Upper limit to magnetism in LaAlO3/SrTiO3 heterostructures

Using polarized neutron reflectometry we measured the neutron spin-dependent reflectivity from four LaAlO(3)/SrTiO(3) superlattices. Our results imply that the upper limit for the magnetization averaged over the lateral dimensions of the sample induced by an 11 T magnetic field at 1.7 K is less than 2 G. SQUID magnetometry of the neutron superlattice samples sporadically finds an enhanced moment, possibly due to experimental artifacts. These observations set important restrictions on theories which imply a strongly enhanced magnetism at the interface between LaAlO(3) and SrTiO(3).

Electronic and magnetic reconstructions in La0.7Sr0.3MnO3/SrTiO3 heterostructures: a case of enhanced interlayer coupling controlled by the interface

We report on the magnetic coupling of La0.7Sr0.3MnO3 layers through SrTiO3 spacers in La0.7Sr0.3MnO3/SrTiO3 epitaxial heterostructures. Combined aberration-corrected microscopy and electron-energy-loss spectroscopy evidence charge transfer to the empty conduction band of the titanate. Ti d electrons interact via superexchange with Mn, giving rise to a Ti magnetic moment as demonstrated by x-ray magnetic circular dichroism. This induced magnetic moment in the SrTiO3 controls the bulk magnetic and transport properties of the superlattices when the titanate layer thickness is below 1 nm.

Preoperative Estimated Glomerular Filtration Rate and RIFLE-Classified Postoperative Acute Kidney Injury Predict Length of Stay Post-Coronary Bypass Surgery in an Australian Setting

We investigated the influence of preoperative estimated glomerular filtration rate and postoperative acute kidney injury on outcomes after coronary bypass surgery in a local setting, with the focus on length of stay.

A retrospective analysis of prospectively collected data for 3302 consecutive patients who underwent coronary artery bypass graft surgery (June 1997 through to January 2007) at St Vincent's Public Hospital, Melbourne, was undertaken. Preoperative estimated glomerular filtration rate was calculated and categorised using US National Kidney Foundation cut-offs for chronic kidney disease (normal function; mild, moderate and severe dysfunction). Postoperative acute kidney injury was categorised using serum creatinine RIFLE criteria (no acute kidney injury, risk, injury and failure). Postoperative intensive care and hospital length of stay was determined.

The hazard ratios for time to hospital discharge up to one month decreased (indicating a longer length of stay) as severity of preoperative renal dysfunction category increased when compared to those with normal renal function: mild hazard ratio=1.02 (95% confidence interval: 0.91 to 1.15, P=0.70), moderate 0.87 (0.76 to 1.00, P=0.047), severe 0.47 (0.35 to 0.64, P < 0.001). Hazard ratios also decreased as severity of postoperative acute kidney injury category increased, when compared to those with no acute kidney injury: risk 0.67 (0.58 to 0.77, P <0.001), injury 0.52 (0.41 to 0.65, P <0.001), failure 0.35 (0.20 to 0.60, P <0.001).

The increasing severity of preoperative renal dysfunction and postoperative acute kidney injury were associated with increased hospital length of stay. This has implications for resource use, informed consent and case selection.

Validation of the hospital outcome prediction equation (HOPE) model for monitoring clinical performance

BACKGROUND

The aim of this study was to validate a risk-adjusted hospital outcome prediction equation (HOPE) using a statewide administrative dataset.

METHODS

Retrospective observational study using multivariate logistic regression modelling. Calibration and discrimination were assessed by standardized mortality ratio (SMR), area under the receiver operating characteristic plot (ROC AUC), Hosmer-Lemeshow contingency tables and goodness-of-fit statistic in an independent dataset, and in all 23 important tertiary, metropolitan and regional hospitals. The dependent variable was in-hospital death. All consecutive adult hospital separations between 1 July 2004 and 30 June 2006, excluding obstetric and day-case only admissions, from all acute health services within the State of Victoria, Australia were included.

RESULTS

A total of 379 676 consecutive records (1 July 2004 to 30 June 2005) was used to derive the HOPE model. Six variables (age, male sex, admission diagnosis, emergency admission, aged-care resident and inter-hospital transfer) were selected for inclusion in the final model. It was validated in the 384 489 consecutive records from the following year (1 July 2005 to 30 June 2006). The 95% confidence interval for the SMR was 0.98-1.02, and for the ROC AUC, 0.87-0.88. Discrimination and (one or more) calibration criteria were achieved in 22 (96%) of the 23 hospitals.

CONCLUSION

The HOPE model is a simple risk-adjusted outcome prediction tool, based on six variables from data that are routinely collected for administrative purposes and appears to be a reliable predictor of hospital outcome.

Pathological description of a non-motor variant of multiple system atrophy

Multiple system atrophy (MSA) is a neurodegenerative disorder that usually presents clinically as a combination of parkinsonism, cerebellar syndrome and autonomic failure. Patients with MSA can present other clinical features, such as inspiratory stridor and rapid eye movement (REM) sleep behaviour disorder (RBD). We report a patient with pathologically confirmed MSA who presented with a longstanding history of stridor, RBD and autonomic disturbances but did not develop overt parkinsonism or cerebellar signs. This case illustrates that MSA may present clinically without its cardinal motor symptoms, and that stridor and RBD may be clues to recognise the disease in a patient with autonomic failure.

Report of an EFNS task force on management of sleep disorders in neurologic disease (degenerative neurologic disorders and stroke)

A task force to develop guidelines for diagnostic evaluation and treatment of sleep disorders in degenerative neurologic disorders and stroke was initiated by the European Federation of Neurological Societies (EFNS). The aims were to provide evidence-based recommendations in the management of sleep disorders associated with degenerative neurologic disorders and stroke. Neurological patients often have significant sleep disorders like sleep-related breathing disorders (SBD), insomnia, sleep-related motor and rapid eye movement behavioral disorders affecting nocturnal sleep and daytime function. A polysomnography (PSG) is usually a diagnostic minimum for the diagnoses of the most commonly reported sleep disorders in patients with neurologic diseases. A full video-PSG/video-EEG-PSG should be considered in patients with nocturnal motor and/behavior manifestations. Respiratory polygraphy has a moderate sensitivity and specificity in the diagnosis of SBD without neurologic diseases, but its value in patients with neurologic diseases has not been evaluated. Oximetry has a poor sensitivity-specificity for the identification of SDB. Continuous and bi-level positive airway pressure devices are the most effective treatment of SDB in patients with neurologic diseases. There is a need for further studies focusing on the diagnostic procedures and treatment modalities in patients with sleep disorders and degenerative neurologic diseases and stroke.

Early and late results of combined mitral-aortic valve surgery

OBJECTIVE

This retrospective study was designed to assess the early morbidity and mortality as well as long-term mortality of combined aortic-mitral valve procedures at a single centre.

METHODS

Patients were identified by analysing the intensive care and perfusion databases, from 1989 to 2003, with 113 receiving aortic-mitral valve procedures. Eighty-four percent of patients received a mechanical bileaflet valve. Survival was assessed using a Kaplan-Meier method, and determinants of survival with the Cox proportional hazards model.

RESULTS

There were 57 men and 56 women, median age 59 (18-84) years. The 30-day mortality was 9% (n=10). This cohort contained a number of high risk patients, 38% were classified as New York Heart Association class IV, 33.5% had at least moderate ventricular impairment, 20% were redo procedures and 17% urgent procedures. Survival estimates at 5 and 10 years were 85% (0.76-0.90) and 65% (0.49-0.77), respectively. Multivariate pre-operative predictors of death included renal dysfunction (creatinine >200 micromol/L) and hypertension. Rheumatic aetiology was associated with improved survival.

CONCLUSION

This study shows acceptable short and long-term survival in patients undergoing combined aortic-mitral valve surgical procedures at a single centre. Renal impairment and hypertension were associated with a poorer long-term prognosis and rheumatic aetiology was associated with improved survival. Age, LVEF and NYHA class were not associated with a worse outcome. This may affect future decision making in light of an aging population.

Prevalence of restless legs syndrome and REM sleep behavior disorder in multiple sclerosis

A total of 135 consecutive, unrelated, multiple sclerosis (MS) patients were interviewed for symptoms suggestive of restless legs syndrome (RLS) and REM sleep behavior disorder (RBD), using semi-structured questionnaires. Some 118 unrelated healthy controls of similar sex and age distribution were included for comparison. Patients and controls with equivocal symptoms were re-evaluated by a sleep disorders specialist and video-polisomnography in those who fulfilled the criteria for RBD. We did not find significant differences in frequency (13.3 versus 9.3%), proportion of females (66.7 versus 58.5%), and mean age (42.1±12.6 versus 43±7.8 years) among MS patients and controls with RLS. RBD was found in three patients (1.4%), one associated with antidepressant intake, but in none of the controls. Our study shows that RLS in MS is not more frequent than in the general population, and that RBD, although uncommon, may occur in the setting of this neurological disease. Multiple Sclerosis 2007; 13: 805-808. http://msj.sagepub.com

Interfacially controlled transient photoinduced superconductivity

We report on a large transient photoinduced enhancement of the superconducting critical temperature (DeltaTc = 23 K) in epitaxial YBa2Cu3O(6.7)/La(0.7)Ca(0.3)MnO3 bilayers upon visible light illumination. The effect relaxes with a characteristic time of 100 s at low temperatures, which is 4 orders of magnitude faster than the persistent photoconductivity or persistent photoinduced superconductivity previously found in single high-Tc superconducting films. This result is discussed in terms of light induced charge transfer through the interface similar to what happens in semiconductor junctions.