Feature selection methods for accelerometry-based seizure detection in children

We investigate the application of feature selection methods and their influence on distinguishing nocturnal motor seizures in epileptic children from normal nocturnal movements using accelerometry signals. We studied two feature selection methods applied one after the other to reduce the complexity and computation costs of least-squares support vector machine (LS-SVM) models. Simultaneous feature selection analyses were performed for each seizure type individually and jointly. Starting from 140 features, a filter method based on mutual information was applied to remove irrelevant and redundant features. The obtained subset was further reduced through a wrapper feature selection strategy using an LS-SVM classifier with both forward search and backward elimination. The discriminative power of each feature subset was evaluated on the test data in terms of the area under the receiver operating characteristic curve, sensitivity, and false detection rate per hour. We showed that, by using only a filter method for feature selection, it was possible to obtain classification results of comparable or slightly reduced performance with respect to the complete feature set. The attained results could facilitate further development of accelerometry-based seizure detection and alarm systems.     

Carbon dioxide poisoning: a literature review of an often forgotten cause of intoxication in the emergency department

The goal of this article was to provide an overview of the literature available on carbon dioxide intoxication. Articles were included based on their focus on medical or physiological effects of carbon dioxide. Studies related to decompression sickness were excluded. Mechanisms of carbon dioxide poising (both as an asphyxiant and as a toxicant) were described. Our review suggested that precautions are needed when handling dry ice or while working in confined spaces. Pre-hospital responders also need to pay attention for the possible diagnosis of CO₂ intoxication for their own safety. When confronted with a victim, he/she should be removed from the dangerous area as fast as possible and oxygen should be administered. Without adequate treatment, victims may show acute reduced cognitive performance, respiratory failure, and circulatory arrest. Therefore, carbon dioxide poisoning is a rare but not to miss diagnosis in the emergency department.     

60 hertz magnetic field exposure assessment for an investigation of leukemia in telephone lineworkers

The purpose of this paper is to present the assessment of magnetic field exposure conducted as a part of a nested case-control investigation of leukemia mortality in telephone lineworkers. For the purposes of exposure classification, telephone company jobs were initially divided into two classes: those with potential for working in an electric environment, referred to as linework jobs, and those not working in an electric environment, referred to as nonlinework jobs. Linework jobs were further divided into the following four categories: outside plant technicians (OPT), installation/maintenance/repair (IMR) technicians, central office technicians (COT), and cable splicing technicians (CST). These job groupings were based on similarity of work tasks and exposure environments. Emdex data-logging dosimeters were used to measure personal exposures to ELF magnetic fields for 204 telephone company workers. Three general classes of exposure indices were calculated for each exposure record: measures of central tendency, measures of peak or maximum exposure, and measures of exposure variability. CSTs had the highest full-shift mean and median exposure, 4.3 and 3.2 mG, respectively. CSTs also ranked the highest, with average peak, average 95th percentile, and average time above background equal to 99.2 mG, 11.1 mG, and 156 min, respectively. In addition, the results suggest the OPT and IMR technicians have exposures similar to nonlineworkers. Exposure classifications, therefore, which misclassify all lineworkers into one “telephone lineworker” job grouping are not appropriate and future studies should concentrate on cable splicing technicians.     

Comparison of ureteral and cervical descents during vaginal hysterectomy for uterine prolapse

Objective: The study measured ureteral and cervical locations during vaginal hysterectomy for prolapse and the extent of parametrial ligament shortening possible. Study Design: Cervical and ureteral position were measured in 26 women undergoing uterine prolapse correction. Parametrial clamp tip location was also measured. Results: The cervix lay between 0 and –14.5 cm (below) the hymen (mean ± SD –5.35 ± 3.96 cm) and the ureters lay +5.0 to –4.0 cm (mean ± SD +1.89 ± 1.99 cm). Correlation of ureteral with cervical position was 0.69 (P < .01) and correlation with ipsilateral uterosacral ligament clamp positions was 0.80 (P < .01). Regression line slope relating cervical descent and cervix to ureter distance was 0.65, indicating that for every 3 cm of cervical descent there was 2 cm widening of the gap between the cervix and ureters and 1 cm descent of the ureter. Conclusion: For every 3 cm of cervical descent the ureters descend 1 cm, thereby widening the ureterocervical gap and permitting ligament shortening during vaginal hysterectomy. (Am J Obstet Gynecol 1998;179:1405-10.)     

123I-5-I-R91150, a new single-photon emission tomography ligand for 5-HT2A receptors: influence of age and gender in healthy subjects

5-HT_2A receptors have been implicated in the pathophysiology of mood disorders and in the therapeutic effect of the so-called atypical antipsychotics. Recently, a new radioiodinated ligand with high affinity and selectivity for serotonin 5-HT_2A receptors, ¹²³iodinated 4-amino-N-1-[3-(4-fluorophenoxy)propyl]-4-methyl-4-piperidinyl] 5-iodo-2-methoxybenzamide (¹²³I-5-I-R91150), has been developed and has been shown to be suitable for single-photon emission tomography (SPET) imaging. In this study the influence of age and gender on the ligand binding was investigated in normal volunteers. One hundred and fifty MBq of ¹²³I-5-I-R91150 was administered to 26 normal volunteers (13 females and 13 males) with an age range of 23–60 years. SPET imaging was performed with a triple-headed gamma camera. For semi-quantitative analysis, ratios of ligand binding in different regions of interest to the binding in the cerebellum were calculated. Mean ratios of 1.7 were obtained. No gender difference was demonstrated. 5-HT_2A binding was shown to decline with age. Over an age range of 40 years a reduction in ligand binding of 42%±7% was found. These results are in agreement with in vitro and positron emission tomography findings of a decline in 5-HT_2A receptor binding with age. The findings confirm the suitability of ¹²³I-5-I-R91150 for SPET imaging of 5-HT_2A receptors, and highlight the necessity for age-matched controls in clinical studies. Received 21 March and in revised form 18 August 1998     

Induction chemotherapy for non-small cell lung cancer with clinically evident mediastinal node metastases: the role of postoperative radiotherapy.

Survival for clinical Stage IIIa (T1-3, N2) non-small cell lung cancer is very poor because of poor local disease control and systemic spread. To address these shortcomings, we initiated a treatment program with induction chemotherapy, surgery, and postoperative radiation reserved for patients with residual disease at thoracotomy. Between 1984 and 1986, 41 patients with clinically evident N2 disease were treated with induction chemotherapy followed by resection and the selective use of intraoperative brachytherapy. All patients with tumor in the resection specimen received two cycles of chemotherapy and 15 patients received radiation therapy. With a median follow-up of 5.4 years, overall survival is 27% at 3 years, and 12% at 5 years. Despite the adverse selection process median survival is 19 months for patients receiving postoperative radiation therapy, and 22 months for the more favorable patients not requiring radiation therapy, supporting the selective use of postoperative radiation in this setting. In summary, this treatment has yielded good median survival and long-term survival for some of the patients. However, the ultimate value of this approach can only be determined by prospective trials which compare it to standard therapy.