Detection of epileptic seizure in EEG signals using linear least squares preprocessing.

An epileptic seizure is a transient event of abnormal excessive neuronal discharge in the brain. This unwanted event can be obstructed by detection of electrical changes in the brain that happen before the seizure takes place. The automatic detection of seizures is necessary since the visual screening of EEG recordings is a time consuming task and requires experts to improve the diagnosis. Much of the prior research in detection of seizures has been developed based on artificial neural network, genetic programming, and wavelet transforms. Although the highest achieved accuracy for classification is 100%, there are drawbacks, such as the existence of unbalanced datasets and the lack of investigations in performances consistency. To address these, four linear least squares-based preprocessing models are proposed to extract key features of an EEG signal in order to detect seizures. The first two models are newly developed. The original signal (EEG) is approximated by a sinusoidal curve. Its amplitude is formed by a polynomial function and compared with the predeveloped spline function. Different statistical measures, namely classification accuracy, true positive and negative rates, false positive and negative rates and precision, are utilised to assess the performance of the proposed models. These metrics are derived from confusion matrices obtained from classifiers. Different classifiers are used over the original dataset and the set of extracted features. The proposed models significantly reduce the dimension of the classification problem and the computational time while the classification accuracy is improved in most cases. The first and third models are promising feature extraction methods with the classification accuracy of 100%. Logistic, LazyIB1, LazyIB5, and J48 are the best classifiers. Their true positive and negative rates are 1 while false positive and negative rates are 0 and the corresponding precision values are 1. Numerical results suggest that these models are robust and efficient for detecting epileptic seizure.

Acute haemodynamic effects of cigarette smoking in healthy young subjects.

BACKGROUND: Invasive studies in middle-aged patients suggest an acute adverse haemodynamic effect of smoking. AIMS: To study acute changes in blood pressure (BP), cardiac output, peripheral resistance and aortic compliance following cigarette smoking in healthy young subjects. METHODS: Using a non-invasive photoplethysmographic technique we compared the effects of smoking one cigarette with sham smoking in 12 healthy volunteers (22-25 years). Data was analysed using JMP version 5.0. RESULTS: In contrast to sham smoking there was a prompt increase in blood pressure with a maximum effect at 15 min (123 +/- 7/75 +/- 5 to 143 +/- 6/86 +/- 6 mmHg, mean +/- SEM, p < 0.01) which is attributed to a rise in cardiac output (p < 0.05) rather than changes in peripheral vascular resistance. There was also a significant (p < 0.05) increase in heart rate and a reduction in aortic compliance. CONCLUSION: These results suggest that healthor young age do not protect from the adverse effects of smoking.

Coordination of deglutitive vocal cord closure and oral-pharyngeal swallowing events in the elderly.

OBJECTIVE: The temporal relationship between deglutitive glottic closure, oropharyngeal bolus transit and other biomechanical swallowing events was studied in 10 healthy elderly subjects by concurrent transnasal videolaryngoscopy, videofluoroscopy, intraluminal pharyngeal manometry and submental electromyography. The results were compared with those of a similar study in a group of young healthy volunteers published previously. RESULTS: Overall, the coordination of various deglutitive biomechanical events in the elderly group was found to be similar to that in the young. However, subtle differences were documented. Contrary to historical young controls, where the onset of the bolus movement from the mouth toward the pharynx invariably occurred after the vocal cords reached their maximum adduction, in the elderly this relationship was variable. In all swallows of two subjects it occurred 0.41 +/- 0.2 s after, and in another two it occurred 0.08 +/- 0.06 s before the maximal vocal cord adduction. Six subjects showed interchanging patterns. Except for the above-mentioned changes, the onset of vocal cord adduction in the elderly also preceded all other studied events, similar to previously published data in the young. In the elderly, the total duration between onset of vocal cord adduction and their complete reopening (2.47 +/- 0.1 s) was similar to that in the young. CONCLUSION: Although subtle alterations occur in the coordination of deglutitive vocal cord closure and oropharyngeal bolus transit in some elderly people, the overall coordination between airway protection and the transit aspect of the oral-pharyngeal phase of swallowing is preserved in the elderly.

Effect of aging, position, and temperature on the threshold volume triggering pharyngeal swallows.

BACKGROUND/AIMS: Swallows triggered by direct stimulation of pharyngeal structures may help to prevent aspiration by emptying the pharynx. The aims of this study were to compare the biomechanical events of the pharyngeal and primary swallow, determine the threshold volume of liquid required to trigger the pharyngeal swallows, and determine the effect of aging, position, and temperature on this threshold volume. METHODS: Concurrent manometry, video fluoroscopy, and video endoscopy were used to study young and elderly healthy volunteers. RESULTS: During pharyngeal swallows, in contrast to primary swallows, the free portion of the tongue did not make contact with the hard palate. In addition, pharyngeal swallows did not result in oral bolus clearance. All other biomechanical events, including deglutitive glottal function, were similar in both types of swallows. The threshold volume for pharyngeal swallows in young volunteers was significantly smaller than in the elderly (P < 0.01). Temperature and position did not have significant effects on threshold volume. CONCLUSIONS: Swallowing is readily induced by water stimulation of the pharynx. Pharyngeal swallows do not induce lingual peristalsis or clearance of oral content. The threshold volume of the pharyngeal swallow is significantly higher in the elderly than in the young, but it is not affected by body position or bolus temperature.

Effect of age and bolus variables on the coordination of the glottis and upper esophageal sphincter during swallowing.

We studied 1) the effect of age and bolus variables on a) the coordination of deglutitive vocal cord adduction and upper esophageal sphincter (UES) relaxation and b) the duration of deglutitive vocal cord adduction; 2) the effect of the presence of a manometric catheter across the UES on the deglutitive glottal function; and 3) the temporal relationship between deglutitive vocal cord closure and swallow-induced apnea. We studied 10 young (23 +/- 2 yr) and 10 healthy elderly (73 +/- 2 yr) volunteers by concurrent videoendoscopy, UES manometry, respirography, and submental surface electromyography. In both groups the onset of vocal cord adduction preceded the onset of UES relaxation, deglutitive apnea, and submental electromyogram swallowing signal. In both groups, bolus volume and temperature did not have any significant effect on the duration of deglutitive vocal cord adduction. In both young and elderly volunteers, water swallows, compared with dry swallows, significantly shortened the interval between the onset of deglutitive vocal cord adduction and the onset of UES relaxation. In conclusion, coordination between deglutitive glottal and UES function, as well as the duration of deglutitive vocal cord adduction, is preserved in the elderly. Bolus volume and temperature do not have a modulatory effect on the duration of vocal cord closure, but water swallow shortens the interval between the onset of glottal closure and UES relaxation. This shortened interval may contribute to the safety of the airway during swallowing of liquid volumes.

Sodium transport in human intestinal basolateral membrane vesicles.

The current investigation was aimed at characterizing transport pathways for Na+ in basolateral membrane vesicles (BLMV) isolated from organ donor jejunum and ileum. An outward proton gradient [pH inside, 5.5; pH outside, 7.5] led to a 4-5-fold stimulation of transport rates compared with the absence of proton-gradient conditions in both human jejunal and ileal BLMV. Voltage-clamping the vesicles (K+ inside = K+ outside + valinomycin) reduced the uptake of 22Na by 20%, indicating a minor conductive component of Na+ transport. Uptake of 22Na (1 mmol/L) in voltage-clamped BLMV was inhibited 70% by 2 mmol/L amiloride. Li+ and NH4+ inhibited transport of 22Na into voltage-clamped BLMV. Transport of Na+ exhibited saturation kinetics, and the Michaelis constant (Km) and Vmax values for jejunum and ileum were similar [Km, 27 +/- 3 mmol/L (jejunum) and 18 +/- 2 mmol/L (ileum); Vmax, 19 +/- 2 nmol.mg protein-1.min-1 (jejunum) and 16 +/- 1 nmol.mg protein-1.min-1 (ileum)]. Vmax values were < 15% of those reported for brush border membrane, whereas Km values were comparable. The results show that Na+ transport in human jejunal and ileal BLMV occurs via an Na+/H+ exchanger and a minor conductive pathway.