The development of free-swimming in Xenopus laevis larvae

In Xenopus laevis frog tadpoles, highly self-motive, free-swimming behaviour emerges at the onset of feeding. This is in contrast to the earlier post-hatched larval form, which is capable of escape swimming when stimulated, but normally lies dormant. This developmental transition in behaviour has been documented here and studied in a semi-intact preparation developed to examine the motor output from larvae at the onset of filter feeding. There is a progressive increase in spontaneous motor activity during this period, where spontaneous fictive swimming occurs in episodes of variable duration but with significantly larger burst durations. This spontaneous activity persists after removal of both the fore- and midbrain, but is absent in spinalised preparations. The spontaneous activity is similar to NMDA (100µM) induced rhythm but shows greater periodic variability in the frequency and occurrence of swimming activity. The activity is not dependent on inhibitory synaptic transmission, but is under the control of central GABAergic restraint, as blocking this inhibition with bicuculine (10µM) increased spontaneous locomotor activity. This is distinct to the role of glycinergic inhibition which influences the character of the ventral root bursts, as strychnine (5µM) caused an initial increase in frequency before bursts were synchronised on both the left and right sides, but not the presence of spontaneous activity. However, activity is abolished by the persistent sodium current blocker riluzole (5µM) and enhanced by veratridine (90nM) which potentiates the current, which may suggest that it originates in neurons with pacemaker-like properties - possibly within the hindbrain. Evidence is also provided which shows that the neuromodulatory gas nitric oxide becomes an excitatory modulator of the Xenopus swimming network at the onset of a free-swimming existence, switching from having a global inhibitory role on locomotion in early larval life. The nitric oxide donor DEA/NO (200µM) increased spontaneous fictive swimming in the semi-intact preparation. In contrast, the nitric oxide synthase inhibitor L-NAME combined with PTIO, which sequesters nitric oxide, decreased spontaneous fictive swimming. It is proposed that the emergence of this rhythmic, spontaneous motor activity parallels the increase in swimming at the onset of feeding, suggesting a direct behavioural role for spontaneous network activity in the developing animal

Simple new risk score model for adult cardiac extracorporeal membrane oxygenation: simple cardiac ECMO score.

BACKGROUND: Although the use of cardiac extracorporeal membrane oxygenation (ECMO) is increasing in adult patients, the field lacks understanding of associated risk factors. While standard intensive care unit risk scores such as SAPS II (simplified acute physiology score II), SOFA (sequential organ failure assessment), and APACHE II (acute physiology and chronic health evaluation II), or disease-specific scores such as MELD (model for end-stage liver disease) and RIFLE (kidney risk, injury, failure, loss of function, ESRD) exist, they may not apply to adult cardiac ECMO patients as their risk factors differ from variables used in these scores. METHODS: Between 2010 and 2014, 73 ECMOs were performed for cardiac support at our institution. Patient demographics and survival were retrospectively analyzed. A new easily calculated score for predicting ECMO mortality was created using identified risk factors from univariate and multivariate analyses, and model discrimination was compared with other scoring systems. RESULTS: Cardiac ECMO was performed on 73 patients (47 males and 26 females) with a mean age of 48 ± 14 y. Sixty-four percent of patients (47/73) survived ECMO support. Pre-ECMO SAPS II, SOFA, APACHE II, MELD, RIFLE, PRESERVE, and ECMOnet scores, were not correlated with survival. Univariate analysis of pre-ECMO risk factors demonstrated that increased lactate, renal dysfunction, and postcardiotomy cardiogenic shock were risk factors for death. Applying these data into a new simplified cardiac ECMO score (minimal risk = 0, maximal = 5) predicted patient survival. Survivors had a lower risk score (1.8 ± 1.2) versus the nonsurvivors (3.0 ± 0.99), P \u3c 0.0001. CONCLUSIONS: Common intensive care unit or disease-specific risk scores calculated for cardiac ECMO patients did not correlate with ECMO survival, whereas a new simplified cardiac ECMO score provides survival predictability

Role of a plausible nuisance contributor in the declining obesity-mortality risks over time.

CONTEXT: Recent analyses of epidemiological data including the National Health and Nutrition Examination Survey (NHANES) have suggested that the harmful effects of obesity may have decreased over calendar time. The shifting BMI distribution over time coupled with the application of fixed broad BMI categories in these analyses could be a plausible nuisance contributor to this observed change in the obesity-associated mortality over calendar time. OBJECTIVE: To evaluate the extent to which observed temporal changes in the obesity-mortality association may be due to a shifting population distribution for body mass index (BMI), coupled with analyses based on static, broad BMI categories. DESIGN, SETTING, AND PARTICIPANTS: Simulations were conducted using data from NHANES I and III linked with mortality data. Data from NHANES I were used to fit a true model treating BMI as a continuous variable. Coefficients estimated from this model were used to simulate mortality for participants in NHANES III. Hence, the population-level association between BMI and mortality in NHANES III was fixed to be identical to the association estimated in NHANES I. Hazard ratios (HRs) for obesity categories based on BMI for NHANES III with simulated mortality data were compared to the corresponding estimated HRs from NHANES I. MAIN OUTCOME MEASURES: Change in hazard ratios for simulated data in NHANES III compared to observed estimates from NHANES I. RESULTS: On average, hazard ratios for NHANES III based on simulated mortality data were 29.3% lower than the estimates from NHANES I using observed mortality follow-up. This reduction accounted for roughly three-fourths of the apparent decrease in the obesity-mortality association observed in a previous analysis of these data. CONCLUSIONS: Some of the apparent diminution of the association between obesity and mortality may be an artifact of treating BMI as a categorical variable

Management considerations of massive hemoptysis while on extracorporeal membrane oxygenation.

BACKGROUND: Veno-arterial extracorporeal membrane oxygenation (V-A ECMO) is a life-saving procedure in patients with both respiratory and cardiac failure. Bleeding complications are common since patients must be maintained on anticoagulation. Massive hemoptysis is a rare complication of ECMO; however, it may result in death if not managed thoughtfully and expeditiously. METHODS: A retrospective chart review was performed of consecutive ECMO patients from 7/2010-8/2014 to identify episodes of massive hemoptysis. The management of and the outcomes in these patients were studied. Massive hemoptysis was defined as an inability to control bleeding (\u3e300 mL/day) from the endotracheal tube with conventional maneuvers, such as bronchoscopy with cold saline lavage, diluted epinephrine lavage and selective lung isolation. All of these episodes necessitated disconnecting the ventilator tubing and clamping the endotracheal tube, causing full airway tamponade. RESULTS: During the period of review, we identified 118 patients on ECMO and 3 (2.5%) patients had the complication of massive hemoptysis. One case was directly related to pulmonary catheter migration and the other two were spontaneous bleeding events that were propagated by antiplatelet agents. All three patients underwent bronchial artery embolization in the interventional radiology suite. Anticoagulation was held during the period of massive hemoptysis without any embolic complications. There was no recurrent bleed after appropriate intervention. All three patients were successfully separated from ECMO. CONCLUSIONS: Bleeding complications remain a major issue in patients on ECMO. Disconnection of the ventilator and clamping the endotracheal tube with full respiratory and cardiac support by V-A ECMO is safe. Early involvement of interventional radiology to embolize any potential sources of the bleed can prevent re-hemoptysis and enable continued cardiac and respiratory recovery

Massive haemoptysis on veno-arterial extracorporeal membrane oxygenation.

A 49-year old female presented with severe heart failure with end-organ dysfunction and was placed on veno-arterial extracorporeal membrane oxygenation (ECMO) as a bridge to a decision for end-organ recovery. While on ECMO, the patient developed massive haemoptysis after a Swan-Ganz catheter manipulation. The haemoptysis was not controllable by conventional methods including bronchoscopy with cold saline and epinephrine lavage, bronchial blocker or angiography. The endotracheal tube was clamped to provide tamponade and the patient relied on full ECMO support for 36 h. After the haemoptysis resolved, the endotracheal tube was unclamped. The patient developed adult respiratory distress syndrome and was ventilated using the ARDSnet protocol with continued support from ECMO. On post-ECMO day 20, the patient underwent a successful ECMO wean and a Heart Mate II left ventricular assist device placement

Tapinoma nigerrimum as safeguard for Italian myrmecofauna against Argentine ant

The Hurst effect plays an important role in many areas such as physics, climate and finance. It describes the anomalous growth of range and constrains the behavior and predictability of these systems. The Hurst effect is frequently taken to be synonymous with Long-Range Dependence (LRD) and is typically assumed to be produced by a stationary stochastic process which has infinite memory. However, infinite memory appears to be at odds with the Markovian nature of most physical laws while the stationarity assumption lacks robustness. Here we use Lorenz's paradigmatic chaotic model to show that regime behavior can also cause the Hurst effect. By giving an alternative, parsimonious, explanation using nonstationary Markovian dynamics, our results question the common belief that the Hurst effect necessarily implies a stationary infinite memory process. We also demonstrate that our results can explain atmospheric variability without the infinite memory previously thought necessary and are consistent with climate model simulations

Pay, productivity and management

Using confidential Census matched employer-employee earnings data we find that employees at more productive firms, and firms with more structured management practices, have substantially higher pay, both on average and across every percentile of the pay distribution. This pay-performance relationship is particularly strong amongst higher paid employees, with a doubling of firm productivity associated with 11% more pay for the highest-paid employee (likely the CEO) compared to 4.7% for the median worker. This pay-performance link holds in public and private firms, although it is almost twice as strong in public firms for the highest-paid employees. Top pay volatility is also strongly related to productivity and structured management, suggesting this performance-pay relationship arises from more aggressive monitoring and incentive practices for top earners