Spatio-Temporal EEG Models for Brain Interfaces.

Multichannel electroencephalography (EEG) is widely used in non-invasive brain computer interfaces (BCIs) for user intent inference. EEG can be assumed to be a Gaussian process with unknown mean and autocovariance, and the estimation of parameters is required for BCI inference. However, the relatively high dimensionality of the EEG feature vectors with respect to the number of labeled observations lead to rank deficient covariance matrix estimates. In this manuscript, to overcome ill-conditioned covariance estimation, we propose a structure for the covariance matrices of the multichannel EEG signals. Specifically, we assume that these covariances can be modeled as a Kronecker product of temporal and spatial covariances. Our results over the experimental data collected from the users of a letter-by-letter typing BCI show that with less number of parameter estimations, the system can achieve higher classification accuracies compared to a method that uses full unstructured covariance estimation. Moreover, in order to illustrate that the proposed Kronecker product structure could enable shortening the BCI calibration data collection sessions, using Cramer-Rao bound analysis on simulated data, we demonstrate that a model with structured covariance matrices will achieve the same estimation error as a model with no covariance structure using fewer labeled EEG observations.

Assessing subsets of analytes in context of detecting laboratory errors.

Laboratory error detection is a hard task yet plays an important role in efficient care of the patients. Quality controls are inadequate in detecting pre-analytic errors and are not frequent enough. Hence population- and patient-based detectors are developed. However, it is not clear what set of analytes leads to the most efficient error detectors. Here, we use three different scoring functions that can be used in detecting errors, to rank a set of analytes in terms of their strength in distinguishing erroneous measurements. We also observe that using evaluations of larger subsets of analytes in our analysis does not necessarily lead to a more accurate error detector. In our data set obtained from renal kidney disease inpatients, calcium, potassium, and sodium, emerged as the top-3 indicators of an erroneous measurement. Using the joint likelihood of these three analytes, we obtain an estimated AUC of 0.73 in error detection.

Anterior sacral meningocele in a patient with currarino syndrome as a cause of ileus.

Currarino's syndrome (CS) is characterized by a triad of a sacral bony defect, anorectal malformations and presacral mass, most commonly an anterior sacral meningocele. Since it was first described as a syndrome by Currarino et al. in 1981, approximately 300 cases have been reported in the literature. Diagnosis of CS in adulthood is rare. We present an adult patient with CS, manifesting by an acute intestinal obstruction. To our knowledge, acute intestinal obstruction in an adult as a presentation of CS has not been reported previously. Colostomy was performed first by the general surgery team to relieve intestinal obstruction caused by the giant cyst. After the final diagnosis of anterior sacral meningocele was established, a second operation was performed for the ligation of the cyst neck through a posterior approach. The size of the cyst gradually reduced over time. A staged approach and the multidisciplinary management, with the collaboration of the general surgery and neurosurgery teams, provided a satisfactory clinical outcome.

An underappreciated problem in renal transplant recipients: anemia.

PURPOSE: Posttransplant anemia (PTA) is associated with a higher risk of cardiac mortality, which is the most frequent cause of death among renal transplant recipients. In this study, we sought to determine the prevalence and causes of PTA among Turkish patients. PATIENTS AND METHODS: The study included 75 (52 male, 23 female) adults. Anemia was defined as an hemoglobin (Hb) level < or = 13 g/dL for men and < or = 12 g/dL for women. RESULTS: The prevalence of PTA was 49.3% at a mean duration of 60.45 months after renal transplantation. The most frequent causes of PTA were erythropoietin (EPO) and iron deficiency. The mean Hb level of 12.76 +/- 2.31 g/dL was significantly higher in male compared to female patients (13.26 +/- 2.31 g/dL vs 11.64 +/- 1.93 g/dL, P = .005). The Hb value was positively correlated with creatinine clearance and serum albumin level, and negatively correlated with serum creatinine level, the amount of proteinuria, and cyclosporine level. Creatinine clearance and serum albumin level were found to be an independent risk factors for PTA upon multivariate analysis. Only 12 of 37 anemic patients received treatment for anemia: 5 (13.5%) with EPO and 7 (18.9%) with iron preparations. CONCLUSION: PTA a common complication was unfortunately neglected in this setting. Impaired renal allograft function and decreased serum albumin were major risk factors for PTA. Increased cyclosporine levels were also correlated with decreased Hb concentrations.