Electroencephalography (EEG) is electrical brain activity that can be measured on the scalp with Ag/AgCl electrodes and conductive gel. However, time‐consuming preparation procedures, dehydration of the gel, and skin irritation are crucial drawbacks of using such electrodes. Alternative approaches involving the use of spiky dry electrodes have their own drawbacks such as limited skin–electrode contact area, high skin–electrode impedance, and pain. Reverse‐curve‐arch‐shaped dry EEG electrodes for use in increasing the skin–electrode contact area on hairy scalps are presented. The proposed electrode was fabricated from sterling silver using a three‐dimensional printer. To increase the contact area between the skin and an electrode, an electrode was designed to have reverse‐curve arches which were arranged in a row on the electrode base. The curvature of the arches was designed to match the curvature of the scalp to maximise the contact area and disperse the pressing force. To validate the proposed electrode design, comparison experiments for EEG and skin–electrode contact impedance were conducted, and the proposed electrode was found to perform better than a commercially available finger‐type dry electrode.

We established and tested a snoring detection method using a polyvinylidene fluoride (PVDF) sensor for accurate, fast, and motion-artifact-robust monitoring of snoring events during sleep. Twenty patients with obstructive sleep apnea participated in this study. The PVDF sensor was located between a mattress cover and mattress, and the patients' snoring signals were unconstrainedly measured with the sensor during polysomnography. The power ratio and peak frequency from the short-time Fourier transform were used to extract spectral features from the PVDF data. A support vector machine was applied to the spectral features to classify the data into either the snore or non-snore class. The performance of the method was assessed using manual labelling by three human observers as a reference. For event-by-event snoring detection, PVDF data that contained 'snoring' (SN), 'snoring with movement' (SM), and 'normal breathing' epochs were selected for each subject. As a result, the overall sensitivity and the positive predictive values were 94.6% and 97.5%, respectively, and there was no significant difference between the SN and SM results. The proposed method can be applied in both residential and ambulatory snoring monitoring systems.

A 67-year-old man underwent two endoscopic submucosal dissection procedures, one for gastric adenoma and one for early gastric cancer. The follow-up endoscopy showed metachronous recurrence at the anterior wall of the lower body, for which he underwent a subtotal gastrectomy. Four first-or second-degree relatives in his family have been diagnosed with gastric or colon cancers. The patient underwent counseling and genetic testing to identify single nucleotide polymorphisms and indel variants for 31 genes by next generation sequencing. Five missense mutations were identified, one each in ATM, BRIP1, and EPCAM and two in BRCA2. These genetic alterations may be candidates for genetic causes of this familial cluster of gastric cancer. This study identified genes that, for the first time, can be potentially associated with an increased risk of familial gastric cancer among the Korean population.

No abstract

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. A 77-year-old man was referred for the evaluation of general weakness and leukocytosis. Computed tomography showed a 9.5×6.5-cm cavitary lesion with an air-fluid level near the stomach, which was thought to be a perigastric abscess. Upper endoscopy revealed a fistula on the greater curvature at the mid body of the stomach. The margin of the fistula opening was clearly demarcated, and yellow turbid fluid oozing from the fistula was seen. Laparoscopic wedge resection was performed at the perforated area of the stomach.