analysis, age ( P = .017), cardiopulmonary bypass duration ( P = .025), and duration of mechanical ventilation ( P < .05) were associated with mortality; duration of postoperative mechanical ventilation was associated with need for significant airway reintervention ( P = .009). Multiple regression analysis indicated preoperative ventilatory support ( P < .001), longer cardiopulmonary bypass ( P = .002), previous airway operation ( P = .01), and need for significant airway reintervention ( P < .001) as predictors of longer hospital stay. Conclusions Slide tracheoplasty with cardiopulmonary bypass can be performed with low mortality in a diverse pediatric population. This technique minimizes need for early significant airway reintervention in most cases.
Background Acute kidney injury (AKI) is common in infants after cardiopulmonary bypass and is associated with poor outcomes. Peritoneal dialysis improves outcomes in adults with AKI after bypass, but ...pediatric data are limited. This retrospective case-matched study was conducted to determine if the practice of peritoneal dialysis catheter (PDC) placement during congenital heart surgery is associated with improved clinical outcomes in infants at high risk for AKI. Methods Forty-two infants undergoing congenital heart surgery with planned PDC placement (PDC+) were age-matched to infants undergoing similar surgery without PDC placement (PDC−). Demographic, baseline and outcome data were compared. Our primary outcome was negative fluid balance on postoperative days 1 to 3. Secondary outcomes included time to negative fluid balance, time to extubation, frequency of electrolyte corrective medications, inotrope scores, and other clinical outcomes. Results Baseline data did not differ between groups. The PDC+ group had a higher percentage of negative fluid balance on postoperative days 1 and 2 (57% vs 33%, P = .04; 85% vs 61%, P = .01). The PDC+ group had shorter time to negative fluid balance (16 vs 32 hours, P < .0001), earlier extubation (80 vs 104 hours, P = .02), improved inotrope scores ( P = .04), and fewer electrolyte imbalances requiring correction ( P = .03). PDC-related complications were rare. Conclusions PDC use is safe and associated with earlier negative fluid balance and improved clinical outcomes in infants at high risk for AKI. Routine PDC use should be considered for infants undergoing cardiopulmonary bypass. Further prospective studies are essential to prove causative effects of PDC placement in this population.
Global change drivers are rapidly altering resource availability and reducing biodiversity. Here, we evaluate the extent to which biodiversity influences the response of ecosystem productivity to ...increases or decreases in resource availability across grassland experiments. This was done using data from 16 grassland experiments across North America and Europe that manipulated both plant species richness and an essential resource: soil nutrients or water. We assessed the interaction between plant diversity and resource alteration as both positive interactions with diversity, e.g. more complete utilization of additional nutrients at high plant diversity, and negative interactions, e.g. the breakdown of complementarity for limiting resources, could be expected. Despite strong increases in productivity with nutrient addition and decreases in productivity due to water reduction, we found that resource alterations did not alter the strength of diversity effects on productivity. Standardizing for absolute productivity changes revealed a consistent yet weak and non-significant trend for diversity to buffer the effects of both drought and nutrient enrichment. The immutability of diversity effects indicates that diversity will remain an important regulator of grassland ecosystem productivity, regardless of changes in other global change drivers.
When is palliation permanent? Manning, Peter B., MD
The Journal of thoracic and cardiovascular surgery,
06/2015, Letnik:
149, Številka:
6
Journal Article
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