Magneto-Responsive Actuating Surfaces with Controlled Wettability and Optical Transmittance.

The wettability of surfaces can be manipulated using actuating micro/nanostructures, as in the manipulation of water droplets with magnetic forces. Controlling water droplets with magneto-responsive surfaces is limited to optical applications, however, because these surfaces are normally opaque. Herein, we introduce a magneto-responsive actuating surface that is capable of controlling not only the wettability but also the optical transmittance. The magneto-responsive actuating surface is fabricated using a composite of iron particles with polydimethylsiloxane (PDMS). Thanks to the elastic properties of PDMS, fabricated microstructures' bending is induced by applying magnetic force. Therefore, the static/dynamic water contact angle and the optical transmittance can be controlled. Furthermore, as a feasible application, a sliding angle control system that depends on the magnet location is implemented. On the basis of the interesting characteristics of not only wettability but also optical transmittance, this study is expected to be widely used in various fields such as optics, surface self-cleaning systems of solar cells, and smart windows.

Fabrication and Performance Evaluation of the Helmholtz Resonator Inspired Acoustic Absorber Using Various Materials.

A soundwave is transmitted by adjacent molecules in the medium, and depending on the type of sound, it exhibits various characteristics such as frequency, sound pressure, etc. If the acoustic wavelength of the soundwave is sufficiently long compared with the size of an acoustic element, physical analysis within the sound element could be simplified regardless of the shape of the acoustic element: this is called "long wavelength approximation". A Helmholtz resonator, a representative acoustic element which satisfies the "long wavelength theory", consists of a neck part and a cavity part. The Helmholtz resonators can absorb certain frequencies of sound through resonance. To exhibit attenuation properties at ultrasound range, the Helmholtz resonator should be made into a microscale since Helmholtz resonators should satisfy the "long wavelength approximation". In this study, Helmholtz resonator inspired acoustic elements were fabricated using MEMS technology, and acoustic attenuation experiments in a water bath were conducted using various shapes and materials. As a result, the fabricated samples showed admirable attenuation properties up to ~13 dB mm-1 at 1 MHz. The results were analyzed to derive the necessary conditions for the fabrication of acoustic elements with acoustic attenuation properties in ultrasound range.

Remora-Inspired Reversible Adhesive for Underwater Applications.

The remoras are marine species that can effectively move by clinging onto other marine species via a suction disk on their dorsal side, which is composed of complex structures. The inner suction disk could be divided into three large parts, namely, lip, lamella, and spinule. The lamella is deformed actively to generate pressure difference between the inside and outside of the suction disk, and the lip maintains the sealing. The spinule, which is composed of hairs with diameter of 300 µm or less hair, enhances the frictional force. In this study, we easily fabricated polymer-based adhesive inspired by the suction disk of the remora and conducted an experiment to determine its performance. The adhesive exhibited admirable performance with a 26.68 N cm-2 (266.8 kPa) pull-off strength and a 19.42 N cm-2 (194.2 kPa) shear strength in water. The durability test result indicated that the adhesion and friction characteristics of the adhesive were well maintained even after multiple uses.

Highly flexible and self-adaptive dry adhesive end-effectors for precision robotics.

Many research groups have studied biomimetic functional surfaces for practical applications. Dry adhesives inspired by the gecko foot consist of hierarchical and numerous micro/nano hairs and can achieve pull-off strengths for vertical and shear adhesion of up to 20 N cm-2. However, when detachment of the nearly dry adhesive is carried out by peeling, the pull-off strength of the dry adhesive in the tilted state is remarkably reduced. In this study, an enhanced pull-off strength dry adhesive in the tilted state was fabricated by using a strategy that reduces the restoring force from the bending moment. An experiment with various column-type dry adhesives was implemented to find the relation between the pull-off strength in the tilted state and the bending resistance of the dry adhesive. The feasibility of using a dry adhesive in the tilted state was observed through a glass-lifting experiment. This strategy could be widely utilized in many practical applications, such as robotics.

Scalable and continuous fabrication of bio-inspired dry adhesives with a thermosetting polymer.

Many research groups have developed unique micro/nano-structured dry adhesives by mimicking the foot of the gecko with the use of molding methods. Through these previous works, polydimethylsiloxane (PDMS) has been developed and become the most commonly used material for making artificial dry adhesives. The material properties of PDMS are well suited for making dry adhesives, such as conformal contacts with almost zero preload, low elastic moduli for stickiness, and easy cleaning with low surface energy. From a performance point of view, dry adhesives made with PDMS can be highly advantageous but are limited by its low productivity, as production takes an average of approximately two hours. Given the low productivity of PDMS, some research groups have developed dry adhesives using UV-curable materials, which are capable of continuous roll-to-roll production processes. However, UV-curable materials were too rigid to produce good adhesion. Thus, we established a PDMS continuous-production system to achieve good productivity and adhesion performance. We designed a thermal roll-imprinting lithography (TRL) system for the continuous production of PDMS microstructures by shortening the curing time by controlling the curing temperature (the production speed is up to 150 mm min-1). Dry adhesives composed of PDMS were fabricated continuously via the TRL system.

Successful Use of Therapeutic Hypothermia for Refractory Nonconvulsive Status Epilepticus.

Therapeutic hypothermia (TH) has rarely been utilized as an adjunct to anticonvulsants in treating patients with refractory convulsive status epilepticus (CSE). However, determining the effectiveness of TH in CSE is difficult due to the unavoidable use of sedative drugs to manage hypothermia. Additionally, the effectiveness of TH has not been studied in patients with refractory non-convulsive status epilepticus (NCSE). Here, we report the successful use of TH without additional sedative drugs in a patient with temporal lobe epilepsy and refractory NCSE. A 46-year-old man was referred to the neurology department because of recurrent seizure attacks. Electroencephalography (EEG) after first-line status treatment showed continuous periodic discharges consistent with NCSE. He was started simultaneously on continuous EEG monitoring and TH, but was not administered any benzodiazepines to control shivering or maintain TH. During TH, EEG abnormalities gradually improved, and the patient regained consciousness in accordance with the improvement in EEG. The patient was alert and his EEG had normalized a few days after starting TH. To the best of our knowledge, this is the first report describing the successful treatment of refractory NCSE with TH. As no sedative drugs were used during the maintenance of hypothermia, NCSE control may have been achieved by TH alone.

Prognostic Value of Initial Standard EEG and MRI in Patients with Herpes Simplex Encephalitis.

BACKGROUND AND PURPOSE: Herpes simplex encephalitis (HSE) is the most common type of sporadic encephalitis worldwide, and it remains fatal even when optimal antiviral therapy is applied. There is only a weak consensus on the clinical outcomes and prognostic factors in patients with HSE. This study examined whether the radiological and electrophysiological findings have a prognostic value in patients with HSE. METHODS: We retrospectively analyzed patients who were diagnosed with HSE by applying the polymerase chain reaction to cerebrospinal fluid and who received intravenous acyclovir at our hospital from 2000 to 2014. We evaluated the clinical outcomes at 6 months after onset and their correlations with initial and clinical findings, including the volume of lesions on MRI, the severity of EEG findings, and the presence of epileptic seizures at the initial presentation. RESULTS: Twenty-nine patients were enrolled (18 men and 11 women). Univariate analysis revealed that the presence of severe EEG abnormality and epileptic seizures at the initial presentation were significant correlated with a poor clinical outcome at 6 months (p=0.005 and p=0.009, respectively). In multivariate analysis, the presence of severe EEG abnormality was the only independent predictor of a poor outcome at 6 months (p=0.006). CONCLUSIONS: In cases of HSE, the initial EEG severity and seizure presentation may be useful predictive factors for the outcome at 6 months after acyclovir treatment.

Prediction of mortality and functional outcome from status epilepticus and independent external validation of STESS and EMSE scores.

BACKGROUND: Two clinical scoring systems, the status epilepticus severity score (STESS) and the epidemiology-based mortality score in status epilepticus (EMSE), are used to predict mortality in patients with status epilepticus (SE). The aim of this study was to compare the outcome-prediction function of the two scoring systems regarding in-hospital mortality using a multicenter large cohort of adult patients with SE. Moreover, we studied the potential role of these two scoring systems in predicting the functional outcome in patients with SE. METHODS: The SE cohort consisted of patients from the epilepsy centers of eight academic tertiary medical centers in South Korea. The clinical and electroencephalography data for all adult patients with SE from January 2013 to December 2014 were derived from a prospective SE database. The primary outcome variable was defined as in-hospital death. The secondary outcome variable was defined as a poor functional outcome, i.e., a score of 1-3 on the Glasgow Outcome Scale, at discharge. RESULTS: Among the 120 non-hypoxic patients with SE recruited into the study, 16 (13.3%) died in the hospital and 64 (53.3%) were discharged with a poor functional outcome. The receiver-operating characteristic (ROC) curve for prediction of in-hospital death based on the STESS had an area under the curve of 0.673 with an optimal cutoff value for discrimination (best match for both sensitivity (0.56) and specificity (0.70)) that was ≥ 4 points. The two combinations of elements of the EMSE system (EMSE-ALDEg and EMSE-ECLEg) predicted not only in-hospital mortality with the best match for sensitivity (more than 0.6) and specificity (more than 0.6), but also a poor functional outcome with the best match for both sensitivity (>0.7) and specificity (>0.6). STESS did not predict a poor functional outcome (area under the ROC, 0.581; P = 0.23). CONCLUSION: Although the EMSE is a clinical scoring system that focuses on individual mortality, we did not find differences between the EMSE and STESS in the prediction of in-hospital death. The EMSE was useful in predicting poor functional outcome, as it was significantly better than STESS.

Change of Patient Selection Strategy and Improved Surgical Outcome in MRI-negative Neocortical Epilepsy.

BACKGROUND AND PURPOSE: It is crucial to make selection strategy to identify surgical candidates among medically refractory MRI-negative neocortical epilepsy patients. In our previous study, we suggested two or more concordance between noninvasive studies (EEG, ictal scalp EEG, interictal FDG-PET, and SPECT) as a new patient selection strategy for MRI-negative neocortical epilepsy surgery. The objective of this study was to evaluate the surgical outcomes of MRI-negative neocortical epilepsy patients before and after the implementation of a new selection strategy. METHODS: From 1995 to 2011, we included 153 consecutive MRI-negative neocortical epilepsy patients who received focal resection and had a follow-up period of at least 2 years. These patients were divided into two groups according to their date of surgery (before and after July 2002). The old group consisted of 89 patients and the new one consisted of 53 patients. Clinical characteristics, presurgical evaluations, and pathology were reviewed. RESULTS: The new patient selection strategy led to a significant increase in the concordance between two or more modalities. The improvement in surgical outcome after 2002 was significant (seizure-free outcome, 47.2% vs. 75.5%; p = 0.001). Concordance between two or more presurgical evaluations and localizing PET were related to a seizure-free outcome in a multivariate analysis. CONCLUSIONS: After a change in surgical strategy to select patients with two or more concordance between noninvasive studies, the seizure-free outcome improved up to 75.5%. MRI-negative neocortical epilepsy patients with two or more concordance between noninvasive studies seem to be good candidates for epilepsy surgery.

CADASIL Initially Presented with a Seizure.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a hereditary disease of the cerebral small blood vessels characterized by recurrent ischemic strokes, migraine, and progressive cognitive impairment. In patients with CADASIL, in whom subcortical white matter structures are typically involved, epileptic seizures have been rarely reported as an initial clinical symptom. We describe a patient genetically confirmed as having CADASIL who initially presented with a seizure.

A Case of Hyperventilation Syndrome Mimicking Complex Partial Seizure: Usefulness of EEG Monitoring in Emergency Department.

Acute hyperventilation syndrome not only can be clinically misdiagnosed as epileptic seizures, but also complex partial seizures may involve hyperventilation as a part of aura. Although electrography (EEG) monitoring is one of the most important procedure to differentiate these conditions, it could not be widely used in emergency department. Variety forms of epileptic attack, mainly idiopathic generalized epilepsy, are provoked by voluntary hyperventilation. In contrast, it is not clear whether hyperventilation can activate the partial seizures. We reported a case of acute hyperventilation syndrome (HSV) mimicking first onset complex partial seizure, impending non-convulsive status epilepticus, which was diagnosed by EEG in the emergency department. The electrographic seizure was provoked again by voluntary hyperventilation after clinical improvement.

Induction of burst suppression or coma using intravenous anesthetics in refractory status epilepticus.

General anesthetic-induced coma therapy has been recommended for the treatment of refractory status epilepticus (RSE). However, the influence of electroencephalographic (EEG) burst suppression (BS) on outcomes still remains unclear. This study investigated the impact of intravenous anesthetic-induced BS on the prognosis of RSE using a retrospective analysis of all consecutive adult patients who received intravenous anesthetic treatment for RSE at the Seoul National University Hospital between January 2006 and June 2011. Twenty-two of the 111 episodes of RSE were enrolled in this study. Of the 22 RSE patients, 12 (54.5%) were women and 18 (81.4%) exhibited generalized convulsive status epilepticus. Sixteen patients (72.7%) were classified as having acute symptomatic etiology, including three patients with anoxic encephalopathy, and others with remote symptomatic etiology. Only two patients (9.1%) had a favorable Status Epilepticus Severity Score (0-2) at admission. All patients received midazolam (MDZ) as a primary intravenous anesthetic drug for RSE treatment; three (13.6%) received MDZ and propofol, and one (4.5%) received MDZ and pentobarbital. The rates of mortality and poor outcome at discharge were 13.6% (n=3) and 54.5% (n=12), respectively. While BS was achieved in six (27.5%) patients, it was not associated with mortality or poor outcome. Induced BS was associated with prolonged hospital stay in subgroup analysis when excluding anoxic encephalopathy. Our results suggest that induction of BS for treating RSE did not affect mortality or outcome at discharge and may lead to an increased length of hospital stay.

Etiology and prognosis of non-convulsive status epilepticus.

Although non-convulsive status epilepticus (NCSE) is an important type of epilepsy, it is not often recognized. In order to analyze the clinical characteristics and outcome in patients with NCSE, we examined the medical records of patients with NCSE admitted to the Seoul National University Hospital between June 2005 and October 2008. The clinical details and electroencephalography records of 34 adult NCSE patients (aged over 16 years) were collected. Their mean age was 47 years (standard deviation 20 years, range, 16-87 years), and 20 were female. Twenty-seven patients (79.4%) showed decreased awareness with acute onset, and seven (20.6%) were obtunded or comatose. Ten patients (29.4%) had a history of epilepsy, and four (11.8%) had a history of stroke. NCSE was etiologically attributed to acute medical or neurological problems in 25 patients (73.5%), was cryptogenic in three (8.8%), and was secondary to underlying epilepsy in six (17.7%). Acute symptomatic etiology was associated with poor recovery (p=0.048), with all unresponsive patients in this acute symptomatic group. Eight (23.5%) of the 34 NCSE patients did not recover or died, whereas nine (26.5%) recovered. Our study shows that the presence of acute symptoms or central nervous system infection is associated with poor outcome, suggesting that a high level of vigilance is required to identify and prevent complications.

Frequency of and risk factors for oxcarbazepine-induced severe and symptomatic hyponatremia.

PURPOSE: Hyponatremia is one of the most common adverse effects in patients treated with oxcarbazepine (OXC). Most patients with OXC-induced hyponatremia are asymptomatic, so the presence of severe or symptomatic hyponatremia, which requires electrolyte correction or discontinuation of OXC therapy, has more important clinically implications. However, data for OXC-induced severe and symptomatic hyponatremia are limited. METHODS: We reviewed medical records of all patients with epilepsy who were treated with OXC at the Seoul National University Hospital. We analyzed serum sodium level results and attempted to identify correlations between various factors and the frequency of severe and symptomatic OXC-induced hyponatremia. RESULTS: Data from a total 1009 patient were examined. The frequency of severe and symptomatic hyponatremia was 11.1% and 6.8%, respectively. Multivariate analysis revealed that age (P=0.014, OR 1.014), antiepileptic drug (AED) polytherapy (P=0.040, OR 1.540), and the concomitant use of diuretics (P<0.001, OR 5.597) were independent risk factors for OXC-induced severe hyponatremia. Age (P=0.001, OR 1.034) and the concomitant use of diuretics (P=0.035, OR 2.222) were independent risk factors for OXC-induced symptomatic hyponatremia. The frequency of OXC-induced symptomatic hyponatremia that was judged to be clinically significant was 2.8% among the total OXC-treated epilepsy patients. CONCLUSION: Our study recommended that serum sodium be monitored regularly in patients taking OXC, especially in old age, AED polytherapy or concomitant use of diuretics, to assist in the early recognition of hyponatremia and to increase the awareness of symptoms that might be attributable to this.

The validity and reliability of characterizing epilepsy based on an external review of medical records.

OBJECTIVES: Our goal is to validate diagnosing and characterizing epilepsy based on a medical record survey by external reviewers. METHODS: We reviewed medical records from 80 patients who received antiepileptic drugs in 2009 at two hospitals. The study consisted of two steps; data abstraction by certified health record administrators and then verification by the investigators. The gold standard was the results of the survey performed by the epileptologists from their own hospital. RESULTS: The specificity was more than 90.0% for diagnosis and activity, and for new-onset seizures. The sensitivity was 97.0% or more for diagnosis and activity and 66.7-75.0% for new-onset epilepsy. This method accurately classified epileptic syndromes in 90.2-92.9% of patients, causes in 85.4-92.7%, and age of onset in 78.0-81.0%. Kappa statistics for inter-rater reliability and test-retest reliability ranged from 0.641-0.975, which means substantial to near-perfect agreement in all items. CONCLUSIONS: Our data suggest that epilepsy can be well identified by external review of medical records. This method may be useful as a basis for large-scale epidemiological research.

The long-term efficacy and safety of levetiracetam in a tertiary epilepsy centre.

AIM: To evaluate the long-term efficacy and safety of levetiracetam based on a large population of patients in a tertiary epilepsy centre. METHODS: All patients who received levetiracetam at the Seoul National University Hospital between January 2007 and March 2009 were evaluated. Patients who underwent brain surgery for seizure control or who had associated progressive disease were excluded from this study. The electronic medical records of these patients were reviewed retrospectively. RESULTS: A total of 568 patients were recruited, including 124 patients with generalised epilepsy. The mean duration of the follow-up period was 29.3 months. The seizure-free rate was 33.6% and was higher in patients with generalised epilepsy (51.6%) than patients with localisation-related epilepsy (28.6%). There was a strong correlation between initial response and dose-up response in 351 patients with increased dosage during the follow-up period. A total of 486 adverse events developed in 316 patients. The most common adverse event (24.3%) was irritability, which was associated with a high rate of drug discontinuation. Previous history of mood disorder was the only factor related to the development of irritability in patients using this medication. CONCLUSION: Levetiracetam was effective and safe as monotherapy and add-on therapy for partial and generalised epilepsy. The initial response to levetiracetam may provide useful information for predicting the response to increased dose of levetiracetam. However, the use of this medication was associated with a rate of irritability that was higher than expected in patients with a history of mood disorders.

An assessment of a new navigatable percutaneous disc decompression device (l'DISQ) through histologic evaluation and thermo-mapping in human cadaveric discs.

STUDY DESIGN: This is an in vitro experimental study of the technical capability and safety study of a navigable percutaneous disc decompression device named L'DISQ. OBJECTIVES: The objectives of this study were to determine if L'DISQ could adequately reach certain target zones in the disc and to measure the distribution of rises in temperature in the surrounding tissue when the device was used to ablate the disc. METHODS: Placement of the wand of L'DISQ was attempted into the posterior annulus of the discs of four fresh human cadavers. During disc ablation, thermocouple probes were used to measure the temperature within the nucleus pulposus and annulus fibrosus, on the surface of the annulus, and on the posterior longitudinal ligament. Tissues harvested from around the disc were examined histologically. RESULTS: The tip of the wand could be successfully navigated to the posterolateral or posterocentral annulus at all levels above L5-S1 using a lateral approach. Rises in temperature did not exceed 13.25 ± 0.84°C within the disc, and did not exceed 1°C on the surface of the disc. Histology demonstrated no thermal damage to the surrounding neural tissues. CONCLUSION: L'DISQ can be successfully navigated to the target zones, and disc tissue ablated without thermal or structural damage to the adjacent neural tissues.

Suppressive effect of zinc on the formation of colonic preneoplastic lesions in the mouse fed high levels of dietary iron.

We investigated the effect of zinc on the formation of colonic aberrant crypt foci induced by azoxymethane (AOM) followed by dextran sodium sulfate (DSS) in mice with high iron diet (HFe; 450 ppm iron). Sixweek old ICR mice were fed on high iron diets with combination of three different levels of zinc in diets, low-zinc (LZn; 0.01 ppm), medium-zinc (MZn; 0.1 ppm), and high-zinc (HZn; 1 ppm) for 12 weeks. Animals were received weekly intraperitoneal injections of AOM (10 mg/kg B.W. in saline) for 3 weeks followed by 2% DSS (molecular weight 36,000~50,000) in the drinking water for a week. To confirm the iron storage in the body, the hepatic iron concentration has been determine chemically and compared with histological assessment visualized by Prussian blue reaction. Aberrant crypt (AC) and aberrant crypt foci (ACF) were analyzed in the colonic mucosa of mouse fed high dietary iron. Superoxide dismutase (SOD) activity and thiobarbituric acid-reactive substances (TBARS) level were also investigated. Apoptosis in the preneoplastic lesion was determined by terminal deoxynucleotidyl transferase-mediated dUTP nickend labeling (TUNEL). In addition, immunohistochemistry of ß-catenin was also performed on the mucous membrane of colon. The number of large ACF (≥ 4 AC/ACF), which possess greater tumorigenic potential, was significantly lower in MZn and HZn groups compared with LZn group. Cytosolic SOD activity in the liver was significantly higher in HZn group compared with LZn group. Hepatic MDA level was decreased significantly in HZn group compared with MZn and LZn groups. Apoptotic index was significantly higher in HZn group. Taken together, these findings indicate that dietary zinc might exert a protective effect against colonic preneoplastic lesion induced by AOM/DSS in ICR mice with high iron status, and suggest that dietary supplement of zinc might play a role in suppressing colon carcinogenesis in mice.